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1.1 |
/* |
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1.4 |
* Written by Doug Lea with assistance from members of JCP JSR-166 |
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* Expert Group and released to the public domain. Use, modify, and |
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* redistribute this code in any way without acknowledgement. |
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1.1 |
*/ |
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package java.util.concurrent; |
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1.4 |
import java.util.concurrent.atomic.*; |
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1.2 |
import java.util.*; |
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1.1 |
|
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/** |
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1.17 |
* An <tt>Executor</tt> that can schedule commands to run after a given |
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1.7 |
* delay, or to execute periodically. This class is preferable to |
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1.1 |
* <tt>java.util.Timer</tt> when multiple worker threads are needed, |
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* or when the additional flexibility or capabilities of |
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1.7 |
* <tt>ThreadPoolExecutor</tt> (which this class extends) are |
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* required. |
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* |
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* <p> The <tt>schedule</tt> methods create tasks with various delays |
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* and return a task object that can be used to cancel or check |
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* execution. The <tt>scheduleAtFixedRate</tt> and |
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* <tt>scheduleWithFixedDelay</tt> methods create and execute tasks |
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* that run periodically until cancelled. Commands submitted using |
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* the <tt>execute</tt> method are scheduled with a requested delay of |
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* zero. |
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* |
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* <p> Delayed tasks execute no sooner than they are enabled, but |
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* without any real-time guarantees about when, after they are enabled |
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* they will commence. Tasks tied for the same execution time are |
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* enabled in first-in-first-out (FIFO) order of submission. An |
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* internal {@link DelayQueue} used for scheduling relies on relative |
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* delays, which may drift from absolute times (as returned by |
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* <tt>System.currentTimeMillis</tt>) over sufficiently long periods. |
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1.1 |
* |
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1.13 |
* <p>While this class inherits from {@link ThreadPoolExecutor}, a few |
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* of the inherited tuning methods are not especially useful for |
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* it. In particular, because a <tt>ScheduledExecutor</tt> always acts |
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* as a fixed-sized pool using <tt>corePoolSize</tt> threads and an |
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* unbounded queue, adjustments to <tt>maximumPoolSize</tt> have no |
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* useful effect. |
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* |
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1.1 |
* @since 1.5 |
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* @see Executors |
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* |
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* @spec JSR-166 |
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1.9 |
* @author Doug Lea |
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1.1 |
*/ |
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public class ScheduledExecutor extends ThreadPoolExecutor { |
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1.4 |
/** |
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1.18 |
* False if should cancel/suppress periodic tasks on shutdown. |
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*/ |
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private volatile boolean continueExistingPeriodicTasksAfterShutdown; |
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/** |
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* False if should cancel non-periodic tasks on shutdown. |
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*/ |
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private volatile boolean executeExistingDelayedTasksAfterShutdown = true; |
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/** |
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1.5 |
* Sequence number to break scheduling ties, and in turn to |
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* guarantee FIFO order among tied entries. |
