Fix the Unsubscribe timeout problem (#313)

- The  Unsubscribe function sync (like the other commands ). The consumers' list is updated in the right way.
  The connection is correctly closed since there are no pending consumers.

- Fix the handle delivery if the consumer is removed, but there are still chunks on the wire.
  Add debug logs for this situation. 

- Add Degug Asserts to validate the buffer size, which can help understand some parse chunk errors.
  That can be temporary at some point; we can remove them.

- Add the cancellation token to the connection class
  it helps when the reader is blocked and the consumer is closed.

- Given this [use case](#310) so short-life 
   consumers, the initial credits should be low to avoid keeping the read handler busy.

- Minor change is replace Memory<T> to ReadOnlyMemory<T>  it is a bit faster and safe 

- Uniform the log debug and error messages  with consumer info it adds all the consumer info that can be helpful in case of debugging and errors

- Fixes #310


---------

Signed-off-by: Gabriele Santomaggio <[email protected]>

Author: Gsantomaggio

RabbitMQ.Stream.Client/Client.cs

@@ -362,13 +362,19 @@ public async Task<UnsubscribeResponse> Unsubscribe(byte subscriptionId)
         {
             try
             {
+                // here we reduce a bit the timeout to avoid waiting too much
+                // if the client is busy with read operations it can take time to process the unsubscribe
+                // but the subscribe is removed.
                 var result =
                     await Request<UnsubscribeRequest, UnsubscribeResponse>(corr =>
-                        new UnsubscribeRequest(corr, subscriptionId)).ConfigureAwait(false);
+                        new UnsubscribeRequest(corr, subscriptionId), TimeSpan.FromSeconds(5)).ConfigureAwait(false);
+                _logger.LogDebug("Unsubscribe request : {SubscriptionId}", subscriptionId);
+
                 return result;
             }
             finally
             {
+                _logger.LogDebug("Unsubscribe: {SubscriptionId}", subscriptionId);
                 // remove consumer after RPC returns, this should avoid uncorrelated data being sent
                 consumers.Remove(subscriptionId);
             }
@@ -436,7 +442,6 @@ private async Task HandleIncoming(Memory<byte> frameMemory)
             // so there is no need to send the heartbeat when not necessary 
             _heartBeatHandler.UpdateHeartBeat();
 
-            ConsumerEvents consumerEvents;
             switch (tag)
             {
                 case PublishConfirm.Key:
@@ -446,14 +451,29 @@ private async Task HandleIncoming(Memory<byte> frameMemory)
                     confirmCallback(confirm.PublishingIds);
                     if (MemoryMarshal.TryGetArray(confirm.PublishingIds, out var confirmSegment))
                     {
-                        ArrayPool<ulong>.Shared.Return(confirmSegment.Array);
+                        if (confirmSegment.Array != null)
+                            ArrayPool<ulong>.Shared.Return(confirmSegment.Array);
                     }
 
                     break;
                 case Deliver.Key:
                     Deliver.Read(frame, out var deliver);
-                    consumerEvents = consumers[deliver.SubscriptionId];
-                    await consumerEvents.DeliverHandler(deliver).ConfigureAwait(false);
+                    if (consumers.TryGetValue(deliver.SubscriptionId, out var consumerEvent))
+                    {
+                        await consumerEvent.DeliverHandler(deliver).ConfigureAwait(false);
+                    }
+                    else
+                    {
+                        // the consumer is not found, this can happen when the consumer is closing
+                        // and there are still chunks on the wire to the handler is still processing the chunks
+                        // we can ignore the chunk since the subscription does not exists anymore
+                        _logger?.LogDebug(
+                            "Could not find stream subscription {ID} or subscription closing." +
+                            "A possible cause it that the subscription was closed and the are still chunks on the wire. " +
+                            "Reduce the initial credits can help to avoid this situation",
+                            deliver.SubscriptionId);
+                    }
+
                     break;
                 case PublishError.Key:
                     PublishError.Read(frame, out var error);
@@ -588,7 +608,8 @@ private void HandleCorrelatedCommand(ushort tag, ref ReadOnlySequence<byte> fram
                 default:
                     if (MemoryMarshal.TryGetArray(frame.First, out var segment))
                     {
-                        ArrayPool<byte>.Shared.Return(segment.Array);
+                        if (segment.Array != null)
+                            ArrayPool<byte>.Shared.Return(segment.Array);
                     }
 
