解析Tomcat处理请求的类Connector<三>

      这次主要解析采用apr方式处理请求.apr用C实现，通过JNI调用,主要提升对静态资源（如HTML、图片、CSS、JS等）的访问性能.在tomcat下配置apr步骤:

  1.下载本地库tcnative-1.dll,放在%jdk%\bin目录下(见附件).

  2.在server.xml里配置listener,这个配置server.xml默认是有的

     

  <Listener className="org.apache.catalina.core.AprLifecycleListener" SSLEngine="on" />

 

  3.在server.xml里配置apr connector

  

     <Connector port="8080" protocol="org.apache.coyote.http11.Http11AprProtocol" 
               connectionTimeout="20000" 
               redirectPort="8443" />

 

    在tomcat启动的时候,会调用Connector类的Start()方法,根据以上配置,Connector的start()方法里会调用Http11AprProtocol类的start()方法,如下:

  

       try {
            protocolHandler.start();
        } catch (Exception e) {
            String errPrefix = "";
            if(this.service != null) {
                errPrefix += "service.getName(): \"" + this.service.getName() + "\"; ";
            }

            throw new LifecycleException
                (errPrefix + " " + sm.getString
                 ("coyoteConnector.protocolHandlerStartFailed", e));
        }

 

   

   Http11AprProtocol类的start()方法又会调用AprEndpoint类的start()方法,如下:

     try {
            endpoint.start();
        } catch (Exception ex) {
            log.error(sm.getString("http11protocol.endpoint.starterror"), ex);
            throw ex;
        }

    AprEndpoint类的start()方法如下:

public void start()
        throws Exception {
        // Initialize socket if not done before
        if (!initialized) {
            init();
        }
        if (!running) {
            running = true;
            paused = false;

            // Create worker collection
            if (executor == null) {
                workers = new WorkerStack(maxThreads);
            }

            // Start poller threads
            pollers = new Poller[pollerThreadCount];
            for (int i = 0; i < pollerThreadCount; i++) {
                pollers[i] = new Poller(false);
                pollers[i].init();
                pollers[i].setName(getName() + "-Poller-" + i);
                pollers[i].setPriority(threadPriority);
                pollers[i].setDaemon(true);
                pollers[i].start();
            }

            // Start comet poller threads
            cometPollers = new Poller[pollerThreadCount];
            for (int i = 0; i < pollerThreadCount; i++) {
                cometPollers[i] = new Poller(true);
                cometPollers[i].init();
                cometPollers[i].setName(getName() + "-CometPoller-" + i);
                cometPollers[i].setPriority(threadPriority);
                cometPollers[i].setDaemon(true);
                cometPollers[i].start();
            }

            // Start sendfile threads
            if (useSendfile) {
                sendfiles = new Sendfile[sendfileThreadCount];
                for (int i = 0; i < sendfileThreadCount; i++) {
                    sendfiles[i] = new Sendfile();
                    sendfiles[i].init();
                    sendfiles[i].setName(getName() + "-Sendfile-" + i);
                    sendfiles[i].setPriority(threadPriority);
                    sendfiles[i].setDaemon(true);
                    sendfiles[i].start();
                }
            }

            // Start acceptor threads
            acceptors = new Acceptor[acceptorThreadCount];
            for (int i = 0; i < acceptorThreadCount; i++) {
                acceptors[i] = new Acceptor();
                acceptors[i].setName(getName() + "-Acceptor-" + i);
                acceptors[i].setPriority(threadPriority);
                acceptors[i].setDaemon(getDaemon());
                acceptors[i].start();
            }

        }
    }

        该方法主要初始化接受socket的线程和处理socket的线程池.Acceptor的run()方法如下:

   

public void run() {

            // Loop until we receive a shutdown command
            while (running) {

                // Loop if endpoint is paused
                while (paused && running) {
                    try {
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
                        // Ignore
                    }
                }

                if (!running) {
                    break;
                }
                try {
                    // Accept the next incoming connection from the server socket
                    long socket = Socket.accept(serverSock);
                    /*
                     * In the case of a deferred accept unlockAccept needs to
                     * send data. This data will be rubbish, so destroy the
                     * socket and don't process it.
                     */
                    if (deferAccept && (paused || !running)) {
                        destroySocket(socket);
                        continue;
                    }
                    // Hand this socket off to an appropriate processor
                    if (!processSocketWithOptions(socket)) {//把socket交给woker线程进行转发
                        // Close socket and pool right away
                        destroySocket(socket);
                    }
                } catch (Throwable t) {
                    if (running) {
                        String msg = sm.getString("endpoint.accept.fail");
                        if (t instanceof Error) {
                            Error e = (Error) t;
                            if (e.getError() == 233) {
                                // Not an error on HP-UX so log as a warning
                                // so it can be filtered out on that platform
                                // See bug 50273
                                log.warn(msg, t);
                            } else {
                                log.error(msg, t);
                            }
                        } else {
                                log.error(msg, t);
                        }
                    }
                }