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*/ |
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private static final AtomicLong sequencer = new AtomicLong(0); |
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1.21 |
|
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private static class ScheduledCancellableTask |
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extends CancellableTask implements ScheduledCancellable { |
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1.9 |
/** Sequence number to break ties FIFO */ |
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1.4 |
private final long sequenceNumber; |
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1.9 |
/** The time the task is enabled to execute in nanoTime units */ |
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1.4 |
private final long time; |
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1.9 |
/** The delay forllowing next time, or <= 0 if non-periodic */ |
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1.4 |
private final long period; |
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1.9 |
/** true if at fixed rate; false if fixed delay */ |
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private final boolean rateBased; |
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1.4 |
/** |
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1.5 |
* Creates a one-shot action with given nanoTime-based trigger time |
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1.4 |
*/ |
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1.21 |
ScheduledCancellableTask(Runnable r, long ns) { |
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1.4 |
super(r); |
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this.time = ns; |
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this.period = 0; |
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1.7 |
rateBased = false; |
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1.4 |
this.sequenceNumber = sequencer.getAndIncrement(); |
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} |
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/** |
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1.5 |
* Creates a periodic action with given nano time and period |
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1.4 |
*/ |
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1.21 |
ScheduledCancellableTask(Runnable r, long ns, long period, boolean rateBased) { |
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1.4 |
super(r); |
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if (period <= 0) |
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throw new IllegalArgumentException(); |
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this.time = ns; |
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this.period = period; |
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1.7 |
this.rateBased = rateBased; |
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1.4 |
this.sequenceNumber = sequencer.getAndIncrement(); |
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} |
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public long getDelay(TimeUnit unit) { |
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1.12 |
long d = unit.convert(time - System.nanoTime(), |
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1.7 |
TimeUnit.NANOSECONDS); |
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1.12 |
return d; |
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1.4 |
} |
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public int compareTo(Object other) { |
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1.18 |
if (other == this) // compare zero ONLY if same object |
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1.15 |
return 0; |
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1.21 |
ScheduledCancellableTask x = (ScheduledCancellableTask)other; |
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1.4 |
long diff = time - x.time; |
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if (diff < 0) |
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return -1; |
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else if (diff > 0) |
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return 1; |
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else if (sequenceNumber < x.sequenceNumber) |
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return -1; |
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else |
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return 1; |
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} |
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/** |
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* Return true if this is a periodic (not a one-shot) action. |
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1.9 |
* @return true if periodic |
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1.4 |
*/ |
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public boolean isPeriodic() { |
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return period > 0; |
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} |
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/** |
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1.11 |
* Returns the period, or zero if non-periodic. |
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* |
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1.9 |
* @return the period |
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1.4 |
*/ |
