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itemprop=publisher itemscope itemtype=http://schema.org/Organization><meta content="Nicksxs's Blog" itemprop=name><meta content="Nicksxs 的技术博客,深入 Java 运行时与生产诊断、低成本大模型推理和 Agent 工程实践。" itemprop=description></span><span hidden itemprop=post itemscope itemtype=http://schema.org/CreativeWork><meta content="聊一下 RocketMQ 的 DefaultMQPushConsumer 源码 | Nicksxs's Blog" itemprop=name><meta content="首先看下官方的小 demo。然后就是看看 start 的过程了 具体的逻辑在this.defaultMQPushConsumerImpl.start(),这个 defaultMQPushConsumerImpl 就是" itemprop=description></span><header class=post-header><h1 itemprop="name headline" class=post-title>聊一下 RocketMQ 的 DefaultMQPushConsumer 源码</h1><div class=post-meta-container><div class=post-meta><span class=post-meta-item><span class=post-meta-item-icon><i class="far fa-calendar"></i> </span><span class=post-meta-item-text>发表于</span> <time itemprop="dateCreated datePublished" title="创建时间:2020-06-26 22:21:20" datetime=2020-06-26T22:21:20+08:00>2020-06-26</time> </span><span class=post-meta-item><span class=post-meta-item-icon><i class="far fa-folder"></i> </span><span class=post-meta-item-text>分类于</span> <span itemprop=about itemscope itemtype=http://schema.org/Thing><a href=/categories/MQ/ itemprop=url rel=index><span itemprop=name>MQ</span></a> </span>, <span itemprop=about itemscope itemtype=http://schema.org/Thing><a href=/categories/MQ/RocketMQ/ itemprop=url rel=index><span itemprop=name>RocketMQ</span></a> </span>, <span itemprop=about itemscope itemtype=http://schema.org/Thing><a href=/categories/%E6%B6%88%E6%81%AF%E9%98%9F%E5%88%97/ itemprop=url rel=index><span itemprop=name>消息队列</span></a> </span>, <span itemprop=about itemscope itemtype=http://schema.org/Thing><a href=/categories/%E6%B6%88%E6%81%AF%E9%98%9F%E5%88%97/RocketMQ/ itemprop=url rel=index><span itemprop=name>RocketMQ</span></a> </span>, <span itemprop=about itemscope itemtype=http://schema.org/Thing><a href=/categories/%E4%B8%AD%E9%97%B4%E4%BB%B6/ itemprop=url rel=index><span itemprop=name>中间件</span></a> </span>, <span itemprop=about itemscope itemtype=http://schema.org/Thing><a href=/categories/%E4%B8%AD%E9%97%B4%E4%BB%B6/RocketMQ/ itemprop=url rel=index><span itemprop=name>RocketMQ</span></a> </span></span><span class="post-meta-item cloudflare-page-counter" data-title="聊一下 RocketMQ 的 DefaultMQPushConsumer 源码" data-increment=true data-path=/2020/06/26/%E8%81%8A%E4%B8%80%E4%B8%8B-RocketMQ-%E7%9A%84-Consumer/ title=阅读次数><span class=post-meta-item-icon><i class="far fa-eye"></i> </span><span class=post-meta-item-text>阅读次数:</span> <span class=cloudflare-page-counter-count></span></span></div><div class=post-description>首先看下官方的小 demo。然后就是看看 start 的过程了 具体的逻辑在this.defaultMQPushConsumerImpl.start(),这个 defaultMQPushConsumerImpl 就是</div></div></header><div class=post-body itemprop=articleBody><p>首先看下官方的小 demo<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br><span class=line>10</span><br><span class=line>11</span><br><span class=line>12</span><br><span class=line>13</span><br><span class=line>14</span><br><span class=line>15</span><br><span class=line>16</span><br><span class=line>17</span><br><span class=line>18</span><br><span class=line>19</span><br><span class=line>20</span><br><span class=line>21</span><br><span class=line>22</span><br><span class=line>23</span><br><span class=line>24</span><br><span class=line>25</span><br><span class=line>26</span><br><span class=line>27</span><br><span class=line>28</span><br><span class=line>29</span><br><span class=line>30</span><br><span class=line>31</span><br><span class=line>32</span><br><span class=line>33</span><br><span class=line>34</span><br><span class=line>35</span><br><span class=line>36</span><br><span class=line>37</span><br><span class=line>38</span><br><span class=line>39</span><br><span class=line>40</span><br><span class=line>41</span><br><span class=line>42</span><br><span class=line>43</span><br><span class=line>44</span><br><span class=line>45</span><br><span class=line>46</span><br><span class=line>47</span><br><span class=line>48</span><br><span class=line>49</span><br><span class=line>50</span><br><span class=line>51</span><br><span class=line>52</span><br><span class=line>53</span><br><span class=line>54</span><br><span class=line>55</span><br><span class=line>56</span><br></pre><td class=code><pre><span class=line><span class=keyword>public</span> <span class=keyword>static</span> <span class=keyword>void</span> <span class="title function_">main</span><span class=params>(String[] args)</span> <span class=keyword>throws</span> InterruptedException, MQClientException {</span><br><span class=line></span><br><span class=line> <span class=comment>/*</span></span><br><span class=line><span class=comment> * Instantiate with specified consumer group name.</span></span><br><span class=line><span class=comment> * 首先是new 一个对象出来,然后指定 Consumer 的 Group</span></span><br><span class=line><span class=comment> * 同一类Consumer的集合,这类Consumer通常消费同一类消息且消费逻辑一致。消费者组使得在消息消费方面,实现负载均衡和容错的目标变得非常容易。要注意的是,消费者组的消费者实例必须订阅完全相同的Topic。RocketMQ 支持两种消息模式:集群消费(Clustering)和广播消费(Broadcasting)。</span></span><br><span class=line><span class=comment> */</span></span><br><span class=line> <span class=type>DefaultMQPushConsumer</span> <span class=variable>consumer</span> <span class=operator>=</span> <span class=keyword>new</span> <span class="title class_">DefaultMQPushConsumer</span>(<span class=string>"please_rename_unique_group_name_4"</span>);</span><br><span class=line></span><br><span class=line> <span class=comment>/*</span></span><br><span class=line><span class=comment> * Specify name server addresses.</span></span><br><span class=line><span class=comment> * &LTp/></span></span><br><span class=line><span class=comment> * 这里可以通知指定环境变量或者设置对象参数的形式指定名字空间服务的地址</span></span><br><span class=line><span class=comment> *</span></span><br><span class=line><span class=comment> * Alternatively, you may specify name server addresses via exporting environmental variable: NAMESRV_ADDR</span></span><br><span class=line><span class=comment> * &LTpre></span></span><br><span class=line><span class=comment> * {@code</span></span><br><span class=line><span class=comment> * consumer.setNamesrvAddr("name-server1-ip:9876;name-server2-ip:9876");</span></span><br><span class=line><span class=comment> * }</span></span><br><span class=line><span class=comment> * &LT/pre></span></span><br><span class=line><span class=comment> */</span></span><br><span class=line></span><br><span class=line> <span class=comment>/*</span></span><br><span class=line><span class=comment> * Specify where to start in case the specified consumer group is a brand new one.</span></span><br><span class=line><span class=comment> * 指定消费起始点</span></span><br><span class=line><span class=comment> */</span></span><br><span class=line> consumer.setConsumeFromWhere(ConsumeFromWhere.CONSUME_FROM_FIRST_OFFSET);</span><br><span class=line></span><br><span class=line> <span class=comment>/*</span></span><br><span class=line><span class=comment> * Subscribe one more more topics to consume.</span></span><br><span class=line><span class=comment> * 指定订阅的 topic 跟 tag,注意后面的是个表达式,可以以 tag1 || tag2 || tag3 传入</span></span><br><span class=line><span class=comment> */</span></span><br><span class=line> consumer.subscribe(<span class=string>"TopicTest"</span>, <span class=string>"*"</span>);</span><br><span class=line></span><br><span class=line> <span class=comment>/*</span></span><br><span class=line><span class=comment> * Register callback to execute on arrival of messages fetched from brokers.</span></span><br><span class=line><span class=comment> * 注册具体获得消息后的处理方法</span></span><br><span class=line><span class=comment> */</span></span><br><span class=line> consumer.registerMessageListener(<span class=keyword>new</span> <span class="title class_">MessageListenerConcurrently</span>() {</span><br><span class=line></span><br><span class=line> <span class=meta>@Override</span></span><br><span class=line> <span class=keyword>public</span> ConsumeConcurrentlyStatus <span class="title function_">consumeMessage</span><span class=params>(List&LTMessageExt> msgs,</span></span><br><span class=line><span class=params> ConsumeConcurrentlyContext context)</span> {</span><br><span class=line> System.out.printf(<span class=string>"%s Receive New Messages: %s %n"</span>, Thread.currentThread().getName(), msgs);</span><br><span class=line> <span class=keyword>return</span> ConsumeConcurrentlyStatus.CONSUME_SUCCESS;</span><br><span class=line> }</span><br><span class=line> });</span><br><span class=line></span><br><span class=line> <span class=comment>/*</span></span><br><span class=line><span class=comment> * Launch the consumer instance.</span></span><br><span class=line><span class=comment> * 启动消费者</span></span><br><span class=line><span class=comment> */</span></span><br><span class=line> consumer.start();</span><br><span class=line></span><br><span class=line> System.out.printf(<span class=string>"Consumer Started.%n"</span>);</span><br><span class=line> }</span><br></pre></table></figure><p>然后就是看看 start 的过程了<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br><span class=line>10</span><br><span class=line>11</span><br><span class=line>12</span><br><span class=line>13</span><br><span class=line>14</span><br><span class=line>15</span><br><span class=line>16</span><br><span class=line>17</span><br></pre><td class=code><pre><span class=line><span class=comment>/**</span></span><br><span class=line><span class=comment> * This method gets internal infrastructure readily to serve. Instances must call this method after configuration.</span></span><br><span class=line><span class=comment> *</span></span><br><span class=line><span class=comment> * <span class=doctag>@throws</span> MQClientException if there is any client error.</span></span><br><span class=line><span class=comment> */</span></span><br><span class=line> <span class=meta>@Override</span></span><br><span class=line> <span class=keyword>public</span> <span class=keyword>void</span> <span class="title function_">start</span><span class=params>()</span> <span class=keyword>throws</span> MQClientException {</span><br><span class=line> setConsumerGroup(NamespaceUtil.wrapNamespace(<span class=built_in>this</span>.getNamespace(), <span class=built_in>this</span>.consumerGroup));</span><br><span class=line> <span class=built_in>this</span>.defaultMQPushConsumerImpl.start();</span><br><span class=line> <span class=keyword>if</span> (<span class=literal>null</span> != traceDispatcher) {</span><br><span class=line> <span class=keyword>try</span> {</span><br><span class=line> traceDispatcher.start(<span class=built_in>this</span>.getNamesrvAddr(), <span class=built_in>this</span>.getAccessChannel());</span><br><span class=line> } <span class=keyword>catch</span> (MQClientException e) {</span><br><span class=line> log.warn(<span class=string>"trace dispatcher start failed "</span>, e);</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line> }</span><br></pre></table></figure><p>具体的逻辑在<code>this.defaultMQPushConsumerImpl.start()</code>,这个 defaultMQPushConsumerImpl 就是<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br></pre><td class=code><pre><span class=line><span class=comment>/**</span></span><br><span class=line><span class=comment> * Internal implementation. Most of the functions herein are delegated to it.