关于java:AQS源码学习记录-二ConditionObject源码分析

ConditionObject

ConditionObject是AQS中的外部类，用于线程间通信，能够准确唤醒某个线程。

ConditionObject中的成员变量是两个Node,别离形成FIFO队列的头节点和尾节点，condition队列中Node出队/入队，由每个节点Node中的static final int CONDITION = -2;中成员变量管制。

 // condition queue的头节点
 private transient Node firstWaiter;
 // condition queue的尾节点
 private transient Node lastWaiter;

先看下ConditionObject的waite()办法，它和Object的waite()办法一样，都是让线程期待。

public final void await() throws InterruptedException {
            if (Thread.interrupted())
                throw new InterruptedException();
            Node node = addConditionWaiter();
            int savedState = fullyRelease(node);
            int interruptMode = 0;
            while (!isOnSyncQueue(node)) {
                LockSupport.park(this);
                if ((interruptMode = checkInterruptWhileWaiting(node)) != 0)
                    break;
            }
            if (acquireQueued(node, savedState) && interruptMode != THROW_IE)
                interruptMode = REINTERRUPT;
            if (node.nextWaiter != null) // clean up if cancelled
                unlinkCancelledWaiters();
            if (interruptMode != 0)
                reportInterruptAfterWait(interruptMode);
        }