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Camel Component for Google Cloud Platform PubSub
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.camel.component.google.pubsub;
import java.io.IOException;
import java.util.LinkedList;
import java.util.List;
import java.util.concurrent.ExecutorService;
import com.google.api.core.AbstractApiService;
import com.google.cloud.pubsub.v1.MessageReceiver;
import com.google.cloud.pubsub.v1.Subscriber;
import com.google.cloud.pubsub.v1.stub.SubscriberStub;
import com.google.common.base.Strings;
import com.google.pubsub.v1.ProjectSubscriptionName;
import com.google.pubsub.v1.PubsubMessage;
import com.google.pubsub.v1.PullRequest;
import com.google.pubsub.v1.PullResponse;
import com.google.pubsub.v1.ReceivedMessage;
import org.apache.camel.Exchange;
import org.apache.camel.ExtendedExchange;
import org.apache.camel.Processor;
import org.apache.camel.component.google.pubsub.consumer.AcknowledgeSync;
import org.apache.camel.component.google.pubsub.consumer.CamelMessageReceiver;
import org.apache.camel.support.DefaultConsumer;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
class GooglePubsubConsumer extends DefaultConsumer {
private Logger localLog;
private final GooglePubsubEndpoint endpoint;
private final Processor processor;
private ExecutorService executor;
private List subscribers;
GooglePubsubConsumer(GooglePubsubEndpoint endpoint, Processor processor) throws Exception {
super(endpoint, processor);
this.endpoint = endpoint;
this.processor = processor;
this.subscribers = new LinkedList<>();
String loggerId = endpoint.getLoggerId();
if (Strings.isNullOrEmpty(loggerId)) {
loggerId = this.getClass().getName();
}
localLog = LoggerFactory.getLogger(loggerId);
}
@Override
protected void doStart() throws Exception {
super.doStart();
localLog.info("Starting Google PubSub consumer for {}/{}", endpoint.getProjectId(), endpoint.getDestinationName());
executor = endpoint.createExecutor();
for (int i = 0; i < endpoint.getConcurrentConsumers(); i++) {
executor.submit(new SubscriberWrapper());
}
}
@Override
protected void doStop() throws Exception {
super.doStop();
localLog.info("Stopping Google PubSub consumer for {}/{}", endpoint.getProjectId(), endpoint.getDestinationName());
if (subscribers != null && !subscribers.isEmpty()) {
localLog.info("Stopping subscribers for {}/{}", endpoint.getProjectId(), endpoint.getDestinationName());
subscribers.forEach(AbstractApiService::stopAsync);
}
if (executor != null) {
if (getEndpoint() != null && getEndpoint().getCamelContext() != null) {
getEndpoint().getCamelContext().getExecutorServiceManager().shutdownGraceful(executor);
} else {
executor.shutdownNow();
}
}
executor = null;
}
private class SubscriberWrapper implements Runnable {
@Override
public void run() {
try {
String subscriptionName = ProjectSubscriptionName.format(endpoint.getProjectId(), endpoint.getDestinationName());
if (localLog.isDebugEnabled()) {
localLog.debug("Subscribing to {}", subscriptionName);
}
if (endpoint.isSynchronousPull()) {
synchronousPull(subscriptionName);
} else {
asynchronousPull(subscriptionName);
}
localLog.debug("Exit run for subscription {}", subscriptionName);
} catch (Exception e) {
localLog.error("Failure getting messages from PubSub", e);
}
}
private void asynchronousPull(String subscriptionName) {
while (isRunAllowed() && !isSuspendingOrSuspended()) {
MessageReceiver messageReceiver = new CamelMessageReceiver(endpoint, processor);
Subscriber subscriber = endpoint.getComponent().getSubscriber(subscriptionName, messageReceiver);
try {
subscribers.add(subscriber);
subscriber.startAsync().awaitRunning();
subscriber.awaitTerminated();
} catch (Exception e) {
localLog.error("Failure getting messages from PubSub", e);
} finally {
localLog.debug("Stopping async subscriber {}", subscriptionName);
subscriber.stopAsync();
}
}
}
private void synchronousPull(String subscriptionName) {
while (isRunAllowed() && !isSuspendingOrSuspended()) {
try (SubscriberStub subscriber = endpoint.getComponent().getSubscriberStub()) {
PullRequest pullRequest = PullRequest.newBuilder()
.setMaxMessages(endpoint.getMaxMessagesPerPoll())
.setReturnImmediately(false)
.setSubscription(subscriptionName)
.build();
PullResponse pullResponse = subscriber.pullCallable().call(pullRequest);
for (ReceivedMessage message : pullResponse.getReceivedMessagesList()) {
PubsubMessage pubsubMessage = message.getMessage();
Exchange exchange = endpoint.createExchange();
exchange.getIn().setBody(pubsubMessage.getData().toByteArray());
exchange.getIn().setHeader(GooglePubsubConstants.ACK_ID, message.getAckId());
exchange.getIn().setHeader(GooglePubsubConstants.MESSAGE_ID, pubsubMessage.getMessageId());
exchange.getIn().setHeader(GooglePubsubConstants.PUBLISH_TIME, pubsubMessage.getPublishTime());
if (null != pubsubMessage.getAttributesMap()) {
exchange.getIn().setHeader(GooglePubsubConstants.ATTRIBUTES, pubsubMessage.getAttributesMap());
}
if (endpoint.getAckMode() != GooglePubsubConstants.AckMode.NONE) {
exchange.adapt(ExtendedExchange.class).addOnCompletion(new AcknowledgeSync(subscriber, subscriptionName));
}
try {
processor.process(exchange);
} catch (Throwable e) {
exchange.setException(e);
}
}
} catch (IOException e) {
localLog.error("Failure getting messages from PubSub", e);
}
}
}
}
}