</span></span><br><span class=line><span class=comment> */</span></span><br><span class=line> <span class=keyword>protected</span> <span class=keyword>final</span> <span class=keyword>transient</span> DefaultMQPushConsumerImpl defaultMQPushConsumerImpl;</span><br></pre></table></figure><figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br><span class=line>10</span><br><span class=line>11</span><br><span class=line>12</span><br><span class=line>13</span><br><span class=line>14</span><br><span class=line>15</span><br><span class=line>16</span><br><span class=line>17</span><br><span class=line>18</span><br><span class=line>19</span><br><span class=line>20</span><br><span class=line>21</span><br><span class=line>22</span><br><span class=line>23</span><br><span class=line>24</span><br><span class=line>25</span><br><span class=line>26</span><br><span class=line>27</span><br><span class=line>28</span><br><span class=line>29</span><br><span class=line>30</span><br><span class=line>31</span><br><span class=line>32</span><br><span class=line>33</span><br><span class=line>34</span><br><span class=line>35</span><br><span class=line>36</span><br><span class=line>37</span><br><span class=line>38</span><br><span class=line>39</span><br><span class=line>40</span><br><span class=line>41</span><br><span class=line>42</span><br><span class=line>43</span><br><span class=line>44</span><br><span class=line>45</span><br><span class=line>46</span><br><span class=line>47</span><br><span class=line>48</span><br><span class=line>49</span><br><span class=line>50</span><br><span class=line>51</span><br><span class=line>52</span><br><span class=line>53</span><br><span class=line>54</span><br><span class=line>55</span><br><span class=line>56</span><br><span class=line>57</span><br><span class=line>58</span><br><span class=line>59</span><br><span class=line>60</span><br><span class=line>61</span><br><span class=line>62</span><br><span class=line>63</span><br><span class=line>64</span><br><span class=line>65</span><br><span class=line>66</span><br><span class=line>67</span><br><span class=line>68</span><br><span class=line>69</span><br><span class=line>70</span><br><span class=line>71</span><br><span class=line>72</span><br><span class=line>73</span><br><span class=line>74</span><br><span class=line>75</span><br><span class=line>76</span><br><span class=line>77</span><br><span class=line>78</span><br><span class=line>79</span><br><span class=line>80</span><br><span class=line>81</span><br><span class=line>82</span><br><span class=line>83</span><br><span class=line>84</span><br><span class=line>85</span><br><span class=line>86</span><br><span class=line>87</span><br><span class=line>88</span><br><span class=line>89</span><br><span class=line>90</span><br><span class=line>91</span><br></pre><td class=code><pre><span class=line><span class=keyword>public</span> <span class=keyword>synchronized</span> <span class=keyword>void</span> <span class="title function_">start</span><span class=params>()</span> <span class=keyword>throws</span> MQClientException {</span><br><span class=line> <span class=keyword>switch</span> (<span class=built_in>this</span>.serviceState) {</span><br><span class=line> <span class=keyword>case</span> CREATE_JUST:</span><br><span class=line> log.info(<span class=string>"the consumer [{}] start beginning. messageModel={}, isUnitMode={}"</span>, <span class=built_in>this</span>.defaultMQPushConsumer.getConsumerGroup(),</span><br><span class=line> <span class=built_in>this</span>.defaultMQPushConsumer.getMessageModel(), <span class=built_in>this</span>.defaultMQPushConsumer.isUnitMode());</span><br><span class=line> <span class=comment>// 这里比较巧妙,相当于想设立了个屏障,防止并发启动,不过这里并不是悲观锁,也不算个严格的乐观锁</span></span><br><span class=line> <span class=built_in>this</span>.serviceState = ServiceState.START_FAILED;</span><br><span class=line></span><br><span class=line> <span class=built_in>this</span>.checkConfig();</span><br><span class=line></span><br><span class=line> <span class=built_in>this</span>.copySubscription();</span><br><span class=line></span><br><span class=line> <span class=keyword>if</span> (<span class=built_in>this</span>.defaultMQPushConsumer.getMessageModel() == MessageModel.CLUSTERING) {</span><br><span class=line> <span class=built_in>this</span>.defaultMQPushConsumer.changeInstanceNameToPID();</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=comment>// 这个mQClientFactory,负责管理client(consumer、producer),并提供多中功能接口供各个Service(Rebalance、PullMessage等)调用;大部分逻辑均在这个类中完成</span></span><br><span class=line> <span class=built_in>this</span>.mQClientFactory = MQClientManager.getInstance().getOrCreateMQClientInstance(<span class=built_in>this</span>.defaultMQPushConsumer, <span class=built_in>this</span>.rpcHook);</span><br><span class=line></span><br><span class=line> <span class=comment>// 这个 rebalanceImpl 主要负责决定,当前的consumer应该从哪些Queue中消费消息;</span></span><br><span class=line> <span class=built_in>this</span>.rebalanceImpl.setConsumerGroup(<span class=built_in>this</span>.defaultMQPushConsumer.getConsumerGroup());</span><br><span class=line> <span class=built_in>this</span>.rebalanceImpl.setMessageModel(<span class=built_in>this</span>.defaultMQPushConsumer.getMessageModel());</span><br><span class=line> <span class=built_in>this</span>.rebalanceImpl.setAllocateMessageQueueStrategy(<span class=built_in>this</span>.defaultMQPushConsumer.getAllocateMessageQueueStrategy());</span><br><span class=line> <span class=built_in>this</span>.rebalanceImpl.setmQClientFactory(<span class=built_in>this</span>.mQClientFactory);</span><br><span class=line></span><br><span class=line> <span class=comment>// 长连接,负责从broker处拉取消息,然后利用ConsumeMessageService回调用户的Listener执行消息消费逻辑</span></span><br><span class=line> <span class=built_in>this</span>.pullAPIWrapper = <span class=keyword>new</span> <span class="title class_">PullAPIWrapper</span>(</span><br><span class=line> mQClientFactory,</span><br><span class=line> <span class=built_in>this</span>.defaultMQPushConsumer.getConsumerGroup(), isUnitMode());</span><br><span class=line> <span class=built_in>this</span>.pullAPIWrapper.registerFilterMessageHook(filterMessageHookList);</span><br><span class=line></span><br><span class=line> <span class=keyword>if</span> (<span class=built_in>this</span>.defaultMQPushConsumer.getOffsetStore() != <span class=literal>null</span>) {</span><br><span class=line> <span class=built_in>this</span>.offsetStore = <span class=built_in>this</span>.defaultMQPushConsumer.getOffsetStore();</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> <span class=keyword>switch</span> (<span class=built_in>this</span>.defaultMQPushConsumer.getMessageModel()) {</span><br><span class=line> <span class=keyword>case</span> BROADCASTING:</span><br><span class=line> <span class=built_in>this</span>.offsetStore = <span class=keyword>new</span> <span class="title class_">LocalFileOffsetStore</span>(<span class=built_in>this</span>.mQClientFactory, <span class=built_in>this</span>.defaultMQPushConsumer.getConsumerGroup());</span><br><span class=line> <span class=keyword>break</span>;</span><br><span class=line> <span class=keyword>case</span> CLUSTERING:</span><br><span class=line> <span class=built_in>this</span>.offsetStore = <span class=keyword>new</span> <span class="title class_">RemoteBrokerOffsetStore</span>(<span class=built_in>this</span>.mQClientFactory, <span class=built_in>this</span>.defaultMQPushConsumer.getConsumerGroup());</span><br><span class=line> <span class=keyword>break</span>;</span><br><span class=line> <span class=keyword>default</span>:</span><br><span class=line> <span class=keyword>break</span>;</span><br><span class=line> }</span><br><span class=line> <span class=built_in>this</span>.defaultMQPushConsumer.setOffsetStore(<span class=built_in>this</span>.offsetStore);</span><br><span class=line> }</span><br><span class=line> <span class=comment>// offsetStore 维护当前consumer的消费记录(offset);有两种实现,Local和Rmote,Local存储在本地磁盘上,适用于BROADCASTING广播消费模式;而Remote则将消费进度存储在Broker上,适用于CLUSTERING集群消费模式;</span></span><br><span class=line> <span class=built_in>this</span>.offsetStore.load();</span><br><span class=line></span><br><span class=line> <span class=keyword>if</span> (<span class=built_in>this</span>.getMessageListenerInner() <span class=keyword>instanceof</span> MessageListenerOrderly) {</span><br><span class=line> <span class=built_in>this</span>.consumeOrderly = <span class=literal>true</span>;</span><br><span class=line> <span class=built_in>this</span>.consumeMessageService =</span><br><span class=line> <span class=keyword>new</span> <span class="title class_">ConsumeMessageOrderlyService</span>(<span class=built_in>this</span>, (MessageListenerOrderly) <span class=built_in>this</span>.getMessageListenerInner());</span><br><span class=line> } <span class=keyword>else</span> <span class=keyword>if</span> (<span class=built_in>this</span>.getMessageListenerInner() <span class=keyword>instanceof</span> MessageListenerConcurrently) {</span><br><span class=line> <span class=built_in>this</span>.consumeOrderly = <span class=literal>false</span>;</span><br><span class=line> <span class=built_in>this</span>.consumeMessageService =</span><br><span class=line> <span class=keyword>new</span> <span class="title class_">ConsumeMessageConcurrentlyService</span>(<span class=built_in>this</span>, (MessageListenerConcurrently) <span class=built_in>this</span>.getMessageListenerInner());</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=comment>// 实现所谓的"Push-被动"消费机制;从Broker拉取的消息后,封装成ConsumeRequest提交给ConsumeMessageSerivce,此service负责回调用户的Listener消费消息;</span></span><br><span class=line> <span class=built_in>this</span>.consumeMessageService.start();</span><br><span class=line></span><br><span class=line> <span class=type>boolean</span> <span class=variable>registerOK</span> <span class=operator>=</span> mQClientFactory.registerConsumer(<span class=built_in>this</span>.defaultMQPushConsumer.getConsumerGroup(), <span class=built_in>this</span>);</span><br><span class=line> <span class=keyword>if</span> (!registerOK) {</span><br><span class=line> <span class=built_in>this</span>.serviceState = ServiceState.CREATE_JUST;</span><br><span class=line> <span class=built_in>this</span>.consumeMessageService.shutdown();</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">MQClientException</span>(<span class=string>"The consumer group["</span> + <span class=built_in>this</span>.defaultMQPushConsumer.getConsumerGroup()</span><br><span class=line> + <span class=string>"] has been created before, specify another name please."</span> + FAQUrl.suggestTodo(FAQUrl.GROUP_NAME_DUPLICATE_URL),</span><br><span class=line> <span class=literal>null</span>);</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> mQClientFactory.start();</span><br><span class=line> log.info(<span class=string>"the consumer [{}] start OK."