feat: introduce metrics based on system diagnostics

Directory.Packages.props

@@ -5,9 +5,15 @@
   <ItemGroup>
     <!-- RabbitMQ.Amqp.Client -->
     <PackageVersion Include="AMQPNetLite.Core" Version="2.4.11" />
+    <PackageVersion Include="OpenTelemetry" Version="1.10.0" />
+    <PackageVersion Include="OpenTelemetry.Exporter.Console" Version="1.10.0" />
+    <PackageVersion Include="System.Diagnostics.DiagnosticSource" Version="9.0.0" />
     <!-- HAClient -->
     <PackageVersion Include="DotNext.Threading" Version="5.15.0" />
     <!-- Tests -->
+    <PackageVersion Include="Microsoft.Extensions.Diagnostics" Version="9.0.0" />
+    <PackageVersion Include="Microsoft.Extensions.Diagnostics.Testing" Version="9.0.0" />
+    <PackageVersion Include="System.Text.Json" Version="9.0.0" />
     <PackageVersion Include="xunit" Version="2.9.2" />
     <PackageVersion Include="xunit.runner.visualstudio" Version="2.8.2" />
     <PackageVersion Include="Xunit.SkippableFact" Version="1.4.13" />
@@ -22,11 +28,7 @@
       * https://github.com/rabbitmq/rabbitmq-dotnet-client/pull/1481#pullrequestreview-1847905299
       * https://github.com/rabbitmq/rabbitmq-dotnet-client/pull/1594
     -->
-    <PackageVersion Include="System.Diagnostics.DiagnosticSource" Version="6.0.0" />
-    <PackageVersion Include="System.Runtime.CompilerServices.Unsafe" Version="6.0.0" />
-  </ItemGroup>
-  <ItemGroup Condition="'$(TargetFramework)'=='net8.0'">
-    <PackageVersion Include="System.Diagnostics.DiagnosticSource" Version="8.0.1" />
+    <PackageVersion Include="System.Runtime.CompilerServices.Unsafe" Version="6.1.0" />
   </ItemGroup>
   <ItemGroup Condition="'$(TargetFrameworkIdentifier)'=='.NETFramework'">
     <GlobalPackageReference Include="Microsoft.NETFramework.ReferenceAssemblies" Version="1.0.3" />
@@ -36,4 +38,4 @@
     <GlobalPackageReference Include="Microsoft.SourceLink.GitHub" Version="8.0.0" />
     <GlobalPackageReference Include="MinVer" Version="6.0.0" />
   </ItemGroup>
-</Project>
+</Project>

RabbitMQ.AMQP.Client/ILifeCycle.cs

@@ -35,6 +35,7 @@ public override string ToString()
 
     public delegate void LifeCycleCallBack(object sender, State previousState, State currentState, Error? failureCause);
 
+    // TODO consider adding IAsyncDisposable that could call CloseAsync()
     public interface ILifeCycle : IDisposable
     {
         Task CloseAsync();

RabbitMQ.AMQP.Client/IMetricsReporter.cs

@@ -0,0 +1,40 @@
+// This source code is dual-licensed under the Apache License, version
+// 2.0, and the Mozilla Public License, version 2.0.
+// Copyright (c) 2017-2023 Broadcom. All Rights Reserved. The term "Broadcom" refers to Broadcom Inc. and/or its subsidiaries.
+
+using System;
+
+namespace RabbitMQ.AMQP.Client
+{
+    public interface IMetricsReporter
+    {
+        enum PublishDispositionValue
+        {
+            ACCEPTED,
+            REJECTED,
+            RELEASED
+        };
+
+        enum ConsumeDispositionValue
+        {
+            ACCEPTED,
+            DISCARDED,
+            REQUEUED
+        };
+
+        void ConnectionOpened();
+        void ConnectionClosed();
+
+        void PublisherOpened();
+        void PublisherClosed();
+
+        void ConsumerOpened();
+        void ConsumerClosed();
+
+        void Published(TimeSpan elapsed);
+        void PublishDisposition(PublishDispositionValue disposition);
+
+        void Consumed(TimeSpan elapsed);
+        void ConsumeDisposition(ConsumeDispositionValue disposition);
+    }
+}

