简单看，tomcat源码（一）启动与监听

tomcat 作为知名的web容器，很棒！ 本文简单了从其应用命令开始拆解，让我们对他有清晰的了解，揭开神秘的面纱！（冗长的代码流水线，给你一目了然）

话分两头：

1. tomcat是如何启动的？

2. tomcat是如何接收请求的？

x. 应用程序是怎样接入tomcat的？

从何处开始？

/etc/init.d/tomcat8 start    # 简单的 tomcat8 脚本封装
. "$_"
/usr/java/jdk1.8.0_101/bin/java org.apache.catalina.startup.Bootstrap "$@" start
# 参考eval命令
eval "/"$_RUNJAVA/"" "/"$LOGGING_CONFIG/"" $LOGGING_MANAGER $JAVA_OPTS $CATALINA_OPTS /
      -Djava.endorsed.dirs="/"$JAVA_ENDORSED_DIRS/"" -classpath "/"$CLASSPATH/"" /
      -Dcatalina.base="/"$CATALINA_BASE/"" /
      -Dcatalina.home="/"$CATALINA_HOME/"" /
      -Djava.io.tmpdir="/"$CATALINA_TMPDIR/"" /
          org.apache.catalina.startup.Bootstrap "$@" start "2>&1" | /usr/local/sbin/cronolog -S  "$CATALINA_BASE"/logs/catalina_ln.out "$CATALINA_BASE"/logs/catalina.%Y-%m-%d-%H.out >> /dev/null &
          
# 运行后得到结果
/usr/java/jdk1.8.0_101/bin/java -server -Xmx6144M -Xms1024M -Dfile.encoding=UTF-8 -Xloggc:/opt/tomcat7/logs/tomcat_app_gc.log -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/opt/tomcat7/logs/ -classpath /opt/tomcat8/bin/bootstrap.jar:/opt/tomcat8/bin/tomcat-juli.jar -Dcatalina.base="/opt/tomcat8" -Dcatalina.home="/opt/tomcat8" org.apache.catalina.startup.Bootstrap "$@" start "2>&1"

可以看到，tomcat最终是执行 org.apache.catalina.startup.Bootstrap 的 main() 方法，参数为 start ...

那么，我们就以此为起点，进行简单查看下 tomcat 的一些运行原理吧！

// org.apache.catalina.startup.Bootstrap main()入口，启动失败时，直接调用 System.exit(1); 退出jvm.

   public static void main(String args[]) {
        
        // 开始执行，先进行各种初始化操作，然后再解析命令，进行相应方法调用
        if (daemon == null) {
            // Don't set daemon until init() has completed
            Bootstrap bootstrap = new Bootstrap();
            try {
                bootstrap.init();
            } catch (Throwable t) {
                handleThrowable(t);
                t.printStackTrace();
                return;
            }
            daemon = bootstrap;
        } else {
            // When running as a service the call to stop will be on a new
            // thread so make sure the correct class loader is used to prevent
            // a range of class not found exceptions.
            Thread.currentThread().setContextClassLoader(daemon.catalinaLoader);
        }

        try {
            // 解析命令行，以最后一个参数作为启动或停止指令，默认为启动操作，但是外部的tomcat脚本可以防止不传入该参数
            String command = "start";
            if (args.length > 0) {
                command = args[args.length - 1];
            }

            if (command.equals("startd")) {
                args[args.length - 1] = "start";
                daemon.load(args);
                daemon.start();
            } else if (command.equals("stopd")) {
                args[args.length - 1] = "stop";
                daemon.stop();
            } else if (command.equals("start")) {
                // 重点以start为例
                daemon.setAwait(true);
                daemon.load(args);
                daemon.start();
                if (null == daemon.getServer()) {
                    System.exit(1);
                }
            } else if (command.equals("stop")) {
                daemon.stopServer(args);
            } else if (command.equals("configtest")) {
                daemon.load(args);
                if (null == daemon.getServer()) {
                    System.exit(1);
                }
                System.exit(0);
            } else {
                log.warn("Bootstrap: command /"" + command + "/" does not exist.");
            }
        } catch (Throwable t) {
            // Unwrap the Exception for clearer error reporting
            if (t instanceof InvocationTargetException &&
                    t.getCause() != null) {
                t = t.getCause();
            }
            // 先处理特殊异常
            handleThrowable(t);
            t.printStackTrace();
            System.exit(1);
        }

    }

// 接下来我们先看看初始化过程: bootstrap.init(); 也就是自身的 init() 方法。

    /**
     * Initialize daemon.
     * @throws Exception Fatal initialization error
     */
    public void init() throws Exception {

        // 设置 classLoader, 因该classLoader可由外部传入，所以不能直接加载类,如: -c
        initClassLoaders();

        // 设置classLoader到当前线程，以备后续调用
        Thread.currentThread().setContextClassLoader(catalinaLoader);

        // 加载关键的各种系统类，使用自定义的classLoader
        SecurityClassLoad.securityClassLoad(catalinaLoader);

        // 由于加载默认应用时报错，找不到 JSP Compiler, 因此加上此句主动加载, 临时解决问题
        catalinaLoader.loadClass(、"org.apache.jasper.servlet.JasperInitializer");
        new JasperInitializer();

        // Load our startup class and call its process() method
        if (log.isDebugEnabled())
            log.debug("Loading startup class");
        Class<?> startupClass = catalinaLoader.loadClass("org.apache.catalina.startup.Catalina");
        Object startupInstance = startupClass.getConstructor().newInstance();

        // Set the shared extensions class loader
        if (log.isDebugEnabled())
            log.debug("Setting startup class properties");
        String methodName = "setParentClassLoader";
        Class<?> paramTypes[] = new Class[1];
        paramTypes[0] = Class.forName("java.lang.ClassLoader");
        Object paramValues[] = new Object[1];
        paramValues[0] = sharedLoader;
        Method method =
            startupInstance.getClass().getMethod(methodName, paramTypes);
        method.invoke(startupInstance, paramValues);

        catalinaDaemon = startupInstance;

    }

    // step1. 加载 classLoader
    private void initClassLoaders() {
        try {
            // 创建 common
            commonLoader = createClassLoader("common", null);
            if( commonLoader == null ) {
                // no config file, default to this loader - we might be in a 'single' env.
                commonLoader=this.getClass().getClassLoader();
            }
            catalinaLoader = createClassLoader("server", commonLoader);
            sharedLoader = createClassLoader("shared", commonLoader);
        } catch (Throwable t) {
            handleThrowable(t);
            log.error("Class loader creation threw exception", t);
            System.exit(1);
        }
    }
    // 
    private ClassLoader createClassLoader(String name, ClassLoader parent)
        throws Exception {

        // "${catalina.base}/lib","${catalina.base}/lib/*.jar","${catalina.home}/lib","${catalina.home}/lib/*.jar"
        String value = CatalinaProperties.getProperty(name + ".loader");
        if ((value == null) || (value.equals("")))
            return parent;

        // 将 ${xx} 替换为具体的路径，转换为绝对路径 
        value = replace(value);

        List<Repository> repositories = new ArrayList<>();

        // 解析每个路径，然后依次加载
        String[] repositoryPaths = getPaths(value);

        for (String repository : repositoryPaths) {
            // Check for a JAR URL repository
            try {
                @SuppressWarnings("unused")
                URL url = new URL(repository);
                repositories.add(
                        new Repository(repository, RepositoryType.URL));
                continue;
            } catch (MalformedURLException e) {
                // Ignore
            }

            // Local repository
            if (repository.endsWith("*.jar")) {
                repository = repository.substring
                    (0, repository.length() - "*.jar".length());
                repositories.add(
                        new Repository(repository, RepositoryType.GLOB));
            } else if (repository.endsWith(".jar")) {
                repositories.add(
                        new Repository(repository, RepositoryType.JAR));
            } else {
                repositories.add(
                        new Repository(repository, RepositoryType.DIR));
            }
        }

        // 将上面加载的目录文件，进行加载到内存
        return ClassLoaderFactory.createClassLoader(repositories, parent);
    }

// org.apache.catalina.startup.ClassLoaderFactory 工厂类

    /**
     * Create and return a new class loader, based on the configuration
     * defaults and the specified directory paths:
     *
     * @param repositories List of class directories, jar files, jar directories
     *                     or URLS that should be added to the repositories of
     *                     the class loader.
     * @param parent Parent class loader for the new class loader, or
     *  <code>null</code> for the system class loader.
     * @return the new class loader
     *
     * @exception Exception if an error occurs constructing the class loader
     */
    public static ClassLoader createClassLoader(List<Repository> repositories,
                                                final ClassLoader parent)
        throws Exception {

        if (log.isDebugEnabled())
            log.debug("Creating new class loader");

        // Construct the "class path" for this class loader
        Set<URL> set = new LinkedHashSet<>();

        if (repositories != null) {
            for (Repository repository : repositories)  {
                if (repository.getType() == RepositoryType.URL) {
                    URL url = buildClassLoaderUrl(repository.getLocation());
                    if (log.isDebugEnabled())
                        log.debug("  Including URL " + url);
                    set.add(url);
                } else if (repository.getType() == RepositoryType.DIR) {
                    File directory = new File(repository.getLocation());
                    directory = directory.getCanonicalFile();
                    if (!validateFile(directory, RepositoryType.DIR)) {
                        continue;
                    }
                    URL url = buildClassLoaderUrl(directory);
                    if (log.isDebugEnabled())
                        log.debug("  Including directory " + url);
                    set.add(url);
                } else if (repository.getType() == RepositoryType.JAR) {
                    File file=new File(repository.getLocation());
                    file = file.getCanonicalFile();
                    if (!validateFile(file, RepositoryType.JAR)) {
                        continue;
                    }
                    URL url = buildClassLoaderUrl(file);
                    if (log.isDebugEnabled())
                        log.debug("  Including jar file " + url);
                    set.add(url);
                } else if (repository.getType() == RepositoryType.GLOB) {
                    File directory=new File(repository.getLocation());
                    directory = directory.getCanonicalFile();
                    if (!validateFile(directory, RepositoryType.GLOB)) {
                        continue;
                    }
                    if (log.isDebugEnabled())
                        log.debug("  Including directory glob "
                            + directory.getAbsolutePath());
                    String filenames[] = directory.list();
                    if (filenames == null) {
                        continue;
                    }
                    for (int j = 0; j < filenames.length; j++) {
                        String filename = filenames[j].toLowerCase(Locale.ENGLISH);
                        if (!filename.endsWith(".jar"))
                            continue;
                        File file = new File(directory, filenames[j]);
                        file = file.getCanonicalFile();
                        if (!validateFile(file, RepositoryType.JAR)) {
                            continue;
                        }
                        if (log.isDebugEnabled())
                            log.debug("    Including glob jar file "
                                + file.getAbsolutePath());
                        URL url = buildClassLoaderUrl(file);
                        set.add(url);
                    }
                }
            }
        }

