SingleThreadEventExecutor
从命名上可以看出，这是一个只有一个线程的线程池， 先看看其中的几个变量：
1、state：线程池当前的状态
2、taskQueue：存放任务的队列
3、thread：线程池维护的唯一线程
4、scheduledTaskQueue：定义在其父类AbstractScheduledEventExecutor中，用以保存延迟执行的任务。
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构造方法：
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protected SingleThreadEventExecutor(EventExecutorGroup parent, ThreadFactory threadFactory, boolean addTaskWakesUp) { if (threadFactory == null) { throw new NullPointerException("threadFactory"); } this.parent = parent; this.addTaskWakesUp = addTaskWakesUp; thread = threadFactory.newThread(new Runnable() { @Override public void run() { boolean success = false; updateLastExecutionTime(); try { SingleThreadEventExecutor.this.run(); success = true; } catch (Throwable t) { logger.warn("Unexpected exception from an event executor: ", t); } finally { for (;;) { int oldState = STATE_UPDATER.get(SingleThreadEventExecutor.this); if (oldState >= ST_SHUTTING_DOWN || STATE_UPDATER.compareAndSet( SingleThreadEventExecutor.this, oldState, ST_SHUTTING_DOWN)) { break; } } // Check if confirmShutdown() was called at the end of the loop. if (success && gracefulShutdownStartTime == 0) { logger.error( "Buggy " + EventExecutor.class.getSimpleName() + " implementation; " + SingleThreadEventExecutor.class.getSimpleName() + ".confirmShutdown() must be called " + "before run() implementation terminates."); } try { // Run all remaining tasks and shutdown hooks. for (;;) { if (confirmShutdown()) { break; } } } finally { try { cleanup(); } finally { STATE_UPDATER.set(SingleThreadEventExecutor.this, ST_TERMINATED); threadLock.release(); if (!taskQueue.isEmpty()) { logger.warn( "An event executor terminated with " + "non-empty task queue (" + taskQueue.size() + ')'); } terminationFuture.setSuccess(null); } } } } }); threadProperties = new DefaultThreadProperties(thread); taskQueue = newTaskQueue();}[url=][/url]
代码很长，内容很简单：
1、初始化一个线程，并在线程内部执行NioEventLoop类的run方法，当然这个线程不会立刻执行。
2、使用LinkedBlockingQueue类初始化taskQueue。 |