RabbitMQ.AMQP.Client/Impl/AmqpConnection.cs

@@ -34,7 +34,8 @@ public class AmqpConnection : AbstractLifeCycle, IConnection
         private readonly AmqpManagement _management;
         private readonly RecordingTopologyListener _recordingTopologyListener = new();
 
-        private readonly IConnectionSettings _connectionSettings;
+        internal readonly IConnectionSettings _connectionSettings;
+        private readonly IMetricsReporter? _metricsReporter;
         internal readonly AmqpSessionManagement _nativePubSubSessions;
 
         private readonly Dictionary<string, object> _connectionProperties = new();
@@ -104,7 +105,6 @@ public IRpcServerBuilder RpcServerBuilder()
 
         public IRpcClientBuilder RpcClientBuilder()
         {
-
             return new AmqpRpcClientBuilder(this);
         }
 
@@ -131,17 +131,22 @@ public IEnumerable<IConsumer> Consumers
         public IReadOnlyDictionary<string, object> Properties => _connectionProperties;
 
         public long Id { get; set; }
+
         /// <summary>
         /// Creates a new instance of <see cref="AmqpConnection"/>
         /// Through the Connection is possible to create:
         ///  - Management. See <see cref="AmqpManagement"/>
         ///  - Publishers and Consumers: See <see cref="AmqpPublisherBuilder"/> and <see cref="AmqpConsumerBuilder"/> 
         /// </summary>
         /// <param name="connectionSettings"></param>
+        /// <param name="metricsReporter"></param>
         /// <returns></returns>
-        public static async Task<IConnection> CreateAsync(IConnectionSettings connectionSettings)
+        // TODO to play nicely with IoC containers, we should not have static Create methods
+        // TODO rename to CreateAndOpenAsync
+        public static async Task<IConnection> CreateAsync(IConnectionSettings connectionSettings,
+            IMetricsReporter? metricsReporter = default)
         {
-            var connection = new AmqpConnection(connectionSettings);
+            var connection = new AmqpConnection(connectionSettings, metricsReporter);
             await connection.OpenAsync()
                 .ConfigureAwait(false);
             return connection;
@@ -154,7 +159,7 @@ public IManagement Management()
 
         public IConsumerBuilder ConsumerBuilder()
         {
-            return new AmqpConsumerBuilder(this);
+            return new AmqpConsumerBuilder(this, _metricsReporter);
         }
 
         // TODO cancellation token
@@ -170,7 +175,7 @@ await base.OpenAsync()
         public IPublisherBuilder PublisherBuilder()
         {
             ThrowIfClosed();
-            var publisherBuilder = new AmqpPublisherBuilder(this);
+            var publisherBuilder = new AmqpPublisherBuilder(this, _metricsReporter);
             return publisherBuilder;
         }
 
@@ -235,6 +240,7 @@ protected override void Dispose(bool disposing)
                 {
                     _nativeConnection.Closed -= _closedCallback;
                 }
+
                 _semaphoreOpen.Dispose();
                 _semaphoreClose.Dispose();
             }
@@ -265,9 +271,10 @@ await consumer.CloseAsync()
             }
         }
 
-        private AmqpConnection(IConnectionSettings connectionSettings)
+        private AmqpConnection(IConnectionSettings connectionSettings, IMetricsReporter? metricsReporter)
         {
             _connectionSettings = connectionSettings;
+            _metricsReporter = metricsReporter;
             _nativePubSubSessions = new AmqpSessionManagement(this, 1);
             _management =
                 new AmqpManagement(new AmqpManagementParameters(this).TopologyListener(_recordingTopologyListener));
@@ -291,10 +298,7 @@ await _semaphoreOpen.WaitAsync(cancellationToken)
                     HostName = $"vhost:{_connectionSettings.VirtualHost}",
                     // Note: no need to set cf.AMQP.ContainerId
                     ContainerId = _connectionSettings.ContainerId,
-                    Properties = new Fields()
-                    {
-                        [new Symbol("connection_name")] = _connectionSettings.ContainerId,
-                    }
+                    Properties = new Fields() { [new Symbol("connection_name")] = _connectionSettings.ContainerId, }
                 };
 