        // Construct the class loader itself
        final URL[] array = set.toArray(new URL[set.size()]);
        if (log.isDebugEnabled())
            for (int i = 0; i < array.length; i++) {
                log.debug("  location " + i + " is " + array[i]);
            }

        return AccessController.doPrivileged(
                new PrivilegedAction<URLClassLoader>() {
                    @Override
                    public URLClassLoader run() {
                        if (parent == null)
                            return new URLClassLoader(array);
                        else
                            return new URLClassLoader(array, parent);
                    }
                });
    }

// org.apache.catalina.security.SecurityClassLoad 加载系统关键类

public final class SecurityClassLoad {

    public static void securityClassLoad(ClassLoader loader) throws Exception {
        securityClassLoad(loader, true);
    }

    static void securityClassLoad(ClassLoader loader, boolean requireSecurityManager) throws Exception {

        if (requireSecurityManager && System.getSecurityManager() == null) {
            return;
        }

        // 清晰地加载各种系统类库
        loadCorePackage(loader);
        loadCoyotePackage(loader);
        loadLoaderPackage(loader);
        loadRealmPackage(loader);
        loadServletsPackage(loader);
        loadSessionPackage(loader);
        loadUtilPackage(loader);
        loadValvesPackage(loader);
        loadJavaxPackage(loader);
        loadConnectorPackage(loader);
        loadTomcatPackage(loader);
    }

    private static final void loadCorePackage(ClassLoader loader) throws Exception {
        final String basePackage = "org.apache.catalina.core.";
        loader.loadClass(basePackage + "AccessLogAdapter");
        loader.loadClass(basePackage + "ApplicationContextFacade$PrivilegedExecuteMethod");
        loader.loadClass(basePackage + "ApplicationDispatcher$PrivilegedForward");
        loader.loadClass(basePackage + "ApplicationDispatcher$PrivilegedInclude");
        loader.loadClass(basePackage + "ApplicationPushBuilder");
        loader.loadClass(basePackage + "AsyncContextImpl");
        loader.loadClass(basePackage + "AsyncContextImpl$AsyncRunnable");
        loader.loadClass(basePackage + "AsyncContextImpl$DebugException");
        loader.loadClass(basePackage + "AsyncListenerWrapper");
        loader.loadClass(basePackage + "ContainerBase$PrivilegedAddChild");
        loadAnonymousInnerClasses(loader, basePackage + "DefaultInstanceManager");
        loader.loadClass(basePackage + "DefaultInstanceManager$AnnotationCacheEntry");
        loader.loadClass(basePackage + "DefaultInstanceManager$AnnotationCacheEntryType");
        loader.loadClass(basePackage + "ApplicationHttpRequest$AttributeNamesEnumerator");
    }

    private static final void loadLoaderPackage(ClassLoader loader) throws Exception {
        final String basePackage = "org.apache.catalina.loader.";
        loader.loadClass(basePackage + "WebappClassLoaderBase$PrivilegedFindClassByName");
        loader.loadClass(basePackage + "WebappClassLoaderBase$PrivilegedHasLoggingConfig");
    }

    private static final void loadRealmPackage(ClassLoader loader) throws Exception {
        final String basePackage = "org.apache.catalina.realm.";
        loader.loadClass(basePackage + "LockOutRealm$LockRecord");
    }

    private static final void loadServletsPackage(ClassLoader loader) throws Exception {
        final String basePackage = "org.apache.catalina.servlets.";
        // Avoid a possible memory leak in the DefaultServlet when running with
        // a security manager. The DefaultServlet needs to load an XML parser
        // when running under a security manager. We want this to be loaded by
        // the container rather than a web application to prevent a memory leak
        // via web application class loader.
        loader.loadClass(basePackage + "DefaultServlet");
    }

    private static final void loadSessionPackage(ClassLoader loader) throws Exception {
        final String basePackage = "org.apache.catalina.session.";
        loader.loadClass(basePackage + "StandardSession");
        loadAnonymousInnerClasses(loader, basePackage + "StandardSession");
        loader.loadClass(basePackage + "StandardManager$PrivilegedDoUnload");
    }

    private static final void loadUtilPackage(ClassLoader loader) throws Exception {
        final String basePackage = "org.apache.catalina.util.";
        loader.loadClass(basePackage + "ParameterMap");
        loader.loadClass(basePackage + "RequestUtil");
        loader.loadClass(basePackage + "TLSUtil");
    }

    private static final void loadValvesPackage(ClassLoader loader) throws Exception {
        final String basePackage = "org.apache.catalina.valves.";
        loadAnonymousInnerClasses(loader, basePackage + "AbstractAccessLogValve");
    }

    private static final void loadCoyotePackage(ClassLoader loader) throws Exception {
        final String basePackage = "org.apache.coyote.";
        loader.loadClass(basePackage + "http11.Constants");
        // Make sure system property is read at this point
        Class<?> clazz = loader.loadClass(basePackage + "Constants");
        clazz.getConstructor().newInstance();
        loader.loadClass(basePackage + "http2.Stream$PrivilegedPush");
    }

    private static final void loadJavaxPackage(ClassLoader loader) throws Exception {
        loader.loadClass("javax.servlet.http.Cookie");
    }

    private static final void loadConnectorPackage(ClassLoader loader) throws Exception {
        final String basePackage = "org.apache.catalina.connector.";
        loader.loadClass(basePackage + "RequestFacade$GetAttributePrivilegedAction");
        loader.loadClass(basePackage + "RequestFacade$GetParameterMapPrivilegedAction");
        loader.loadClass(basePackage + "RequestFacade$GetRequestDispatcherPrivilegedAction");
        loader.loadClass(basePackage + "RequestFacade$GetParameterPrivilegedAction");
        loader.loadClass(basePackage + "RequestFacade$GetParameterNamesPrivilegedAction");
        loader.loadClass(basePackage + "RequestFacade$GetParameterValuePrivilegedAction");
        loader.loadClass(basePackage + "RequestFacade$GetCharacterEncodingPrivilegedAction");
        loader.loadClass(basePackage + "RequestFacade$GetHeadersPrivilegedAction");
        loader.loadClass(basePackage + "RequestFacade$GetHeaderNamesPrivilegedAction");
        loader.loadClass(basePackage + "RequestFacade$GetCookiesPrivilegedAction");
        loader.loadClass(basePackage + "RequestFacade$GetLocalePrivilegedAction");
        loader.loadClass(basePackage + "RequestFacade$GetLocalesPrivilegedAction");
        loader.loadClass(basePackage + "ResponseFacade$SetContentTypePrivilegedAction");
        loader.loadClass(basePackage + "ResponseFacade$DateHeaderPrivilegedAction");
        loader.loadClass(basePackage + "RequestFacade$GetSessionPrivilegedAction");
        loadAnonymousInnerClasses(loader, basePackage + "ResponseFacade");
        loadAnonymousInnerClasses(loader, basePackage + "OutputBuffer");
        loadAnonymousInnerClasses(loader, basePackage + "CoyoteInputStream");
        loadAnonymousInnerClasses(loader, basePackage + "InputBuffer");
        loadAnonymousInnerClasses(loader, basePackage + "Response");
    }

    private static final void loadTomcatPackage(ClassLoader loader) throws Exception {
        final String basePackage = "org.apache.tomcat.";
        // buf
        loader.loadClass(basePackage + "util.buf.B2CConverter");
        loader.loadClass(basePackage + "util.buf.ByteBufferUtils");
        loader.loadClass(basePackage + "util.buf.C2BConverter");
        loader.loadClass(basePackage + "util.buf.HexUtils");
        loader.loadClass(basePackage + "util.buf.StringCache");
        loader.loadClass(basePackage + "util.buf.StringCache$ByteEntry");
        loader.loadClass(basePackage + "util.buf.StringCache$CharEntry");
        loader.loadClass(basePackage + "util.buf.UriUtil");
        // collections
        Class<?> clazz = loader.loadClass(basePackage + "util.collections.CaseInsensitiveKeyMap");
        // Ensure StringManager is configured
        clazz.getConstructor().newInstance();
        loader.loadClass(basePackage + "util.collections.CaseInsensitiveKeyMap$EntryImpl");
        loader.loadClass(basePackage + "util.collections.CaseInsensitiveKeyMap$EntryIterator");
        loader.loadClass(basePackage + "util.collections.CaseInsensitiveKeyMap$EntrySet");
        loader.loadClass(basePackage + "util.collections.CaseInsensitiveKeyMap$Key");
        // http
        loader.loadClass(basePackage + "util.http.CookieProcessor");
        loader.loadClass(basePackage + "util.http.NamesEnumerator");
        // Make sure system property is read at this point
        clazz = loader.loadClass(basePackage + "util.http.FastHttpDateFormat");
        clazz.getConstructor().newInstance();
        loader.loadClass(basePackage + "util.http.parser.HttpParser");
        loader.loadClass(basePackage + "util.http.parser.MediaType");
        loader.loadClass(basePackage + "util.http.parser.MediaTypeCache");
        loader.loadClass(basePackage + "util.http.parser.SkipResult");
        // net
        loader.loadClass(basePackage + "util.net.Constants");
        loader.loadClass(basePackage + "util.net.DispatchType");
        loader.loadClass(basePackage + "util.net.NioBlockingSelector$BlockPoller$RunnableAdd");
        loader.loadClass(basePackage + "util.net.NioBlockingSelector$BlockPoller$RunnableCancel");
        loader.loadClass(basePackage + "util.net.NioBlockingSelector$BlockPoller$RunnableRemove");
        // security
        loader.loadClass(basePackage + "util.security.PrivilegedGetTccl");
        loader.loadClass(basePackage + "util.security.PrivilegedSetTccl");
    }

    private static final void loadAnonymousInnerClasses(ClassLoader loader, String enclosingClass) {
        try {
            for (int i = 1;; i++) {
                loader.loadClass(enclosingClass + '$' + i);
            }
        } catch (ClassNotFoundException ignored) {
            //
        }
    }
}

