RocketMQTransactionAnnotationProcessor的原理和用法

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序

本文主要研究一下RocketMQTransactionAnnotationProcessor

RocketMQTransactionAnnotationProcessor

rocketmq-spring-boot-2.0.3-sources.jar!/org/apache/rocketmq/spring/config/RocketMQTransactionAnnotationProcessor.java

public class RocketMQTransactionAnnotationProcessor
    implements BeanPostProcessor, Ordered, ApplicationContextAware {
    private final static Logger log = LoggerFactory.getLogger(RocketMQTransactionAnnotationProcessor.class);

    private ApplicationContext applicationContext;
    private final Set<Class<?>> nonProcessedClasses =
        Collections.newSetFromMap(new ConcurrentHashMap<Class<?>, Boolean>(64));

    private TransactionHandlerRegistry transactionHandlerRegistry;

    public RocketMQTransactionAnnotationProcessor(TransactionHandlerRegistry transactionHandlerRegistry) {
        this.transactionHandlerRegistry = transactionHandlerRegistry;
    }

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext = applicationContext;
    }

    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        return bean;
    }

    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        if (!this.nonProcessedClasses.contains(bean.getClass())) {
            Class<?> targetClass = AopUtils.getTargetClass(bean);
            RocketMQTransactionListener listener = AnnotationUtils.findAnnotation(targetClass, RocketMQTransactionListener.class);
            this.nonProcessedClasses.add(bean.getClass());
            if (listener == null) { // for quick search
                log.trace("No @RocketMQTransactionListener annotations found on bean type: {}", bean.getClass());
            } else {
                try {
                    processTransactionListenerAnnotation(listener, bean);
                } catch (MQClientException e) {
                    log.error("Failed to process annotation " + listener, e);
                    throw new BeanCreationException("Failed to process annotation " + listener, e);
                }
            }
        }

        return bean;
    }

    private void processTransactionListenerAnnotation(RocketMQTransactionListener listener, Object bean)
        throws MQClientException {
        if (transactionHandlerRegistry == null) {
            throw new MQClientException("Bad usage of @RocketMQTransactionListener, " +
                "the class must work with RocketMQTemplate", null);
        }
        if (!RocketMQLocalTransactionListener.class.isAssignableFrom(bean.getClass())) {
            throw new MQClientException("Bad usage of @RocketMQTransactionListener, " +
                "the class must implement interface RocketMQLocalTransactionListener",
                null);
        }
        TransactionHandler transactionHandler = new TransactionHandler();
        transactionHandler.setBeanFactory(this.applicationContext.getAutowireCapableBeanFactory());
        transactionHandler.setName(listener.txProducerGroup());
        transactionHandler.setBeanName(bean.getClass().getName());
        transactionHandler.setListener((RocketMQLocalTransactionListener) bean);
        transactionHandler.setCheckExecutor(listener.corePoolSize(), listener.maximumPoolSize(),
                listener.keepAliveTime(), listener.blockingQueueSize());

        RPCHook rpcHook = RocketMQUtil.getRPCHookByAkSk(applicationContext.getEnvironment(),
            listener.accessKey(), listener.secretKey());

        if (Objects.nonNull(rpcHook)) {
            transactionHandler.setRpcHook(rpcHook);
        } else {
            log.debug("Access-key or secret-key not configure in " + listener + ".");
        }

        transactionHandlerRegistry.registerTransactionHandler(transactionHandler);
    }

    @Override
    public int getOrder() {
        return LOWEST_PRECEDENCE;
    }

}

• RocketMQTransactionAnnotationProcessor实现了BeanPostProcessor, Ordered, ApplicationContextAware接口

• postProcessAfterInitialization方法会查找标记有RocketMQTransactionListener注解的bean，然后执行processTransactionListenerAnnotation方法

• processTransactionListenerAnnotation方法会创建transactionHandler，然后执行transactionHandlerRegistry.registerTransactionHandler进行注册

TransactionHandler

rocketmq-spring-boot-2.0.3-sources.jar!/org/apache/rocketmq/spring/config/TransactionHandler.java

class TransactionHandler {
    private String name;
    private String beanName;
    private RocketMQLocalTransactionListener bean;
    private BeanFactory beanFactory;
    private ThreadPoolExecutor checkExecutor;
    private RPCHook rpcHook;

    public String getBeanName() {
        return beanName;
    }

    public void setBeanName(String beanName) {
        this.beanName = beanName;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public RPCHook getRpcHook() {
        return rpcHook;
    }

    public void setRpcHook(RPCHook rpcHook) {
        this.rpcHook = rpcHook;
    }

    public BeanFactory getBeanFactory() {
        return beanFactory;
    }

    public void setBeanFactory(BeanFactory beanFactory) {
        this.beanFactory = beanFactory;
    }

    public void setListener(RocketMQLocalTransactionListener listener) {
        this.bean = listener;
    }

    public RocketMQLocalTransactionListener getListener() {
        return this.bean;
    }

    public void setCheckExecutor(int corePoolSize, int maxPoolSize, long keepAliveTime, int blockingQueueSize) {
        this.checkExecutor = new ThreadPoolExecutor(corePoolSize, maxPoolSize,
            keepAliveTime, TimeUnit.MILLISECONDS,
            new LinkedBlockingDeque<>(blockingQueueSize));
    }

    public ThreadPoolExecutor getCheckExecutor() {
        return checkExecutor;
    }
}

• TransactionHandler包含了name、beanName、bean、beanFactory、checkExecutor、rpcHook属性

TransactionHandlerRegistry

rocketmq-spring-boot-2.0.3-sources.jar!/org/apache/rocketmq/spring/config/TransactionHandlerRegistry.java

public class TransactionHandlerRegistry implements DisposableBean {
    private RocketMQTemplate rocketMQTemplate;

    private final Set<String> listenerContainers = new ConcurrentSet<>();

    public TransactionHandlerRegistry(RocketMQTemplate template) {
        this.rocketMQTemplate = template;
    }

    @Override
    public void destroy() throws Exception {
        listenerContainers.clear();
    }

    public void registerTransactionHandler(TransactionHandler handler) throws MQClientException {
        if (listenerContainers.contains(handler.getName())) {
            throw new MQClientException(-1,
                String
                    .format("The transaction name [%s] has been defined in TransactionListener [%s]", handler.getName(),
                        handler.getBeanName()));
        }
        listenerContainers.add(handler.getName());

        rocketMQTemplate.createAndStartTransactionMQProducer(handler.getName(), handler.getListener(), handler.getCheckExecutor(), handler.getRpcHook());
    }
}

• TransactionHandlerRegistry实现了DisposableBean接口，其clear方法直接清空listenerContainers；registerTransactionHandler方法会往listenerContainers添加该handler的name，然后执行rocketMQTemplate.createAndStartTransactionMQProducer来创建并启动TransactionMQProducer

小结

• RocketMQTransactionAnnotationProcessor实现了BeanPostProcessor, Ordered, ApplicationContextAware接口

• postProcessAfterInitialization方法会查找标记有RocketMQTransactionListener注解的bean，然后执行processTransactionListenerAnnotation方法

• processTransactionListenerAnnotation方法会创建transactionHandler，然后执行transactionHandlerRegistry.registerTransactionHandler进行注册

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