Fix unconditional semaphore release in BasicPublishAsync when Cancell…

projects/RabbitMQ.Client/Impl/Channel.BasicPublish.cs

@@ -34,6 +34,7 @@
 using System.Diagnostics;
 using System.Runtime.CompilerServices;
 using System.Threading;
+using System.Threading.RateLimiting;
 using System.Threading.Tasks;
 using RabbitMQ.Client.Framing;
 
@@ -49,11 +50,12 @@ public async ValueTask BasicPublishAsync<TProperties>(string exchange, string ro
             where TProperties : IReadOnlyBasicProperties, IAmqpHeader
         {
             PublisherConfirmationInfo? publisherConfirmationInfo = null;
+            RateLimitLease? lease =
+                await MaybeAcquirePublisherConfirmationLockAsync(cancellationToken)
+                    .ConfigureAwait(false);
             try
             {
-                publisherConfirmationInfo =
-                    await MaybeStartPublisherConfirmationTrackingAsync(cancellationToken)
-                        .ConfigureAwait(false);
+                publisherConfirmationInfo = MaybeStartPublisherConfirmationTracking();
 
                 await MaybeEnforceFlowControlAsync(cancellationToken)
                     .ConfigureAwait(false);
@@ -93,6 +95,7 @@ await ModelSendAsync(in cmd, in props, body, cancellationToken)
             }
             finally
             {
+                MaybeReleasePublisherConfirmationLock(lease);
                 await MaybeEndPublisherConfirmationTrackingAsync(publisherConfirmationInfo, cancellationToken)
                     .ConfigureAwait(false);
             }
@@ -104,11 +107,12 @@ public async ValueTask BasicPublishAsync<TProperties>(CachedString exchange, Cac
             where TProperties : IReadOnlyBasicProperties, IAmqpHeader
         {
             PublisherConfirmationInfo? publisherConfirmationInfo = null;
+            RateLimitLease? lease =
+                await MaybeAcquirePublisherConfirmationLockAsync(cancellationToken)
+                    .ConfigureAwait(false);
             try
             {
-                publisherConfirmationInfo =
-                    await MaybeStartPublisherConfirmationTrackingAsync(cancellationToken)
-                        .ConfigureAwait(false);
+                publisherConfirmationInfo = MaybeStartPublisherConfirmationTracking();
 
                 await MaybeEnforceFlowControlAsync(cancellationToken)
                     .ConfigureAwait(false);
@@ -148,6 +152,7 @@ await ModelSendAsync(in cmd, in props, body, cancellationToken)
             }
             finally
             {
+                MaybeReleasePublisherConfirmationLock(lease);
                 await MaybeEndPublisherConfirmationTrackingAsync(publisherConfirmationInfo, cancellationToken)
                     .ConfigureAwait(false);
             }

projects/RabbitMQ.Client/Impl/Channel.PublisherConfirms.cs

@@ -52,18 +52,15 @@ internal partial class Channel : IChannel, IRecoverable
         private readonly ConcurrentDictionary<ulong, TaskCompletionSource<bool>> _confirmsTaskCompletionSources = new();
         private RateLimiter? _outstandingPublisherConfirmationsRateLimiter;
 
-        private sealed class PublisherConfirmationInfo : IDisposable
+        private sealed class PublisherConfirmationInfo
         {
             private TaskCompletionSource<bool>? _publisherConfirmationTcs;
-            private readonly RateLimitLease? _lease;
 
             internal PublisherConfirmationInfo(ulong publishSequenceNumber,
-                TaskCompletionSource<bool>? publisherConfirmationTcs,
-                RateLimitLease? lease)
+                TaskCompletionSource<bool>? publisherConfirmationTcs)
             {
                 PublishSequenceNumber = publishSequenceNumber;
                 _publisherConfirmationTcs = publisherConfirmationTcs;
-                _lease = lease;
             }
 
             internal ulong PublishSequenceNumber { get; }
@@ -89,11 +86,6 @@ internal bool MaybeHandleException(Exception ex)
 
                 return exceptionWasHandled;
             }
-
-            public void Dispose()
-            {
-                _lease?.Dispose();
-            }
         }
 