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public long getPeriod(TimeUnit unit) { |
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return unit.convert(period, TimeUnit.NANOSECONDS); |
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} |
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/** |
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1.21 |
* Return a new ScheduledCancellable that will trigger in the period |
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1.4 |
* subsequent to current task, or null if non-periodic |
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* or canceled. |
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*/ |
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1.21 |
ScheduledCancellableTask nextTask() { |
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1.4 |
if (period <= 0 || isCancelled()) |
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return null; |
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1.10 |
long nextTime = period + (rateBased ? time : System.nanoTime()); |
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1.21 |
return new ScheduledCancellableTask(getRunnable(), nextTime, period, rateBased); |
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1.4 |
} |
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} |
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1.21 |
|
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private static class ScheduledFutureTask<V> |
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extends ScheduledCancellableTask implements ScheduledFuture<V> { |
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1.4 |
/** |
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1.21 |
* Creates a ScheduledFuture that may trigger after the given delay. |
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1.4 |
*/ |
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1.21 |
ScheduledFutureTask(Callable<V> callable, long triggerTime) { |
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1.4 |
// must set after super ctor call to use inner class |
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1.17 |
super(null, triggerTime); |
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1.4 |
setRunnable(new InnerCancellableFuture<V>(callable)); |
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1.2 |
} |
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1.4 |
public V get() throws InterruptedException, ExecutionException { |
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return ((InnerCancellableFuture<V>)getRunnable()).get(); |
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1.2 |
} |
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1.4 |
public V get(long timeout, TimeUnit unit) |
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throws InterruptedException, ExecutionException, TimeoutException { |
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return ((InnerCancellableFuture<V>)getRunnable()).get(timeout, unit); |
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1.2 |
} |
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1.1 |
|
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1.4 |
protected void set(V v) { |
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((InnerCancellableFuture<V>)getRunnable()).set(v); |
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1.2 |
} |
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1.1 |
|
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1.4 |
protected void setException(Throwable t) { |
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((InnerCancellableFuture<V>)getRunnable()).setException(t); |
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} |
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} |
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/** |
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* An annoying wrapper class to convince generics compiler to |
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1.21 |
* use a DelayQueue<ScheduledCancellableTask> as a BlockingQueue<Runnable> |
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1.4 |
*/ |
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1.21 |
private static class DelayedWorkQueue |
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extends AbstractCollection<Runnable> implements BlockingQueue<Runnable> { |
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private final DelayQueue<ScheduledCancellableTask> dq = new DelayQueue<ScheduledCancellableTask>(); |
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1.4 |
public Runnable poll() { return dq.poll(); } |
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public Runnable peek() { return dq.peek(); } |
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public Runnable take() throws InterruptedException { return dq.take(); } |
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public Runnable poll(long timeout, TimeUnit unit) throws InterruptedException { |
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return dq.poll(timeout, unit); |
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1.2 |
} |
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1.12 |
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1.21 |
public boolean add(Runnable x) { return dq.add((ScheduledCancellableTask)x); } |
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public boolean offer(Runnable x) { return dq.offer((ScheduledCancellableTask)x); } |
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1.4 |
public void put(Runnable x) throws InterruptedException { |