</span>, <span class=built_in>this</span>.defaultMQPushConsumer.getConsumerGroup());</span><br><span class=line> <span class=built_in>this</span>.serviceState = ServiceState.RUNNING;</span><br><span class=line> <span class=keyword>break</span>;</span><br><span class=line> <span class=keyword>case</span> RUNNING:</span><br><span class=line> <span class=keyword>case</span> START_FAILED:</span><br><span class=line> <span class=keyword>case</span> SHUTDOWN_ALREADY:</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">MQClientException</span>(<span class=string>"The PushConsumer service state not OK, maybe started once, "</span></span><br><span class=line> + <span class=built_in>this</span>.serviceState</span><br><span class=line> + FAQUrl.suggestTodo(FAQUrl.CLIENT_SERVICE_NOT_OK),</span><br><span class=line> <span class=literal>null</span>);</span><br><span class=line> <span class=keyword>default</span>:</span><br><span class=line> <span class=keyword>break</span>;</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=built_in>this</span>.updateTopicSubscribeInfoWhenSubscriptionChanged();</span><br><span class=line> <span class=built_in>this</span>.mQClientFactory.checkClientInBroker();</span><br><span class=line> <span class=built_in>this</span>.mQClientFactory.sendHeartbeatToAllBrokerWithLock();</span><br><span class=line> <span class=built_in>this</span>.mQClientFactory.rebalanceImmediately();</span><br><span class=line> }</span><br></pre></table></figure><p>然后我们往下看主要的目光聚焦<code>mQClientFactory.start()</code><figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br><span class=line>10</span><br><span class=line>11</span><br><span class=line>12</span><br><span class=line>13</span><br><span class=line>14</span><br><span class=line>15</span><br><span class=line>16</span><br><span class=line>17</span><br><span class=line>18</span><br><span class=line>19</span><br><span class=line>20</span><br><span class=line>21</span><br><span class=line>22</span><br><span class=line>23</span><br><span class=line>24</span><br><span class=line>25</span><br><span class=line>26</span><br><span class=line>27</span><br><span class=line>28</span><br><span class=line>29</span><br><span class=line>30</span><br><span class=line>31</span><br><span class=line>32</span><br><span class=line>33</span><br></pre><td class=code><pre><span class=line><span class=keyword>public</span> <span class=keyword>void</span> <span class="title function_">start</span><span class=params>()</span> <span class=keyword>throws</span> MQClientException {</span><br><span class=line></span><br><span class=line> <span class=keyword>synchronized</span> (<span class=built_in>this</span>) {</span><br><span class=line> <span class=keyword>switch</span> (<span class=built_in>this</span>.serviceState) {</span><br><span class=line> <span class=keyword>case</span> CREATE_JUST:</span><br><span class=line> <span class=built_in>this</span>.serviceState = ServiceState.START_FAILED;</span><br><span class=line> <span class=comment>// If not specified,looking address from name server</span></span><br><span class=line> <span class=keyword>if</span> (<span class=literal>null</span> == <span class=built_in>this</span>.clientConfig.getNamesrvAddr()) {</span><br><span class=line> <span class=built_in>this</span>.mQClientAPIImpl.fetchNameServerAddr();</span><br><span class=line> }</span><br><span class=line> <span class=comment>// Start request-response channel</span></span><br><span class=line> <span class=comment>// 这里主要是初始化了个网络客户端</span></span><br><span class=line> <span class=built_in>this</span>.mQClientAPIImpl.start();</span><br><span class=line> <span class=comment>// Start various schedule tasks</span></span><br><span class=line> <span class=comment>// 定时任务</span></span><br><span class=line> <span class=built_in>this</span>.startScheduledTask();</span><br><span class=line> <span class=comment>// Start pull service</span></span><br><span class=line> <span class=comment>// 这里重点说下</span></span><br><span class=line> <span class=built_in>this</span>.pullMessageService.start();</span><br><span class=line> <span class=comment>// Start rebalance service</span></span><br><span class=line> <span class=built_in>this</span>.rebalanceService.start();</span><br><span class=line> <span class=comment>// Start push service</span></span><br><span class=line> <span class=built_in>this</span>.defaultMQProducer.getDefaultMQProducerImpl().start(<span class=literal>false</span>);</span><br><span class=line> log.info(<span class=string>"the client factory [{}] start OK"</span>, <span class=built_in>this</span>.clientId);</span><br><span class=line> <span class=built_in>this</span>.serviceState = ServiceState.RUNNING;</span><br><span class=line> <span class=keyword>break</span>;</span><br><span class=line> <span class=keyword>case</span> START_FAILED:</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">MQClientException</span>(<span class=string>"The Factory object["</span> + <span class=built_in>this</span>.getClientId() + <span class=string>"] has been created before, and failed."</span>, <span class=literal>null</span>);</span><br><span class=line> <span class=keyword>default</span>:</span><br><span class=line> <span class=keyword>break</span>;</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line> }</span><br></pre></table></figure><p>我们来看下这个 pullMessageService,org.apache.rocketmq.client.impl.consumer.PullMessageService,<br><img loading=lazy src=https://mystore-1255223546.cos.ap-chengdu.myqcloud.com/uPic/QdeiVv.png><br>实现了 runnable 接口,<br>然后可以看到 run 方法<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br><span class=line>10</span><br><span class=line>11</span><br><span class=line>12</span><br><span class=line>13</span><br><span class=line>14</span><br><span class=line>15</span><br></pre><td class=code><pre><span class=line><span class=keyword>public</span> <span class=keyword>void</span> <span class="title function_">run</span><span class=params>()</span> {</span><br><span class=line> log.info(<span class=built_in>this</span>.getServiceName() + <span class=string>" service started"</span>);</span><br><span class=line></span><br><span class=line> <span class=keyword>while</span> (!<span class=built_in>this</span>.isStopped()) {</span><br><span class=line> <span class=keyword>try</span> {</span><br><span class=line> <span class=type>PullRequest</span> <span class=variable>pullRequest</span> <span class=operator>=</span> <span class=built_in>this</span>.pullRequestQueue.take();</span><br><span class=line> <span class=built_in>this</span>.pullMessage(pullRequest);</span><br><span class=line> } <span class=keyword>catch</span> (InterruptedException ignored) {</span><br><span class=line> } <span class=keyword>catch</span> (Exception e) {</span><br><span class=line> log.error(<span class=string>"Pull Message Service Run Method exception"</span>, e);</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> log.info(<span class=built_in>this</span>.getServiceName() + <span class=string>" service end"</span>);</span><br><span class=line> }</span><br></pre></table></figure><p>接着在看 pullMessage 方法<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br></pre><td class=code><pre><span class=line><span class=keyword>private</span> <span class=keyword>void</span> <span class="title function_">pullMessage</span><span class=params>(<span class=keyword>final</span> PullRequest pullRequest)</span> {</span><br><span class=line> <span class=keyword>final</span> <span class=type>MQConsumerInner</span> <span class=variable>consumer</span> <span class=operator>=</span> <span class=built_in>this</span>.mQClientFactory.selectConsumer(pullRequest.getConsumerGroup());</span><br><span class=line> <span class=keyword>if</span> (consumer != <span class=literal>null</span>) {</span><br><span class=line> <span class=type>DefaultMQPushConsumerImpl</span> <span class=variable>impl</span> <span class=operator>=</span> (DefaultMQPushConsumerImpl) consumer;</span><br><span class=line> impl.pullMessage(pullRequest);</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> log.warn(<span class=string>"No matched consumer for the PullRequest {}, drop it"</span>, pullRequest);</span><br><span class=line> }</span><br><span class=line> }</span><br></pre></table></figure><p>实际上调用了这个方法,这个方法很长,我在代码里注释下下每一段的功能<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br><span class=line>10</span><br><span class=line>11</span><br><span class=line>12</span><br><span class=line>13</span><br><span class=line>14</span><br><span class=line>15</span><br><span class=line>16</span><br><span class=line>17</span><br><span class=line>18</span><br><span class=line>19</span><br><span class=line>20</span><br><span class=line>21</span><br><span class=line>22</span><br><span class=line>23</span><br><span class=line>24</span><br><span class=line>25</span><br><span class=line>26</span><br><span class=line>27</span><br><span class=line>28</span><br><span class=line>29</span><br><span class=line>30</span><br><span class=line>31</span><br><span class=line>32</span><br><span class=line>33</span><br><span class=line>34</span><br><span class=line>35</span><br><span class=line>36</span><br><span class=line>37</span><br><span class=line>38</span><br><span class=line>39</span><br><span class=line>40</span><br><span class=line>41</span><br><span class=line>42</span><br><span class=line>43</span><br><span class=line>44</span><br><span class=line>45</span><br><span class=line>46</span><br><span class=line>47</span><br><span class=line>48</span><br><span class=line>49</span><br><span class=line>50</span><br><span class=line>51</span><br><span class=line>52</span><br><span class=line>53</span><br><span class=line>54</span><br><span class=line>55</span><br><span class=line>56</span><br><span class=line>57</span><br><span class=line>58</span><br><span class=line>59</span><br><span class=line>60</span><br><span class=line>61</span><br><span class=line>62</span><br><span class=line>63</span><br><span class=line>64</span><br><span class=line>65</span><br><span class=line>66</span><br><span class=line>67</span><br><span class=line>68</span><br><span class=line>69</span><br><span class=line>70</span><br><span class=line>71</span><br><span class=line>72</span><br><span class=line>73</span><br><span class=line>74</span><br><span class=line>75</span><br><span class=line>76</span><br><span class=line>77</span><br><span class=line>78</span><br><span class=line>79</span><br><span class=line>80</span><br><span class=line>81</span><br><span class=line>82</span><br><span class=line>83</span><br><span class=line>84</span><br><span class=line>85</span><br><span class=line>86</span><br><span class=line>87</span><br><span class=line>88</span><br><span class=line>89</span><br><span class=line>90</span><br><span class=line>91</span><br><span class=line>92</span><br><span class=line>93</span><br><span class=line>94</span><br><span class=line>95</span><br><span class=line>96</span><br><span class=line>97</span><br><span class=line>98</span><br><span class=line>99</span><br><span class=line>100</span><br><span class=line>101</span><br><span class=line>102</span><br><span class=line>103</span><br><span class=line>104</span><br><span class=line>105</span><br><span class=line>106</span><br><span class=line>107</span><br><span class=line>108</span><br><span class=line>109</span><br><span class=line>110</span><br><span class=line>111</span><br><span class=line>112</span><br><span class=line>113</span><br><span class=line>114</span><br><span class=line>115</span><br><span class=line>116</span><br><span class=line>117</span><br><span class=line>118</span><br><span class=line>119</span><br><span class=line>120</span><br><span class=line>121</span><br><span class=line>122</span><br><span class=line>123</span><br><span class=line>124</span><br><span class=line>125</span><br><span class=line>126</span><br><span class=line>127</span><br><span class=line>128</span><br><span class=line>129</span><br><span class=line>130</span><br><span class=line>131</span><br><span class=line>132</span><br><span class=line>133</span><br><span class=line>134</span><br><span class=line>135</span><br><span class=line>136</span><br><span class=line>137</span><br><span class=line>138</span><br><span class=line>139</span><br><span class=line>140</span><br><span class=line>141</span><br><span class=line>142</span><br><span class=line>143</span><br><span class=line>144</span><br><span class=line>145</span><br><span class=line>146</span><br><span class=line>147</span><br><span class=line>148</span><br><span class=line>149</span><br><span class=line>150</span><br><span class=line>151</span><br><span class=line>152</span><br><span class=line>153</span><br><span class=line>154</span><br><span class=line>155</span><br><span class=line>156</span><br><span class=line>157</span><br><span class=line>158</span><br><span class=line>159</span><br><span class=line>160</span><br><span class=line>161</span><br><span class=line>162</span><br><span class=line>163</span><br><span class=line>164</span><br><span class=line>165</span><br><span class=line>166</span><br><span class=line>167</span><br><span class=line>168</span><br><span class=line>169</span><br><span class=line>170</span><br><span class=line>171</span><br><span class=line>172</span><br><span class=line>173</span><br><span class=line>174</span><br><span class=line>175</span><br><span class=line>176</span><br><span class=line>177</span><br><span class=line>178</span><br><span class=line>179</span><br><span class=line>180</span><br><span class=line>181</span><br><span