RocketMQ源码解析：Filtersrv

title: RocketMQ 源码分析 —— Filtersrv
date: 2017-05-17
tags:
categories: RocketMQ
permalink: RocketMQ/filtersrv

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• 1. 概述
• 2. Filtersrv 注册到 Broker
• 3. 过滤类
  
  • 3.1 Consumer 订阅时设置 过滤类代码
  • 3.2 Consumer 上传 过滤类代码
  • 3.3 Filter 编译 过滤类代码
• 4. 过滤消息
  
  • 4.1 Consumer 从 Filtersrv 拉取消息
  • 4.2 Filtersrv 从 Broker 拉取消息
• 5. Filtersrv 高可用

1. 概述

Filtersrv ，负责自定义规则过滤 Consumer 从 Broker 拉取的消息。

为什么 Broker 不提供过滤消息的功能呢？我们来看看官方的说法：

• Broker 端消息过滤
  在 Broker 中，按照 Consumer 的要求做过滤，优点是减少了对于 Consumer 无用消息的网络传输。 缺点是增加了 Broker 的负担，实现相对复杂。
  (1). 淘宝 Notify 支持多种过滤方式，包含直接按照消息类型过滤，灵活的语法表达式过滤，几乎可以满足最苛刻的过滤需求。
  (2). 淘宝 RocketMQ 支持按照简单的 Message Tag 过滤，也支持按照 Message Header、body 进行过滤。
  (3). CORBA Notification 规范中也支持灵活的语法表达式过滤。
• Consumer 端消息过滤
  这种过滤方式可由应用完全自定义实现，但是缺点是很多无用的消息要传输到 Consumer 端。

就是在这种考虑下，Filtersrv 出现了。减少了 Broker 的负担，又减少了 Consumer 接收无用的消息。当然缺点也是有的，多了一层 Filtersrv 网络开销。

2. Filtersrv 注册到 Broker

• �� 一个 Filtersrv 只对应一个 Broker。
• �� 一个 Broker 可以对应多个 Filtersrv。Filtersrv 的高可用通过启动多个 Filtersrv 实现。
• �� Filtersrv 注册失败时，主动退出关闭。

核心代码如下：

  1: // ⬇️⬇️⬇️【FiltersrvController.java】  2: public boolean initialize() {  3:     // ....(省略代码)  4:   5:     // 固定间隔注册到Broker  6:     this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {  7:   8:         @Override  9:         public void run() { 10:             FiltersrvController.this.registerFilterServerToBroker(); 11:         } 12:     }, 15, 10, TimeUnit.SECONDS); // TODO edit by 芋艿：initialDelay时间太短，可能导致初始化失败。从3=》15 13:  14:     // ....(省略代码) 15: } 16:  17: /** 18:  * 注册Filtersrv 到 Broker 19:  * ！！！如果注册失败，关闭Filtersrv 20:  */ 21: public void registerFilterServerToBroker() { 22:     try { 23:         RegisterFilterServerResponseHeader responseHeader = 24:             this.filterServerOuterAPI.registerFilterServerToBroker( 25:                 this.filtersrvConfig.getConnectWhichBroker(), this.localAddr()); 26:         this.defaultMQPullConsumer.getDefaultMQPullConsumerImpl().getPullAPIWrapper() 27:             .setDefaultBrokerId(responseHeader.getBrokerId()); 28:  29:         if (null == this.brokerName) { 30:             this.brokerName = responseHeader.getBrokerName(); 31:         } 32:  33:         log.info("register filter server<{}> to broker<{}> OK, Return: {} {}", 34:             this.localAddr(), 35:             this.filtersrvConfig.getConnectWhichBroker(), 36:             responseHeader.getBrokerName(), 37:             responseHeader.getBrokerId()); 38:     } catch (Exception e) { 39:         log.warn("register filter server Exception", e); 40:  41:         log.warn("access broker failed, kill oneself"); 42:         System.exit(-1); // 异常退出 43:     } 44: }

