Merge pull request #605 from rabbitmq/rabbitmq-java-client-528-log-warning-in-basic-cancel

 Log warning when calling Channel#basicCancel with unknown tag

Author: michaelklishin

src/main/java/com/rabbitmq/client/Channel.java

@@ -15,18 +15,14 @@
 
 package com.rabbitmq.client;
 
+import com.rabbitmq.client.AMQP.BasicProperties;
+import com.rabbitmq.client.AMQP.*;
+
 import java.io.IOException;
 import java.util.Map;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.TimeoutException;
 
-import com.rabbitmq.client.AMQP.BasicProperties;
-import com.rabbitmq.client.AMQP.Exchange;
-import com.rabbitmq.client.AMQP.Queue;
-import com.rabbitmq.client.AMQP.Tx;
-import com.rabbitmq.client.AMQP.Basic;
-import com.rabbitmq.client.AMQP.Confirm;
-
 /**
  * Interface to a channel. All non-deprecated methods of
  * this interface are part of the public API.
@@ -1220,8 +1216,11 @@ void basicNack(long deliveryTag, boolean multiple, boolean requeue)
     /**
      * Cancel a consumer. Calls the consumer's {@link Consumer#handleCancelOk}
      * method.
+     * <p>
+     * A consumer tag that does not match any consumer is ignored.
+     *
      * @param consumerTag a client- or server-generated consumer tag to establish context
-     * @throws IOException if an error is encountered, or if the consumerTag is unknown
+     * @throws IOException if an error is encountered
      * @see com.rabbitmq.client.AMQP.Basic.Cancel
      * @see com.rabbitmq.client.AMQP.Basic.CancelOk
      */

src/main/java/com/rabbitmq/client/impl/ChannelN.java

@@ -1472,8 +1472,10 @@ public void basicCancel(final String consumerTag)
         throws IOException
     {
         final Consumer originalConsumer = _consumers.get(consumerTag);
-        if (originalConsumer == null)
-            throw new IOException("Unknown consumerTag");
+        if (originalConsumer == null) {
+            LOGGER.warn("Tried to cancel consumer with unknown tag {}", consumerTag);
+            return;
+        }
 
         final Method m = new Basic.Cancel(consumerTag, false);
         BlockingRpcContinuation<Consumer> k = new BlockingRpcContinuation<Consumer>(m) {

src/test/java/com/rabbitmq/client/test/ChannelNTest.java

@@ -22,7 +22,6 @@
 import org.junit.Test;
 import org.mockito.Mockito;
 
-import java.io.IOException;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 
@@ -51,8 +50,8 @@ public void serverBasicCancelForUnknownConsumerDoesNotThrowException() throws Ex
         channel.processAsync(new AMQCommand(method));
     }
 
-    @Test(expected = IOException.class)
-    public void callingBasicCancelForUnknownConsumerThrowsException() throws Exception {
+    @Test
+    public void callingBasicCancelForUnknownConsumerDoesNotThrowException() throws Exception {
         AMQConnection connection = Mockito.mock(AMQConnection.class);
         ChannelN channel = new ChannelN(connection, 1, consumerWorkService);
         channel.basicCancel("does-not-exist");