class=line>182</span><br><span class=line>183</span><br><span class=line>184</span><br><span class=line>185</span><br><span class=line>186</span><br><span class=line>187</span><br><span class=line>188</span><br><span class=line>189</span><br><span class=line>190</span><br><span class=line>191</span><br><span class=line>192</span><br><span class=line>193</span><br><span class=line>194</span><br><span class=line>195</span><br><span class=line>196</span><br><span class=line>197</span><br><span class=line>198</span><br><span class=line>199</span><br><span class=line>200</span><br><span class=line>201</span><br><span class=line>202</span><br><span class=line>203</span><br><span class=line>204</span><br><span class=line>205</span><br><span class=line>206</span><br><span class=line>207</span><br><span class=line>208</span><br><span class=line>209</span><br><span class=line>210</span><br><span class=line>211</span><br><span class=line>212</span><br><span class=line>213</span><br><span class=line>214</span><br><span class=line>215</span><br><span class=line>216</span><br><span class=line>217</span><br><span class=line>218</span><br><span class=line>219</span><br><span class=line>220</span><br><span class=line>221</span><br><span class=line>222</span><br><span class=line>223</span><br><span class=line>224</span><br><span class=line>225</span><br><span class=line>226</span><br><span class=line>227</span><br><span class=line>228</span><br><span class=line>229</span><br><span class=line>230</span><br><span class=line>231</span><br><span class=line>232</span><br><span class=line>233</span><br><span class=line>234</span><br><span class=line>235</span><br><span class=line>236</span><br><span class=line>237</span><br><span class=line>238</span><br><span class=line>239</span><br><span class=line>240</span><br><span class=line>241</span><br><span class=line>242</span><br><span class=line>243</span><br><span class=line>244</span><br><span class=line>245</span><br><span class=line>246</span><br></pre><td class=code><pre><span class=line><span class=keyword>public</span> <span class=keyword>void</span> <span class="title function_">pullMessage</span><span class=params>(<span class=keyword>final</span> PullRequest pullRequest)</span> {</span><br><span class=line> <span class=keyword>final</span> <span class=type>ProcessQueue</span> <span class=variable>processQueue</span> <span class=operator>=</span> pullRequest.getProcessQueue();</span><br><span class=line> <span class=comment>// 这里开始就是检查状态,确定是否往下执行</span></span><br><span class=line> <span class=keyword>if</span> (processQueue.isDropped()) {</span><br><span class=line> log.info(<span class=string>"the pull request[{}] is dropped."</span>, pullRequest.toString());</span><br><span class=line> <span class=keyword>return</span>;</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> pullRequest.getProcessQueue().setLastPullTimestamp(System.currentTimeMillis());</span><br><span class=line></span><br><span class=line> <span class=keyword>try</span> {</span><br><span class=line> <span class=built_in>this</span>.makeSureStateOK();</span><br><span class=line> } <span class=keyword>catch</span> (MQClientException e) {</span><br><span class=line> log.warn(<span class=string>"pullMessage exception, consumer state not ok"</span>, e);</span><br><span class=line> <span class=built_in>this</span>.executePullRequestLater(pullRequest, pullTimeDelayMillsWhenException);</span><br><span class=line> <span class=keyword>return</span>;</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=keyword>if</span> (<span class=built_in>this</span>.isPause()) {</span><br><span class=line> log.warn(<span class=string>"consumer was paused, execute pull request later. instanceName={}, group={}"</span>, <span class=built_in>this</span>.defaultMQPushConsumer.getInstanceName(), <span class=built_in>this</span>.defaultMQPushConsumer.getConsumerGroup());</span><br><span class=line> <span class=built_in>this</span>.executePullRequestLater(pullRequest, PULL_TIME_DELAY_MILLS_WHEN_SUSPEND);</span><br><span class=line> <span class=keyword>return</span>;</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=comment>// 这块其实是个类似于限流的功能块,对消息数量和消息大小做限制</span></span><br><span class=line> <span class=type>long</span> <span class=variable>cachedMessageCount</span> <span class=operator>=</span> processQueue.getMsgCount().get();</span><br><span class=line> <span class=type>long</span> <span class=variable>cachedMessageSizeInMiB</span> <span class=operator>=</span> processQueue.getMsgSize().get() / (<span class=number>1024</span> * <span class=number>1024</span>);</span><br><span class=line></span><br><span class=line> <span class=keyword>if</span> (cachedMessageCount > <span class=built_in>this</span>.defaultMQPushConsumer.getPullThresholdForQueue()) {</span><br><span class=line> <span class=built_in>this</span>.executePullRequestLater(pullRequest, PULL_TIME_DELAY_MILLS_WHEN_FLOW_CONTROL);</span><br><span class=line> <span class=keyword>if</span> ((queueFlowControlTimes++ % <span class=number>1000</span>) == <span class=number>0</span>) {</span><br><span class=line> log.warn(</span><br><span class=line> <span class=string>"the cached message count exceeds the threshold {}, so do flow control, minOffset={}, maxOffset={}, count={}, size={} MiB, pullRequest={}, flowControlTimes={}"</span>,</span><br><span class=line> <span class=built_in>this</span>.defaultMQPushConsumer.getPullThresholdForQueue(), processQueue.getMsgTreeMap().firstKey(), processQueue.getMsgTreeMap().lastKey(), cachedMessageCount, cachedMessageSizeInMiB, pullRequest, queueFlowControlTimes);</span><br><span class=line> }</span><br><span class=line> <span class=keyword>return</span>;</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=keyword>if</span> (cachedMessageSizeInMiB > <span class=built_in>this</span>.defaultMQPushConsumer.getPullThresholdSizeForQueue()) {</span><br><span class=line> <span class=built_in>this</span>.executePullRequestLater(pullRequest, PULL_TIME_DELAY_MILLS_WHEN_FLOW_CONTROL);</span><br><span class=line> <span class=keyword>if</span> ((queueFlowControlTimes++ % <span class=number>1000</span>) == <span class=number>0</span>) {</span><br><span class=line> log.warn(</span><br><span class=line> <span class=string>"the cached message size exceeds the threshold {} MiB, so do flow control, minOffset={}, maxOffset={}, count={}, size={} MiB, pullRequest={}, flowControlTimes={}"</span>,</span><br><span class=line> <span class=built_in>this</span>.defaultMQPushConsumer.getPullThresholdSizeForQueue(), processQueue.getMsgTreeMap().firstKey(), processQueue.getMsgTreeMap().lastKey(), cachedMessageCount, cachedMessageSizeInMiB, pullRequest, queueFlowControlTimes);</span><br><span class=line> }</span><br><span class=line> <span class=keyword>return</span>;</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=comment>// 若不是顺序消费(即DefaultMQPushConsumerImpl.consumeOrderly等于false),则检查ProcessQueue对象的msgTreeMap:TreeMap&LTLong,MessageExt>变量的第一个key值与最后一个key值之间的差额,该key值表示查询的队列偏移量queueoffset;若差额大于阈值(由DefaultMQPushConsumer. consumeConcurrentlyMaxSpan指定,默认是2000),则调用PullMessageService.executePullRequestLater方法,在50毫秒之后重新将该PullRequest请求放入PullMessageService.pullRequestQueue队列中;并跳出该方法;这里的意思主要就是消息有堆积了,等会再来拉取</span></span><br><span class=line> <span class=keyword>if</span> (!<span class=built_in>this</span>.consumeOrderly) {</span><br><span class=line> <span class=keyword>if</span> (processQueue.getMaxSpan() > <span class=built_in>this</span>.defaultMQPushConsumer.getConsumeConcurrentlyMaxSpan()) {</span><br><span class=line> <span class=built_in>this</span>.executePullRequestLater(pullRequest, PULL_TIME_DELAY_MILLS_WHEN_FLOW_CONTROL);</span><br><span class=line> <span class=keyword>if</span> ((queueMaxSpanFlowControlTimes++ % <span class=number>1000</span>) == <span class=number>0</span>) {</span><br><span class=line> log.warn(</span><br><span class=line> <span class=string>"the queue's messages, span too long, so do flow control, minOffset={}, maxOffset={}, maxSpan={}, pullRequest={}, flowControlTimes={}"</span>,</span><br><span class=line> processQueue.getMsgTreeMap().firstKey(), processQueue.getMsgTreeMap().lastKey(), processQueue.getMaxSpan(),</span><br><span class=line> pullRequest, queueMaxSpanFlowControlTimes);</span><br><span class=line> }</span><br><span class=line> <span class=keyword>return</span>;</span><br><span class=line> }</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> <span class=keyword>if</span> (processQueue.isLocked()) {</span><br><span class=line> <span class=keyword>if</span> (!pullRequest.isLockedFirst()) {</span><br><span class=line> <span class=keyword>final</span> <span class=type>long</span> <span class=variable>offset</span> <span class=operator>=</span> <span class=built_in>this</span>.rebalanceImpl.computePullFromWhere(pullRequest.getMessageQueue());</span><br><span class=line> <span class=type>boolean</span> <span class=variable>brokerBusy</span> <span class=operator>=</span> offset < pullRequest.getNextOffset();</span><br><span class=line> log.info(<span class=string>"the first time to pull message, so fix offset from broker. pullRequest: {} NewOffset: {} brokerBusy: {}"</span>,</span><br><span class=line> pullRequest, offset, brokerBusy);</span><br><span class=line> <span class=keyword>if</span> (brokerBusy) {</span><br><span class=line> log.info(<span class=string>"[NOTIFYME]the first time to pull message, but pull request offset larger than broker consume offset. pullRequest: {} NewOffset: {}"</span>,</span><br><span class=line> pullRequest, offset);</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> pullRequest.setLockedFirst(<span class=literal>true</span>);</span><br><span class=line> pullRequest.setNextOffset(offset);</span><br><span class=line> }</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> <span class=built_in>this</span>.executePullRequestLater(pullRequest, pullTimeDelayMillsWhenException);</span><br><span class=line> log.info(<span class=string>"pull message later because not locked in broker, {}"</span>, pullRequest);</span><br><span class=line> <span class=keyword>return</span>;</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=comment>// 以PullRequest.messageQueue对象的topic值为参数从RebalanceImpl.subscriptionInner: ConcurrentHashMap, SubscriptionData>中获取对应的SubscriptionData对象,若该对象为null,考虑到并发的关系,调用executePullRequestLater方法,稍后重试;并跳出该方法;</span></span><br><span class=line> <span class=keyword>final</span> <span class=type>SubscriptionData</span> <span class=variable>subscriptionData</span> <span class=operator>=</span> <span class=built_in>this</span>.rebalanceImpl.getSubscriptionInner().get(pullRequest.getMessageQueue().getTopic());</span><br><span class=line> <span class=keyword>if</span> (<span class=literal>null</span> == subscriptionData) {</span><br><span class=line> <span class=built_in>this</span>.executePullRequestLater(pullRequest, pullTimeDelayMillsWhenException);</span><br><span class=line> log.warn(<span class=string>"find the consumer's subscription failed, {}"</span>, pullRequest);</span><br><span class=line> <span class=keyword>return</span>;</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=keyword>final</span> <span class=type>long</span> <span class=variable>beginTimestamp</span> <span class=operator>=</span> System.currentTimeMillis();</span><br><span class=line></span><br><span class=line> <span class=comment>// 异步拉取回调,先不讨论细节</span></span><br><span class=line> <span class=type>PullCallback</span> <span class=variable>pullCallback</span> <span class=operator>=</span> <span class=keyword>new</span> <span class="title class_">PullCallback</span>() {</span><br><span class=line> <span class=meta>@Override</span></span><br><span class=line> <span class=keyword>public</span> <span class=keyword>void</span> <span class="title function_">onSuccess</span><span class=params>(PullResult pullResult)</span> {</span><br><span class=line> <span class=keyword>if</span> (pullResult != <span class=literal>null</span>) {</span><br><span class=line> pullResult = DefaultMQPushConsumerImpl.