fix: ensure all publishes complete before shutting down publisher (#76)

* Modifying Publish example in README to match other examples given, and fix issue #6784 * fix: Modifying Publish example in README to match other examples, and fix Issue #11 * feat: Adding support for DLQs Adding delivery attempt count to PubsubMessages as a message attribute, and creating helper function to allow users to get the count without knowing implementation details. * Fix formatting * fix: making changes requested in pull request * fix: creating fix to not populate delivery attempt attribute when dead lettering is not enabled * Adding unit test for case in which a received message has no delivery attempt * Making MessageWaiter class more generic to also be used for outstanding ack operations * Waiting for acks to complete before shutting down a streaming subscriber connection * Fixing formatting error * fix: making sure all publishes complete before shutting down the publisher

Author: hannahrogers-google

google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/v1/Publisher.java

@@ -527,6 +527,7 @@ public void shutdown() {
  currentAlarmFuture.cancel(false);
  }
  publishAllOutstanding();
+ messagesWaiter.waitComplete();
  backgroundResources.shutdown();
  }
 

google-cloud-pubsub/src/test/java/com/google/cloud/pubsub/v1/PublisherImplTest.java

@@ -195,6 +195,37 @@ public void testSinglePublishByNumBytes() throws Exception {
  publisher.awaitTermination(1, TimeUnit.MINUTES);
  }
 
+ @Test
+ public void testPublishByShutdown() throws Exception {
+ Publisher publisher =
+ getTestPublisherBuilder()
+ .setBatchingSettings(
+ Publisher.Builder.DEFAULT_BATCHING_SETTINGS
+ .toBuilder()
+ .setDelayThreshold(Duration.ofSeconds(100))
+ .setElementCountThreshold(10L)
+ .build())
+ .build();
+
+ testPublisherServiceImpl.addPublishResponse(
+ PublishResponse.newBuilder().addMessageIds("1").addMessageIds("2"));
+
+ ApiFuture<String> publishFuture1 = sendTestMessage(publisher, "A");
+ ApiFuture<String> publishFuture2 = sendTestMessage(publisher, "B");
+
+ // Note we are not advancing time or reaching the count threshold but messages should
+ // still get published by call to shutdown
+
+ publisher.shutdown();
+ publisher.awaitTermination(1, TimeUnit.MINUTES);
+
+ // Verify the publishes completed
+ assertTrue(publishFuture1.isDone());
+ assertTrue(publishFuture2.isDone());
+ assertEquals("1", publishFuture1.get());
+ assertEquals("2", publishFuture2.get());
+ }
+
  @Test
  public void testPublishMixedSizeAndDuration() throws Exception {
  Publisher publisher =