Fix bugs related to channel dispose while there are active calls

src/Grpc.Net.Client/Configuration/HedgingPolicy.cs

@@ -1,4 +1,4 @@
-#region Copyright notice and license
+#region Copyright notice and license
 
 // Copyright 2019 The gRPC Authors
 //
@@ -37,7 +37,7 @@ public sealed class HedgingPolicy : ConfigObject
     internal const string HedgingDelayPropertyName = "hedgingDelay";
     internal const string NonFatalStatusCodesPropertyName = "nonFatalStatusCodes";
 
-    private ConfigProperty<Values<StatusCode, object>, IList<object>> _nonFatalStatusCodes =
+    private readonly ConfigProperty<Values<StatusCode, object>, IList<object>> _nonFatalStatusCodes =
         new(i => new Values<StatusCode, object>(i ?? new List<object>(), s => ConvertHelpers.ConvertStatusCode(s), s => ConvertHelpers.ConvertStatusCode(s.ToString()!)), NonFatalStatusCodesPropertyName);
 
     /// <summary>

src/Grpc.Net.Client/GrpcChannel.cs

@@ -483,6 +483,13 @@ internal void RegisterActiveCall(IDisposable grpcCall)
     {
         lock (_lock)
         {
+            // Test the disposed flag inside the lock to ensure there is no chance of a race and adding a call after dispose.
+            // Note that a GrpcCall has been created but hasn't been started. The error will prevent it from starting.
+            if (Disposed)
+            {
+                throw new ObjectDisposedException(nameof(GrpcChannel));
+            }
+
             ActiveCalls.Add(grpcCall);
         }
     }
@@ -733,23 +740,29 @@ public Task WaitForStateChangedAsync(ConnectivityState lastObservedState, Cancel
     /// </summary>
     public void Dispose()
     {
-        if (Disposed)
-        {
-            return;
-        }
-
+        IDisposable[]? activeCallsCopy = null;
         lock (_lock)
         {
+            // Check and set disposed flag inside lock.
+            if (Disposed)
+            {
+                return;
+            }
+
             if (ActiveCalls.Count > 0)
             {
-                // Disposing a call will remove it from ActiveCalls. Need to take a copy
-                // to avoid enumeration from being modified
-                var activeCallsCopy = ActiveCalls.ToArray();
+                activeCallsCopy = ActiveCalls.ToArray();
+            }
 
-                foreach (var activeCall in activeCallsCopy)
-                {
-                    activeCall.Dispose();
-                }
+            Disposed = true;
+        }
+
+        // Dispose calls outside of lock to avoid chance of deadlock.
+        if (activeCallsCopy is not null)
+        {
+            foreach (var activeCall in activeCallsCopy)
+            {
+                activeCall.Dispose();
             }
         }
 
@@ -760,7 +773,6 @@ public void Dispose()
 #if SUPPORT_LOAD_BALANCING
         ConnectionManager.Dispose();
 #endif
-        Disposed = true;
     }
 
     internal bool TryAddToRetryBuffer(long messageSize)

src/Grpc.Net.Client/Internal/HttpClientCallInvoker.cs

@@ -1,4 +1,4 @@
-#region Copyright notice and license
+#region Copyright notice and license
 
 // Copyright 2019 The gRPC Authors
 //
@@ -150,11 +150,6 @@ public HttpClientCallInvoker(GrpcChannel channel)
         where TRequest : class
         where TResponse : class
     {
-        if (channel.Disposed)
-        {
-            throw new ObjectDisposedException(nameof(GrpcChannel));
-        }
-
         var methodInfo = channel.GetCachedGrpcMethodInfo(method);
         var call = new GrpcCall<TRequest, TResponse>(method, methodInfo, options, channel, attempt);
 

src/Grpc.Net.Client/Internal/Retry/HedgingCall.cs

@@ -1,4 +1,4 @@
-#region Copyright notice and license
+#region Copyright notice and license
 
 // Copyright 2019 The gRPC Authors
 //
@@ -54,6 +54,8 @@ public HedgingCall(HedgingPolicyInfo hedgingPolicy, GrpcChannel channel, Method<
             _delayInterruptTcs = new TaskCompletionSource<object?>(TaskCreationOptions.RunContinuationsAsynchronously);
             _hedgingDelayCts = new CancellationTokenSource();
         }
+
+        Channel.RegisterActiveCall(this);
     }
 
     private async Task StartCall(Action<GrpcCall<TRequest, TResponse>> startCallFunc)

src/Grpc.Net.Client/Internal/Retry/RetryCall.cs

@@ -1,4 +1,4 @@
-#region Copyright notice and license
+#region Copyright notice and license
 
 // Copyright 2019 The gRPC Authors
 //
@@ -42,6 +42,8 @@ public RetryCall(RetryPolicyInfo retryPolicy, GrpcChannel channel, Method<TReque
         _retryPolicy = retryPolicy;
 
         _nextRetryDelayMilliseconds = Convert.ToInt32(retryPolicy.InitialBackoff.TotalMilliseconds);
+
+        Channel.RegisterActiveCall(this);
     }
 
     private int CalculateNextRetryDelay()

src/Grpc.Net.Client/Internal/Retry/RetryCallBase.cs

@@ -1,4 +1,4 @@
-#region Copyright notice and license
+#region Copyright notice and license
 
