聊聊canal的MysqlConnection

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    本文主要研究一下canal的MysqlConnection

    ErosaConnection

    canal-1.1.4/parse/src/main/java/com/alibaba/otter/canal/parse/inbound/ErosaConnection.java

    public interface ErosaConnection {

    public void connect() throws IOException;

    public void reconnect() throws IOException;

    public void disconnect() throws IOException;

    /**
     * 用于快速数据查找,和dump的区别在于，seek会只给出部分的数据
     */
    public void seek(String binlogfilename, Long binlogPosition, String gtid, SinkFunction func) throws IOException;

    public void dump(String binlogfilename, Long binlogPosition, SinkFunction func) throws IOException;

    public void dump(long timestamp, SinkFunction func) throws IOException;

    /**
     * 通过GTID同步binlog
     */
    public void dump(GTIDSet gtidSet, SinkFunction func) throws IOException;

    // -------------

    public void dump(String binlogfilename, Long binlogPosition, MultiStageCoprocessor coprocessor) throws IOException;

    public void dump(long timestamp, MultiStageCoprocessor coprocessor) throws IOException;

    public void dump(GTIDSet gtidSet, MultiStageCoprocessor coprocessor) throws IOException;

    ErosaConnection fork();

    public long queryServerId() throws IOException;
}
    • ErosaConnection接口定义了connect、reconnect、disconnect、seek、dump、fork、queryServerId方法

    MysqlConnection

    canal-1.1.4/parse/src/main/java/com/alibaba/otter/canal/parse/inbound/mysql/MysqlConnection.java

    public class MysqlConnection implements ErosaConnection {

    private static final Logger logger         = LoggerFactory.getLogger(MysqlConnection.class);

    private MysqlConnector      connector;
    private long                slaveId;
    private Charset             charset        = Charset.forName("UTF-8");
    private BinlogFormat        binlogFormat;
    private BinlogImage         binlogImage;

    // tsdb releated
    private AuthenticationInfo  authInfo;
    protected int               connTimeout    = 5 * 1000;                                      // 5秒
    protected int               soTimeout      = 60 * 60 * 1000;                                // 1小时
    private int                 binlogChecksum = LogEvent.BINLOG_CHECKSUM_ALG_OFF;
    // dump binlog bytes, 暂不包括meta与TSDB
    private AtomicLong          receivedBinlogBytes;

    public MysqlConnection(){
    }

    public MysqlConnection(InetSocketAddress address, String username, String password){
        authInfo = new AuthenticationInfo();
        authInfo.setAddress(address);
        authInfo.setUsername(username);
        authInfo.setPassword(password);
        connector = new MysqlConnector(address, username, password);
        // 将connection里面的参数透传下
        connector.setSoTimeout(soTimeout);
        connector.setConnTimeout(connTimeout);
    }

    public MysqlConnection(InetSocketAddress address, String username, String password, byte charsetNumber,
                           String defaultSchema){
        authInfo = new AuthenticationInfo();
        authInfo.setAddress(address);
        authInfo.setUsername(username);
        authInfo.setPassword(password);
        authInfo.setDefaultDatabaseName(defaultSchema);
        connector = new MysqlConnector(address, username, password, charsetNumber, defaultSchema);
        // 将connection里面的参数透传下
        connector.setSoTimeout(soTimeout);
        connector.setConnTimeout(connTimeout);
    }

    public void connect() throws IOException {
        connector.connect();
    }

    public void reconnect() throws IOException {
        connector.reconnect();
    }

    public void disconnect() throws IOException {
        connector.disconnect();
    }

    public boolean isConnected() {
        return connector.isConnected();
    }

    public MysqlConnection fork() {
        MysqlConnection connection = new MysqlConnection();
        connection.setCharset(getCharset());
        connection.setSlaveId(getSlaveId());
        connection.setConnector(connector.fork());
        // set authInfo
        connection.setAuthInfo(authInfo);
        return connection;
    }

    @Override
    public long queryServerId() throws IOException {
        ResultSetPacket resultSetPacket = query("show variables like 'server_id'");
        List<String> fieldValues = resultSetPacket.getFieldValues();
        if (fieldValues == null || fieldValues.size() != 2) {
            return 0;
        }
        return NumberUtils.toLong(fieldValues.get(1));
    }

    public ResultSetPacket query(String cmd) throws IOException {
        MysqlQueryExecutor exector = new MysqlQueryExecutor(connector);
        return exector.query(cmd);
    }

    //......

