Ruby FFI implementation (#13343)

Supersedes #11483.

Closes #13343

COPYBARA_INTEGRATE_REVIEW=https://github.com/protocolbuffers/protobuf/pull/13343 from protocolbuffers:simultaneous_ffi bcb4bb7842
PiperOrigin-RevId: 550782245

.github/workflows/test_ruby.yml

@@ -17,17 +17,20 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - { name: Ruby 2.7, ruby: ruby-2.7.0, bazel: 5.1.1}
+          # Test both FFI and Native implementations on the highest and lowest
+          # Ruby versions for CRuby and JRuby, but only on Bazel 5.x.
+          - { name: Ruby 2.7, ruby: ruby-2.7.0, bazel: 5.1.1, ffi: NATIVE}
+          - { name: Ruby 2.7, ruby: ruby-2.7.0, bazel: 5.1.1, ffi: FFI}
           - { name: Ruby 3.0, ruby: ruby-3.0.2, bazel: 5.1.1}
           - { name: Ruby 3.1, ruby: ruby-3.1.0, bazel: 5.1.1}
-          - { name: Ruby 3.2, ruby: ruby-3.2.0, bazel: 5.1.1}
-          - { name: JRuby 9.2, ruby: jruby-9.2.20.1, bazel: 5.1.1}
-          - { name: JRuby 9.3, ruby: jruby-9.3.10.0, bazel: 5.1.1}
-          - { name: JRuby 9.4, ruby: jruby-9.4.3.0, bazel: 5.1.1}
+          - { name: Ruby 3.2, ruby: ruby-3.2.0, bazel: 5.1.1, ffi: NATIVE}
+          - { name: Ruby 3.2, ruby: ruby-3.2.0, bazel: 5.1.1, ffi: FFI}
+          - { name: JRuby 9.4, ruby: jruby-9.4.3.0, bazel: 5.1.1, ffi: NATIVE}
+          - { name: JRuby 9.4, ruby: jruby-9.4.3.0, bazel: 5.1.1, ffi: FFI}
           - { name: Ruby 2.7 (Bazel6), ruby: ruby-2.7.0, bazel: 6.0.0}
           - { name: JRuby 9.4 (Bazel6), ruby: jruby-9.4.3.0, bazel: 6.0.0}
 
-    name: Linux ${{ matrix.name }}
+    name: Linux ${{ matrix.name }}${{ matrix.ffi == 'FFI' && ' FFI' || '' }}
     runs-on: ubuntu-latest
     steps:
       - name: Checkout pending changes
@@ -40,7 +43,7 @@ jobs:
           image: ${{ matrix.image || format('us-docker.pkg.dev/protobuf-build/containers/test/linux/ruby:{0}-{1}-508417e5215994ade7585d28ba3aad681a25fa5d', matrix.ruby, matrix.bazel) }}
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
           bazel-cache: ruby_linux/${{ matrix.ruby }}_${{ matrix.bazel }}
-          bazel: test //ruby/... //ruby/tests:ruby_version --test_env=KOKORO_RUBY_VERSION
+          bazel: test //ruby/... //ruby/tests:ruby_version --test_env=KOKORO_RUBY_VERSION --test_env=BAZEL=true ${{ matrix.ffi == 'FFI' && '--//ruby:ffi=enabled --test_env=PROTOCOL_BUFFERS_RUBY_IMPLEMENTATION=FFI' || '' }}
 
   linux-aarch64:
     name: Linux aarch64
@@ -78,10 +81,18 @@ jobs:
     strategy:
       fail-fast: false   # Don't cancel all jobs if one fails.
       matrix:
-        # This is the full set of versions we support on MacOS.
-        version: [ "2.7", "3.0", "3.1", "3.2" ]
+        include:
+        # Test both FFI and Native implementations on the highest and lowest
+        # Ruby versions for CRuby, but only on Bazel 5.x.
+        # Quote versions numbers otherwise 3.0 will render as 3
+        - { version: "2.7", ffi: NATIVE }
+        - { version: "2.7", ffi: FFI }
+        - { version: "3.0" }
+        - { version: "3.1" }
+        - { version: "3.2", ffi: NATIVE }
+        - { version: "3.2", ffi: FFI }
 
-    name: MacOS Ruby ${{ matrix.version }}
+    name: MacOS Ruby ${{ matrix.version }}${{ matrix.ffi == 'FFI' && ' FFI' || '' }}
     runs-on: macos-12
     steps:
       - name: Checkout pending changes
@@ -102,23 +113,26 @@ jobs:
         with:
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
           bazel-cache: ruby_macos/${{ matrix.version }}
-          bazel: test //ruby/... --test_env=KOKORO_RUBY_VERSION=${{ matrix.version }}
+          bazel: test //ruby/... --test_env=KOKORO_RUBY_VERSION=${{ matrix.version }} --test_env=BAZEL=true ${{ matrix.ffi == 'FFI' && '--//ruby:ffi=enabled --test_env=PROTOCOL_BUFFERS_RUBY_IMPLEMENTATION=FFI' || '' }}
 
   test_ruby_gems:
     strategy:
       fail-fast: false
       matrix:
         include:
-          - { name: Ruby 2.7, ruby: ruby-2.7.0, bazel: 5.1.1}
+          # Test both FFI and Native implementations on the highest and lowest
+          # Ruby versions for CRuby and JRuby, but only on Bazel 5.x.
+          - { name: Ruby 2.7, ruby: ruby-2.7.0, bazel: 5.1.1, ffi: NATIVE }
+          - { name: Ruby 2.7, ruby: ruby-2.7.0, bazel: 5.1.1, ffi: FFI }
           - { name: Ruby 3.0, ruby: ruby-3.0.2, bazel: 5.1.1}
           - { name: Ruby 3.1, ruby: ruby-3.1.0, bazel: 5.1.1}
-          - { name: Ruby 3.2, ruby: ruby-3.2.0, bazel: 5.1.1}
-          - { name: JRuby 9.2, ruby: jruby-9.2.20.1, bazel: 5.1.1}
-          - { name: JRuby 9.3, ruby: jruby-9.3.10.0, bazel: 5.1.1}
-          - { name: JRuby 9.4, ruby: jruby-9.4.3.0, bazel: 5.1.1}
+          - { name: Ruby 3.2, ruby: ruby-3.2.0, bazel: 5.1.1, ffi: NATIVE }
+          - { name: Ruby 3.2, ruby: ruby-3.2.0, bazel: 5.1.1, ffi: FFI }
+          - { name: JRuby 9.4, ruby: jruby-9.4.3.0, bazel: 5.1.1, ffi: NATIVE }
+          - { name: JRuby 9.4, ruby: jruby-9.4.3.0, bazel: 5.1.1, ffi: FFI }
           - { name: Ruby 2.7 (Bazel6), ruby: ruby-2.7.0, bazel: 6.0.0}
           - { name: JRuby 9.4 (Bazel6), ruby: jruby-9.4.3.0, bazel: 6.0.0}
-    name: Install ${{ matrix.name }}
+    name: Install ${{ matrix.name }}${{ matrix.ffi == 'FFI' && ' FFI' || '' }}
     runs-on: ubuntu-latest
     steps:
       - name: Checkout pending changes
@@ -134,8 +148,9 @@ jobs:
           bash: >
             bazel --version;
             ruby --version;
-            bazel build //ruby:release //:protoc $BAZEL_FLAGS;
+            bazel build //ruby:release //:protoc ${{ matrix.ffi == 'FFI' && '--//ruby:ffi=enabled' || '' }} $BAZEL_FLAGS;
             gem install bazel-bin/ruby/google-protobuf-*;
             bazel-bin/protoc --proto_path=src --proto_path=ruby/tests --proto_path=ruby --ruby_out=ruby tests/test_import_proto2.proto;
             bazel-bin/protoc --proto_path=src --proto_path=ruby/tests --proto_path=ruby --ruby_out=ruby tests/basic_test.proto;
-            ruby ruby/tests/basic.rb
+            ${{ matrix.ffi == 'FFI' && 'PROTOCOL_BUFFERS_RUBY_IMPLEMENTATION=FFI' || '' }} ruby ruby/tests/basic.rb;
+            ${{ matrix.ffi == 'FFI' && 'PROTOCOL_BUFFERS_RUBY_IMPLEMENTATION=FFI' || '' }} ruby ruby/tests/implementation.rb

conformance/BUILD.bazel

@@ -24,6 +24,7 @@ exports_files([
     "failure_list_python_cpp.txt",
     "failure_list_ruby.txt",
     "failure_list_jruby.txt",
+    "failure_list_jruby_ffi.txt",
     "text_format_failure_list_cpp.txt",
     "text_format_failure_list_csharp.txt",
     "text_format_failure_list_java.txt",
@@ -34,6 +35,7 @@ exports_files([
     "text_format_failure_list_python_cpp.txt",
     "text_format_failure_list_ruby.txt",
     "text_format_failure_list_jruby.txt",
+    "text_format_failure_list_jruby_ffi.txt",
 ])
 
 cc_proto_library(
@@ -326,12 +328,12 @@ ruby_binary(
     name = "conformance_ruby",
     testonly = True,
     srcs = ["conformance_ruby.rb"],
+    visibility = ["//ruby:__subpackages__"],
     deps = [
         ":conformance_ruby_proto",
         "//:test_messages_proto2_ruby_proto",
-        "//:test_messages_proto3_ruby_proto",        
+        "//:test_messages_proto3_ruby_proto",
     ],
-    visibility = ["//ruby:__subpackages__"],
 )
 
 ################################################################################

conformance/failure_list_jruby_ffi.txt

@@ -0,0 +1,2 @@
+Recommended.Proto3.JsonInput.IgnoreUnknownEnumStringValueInMapValue.ProtobufOutput
+Recommended.Proto3.JsonInput.IgnoreUnknownEnumStringValueInRepeatedField.ProtobufOutput

protobuf_deps.bzl

@@ -110,8 +110,8 @@ def protobuf_deps():
         _github_archive(
             name = "rules_ruby",
             repo = "https://github.com/protocolbuffers/rules_ruby",
-            commit = "8fca842a3006c3d637114aba4f6bf9695bb3a432",
-            sha256 = "2619f9a23cee6f6a198d9ef284b6f6cbc901545ee9a9aac9ffa6b83dbf17cf0c",
+            commit = "b7f3e9756f3c45527be27bc38840d5a1ba690436",
+            sha256 = "347927fd8de6132099fcdc58e8f7eab7bde4eb2fd424546b9cd4f1c6f8f8bad8",
         )
 
     if not native.existing_rule("rules_jvm_external"):

ruby/.gitignore

@@ -6,4 +6,10 @@ protobuf-jruby.iml
 target/
 pkg/
 tmp/
-tests/google/
+tests/google/
+ext/google/protobuf_c/third_party/utf8_range/utf8_range.h
+ext/google/protobuf_c/third_party/utf8_range/range2-sse.c
+ext/google/protobuf_c/third_party/utf8_range/range2-neon.c
+ext/google/protobuf_c/third_party/utf8_range/naive.c
+ext/google/protobuf_c/third_party/utf8_range/LICENSE
+lib/google/protobuf/*_pb.rb

ruby/BUILD.bazel

@@ -2,6 +2,8 @@
 #
 # See also code generation logic under /src/google/protobuf/compiler/ruby.
 
+load("@bazel_skylib//lib:selects.bzl", "selects")
+load("@bazel_skylib//rules:common_settings.bzl", "string_flag")
 load("@rules_pkg//:mappings.bzl", "pkg_files", "strip_prefix")
 load("@rules_ruby//ruby:defs.bzl", "ruby_library")
 load("//build_defs:internal_shell.bzl", "inline_sh_binary")
@@ -13,12 +15,83 @@ load("//:protobuf_version.bzl", "PROTOBUF_RUBY_VERSION")
 # Ruby Runtime
 ################################################################################
 
+string_flag(
+    name = "ffi",
+    build_setting_default = "disabled",
+    values = [
+        "enabled",
+        "disabled",
+    ],
+)
+
+config_setting(
+    name = "ffi_enabled",
+    flag_values = {
+        ":ffi": "enabled",
+    },
+)
+
+config_setting(
+    name = "ffi_disabled",
+    flag_values = {
+        ":ffi": "disabled",
+    },
+)
+
+selects.config_setting_group(
+    name = "jruby_ffi",
+    match_all = [
+        ":ffi_enabled",
+        "@rules_ruby//ruby/runtime:config_jruby",
+    ],
+)
+
+selects.config_setting_group(
+    name = "jruby_native",
+    match_all = [
+        ":ffi_disabled",
+        "@rules_ruby//ruby/runtime:config_jruby",
+    ],
+)
+
+selects.config_setting_group(
+    name = "ruby_ffi",
+    match_all = [
+        ":ffi_enabled",
+        "@rules_ruby//ruby/runtime:config_ruby",
+    ],
+)
+
+selects.config_setting_group(
+    name = "ruby_native",
+    match_all = [
+        ":ffi_disabled",
+        "@rules_ruby//ruby/runtime:config_ruby",
+    ],
+)
+
+selects.config_setting_group(
+    name = "macos_ffi_enabled",
+    match_all = [
+        ":ffi_enabled",
+        "@platforms//os:osx",
+    ],
+)
+
+selects.config_setting_group(
+    name = "linux_ffi_enabled",
+    match_all = [
+        ":ffi_enabled",
+        "@platforms//os:linux",
+    ],
+)
+
 ruby_library(
     name = "protobuf",
-    deps = ["//ruby/lib/google:protobuf_lib"],
     visibility = [
         "//visibility:public",
     ],
+    deps = ["//ruby/lib/google:protobuf_lib"],
 )
 
 # Note: these can be greatly simplified using inline_sh_binary in Bazel 6,
@@ -27,18 +100,25 @@ ruby_library(
 genrule(
     name = "jruby_release",
     srcs = [
-      "//ruby/lib/google:copy_jar",
-      "//ruby/lib/google:dist_files",
-      "//:well_known_ruby_protos",
-      "google-protobuf.gemspec",
+        "@utf8_range//:utf8_range_srcs",
+        "@utf8_range//:LICENSE",
+        "//ruby/lib/google:copy_jar",
+        "//ruby/lib/google:dist_files",
+        "//ruby/ext/google/protobuf_c:dist_files",
+        "//:well_known_ruby_protos",
+        "google-protobuf.gemspec",
     ],
-    outs = ["google-protobuf-"+PROTOBUF_RUBY_VERSION+"-java.gem"],
+    outs = ["google-protobuf-" + PROTOBUF_RUBY_VERSION + "-java.gem"],
     cmd = """
         set -eux
         mkdir tmp
         for src in $(SRCS); do
             cp --parents -L "$$src" tmp
         done
+        mkdir -p "tmp/ruby/ext/google/protobuf_c/third_party/utf8_range"
+        for utf in $(execpaths @utf8_range//:utf8_range_srcs) $(execpath @utf8_range//:LICENSE); do
+            mv "tmp/$$utf" "tmp/ruby/ext/google/protobuf_c/third_party/utf8_range"
+        done
         for wkt in $(execpaths //:well_known_ruby_protos); do
             mv "tmp/$$wkt" "tmp/ruby/lib/google/protobuf/"
         done
@@ -59,14 +139,14 @@ genrule(
 genrule(
     name = "ruby_release",
     srcs = [
-      "@utf8_range//:utf8_range_srcs",
-      "@utf8_range//:LICENSE",
-      "//:well_known_ruby_protos",
-      "//ruby/ext/google/protobuf_c:dist_files",
-      "//ruby/lib/google:dist_files",
-      "google-protobuf.gemspec",
+        "@utf8_range//:utf8_range_srcs",
+        "@utf8_range//:LICENSE",
+        "//:well_known_ruby_protos",
+        "//ruby/ext/google/protobuf_c:dist_files",
+        "//ruby/lib/google:dist_files",
+        "google-protobuf.gemspec",
     ],
-    outs = ["google-protobuf-"+PROTOBUF_RUBY_VERSION+".gem"],
+    outs = ["google-protobuf-" + PROTOBUF_RUBY_VERSION + ".gem"],
     cmd = """
         set -eux
         mkdir tmp
@@ -102,7 +182,6 @@ filegroup(
     tags = ["manual"],
 )
 
-
 ################################################################################
 # Tests
 ################################################################################
@@ -111,34 +190,65 @@ filegroup(
 internal_ruby_proto_library(
     name = "test_ruby_protos",
     srcs = ["//ruby/tests:test_protos"],
-    deps = ["//:well_known_ruby_protos"],
-    includes = [".", "src", "ruby/tests"],
+    includes = [
+        ".",
+        "ruby/tests",
+        "src",
+    ],
     visibility = [
         "//ruby:__subpackages__",
     ],
+    deps = ["//:well_known_ruby_protos"],
 )
 
-
 conformance_test(
     name = "conformance_test",
     failure_list = "//conformance:failure_list_ruby.txt",
-    testee = "//conformance:conformance_ruby",
-    text_format_failure_list = "//conformance:text_format_failure_list_ruby.txt",
     target_compatible_with = select({
-        "@rules_ruby//ruby/runtime:config_ruby": [],
+        ":ruby_native": [],
         "//conditions:default": ["@platforms//:incompatible"],
     }),
+    testee = "//conformance:conformance_ruby",
+    text_format_failure_list = "//conformance:text_format_failure_list_ruby.txt",
+)
+
+conformance_test(
+    name = "conformance_test_ffi",
+    env = {
+        "PROTOCOL_BUFFERS_RUBY_IMPLEMENTATION": "ffi",
+    },
+    failure_list = "//conformance:failure_list_ruby.txt",
+    target_compatible_with = select({
+        ":ruby_ffi": [],
+        "//conditions:default": ["@platforms//:incompatible"],
+    }),
+    testee = "//conformance:conformance_ruby",
+    text_format_failure_list = "//conformance:text_format_failure_list_ruby.txt",
 )
 
 conformance_test(
     name = "conformance_test_jruby",
     failure_list = "//conformance:failure_list_jruby.txt",
-    testee = "//conformance:conformance_ruby",
-    text_format_failure_list = "//conformance:text_format_failure_list_jruby.txt",
     target_compatible_with = select({
-        "@rules_ruby//ruby/runtime:config_jruby": [],
+        ":jruby_native": [],
         "//conditions:default": ["@platforms//:incompatible"],
     }),
+    testee = "//conformance:conformance_ruby",
+    text_format_failure_list = "//conformance:text_format_failure_list_jruby.txt",
+)
+
+conformance_test(
+    name = "conformance_test_jruby_ffi",
+    env = {
+        "PROTOCOL_BUFFERS_RUBY_IMPLEMENTATION": "ffi",
+    },
+    failure_list = "//conformance:failure_list_jruby_ffi.txt",
+    target_compatible_with = select({
+        ":jruby_ffi": [],
+        "//conditions:default": ["@platforms//:incompatible"],
+    }),
+    testee = "//conformance:conformance_ruby",
+    text_format_failure_list = "//conformance:text_format_failure_list_jruby.txt",
 )
 
 ################################################################################
@@ -148,15 +258,15 @@ conformance_test(
 pkg_files(
     name = "dist_files",
     srcs = [
+        ".gitignore",
+        "BUILD.bazel",
+        "Gemfile",
+        "README.md",
+        "Rakefile",
         "//ruby/ext/google/protobuf_c:dist_files",
         "//ruby/lib/google:dist_files",
         "//ruby/src/main/java:dist_files",
         "//ruby/tests:dist_files",
-        ".gitignore",
-        "BUILD.bazel",
-        "Gemfile",
-        "Rakefile",
-        "README.md",
     ],
     strip_prefix = strip_prefix.from_root(""),
     visibility = ["//pkg:__pkg__"],

ruby/README.md

@@ -2,10 +2,11 @@ This directory contains the Ruby extension that implements Protocol Buffers
 functionality in Ruby.
 
 The Ruby extension makes use of generated Ruby code that defines message and
-enum types in a Ruby DSL. You may write definitions in this DSL directly, but
-we recommend using protoc's Ruby generation support with .proto files. The
-build process in this directory only installs the extension; you need to
-install protoc as well to have Ruby code generation functionality.
+enum types in a Ruby DSL. You may write definitions in this DSL directly, but we
+recommend using protoc's Ruby generation support with .proto files. The build
+process in this directory only installs the extension; you need to install
+protoc as well to have Ruby code generation functionality. You can build protoc
+from source using `bazel build //:protoc`.
 
 Installation from Gem
 ---------------------
@@ -50,6 +51,18 @@ puts MyTestMessage.encode_json(mymessage)
 
 Installation from Source (Building Gem)
 ---------------------------------------
+ 
+
+Protocol Buffers has a new experimental backend that uses the
+[ffi](https://github.com/ffi/ffi) gem to provide a unified C-based
+implementation across Ruby interpreters based on
+[UPB](https://github.com/protocolbuffers/upb). For now, use of the FFI
+implementation is opt-in. If any of the following are true, the traditional
+platform-native implementations (MRI-ruby based on CRuby, Java based on JRuby)
+are used instead of the new FFI-based implementation: 1. `ffi` and
+`ffi-compiler` gems are not installed 2. `PROTOCOL_BUFFERS_RUBY_IMPLEMENTATION`
+environment variable has a value other than `FFI` (case-insensitive). 3. FFI is
+unable to load the native library at runtime.
 
