07-Tomcat启动过程（二）

public void start()
    throws Exception {
    if( catalinaDaemon==null ) init();

    Method method = catalinaDaemon.getClass().getMethod("start", (Class [] )null);
    method.invoke(catalinaDaemon, (Object [])null);
}

public void start() {

    if (getServer() == null) {
        load();
    }

    if (getServer() == null) {
        log.fatal("Cannot start server. Server instance is not configured.");
        return;
    }

    long t1 = System.nanoTime();

    // Start the new server
    try {
        //调用Server的start方法，启动Server组件 
        getServer().start();
    } catch (LifecycleException e) {
        log.fatal(sm.getString("catalina.serverStartFail"), e);
        try {
            getServer().destroy();
        } catch (LifecycleException e1) {
            log.debug("destroy() failed for failed Server ", e1);
        }
        return;
    }

    long t2 = System.nanoTime();
    if(log.isInfoEnabled()) {
        log.info("Server startup in " + ((t2 - t1) / 1000000) + " ms");
    }

    // Register shutdown hook
    // 注册勾子，用于安全关闭tomcat
    if (useShutdownHook) {
        if (shutdownHook == null) {
            shutdownHook = new CatalinaShutdownHook();
        }
        Runtime.getRuntime().addShutdownHook(shutdownHook);

        // If JULI is being used, disable JULI's shutdown hook since
        // shutdown hooks run in parallel and log messages may be lost
        // if JULI's hook completes before the CatalinaShutdownHook()
        LogManager logManager = LogManager.getLogManager();
        if (logManager instanceof ClassLoaderLogManager) {
            ((ClassLoaderLogManager) logManager).setUseShutdownHook(
                    false);
        }
    }

    // Bootstrap中会设置await为true，其目的在于让tomcat在shutdown端口阻塞监听关闭命令
    if (await) {
        await();
        stop();
    }
}

protected void startInternal() throws LifecycleException {

    fireLifecycleEvent(CONFIGURE_START_EVENT, null);
    setState(LifecycleState.STARTING);

    globalNamingResources.start();

    // Start our defined Services
    synchronized (servicesLock) {
        for (int i = 0; i < services.length; i++) {
            services[i].start();
        }
    }
}

protected void startInternal() throws LifecycleException {

    setState(LifecycleState.STARTING);

    // 启动Engine
    if (engine != null) {
        synchronized (engine) {
            engine.start();
        }
    }

    // 启动Executor线程池
    synchronized (executors) {
        for (Executor executor: executors) {
            executor.start();
        }
    }

    // 启动MapperListener
    mapperListener.start();

    // 启动Connector
    synchronized (connectorsLock) {
        for (Connector connector: connectors) {
            try {
                // If it has already failed, don't try and start it
                if (connector.getState() != LifecycleState.FAILED) {
                    connector.start();
                }
            } catch (Exception e) {
                // logger......
            }
        }
    }
}

/**
 * Create a new StandardEngine component with the default basic Valve.
 */
public StandardEngine() {
    super();
    pipeline.setBasic(new StandardEngineValve());
    /* Set the jmvRoute using the system property jvmRoute */
    try {
        setJvmRoute(System.getProperty("jvmRoute"));
    } catch(Exception ex) {
        log.warn(sm.getString("standardEngine.jvmRouteFail"));
    }
    // By default, the engine will hold the reloading thread
    backgroundProcessorDelay = 10;
}

@Override
protected synchronized void startInternal() throws LifecycleException {

    // Log our server identification information
    if(log.isInfoEnabled())
        log.info( "Starting Servlet Engine: " + ServerInfo.getServerInfo());

    // Standard container startup
    super.startInternal();
}

protected synchronized void startInternal() throws LifecycleException {
    // 省略若干代码......

    // 把子容器的启动步骤放在线程中处理，默认情况下线程池只有一个线程处理任务队列
    Container children[] = findChildren();
    List<Future<Void>> results = new ArrayList<>();
    for (int i = 0; i < children.length; i++) {
        results.add(startStopExecutor.submit(new StartChild(children[i])));
    }

    // 阻塞当前线程，直到子容器start完成
    boolean fail = false;
    for (Future<Void> result : results) {
        try {
            result.get();
        } catch (Exception e) {
            log.error(sm.getString("containerBase.threadedStartFailed"), e);
            fail = true;
        }
    }

    // 启用Pipeline
    if (pipeline instanceof Lifecycle)
        ((Lifecycle) pipeline).start();
    setState(LifecycleState.STARTING);

    // 开启ContainerBackgroundProcessor线程用于调用子容器的backgroundProcess方法，默认情况下backgroundProcessorDelay=-1，不会启用该线程
    threadStart();
}

private static class StartChild implements Callable<Void> {

    private Container child;

    public StartChild(Container child) {
        this.child = child;
    }

    @Override
    public Void call() throws LifecycleException {
        child.start();
        return null;
    }
}

public class StandardPipeline extends LifecycleBase
        implements Pipeline, Contained {

    // 省略若干代码......

    protected synchronized void startInternal() throws LifecycleException {

        Valve current = first;
        if (current == null) {
            current = basic;
        }
        while (current != null) {
            if (current instanceof Lifecycle)
                ((Lifecycle) current).start();
            current = current.getNext();
        }

        setState(LifecycleState.STARTING);
    }

}

public StandardHost() {
    super();
    pipeline.setBasic(new StandardHostValve());
}

protected synchronized void startInternal() throws LifecycleException {

    // errorValve默认使用org.apache.catalina.valves.ErrorReportValve
    String errorValve = getErrorReportValveClass();
    if ((errorValve != null) && (!errorValve.equals(""))) {
        try {
            boolean found = false;

            // 如果所有的阀门中已经存在这个实例，则不进行处理，否则添加到  Pipeline 中
            Valve[] valves = getPipeline().getValves();
            for (Valve valve : valves) {
                if (errorValve.equals(valve.getClass().getName())) {
                    found = true;
                    break;
                }
            }

            // 如果未找到则添加到 Pipeline 中，注意是添加到 basic valve 的前面
            // 默认情况下，first valve 是 AccessLogValve，basic 是 StandardHostValve
            if(!found) {
                Valve valve =
                    (Valve) Class.forName(errorValve).getConstructor().newInstance();
                getPipeline().addValve(valve);
            }
        } catch (Throwable t) {
            // 处理异常，省略......
        }
    }

    // 调用父类 ContainerBase，完成统一的启动动作
    super.startInternal();
}

public StandardContext() {
    super();
    pipeline.setBasic(new StandardContextValve());
    broadcaster = new NotificationBroadcasterSupport();
    // Set defaults
    if (!Globals.STRICT_SERVLET_COMPLIANCE) {
        // Strict servlet compliance requires all extension mapped servlets
        // to be checked against welcome files
        resourceOnlyServlets.add("jsp");
    }
}

public StandardWrapper() {
    super();
    swValve=new StandardWrapperValve();
    pipeline.setBasic(swValve);
    broadcaster = new NotificationBroadcasterSupport();
}