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1.21 |
dq.put((ScheduledCancellableTask)x); |
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1.2 |
} |
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1.4 |
public boolean offer(Runnable x, long timeout, TimeUnit unit) throws InterruptedException { |
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1.21 |
return dq.offer((ScheduledCancellableTask)x, timeout, unit); |
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1.2 |
} |
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1.12 |
|
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public Runnable remove() { return dq.remove(); } |
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public Runnable element() { return dq.element(); } |
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public void clear() { dq.clear(); } |
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1.4 |
public int remainingCapacity() { return dq.remainingCapacity(); } |
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public boolean remove(Object x) { return dq.remove(x); } |
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public boolean contains(Object x) { return dq.contains(x); } |
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public int size() { return dq.size(); } |
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1.11 |
public boolean isEmpty() { return dq.isEmpty(); } |
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1.4 |
public Iterator<Runnable> iterator() { |
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return new Iterator<Runnable>() { |
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1.21 |
private Iterator<ScheduledCancellableTask> it = dq.iterator(); |
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1.4 |
public boolean hasNext() { return it.hasNext(); } |
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public Runnable next() { return it.next(); } |
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public void remove() { it.remove(); } |
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}; |
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tim |
1.1 |
} |
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1.4 |
} |
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tim |
1.1 |
|
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1.4 |
/** |
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* Creates a new ScheduledExecutor with the given initial parameters. |
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* |
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* @param corePoolSize the number of threads to keep in the pool, |
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* even if they are idle. |
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*/ |
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public ScheduledExecutor(int corePoolSize) { |
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super(corePoolSize, Integer.MAX_VALUE, 0, TimeUnit.NANOSECONDS, |
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new DelayedWorkQueue()); |
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} |
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tim |
1.1 |
|
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dl |
1.4 |
/** |
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* Creates a new ScheduledExecutor with the given initial parameters. |
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* |
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* @param corePoolSize the number of threads to keep in the pool, |
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* even if they are idle. |
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* @param threadFactory the factory to use when the executor |
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* creates a new thread. |
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*/ |
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public ScheduledExecutor(int corePoolSize, |
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ThreadFactory threadFactory) { |
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super(corePoolSize, Integer.MAX_VALUE, 0, TimeUnit.NANOSECONDS, |
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new DelayedWorkQueue(), threadFactory); |
252 |
tim |
1.1 |
} |
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dl |
1.4 |
/** |
255 |
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* Creates a new ScheduledExecutor with the given initial parameters. |
256 |
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* |
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* @param corePoolSize the number of threads to keep in the pool, |
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* even if they are idle. |
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* @param handler the handler to use when execution is blocked |
260 |
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* because the thread bounds and queue capacities are reached. |
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*/ |
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public ScheduledExecutor(int corePoolSize, |
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RejectedExecutionHandler handler) { |
264 |
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super(corePoolSize, Integer.MAX_VALUE, 0, TimeUnit.NANOSECONDS, |
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new DelayedWorkQueue(), handler); |
266 |
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} |
267 |
dl |
1.2 |
|
