elasticSearch6源码分析(1)启动过程

1.找到bin目录，下面有elasticSearch的sh文件，查看执行过程

  exec \
    "$JAVA" \
    $ES_JAVA_OPTS \
    -Des.path.home="$ES_HOME" \
    -Des.path.conf="$ES_PATH_CONF" \
    -Des.distribution.flavor="$ES_DISTRIBUTION_FLAVOR" \
    -Des.distribution.type="$ES_DISTRIBUTION_TYPE" \
    -cp "$ES_CLASSPATH" \
    org.elasticsearch.bootstrap.Elasticsearch \
    "$@"

可以看到主类的名称为：

Elasticsearch

2.主类Elasticsearch

找到main方法，父类

Command的execute()方法，ElasticSearch重写了该方法

    @Override
    protected void execute(Terminal terminal, OptionSet options, Environment env) throws UserException {
        if (options.nonOptionArguments().isEmpty() == false) {
            throw new UserException(ExitCodes.USAGE, "Positional arguments not allowed, found " + options.nonOptionArguments());
        }
        if (options.has(versionOption)) {
            final String versionOutput = String.format(
                    Locale.ROOT,
                    "Version: %s, Build: %s/%s/%s/%s, JVM: %s",
                    Version.displayVersion(Version.CURRENT, Build.CURRENT.isSnapshot()),
                    Build.CURRENT.flavor().displayName(),
                    Build.CURRENT.type().displayName(),
                    Build.CURRENT.shortHash(),
                    Build.CURRENT.date(),
                    JvmInfo.jvmInfo().version());
            terminal.println(versionOutput);
            return;
        }
 
        final boolean daemonize = options.has(daemonizeOption);
        final Path pidFile = pidfileOption.value(options);
        final boolean quiet = options.has(quietOption);
 
        // a misconfigured java.io.tmpdir can cause hard-to-diagnose problems later, so reject it immediately
        try {
            env.validateTmpFile();
        } catch (IOException e) {
            throw new UserException(ExitCodes.CONFIG, e.getMessage());
        }
 
        try {
            init(daemonize, pidFile, quiet, env);
        } catch (NodeValidationException e) {
            throw new UserException(ExitCodes.CONFIG, e.getMessage());
        }
    }
 
    void init(final boolean daemonize, final Path pidFile, final boolean quiet, Environment initialEnv)
        throws NodeValidationException, UserException {
        try {
            Bootstrap.init(!daemonize, pidFile, quiet, initialEnv);
        } catch (BootstrapException | RuntimeException e) {
            // format exceptions to the console in a special way
            // to avoid 2MB stacktraces from guice, etc.
            throw new StartupException(e);
        }
    }

2.启动类Bootstrap

init方法

  /**
     * This method is invoked by {@link Elasticsearch#main(String[])} to startup elasticsearch.
     */
    static void init(
            final boolean foreground,
            final Path pidFile,
            final boolean quiet,
            final Environment initialEnv) throws BootstrapException, NodeValidationException, UserException {
        // force the class initializer for BootstrapInfo to run before
        // the security manager is installed
        BootstrapInfo.init();
 
        INSTANCE = new Bootstrap();
 
        final SecureSettings keystore = loadSecureSettings(initialEnv);
        final Environment environment = createEnvironment(pidFile, keystore, initialEnv.settings(), initialEnv.configFile());
 
        LogConfigurator.setNodeName(Node.NODE_NAME_SETTING.get(environment.settings()));
        try {
            LogConfigurator.configure(environment);
        } catch (IOException e) {
            throw new BootstrapException(e);
        }
        if (environment.pidFile() != null) {
            try {
                PidFile.create(environment.pidFile(), true);
            } catch (IOException e) {
                throw new BootstrapException(e);
            }
        }
 
        final boolean closeStandardStreams = (foreground == false) || quiet;
        try {
            if (closeStandardStreams) {
                final Logger rootLogger = LogManager.getRootLogger();
                final Appender maybeConsoleAppender = Loggers.findAppender(rootLogger, ConsoleAppender.class);
                if (maybeConsoleAppender != null) {
                    Loggers.removeAppender(rootLogger, maybeConsoleAppender);
                }
                closeSystOut();
            }
 
            // fail if somebody replaced the lucene jars
            checkLucene();
 
