Consumer
Consumer
Consumer与Name Server集群中的其中一个节点（随机选择）建立长连接，定期从Name Server取Topic路由信息，并向提供Topic服务的Master、Slave建立长连接，且定时向Master、Slave发送心跳。Consumer既可以从Master订阅消息，也可以从Slave订阅消息，订阅规则由Broker配置决定。 Consumer支持顺序消费和无序消费。
Consumer Group用来表示一组消费消息应用，一个Consumer Group下包含多个Consumer实例，可以是多台机器，也可以是多个进程，或者是一个进程的多个Consumer对象。一个Consumer Group下的多个Consumer以均摊方式消费消息，如果设置为广播方式，那么这个Consumer Group下的每个实例都消费全量数据。
DefaultMQPushConsumer
启动
public synchronized void start() throws MQClientException {
switch (this.serviceState) {
case CREATE_JUST:
log.info("the consumer [{}] start beginning. messageModel={}, isUnitMode={}", this.defaultMQPushConsumer.getConsumerGroup(),
this.defaultMQPushConsumer.getMessageModel(), this.defaultMQPushConsumer.isUnitMode());
this.serviceState = ServiceState.START_FAILED;
this.checkConfig();
this.copySubscription();
if (this.defaultMQPushConsumer.getMessageModel() == MessageModel.CLUSTERING) {
this.defaultMQPushConsumer.changeInstanceNameToPID();
}
//创建客户端实例，注册请求处理类ClientRemotingProcessor
this.mQClientFactory = MQClientManager.getInstance().getAndCreateMQClientInstance(this.defaultMQPushConsumer, this.rpcHook);
this.rebalanceImpl.setConsumerGroup(this.defaultMQPushConsumer.getConsumerGroup());
this.rebalanceImpl.setMessageModel(this.defaultMQPushConsumer.getMessageModel());
this.rebalanceImpl.setAllocateMessageQueueStrategy(this.defaultMQPushConsumer.getAllocateMessageQueueStrategy());
this.rebalanceImpl.setmQClientFactory(this.mQClientFactory);
this.pullAPIWrapper = new PullAPIWrapper(
mQClientFactory,
this.defaultMQPushConsumer.getConsumerGroup(), isUnitMode());
this.pullAPIWrapper.registerFilterMessageHook(filterMessageHookList);
if (this.defaultMQPushConsumer.getOffsetStore() != null) {
this.offsetStore = this.defaultMQPushConsumer.getOffsetStore();
} else {
switch (this.defaultMQPushConsumer.getMessageModel()) {
case BROADCASTING:
//将storePath目录下的offsets.json文件加载到内存
//也会将保存在内存中的偏移量数据持久化到offsets.json文件中
this.offsetStore = new LocalFileOffsetStore(this.mQClientFactory, this.defaultMQPushConsumer.getConsumerGroup());
break;
case CLUSTERING:
//根据topic将偏移量数据同步给指定broker，主从节点当中随机同步一个，默认
this.offsetStore = new RemoteBrokerOffsetStore(this.mQClientFactory, this.defaultMQPushConsumer.getConsumerGroup());
break;
default:
break;
}
this.defaultMQPushConsumer.setOffsetStore(this.offsetStore);
}
//加载偏移量
this.offsetStore.load();
if (this.getMessageListenerInner() instanceof MessageListenerOrderly) { //顺序消费
this.consumeOrderly = true;
this.consumeMessageService =
new ConsumeMessageOrderlyService(this, (MessageListenerOrderly) this.getMessageListenerInner());
} else if (this.getMessageListenerInner() instanceof MessageListenerConcurrently) { //立即消费，不保证顺序
this.consumeOrderly = false;
this.consumeMessageService =
new ConsumeMessageConcurrentlyService(this, (MessageListenerConcurrently) this.getMessageListenerInner());
}
//启动消费服务，实现消费消息
//ConsumeMessageConcurrentlyService:启动定时器，定期从队列中删除过期的消息
//ConsumeMessageOrderlyService:只能在集群模式启动，定期向broker主节点发送请求，锁住消息队列
this.consumeMessageService.start();
//将消费者信息保存到consumerTable
boolean registerOK = mQClientFactory.registerConsumer(this.defaultMQPushConsumer.getConsumerGroup(), this);
if (!registerOK) {
this.serviceState = ServiceState.CREATE_JUST;
this.consumeMessageService.shutdown();
throw new MQClientException("The consumer group[" + this.defaultMQPushConsumer.getConsumerGroup()
+ "] has been created before, specify another name please." + FAQUrl.suggestTodo(FAQUrl.GROUP_NAME_DUPLICATE_URL),
null);
}
mQClientFactory.start();
log.info("the consumer [{}] start OK.", this.defaultMQPushConsumer.getConsumerGroup());
this.serviceState = ServiceState.RUNNING;
break;
case RUNNING:
case START_FAILED:
case SHUTDOWN_ALREADY:
throw new MQClientException("The PushConsumer service state not OK, maybe started once, "
+ this.serviceState
+ FAQUrl.suggestTodo(FAQUrl.CLIENT_SERVICE_NOT_OK),
null);
default:
break;
}
//在name server中更新topic路由信息
this.updateTopicSubscribeInfoWhenSubscriptionChanged();
this.mQClientFactory.checkClientInBroker();
this.mQClientFactory.sendHeartbeatToAllBrokerWithLock();
