Said ahead

Message Pull Processor

Source code analysis
Enter this method and find the mapping file according to offset, as described above at org. apache. rocketmq. store. MappedFileQueue # find MappedFileByOffset (long, boolean).

Return to this method and find the next mapping file based on offset, org.apache.rocketmq.store.CommitLog#rollNextFile

 public long rollNextFile(final long offset) {
        int mappedFileSize = this.defaultMessageStore.getMessageStoreConfig().getMapedFileSizeCommitLog();
        return offset + mappedFileSize - offset % mappedFileSize;
    }

Back to this method, the hook method that executes message consumption is org.apache.rocketmq.broker.processor.PullMessageProcessor#executeConsumeMessageHookBefore consuming the message

 public void executeConsumeMessageHookBefore(final ConsumeMessageContext context) {
        if (hasConsumeMessageHook()) {
            for (ConsumeMessageHook hook : this.consumeMessageHookList) {
                try {
//                    Users can implement their own hook method before consumption
                    hook.consumeMessageBefore(context);
                } catch (Throwable e) {
                }
            }
        }
    }

Back to this method, pause the message pull service, org. apache. rocketmq. broker. longpolling. PullRequestHoldService # suspend PullRequest

 public void suspendPullRequest(final String topic, final int queueId, final PullRequest pullRequest) {
        String key = this.buildKey(topic, queueId);
        ManyPullRequest mpr = this.pullRequestTable.get(key);
        if (null == mpr) {
            mpr = new ManyPullRequest();
            ManyPullRequest prev = this.pullRequestTable.putIfAbsent(key, mpr);
            if (prev != null) {
                mpr = prev;
            }
        }

        mpr.addPullRequest(pullRequest);
    }

Go back to this method and submit offset, org.apache.rocketmq.broker.offset.ConsumerOffsetManager#commitOffset(java.lang.String, java.lang.String, java.lang.String, int, long)

 public void commitOffset(final String clientHost, final String group, final String topic, final int queueId,
        final long offset) {
        // topic@group
        String key = topic + TOPIC_GROUP_SEPARATOR + group;
//        =>
        this.commitOffset(clientHost, key, queueId, offset);
    }

Enter this method, org.apache.rocketmq.broker.offset.ConsumerOffsetManager#commitOffset(java.lang.String, java.lang.String, int, long)

private void commitOffset(final String clientHost, final String key, final int queueId, final long offset) {
        ConcurrentMap<Integer, Long> map = this.offsetTable.get(key);
        if (null == map) {
            map = new ConcurrentHashMap<Integer, Long>(32);
            map.put(queueId, offset);
            this.offsetTable.put(key, map);
        } else {
            Long storeOffset = map.put(queueId, offset);
            if (storeOffset != null && offset < storeOffset) {
                log.warn("[NOTIFYME]update consumer offset less than store. clientHost={}, key={}, queueId={}, requestOffset={}, storeOffset={}", clientHost, key, queueId, offset, storeOffset);
            }
        }
    }

Back to this method, org. apache. rocketmq. broker. processor. PullMessageProcessor processRequest (io. netty. channel. Channel, org. apache. rocketmq. remoting. protocol. RemotingCommand, boolean) ends.

Said at the end
This analysis only represents personal views, for reference only.

Nail Technology Group