聊聊BinlogConnectorReplicator的work

序

本文主要研究一下BinlogConnectorReplicator的work

StoppableTask

maxwell-1.25.1/src/main/java/com/zendesk/maxwell/util/StoppableTask.java

public interface StoppableTask {
	void requestStop() throws Exception;
	void awaitStop(Long timeout) throws TimeoutException;
}

• StoppableTask接口定义了requestStop、awaitStop方法

RunLoopProcess

maxwell-1.25.1/src/main/java/com/zendesk/maxwell/util/RunLoopProcess.java

abstract public class RunLoopProcess implements StoppableTask {
	protected volatile StoppableTaskState taskState;
	private Thread thread;

	public RunLoopProcess() {
		this.taskState = new StoppableTaskState(this.getClass().getName());
	}

	public void requestStop() {
		this.taskState.requestStop();

		interrupt();
	}

	public void interrupt() {
		if ( this.thread != null )
			this.thread.interrupt();
	}

	public void awaitStop(Long timeout) throws TimeoutException {
		this.taskState.awaitStop(thread, timeout);
	}

	public void runLoop() throws Exception {
		this.thread = Thread.currentThread();
		this.beforeStart();

		try {
			while (this.taskState.isRunning()) {
				work();
			}
		} finally {
			this.beforeStop();
			this.taskState.stopped();
		}
	}

	protected abstract void work() throws Exception;
	protected void beforeStart() throws Exception { }
	protected void beforeStop() throws Exception { }
}

• RunLoopProcess实现了StoppableTask接口，其runLoop方法会通过while循环不断执行work()方法，直到taskState.isRunning()为false

BinlogConnectorReplicator

maxwell-1.25.1/src/main/java/com/zendesk/maxwell/replication/BinlogConnectorReplicator.java

public class BinlogConnectorReplicator extends RunLoopProcess implements Replicator {

	//......

	public void work() throws Exception {
		RowMap row = null;
		try {
			row = getRow();
		} catch ( InterruptedException e ) {
		}

		if ( row == null )
			return;

		rowCounter.inc();
		rowMeter.mark();

		if ( scripting != null && !isMaxwellRow(row))
			scripting.invoke(row);

		processRow(row);
	}

	protected void processRow(RowMap row) throws Exception {
		if ( row instanceof HeartbeatRowMap) {
			producer.push(row);
			if (stopAtHeartbeat != null) {
				long thisHeartbeat = row.getPosition().getLastHeartbeatRead();
				if (thisHeartbeat >= stopAtHeartbeat) {
					LOGGER.info("received final heartbeat " + thisHeartbeat + "; stopping replicator");
					// terminate runLoop
					this.taskState.stopped();
				}
			}
		} else if ( !shouldSkipRow(row) )
			producer.push(row);
	}

	//......

}

• BinlogConnectorReplicator实现了RunLoopProcess接口，其work方法通过getRow()获取RowMap，若不为null则执行processRow(row)方法；processRow方法则执行producer.push(row)

AbstractProducer

maxwell-1.25.1/src/main/java/com/zendesk/maxwell/producer/AbstractProducer.java

public abstract class AbstractProducer {
	protected final MaxwellContext context;
	protected final MaxwellOutputConfig outputConfig;
	protected final Counter succeededMessageCount;
	protected final Meter succeededMessageMeter;
	protected final Counter failedMessageCount;
	protected final Meter failedMessageMeter;
	protected final Timer messagePublishTimer;
	protected final Timer messageLatencyTimer;
	protected final Counter messageLatencySloViolationCount;

	public AbstractProducer(MaxwellContext context) {
		this.context = context;
		this.outputConfig = context.getConfig().outputConfig;

		Metrics metrics = context.getMetrics();
		MetricRegistry metricRegistry = metrics.getRegistry();

		this.succeededMessageCount = metricRegistry.counter(metrics.metricName("messages", "succeeded"));
		this.succeededMessageMeter = metricRegistry.meter(metrics.metricName("messages", "succeeded", "meter"));
		this.failedMessageCount = metricRegistry.counter(metrics.metricName("messages", "failed"));
		this.failedMessageMeter = metricRegistry.meter(metrics.metricName("messages", "failed", "meter"));
		this.messagePublishTimer = metricRegistry.timer(metrics.metricName("message", "publish", "time"));
		this.messageLatencyTimer = metricRegistry.timer(metrics.metricName("message", "publish", "age"));
		this.messageLatencySloViolationCount = metricRegistry.counter(metrics.metricName("message", "publish", "age", "slo_violation"));
	}

	abstract public void push(RowMap r) throws Exception;

	public StoppableTask getStoppableTask() {
		return null;
	}

	public Meter getFailedMessageMeter() {
		return this.failedMessageMeter;
	}

	public MaxwellDiagnostic getDiagnostic() {
		return null;
	}
}

• AbstractProducer定义了push抽象方法供子类实现

StdoutProducer

maxwell-1.25.1/src/main/java/com/zendesk/maxwell/producer/StdoutProducer.java

public class StdoutProducer extends AbstractProducer {
	public StdoutProducer(MaxwellContext context) {
		super(context);
	}

	@Override
	public void push(RowMap r) throws Exception {
		String output = r.toJSON(outputConfig);

		if ( output != null && r.shouldOutput(outputConfig) )
			System.out.println(output);

		this.context.setPosition(r);
	}
}

• StdoutProducer继承了AbstractProducer，其push方法则执行System.out.println(output)以及context.setPosition(r)

小结

StoppableTask接口定义了requestStop、awaitStop方法；RunLoopProcess实现了StoppableTask接口，其runLoop方法会通过while循环不断执行work()方法，直到taskState.isRunning()为false；BinlogConnectorReplicator实现了RunLoopProcess接口，其work方法通过getRow()获取RowMap，若不为null则执行processRow(row)方法；processRow方法则执行producer.push(row)

doc

• BinlogConnectorReplicator