保护性暂停

没有时间的限制

package org.example.concurrency.test;
import lombok.extern.slf4j.Slf4j;
import java.util.concurrent.TimeUnit;
/**
 * @author huskyui
 */
@Slf4j
public class GuardedObject {
    private Object response;
    public Object get(){
        synchronized (this){
            while (response == null){
                try{
                    this.wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            return response;
        }
    }
    public void complete(Object response){
        synchronized (this){
            this.response = response;
            this.notifyAll();
        }
    }
    public static void main(String[] args) {
        GuardedObject guardedObject = new GuardedObject();
        new Thread(()->{
            log.info("获取结果");
            String response = (String)guardedObject.get();
            log.info("结果{}",response);
        },"t1").start();
        new Thread(()->{
            log.info("执行任务");
            try {
                TimeUnit.SECONDS.sleep(2);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            guardedObject.complete(new String("hello"));
        },"t2").start();
    }
}

可以看到线程1在等待线程二的任务结束，后现场一获取结果

设置时间的限制

package org.example.concurrency.test;
import lombok.extern.slf4j.Slf4j;
import java.util.concurrent.TimeUnit;
/**
 * @author huskyui
 */
@Slf4j
public class GuardedObject {
    private Object response;
    public Object get() {
        synchronized (this) {
            while (response == null) {
                try {
                    this.wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            return response;
        }
    }
    public Object get(long timeout) {
        long begin = System.currentTimeMillis();
        long passedTime = 0;
        synchronized (this) {
            while (response == null) {
                long delay = timeout - passedTime;
                if (delay <= 0) {
                    break;
                }
                try {
                    this.wait(delay);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                passedTime = System.currentTimeMillis() - begin;
            }
            return response;
        }
    }
    public void complete(Object response) {
        synchronized (this) {
            this.response = response;
            this.notifyAll();
        }
    }
    public static void main(String[] args) {
        GuardedObject guardedObject = new GuardedObject();
        // t1线程等待t2线程的结果
        new Thread(() -> {
            log.info("获取结果");
            String response = (String) guardedObject.get(1500);
            log.info("结果{}", response);
        }, "t1").start();
        new Thread(() -> {
            log.info("执行任务");
            try {
                TimeUnit.SECONDS.sleep(2);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            guardedObject.complete(new String("hello"));
        }, "t2").start();
    }
}