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tim |
1.1 |
/** |
269 |
dl |
1.2 |
* Creates a new ScheduledExecutor with the given initial parameters. |
270 |
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* |
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* @param corePoolSize the number of threads to keep in the pool, |
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* even if they are idle. |
273 |
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1.4 |
* @param threadFactory the factory to use when the executor |
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* creates a new thread. |
275 |
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* @param handler the handler to use when execution is blocked |
276 |
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* because the thread bounds and queue capacities are reached. |
277 |
tim |
1.1 |
*/ |
278 |
dl |
1.4 |
public ScheduledExecutor(int corePoolSize, |
279 |
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ThreadFactory threadFactory, |
280 |
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RejectedExecutionHandler handler) { |
281 |
dl |
1.2 |
super(corePoolSize, Integer.MAX_VALUE, 0, TimeUnit.NANOSECONDS, |
282 |
dl |
1.4 |
new DelayedWorkQueue(), threadFactory, handler); |
283 |
dl |
1.13 |
} |
284 |
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/** |
286 |
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* Specialized variant of ThreadPoolExecutor.execute for delayed tasks. |
287 |
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*/ |
288 |
dl |
1.18 |
private void delayedExecute(Runnable command) { |
289 |
dl |
1.13 |
if (isShutdown()) { |
290 |
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reject(command); |
291 |
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return; |
292 |
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} |
293 |
dl |
1.18 |
// Prestart a thread if necessary. We cannot prestart it |
294 |
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// running the task because the task (probably) shouldn't be |
295 |
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// run yet, so thread will just idle until delay elapses. |
296 |
dl |
1.13 |
if (getPoolSize() < getCorePoolSize()) |
297 |
dl |
1.18 |
prestartCoreThread(); |
298 |
dl |
1.13 |
|
299 |
dl |
1.20 |
super.getQueue().offer(command); |
300 |
dl |
1.4 |
} |
301 |
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302 |
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/** |
303 |
dl |
1.7 |
* Creates and executes a one-shot action that becomes enabled after |
304 |
dl |
1.4 |
* the given delay. |
305 |
dl |
1.6 |
* @param command the task to execute. |
306 |
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* @param delay the time from now to delay execution. |
307 |
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* @param unit the time unit of the delay parameter. |
308 |
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* @return a handle that can be used to cancel the task. |
309 |
dl |
1.17 |
* @throws RejectedExecutionException if task cannot be scheduled |
310 |
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* for execution because the executor has been shut down. |
311 |
dl |
1.4 |
*/ |
312 |
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|
313 |
tim |
1.21 |
public ScheduledCancellable schedule(Runnable command, long delay, TimeUnit unit) { |
314 |
dl |
1.17 |
long triggerTime = System.nanoTime() + unit.toNanos(delay); |
315 |
tim |
1.21 |
ScheduledCancellableTask t = new ScheduledCancellableTask(command, triggerTime); |
316 |
dl |
1.13 |
delayedExecute(t); |
317 |
dl |
1.4 |
return t; |
318 |
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} |
319 |
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320 |
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/** |
321 |
dl |
1.9 |
* Creates and executes a one-shot action that becomes enabled |
322 |
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* after the given date. |
323 |
dl |
1.6 |
* @param command the task to execute. |
324 |
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* @param date the time to commence excution. |
325 |
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* @return a handle that can be used to cancel the task. |
326 |
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* @throws RejectedExecutionException if task cannot be scheduled |
327 |
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* for execution because the executor has been shut down. |
328 |
dl |
1.4 |
*/ |
329 |
tim |
1.21 |
public ScheduledCancellable schedule(Runnable command, Date date) { |
330 |
dl |
1.17 |
long triggerTime = System.nanoTime() + |
331 |
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TimeUnit.MILLISECONDS.toNanos(date.getTime() - |
332 |
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System.currentTimeMillis()); |
333 |
tim |
1.21 |
ScheduledCancellableTask t = new ScheduledCancellableTask(command, triggerTime); |
334 |
dl |
1.13 |
delayedExecute(t); |
335 |
dl |
1.4 |
return t; |
336 |
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} |
337 |
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338 |
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/** |
339 |
dl |
1.7 |
* Creates and executes a periodic action that becomes enabled first |
340 |
dl |
1.4 |
* after the given initial delay, and subsequently with the given |
341 |
dl |
1.7 |
* period; that is executions will commence after |
342 |
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* <tt>initialDelay</tt> then <tt>initialDelay+period</tt>, then |