3. 过滤类

3.1 Consumer 订阅时设置 过滤类代码

• �� Consumer 针对每个 Topic 可以订阅不同的 过滤类代码。

  1: // ⬇️⬇️⬇️【DefaultMQPushConsumer.java】  2: @Override  3: public void subscribe(String topic, String fullClassName, String filterClassSource) throws MQClientException {  4:     this.defaultMQPushConsumerImpl.subscribe(topic, fullClassName, filterClassSource);  5: }

3.2 Consumer 上传 过滤类代码

• �� Consumer 心跳注册到 Broker 的同时，上传 过滤类代码 到 Broker 对应的所有 Filtersrv。

  1: // ⬇️⬇️⬇️【MQClientInstance.java】  2: /**  3:  * 发送心跳到Broker，上传过滤类源码到Filtersrv  4:  */  5: public void sendHeartbeatToAllBrokerWithLock() {  6:     if (this.lockHeartbeat.tryLock()) {  7:         try {  8:             this.sendHeartbeatToAllBroker();  9:             this.uploadFilterClassSource(); 10:         } catch (final Exception e) { 11:             log.error("sendHeartbeatToAllBroker exception", e); 12:         } finally { 13:             this.lockHeartbeat.unlock(); 14:         } 15:     } else { 16:         log.warn("lock heartBeat, but failed."); 17:     } 18: } 19:  20: /** 21:  * 上传过滤类到Filtersrv 22:  */ 23: private void uploadFilterClassSource() { 24:     Iterator<Entry<String, MQConsumerInner>> it = this.consumerTable.entrySet().iterator(); 25:     while (it.hasNext()) { 26:         Entry<String, MQConsumerInner> next = it.next(); 27:         MQConsumerInner consumer = next.getValue(); 28:         if (ConsumeType.CONSUME_PASSIVELY == consumer.consumeType()) { 29:             Set<SubscriptionData> subscriptions = consumer.subscriptions(); 30:             for (SubscriptionData sub : subscriptions) { 31:                 if (sub.isClassFilterMode() && sub.getFilterClassSource() != null) { 32:                     final String consumerGroup = consumer.groupName(); 33:                     final String className = sub.getSubString(); 34:                     final String topic = sub.getTopic(); 35:                     final String filterClassSource = sub.getFilterClassSource(); 36:                     try { 37:                         this.uploadFilterClassToAllFilterServer(consumerGroup, className, topic, filterClassSource); 38:                     } catch (Exception e) { 39:                         log.error("uploadFilterClassToAllFilterServer Exception", e); 40:                     } 41:                 } 42:             } 43:         } 44:     } 45: }

