feat: add consume message process (#123)

* Add ConsumeMessage process
2 years ago · 9e4f4dad04
parent ab8f436b66
commit 9e4f4dad04
2 changed files with 221 additions and 0 deletions
--- a/README.md
+++ b/README.md
@ -284,6 +284,7 @@
 - [RocketMQ 消费者启动流程](docs/rocketmq/rocketmq-consumer-start.md)
 - [RocketMQ 消息拉取流程](docs/rocketmq/rocketmq-pullmessage.md)
 - [RocketMQ Broker 处理拉取消息请求流程](docs/rocketmq/rocketmq-pullmessage-processor.md)
+- [RocketMQ 消息消费流程](docs/rocketmq/rocketmq-consume-message-process.md)

 ## 番外篇（JDK 1.8）

--- a/docs/rocketmq/rocketmq-consume-message-process.md
+++ b/docs/rocketmq/rocketmq-consume-message-process.md
@ -0,0 +1,220 @@
+该文所涉及的 RocketMQ 源码版本为 4.9.3。
+
+# RocketMQ 消息消费流程
+
+拉取消息 成功之后 会调用 org.apache.rocketmq.client.impl.consumer.ConsumeMessageConcurrentlyService#submitConsumeRequest 组装 消费消息 请求
+
+获取 consumeMessageBatchMaxSize,表示一个 ConsumeRequest 包含的消息 数量，默认为 1
+
+入参 msgs 为拉取消息的最大值，默认为 32
+
+如果 msgs 小于等于 consumeMessageBatchMaxSize，直接创建`ConsumeRequest`任务并提交到 线程池，当出现`RejectedExecutionException`异常时会重新提交任务，但是查看线程池的队列
+
+`this.consumeRequestQueue = new LinkedBlockingQueue<Runnable>();`
+
+为无界队列，最大值为`Integer.MAX_VALUE`，理论上不会出现该异常
+
+```java
+if (msgs.size() <= consumeBatchSize) {
+    ConsumeRequest consumeRequest = new ConsumeRequest(msgs, processQueue, messageQueue);
+    try {
+        this.consumeExecutor.submit(consumeRequest);
+    } catch (RejectedExecutionException e) {
+        this.submitConsumeRequestLater(consumeRequest);
+    }
+}
+```
+
+如果 msgs 大于 consumeMessageBatchMaxSize，消息分批处理，即创建多个`ConsumeRequest`任务
+
+```java
+for (int total = 0; total < msgs.size(); ) {
+    List<MessageExt> msgThis = new ArrayList<MessageExt>(consumeBatchSize);
+    for (int i = 0; i < consumeBatchSize; i++, total++) {
+        if (total < msgs.size()) {
+            msgThis.add(msgs.get(total));
+        } else {
+            break;
+        }
+    }
+
+    ConsumeRequest consumeRequest = new ConsumeRequest(msgThis, processQueue, messageQueue);
+    try {
+        this.consumeExecutor.submit(consumeRequest);
+    } catch (RejectedExecutionException e) {
+        for (; total < msgs.size(); total++) {
+            msgThis.add(msgs.get(total));
+        }
+
+        this.submitConsumeRequestLater(consumeRequest);
+    }
+}
+```
+
+`class ConsumeRequest implements Runnable`
+
+详细的消费逻辑查看 org.apache.rocketmq.client.impl.consumer.ConsumeMessageConcurrentlyService.ConsumeRequest#run
+
+第 1 步：首先会校验队列的 dropped 是否为 true，当队列重平衡的时候，该队列可能会被分配给其他消费者，如果该队列被分配给其他消费者，会设置 dropped 为 true
+
+```java
+if (this.processQueue.isDropped()) {
+    log.info("the message queue not be able to consume, because it's dropped. group={} {}", ConsumeMessageConcurrentlyService.this.consumerGroup, this.messageQueue);
+    return;
+}
+```
+
+第 2 步：如果是重试消息重新设置主题
+
+```java
+public void resetRetryAndNamespace(final List<MessageExt> msgs, String consumerGroup) {
+    final String groupTopic = MixAll.getRetryTopic(consumerGroup);
+    for (MessageExt msg : msgs) {
+        String retryTopic = msg.getProperty(MessageConst.PROPERTY_RETRY_TOPIC);
+        if (retryTopic != null && groupTopic.equals(msg.getTopic())) {
+            msg.setTopic(retryTopic);
+        }
+
+        if (StringUtils.isNotEmpty(this.defaultMQPushConsumer.getNamespace())) {
+            msg.setTopic(NamespaceUtil.withoutNamespace(msg.getTopic(), this.defaultMQPushConsumer.getNamespace()));
+        }
+    }
+}
+```
+
+第 3 步：如果有钩子函数则执行
+
+```java
+if (ConsumeMessageConcurrentlyService.this.defaultMQPushConsumerImpl.hasHook()) {
+    consumeMessageContext = new ConsumeMessageContext();
+    consumeMessageContext.setNamespace(defaultMQPushConsumer.getNamespace());
+    consumeMessageContext.setConsumerGroup(defaultMQPushConsumer.getConsumerGroup());
+    consumeMessageContext.setProps(new HashMap<String, String>());
+    consumeMessageContext.setMq(messageQueue);
+    consumeMessageContext.setMsgList(msgs);
+    consumeMessageContext.setSuccess(false);
+    ConsumeMessageConcurrentlyService.this.defaultMQPushConsumerImpl.executeHookBefore(consumeMessageContext);
+}
+```
+
+第 4 步：调用消息监听器的`consumeMessage执行具体的消费逻辑` ，返回值为`ConsumeConcurrentlyStatus`