 To build this Ruby extension, you will need:
 
@@ -81,6 +94,12 @@ To run the specs:
 
     $ rake test
 
+To run the specs while using the FFI-based implementation:
+
+```
+$ PROTOCOL_BUFFERS_RUBY_IMPLEMENTATION=FFI rake test
+```
+
 This gem includes the upb parsing and serialization library as a single-file
 amalgamation. It is up-to-date with upb git commit
 `535bc2fe2f2b467f59347ffc9449e11e47791257`.
@@ -93,6 +112,12 @@ From the project root (rather than the `ruby` directory):
 $ bazel test //ruby/tests/...
 ```
 
+To run tests against the FFI implementation:
+
+```
+$ bazel test //ruby/tests/... //ruby:ffi=enabled --test_env=PROTOCOL_BUFFERS_RUBY_IMPLEMENTATION=FFI
+```
+
 Version Number Scheme
 ---------------------
 

ruby/Rakefile

@@ -2,6 +2,7 @@ require "rubygems"
 require "rubygems/package_task"
 require "rake/extensiontask" unless RUBY_PLATFORM == "java"
 require "rake/testtask"
+import 'lib/google/tasks/ffi.rake'
 
 spec = Gem::Specification.load("google-protobuf.gemspec")
 
@@ -68,6 +69,24 @@ unless ENV['IN_DOCKER'] == 'true' or ENV['BAZEL'] == 'true'
   end
 end
 
+task :copy_third_party do
+  unless File.exist? 'ext/google/protobuf_c/third_party/utf8_range'
+    FileUtils.mkdir_p 'ext/google/protobuf_c/third_party/utf8_range'
+    # We need utf8_range in-tree.
+    if  ENV['BAZEL'] == 'true'
+      utf8_root = '../external/utf8_range'
+    else
+      utf8_root = '../third_party/utf8_range'
+    end
+    %w[
+      utf8_range.h naive.c range2-neon.c range2-neon.c range2-sse.c LICENSE
+    ].each do |file|
+      FileUtils.cp File.join(utf8_root, file),
+                   "ext/google/protobuf_c/third_party/utf8_range"
+    end
+  end
+end
+
 if RUBY_PLATFORM == "java"
   task :clean => :require_mvn do
     system("mvn --batch-mode clean")
@@ -82,20 +101,6 @@ if RUBY_PLATFORM == "java"
   end
 
 else
-  unless ENV['IN_DOCKER'] == 'true'
-    # We need utf8_range in-tree.
-    if  ENV['BAZEL'] == 'true'
-      utf8_root = '../external/utf8_range'
-    else
-      utf8_root = '../third_party/utf8_range'
-    end
-    FileUtils.mkdir_p("ext/google/protobuf_c")
-    FileUtils.cp(utf8_root+"/utf8_range.h", "ext/google/protobuf_c")
-    FileUtils.cp(utf8_root+"/naive.c", "ext/google/protobuf_c")
-    FileUtils.cp(utf8_root+"/range2-neon.c", "ext/google/protobuf_c")
-    FileUtils.cp(utf8_root+"/range2-sse.c", "ext/google/protobuf_c")
-  end
-
   Rake::ExtensionTask.new("protobuf_c", spec) do |ext|
     unless RUBY_PLATFORM =~ /darwin/
       # TODO: also set "no_native to true" for mac if possible. As is,
@@ -133,7 +138,7 @@ else
     ['x86-mingw32', 'x64-mingw32', 'x64-mingw-ucrt', 'x86_64-linux', 'x86-linux'].each do |plat|
       RakeCompilerDock.sh <<-"EOT", platform: plat
         bundle && \
-        IN_DOCKER=true rake native:#{plat} pkg/#{spec.full_name}-#{plat}.gem RUBY_CC_VERSION=3.1.0:3.0.0:2.7.0:2.6.0
+        IN_DOCKER=true rake native:#{plat} pkg/#{spec.full_name}-#{plat}.gem RUBY_CC_VERSION=3.1.0:3.0.0:2.7.0
       EOT
     end
   end
@@ -141,7 +146,7 @@ else
   if RUBY_PLATFORM =~ /darwin/
     task 'gem:native' do
       system "rake genproto"
-      system "rake cross native gem RUBY_CC_VERSION=3.1.0:3.0.0:2.7.0:2.6.0"
+      system "rake cross native gem RUBY_CC_VERSION=3.1.0:3.0.0:2.7.0"
     end
   else
     task 'gem:native' => [:genproto, 'gem:windows', 'gem:java']
@@ -152,6 +157,14 @@ task :genproto => genproto_output
 
 task :clean do
   sh "rm -f #{genproto_output.join(' ')}"
+  sh "rm -f google-protobuf-*gem"
+  sh "rm -f Gemfile.lock"
+  sh "rm -rf pkg"
+  sh "rm -rf tmp"
+  # Handles third_party and any platform specific directories built by FFI
+  Pathname('ext/google/protobuf_c').children.select(&:directory?).each do |dir|
+    sh "rm -rf #{dir}"
+  end
 end
 
 Gem::PackageTask.new(spec) do |pkg|
@@ -169,7 +182,8 @@ Rake::TestTask.new(:gc_test => ENV['BAZEL'] == 'true' ? [] : :build) do |t|
   t.test_files = FileList["tests/gc_test.rb"]
 end
 
-task :build => [:clean, :genproto, :compile]
+task :build => [:clean, :genproto, :copy_third_party, :compile, :"ffi-protobuf:default"]
+Rake::Task[:gem].enhance [:copy_third_party, :genproto]
 task :default => [:build]
 
 # vim:sw=2:et

ruby/ext/google/protobuf_c/BUILD.bazel

@@ -6,22 +6,106 @@ package(default_visibility = ["//ruby:__subpackages__"])
 
 cc_library(
     name = "protobuf_c",
-    srcs = glob([
-        "*.h",
-        "*.c",
-    ]),
-    deps = [
-        "@rules_ruby//ruby/runtime:headers",
-        "@utf8_range//:utf8_range",
+    srcs = [
+        "convert.c",
+        "convert.h",
+        "defs.c",
+        "defs.h",
+        "map.c",
+        "map.h",
+        "message.c",
+        "message.h",
+        "protobuf.c",
+        "protobuf.h",
+        "repeated_field.c",
+        "repeated_field.h",
+        "ruby-upb.c",
+        "ruby-upb.h",
+        "shared_convert.c",
+        "shared_convert.h",
+        "shared_message.c",
+        "shared_message.h",
+        "wrap_memcpy.c",
     ],
+    linkstatic = True,
     target_compatible_with = select({
         "@rules_ruby//ruby/runtime:config_jruby": ["@platforms//:incompatible"],
         "//conditions:default": [],
     }),
-    linkstatic = True,
+    deps = [
+        "@rules_ruby//ruby/runtime:headers",
+        "@utf8_range",
+    ],
     alwayslink = True,
 )
 
+# Needs to be compiled with UPB_BUILD_API in order to expose functions called
+# via FFI directly by Ruby.
+cc_library(
+    name = "upb_api",
+    srcs = [
+        "ruby-upb.c",
+    ],
+    hdrs = [
+        "ruby-upb.h",
+    ],
+    copts = ["-fvisibility=hidden"],
+    linkstatic = False,
+    local_defines = [
+        "UPB_BUILD_API",
+    ],
+    target_compatible_with = select({
+        "//ruby:ffi_disabled": ["@platforms//:incompatible"],
+        "//conditions:default": [],
+    }),
+    deps = [
+        "@utf8_range",
+    ],
+)
+
+cc_library(
+    name = "protobuf_c_ffi",
+    srcs = [
+        "glue.c",
+        "shared_convert.c",
+        "shared_convert.h",
+        "shared_message.c",
+        "shared_message.h",
+    ],
+    copts = [
+        "-std=gnu99",
+        "-O3",
+        "-Wall",
+        "-Wsign-compare",
+        "-Wno-declaration-after-statement",
+    ],
+    linkstatic = True,
+    local_defines = [
+        "NDEBUG",
+    ],
+    target_compatible_with = select({
+        "//ruby:ffi_disabled": ["@platforms//:incompatible"],
+        "//conditions:default": [],
+    }),
+    deps = [":upb_api"],
+    alwayslink = 1,
+)
+
+apple_binary(
+    name = "ffi_bundle",
+    binary_type = "loadable_bundle",
+    linkopts = [
+        "-undefined,dynamic_lookup",
+        "-multiply_defined,suppress",
+    ],
+    minimum_os_version = "10.11",
+    platform_type = "macos",
+    tags = ["manual"],
+    deps = [
+        ":protobuf_c_ffi",
+    ],
+)
+
 apple_binary(
     name = "bundle",
     binary_type = "loadable_bundle",
@@ -29,8 +113,8 @@ apple_binary(
         "-undefined,dynamic_lookup",
         "-multiply_defined,suppress",
     ],
-    platform_type = "macos",
     minimum_os_version = "10.11",
+    platform_type = "macos",
     tags = ["manual"],
     deps = [
         ":protobuf_c",
@@ -43,6 +127,7 @@ pkg_files(
         "*.h",
         "*.c",
         "*.rb",
+        "Rakefile",
     ]),
     strip_prefix = strip_prefix.from_root(""),
     visibility = ["//ruby:__pkg__"],
@@ -65,8 +150,8 @@ genrule(
 staleness_test(
     name = "test_amalgamation_staleness",
     outs = [
-        "ruby-upb.h",
         "ruby-upb.c",
+        "ruby-upb.h",
     ],
     generated_pattern = "generated-in/%s",
 )

ruby/ext/google/protobuf_c/Rakefile

@@ -0,0 +1,3 @@
+import '../../../lib/google/tasks/ffi.rake'
+
+task default: ['ffi-protobuf:default']

ruby/ext/google/protobuf_c/convert.c

@@ -41,6 +41,7 @@
 
 #include "message.h"
 #include "protobuf.h"
+#include "shared_convert.h"
 
 static upb_StringView Convert_StringData(VALUE str, upb_Arena* arena) {
   upb_StringView ret;
@@ -111,8 +112,7 @@ static int32_t Convert_ToEnum(VALUE value, const char* name,
     case T_SYMBOL: {
       const upb_EnumValueDef* ev =
           upb_EnumDef_FindValueByName(e, rb_id2name(SYM2ID(value)));
-      if (!ev)
-        goto unknownval;
+      if (!ev) goto unknownval;
       val = upb_EnumValueDef_Number(ev);
       break;
     }
@@ -255,7 +255,7 @@ VALUE Convert_UpbToRuby(upb_MessageValue upb_val, TypeInfo type_info,
     case kUpb_CType_UInt64:
       return ULL2NUM(upb_val.int64_val);
     case kUpb_CType_Enum: {
-      const upb_EnumValueDef *ev = upb_EnumDef_FindValueByNumber(
+      const upb_EnumValueDef* ev = upb_EnumDef_FindValueByNumber(
           type_info.def.enumdef, upb_val.int32_val);
       if (ev) {
         return ID2SYM(rb_intern(upb_EnumValueDef_Name(ev)));
@@ -312,50 +312,26 @@ upb_MessageValue Msgval_DeepCopy(upb_MessageValue msgval, TypeInfo type_info,
 
 bool Msgval_IsEqual(upb_MessageValue val1, upb_MessageValue val2,
                     TypeInfo type_info) {
-  switch (type_info.type) {
-    case kUpb_CType_Bool:
-      return memcmp(&val1, &val2, 1) == 0;
-    case kUpb_CType_Float:
-    case kUpb_CType_Int32:
-    case kUpb_CType_UInt32:
-    case kUpb_CType_Enum:
-      return memcmp(&val1, &val2, 4) == 0;
-    case kUpb_CType_Double:
-    case kUpb_CType_Int64:
-    case kUpb_CType_UInt64:
-      return memcmp(&val1, &val2, 8) == 0;
-    case kUpb_CType_String:
-    case kUpb_CType_Bytes:
-      return val1.str_val.size == val2.str_val.size &&
-             memcmp(val1.str_val.data, val2.str_val.data, val1.str_val.size) ==
-                 0;
-    case kUpb_CType_Message:
-      return Message_Equal(val1.msg_val, val2.msg_val, type_info.def.msgdef);
-    default:
-      rb_raise(rb_eRuntimeError, "Internal error, unexpected type");
+  upb_Status status;
+  upb_Status_Clear(&status);
+  bool return_value = shared_Msgval_IsEqual(val1, val2, type_info.type,
+                                            type_info.def.msgdef, &status);
+  if (upb_Status_IsOk(&status)) {
+    return return_value;
+  } else {
+    rb_raise(rb_eRuntimeError, upb_Status_ErrorMessage(&status));
   }
 }
 
 uint64_t Msgval_GetHash(upb_MessageValue val, TypeInfo type_info,
                         uint64_t seed) {
-  switch (type_info.type) {
-    case kUpb_CType_Bool:
-      return _upb_Hash(&val, 1, seed);
-    case kUpb_CType_Float:
-    case kUpb_CType_Int32:
-    case kUpb_CType_UInt32:
-    case kUpb_CType_Enum:
-      return _upb_Hash(&val, 4, seed);
-    case kUpb_CType_Double:
-    case kUpb_CType_Int64:
-    case kUpb_CType_UInt64:
-      return _upb_Hash(&val, 8, seed);
-    case kUpb_CType_String:
-    case kUpb_CType_Bytes:
-      return _upb_Hash(val.str_val.data, val.str_val.size, seed);
-    case kUpb_CType_Message:
-      return Message_Hash(val.msg_val, type_info.def.msgdef, seed);
-    default:
-      rb_raise(rb_eRuntimeError, "Internal error, unexpected type");
+  upb_Status status;
+  upb_Status_Clear(&status);
+  uint64_t return_value = shared_Msgval_GetHash(
+      val, type_info.type, type_info.def.msgdef, seed, &status);
+  if (upb_Status_IsOk(&status)) {
+    return return_value;
+  } else {
+    rb_raise(rb_eRuntimeError, upb_Status_ErrorMessage(&status));
   }
 }

ruby/ext/google/protobuf_c/extconf.rb

@@ -22,6 +22,7 @@ $INCFLAGS += " -I$(srcdir)/third_party/utf8_range"
 
 $srcs = ["protobuf.c", "convert.c", "defs.c", "message.c",
          "repeated_field.c", "map.c", "ruby-upb.c", "wrap_memcpy.c",
-         "naive.c", "range2-neon.c", "range2-sse.c"]
+         "naive.c", "range2-neon.c", "range2-sse.c", "shared_convert.c",
+         "shared_message.c"]
 
 create_makefile(ext_name)

ruby/ext/google/protobuf_c/glue.c

@@ -0,0 +1,44 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2023 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// -----------------------------------------------------------------------------
+// Exposing inlined UPB functions. Strictly free of dependencies on
+// Ruby interpreter internals.
+
+#include "ruby-upb.h"
+
+upb_Arena* Arena_create() { return upb_Arena_Init(NULL, 0, &upb_alloc_global); }
+
+google_protobuf_FileDescriptorProto* FileDescriptorProto_parse(
+    const char* serialized_file_proto, size_t length) {
+  upb_Arena* arena = Arena_create();
+  return google_protobuf_FileDescriptorProto_parse(serialized_file_proto,
+                                                   length, arena);
+}

ruby/ext/google/protobuf_c/message.c

@@ -35,6 +35,7 @@
 #include "map.h"
 #include "protobuf.h"
 #include "repeated_field.h"
+#include "shared_message.h"
 
 static VALUE cParseError = Qnil;
 static VALUE cAbstractMessage = Qnil;
@@ -694,29 +695,13 @@ static VALUE Message_dup(VALUE _self) {
 // Support function for Message_eq, and also used by other #eq functions.
 bool Message_Equal(const upb_Message* m1, const upb_Message* m2,
                    const upb_MessageDef* m) {
-  if (m1 == m2) return true;
-
-  size_t size1, size2;
-  int encode_opts =
-      kUpb_EncodeOption_SkipUnknown | kUpb_EncodeOption_Deterministic;
-  upb_Arena* arena_tmp = upb_Arena_New();
-  const upb_MiniTable* layout = upb_MessageDef_MiniTable(m);
-
-  // Compare deterministically serialized payloads with no unknown fields.
-  char* data1;
-  char* data2;
-  upb_EncodeStatus status1 =
-      upb_Encode(m1, layout, encode_opts, arena_tmp, &data1, &size1);
-  upb_EncodeStatus status2 =
-      upb_Encode(m2, layout, encode_opts, arena_tmp, &data2, &size2);
-
-  if (status1 == kUpb_EncodeStatus_Ok && status2 == kUpb_EncodeStatus_Ok) {
-    bool ret = (size1 == size2) && (memcmp(data1, data2, size1) == 0);
-    upb_Arena_Free(arena_tmp);
-    return ret;
+  upb_Status status;
+  upb_Status_Clear(&status);
+  bool return_value = shared_Message_Equal(m1, m2, m, &status);
+  if (upb_Status_IsOk(&status)) {
+    return return_value;
   } else {
-    upb_Arena_Free(arena_tmp);
-    rb_raise(cParseError, "Error comparing messages");
+    rb_raise(cParseError, upb_Status_ErrorMessage(&status));
   }
 }
 
@@ -741,23 +726,13 @@ static VALUE Message_eq(VALUE _self, VALUE _other) {
 
 uint64_t Message_Hash(const upb_Message* msg, const upb_MessageDef* m,
                       uint64_t seed) {
-  upb_Arena* arena = upb_Arena_New();
-  char* data;
-  size_t size;
-
-  // Hash a deterministically serialized payloads with no unknown fields.
-  upb_EncodeStatus status = upb_Encode(
-      msg, upb_MessageDef_MiniTable(m),
-      kUpb_EncodeOption_SkipUnknown | kUpb_EncodeOption_Deterministic, arena,
-      &data, &size);
-
-  if (status == kUpb_EncodeStatus_Ok) {
-    uint64_t ret = _upb_Hash(data, size, seed);
-    upb_Arena_Free(arena);
-    return ret;
+  upb_Status status;
+  upb_Status_Clear(&status);
+  uint64_t return_value = shared_Message_Hash(msg, m, seed, &status);
+  if (upb_Status_IsOk(&status)) {
+    return return_value;
   } else {
-    upb_Arena_Free(arena);
-    rb_raise(cParseError, "Error calculating hash");
+    rb_raise(cParseError, upb_Status_ErrorMessage(&status));
   }
 }
 

ruby/ext/google/protobuf_c/shared_convert.c

@@ -0,0 +1,87 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2023 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// -----------------------------------------------------------------------------
+// Ruby <-> upb data conversion functions. Strictly free of dependencies on
+// Ruby interpreter internals.
+
+#include "shared_convert.h"
+
+bool shared_Msgval_IsEqual(upb_MessageValue val1, upb_MessageValue val2,
+                           upb_CType type, upb_MessageDef* msgdef,
+                           upb_Status* status) {
+  switch (type) {
+    case kUpb_CType_Bool:
+      return memcmp(&val1, &val2, 1) == 0;
+    case kUpb_CType_Float:
+    case kUpb_CType_Int32:
+    case kUpb_CType_UInt32:
+    case kUpb_CType_Enum:
+      return memcmp(&val1, &val2, 4) == 0;
+    case kUpb_CType_Double:
+    case kUpb_CType_Int64:
+    case kUpb_CType_UInt64:
+      return memcmp(&val1, &val2, 8) == 0;
+    case kUpb_CType_String:
+    case kUpb_CType_Bytes:
+      return val1.str_val.size == val2.str_val.size &&
+             memcmp(val1.str_val.data, val2.str_val.data, val1.str_val.size) ==
+                 0;
+    case kUpb_CType_Message:
+      return shared_Message_Equal(val1.msg_val, val2.msg_val, msgdef, status);
+    default:
+      upb_Status_SetErrorMessage(status, "Internal error, unexpected type");
+  }
+}
+
+uint64_t shared_Msgval_GetHash(upb_MessageValue val, upb_CType type,
+                               upb_MessageDef* msgdef, uint64_t seed,
+                               upb_Status* status) {
+  switch (type) {
+    case kUpb_CType_Bool:
+      return _upb_Hash(&val, 1, seed);
+    case kUpb_CType_Float:
+    case kUpb_CType_Int32:
+    case kUpb_CType_UInt32:
+    case kUpb_CType_Enum:
+      return _upb_Hash(&val, 4, seed);
+    case kUpb_CType_Double:
+    case kUpb_CType_Int64:
+    case kUpb_CType_UInt64:
+      return _upb_Hash(&val, 8, seed);
+    case kUpb_CType_String:
+    case kUpb_CType_Bytes:
+      return _upb_Hash(val.str_val.data, val.str_val.size, seed);
+    case kUpb_CType_Message:
+      return shared_Message_Hash(val.msg_val, msgdef, seed, status);
+    default:
+      upb_Status_SetErrorMessage(status, "Internal error, unexpected type");
+  }
+}

ruby/ext/google/protobuf_c/shared_convert.h

@@ -0,0 +1,49 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2023 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// -----------------------------------------------------------------------------
+// Ruby <-> upb data conversion functions. Strictly free of dependencies on
+// Ruby interpreter internals.
+
+#ifndef RUBY_PROTOBUF_SHARED_CONVERT_H_
+#define RUBY_PROTOBUF_SHARED_CONVERT_H_
+
+#include "ruby-upb.h"
+#include "shared_message.h"
+
+bool shared_Msgval_IsEqual(upb_MessageValue val1, upb_MessageValue val2,
+                           upb_CType type, upb_MessageDef* msgdef,
+                           upb_Status* status);
+
+uint64_t shared_Msgval_GetHash(upb_MessageValue val, upb_CType type,
+                               upb_MessageDef* msgdef, uint64_t seed,
+                               upb_Status* status);
+
+#endif  // RUBY_PROTOBUF_SHARED_CONVERT_H_

ruby/ext/google/protobuf_c/shared_message.c

@@ -0,0 +1,88 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2023 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// -----------------------------------------------------------------------------
+// Ruby Message functions. Strictly free of dependencies on
+// Ruby interpreter internals.
+
+#include "shared_message.h"
+
+// Support function for Message_Hash. Returns a hash value for the given
+// message.
+uint64_t shared_Message_Hash(const upb_Message* msg, const upb_MessageDef* m,
+                             uint64_t seed, upb_Status* status) {
+  upb_Arena* arena = upb_Arena_New();
+  char* data;
+  size_t size;
+
+  // Hash a deterministically serialized payloads with no unknown fields.
+  upb_EncodeStatus encode_status = upb_Encode(
+      msg, upb_MessageDef_MiniTable(m),
+      kUpb_EncodeOption_SkipUnknown | kUpb_EncodeOption_Deterministic, arena,
+      &data, &size);
+
+  if (encode_status == kUpb_EncodeStatus_Ok) {
+    uint64_t ret = _upb_Hash(data, size, seed);
+    upb_Arena_Free(arena);
+    return ret;
+  } else {
+    upb_Arena_Free(arena);
+    upb_Status_SetErrorMessage(status, "Error calculating hash");
+  }
+}
+
+// Support function for Message_Equal
+bool shared_Message_Equal(const upb_Message* m1, const upb_Message* m2,
+                          const upb_MessageDef* m, upb_Status* status) {
+  if (m1 == m2) return true;
+
+  size_t size1, size2;
+  int encode_opts =
+      kUpb_EncodeOption_SkipUnknown | kUpb_EncodeOption_Deterministic;
+  upb_Arena* arena_tmp = upb_Arena_New();
+  const upb_MiniTable* layout = upb_MessageDef_MiniTable(m);
+
+  // Compare deterministically serialized payloads with no unknown fields.
+  char* data1;
+  char* data2;
+  upb_EncodeStatus status1 =
+      upb_Encode(m1, layout, encode_opts, arena_tmp, &data1, &size1);
+  upb_EncodeStatus status2 =
+      upb_Encode(m2, layout, encode_opts, arena_tmp, &data2, &size2);
+
+  if (status1 == kUpb_EncodeStatus_Ok && status2 == kUpb_EncodeStatus_Ok) {
+    bool ret = (size1 == size2) && (memcmp(data1, data2, size1) == 0);
+    upb_Arena_Free(arena_tmp);
+    return ret;
+  } else {
+    upb_Arena_Free(arena_tmp);
+    upb_Status_SetErrorMessage(status, "Error comparing messages");
+  }
+}

ruby/ext/google/protobuf_c/shared_message.h

@@ -0,0 +1,48 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2023 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// -----------------------------------------------------------------------------
+// Ruby Message functions. Strictly free of dependencies on
+// Ruby interpreter internals.
+
+#ifndef RUBY_PROTOBUF_SHARED_MESSAGE_H_
+#define RUBY_PROTOBUF_SHARED_MESSAGE_H_
+
+#include "ruby-upb.h"
+
+// Returns a hash value for the given message.
+uint64_t shared_Message_Hash(const upb_Message* msg, const upb_MessageDef* m,
+                             uint64_t seed, upb_Status* status);
+
+// Returns true if these two messages are equal.
+bool shared_Message_Equal(const upb_Message* m1, const upb_Message* m2,
+                          const upb_MessageDef* m, upb_Status* status);
+
+#endif  // RUBY_PROTOBUF_SHARED_MESSAGE_H_

ruby/google-protobuf.gemspec

@@ -10,15 +10,31 @@ Gem::Specification.new do |s|
   s.email       = "protobuf@googlegroups.com"
   s.metadata    = { "source_code_uri" => "https://github.com/protocolbuffers/protobuf/tree/#{git_tag}/ruby" }
   s.require_paths = ["lib"]
-  s.files       = Dir.glob('lib/**/*.rb')
+  s.files       = Dir.glob('lib/**/*.{rb,rake}')
   if RUBY_PLATFORM == "java"
     s.platform  = "java"
-    s.files     += ["lib/google/protobuf_java.jar"]
+    s.files     += ["lib/google/protobuf_java.jar"] +
+      Dir.glob('ext/**/*').reject do |file|
+        File.basename(file) =~ /^((convert|defs|map|repeated_field)\.[ch]|
+                                   BUILD\.bazel|extconf\.rb|wrap_memcpy\.c)$/x
+      end
+    s.extensions = ["ext/google/protobuf_c/Rakefile"]
+    s.add_dependency "ffi", "~>1"
+    s.add_dependency "ffi-compiler", "~>1"
   else
-    s.files     += Dir.glob('ext/**/*')
-    s.extensions= ["ext/google/protobuf_c/extconf.rb"]
-    s.add_development_dependency "rake-compiler-dock", "= 1.2.1"  end
+    s.files     += Dir.glob('ext/**/*').reject do |file|
+      File.basename(file) =~ /^(BUILD\.bazel)$/
+    end
+    s.extensions = %w[
+      ext/google/protobuf_c/extconf.rb
+      ext/google/protobuf_c/Rakefile
+    ]
+    s.add_development_dependency "rake-compiler-dock", "= 1.2.1"
+  end
   s.required_ruby_version = '>= 2.5'
+  s.add_development_dependency "rake", "~> 13"
+  s.add_development_dependency "ffi", "~>1"
+  s.add_development_dependency "ffi-compiler", "~>1"
   s.add_development_dependency "rake-compiler", "~> 1.1.0"
   s.add_development_dependency "test-unit", '~> 3.0', '>= 3.0.9'
 end

ruby/lib/google/BUILD.bazel

@@ -8,9 +8,16 @@ config_setting(
 
 cc_binary(
     name = "protobuf_c.so",
-    deps = ["//ruby/ext/google/protobuf_c"],
     linkshared = 1,
     tags = ["manual"],
+    deps = ["//ruby/ext/google/protobuf_c"],
+)
+
+cc_binary(
+    name = "libprotobuf_c_ffi.so",
+    linkshared = 1,
+    tags = ["manual"],
+    deps = ["//ruby/ext/google/protobuf_c:protobuf_c_ffi"],
 )
 
 # Move the bundle to the location expected by our Ruby files.
@@ -22,13 +29,25 @@ genrule(
     tags = ["manual"],
 )
 
+# Move the bundle to the location expected by our Ruby files.
