Wire ITranscodeSessionStore to Redis-backed impl with NullTranscodeSessionStore fallback and DI registration (#21)

* Initial plan * feat: add Redis-backed ITranscodeSessionStore with NullTranscodeSessionStore fallback and DI registration Co-authored-by: ZoltyMat <177592743+ZoltyMat@users.noreply.github.com> * refactor: add code review improvements - lease expiry comment, Redis connection error handling Co-authored-by: ZoltyMat <177592743+ZoltyMat@users.noreply.github.com> --------- Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com> Co-authored-by: ZoltyMat <177592743+ZoltyMat@users.noreply.github.com>
2026-03-09 23:04:04 -04:00
parent a187ab18b8
commit d60ae43b59
8 changed files with 452 additions and 0 deletions
@@ -0,0 +1,225 @@
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+using MediaBrowser.Controller.MediaEncoding;
+using Xunit;
+
+namespace Jellyfin.Server.Implementations.Tests.MediaEncoding;
+
+/// <summary>
+/// Tests for transcode session store contract behavior, using <see cref="InMemoryTranscodeSessionStore"/>
+/// as a reference implementation (no real Redis required).
+/// </summary>
+public class RedisTranscodeSessionStoreTests
+{
+    /// <summary>
+    /// Verifies that <see cref="ITranscodeSessionStore.TryGetAsync"/> returns <c>null</c> after
+    /// a session's lease has expired.
+    /// </summary>
+    [Fact]
+    [Trait("Category", "UnitTest")]
+    public async Task TryGetAsync_AfterLeaseExpires_ReturnsNull()
+    {
+        var store = new InMemoryTranscodeSessionStore();
+        var session = new TranscodeSession
+        {
+            PlaySessionId = "session-1",
+            OwnerPod = "pod-a",
+            LeaseExpiresUtc = DateTime.UtcNow.AddSeconds(-1),
+        };
+
+        await store.SetAsync(session);
+
+        var result = await store.TryGetAsync("session-1");
+
+        Assert.Null(result);
+    }
+
+    /// <summary>
+    /// Verifies that <see cref="ITranscodeSessionStore.TryTakeoverAsync"/> returns <c>false</c>
+    /// when the session's lease is still valid.
+    /// </summary>
+    [Fact]
+    [Trait("Category", "UnitTest")]
+    public async Task TryTakeoverAsync_WhileLeaseValid_ReturnsFalse()
+    {
+        var store = new InMemoryTranscodeSessionStore();
+        var session = new TranscodeSession
+        {
+            PlaySessionId = "session-2",
+            OwnerPod = "pod-a",
+            LeaseExpiresUtc = DateTime.UtcNow.AddSeconds(30),
+        };
+
+        await store.SetAsync(session);
+
+        var result = await store.TryTakeoverAsync("session-2", "pod-b");
+
+        Assert.False(result);
+    }
+
+    /// <summary>
+    /// Verifies that <see cref="ITranscodeSessionStore.TryTakeoverAsync"/> returns <c>true</c>
+    /// and updates the owner when the session's lease has expired.
+    /// </summary>
+    [Fact]
+    [Trait("Category", "UnitTest")]
+    public async Task TryTakeoverAsync_AfterLeaseExpires_ReturnsTrue_AndUpdatesOwner()
+    {
+        var store = new InMemoryTranscodeSessionStore();
+        var session = new TranscodeSession
+        {
+            PlaySessionId = "session-3",
+            OwnerPod = "pod-a",
+            LeaseExpiresUtc = DateTime.UtcNow.AddSeconds(-1),
+        };
+
+        await store.SetAsync(session);
+
+        var result = await store.TryTakeoverAsync("session-3", "pod-b");
+
+        Assert.True(result);
+
+        var updated = await store.TryGetAsync("session-3");
+        Assert.NotNull(updated);
+        Assert.Equal("pod-b", updated.OwnerPod);
+        Assert.True(updated.LeaseExpiresUtc > DateTime.UtcNow);
+    }
+
+    /// <summary>
+    /// Verifies that when multiple pods concurrently attempt to take over an expired session,
+    /// exactly one succeeds.
