mycat源码解读1-登录mycat

mycat的启动过程及mycat登录部分代码

mycat的启动类是MycatStartup，启动的时候会启动两个Server。分别是FrontendServer和ManagerServer。ManageServer先不管，暂时关注于FrontendServer.

  • FrontendServer的初始化为

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    ServerConnectionFactory sf = new ServerConnectionFactory();
    ...
    ...
    server = new NIOAcceptor(DirectByteBufferPool.LOCAL_BUF_THREAD_PREX + NAME
    					+ "Server", system.getBindIp(), system.getServerPort(), sf, reactorPool);

  • 再看ServerConnectionFactory的代码

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    public class ServerConnectionFactory extends FrontendConnectionFactory {
        @Override
        protected FrontendConnection getConnection(NetworkChannel channel) throws IOException {
            SystemConfig sys = MycatServer.getInstance().getConfig().getSystem();
            //使用该connection，channel丢给该connection。
            ServerConnection c = new ServerConnection(channel);
            MycatServer.getInstance().getConfig().setSocketParams(c, true);
            c.setPrivileges(MycatPrivileges.instance());
            c.setQueryHandler(new ServerQueryHandler(c));
            c.setLoadDataInfileHandler(new ServerLoadDataInfileHandler(c));
            c.setPrepareHandler(new ServerPrepareHandler(c));
            c.setTxIsolation(sys.getTxIsolation());
            c.setSession2(new NonBlockingSession(c));
            return c;
        }
    }

  • 每次请求获得的Connection为ServerConnection。ServerConnection直接使用父类的构造方法.

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    public FrontendConnection(NetworkChannel channel) throws IOException {
    		super(channel);
    		InetSocketAddress localAddr = (InetSocketAddress) channel.getLocalAddress();
    		InetSocketAddress remoteAddr = null;
    		if (channel instanceof SocketChannel) {
    			remoteAddr = (InetSocketAddress) ((SocketChannel) channel).getRemoteAddress();	
    			
    		} else if (channel instanceof AsynchronousSocketChannel) {
    			remoteAddr = (InetSocketAddress) ((AsynchronousSocketChannel) channel).getRemoteAddress();
    		}
    		
    		this.host = remoteAddr.getHostString();
    		this.port = localAddr.getPort();
    		this.localPort = remoteAddr.getPort();
    		//将handler指向为FrontendAuthenticator
    		this.handler = new FrontendAuthenticator(this);
    	}

  • 可以看到使用的handler为FrontendAuthenticator，该handler起个认证的作用。看该类的handle方法

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    public void handle(byte[] data) {
            // check quit packet
            if (data.length == QuitPacket.QUIT.length && data[4] == MySQLPacket.COM_QUIT) {
                source.close("quit packet");
                return;
            }
            AuthPacket auth = new AuthPacket();
            auth.read(data);
            
            ...
            ...
            default:
                success(auth);
            }
        }
        
    protected void success(AuthPacket auth) {
        source.setAuthenticated(true);
        source.setUser(auth.user);
        source.setSchema(auth.database);
        source.setCharsetIndex(auth.charsetIndex);
        //成功后将handler指向FrontendCommandHandler
        source.setHandler(new FrontendCommandHandler(source));
        if (LOGGER.isInfoEnabled()) {
            StringBuilder s = new StringBuilder();
            s.append(source).append('\'').append(auth.user).append("' login success");
            byte[] extra = auth.extra;
            if (extra != null && extra.length > 0) {
                s.append(",extra:").append(new String(extra));
            }
            LOGGER.info(s.toString());
        }
        ByteBuffer buffer = source.allocate();
        source.write(source.writeToBuffer(AUTH_OK, buffer));
        boolean clientCompress = Capabilities.CLIENT_COMPRESS==(Capabilities.CLIENT_COMPRESS & auth.clientFlags);
        boolean usingCompress= MycatServer.getInstance().getConfig().getSystem().getUseCompression()==1 ;
        if(clientCompress&&usingCompress)
        {
            source.setSupportCompress(true);
        }
    }

  • 到此步骤为止，完成登录验证。登录成功后FrontendCOnnection的handler指向了FrontendCommandHandler。后续继续阅读mycat 请求sql部分代码。