7、线程池之runWorker

final void runWorker(Worker w) {
        Thread wt = Thread.currentThread();
        Runnable task = w.firstTask;
        w.firstTask = null;
        //为什么要unlock一下？
        w.unlock(); // allow interrupts
        boolean completedAbruptly = true;
        try {
            //worker中封装的任务  或者   队列中存放的任务
            while (task != null || (task = getTask()) != null) {
                w.lock();
                /**
                 * Thread.interrupted()   返回当前线程的中断标志并且重置为false
                 * wt.isInterrupted()     返回线程wt的中断标志
                 * wt.interrupt();        给线程wt设置一个中断标志，线程仍会继续运行。
                 */
                //(Thread.interrupted() && runStateAtLeast(ctl.get(), STOP)) 这个条件是啥意思？
                if ((runStateAtLeast(ctl.get(), STOP) || (Thread.interrupted() && runStateAtLeast(ctl.get(), STOP)))
                        && !wt.isInterrupted())
                    wt.interrupt();
                try {
                    //任务执行前的前置处理
                    beforeExecute(wt, task);
                    Throwable thrown = null;
                    try {
                        task.run();
                    } catch (RuntimeException x) {
                        thrown = x; throw x;
                    } catch (Error x) {
                        thrown = x; throw x;
                    } catch (Throwable x) {
                        thrown = x; throw new Error(x);
                    } finally {
                        afterExecute(task, thrown);
                    }
                } finally {
                    //清空正在执行的任务
                    task = null;
                    //任务计数器
                    w.completedTasks++;
                    w.unlock();
                }
            }
            completedAbruptly = false;
        } finally {
            //结束一个工作线程
            processWorkerExit(w, completedAbruptly);
        }
    }