<span class=built_in>this</span>.pullAPIWrapper.processPullResult(pullRequest.getMessageQueue(), pullResult,</span><br><span class=line> subscriptionData);</span><br><span class=line></span><br><span class=line> <span class=keyword>switch</span> (pullResult.getPullStatus()) {</span><br><span class=line> <span class=keyword>case</span> FOUND:</span><br><span class=line> <span class=type>long</span> <span class=variable>prevRequestOffset</span> <span class=operator>=</span> pullRequest.getNextOffset();</span><br><span class=line> pullRequest.setNextOffset(pullResult.getNextBeginOffset());</span><br><span class=line> <span class=type>long</span> <span class=variable>pullRT</span> <span class=operator>=</span> System.currentTimeMillis() - beginTimestamp;</span><br><span class=line> DefaultMQPushConsumerImpl.<span class=built_in>this</span>.getConsumerStatsManager().incPullRT(pullRequest.getConsumerGroup(),</span><br><span class=line> pullRequest.getMessageQueue().getTopic(), pullRT);</span><br><span class=line></span><br><span class=line> <span class=type>long</span> <span class=variable>firstMsgOffset</span> <span class=operator>=</span> Long.MAX_VALUE;</span><br><span class=line> <span class=keyword>if</span> (pullResult.getMsgFoundList() == <span class=literal>null</span> || pullResult.getMsgFoundList().isEmpty()) {</span><br><span class=line> DefaultMQPushConsumerImpl.<span class=built_in>this</span>.executePullRequestImmediately(pullRequest);</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> firstMsgOffset = pullResult.getMsgFoundList().get(<span class=number>0</span>).getQueueOffset();</span><br><span class=line></span><br><span class=line> DefaultMQPushConsumerImpl.<span class=built_in>this</span>.getConsumerStatsManager().incPullTPS(pullRequest.getConsumerGroup(),</span><br><span class=line> pullRequest.getMessageQueue().getTopic(), pullResult.getMsgFoundList().size());</span><br><span class=line></span><br><span class=line> <span class=type>boolean</span> <span class=variable>dispatchToConsume</span> <span class=operator>=</span> processQueue.putMessage(pullResult.getMsgFoundList());</span><br><span class=line> DefaultMQPushConsumerImpl.<span class=built_in>this</span>.consumeMessageService.submitConsumeRequest(</span><br><span class=line> pullResult.getMsgFoundList(),</span><br><span class=line> processQueue,</span><br><span class=line> pullRequest.getMessageQueue(),</span><br><span class=line> dispatchToConsume);</span><br><span class=line></span><br><span class=line> <span class=keyword>if</span> (DefaultMQPushConsumerImpl.<span class=built_in>this</span>.defaultMQPushConsumer.getPullInterval() > <span class=number>0</span>) {</span><br><span class=line> DefaultMQPushConsumerImpl.<span class=built_in>this</span>.executePullRequestLater(pullRequest,</span><br><span class=line> DefaultMQPushConsumerImpl.<span class=built_in>this</span>.defaultMQPushConsumer.getPullInterval());</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> DefaultMQPushConsumerImpl.<span class=built_in>this</span>.executePullRequestImmediately(pullRequest);</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=keyword>if</span> (pullResult.getNextBeginOffset() < prevRequestOffset</span><br><span class=line> || firstMsgOffset < prevRequestOffset) {</span><br><span class=line> log.warn(</span><br><span class=line> <span class=string>"[BUG] pull message result maybe data wrong, nextBeginOffset: {} firstMsgOffset: {} prevRequestOffset: {}"</span>,</span><br><span class=line> pullResult.getNextBeginOffset(),</span><br><span class=line> firstMsgOffset,</span><br><span class=line> prevRequestOffset);</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=keyword>break</span>;</span><br><span class=line> <span class=keyword>case</span> NO_NEW_MSG:</span><br><span class=line> pullRequest.setNextOffset(pullResult.getNextBeginOffset());</span><br><span class=line></span><br><span class=line> DefaultMQPushConsumerImpl.<span class=built_in>this</span>.correctTagsOffset(pullRequest);</span><br><span class=line></span><br><span class=line> DefaultMQPushConsumerImpl.<span class=built_in>this</span>.executePullRequestImmediately(pullRequest);</span><br><span class=line> <span class=keyword>break</span>;</span><br><span class=line> <span class=keyword>case</span> NO_MATCHED_MSG:</span><br><span class=line> pullRequest.setNextOffset(pullResult.getNextBeginOffset());</span><br><span class=line></span><br><span class=line> DefaultMQPushConsumerImpl.<span class=built_in>this</span>.correctTagsOffset(pullRequest);</span><br><span class=line></span><br><span class=line> DefaultMQPushConsumerImpl.<span class=built_in>this</span>.executePullRequestImmediately(pullRequest);</span><br><span class=line> <span class=keyword>break</span>;</span><br><span class=line> <span class=keyword>case</span> OFFSET_ILLEGAL:</span><br><span class=line> log.warn(<span class=string>"the pull request offset illegal, {} {}"</span>,</span><br><span class=line> pullRequest.toString(), pullResult.toString());</span><br><span class=line> pullRequest.setNextOffset(pullResult.getNextBeginOffset());</span><br><span class=line></span><br><span class=line> pullRequest.getProcessQueue().setDropped(<span class=literal>true</span>);</span><br><span class=line> DefaultMQPushConsumerImpl.<span class=built_in>this</span>.executeTaskLater(<span class=keyword>new</span> <span class="title class_">Runnable</span>() {</span><br><span class=line></span><br><span class=line> <span class=meta>@Override</span></span><br><span class=line> <span class=keyword>public</span> <span class=keyword>void</span> <span class="title function_">run</span><span class=params>()</span> {</span><br><span class=line> <span class=keyword>try</span> {</span><br><span class=line> DefaultMQPushConsumerImpl.<span class=built_in>this</span>.offsetStore.updateOffset(pullRequest.getMessageQueue(),</span><br><span class=line> pullRequest.getNextOffset(), <span class=literal>false</span>);</span><br><span class=line></span><br><span class=line> DefaultMQPushConsumerImpl.<span class=built_in>this</span>.offsetStore.persist(pullRequest.getMessageQueue());</span><br><span class=line></span><br><span class=line> DefaultMQPushConsumerImpl.<span class=built_in>this</span>.rebalanceImpl.removeProcessQueue(pullRequest.getMessageQueue());</span><br><span class=line></span><br><span class=line> log.warn(<span class=string>"fix the pull request offset, {}"</span>, pullRequest);</span><br><span class=line> } <span class=keyword>catch</span> (Throwable e) {</span><br><span class=line> log.error(<span class=string>"executeTaskLater Exception"</span>, e);</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line> }, <span class=number>10000</span>);</span><br><span class=line> <span class=keyword>break</span>;</span><br><span class=line> <span class=keyword>default</span>:</span><br><span class=line> <span class=keyword>break</span>;</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=meta>@Override</span></span><br><span class=line> <span class=keyword>public</span> <span class=keyword>void</span> <span class="title function_">onException</span><span class=params>(Throwable e)</span> {</span><br><span class=line> <span class=keyword>if</span> (!pullRequest.getMessageQueue().getTopic().startsWith(MixAll.RETRY_GROUP_TOPIC_PREFIX)) {</span><br><span class=line> log.warn(<span class=string>"execute the pull request exception"</span>, e);</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> DefaultMQPushConsumerImpl.<span class=built_in>this</span>.executePullRequestLater(pullRequest, pullTimeDelayMillsWhenException);</span><br><span class=line> }</span><br><span class=line> };</span><br><span class=line> <span class=comment>// 如果为集群模式,即可置commitOffsetEnable为 true</span></span><br><span class=line> <span class=type>boolean</span> <span class=variable>commitOffsetEnable</span> <span class=operator>=</span> <span class=literal>false</span>;</span><br><span class=line> <span class=type>long</span> <span class=variable>commitOffsetValue</span> <span class=operator>=</span> <span class=number>0L</span>;</span><br><span class=line> <span class=keyword>if</span> (MessageModel.CLUSTERING == <span class=built_in>this</span>.defaultMQPushConsumer.getMessageModel()) {</span><br><span class=line> commitOffsetValue = <span class=built_in>this</span>.offsetStore.readOffset(pullRequest.getMessageQueue(), ReadOffsetType.READ_FROM_MEMORY);</span><br><span class=line> <span class=keyword>if</span> (commitOffsetValue > <span class=number>0</span>) {</span><br><span class=line> commitOffsetEnable = <span class=literal>true</span>;</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=comment>// 将上面获得的commitOffsetEnable更新到订阅关系里</span></span><br><span class=line> <span class=type>String</span> <span class=variable>subExpression</span> <span class=operator>=</span> <span class=literal>null</span>;</span><br><span class=line> <span class=type>boolean</span> <span class=variable>classFilter</span> <span class=operator>=</span> <span class=literal>false</span>;</span><br><span class=line> <span class=type>SubscriptionData</span> <span class=variable>sd</span> <span class=operator>=</span> <span class=built_in>this</span>.rebalanceImpl.getSubscriptionInner().get(pullRequest.getMessageQueue().getTopic());</span><br><span class=line> <span class=keyword>if</span> (sd != <span class=literal>null</span>) {</span><br><span class=line> <span class=keyword>if</span> (<span class=built_in>this</span>.defaultMQPushConsumer.isPostSubscriptionWhenPull() && !sd.isClassFilterMode()) {</span><br><span class=line> subExpression = sd.getSubString();</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> classFilter = sd.isClassFilterMode();</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=comment>// 组成 sysFlag</span></span><br><span class=line> <span class=type>int</span> <span class=variable>sysFlag</span> <span class=operator>=</span> PullSysFlag.buildSysFlag(</span><br><span class=line> commitOffsetEnable, <span class=comment>// commitOffset</span></span><br><span class=line> <span class=literal>true</span>, <span class=comment>// suspend</span></span><br><span class=line> subExpression != <span class=literal>null</span>, <span class=comment>// subscription</span></span><br><span class=line> classFilter <span class=comment>// class filter</span></span><br><span class=line> );</span><br><span class=line> <span class=comment>// 调用真正的拉取消息接口</span></span><br><span class=line> <span class=keyword>try</span> {</span><br><span class=line> <span class=built_in>this</span>.pullAPIWrapper.pullKernelImpl(</span><br><span class=line> pullRequest.getMessageQueue(),</span><br><span class=line> subExpression,</span><br><span class=line> subscriptionData.getExpressionType(),</span><br><span class=line> subscriptionData.getSubVersion(),</span><br><span class=line> pullRequest.getNextOffset(),</span><br><span class=line> <span class=built_in>this</span>.defaultMQPushConsumer.getPullBatchSize(),</span><br><span class=line> sysFlag,</span><br><span class=line> commitOffsetValue,</span><br><span class=line> BROKER_SUSPEND_MAX_TIME_MILLIS,</span><br><span class=line> CONSUMER_TIMEOUT_MILLIS_WHEN_SUSPEND,</span><br><span class=line> CommunicationMode.ASYNC,</span><br><span class=line> pullCallback</span><br><span class=line> );</span><br><span class=line> } <span class=keyword>catch</span> (Exception e) {</span><br><span class=line> log.error(<span class=string>"pullKernelImpl exception"</span>, e);</span><br><span class=line> <span class=built_in>this</span>.executePullRequestLater(pullRequest, pullTimeDelayMillsWhenException);</span><br><span class=line> }</span><br><span class=line> }</span><br></pre></table></figure><p>以下就是拉取消息的底层 api,不够不是特别复杂,主要是在找 broker,和设置请求参数<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br><span