// 初始化完成后，准备启动tomcat了

        // 启动时序
        if (command.equals("start")) {
            // 设置标志位
            daemon.setAwait(true);
            // 加载参数
            daemon.load(args);
            // 启动监听
            daemon.start();
            if (null == daemon.getServer()) {
                System.exit(1);
            }
        }

        
    /**
     * Set flag.
     * @param await <code>true</code> if the daemon should block
     * @throws Exception Reflection error
     */
    public void setAwait(boolean await)
        throws Exception {

        Class<?> paramTypes[] = new Class[1];
        paramTypes[0] = Boolean.TYPE;
        Object paramValues[] = new Object[1];
        paramValues[0] = Boolean.valueOf(await);
        Method method =
            catalinaDaemon.getClass().getMethod("setAwait", paramTypes);
        method.invoke(catalinaDaemon, paramValues);

    }
    
    
    // 加载参数配置，设置
    /**
     * Load daemon.
     */
    private void load(String[] arguments)
        throws Exception {

        // Call the load() method
        String methodName = "load";
        Object param[];
        Class<?> paramTypes[];
        if (arguments==null || arguments.length==0) {
            paramTypes = null;
            param = null;
        } else {
            paramTypes = new Class[1];
            paramTypes[0] = arguments.getClass();
            param = new Object[1];
            param[0] = arguments;
        }
        Method method =
            catalinaDaemon.getClass().getMethod(methodName, paramTypes);
        if (log.isDebugEnabled())
            log.debug("Calling startup class " + method);
        method.invoke(catalinaDaemon, param);

    }

// 调用 org.apache.catalina.startup.Catalina.load()

    /**
     * Start a new server instance.
     */
    public void load() {

        // 只加载一次
        if (loaded) {
            return;
        }
        loaded = true;

        long t1 = System.nanoTime();

        // 检查临时目录设置
        initDirs();

        // Before digester - it may be needed
        initNaming();

        // Create and execute our Digester
        // 初始化 server.xml 的配置项
        Digester digester = createStartDigester();

        InputSource inputSource = null;
        InputStream inputStream = null;
        File file = null;
        try {
            try {
                // 加载配置 server.xml
                file = configFile();
                inputStream = new FileInputStream(file);
                inputSource = new InputSource(file.toURI().toURL().toString());
            } catch (Exception e) {
                if (log.isDebugEnabled()) {
                    log.debug(sm.getString("catalina.configFail", file), e);
                }
            }
            if (inputStream == null) {
                try {
                    inputStream = getClass().getClassLoader()
                        .getResourceAsStream(getConfigFile());
                    inputSource = new InputSource
                        (getClass().getClassLoader()
                         .getResource(getConfigFile()).toString());
                } catch (Exception e) {
                    if (log.isDebugEnabled()) {
                        log.debug(sm.getString("catalina.configFail",
                                getConfigFile()), e);
                    }
                }
            }

            // This should be included in catalina.jar
            // Alternative: don't bother with xml, just create it manually.
            if (inputStream == null) {
                try {
                    inputStream = getClass().getClassLoader()
                            .getResourceAsStream("server-embed.xml");
                    inputSource = new InputSource
                    (getClass().getClassLoader()
                            .getResource("server-embed.xml").toString());
                } catch (Exception e) {
                    if (log.isDebugEnabled()) {
                        log.debug(sm.getString("catalina.configFail",
                                "server-embed.xml"), e);
                    }
                }
            }


            if (inputStream == null || inputSource == null) {
                if  (file == null) {
                    log.warn(sm.getString("catalina.configFail",
                            getConfigFile() + "] or [server-embed.xml]"));
                } else {
                    log.warn(sm.getString("catalina.configFail",
                            file.getAbsolutePath()));
                    if (file.exists() && !file.canRead()) {
                        log.warn("Permissions incorrect, read permission is not allowed on the file.");
                    }
                }
                return;
            }

            try {
                inputSource.setByteStream(inputStream);
                // Catalina 加入栈
                digester.push(this);
                digester.parse(inputSource);
            } catch (SAXParseException spe) {
                log.warn("Catalina.start using " + getConfigFile() + ": " +
                        spe.getMessage());
                return;
            } catch (Exception e) {
                log.warn("Catalina.start using " + getConfigFile() + ": " , e);
                return;
            }
        } finally {
            if (inputStream != null) {
                try {
                    inputStream.close();
                } catch (IOException e) {
                    // Ignore
                }
            }
        }

        getServer().setCatalina(this);
        getServer().setCatalinaHome(Bootstrap.getCatalinaHomeFile());
        getServer().setCatalinaBase(Bootstrap.getCatalinaBaseFile());

        // Stream redirection
        initStreams();

        // Start the new server
        try {
            getServer().init();
        } catch (LifecycleException e) {
            if (Boolean.getBoolean("org.apache.catalina.startup.EXIT_ON_INIT_FAILURE")) {
                throw new java.lang.Error(e);
            } else {
                log.error("Catalina.start", e);
            }
        }

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

    /**
     * Create and configure the Digester we will be using for startup.
     * @return the main digester to parse server.xml
     */
    protected Digester createStartDigester() {
        long t1=System.currentTimeMillis();
        // Initialize the digester
        Digester digester = new Digester();
        digester.setValidating(false);
        digester.setRulesValidation(true);
        HashMap<Class<?>, List<String>> fakeAttributes = new HashMap<>();
        ArrayList<String> attrs = new ArrayList<>();
        attrs.add("className");
        fakeAttributes.put(Object.class, attrs);
        digester.setFakeAttributes(fakeAttributes);
        digester.setUseContextClassLoader(true);

        // Configure the actions we will be using
        digester.addObjectCreate("Server",
                                 "org.apache.catalina.core.StandardServer",
                                 "className");
        digester.addSetProperties("Server");
        digester.addSetNext("Server",
                            "setServer",
                            "org.apache.catalina.Server");

        digester.addObjectCreate("Server/GlobalNamingResources",
                                 "org.apache.catalina.deploy.NamingResourcesImpl");
        digester.addSetProperties("Server/GlobalNamingResources");
        digester.addSetNext("Server/GlobalNamingResources",
                            "setGlobalNamingResources",
                            "org.apache.catalina.deploy.NamingResourcesImpl");

        digester.addObjectCreate("Server/Listener",
                                 null, // MUST be specified in the element
                                 "className");
        digester.addSetProperties("Server/Listener");
        digester.addSetNext("Server/Listener",
                            "addLifecycleListener",
                            "org.apache.catalina.LifecycleListener");

        digester.addObjectCreate("Server/Service",
                                 "org.apache.catalina.core.StandardService",
                                 "className");
        digester.addSetProperties("Server/Service");
        digester.addSetNext("Server/Service",
                            "addService",
                            "org.apache.catalina.Service");

        digester.addObjectCreate("Server/Service/Listener",
                                 null, // MUST be specified in the element
                                 "className");
        digester.addSetProperties("Server/Service/Listener");
        digester.addSetNext("Server/Service/Listener",
                            "addLifecycleListener",
                            "org.apache.catalina.LifecycleListener");

        //Executor
        digester.addObjectCreate("Server/Service/Executor",
                         "org.apache.catalina.core.StandardThreadExecutor",
                         "className");
        digester.addSetProperties("Server/Service/Executor");

        digester.addSetNext("Server/Service/Executor",
                            "addExecutor",
                            "org.apache.catalina.Executor");


        digester.addRule("Server/Service/Connector",
                         new ConnectorCreateRule());
        digester.addRule("Server/Service/Connector",
                         new SetAllPropertiesRule(new String[]{"executor", "sslImplementationName"}));
        digester.addSetNext("Server/Service/Connector",
                            "addConnector",
                            "org.apache.catalina.connector.Connector");

        digester.addObjectCreate("Server/Service/Connector/SSLHostConfig",
                                 "org.apache.tomcat.util.net.SSLHostConfig");
        digester.addSetProperties("Server/Service/Connector/SSLHostConfig");
        digester.addSetNext("Server/Service/Connector/SSLHostConfig",
                "addSslHostConfig",
                "org.apache.tomcat.util.net.SSLHostConfig");

        digester.addRule("Server/Service/Connector/SSLHostConfig/Certificate",
                         new CertificateCreateRule());
        digester.addRule("Server/Service/Connector/SSLHostConfig/Certificate",
                         new SetAllPropertiesRule(new String[]{"type"}));
        digester.addSetNext("Server/Service/Connector/SSLHostConfig/Certificate",
                            "addCertificate",
                            "org.apache.tomcat.util.net.SSLHostConfigCertificate");

        digester.addObjectCreate("Server/Service/Connector/SSLHostConfig/OpenSSLConf",
                                 "org.apache.tomcat.util.net.openssl.OpenSSLConf");
        digester.addSetProperties("Server/Service/Connector/SSLHostConfig/OpenSSLConf");
        digester.addSetNext("Server/Service/Connector/SSLHostConfig/OpenSSLConf",
                            "setOpenSslConf",
                            "org.apache.tomcat.util.net.openssl.OpenSSLConf");

        digester.addObjectCreate("Server/Service/Connector/SSLHostConfig/OpenSSLConf/OpenSSLConfCmd",
                                 "org.apache.tomcat.util.net.openssl.OpenSSLConfCmd");
        digester.addSetProperties("Server/Service/Connector/SSLHostConfig/OpenSSLConf/OpenSSLConfCmd");
        digester.addSetNext("Server/Service/Connector/SSLHostConfig/OpenSSLConf/OpenSSLConfCmd",
                            "addCmd",
                            "org.apache.tomcat.util.net.openssl.OpenSSLConfCmd");

        digester.addObjectCreate("Server/Service/Connector/Listener",
                                 null, // MUST be specified in the element
                                 "className");
        digester.addSetProperties("Server/Service/Connector/Listener");
        digester.addSetNext("Server/Service/Connector/Listener",
                            "addLifecycleListener",
                            "org.apache.catalina.LifecycleListener");

        digester.addObjectCreate("Server/Service/Connector/UpgradeProtocol",
                                  null, // MUST be specified in the element
                                  "className");
        digester.addSetProperties("Server/Service/Connector/UpgradeProtocol");
        digester.addSetNext("Server/Service/Connector/UpgradeProtocol",
                            "addUpgradeProtocol",
                            "org.apache.coyote.UpgradeProtocol");

