RocketMQ源码分析之消费消息（上）

最新推荐文章于 2025-01-07 11:10:29 发布

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最新推荐文章于 2025-01-07 11:10:29 发布 · 930 阅读

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文章标签：

#RocketMQ

本文深入探讨RocketMQ消费消息过程，从拉取回调、异常处理、消息过滤到队列偏移量更新，详述每个步骤，并强调直接对比tag以避免哈希冲突，同时涵盖消息的处理、大小记录及消费请求提交策略。

当从broker拉取到消息后，开始执行回调方法


private void executeInvokeCallback(final ResponseFuture responseFuture) {
    boolean runInThisThread = false;
    ExecutorService executor = this.getCallbackExecutor();
    if (executor != null) {
        try {
            executor.submit(new Runnable() {
                @Override
                public void run() {
                    try {
                        responseFuture.executeInvokeCallback();
                    } catch (Throwable e) {
                        log.warn("execute callback in executor exception, and callback throw", e);
                    } finally {
                        responseFuture.release();
                    }
                }
            });
        } catch (Exception e) {
            runInThisThread = true;
            log.warn("execute callback in executor exception, maybe executor busy", e);
        }
    } else {
        runInThisThread = true;
    }

    if (runInThisThread) {
        try {
            responseFuture.executeInvokeCallback();
        } catch (Throwable e) {
            log.warn("executeInvokeCallback Exception", e);
        } finally {
            responseFuture.release();
        }
    }
}

并且回调方法只能执行一次，解析具体回应的数据

public void executeInvokeCallback() {
    if (invokeCallback != null) {
        if (this.executeCallbackOnlyOnce.compareAndSet(false, true)) {
            invokeCallback.operationComplete(this);
        }
    }
}

public void operationComplete(ResponseFuture responseFuture) {
    RemotingCommand response = responseFuture.getResponseCommand();
    if (response != null) {
        try {
            PullResult pullResult = MQClientAPIImpl.this.processPullResponse(response);
            assert pullResult != null;
            pullCallback.onSuccess(pullResult);
        } catch (Exception e) {
            pullCallback.onException(e);
        }
    } else {
        if (!responseFuture.isSendRequestOK()) {
            pullCallback.onException(new MQClientException("send request failed to " + addr + ". Request: " + request, responseFuture.getCause()));
        } else if (responseFuture.isTimeout()) {
            pullCallback.onException(new MQClientException("wait response from " + addr + " timeout :" + responseFuture.getTimeoutMillis() + "ms" + ". Request: " + request,
                responseFuture.getCause()));
        } else {
            pullCallback.onException(new MQClientException("unknown reason. addr: " + addr + ", timeoutMillis: " + timeoutMillis + ". Request: " + request, responseFuture.getCause()));
        }
    }
}

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