 // Copyright 2019 The gRPC Authors
 //
@@ -440,6 +440,8 @@ protected virtual void Dispose(bool disposing)
 
     protected void Cleanup()
     {
+        Channel.FinishActiveCall(this);
+
         _ctsRegistration?.Dispose();
         _ctsRegistration = null;
         CancellationTokenSource.Cancel();

test/FunctionalTests/Client/RetryTests.cs

@@ -1,4 +1,4 @@
-#region Copyright notice and license
+#region Copyright notice and license
 
 // Copyright 2019 The gRPC Authors
 //
@@ -108,6 +108,8 @@ await foreach (var message in requestStream.ReadAllAsync())
 
         // Assert
         Assert.IsTrue(result.Data.Span.SequenceEqual(sentData.ToArray()));
+
+        Assert.AreEqual(0, channel.ActiveCalls.Count);
     }
 
     [Test]
@@ -390,6 +392,8 @@ Task FakeServerStreamCall(DataMessage request, IServerStreamWriter<DataMessage>
         await MakeCallsAsync(channel, method, references, cts.Token).DefaultTimeout();
 
         // Assert
+        Assert.AreEqual(0, channel.ActiveCalls.Count);
+
         // There is a race when cleaning up cancellation token registry.
         // Retry a few times to ensure GC is run after unregister.
         await TestHelpers.AssertIsTrueRetryAsync(() =>

test/Grpc.Net.Client.Tests/AsyncDuplexStreamingCallTests.cs

@@ -1,4 +1,4 @@
-#region Copyright notice and license
+#region Copyright notice and license
 
 // Copyright 2019 The gRPC Authors
 //
@@ -17,13 +17,16 @@
 #endregion
 
 using System.Net;
+using System.Threading.Tasks;
 using Greet;
 using Grpc.Core;
 using Grpc.Net.Client.Internal;
 using Grpc.Net.Client.Internal.Http;
 using Grpc.Net.Client.Tests.Infrastructure;
 using Grpc.Shared;
 using Grpc.Tests.Shared;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging;
 using NUnit.Framework;
 
 namespace Grpc.Net.Client.Tests;
@@ -177,4 +180,81 @@ public async Task AsyncDuplexStreamingCall_MessagesStreamed_MessagesReceived()
         Assert.IsTrue(moveNextTask4.IsCompleted);
         Assert.IsFalse(await moveNextTask3.DefaultTimeout());
     }
+
+    [Test]
+    public async Task AsyncDuplexStreamingCall_CancellationDisposeRace_Success()
+    {
+        // Arrange
+        var services = new ServiceCollection();
+        services.AddNUnitLogger();
+        var loggerFactory = services.BuildServiceProvider().GetRequiredService<ILoggerFactory>();
+        var logger = loggerFactory.CreateLogger(GetType());
+
+        for (var i = 0; i < 20; i++)
+        {
+            // Let's mimic a real call first to get GrpcCall.RunCall where we need to for reproducing the deadlock.
+            var streamContent = new SyncPointMemoryStream();
+            var requestContentTcs = new TaskCompletionSource<Task<Stream>>(TaskCreationOptions.RunContinuationsAsynchronously);
+
+            PushStreamContent<HelloRequest, HelloReply>? content = null;
+
+            var handler = TestHttpMessageHandler.Create(async request =>
+            {
+                content = (PushStreamContent<HelloRequest, HelloReply>)request.Content!;
+                var streamTask = content.ReadAsStreamAsync();
+                requestContentTcs.SetResult(streamTask);
+                // Wait for RequestStream.CompleteAsync()
+                await streamTask;
+                return ResponseUtils.CreateResponse(HttpStatusCode.OK, new StreamContent(streamContent));
+            });
+            var channel = GrpcChannel.ForAddress("http://localhost", new GrpcChannelOptions
+            {
+                HttpHandler = handler,
+                LoggerFactory = loggerFactory
+            });
+            var invoker = channel.CreateCallInvoker();
+
+            var cts = new CancellationTokenSource();
+
+            var call = invoker.AsyncDuplexStreamingCall<HelloRequest, HelloReply>(ClientTestHelpers.ServiceMethod, string.Empty, new CallOptions(cancellationToken: cts.Token));
+            await call.RequestStream.WriteAsync(new HelloRequest { Name = "1" }).DefaultTimeout();
+            await call.RequestStream.CompleteAsync().DefaultTimeout();
+
+            // Let's read a response
+            var deserializationContext = new DefaultDeserializationContext();
+            var requestContent = await await requestContentTcs.Task.DefaultTimeout();
+            var requestMessage = await StreamSerializationHelper.ReadMessageAsync(
+                requestContent,
+                ClientTestHelpers.ServiceMethod.RequestMarshaller.ContextualDeserializer,
+                GrpcProtocolConstants.IdentityGrpcEncoding,
+                maximumMessageSize: null,
+                GrpcProtocolConstants.DefaultCompressionProviders,
+                singleMessage: false,
+                CancellationToken.None).DefaultTimeout();
+            Assert.AreEqual("1", requestMessage!.Name);
+
+            var actTcs = new TaskCompletionSource<object?>(TaskCreationOptions.RunContinuationsAsynchronously);
+
+            var cancellationTask = Task.Run(async () =>
+            {
+                await actTcs.Task;
+                cts.Cancel();
+            });
+            var disposingTask = Task.Run(async () =>
+            {
+                await actTcs.Task;
+                channel.Dispose();
+            });
+
+            // Small pause to make sure we're waiting at the TCS everywhere.
+            await Task.Delay(50);
+
+            // Act
+            actTcs.SetResult(null);
+
+            // Assert
+            // Cancellation and disposing should both complete quickly. If there is a deadlock then the await will timeout.
+            await Task.WhenAll(cancellationTask, disposingTask).DefaultTimeout();
+        }
+    }
 }