            }

        }

    }

 

   Socket.accept(serverSock)方法的Socket类是用JNI实现的不同于java的Socket类,所以 Socket.accept(serverSock)返回的参数是long类型的.processSocketWithOptions(socket)方法如下:

    

    protected boolean processSocketWithOptions(long socket) {
        try {
            if (executor == null) {
                getWorkerThread().assignWithOptions(socket);
            } else {
                executor.execute(new SocketWithOptionsProcessor(socket));
            }
        } catch (Throwable t) {
            // This means we got an OOM or similar creating a thread, or that
            // the pool and its queue are full
            log.error(sm.getString("endpoint.process.fail"), t);
            return false;
        }
        return true;
    }

 

   再来看一下woker线程的run方法():

  

public void run() {

            // Process requests until we receive a shutdown signal
            while (running) {

                // Wait for the next socket to be assigned
                long socket = await();
                if (socket == 0)
                    continue;

                if (!deferAccept && options) {
                    if (setSocketOptions(socket)) {
                        getPoller().add(socket);//将sokcet交给poller转发.poller最终会把socket交给worker处理不知道为什么这么做
                    } else {
                        // Close socket and pool
                        destroySocket(socket);
                        socket = 0;
                    }
                } else {

                    // Process the request from this socket
                    if ((status != null) && (handler.event(socket, status) == Handler.SocketState.CLOSED)) {
                        // Close socket and pool
                        destroySocket(socket);
                        socket = 0;
                    } else if ((status == null) && ((options && !setSocketOptions(socket))
                            || handler.process(socket) == Handler.SocketState.CLOSED)) {//Http11AprProtocol.Http11ConnectionHandler.process(socket)处理socket
                        // Close socket and pool
                        destroySocket(socket);
                        socket = 0;
                    }
                }

                // Finish up this request
                recycleWorkerThread(this);

            }

        }

 

可以看到,woker的run()方法做了两件事.1.把socket交给poller.2.直接调用处理 Http11AprProtocol.Http11ConnectionHandler.process(socket)处理socket

 handler.process(socket)方法如下:    

 public SocketState process(long socket) {
            Http11AprProcessor processor = recycledProcessors.poll();
            try {
                if (processor == null) {
                    processor = createProcessor();
                }

                if (processor instanceof ActionHook) {
                    ((ActionHook) processor).action(ActionCode.ACTION_START, null);
                }

                SocketState state = processor.process(socket);//真正的解析http请求的方法
                if (state == SocketState.LONG) {//如果是长连接再放回线程池处理
                    // Associate the connection with the processor. The next request 
                    // processed by this thread will use either a new or a recycled
                    // processor.
                    connections.put(socket, processor);
                    proto.endpoint.getCometPoller().add(socket);
                } else {
                    recycledProcessors.offer(processor);
                }
                return state;

            } catch (java.net.SocketException e) {
                // SocketExceptions are normal
                Http11AprProtocol.log.debug
                    (sm.getString
                     ("http11protocol.proto.socketexception.debug"), e);
            } catch (java.io.IOException e) {
                // IOExceptions are normal
                Http11AprProtocol.log.debug
                    (sm.getString
                     ("http11protocol.proto.ioexception.debug"), e);
            }
            // Future developers: if you discover any other
            // rare-but-nonfatal exceptions, catch them here, and log as
            // above.
            catch (Throwable e) {
                // any other exception or error is odd. Here we log it
                // with "ERROR" level, so it will show up even on
                // less-than-verbose logs.
                Http11AprProtocol.log.error
                    (sm.getString("http11protocol.proto.error"), e);
            }
            recycledProcessors.offer(processor);
            return SocketState.CLOSED;
        }

     processor.process(socket)调用的是Http11AprProcessor类的process(long socket) 方法,用http协议对http请求进行解析