+genrule(
+    name = "copy_ffi_bundle",
+    srcs = ["//ruby/ext/google/protobuf_c:ffi_bundle"],
+    outs = ["libprotobuf_c_ffi.bundle"],
+    cmd = "cp $< $@",
+    tags = ["manual"],
+    visibility = [
+        "//ruby:__subpackages__",
+    ],
+)
+
 java_binary(
     name = "protobuf_java_bin",
-    runtime_deps = [
-        "//ruby/src/main/java:protobuf_java"
-    ],
-    deploy_env = ["@rules_ruby//ruby/runtime:jruby_binary"],
     create_executable = False,
+    deploy_env = ["@rules_ruby//ruby/runtime:jruby_binary"],
+    runtime_deps = [
+        "//ruby/src/main/java:protobuf_java",
+    ],
 )
 
 # Move the jar to the location expected by our Ruby files.
@@ -46,19 +65,34 @@ ruby_library(
     srcs = glob([
         "**/*.rb",
     ]),
-    deps = ["//:well_known_ruby_protos"],
-    includes = ["ruby/lib"],
     data = select({
+        # Platform native implementations
         "@rules_ruby//ruby/runtime:config_jruby": ["protobuf_java.jar"],
         "@platforms//os:osx": ["protobuf_c.bundle"],
         "//conditions:default": ["protobuf_c.so"],
+    }) + select({
+        # FFI Implementations
+        "//ruby:macos_ffi_enabled": ["libprotobuf_c_ffi.bundle"],
+        "//ruby:linux_ffi_enabled": ["libprotobuf_c_ffi.so"],
+        "//conditions:default": [],
     }),
+    includes = ["ruby/lib"],
     visibility = ["//ruby:__pkg__"],
+    deps = ["//:well_known_ruby_protos"] + select({
+        "//ruby:ffi_enabled": [
+            "@protobuf_bundle//:ffi",
+            "@protobuf_bundle//:ffi-compiler",
+        ],
+        "//conditions:default": [],
+    }),
 )
 
 pkg_files(
     name = "dist_files",
-    srcs = glob(["**/*.rb"]),
+    srcs = glob([
+        "**/*.rb",
+        "**/*.rake",
+    ]),
     strip_prefix = strip_prefix.from_root(""),
     visibility = ["//ruby:__pkg__"],
 )

ruby/lib/google/protobuf.rb

@@ -39,26 +39,16 @@ module Google
     class Error < StandardError; end
     class ParseError < Error; end
     class TypeError < ::TypeError; end
-  end
-end
 
-if RUBY_PLATFORM == "java"
-  require 'json'
-  require 'google/protobuf_java'
-else
-  begin
-    require "google/#{RUBY_VERSION.sub(/\.\d+$/, '')}/protobuf_c"
-  rescue LoadError
-    require 'google/protobuf_c'
-  end
-
-end
-
-require 'google/protobuf/descriptor_dsl'
-require 'google/protobuf/repeated_field'
-
-module Google
-  module Protobuf
+    PREFER_FFI = case ENV['PROTOCOL_BUFFERS_RUBY_IMPLEMENTATION']
+                 when nil, "", /^native$/i
+                   false
+                 when /^ffi$/i
+                   true
+                 else
+                   warn "Unexpected value `#{ENV['PROTOCOL_BUFFERS_RUBY_IMPLEMENTATION']}` for environment variable `PROTOCOL_BUFFERS_RUBY_IMPLEMENTATION`. Should be either \"FFI\", \"NATIVE\"."
+                   false
+                 end
 
     def self.encode(msg, options = {})
       msg.to_proto(options)
@@ -76,5 +66,19 @@ module Google
       klass.decode_json(json, options)
     end
 
+    IMPLEMENTATION = if PREFER_FFI
+      begin
+        require 'google/protobuf_ffi'
+        :FFI
+      rescue LoadError
+        warn "Caught exception `#{$!.message}` while loading FFI implementation of google/protobuf."
+        warn "Falling back to native implementation."
+        require 'google/protobuf_native'
+        :NATIVE
+      end
+    else
+      require 'google/protobuf_native'
+      :NATIVE
+    end
   end
 end

ruby/lib/google/protobuf/ffi/descriptor.rb

@@ -0,0 +1,177 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2022 Google Inc.  All rights reserved.
+# https://developers.google.com/protocol-buffers/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+module Google
+  module Protobuf
+    ##
+    # Message Descriptor - Descriptor for short.
+    class Descriptor
+      attr :descriptor_pool, :msg_class
+      include Enumerable
+
+      # FFI Interface methods and setup
+      extend ::FFI::DataConverter
+      native_type ::FFI::Type::POINTER
+
+      class << self
+        prepend Google::Protobuf::Internal::TypeSafety
+        include Google::Protobuf::Internal::PointerHelper
+
+        # @param value [Descriptor] Descriptor to convert to an FFI native type
+        # @param _ [Object] Unused
+        def to_native(value, _ = nil)
+          msg_def_ptr = value.nil? ? nil : value.instance_variable_get(:@msg_def)
+          return ::FFI::Pointer::NULL if msg_def_ptr.nil?
+          raise "Underlying msg_def was null!" if msg_def_ptr.null?
+          msg_def_ptr
+        end
+
+        ##
+        # @param msg_def [::FFI::Pointer] MsgDef pointer to be wrapped
+        # @param _ [Object] Unused
+        def from_native(msg_def, _ = nil)
+          return nil if msg_def.nil? or msg_def.null?
+          file_def = Google::Protobuf::FFI.get_message_file_def msg_def
+          descriptor_from_file_def(file_def, msg_def)
+        end
+      end
+
+      def to_native
+        self.class.to_native(self)
+      end
+
+      ##
+      # Great write up of this strategy:
+      # See https://blog.appsignal.com/2018/08/07/ruby-magic-changing-the-way-ruby-creates-objects.html
+      def self.new(*arguments, &block)
+        raise "Descriptor objects may not be created from Ruby."
+      end
+
+      def to_s
+        inspect
+      end
+
+      def inspect
+        "Descriptor - (not the message class) #{name}"
+      end
+
+      def file_descriptor
+        @descriptor_pool.send(:get_file_descriptor, Google::Protobuf::FFI.get_message_file_def(@msg_def))
+      end
+
+      def name
+        @name ||= Google::Protobuf::FFI.get_message_fullname(self)
+      end
+
+      def each_oneof &block
+        n = Google::Protobuf::FFI.oneof_count(self)
+        0.upto(n-1) do |i|
+          yield(Google::Protobuf::FFI.get_oneof_by_index(self, i))
+        end
+        nil
+      end
+
+      def each &block
+        n = Google::Protobuf::FFI.field_count(self)
+        0.upto(n-1) do |i|
+          yield(Google::Protobuf::FFI.get_field_by_index(self, i))
+        end
+        nil
+      end
+
+      def lookup(name)
+        Google::Protobuf::FFI.get_field_by_name(self, name, name.size)
+      end
+
+      def lookup_oneof(name)
+        Google::Protobuf::FFI.get_oneof_by_name(self, name, name.size)
+      end
+
+      def msgclass
+        @msg_class ||= build_message_class
+      end
+
+      private
+
+      extend Google::Protobuf::Internal::Convert
+
+      def initialize(msg_def, descriptor_pool)
+        @msg_def = msg_def
+        @msg_class = nil
+        @descriptor_pool = descriptor_pool
+      end
+
+      def self.private_constructor(msg_def, descriptor_pool)
+        instance = allocate
+        instance.send(:initialize, msg_def, descriptor_pool)
+        instance
+      end
+
+      def wrapper?
+        if defined? @wrapper
+          @wrapper
+        else
+          @wrapper = case Google::Protobuf::FFI.get_well_known_type self
+          when :DoubleValue, :FloatValue, :Int64Value, :UInt64Value, :Int32Value, :UInt32Value, :StringValue, :BytesValue, :BoolValue
+            true
+          else
+            false
+          end
+        end
+      end
+
+      def self.get_message(msg, descriptor, arena)
+        return nil if msg.nil? or msg.null?
+        message = OBJECT_CACHE.get(msg.address)
+        if message.nil?
+          message = descriptor.msgclass.send(:private_constructor, arena, msg: msg)
+        end
+        message
+      end
+
+      def pool
+        @descriptor_pool
+      end
+    end
+
+    class FFI
+      # MessageDef
+      attach_function :new_message_from_def, :upb_Message_New,                        [Descriptor, Internal::Arena], :Message
+      attach_function :field_count,          :upb_MessageDef_FieldCount,              [Descriptor], :int
+      attach_function :get_message_file_def, :upb_MessageDef_File,                    [:pointer], :FileDef
+      attach_function :get_message_fullname, :upb_MessageDef_FullName,                [Descriptor], :string
+      attach_function :get_mini_table,       :upb_MessageDef_MiniTable,               [Descriptor], MiniTable.ptr
+      attach_function :oneof_count,          :upb_MessageDef_OneofCount,              [Descriptor], :int
+      attach_function :get_well_known_type,  :upb_MessageDef_WellKnownType,           [Descriptor], WellKnown
+      attach_function :message_def_syntax,   :upb_MessageDef_Syntax,                  [Descriptor], Syntax
+      attach_function :find_msg_def_by_name, :upb_MessageDef_FindByNameWithSize,      [Descriptor, :string, :size_t, :FieldDefPointer, :OneofDefPointer], :bool
+    end
+  end
+end

ruby/lib/google/protobuf/ffi/descriptor_pool.rb

@@ -0,0 +1,93 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2022 Google Inc.  All rights reserved.
+# https://developers.google.com/protocol-buffers/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+module Google
+  module Protobuf
+    class FFI
+      # DefPool
+      attach_function :add_serialized_file,   :upb_DefPool_AddFile,           [:DefPool, :FileDescriptorProto, Status.by_ref], :FileDef
+      attach_function :free_descriptor_pool,  :upb_DefPool_Free,              [:DefPool], :void
+      attach_function :create_descriptor_pool,:upb_DefPool_New,               [], :DefPool
+      attach_function :lookup_enum,           :upb_DefPool_FindEnumByName,    [:DefPool, :string], EnumDescriptor
+      attach_function :lookup_msg,            :upb_DefPool_FindMessageByName, [:DefPool, :string], Descriptor
+      # FileDescriptorProto
+      attach_function :parse,                 :FileDescriptorProto_parse, [:binary_string, :size_t], :FileDescriptorProto
+    end
+    class DescriptorPool
+      attr :descriptor_pool
+      attr_accessor :descriptor_class_by_def
+
+      def initialize
+        @descriptor_pool = ::FFI::AutoPointer.new(Google::Protobuf::FFI.create_descriptor_pool, Google::Protobuf::FFI.method(:free_descriptor_pool))
+        @descriptor_class_by_def = {}
+
+        # Should always be the last expression of the initializer to avoid
+        # leaking references to this object before construction is complete.
+        Google::Protobuf::OBJECT_CACHE.try_add @descriptor_pool.address, self
+      end
+
+      def add_serialized_file(file_contents)
+        # Allocate memory sized to file_contents
+        memBuf = ::FFI::MemoryPointer.new(:char, file_contents.bytesize)
+        # Insert the data
+        memBuf.put_bytes(0, file_contents)
+        file_descriptor_proto = Google::Protobuf::FFI.parse memBuf, file_contents.bytesize
+        raise ArgumentError.new("Unable to parse FileDescriptorProto") if file_descriptor_proto.null?
+
+        status = Google::Protobuf::FFI::Status.new
+        file_descriptor = Google::Protobuf::FFI.add_serialized_file @descriptor_pool, file_descriptor_proto, status
+        if file_descriptor.null?
+          raise TypeError.new("Unable to build file to DescriptorPool: #{Google::Protobuf::FFI.error_message(status)}")
+        else
+          @descriptor_class_by_def[file_descriptor.address] = FileDescriptor.new file_descriptor, self
+        end
+      end
+
+      def lookup name
+        Google::Protobuf::FFI.lookup_msg(@descriptor_pool, name) ||
+          Google::Protobuf::FFI.lookup_enum(@descriptor_pool, name)
+      end
+
+      def self.generated_pool
+        @@generated_pool ||= DescriptorPool.new
+      end
+
+      private
+
+      # Implementation details below are subject to breaking changes without
+      # warning and are intended for use only within the gem.
+
+      def get_file_descriptor file_def
+        return nil if file_def.null?
+        @descriptor_class_by_def[file_def.address] ||= FileDescriptor.new(file_def, self)
+      end
+    end
+  end
+end

ruby/lib/google/protobuf/ffi/enum_descriptor.rb

@@ -0,0 +1,184 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2022 Google Inc.  All rights reserved.
+# https://developers.google.com/protocol-buffers/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+module Google
+  module Protobuf
+    class EnumDescriptor
+      attr :descriptor_pool, :enum_def
+      include Enumerable
+
+      # FFI Interface methods and setup
+      extend ::FFI::DataConverter
+      native_type ::FFI::Type::POINTER
+
+      class << self
+        prepend Google::Protobuf::Internal::TypeSafety
+        include Google::Protobuf::Internal::PointerHelper
+
+        # @param value [Arena] Arena to convert to an FFI native type
+        # @param _ [Object] Unused
+        def to_native(value, _)
+          value.instance_variable_get(:@enum_def) || ::FFI::Pointer::NULL
+        end
+
+        ##
+        # @param enum_def [::FFI::Pointer] EnumDef pointer to be wrapped
+        # @param _ [Object] Unused
+        def from_native(enum_def, _)
+          return nil if enum_def.nil? or enum_def.null?
+          file_def = Google::Protobuf::FFI.get_message_file_def enum_def
+          descriptor_from_file_def(file_def, enum_def)
+        end
+      end
+
+      def self.new(*arguments, &block)
+        raise "Descriptor objects may not be created from Ruby."
+      end
+
+      def file_descriptor
+        @descriptor_pool.send(:get_file_descriptor, Google::Protobuf::FFI.get_enum_file_descriptor(self))
+      end
+
+      def name
+        Google::Protobuf::FFI.get_enum_fullname(self)
+      end
+
+      def to_s
+        inspect
+      end
+
+      def inspect
+        "#{self.class.name}: #{name}"
+      end
+
+      def lookup_name(name)
+        self.class.send(:lookup_name, self, name)
+      end
+
+      def lookup_value(number)
+        self.class.send(:lookup_value, self, number)
+      end
+
+      def each &block
+        n = Google::Protobuf::FFI.enum_value_count(self)
+        0.upto(n - 1) do |i|
+          enum_value = Google::Protobuf::FFI.enum_value_by_index(self, i)
+          yield(Google::Protobuf::FFI.enum_name(enum_value).to_sym, Google::Protobuf::FFI.enum_number(enum_value))
+        end
+        nil
+      end
+
+      def enummodule
+        if @module.nil?
+          @module = build_enum_module
+        end
+        @module
+      end
+
+      private
+
+      def initialize(enum_def, descriptor_pool)
+        @descriptor_pool = descriptor_pool
+        @enum_def = enum_def
+        @module = nil
+      end
+
+      def self.private_constructor(enum_def, descriptor_pool)
+        instance = allocate
+        instance.send(:initialize, enum_def, descriptor_pool)
+        instance
+      end
+
+      def self.lookup_value(enum_def, number)
+        enum_value = Google::Protobuf::FFI.enum_value_by_number(enum_def, number)
+        if enum_value.null?
+          nil
+        else
+          Google::Protobuf::FFI.enum_name(enum_value).to_sym
+        end
+      end
+
+      def self.lookup_name(enum_def, name)
+        enum_value = Google::Protobuf::FFI.enum_value_by_name(enum_def, name.to_s, name.size)
+        if enum_value.null?
+          nil
+        else
+          Google::Protobuf::FFI.enum_number(enum_value)
+        end
+      end
+
+      def build_enum_module
+        descriptor = self
+        dynamic_module = Module.new do
+          @descriptor = descriptor
+
+          class << self
+            attr_accessor :descriptor
+          end
+
+          def self.lookup(number)
+            descriptor.lookup_value number
+          end
+
+          def self.resolve(name)
+            descriptor.lookup_name name
+          end
+        end
+
+        self.each do |name, value|
+          if name[0] < 'A' || name[0] > 'Z'
+            if name[0] >= 'a' and name[0] <= 'z'
+              name = name[0].upcase + name[1..-1] # auto capitalize
+            else
+              warn(
+                "Enum value '#{name}' does not start with an uppercase letter " +
+                  "as is required for Ruby constants.")
+              next
+            end
+          end
+          dynamic_module.const_set(name.to_sym, value)
+        end
+        dynamic_module
+      end
+    end
+
+    class FFI
+      # EnumDescriptor
+      attach_function :get_enum_file_descriptor,  :upb_EnumDef_File,                   [EnumDescriptor], :FileDef
+      attach_function :enum_value_by_name,        :upb_EnumDef_FindValueByNameWithSize,[EnumDescriptor, :string, :size_t], :EnumValueDef
+      attach_function :enum_value_by_number,      :upb_EnumDef_FindValueByNumber,      [EnumDescriptor, :int], :EnumValueDef
+      attach_function :get_enum_fullname,         :upb_EnumDef_FullName,               [EnumDescriptor], :string
+      attach_function :enum_value_by_index,       :upb_EnumDef_Value,                  [EnumDescriptor, :int], :EnumValueDef
+      attach_function :enum_value_count,          :upb_EnumDef_ValueCount,             [EnumDescriptor], :int
+      attach_function :enum_name,                 :upb_EnumValueDef_Name,              [:EnumValueDef], :string
+      attach_function :enum_number,               :upb_EnumValueDef_Number,            [:EnumValueDef], :int
+    end
+  end
+end

ruby/lib/google/protobuf/ffi/ffi.rb

@@ -0,0 +1,236 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2022 Google Inc.  All rights reserved.
+# https://developers.google.com/protocol-buffers/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+module Google
+  module Protobuf
+    class FFI
+      extend ::FFI::Library
+      # Workaround for Bazel's use of symlinks + JRuby's __FILE__ and `caller`
+      # that resolves them.
+      if ENV['BAZEL'] == 'true'
+        ffi_lib ::FFI::Compiler::Loader.find 'protobuf_c_ffi', ENV['PWD']
+      else
+        ffi_lib ::FFI::Compiler::Loader.find 'protobuf_c_ffi'
+      end
+
+      ## Map
+      Upb_Map_Begin = -1
+
+      ## Encoding Status
+      Upb_Status_MaxMessage = 127
+      Upb_Encode_Deterministic = 1
+      Upb_Encode_SkipUnknown = 2
+
+      ## JSON Encoding options
+      # When set, emits 0/default values.  TODO(haberman): proto3 only?
+      Upb_JsonEncode_EmitDefaults = 1
+      # When set, use normal (snake_case) field names instead of JSON (camelCase) names.
+      Upb_JsonEncode_UseProtoNames = 2
+      # When set, emits enums as their integer values instead of as their names.
+      Upb_JsonEncode_FormatEnumsAsIntegers = 4
+
+      ## JSON Decoding options
+      Upb_JsonDecode_IgnoreUnknown = 1
+
+      typedef :pointer, :Array
+      typedef :pointer, :DefPool
+      typedef :pointer, :EnumValueDef
+      typedef :pointer, :ExtensionRegistry
+      typedef :pointer, :FieldDefPointer
+      typedef :pointer, :FileDef
+      typedef :pointer, :FileDescriptorProto
+      typedef :pointer, :Map
+      typedef :pointer, :Message    # Instances of a message
+      typedef :pointer, :OneofDefPointer
+      typedef :pointer, :binary_string
+      if ::FFI::Platform::ARCH == "aarch64"
+        typedef :u_int8_t, :uint8_t
+        typedef :u_int16_t, :uint16_t
+        typedef :u_int32_t, :uint32_t
+        typedef :u_int64_t, :uint64_t
+      end
+
+      FieldType = enum(
+        :double, 1,
+        :float,
+        :int64,
+        :uint64,
+        :int32,
+        :fixed64,
+        :fixed32,
+        :bool,
+        :string,
+        :group,
+        :message,
+        :bytes,
+        :uint32,
+        :enum,
+        :sfixed32,
+        :sfixed64,
+        :sint32,
+        :sint64
+      )
+
+      CType = enum(
+        :bool, 1,
+        :float,
+        :int32,
+        :uint32,
+        :enum,
+        :message,
+        :double,
+        :int64,
+        :uint64,
+        :string,
+        :bytes
+      )
+
+      Label = enum(
+        :optional, 1,
+        :required,
+        :repeated
+      )
+
+      Syntax = enum(
+        :Proto2, 2,
+        :Proto3
+      )
+
+      # All the different kind of well known type messages. For simplicity of check,
+      # number wrappers and string wrappers are grouped together. Make sure the
+      # order and merber of these groups are not changed.
+
+      WellKnown = enum(
+        :Unspecified,
+        :Any,
+        :FieldMask,
+        :Duration,
+        :Timestamp,
+        # number wrappers
+        :DoubleValue,
+        :FloatValue,
+        :Int64Value,
+        :UInt64Value,
+        :Int32Value,
+        :UInt32Value,
+        # string wrappers
+        :StringValue,
+        :BytesValue,
+        :BoolValue,
+        :Value,
+        :ListValue,
+        :Struct
+      )
+
+      DecodeStatus = enum(
+        :Ok,
+        :Malformed,         # Wire format was corrupt
+        :OutOfMemory,       # Arena alloc failed
+        :BadUtf8,           # String field had bad UTF-8
+        :MaxDepthExceeded,  # Exceeded UPB_DECODE_MAXDEPTH
+
+        # CheckRequired failed, but the parse otherwise succeeded.
+        :MissingRequired,
+      )
+
+      EncodeStatus = enum(
+        :Ok,
+        :OutOfMemory,       # Arena alloc failed
+        :MaxDepthExceeded,  # Exceeded UPB_DECODE_MAXDEPTH
+
+        # CheckRequired failed, but the parse otherwise succeeded.
+        :MissingRequired,
+      )
+
+      class StringView < ::FFI::Struct
+        layout :data, :pointer,
+               :size, :size_t
+      end
+
+      class MiniTable < ::FFI::Struct
+        layout :subs, :pointer,
+               :fields, :pointer,
+               :size, :uint16_t,
+               :field_count, :uint16_t,
+               :ext, :uint8_t,  # upb_ExtMode, declared as uint8_t so sizeof(ext) == 1
+               :dense_below, :uint8_t,
+               :table_mask, :uint8_t,
+               :required_count, :uint8_t  # Required fields have the lowest hasbits.
+        # To statically initialize the tables of variable length, we need a flexible
+        # array member, and we need to compile in gnu99 mode (constant initialization
+        # of flexible array members is a GNU extension, not in C99 unfortunately. */
+        #       _upb_FastTable_Entry fasttable[];
+      end
+
+      class Status < ::FFI::Struct
+        layout :ok, :bool,
+               :msg, [:char, Upb_Status_MaxMessage]
+
+        def initialize
+          super
+          FFI.clear self
+        end
+      end
+
+      class MessageValue < ::FFI::Union
+        layout :bool_val, :bool,
+               :float_val, :float,
+               :double_val, :double,
+               :int32_val, :int32_t,
+               :int64_val, :int64_t,
+               :uint32_val, :uint32_t,
+               :uint64_val,:uint64_t,
+               :map_val, :pointer,
+               :msg_val, :pointer,
+               :array_val,:pointer,
+               :str_val, StringView
+      end
+
+      class MutableMessageValue < ::FFI::Union
+        layout :map, :Map,
+               :msg, :Message,
+               :array, :Array
+      end
+
+      # Status
+      attach_function :clear,                 :upb_Status_Clear, [Status.by_ref], :void
+      attach_function :error_message,         :upb_Status_ErrorMessage, [Status.by_ref], :string
+
+      # Generic
+      attach_function :memcmp, [:pointer, :pointer, :size_t], :int
+      attach_function :memcpy, [:pointer, :pointer, :size_t], :int
+
+      # Alternatives to pre-processor macros
+      def self.decode_max_depth(i)
+        i << 16
+      end
+    end
+  end
+end

ruby/lib/google/protobuf/ffi/field_descriptor.rb

@@ -0,0 +1,332 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2022 Google Inc.  All rights reserved.
+# https://developers.google.com/protocol-buffers/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+module Google
+  module Protobuf
+    class FieldDescriptor
+      attr :field_def, :descriptor_pool
+
+      include Google::Protobuf::Internal::Convert
+
+      # FFI Interface methods and setup