        // Add RuleSets for nested elements
        digester.addRuleSet(new NamingRuleSet("Server/GlobalNamingResources/"));
        digester.addRuleSet(new EngineRuleSet("Server/Service/"));
        digester.addRuleSet(new HostRuleSet("Server/Service/Engine/"));
        digester.addRuleSet(new ContextRuleSet("Server/Service/Engine/Host/"));
        addClusterRuleSet(digester, "Server/Service/Engine/Host/Cluster/");
        digester.addRuleSet(new NamingRuleSet("Server/Service/Engine/Host/Context/"));

        // When the 'engine' is found, set the parentClassLoader.
        digester.addRule("Server/Service/Engine",
                         new SetParentClassLoaderRule(parentClassLoader));
        addClusterRuleSet(digester, "Server/Service/Engine/Cluster/");

        long t2=System.currentTimeMillis();
        if (log.isDebugEnabled()) {
            log.debug("Digester for server.xml created " + ( t2-t1 ));
        }
        return (digester);

    }
    
    
    protected File configFile() {

        File file = new File(configFile);
        if (!file.isAbsolute()) {
            file = new File(Bootstrap.getCatalinaBase(), configFile);
        }
        return (file);

    }

// org.apache.tomcat.util.digester.Digester.push() 入栈, parse() 解析配置文件

    /**
     * Push a new object onto the top of the object stack.
     *
     * @param object The new object
     */
    public void push(Object object) {

        if (stack.size() == 0) {
            root = object;
        }
        stack.push(object);

    }
    
    /**
     * Parse the content of the specified input source using this Digester.
     * Returns the root element from the object stack (if any).
     *
     * @param input Input source containing the XML data to be parsed
     * @return the root object
     * @exception IOException if an input/output error occurs
     * @exception SAXException if a parsing exception occurs
     */
    public Object parse(InputSource input) throws IOException, SAXException {

        configure();
        getXMLReader().parse(input);
        return (root);

    }

View Code

// org.apache.catalina.util.LifeCycleBase.init()

    @Override
    public final synchronized void init() throws LifecycleException {
        if (!state.equals(LifecycleState.NEW)) {
            invalidTransition(Lifecycle.BEFORE_INIT_EVENT);
        }

        try {
            setStateInternal(LifecycleState.INITIALIZING, null, false);
            initInternal();
            setStateInternal(LifecycleState.INITIALIZED, null, false);
        } catch (Throwable t) {
            ExceptionUtils.handleThrowable(t);
            setStateInternal(LifecycleState.FAILED, null, false);
            throw new LifecycleException(
                    sm.getString("lifecycleBase.initFail",toString()), t);
        }
    }

    // setStateInternal, 设置当前运行状态
    private synchronized void setStateInternal(LifecycleState state,
            Object data, boolean check) throws LifecycleException {

        if (log.isDebugEnabled()) {
            log.debug(sm.getString("lifecycleBase.setState", this, state));
        }

        if (check) {
            // Must have been triggered by one of the abstract methods (assume
            // code in this class is correct)
            // null is never a valid state
            if (state == null) {
                invalidTransition("null");
                // Unreachable code - here to stop eclipse complaining about
                // a possible NPE further down the method
                return;
            }

            // Any method can transition to failed
            // startInternal() permits STARTING_PREP to STARTING
            // stopInternal() permits STOPPING_PREP to STOPPING and FAILED to
            // STOPPING
            if (!(state == LifecycleState.FAILED ||
                    (this.state == LifecycleState.STARTING_PREP &&
                            state == LifecycleState.STARTING) ||
                    (this.state == LifecycleState.STOPPING_PREP &&
                            state == LifecycleState.STOPPING) ||
                    (this.state == LifecycleState.FAILED &&
                            state == LifecycleState.STOPPING))) {
                // No other transition permitted
                invalidTransition(state.name());
            }
        }

        this.state = state;
        String lifecycleEvent = state.getLifecycleEvent();
        if (lifecycleEvent != null) {
            fireLifecycleEvent(lifecycleEvent, data);
        }
    }

    // 进行事件监听通知
    /**
     * Allow sub classes to fire {@link Lifecycle} events.
     *
     * @param type  Event type
     * @param data  Data associated with event.
     */
    protected void fireLifecycleEvent(String type, Object data) {
        LifecycleEvent event = new LifecycleEvent(this, type, data);
        // NamingContextListener
        // VersionLoggerListener
        // AprLifecycleListener
        // JreMemoryLeakPreventionListener
        // GlobalResourcesLifecycleListener
        // ThreadLocalLeakPreventionListener
        for (LifecycleListener listener : lifecycleListeners) {
            listener.lifecycleEvent(event);
        }
    }

    // org.apache.catalina.core.StandardServer.initInternal()
    /**
     * Invoke a pre-startup initialization. This is used to allow connectors
     * to bind to restricted ports under Unix operating environments.
     */
    @Override
    protected void initInternal() throws LifecycleException {

        super.initInternal();

        // Register global String cache
        // Note although the cache is global, if there are multiple Servers
        // present in the JVM (may happen when embedding) then the same cache
        // will be registered under multiple names
        onameStringCache = register(new StringCache(), "type=StringCache");

        // Register the MBeanFactory
        MBeanFactory factory = new MBeanFactory();
        factory.setContainer(this);
        onameMBeanFactory = register(factory, "type=MBeanFactory");

        // Register the naming resources
        globalNamingResources.init();

        // Populate the extension validator with JARs from common and shared
        // class loaders
        if (getCatalina() != null) {
            ClassLoader cl = getCatalina().getParentClassLoader();
            // Walk the class loader hierarchy. Stop at the system class loader.
            // This will add the shared (if present) and common class loaders
            while (cl != null && cl != ClassLoader.getSystemClassLoader()) {
                if (cl instanceof URLClassLoader) {
                    URL[] urls = ((URLClassLoader) cl).getURLs();
                    for (URL url : urls) {
                        if (url.getProtocol().equals("file")) {
                            try {
                                File f = new File (url.toURI());
                                if (f.isFile() &&
                                        f.getName().endsWith(".jar")) {
                                    ExtensionValidator.addSystemResource(f);
                                }
                            } catch (URISyntaxException e) {
                                // Ignore
                            } catch (IOException e) {
                                // Ignore
                            }
                        }
                    }
                }
                cl = cl.getParent();
            }
        }
        // Initialize our defined Services
        for (int i = 0; i < services.length; i++) {
            services[i].init();
        }
    }
    
    // org.apache.catalina.util.LifecycleMBeanBase.initInternal()
    /**
     * Sub-classes wishing to perform additional initialization should override
     * this method, ensuring that super.initInternal() is the first call in the
     * overriding method.
     */
    @Override
    protected void initInternal() throws LifecycleException {

        // If oname is not null then registration has already happened via
        // preRegister().
        if (oname == null) {
            mserver = Registry.getRegistry(null, null).getMBeanServer();

            oname = register(this, getObjectNameKeyProperties());
        }
    }
    
    /**
     * Utility method to enable sub-classes to easily register additional
     * components that don't implement {@link JmxEnabled} with an MBean server.
     * <br>
     * Note: This method should only be used once {@link #initInternal()} has
     * been called and before {@link #destroyInternal()} has been called.
     *
     * @param obj                       The object the register
     * @param objectNameKeyProperties   The key properties component of the
     *                                  object name to use to register the
     *                                  object
     *
     * @return  The name used to register the object
     */
    protected final ObjectName register(Object obj,
            String objectNameKeyProperties) {

        // Construct an object name with the right domain
        StringBuilder name = new StringBuilder(getDomain());
        name.append(':');
        name.append(objectNameKeyProperties);

        ObjectName on = null;

        try {
            on = new ObjectName(name.toString());

            Registry.getRegistry(null, null).registerComponent(obj, on, null);
        } catch (MalformedObjectNameException e) {
            log.warn(sm.getString("lifecycleMBeanBase.registerFail", obj, name),
                    e);
        } catch (Exception e) {
            log.warn(sm.getString("lifecycleMBeanBase.registerFail", obj, name),
                    e);
        }

        return on;
    }
    

View Code

// org.apache.catalina.util.LifecycleBase.init()

    @Override
    public final synchronized void init() throws LifecycleException {
        if (!state.equals(LifecycleState.NEW)) {
            invalidTransition(Lifecycle.BEFORE_INIT_EVENT);
        }

        try {
            setStateInternal(LifecycleState.INITIALIZING, null, false);
            initInternal();
            setStateInternal(LifecycleState.INITIALIZED, null, false);
        } catch (Throwable t) {
            ExceptionUtils.handleThrowable(t);
            setStateInternal(LifecycleState.FAILED, null, false);
            throw new LifecycleException(
                    sm.getString("lifecycleBase.initFail",toString()), t);
        }
    }

// StandardService.initInternal() 初始化服务，线程池。。。

    /**
     * Invoke a pre-startup initialization. This is used to allow connectors
     * to bind to restricted ports under Unix operating environments.
     */
    @Override
    protected void initInternal() throws LifecycleException {

        super.initInternal();

        // engin init
        if (engine != null) {
            engine.init();
        }

        // Initialize any Executors
        for (Executor executor : findExecutors()) {
            if (executor instanceof JmxEnabled) {
                ((JmxEnabled) executor).setDomain(getDomain());
            }
            executor.init();
        }

        // Initialize mapper listener
        mapperListener.init();

        // Initialize our defined Connectors
        // 初始化连接器，如: Connector[HTTP/1.1-8080], Connector[AJP/1.3-8011]
        synchronized (connectorsLock) {
            for (Connector connector : connectors) {
                try {
                    connector.init();
                } catch (Exception e) {
                    String message = sm.getString(
                            "standardService.connector.initFailed", connector);
                    log.error(message, e);

                    if (Boolean.getBoolean("org.apache.catalina.startup.EXIT_ON_INIT_FAILURE"))
                        throw new LifecycleException(message);
                }
            }
        }
    }

// org.apache.catalina.core.StandardEngine.initInternal()