                 if (_connectionSettings.MaxFrameSize > uint.MinValue)
@@ -350,7 +354,8 @@ void OnOpened(Amqp.IConnection connection, Open openOnOpened)
                     if (_connectionSettings is null)
                     {
                         // TODO create "internal bug" exception type?
-                        throw new InvalidOperationException("_connectionSettings is null, report via https://github.com/rabbitmq/rabbitmq-amqp-dotnet-client/issues");
+                        throw new InvalidOperationException(
+                            "_connectionSettings is null, report via https://github.com/rabbitmq/rabbitmq-amqp-dotnet-client/issues");
                     }
                     else
                     {
@@ -497,8 +502,8 @@ await OpenConnectionAsync(CancellationToken.None)
                         if (false == connected)
                         {
                             var notRecoveredError = new Error(ConnectionNotRecoveredCode,
-                                    $"{ConnectionNotRecoveredMessage}," +
-                                    $"recover status: {_connectionSettings.Recovery}");
+                                $"{ConnectionNotRecoveredMessage}," +
+                                $"recover status: {_connectionSettings.Recovery}");
                             DoClose(notRecoveredError);
                             return;
                         }

RabbitMQ.AMQP.Client/Impl/AmqpConsumer.cs

@@ -3,11 +3,14 @@
 // Copyright (c) 2017-2023 Broadcom. All Rights Reserved. The term "Broadcom" refers to Broadcom Inc. and/or its subsidiaries.
 
 using System;
+using System.Diagnostics;
 using System.Runtime.CompilerServices;
 using System.Threading;
 using System.Threading.Tasks;
 using Amqp;
 using Amqp.Framing;
+using Trace = Amqp.Trace;
+using TraceLevel = Amqp.TraceLevel;
 
 namespace RabbitMQ.AMQP.Client.Impl
 {
@@ -28,12 +31,13 @@ private enum PauseStatus
         private PauseStatus _pauseStatus = PauseStatus.UNPAUSED;
         private readonly UnsettledMessageCounter _unsettledMessageCounter = new();
         private readonly ConsumerConfiguration _configuration;
+        private readonly IMetricsReporter? _metricsReporter;
 
-        internal AmqpConsumer(AmqpConnection amqpConnection, ConsumerConfiguration configuration)
+        internal AmqpConsumer(AmqpConnection amqpConnection, ConsumerConfiguration configuration, IMetricsReporter? metricsReporter)
         {
             _amqpConnection = amqpConnection;
             _configuration = configuration;
-
+            _metricsReporter = metricsReporter;
             _amqpConnection.AddConsumer(_id, this);
         }
 
@@ -127,11 +131,21 @@ private async Task ProcessMessages()
                     return;
                 }
 
+                Stopwatch? stopwatch = null;
+                if (_metricsReporter is not null)
+                {
+                    stopwatch = new();
+                }
+
                 while (_receiverLink is { LinkState: LinkState.Attached })
                 {
+                    stopwatch?.Restart();
+
                     // TODO the timeout waiting for messages should be configurable
                     TimeSpan timeout = TimeSpan.FromSeconds(60);
-                    Message? nativeMessage = await _receiverLink.ReceiveAsync(timeout).ConfigureAwait(false);
+                    Message? nativeMessage = await _receiverLink.ReceiveAsync(timeout)
+                        .ConfigureAwait(false);
+
                     if (nativeMessage is null)
                     {
                         // this is not a problem, it is just a timeout. 
@@ -144,15 +158,24 @@ private async Task ProcessMessages()
 
                     _unsettledMessageCounter.Increment();
 
-                    IContext context = new DeliveryContext(_receiverLink, nativeMessage, _unsettledMessageCounter);
+                    IContext context = new DeliveryContext(_receiverLink, nativeMessage,
+                        _unsettledMessageCounter, _metricsReporter);
                     var amqpMessage = new AmqpMessage(nativeMessage);
 
