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ReentrantLock之AQS原理与lock()流程图

2019-12-30 09:43:36   3  举报

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ReentrantLock源码流程图与AQS原理

ReentrantLock

AQS

Lock

模版推荐

作者其他创作

大纲/内容

否

signal()

AQS

条件等待

获取了state就代表加锁成功

NULL

state

head

返回true

volatile Node head;volatile Node tail;volatile int state;Thread exclusiveOwnerThread

Node

tryAcquire()

thread3

currentThread==exclusiveOwnerThread

state+1

head节点是获得锁的

阻塞自旋

添加到队尾释放锁资源

失败

是

addWaiter添加到队尾

acquiredQueued()

thread0 释放锁release()中LockSupport.unpark(thread1)thread1在自旋中通过CAS获取锁状态并将自己设为head，获得锁成功

tryAcquire()之nonfairTryAcquire()

acquireQueued

end

thread2

自旋

重入

firstWaiter

tail

thread1

成功

tryAcquire失败

await()

非公平锁是nonfairTryAcquire()

acquire

start

setHead()

thread0

nextWaiter

获得锁

设置当前线程exclusiveOwnerThread

当前线程是否拥有锁判断是否重入

返回false

acquire()

volatile Node prev;volatile Node next;volatile Thread thread;volatile int waitStatus;Node nextWaiter;

非公平锁lock()

Condition

thread4

lastWaiter

LockSupport.park()阻塞

唤醒

Condition复用Node内部类

node.prev==head且tryAcquire()成功

state==0

 Collect

Get Started

ReentrantLock lock()流程

 Collect

Get Started

ReentrantLock之lock加锁过程

 Collect

Get Started

ReentrantLock（AQS）

 Collect

Get Started

AQS-ReentrantLock-Lock源码详解

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