    @Override
    protected void initInternal() throws LifecycleException {
        // Ensure that a Realm is present before any attempt is made to start
        // one. This will create the default NullRealm if necessary.
        getRealm();
        super.initInternal();
    }
    
    
    // org.apache.catalina.core.ContainerBase.initInternal()
    // Catalina-startStop-xx 线程池创建
    @Override
    protected void initInternal() throws LifecycleException {
        BlockingQueue<Runnable> startStopQueue = new LinkedBlockingQueue<>();
        startStopExecutor = new ThreadPoolExecutor(
                getStartStopThreadsInternal(),
                getStartStopThreadsInternal(), 10, TimeUnit.SECONDS,
                startStopQueue,
                new StartStopThreadFactory(getName() + "-startStop-"));
        startStopExecutor.allowCoreThreadTimeOut(true);
        super.initInternal();
    }

    

// org.apache.catalina.connector.Connector
    @Override
    protected void initInternal() throws LifecycleException {

        super.initInternal();

        // Initialize adapter
        adapter = new CoyoteAdapter(this);
        protocolHandler.setAdapter(adapter);

        // Make sure parseBodyMethodsSet has a default
        if (null == parseBodyMethodsSet) {
            setParseBodyMethods(getParseBodyMethods());
        }

        if (protocolHandler.isAprRequired() && !AprLifecycleListener.isAprAvailable()) {
            throw new LifecycleException(sm.getString("coyoteConnector.protocolHandlerNoApr",
                    getProtocolHandlerClassName()));
        }
        if (AprLifecycleListener.isAprAvailable() && AprLifecycleListener.getUseOpenSSL() &&
                protocolHandler instanceof AbstractHttp11JsseProtocol) {
            AbstractHttp11JsseProtocol<?> jsseProtocolHandler =
                    (AbstractHttp11JsseProtocol<?>) protocolHandler;
            if (jsseProtocolHandler.isSSLEnabled() &&
                    jsseProtocolHandler.getSslImplementationName() == null) {
                // OpenSSL is compatible with the JSSE configuration, so use it if APR is available
                jsseProtocolHandler.setSslImplementationName(OpenSSLImplementation.class.getName());
            }
        }

        try {
            protocolHandler.init();
        } catch (Exception e) {
            throw new LifecycleException(
                    sm.getString("coyoteConnector.protocolHandlerInitializationFailed"), e);
        }
    }
    
    // org.apache.coyote.AbstractProtocol.init()
    @Override
    public void init() throws Exception {
        if (getLog().isInfoEnabled()) {
            getLog().info(sm.getString("abstractProtocolHandler.init", getName()));
        }

        if (oname == null) {
            // Component not pre-registered so register it
            oname = createObjectName();
            if (oname != null) {
                Registry.getRegistry(null, null).registerComponent(this, oname, null);
            }
        }

        if (this.domain != null) {
            rgOname = new ObjectName(domain + ":type=GlobalRequestProcessor,name=" + getName());
            Registry.getRegistry(null, null).registerComponent(
                    getHandler().getGlobal(), rgOname, null);
        }

        String endpointName = getName();
        endpoint.setName(endpointName.substring(1, endpointName.length()-1));
        endpoint.setDomain(domain);

        endpoint.init();
    }
    
    // org.apache.tomcat.util.net.AbstractEndpoint.init()
    public void init() throws Exception {
        if (bindOnInit) {
            bind();
            bindState = BindState.BOUND_ON_INIT;
        }
        if (this.domain != null) {
            // Register endpoint (as ThreadPool - historical name)
            oname = new ObjectName(domain + ":type=ThreadPool,name=/"" + getName() + "/"");
            Registry.getRegistry(null, null).registerComponent(this, oname, null);

            for (SSLHostConfig sslHostConfig : findSslHostConfigs()) {
                registerJmx(sslHostConfig);
            }
        }
    }

View Code

// NioEndpoint.bind(), 打开socket连接

    /**
     * Initialize the endpoint.
     */
    @Override
    public void bind() throws Exception {

        if (!getUseInheritedChannel()) {
            serverSock = ServerSocketChannel.open();
            socketProperties.setProperties(serverSock.socket());
            InetSocketAddress addr = (getAddress()!=null?new InetSocketAddress(getAddress(),getPort()):new InetSocketAddress(getPort()));
            serverSock.socket().bind(addr,getAcceptCount());
        } else {
            // Retrieve the channel provided by the OS
            Channel ic = System.inheritedChannel();
            if (ic instanceof ServerSocketChannel) {
                serverSock = (ServerSocketChannel) ic;
            }
            if (serverSock == null) {
                throw new IllegalArgumentException(sm.getString("endpoint.init.bind.inherited"));
            }
        }
        serverSock.configureBlocking(true); //mimic APR behavior

        // Initialize thread count defaults for acceptor, poller
        if (acceptorThreadCount == 0) {
            // FIXME: Doesn't seem to work that well with multiple accept threads
            acceptorThreadCount = 1;
        }
        if (pollerThreadCount <= 0) {
            //minimum one poller thread
            pollerThreadCount = 1;
        }
        // 闭锁控制
        setStopLatch(new CountDownLatch(pollerThreadCount));

        // Initialize SSL if needed
        initialiseSsl();

        // 打开 select 连接
        selectorPool.open();
    }
    
    // org.apache.tomcat.util.net.NioSelectorPool.open()
    public void open() throws IOException {
        enabled = true;
        getSharedSelector();
        if (SHARED) {
            blockingSelector = new NioBlockingSelector();
            blockingSelector.open(getSharedSelector());
        }

    }

// load() 完成后，回到 Bootstrap

// daemon.start();

    /**
     * Start the Catalina daemon.
     * @throws Exception Fatal start error
     */
    public void start()
        throws Exception {
        if( catalinaDaemon==null ) init();

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

    }

// org.apache.catalina.startup.Catalina.start()
    /**
     * Start a new server instance.
     */
    public void start() {

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

        // 如果经过前面的server初始化，还是获取不到 StandardServer
        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.start()
            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 注册关闭钩子，进行资源清理，server stop
        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);
            }
        }

        if (await) {
            await();
            stop();
        }
    }
    

    
    // LifeCycleBase.start()
    /**
     * {@inheritDoc}
     */
    @Override
    public final synchronized void start() throws LifecycleException {

        if (LifecycleState.STARTING_PREP.equals(state) || LifecycleState.STARTING.equals(state) ||
                LifecycleState.STARTED.equals(state)) {

            if (log.isDebugEnabled()) {
                Exception e = new LifecycleException();
                log.debug(sm.getString("lifecycleBase.alreadyStarted", toString()), e);
            } else if (log.isInfoEnabled()) {
                log.info(sm.getString("lifecycleBase.alreadyStarted", toString()));
            }

            return;
        }

        // 再次检测状态，确保初始化ok
        if (state.equals(LifecycleState.NEW)) {
            init();
        } else if (state.equals(LifecycleState.FAILED)) {
            stop();
        } else if (!state.equals(LifecycleState.INITIALIZED) &&
                !state.equals(LifecycleState.STOPPED)) {
            invalidTransition(Lifecycle.BEFORE_START_EVENT);
        }

        try {
            setStateInternal(LifecycleState.STARTING_PREP, null, false);
            startInternal();
            if (state.equals(LifecycleState.FAILED)) {
                // This is a 'controlled' failure. The component put itself into the
                // FAILED state so call stop() to complete the clean-up.
                stop();
            } else if (!state.equals(LifecycleState.STARTING)) {
                // Shouldn't be necessary but acts as a check that sub-classes are
                // doing what they are supposed to.
                invalidTransition(Lifecycle.AFTER_START_EVENT);
            } else {
                setStateInternal(LifecycleState.STARTED, null, false);
            }
        } catch (Throwable t) {
            // This is an 'uncontrolled' failure so put the component into the
            // FAILED state and throw an exception.
            ExceptionUtils.handleThrowable(t);
            setStateInternal(LifecycleState.FAILED, null, false);
            throw new LifecycleException(sm.getString("lifecycleBase.startFail", toString()), t);
        }
    }
    
    
    // 
    /**
     * Start nested components ({@link Service}s) and implement the requirements
     * of {@link org.apache.catalina.util.LifecycleBase#startInternal()}.
     *
     * @exception LifecycleException if this component detects a fatal error
     *  that prevents this component from being used
     */
    @Override
    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();
            }
        }
    }
    /**
     * Shutdown hook which will perform a clean shutdown of Catalina if needed.
     */
    protected class CatalinaShutdownHook extends Thread {

        @Override
        public void run() {
            try {
                if (getServer() != null) {
                    Catalina.this.stop();
                }
            } catch (Throwable ex) {
                ExceptionUtils.handleThrowable(ex);
                log.error(sm.getString("catalina.shutdownHookFail"), ex);
            } finally {
                // If JULI is used, shut JULI down *after* the server shuts down
                // so log messages aren't lost
                LogManager logManager = LogManager.getLogManager();
                if (logManager instanceof ClassLoaderLogManager) {
                    ((ClassLoaderLogManager) logManager).shutdown();
                }
            }
        }
    }

View Code

// 阻塞等待
    if (await) {
        await();
        stop();
    }

// org.apache.catalina.core.StandardServer
    /**
     * Wait until a proper shutdown command is received, then return.
     * This keeps the main thread alive - the thread pool listening for http
     * connections is daemon threads.
     */
    @Override
    public void await() {
        // Negative values - don't wait on port - tomcat is embedded or we just don't like ports
        if( port == -2 ) {
            // undocumented yet - for embedding apps that are around, alive.
            return;
        }
        if( port==-1 ) {
            try {
                awaitThread = Thread.currentThread();
                while(!stopAwait) {
                    try {
                        Thread.sleep( 10000 );
                    } catch( InterruptedException ex ) {
                        // continue and check the flag
                    }
                }
            } finally {
                awaitThread = null;
            }
            return;
        }

        // Set up a server socket to wait on
        try {
            awaitSocket = new ServerSocket(port, 1,
                    InetAddress.getByName(address));
        } catch (IOException e) {
            log.error("StandardServer.await: create[" + address
                               + ":" + port
                               + "]: ", e);
            return;
        }

        try {
            awaitThread = Thread.currentThread();

