渣渣的 ElasticSearch 源码解析 —— 启动流程（下）

摘要：关注我转载请务必注明原创地址为前提上篇文章写完了流程启动的一部分，方法都入口，以及创建运行的必须环境以及相关配置，接着就是创建该环境的节点了。的创建看下新建节点的代码代码比较多，这里是比较关键的地方，我就把注释直接写在代码上面了，实在不好

转载请务必注明原创地址为：http://www.54tianzhisheng.cn/2018/08/12/es-code03/

上篇文章写完了 ES 流程启动的一部分，main 方法都入口，以及创建 Elasticsearch 运行的必须环境以及相关配置，接着就是创建该环境的节点了。

看下新建节点的代码：(代码比较多，这里是比较关键的地方，我就把注释直接写在代码上面了，实在不好拆开这段代码，300 多行代码)

public Node(Environment environment) {
        this(environment, Collections.emptyList()); //执行下面的代码
    }

protected Node(final Environment environment, Collection> classpathPlugins) {
    final List resourcesToClose = new ArrayList<>(); // register everything we need to release in the case of an error
    boolean success = false;
    {
// use temp logger just to say we are starting. we can"t use it later on because the node name might not be set
        Logger logger = Loggers.getLogger(Node.class, NODE_NAME_SETTING.get(environment.settings()));
        logger.info("initializing ...");
    }
    try {
        originalSettings = environment.settings();
        Settings tmpSettings = Settings.builder().put(environment.settings())
            .put(Client.CLIENT_TYPE_SETTING_S.getKey(), CLIENT_TYPE).build();

// create the node environment as soon as possible, to recover the node id and enable logging
        try {
            nodeEnvironment = new NodeEnvironment(tmpSettings, environment); //1、创建节点环境,比如节点名称,节点ID,分片信息,存储元,以及分配内存准备给节点使用
            resourcesToClose.add(nodeEnvironment);
        } catch (IOException ex) {
        throw new IllegalStateException("Failed to create node environment", ex);
        }
        final boolean hadPredefinedNodeName = NODE_NAME_SETTING.exists(tmpSettings);
        final String nodeId = nodeEnvironment.nodeId();
        tmpSettings = addNodeNameIfNeeded(tmpSettings, nodeId);
        final Logger logger = Loggers.getLogger(Node.class, tmpSettings);
// this must be captured after the node name is possibly added to the settings
        final String nodeName = NODE_NAME_SETTING.get(tmpSettings);
        if (hadPredefinedNodeName == false) {
            logger.info("node name derived from node ID [{}]; set [{}] to override", nodeId, NODE_NAME_SETTING.getKey());
        } else {
            logger.info("node name [{}], node ID [{}]", nodeName, nodeId);
        }

        //2、打印出JVM相关信息
        final JvmInfo jvmInfo = JvmInfo.jvmInfo();
        logger.info(
"version[{}], pid[{}], build[{}/{}/{}/{}], OS[{}/{}/{}], JVM[{}/{}/{}/{}]",
            Version.displayVersion(Version.CURRENT, Build.CURRENT.isSnapshot()),
            jvmInfo.pid(), Build.CURRENT.flavor().displayName(),
            Build.CURRENT.type().displayName(), Build.CURRENT.shortHash(),
            Build.CURRENT.date(), Constants.OS_NAME, Constants.OS_VERSION,
            Constants.OS_ARCH,Constants.JVM_VENDOR,Constants.JVM_NAME,
            Constants.JAVA_VERSION,Constants.JVM_VERSION);
        logger.info("JVM arguments {}", Arrays.toString(jvmInfo.getInputArguments()));
        //检查当前版本是不是 pre-release 版本（Snapshot），
        warnIfPreRelease(Version.CURRENT, Build.CURRENT.isSnapshot(), logger);
        。。。
        this.pluginsService = new PluginsService(tmpSettings, environment.configFile(), environment.modulesFile(), environment.pluginsFile(), classpathPlugins);   //3、利用PluginsService加载相应的模块和插件
        this.settings = pluginsService.updatedSettings();
        localNodeFactory = new LocalNodeFactory(settings, nodeEnvironment.nodeId());

// create the environment based on the finalized (processed) view of the settings
// this is just to makes sure that people get the same settings, no matter where they ask them from
        this.environment = new Environment(this.settings, environment.configFile());
        Environment.assertEquivalent(environment, this.environment);

        final List> executorBuilders = pluginsService.getExecutorBuilders(settings);        //线程池

        final ThreadPool threadPool = new ThreadPool(settings, executorBuilders.toArray(new ExecutorBuilder[0]));
        resourcesToClose.add(() -> ThreadPool.terminate(threadPool, 10, TimeUnit.SECONDS));
        // adds the context to the DeprecationLogger so that it does not need to be injected everywhere
        DeprecationLogger.setThreadContext(threadPool.getThreadContext());
        resourcesToClose.add(() -> DeprecationLogger.removeThreadContext(threadPool.getThreadContext()));

        final List> additionalSettings = new ArrayList<>(pluginsService.getPluginSettings());       //额外配置
        final List additionalSettingsFilter = new ArrayList<>(pluginsService.getPluginSettingsFilter());
        for (final ExecutorBuilder builder : threadPool.builders()) {
            //4、加载一些额外配置
            additionalSettings.addAll(builder.getRegisteredSettings());
        }
        client = new NodeClient(settings, threadPool);//5、创建一个节点客户端                                                                                  