+      extend ::FFI::DataConverter
+      native_type ::FFI::Type::POINTER
+
+      class << self
+        prepend Google::Protobuf::Internal::TypeSafety
+        include Google::Protobuf::Internal::PointerHelper
+
+        # @param value [FieldDescriptor] FieldDescriptor to convert to an FFI native type
+        # @param _ [Object] Unused
+        def to_native(value, _)
+          field_def_ptr = value.instance_variable_get(:@field_def)
+          warn "Underlying field_def was nil!" if field_def_ptr.nil?
+          raise "Underlying field_def was null!" if !field_def_ptr.nil? and field_def_ptr.null?
+          field_def_ptr
+        end
+
+        ##
+        # @param field_def [::FFI::Pointer] FieldDef pointer to be wrapped
+        # @param _ [Object] Unused
+        def from_native(field_def, _ = nil)
+          return nil if field_def.nil? or field_def.null?
+          file_def = Google::Protobuf::FFI.file_def_by_raw_field_def(field_def)
+          descriptor_from_file_def(file_def, field_def)
+        end
+      end
+
+      def self.new(*arguments, &block)
+        raise "Descriptor objects may not be created from Ruby."
+      end
+
+      def to_s
+        inspect
+      end
+
+      def inspect
+        "#{self.class.name}: #{name}"
+      end
+
+      def name
+        @name ||= Google::Protobuf::FFI.get_full_name(self)
+      end
+
+      def json_name
+        @json_name ||= Google::Protobuf::FFI.get_json_name(self)
+      end
+
+      def number
+        @number ||= Google::Protobuf::FFI.get_number(self)
+      end
+
+      def type
+        @type ||= Google::Protobuf::FFI.get_type(self)
+      end
+
+      def label
+        @label ||= Google::Protobuf::FFI::Label[Google::Protobuf::FFI.get_label(self)]
+      end
+
+      def default
+        return nil if Google::Protobuf::FFI.is_sub_message(self)
+        if Google::Protobuf::FFI.is_repeated(self)
+          message_value = Google::Protobuf::FFI::MessageValue.new
+        else
+          message_value = Google::Protobuf::FFI.get_default(self)
+        end
+        enum_def = Google::Protobuf::FFI.get_subtype_as_enum(self)
+        if enum_def.null?
+          convert_upb_to_ruby message_value, c_type
+        else
+          convert_upb_to_ruby message_value, c_type, enum_def
+        end
+      end
+
+      def submsg_name
+        if defined? @submsg_name
+          @submsg_name
+        else
+          @submsg_name = case c_type
+            when :enum
+              Google::Protobuf::FFI.get_enum_fullname Google::Protobuf::FFI.get_subtype_as_enum self
+            when :message
+              Google::Protobuf::FFI.get_message_fullname Google::Protobuf::FFI.get_subtype_as_message self
+            else
+              nil
+            end
+        end
+      end
+
+      ##
+      # Tests if this field has been set on the argument message.
+      #
+      # @param msg [Google::Protobuf::Message]
+      # @return [Object] Value of the field on this message.
+      # @raise [TypeError] If the field is not defined on this message.
+      def get(msg)
+        if msg.class.descriptor == Google::Protobuf::FFI.get_containing_message_def(self)
+          msg.send :get_field, self
+        else
+          raise TypeError.new "get method called on wrong message type"
+        end
+      end
+
+      def subtype
+        if defined? @subtype
+          @subtype
+        else
+          @subtype = case c_type
+            when :enum
+              Google::Protobuf::FFI.get_subtype_as_enum(self)
+            when :message
+              Google::Protobuf::FFI.get_subtype_as_message(self)
+            else
+              nil
+            end
+        end
+      end
+
+      ##
+      # Tests if this field has been set on the argument message.
+      #
+      # @param msg [Google::Protobuf::Message]
+      # @return [Boolean] True iff message has this field set
+      # @raise [TypeError] If this field does not exist on the message
+      # @raise [ArgumentError] If this field does not track presence
+      def has?(msg)
+        if msg.class.descriptor != Google::Protobuf::FFI.get_containing_message_def(self)
+          raise TypeError.new "has method called on wrong message type"
+        end
+        unless has_presence?
+          raise ArgumentError.new "does not track presence"
+        end
+
+        Google::Protobuf::FFI.get_message_has msg.instance_variable_get(:@msg), self
+      end
+
+      ##
+      # Tests if this field tracks presence.
+      #
+      # @return [Boolean] True iff this field tracks presence
+      def has_presence?
+        @has_presence ||= Google::Protobuf::FFI.get_has_presence(self)
+      end
+
+      # @param msg [Google::Protobuf::Message]
+      def clear(msg)
+        if msg.class.descriptor != Google::Protobuf::FFI.get_containing_message_def(self)
+          raise TypeError.new "clear method called on wrong message type"
+        end
+        Google::Protobuf::FFI.clear_message_field msg.instance_variable_get(:@msg), self
+        nil
+      end
+
+      ##
+      # call-seq:
+      #     FieldDescriptor.set(message, value)
+      #
+      # Sets the value corresponding to this field to the given value on the given
+      # message. Raises an exception if message is of the wrong type. Performs the
+      # ordinary type-checks for field setting.
+      #
+      # @param msg [Google::Protobuf::Message]
+      # @param value [Object]
+      def set(msg, value)
+        if msg.class.descriptor != Google::Protobuf::FFI.get_containing_message_def(self)
+          raise TypeError.new "set method called on wrong message type"
+        end
+        unless set_value_on_message value, msg.instance_variable_get(:@msg), msg.instance_variable_get(:@arena)
+          raise RuntimeError.new "allocation failed"
+        end
+        nil
+      end
+
+      def map?
+        @map ||= Google::Protobuf::FFI.is_map self
+      end
+
+      def repeated?
+        @repeated ||= Google::Protobuf::FFI.is_repeated self
+      end
+
+      def sub_message?
+        @sub_message ||= Google::Protobuf::FFI.is_sub_message self
+      end
+
+      def wrapper?
+        if defined? @wrapper
+          @wrapper
+        else
+          message_descriptor = Google::Protobuf::FFI.get_subtype_as_message(self)
+          @wrapper = message_descriptor.nil? ? false : message_descriptor.send(:wrapper?)
+        end
+      end
+
+      private
+
+      def initialize(field_def, descriptor_pool)
+        @field_def = field_def
+        @descriptor_pool = descriptor_pool
+      end
+
+      def self.private_constructor(field_def, descriptor_pool)
+        instance = allocate
+        instance.send(:initialize, field_def, descriptor_pool)
+        instance
+      end
+
+      # TODO(jatl) Can this be added to the public API?
+      def real_containing_oneof
+        @real_containing_oneof ||= Google::Protobuf::FFI.real_containing_oneof self
+      end
+
+      # Implementation details below are subject to breaking changes without
+      # warning and are intended for use only within the gem.
+
+      ##
+      # Sets the field this FieldDescriptor represents to the given value on the given message.
+      # @param value [Object] Value to be set
+      # @param msg [::FFI::Pointer] Pointer the the upb_Message
+      # @param arena [Arena] Arena of the message that owns msg
+      def set_value_on_message(value, msg, arena, wrap: false)
+        message_to_alter = msg
+        field_def_to_set = self
+        if map?
+          raise TypeError.new "Expected map" unless value.is_a? Google::Protobuf::Map
+          message_descriptor = subtype
+
+          key_field_def = Google::Protobuf::FFI.get_field_by_number(message_descriptor, 1)
+          key_field_type = Google::Protobuf::FFI.get_type(key_field_def)
+          raise TypeError.new "Map key type does not match field's key type" unless key_field_type == value.send(:key_type)
+
+          value_field_def = Google::Protobuf::FFI.get_field_by_number(message_descriptor, 2)
+          value_field_type = Google::Protobuf::FFI.get_type(value_field_def)
+          raise TypeError.new "Map value type does not match field's value type" unless value_field_type == value.send(:value_type)
+
+          raise TypeError.new "Map value type has wrong message/enum class" unless value_field_def.subtype == value.send(:descriptor)
+
+          arena.fuse(value.send(:arena))
+          message_value = Google::Protobuf::FFI::MessageValue.new
+          message_value[:map_val] = value.send(:map_ptr)
+        elsif repeated?
+          raise TypeError.new "Expected repeated field array" unless value.is_a? RepeatedField
+          raise TypeError.new "Repeated field array has wrong message/enum class" unless value.send(:type) == type
+          arena.fuse(value.send(:arena))
+          message_value = Google::Protobuf::FFI::MessageValue.new
+          message_value[:array_val] = value.send(:array)
+        else
+          if value.nil? and (sub_message? or !real_containing_oneof.nil?)
+            Google::Protobuf::FFI.clear_message_field message_to_alter, field_def_to_set
+            return true
+          end
+          if wrap
+            value_field_def = Google::Protobuf::FFI.get_field_by_number subtype, 1
+            type_for_conversion = Google::Protobuf::FFI.get_c_type(value_field_def)
+            raise RuntimeError.new "Not expecting to get a msg or enum when unwrapping" if [:enum, :message].include? type_for_conversion
+            message_value = convert_ruby_to_upb(value, arena, type_for_conversion, nil)
+            message_to_alter = Google::Protobuf::FFI.get_mutable_message(msg, self, arena)[:msg]
+            field_def_to_set = value_field_def
+          else
+            message_value = convert_ruby_to_upb(value, arena, c_type, subtype)
+          end
+        end
+        Google::Protobuf::FFI.set_message_field message_to_alter, field_def_to_set, message_value, arena
+      end
+
+      def c_type
+        @c_type ||= Google::Protobuf::FFI.get_c_type(self)
+      end
+    end
+
+    class FFI
+      # MessageDef
+      attach_function :get_field_by_index,   :upb_MessageDef_Field,                  [Descriptor, :int], FieldDescriptor
+      attach_function :get_field_by_name,    :upb_MessageDef_FindFieldByNameWithSize,[Descriptor, :string, :size_t], FieldDescriptor
+      attach_function :get_field_by_number,  :upb_MessageDef_FindFieldByNumber,      [Descriptor, :uint32_t], FieldDescriptor
+
+      # FieldDescriptor
+      attach_function :get_containing_message_def, :upb_FieldDef_ContainingType,     [FieldDescriptor], Descriptor
+      attach_function :get_c_type,                 :upb_FieldDef_CType,              [FieldDescriptor], CType
+      attach_function :get_default,                :upb_FieldDef_Default,            [FieldDescriptor], MessageValue.by_value
+      attach_function :get_subtype_as_enum,        :upb_FieldDef_EnumSubDef,         [FieldDescriptor], EnumDescriptor
+      attach_function :get_has_presence,           :upb_FieldDef_HasPresence,        [FieldDescriptor], :bool
+      attach_function :is_map,                     :upb_FieldDef_IsMap,              [FieldDescriptor], :bool
+      attach_function :is_repeated,                :upb_FieldDef_IsRepeated,         [FieldDescriptor], :bool
+      attach_function :is_sub_message,             :upb_FieldDef_IsSubMessage,       [FieldDescriptor], :bool
+      attach_function :get_json_name,              :upb_FieldDef_JsonName,           [FieldDescriptor], :string
+      attach_function :get_label,                  :upb_FieldDef_Label,              [FieldDescriptor], Label
+      attach_function :get_subtype_as_message,     :upb_FieldDef_MessageSubDef,      [FieldDescriptor], Descriptor
+      attach_function :get_full_name,              :upb_FieldDef_Name,               [FieldDescriptor], :string
+      attach_function :get_number,                 :upb_FieldDef_Number,             [FieldDescriptor], :uint32_t
+      attach_function :get_type,                   :upb_FieldDef_Type,               [FieldDescriptor], FieldType
+      attach_function :file_def_by_raw_field_def,  :upb_FieldDef_File,               [:pointer], :FileDef
+    end
+  end
+end

ruby/lib/google/protobuf/ffi/file_descriptor.rb

@@ -0,0 +1,71 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2022 Google Inc.  All rights reserved.
+# https://developers.google.com/protocol-buffers/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+module Google
+  module Protobuf
+    class FFI
+      # FileDescriptor
+      attach_function :file_def_name,   :upb_FileDef_Name,   [:FileDef], :string
+      attach_function :file_def_syntax, :upb_FileDef_Syntax, [:FileDef], Syntax
+      attach_function :file_def_pool,   :upb_FileDef_Pool,   [:FileDef], :DefPool
+    end
+    class FileDescriptor
+      attr :descriptor_pool, :file_def
+
+      def initialize(file_def, descriptor_pool)
+        @descriptor_pool = descriptor_pool
+        @file_def = file_def
+      end
+
+      def to_s
+        inspect
+      end
+
+      def inspect
+        "#{self.class.name}: #{name}"
+      end
+
+      def syntax
+        case Google::Protobuf::FFI.file_def_syntax(@file_def)
+        when :Proto3
+          :proto3
+        when :Proto2
+          :proto2
+        else
+          nil
+        end
+      end
+
+      def name
+        Google::Protobuf::FFI.file_def_name(@file_def)
+      end
+    end
+  end
+end

ruby/lib/google/protobuf/ffi/internal/arena.rb

@@ -0,0 +1,83 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2022 Google Inc.  All rights reserved.
+# https://developers.google.com/protocol-buffers/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+##
+# Implementation details below are subject to breaking changes without
+# warning and are intended for use only within the gem.
+module Google
+  module Protobuf
+    module Internal
+      class Arena
+
+        # FFI Interface methods and setup
+        extend ::FFI::DataConverter
+        native_type ::FFI::Type::POINTER
+
+        class << self
+          prepend Google::Protobuf::Internal::TypeSafety
+
+          # @param value [Arena] Arena to convert to an FFI native type
+          # @param _ [Object] Unused
+          def to_native(value, _)
+            value.instance_variable_get(:@arena) || ::FFI::Pointer::NULL
+          end
+
+          ##
+          # @param value [::FFI::Pointer] Arena pointer to be wrapped
+          # @param _ [Object] Unused
+          def from_native(value, _)
+            new(value)
+          end
+        end
+
+        def initialize(pointer)
+          @arena = ::FFI::AutoPointer.new(pointer, Google::Protobuf::FFI.method(:free_arena))
+        end
+
+        def fuse(other_arena)
+          return if other_arena == self
+          unless Google::Protobuf::FFI.fuse_arena(self, other_arena)
+            raise RuntimeError.new "Unable to fuse arenas. This should never happen since Ruby does not use initial blocks"
+          end
+        end
+      end
+    end
+
+    class FFI
+      # Arena
+      attach_function :create_arena, :Arena_create,         [], Internal::Arena
+      attach_function :fuse_arena,   :upb_Arena_Fuse,       [Internal::Arena, Internal::Arena], :bool
+      # Argument takes a :pointer rather than a typed Arena here due to
+      # implementation details of FFI::AutoPointer.
+      attach_function :free_arena,   :upb_Arena_Free,       [:pointer], :void
+      attach_function :arena_malloc, :upb_Arena_Malloc,     [Internal::Arena, :size_t], :pointer
+    end
+  end
+end

ruby/lib/google/protobuf/ffi/internal/convert.rb

@@ -0,0 +1,328 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2022 Google Inc.  All rights reserved.
+# https://developers.google.com/protocol-buffers/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+##
+# Implementation details below are subject to breaking changes without
+# warning and are intended for use only within the gem.
+module Google
+  module Protobuf
+    module Internal
+      module Convert
+
+        # Arena should be the
+        # @param value [Object] Value to convert
+        # @param arena [Arena] Arena that owns the Message where the MessageValue
+        #   will be set
+        # @return [Google::Protobuf::FFI::MessageValue]
+        def convert_ruby_to_upb(value, arena, c_type, msg_or_enum_def)
+          raise ArgumentError.new "Expected Descriptor or EnumDescriptor, instead got #{msg_or_enum_def.class}" unless [NilClass, Descriptor, EnumDescriptor].include? msg_or_enum_def.class
+          return_value = Google::Protobuf::FFI::MessageValue.new
+          case c_type
+          when :float
+            raise TypeError.new "Expected number type for float field '#{name}' (given #{value.class})." unless value.respond_to? :to_f
+            return_value[:float_val] = value.to_f
+          when :double
+            raise TypeError.new "Expected number type for double field '#{name}' (given #{value.class})." unless value.respond_to? :to_f
+            return_value[:double_val] = value.to_f
+          when :bool
+            raise TypeError.new "Invalid argument for boolean field '#{name}' (given #{value.class})." unless [TrueClass, FalseClass].include? value.class
+            return_value[:bool_val] = value
+          when :string
+            raise TypeError.new "Invalid argument for string field '#{name}' (given #{value.class})." unless [Symbol, String].include? value.class
+            begin
+              string_value = value.to_s.encode("UTF-8")
+            rescue Encoding::UndefinedConversionError
+              # TODO(jatl) - why not include the field name here?
+              raise Encoding::UndefinedConversionError.new "String is invalid UTF-8"
+            end
+            return_value[:str_val][:size] = string_value.bytesize
+            return_value[:str_val][:data] = Google::Protobuf::FFI.arena_malloc(arena, string_value.bytesize)
+            # TODO(jatl) - how important is it to still use arena malloc, versus the following?
+            # buffer = ::FFI::MemoryPointer.new(:char, string_value.bytesize)
+            # buffer.put_bytes(0, string_value)
+            # return_value[:str_val][:data] = buffer
+            raise NoMemoryError.new "Cannot allocate #{string_value.bytesize} bytes for string on Arena" if return_value[:str_val][:data].nil? || return_value[:str_val][:data].null?
+            return_value[:str_val][:data].write_string(string_value)
+          when :bytes
+            raise TypeError.new "Invalid argument for bytes field '#{name}' (given #{value.class})." unless value.is_a? String
+            string_value = value.encode("ASCII-8BIT")
+            return_value[:str_val][:size] = string_value.bytesize
+            return_value[:str_val][:data] = Google::Protobuf::FFI.arena_malloc(arena, string_value.bytesize)
+            raise NoMemoryError.new "Cannot allocate #{string_value.bytesize} bytes for bytes on Arena" if return_value[:str_val][:data].nil? || return_value[:str_val][:data].null?
+            return_value[:str_val][:data].write_string_length(string_value, string_value.bytesize)
+          when :message
+            raise TypeError.new "nil message not allowed here." if value.nil?
+            if value.is_a? Hash
+              raise RuntimeError.new "Attempted to initialize message from Hash for field #{name} but have no definition" if msg_or_enum_def.nil?
+              new_message = msg_or_enum_def.msgclass.
+                send(:private_constructor, arena, initial_value: value)
+              return_value[:msg_val] = new_message.instance_variable_get(:@msg)
+              return return_value
+            end
+
+            descriptor = value.class.respond_to?(:descriptor) ? value.class.descriptor : nil
+            if descriptor != msg_or_enum_def
+              wkt = Google::Protobuf::FFI.get_well_known_type(msg_or_enum_def)
+              case wkt
+              when :Timestamp
+                raise TypeError.new "Invalid type #{value.class} to assign to submessage field '#{name}'." unless value.kind_of? Time
+                new_message = Google::Protobuf::FFI.new_message_from_def msg_or_enum_def, arena
+                sec = Google::Protobuf::FFI::MessageValue.new
+                sec[:int64_val] = value.tv_sec
+                sec_field_def = Google::Protobuf::FFI.get_field_by_number msg_or_enum_def, 1
+                raise "Should be impossible" unless Google::Protobuf::FFI.set_message_field new_message, sec_field_def, sec, arena
+                nsec_field_def = Google::Protobuf::FFI.get_field_by_number msg_or_enum_def, 2
+                nsec = Google::Protobuf::FFI::MessageValue.new
+                nsec[:int32_val] = value.tv_nsec
+                raise "Should be impossible" unless Google::Protobuf::FFI.set_message_field new_message, nsec_field_def, nsec, arena
+                return_value[:msg_val] = new_message
+              when :Duration
+                raise TypeError.new "Invalid type #{value.class} to assign to submessage field '#{name}'." unless value.kind_of? Numeric
+                new_message = Google::Protobuf::FFI.new_message_from_def msg_or_enum_def, arena
+                sec = Google::Protobuf::FFI::MessageValue.new
+                sec[:int64_val] = value
+                sec_field_def = Google::Protobuf::FFI.get_field_by_number msg_or_enum_def, 1
+                raise "Should be impossible" unless Google::Protobuf::FFI.set_message_field new_message, sec_field_def, sec, arena
+                nsec_field_def = Google::Protobuf::FFI.get_field_by_number msg_or_enum_def, 2
+                nsec = Google::Protobuf::FFI::MessageValue.new
+                nsec[:int32_val] = ((value.to_f - value.to_i) * 1000000000).round
+                raise "Should be impossible" unless Google::Protobuf::FFI.set_message_field new_message, nsec_field_def, nsec, arena
+                return_value[:msg_val] = new_message
+              else
+                raise TypeError.new "Invalid type #{value.class} to assign to submessage field '#{name}'."
+              end
+            else
+              arena.fuse(value.instance_variable_get(:@arena))
+              return_value[:msg_val] = value.instance_variable_get :@msg
+            end
+          when :enum
+            return_value[:int32_val] = case value
+              when Numeric
+                value.to_i
+              when String, Symbol
+                enum_number = EnumDescriptor.send(:lookup_name, msg_or_enum_def, value.to_s)
+                #TODO(jatl) add the bad value to the error message after tests pass
+                raise RangeError.new "Unknown symbol value for enum field '#{name}'." if enum_number.nil?
+                enum_number
+              else
+                raise TypeError.new "Expected number or symbol type for enum field '#{name}'."
+              end
+          #TODO(jatl) After all tests pass, improve error message across integer type by including actual offending value
+          when :int32
+            raise TypeError.new "Expected number type for integral field '#{name}' (given #{value.class})." unless value.is_a? Numeric
+            raise RangeError.new "Non-integral floating point value assigned to integer field '#{name}' (given #{value.class})." if value.floor != value
+            raise RangeError.new "Value assigned to int32 field '#{name}' (given #{value.class}) with more than 32-bits." unless value.to_i.bit_length < 32
+            return_value[:int32_val] = value.to_i
+          when :uint32