            // install the default uncaught exception handler; must be done before security is
            // initialized as we do not want to grant the runtime permission
            // setDefaultUncaughtExceptionHandler
            Thread.setDefaultUncaughtExceptionHandler(new ElasticsearchUncaughtExceptionHandler());
 
            INSTANCE.setup(true, environment);
 
            try {
                // any secure settings must be read during node construction
                IOUtils.close(keystore);
            } catch (IOException e) {
                throw new BootstrapException(e);
            }
 
            INSTANCE.start();
 
            if (closeStandardStreams) {
                closeSysError();
            }
        } catch (NodeValidationException | RuntimeException e) {
            // disable console logging, so user does not see the exception twice (jvm will show it already)
            final Logger rootLogger = LogManager.getRootLogger();
            final Appender maybeConsoleAppender = Loggers.findAppender(rootLogger, ConsoleAppender.class);
            if (foreground && maybeConsoleAppender != null) {
                Loggers.removeAppender(rootLogger, maybeConsoleAppender);
            }
            Logger logger = LogManager.getLogger(Bootstrap.class);
            // HACK, it sucks to do this, but we will run users out of disk space otherwise
            if (e instanceof CreationException) {
                // guice: log the shortened exc to the log file
                ByteArrayOutputStream os = new ByteArrayOutputStream();
                PrintStream ps = null;
                try {
                    ps = new PrintStream(os, false, "UTF-8");
                } catch (UnsupportedEncodingException uee) {
                    assert false;
                    e.addSuppressed(uee);
                }
                new StartupException(e).printStackTrace(ps);
                ps.flush();
                try {
                    logger.error("Guice Exception: {}", os.toString("UTF-8"));
                } catch (UnsupportedEncodingException uee) {
                    assert false;
                    e.addSuppressed(uee);
                }
            } else if (e instanceof NodeValidationException) {
                logger.error("node validation exception\n{}", e.getMessage());
            } else {
                // full exception
                logger.error("Exception", e);
            }
            // re-enable it if appropriate, so they can see any logging during the shutdown process
            if (foreground && maybeConsoleAppender != null) {
                Loggers.addAppender(rootLogger, maybeConsoleAppender);
            }
 
            throw e;
        }
    }

找到红色的启动方法start，进去看，是Node的start方法

    private void start() throws NodeValidationException {
        node.start();
        keepAliveThread.start();
    }

3.节点启动Node

start方法

  /**
     * Start the node. If the node is already started, this method is no-op.
     */
    public Node start() throws NodeValidationException {
        if (!lifecycle.moveToStarted()) {
            return this;
        }
 
        logger.info("starting ...");
        pluginLifecycleComponents.forEach(LifecycleComponent::start);
 
        injector.getInstance(MappingUpdatedAction.class).setClient(client);
        injector.getInstance(IndicesService.class).start();
        injector.getInstance(IndicesClusterStateService.class).start();
        injector.getInstance(SnapshotsService.class).start();
        injector.getInstance(SnapshotShardsService.class).start();
        injector.getInstance(RoutingService.class).start();
        injector.getInstance(SearchService.class).start();
        nodeService.getMonitorService().start();
 
        final ClusterService clusterService = injector.getInstance(ClusterService.class);
 
        final NodeConnectionsService nodeConnectionsService = injector.getInstance(NodeConnectionsService.class);
        nodeConnectionsService.start();
        clusterService.setNodeConnectionsService(nodeConnectionsService);
 
        injector.getInstance(ResourceWatcherService.class).start();
        injector.getInstance(GatewayService.class).start();
        Discovery discovery = injector.getInstance(Discovery.class);
        clusterService.getMasterService().setClusterStatePublisher(discovery::publish);
 
