mycat服务启动{管理模块启动过程}

mycat启动的时候启动了三个模块

1:NIOConnector(负责链接mysql数据库,连接池以数据库为准不以链接字符串为准),

1:NIOAcceptor,ManagerConnectionFactory(管理模块,默认端口9066)

2:NIOAcceptor,ServerConnectionFactory(mysql服务模块,默认端口8066)

这里介绍下管理模块的启动流程

顺序图

NIO和AIO

mycat分别实现了NIO和AIO,由于linux当前没有真正实现AIO这里主要介绍NIO的流程。

NIO的Reactor与AIO的Proactor两种模式的场景区别:
下面是Reactor的做法:
1. 等待事件响应 (Reactor job)
2. 分发 “Ready-to-Read” 事件给用户句柄 ( Reactor job)
3. 读数据 (user handler job)
4. 处理数据( user handler job)
下面再来看看真正意义的异步模式Proactor是如何做的:
1. 等待事件响应 (Proactor job)
2. 读数据 (Proactor job)
3. 分发 “Read-Completed” 事件给用户句柄 (Proactor job)
4. 处理数据(user handler job)

mycat的NIO实现

Selector(选择器)是Java NIO中能够检测一到多个NIO通道,并能够知晓通道是否为诸如读写事件做好准备的组件。这样,一个单独的线程可以管理多个channel,从而管理多个网络连接。
Selector可以监听四种不同类型的事件:
- Connect
- Accept
- Read
- Write
这四种事件用SelectionKey的四个常量来表示:
- SelectionKey.OP_CONNECT
- SelectionKey.OP_ACCEPT
- SelectionKey.OP_READ
- SelectionKey.OP_WRITE
前面已经说了,NIO采用的Reactor模式:例如汽车是乘客访问的主体(Reactor),乘客上车后,到售票员(acceptor)处登记,之后乘客便可以休息睡觉去了,当到达乘客所要到达的目的地后,售票员将其唤醒即可。

 

核心顺序

mycat管理端的启动流程

1:new ManagerConnectionFactory extends FrontendConnectionFactory

2:new NIOReactorPool,new NIOReactor,new RW中new ConcurrentLinkedQueue<AbstractConnection>()而AbstractConnection中new NIOSocketWR

3:new NIOAcceptor中向反应堆中注册了OP_ACCEPT,该类继承了Thread然后start启动

accept

			channel = serverChannel.accept();
			channel.configureBlocking(false);
			FrontendConnection c = factory.make(channel);
			c.setAccepted(true);
			c.setId(ID_GENERATOR.getId());
			NIOProcessor processor = (NIOProcessor) MycatServer.getInstance()
					.nextProcessor();
			c.setProcessor(processor);

			LOGGER.info("accept");

			NIOReactor reactor = reactorPool.getNextReactor();
			reactor.postRegister(c);

factory.make(channel):最终构造了ManagerQueryHandler(管理命令解析器)和FrontendAuthenticator(mycat权限解析器)

reactor.postRegister(c):把当前链接添加到reactor的registerQueue中并唤醒reactor的selector

read

在NIOReactor的registerQueue为空的时候run循环空运转,当上一步把accept的链接放到队列的时候则

			for (;;) {



				++reactCount;
				try {
					selector.select(500L);
					register(selector);
					keys = selector.selectedKeys();
					for (SelectionKey key : keys) {
						AbstractConnection con = null;
						try {
							Object att = key.attachment();
							if (att != null) {
								con = (AbstractConnection) att;
								if (key.isValid() && key.isReadable()) {
									try {
										con.asynRead();
									} catch (IOException e) {
                                        con.close("program err:" + e.toString());
										continue;
									} catch (Exception e) {
										LOGGER.debug("caught err:", e);
										con.close("program err:" + e.toString());
										continue;
									}
								}
								if (key.isValid() && key.isWritable()) {
									con.doNextWriteCheck();
								}
							} else {
								key.cancel();
							}
                        } catch (CancelledKeyException e) {
                            if (LOGGER.isDebugEnabled()) {
                                LOGGER.debug(con + " socket key canceled");
                            }
                        } catch (Exception e) {
                            LOGGER.warn(con + " " + e);
                        }
					}
				} catch (Exception e) {
					LOGGER.warn(name, e);
				} finally {
					if (keys != null) {
						keys.clear();
					}

				}

register(selector);也即

((NIOSocketWR) c.getSocketWR()).register(selector); 注册OP_READ事件
c.register();即FrontendConnection的register发送握手数据包

con.asynRead();即NIOSocketWR的asynRead即

	public void asynRead() throws IOException {
		LOGGER.info("asynRead");
		ByteBuffer theBuffer = con.readBuffer;
		if (theBuffer == null) {
			theBuffer = con.processor.getBufferPool().allocate();
			con.readBuffer = theBuffer;
		}
		int got = channel.read(theBuffer);
		con.onReadData(got);