class=line>10</span><br><span class=line>11</span><br><span class=line>12</span><br><span class=line>13</span><br><span class=line>14</span><br><span class=line>15</span><br><span class=line>16</span><br><span class=line>17</span><br><span class=line>18</span><br><span class=line>19</span><br><span class=line>20</span><br><span class=line>21</span><br><span class=line>22</span><br><span class=line>23</span><br><span class=line>24</span><br><span class=line>25</span><br><span class=line>26</span><br><span class=line>27</span><br><span class=line>28</span><br><span class=line>29</span><br><span class=line>30</span><br><span class=line>31</span><br><span class=line>32</span><br><span class=line>33</span><br><span class=line>34</span><br><span class=line>35</span><br><span class=line>36</span><br><span class=line>37</span><br><span class=line>38</span><br><span class=line>39</span><br><span class=line>40</span><br><span class=line>41</span><br><span class=line>42</span><br><span class=line>43</span><br><span class=line>44</span><br><span class=line>45</span><br><span class=line>46</span><br><span class=line>47</span><br><span class=line>48</span><br><span class=line>49</span><br><span class=line>50</span><br><span class=line>51</span><br><span class=line>52</span><br><span class=line>53</span><br><span class=line>54</span><br><span class=line>55</span><br><span class=line>56</span><br><span class=line>57</span><br><span class=line>58</span><br><span class=line>59</span><br><span class=line>60</span><br><span class=line>61</span><br><span class=line>62</span><br><span class=line>63</span><br><span class=line>64</span><br><span class=line>65</span><br><span class=line>66</span><br><span class=line>67</span><br><span class=line>68</span><br><span class=line>69</span><br></pre><td class=code><pre><span class=line><span class=keyword>public</span> PullResult <span class="title function_">pullKernelImpl</span><span class=params>(</span></span><br><span class=line><span class=params> <span class=keyword>final</span> MessageQueue mq,</span></span><br><span class=line><span class=params> <span class=keyword>final</span> String subExpression,</span></span><br><span class=line><span class=params> <span class=keyword>final</span> String expressionType,</span></span><br><span class=line><span class=params> <span class=keyword>final</span> <span class=type>long</span> subVersion,</span></span><br><span class=line><span class=params> <span class=keyword>final</span> <span class=type>long</span> offset,</span></span><br><span class=line><span class=params> <span class=keyword>final</span> <span class=type>int</span> maxNums,</span></span><br><span class=line><span class=params> <span class=keyword>final</span> <span class=type>int</span> sysFlag,</span></span><br><span class=line><span class=params> <span class=keyword>final</span> <span class=type>long</span> commitOffset,</span></span><br><span class=line><span class=params> <span class=keyword>final</span> <span class=type>long</span> brokerSuspendMaxTimeMillis,</span></span><br><span class=line><span class=params> <span class=keyword>final</span> <span class=type>long</span> timeoutMillis,</span></span><br><span class=line><span class=params> <span class=keyword>final</span> CommunicationMode communicationMode,</span></span><br><span class=line><span class=params> <span class=keyword>final</span> PullCallback pullCallback</span></span><br><span class=line><span class=params>)</span> <span class=keyword>throws</span> MQClientException, RemotingException, MQBrokerException, InterruptedException {</span><br><span class=line> <span class=type>FindBrokerResult</span> <span class=variable>findBrokerResult</span> <span class=operator>=</span></span><br><span class=line> <span class=built_in>this</span>.mQClientFactory.findBrokerAddressInSubscribe(mq.getBrokerName(),</span><br><span class=line> <span class=built_in>this</span>.recalculatePullFromWhichNode(mq), <span class=literal>false</span>);</span><br><span class=line> <span class=keyword>if</span> (<span class=literal>null</span> == findBrokerResult) {</span><br><span class=line> <span class=built_in>this</span>.mQClientFactory.updateTopicRouteInfoFromNameServer(mq.getTopic());</span><br><span class=line> findBrokerResult =</span><br><span class=line> <span class=built_in>this</span>.mQClientFactory.findBrokerAddressInSubscribe(mq.getBrokerName(),</span><br><span class=line> <span class=built_in>this</span>.recalculatePullFromWhichNode(mq), <span class=literal>false</span>);</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=keyword>if</span> (findBrokerResult != <span class=literal>null</span>) {</span><br><span class=line> {</span><br><span class=line> <span class=comment>// check version</span></span><br><span class=line> <span class=keyword>if</span> (!ExpressionType.isTagType(expressionType)</span><br><span class=line> && findBrokerResult.getBrokerVersion() < MQVersion.Version.V4_1_0_SNAPSHOT.ordinal()) {</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">MQClientException</span>(<span class=string>"The broker["</span> + mq.getBrokerName() + <span class=string>", "</span></span><br><span class=line> + findBrokerResult.getBrokerVersion() + <span class=string>"] does not upgrade to support for filter message by "</span> + expressionType, <span class=literal>null</span>);</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line> <span class=type>int</span> <span class=variable>sysFlagInner</span> <span class=operator>=</span> sysFlag;</span><br><span class=line></span><br><span class=line> <span class=keyword>if</span> (findBrokerResult.isSlave()) {</span><br><span class=line> sysFlagInner = PullSysFlag.clearCommitOffsetFlag(sysFlagInner);</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=type>PullMessageRequestHeader</span> <span class=variable>requestHeader</span> <span class=operator>=</span> <span class=keyword>new</span> <span class="title class_">PullMessageRequestHeader</span>();</span><br><span class=line> requestHeader.setConsumerGroup(<span class=built_in>this</span>.consumerGroup);</span><br><span class=line> requestHeader.setTopic(mq.getTopic());</span><br><span class=line> requestHeader.setQueueId(mq.getQueueId());</span><br><span class=line> requestHeader.setQueueOffset(offset);</span><br><span class=line> requestHeader.setMaxMsgNums(maxNums);</span><br><span class=line> requestHeader.setSysFlag(sysFlagInner);</span><br><span class=line> requestHeader.setCommitOffset(commitOffset);</span><br><span class=line> requestHeader.setSuspendTimeoutMillis(brokerSuspendMaxTimeMillis);</span><br><span class=line> requestHeader.setSubscription(subExpression);</span><br><span class=line> requestHeader.setSubVersion(subVersion);</span><br><span class=line> requestHeader.setExpressionType(expressionType);</span><br><span class=line></span><br><span class=line> <span class=type>String</span> <span class=variable>brokerAddr</span> <span class=operator>=</span> findBrokerResult.getBrokerAddr();</span><br><span class=line> <span class=keyword>if</span> (PullSysFlag.hasClassFilterFlag(sysFlagInner)) {</span><br><span class=line> brokerAddr = computPullFromWhichFilterServer(mq.getTopic(), brokerAddr);</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=type>PullResult</span> <span class=variable>pullResult</span> <span class=operator>=</span> <span class=built_in>this</span>.mQClientFactory.getMQClientAPIImpl().pullMessage(</span><br><span class=line> brokerAddr,</span><br><span class=line> requestHeader,</span><br><span class=line> timeoutMillis,</span><br><span class=line> communicationMode,</span><br><span class=line> pullCallback);</span><br><span class=line></span><br><span class=line> <span class=keyword>return</span> pullResult;</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">MQClientException</span>(<span class=string>"The broker["</span> + mq.getBrokerName() + <span class=string>"] not exist"</span>, <span class=literal>null</span>);</span><br><span class=line>}</span><br></pre></table></figure><p>再看下一步的<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br><span class=line>10</span><br><span class=line>11</span><br><span class=line>12</span><br><span class=line>13</span><br><span class=line>14</span><br><span class=line>15</span><br><span class=line>16</span><br><span class=line>17</span><br><span class=line>18</span><br><span class=line>19</span><br><span class=line>20</span><br><span class=line>21</span><br><span class=line>22</span><br><span class=line>23</span><br><span class=line>24</span><br><span class=line>25</span><br></pre><td class=code><pre><span class=line><span class=keyword>public</span> PullResult <span class="title function_">pullMessage</span><span class=params>(</span></span><br><span class=line><span class=params> <span class=keyword>final</span> String addr,</span></span><br><span class=line><span class=params> <span class=keyword>final</span> PullMessageRequestHeader requestHeader,</span></span><br><span class=line><span class=params> <span class=keyword>final</span> <span class=type>long</span> timeoutMillis,</span></span><br><span class=line><span class=params> <span class=keyword>final</span> CommunicationMode communicationMode,</span></span><br><span class=line><span class=params> <span class=keyword>final</span> PullCallback pullCallback</span></span><br><span class=line><span class=params>)</span> <span class=keyword>throws</span> RemotingException, MQBrokerException, InterruptedException {</span><br><span class=line> <span class=type>RemotingCommand</span> <span class=variable>request</span> <span class=operator>=</span> RemotingCommand.createRequestCommand(RequestCode.PULL_MESSAGE, requestHeader);</span><br><span class=line></span><br><span class=line> <span class=keyword>switch</span> (communicationMode) {</span><br><span class=line> <span class=keyword>case</span> ONEWAY:</span><br><span class=line> <span class=keyword>assert</span> <span class=literal>false</span>;</span><br><span class=line> <span class=keyword>return</span> <span class=literal>null</span>;</span><br><span class=line> <span class=keyword>case</span> ASYNC:</span><br><span class=line> <span class=built_in>this</span>.pullMessageAsync(addr, request, timeoutMillis, pullCallback);</span><br><span class=line> <span class=keyword>return</span> <span class=literal>null</span>;</span><br><span class=line> <span class=keyword>case</span> SYNC:</span><br><span class=line> <span class=keyword>return</span> <span class=built_in>this</span>.pullMessageSync(addr, request, timeoutMillis);</span><br><span class=line> <span class=keyword>default</span>:</span><br><span class=line> <span class=keyword>assert</span> <span class=literal>false</span>;</span><br><span class=line> <span class=keyword>break</span>;</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=keyword>return</span> <span class=literal>null</span>;</span><br><span class=line>}</span><br></pre></table></figure><p>通过 communicationMode 判断是同步拉取还是异步拉取,异步就调用<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br><span class=line>10</span><br><span class=line>11</span><br><span class=line>12</span><br><span class=line>13</span><br><span class=line>14</span><br><span class=line>15</span><br><span class=line>16</span><br><span class=line>17</span><br><span class=line>18</span><br><span class=line>19</span><br><span class=line>20</span><br><span class=line>21</span><br><span class=line>22</span><br><span class=line>23</span><br><span class=line>24</span><br><span class=line>25</span><br><span class=line>26</span><br><span class=line>27</span><br><span class=line>28</span><br><span class=line>29</span><br><span class=line>30</span><br><span class=line>31</span><br><span class=line>32</span><br></pre><td class=code><pre><span class=line><span class=keyword>private</span> <span class=keyword>void</span> <span class="title function_">pullMessageAsync</span><span class=params>(</span></span><br><span class=line><span class=params> <span class=keyword>final</span> String addr,</span></span><br><span class=line><span class=params> <span class=keyword>final</span> RemotingCommand request,</span></span><br><span class=line><span class=params> <span class=keyword>final</span> <span class=type>long</span> timeoutMillis,</span></span><br><span class=line><span class=params> <span class=keyword>final</span> PullCallback pullCallback</span></span><br><span class=line><span class=params> )</span> <span class=keyword>throws</span> RemotingException, InterruptedException {</span><br><span class=line> <span class=built_in>this</span>.remotingClient.invokeAsync(addr, request, timeoutMillis, <span class=keyword>new</span> <span class="title class_">InvokeCallback</span>() {</span><br><span class=line> <span class=meta>@Override</span></span><br><span class=line> <span class=keyword>public</span> <span class=keyword>void</span> <span class="title function_">operationComplete</span><span class=params>(ResponseFuture responseFuture)</span> {</span><br><span class=line> 异步</span><br><span class=line> <span class=type>RemotingCommand</span> <span class=variable>response</span> <span class=operator>=</span> responseFuture.getResponseCommand();</span><br><span class=line> <span class=keyword>if</span> (response != <span class=literal>null</span>) {</span><br><span class=line> <span class=keyword>try</span> {</span><br><span class=line> <span class=type>PullResult</span> <span class=variable>pullResult</span> <span class=operator>=</span> MQClientAPIImpl.