fix(saf): standby assembles chunked resync, applies atomically with re-check, acks; N5 race documented (plan R2-02 T6)

2026-07-13 10:00:47 -04:00
parent 3f937b399b
commit 84bc2380f3
2 changed files with 160 additions and 2 deletions
@@ -335,6 +335,57 @@ akka {
        Assert.Equal(3, rest.Sum(c => c.Messages.Count));
    }

+    // ── R2 T6: standby chunk assembly + atomic apply + ack ──
+
+    [Fact]
+    public async Task StandbyNode_AssemblesChunks_AppliesOnce_AndAcks()
+    {
+        await _sfStorage.EnqueueAsync(NewMessage("stale"));
+        var actor = CreateResyncActor(isActive: () => false);
+        var resyncId = "r1";
+
+        actor.Tell(new SfBufferSnapshotChunk(resyncId, 1, 2,
+            new List<StoreAndForwardMessage> { NewMessage("f1") }, false), TestActor);
+        actor.Tell(new SfBufferSnapshotChunk(resyncId, 2, 2,
+            new List<StoreAndForwardMessage> { NewMessage("f2") }, false), TestActor);
+
+        var ack = ExpectMsg<SfBufferResyncAck>(TimeSpan.FromSeconds(5));
+        Assert.Equal(resyncId, ack.ResyncId);
+        Assert.Equal(2, ack.RowCount);
+        await AwaitAssertAsync(async () =>
+        {
+            Assert.Null(await _sfStorage.GetMessageByIdAsync("stale"));   // replaced wholesale
+            Assert.NotNull(await _sfStorage.GetMessageByIdAsync("f1"));
+            Assert.NotNull(await _sfStorage.GetMessageByIdAsync("f2"));
+        });
+    }
+
+    [Fact]
+    public async Task StandbyNode_NewResyncId_DiscardsStalePartialAssembly()
+    {
+        var actor = CreateResyncActor(isActive: () => false);
+        actor.Tell(new SfBufferSnapshotChunk("old", 1, 2,
+            new List<StoreAndForwardMessage> { NewMessage("orphan") }, false), TestActor);
+        actor.Tell(new SfBufferSnapshotChunk("new", 1, 1,
+            new List<StoreAndForwardMessage> { NewMessage("fresh") }, false), TestActor);
+
+        ExpectMsg<SfBufferResyncAck>(TimeSpan.FromSeconds(5)); // "new" completed
+        await AwaitAssertAsync(async () =>
+        {
+            Assert.NotNull(await _sfStorage.GetMessageByIdAsync("fresh"));
+            Assert.Null(await _sfStorage.GetMessageByIdAsync("orphan")); // stale partial never applied
+        });
+    }
+
+    [Fact]
+    public void ActiveNode_IgnoresChunks_NeverAcks()
+    {
+        var actor = CreateResyncActor(isActive: () => true);
+        actor.Tell(new SfBufferSnapshotChunk("r", 1, 1,
+            new List<StoreAndForwardMessage> { NewMessage("x") }, false), TestActor);
+        ExpectNoMsg(TimeSpan.FromMilliseconds(300));
+    }
+
    private static StoreAndForwardMessage NewSfMessage(string id) => new()
    {
        Id = id,