343 |
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* <tt>initialDelay + 2 * period</tt>, and so on. |
344 |
dl |
1.6 |
* @param command the task to execute. |
345 |
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* @param initialDelay the time to delay first execution. |
346 |
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* @param period the period between successive executions. |
347 |
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* @param unit the time unit of the delay and period parameters |
348 |
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* @return a handle that can be used to cancel the task. |
349 |
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* @throws RejectedExecutionException if task cannot be scheduled |
350 |
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* for execution because the executor has been shut down. |
351 |
dl |
1.4 |
*/ |
352 |
tim |
1.21 |
public ScheduledCancellable scheduleAtFixedRate(Runnable command, long initialDelay, long period, TimeUnit unit) { |
353 |
dl |
1.17 |
long triggerTime = System.nanoTime() + unit.toNanos(initialDelay); |
354 |
tim |
1.21 |
ScheduledCancellableTask t = new ScheduledCancellableTask(command, |
355 |
dl |
1.17 |
triggerTime, |
356 |
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unit.toNanos(period), |
357 |
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true); |
358 |
dl |
1.13 |
delayedExecute(t); |
359 |
dl |
1.4 |
return t; |
360 |
|
|
} |
361 |
|
|
|
362 |
|
|
/** |
363 |
dl |
1.7 |
* Creates a periodic action that becomes enabled first after the |
364 |
|
|
* given date, and subsequently with the given period |
365 |
|
|
* period; that is executions will commence after |
366 |
|
|
* <tt>initialDate</tt> then <tt>initialDate+period</tt>, then |
367 |
|
|
* <tt>initialDate + 2 * period</tt>, and so on. |
368 |
dl |
1.6 |
* @param command the task to execute. |
369 |
|
|
* @param initialDate the time to delay first execution. |
370 |
dl |
1.7 |
* @param period the period between commencement of successive |
371 |
|
|
* executions. |
372 |
dl |
1.6 |
* @param unit the time unit of the period parameter. |
373 |
|
|
* @return a handle that can be used to cancel the task. |
374 |
|
|
* @throws RejectedExecutionException if task cannot be scheduled |
375 |
|
|
* for execution because the executor has been shut down. |
376 |
dl |
1.4 |
*/ |
377 |
tim |
1.21 |
public ScheduledCancellable scheduleAtFixedRate(Runnable command, Date initialDate, long period, TimeUnit unit) { |
378 |
dl |
1.17 |
long triggerTime = System.nanoTime() + |
379 |
|
|
TimeUnit.MILLISECONDS.toNanos(initialDate.getTime() - |
380 |
|
|
System.currentTimeMillis()); |
381 |
tim |
1.21 |
ScheduledCancellableTask t = new ScheduledCancellableTask(command, |
382 |
dl |
1.17 |
triggerTime, |
383 |
|
|
unit.toNanos(period), |
384 |
|
|
true); |
385 |
dl |
1.13 |
delayedExecute(t); |
386 |
dl |
1.7 |
return t; |
387 |
|
|
} |
388 |
|
|
|
389 |
|
|
/** |
390 |
|
|
* Creates and executes a periodic action that becomes enabled first |
391 |
|
|
* after the given initial delay, and and subsequently with the |
392 |
|
|
* given delay between the termination of one execution and the |
393 |
|
|
* commencement of the next. |
394 |
|
|
* @param command the task to execute. |
395 |
|
|
* @param initialDelay the time to delay first execution. |
396 |
|
|
* @param delay the delay between the termination of one |
397 |
|
|
* execution and the commencement of the next. |
398 |
|
|
* @param unit the time unit of the delay and delay parameters |
399 |
|
|
* @return a handle that can be used to cancel the task. |
400 |
|
|
* @throws RejectedExecutionException if task cannot be scheduled |
401 |
|
|
* for execution because the executor has been shut down. |
402 |
|
|
*/ |
403 |
tim |
1.21 |
public ScheduledCancellable scheduleWithFixedDelay(Runnable command, long initialDelay, long delay, TimeUnit unit) { |
404 |
dl |
1.17 |
long triggerTime = System.nanoTime() + unit.toNanos(initialDelay); |
405 |
tim |
1.21 |
ScheduledCancellableTask t = new ScheduledCancellableTask(command, |
406 |
dl |
1.17 |
triggerTime, |
407 |
|
|
unit.toNanos(delay), |
408 |
|
|
false); |
409 |
dl |
1.13 |
delayedExecute(t); |
410 |
dl |
1.7 |
return t; |
411 |
|
|
} |
412 |
|
|
|
413 |
|
|
/** |
414 |
|
|
* Creates a periodic action that becomes enabled first after the |
415 |
|
|
* given date, and subsequently with the given delay between |
416 |
|
|
* the termination of one execution and the commencement of the |
417 |
|
|
* next. |
418 |
|
|
* @param command the task to execute. |
419 |
|
|
* @param initialDate the time to delay first execution. |
420 |
|
|
* @param delay the delay between the termination of one |
421 |
|
|
* execution and the commencement of the next. |
422 |
|
|
* @param unit the time unit of the delay parameter. |
423 |
|
|
* @return a handle that can be used to cancel the task. |
424 |
|
|
* @throws RejectedExecutionException if task cannot be scheduled |
425 |
|
|
* for execution because the executor has been shut down. |
426 |
|
|
*/ |
427 |
tim |
1.21 |
public ScheduledCancellable scheduleWithFixedDelay(Runnable command, Date initialDate, long delay, TimeUnit unit) { |
428 |
dl |
1.17 |
long triggerTime = System.nanoTime() + |
429 |
|
|
TimeUnit.MILLISECONDS.toNanos(initialDate.getTime() - |
430 |
|
|
System.currentTimeMillis()); |
431 |
tim |
1.21 |
ScheduledCancellableTask t = new ScheduledCancellableTask(command, |
432 |
dl |
1.17 |
triggerTime, |
433 |
|
|
unit.toNanos(delay), |
434 |
|
|
false); |
435 |
dl |
1.13 |