+            raise TypeError.new "Expected number type for integral field '#{name}' (given #{value.class})." unless value.is_a? Numeric
+            raise RangeError.new "Non-integral floating point value assigned to integer field '#{name}' (given #{value.class})." if value.floor != value
+            raise RangeError.new "Assigning negative value to unsigned integer field '#{name}' (given #{value.class})." if value < 0
+            raise RangeError.new "Value assigned to uint32 field '#{name}' (given #{value.class}) with more than 32-bits." unless value.to_i.bit_length < 33
+            return_value[:uint32_val] = value.to_i
+          when :int64
+            raise TypeError.new "Expected number type for integral field '#{name}' (given #{value.class})." unless value.is_a? Numeric
+            raise RangeError.new "Non-integral floating point value assigned to integer field '#{name}' (given #{value.class})." if value.floor != value
+            raise RangeError.new "Value assigned to int64 field '#{name}' (given #{value.class}) with more than 64-bits." unless value.to_i.bit_length < 64
+            return_value[:int64_val] = value.to_i
+          when :uint64
+            raise TypeError.new "Expected number type for integral field '#{name}' (given #{value.class})." unless value.is_a? Numeric
+            raise RangeError.new "Non-integral floating point value assigned to integer field '#{name}' (given #{value.class})." if value.floor != value
+            raise RangeError.new "Assigning negative value to unsigned integer field '#{name}' (given #{value.class})." if value < 0
+            raise RangeError.new "Value assigned to uint64 field '#{name}' (given #{value.class}) with more than 64-bits." unless value.to_i.bit_length < 65
+            return_value[:uint64_val] = value.to_i
+          else
+            raise RuntimeError.new "Unsupported type #{c_type}"
+          end
+          return_value
+        end
+
+        ##
+        # Safe to call without an arena if the caller has checked that c_type
+        # is not :message.
+        # @param message_value [Google::Protobuf::FFI::MessageValue] Value to be converted.
+        # @param c_type [Google::Protobuf::FFI::CType] Enum representing the type of message_value
+        # @param msg_or_enum_def [::FFI::Pointer] Pointer to the MsgDef or EnumDef definition
+        # @param arena [Google::Protobuf::Internal::Arena] Arena to create Message instances, if needed
+        def convert_upb_to_ruby(message_value, c_type, msg_or_enum_def = nil, arena = nil)
+          throw TypeError.new "Expected MessageValue but got #{message_value.class}" unless message_value.is_a? Google::Protobuf::FFI::MessageValue
+
+          case c_type
+          when :bool
+            message_value[:bool_val]
+          when :int32
+            message_value[:int32_val]
+          when :uint32
+            message_value[:uint32_val]
+          when :double
+            message_value[:double_val]
+          when :int64
+            message_value[:int64_val]
+          when :uint64
+            message_value[:uint64_val]
+          when :string
+            if message_value[:str_val][:size].zero?
+              ""
+            else
+              message_value[:str_val][:data].read_string_length(message_value[:str_val][:size]).force_encoding("UTF-8").freeze
+            end
+          when :bytes
+            if message_value[:str_val][:size].zero?
+              ""
+            else
+              message_value[:str_val][:data].read_string_length(message_value[:str_val][:size]).force_encoding("ASCII-8BIT").freeze
+            end
+          when :float
+            message_value[:float_val]
+          when :enum
+            EnumDescriptor.send(:lookup_value, msg_or_enum_def, message_value[:int32_val]) || message_value[:int32_val]
+          when :message
+            raise "Null Arena for message" if arena.nil?
+            Descriptor.send(:get_message, message_value[:msg_val], msg_or_enum_def, arena)
+          else
+            raise RuntimeError.new "Unexpected type #{c_type}"
+          end
+        end
+
+        def to_h_internal(msg, message_descriptor)
+          return nil if msg.nil? or msg.null?
+          hash = {}
+          is_proto2 = Google::Protobuf::FFI.message_def_syntax(message_descriptor) == :Proto2
+          message_descriptor.each do |field_descriptor|
+            # TODO: Legacy behavior, remove when we fix the is_proto2 differences.
+            if !is_proto2 and
+              field_descriptor.sub_message? and
+              !field_descriptor.repeated? and
+              !Google::Protobuf::FFI.get_message_has(msg, field_descriptor)
+              hash[field_descriptor.name.to_sym] = nil
+              next
+            end
+
+            # Do not include fields that are not present (oneof or optional fields).
+            if is_proto2 and field_descriptor.has_presence? and !Google::Protobuf::FFI.get_message_has(msg, field_descriptor)
+              next
+            end
+
+            message_value = Google::Protobuf::FFI.get_message_value msg, field_descriptor
+
+            # Proto2 omits empty map/repeated fields also.
+            if field_descriptor.map?
+              hash_entry = map_create_hash(message_value[:map_val], field_descriptor)
+            elsif field_descriptor.repeated?
+              array = message_value[:array_val]
+              if is_proto2 and (array.null? || Google::Protobuf::FFI.array_size(array).zero?)
+                next
+              end
+              hash_entry = repeated_field_create_array(array, field_descriptor, field_descriptor.type)
+            else
+              hash_entry = scalar_create_hash(message_value, field_descriptor.type, field_descriptor: field_descriptor)
+            end
+
+            hash[field_descriptor.name.to_sym] = hash_entry
+
+          end
+
+          hash
+        end
+
+        def map_create_hash(map_ptr, field_descriptor)
+          return {} if map_ptr.nil? or map_ptr.null?
+          return_value = {}
+
+          message_descriptor = field_descriptor.send(:subtype)
+          key_field_def = Google::Protobuf::FFI.get_field_by_number(message_descriptor, 1)
+          key_field_type = Google::Protobuf::FFI.get_type(key_field_def)
+
+          value_field_def = Google::Protobuf::FFI.get_field_by_number(message_descriptor, 2)
+          value_field_type = Google::Protobuf::FFI.get_type(value_field_def)
+
+          iter = ::FFI::MemoryPointer.new(:size_t, 1)
+          iter.write(:size_t, Google::Protobuf::FFI::Upb_Map_Begin)
+          while Google::Protobuf::FFI.map_next(map_ptr, iter) do
+            iter_size_t = iter.read(:size_t)
+            key_message_value = Google::Protobuf::FFI.map_key(map_ptr, iter_size_t)
+            value_message_value = Google::Protobuf::FFI.map_value(map_ptr, iter_size_t)
+            hash_key = convert_upb_to_ruby(key_message_value, key_field_type)
+            hash_value = scalar_create_hash(value_message_value, value_field_type, msg_or_enum_descriptor: value_field_def.subtype)
+            return_value[hash_key] = hash_value
+          end
+          return_value
+        end
+
+        def repeated_field_create_array(array, field_descriptor, type)
+          return_value = []
+          n = (array.nil? || array.null?) ? 0 : Google::Protobuf::FFI.array_size(array)
+          0.upto(n - 1) do |i|
+            message_value = Google::Protobuf::FFI.get_msgval_at(array, i)
+            return_value << scalar_create_hash(message_value, type, field_descriptor: field_descriptor)
+          end
+          return_value
+        end
+
+        # @param field_descriptor [FieldDescriptor] Descriptor of the field to convert to a hash.
+        def scalar_create_hash(message_value, type, field_descriptor: nil, msg_or_enum_descriptor: nil)
+          if [:message, :enum].include? type
+            if field_descriptor.nil?
+              if msg_or_enum_descriptor.nil?
+                raise "scalar_create_hash requires either a FieldDescriptor, MessageDescriptor, or EnumDescriptor as an argument, but received only nil"
+              end
+            else
+              msg_or_enum_descriptor = field_descriptor.subtype
+            end
+            if type == :message
+              to_h_internal(message_value[:msg_val], msg_or_enum_descriptor)
+            elsif type == :enum
+              convert_upb_to_ruby message_value, type, msg_or_enum_descriptor
+            end
+          else
+            convert_upb_to_ruby message_value, type
+          end
+        end
+
+        def message_value_deep_copy(message_value, type, descriptor, arena)
+          raise unless message_value.is_a? Google::Protobuf::FFI::MessageValue
+          new_message_value = Google::Protobuf::FFI::MessageValue.new
+          case type
+          when :string, :bytes
+            # TODO(jatl) - how important is it to still use arena malloc, versus using FFI MemoryPointers?
+            new_message_value[:str_val][:size] = message_value[:str_val][:size]
+            new_message_value[:str_val][:data] = Google::Protobuf::FFI.arena_malloc(arena, message_value[:str_val][:size])
+            raise NoMemoryError.new "Allocation failed" if  new_message_value[:str_val][:data].nil? or new_message_value[:str_val][:data].null?
+            Google::Protobuf::FFI.memcpy(new_message_value[:str_val][:data], message_value[:str_val][:data], message_value[:str_val][:size])
+          when :message
+            new_message_value[:msg_val] = descriptor.msgclass.send(:deep_copy, message_value[:msg_val], arena).instance_variable_get(:@msg)
+          else
+            Google::Protobuf::FFI.memcpy(new_message_value.to_ptr, message_value.to_ptr, Google::Protobuf::FFI::MessageValue.size)
+          end
+          new_message_value
+        end
+      end
+    end
+  end
+end

ruby/lib/google/protobuf/ffi/internal/pointer_helper.rb

@@ -0,0 +1,58 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2023 Google Inc.  All rights reserved.
+# https://developers.google.com/protocol-buffers/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+module Google
+  module Protobuf
+    module Internal
+      module PointerHelper
+        # Utility code to defensively walk the object graph from a file_def to
+        # the pool, and either retrieve the wrapper object for the given pointer
+        # or create one. Assumes that the caller is the wrapper class for the
+        # given pointer and that it implements `private_constructor`.
+        def descriptor_from_file_def(file_def, pointer)
+          raise RuntimeError.new "FileDef is nil" if file_def.nil?
+          raise RuntimeError.new "FileDef is null" if file_def.null?
+          pool_def = Google::Protobuf::FFI.file_def_pool file_def
+          raise RuntimeError.new "PoolDef is nil" if pool_def.nil?
+          raise RuntimeError.new "PoolDef is null" if pool_def.null?
+          pool = Google::Protobuf::OBJECT_CACHE.get(pool_def.address)
+          raise "Cannot find pool in ObjectCache!" if pool.nil?
+          descriptor = pool.descriptor_class_by_def[pointer.address]
+          if descriptor.nil?
+            pool.descriptor_class_by_def[pointer.address] = private_constructor(pointer, pool)
+          else
+            descriptor
+          end
+        end
+      end
+    end
+  end
+end
+

ruby/lib/google/protobuf/ffi/internal/type_safety.rb

@@ -0,0 +1,48 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2022 Google Inc.  All rights reserved.
+# https://developers.google.com/protocol-buffers/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+# A to_native DataConverter method that raises an error if the value is not of the same type.
+# Adapted from to https://www.varvet.com/blog/advanced-topics-in-ruby-ffi/
+module Google
+  module Protobuf
+    module Internal
+      module TypeSafety
+        def to_native(value, ctx = nil)
+          if value.kind_of?(self) or value.nil?
+            super
+          else
+            raise TypeError.new "Expected a kind of #{name}, was #{value.class}"
+          end
+        end
+      end
+    end
+  end
+end
+

ruby/lib/google/protobuf/ffi/map.rb

@@ -0,0 +1,419 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2022 Google Inc.  All rights reserved.
+# https://developers.google.com/protocol-buffers/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+module Google
+  module Protobuf
+    class FFI
+      # Map
+      attach_function :map_clear,  :upb_Map_Clear,                    [:Map], :void
+      attach_function :map_delete, :upb_Map_Delete,                   [:Map, MessageValue.by_value, MessageValue.by_ref], :bool
+      attach_function :map_get,    :upb_Map_Get,                      [:Map, MessageValue.by_value, MessageValue.by_ref], :bool
+      attach_function :create_map, :upb_Map_New,                      [Internal::Arena, CType, CType], :Map
+      attach_function :map_size,   :upb_Map_Size,                     [:Map], :size_t
+      attach_function :map_set,    :upb_Map_Set,                      [:Map, MessageValue.by_value, MessageValue.by_value, Internal::Arena], :bool
+
+      # MapIterator
+      attach_function :map_next,   :upb_MapIterator_Next,             [:Map, :pointer], :bool
+      attach_function :map_done,   :upb_MapIterator_Done,             [:Map, :size_t], :bool
+      attach_function :map_key,    :upb_MapIterator_Key,              [:Map, :size_t], MessageValue.by_value
+      attach_function :map_value,  :upb_MapIterator_Value,            [:Map, :size_t], MessageValue.by_value
+    end
+    class Map
+      include Enumerable
+      ##
+      # call-seq:
+      #    Map.new(key_type, value_type, value_typeclass = nil, init_hashmap = {})
+      #    => new map
+      #
+      # Allocates a new Map container. This constructor may be called with 2, 3, or 4
+      # arguments. The first two arguments are always present and are symbols (taking
+      # on the same values as field-type symbols in message descriptors) that
+      # indicate the type of the map key and value fields.
+      #
+      # The supported key types are: :int32, :int64, :uint32, :uint64, :bool,
+      # :string, :bytes.
+      #
+      # The supported value types are: :int32, :int64, :uint32, :uint64, :bool,
+      # :string, :bytes, :enum, :message.
+      #
+      # The third argument, value_typeclass, must be present if value_type is :enum
+      # or :message. As in RepeatedField#new, this argument must be a message class
+      # (for :message) or enum module (for :enum).
+      #
+      # The last argument, if present, provides initial content for map. Note that
+      # this may be an ordinary Ruby hashmap or another Map instance with identical
+      # key and value types. Also note that this argument may be present whether or
+      # not value_typeclass is present (and it is unambiguously separate from
+      # value_typeclass because value_typeclass's presence is strictly determined by
+      # value_type). The contents of this initial hashmap or Map instance are
+      # shallow-copied into the new Map: the original map is unmodified, but
+      # references to underlying objects will be shared if the value type is a
+      # message type.
+      def self.new(key_type, value_type, value_typeclass = nil, init_hashmap = {})
+        instance = allocate
+        # TODO(jatl) This argument mangling doesn't agree with the type signature,
+        # but does align with the text of the comments and is required to make unit tests pass.
+        if init_hashmap.empty? and ![:enum, :message].include?(value_type)
+          init_hashmap = value_typeclass
+          value_typeclass = nil
+        end
+        instance.send(:initialize, key_type, value_type, value_type_class: value_typeclass, initial_values: init_hashmap)
+        instance
+      end
+
+      ##
+      # call-seq:
+      #     Map.keys => [list_of_keys]
+      #
+      # Returns the list of keys contained in the map, in unspecified order.
+      def keys
+        return_value = []
+        internal_iterator do |iterator|
+          key_message_value = Google::Protobuf::FFI.map_key(@map_ptr, iterator)
+          return_value << convert_upb_to_ruby(key_message_value, key_type)
+        end
+        return_value
+      end
+
+      ##
+      # call-seq:
+      #     Map.values => [list_of_values]
+      #
+      # Returns the list of values contained in the map, in unspecified order.
+      def values
+        return_value = []
+        internal_iterator do |iterator|
+          value_message_value = Google::Protobuf::FFI.map_value(@map_ptr, iterator)
+          return_value << convert_upb_to_ruby(value_message_value, value_type, descriptor, arena)
+        end
+        return_value
+      end
+
+      ##
+      # call-seq:
+      #    Map.[](key) => value
+      #
+      #  Accesses the element at the given key. Throws an exception if the key type is
+      #  incorrect. Returns nil when the key is not present in the map.
+      def [](key)
+        value = Google::Protobuf::FFI::MessageValue.new
+        key_message_value = convert_ruby_to_upb(key, arena, key_type, nil)
+        if Google::Protobuf::FFI.map_get(@map_ptr, key_message_value, value)
+           convert_upb_to_ruby(value, value_type, descriptor, arena)
+        end
+      end
+
+      ##
+      # call-seq:
+      #     Map.[]=(key, value) => value
+      #
+      # Inserts or overwrites the value at the given key with the given new value.
+      # Throws an exception if the key type is incorrect. Returns the new value that
+      # was just inserted.
+      def []=(key, value)
+        raise FrozenError.new "can't modify frozen #{self.class}" if frozen?
+        key_message_value = convert_ruby_to_upb(key, arena, key_type, nil)
+        value_message_value = convert_ruby_to_upb(value, arena, value_type, descriptor)
+        Google::Protobuf::FFI.map_set(@map_ptr, key_message_value, value_message_value, arena)
+        value
+      end
+
+      def has_key?(key)
+        key_message_value = convert_ruby_to_upb(key, arena, key_type, nil)
+        Google::Protobuf::FFI.map_get(@map_ptr, key_message_value, nil)
+      end
+
+      ##
+      # call-seq:
+      #    Map.delete(key) => old_value
+      #
+      # Deletes the value at the given key, if any, returning either the old value or
+      # nil if none was present. Throws an exception if the key is of the wrong type.
+      def delete(key)
+        raise FrozenError.new "can't modify frozen #{self.class}" if frozen?
+        value = Google::Protobuf::FFI::MessageValue.new
+        key_message_value = convert_ruby_to_upb(key, arena, key_type, nil)
+        if Google::Protobuf::FFI.map_delete(@map_ptr, key_message_value, value)
+          convert_upb_to_ruby(value, value_type, descriptor, arena)
+        else
+          nil
+        end
+      end
+
+      def clear
+        raise FrozenError.new "can't modify frozen #{self.class}" if frozen?
+        Google::Protobuf::FFI.map_clear(@map_ptr)
+        nil
+      end
+
+      def length
+        Google::Protobuf::FFI.map_size(@map_ptr)
+      end
+      alias size length
+
+      ##
+      # call-seq:
+      #    Map.dup => new_map
+      #
+      # Duplicates this map with a shallow copy. References to all non-primitive
+      # element objects (e.g., submessages) are shared.
+      def dup
+        internal_dup
+      end
+      alias clone dup
+
+      ##
+      # call-seq:
+      #     Map.==(other) => boolean
+      #
+      # Compares this map to another. Maps are equal if they have identical key sets,
+      # and for each key, the values in both maps compare equal. Elements are
+      # compared as per normal Ruby semantics, by calling their :== methods (or
+      # performing a more efficient comparison for primitive types).
+      #
+      # Maps with dissimilar key types or value types/typeclasses are never equal,
+      # even if value comparison (for example, between integers and floats) would
+      # have otherwise indicated that every element has equal value.
+      def ==(other)
+        if other.is_a? Hash
+          other = self.class.send(:private_constructor, key_type, value_type, descriptor, initial_values: other)
+        elsif !other.is_a? Google::Protobuf::Map
+          return false
+        end
+
+        return true if object_id == other.object_id
+        return false if key_type != other.send(:key_type) or value_type != other.send(:value_type) or descriptor != other.send(:descriptor) or length != other.length
+        other_map_ptr = other.send(:map_ptr)
+        each_msg_val do |key_message_value, value_message_value|
+          other_value = Google::Protobuf::FFI::MessageValue.new
+          return false unless Google::Protobuf::FFI.map_get(other_map_ptr, key_message_value, other_value)
+          return false unless Google::Protobuf::FFI.message_value_equal(value_message_value, other_value, value_type, descriptor)
+        end
+        true
+      end
+
+      def hash
+        return_value = 0
+        each_msg_val do |key_message_value, value_message_value|
+          return_value = Google::Protobuf::FFI.message_value_hash(key_message_value, key_type, nil, return_value)
+          return_value = Google::Protobuf::FFI.message_value_hash(value_message_value, value_type, descriptor, return_value)
+        end
+        return_value
+      end
+
+      ##
+      # call-seq:
+      #    Map.to_h => {}
+      #
+      # Returns a Ruby Hash object containing all the values within the map
+      def to_h
+        return {} if map_ptr.nil? or map_ptr.null?
+        return_value = {}
+        each_msg_val do |key_message_value, value_message_value|
+          hash_key = convert_upb_to_ruby(key_message_value, key_type)
+          hash_value = scalar_create_hash(value_message_value, value_type, msg_or_enum_descriptor: descriptor)
+          return_value[hash_key] = hash_value
+        end
+        return_value
+      end
+
+      def inspect
+        key_value_pairs = []
+        each_msg_val do |key_message_value, value_message_value|
+          key_string = convert_upb_to_ruby(key_message_value, key_type).inspect
+          if value_type == :message
+            sub_msg_descriptor = Google::Protobuf::FFI.get_subtype_as_message(descriptor)
+            value_string = sub_msg_descriptor.msgclass.send(:inspect_internal, value_message_value[:msg_val])
+          else
+            value_string = convert_upb_to_ruby(value_message_value, value_type, descriptor).inspect
+          end
+          key_value_pairs << "#{key_string}=>#{value_string}"
+        end
+        "{#{key_value_pairs.join(", ")}}"
+      end
+
+      ##
+      # call-seq:
+      #    Map.merge(other_map) => map
+      #
+      # Copies key/value pairs from other_map into a copy of this map. If a key is
+      # set in other_map and this map, the value from other_map overwrites the value
+      # in the new copy of this map. Returns the new copy of this map with merged
+      # contents.
+      def merge(other)
+        internal_merge(other)
+      end
+
+      ##
+      # call-seq:
+      #    Map.each(&block)
+      #
+      # Invokes &block on each |key, value| pair in the map, in unspecified order.
+      # Note that Map also includes Enumerable; map thus acts like a normal Ruby
+      # sequence.
+      def each &block
+        each_msg_val do |key_message_value, value_message_value|
+          key_value = convert_upb_to_ruby(key_message_value, key_type)
+          value_value = convert_upb_to_ruby(value_message_value, value_type, descriptor, arena)
+          yield key_value, value_value
+        end
+        nil
+      end
+
+      private
