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meout} 参数，表示给定粒度单位的持续时间
* @return 入参的 CompletableFuture
*/
public static <T> CompletableFuture<T> orTimeout(CompletableFuture<T> future, long timeout, TimeUnit unit) {
if (null == unit) {
throw new UncheckedException("时间的给定粒度不能为空");
}
if (null == future) {
throw new UncheckedException("异步任务不能为空");
}
if (future.isDone()) {
return future;
}
return future.whenComplete(new Canceller(Delayer.delay(new Timeout(future), timeout, unit)));
}
/**
* 超时时异常完成的操作
*/
static final class Timeout implements Runnable {
final CompletableFuture<?> future;
Timeout(CompletableFuture<?> future) {
this.future = future;
}
public void run() {
if (null != future && !future.isDone()) {
future.completeExceptionally(new TimeoutException());
}
}
}
/**
* 取消不需要的超时的操作
*/
static final class Canceller implements BiConsumer<Object, Throwable> {
final Future<?> future;
Canceller(Future<?> future) {
this.future = future;
}
public void accept(Object ignore, Throwable ex) {
if (null == ex && null != future && !future.isDone()) {
future.cancel(false);
}
}
}
/**
* 单例延迟调度器，仅用于启动和取消任务，一个线程就足够
*/
static final class Delayer {
static ScheduledFuture<?> delay(Runnable command, long delay, TimeUnit unit) {
return delayer.schedule(command, delay, unit);
}
static final class DaemonThreadFactory implements ThreadFactory {
public Thread newThread(Runnable r) {
Thread t = new Thread(r);
t.setDaemon(true);
t.setName("CompletableFutureExpandUtilsDelayScheduler");
return t;
}
}
static final ScheduledThreadPoolExecutor delayer;
static {
delayer = new ScheduledThreadPoolExecutor(1, new DaemonThreadFactory());
delayer.setRemoveOnCancelPolicy(true);
}
}
}
参考资料
- JEP 266: JDK 9 并发包更新提案
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