<span class=built_in>this</span>.processPullResponse(response);</span><br><span class=line> <span class=keyword>assert</span> pullResult != <span class=literal>null</span>;</span><br><span class=line> pullCallback.onSuccess(pullResult);</span><br><span class=line> } <span class=keyword>catch</span> (Exception e) {</span><br><span class=line> pullCallback.onException(e);</span><br><span class=line> }</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> <span class=keyword>if</span> (!responseFuture.isSendRequestOK()) {</span><br><span class=line> pullCallback.onException(<span class=keyword>new</span> <span class="title class_">MQClientException</span>(<span class=string>"send request failed to "</span> + addr + <span class=string>". Request: "</span> + request, responseFuture.getCause()));</span><br><span class=line> } <span class=keyword>else</span> <span class=keyword>if</span> (responseFuture.isTimeout()) {</span><br><span class=line> pullCallback.onException(<span class=keyword>new</span> <span class="title class_">MQClientException</span>(<span class=string>"wait response from "</span> + addr + <span class=string>" timeout :"</span> + responseFuture.getTimeoutMillis() + <span class=string>"ms"</span> + <span class=string>". Request: "</span> + request,</span><br><span class=line> responseFuture.getCause()));</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> pullCallback.onException(<span class=keyword>new</span> <span class="title class_">MQClientException</span>(<span class=string>"unknown reason. addr: "</span> + addr + <span class=string>", timeoutMillis: "</span> + timeoutMillis + <span class=string>". Request: "</span> + request, responseFuture.getCause()));</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line> });</span><br><span class=line> }</span><br></pre></table></figure><p>并且会调用前面 pullCallback 的onSuccess和onException方法,同步的就是调用<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br></pre><td class=code><pre><span class=line><span class=keyword>private</span> PullResult <span class="title function_">pullMessageSync</span><span class=params>(</span></span><br><span class=line><span class=params> <span class=keyword>final</span> String addr,</span></span><br><span class=line><span class=params> <span class=keyword>final</span> RemotingCommand request,</span></span><br><span class=line><span class=params> <span class=keyword>final</span> <span class=type>long</span> timeoutMillis</span></span><br><span class=line><span class=params> )</span> <span class=keyword>throws</span> RemotingException, InterruptedException, MQBrokerException {</span><br><span class=line> <span class=type>RemotingCommand</span> <span class=variable>response</span> <span class=operator>=</span> <span class=built_in>this</span>.remotingClient.invokeSync(addr, request, timeoutMillis);</span><br><span class=line> <span class=keyword>assert</span> response != <span class=literal>null</span>;</span><br><span class=line> <span class=keyword>return</span> <span class=built_in>this</span>.processPullResponse(response);</span><br><span class=line> }</span><br></pre></table></figure><p>然后就是这个 remotingClient 的 invokeAsync 跟 invokeSync 方法<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br><span class=line>10</span><br><span class=line>11</span><br><span class=line>12</span><br><span class=line>13</span><br><span class=line>14</span><br><span class=line>15</span><br><span class=line>16</span><br><span class=line>17</span><br><span class=line>18</span><br><span class=line>19</span><br><span class=line>20</span><br><span class=line>21</span><br><span class=line>22</span><br><span class=line>23</span><br><span class=line>24</span><br><span class=line>25</span><br><span class=line>26</span><br><span class=line>27</span><br><span class=line>28</span><br><span class=line>29</span><br><span class=line>30</span><br><span class=line>31</span><br><span class=line>32</span><br><span class=line>33</span><br><span class=line>34</span><br><span class=line>35</span><br><span class=line>36</span><br><span class=line>37</span><br><span class=line>38</span><br><span class=line>39</span><br><span class=line>40</span><br><span class=line>41</span><br><span class=line>42</span><br><span class=line>43</span><br><span class=line>44</span><br><span class=line>45</span><br><span class=line>46</span><br><span class=line>47</span><br><span class=line>48</span><br><span class=line>49</span><br><span class=line>50</span><br><span class=line>51</span><br><span class=line>52</span><br><span class=line>53</span><br><span class=line>54</span><br><span class=line>55</span><br><span class=line>56</span><br></pre><td class=code><pre><span class=line><span class=meta>@Override</span></span><br><span class=line> <span class=keyword>public</span> <span class=keyword>void</span> <span class="title function_">invokeAsync</span><span class=params>(String addr, RemotingCommand request, <span class=type>long</span> timeoutMillis, InvokeCallback invokeCallback)</span></span><br><span class=line> <span class=keyword>throws</span> InterruptedException, RemotingConnectException, RemotingTooMuchRequestException, RemotingTimeoutException,</span><br><span class=line> RemotingSendRequestException {</span><br><span class=line> <span class=type>long</span> <span class=variable>beginStartTime</span> <span class=operator>=</span> System.currentTimeMillis();</span><br><span class=line> <span class=keyword>final</span> <span class=type>Channel</span> <span class=variable>channel</span> <span class=operator>=</span> <span class=built_in>this</span>.getAndCreateChannel(addr);</span><br><span class=line> <span class=keyword>if</span> (channel != <span class=literal>null</span> && channel.isActive()) {</span><br><span class=line> <span class=keyword>try</span> {</span><br><span class=line> doBeforeRpcHooks(addr, request);</span><br><span class=line> <span class=type>long</span> <span class=variable>costTime</span> <span class=operator>=</span> System.currentTimeMillis() - beginStartTime;</span><br><span class=line> <span class=keyword>if</span> (timeoutMillis < costTime) {</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">RemotingTooMuchRequestException</span>(<span class=string>"invokeAsync call timeout"</span>);</span><br><span class=line> }</span><br><span class=line> <span class=built_in>this</span>.invokeAsyncImpl(channel, request, timeoutMillis - costTime, invokeCallback);</span><br><span class=line> } <span class=keyword>catch</span> (RemotingSendRequestException e) {</span><br><span class=line> log.warn(<span class=string>"invokeAsync: send request exception, so close the channel[{}]"</span>, addr);</span><br><span class=line> <span class=built_in>this</span>.closeChannel(addr, channel);</span><br><span class=line> <span class=keyword>throw</span> e;</span><br><span class=line> }</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> <span class=built_in>this</span>.closeChannel(addr, channel);</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">RemotingConnectException</span>(addr);</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line><span class=meta>@Override</span></span><br><span class=line> <span class=keyword>public</span> RemotingCommand <span class="title function_">invokeSync</span><span class=params>(String addr, <span class=keyword>final</span> RemotingCommand request, <span class=type>long</span> timeoutMillis)</span></span><br><span class=line> <span class=keyword>throws</span> InterruptedException, RemotingConnectException, RemotingSendRequestException, RemotingTimeoutException {</span><br><span class=line> <span class=type>long</span> <span class=variable>beginStartTime</span> <span class=operator>=</span> System.currentTimeMillis();</span><br><span class=line> <span class=keyword>final</span> <span class=type>Channel</span> <span class=variable>channel</span> <span class=operator>=</span> <span class=built_in>this</span>.getAndCreateChannel(addr);</span><br><span class=line> <span class=keyword>if</span> (channel != <span class=literal>null</span> && channel.isActive()) {</span><br><span class=line> <span class=keyword>try</span> {</span><br><span class=line> doBeforeRpcHooks(addr, request);</span><br><span class=line> <span class=type>long</span> <span class=variable>costTime</span> <span class=operator>=</span> System.currentTimeMillis() - beginStartTime;</span><br><span class=line> <span class=keyword>if</span> (timeoutMillis < costTime) {</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">RemotingTimeoutException</span>(<span class=string>"invokeSync call timeout"</span>);</span><br><span class=line> }</span><br><span class=line> <span class=type>RemotingCommand</span> <span class=variable>response</span> <span class=operator>=</span> <span class=built_in>this</span>.invokeSyncImpl(channel, request, timeoutMillis - costTime);</span><br><span class=line> doAfterRpcHooks(RemotingHelper.parseChannelRemoteAddr(channel), request, response);</span><br><span class=line> <span class=keyword>return</span> response;</span><br><span class=line> } <span class=keyword>catch</span> (RemotingSendRequestException e) {</span><br><span class=line> log.warn(<span class=string>"invokeSync: send request exception, so close the channel[{}]"</span>, addr);</span><br><span class=line> <span class=built_in>this</span>.closeChannel(addr, channel);</span><br><span class=line> <span class=keyword>throw</span> e;</span><br><span class=line> } <span class=keyword>catch</span> (RemotingTimeoutException e) {</span><br><span class=line> <span class=keyword>if</span> (nettyClientConfig.isClientCloseSocketIfTimeout()) {</span><br><span class=line> <span class=built_in>this</span>.closeChannel(addr, channel);</span><br><span class=line> log.warn(<span class=string>"invokeSync: close socket because of timeout, {}ms, {}"</span>, timeoutMillis, addr);</span><br><span class=line> }</span><br><span class=line> log.warn(<span class=string>"invokeSync: wait response timeout exception, the channel[{}]"</span>, addr);</span><br><span class=line> <span class=keyword>throw</span> e;</span><br><span class=line> }</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> <span class=built_in>this</span>.closeChannel(addr, channel);</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">RemotingConnectException</span>(addr);</span><br><span class=line> }</span><br><span