+      attr :arena, :map_ptr, :key_type, :value_type, :descriptor, :name
+
+      include Google::Protobuf::Internal::Convert
+
+      def internal_iterator
+        iter = ::FFI::MemoryPointer.new(:size_t, 1)
+        iter.write(:size_t, Google::Protobuf::FFI::Upb_Map_Begin)
+        while Google::Protobuf::FFI.map_next(@map_ptr, iter) do
+          iter_size_t = iter.read(:size_t)
+          yield iter_size_t
+        end
+      end
+
+      def each_msg_val &block
+        internal_iterator do |iterator|
+          key_message_value = Google::Protobuf::FFI.map_key(@map_ptr, iterator)
+          value_message_value = Google::Protobuf::FFI.map_value(@map_ptr, iterator)
+          yield key_message_value, value_message_value
+        end
+      end
+
+      def internal_dup
+        instance = self.class.send(:private_constructor, key_type, value_type, descriptor, arena: arena)
+        new_map_ptr = instance.send(:map_ptr)
+        each_msg_val do |key_message_value, value_message_value|
+          Google::Protobuf::FFI.map_set(new_map_ptr, key_message_value, value_message_value, arena)
+        end
+        instance
+      end
+
+      def internal_merge_into_self(other)
+        case other
+        when Hash
+          other.each do |key, value|
+            key_message_value = convert_ruby_to_upb(key, arena, key_type, nil)
+            value_message_value = convert_ruby_to_upb(value, arena, value_type, descriptor)
+            Google::Protobuf::FFI.map_set(@map_ptr, key_message_value, value_message_value, arena)
+          end
+        when Google::Protobuf::Map
+          unless key_type == other.send(:key_type) and value_type == other.send(:value_type) and descriptor == other.descriptor
+            raise ArgumentError.new "Attempt to merge Map with mismatching types" #TODO(jatl) Improve error message by adding type information
+          end
+          arena.fuse(other.send(:arena))
+          iter = ::FFI::MemoryPointer.new(:size_t, 1)
+          iter.write(:size_t, Google::Protobuf::FFI::Upb_Map_Begin)
+          other.send(:each_msg_val) do |key_message_value, value_message_value|
+            Google::Protobuf::FFI.map_set(@map_ptr, key_message_value, value_message_value, arena)
+          end
+        else
+          raise ArgumentError.new "Unknown type merging into Map" #TODO(jatl) improve this error message by including type information
+        end
+        self
+      end
+
+      def internal_merge(other)
+        internal_dup.internal_merge_into_self(other)
+      end
+
+      def initialize(key_type, value_type, value_type_class: nil, initial_values: nil, arena: nil, map: nil, descriptor: nil, name: nil)
+        @name = name || 'Map'
+
+        unless [:int32, :int64, :uint32, :uint64, :bool, :string, :bytes].include? key_type
+          raise ArgumentError.new "Invalid key type for map." #TODO(jatl) improve error message to include what type was passed
+        end
+        @key_type = key_type
+
+        unless [:int32, :int64, :uint32, :uint64, :bool, :string, :bytes, :enum, :message].include? value_type
+          raise ArgumentError.new "Invalid value type for map." #TODO(jatl) improve error message to include what type was passed
+        end
+        @value_type = value_type
+
+        if !descriptor.nil?
+          raise ArgumentError "Expected descriptor to be a Descriptor or EnumDescriptor" unless [EnumDescriptor, Descriptor].include? descriptor.class
+          @descriptor = descriptor
+        elsif [:message, :enum].include? value_type
+          raise ArgumentError.new "Expected at least 3 arguments for message/enum." if value_type_class.nil?
+          descriptor = value_type_class.respond_to?(:descriptor) ? value_type_class.descriptor : nil
+          raise ArgumentError.new "Type class #{value_type_class} has no descriptor. Please pass a class or enum as returned by the DescriptorPool." if descriptor.nil?
+          @descriptor = descriptor
+        else
+          @descriptor = nil
+        end
+
+        @arena = arena || Google::Protobuf::FFI.create_arena
+        @map_ptr = map || Google::Protobuf::FFI.create_map(@arena, @key_type, @value_type)
+
+        internal_merge_into_self(initial_values) unless initial_values.nil?
+
+        # Should always be the last expression of the initializer to avoid
+        # leaking references to this object before construction is complete.
+        OBJECT_CACHE.try_add(@map_ptr.address, self)
+      end
+
+      # @param field [FieldDescriptor] Descriptor of the field where the RepeatedField will be assigned
+      # @param values [Hash|Map] Initial value; may be nil or empty
+      # @param arena [Arena] Owning message's arena
+      def self.construct_for_field(field, arena, value: nil, map: nil)
+        raise ArgumentError.new "Expected Hash object as initializer value for map field '#{field.name}' (given #{value.class})." unless value.nil? or value.is_a? Hash
+        instance = allocate
+        raise ArgumentError.new "Expected field with type :message, instead got #{field.class}" unless field.type == :message
+        message_descriptor = field.send(:subtype)
+        key_field_def = Google::Protobuf::FFI.get_field_by_number(message_descriptor, 1)
+        key_field_type = Google::Protobuf::FFI.get_type(key_field_def)
+
+        value_field_def = Google::Protobuf::FFI.get_field_by_number(message_descriptor, 2)
+        value_field_type = Google::Protobuf::FFI.get_type(value_field_def)
+        instance.send(:initialize, key_field_type, value_field_type, initial_values: value, name: field.name, arena: arena, map: map, descriptor: value_field_def.subtype)
+        instance
+      end
+
+      def self.private_constructor(key_type, value_type, descriptor, initial_values: nil, arena: nil)
+        instance = allocate
+        instance.send(:initialize, key_type, value_type, descriptor: descriptor, initial_values: initial_values, arena: arena)
+        instance
+      end
+
+      extend Google::Protobuf::Internal::Convert
+
+      def self.deep_copy(map)
+        instance = allocate
+        instance.send(:initialize, map.send(:key_type), map.send(:value_type), descriptor: map.send(:descriptor))
+        map.send(:each_msg_val) do |key_message_value, value_message_value|
+          Google::Protobuf::FFI.map_set(instance.send(:map_ptr), key_message_value, message_value_deep_copy(value_message_value, map.send(:value_type), map.send(:descriptor), instance.send(:arena)), instance.send(:arena))
+        end
+        instance
+      end
+    end
+  end
+end

ruby/lib/google/protobuf/ffi/message.rb

@@ -0,0 +1,658 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2023 Google Inc.  All rights reserved.
+# https://developers.google.com/protocol-buffers/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+
+# Decorates Descriptor with the `build_message_class` method that defines
+# Message classes.
+module Google
+  module Protobuf
+    class FFI
+      # Message
+      attach_function :clear_message_field,     :upb_Message_ClearFieldByDef, [:Message, FieldDescriptor], :void
+      attach_function :get_message_value,       :upb_Message_GetFieldByDef,   [:Message, FieldDescriptor], MessageValue.by_value
+      attach_function :get_message_has,         :upb_Message_HasFieldByDef,   [:Message, FieldDescriptor], :bool
+      attach_function :set_message_field,       :upb_Message_SetFieldByDef,   [:Message, FieldDescriptor, MessageValue.by_value, Internal::Arena], :bool
+      attach_function :encode_message,          :upb_Encode,                  [:Message, MiniTable.by_ref, :size_t, Internal::Arena, :pointer, :pointer], EncodeStatus
+      attach_function :json_decode_message,     :upb_JsonDecode,              [:binary_string, :size_t, :Message, Descriptor, :DefPool, :int, Internal::Arena, Status.by_ref], :bool
+      attach_function :json_encode_message,     :upb_JsonEncode,              [:Message, Descriptor, :DefPool, :int, :binary_string, :size_t, Status.by_ref], :size_t
+      attach_function :decode_message,          :upb_Decode,                              [:binary_string, :size_t, :Message, MiniTable.by_ref, :ExtensionRegistry, :int, Internal::Arena], DecodeStatus
+      attach_function :get_mutable_message,     :upb_Message_Mutable,         [:Message, FieldDescriptor, Internal::Arena], MutableMessageValue.by_value
+      attach_function :get_message_which_oneof, :upb_Message_WhichOneof,      [:Message, OneofDescriptor], FieldDescriptor
+      attach_function :message_discard_unknown, :upb_Message_DiscardUnknown,  [:Message, Descriptor, :int], :bool
+      # MessageValue
+      attach_function :message_value_equal,     :shared_Msgval_IsEqual,       [MessageValue.by_value, MessageValue.by_value, CType, Descriptor], :bool
+      attach_function :message_value_hash,      :shared_Msgval_GetHash,       [MessageValue.by_value, CType, Descriptor, :uint64_t], :uint64_t
+    end
+
+    class Descriptor
+      def build_message_class
+        descriptor = self
+        Class.new(Google::Protobuf::const_get(:AbstractMessage)) do
+          @descriptor = descriptor
+          class << self
+            attr_accessor :descriptor
+            private
+            attr_accessor :oneof_field_names
+            include ::Google::Protobuf::Internal::Convert
+          end
+
+          alias original_method_missing method_missing
+          def method_missing(method_name, *args)
+            method_missing_internal method_name, *args, mode: :method_missing
+          end
+
+          def respond_to_missing?(method_name, include_private = false)
+            method_missing_internal(method_name, mode: :respond_to_missing?) || super
+          end
+
+          ##
+          # Public constructor. Automatically allocates from a new Arena.
+          def self.new(initial_value = nil)
+            instance = allocate
+            instance.send(:initialize, initial_value)
+            instance
+          end
+
+          def dup
+            duplicate = self.class.private_constructor(@arena)
+            mini_table = Google::Protobuf::FFI.get_mini_table(self.class.descriptor)
+            size = mini_table[:size]
+            duplicate.instance_variable_get(:@msg).write_string_length(@msg.read_string_length(size), size)
+            duplicate
+          end
+          alias clone dup
+
+          def eql?(other)
+            return false unless self.class === other
+            encoding_options = Google::Protobuf::FFI::Upb_Encode_Deterministic | Google::Protobuf::FFI::Upb_Encode_SkipUnknown
+            temporary_arena = Google::Protobuf::FFI.create_arena
+            mini_table = Google::Protobuf::FFI.get_mini_table(self.class.descriptor)
+            size_one = ::FFI::MemoryPointer.new(:size_t, 1)
+            encoding_one = ::FFI::MemoryPointer.new(:pointer, 1)
+            encoding_status = Google::Protobuf::FFI.encode_message(@msg, mini_table, encoding_options, temporary_arena, encoding_one.to_ptr, size_one)
+            raise ParseError.new "Error comparing messages due to #{encoding_status} while encoding LHS of `eql?()`" unless encoding_status == :Ok
+
+            size_two = ::FFI::MemoryPointer.new(:size_t, 1)
+            encoding_two = ::FFI::MemoryPointer.new(:pointer, 1)
+            encoding_status = Google::Protobuf::FFI.encode_message(other.instance_variable_get(:@msg), mini_table, encoding_options, temporary_arena, encoding_two.to_ptr, size_two)
+            raise ParseError.new "Error comparing messages due to #{encoding_status} while encoding RHS of `eql?()`" unless encoding_status == :Ok
+
+            if encoding_one.null? or encoding_two.null?
+              raise ParseError.new "Error comparing messages"
+            end
+            size_one.read(:size_t) == size_two.read(:size_t) and Google::Protobuf::FFI.memcmp(encoding_one.read(:pointer), encoding_two.read(:pointer), size_one.read(:size_t)).zero?
+          end
+          alias == eql?
+
+          def hash
+            encoding_options = Google::Protobuf::FFI::Upb_Encode_Deterministic | Google::Protobuf::FFI::Upb_Encode_SkipUnknown
+            temporary_arena = Google::Protobuf::FFI.create_arena
+            mini_table_ptr = Google::Protobuf::FFI.get_mini_table(self.class.descriptor)
+            size_ptr = ::FFI::MemoryPointer.new(:size_t, 1)
+            encoding = ::FFI::MemoryPointer.new(:pointer, 1)
+            encoding_status = Google::Protobuf::FFI.encode_message(@msg, mini_table_ptr, encoding_options, temporary_arena, encoding.to_ptr, size_ptr)
+            if encoding_status != :Ok or encoding.null?
+              raise ParseError.new "Error calculating hash"
+            end
+            encoding.read(:pointer).read_string(size_ptr.read(:size_t)).hash
+          end
+
+          def to_h
+            to_h_internal @msg, self.class.descriptor
+          end
+
+          ##
+          # call-seq:
+          #     Message.inspect => string
+          #
+          # Returns a human-readable string representing this message. It will be
+          # formatted as "<MessageType: field1: value1, field2: value2, ...>". Each
+          # field's value is represented according to its own #inspect method.
+          def inspect
+            self.class.inspect_internal @msg
+          end
+
+          def to_s
+            self.inspect
+          end
+
+          ##
+          # call-seq:
+          #     Message.[](index) => value
+          # Accesses a field's value by field name. The provided field name
+          # should be a string.
+          def [](name)
+            raise TypeError.new "Expected String for name but got #{name.class}" unless name.is_a? String
+            index_internal name
+          end
+
+          ##
+          # call-seq:
+          #     Message.[]=(index, value)
+          # Sets a field's value by field name. The provided field name should
+          # be a string.
+          # @param name [String] Name of the field to be set
+          # @param value [Object] Value to set the field to
+          def []=(name, value)
+            raise TypeError.new "Expected String for name but got #{name.class}" unless name.is_a? String
+            index_assign_internal(value, name: name)
+          end
+
+          ##
+          # call-seq:
+          #    MessageClass.decode(data, options) => message
+          #
+          # Decodes the given data (as a string containing bytes in protocol buffers wire
+          # format) under the interpretation given by this message class's definition
+          # and returns a message object with the corresponding field values.
+          # @param data [String] Binary string in Protobuf wire format to decode
+          # @param options [Hash] options for the decoder
+          # @option options [Integer] :recursion_limit Set to maximum decoding depth for message (default is 64)
+          def self.decode(data, options = {})
+            raise ArgumentError.new "Expected hash arguments." unless options.is_a? Hash
+            raise ArgumentError.new "Expected string for binary protobuf data." unless data.is_a? String
+            decoding_options = 0
+            depth = options[:recursion_limit]
+
+            if depth.is_a? Numeric
+              decoding_options |= Google::Protobuf::FFI.decode_max_depth(depth.to_i)
+            end
+
+            message = new
+            mini_table_ptr = Google::Protobuf::FFI.get_mini_table(message.class.descriptor)
+            status = Google::Protobuf::FFI.decode_message(data, data.bytesize, message.instance_variable_get(:@msg), mini_table_ptr, nil, decoding_options, message.instance_variable_get(:@arena))
+            raise ParseError.new "Error occurred during parsing" unless status == :Ok
+            message
+          end
+
+          ##
+          # call-seq:
+          #    MessageClass.encode(msg, options) => bytes
+          #
+          # Encodes the given message object to its serialized form in protocol buffers
+          # wire format.
+          # @param options [Hash] options for the encoder
+          # @option options [Integer] :recursion_limit Set to maximum encoding depth for message (default is 64)
+          def self.encode(message, options = {})
+            raise ArgumentError.new "Message of wrong type." unless message.is_a? self
+            raise ArgumentError.new "Expected hash arguments." unless options.is_a? Hash
+
+            encoding_options = 0
+            depth = options[:recursion_limit]
+
+            if depth.is_a? Numeric
+              encoding_options |= Google::Protobuf::FFI.decode_max_depth(depth.to_i)
+            end
+
+            encode_internal(message.instance_variable_get(:@msg), encoding_options) do |encoding, size, _|
+              if encoding.nil? or encoding.null?
+                raise RuntimeError.new "Exceeded maximum depth (possibly cycle)"
+              else
+                encoding.read_string_length(size).force_encoding("ASCII-8BIT").freeze
+              end
+            end
+          end
+
+          ##
+          # all-seq:
+          #    MessageClass.decode_json(data, options = {}) => message
+          #
+          # Decodes the given data (as a string containing bytes in protocol buffers wire
+          # format) under the interpretation given by this message class's definition
+          # and returns a message object with the corresponding field values.
+          #
+          # @param options [Hash] options for the decoder
+          # @option options [Boolean] :ignore_unknown_fields Set true to ignore unknown fields (default is to raise an error)
+          # @return [Message]
+          def self.decode_json(data, options = {})
+            decoding_options = 0
+            unless options.is_a? Hash
+              if options.respond_to? :to_h
+                options options.to_h
+              else
+                #TODO(jatl) can this error message be improve to include what was received?
+                raise ArgumentError.new "Expected hash arguments"
+              end
+            end
+            raise ArgumentError.new "Expected string for JSON data." unless data.is_a? String
+            raise RuntimeError.new "Cannot parse a wrapper directly" if descriptor.send(:wrapper?)
+
+            if options[:ignore_unknown_fields]
+              decoding_options |= Google::Protobuf::FFI::Upb_JsonDecode_IgnoreUnknown
+            end
+
+            message = new
+            pool_def = message.class.descriptor.instance_variable_get(:@descriptor_pool).descriptor_pool
+            status = Google::Protobuf::FFI::Status.new
+            unless Google::Protobuf::FFI.json_decode_message(data, data.bytesize, message.instance_variable_get(:@msg), message.class.descriptor, pool_def, decoding_options, message.instance_variable_get(:@arena), status)
+              raise ParseError.new "Error occurred during parsing: #{Google::Protobuf::FFI.error_message(status)}"
+            end
+            message
+          end
+
+          def self.encode_json(message, options = {})
+            encoding_options = 0
+            unless options.is_a? Hash
+              if options.respond_to? :to_h
+                options = options.to_h
+              else
+                #TODO(jatl) can this error message be improve to include what was received?
+                raise ArgumentError.new "Expected hash arguments"
+              end
+            end
+
+            if options[:preserve_proto_fieldnames]
+              encoding_options |= Google::Protobuf::FFI::Upb_JsonEncode_UseProtoNames
+            end
+            if options[:emit_defaults]
+              encoding_options |= Google::Protobuf::FFI::Upb_JsonEncode_EmitDefaults
+            end
+            if options[:format_enums_as_integers]
+              encoding_options |= Google::Protobuf::FFI::Upb_JsonEncode_FormatEnumsAsIntegers
+            end
+
+            buffer_size = 1024
+            buffer = ::FFI::MemoryPointer.new(:char, buffer_size)
+            status = Google::Protobuf::FFI::Status.new
+            msg = message.instance_variable_get(:@msg)
+            pool_def = message.class.descriptor.instance_variable_get(:@descriptor_pool).descriptor_pool
+            size = Google::Protobuf::FFI::json_encode_message(msg, message.class.descriptor, pool_def, encoding_options, buffer, buffer_size, status)
+            unless status[:ok]
+              raise ParseError.new "Error occurred during encoding: #{Google::Protobuf::FFI.error_message(status)}"
+            end
+
+            if size >= buffer_size
+              buffer_size = size + 1
+              buffer = ::FFI::MemoryPointer.new(:char, buffer_size)
+              status.clear
+              size = Google::Protobuf::FFI::json_encode_message(msg, message.class.descriptor, pool_def, encoding_options, buffer, buffer_size, status)
+              unless status[:ok]
+                raise ParseError.new "Error occurred during encoding: #{Google::Protobuf::FFI.error_message(status)}"
+              end
+              if size >= buffer_size
+                raise ParseError.new "Inconsistent JSON encoding sizes - was #{buffer_size - 1}, now #{size}"
+              end
+            end
+
+            buffer.read_string_length(size).force_encoding("UTF-8").freeze
+          end
+
+          private
+          # Implementation details below are subject to breaking changes without
+          # warning and are intended for use only within the gem.
+
+          include Google::Protobuf::Internal::Convert
+
+          def self.setup_accessors!
+            @descriptor.each do |field_descriptor|
+              field_name = field_descriptor.name
+              unless instance_methods(true).include?(field_name.to_sym)
+                #TODO(jatl) - at a high level, dispatching to either
+                # index_internal or get_field would be logically correct, but slightly slower.
+                if field_descriptor.map?
+                  define_method(field_name) do
+                    mutable_message_value = Google::Protobuf::FFI.get_mutable_message @msg, field_descriptor, @arena
+                    get_map_field(mutable_message_value[:map], field_descriptor)
+                  end
+                elsif field_descriptor.repeated?
+                  define_method(field_name) do
+                    mutable_message_value = Google::Protobuf::FFI.get_mutable_message @msg, field_descriptor, @arena
+                    get_repeated_field(mutable_message_value[:array], field_descriptor)
+                  end
+                elsif field_descriptor.sub_message?
+                  define_method(field_name) do
+                    return nil unless Google::Protobuf::FFI.get_message_has @msg, field_descriptor
+                    mutable_message = Google::Protobuf::FFI.get_mutable_message @msg, field_descriptor, @arena
+                    sub_message = mutable_message[:msg]
+                    sub_message_def = Google::Protobuf::FFI.get_subtype_as_message(field_descriptor)
+                    Descriptor.send(:get_message, sub_message, sub_message_def, @arena)
+                  end
+                else
+                  c_type = field_descriptor.send(:c_type)
+                  if c_type == :enum
+                    define_method(field_name) do
+                      message_value = Google::Protobuf::FFI.get_message_value @msg, field_descriptor
+                      convert_upb_to_ruby message_value, c_type, Google::Protobuf::FFI.get_subtype_as_enum(field_descriptor)
+                    end
+                  else
+                    define_method(field_name) do
+                      message_value = Google::Protobuf::FFI.get_message_value @msg, field_descriptor
