* We've come full circle ... restoring @danielmarbach's original changes.

Author: lukebakken

projects/RabbitMQ.Client/PublicAPI.Shipped.txt

@@ -894,4 +894,4 @@ static RabbitMQ.Client.IChannelExtensions.BasicPublishAsync(this RabbitMQ.Client
 RabbitMQ.Client.IChannel.ConfirmSelectAsync(bool trackConfirmations = true, System.Threading.CancellationToken cancellationToken = default(System.Threading.CancellationToken)) -> System.Threading.Tasks.Task!
 const RabbitMQ.Client.Constants.DefaultConsumerDispatchConcurrency = 1 -> ushort
 readonly RabbitMQ.Client.ConnectionConfig.ConsumerDispatchConcurrency -> ushort
-RabbitMQ.Client.IConnection.CreateChannelAsync(ushort consumerDispatchConcurrency = 1, System.Threading.CancellationToken cancellationToken = default(System.Threading.CancellationToken)) -> System.Threading.Tasks.Task<RabbitMQ.Client.IChannel!>!
+RabbitMQ.Client.IConnection.CreateChannelAsync(ushort? consumerDispatchConcurrency = null, System.Threading.CancellationToken cancellationToken = default(System.Threading.CancellationToken)) -> System.Threading.Tasks.Task<RabbitMQ.Client.IChannel!>!

projects/RabbitMQ.Client/client/api/IConnection.cs

@@ -239,13 +239,13 @@ Task CloseAsync(ushort reasonCode, string reasonText, TimeSpan timeout, bool abo
         /// will be offloaded to the worker thread pool so it is important to choose the value for the concurrency wisely to avoid thread pool overloading.
         /// <see cref="IAsyncBasicConsumer"/> can handle concurrency much more efficiently due to the non-blocking nature of the consumer.
         ///
-        /// Defaults to <see cref="Constants.DefaultConsumerDispatchConcurrency"/>.
+        /// Defaults to <c>null</c>, which will use the value from <see cref="IConnectionFactory.ConsumerDispatchConcurrency"/>
         /// 
         /// For concurrency greater than one this removes the guarantee that consumers handle messages in the order they receive them.
         /// In addition to that consumers need to be thread/concurrency safe.
         /// </param>
         /// <param name="cancellationToken">Cancellation token</param>
-        Task<IChannel> CreateChannelAsync(ushort consumerDispatchConcurrency = Constants.DefaultConsumerDispatchConcurrency,
+        Task<IChannel> CreateChannelAsync(ushort? consumerDispatchConcurrency = null,
             CancellationToken cancellationToken = default);
     }
 }

projects/RabbitMQ.Client/client/framing/Channel.cs

@@ -38,8 +38,7 @@ namespace RabbitMQ.Client.Framing.Impl
 {
     internal class Channel : ChannelBase
     {
-        public Channel(ConnectionConfig config, ISession session,
-            ushort consumerDispatchConcurrency = Constants.DefaultConsumerDispatchConcurrency)
+        public Channel(ConnectionConfig config, ISession session, ushort? consumerDispatchConcurrency = null)
             : base(config, session, consumerDispatchConcurrency)
         {
         }

projects/RabbitMQ.Client/client/framing/Constants.cs

@@ -87,7 +87,7 @@ public static class Constants
         /// <summary>
         /// The default consumer dispatch concurrency. See <see cref="IConnectionFactory.ConsumerDispatchConcurrency"/>
         /// to set this value for every channel created on a connection,
-        /// and <see cref="IConnection.CreateChannelAsync(ushort, System.Threading.CancellationToken)"/>
+        /// and <see cref="IConnection.CreateChannelAsync(ushort?, System.Threading.CancellationToken)"/>
         /// for setting this value for a particular channel.
         /// </summary>
         public const ushort DefaultConsumerDispatchConcurrency = 1;

projects/RabbitMQ.Client/client/impl/AutorecoveringConnection.cs

@@ -37,7 +37,6 @@
 using RabbitMQ.Client.Events;
 using RabbitMQ.Client.Exceptions;
 using RabbitMQ.Client.Impl;
-using RabbitMQ.Util;
 
 namespace RabbitMQ.Client.Framing.Impl
 {
@@ -241,11 +240,11 @@ await CloseInnerConnectionAsync()
             }
         }
 