        // Start the transport service now so the publish address will be added to the local disco node in ClusterService
        TransportService transportService = injector.getInstance(TransportService.class);
        transportService.getTaskManager().setTaskResultsService(injector.getInstance(TaskResultsService.class));
        transportService.start();
        assert localNodeFactory.getNode() != null;
        assert transportService.getLocalNode().equals(localNodeFactory.getNode())
            : "transportService has a different local node than the factory provided";
        final MetaData onDiskMetadata;
        try {
            // we load the global state here (the persistent part of the cluster state stored on disk) to
            // pass it to the bootstrap checks to allow plugins to enforce certain preconditions based on the recovered state.
            if (DiscoveryNode.isMasterNode(settings) || DiscoveryNode.isDataNode(settings)) {
                onDiskMetadata = injector.getInstance(GatewayMetaState.class).loadMetaState();
            } else {
                onDiskMetadata = MetaData.EMPTY_META_DATA;
            }
            assert onDiskMetadata != null : "metadata is null but shouldn't"; // this is never null
        } catch (IOException e) {
            throw new UncheckedIOException(e);
        }
        validateNodeBeforeAcceptingRequests(new BootstrapContext(settings, onDiskMetadata), transportService.boundAddress(), pluginsService
            .filterPlugins(Plugin
            .class)
            .stream()
            .flatMap(p -> p.getBootstrapChecks().stream()).collect(Collectors.toList()));
 
        clusterService.addStateApplier(transportService.getTaskManager());
        // start after transport service so the local disco is known
        discovery.start(); // start before cluster service so that it can set initial state on ClusterApplierService
        clusterService.start();
        assert clusterService.localNode().equals(localNodeFactory.getNode())
            : "clusterService has a different local node than the factory provided";
        transportService.acceptIncomingRequests();
        discovery.startInitialJoin();
        final TimeValue initialStateTimeout = DiscoverySettings.INITIAL_STATE_TIMEOUT_SETTING.get(settings);
        if (initialStateTimeout.millis() > 0) {
            final ThreadPool thread = injector.getInstance(ThreadPool.class);
            ClusterState clusterState = clusterService.state();
            ClusterStateObserver observer = new ClusterStateObserver(clusterState, clusterService, null, logger, thread.getThreadContext());
            if (clusterState.nodes().getMasterNodeId() == null) {
                logger.debug("waiting to join the cluster. timeout [{}]", initialStateTimeout);
                final CountDownLatch latch = new CountDownLatch(1);
                observer.waitForNextChange(new ClusterStateObserver.Listener() {
                    @Override
                    public void onNewClusterState(ClusterState state) { latch.countDown(); }
 
                    @Override
                    public void onClusterServiceClose() {
                        latch.countDown();
                    }
 
                    @Override
                    public void onTimeout(TimeValue timeout) {
                        logger.warn("timed out while waiting for initial discovery state - timeout: {}",
                            initialStateTimeout);
                        latch.countDown();
                    }
                }, state -> state.nodes().getMasterNodeId() != null, initialStateTimeout);
 
                try {
                    latch.await();
                } catch (InterruptedException e) {
                    throw new ElasticsearchTimeoutException("Interrupted while waiting for initial discovery state");
                }
            }
        }
 
        injector.getInstance(HttpServerTransport.class).start();
 
        if (WRITE_PORTS_FILE_SETTING.get(settings)) {
            TransportService transport = injector.getInstance(TransportService.class);
            writePortsFile("transport", transport.boundAddress());
            HttpServerTransport http = injector.getInstance(HttpServerTransport.class);
            writePortsFile("http", http.boundAddress());
        }
 
        logger.info("started");
 
        pluginsService.filterPlugins(ClusterPlugin.class).forEach(ClusterPlugin::onNodeStarted);
 
        return this;
    }

里面一个非常重要的对象Injector，我们看看它的定义：

/**
 * Builds the graphs of objects that make up your application. The injector tracks the dependencies
 * for each type and uses bindings to inject them. This is the core of Guice, although you rarely
 * interact with it directly. This "behind-the-scenes" operation is what distinguishes dependency
 * injection from its cousin, the service locator pattern.
 * <p>
 * Contains several default bindings:
 * <ul>
 * <li>This {@link Injector} instance itself
 * <li>A {@code Provider<T>} for each binding of type {@code T}
 * <li>The {@link java.util.logging.Logger} for the class being injected
 * <li>The {@link Stage} in which the Injector was created
 * </ul>
 * <p>
 * Injectors are created using the facade class {@link Guice}.
 * <p>
 * An injector can also {@link #injectMembers(Object) inject the dependencies} of
 * already-constructed instances. This can be used to interoperate with objects created by other
 * frameworks or services.
 *
 * @author crazybob@google.com (Bob Lee)
 * @author jessewilson@google.com (Jesse Wilson)
 */

简单的说，Injector是一个实例管理器，和spring中IOC的beanfactory功能相当。

需要启动的服务如下：

后续会针对每个服务做单独的分析