下面的 java 代码示例使用 java DelayQueue 来处理任务。但是，从另一个线程插入任务似乎会破坏（我的）预期行为。
很抱歉代码示例太长了，但总结一下：
- 主线程将 5 个任务（AE）添加到具有各种延迟（0ms、10ms、100ms、1000ms、10000ms）的延迟队列中
- 启动另一个线程，在 3000 毫秒后将另一个任务添加到延迟队列
- 主线程轮询 DelayQueue 并在每个 Task 过期时报告
- 8000ms后，主线程报告DelayQueue中剩余的Tasks
我从代码示例中得到的输出是：
------initial tasks ---------------
task A due in 0ms
task B due in 9ms
task C due in 99ms
task D due in 999ms
task E due in 9999ms
task F due in 99999ms
------processing--------------------
time = 5 task A due in -1ms
time = 14 task B due in 0ms
time = 104 task C due in 0ms
time = 1004 task D due in 0ms
time = 3003 added task Z due in 0ms
------remaining after 15007ms -----------
task F due in 84996ms
task E due in -5003ms
task Z due in -12004ms
我的问题是：为什么在 15000 毫秒后延迟队列中剩余过期的任务（即 GetDelay() 返回 -ve 值的地方）？
我检查过的一些事情：
- 我已经实现了 compareTo() 来定义任务的自然顺序
- equals() 与 compareTo() 一致
- hashCode() 已被覆盖
我最感兴趣的是学习如何解决这个问题。预先感谢您的协助。（以及迄今为止帮助我的所有 Stack Overflow 答案：）
package test;
import java.util.concurrent.DelayQueue;
import java.util.concurrent.Delayed;
import java.util.concurrent.TimeUnit;
public class Test10_DelayQueue {
private static final TimeUnit delayUnit = TimeUnit.MILLISECONDS;
private static final TimeUnit ripeUnit = TimeUnit.NANOSECONDS;
static long startTime;
static class Task implements Delayed {
public long ripe;
public String name;
public Task(String name, int delay) {
this.name = name;
ripe = System.nanoTime() + ripeUnit.convert(delay, delayUnit);
}
@Override
public boolean equals(Object obj) {
if (obj instanceof Task) {
return compareTo((Task) obj) == 0;
}
return false;
}
@Override
public int hashCode() {
int hash = 7;
hash = 67 * hash + (int) (this.ripe ^ (this.ripe >>> 32));
hash = 67 * hash + (this.name != null ? this.name.hashCode() : 0);
return hash;
}
@Override
public int compareTo(Delayed delayed) {
if (delayed instanceof Task) {
Task that = (Task) delayed;
return (int) (this.ripe - that.ripe);
}
throw new UnsupportedOperationException();
}
@Override
public long getDelay(TimeUnit unit) {
return unit.convert(ripe - System.nanoTime(), ripeUnit);
}
@Override
public String toString() {
return "task " + name + " due in " + String.valueOf(getDelay(delayUnit) + "ms");
}
}
static class TaskAdder implements Runnable {
DelayQueue dq;
int delay;
public TaskAdder(DelayQueue dq, int delay) {
this.dq = dq;
this.delay = delay;
}
@Override
public void run() {
try {
Thread.sleep(delay);
Task z = new Task("Z", 0);
dq.add(z);
Long elapsed = System.currentTimeMillis() - startTime;
System.out.println("time = " + elapsed + "\tadded " + z);
} catch (InterruptedException e) {
}
}
}
public static void main(String[] args) {
startTime = System.currentTimeMillis();
DelayQueue<Task> taskQ = new DelayQueue<Task>();
Thread thread = new Thread(new TaskAdder(taskQ, 3000));
thread.start();
taskQ.add(new Task("A", 0));
taskQ.add(new Task("B", 10));
taskQ.add(new Task("C", 100));
taskQ.add(new Task("D", 1000));
taskQ.add(new Task("E", 10000));
taskQ.add(new Task("F", 100000));
System.out.println("------initial tasks ---------------");
Task[] tasks = taskQ.toArray(new Task[0]);
for (int i = 0; i < tasks.length; i++) {
System.out.println(tasks[i]);
}
System.out.println("------processing--------------------");
try {
Long elapsed = System.currentTimeMillis() - startTime;
while (elapsed < 15000) {
Task task = taskQ.poll(1, TimeUnit.SECONDS);
elapsed = System.currentTimeMillis() - startTime;
if (task != null) {
System.out.println("time = " + elapsed + "\t" + task);
}
}
System.out.println("------remaining after " + elapsed + "ms -----------");
tasks = taskQ.toArray(new Task[0]);
for (int i = 0; i < tasks.length; i++) {
System.out.println(tasks[i]);
}
} catch (InterruptedException e) {
}
}
}