         public async ValueTask<ulong> GetNextPublishSequenceNumberAsync(CancellationToken cancellationToken = default)
@@ -289,29 +281,53 @@ await _confirmSemaphore.WaitAsync(reason.CancellationToken)
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private async Task<PublisherConfirmationInfo?> MaybeStartPublisherConfirmationTrackingAsync(CancellationToken cancellationToken)
+        private async Task<RateLimitLease?> MaybeAcquirePublisherConfirmationLockAsync(CancellationToken cancellationToken)
         {
             if (_publisherConfirmationsEnabled)
             {
                 RateLimitLease? lease = null;
-                if (_publisherConfirmationTrackingEnabled)
+                if (_publisherConfirmationTrackingEnabled && _outstandingPublisherConfirmationsRateLimiter is not null)
                 {
-                    if (_outstandingPublisherConfirmationsRateLimiter is not null)
+                    lease = await _outstandingPublisherConfirmationsRateLimiter.AcquireAsync(cancellationToken: cancellationToken)
+                        .ConfigureAwait(false);
+                    if (false == lease.IsAcquired)
                     {
-                        lease = await _outstandingPublisherConfirmationsRateLimiter.AcquireAsync(
-                            cancellationToken: cancellationToken)
-                            .ConfigureAwait(false);
-
-                        if (!lease.IsAcquired)
-                        {
-                            throw new InvalidOperationException("Could not acquire a lease from the rate limiter.");
-                        }
+                        throw new InvalidOperationException("Could not acquire a lease from the rate limiter.");
                     }
                 }
 
-                await _confirmSemaphore.WaitAsync(cancellationToken)
-                    .ConfigureAwait(false);
+                try
+                {
+                    await _confirmSemaphore.WaitAsync(cancellationToken)
+                        .ConfigureAwait(false);
+                }
+                catch (OperationCanceledException)
+                {
+                    lease?.Dispose();
+                    throw;
+                }
+
+                return lease;
+            }
+
+            return null;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private void MaybeReleasePublisherConfirmationLock(RateLimitLease? lease)
+        {
+            if (_publisherConfirmationsEnabled)
+            {
+                _confirmSemaphore.Release();
+                lease?.Dispose();
+            }
+        }
 
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private PublisherConfirmationInfo? MaybeStartPublisherConfirmationTracking()
+        {
+            if (_publisherConfirmationsEnabled)
+            {
                 ulong publishSequenceNumber = _nextPublishSeqNo;
 
                 TaskCompletionSource<bool>? publisherConfirmationTcs = null;
@@ -326,7 +342,7 @@ await _confirmSemaphore.WaitAsync(cancellationToken)
 
                 _nextPublishSeqNo++;
 
-                return new PublisherConfirmationInfo(publishSequenceNumber, publisherConfirmationTcs, lease);
+                return new PublisherConfirmationInfo(publishSequenceNumber, publisherConfirmationTcs);
             }
             else
             {
@@ -362,25 +378,6 @@ private async Task MaybeEndPublisherConfirmationTrackingAsync(PublisherConfirmat
         {
             if (_publisherConfirmationsEnabled)
             {
-                try
-                {
-                    _confirmSemaphore.Release();
-                }
-                catch (SemaphoreFullException ex)
-                {
-                    /*
-                     * rabbitmq/rabbitmq-dotnet-client-1793
-                     * If MaybeStartPublisherConfirmationTracking throws an exception *prior* to acquiring
-                     * _confirmSemaphore, the above Release() call will throw SemaphoreFullException.
-                     * In "normal" cases, publisherConfirmationInfo will thus be null, but if not, throw
-                     * a "bug found" exception here.
-                     */
-                    if (publisherConfirmationInfo is not null)
-                    {
-                        throw new InvalidOperationException(InternalConstants.BugFound, ex);
-                    }
-                }
-
                 if (publisherConfirmationInfo is not null)
                 {
                     try
@@ -393,10 +390,6 @@ await publisherConfirmationInfo.MaybeWaitForConfirmationAsync(cancellationToken)
                         _confirmsTaskCompletionSources.TryRemove(publisherConfirmationInfo.PublishSequenceNumber, out _);
                         throw;
                     }
-                    finally
-                    {
-                        publisherConfirmationInfo.Dispose();
-                    }
                 }
             }
         }

projects/Test/Integration/GH/TestGitHubIssues.cs

@@ -1,4 +1,4 @@
-// This source code is dual-licensed under the Apache License, version
+// This source code is dual-licensed under the Apache License, version
 // 2.0, and the Mozilla Public License, version 2.0.
 //
 // The APL v2.0:
@@ -370,11 +370,6 @@ await Assert.ThrowsAnyAsync<InvalidOperationException>(async () =>
                         });
                         break;
                     }
-                    catch (SemaphoreFullException ex0)
-                    {
-                        _output.WriteLine("{0} ex: {1}", _testDisplayName, ex0);
-                        retryCount++;
-                    }
                     catch (PublishException)
                     {
                         retryCount++;