}
    • MysqlConnection实现了ErosaConnection接口，其构造器会构建AuthenticationInfo及MysqlConnector；其connect、reconnect、disconnect方法均直接委托给MysqlConnector；其fork方法会使用connector.fork()重新创建一个MysqlConnection；其queryServerId方法则使用show variables like 'server_id'查询

    seek

    canal-1.1.4/parse/src/main/java/com/alibaba/otter/canal/parse/inbound/mysql/MysqlConnection.java

    public class MysqlConnection implements ErosaConnection {

    //......

    public void seek(String binlogfilename, Long binlogPosition, String gtid, SinkFunction func) throws IOException {
        updateSettings();
        loadBinlogChecksum();
        sendBinlogDump(binlogfilename, binlogPosition);
        DirectLogFetcher fetcher = new DirectLogFetcher(connector.getReceiveBufferSize());
        fetcher.start(connector.getChannel());
        LogDecoder decoder = new LogDecoder();
        decoder.handle(LogEvent.ROTATE_EVENT);
        decoder.handle(LogEvent.FORMAT_DESCRIPTION_EVENT);
        decoder.handle(LogEvent.QUERY_EVENT);
        decoder.handle(LogEvent.XID_EVENT);
        LogContext context = new LogContext();
        // 若entry position存在gtid，则使用传入的gtid作为gtidSet
        // 拼接的标准,否则同时开启gtid和tsdb时，会导致丢失gtid
        // 而当源端数据库gtid 有purged时会有如下类似报错
        // 'errno = 1236, sqlstate = HY000 errmsg = The slave is connecting
        // using CHANGE MASTER TO MASTER_AUTO_POSITION = 1 ...
        if (StringUtils.isNotEmpty(gtid)) {
            decoder.handle(LogEvent.GTID_LOG_EVENT);
            context.setGtidSet(MysqlGTIDSet.parse(gtid));
        }
        context.setFormatDescription(new FormatDescriptionLogEvent(4, binlogChecksum));
        while (fetcher.fetch()) {
            accumulateReceivedBytes(fetcher.limit());
            LogEvent event = null;
            event = decoder.decode(fetcher, context);

            if (event == null) {
                throw new CanalParseException("parse failed");
            }

            if (!func.sink(event)) {
                break;
            }
        }
    }

    private void updateSettings() throws IOException {
        try {
            update("set wait_timeout=9999999");
        } catch (Exception e) {
            logger.warn("update wait_timeout failed", e);
        }
        try {
            update("set net_write_timeout=1800");
        } catch (Exception e) {
            logger.warn("update net_write_timeout failed", e);
        }

        try {
            update("set net_read_timeout=1800");
        } catch (Exception e) {
            logger.warn("update net_read_timeout failed", e);
        }

        try {
            // 设置服务端返回结果时不做编码转化，直接按照数据库的二进制编码进行发送，由客户端自己根据需求进行编码转化
            update("set names 'binary'");
        } catch (Exception e) {
            logger.warn("update names failed", e);
        }

        try {
            // mysql5.6针对checksum支持需要设置session变量
            // 如果不设置会出现错误： Slave can not handle replication events with the
            // checksum that master is configured to log
            // 但也不能乱设置，需要和mysql server的checksum配置一致，不然RotateLogEvent会出现乱码
            // '@@global.binlog_checksum'需要去掉单引号,在mysql 5.6.29下导致master退出
            update("set @master_binlog_checksum= @@global.binlog_checksum");
        } catch (Exception e) {
            if (!StringUtils.contains(e.getMessage(), "Unknown system variable")) {
                logger.warn("update master_binlog_checksum failed", e);
            }
        }