            // Loop waiting for a connection and a valid command
            // 进入正题，等待连接
            while (!stopAwait) {
                ServerSocket serverSocket = awaitSocket;
                if (serverSocket == null) {
                    break;
                }

                // Wait for the next connection
                Socket socket = null;
                StringBuilder command = new StringBuilder();
                try {
                    InputStream stream;
                    long acceptStartTime = System.currentTimeMillis();
                    try {
                        // 此处阻塞等待连接控制，一般端口为 8005
                        socket = serverSocket.accept();
                        socket.setSoTimeout(10 * 1000);  // Ten seconds
                        stream = socket.getInputStream();
                    } catch (SocketTimeoutException ste) {
                        // This should never happen but bug 56684 suggests that
                        // it does.
                        log.warn(sm.getString("standardServer.accept.timeout",
                                Long.valueOf(System.currentTimeMillis() - acceptStartTime)), ste);
                        continue;
                    } catch (AccessControlException ace) {
                        log.warn("StandardServer.accept security exception: "
                                + ace.getMessage(), ace);
                        continue;
                    } catch (IOException e) {
                        if (stopAwait) {
                            // Wait was aborted with socket.close()
                            break;
                        }
                        log.error("StandardServer.await: accept: ", e);
                        break;
                    }

                    // Read a set of characters from the socket
                    int expected = 1024; // Cut off to avoid DoS attack
                    while (expected < shutdown.length()) {
                        if (random == null)
                            random = new Random();
                        expected += (random.nextInt() % 1024);
                    }
                    while (expected > 0) {
                        int ch = -1;
                        try {
                            ch = stream.read();
                        } catch (IOException e) {
                            log.warn("StandardServer.await: read: ", e);
                            ch = -1;
                        }
                        // Control character or EOF (-1) terminates loop
                        if (ch < 32 || ch == 127) {
                            break;
                        }
                        command.append((char) ch);
                        expected--;
                    }
                } finally {
                    // Close the socket now that we are done with it
                    try {
                        if (socket != null) {
                            socket.close();
                        }
                    } catch (IOException e) {
                        // Ignore
                    }
                }

                // Match against our command string
                boolean match = command.toString().equals(shutdown);
                if (match) {
                    log.info(sm.getString("standardServer.shutdownViaPort"));
                    break;
                } else
                    log.warn("StandardServer.await: Invalid command '"
                            + command.toString() + "' received");
            }
        } finally {
            ServerSocket serverSocket = awaitSocket;
            awaitThread = null;
            awaitSocket = null;

            // Close the server socket and return
            if (serverSocket != null) {
                try {
                    serverSocket.close();
                } catch (IOException e) {
                    // Ignore
                }
            }
        }
    }
    
    // AbstractEndpoint.start()
    public final void start() throws Exception {
        if (bindState == BindState.UNBOUND) {
            bind();
            bindState = BindState.BOUND_ON_START;
        }
        startInternal();
    }
    
    // NioEndpoint.startInternal();
    /**
     * Start the NIO endpoint, creating acceptor, poller threads.
     */
    @Override
    public void startInternal() throws Exception {

        if (!running) {
            running = true;
            paused = false;

            processorCache = new SynchronizedStack<>(SynchronizedStack.DEFAULT_SIZE,
                    socketProperties.getProcessorCache());
            eventCache = new SynchronizedStack<>(SynchronizedStack.DEFAULT_SIZE,
                            socketProperties.getEventCache());
            nioChannels = new SynchronizedStack<>(SynchronizedStack.DEFAULT_SIZE,
                    socketProperties.getBufferPool());

            // Create worker collection
            if ( getExecutor() == null ) {
                createExecutor();
            }

            initializeConnectionLatch();

            // Start poller threads
            pollers = new Poller[getPollerThreadCount()];
            for (int i=0; i<pollers.length; i++) {
                pollers[i] = new Poller();
                Thread pollerThread = new Thread(pollers[i], getName() + "-ClientPoller-"+i);
                pollerThread.setPriority(threadPriority);
                pollerThread.setDaemon(true);
                pollerThread.start();
            }

            startAcceptorThreads();
        }
    }

    // AbstractEndpoint.createExecutor(), 创建excutor, 备用
    public void createExecutor() {
        internalExecutor = true;
        TaskQueue taskqueue = new TaskQueue();
        TaskThreadFactory tf = new TaskThreadFactory(getName() + "-exec-", daemon, getThreadPriority());
        executor = new ThreadPoolExecutor(getMinSpareThreads(), getMaxThreads(), 60, TimeUnit.SECONDS,taskqueue, tf);
        taskqueue.setParent( (ThreadPoolExecutor) executor);
    }

View Code

// NioEndpoint$Acceptor 进行请求监听

    /**
     * The background thread that listens for incoming TCP/IP connections and
     * hands them off to an appropriate processor.
     */
    protected class Acceptor extends AbstractEndpoint.Acceptor {

        @Override
        public void run() {

            int errorDelay = 0;

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

                // Loop if endpoint is paused
                while (paused && running) {
                    state = AcceptorState.PAUSED;
                    try {
                        Thread.sleep(50);
                    } catch (InterruptedException e) {
                        // Ignore
                    }
                }

                if (!running) {
                    break;
                }
                state = AcceptorState.RUNNING;

                try {
                    //if we have reached max connections, wait
                    countUpOrAwaitConnection();

                    SocketChannel socket = null;
                    try {
                        // Accept the next incoming connection from the server
                        // socket
                        socket = serverSock.accept();
                    } catch (IOException ioe) {
                        // We didn't get a socket
                        countDownConnection();
                        if (running) {
                            // Introduce delay if necessary
                            errorDelay = handleExceptionWithDelay(errorDelay);
                            // re-throw
                            throw ioe;
                        } else {
                            break;
                        }
                    }
                    // Successful accept, reset the error delay
                    errorDelay = 0;

                    // Configure the socket
                    if (running && !paused) {
                        // setSocketOptions() will hand the socket off to
                        // an appropriate processor if successful
                        // 真正去处理业务逻辑去了
                        if (!setSocketOptions(socket)) {
                            closeSocket(socket);
                        }
                    } else {
                        closeSocket(socket);
                    }
                } catch (Throwable t) {
                    ExceptionUtils.handleThrowable(t);
                    log.error(sm.getString("endpoint.accept.fail"), t);
                }
            }
            state = AcceptorState.ENDED;
        }


        private void closeSocket(SocketChannel socket) {
            countDownConnection();
            try {
                socket.socket().close();
            } catch (IOException ioe)  {
                if (log.isDebugEnabled()) {
                    log.debug(sm.getString("endpoint.err.close"), ioe);
                }
            }
            try {
                socket.close();
            } catch (IOException ioe) {
                if (log.isDebugEnabled()) {
                    log.debug(sm.getString("endpoint.err.close"), ioe);
                }
            }
        }
    }


    @Override
    protected SocketProcessorBase<NioChannel> createSocketProcessor(
            SocketWrapperBase<NioChannel> socketWrapper, SocketEvent event) {
        return new SocketProcessor(socketWrapper, event);
    }


    private void close(NioChannel socket, SelectionKey key) {
        try {
            if (socket.getPoller().cancelledKey(key) != null) {
                // SocketWrapper (attachment) was removed from the
                // key - recycle the key. This can only happen once
                // per attempted closure so it is used to determine
                // whether or not to return the key to the cache.
                // We do NOT want to do this more than once - see BZ
                // 57340 / 57943.
                if (log.isDebugEnabled()) {
                    log.debug("Socket: [" + socket + "] closed");
                }
                if (running && !paused) {
                    if (!nioChannels.push(socket)) {
                        socket.free();
                    }
                }
            }
        } catch (Exception x) {
            log.error("",x);
        }
    }

// 接收请求是: org.apache.tomcat.util.net.NioEndpoint$Acceptor

// 接收到后， NioEndpoint.setSocketOptions(SocketChannel socket)

// 注册处理事件 NioEndpoint$Poller.register(final NioChannel socket)

// NioEndpoint$Poller.doRun 进行事件处理

        /**
         * Registers a newly created socket with the poller.
         *
         * @param socket    The newly created socket
         */
        public void register(final NioChannel socket) {
            socket.setPoller(this);
            NioSocketWrapper ka = new NioSocketWrapper(socket, NioEndpoint.this);
            socket.setSocketWrapper(ka);
            ka.setPoller(this);
            ka.setReadTimeout(getSocketProperties().getSoTimeout());
            ka.setWriteTimeout(getSocketProperties().getSoTimeout());
            ka.setKeepAliveLeft(NioEndpoint.this.getMaxKeepAliveRequests());
            ka.setSecure(isSSLEnabled());
            ka.setReadTimeout(getConnectionTimeout());
            ka.setWriteTimeout(getConnectionTimeout());
            PollerEvent r = eventCache.pop();
            ka.interestOps(SelectionKey.OP_READ);//this is what OP_REGISTER turns into.
            if ( r==null) r = new PollerEvent(socket,ka,OP_REGISTER);
            else r.reset(socket,ka,OP_REGISTER);
            addEvent(r);
        }
    
        // 添加到事件Poller 队列, 并唤醒处理 selector
        private void addEvent(PollerEvent event) {
            events.offer(event);
            if ( wakeupCounter.incrementAndGet() == 0 ) selector.wakeup();
        }
        
// 后台消费队列, org.apache.tomcat.util.net.NioEndpoint$Poller 

        /**
         * The background thread that adds sockets to the Poller, checks the
         * poller for triggered events and hands the associated socket off to an
         * appropriate processor as events occur.
         */
        @Override
        public void run() {
            // Loop until destroy() is called
            while (true) {

                boolean hasEvents = false;

                try {
                    if (!close) {
                        hasEvents = events();
                        if (wakeupCounter.getAndSet(-1) > 0) {
                            //if we are here, means we have other stuff to do
                            //do a non blocking select
                            keyCount = selector.selectNow();
                        } else {
                            keyCount = selector.select(selectorTimeout);
                        }
                        wakeupCounter.set(0);
                    }
                    if (close) {
                        events();
                        timeout(0, false);
                        try {
                            selector.close();
                        } catch (IOException ioe) {
                            log.error(sm.getString("endpoint.nio.selectorCloseFail"), ioe);
                        }
                        break;
                    }
                } catch (Throwable x) {
                    ExceptionUtils.handleThrowable(x);
                    log.error("",x);
                    continue;
                }
                //either we timed out or we woke up, process events first
                if ( keyCount == 0 ) hasEvents = (hasEvents | events());

