make call object implement IDisposable

src/csharp/Grpc.Core/AsyncClientStreamingCall.cs

@@ -40,7 +40,7 @@ namespace Grpc.Core
     /// <summary>
     /// Return type for client streaming calls.
     /// </summary>
-    public sealed class AsyncClientStreamingCall<TRequest, TResponse>
+    public sealed class AsyncClientStreamingCall<TRequest, TResponse> : IDisposable
     {
         readonly IClientStreamWriter<TRequest> requestStream;
         readonly Task<TResponse> result;
@@ -81,5 +81,17 @@ namespace Grpc.Core
         {
             return result.GetAwaiter();
         }
+
+        /// <summary>
+        /// Provides means to provide after the call.
+        /// If the call has already finished normally (request stream has been completed and call result has been received), doesn't do anything.
+        /// Otherwise, requests cancellation of the call which should terminate all pending async operations associated with the call.
+        /// As a result, all resources being used by the call should be released eventually.
+        /// </summary>
+        public void Dispose()
+        {
+            // TODO(jtattermusch): implement
+            throw new NotImplementedException();
+        }
     }
 }

src/csharp/Grpc.Core/AsyncDuplexStreamingCall.cs

@@ -40,7 +40,7 @@ namespace Grpc.Core
     /// <summary>
     /// Return type for bidirectional streaming calls.
     /// </summary>
-    public sealed class AsyncDuplexStreamingCall<TRequest, TResponse>
+    public sealed class AsyncDuplexStreamingCall<TRequest, TResponse> : IDisposable
     {
         readonly IClientStreamWriter<TRequest> requestStream;
         readonly IAsyncStreamReader<TResponse> responseStream;
@@ -72,5 +72,17 @@ namespace Grpc.Core
                 return requestStream;
             }
         }
+
+        /// <summary>
+        /// Provides means to cleanup after the call.
+        /// If the call has already finished normally (request stream has been completed and response stream has been fully read), doesn't do anything.
+        /// Otherwise, requests cancellation of the call which should terminate all pending async operations associated with the call.
+        /// As a result, all resources being used by the call should be released eventually.
+        /// </summary>
+        public void Dispose()
+        {
+            // TODO(jtattermusch): implement
+            throw new NotImplementedException();
+        }
     }
 }

src/csharp/Grpc.Core/AsyncServerStreamingCall.cs

@@ -40,7 +40,7 @@ namespace Grpc.Core
     /// <summary>
     /// Return type for server streaming calls.
     /// </summary>
-    public sealed class AsyncServerStreamingCall<TResponse>
+    public sealed class AsyncServerStreamingCall<TResponse> : IDisposable
     {
         readonly IAsyncStreamReader<TResponse> responseStream;
 
@@ -59,5 +59,17 @@ namespace Grpc.Core
                 return responseStream;
             }
         }
+
+        /// <summary>
+        /// Provides means to cleanup after the call.
+        /// If the call has already finished normally (response stream has been fully read), doesn't do anything.
+        /// Otherwise, requests cancellation of the call which should terminate all pending async operations associated with the call.
+        /// As a result, all resources being used by the call should be released eventually.
+        /// </summary>
+        public void Dispose()
+        {
+            // TODO(jtattermusch): implement
+            throw new NotImplementedException();
+        }
     }
 }