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本文主要研究一下rocketmq的compressMsgBodyOverHowmuch

compressMsgBodyOverHowmuch

rocketmq-client-4.5.2-sources.jar!/org/apache/rocketmq/client/producer/DefaultMQProducer.java

public class DefaultMQProducer extends ClientConfig implements MQProducer {

    //......

    /**
     * Compress message body threshold,namely,message body larger than 4k will be compressed on default.
     */
    private int compressMsgBodyOverHowmuch = 1024 * 4;

    public int getCompressMsgBodyOverHowmuch
 
() {
        return compressMsgBodyOverHowmuch;
    }

    public void setCompressMsgBodyOverHowmuch(int compressMsgBodyOverHowmuch) {
        this.compressMsgBodyOverHowmuch = compressMsgBodyOverHowmuch;
    }

    //......
}
複製程式碼

• DefaultMQProducer定義了compressMsgBodyOverHowmuch屬性，預設值為4k

DefaultMQProducerImpl

rocketmq-client-4.5.2-sources.jar!/org/apache/rocketmq/client/impl/producer/DefaultMQProducerImpl.java

public class DefaultMQProducerImpl implements MQProducerInner {
    private final InternalLogger log = ClientLogger.getLog();
    private final Random random = new Random();
    private final DefaultMQProducer defaultMQProducer;
    private final ConcurrentMap<String/* topic */,TopicPublishInfo> topicPublishInfoTable =
        new ConcurrentHashMap<String,TopicPublishInfo>();
    private final ArrayList<SendMessageHook> sendMessageHookList = new ArrayList<SendMessageHook>();
    private final RPCHook rpcHook;
    protected BlockingQueue<Runnable> checkRequestQueue;
    protected ExecutorService checkExecutor;
    private ServiceState serviceState = ServiceState.CREATE_JUST;
    private MQClientInstance mQClientFactory;
    private ArrayList<CheckForbiddenHook> checkForbiddenHookList = new ArrayList<CheckForbiddenHook>();
    private int zipCompressLevel = Integer.parseInt(System.getProperty(MixAll.MESSAGE_COMPRESS_LEVEL,"5"
 
));

    private MQFaultStrategy mqFaultStrategy = new MQFaultStrategy();

    private final BlockingQueue<Runnable> asyncSenderThreadPoolQueue;
    private final ExecutorService defaultAsyncSenderExecutor;
    private ExecutorService asyncSenderExecutor;

    //......

    private SendResult sendKernelImpl(final Message msg,final MessageQueue mq,final CommunicationMode communicationMode,final SendCallback sendCallback,final TopicPublishInfo topicPublishInfo,final long timeout) throws MQClientException,RemotingException,MQBrokerException,InterruptedException {
        long beginStartTime = System.currentTimeMillis();
        String brokerAddr = this.mQClientFactory.findBrokerAddressInPublish(mq.getBrokerName());
        if (null == brokerAddr) {
            tryToFindTopicPublishInfo(mq.getTopic());
            brokerAddr = this.mQClientFactory.findBrokerAddressInPublish(mq.getBrokerName());
        }

        SendMessageContext context = null;
        if (brokerAddr != null) {
            brokerAddr = MixAll.brokerVIPChannel(this.defaultMQProducer.isSendMessageWithVIPChannel(),brokerAddr);

            byte[] prevBody = msg.getBody();
            try {
                //for MessageBatch,ID has been set in the generating process
                if (!(msg instanceof MessageBatch)) {
                    MessageClientIDSetter.setUniqID(msg);
                }

                boolean topicWithNamespace = false;
                if (null != this.mQClientFactory.getClientConfig().getNamespace()) {
                    msg.setInstanceId(this.mQClientFactory.getClientConfig().getNamespace());
                    topicWithNamespace = true;
                }

                int sysFlag = 0;
                boolean msgBodyCompressed = false;
                if (this.tryToCompressMessage(msg)) {
                    sysFlag |= MessageSysFlag.COMPRESSED_FLAG;
                    msgBodyCompressed = true;
                }

                final String tranMsg = msg.getProperty(MessageConst.PROPERTY_TRANSACTION_PREPARED);
                if (tranMsg != null && Boolean.parseBoolean(tranMsg)) {
                    sysFlag |= MessageSysFlag.TRANSACTION_PREPARED_TYPE;
                }