delayedExecute(t); |
436 |
dl |
1.4 |
return t; |
437 |
tim |
1.1 |
} |
438 |
|
|
|
439 |
|
|
|
440 |
dl |
1.4 |
/** |
441 |
tim |
1.21 |
* Creates and executes a ScheduledFuture that becomes enabled after the |
442 |
dl |
1.7 |
* given delay. |
443 |
dl |
1.6 |
* @param callable the function to execute. |
444 |
|
|
* @param delay the time from now to delay execution. |
445 |
|
|
* @param unit the time unit of the delay parameter. |
446 |
tim |
1.21 |
* @return a ScheduledFuture that can be used to extract result or cancel. |
447 |
dl |
1.6 |
* @throws RejectedExecutionException if task cannot be scheduled |
448 |
|
|
* for execution because the executor has been shut down. |
449 |
dl |
1.4 |
*/ |
450 |
tim |
1.21 |
public <V> ScheduledFuture<V> schedule(Callable<V> callable, long delay, TimeUnit unit) { |
451 |
dl |
1.17 |
long triggerTime = System.nanoTime() + unit.toNanos(delay); |
452 |
tim |
1.21 |
ScheduledFutureTask<V> t = new ScheduledFutureTask<V>(callable, triggerTime); |
453 |
dl |
1.13 |
delayedExecute(t); |
454 |
dl |
1.4 |
return t; |
455 |
|
|
} |
456 |
|
|
|
457 |
|
|
/** |
458 |
dl |
1.7 |
* Creates and executes a one-shot action that becomes enabled after |
459 |
dl |
1.4 |
* the given date. |
460 |
dl |
1.6 |
* @param callable the function to execute. |
461 |
|
|
* @param date the time to commence excution. |
462 |
tim |
1.21 |
* @return a ScheduledFuture that can be used to extract result or cancel. |
463 |
dl |
1.6 |
* @throws RejectedExecutionException if task cannot be scheduled |
464 |
|
|
* for execution because the executor has been shut down. |
465 |
dl |
1.4 |
*/ |
466 |
tim |
1.21 |
public <V> ScheduledFuture<V> schedule(Callable<V> callable, Date date) { |
467 |
dl |
1.17 |
long triggerTime = System.nanoTime() + |
468 |
|
|
TimeUnit.MILLISECONDS.toNanos(date.getTime() - |
469 |
|
|
System.currentTimeMillis()); |
470 |
tim |
1.21 |
ScheduledFutureTask<V> t = new ScheduledFutureTask<V>(callable, triggerTime); |
471 |
dl |
1.13 |
delayedExecute(t); |
472 |
dl |
1.4 |
return t; |
473 |
tim |
1.1 |
} |
474 |
|
|
|
475 |
dl |
1.4 |
/** |
476 |
dl |
1.16 |
* Execute command with zero required delay. This has effect |
477 |
|
|
* equivalent to <tt>schedule(command, 0, anyUnit)</tt>. Note |
478 |
|
|
* that inspections of the queue and of the list returned by |
479 |
|
|
* <tt>shutdownNow</tt> will access the zero-delayed |
480 |
tim |
1.21 |
* <tt>ScheduledCancellable</tt>, not the <tt>command</tt> itself. |
481 |
tim |
1.11 |
* |
482 |
dl |
1.6 |
* @param command the task to execute |
483 |
|
|
* @throws RejectedExecutionException at discretion of |
484 |
|
|
* <tt>RejectedExecutionHandler</tt>, if task cannot be accepted |
485 |
|
|
* for execution because the executor has been shut down. |
486 |
dl |
1.4 |
*/ |
487 |
|
|
public void execute(Runnable command) { |
488 |
|
|
schedule(command, 0, TimeUnit.NANOSECONDS); |
489 |
tim |
1.1 |
} |
490 |
|
|
|
491 |
dl |
1.18 |
|
492 |
|
|
/** |
493 |
|
|
* Set policy on whether to continue executing existing periodic |
494 |
|
|
* tasks even when this executor has been <tt>shutdown</tt>. In |
495 |
|
|
* this case, these tasks will only terminate upon |
496 |
|
|
* <tt>shutdownNow</tt>, or after setting the policy to |
497 |
|
|
* <tt>false</tt> when already shutdown. This value is by default |
498 |
|
|
* false. |
499 |
|
|
* @param value if true, continue after shutdown, else don't. |
500 |
|
|
*/ |
501 |
|
|
public void setContinueExistingPeriodicTasksAfterShutdownPolicy(boolean value) { |
502 |
|
|
continueExistingPeriodicTasksAfterShutdown = value; |
503 |
|
|
if (!value && isShutdown()) |
504 |
|
|
cancelUnwantedTasks(); |
505 |
|
|
} |
506 |
|
|
|
507 |
|
|
/** |
508 |
|
|
* Get the policy on whether to continue executing existing |
509 |
|
|
* periodic tasks even when this executor has been |
510 |
|
|
* <tt>shutdown</tt>. In this case, these tasks will only |
511 |
|
|
* terminate upon <tt>shutdownNow</tt> or after setting the policy |
512 |
|
|
* to <tt>false</tt> when already shutdown. This value is by |
513 |
|
|
* default false. |
514 |
|
|
* @return true if will continue after shutdown. |
515 |
|
|
*/ |
516 |
|
|
public boolean getContinueExistingPeriodicTasksAfterShutdownPolicy() { |
517 |
|
|
return continueExistingPeriodicTasksAfterShutdown; |
518 |
|
|
} |
519 |
|
|
|
520 |
|
|
/** |
521 |
|
|
* Set policy on whether to execute existing delayed |
522 |
|
|
* tasks even when this executor has been <tt>shutdown</tt>. In |
523 |
|
|
* this case, these tasks will only terminate upon |
524 |
|
|
* <tt>shutdownNow</tt>, or after setting the policy to |
525 |
|
|
* <tt>false</tt> when already shutdown. This value is by default |
526 |
|
|
* true. |
527 |
|
|
* @param value if true, execute after shutdown, else don't. |
528 |
|
|
*/ |
529 |
|
|
public void setExecuteExistingDelayedTasksAfterShutdownPolicy(boolean value) { |
530 |
|
|
executeExistingDelayedTasksAfterShutdown = value; |
531 |
|
|
if (!value && isShutdown()) |
532 |
|
|
cancelUnwantedTasks(); |
533 |
|
|
} |
534 |
|
|
|
535 |
|
|
/** |
536 |
|
|
* Set policy on whether to execute existing delayed |
537 |
|
|
* tasks even when this executor has been <tt>shutdown</tt>. In |
538 |
|
|
* this case, these tasks will only terminate upon |
539 |
|
|
* <tt>shutdownNow</tt>, or after setting the policy to |
540 |
|
|
* <tt>false</tt> when already shutdown. This value is by default |
541 |
|
|
* true. |
542 |
|
|
* @return true if will execute after shutdown. |
543 |
|
|
*/ |
544 |
|
|
public boolean getExecuteExistingDelayedTasksAfterShutdownPolicy() { |
545 |
|
|