class=line> }</span><br></pre></table></figure><p>再往下看<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br><span class=line>10</span><br><span class=line>11</span><br><span class=line>12</span><br><span class=line>13</span><br><span class=line>14</span><br><span class=line>15</span><br><span class=line>16</span><br><span class=line>17</span><br><span class=line>18</span><br><span class=line>19</span><br><span class=line>20</span><br><span class=line>21</span><br><span class=line>22</span><br><span class=line>23</span><br><span class=line>24</span><br><span class=line>25</span><br><span class=line>26</span><br><span class=line>27</span><br><span class=line>28</span><br><span class=line>29</span><br><span class=line>30</span><br><span class=line>31</span><br><span class=line>32</span><br><span class=line>33</span><br><span class=line>34</span><br><span class=line>35</span><br><span class=line>36</span><br><span class=line>37</span><br><span class=line>38</span><br><span class=line>39</span><br><span class=line>40</span><br><span class=line>41</span><br><span class=line>42</span><br><span class=line>43</span><br><span class=line>44</span><br><span class=line>45</span><br><span class=line>46</span><br><span class=line>47</span><br><span class=line>48</span><br><span class=line>49</span><br><span class=line>50</span><br><span class=line>51</span><br><span class=line>52</span><br><span class=line>53</span><br><span class=line>54</span><br><span class=line>55</span><br><span class=line>56</span><br><span class=line>57</span><br><span class=line>58</span><br><span class=line>59</span><br><span class=line>60</span><br><span class=line>61</span><br><span class=line>62</span><br><span class=line>63</span><br><span class=line>64</span><br><span class=line>65</span><br><span class=line>66</span><br><span class=line>67</span><br><span class=line>68</span><br><span class=line>69</span><br><span class=line>70</span><br><span class=line>71</span><br><span class=line>72</span><br><span class=line>73</span><br><span class=line>74</span><br><span class=line>75</span><br><span class=line>76</span><br><span class=line>77</span><br><span class=line>78</span><br><span class=line>79</span><br><span class=line>80</span><br><span class=line>81</span><br><span class=line>82</span><br><span class=line>83</span><br><span class=line>84</span><br><span class=line>85</span><br><span class=line>86</span><br><span class=line>87</span><br><span class=line>88</span><br><span class=line>89</span><br><span class=line>90</span><br><span class=line>91</span><br></pre><td class=code><pre><span class=line><span class=keyword>public</span> RemotingCommand <span class="title function_">invokeSyncImpl</span><span class=params>(<span class=keyword>final</span> Channel channel, <span class=keyword>final</span> RemotingCommand request,</span></span><br><span class=line><span class=params> <span class=keyword>final</span> <span class=type>long</span> timeoutMillis)</span></span><br><span class=line> <span class=keyword>throws</span> InterruptedException, RemotingSendRequestException, RemotingTimeoutException {</span><br><span class=line> <span class=keyword>final</span> <span class=type>int</span> <span class=variable>opaque</span> <span class=operator>=</span> request.getOpaque();</span><br><span class=line></span><br><span class=line> <span class=keyword>try</span> {</span><br><span class=line> 同步跟异步都是会把结果用ResponseFuture抱起来</span><br><span class=line> <span class=keyword>final</span> <span class=type>ResponseFuture</span> <span class=variable>responseFuture</span> <span class=operator>=</span> <span class=keyword>new</span> <span class="title class_">ResponseFuture</span>(channel, opaque, timeoutMillis, <span class=literal>null</span>, <span class=literal>null</span>);</span><br><span class=line> <span class=built_in>this</span>.responseTable.put(opaque, responseFuture);</span><br><span class=line> <span class=keyword>final</span> <span class=type>SocketAddress</span> <span class=variable>addr</span> <span class=operator>=</span> channel.remoteAddress();</span><br><span class=line> channel.writeAndFlush(request).addListener(<span class=keyword>new</span> <span class="title class_">ChannelFutureListener</span>() {</span><br><span class=line> <span class=meta>@Override</span></span><br><span class=line> <span class=keyword>public</span> <span class=keyword>void</span> <span class="title function_">operationComplete</span><span class=params>(ChannelFuture f)</span> <span class=keyword>throws</span> Exception {</span><br><span class=line> <span class=keyword>if</span> (f.isSuccess()) {</span><br><span class=line> responseFuture.setSendRequestOK(<span class=literal>true</span>);</span><br><span class=line> <span class=keyword>return</span>;</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> responseFuture.setSendRequestOK(<span class=literal>false</span>);</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> responseTable.remove(opaque);</span><br><span class=line> responseFuture.setCause(f.cause());</span><br><span class=line> responseFuture.putResponse(<span class=literal>null</span>);</span><br><span class=line> log.warn(<span class=string>"send a request command to channel <"</span> + addr + <span class=string>"> failed."</span>);</span><br><span class=line> }</span><br><span class=line> });</span><br><span class=line> <span class=comment>// 区别是同步的是在这等待</span></span><br><span class=line> <span class=type>RemotingCommand</span> <span class=variable>responseCommand</span> <span class=operator>=</span> responseFuture.waitResponse(timeoutMillis);</span><br><span class=line> <span class=keyword>if</span> (<span class=literal>null</span> == responseCommand) {</span><br><span class=line> <span class=keyword>if</span> (responseFuture.isSendRequestOK()) {</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">RemotingTimeoutException</span>(RemotingHelper.parseSocketAddressAddr(addr), timeoutMillis,</span><br><span class=line> responseFuture.getCause());</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">RemotingSendRequestException</span>(RemotingHelper.parseSocketAddressAddr(addr), responseFuture.getCause());</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=keyword>return</span> responseCommand;</span><br><span class=line> } <span class=keyword>finally</span> {</span><br><span class=line> <span class=built_in>this</span>.responseTable.remove(opaque);</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=keyword>public</span> <span class=keyword>void</span> <span class="title function_">invokeAsyncImpl</span><span class=params>(<span class=keyword>final</span> Channel channel, <span class=keyword>final</span> RemotingCommand request, <span class=keyword>final</span> <span class=type>long</span> timeoutMillis,</span></span><br><span class=line><span class=params> <span class=keyword>final</span> InvokeCallback invokeCallback)</span></span><br><span class=line> <span class=keyword>throws</span> InterruptedException, RemotingTooMuchRequestException, RemotingTimeoutException, RemotingSendRequestException {</span><br><span class=line> <span class=type>long</span> <span class=variable>beginStartTime</span> <span class=operator>=</span> System.currentTimeMillis();</span><br><span class=line> <span class=keyword>final</span> <span class=type>int</span> <span class=variable>opaque</span> <span class=operator>=</span> request.getOpaque();</span><br><span class=line> <span class=type>boolean</span> <span class=variable>acquired</span> <span class=operator>=</span> <span class=built_in>this</span>.semaphoreAsync.tryAcquire(timeoutMillis, TimeUnit.MILLISECONDS);</span><br><span class=line> <span class=keyword>if</span> (acquired) {</span><br><span class=line> <span class=keyword>final</span> <span class=type>SemaphoreReleaseOnlyOnce</span> <span class=variable>once</span> <span class=operator>=</span> <span class=keyword>new</span> <span class="title class_">SemaphoreReleaseOnlyOnce</span>(<span class=built_in>this</span>.semaphoreAsync);</span><br><span class=line> <span class=type>long</span> <span class=variable>costTime</span> <span class=operator>=</span> System.currentTimeMillis() - beginStartTime;</span><br><span class=line> <span class=keyword>if</span> (timeoutMillis < costTime) {</span><br><span class=line> once.release();</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">RemotingTimeoutException</span>(<span class=string>"invokeAsyncImpl call timeout"</span>);</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=keyword>final</span> <span class=type>ResponseFuture</span> <span class=variable>responseFuture</span> <span class=operator>=</span> <span class=keyword>new</span> <span class="title class_">ResponseFuture</span>(channel, opaque, timeoutMillis - costTime, invokeCallback, once);</span><br><span class=line> <span class=built_in>this</span>.responseTable.put(opaque, responseFuture);</span><br><span class=line> <span class=keyword>try</span> {</span><br><span class=line> channel.writeAndFlush(request).addListener(<span class=keyword>new</span> <span class="title class_">ChannelFutureListener</span>() {</span><br><span class=line> <span class=meta>@Override</span></span><br><span class=line> <span class=keyword>public</span> <span class=keyword>void</span> <span class="title function_">operationComplete</span><span class=params>(ChannelFuture f)</span> <span class=keyword>throws</span> Exception {</span><br><span class=line> <span class=keyword>if</span> (f.isSuccess()) {</span><br><span class=line> responseFuture.setSendRequestOK(<span class=literal>true</span>);</span><br><span class=line> <span class=keyword>return</span>;</span><br><span class=line> }</span><br><span class=line> requestFail(opaque);</span><br><span class=line> log.warn(<span class=string>"send a request command to channel <{}> failed."</span>, RemotingHelper.parseChannelRemoteAddr(channel));</span><br><span class=line> }</span><br><span class=line> });</span><br><span class=line> } <span class=keyword>catch</span> (Exception e) {</span><br><span class=line> responseFuture.release();</span><br><span class=line> log.warn(<span class=string>"send a request command to channel <"</span> + RemotingHelper.parseChannelRemoteAddr(channel) + <span class=string>"> Exception"</span>, e);</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">RemotingSendRequestException</span>(RemotingHelper.parseChannelRemoteAddr(channel), e);</span><br><span class=line> }</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> <span class=keyword>if</span> (timeoutMillis <= <span class=number>0</span>) {</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">RemotingTooMuchRequestException</span>(<span class=string>"invokeAsyncImpl invoke too fast"</span>);</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> <span class=type>String</span> <span class=variable>info</span> <span class=operator>=</span></span><br><span class=line> String.format(<span class=string>"invokeAsyncImpl tryAcquire semaphore timeout, %dms, waiting thread nums: %d semaphoreAsyncValue: %d"</span>,</span><br><span class=line> timeoutMillis,</span><br><span class=line> <span class=built_in>this</span>.semaphoreAsync.getQueueLength(),</span><br><span class=line> <span class=built_in>this</span>.semaphoreAsync.availablePermits()</span><br><span class=line> );</span><br><span class=line> log.warn(info);</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">RemotingTimeoutException</span>(info);</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line> }</span><br></pre></table></figure></div><footer class=post-footer><div class="affiliate-creative affiliate-creative--post-end" data-affiliate-id=tencent-cloud-general><a rel="sponsored noopener" aria-label=腾讯云产品优惠 href=https://cloud.tencent.com/act/cps/redirect?redirect=2446&cps_key=2e33a1eedb380997d03618b4a5ba6ca7&from=console target=_blank><img alt=腾讯云服务器、数据库和云产品优惠 decoding=async height=419 loading=lazy 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