                if (hasCheckForbiddenHook()) {
                    CheckForbiddenContext checkForbiddenContext = new CheckForbiddenContext();
                    checkForbiddenContext.setNameSrvAddr(this.defaultMQProducer.getNamesrvAddr());
                    checkForbiddenContext.setGroup(this.defaultMQProducer.getProducerGroup());
                    checkForbiddenContext.setCommunicationMode(communicationMode);
                    checkForbiddenContext.setBrokerAddr(brokerAddr);
                    checkForbiddenContext.setMessage(msg);
                    checkForbiddenContext.setMq(mq);
                    checkForbiddenContext.setUnitMode(this.isUnitMode());
                    this.executeCheckForbiddenHook(checkForbiddenContext);
                }

                if (this.hasSendMessageHook()) {
                    context = new SendMessageContext();
                    context.setProducer(this);
                    context.setProducerGroup(this.defaultMQProducer.getProducerGroup());
                    context.setCommunicationMode(communicationMode);
                    context.setBornHost(this.defaultMQProducer.getClientIP());
                    context.setBrokerAddr(brokerAddr);
                    context.setMessage(msg);
                    context.setMq(mq);
                    context.setNamespace(this.defaultMQProducer.getNamespace());
                    String isTrans = msg.getProperty(MessageConst.PROPERTY_TRANSACTION_PREPARED);
                    if (isTrans != null && isTrans.equals("true")) {
                        context.setMsgType(MessageType.Trans_Msg_Half);
                    }

                    if (msg.getProperty("__STARTDELIVERTIME") != null || msg.getProperty(MessageConst.PROPERTY_DELAY_TIME_LEVEL) != null) {
                        context.setMsgType(MessageType.Delay_Msg);
                    }
                    this.executeSendMessageHookBefore(context);
                }

                SendMessageRequestHeader requestHeader = new SendMessageRequestHeader();
                requestHeader.setProducerGroup(this.defaultMQProducer.getProducerGroup());
                requestHeader.setTopic(msg.getTopic());
                requestHeader.setDefaultTopic(this.defaultMQProducer.getCreateTopicKey());
                requestHeader.setDefaultTopicQueueNums(this.defaultMQProducer.getDefaultTopicQueueNums());
                requestHeader.setQueueId(mq.getQueueId());
                requestHeader.setSysFlag(sysFlag);
                requestHeader.setBornTimestamp(System.currentTimeMillis());
                requestHeader.setFlag(msg.getFlag());
                requestHeader.setProperties(MessageDecoder.messageProperties2String(msg.getProperties()));
                requestHeader.setReconsumeTimes(0);
                requestHeader.setUnitMode(this.isUnitMode());
                requestHeader.setBatch(msg instanceof MessageBatch);
                if (requestHeader.getTopic().startsWith(MixAll.RETRY_GROUP_TOPIC_PREFIX)) {
                    String reconsumeTimes = MessageAccessor.getReconsumeTime(msg);
                    if (reconsumeTimes != null) {
                        requestHeader.setReconsumeTimes(Integer.valueOf(reconsumeTimes));
                        MessageAccessor.clearProperty(msg,MessageConst.PROPERTY_RECONSUME_TIME);
                    }

                    String maxReconsumeTimes = MessageAccessor.getMaxReconsumeTimes(msg);
                    if (maxReconsumeTimes != null) {
                        requestHeader.setMaxReconsumeTimes(Integer.valueOf(maxReconsumeTimes));
                        MessageAccessor.clearProperty(msg,MessageConst.PROPERTY_MAX_RECONSUME_TIMES);
                    }
                }

                SendResult sendResult = null;
                switch (communicationMode) {
                    case ASYNC:
                        Message tmpMessage = msg;
                        boolean messageCloned = false;
                        if (msgBodyCompressed) {
                            //If msg body was compressed,msgbody should be reset using prevBody.
                            //Clone new message using commpressed message body and recover origin massage.
                            //Fix bug:https://github.com/apache/rocketmq-externals/issues/66
                            tmpMessage = MessageAccessor.cloneMessage(msg);
                            messageCloned = true;
                            msg.setBody(prevBody);
                        }

                        if (topicWithNamespace) {
                            if (!messageCloned) {
                                tmpMessage = MessageAccessor.cloneMessage(msg);
                                messageCloned = true;
                            }
                            msg.setTopic(NamespaceUtil.withoutNamespace(msg.getTopic(),this.defaultMQProducer.getNamespace()));
                        }