+
+```java
+try {
+    if (msgs != null && !msgs.isEmpty()) {
+        for (MessageExt msg : msgs) {
+            MessageAccessor.setConsumeStartTimeStamp(msg, String.valueOf(System.currentTimeMillis()));
+        }
+    }
+    status = listener.consumeMessage(Collections.unmodifiableList(msgs), context);
+} catch (Throwable e) {
+        log.warn(String.format("consumeMessage exception: %s Group: %s Msgs: %s MQ: %s",
+        RemotingHelper.exceptionSimpleDesc(e),
+        ConsumeMessageConcurrentlyService.this.consumerGroup,
+        msgs,
+        messageQueue), e);
+    hasException = true;
+}
+```
+
+```java
+public enum ConsumeConcurrentlyStatus {
+    /**
+     * Success consumption
+     */
+    CONSUME_SUCCESS,
+    /**
+     * Failure consumption,later try to consume
+     */
+    RECONSUME_LATER;
+}
+
+```
+
+第 5 步：如果有 钩子 函数执行钩子
+
+```java
+if (ConsumeMessageConcurrentlyService.this.defaultMQPushConsumerImpl.hasHook()) {
+    consumeMessageContext.setStatus(status.toString());
+    consumeMessageContext.setSuccess(ConsumeConcurrentlyStatus.CONSUME_SUCCESS== status);
+    ConsumeMessageConcurrentlyService.this.defaultMQPushConsumerImpl.executeHookAfter(consumeMessageContext);
+}
+```
+
+第 6 步：再次校验队列 的 dropped 状态 ，如果为 false 才会对结果进行处理
+
+```java
+if (!processQueue.isDropped()) {
+    ConsumeMessageConcurrentlyService.this.processConsumeResult(status, context, this);
+} else {
+    log.warn("processQueue is dropped without process consume result. messageQueue={}, msgs={}", messageQueue, msgs);
+}
+```
+
+org.apache.rocketmq.client.impl.consumer.ConsumeMessageConcurrentlyService#processConsumeResult
+
+第 7 步：计算 ackIndex，如果为`CONSUME_SUCCESS`等于`consumeRequest.getMsgs().size() - 1;`
+
+如果为`RECONSUME_LATER`等于-1
+
+```java
+switch (status) {
+    caseCONSUME_SUCCESS:
+        if (ackIndex >= consumeRequest.getMsgs().size()) {
+            ackIndex = consumeRequest.getMsgs().size() - 1;
+        }
+        int ok = ackIndex + 1;
+        int failed = consumeRequest.getMsgs().size() - ok;
+        this.getConsumerStatsManager().incConsumeOKTPS(consumerGroup, consumeRequest.getMessageQueue().getTopic(), ok);
+        this.getConsumerStatsManager().incConsumeFailedTPS(consumerGroup, consumeRequest.getMessageQueue().getTopic(), failed);
+        break;
+    caseRECONSUME_LATER:
+        ackIndex = -1;
+        this.getConsumerStatsManager().incConsumeFailedTPS(consumerGroup, consumeRequest.getMessageQueue().getTopic(),
+            consumeRequest.getMsgs().size());
+        break;
+    default:
+        break;
+}
+```
+
+第 8 步：如果是广播模式并且是消费失败，打印警告 信息，如果是集群模式并且消费失败会将消息发送到 broker，如果发送失败将消息封装到 consumerRequest 中延迟消费
+
+```java
+switch (this.defaultMQPushConsumer.getMessageModel()) {
+    caseBROADCASTING:
+        for (int i = ackIndex + 1; i < consumeRequest.getMsgs().size(); i++) {
+            MessageExt msg = consumeRequest.getMsgs().get(i);
+            log.warn("BROADCASTING, the message consume failed, drop it, {}", msg.toString());
+        }
+        break;
+    caseCLUSTERING:
+        List<MessageExt> msgBackFailed = new ArrayList<MessageExt>(consumeRequest.getMsgs().size());
+        for (int i = ackIndex + 1; i < consumeRequest.getMsgs().size(); i++) {
+            MessageExt msg = consumeRequest.getMsgs().get(i);
+            boolean result = this.sendMessageBack(msg, context);
+            if (!result) {
+                msg.setReconsumeTimes(msg.getReconsumeTimes() + 1);
+                msgBackFailed.add(msg);
+            }
+        }
+
+        if (!msgBackFailed.isEmpty()) {
+            consumeRequest.getMsgs().removeAll(msgBackFailed);
+
+            this.submitConsumeRequestLater(msgBackFailed, consumeRequest.getProcessQueue(), consumeRequest.getMessageQueue());
+        }
+        break;
+    default:
+        break;
+}
+```
+
+第 9 步：更新消息消费偏移量
+
+```java
+long offset = consumeRequest.getProcessQueue().removeMessage(consumeRequest.getMsgs());
+if (offset >= 0 && !consumeRequest.getProcessQueue().isDropped()) {
+    this.defaultMQPushConsumerImpl.getOffsetStore().updateOffset(consumeRequest.getMessageQueue(), offset, true);
+}
+```