Implemented ClientCallStreamObserver.cancel()

2 files changed, 23 insertions, 0 deletions

diff --git a/stub/src/main/java/io/grpc/stub/ClientCallStreamObserver.java b/stub/src/main/java/io/grpc/stub/ClientCallStreamObserver.java
index 108dca71d..ca49ad57a 100644
--- a/stub/src/main/java/io/grpc/stub/ClientCallStreamObserver.java
+++ b/stub/src/main/java/io/grpc/stub/ClientCallStreamObserver.java
@@ -18,10 +18,28 @@ package io.grpc.stub;
 
 import io.grpc.ExperimentalApi;
 
+import javax.annotation.Nullable;
+
 /**
  * A refinement of {@link CallStreamObserver} that allows for lower-level interaction with
  * client calls.
  */
 @ExperimentalApi("https://github.com/grpc/grpc-java/issues/1788")
 public abstract class ClientCallStreamObserver<V> extends CallStreamObserver<V> {
+  /**
+   * Prevent any further processing for this {@code ClientCallStreamObserver}. No further messages
+   * will be received. The server is informed of cancellations, but may not stop processing the
+   * call. Cancelling an already
+   * {@code cancel()}ed {@code ClientCallStreamObserver} has no effect.
+   *
+   * <p>No other methods on this class can be called after this method has been called.
+   *
+   * <p>It is recommended that at least one of the arguments to be non-{@code null}, to provide
+   * useful debug information. Both argument being null may log warnings and result in suboptimal
+   * performance. Also note that the provided information will not be sent to the server.
+   *
+   * @param message if not {@code null}, will appear as the description of the CANCELLED status
+   * @param cause if not {@code null}, will appear as the cause of the CANCELLED status
+   */
+  public abstract void cancel(@Nullable String message, @Nullable Throwable cause);
 }
diff --git a/stub/src/main/java/io/grpc/stub/ClientCalls.java b/stub/src/main/java/io/grpc/stub/ClientCalls.java
index c4158cc6b..f26796ce0 100644
--- a/stub/src/main/java/io/grpc/stub/ClientCalls.java
+++ b/stub/src/main/java/io/grpc/stub/ClientCalls.java
@@ -326,6 +326,11 @@ public final class ClientCalls {
     public void setMessageCompression(boolean enable) {
       call.setMessageCompression(enable);
     }
+
+    @Override
+    public void cancel(@Nullable String message, @Nullable Throwable cause) {
+      call.cancel(message, cause);
+    }
   }
 
   private static final class StreamObserverToCallListenerAdapter<ReqT, RespT>