	}

con.onReadData(got);即AbstractConnection的onReadData这里拆包得到完成的数据包后调用

handler.handle(data);也即FrontendAuthenticator的handle在这里check user;check password;check schema如果失败则将失败信息写入缓冲区,如果成功

则把AbstractConnection的默认hander从FrontendAuthenticator换成FrontendCommandHandler等待接下来的处理(比如show命令等,

以上的处理是发生在输入mysql -utest -ptest -h10.97.177.83 -P9066时)

认证完成后下一次的handler.handle(data)则使用FrontendCommandHandler的handle来处理也即

    public void handle(byte[] data)
    {
        if(source.getLoadDataInfileHandler()!=null&&source.getLoadDataInfileHandler().isStartLoadData())
        {
            MySQLMessage mm = new MySQLMessage(data);
            int  packetLength = mm.readUB3();
            if(packetLength+4==data.length)
            {
                source.loadDataInfileData(data);
            }
            return;
        }
        switch (data[4])
        {
            case MySQLPacket.COM_INIT_DB:
                commands.doInitDB();
                source.initDB(data);
                break;
            case MySQLPacket.COM_QUERY:
                commands.doQuery();
                source.query(data);
                break;
            case MySQLPacket.COM_PING:
                commands.doPing();
                source.ping();
                break;
            case MySQLPacket.COM_QUIT:
                commands.doQuit();
                source.close("quit cmd");
                break;
            case MySQLPacket.COM_PROCESS_KILL:
                commands.doKill();
                source.kill(data);
                break;
            case MySQLPacket.COM_STMT_PREPARE:
                commands.doStmtPrepare();
                source.stmtPrepare(data);
                break;
            case MySQLPacket.COM_STMT_EXECUTE:
                commands.doStmtExecute();
                source.stmtExecute(data);
                break;
            case MySQLPacket.COM_STMT_CLOSE:
                commands.doStmtClose();
                source.stmtClose(data);
                break;
            case MySQLPacket.COM_HEARTBEAT:
                commands.doHeartbeat();
                source.heartbeat(data);
                break;
            default:
                     commands.doOther();
                     source.writeErrMessage(ErrorCode.ER_UNKNOWN_COM_ERROR,
                             "Unknown command");

        }
    }

source.query(data);即queryHandler.query(sql);这里的queryHandler是ManagerQueryHandler即

    public void query(String sql) {
        ManagerConnection c = this.source;
        if (LOGGER.isDebugEnabled()) {
            LOGGER.debug(new StringBuilder().append(c).append(sql).toString());
        }
        int rs = ManagerParse.parse(sql);
        switch (rs & 0xff) {
            case ManagerParse.SELECT:
                SelectHandler.handle(sql, c, rs >>> SHIFT);
                break;
            case ManagerParse.SET:
                c.write(c.writeToBuffer(OkPacket.OK, c.allocate()));
                break;
            case ManagerParse.SHOW:
                ShowHandler.handle(sql, c, rs >>> SHIFT);
                break;
            case ManagerParse.SWITCH:
                SwitchHandler.handler(sql, c, rs >>> SHIFT);
                break;
            case ManagerParse.KILL_CONN:
                KillConnection.response(sql, rs >>> SHIFT, c);
                break;
            case ManagerParse.OFFLINE:
                Offline.execute(sql, c);
                break;
            case ManagerParse.ONLINE:
                Online.execute(sql, c);
                break;
            case ManagerParse.STOP:
                StopHandler.handle(sql, c, rs >>> SHIFT);
                break;
            case ManagerParse.RELOAD:
                ReloadHandler.handle(sql, c, rs >>> SHIFT);
                break;
            case ManagerParse.ROLLBACK:
                RollbackHandler.handle(sql, c, rs >>> SHIFT);
                break;
            case ManagerParse.CLEAR:
                ClearHandler.handle(sql, c, rs >>> SHIFT);
                break;
            case ManagerParse.CONFIGFILE:
                ConfFileHandler.handle(sql, c);
                break;
            case ManagerParse.LOGFILE:
                ShowServerLog.handle(sql, c);
                break;
            default:
                c.writeErrMessage(ErrorCode.ER_YES, "Unsupported statement");
        }
    }

总结

mycat的网络处理逻辑上是通过队列加上后台线程来实现了accept和read的解耦从而实现了高性能,但是代码写的就不敢恭维。

 

posted @ 2016-01-13 15:59  李占卫  阅读(2885)  评论(0编辑  收藏  举报