                Iterator<SelectionKey> iterator =
                    keyCount > 0 ? selector.selectedKeys().iterator() : null;
                // Walk through the collection of ready keys and dispatch
                // any active event.
                while (iterator != null && iterator.hasNext()) {
                    SelectionKey sk = iterator.next();
                    NioSocketWrapper attachment = (NioSocketWrapper)sk.attachment();
                    // Attachment may be null if another thread has called
                    // cancelledKey()
                    if (attachment == null) {
                        iterator.remove();
                    } else {
                        iterator.remove();
                        processKey(sk, attachment);
                    }
                }//while

                //process timeouts
                timeout(keyCount,hasEvents);
            }//while

            getStopLatch().countDown();
        }

        // NioEndpoint$Poller.timeout()
        protected void timeout(int keyCount, boolean hasEvents) {
            long now = System.currentTimeMillis();
            // This method is called on every loop of the Poller. Don't process
            // timeouts on every loop of the Poller since that would create too
            // much load and timeouts can afford to wait a few seconds.
            // However, do process timeouts if any of the following are true:
            // - the selector simply timed out (suggests there isn't much load)
            // - the nextExpiration time has passed
            // - the server socket is being closed
            if (nextExpiration > 0 && (keyCount > 0 || hasEvents) && (now < nextExpiration) && !close) {
                return;
            }
            //timeout
            int keycount = 0;
            try {
                for (SelectionKey key : selector.keys()) {
                    keycount++;
                    try {
                        NioSocketWrapper ka = (NioSocketWrapper) key.attachment();
                        if ( ka == null ) {
                            cancelledKey(key); //we don't support any keys without attachments
                        } else if (close) {
                            key.interestOps(0);
                            ka.interestOps(0); //avoid duplicate stop calls
                            processKey(key,ka);
                        } else if ((ka.interestOps()&SelectionKey.OP_READ) == SelectionKey.OP_READ ||
                                  (ka.interestOps()&SelectionKey.OP_WRITE) == SelectionKey.OP_WRITE) {
                            boolean isTimedOut = false;
                            // Check for read timeout
                            if ((ka.interestOps() & SelectionKey.OP_READ) == SelectionKey.OP_READ) {
                                long delta = now - ka.getLastRead();
                                long timeout = ka.getReadTimeout();
                                isTimedOut = timeout > 0 && delta > timeout;
                            }
                            // Check for write timeout
                            if (!isTimedOut && (ka.interestOps() & SelectionKey.OP_WRITE) == SelectionKey.OP_WRITE) {
                                long delta = now - ka.getLastWrite();
                                long timeout = ka.getWriteTimeout();
                                isTimedOut = timeout > 0 && delta > timeout;
                            }
                            if (isTimedOut) {
                                key.interestOps(0);
                                ka.interestOps(0); //avoid duplicate timeout calls
                                ka.setError(new SocketTimeoutException());
                                // 提交 excutor 执行逻辑，如交由框架处理
                                if (!processSocket(ka, SocketEvent.ERROR, true)) {
                                    cancelledKey(key);
                                }
                            }
                        }
                    }catch ( CancelledKeyException ckx ) {
                        cancelledKey(key);
                    }
                }//for
            } catch (ConcurrentModificationException cme) {
                // See https://bz.apache.org/bugzilla/show_bug.cgi?id=57943
                log.warn(sm.getString("endpoint.nio.timeoutCme"), cme);
            }
            long prevExp = nextExpiration; //for logging purposes only
            nextExpiration = System.currentTimeMillis() +
                    socketProperties.getTimeoutInterval();
            if (log.isTraceEnabled()) {
                log.trace("timeout completed: keys processed=" + keycount +
                        "; now=" + now + "; nextExpiration=" + prevExp +
                        "; keyCount=" + keyCount + "; hasEvents=" + hasEvents +
                        "; eval=" + ((now < prevExp) && (keyCount>0 || hasEvents) && (!close) ));
            }

        }
    }

// 处理业务逻辑 org.apache.tomcat.util.net.AbstractEndpoint.processSocket()

    /**
     * Process the given SocketWrapper with the given status. Used to trigger
     * processing as if the Poller (for those endpoints that have one)
     * selected the socket.
     *
     * @param socketWrapper The socket wrapper to process
     * @param event         The socket event to be processed
     * @param dispatch      Should the processing be performed on a new
     *                          container thread
     *
     * @return if processing was triggered successfully
     */
    public boolean processSocket(SocketWrapperBase<S> socketWrapper,
            SocketEvent event, boolean dispatch) {
        try {
            if (socketWrapper == null) {
                return false;
            }
            // 此处获取处理线程，即: org.apache.tomcat.util.net.NioEndpoint$SocketProcessor
            SocketProcessorBase<S> sc = processorCache.pop();
            if (sc == null) {
                sc = createSocketProcessor(socketWrapper, event);
            } else {
                sc.reset(socketWrapper, event);
            }
            Executor executor = getExecutor();
            // 如果有线程池，就异步处理，否则同步调用
            if (dispatch && executor != null) {
                executor.execute(sc);
            } else {
                sc.run();
            }
        } catch (RejectedExecutionException ree) {
            getLog().warn(sm.getString("endpoint.executor.fail", socketWrapper) , ree);
            return false;
        } catch (Throwable t) {
            ExceptionUtils.handleThrowable(t);
            // This means we got an OOM or similar creating a thread, or that
            // the pool and its queue are full
            getLog().error(sm.getString("endpoint.process.fail"), t);
            return false;
        }
        return true;
    }

// org.apache.tomcat.util.net.SocketProcessorBase 处理 run(), 子类实现 doRun() 方法。

    @Override
    public final void run() {
        synchronized (socketWrapper) {
            // It is possible that processing may be triggered for read and
            // write at the same time. The sync above makes sure that processing
            // does not occur in parallel. The test below ensures that if the
            // first event to be processed results in the socket being closed,
            // the subsequent events are not processed.
            if (socketWrapper.isClosed()) {
                return;
            }
            doRun();
        }
    }
    

// NioEndpoint$SocketProcessor 处理逻辑 
    /**
     * This class is the equivalent of the Worker, but will simply use in an
     * external Executor thread pool.
     */
    protected class SocketProcessor extends SocketProcessorBase<NioChannel> {

        public SocketProcessor(SocketWrapperBase<NioChannel> socketWrapper, SocketEvent event) {
            super(socketWrapper, event);
        }

        @Override
        protected void doRun() {
            NioChannel socket = socketWrapper.getSocket();
            SelectionKey key = socket.getIOChannel().keyFor(socket.getPoller().getSelector());

            try {
                int handshake = -1;

                try {
                    if (key != null) {
                        if (socket.isHandshakeComplete()) {
                            // No TLS handshaking required. Let the handler
                            // process this socket / event combination.
                            handshake = 0;
                        } else if (event == SocketEvent.STOP || event == SocketEvent.DISCONNECT ||
                                event == SocketEvent.ERROR) {
                            // Unable to complete the TLS handshake. Treat it as
                            // if the handshake failed.
                            handshake = -1;
                        } else {
                            handshake = socket.handshake(key.isReadable(), key.isWritable());
                            // The handshake process reads/writes from/to the
                            // socket. status may therefore be OPEN_WRITE once
                            // the handshake completes. However, the handshake
                            // happens when the socket is opened so the status
                            // must always be OPEN_READ after it completes. It
                            // is OK to always set this as it is only used if
                            // the handshake completes.
                            event = SocketEvent.OPEN_READ;
                        }
                    }
                } catch (IOException x) {
                    handshake = -1;
                    if (log.isDebugEnabled()) log.debug("Error during SSL handshake",x);
                } catch (CancelledKeyException ckx) {
                    handshake = -1;
                }
                if (handshake == 0) {
                    SocketState state = SocketState.OPEN;
                    // Process the request from this socket
                    // 转交控控权给业务系统
                    if (event == null) {
                        state = getHandler().process(socketWrapper, SocketEvent.OPEN_READ);
                    } else {
                        state = getHandler().process(socketWrapper, event);
                    }
                    if (state == SocketState.CLOSED) {
                        close(socket, key);
                    }
                } else if (handshake == -1 ) {
                    close(socket, key);
                } else if (handshake == SelectionKey.OP_READ){
                    socketWrapper.registerReadInterest();
                } else if (handshake == SelectionKey.OP_WRITE){
                    socketWrapper.registerWriteInterest();
                }
            } catch (CancelledKeyException cx) {
                socket.getPoller().cancelledKey(key);
            } catch (VirtualMachineError vme) {
                ExceptionUtils.handleThrowable(vme);
            } catch (Throwable t) {
                log.error("", t);
                socket.getPoller().cancelledKey(key);
            } finally {
                socketWrapper = null;
                event = null;
                //return to cache
                if (running && !paused) {
                    processorCache.push(this);
                }
            }
        }
    }

    
// org.apache.coyote.AbstractProtocol$ConnectionHandler  -> 获取到
        @Override
        public SocketState process(SocketWrapperBase<S> wrapper, SocketEvent status) {
            if (getLog().isDebugEnabled()) {
                getLog().debug(sm.getString("abstractConnectionHandler.process",
                        wrapper.getSocket(), status));
            }
            if (wrapper == null) {
                // Nothing to do. Socket has been closed.
                return SocketState.CLOSED;
            }

            S socket = wrapper.getSocket();

            Processor processor = connections.get(socket);
            if (getLog().isDebugEnabled()) {
                getLog().debug(sm.getString("abstractConnectionHandler.connectionsGet",
                        processor, socket));
            }

            // Async timeouts are calculated on a dedicated thread and then
            // dispatched. Because of delays in the dispatch process, the
            // timeout may no longer be required. Check here and avoid
            // unnecessary processing.
            if (SocketEvent.TIMEOUT == status && (processor == null ||
                    !processor.isAsync() || !processor.checkAsyncTimeoutGeneration())) {
                // This is effectively a NO-OP
                return SocketState.OPEN;
            }

            if (processor != null) {
                // Make sure an async timeout doesn't fire
                getProtocol().removeWaitingProcessor(processor);
            } else if (status == SocketEvent.DISCONNECT || status == SocketEvent.ERROR) {
                // Nothing to do. Endpoint requested a close and there is no
                // longer a processor associated with this socket.
                return SocketState.CLOSED;
            }