return executeExistingDelayedTasksAfterShutdown; |
546 |
|
|
} |
547 |
|
|
|
548 |
|
|
/** |
549 |
|
|
* Cancel and clear the queue of all tasks that should not be run |
550 |
|
|
* due to shutdown policy. |
551 |
|
|
*/ |
552 |
|
|
private void cancelUnwantedTasks() { |
553 |
|
|
boolean keepDelayed = getExecuteExistingDelayedTasksAfterShutdownPolicy(); |
554 |
|
|
boolean keepPeriodic = getContinueExistingPeriodicTasksAfterShutdownPolicy(); |
555 |
|
|
if (!keepDelayed && !keepPeriodic) |
556 |
dl |
1.20 |
super.getQueue().clear(); |
557 |
dl |
1.18 |
else if (keepDelayed || keepPeriodic) { |
558 |
dl |
1.20 |
Object[] entries = super.getQueue().toArray(); |
559 |
dl |
1.18 |
for (int i = 0; i < entries.length; ++i) { |
560 |
tim |
1.21 |
ScheduledCancellableTask t = (ScheduledCancellableTask)entries[i]; |
561 |
dl |
1.18 |
if (t.isPeriodic()? !keepPeriodic : !keepDelayed) |
562 |
|
|
t.cancel(false); |
563 |
|
|
} |
564 |
|
|
entries = null; |
565 |
|
|
purge(); |
566 |
|
|
} |
567 |
|
|
} |
568 |
|
|
|
569 |
|
|
/** |
570 |
|
|
* Initiates an orderly shutdown in which previously submitted |
571 |
|
|
* tasks are executed, but no new tasks will be accepted. If the |
572 |
|
|
* <tt>ExecuteExistingDelayedTasksAfterShutdownPolicy</tt> has |
573 |
|
|
* been set <tt>false</tt>, existing delayed tasks whose delays |
574 |
|
|
* have not yet elapsed are cancelled. And unless the |
575 |
dl |
1.19 |
* <tt>ContinueExistingPeriodicTasksAfterShutdownPolicy</tt> hase |
576 |
dl |
1.18 |
* been set <tt>true</tt>, future executions of existing periodic |
577 |
|
|
* tasks will be cancelled. |
578 |
|
|
*/ |
579 |
|
|
public void shutdown() { |
580 |
|
|
cancelUnwantedTasks(); |
581 |
|
|
super.shutdown(); |
582 |
|
|
} |
583 |
dl |
1.20 |
|
584 |
|
|
/** |
585 |
|
|
* Attempts to stop all actively executing tasks, halts the |
586 |
|
|
* processing of waiting tasks, and returns a list of the tasks that were |
587 |
|
|
* awaiting execution. |
588 |
|
|
* |
589 |
|
|
* <p>There are no guarantees beyond best-effort attempts to stop |
590 |
|
|
* processing actively executing tasks. This implementations |
591 |
|
|
* cancels via {@link Thread#interrupt}, so if any tasks mask or |
592 |
|
|
* fail to respond to interrupts, they may never terminate. |
593 |
|
|
* |
594 |
|
|
* @return list of tasks that never commenced execution. Each |
595 |
tim |
1.21 |
* element of this list is a <tt>ScheduledCancellable</tt>, including those |
596 |
dl |
1.20 |
* tasks submitted using <tt>execute</tt> which are for scheduling |
597 |
tim |
1.21 |
* purposes used as the basis of a zero-delay <tt>ScheduledCancellable</tt>. |
598 |
dl |
1.20 |
*/ |
599 |
|
|
public List shutdownNow() { |
600 |
|
|
return super.shutdownNow(); |
601 |
|
|
} |
602 |
dl |
1.18 |
|
603 |
dl |
1.4 |
/** |
604 |
dl |
1.15 |
* Removes this task from internal queue if it is present, thus |
605 |
|
|
* causing it not to be run if it has not already started. This |
606 |
|
|
* method may be useful as one part of a cancellation scheme. |
607 |
|
|
* |
608 |
|
|
* @param task the task to remove |
609 |
|
|
* @return true if the task was removed |
610 |
|
|
*/ |
611 |
|
|
public boolean remove(Runnable task) { |
612 |
tim |
1.21 |
if (task instanceof ScheduledCancellable && super.getQueue().remove(task)) |
613 |
dl |
1.15 |
return true; |
614 |
|
|
|
615 |
tim |
1.21 |
// The task might actually have been wrapped as a ScheduledCancellable |
616 |
dl |
1.15 |
// in execute(), in which case we need to maually traverse |
617 |
|
|
// looking for it. |
618 |
|
|
|
619 |
tim |
1.21 |
ScheduledCancellable wrap = null; |
620 |
dl |
1.20 |
Object[] entries = super.getQueue().toArray(); |
621 |
dl |
1.15 |
for (int i = 0; i < entries.length; ++i) { |
622 |
tim |
1.21 |
ScheduledCancellableTask t = (ScheduledCancellableTask)entries[i]; |
623 |
dl |
1.15 |
Runnable r = t.getRunnable(); |
624 |
|
|
if (task.equals(r)) { |
625 |
|
|
wrap = t; |
626 |
|
|
break; |
627 |
|
|
} |
628 |
|
|
} |
629 |
|
|
entries = null; |
630 |
dl |
1.20 |
return wrap != null && super.getQueue().remove(wrap); |
631 |
|
|
} |
632 |
|
|
|
633 |
|
|
|
634 |
|
|
/** |
635 |
|
|
* Returns the task queue used by this executor. Each element |
636 |
tim |
1.21 |
* of this queue is a <tt>ScheduledCancellable</tt>, including those |
637 |
dl |
1.20 |
* tasks submitted using <tt>execute</tt> which are for |
638 |
|
|
* scheduling purposes used as the basis of a zero-delay |
639 |
tim |
1.21 |
* <tt>ScheduledCancellable</tt>. |
640 |
dl |
1.20 |
* |
641 |
|
|
* @return the task queue |
642 |
|
|
*/ |
643 |
|
|
public BlockingQueue<Runnable> getQueue() { |
644 |
|
|
return super.getQueue(); |
645 |
dl |
1.15 |
} |
646 |
|
|
|
647 |
|
|
/** |
648 |
dl |
1.4 |
* If executed task was periodic, cause the task for the next |
649 |
|
|
* period to execute. |
650 |
tim |
1.21 |
* @param r the task (assumed to be a ScheduledCancellable) |
651 |
dl |
1.9 |
* @param t the exception |
652 |
dl |
1.4 |
*/ |
653 |
|
|
protected void afterExecute(Runnable r, Throwable t) { |
654 |
|
|
super.afterExecute(r, t); |
655 |
tim |
1.21 |
ScheduledCancellableTask next = ((ScheduledCancellableTask)r).nextTask(); |
656 |
dl |
1.18 |
if (next != null && |
657 |
|
|
(!isShutdown() || |
658 |
|
|
(getContinueExistingPeriodicTasksAfterShutdownPolicy() && |
659 |
|
|
!isTerminating()))) |
660 |
dl |
1.20 |
super.getQueue().offer(next); |
661 |
dl |
1.18 |
|
662 |
|
|
// This might have been the final executed delayed task. Wake |
663 |
|
|
// up threads to check. |
664 |
|
|
else if (isShutdown()) |
665 |
|
|
interruptIdleWorkers(); |
666 |
dl |
1.4 |
} |
667 |
tim |
1.1 |
} |