零基础java自学流程-Java语言高级355

零基础java自学流程-Java语言高级355 CountDownLatch源码分析(基于JDK1.7.0_40)

CountDownLatch完整源码(基于JDK1.7.0_40)

  1 
 24 
 25 
 35 
 36 package java.util.concurrent;
 37 import java.util.concurrent.locks.*;
 38 import java.util.concurrent.atomic.*;
 39 
 40 
161 public class CountDownLatch {
162     
166     private static final class Sync extends AbstractQueuedSynchronizer {
167         private static final long serialVersionUID = 4982264981922014374L;
168 
169         Sync(int count) {
170             setState(count);
171         }
172 
173         int getCount() {
174             return getState();
175         }
176 
177         protected int tryAcquireShared(int acquires) {
178             return (getState() == 0) ? 1 : -1;
179         }
180 
181         protected boolean tryReleaseShared(int releases) {
182             // Decrement count; signal when transition to zero
183             for (;;) {
184                 int c = getState();
185                 if (c == 0)
186                     return false;
187                 int nextc = c-1;
188                 if (compareAndSetState(c, nextc))
189                     return nextc == 0;
190             }
191         }
192     }
193 
194     private final Sync sync;
195 
196     
203     public CountDownLatch(int count) {
204         if (count < 0) throw new IllegalArgumentException("count < 0");
205         this.sync = new Sync(count);
206     }
207 
208     
235     public void await() throws InterruptedException {
236         sync.acquireSharedInterruptibly(1);
237     }
238 
239     
280     public boolean await(long timeout, TimeUnit unit)
281         throws InterruptedException {
282         return sync.tryAcquireSharedNanos(1, unit.tonanos(timeout));
283     }
284 
285     
295     public void countDown() {
296         sync.releaseShared(1);
297     }
298 
299     
306     public long getCount() {
307         return sync.getCount();
308     }
309 
310     
317     public String toString() {
318         return super.toString() + "[Count = " + sync.getCount() + "]";
319     }
320 }

CountDownLatch是通过“共享锁”实现的。下面，我们分析CountDownLatch中3个核心函数: CountDownLatch(int count), await(), countDown()。

---

尚学堂给同学们带来全新的Java300集课程啦!java零基础小白自学Java必备优质教程_手把手图解学习Java，让学习成为一种享受_哔哩哔哩_bilibili尚学堂给同学们带来全新的Java300集课程啦本课程为Java300集2022版第一季，配合最新版的Java课程，所有视频重新录制，课件所有图形做了重新绘制和配色，图解学习Java，让学习成为一种享受本套教程专门为零基础学员而制，适合准备入行Java开发的零基础学员，视频中穿插多个实战项目。每一个知识点都讲解的通俗易懂，由浅入深。不仅适用于零基础的初学者，有经验的程序员也可做巩固学习。后续课https://www.bilibili.com/video/BV1qL411u7eE?spm_id_from=333.999.0.0