                        long costTimeAsync = System.currentTimeMillis() - beginStartTime;
                        if (timeout < costTimeAsync) {
                            throw new RemotingTooMuchRequestException("sendKernelImpl call timeout");
                        }
                        sendResult = this.mQClientFactory.getMQClientAPIImpl().sendMessage(
                            brokerAddr,mq.getBrokerName(),tmpMessage,requestHeader,timeout - costTimeAsync,communicationMode,sendCallback,topicPublishInfo,this.mQClientFactory,this.defaultMQProducer.getRetryTimesWhenSendAsyncFailed(),context,this);
                        break;
                    case ONEWAY:
                    case SYNC:
                        long costTimeSync = System.currentTimeMillis() - beginStartTime;
                        if (timeout < costTimeSync) {
                            throw new RemotingTooMuchRequestException("sendKernelImpl call timeout");
                        }
                        sendResult = this.mQClientFactory.getMQClientAPIImpl().sendMessage(
                            brokerAddr,msg,timeout - costTimeSync,this);
                        break;
                    default:
                        assert false;
                        break;
                }

                if (this.hasSendMessageHook()) {
                    context.setSendResult(sendResult);
                    this.executeSendMessageHookAfter(context);
                }

                return sendResult;
            } catch (RemotingException e) {
                if (this.hasSendMessageHook()) {
                    context.setException(e);
                    this.executeSendMessageHookAfter(context);
                }
                throw e;
            } catch (MQBrokerException e) {
                if (this.hasSendMessageHook()) {
                    context.setException(e);
                    this.executeSendMessageHookAfter(context);
                }
                throw e;
            } catch (InterruptedException e) {
                if (this.hasSendMessageHook()) {
                    context.setException(e);
                    this.executeSendMessageHookAfter(context);
                }
                throw e;
            } finally {
                msg.setBody(prevBody);
                msg.setTopic(NamespaceUtil.withoutNamespace(msg.getTopic(),this.defaultMQProducer.getNamespace()));
            }
        }

        throw new MQClientException("The broker[" + mq.getBrokerName() + "] not exist",null);
    }

    private boolean tryToCompressMessage(final Message msg) {
        if (msg instanceof MessageBatch) {
            //batch dose not support compressing right now
            return false;
        }
        byte[] body = msg.getBody();
        if (body != null) {
            if (body.length >= this.defaultMQProducer.getCompressMsgBodyOverHowmuch()) {
                try {
                    byte[] data = UtilAll.compress(body,zipCompressLevel);
                    if (data != null) {
                        msg.setBody(data);
                        return true;
                    }
                } catch (IOException e) {
                    log.error("tryToCompressMessage exception",e);
                    log.warn(msg.toString());
                }
            }
        }

        return false;
    }

    //......
}
複製程式碼

• DefaultMQProducerImpl的sendKernelImpl方法會通過tryToCompressMessage(msg)方法來決定是否壓縮msgBody，返回true的話，會設定sysFlag，然後通過requestHeader傳遞給broker

MessageDecoder

rocketmq/common/src/main/java/org/apache/rocketmq/common/message/MessageDecoder.java

public class MessageDecoder {
    public final static int MSG_ID_LENGTH = 8 + 8;

    public final static Charset CHARSET_UTF8 = Charset.forName("UTF-8");
    public final static int MESSAGE_MAGIC_CODE_POSTION = 4;
    public final static int MESSAGE_FLAG_POSTION = 16;
    public final static int MESSAGE_PHYSIC_OFFSET_POSTION = 28;
    public final static int MESSAGE_STORE_TIMESTAMP_POSTION = 56;
    public final static int MESSAGE_MAGIC_CODE = -626843481;
    public static final char NAME_VALUE_SEPARATOR = 1;
    public static final char PROPERTY_SEPARATOR = 2;
    public static final int PHY_POS_POSITION =  4 + 4 + 4 + 4 + 4 + 8;
    public static final int BODY_SIZE_POSITION = 4 // 1 TOTALSIZE
        + 4 // 2 MAGICCODE
        + 4 // 3 BODYCRC
        + 4 // 4 QUEUEID
        + 4 // 5 FLAG
        + 8 // 6 QUEUEOFFSET
        + 8 // 7 PHYSICALOFFSET
        + 4 // 8 SYSFLAG
        + 8 // 9 BORNTIMESTAMP
        + 8 // 10 BORNHOST
        + 8 // 11 STORETIMESTAMP
        + 8 // 12 STOREHOSTADDRESS
        + 4 // 13 RECONSUMETIMES
        + 8; // 14 Prepared Transaction Offset

    //......

