聊聊rocketmq-mysql的EventProcessor

积累知识，胜过积蓄金银！毕竟在##column_title##开发的过程中，会遇到各种各样的问题，往往都是一些细节知识点还没有掌握好而导致的，因此基础知识点的积累是很重要的。下面本文《聊聊rocketmq-mysql的EventProcessor》，就带大家讲解一下MySQL知识点，若是你对本文感兴趣，或者是想搞懂其中某个知识点，就请你继续往下看吧~

序

本文主要研究一下rocketmq-mysql的EventProcessor

EventProcessor

rocketmq-externals/rocketmq-mysql/src/main/java/org/apache/rocketmq/mysql/binlog/EventProcessor.java

public class EventProcessor {
    private static final Logger LOGGER = LoggerFactory.getLogger(EventProcessor.class);

    private Replicator replicator;
    private Config config;

    private DataSource dataSource;

    private BinlogPositionManager binlogPositionManager;

    private BlockingQueue queue = new LinkedBlockingQueue(100);

    private BinaryLogClient binaryLogClient;

    private EventListener eventListener;

    private Schema schema;

    private Map tableMap = new HashMap();

    private Transaction transaction;

    public EventProcessor(Replicator replicator) {

        this.replicator = replicator;
        this.config = replicator.getConfig();
    }

    public void start() throws Exception {

        initDataSource();

        binlogPositionManager = new BinlogPositionManager(config, dataSource);
        binlogPositionManager.initBeginPosition();

        schema = new Schema(dataSource);
        schema.load();

        eventListener = new EventListener(queue);
        binaryLogClient = new BinaryLogClient(config.mysqlAddr,
            config.mysqlPort,
            config.mysqlUsername,
            config.mysqlPassword);
        binaryLogClient.setBlocking(true);
        binaryLogClient.setServerId(1001);

        EventDeserializer eventDeserializer = new EventDeserializer();
        eventDeserializer.setCompatibilityMode(EventDeserializer.CompatibilityMode.DATE_AND_TIME_AS_LONG,
            EventDeserializer.CompatibilityMode.CHAR_AND_BINARY_AS_BYTE_ARRAY);
        binaryLogClient.setEventDeserializer(eventDeserializer);
        binaryLogClient.registerEventListener(eventListener);
        binaryLogClient.setBinlogFilename(binlogPositionManager.getBinlogFilename());
        binaryLogClient.setBinlogPosition(binlogPositionManager.getPosition());

        binaryLogClient.connect(3000);

        LOGGER.info("Started.");

        doProcess();
    }

    //......

}

• EventProcessor提供了start方法，该方法首先执行initDataSource；之后创建BinlogPositionManager并执行binlogPositionManager.initBeginPosition()；然后创建EventListener及BinaryLogClient并执行binaryLogClient.connect(3000)；最后执行doProcess方法

initDataSource

rocketmq-externals/rocketmq-mysql/src/main/java/org/apache/rocketmq/mysql/binlog/EventProcessor.java

public class EventProcessor {

    //......

    private void initDataSource() throws Exception {
        Map map = new HashMap();
        map.put("driverClassName", "com.mysql.jdbc.Driver");
        map.put("url", "jdbc:mysql://" + config.mysqlAddr + ":" + config.mysqlPort + "?useSSL=true&verifyServerCertificate=false");
        map.put("username", config.mysqlUsername);
        map.put("password", config.mysqlPassword);
        map.put("initialSize", "2");
        map.put("maxActive", "2");
        map.put("maxWait", "60000");
        map.put("timeBetweenEvictionRunsMillis", "60000");
        map.put("minEvictableIdleTimeMillis", "300000");
        map.put("validationQuery", "SELECT 1 FROM DUAL");
        map.put("testWhileIdle", "true");

        dataSource = DruidDataSourceFactory.createDataSource(map);
    }

    //......