        try {
            // 参考:https://github.com/alibaba/canal/issues/284
            // mysql5.6需要设置slave_uuid避免被server kill链接
            update("set @slave_uuid=uuid()");
        } catch (Exception e) {
            if (!StringUtils.contains(e.getMessage(), "Unknown system variable")) {
                logger.warn("update slave_uuid failed", e);
            }
        }

        try {
            // mariadb针对特殊的类型，需要设置session变量
            update("SET @mariadb_slave_capability='" + LogEvent.MARIA_SLAVE_CAPABILITY_MINE + "'");
        } catch (Exception e) {
            if (!StringUtils.contains(e.getMessage(), "Unknown system variable")) {
                logger.warn("update mariadb_slave_capability failed", e);
            }
        }

        /**
         * MASTER_HEARTBEAT_PERIOD sets the interval in seconds between
         * replication heartbeats. Whenever the master's binary log is updated
         * with an event, the waiting period for the next heartbeat is reset.
         * interval is a decimal value having the range 0 to 4294967 seconds and
         * a resolution in milliseconds; the smallest nonzero value is 0.001.
         * Heartbeats are sent by the master only if there are no unsent events
         * in the binary log file for a period longer than interval.
         */
        try {
            long periodNano = TimeUnit.SECONDS.toNanos(MASTER_HEARTBEAT_PERIOD_SECONDS);
            update("SET @master_heartbeat_period=" + periodNano);
        } catch (Exception e) {
            logger.warn("update master_heartbeat_period failed", e);
        }
    }

    private void loadBinlogChecksum() {
        ResultSetPacket rs = null;
        try {
            rs = query("select @@global.binlog_checksum");
            List<String> columnValues = rs.getFieldValues();
            if (columnValues != null && columnValues.size() >= 1 && columnValues.get(0) != null
                && columnValues.get(0).toUpperCase().equals("CRC32")) {
                binlogChecksum = LogEvent.BINLOG_CHECKSUM_ALG_CRC32;
            } else {
                binlogChecksum = LogEvent.BINLOG_CHECKSUM_ALG_OFF;
            }
        } catch (Throwable e) {
            // logger.error("", e);
            binlogChecksum = LogEvent.BINLOG_CHECKSUM_ALG_OFF;
        }
    }

    private void sendBinlogDump(String binlogfilename, Long binlogPosition) throws IOException {
        BinlogDumpCommandPacket binlogDumpCmd = new BinlogDumpCommandPacket();
        binlogDumpCmd.binlogFileName = binlogfilename;
        binlogDumpCmd.binlogPosition = binlogPosition;
        binlogDumpCmd.slaveServerId = this.slaveId;
        byte[] cmdBody = binlogDumpCmd.toBytes();

        logger.info("COM_BINLOG_DUMP with position:{}", binlogDumpCmd);
        HeaderPacket binlogDumpHeader = new HeaderPacket();
        binlogDumpHeader.setPacketBodyLength(cmdBody.length);
        binlogDumpHeader.setPacketSequenceNumber((byte) 0x00);
        PacketManager.writePkg(connector.getChannel(), binlogDumpHeader.toBytes(), cmdBody);
        connector.setDumping(true);
    }

    //......
}
    • seek方法先执行updateSettings、loadBinlogChecksum、sendBinlogDump方法，然后创建DirectLogFetcher来fetch数据；updateSettings方法会设置wait_timeout、net_write_timeout、net_read_timeout、master_heartbeat_period等参数；loadBinlogChecksum方法会校验master的binlogChecksum；sendBinlogDump方法则是发送BinlogDumpCommandPacket

    dump

    canal-1.1.4/parse/src/main/java/com/alibaba/otter/canal/parse/inbound/mysql/MysqlConnection.java

    public class MysqlConnection implements ErosaConnection {

    //......

