Create a No-op stream in ClientCallImpl.start() if the Context has been cancelled.

core/src/main/java/io/grpc/inprocess/InProcessTransport.java

@@ -40,6 +40,7 @@ import io.grpc.internal.ClientStream;
 import io.grpc.internal.ClientStreamListener;
 import io.grpc.internal.ClientTransport;
 import io.grpc.internal.GrpcUtil;
+import io.grpc.internal.NoopClientStream;
 import io.grpc.internal.ServerStream;
 import io.grpc.internal.ServerStreamListener;
 import io.grpc.internal.ServerTransport;
@@ -452,41 +453,5 @@ class InProcessTransport implements ServerTransport, ClientTransport {
         // noop
       }
     }
-
-  }
-
-  private static class NoopClientStream implements ClientStream {
-    @Override
-    public void request(int numMessages) {}
-
-    @Override
-    public void writeMessage(InputStream message) {}
-
-    @Override
-    public void flush() {}
-
-    @Override
-    public boolean isReady() {
-      return false;
-    }
-
-    @Override
-    public void cancel(Status status) {}
-
-    @Override
-    public void halfClose() {}
-
-    @Override
-    public void setCompressor(Compressor c) {
-      // very much a nop
-    }
-
-    @Override
-    public void setDecompressionRegistry(DecompressorRegistry registry) {}
-
-    @Override
-    public void setMessageCompression(boolean enable) {
-      // noop
-    }
   }
 }

core/src/main/java/io/grpc/internal/ClientCallImpl.java

@@ -164,8 +164,9 @@ final class ClientCallImpl<ReqT, RespT> extends ClientCall<ReqT, RespT>
     Preconditions.checkState(stream == null, "Already started");
 
     if (context.isCancelled()) {
-      // Context is already cancelled so no need to create a stream, just notify the observer of
+      // Context is already cancelled so no need to create a real stream, just notify the observer
-      // cancellation via callback on the executor
+      // of cancellation via callback on the executor
+      stream = NoopClientStream.INSTANCE;
       callExecutor.execute(new ContextRunnable(context) {
         @Override
         public void runInContext() {

core/src/main/java/io/grpc/internal/DelayedStream.java

@@ -33,8 +33,6 @@ package io.grpc.internal;
 
 import static com.google.common.base.Preconditions.checkState;
 
-import com.google.common.annotations.VisibleForTesting;
-
 import io.grpc.Compressor;
 import io.grpc.DecompressorRegistry;
 import io.grpc.Metadata;
@@ -94,9 +92,9 @@ class DelayedStream implements ClientStream {
 
   /**
    * Creates a stream on a presumably usable transport. Must not be called if {@link
-   * cancelledPrematurely}, as there is no way to close {@code stream} without double-calling {@code
+   * #cancelledPrematurely}, as there is no way to close {@code stream} without double-calling
-   * listener}. Most callers of this method will need to acquire the intrinsic lock to check {@code
+   * {@code listener}. Most callers of this method will need to acquire the intrinsic lock to check
-   * cancelledPrematurely} and this method atomically.
+   * {@code cancelledPrematurely} and this method atomically.
    */
   void setStream(ClientStream stream) {
     synchronized (this) {
@@ -137,7 +135,7 @@ class DelayedStream implements ClientStream {
   void maybeClosePrematurely(final Status reason) {
     synchronized (this) {
       if (realStream == null) {
-        realStream = NOOP_CLIENT_STREAM;
+        realStream = NoopClientStream.INSTANCE;
         listener.closed(reason, new Metadata());
       }
     }
@@ -145,7 +143,7 @@ class DelayedStream implements ClientStream {
 
   public boolean cancelledPrematurely() {
     synchronized (this) {
-      return realStream == NOOP_CLIENT_STREAM;
+      return realStream == NoopClientStream.INSTANCE;
     }
   }
 
@@ -249,40 +247,4 @@ class DelayedStream implements ClientStream {
       }
     }
   }
-
-  @VisibleForTesting
-  static final ClientStream NOOP_CLIENT_STREAM = new ClientStream() {
-    @Override public void writeMessage(InputStream message) {}
-
-    @Override public void flush() {}
-
-    @Override public void cancel(Status reason) {}
-
-    @Override public void halfClose() {}
-
-    @Override public void request(int numMessages) {}
-
-    @Override public void setCompressor(Compressor c) {}
-
-    @Override
-    public void setMessageCompression(boolean enable) {
-      // noop
-    }
-
-    /**
-     * Always returns {@code false}, since this is only used when the startup of the {@link
-     * ClientCall} fails (i.e. the {@link ClientCall} is closed).
-     */
-    @Override public boolean isReady() {
-      return false;
-    }
-
-    @Override
-    public void setDecompressionRegistry(DecompressorRegistry registry) {}
-
-    @Override
-    public String toString() {
-      return "NOOP_CLIENT_STREAM";
-    }
-  };
 }

core/src/main/java/io/grpc/internal/NoopClientStream.java

@@ -0,0 +1,78 @@
+/*
+ * Copyright 2015, Google Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *    * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *    * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *
+ *    * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package io.grpc.internal;
+
+import io.grpc.Compressor;
+import io.grpc.DecompressorRegistry;
+import io.grpc.Status;
+
+import java.io.InputStream;
+
+/**
+ * An implementation of {@link ClientStream} that silently does nothing for the operations.
+ */
+public class NoopClientStream implements ClientStream {
+  public static NoopClientStream INSTANCE = new NoopClientStream();
+
+  @Override
+  public void request(int numMessages) {}
+
+  @Override
+  public void writeMessage(InputStream message) {}
+
+  @Override
+  public void flush() {}
+
+  @Override
+  public boolean isReady() {
+    return false;
+  }
+
+  @Override
+  public void cancel(Status status) {}
+
+  @Override
+  public void halfClose() {}
+
+  @Override
+  public void setCompressor(Compressor c) {
+    // very much a nop
+  }
+
+  @Override
+  public void setDecompressionRegistry(DecompressorRegistry registry) {}
+
+  @Override
+  public void setMessageCompression(boolean enable) {
+    // noop
+  }
+}

core/src/test/java/io/grpc/internal/ClientCallImplTest.java

@@ -425,6 +425,11 @@ public class ClientCallImplTest {
     assertEquals(Status.Code.CANCELLED, status.getCode());
     assertSame(cause, status.getCause());
 
+    // Following operations should be no-op.
+    call.request(1);
+    call.sendMessage(null);
+    call.halfClose();
+
     // Stream should never be created.
     verifyZeroInteractions(transport);
 
@@ -489,7 +494,7 @@ public class ClientCallImplTest {
     StreamCreationTask task =
         new StreamCreationTask(delayedStream, headers, method, CallOptions.DEFAULT, streamListener);
     when(clientTransport.newStream(method, headers, streamListener))
-        .thenReturn(DelayedStream.NOOP_CLIENT_STREAM);
+        .thenReturn(NoopClientStream.INSTANCE);
 
     task.onSuccess(clientTransport);