                     // TODO catch exceptions thrown by handlers,
                     // then call exception handler?
-                    if (_configuration.Handler != null)
+                    if (_configuration.Handler is not null)
                     {
-                        await _configuration.Handler(context, amqpMessage).ConfigureAwait(false);
+                        await _configuration.Handler(context, amqpMessage)
+                            .ConfigureAwait(false);
                     }
+
+                    if (_metricsReporter is not null && stopwatch is not null)
+                    {
+                        stopwatch.Stop();
+                        _metricsReporter.Consumed(stopwatch.Elapsed);
+                    }
+
                 }
             }
             catch (Exception e)

RabbitMQ.AMQP.Client/Impl/AmqpConsumerBuilder.cs

@@ -19,6 +19,7 @@ internal sealed class ConsumerConfiguration
         public string Address { get; set; } = "";
         public int InitialCredits { get; set; } = 100; // TODO use constant, check with Java lib
         public Map Filters { get; set; } = new();
+        // TODO is a MessageHandler *really* optional???
         public MessageHandler? Handler { get; set; }
         // TODO re-name to ListenerContextAction? Callback?
         public Action<IConsumerBuilder.ListenerContext>? ListenerContext = null;
@@ -32,10 +33,12 @@ public class AmqpConsumerBuilder : IConsumerBuilder
     {
         private readonly ConsumerConfiguration _configuration = new();
         private readonly AmqpConnection _amqpConnection;
+        private readonly IMetricsReporter? _metricsReporter;
 
-        public AmqpConsumerBuilder(AmqpConnection connection)
+        public AmqpConsumerBuilder(AmqpConnection connection, IMetricsReporter? metricsReporter)
         {
             _amqpConnection = connection;
+            _metricsReporter = metricsReporter;
         }
 
         public IConsumerBuilder Queue(IQueueSpecification queueSpec)
@@ -81,7 +84,7 @@ public async Task<IConsumer> BuildAndStartAsync(CancellationToken cancellationTo
                 throw new ConsumerException("Message handler is not set");
             }
 
-            AmqpConsumer consumer = new(_amqpConnection, _configuration);
+            AmqpConsumer consumer = new(_amqpConnection, _configuration, _metricsReporter);
 
             // TODO pass cancellationToken
             await consumer.OpenAsync()

RabbitMQ.AMQP.Client/Impl/AmqpEnvironment.cs

@@ -12,23 +12,26 @@ namespace RabbitMQ.AMQP.Client.Impl
 {
     public class AmqpEnvironment : IEnvironment
     {
-        private IConnectionSettings? ConnectionSettings { get; }
+        private IConnectionSettings ConnectionSettings { get; }
         private long _sequentialId = 0;
         private readonly ConcurrentDictionary<long, IConnection> _connections = new();
+        private readonly IMetricsReporter? _metricsReporter;
 
-        private AmqpEnvironment(IConnectionSettings connectionSettings)
+        private AmqpEnvironment(IConnectionSettings connectionSettings, IMetricsReporter? metricsReporter = default)
         {
             ConnectionSettings = connectionSettings;
+            _metricsReporter = metricsReporter;
         }
 
-        public static Task<IEnvironment> CreateAsync(IConnectionSettings connectionSettings)
+        // TODO to play nicely with IoC containers, we should not have static Create methods
+        public static IEnvironment Create(IConnectionSettings connectionSettings, IMetricsReporter? metricsReporter = default)
         {
-            return Task.FromResult<IEnvironment>(new AmqpEnvironment(connectionSettings));
+            return new AmqpEnvironment(connectionSettings, metricsReporter);
         }
 
         public async Task<IConnection> CreateConnectionAsync(IConnectionSettings connectionSettings)
         {
-            IConnection c = await AmqpConnection.CreateAsync(connectionSettings).ConfigureAwait(false);
+            IConnection c = await AmqpConnection.CreateAsync(connectionSettings, _metricsReporter).ConfigureAwait(false);
             c.Id = Interlocked.Increment(ref _sequentialId);
             _connections.TryAdd(c.Id, c);
             c.ChangeState += (sender, previousState, currentState, failureCause) =>