    public void dump(String binlogfilename, Long binlogPosition, SinkFunction func) throws IOException {
        updateSettings();
        loadBinlogChecksum();
        sendRegisterSlave();
        sendBinlogDump(binlogfilename, binlogPosition);
        DirectLogFetcher fetcher = new DirectLogFetcher(connector.getReceiveBufferSize());
        fetcher.start(connector.getChannel());
        LogDecoder decoder = new LogDecoder(LogEvent.UNKNOWN_EVENT, LogEvent.ENUM_END_EVENT);
        LogContext context = new LogContext();
        context.setFormatDescription(new FormatDescriptionLogEvent(4, binlogChecksum));
        while (fetcher.fetch()) {
            accumulateReceivedBytes(fetcher.limit());
            LogEvent event = null;
            event = decoder.decode(fetcher, context);

            if (event == null) {
                throw new CanalParseException("parse failed");
            }

            if (!func.sink(event)) {
                break;
            }

            if (event.getSemival() == 1) {
                sendSemiAck(context.getLogPosition().getFileName(), context.getLogPosition().getPosition());
            }
        }
    }

    public void dump(GTIDSet gtidSet, SinkFunction func) throws IOException {
        updateSettings();
        loadBinlogChecksum();
        sendBinlogDumpGTID(gtidSet);

        DirectLogFetcher fetcher = new DirectLogFetcher(connector.getReceiveBufferSize());
        try {
            fetcher.start(connector.getChannel());
            LogDecoder decoder = new LogDecoder(LogEvent.UNKNOWN_EVENT, LogEvent.ENUM_END_EVENT);
            LogContext context = new LogContext();
            context.setFormatDescription(new FormatDescriptionLogEvent(4, binlogChecksum));
            // fix bug: #890 将gtid传输至context中，供decode使用
            context.setGtidSet(gtidSet);
            while (fetcher.fetch()) {
                accumulateReceivedBytes(fetcher.limit());
                LogEvent event = null;
                event = decoder.decode(fetcher, context);

                if (event == null) {
                    throw new CanalParseException("parse failed");
                }

                if (!func.sink(event)) {
                    break;
                }
            }
        } finally {
            fetcher.close();
        }
    }

    public void dump(String binlogfilename, Long binlogPosition, MultiStageCoprocessor coprocessor) throws IOException {
        updateSettings();
        loadBinlogChecksum();
        sendRegisterSlave();
        sendBinlogDump(binlogfilename, binlogPosition);
        ((MysqlMultiStageCoprocessor) coprocessor).setConnection(this);
        ((MysqlMultiStageCoprocessor) coprocessor).setBinlogChecksum(binlogChecksum);
        DirectLogFetcher fetcher = new DirectLogFetcher(connector.getReceiveBufferSize());
        try {
            fetcher.start(connector.getChannel());
            while (fetcher.fetch()) {
                accumulateReceivedBytes(fetcher.limit());
                LogBuffer buffer = fetcher.duplicate();
                fetcher.consume(fetcher.limit());
                if (!coprocessor.publish(buffer)) {
                    break;
                }
            }
        } finally {
            fetcher.close();
        }
    }

    public void dump(GTIDSet gtidSet, MultiStageCoprocessor coprocessor) throws IOException {
        updateSettings();
        loadBinlogChecksum();
        sendBinlogDumpGTID(gtidSet);
        ((MysqlMultiStageCoprocessor) coprocessor).setConnection(this);
        ((MysqlMultiStageCoprocessor) coprocessor).setBinlogChecksum(binlogChecksum);
        DirectLogFetcher fetcher = new DirectLogFetcher(connector.getReceiveBufferSize());
        try {
            fetcher.start(connector.getChannel());
            while (fetcher.fetch()) {
                accumulateReceivedBytes(fetcher.limit());
                LogBuffer buffer = fetcher.duplicate();
                fetcher.consume(fetcher.limit());
                if (!coprocessor.publish(buffer)) {
                    break;
                }
            }
        } finally {
            fetcher.close();
        }
    }

    private void sendRegisterSlave() throws IOException {
        RegisterSlaveCommandPacket cmd = new RegisterSlaveCommandPacket();
        SocketAddress socketAddress = connector.getChannel().getLocalSocketAddress();
        if (socketAddress == null || !(socketAddress instanceof InetSocketAddress)) {
            return;
        }