3.3 Filter 编译 过滤类代码

• �� Filtersrv 处理 Consumer 上传的 过滤类代码，并进行编译使用。

核心代码如下：

  1: // ⬇️⬇️⬇️【FilterClassManager.java】  2: /**  3:  * 注册过滤类  4:  *  5:  * @param consumerGroup 消费分组  6:  * @param topic Topic  7:  * @param className 过滤类名  8:  * @param classCRC 过滤类源码CRC  9:  * @param filterSourceBinary 过滤类源码 10:  * @return 是否注册成功 11:  */ 12: public boolean registerFilterClass(final String consumerGroup, final String topic, 13:     final String className, final int classCRC, final byte[] filterSourceBinary) { 14:     final String key = buildKey(consumerGroup, topic); 15:     // 判断是否要注册新的过滤类 16:     boolean registerNew = false; 17:     FilterClassInfo filterClassInfoPrev = this.filterClassTable.get(key); 18:     if (null == filterClassInfoPrev) { 19:         registerNew = true; 20:     } else { 21:         if (this.filtersrvController.getFiltersrvConfig().isClientUploadFilterClassEnable()) { 22:             if (filterClassInfoPrev.getClassCRC() != classCRC && classCRC != 0) { // 类有变化 23:                 registerNew = true; 24:             } 25:         } 26:     } 27:     // 注册新的过滤类 28:     if (registerNew) { 29:         synchronized (this.compileLock) { 30:             filterClassInfoPrev = this.filterClassTable.get(key); 31:             if (null != filterClassInfoPrev && filterClassInfoPrev.getClassCRC() == classCRC) { 32:                 return true; 33:             } 34:             try { 35:                 FilterClassInfo filterClassInfoNew = new FilterClassInfo(); 36:                 filterClassInfoNew.setClassName(className); 37:                 filterClassInfoNew.setClassCRC(0); 38:                 filterClassInfoNew.setMessageFilter(null); 39:  40:                 if (this.filtersrvController.getFiltersrvConfig().isClientUploadFilterClassEnable()) { 41:                     String javaSource = new String(filterSourceBinary, MixAll.DEFAULT_CHARSET); 42:                     // 编译新的过滤类 43:                     Class<?> newClass = DynaCode.compileAndLoadClass(className, javaSource); 44:                     // 创建新的过滤类对象 45:                     Object newInstance = newClass.newInstance(); 46:                     filterClassInfoNew.setMessageFilter((MessageFilter) newInstance); 47:                     filterClassInfoNew.setClassCRC(classCRC); 48:                 } 49:  50:                 this.filterClassTable.put(key, filterClassInfoNew); 51:             } catch (Throwable e) { 52:                 String info = String.format("FilterServer, registerFilterClass Exception, consumerGroup: %s topic: %s className: %s", 53:                             consumerGroup, topic, className); 54:                 log.error(info, e); 55:                 return false; 56:             } 57:         } 58:     } 59:  60:     return true; 61: }

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4. 过滤消息

4.1 Consumer 从 Filtersrv 拉取消息

• �� Consumer 拉取 使用过滤类方式订阅 的消费消息时，从 Broker 对应的 Filtersrv 列表随机选择一个拉取消息。如果选择不到 Filtersrv，则无法拉取消息。因此，Filtersrv 一定要做高可用。

