聊聊rocketmq-mysql的Replicator

序

本文主要研究一下rocketmq-mysql的Replicator

Replicator

rocketmq-externals/rocketmq-mysql/src/main/java/org/apache/rocketmq/mysql/Replicator.java

public class Replicator {

    private static final Logger LOGGER = LoggerFactory.getLogger(Replicator.class);

    private static final Logger POSITION_LOGGER = LoggerFactory.getLogger("PositionLogger");

    private Config config;

    private EventProcessor eventProcessor;

    private RocketMQProducer rocketMQProducer;

    private Object lock = new Object();
    private BinlogPosition nextBinlogPosition;
    private long nextQueueOffset;
    private long xid;

    public static void main(String[] args) {

        Replicator replicator = new Replicator();
        replicator.start();
    }

    public void start() {

        try {
            config = new Config();
            config.load();

            rocketMQProducer = new RocketMQProducer(config);
            rocketMQProducer.start();

            BinlogPositionLogThread binlogPositionLogThread = new BinlogPositionLogThread(this);
            binlogPositionLogThread.start();

            eventProcessor = new EventProcessor(this);
            eventProcessor.start();

        } catch (Exception e) {
            LOGGER.error("Start error.", e);
            System.exit(1);
        }
    }

    public void commit(Transaction transaction, boolean isComplete) {

        String json = transaction.toJson();

        for (int i = 0; i < 3; i++) {
            try {
                if (isComplete) {
                    long offset = rocketMQProducer.push(json);

                    synchronized (lock) {
                        xid = transaction.getXid();
                        nextBinlogPosition = transaction.getNextBinlogPosition();
                        nextQueueOffset = offset;
                    }

                } else {
                    rocketMQProducer.push(json);
                }
                break;

            } catch (Exception e) {
                LOGGER.error("Push error,retry:" + (i + 1) + ",", e);
            }
        }
    }

    public void logPosition() {

        String binlogFilename = null;
        long xid = 0L;
        long nextPosition = 0L;
        long nextOffset = 0L;

        synchronized (lock) {
            if (nextBinlogPosition != null) {
                xid = this.xid;
                binlogFilename = nextBinlogPosition.getBinlogFilename();
                nextPosition = nextBinlogPosition.getPosition();
                nextOffset = nextQueueOffset;
            }
        }

        if (binlogFilename != null) {
            POSITION_LOGGER.info("XID: {},   BINLOG_FILE: {},   NEXT_POSITION: {},   NEXT_OFFSET: {}",
                xid, binlogFilename, nextPosition, nextOffset);
        }

    }

    public Config getConfig() {
        return config;
    }

    public BinlogPosition getNextBinlogPosition() {
        return nextBinlogPosition;
    }

}

• Replicator提供了start、commit、logPosition方法；start方法会创建RocketMQProducer、BinlogPositionLogThread及EventProcessor，然后执行其start方法；commit方法会通过rocketMQProducer将transaction.toJson()发送出去，对于isComplete为true的会更新xid、nextBinlogPosition、nextQueueOffset；logPosition方法会打印binlogFilename、nextPosition、nextOffset

RocketMQProducer

rocketmq-externals/rocketmq-mysql/src/main/java/org/apache/rocketmq/mysql/productor/RocketMQProducer.java

public class RocketMQProducer {
    private static final Logger LOGGER = LoggerFactory.getLogger(RocketMQProducer.class);

    private DefaultMQProducer producer;
    private Config config;

    public RocketMQProducer(Config config) {
        this.config = config;
    }

    public void start() throws MQClientException {
        producer = new DefaultMQProducer("BINLOG_PRODUCER_GROUP");
        producer.setNamesrvAddr(config.mqNamesrvAddr);
        producer.start();
    }

    public long push(String json) throws Exception {
        LOGGER.debug(json);

        Message message = new Message(config.mqTopic, json.getBytes("UTF-8"));
        SendResult sendResult = producer.send(message);

        return sendResult.getQueueOffset();
    }
}

• RocketMQProducer的start方法创建DefaultMQProducer并执行其start方法；其push方法则通过producer.send(message)发送消息，并返回sendResult.getQueueOffset()

BinlogPositionLogThread

rocketmq-externals/rocketmq-mysql/src/main/java/org/apache/rocketmq/mysql/position/BinlogPositionLogThread.java

public class BinlogPositionLogThread extends Thread {
    private Logger logger = LoggerFactory.getLogger(BinlogPositionLogThread.class);

    private Replicator replicator;

    public BinlogPositionLogThread(Replicator replicator) {
        this.replicator = replicator;
        setDaemon(true);
    }

    @Override
    public void run() {

        while (true) {
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                logger.error("Offset thread interrupted.", e);
            }

            replicator.logPosition();
        }
    }
}

• BinlogPositionLogThread会定时执行replicator.logPosition()来打印position信息

小结

Replicator提供了start、commit、logPosition方法；start方法会创建RocketMQProducer、BinlogPositionLogThread及EventProcessor，然后执行其start方法；commit方法会通过rocketMQProducer将transaction.toJson()发送出去，对于isComplete为true的会更新xid、nextBinlogPosition、nextQueueOffset；logPosition方法会打印binlogFilename、nextPosition、nextOffset

doc

• Replicator