+                      convert_upb_to_ruby message_value, c_type
+                    end
+                  end
+                end
+                define_method("#{field_name}=") do |value|
+                  index_assign_internal(value, field_descriptor: field_descriptor)
+                end
+                define_method("clear_#{field_name}") do
+                  clear_internal(field_descriptor)
+                end
+                if field_descriptor.type == :enum
+                  define_method("#{field_name}_const") do
+                    if field_descriptor.repeated?
+                      return_value = []
+                      get_field(field_descriptor).send(:each_msg_val) do |msg_val|
+                        return_value << msg_val[:int32_val]
+                      end
+                      return_value
+                    else
+                      message_value = Google::Protobuf::FFI.get_message_value @msg, field_descriptor
+                      message_value[:int32_val]
+                    end
+                  end
+                end
+                if !field_descriptor.repeated? and field_descriptor.wrapper?
+                  define_method("#{field_name}_as_value") do
+                    get_field(field_descriptor, unwrap: true)
+                  end
+                  define_method("#{field_name}_as_value=") do |value|
+                    if value.nil?
+                      clear_internal(field_descriptor)
+                    else
+                      index_assign_internal(value, field_descriptor: field_descriptor, wrap: true)
+                    end
+                  end
+                end
+                if field_descriptor.has_presence?
+                  define_method("has_#{field_name}?") do
+                    Google::Protobuf::FFI.get_message_has(@msg, field_descriptor)
+                  end
+                end
+              end
+            end
+          end
+
+          def self.setup_oneof_accessors!
+            @oneof_field_names = []
+            @descriptor.each_oneof do |oneof_descriptor|
+              self.add_oneof_accessors_for! oneof_descriptor
+            end
+          end
+          def self.add_oneof_accessors_for!(oneof_descriptor)
+            field_name = oneof_descriptor.name.to_sym
+            @oneof_field_names << field_name
+            unless instance_methods(true).include?(field_name)
+              define_method(field_name) do
+                field_descriptor = Google::Protobuf::FFI.get_message_which_oneof(@msg, oneof_descriptor)
+                if field_descriptor.nil?
+                  return
+                else
+                  return field_descriptor.name.to_sym
+                end
+              end
+              define_method("clear_#{field_name}") do
+                field_descriptor = Google::Protobuf::FFI.get_message_which_oneof(@msg, oneof_descriptor)
+                unless field_descriptor.nil?
+                  clear_internal(field_descriptor)
+                end
+              end
+              define_method("has_#{field_name}?") do
+                !Google::Protobuf::FFI.get_message_which_oneof(@msg, oneof_descriptor).nil?
+              end
+            end
+          end
+
+          setup_accessors!
+          setup_oneof_accessors!
+
+          def self.private_constructor(arena, msg: nil, initial_value: nil)
+            instance = allocate
+            instance.send(:initialize, initial_value, arena, msg)
+            instance
+          end
+
+          def self.inspect_field(field_descriptor, c_type, message_value)
+            if field_descriptor.sub_message?
+              sub_msg_descriptor = Google::Protobuf::FFI.get_subtype_as_message(field_descriptor)
+              sub_msg_descriptor.msgclass.send(:inspect_internal, message_value[:msg_val])
+            else
+              convert_upb_to_ruby(message_value, c_type, field_descriptor.subtype).inspect
+            end
+          end
+
+          # @param msg [::FFI::Pointer] Pointer to the Message
+          def self.inspect_internal(msg)
+            field_output = []
+            descriptor.each do |field_descriptor|
+              next if field_descriptor.has_presence? && !Google::Protobuf::FFI.get_message_has(msg, field_descriptor)
+              if field_descriptor.map?
+                # TODO(jatl) Adapted - from map#each_msg_val and map#inspect- can this be refactored to reduce echo without introducing a arena allocation?
+                message_descriptor = field_descriptor.subtype
+                key_field_def = Google::Protobuf::FFI.get_field_by_number(message_descriptor, 1)
+                key_field_type = Google::Protobuf::FFI.get_type(key_field_def)
+
+                value_field_def = Google::Protobuf::FFI.get_field_by_number(message_descriptor, 2)
+                value_field_type = Google::Protobuf::FFI.get_type(value_field_def)
+
+                message_value = Google::Protobuf::FFI.get_message_value(msg, field_descriptor)
+                iter = ::FFI::MemoryPointer.new(:size_t, 1)
+                iter.write(:size_t, Google::Protobuf::FFI::Upb_Map_Begin)
+                key_value_pairs = []
+                while Google::Protobuf::FFI.map_next(message_value[:map_val], iter) do
+                  iter_size_t = iter.read(:size_t)
+                  key_message_value = Google::Protobuf::FFI.map_key(message_value[:map_val], iter_size_t)
+                  value_message_value = Google::Protobuf::FFI.map_value(message_value[:map_val], iter_size_t)
+                  key_string = convert_upb_to_ruby(key_message_value, key_field_type).inspect
+                  value_string = inspect_field(value_field_def, value_field_type, value_message_value)
+                  key_value_pairs << "#{key_string}=>#{value_string}"
+                end
+                field_output << "#{field_descriptor.name}: {#{key_value_pairs.join(", ")}}"
+              elsif field_descriptor.repeated?
+                # TODO(jatl) Adapted - from repeated_field#each - can this be refactored to reduce echo?
+                repeated_field_output = []
+                message_value = Google::Protobuf::FFI.get_message_value(msg, field_descriptor)
+                array = message_value[:array_val]
+                n = array.null? ? 0 : Google::Protobuf::FFI.array_size(array)
+                0.upto(n - 1) do |i|
+                  element = Google::Protobuf::FFI.get_msgval_at(array, i)
+                  repeated_field_output << inspect_field(field_descriptor, field_descriptor.send(:c_type), element)
+                end
+                field_output << "#{field_descriptor.name}: [#{repeated_field_output.join(", ")}]"
+              else
+                message_value = Google::Protobuf::FFI.get_message_value msg, field_descriptor
+                rendered_value = inspect_field(field_descriptor, field_descriptor.send(:c_type), message_value)
+                field_output << "#{field_descriptor.name}: #{rendered_value}"
+              end
+            end
+            "<#{name}: #{field_output.join(', ')}>"
+          end
+
+          def self.deep_copy(msg, arena = nil)
+            arena ||= Google::Protobuf::FFI.create_arena
+            encode_internal(msg) do |encoding, size, mini_table_ptr|
+              message = private_constructor(arena)
+              if encoding.nil? or encoding.null? or Google::Protobuf::FFI.decode_message(encoding, size, message.instance_variable_get(:@msg), mini_table_ptr, nil, 0, arena) != :Ok
+                raise ParseError.new "Error occurred copying proto"
+              end
+              message
+            end
+          end
+
+          def self.encode_internal(msg, encoding_options = 0)
+            temporary_arena = Google::Protobuf::FFI.create_arena
+
+            mini_table_ptr = Google::Protobuf::FFI.get_mini_table(descriptor)
+            size_ptr = ::FFI::MemoryPointer.new(:size_t, 1)
+            pointer_ptr = ::FFI::MemoryPointer.new(:pointer, 1)
+            encoding_status = Google::Protobuf::FFI.encode_message(msg, mini_table_ptr, encoding_options, temporary_arena, pointer_ptr.to_ptr, size_ptr)
+            raise "Encoding failed due to #{encoding_status}" unless encoding_status == :Ok
+            yield pointer_ptr.read(:pointer), size_ptr.read(:size_t), mini_table_ptr
+          end
+
+          def method_missing_internal(method_name, *args, mode: nil)
+            raise ArgumentError.new "method_missing_internal called with invalid mode #{mode.inspect}" unless [:respond_to_missing?, :method_missing].include? mode
+
+            #TODO(jatl) not being allowed is not the same thing as not responding, but this is needed to pass tests
+            if method_name.to_s.end_with? '='
+              if self.class.send(:oneof_field_names).include? method_name.to_s[0..-2].to_sym
+                return false if mode == :respond_to_missing?
+                raise RuntimeError.new "Oneof accessors are read-only."
+              end
+            end
+
+            original_method_missing(method_name, *args) if mode == :method_missing
+          end
+
+          def clear_internal(field_def)
+            raise FrozenError.new "can't modify frozen #{self.class}" if frozen?
+            Google::Protobuf::FFI.clear_message_field(@msg, field_def)
+          end
+
+          def index_internal(name)
+            field_descriptor = self.class.descriptor.lookup(name)
+            get_field field_descriptor unless field_descriptor.nil?
+          end
+
+          #TODO(jatl) - well known types keeps us on our toes by overloading methods.
+          # How much of the public API needs to be defended?
+          def index_assign_internal(value, name: nil, field_descriptor: nil, wrap: false)
+            raise FrozenError.new "can't modify frozen #{self.class}" if frozen?
+            if field_descriptor.nil?
+              field_descriptor = self.class.descriptor.lookup(name)
+              if field_descriptor.nil?
+                raise ArgumentError.new "Unknown field: #{name}"
+              end
+            end
+            unless field_descriptor.send :set_value_on_message, value, @msg, @arena, wrap: wrap
+              raise RuntimeError.new "allocation failed"
+            end
+          end
+
+          ##
+          # @param initial_value [Object] initial value of this Message
+          # @param arena [Arena] Optional; Arena where this message will be allocated
+          # @param msg [::FFI::Pointer] Optional; Message to initialize; creates
+          #   one if omitted or nil.
+          def initialize(initial_value = nil, arena = nil, msg = nil)
+            @arena = arena || Google::Protobuf::FFI.create_arena
+            @msg = msg || Google::Protobuf::FFI.new_message_from_def(self.class.descriptor, @arena)
+
+            unless initial_value.nil?
+              raise ArgumentError.new "Expected hash arguments or message, not #{initial_value.class}" unless initial_value.respond_to? :each
+
+              field_def_ptr = ::FFI::MemoryPointer.new :pointer
+              oneof_def_ptr = ::FFI::MemoryPointer.new :pointer
+
+              initial_value.each do |key, value|
+                raise ArgumentError.new "Expected string or symbols as hash keys when initializing proto from hash." unless [String, Symbol].include? key.class
+
+                unless Google::Protobuf::FFI.find_msg_def_by_name self.class.descriptor, key.to_s, key.to_s.bytesize, field_def_ptr, oneof_def_ptr
+                  raise ArgumentError.new "Unknown field name '#{key}' in initialization map entry."
+                end
+                raise NotImplementedError.new "Haven't added oneofsupport yet" unless oneof_def_ptr.get_pointer(0).null?
+                raise NotImplementedError.new "Expected a field def" if field_def_ptr.get_pointer(0).null?
+
+                field_descriptor = FieldDescriptor.from_native field_def_ptr.get_pointer(0)
+
+                next if value.nil?
+                if field_descriptor.map?
+                  index_assign_internal(Google::Protobuf::Map.send(:construct_for_field, field_descriptor, @arena, value: value), name: key.to_s)
+                elsif field_descriptor.repeated?
+                  index_assign_internal(RepeatedField.send(:construct_for_field, field_descriptor, @arena, values: value), name: key.to_s)
+                else
+                  index_assign_internal(value, name: key.to_s)
+                end
+              end
+            end
+
+            # Should always be the last expression of the initializer to avoid
+            # leaking references to this object before construction is complete.
+            Google::Protobuf::OBJECT_CACHE.try_add @msg.address, self
+          end
+
+          ##
+          # Gets a field of this message identified by the argument definition.
+          #
+          # @param field [FieldDescriptor] Descriptor of the field to get
+          def get_field(field, unwrap: false)
+            if field.map?
+              mutable_message_value = Google::Protobuf::FFI.get_mutable_message @msg, field, @arena
+              get_map_field(mutable_message_value[:map], field)
+            elsif field.repeated?
+              mutable_message_value = Google::Protobuf::FFI.get_mutable_message @msg, field, @arena
+              get_repeated_field(mutable_message_value[:array], field)
+            elsif field.sub_message?
+              return nil unless Google::Protobuf::FFI.get_message_has @msg, field
+              sub_message_def = Google::Protobuf::FFI.get_subtype_as_message(field)
+              if unwrap
+                if field.has?(self)
+                  wrapper_message_value = Google::Protobuf::FFI.get_message_value @msg, field
+                  fields = Google::Protobuf::FFI.field_count(sub_message_def)
+                  raise "Sub message has #{fields} fields! Expected exactly 1." unless fields == 1
+                  value_field_def = Google::Protobuf::FFI.get_field_by_number sub_message_def, 1
+                  message_value = Google::Protobuf::FFI.get_message_value wrapper_message_value[:msg_val], value_field_def
+                  convert_upb_to_ruby message_value, Google::Protobuf::FFI.get_c_type(value_field_def)
+                else
+                  nil
+                end
+              else
+                mutable_message = Google::Protobuf::FFI.get_mutable_message @msg, field, @arena
+                sub_message = mutable_message[:msg]
+                Descriptor.send(:get_message, sub_message, sub_message_def, @arena)
+              end
+            else
+              c_type = field.send(:c_type)
+              message_value = Google::Protobuf::FFI.get_message_value @msg, field
+              if c_type == :enum
+                convert_upb_to_ruby message_value, c_type, Google::Protobuf::FFI.get_subtype_as_enum(field)
+              else
+                convert_upb_to_ruby message_value, c_type
+              end
+            end
+          end
+
+          ##
+          # @param array [::FFI::Pointer] Pointer to the Array
+          # @param field [Google::Protobuf::FieldDescriptor] Type of the repeated field
+          def get_repeated_field(array, field)
+            return nil if array.nil? or array.null?
+            repeated_field = OBJECT_CACHE.get(array.address)
+            if repeated_field.nil?
+              repeated_field = RepeatedField.send(:construct_for_field, field, @arena, array: array)
+            end
+            repeated_field
+          end
+
+          ##
+          # @param map [::FFI::Pointer] Pointer to the Map
+          # @param field [Google::Protobuf::FieldDescriptor] Type of the map field
+          def get_map_field(map, field)
+            return nil if map.nil? or map.null?
+            map_field = OBJECT_CACHE.get(map.address)
+            if map_field.nil?
+              map_field = Google::Protobuf::Map.send(:construct_for_field, field, @arena, map: map)
+            end
+            map_field
+          end
+        end
+      end
+    end
+  end
+end

ruby/lib/google/protobuf/ffi/object_cache.rb

@@ -0,0 +1,53 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2022 Google Inc.  All rights reserved.
+# https://developers.google.com/protocol-buffers/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+module Google
+  module Protobuf
+    private
+
+    SIZEOF_LONG = ::FFI::MemoryPointer.new(:long).size
+    SIZEOF_VALUE = ::FFI::Pointer::SIZE
+
+    def self.interpreter_supports_non_finalized_keys_in_weak_map?
+      ! defined? JRUBY_VERSION
+    end
+
+    def self.cache_implementation
+      if interpreter_supports_non_finalized_keys_in_weak_map? and SIZEOF_LONG >= SIZEOF_VALUE
+        Google::Protobuf::ObjectCache
+      else
+        Google::Protobuf::LegacyObjectCache
+      end
+    end
+
+    public
+    OBJECT_CACHE = cache_implementation.new
+  end
+end

ruby/lib/google/protobuf/ffi/oneof_descriptor.rb

@@ -0,0 +1,111 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2022 Google Inc.  All rights reserved.
+# https://developers.google.com/protocol-buffers/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+module Google
+  module Protobuf
+    class OneofDescriptor
+      attr :descriptor_pool, :oneof_def
+      include Enumerable
+
+      # FFI Interface methods and setup
+      extend ::FFI::DataConverter
+      native_type ::FFI::Type::POINTER
+
+      class << self
+        prepend Google::Protobuf::Internal::TypeSafety
+        include Google::Protobuf::Internal::PointerHelper
+
+        # @param value [OneofDescriptor] FieldDescriptor to convert to an FFI native type
+        # @param _ [Object] Unused
+        def to_native(value, _ = nil)
+          oneof_def_ptr = value.instance_variable_get(:@oneof_def)
+          warn "Underlying oneof_def was nil!" if oneof_def_ptr.nil?
+          raise "Underlying oneof_def was null!" if !oneof_def_ptr.nil? and oneof_def_ptr.null?
+          oneof_def_ptr
+        end
+
+        ##
+        # @param oneof_def [::FFI::Pointer] OneofDef pointer to be wrapped
+        # @param _ [Object] Unused
+        def from_native(oneof_def, _ = nil)
+          return nil if oneof_def.nil? or oneof_def.null?
+          message_descriptor = Google::Protobuf::FFI.get_oneof_containing_type oneof_def
+          raise RuntimeError.new "Message Descriptor is nil" if message_descriptor.nil?
+          file_def = Google::Protobuf::FFI.get_message_file_def message_descriptor.to_native
+          descriptor_from_file_def(file_def, oneof_def)
+        end
+      end
+
+      def self.new(*arguments, &block)
+        raise "OneofDescriptor objects may not be created from Ruby."
+      end
+
+      def name
+        Google::Protobuf::FFI.get_oneof_name(self)
+      end
+
+      def each &block
+        n = Google::Protobuf::FFI.get_oneof_field_count(self)
+        0.upto(n-1) do |i|
+          yield(Google::Protobuf::FFI.get_oneof_field_by_index(self, i))
+        end
+        nil
+      end
+
+      private
+
+      def initialize(oneof_def, descriptor_pool)
+        @descriptor_pool = descriptor_pool
+        @oneof_def = oneof_def
+      end
+
+      def self.private_constructor(oneof_def, descriptor_pool)
+        instance = allocate
+        instance.send(:initialize, oneof_def, descriptor_pool)
+        instance
+      end
+    end
+
+    class FFI
+      # MessageDef
+      attach_function :get_oneof_by_name,    :upb_MessageDef_FindOneofByNameWithSize, [Descriptor, :string, :size_t], OneofDescriptor
+      attach_function :get_oneof_by_index,   :upb_MessageDef_Oneof,                   [Descriptor, :int], OneofDescriptor
+
+      # OneofDescriptor
+      attach_function :get_oneof_name,           :upb_OneofDef_Name,          [OneofDescriptor], :string
+      attach_function :get_oneof_field_count,    :upb_OneofDef_FieldCount,    [OneofDescriptor], :int
+      attach_function :get_oneof_field_by_index, :upb_OneofDef_Field,         [OneofDescriptor, :int], FieldDescriptor
+      attach_function :get_oneof_containing_type,:upb_OneofDef_ContainingType,[:pointer], Descriptor
+
+      # FieldDescriptor
+      attach_function :real_containing_oneof,      :upb_FieldDef_RealContainingOneof,[FieldDescriptor], OneofDescriptor
+    end
+  end
+end

ruby/lib/google/protobuf/ffi/repeated_field.rb

@@ -0,0 +1,526 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# https://developers.google.com/protocol-buffers/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+require 'forwardable'
+
+#
+# This class makes RepeatedField act (almost-) like a Ruby Array.
+# It has convenience methods that extend the core C or Java based
+# methods.
+#
+# This is a best-effort to mirror Array behavior.  Two comments:
+#  1) patches always welcome :)
+#  2) if performance is an issue, feel free to rewrite the method
+#     in jruby and C.  The source code has plenty of examples
+#
+# KNOWN ISSUES
+#   - #[]= doesn't allow less used approaches such as `arr[1, 2] = 'fizz'`
+#   - #concat should return the orig array
+#   - #push should accept multiple arguments and push them all at the same time
+#
+module Google
+  module Protobuf
+    class FFI
+      # Array
+      attach_function :append_array, :upb_Array_Append,        [:Array, MessageValue.by_value, Internal::Arena], :bool
+      attach_function :get_msgval_at,:upb_Array_Get,           [:Array, :size_t], MessageValue.by_value
+      attach_function :create_array, :upb_Array_New,           [Internal::Arena, CType], :Array
+      attach_function :array_resize, :upb_Array_Resize,        [:Array, :size_t, Internal::Arena], :bool
+      attach_function :array_set,    :upb_Array_Set,           [:Array, :size_t, MessageValue.by_value], :void
+      attach_function :array_size,   :upb_Array_Size,          [:Array], :size_t
+    end
+
+    class RepeatedField
+      extend Forwardable
+      # NOTE:  using delegators rather than method_missing to make the
+      #        relationship explicit instead of implicit
+      def_delegators :to_ary,
+        :&, :*, :-, :'<=>',
+        :assoc, :bsearch, :bsearch_index, :combination, :compact, :count,
+        :cycle, :dig, :drop, :drop_while, :eql?, :fetch, :find_index, :flatten,
+        :include?, :index, :inspect, :join,
+        :pack, :permutation, :product, :pretty_print, :pretty_print_cycle,
+        :rassoc, :repeated_combination, :repeated_permutation, :reverse,
+        :rindex, :rotate, :sample, :shuffle, :shelljoin,
+        :to_s, :transpose, :uniq, :|
+
+      include Enumerable
+
+      ##
+      # call-seq:
+      #     RepeatedField.new(type, type_class = nil, initial_values = [])
+      #
+      # Creates a new repeated field. The provided type must be a Ruby symbol, and
+      # an take on the same values as those accepted by FieldDescriptor#type=. If
+      # the type is :message or :enum, type_class must be non-nil, and must be the
+      # Ruby class or module returned by Descriptor#msgclass or
+      # EnumDescriptor#enummodule, respectively. An initial list of elements may also
+      # be provided.
+      def self.new(type, type_class = nil, initial_values = [])
+        instance = allocate
+        # TODO(jatl) This argument mangling doesn't agree with the type signature in the comments
+        # but is required to make unit tests pass;
+        if type_class.is_a?(Enumerable) and initial_values.empty? and ![:enum, :message].include?(type)
+          initial_values = type_class
+          type_class = nil
+        end
+        instance.send(:initialize, type, type_class: type_class, initial_values: initial_values)
