Class Publisher
- All Implemented Interfaces:
PublisherInterface
A Publisher
provides built-in capabilities to automatically handle batching of
messages, controlling memory utilization, and retrying API calls on transient errors.
With customizable options that control:
- Message batching: such as number of messages or max batch byte size.
- Retries: such as the maximum duration of retries for a failing batch of messages.
Publisher
will use the credentials set on the channel, which uses application default
credentials through GoogleCredentials.getApplicationDefault()
by default.
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Nested Class Summary
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Method Summary
Modifier and TypeMethodDescriptionboolean
awaitTermination
(long duration, TimeUnit unit) Wait for all work has completed execution after ashutdown()
request, or the timeout occurs, or the current thread is interrupted.static long
The maximum size of one request.static long
The maximum number of messages in one request.com.google.api.gax.batching.BatchingSettings
The batching settings configured on thisPublisher
.Topic which the publisher publishes to.Topic which the publisher publishes to.static Publisher.Builder
newBuilder
(TopicName topicName) Constructs a newPublisher.Builder
using the given topic.static Publisher.Builder
newBuilder
(String topicName) Constructs a newPublisher.Builder
using the given topic.com.google.api.core.ApiFuture<String>
publish
(PubsubMessage message) Schedules the publishing of a message.void
Publish any outstanding batches if non-empty.void
resumePublish
(String key) There may be non-recoverable problems with a request for an ordering key.void
shutdown()
Schedules immediate publishing of any outstanding messages and waits until all are processed.
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Method Details
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getApiMaxRequestElementCount
public static long getApiMaxRequestElementCount()The maximum number of messages in one request. Defined by the API. -
getApiMaxRequestBytes
public static long getApiMaxRequestBytes()The maximum size of one request. Defined by the API. -
getTopicName
Topic which the publisher publishes to. -
getTopicNameString
Topic which the publisher publishes to. -
publish
Schedules the publishing of a message. The publishing of the message may occur immediately or be delayed based on the publisher batching options.This method blocks in the downcall if using LimitExceededBehavior.Block in the flow control settings.
Example of publishing a message.
String message = "my_message"; ByteString data = ByteString.copyFromUtf8(message); PubsubMessage pubsubMessage = PubsubMessage.newBuilder().setData(data).build(); ApiFuture<String> messageIdFuture = publisher.publish(pubsubMessage); ApiFutures.addCallback(messageIdFuture, new ApiFutureCallback<String>() { public void onSuccess(String messageId) { System.out.println("published with message id: " + messageId); } public void onFailure(Throwable t) { System.out.println("failed to publish: " + t); } }, MoreExecutors.directExecutor());
- Specified by:
publish
in interfacePublisherInterface
- Parameters:
message
- the message to publish.- Returns:
- the message ID wrapped in a future.
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resumePublish
There may be non-recoverable problems with a request for an ordering key. In that case, all subsequent requests will fail until this method is called. If the key is not currently paused, calling this method will be a no-op.- Parameters:
key
- The key for which to resume publishing.
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publishAllOutstanding
public void publishAllOutstanding()Publish any outstanding batches if non-empty. This method sends buffered messages, but does not wait for the send operations to complete. To wait for messages to send, callget
on the futures returned frompublish
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getBatchingSettings
public com.google.api.gax.batching.BatchingSettings getBatchingSettings()The batching settings configured on thisPublisher
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shutdown
public void shutdown()Schedules immediate publishing of any outstanding messages and waits until all are processed.Sends remaining outstanding messages and prevents future calls to publish. This method should be invoked prior to deleting the
Publisher
object in order to ensure that no pending messages are lost. -
awaitTermination
Wait for all work has completed execution after ashutdown()
request, or the timeout occurs, or the current thread is interrupted.Call this method to make sure all resources are freed properly.
- Throws:
InterruptedException
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newBuilder
Constructs a newPublisher.Builder
using the given topic.Example of creating a
Publisher
.String projectName = "my_project"; String topicName = "my_topic"; ProjectTopicName topic = ProjectTopicName.create(projectName, topicName); Publisher publisher = Publisher.newBuilder(topic).build(); try { // ... } finally { // When finished with the publisher, make sure to shutdown to free up resources. publisher.shutdown(); publisher.awaitTermination(1, TimeUnit.MINUTES); }
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newBuilder
Constructs a newPublisher.Builder
using the given topic.Example of creating a
Publisher
.String topic = "projects/my_project/topics/my_topic"; Publisher publisher = Publisher.newBuilder(topic).build(); try { // ... } finally { // When finished with the publisher, make sure to shutdown to free up resources. publisher.shutdown(); publisher.awaitTermination(1, TimeUnit.MINUTES); }
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