this.mQClientFactory.rebalanceImmediately();
}客户端处理类
NettyClientHandler处理请求和响应。然后调用ClientRemotingProcessor执行具体操作。
public RemotingCommand processRequest(ChannelHandlerContext ctx,
RemotingCommand request) throws RemotingCommandException {
switch (request.getCode()) {
case RequestCode.CHECK_TRANSACTION_STATE: //执行自定义监听，向broker发送请求，结束事务
return this.checkTransactionState(ctx, request);
case RequestCode.NOTIFY_CONSUMER_IDS_CHANGED:
return this.notifyConsumerIdsChanged(ctx, request);
case RequestCode.RESET_CONSUMER_CLIENT_OFFSET:
return this.resetOffset(ctx, request);
case RequestCode.GET_CONSUMER_STATUS_FROM_CLIENT:
return this.getConsumeStatus(ctx, request);
case RequestCode.GET_CONSUMER_RUNNING_INFO:
return this.getConsumerRunningInfo(ctx, request);
case RequestCode.CONSUME_MESSAGE_DIRECTLY: //根据不同的消费模式（顺序消费与非顺序消费），消费消息，执行consumeMessage，返回消费状态
return this.consumeMessageDirectly(ctx, request);
default:
break;
}
return null;
}无序消费
public ConsumeMessageDirectlyResult consumeMessageDirectly(MessageExt msg, String brokerName) {
ConsumeMessageDirectlyResult result = new ConsumeMessageDirectlyResult();
//无序
result.setOrder(false);
result.setAutoCommit(true);
List<MessageExt> msgs = new ArrayList<MessageExt>();
msgs.add(msg);
MessageQueue mq = new MessageQueue();
mq.setBrokerName(brokerName);
mq.setTopic(msg.getTopic());
mq.setQueueId(msg.getQueueId());
ConsumeConcurrentlyContext context = new ConsumeConcurrentlyContext(mq);
this.resetRetryTopic(msgs);
final long beginTime = System.currentTimeMillis();
log.info("consumeMessageDirectly receive new message: {}", msg);
try {
//消费消息
ConsumeConcurrentlyStatus status = this.messageListener.consumeMessage(msgs, context);
if (status != null) {
switch (status) {
case CONSUME_SUCCESS:
result.setConsumeResult(CMResult.CR_SUCCESS);
break;
case RECONSUME_LATER: //延迟消费
result.setConsumeResult(CMResult.CR_LATER);
break;
default:
break;
}
} else {
result.setConsumeResult(CMResult.CR_RETURN_NULL);
}
} catch (Throwable e) {
result.setConsumeResult(CMResult.CR_THROW_EXCEPTION);
result.setRemark(RemotingHelper.exceptionSimpleDesc(e));
log.warn(String.format("consumeMessageDirectly exception: %s Group: %s Msgs: %s MQ: %s",
RemotingHelper.exceptionSimpleDesc(e),
ConsumeMessageConcurrentlyService.this.consumerGroup,
msgs,
mq), e);
}
result.setSpentTimeMills(System.currentTimeMillis() - beginTime);
log.info("consumeMessageDirectly Result: {}", result);
return result;
}有序消费
public ConsumeMessageDirectlyResult consumeMessageDirectly(MessageExt msg, String brokerName) {
ConsumeMessageDirectlyResult result = new ConsumeMessageDirectlyResult();
//有序
result.setOrder(true);
List<MessageExt> msgs = new ArrayList<MessageExt>();
msgs.add(msg);
MessageQueue mq = new MessageQueue();
mq.setBrokerName(brokerName);
mq.setTopic(msg.getTopic());
mq.setQueueId(msg.getQueueId());
ConsumeOrderlyContext context = new ConsumeOrderlyContext(mq);
final long beginTime = System.currentTimeMillis();
log.info("consumeMessageDirectly receive new message: {}", msg);
try {
//消费消息
ConsumeOrderlyStatus status = this.messageListener.consumeMessage(msgs, context);
if (status != null) {
switch (status) {
case COMMIT:
result.setConsumeResult(CMResult.CR_COMMIT);
break;
case ROLLBACK:
result.setConsumeResult(CMResult.CR_ROLLBACK);
break;
case SUCCESS:
result.setConsumeResult(CMResult.CR_SUCCESS);
break;
case SUSPEND_CURRENT_QUEUE_A_MOMENT:
result.setConsumeResult(CMResult.CR_LATER);
break;
default:
break;
}
} else {
result.setConsumeResult(CMResult.CR_RETURN_NULL);
}
} catch (Throwable e) {
result.setConsumeResult(CMResult.CR_THROW_EXCEPTION);
result.setRemark(RemotingHelper.exceptionSimpleDesc(e));
log.warn(String.format("consumeMessageDirectly exception: %s Group: %s Msgs: %s MQ: %s",
RemotingHelper.exceptionSimpleDesc(e),
ConsumeMessageOrderlyService.this.consumerGroup,
msgs,
mq), e);
}
result.setAutoCommit(context.isAutoCommit());
result.setSpentTimeMills(System.currentTimeMillis() - beginTime);
log.info("consumeMessageDirectly Result: {}", result);
return result;
}Last updated