public RunnableScheduledFuture<?> poll(long timeout, TimeUnit unit)
throws InterruptedException {
long nanos = unit.toNanos(timeout);
final ReentrantLock lock = this.lock;
lock.lockInterruptibly();
try {
for (; ; ) {
RunnableScheduledFuture<?> first = queue[0];
if (first == null) {
if (nanos <= 0) return null;
else nanos = available.awaitNanos(nanos);
} else {
long delay = first.getDelay(NANOSECONDS);
if (delay <= 0) return finishPoll(first);
if (nanos <= 0) return null;
if (nanos < delay || leader != null) nanos = available.awaitNanos(nanos);
else {
Thread thisThread = Thread.currentThread();
leader = thisThread;
try {
long timeLeft = available.awaitNanos(delay);
nanos -= delay - timeLeft;
} finally {
if (leader == thisThread) leader = null;
}
}
}
}
} finally {
if (leader == null && queue[0] != null) available.signal();
lock.unlock();
}
}
public RunnableScheduledFuture<?> take() throws InterruptedException {
final ReentrantLock lock = this.lock;
lock.lockInterruptibly();
try {
for (; ; ) {
RunnableScheduledFuture<?> first = queue[0];
if (first == null) available.await();
else {
long delay = first.getDelay(NANOSECONDS);
if (delay <= 0) return finishPoll(first);
else if (leader != null) available.await();
else {
Thread thisThread = Thread.currentThread();
leader = thisThread;
try {
available.awaitNanos(delay);
} finally {
if (leader == thisThread) leader = null;
}
}
}
}
} finally {
if (leader == null && queue[0] != null) available.signal();
lock.unlock();
}
}
/**
* Main execution method for delayed or periodic tasks. If pool is shut down, rejects the task.
* Otherwise adds task to queue and starts a thread, if necessary, to run it. (We cannot prestart
* the thread to run the task because the task (probably) shouldn't be run yet,) If the pool is
* shut down while the task is being added, cancel and remove it if required by state and
* run-after-shutdown parameters.
*
* @param task the task
*/
private void delayedExecute(RunnableScheduledFuture<?> task) {
if (isShutdown()) reject(task);
else {
super.getQueue().add(task);
if (isShutdown() && !canRunInCurrentRunState(task.isPeriodic()) && remove(task))
task.cancel(false);
else ensurePrestart();
}
}
public RunnableScheduledFuture<?> poll() {
final ReentrantLock lock = this.lock;
lock.lock();
try {
RunnableScheduledFuture<?> first = queue[0];
if (first == null || first.getDelay(NANOSECONDS) > 0) return null;
else return finishPoll(first);
} finally {
lock.unlock();
}
}
/** Sift element added at top down to its heap-ordered spot. Call only when holding lock. */
private void siftDown(int k, RunnableScheduledFuture<?> key) {
int half = size >>> 1;
while (k < half) {
int child = (k << 1) + 1;
RunnableScheduledFuture<?> c = queue[child];
int right = child + 1;
if (right < size && c.compareTo(queue[right]) > 0) c = queue[child = right];
if (key.compareTo(c) <= 0) break;
queue[k] = c;
setIndex(c, k);
k = child;
}
queue[k] = key;
setIndex(key, k);
}
/**
* Requeues a periodic task unless current run state precludes it. Same idea as delayedExecute
* except drops task rather than rejecting.
*
* @param task the task
*/
void reExecutePeriodic(RunnableScheduledFuture<?> task) {
if (canRunInCurrentRunState(true)) {
super.getQueue().add(task);
if (!canRunInCurrentRunState(true) && remove(task)) task.cancel(false);
else ensurePrestart();
}
}
/** Sift element added at bottom up to its heap-ordered spot. Call only when holding lock. */
private void siftUp(int k, RunnableScheduledFuture<?> key) {
while (k > 0) {
int parent = (k - 1) >>> 1;
RunnableScheduledFuture<?> e = queue[parent];
if (key.compareTo(e) >= 0) break;
queue[k] = e;
setIndex(e, k);
k = parent;
}
queue[k] = key;
setIndex(key, k);
}
/**
* Cancels and clears the queue of all tasks that should not be run due to shutdown policy.
* Invoked within super.shutdown.
*/
@Override
void onShutdown() {
BlockingQueue<Runnable> q = super.getQueue();
boolean keepDelayed = getExecuteExistingDelayedTasksAfterShutdownPolicy();
boolean keepPeriodic = getContinueExistingPeriodicTasksAfterShutdownPolicy();
if (!keepDelayed && !keepPeriodic) {
for (Object e : q.toArray())
if (e instanceof RunnableScheduledFuture<?>) ((RunnableScheduledFuture<?>) e).cancel(false);
q.clear();
} else {
// Traverse snapshot to avoid iterator exceptions
for (Object e : q.toArray()) {
if (e instanceof RunnableScheduledFuture) {
RunnableScheduledFuture<?> t = (RunnableScheduledFuture<?>) e;
if ((t.isPeriodic() ? !keepPeriodic : !keepDelayed)
|| t.isCancelled()) { // also remove if already cancelled
if (q.remove(t)) t.cancel(false);
}
}
}
}
tryTerminate();
}
/**
* Return first element only if it is expired. Used only by drainTo. Call only when holding
* lock.
*/
private RunnableScheduledFuture<?> peekExpired() {
// assert lock.isHeldByCurrentThread();
RunnableScheduledFuture<?> first = queue[0];
return (first == null || first.getDelay(NANOSECONDS) > 0) ? null : first;
}