        InetSocketAddress address = (InetSocketAddress) socketAddress;
        String host = address.getHostString();
        int port = address.getPort();
        cmd.reportHost = host;
        cmd.reportPort = port;
        cmd.reportPasswd = authInfo.getPassword();
        cmd.reportUser = authInfo.getUsername();
        cmd.serverId = this.slaveId;
        byte[] cmdBody = cmd.toBytes();

        logger.info("Register slave {}", cmd);

        HeaderPacket header = new HeaderPacket();
        header.setPacketBodyLength(cmdBody.length);
        header.setPacketSequenceNumber((byte) 0x00);
        PacketManager.writePkg(connector.getChannel(), header.toBytes(), cmdBody);

        header = PacketManager.readHeader(connector.getChannel(), 4);
        byte[] body = PacketManager.readBytes(connector.getChannel(), header.getPacketBodyLength());
        assert body != null;
        if (body[0] < 0) {
            if (body[0] == -1) {
                ErrorPacket err = new ErrorPacket();
                err.fromBytes(body);
                throw new IOException("Error When doing Register slave:" + err.toString());
            } else {
                throw new IOException("unpexpected packet with field_count=" + body[0]);
            }
        }
    }

    private void sendBinlogDumpGTID(GTIDSet gtidSet) throws IOException {
        BinlogDumpGTIDCommandPacket binlogDumpCmd = new BinlogDumpGTIDCommandPacket();
        binlogDumpCmd.slaveServerId = this.slaveId;
        binlogDumpCmd.gtidSet = gtidSet;
        byte[] cmdBody = binlogDumpCmd.toBytes();

        logger.info("COM_BINLOG_DUMP_GTID:{}", binlogDumpCmd);
        HeaderPacket binlogDumpHeader = new HeaderPacket();
        binlogDumpHeader.setPacketBodyLength(cmdBody.length);
        binlogDumpHeader.setPacketSequenceNumber((byte) 0x00);
        PacketManager.writePkg(connector.getChannel(), binlogDumpHeader.toBytes(), cmdBody);
        connector.setDumping(true);
    }

    //......

}
    • MysqlConnection提供了多个dump方法，主要分为根据binlog文件名的，根据gtidSet的，以及使用SinkFunction或者MultiStageCoprocessor的
    • 根据binlogfilename的dump方法先执行updateSettings、loadBinlogChecksum、sendRegisterSlave、sendBinlogDump，然后创建DirectLogFetcher拉取数据，触发SinkFunction或者MultiStageCoprocessor；根据gtidSet的dump方法先执行updateSettings、loadBinlogChecksum、sendBinlogDumpGTID，然后创建DirectLogFetcher拉取数据，触发SinkFunction或者MultiStageCoprocessor
    • sendRegisterSlave方法构造并发送RegisterSlaveCommandPacket；sendBinlogDumpGTID方法则构造并发送BinlogDumpGTIDCommandPacket

    小结

    MysqlConnection实现了ErosaConnection接口，其构造器会构建AuthenticationInfo及MysqlConnector；其connect、reconnect、disconnect方法均直接委托给MysqlConnector；其fork方法会使用connector.fork()重新创建一个MysqlConnection；其queryServerId方法则使用show variables like 'server_id'查询；它提供了多个dump方法，主要分为根据binlog文件名的，根据gtidSet的，以及使用SinkFunction或者MultiStageCoprocessor的

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