   public static byte[] encode(MessageExt messageExt,boolean needCompress) throws Exception {
        byte[] body = messageExt.getBody();
        byte[] topics = messageExt.getTopic().getBytes(CHARSET_UTF8);
        byte topicLen = (byte) topics.length;
        String properties = messageProperties2String(messageExt.getProperties());
        byte[] propertiesBytes = properties.getBytes(CHARSET_UTF8);
        short propertiesLength = (short) propertiesBytes.length;
        int sysFlag = messageExt.getSysFlag();
        byte[] newBody = messageExt.getBody();
        if (needCompress && (sysFlag & MessageSysFlag.COMPRESSED_FLAG) == MessageSysFlag.COMPRESSED_FLAG) {
            newBody = UtilAll.compress(body,5);
        }
        int bodyLength = newBody.length;
        int storeSize = messageExt.getStoreSize();
        ByteBuffer byteBuffer;
        if (storeSize > 0) {
            byteBuffer = ByteBuffer.allocate(storeSize);
        } else {
            storeSize = 4 // 1 TOTALSIZE
                + 4 // 2 MAGICCODE
                + 4 // 3 BODYCRC
                + 4 // 4 QUEUEID
                + 4 // 5 FLAG
                + 8 // 6 QUEUEOFFSET
                + 8 // 7 PHYSICALOFFSET
                + 4 // 8 SYSFLAG
                + 8 // 9 BORNTIMESTAMP
                + 8 // 10 BORNHOST
                + 8 // 11 STORETIMESTAMP
                + 8 // 12 STOREHOSTADDRESS
                + 4 // 13 RECONSUMETIMES
                + 8 // 14 Prepared Transaction Offset
                + 4 + bodyLength // 14 BODY
                + 1 + topicLen // 15 TOPIC
                + 2 + propertiesLength // 16 propertiesLength
                + 0;
            byteBuffer = ByteBuffer.allocate(storeSize);
        }
        // 1 TOTALSIZE
        byteBuffer.putInt(storeSize);

        // 2 MAGICCODE
        byteBuffer.putInt(MESSAGE_MAGIC_CODE);

        // 3 BODYCRC
        int bodyCRC = messageExt.getBodyCRC();
        byteBuffer.putInt(bodyCRC);

        // 4 QUEUEID
        int queueId = messageExt.getQueueId();
        byteBuffer.putInt(queueId);

        // 5 FLAG
        int flag = messageExt.getFlag();
        byteBuffer.putInt(flag);

        // 6 QUEUEOFFSET
        long queueOffset = messageExt.getQueueOffset();
        byteBuffer.putLong(queueOffset);

        // 7 PHYSICALOFFSET
        long physicOffset = messageExt.getCommitLogOffset();
        byteBuffer.putLong(physicOffset);

        // 8 SYSFLAG
        byteBuffer.putInt(sysFlag);

        // 9 BORNTIMESTAMP
        long bornTimeStamp = messageExt.getBornTimestamp();
        byteBuffer.putLong(bornTimeStamp);

        // 10 BORNHOST
        InetSocketAddress bornHost = (InetSocketAddress) messageExt.getBornHost();
        byteBuffer.put(bornHost.getAddress().getAddress());
        byteBuffer.putInt(bornHost.getPort());

        // 11 STORETIMESTAMP
        long storeTimestamp = messageExt.getStoreTimestamp();
        byteBuffer.putLong(storeTimestamp);

        // 12 STOREHOST
        InetSocketAddress serverHost = (InetSocketAddress) messageExt.getStoreHost();
        byteBuffer.put(serverHost.getAddress().getAddress());
        byteBuffer.putInt(serverHost.getPort());

        // 13 RECONSUMETIMES
        int reconsumeTimes = messageExt.getReconsumeTimes();
        byteBuffer.putInt(reconsumeTimes);

        // 14 Prepared Transaction Offset
        long preparedTransactionOffset = messageExt.getPreparedTransactionOffset();
        byteBuffer.putLong(preparedTransactionOffset);

        // 15 BODY
        byteBuffer.putInt(bodyLength);
        byteBuffer.put(newBody);

        // 16 TOPIC
        byteBuffer.put(topicLen);
        byteBuffer.put(topics);

        // 17 properties
        byteBuffer.putShort(propertiesLength);
        byteBuffer.put(propertiesBytes);

        return byteBuffer.array();
    }

    public static MessageExt decode(
        java.nio.ByteBuffer byteBuffer,final boolean readBody,final boolean deCompressBody,final boolean isClient) {
        try {

            MessageExt msgExt;
            if (isClient) {
                msgExt = new MessageClientExt();
            } else {
                msgExt = new MessageExt();
            }

            // 1 TOTALSIZE
            int storeSize = byteBuffer.getInt();
            msgExt.setStoreSize(storeSize);