                     throw new ArgumentException($"Unknown or unexpected tag: {tag}", nameof(tag));
@@ -637,19 +658,23 @@ public async Task<CloseResponse> Close(string reason)
                     await Request<CloseRequest, CloseResponse>(corr => new CloseRequest(corr, reason),
                         TimeSpan.FromSeconds(10)).ConfigureAwait(false);
 
-                InternalClose();
-                connection.Dispose();
                 return result;
             }
-
-            catch (System.TimeoutException)
+            catch (TimeoutException)
             {
-                _logger.LogError("Timeout while closing the connection. The connection will be closed anyway");
+                _logger.LogError(
+                    "Timeout while closing the connection. The connection will be closed anyway");
             }
             catch (Exception e)
             {
                 _logger.LogError(e, "An error occurred while calling {CalledFunction}", nameof(connection.Dispose));
             }
+            finally
+            {
+                // even if the close fails we need to close the connection
+                InternalClose();
+                connection.Dispose();
+            }
 
             return new CloseResponse(0, ResponseCode.Ok);
         }

RabbitMQ.Stream.Client/Connection.cs

@@ -28,6 +28,10 @@ public class Connection : IDisposable
         private bool _disposedValue;
         private readonly ILogger _logger;
 
+        // this is used to cancel the socket and the reader/write operations tasks
+        private readonly CancellationTokenSource _cancelTokenSource = new();
+        private CancellationToken Token => _cancelTokenSource.Token;
+
         internal int NumFrames => numFrames;
 
         public bool IsClosed => isClosed;
@@ -98,21 +102,27 @@ public async ValueTask<bool> Write<T>(T command) where T : struct, ICommand
 
         private async Task WriteCommand<T>(T command) where T : struct, ICommand
         {
+            if (Token.IsCancellationRequested)
+            {
+                throw new OperationCanceledException("Token Cancellation Requested Connection");
+            }
+
             if (isClosed)
             {
                 throw new InvalidOperationException("Connection is closed");
             }
+
             // Only one thread should be able to write to the output pipeline at a time.
-            await _writeLock.WaitAsync().ConfigureAwait(false);
+            await _writeLock.WaitAsync(Token).ConfigureAwait(false);
             try
             {
                 var size = command.SizeNeeded;
                 var mem = new byte[4 + size]; // + 4 to write the size
                 WireFormatting.WriteUInt32(mem, (uint)size);
                 var written = command.Write(mem.AsSpan()[4..]);
-                await writer.WriteAsync(new ReadOnlyMemory<byte>(mem)).ConfigureAwait(false);
+                await writer.WriteAsync(new ReadOnlyMemory<byte>(mem), Token).ConfigureAwait(false);
                 Debug.Assert(size == written);
-                await writer.FlushAsync().ConfigureAwait(false);
+                await writer.FlushAsync(Token).ConfigureAwait(false);
             }
             finally
             {
@@ -129,7 +139,7 @@ private async Task ProcessIncomingFrames()
                 {
                     if (!reader.TryRead(out var result))
                     {
-                        result = await reader.ReadAsync().ConfigureAwait(false);
+                        result = await reader.ReadAsync(Token).ConfigureAwait(false);
                     }
 