        //6、缓存一系列模块,如NodeModule,ClusterModule,IndicesModule,ActionModule,GatewayModule,SettingsModule,RepositioriesModule，scriptModule，analysisModule
        final ResourceWatcherService resourceWatcherService = new ResourceWatcherService(settings, threadPool);
        final ScriptModule scriptModule = new ScriptModule(settings, pluginsService.filterPlugins(ScriptPlugin.class));
        AnalysisModule analysisModule = new AnalysisModule(this.environment, pluginsService.filterPlugins(AnalysisPlugin.class));
        // this is as early as we can validate settings at this point. we already pass them to ScriptModule as well as ThreadPool so we might be late here already
        final SettingsModule settingsModule = new SettingsModule(this.settings, additionalSettings, additionalSettingsFilter);
scriptModule.registerClusterSettingsListeners(settingsModule.getClusterSettings());
        resourcesToClose.add(resourceWatcherService);
        final NetworkService networkService = new NetworkService(
  getCustomNameResolvers(pluginsService.filterPlugins(DiscoveryPlugin.class)));
        List clusterPlugins = pluginsService.filterPlugins(ClusterPlugin.class);
        final ClusterService clusterService = new ClusterService(settings, settingsModule.getClusterSettings(), threadPool,                                                      ClusterModule.getClusterStateCustomSuppliers(clusterPlugins));
        clusterService.addStateApplier(scriptModule.getScriptService());
        resourcesToClose.add(clusterService);
        final IngestService ingestService = new IngestService(settings, threadPool, this.environment,                                                  scriptModule.getScriptService(), analysisModule.getAnalysisRegistry(), pluginsService.filterPlugins(IngestPlugin.class));
        final DiskThresholdMonitor listener = new DiskThresholdMonitor(settings, clusterService::state, clusterService.getClusterSettings(), client);
        final ClusterInfoService clusterInfoService = newClusterInfoService(settings, clusterService, threadPool, client,
listener::onNewInfo);
        final UsageService usageService = new UsageService(settings);

        ModulesBuilder modules = new ModulesBuilder();
// plugin modules must be added here, before others or we can get crazy injection errors...
        for (Module pluginModule : pluginsService.createGuiceModules()) {
            modules.add(pluginModule);
        }
        final MonitorService monitorService = new MonitorService(settings, nodeEnvironment, threadPool, clusterInfoService);
        ClusterModule clusterModule = new ClusterModule(settings, clusterService, clusterPlugins, clusterInfoService);
        modules.add(clusterModule);
        IndicesModule indicesModule = new IndicesModule(pluginsService.filterPlugins(MapperPlugin.class));
        modules.add(indicesModule);

        SearchModule searchModule = new SearchModule(settings, false, pluginsService.filterPlugins(SearchPlugin.class));
        CircuitBreakerService circuitBreakerService = createCircuitBreakerService(settingsModule.getSettings(),
                                                                                  settingsModule.getClusterSettings());
        resourcesToClose.add(circuitBreakerService);
        modules.add(new GatewayModule());

        PageCacheRecycler pageCacheRecycler = createPageCacheRecycler(settings);
        BigArrays bigArrays = createBigArrays(pageCacheRecycler, circuitBreakerService);
        resourcesToClose.add(bigArrays);
        modules.add(settingsModule);
        List namedWriteables = Stream.of(
            NetworkModule.getNamedWriteables().stream(),
            indicesModule.getNamedWriteables().stream(),
            searchModule.getNamedWriteables().stream(),
            pluginsService.filterPlugins(Plugin.class).stream()
            .flatMap(p -> p.getNamedWriteables().stream()),
            ClusterModule.getNamedWriteables().stream())
            .flatMap(Function.identity()).collect(Collectors.toList());
        final NamedWriteableRegistry namedWriteableRegistry = new NamedWriteableRegistry(namedWriteables);
        NamedXContentRegistry xContentRegistry = new NamedXContentRegistry(Stream.of(
            NetworkModule.getNamedXContents().stream(),
            searchModule.getNamedXContents().stream(),
            pluginsService.filterPlugins(Plugin.class).stream()
            .flatMap(p -> p.getNamedXContent().stream()),
            ClusterModule.getNamedXWriteables().stream())
.flatMap(Function.identity()).collect(toList()));
        modules.add(new RepositoriesModule(this.environment, pluginsService.filterPlugins(RepositoryPlugin.class), xContentRegistry));
        final MetaStateService metaStateService = new MetaStateService(settings, nodeEnvironment, xContentRegistry);
        final IndicesService indicesService = new IndicesService(settings, pluginsService, nodeEnvironment, xContentRegistry,
analysisModule.getAnalysisRegistry(),                                                                clusterModule.getIndexNameExpressionResolver(), indicesModule.getMapperRegistry(), namedWriteableRegistry,threadPool, settingsModule.getIndexScopedSettings(), circuitBreakerService, bigArrays, scriptModule.getScriptService(),client, metaStateService);

        Collection