throw RpcException from writes after finishing

2 files changed, 14 insertions, 1 deletions

diff --git a/src/csharp/Grpc.Core/Internal/AsyncCall.cs b/src/csharp/Grpc.Core/Internal/AsyncCall.cs
index da1e6592d1..55351869b5 100644
--- a/src/csharp/Grpc.Core/Internal/AsyncCall.cs
+++ b/src/csharp/Grpc.Core/Internal/AsyncCall.cs
@@ -443,6 +443,19 @@ namespace Grpc.Core.Internal
             }
         }
 
+        protected override void CheckSendingAllowed(bool allowFinished)
+        {
+            base.CheckSendingAllowed(true);
+
+            // throwing RpcException if we already received status on client
+            // side makes the most sense.
+            // Note that this throws even for StatusCode.OK.
+            if (!allowFinished && finishedStatus.HasValue)
+            {
+                throw new RpcException(finishedStatus.Value.Status);
+            }
+        }
+
         /// <summary>
         /// Handles receive status completion for calls with streaming response.
         /// </summary>
diff --git a/src/csharp/Grpc.Core/Internal/AsyncCallBase.cs b/src/csharp/Grpc.Core/Internal/AsyncCallBase.cs
index 42234dcac2..4de23706b2 100644
--- a/src/csharp/Grpc.Core/Internal/AsyncCallBase.cs
+++ b/src/csharp/Grpc.Core/Internal/AsyncCallBase.cs
@@ -213,7 +213,7 @@ namespace Grpc.Core.Internal
         {
         }
 
-        protected void CheckSendingAllowed(bool allowFinished)
+        protected virtual void CheckSendingAllowed(bool allowFinished)
         {
             GrpcPreconditions.CheckState(started);
             CheckNotCancelled();