51 lines
2.2 KiB
C#
51 lines
2.2 KiB
C#
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using ZiggyCreatures.Caching.Fusion;
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namespace LANCommander.Server.Services;
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/// <summary>
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/// Tracks the last time each active play session was heard from via the RPC keepalive. Backed by
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/// <see cref="IFusionCache"/> so it works across instances when a distributed (e.g. Redis) backend
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/// is configured. The sweep consults this to end sessions that have gone stale, ending them at the
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/// last known-alive time so recorded playtime isn't inflated.
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/// </summary>
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public sealed class PlaySessionKeepAliveTracker(
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IFusionCache cache,
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SettingsProvider<Settings.Settings> settingsProvider)
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{
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private static string GetCacheKey(Guid gameId, Guid userId) => $"PlaySessions/KeepAlive/{gameId}/{userId}";
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// Keep entries alive well past the staleness timeout so the sweep can still read the last
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// keepalive time when ending a stale session, rather than losing it to expiration.
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private TimeSpan EntryDuration =>
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TimeSpan.FromSeconds(Math.Max(1, settingsProvider.CurrentValue.Server.GameServers.KeepAliveTimeout) * 3);
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/// <summary>Records that the session for this game/user was heard from just now.</summary>
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public async Task TouchAsync(Guid gameId, Guid userId) =>
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await cache.SetAsync(GetCacheKey(gameId, userId), DateTime.UtcNow, EntryDuration);
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/// <summary>
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/// Returns the last-seen time for the session, seeding it with the current time if we have no
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/// record yet (e.g. a session that predates a restart with no distributed backend). Seeding
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/// grants a fresh grace window rather than immediately reaping a session we haven't observed yet.
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/// </summary>
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public async Task<DateTime> GetOrSeedAsync(Guid gameId, Guid userId)
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{
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var cacheKey = GetCacheKey(gameId, userId);
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var lastSeen = await cache.TryGetAsync<DateTime>(cacheKey);
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if (lastSeen.HasValue)
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return lastSeen.Value;
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var now = DateTime.UtcNow;
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await cache.SetAsync(cacheKey, now, EntryDuration);
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return now;
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}
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/// <summary>Stops tracking the session (it ended normally or was swept).</summary>
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public async Task RemoveAsync(Guid gameId, Guid userId) =>
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await cache.RemoveAsync(GetCacheKey(gameId, userId));
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}
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