            ContainerThreadMarker.set();

            try {
                if (processor == null) {
                    String negotiatedProtocol = wrapper.getNegotiatedProtocol();
                    if (negotiatedProtocol != null) {
                        UpgradeProtocol upgradeProtocol =
                                getProtocol().getNegotiatedProtocol(negotiatedProtocol);
                        if (upgradeProtocol != null) {
                            processor = upgradeProtocol.getProcessor(
                                    wrapper, getProtocol().getAdapter());
                        } else if (negotiatedProtocol.equals("http/1.1")) {
                            // Explicitly negotiated the default protocol.
                            // Obtain a processor below.
                        } else {
                            // TODO:
                            // OpenSSL 1.0.2's ALPN callback doesn't support
                            // failing the handshake with an error if no
                            // protocol can be negotiated. Therefore, we need to
                            // fail the connection here. Once this is fixed,
                            // replace the code below with the commented out
                            // block.
                            if (getLog().isDebugEnabled()) {
                                getLog().debug(sm.getString(
                                    "abstractConnectionHandler.negotiatedProcessor.fail",
                                    negotiatedProtocol));
                            }
                            return SocketState.CLOSED;
                            /*
                             * To replace the code above once OpenSSL 1.1.0 is
                             * used.
                            // Failed to create processor. This is a bug.
                            throw new IllegalStateException(sm.getString(
                                    "abstractConnectionHandler.negotiatedProcessor.fail",
                                    negotiatedProtocol));
                            */
                        }
                    }
                }
                if (processor == null) {
                    processor = recycledProcessors.pop();
                    if (getLog().isDebugEnabled()) {
                        getLog().debug(sm.getString("abstractConnectionHandler.processorPop",
                                processor));
                    }
                }
                if (processor == null) {
                    processor = getProtocol().createProcessor();
                    register(processor);
                }

                processor.setSslSupport(
                        wrapper.getSslSupport(getProtocol().getClientCertProvider()));

                // Associate the processor with the connection
                connections.put(socket, processor);

                SocketState state = SocketState.CLOSED;
                do {
                    state = processor.process(wrapper, status);

                    if (state == SocketState.UPGRADING) {
                        // Get the HTTP upgrade handler
                        UpgradeToken upgradeToken = processor.getUpgradeToken();
                        // Retrieve leftover input
                        ByteBuffer leftOverInput = processor.getLeftoverInput();
                        if (upgradeToken == null) {
                            // Assume direct HTTP/2 connection
                            UpgradeProtocol upgradeProtocol = getProtocol().getUpgradeProtocol("h2c");
                            if (upgradeProtocol != null) {
                                processor = upgradeProtocol.getProcessor(
                                        wrapper, getProtocol().getAdapter());
                                wrapper.unRead(leftOverInput);
                                // Associate with the processor with the connection
                                connections.put(socket, processor);
                            } else {
                                if (getLog().isDebugEnabled()) {
                                    getLog().debug(sm.getString(
                                        "abstractConnectionHandler.negotiatedProcessor.fail",
                                        "h2c"));
                                }
                                return SocketState.CLOSED;
                            }
                        } else {
                            HttpUpgradeHandler httpUpgradeHandler = upgradeToken.getHttpUpgradeHandler();
                            // Release the Http11 processor to be re-used
                            release(processor);
                            // Create the upgrade processor
                            processor = getProtocol().createUpgradeProcessor(wrapper, upgradeToken);
                            if (getLog().isDebugEnabled()) {
                                getLog().debug(sm.getString("abstractConnectionHandler.upgradeCreate",
                                        processor, wrapper));
                            }
                            wrapper.unRead(leftOverInput);
                            // Mark the connection as upgraded
                            wrapper.setUpgraded(true);
                            // Associate with the processor with the connection
                            connections.put(socket, processor);
                            // Initialise the upgrade handler (which may trigger
                            // some IO using the new protocol which is why the lines
                            // above are necessary)
                            // This cast should be safe. If it fails the error
                            // handling for the surrounding try/catch will deal with
                            // it.
                            if (upgradeToken.getInstanceManager() == null) {
                                httpUpgradeHandler.init((WebConnection) processor);
                            } else {
                                ClassLoader oldCL = upgradeToken.getContextBind().bind(false, null);
                                try {
                                    httpUpgradeHandler.init((WebConnection) processor);
                                } finally {
                                    upgradeToken.getContextBind().unbind(false, oldCL);
                                }
                            }
                        }
                    }
                } while ( state == SocketState.UPGRADING);

                if (state == SocketState.LONG) {
                    // In the middle of processing a request/response. Keep the
                    // socket associated with the processor. Exact requirements
                    // depend on type of long poll
                    longPoll(wrapper, processor);
                    if (processor.isAsync()) {
                        getProtocol().addWaitingProcessor(processor);
                    }
                } else if (state == SocketState.OPEN) {
                    // In keep-alive but between requests. OK to recycle
                    // processor. Continue to poll for the next request.
                    connections.remove(socket);
                    release(processor);
                    wrapper.registerReadInterest();
                } else if (state == SocketState.SENDFILE) {
                    // Sendfile in progress. If it fails, the socket will be
                    // closed. If it works, the socket either be added to the
                    // poller (or equivalent) to await more data or processed
                    // if there are any pipe-lined requests remaining.
                } else if (state == SocketState.UPGRADED) {
                    // Don't add sockets back to the poller if this was a
                    // non-blocking write otherwise the poller may trigger
                    // multiple read events which may lead to thread starvation
                    // in the connector. The write() method will add this socket
                    // to the poller if necessary.
                    if (status != SocketEvent.OPEN_WRITE) {
                        longPoll(wrapper, processor);
                    }
                } else if (state == SocketState.SUSPENDED) {
                    // Don't add sockets back to the poller.
                    // The resumeProcessing() method will add this socket
                    // to the poller.
                } else {
                    // Connection closed. OK to recycle the processor. Upgrade
                    // processors are not recycled.
                    connections.remove(socket);
                    if (processor.isUpgrade()) {
                        UpgradeToken upgradeToken = processor.getUpgradeToken();
                        HttpUpgradeHandler httpUpgradeHandler = upgradeToken.getHttpUpgradeHandler();
                        InstanceManager instanceManager = upgradeToken.getInstanceManager();
                        if (instanceManager == null) {
                            httpUpgradeHandler.destroy();
                        } else {
                            ClassLoader oldCL = upgradeToken.getContextBind().bind(false, null);
                            try {
                                httpUpgradeHandler.destroy();
                            } finally {
                                try {
                                    instanceManager.destroyInstance(httpUpgradeHandler);
                                } catch (Throwable e) {
                                    ExceptionUtils.handleThrowable(e);
                                    getLog().error(sm.getString("abstractConnectionHandler.error"), e);
                                }
                                upgradeToken.getContextBind().unbind(false, oldCL);
                            }
                        }
                    } else {
                        release(processor);
                    }
                }
                return state;
            } catch(java.net.SocketException e) {
                // SocketExceptions are normal
                getLog().debug(sm.getString(
                        "abstractConnectionHandler.socketexception.debug"), e);
            } catch (java.io.IOException e) {
                // IOExceptions are normal
                getLog().debug(sm.getString(
                        "abstractConnectionHandler.ioexception.debug"), e);
            } catch (ProtocolException e) {
                // Protocol exceptions normally mean the client sent invalid or
                // incomplete data.
                getLog().debug(sm.getString(
                        "abstractConnectionHandler.protocolexception.debug"), e);
            }
            // Future developers: if you discover any other
            // rare-but-nonfatal exceptions, catch them here, and log as
            // above.
            catch (Throwable e) {
                ExceptionUtils.handleThrowable(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.
                getLog().error(sm.getString("abstractConnectionHandler.error"), e);
            } finally {
                ContainerThreadMarker.clear();
            }

            // Make sure socket/processor is removed from the list of current
            // connections
            connections.remove(socket);
            release(processor);
            return SocketState.CLOSED;
        }


// org.apache.coyote.http11.Http11Processor -> org.apache.coyote.AbstractProcessorLight
    @Override
    public SocketState process(SocketWrapperBase<?> socketWrapper, SocketEvent status)
            throws IOException {

        SocketState state = SocketState.CLOSED;
        Iterator<DispatchType> dispatches = null;
        do {
            if (dispatches != null) {
                DispatchType nextDispatch = dispatches.next();
                state = dispatch(nextDispatch.getSocketStatus());
            } else if (status == SocketEvent.DISCONNECT) {
                // Do nothing here, just wait for it to get recycled
            } else if (isAsync() || isUpgrade() || state == SocketState.ASYNC_END) {
                state = dispatch(status);
                if (state == SocketState.OPEN) {
                    // There may be pipe-lined data to read. If the data isn't
                    // processed now, execution will exit this loop and call
                    // release() which will recycle the processor (and input
                    // buffer) deleting any pipe-lined data. To avoid this,
                    // process it now.
                    state = service(socketWrapper);
                }
            } else if (status == SocketEvent.OPEN_WRITE) {
                // Extra write event likely after async, ignore
                state = SocketState.LONG;
            } else if (status == SocketEvent.OPEN_READ){
                state = service(socketWrapper);
            } else {
                // Default to closing the socket if the SocketEvent passed in
                // is not consistent with the current state of the Processor
                state = SocketState.CLOSED;
            }

            if (getLog().isDebugEnabled()) {
                getLog().debug("Socket: [" + socketWrapper +
                        "], Status in: [" + status +
                        "], State out: [" + state + "]");
            }

            if (state != SocketState.CLOSED && isAsync()) {
                state = asyncPostProcess();
                if (getLog().isDebugEnabled()) {
                    getLog().debug("Socket: [" + socketWrapper +
                            "], State after async post processing: [" + state + "]");
                }
            }

            if (dispatches == null || !dispatches.hasNext()) {
                // Only returns non-null iterator if there are
                // dispatches to process.
                dispatches = getIteratorAndClearDispatches();
            }
        } while (state == SocketState.ASYNC_END ||
                dispatches != null && state != SocketState.CLOSED);

        return state;
    }

View Code

// ... 已经很接近了

未完，待续...