  1: // ⬇️⬇️⬇️【PullAPIWrapper.java】  2: /**  3:  * 拉取消息核心方法  4:  *  5:  * @param mq 消息嘟列  6:  * @param subExpression 订阅表达式  7:  * @param subVersion 订阅版本号  8:  * @param offset 拉取队列开始位置  9:  * @param maxNums 批量拉 取消息数量 10:  * @param sysFlag 拉取系统标识 11:  * @param commitOffset 提交消费进度 12:  * @param brokerSuspendMaxTimeMillis broker挂起请求最大时间 13:  * @param timeoutMillis 请求broker超时时间 14:  * @param communicationMode 通讯模式 15:  * @param pullCallback 拉取回调 16:  * @return 拉取消息结果。只有通讯模式为同步时，才返回结果，否则返回null。 17:  * @throws MQClientException 当寻找不到 broker 时，或发生其他client异常 18:  * @throws RemotingException 当远程调用发生异常时 19:  * @throws MQBrokerException 当 broker 发生异常时。只有通讯模式为同步时才会发生该异常。 20:  * @throws InterruptedException 当发生中断异常时 21:  */ 22: protected PullResult pullKernelImpl( 23:     final MessageQueue mq, 24:     final String subExpression, 25:     final long subVersion, 26:     final long offset, 27:     final int maxNums, 28:     final int sysFlag, 29:     final long commitOffset, 30:     final long brokerSuspendMaxTimeMillis, 31:     final long timeoutMillis, 32:     final CommunicationMode communicationMode, 33:     final PullCallback pullCallback 34: ) throws MQClientException, RemotingException, MQBrokerException, InterruptedException { 35:     // // ....(省略代码) 36:     // 请求拉取消息 37:     if (findBrokerResult != null) { 38:         // ....(省略代码) 39:         // 若订阅topic使用过滤类，使用filtersrv获取消息 40:         String brokerAddr = findBrokerResult.getBrokerAddr(); 41:         if (PullSysFlag.hasClassFilterFlag(sysFlagInner)) { 42:             brokerAddr = computPullFromWhichFilterServer(mq.getTopic(), brokerAddr); 43:         } 44:  45:         PullResult pullResult = this.mQClientFactory.getMQClientAPIImpl().pullMessage( 46:             brokerAddr, 47:             requestHeader, 48:             timeoutMillis, 49:             communicationMode, 50:             pullCallback); 51:  52:         return pullResult; 53:     } 54:  55:     // Broker信息不存在，则抛出异常 56:     throw new MQClientException("The broker[" + mq.getBrokerName() + "] not exist", null); 57: } 58:  59: /** 60:  * 计算filtersrv地址。如果有多个filtersrv，随机选择一个。 61:  * 62:  * @param topic Topic 63:  * @param brokerAddr broker地址 64:  * @return filtersrv地址 65:  * @throws MQClientException 当filtersrv不存在时 66:  */ 67: private String computPullFromWhichFilterServer(final String topic, final String brokerAddr) 68:     throws MQClientException { 69:     ConcurrentHashMap<String, TopicRouteData> topicRouteTable = this.mQClientFactory.getTopicRouteTable(); 70:     if (topicRouteTable != null) { 71:         TopicRouteData topicRouteData = topicRouteTable.get(topic); 72:         List<String> list = topicRouteData.getFilterServerTable().get(brokerAddr); 73:         if (list != null && !list.isEmpty()) { 74:             return list.get(randomNum() % list.size()); 75:         } 76:     } 77:     throw new MQClientException("Find Filter Server Failed, Broker Addr: " + brokerAddr + " topic: " 78:         + topic, null); 79: }

4.2 Filtersrv 从 Broker 拉取消息

• �� Filtersrv 拉取消息后，会建议 Consumer 向 Broker主节点 拉取消息。
• �� Filtersrv 可以理解成一个 Consumer，向 Broker 拉取消息时，实际使用的 DefaultMQPullConsumer.java 的方法和逻辑。