            // 2 MAGICCODE
            byteBuffer.getInt();

            // 3 BODYCRC
            int bodyCRC = byteBuffer.getInt();
            msgExt.setBodyCRC(bodyCRC);

            // 4 QUEUEID
            int queueId = byteBuffer.getInt();
            msgExt.setQueueId(queueId);

            // 5 FLAG
            int flag = byteBuffer.getInt();
            msgExt.setFlag(flag);

            // 6 QUEUEOFFSET
            long queueOffset = byteBuffer.getLong();
            msgExt.setQueueOffset(queueOffset);

            // 7 PHYSICALOFFSET
            long physicOffset = byteBuffer.getLong();
            msgExt.setCommitLogOffset(physicOffset);

            // 8 SYSFLAG
            int sysFlag = byteBuffer.getInt();
            msgExt.setSysFlag(sysFlag);

            // 9 BORNTIMESTAMP
            long bornTimeStamp = byteBuffer.getLong();
            msgExt.setBornTimestamp(bornTimeStamp);

            // 10 BORNHOST
            byte[] bornHost = new byte[4];
            byteBuffer.get(bornHost,4);
            int port = byteBuffer.getInt();
            msgExt.setBornHost(new InetSocketAddress(InetAddress.getByAddress(bornHost),port));

            // 11 STORETIMESTAMP
            long storeTimestamp = byteBuffer.getLong();
            msgExt.setStoreTimestamp(storeTimestamp);

            // 12 STOREHOST
            byte[] storeHost = new byte[4];
            byteBuffer.get(storeHost,4);
            port = byteBuffer.getInt();
            msgExt.setStoreHost(new InetSocketAddress(InetAddress.getByAddress(storeHost),port));

            // 13 RECONSUMETIMES
            int reconsumeTimes = byteBuffer.getInt();
            msgExt.setReconsumeTimes(reconsumeTimes);

            // 14 Prepared Transaction Offset
            long preparedTransactionOffset = byteBuffer.getLong();
            msgExt.setPreparedTransactionOffset(preparedTransactionOffset);

            // 15 BODY
            int bodyLen = byteBuffer.getInt();
            if (bodyLen > 0) {
                if (readBody) {
                    byte[] body = new byte[bodyLen];
                    byteBuffer.get(body);

                    // uncompress body
                    if (deCompressBody && (sysFlag & MessageSysFlag.COMPRESSED_FLAG) == MessageSysFlag.COMPRESSED_FLAG) {
                        body = UtilAll.uncompress(body);
                    }

                    msgExt.setBody(body);
                } else {
                    byteBuffer.position(byteBuffer.position() + bodyLen);
                }
            }

            // 16 TOPIC
            byte topicLen = byteBuffer.get();
            byte[] topic = new byte[(int) topicLen];
            byteBuffer.get(topic);
            msgExt.setTopic(new String(topic,CHARSET_UTF8));

            // 17 properties
            short propertiesLength = byteBuffer.getShort();
            if (propertiesLength > 0) {
                byte[] properties = new byte[propertiesLength];
                byteBuffer.get(properties);
                String propertiesString = new String(properties,CHARSET_UTF8);
                Map<String,String> map = string2messageProperties(propertiesString);
                msgExt.setProperties(map);
            }

            ByteBuffer byteBufferMsgId = ByteBuffer.allocate(MSG_ID_LENGTH);
            String msgId = createMessageId(byteBufferMsgId,msgExt.getStoreHostBytes(),msgExt.getCommitLogOffset());
            msgExt.setMsgId(msgId);

            if (isClient) {
                ((MessageClientExt) msgExt).setOffsetMsgId(msgId);
            }

            return msgExt;
        } catch (Exception e) {
            byteBuffer.position(byteBuffer.limit());
        }

        return null;
    }

    //......
}    
複製程式碼

• MessageDecoder的encode會根據sysFlag判斷是否需要壓縮，是的話執行UtilAll.compress(body,5)；decode方法會根據根據sysFlag判斷是否需要解壓縮，是的話執行UtilAll.uncompress(body)

小結

DefaultMQProducerImpl的sendKernelImpl方法會通過tryToCompressMessage(msg)方法來決定是否壓縮msgBody，返回true的話，會設定sysFlag，然後通過requestHeader傳遞給broker；MessageDecoder的encode會根據sysFlag判斷是否需要壓縮，是的話執行UtilAll.compress(body,5)；decode方法會根據根據sysFlag判斷是否需要解壓縮，是的話執行UtilAll.uncompress(body)

doc

• DefaultMQProducer