+        instance
+      end
+
+      ##
+      # call-seq:
+      #     RepeatedField.each(&block)
+      #
+      # Invokes the block once for each element of the repeated field. RepeatedField
+      # also includes Enumerable; combined with this method, the repeated field thus
+      # acts like an ordinary Ruby sequence.
+      def each &block
+        each_msg_val do |element|
+          yield(convert_upb_to_ruby(element, type, descriptor, arena))
+        end
+        self
+      end
+
+      def [](*args)
+        count = length
+        if args.size < 1
+          raise ArgumentError.new "Index or range is a required argument."
+        end
+        if args[0].is_a? Range
+          if args.size > 1
+            raise ArgumentError.new "Expected 1 when passing Range argument, but got #{args.size}"
+          end
+          range = args[0]
+          # Handle begin-less and/or endless ranges, when supported.
+          index_of_first = range.respond_to?(:begin) ? range.begin : range.last
+          index_of_first = 0 if index_of_first.nil?
+          end_of_range = range.respond_to?(:end) ? range.end : range.last
+          index_of_last = end_of_range.nil? ? -1 : end_of_range
+
+          if index_of_last < 0
+            index_of_last += count
+          end
+          unless range.exclude_end? and !end_of_range.nil?
+            index_of_last += 1
+          end
+          index_of_first += count if index_of_first < 0
+          length = index_of_last - index_of_first
+          return [] if length.zero?
+        elsif args[0].is_a? Integer
+          index_of_first = args[0]
+          index_of_first += count if index_of_first < 0
+          if args.size > 2
+            raise ArgumentError.new "Expected 1 or 2 arguments, but got #{args.size}"
+          end
+          if args.size == 1 # No length specified, return one element
+            if array.null? or index_of_first < 0 or index_of_first >= count
+              return nil
+            else
+              return convert_upb_to_ruby(Google::Protobuf::FFI.get_msgval_at(array, index_of_first), type, descriptor, arena)
+            end
+          else
+            length = [args[1],count].min
+          end
+        else
+          raise NotImplementedError
+        end
+
+        if array.null? or index_of_first < 0 or index_of_first >= count
+          nil
+        else
+          if index_of_first + length > count
+            length = count - index_of_first
+          end
+          if length < 0
+            nil
+          else
+            subarray(index_of_first, length)
+          end
+        end
+      end
+      alias at []
+
+
+      def []=(index, value)
+        raise FrozenError if frozen?
+        count = length
+        index += count if index < 0
+        return nil if index < 0
+        if index >= count
+          resize(index+1)
+          empty_message_value = Google::Protobuf::FFI::MessageValue.new # Implicitly clear
+          count.upto(index-1) do |i|
+            Google::Protobuf::FFI.array_set(array, i, empty_message_value)
+          end
+        end
+        Google::Protobuf::FFI.array_set(array, index, convert_ruby_to_upb(value, arena, type, descriptor))
+        nil
+      end
+
+      def push(*elements)
+        raise FrozenError if frozen?
+        internal_push(*elements)
+      end
+
+      def <<(element)
+        raise FrozenError if frozen?
+        push element
+      end
+
+      def replace(replacements)
+        raise FrozenError if frozen?
+        clear
+        push(*replacements)
+      end
+
+      def clear
+        raise FrozenError if frozen?
+        resize 0
+        self
+      end
+
+      def length
+        array.null? ? 0 : Google::Protobuf::FFI.array_size(array)
+      end
+      alias size :length
+
+      def dup
+        instance = self.class.allocate
+        instance.send(:initialize, type, descriptor: descriptor, arena: arena)
+        each_msg_val do |element|
+          instance.send(:append_msg_val, element)
+        end
+        instance
+      end
+      alias clone dup
+
+      def ==(other)
+        return true if other.object_id == object_id
+        if other.is_a? RepeatedField
+          return false unless other.length == length
+          each_msg_val_with_index do |msg_val, i|
+            other_msg_val = Google::Protobuf::FFI.get_msgval_at(other.send(:array), i)
+            unless Google::Protobuf::FFI.message_value_equal(msg_val, other_msg_val, type, descriptor)
+              return false
+            end
+          end
+          return true
+        elsif other.is_a? Enumerable
+          return to_ary == other.to_a
+        end
+        false
+      end
+
+      ##
+      # call-seq:
+      #    RepeatedField.to_ary => array
+      #
+      # Used when converted implicitly into array, e.g. compared to an Array.
+      # Also called as a fallback of Object#to_a
+      def to_ary
+        return_value = []
+        each do |element|
+          return_value << element
+        end
+        return_value
+      end
+
+      def hash
+        return_value = 0
+        each_msg_val do |msg_val|
+          return_value = Google::Protobuf::FFI.message_value_hash(msg_val, type, descriptor, return_value)
+        end
+        return_value
+      end
+
+      def +(other)
+        if other.is_a? RepeatedField
+          if type != other.instance_variable_get(:@type) or descriptor != other.instance_variable_get(:@descriptor)
+            raise ArgumentError.new "Attempt to append RepeatedField with different element type."
+          end
+          fuse_arena(other.send(:arena))
+          super_set = dup
+          other.send(:each_msg_val) do |msg_val|
+            super_set.send(:append_msg_val, msg_val)
+          end
+          super_set
+        elsif other.is_a? Enumerable
+          super_set = dup
+          super_set.push(*other.to_a)
+        else
+          raise ArgumentError.new "Unknown type appending to RepeatedField"
+        end
+      end
+
+      def concat(other)
+        raise ArgumentError.new "Expected Enumerable, but got #{other.class}" unless other.is_a? Enumerable
+        push(*other.to_a)
+      end
+
+      def first(n=nil)
+        if n.nil?
+          return self[0]
+        elsif n < 0
+          raise ArgumentError, "negative array size"
+        else
+          return self[0...n]
+        end
+      end
+
+
+      def last(n=nil)
+        if n.nil?
+          return self[-1]
+        elsif n < 0
+          raise ArgumentError, "negative array size"
+        else
+          start = [self.size-n, 0].max
+          return self[start...self.size]
+        end
+      end
+
+
+      def pop(n=nil)
+        if n
+          results = []
+          n.times{ results << pop_one }
+          return results
+        else
+          return pop_one
+        end
+      end
+
+
+      def empty?
+        self.size == 0
+      end
+
+      # array aliases into enumerable
+      alias_method :each_index, :each_with_index
+      alias_method :slice, :[]
+      alias_method :values_at, :select
+      alias_method :map, :collect
+
+
+      class << self
+        def define_array_wrapper_method(method_name)
+          define_method(method_name) do |*args, &block|
+            arr = self.to_a
+            result = arr.send(method_name, *args)
+            self.replace(arr)
+            return result if result
+            return block ? block.call : result
+          end
+        end
+        private :define_array_wrapper_method
+
+
+        def define_array_wrapper_with_result_method(method_name)
+          define_method(method_name) do |*args, &block|
+            # result can be an Enumerator, Array, or nil
+            # Enumerator can sometimes be returned if a block is an optional argument and it is not passed in
+            # nil usually specifies that no change was made
+            result = self.to_a.send(method_name, *args, &block)
+            if result
+              new_arr = result.to_a
+              self.replace(new_arr)
+              if result.is_a?(Enumerator)
+                # generate a fresh enum; rewinding the exiting one, in Ruby 2.2, will
+                # reset the enum with the same length, but all the #next calls will
+                # return nil
+                result = new_arr.to_enum
+                # generate a wrapper enum so any changes which occur by a chained
+                # enum can be captured
+                ie = ProxyingEnumerator.new(self, result)
+                result = ie.to_enum
+              end
+            end
+            result
+          end
+        end
+        private :define_array_wrapper_with_result_method
+      end
+
+
+      %w(delete delete_at shift slice! unshift).each do |method_name|
+        define_array_wrapper_method(method_name)
+      end
+
+
+      %w(collect! compact! delete_if fill flatten! insert reverse!
+        rotate! select! shuffle! sort! sort_by! uniq!).each do |method_name|
+        define_array_wrapper_with_result_method(method_name)
+      end
+      alias_method :keep_if, :select!
+      alias_method :map!, :collect!
+      alias_method :reject!, :delete_if
+
+
+      # propagates changes made by user of enumerator back to the original repeated field.
+      # This only applies in cases where the calling function which created the enumerator,
+      # such as #sort!, modifies itself rather than a new array, such as #sort
+      class ProxyingEnumerator < Struct.new(:repeated_field, :external_enumerator)
+        def each(*args, &block)
+          results = []
+          external_enumerator.each_with_index do |val, i|
+            result = yield(val)
+            results << result
+            #nil means no change occurred from yield; usually occurs when #to_a is called
+            if result
+              repeated_field[i] = result if result != val
+            end
+          end
+          results
+        end
+      end
+
+      private
+      include Google::Protobuf::Internal::Convert
+
+      attr :name, :arena, :array, :type, :descriptor
+
+      def internal_push(*elements)
+        elements.each do |element|
+          append_msg_val convert_ruby_to_upb(element, arena, type, descriptor)
+        end
+        self
+      end
+
+      def pop_one
+        raise FrozenError if frozen?
+        count = length
+        return nil if length.zero?
+        last_element = Google::Protobuf::FFI.get_msgval_at(array, count-1)
+        return_value = convert_upb_to_ruby(last_element, type, descriptor, arena)
+        resize(count-1)
+        return_value
+      end
+
+      def subarray(start, length)
+        return_result = []
+        (start..(start + length - 1)).each do |i|
+          element = Google::Protobuf::FFI.get_msgval_at(array, i)
+          return_result << convert_upb_to_ruby(element, type, descriptor, arena)
+        end
+        return_result
+      end
+
+      def each_msg_val_with_index &block
+        n = array.null? ? 0 : Google::Protobuf::FFI.array_size(array)
+        0.upto(n-1) do |i|
+          yield Google::Protobuf::FFI.get_msgval_at(array, i), i
+        end
+      end
+
+      def each_msg_val &block
+        each_msg_val_with_index do |msg_val, _|
+          yield msg_val
+        end
+      end
+
+      # @param msg_val [Google::Protobuf::FFI::MessageValue] Value to append
+      def append_msg_val(msg_val)
+        unless Google::Protobuf::FFI.append_array(array, msg_val, arena)
+          raise NoMemoryError.new "Could not allocate room for #{msg_val} in Arena"
+        end
+      end
+
+      # @param new_size [Integer] New size of the array
+      def resize(new_size)
+        unless Google::Protobuf::FFI.array_resize(array, new_size, arena)
+          raise NoMemoryError.new "Array resize to #{new_size} failed!"
+        end
+      end
+
+      def initialize(type, type_class: nil, initial_values: nil, name: nil, arena: nil, array: nil, descriptor: nil)
+        @name = name || 'RepeatedField'
+        raise ArgumentError.new "Expected argument type to be a Symbol" unless type.is_a? Symbol
+        field_number = Google::Protobuf::FFI::FieldType[type]
+        raise ArgumentError.new "Unsupported type '#{type}'" if field_number.nil?
+        if !descriptor.nil?
+          @descriptor = descriptor
+        elsif [:message, :enum].include? type
+          raise ArgumentError.new "Expected at least 2 arguments for message/enum." if type_class.nil?
+          descriptor = type_class.respond_to?(:descriptor) ? type_class.descriptor : nil
+          raise ArgumentError.new "Type class #{type_class} has no descriptor. Please pass a class or enum as returned by the DescriptorPool." if descriptor.nil?
+          @descriptor = descriptor
+        else
+          @descriptor = nil
+        end
+        @type = type
+
+        @arena = arena || Google::Protobuf::FFI.create_arena
+        @array = array || Google::Protobuf::FFI.create_array(@arena, @type)
+        unless initial_values.nil?
+          unless initial_values.is_a? Enumerable
+            raise ArgumentError.new "Expected array as initializer value for repeated field '#{name}' (given #{initial_values.class})."
+          end
+          internal_push(*initial_values)
+        end
+
+        # Should always be the last expression of the initializer to avoid
+        # leaking references to this object before construction is complete.
+        OBJECT_CACHE.try_add(@array.address, self)
+      end
+
+      # @param field [FieldDescriptor] Descriptor of the field where the RepeatedField will be assigned
+      # @param values [Enumerable] Initial values; may be nil or empty
+      # @param arena [Arena] Owning message's arena
+      def self.construct_for_field(field, arena, values: nil, array: nil)
+        instance = allocate
+        options = {initial_values: values, name: field.name, arena: arena, array: array}
+        if [:enum, :message].include? field.type
+          options[:descriptor] = field.subtype
+        end
+        instance.send(:initialize, field.type, **options)
+        instance
+      end
+
+      def fuse_arena(arena)
+        arena.fuse(arena)
+      end
+
+      extend Google::Protobuf::Internal::Convert
+
+      def self.deep_copy(repeated_field)
+        instance = allocate
+        instance.send(:initialize, repeated_field.send(:type), descriptor: repeated_field.send(:descriptor))
+        instance.send(:resize, repeated_field.length)
+        new_array = instance.send(:array)
+        repeated_field.send(:each_msg_val_with_index) do |element, i|
+          Google::Protobuf::FFI.array_set(new_array, i, message_value_deep_copy(element, repeated_field.send(:type), repeated_field.send(:descriptor), instance.send(:arena)))
+        end
+        instance
+      end
+
+    end
+  end
+end

ruby/lib/google/protobuf_ffi.rb

@@ -0,0 +1,73 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2023 Google Inc.  All rights reserved.
+# https://developers.google.com/protocol-buffers/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+require 'ffi-compiler/loader'
+require 'google/protobuf/ffi/ffi'
+require 'google/protobuf/ffi/internal/type_safety'
+require 'google/protobuf/ffi/internal/pointer_helper'
+require 'google/protobuf/ffi/internal/arena'
+require 'google/protobuf/ffi/internal/convert'
+require 'google/protobuf/ffi/descriptor'
+require 'google/protobuf/ffi/enum_descriptor'
+require 'google/protobuf/ffi/field_descriptor'
+require 'google/protobuf/ffi/oneof_descriptor'
+require 'google/protobuf/ffi/descriptor_pool'
+require 'google/protobuf/ffi/file_descriptor'
+require 'google/protobuf/ffi/map'
+require 'google/protobuf/ffi/object_cache'
+require 'google/protobuf/ffi/repeated_field'
+require 'google/protobuf/ffi/message'
+require 'google/protobuf/descriptor_dsl'
+
+module Google
+  module Protobuf
+    def self.deep_copy(object)
+      case object
+      when RepeatedField
+        RepeatedField.send(:deep_copy, object)
+      when Google::Protobuf::Map
+        Google::Protobuf::Map.deep_copy(object)
+      when Google::Protobuf::MessageExts
+        object.class.send(:deep_copy, object.instance_variable_get(:@msg))
+      else
+        raise NotImplementedError
+      end
+    end
+
+    def self.discard_unknown(message)
+      raise FrozenError if message.frozen?
+      raise ArgumentError.new "Expected message, got #{message.class} instead." if message.instance_variable_get(:@msg).nil?
+      unless Google::Protobuf::FFI.message_discard_unknown(message.instance_variable_get(:@msg), message.class.descriptor, 128)
+        raise RuntimeError.new "Messages nested too deeply."
+      end
+      nil
+    end
+  end
+end

ruby/lib/google/protobuf_native.rb

@@ -0,0 +1,43 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2023 Google Inc.  All rights reserved.
+# https://developers.google.com/protocol-buffers/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+if RUBY_PLATFORM == "java"
+  require 'json'
+  require 'google/protobuf_java'
+else
+  begin
+    require "google/#{RUBY_VERSION.sub(/\.\d+$/, '')}/protobuf_c"
+  rescue LoadError
+    require 'google/protobuf_c'
+  end
+end
+
+require 'google/protobuf/descriptor_dsl'
+require 'google/protobuf/repeated_field'

ruby/lib/google/tasks/ffi.rake

@@ -0,0 +1,94 @@
+require "ffi-compiler/compile_task"
+
+# # @param task [FFI::Compiler::CompileTask] task to configure
+def configure_common_compile_task(task)
+  if FileUtils.pwd.include? 'ext'
+    src_dir = '.'
+    third_party_path = 'third_party/utf8_range'
+  else
+    src_dir = 'ext/google/protobuf_c'
+    third_party_path = 'ext/google/protobuf_c/third_party/utf8_range'
+  end
+
+  task.add_include_path third_party_path
+  task.add_define 'NDEBUG'
+  task.cflags << "-std=gnu99 -O3"
+  [
+    :convert, :defs, :map, :message, :protobuf, :repeated_field, :wrap_memcpy
+  ].each { |file| task.exclude << "/#{file}.c" }
+  task.ext_dir = src_dir
+  task.source_dirs = [src_dir]
+  if RbConfig::CONFIG['target_os'] =~ /darwin|linux/
+    task.cflags << "-Wall -Wsign-compare -Wno-declaration-after-statement"
+  end
+end
+
+# FFI::CompilerTask's constructor walks the filesystem at task definition time
+# to create subtasks for each source file, so files from third_party must be
+# copied into place before the task is defined for it to work correctly.
+# TODO(jatl) Is there a sane way to check for generated protos under lib too?
+def with_generated_files
+  expected_path = FileUtils.pwd.include?('ext') ? 'third_party/utf8_range' : 'ext/google/protobuf_c/third_party/utf8_range'
+  if File.directory?(expected_path)
+    yield
+  else
+    task :default do
+      # It is possible, especially in cases like the first invocation of
+      # `rake test` following `rake clean` or a fresh checkout that the
+      # `copy_third_party` task has been executed since initial task definition.
+      # If so, run the task definition block now and invoke it explicitly.
+      if File.directory?(expected_path)
+        yield
+        Rake::Task[:default].invoke
+      else
+        raise "Missing directory #{File.absolute_path(expected_path)}." +
+                " Did you forget to run `rake copy_third_party` before building" +
+                " native extensions?"
+      end
+    end
+  end
+end
+
+desc "Compile Protobuf library for FFI"
+namespace "ffi-protobuf" do
+  with_generated_files do
+    # Compile Ruby UPB separately in order to limit use of -DUPB_BUILD_API to one
+    # compilation unit.
+    desc "Compile UPB library for FFI"
+    namespace "ffi-upb" do
+      with_generated_files do
+        FFI::Compiler::CompileTask.new('ruby-upb') do |c|
+          configure_common_compile_task c
+          c.add_define "UPB_BUILD_API"
+          c.exclude << "/glue.c"
+          c.exclude << "/shared_message.c"
+          c.exclude << "/shared_convert.c"
+          if RbConfig::CONFIG['target_os'] =~ /darwin|linux/
+            c.cflags << "-fvisibility=hidden"
+          end
+        end
+      end
+    end
+
+    FFI::Compiler::CompileTask.new 'protobuf_c_ffi' do |c|
+      configure_common_compile_task c
+      # Ruby UPB was already compiled with different flags.
+      c.exclude << "/range2-neon.c"
+      c.exclude << "/range2-sse.c"
+      c.exclude << "/naive.c"
+      c.exclude << "/ruby-upb.c"
+    end
+
+    # Setup dependencies so that the .o files generated by building ffi-upb are
+    # available to link here.
+    # TODO(jatl) Can this be simplified? Can the single shared library be used
+    # instead of the object files?
+    protobuf_c_task = Rake::Task[:default]
+    protobuf_c_shared_lib_task = Rake::Task[protobuf_c_task.prereqs.last]
+    ruby_upb_shared_lib_task = Rake::Task[:"ffi-upb:default"].prereqs.first
+    Rake::Task[ruby_upb_shared_lib_task].prereqs.each do |dependency|
+      protobuf_c_shared_lib_task.prereqs.prepend dependency
+    end
+  end
+end
+

ruby/tests/BUILD.bazel

@@ -14,6 +14,15 @@ filegroup(
     ],
 )
 
+ruby_test(
+    name = "implementation",
+    srcs = ["implementation.rb"],
+    deps = [
+        "//ruby:protobuf",
+        "@protobuf_bundle//:test-unit",
+    ],
+)
+
 ruby_test(
     name = "basic",
     srcs = ["basic.rb"],

ruby/tests/implementation.rb

@@ -0,0 +1,37 @@
+require 'google/protobuf'
+require 'test/unit'
+
+class BackendTest < Test::Unit::TestCase
+  # Verifies the implementation of Protobuf is the preferred one.
+  # See protobuf.rb for the logic that defines PREFER_FFI.
+  def test_prefer_ffi_aligns_with_implementation
+    expected = Google::Protobuf::PREFER_FFI ? :FFI : :NATIVE
+    assert_equal expected, Google::Protobuf::IMPLEMENTATION
+  end
+
+  def test_prefer_ffi
+    unless ENV['PROTOCOL_BUFFERS_RUBY_IMPLEMENTATION'] =~ /ffi/i
+      omit"FFI implementation requires environment variable PROTOCOL_BUFFERS_RUBY_IMPLEMENTATION=FFI to activate."
+    end
+    assert_equal true, Google::Protobuf::PREFER_FFI
+  end
+  def test_ffi_implementation
+    unless ENV['PROTOCOL_BUFFERS_RUBY_IMPLEMENTATION'] =~ /ffi/i
+      omit "FFI implementation requires environment variable PROTOCOL_BUFFERS_RUBY_IMPLEMENTATION=FFI to activate."
+    end
+    assert_equal :FFI, Google::Protobuf::IMPLEMENTATION
+  end
+
+  def test_prefer_native
+    if ENV.include?('PROTOCOL_BUFFERS_RUBY_IMPLEMENTATION') and ENV['PROTOCOL_BUFFERS_RUBY_IMPLEMENTATION'] !~ /native/i
+      omit"Native implementation requires omitting environment variable PROTOCOL_BUFFERS_RUBY_IMPLEMENTATION or setting it to `NATIVE` to activate."
+    end
+    assert_equal false, Google::Protobuf::PREFER_FFI
+  end
+  def test_native_implementation
+    if ENV.include?('PROTOCOL_BUFFERS_RUBY_IMPLEMENTATION') and ENV['PROTOCOL_BUFFERS_RUBY_IMPLEMENTATION'] !~ /native/i
+      omit"Native implementation requires omitting environment variable PROTOCOL_BUFFERS_RUBY_IMPLEMENTATION or setting it to `NATIVE` to activate."
+    end
+    assert_equal :NATIVE, Google::Protobuf::IMPLEMENTATION
+  end
+end

ruby/tests/object_cache_test.rb

@@ -4,7 +4,7 @@ require 'test/unit'
 class PlatformTest < Test::Unit::TestCase
   def test_correct_implementation_for_platform
     omit('OBJECT_CACHE not defined') unless defined? Google::Protobuf::OBJECT_CACHE
-    if Gem::Version.new(RUBY_VERSION) >= Gem::Version.new('2.7.0') and Google::Protobuf::SIZEOF_LONG >= Google::Protobuf::SIZEOF_VALUE
+    if Google::Protobuf::SIZEOF_LONG >= Google::Protobuf::SIZEOF_VALUE and not defined? JRUBY_VERSION
       assert_instance_of Google::Protobuf::ObjectCache, Google::Protobuf::OBJECT_CACHE
     else
       assert_instance_of Google::Protobuf::LegacyObjectCache, Google::Protobuf::OBJECT_CACHE