  1: // ⬇️⬇️⬇️【DefaultRequestProcessor.java】  2: /**  3:  * 拉取消息  4:  *  5:  * @param ctx 拉取消息context  6:  * @param request 拉取消息请求  7:  * @return 响应  8:  * @throws Exception 当发生异常时  9:  */ 10: private RemotingCommand pullMessageForward(final ChannelHandlerContext ctx, final RemotingCommand request) throws Exception { 11:     final RemotingCommand response = RemotingCommand.createResponseCommand(PullMessageResponseHeader.class); 12:     final PullMessageResponseHeader responseHeader = (PullMessageResponseHeader) response.readCustomHeader(); 13:     final PullMessageRequestHeader requestHeader = 14:         (PullMessageRequestHeader) request.decodeCommandCustomHeader(PullMessageRequestHeader.class); 15:  16:     final FilterContext filterContext = new FilterContext(); 17:     filterContext.setConsumerGroup(requestHeader.getConsumerGroup()); 18:  19:     response.setOpaque(request.getOpaque()); 20:  21:     DefaultMQPullConsumer pullConsumer = this.filtersrvController.getDefaultMQPullConsumer(); 22:  23:     // 校验Topic过滤类是否完整 24:     final FilterClassInfo findFilterClass = this.filtersrvController.getFilterClassManager().findFilterClass(requestHeader.getConsumerGroup(), requestHeader.getTopic()); 25:     if (null == findFilterClass) { 26:         response.setCode(ResponseCode.SYSTEM_ERROR); 27:         response.setRemark("Find Filter class failed, not registered"); 28:         return response; 29:     } 30:     if (null == findFilterClass.getMessageFilter()) { 31:         response.setCode(ResponseCode.SYSTEM_ERROR); 32:         response.setRemark("Find Filter class failed, registered but no class"); 33:         return response; 34:     } 35:  36:     // 设置下次请求从 Broker主节点。 37:     responseHeader.setSuggestWhichBrokerId(MixAll.MASTER_ID); 38:  39:     MessageQueue mq = new MessageQueue(); 40:     mq.setTopic(requestHeader.getTopic()); 41:     mq.setQueueId(requestHeader.getQueueId()); 42:     mq.setBrokerName(this.filtersrvController.getBrokerName()); 43:     long offset = requestHeader.getQueueOffset(); 44:     int maxNums = requestHeader.getMaxMsgNums(); 45:  46:     final PullCallback pullCallback = new PullCallback() { 47:  48:         @Override 49:         public void onSuccess(PullResult pullResult) { 50:             responseHeader.setMaxOffset(pullResult.getMaxOffset()); 51:             responseHeader.setMinOffset(pullResult.getMinOffset()); 52:             responseHeader.setNextBeginOffset(pullResult.getNextBeginOffset()); 53:             response.setRemark(null); 54:  55:             switch (pullResult.getPullStatus()) { 56:                 case FOUND: 57:                     response.setCode(ResponseCode.SUCCESS); 58:  59:                     List<MessageExt> msgListOK = new ArrayList<MessageExt>(); 60:                     try { 61:                         for (MessageExt msg : pullResult.getMsgFoundList()) { 62:                             // 使用过滤类过滤消息 63:                             boolean match = findFilterClass.getMessageFilter().match(msg, filterContext); 64:                             if (match) { 65:                                 msgListOK.add(msg); 66:                             } 67:                         } 68:  69:                         if (!msgListOK.isEmpty()) { 70:                             returnResponse(requestHeader.getConsumerGroup(), requestHeader.getTopic(), ctx, response, msgListOK); 71:                             return; 72:                         } else { 73:                             response.setCode(ResponseCode.PULL_RETRY_IMMEDIATELY); 74:                         } 75:                     } catch (Throwable e) { 76:                         final String error = 77:                             String.format("do Message Filter Exception, ConsumerGroup: %s Topic: %s ", 78:                                 requestHeader.getConsumerGroup(), requestHeader.getTopic()); 79:                         log.error(error, e); 80:  81:                         response.setCode(ResponseCode.SYSTEM_ERROR); 82:                         response.setRemark(error + RemotingHelper.exceptionSimpleDesc(e)); 83:                         returnResponse(requestHeader.getConsumerGroup(), requestHeader.getTopic(), ctx, response, null); 84:                         return; 85:                     } 86:  87:                     break; 88:                 case NO_MATCHED_MSG: 89:                     response.setCode(ResponseCode.PULL_RETRY_IMMEDIATELY); 90:                     break; 91:                 case NO_NEW_MSG: 92:                     response.setCode(ResponseCode.PULL_NOT_FOUND); 93:                     break; 94:                 case OFFSET_ILLEGAL: 95:                     response.setCode(ResponseCode.PULL_OFFSET_MOVED); 96:                     break; 97:                 default: 98:                     break; 99:             }100: 101:             returnResponse(requestHeader.getConsumerGroup(), requestHeader.getTopic(), ctx, response, null);102:         }103: 104:         @Override105:         public void onException(Throwable e) {106:             response.setCode(ResponseCode.SYSTEM_ERROR);107:             response.setRemark("Pull Callback Exception, " + RemotingHelper.exceptionSimpleDesc(e));108:             returnResponse(requestHeader.getConsumerGroup(), requestHeader.getTopic(), ctx, response, null);109:             return;110:         }111:     };112: 113:     // 拉取消息114:     pullConsumer.pullBlockIfNotFound(mq, null, offset, maxNums, pullCallback);115:     return null;116: }

5. Filtersrv 高可用