+    /// </summary>
+    [Fact]
+    [Trait("Category", "UnitTest")]
+    public async Task ConcurrentTryTakeover_OnlyOneWins()
+    {
+        var store = new InMemoryTranscodeSessionStore();
+        var session = new TranscodeSession
+        {
+            PlaySessionId = "session-4",
+            OwnerPod = "pod-a",
+            LeaseExpiresUtc = DateTime.UtcNow.AddSeconds(-1),
+        };
+
+        await store.SetAsync(session);
+
+        const int concurrency = 10;
+        var tasks = new Task<bool>[concurrency];
+        for (int i = 0; i < concurrency; i++)
+        {
+            var podName = $"pod-{i}";
+            tasks[i] = store.TryTakeoverAsync("session-4", podName);
+        }
+
+        var results = await Task.WhenAll(tasks);
+
+        var successCount = 0;
+        foreach (var r in results)
+        {
+            if (r)
+            {
+                successCount++;
+            }
+        }
+
+        Assert.Equal(1, successCount);
+    }
+
+    /// <summary>
+    /// Thread-safe, in-memory implementation of <see cref="ITranscodeSessionStore"/> used within
+    /// this test class to avoid a cross-project reference to Jellyfin.MediaEncoding.Tests.
+    /// </summary>
+    private sealed class InMemoryTranscodeSessionStore : ITranscodeSessionStore
+    {
+        private static readonly TimeSpan DefaultLeaseDuration = TimeSpan.FromSeconds(30);
+
+        private readonly Dictionary<string, TranscodeSession> _sessions = new(StringComparer.OrdinalIgnoreCase);
+        private readonly Lock _lock = new();
+
+        /// <inheritdoc />
+        public Task<TranscodeSession?> TryGetAsync(string playSessionId, CancellationToken cancellationToken = default)
+        {
+            lock (_lock)
+            {
+                if (_sessions.TryGetValue(playSessionId, out var session) && session.LeaseExpiresUtc > DateTime.UtcNow)
+                {
+                    return Task.FromResult<TranscodeSession?>(Clone(session));
+                }
+
+                return Task.FromResult<TranscodeSession?>(null);
+            }
+        }
+
+        /// <inheritdoc />
+        public Task<bool> TryTakeoverAsync(string playSessionId, string claimingPod, CancellationToken cancellationToken = default)
+        {
+            lock (_lock)
+            {
+                if (!_sessions.TryGetValue(playSessionId, out var session))
+                {
+                    return Task.FromResult(false);
+                }
+
+                if (session.LeaseExpiresUtc > DateTime.UtcNow)
+                {
+                    return Task.FromResult(false);
+                }
+
+                session.OwnerPod = claimingPod;
+                session.LeaseExpiresUtc = DateTime.UtcNow.Add(DefaultLeaseDuration);
+                return Task.FromResult(true);
+            }
+        }
+
+        /// <inheritdoc />
+        public Task SetAsync(TranscodeSession session, CancellationToken cancellationToken = default)
+        {
+            lock (_lock)
+            {
+                _sessions[session.PlaySessionId] = session;
+            }
+
+            return Task.CompletedTask;
+        }
+
+        /// <inheritdoc />
+        public Task RenewLeaseAsync(string playSessionId, CancellationToken cancellationToken = default)
+        {
+            lock (_lock)
+            {
+                if (_sessions.TryGetValue(playSessionId, out var session))
+                {
+                    session.LeaseExpiresUtc = DateTime.UtcNow.Add(DefaultLeaseDuration);
+                }
+            }
+
+            return Task.CompletedTask;
+        }
+
+        /// <inheritdoc />
+        public Task DeleteAsync(string playSessionId, CancellationToken cancellationToken = default)
+        {
+            lock (_lock)
+            {
+                _sessions.Remove(playSessionId);
+            }
+
+            return Task.CompletedTask;
+        }
+
+        private static TranscodeSession Clone(TranscodeSession source)
+            => new TranscodeSession
+            {
+                PlaySessionId = source.PlaySessionId,
+                OwnerPod = source.OwnerPod,
+                LeaseExpiresUtc = source.LeaseExpiresUtc,
+                ManifestPath = source.ManifestPath,
+                SegmentPathPrefix = source.SegmentPathPrefix,
+                MediaSourceId = source.MediaSourceId,
+                LastCompletedSegmentIndex = source.LastCompletedSegmentIndex,
+                LastDurablePlaybackOffset = source.LastDurablePlaybackOffset,
+            };
+    }
+}