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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
doc
来源：oschina
链接：https://my.oschina.net/go4it/blog/4035725