                     var buffer = result.Buffer;
@@ -219,13 +229,19 @@ public void Dispose()
             {
                 try
                 {
+                    if (!_cancelTokenSource.IsCancellationRequested)
+                    {
+                        _cancelTokenSource.Cancel();
+                    }
+
                     isClosed = true;
                     writer.Complete();
                     reader.Complete();
-                    socket.Dispose();
+                    socket.Close();
                     if (!_incomingFramesTask.Wait(Consts.MidWait))
                     {
-                        _logger?.LogWarning("ProcessIncomingFrames reader task did not exit in {MidWait}", Consts.MidWait);
+                        _logger?.LogWarning("ProcessIncomingFrames reader task did not exit in {MidWait}",
+                            Consts.MidWait);
                     }
                 }
                 finally

RabbitMQ.Stream.Client/Deliver.cs

@@ -51,7 +51,7 @@ internal readonly struct SubEntryChunk
         private SubEntryChunk(byte compress,
             ushort numRecordsInBatch,
             uint unCompressedDataSize, uint dataLen,
-            Memory<byte> data)
+            ReadOnlyMemory<byte> data)
         {
             compressValue = compress;
             NumRecordsInBatch = numRecordsInBatch;
@@ -67,7 +67,7 @@ private SubEntryChunk(byte compress,
         public uint UnCompressedDataSize { get; }
 
         public uint DataLen { get; }
-        public Memory<byte> Data { get; }
+        public ReadOnlyMemory<byte> Data { get; }
 
         // This wrapper was added to be used in async methods
         // where the SequenceReader is not available
@@ -122,7 +122,7 @@ private Chunk(byte magicVersion,
             ulong epoch,
             ulong chunkId,
             uint crc,
-            Memory<byte> data)
+            ReadOnlyMemory<byte> data)
         {
             MagicVersion = magicVersion;
             NumEntries = numEntries;
@@ -142,7 +142,7 @@ private Chunk(byte magicVersion,
         public ulong Epoch { get; }
         public ulong ChunkId { get; }
         public uint Crc { get; }
-        public Memory<byte> Data { get; }
+        public ReadOnlyMemory<byte> Data { get; }
 
         internal static int Read(ReadOnlySequence<byte> frame, out Chunk chunk)
         {
@@ -175,6 +175,11 @@ internal static int Read(ReadOnlySequence<byte> frame, out Chunk chunk)
                     $"Chunk: Not enough data, sourceLength: {reader.Length}, memoryLen: {memory.Length}, dataLen: {dataLen}");
             }
 
+            if (memory.Length != dataLen)
+            {
+                throw new Exception($"Chunk: Not enough data, memoryLen: {memory.Length}, dataLen: {dataLen}");
+            }
+
             chunk = new Chunk(magicVersion, numEntries, numRecords, timestamp, epoch, chunkId, crc, memory);
             return offset;
         }

RabbitMQ.Stream.Client/PublicAPI.Unshipped.txt

@@ -8,7 +8,7 @@ RabbitMQ.Stream.Client.AuthMechanism.Plain = 0 -> RabbitMQ.Stream.Client.AuthMec
 RabbitMQ.Stream.Client.AuthMechanismNotSupportedException
 RabbitMQ.Stream.Client.AuthMechanismNotSupportedException.AuthMechanismNotSupportedException(string s) -> void
 RabbitMQ.Stream.Client.Chunk.Crc.get -> uint
-RabbitMQ.Stream.Client.Chunk.Data.get -> System.Memory<byte>
+RabbitMQ.Stream.Client.Chunk.Data.get -> System.ReadOnlyMemory<byte>
 RabbitMQ.Stream.Client.Chunk.MagicVersion.get -> byte
 RabbitMQ.Stream.Client.Client.ExchangeVersions() -> System.Threading.Tasks.Task<RabbitMQ.Stream.Client.CommandVersionsResponse>
 RabbitMQ.Stream.Client.Client.QueryRoute(string superStream, string routingKey) -> System.Threading.Tasks.Task<RabbitMQ.Stream.Client.RouteQueryResponse>