test/Grpc.Net.Client.Tests/Retry/HedgingTests.cs

@@ -1,4 +1,4 @@
-#region Copyright notice and license
+#region Copyright notice and license
 
 // Copyright 2019 The gRPC Authors
 //
@@ -72,6 +72,8 @@ public async Task AsyncUnaryCall_OneAttempt_Success(int maxAttempts)
         var rs = await call.ResponseAsync.DefaultTimeout();
         Assert.AreEqual("Hello world", rs.Message);
         Assert.AreEqual(StatusCode.OK, call.GetStatus().StatusCode);
+
+        Assert.AreEqual(0, invoker.Channel.ActiveCalls.Count);
     }
 
     [Test]
@@ -591,7 +593,6 @@ public async Task AsyncClientStreamingCall_SuccessAfterRetry_RequestContentSent(
         var responseTask = call.ResponseAsync;
         Assert.IsFalse(responseTask.IsCompleted, "Response not returned until client stream is complete.");
 
-
         await call.RequestStream.WriteAsync(new HelloRequest { Name = "1" }).DefaultTimeout();
         await call.RequestStream.WriteAsync(new HelloRequest { Name = "2" }).DefaultTimeout();
 
@@ -687,6 +688,54 @@ public async Task AsyncClientStreamingCall_WriteAfterResult_Error()
         Assert.AreEqual(StatusCode.OK, ex.StatusCode);
     }
 
+    [Test]
+    public void AsyncUnaryCall_DisposedChannel_Error()
+    {
+        // Arrange
+        var httpClient = ClientTestHelpers.CreateTestClient(request =>
+        {
+            return Task.FromResult(ResponseUtils.CreateResponse(HttpStatusCode.OK));
+        });
+        var serviceConfig = ServiceConfigHelpers.CreateHedgingServiceConfig();
+        var invoker = HttpClientCallInvokerFactory.Create(httpClient, serviceConfig: serviceConfig);
+
+        // Act & Assert
+        invoker.Channel.Dispose();
+        Assert.Throws<ObjectDisposedException>(() => invoker.AsyncUnaryCall<HelloRequest, HelloReply>(ClientTestHelpers.ServiceMethod, string.Empty, new CallOptions(), new HelloRequest { Name = "World" }));
+    }
+
+    [Test]
+    public async Task AsyncUnaryCall_ChannelDisposeDuringBackoff_CanceledStatus()
+    {
+        // Arrange
+        var callCount = 0;
+        var httpClient = ClientTestHelpers.CreateTestClient(async request =>
+        {
+            callCount++;
+
+            await request.Content!.CopyToAsync(new MemoryStream());
+            return ResponseUtils.CreateHeadersOnlyResponse(HttpStatusCode.OK, StatusCode.Unavailable, retryPushbackHeader: TimeSpan.FromSeconds(10).TotalMilliseconds.ToString(CultureInfo.InvariantCulture));
+        });
+        var serviceConfig = ServiceConfigHelpers.CreateHedgingServiceConfig(hedgingDelay: TimeSpan.FromSeconds(10));
+        var invoker = HttpClientCallInvokerFactory.Create(httpClient, serviceConfig: serviceConfig);
+        var cts = new CancellationTokenSource();
+
+        // Act
+        var call = invoker.AsyncUnaryCall<HelloRequest, HelloReply>(ClientTestHelpers.ServiceMethod, string.Empty, new CallOptions(cancellationToken: cts.Token), new HelloRequest { Name = "World" });
+
+        var delayTask = Task.Delay(100);
+        var completedTask = await Task.WhenAny(call.ResponseAsync, delayTask);
+
+        // Assert
+        Assert.AreEqual(delayTask, completedTask); // Ensure that we're waiting for retry
+
+        invoker.Channel.Dispose();
+
+        var ex = await ExceptionAssert.ThrowsAsync<RpcException>(() => call.ResponseAsync).DefaultTimeout();
+        Assert.AreEqual(StatusCode.Cancelled, ex.StatusCode);
+        Assert.AreEqual("gRPC call disposed.", ex.Status.Detail);
+    }
+
     private static Task<HelloRequest?> ReadRequestMessage(Stream requestContent)
     {
         return StreamSerializationHelper.ReadMessageAsync(