信号量计数代码,Java代码库,德仔网

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【Java】信号量计数
作者:人生如歌 / 发布于2015/7/17/ 495

	package com.javapapers.thread;

	public class CountingSemaphore {
	 private int value = 0;
	 private int waitCount = 0;
	 private int notifyCount = 0;

	 public CountingSemaphore(int initial) {
	 if (initial > 0) {
	 value = initial;
	 }
	 }

	 public synchronized void waitForNotify() {
	 if (value <= waitCount) {
	 waitCount++;
	 try {
	 do {
	 wait();
	 } while (notifyCount == 0);
	 } catch (InterruptedException e) {
	 notify();
	 } finally {
	 waitCount--;
	 }
	 notifyCount--;
	 }
	 value--;
	 }

	 public synchronized void notifyToWakeup() {
	 value++;
	 if (waitCount > notifyCount) {
	 notifyCount++;
	 notify();
	 }
	 }
	}

	

	

	

	Binary Semaphore

	package com.javapapers.thread;

	public class BinarySemaphore {
	 private boolean locked = false;

	 BinarySemaphore(int initial) {
	 locked = (initial == 0);
	 }

	 public synchronized void waitForNotify() throws InterruptedException {
	 while (locked) {
	 wait();
	 }
	 locked = true;
	 }

	 public synchronized void notifyToWakeup() {
	 if (locked) {
	 notify();
	 }
	 locked = false;
	 }
	}
	测试类 SemaphoreABC.java

	package com.javapapers.thread;

	import java.util.Random;

	public class SemaphoreABC {
	 protected static final BinarySemaphore binarySemaphore0 = new BinarySemaphore(
	 0);
	 protected static final BinarySemaphore binarySemaphore1 = new BinarySemaphore(
	 1);
	 protected static final CountingSemaphore countingSemaphore = new CountingSemaphore(
	 0);

	 protected static final Random random = new Random();

	 public static void main(String args[]) throws InterruptedException {
	 new Thread(new ProcessA()).start();
	 new Thread(new ProcessB()).start();
	 new Thread(new ProcessC()).start();
	 Thread.sleep(9000);
	 System.exit(0);
	 }
	}
	ProcessA.java

	package com.javapapers.thread;

	public class ProcessA extends SemaphoreABC implements Runnable {
	 public void run() {
	 while (true) {
	 try {
	 Thread.sleep(1 + (int) (random.nextDouble() * 500));
	 } catch (InterruptedException e1) {
	 e1.printStackTrace();
	 }
	 System.out.print("A");
	 countingSemaphore.notifyToWakeup();
	 }
	 }
	}
	ProcessB.java

	package com.javapapers.thread;

	public class ProcessB extends SemaphoreABC implements Runnable {
	 public void run() {
	 while (true) {
	 try {
	 Thread.sleep(1 + (int) (random.nextDouble() * 800));
	 binarySemaphore1.waitForNotify();
	 } catch (InterruptedException e) {
	 e.printStackTrace();
	 }
	 countingSemaphore.waitForNotify();
	 System.out.print("B");
	 binarySemaphore0.notifyToWakeup();
	 }
	 }
	}
	ProcessC.java

	package com.javapapers.thread;

	public class ProcessC extends SemaphoreABC implements Runnable {
	 public void run() {
	 while (true) {
	 try {
	 Thread.sleep(1 + (int) (random.nextDouble() * 800));
	 binarySemaphore0.waitForNotify();
	 } catch (InterruptedException e) {
	 e.printStackTrace();
	 }
	 countingSemaphore.waitForNotify();
	 System.out.print("C");
	 binarySemaphore1.notifyToWakeup();
	 }
	 }
	}
	输出

	AABCABACAABCAABCAAABCABCABACAABCABACABACABACABAC
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