-        public async Task<IChannel> CreateChannelAsync(ushort consumerDispatchConcurrency = Constants.DefaultConsumerDispatchConcurrency,
+        public async Task<IChannel> CreateChannelAsync(ushort? consumerDispatchConcurrency = null,
             CancellationToken cancellationToken = default)
         {
             EnsureIsOpen();
-            ushort cdc = Misc.DetermineConsumerDispatchConcurrency(_config, consumerDispatchConcurrency);
+            ushort cdc = consumerDispatchConcurrency.GetValueOrDefault(_config.ConsumerDispatchConcurrency);
             RecoveryAwareChannel recoveryAwareChannel = await CreateNonRecoveringChannelAsync(cdc, cancellationToken)
                 .ConfigureAwait(false);
             AutorecoveringChannel channel = new AutorecoveringChannel(this, recoveryAwareChannel, cdc);

projects/RabbitMQ.Client/client/impl/ChannelBase.cs

@@ -45,7 +45,6 @@
 using RabbitMQ.Client.Events;
 using RabbitMQ.Client.Exceptions;
 using RabbitMQ.Client.Framing.Impl;
-using RabbitMQ.Util;
 
 namespace RabbitMQ.Client.Impl
 {
@@ -75,10 +74,11 @@ internal abstract class ChannelBase : IChannel, IRecoverable
         internal readonly IConsumerDispatcher ConsumerDispatcher;
 
         protected ChannelBase(ConnectionConfig config, ISession session,
-            ushort consumerDispatchConcurrency = Constants.DefaultConsumerDispatchConcurrency)
+            ushort? perChannelConsumerDispatchConcurrency = null)
         {
             ContinuationTimeout = config.ContinuationTimeout;
-            ConsumerDispatcher = BuildConsumerDispatcher(config, consumerDispatchConcurrency);
+            ConsumerDispatcher = new AsyncConsumerDispatcher(this,
+                perChannelConsumerDispatchConcurrency.GetValueOrDefault(config.ConsumerDispatchConcurrency));
             Action<Exception, string> onException = (exception, context) =>
                 OnCallbackException(CallbackExceptionEventArgs.Build(exception, context));
             _basicAcksWrapper = new EventingWrapper<BasicAckEventArgs>("OnBasicAck", onException);
@@ -94,12 +94,6 @@ protected ChannelBase(ConnectionConfig config, ISession session,
             Session = session;
         }
 
-        private IConsumerDispatcher BuildConsumerDispatcher(ConnectionConfig config, ushort perChannelConsumerDispatchConcurrency)
-        {
-            ushort cdc = Misc.DetermineConsumerDispatchConcurrency(config, perChannelConsumerDispatchConcurrency);
-            return new AsyncConsumerDispatcher(this, cdc);
-        }
-
         internal TimeSpan HandshakeContinuationTimeout { get; set; } = TimeSpan.FromSeconds(10);
         public TimeSpan ContinuationTimeout { get; set; }
 

projects/RabbitMQ.Client/client/impl/Connection.cs

@@ -253,7 +253,7 @@ await CloseAsync(ea, true,
             }
         }
 
-        public Task<IChannel> CreateChannelAsync(ushort consumerDispatchConcurrency = Constants.DefaultConsumerDispatchConcurrency,
+        public Task<IChannel> CreateChannelAsync(ushort? consumerDispatchConcurrency = null,
             CancellationToken cancellationToken = default)
         {
             EnsureIsOpen();