}

• initDataSource主要是通过DruidDataSourceFactory来创建dataSource

doProcess

rocketmq-externals/rocketmq-mysql/src/main/java/org/apache/rocketmq/mysql/binlog/EventProcessor.java

public class EventProcessor {

    //......

    private void doProcess() {

        while (true) {

            try {
                Event event = queue.poll(1000, TimeUnit.MILLISECONDS);
                if (event == null) {
                    checkConnection();
                    continue;
                }

                switch (event.getHeader().getEventType()) {
                    case TABLE_MAP:
                        processTableMapEvent(event);
                        break;

                    case WRITE_ROWS:
                    case EXT_WRITE_ROWS:
                        processWriteEvent(event);
                        break;

                    case UPDATE_ROWS:
                    case EXT_UPDATE_ROWS:
                        processUpdateEvent(event);
                        break;

                    case DELETE_ROWS:
                    case EXT_DELETE_ROWS:
                        processDeleteEvent(event);
                        break;

                    case QUERY:
                        processQueryEvent(event);
                        break;

                    case XID:
                        processXidEvent(event);
                        break;

                }
            } catch (Exception e) {
                LOGGER.error("Binlog process error.", e);
            }

        }
    }
            
    //......

}

• doProcess方法会执行queue.poll(1000, TimeUnit.MILLISECONDS)拉取event，如果event为null，则会执行checkConnection；之后根据event.getHeader().getEventType()来做不同处理；主要有processTableMapEvent、processWriteEvent、processUpdateEvent、processDeleteEvent、processQueryEvent、processXidEvent这几种

processEvent

rocketmq-externals/rocketmq-mysql/src/main/java/org/apache/rocketmq/mysql/binlog/EventProcessor.java

public class EventProcessor {

    //......

    private void processTableMapEvent(Event event) {
        TableMapEventData data = event.getData();
        String dbName = data.getDatabase();
        String tableName = data.getTable();
        Long tableId = data.getTableId();

        Table table = schema.getTable(dbName, tableName);

        tableMap.put(tableId, table);
    }

    private void processWriteEvent(Event event) {
        WriteRowsEventData data = event.getData();
        Long tableId = data.getTableId();
        List list = data.getRows();

        for (Serializable[] row : list) {
            addRow("WRITE", tableId, row);
        }
    }

    private void processUpdateEvent(Event event) {
        UpdateRowsEventData data = event.getData();
        Long tableId = data.getTableId();
        List> list = data.getRows();

        for (Map.Entry entry : list) {
            addRow("UPDATE", tableId, entry.getValue());
        }
    }

    private void processDeleteEvent(Event event) {
        DeleteRowsEventData data = event.getData();
        Long tableId = data.getTableId();
        List list = data.getRows();

        for (Serializable[] row : list) {
            addRow("DELETE", tableId, row);
        }

    }

    private void processQueryEvent(Event event) {
        QueryEventData data = event.getData();
        String sql = data.getSql();

        if (createTablePattern.matcher(sql).find()) {
            schema.reset();
        }
    }

    private void processXidEvent(Event event) {
        EventHeaderV4 header = event.getHeader();
        XidEventData data = event.getData();

        String binlogFilename = binaryLogClient.getBinlogFilename();
        Long position = header.getNextPosition();
        Long xid = data.getXid();

        BinlogPosition binlogPosition = new BinlogPosition(binlogFilename, position);
        transaction.setNextBinlogPosition(binlogPosition);
        transaction.setXid(xid);

        replicator.commit(transaction, true);

        transaction = new Transaction(config);
    }

    private void addRow(String type, Long tableId, Serializable[] row) {

        if (transaction == null) {
            transaction = new Transaction(config);
        }

        Table t = tableMap.get(tableId);
        if (t != null) {

            while (true) {
                if (transaction.addRow(type, t, row)) {
                    break;

                } else {
                    transaction.setNextBinlogPosition(replicator.getNextBinlogPosition());
                    replicator.commit(transaction, false);
                    transaction = new Transaction(config);
                }
            }

        }
    }

    //......

}

• processWriteEvent、processUpdateEvent、processDeleteEvent都会执行addRow方法，它会执行transaction.addRow(type, t, row)，如果返回false则会执行transaction.setNextBinlogPosition以及replicator.commit；processXidEvent会执行binaryLogClient.getBinlogFilename()，更新transaction的xid及binlogPosition，然后执行replicator.commit(transaction, true)，并重置transaction

小结

EventProcessor提供了start方法，该方法首先执行initDataSource；之后创建BinlogPositionManager并执行binlogPositionManager.initBeginPosition()；然后创建EventListener及BinaryLogClient并执行binaryLogClient.connect(3000)；最后执行doProcess方法

doc

• EventProcessor

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