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/* |
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* 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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*/ |
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|
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package java.util.concurrent; |
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|
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/** |
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* Something, usually a task, that can be cancelled. Cancellation is |
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* performed by the <tt>cancel</tt> method. Additional methods are |
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* provided to determine if the task completed normally or was |
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* cancelled. |
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* |
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* @see FutureTask |
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* @see Executor |
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* @since 1.5 |
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* @author Doug Lea |
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*/ |
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public interface Cancellable { |
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|
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/** |
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* Attempts to cancel execution of this task. This attempt will |
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* fail if the task has already completed, already been cancelled, |
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* or could not be cancelled for some other reason. If successful, |
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* and this task has not started when <tt>cancel</tt> is called, |
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* this task should never run. If the task has already started, |
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* then the <tt>interruptIfRunning</tt> parameter determines |
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* whether the thread executing this task should be interrupted in |
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* an attempt to stop the task. |
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* |
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* @param mayInterruptIfRunning <tt>true</tt> if the thread executing this |
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* task should be interrupted; otherwise, in-progress tasks are allowed |
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* to complete |
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* @return <tt>false</tt> if the task could not be cancelled, |
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* typically because is has already completed normally; |
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* <tt>true</tt> otherwise |
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*/ |
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boolean cancel(boolean mayInterruptIfRunning); |
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|
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/** |
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* Returns <tt>true</tt> if this task was cancelled before it completed |
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* normally. |
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* |
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* @return <tt>true</tt> if task was cancelled before it completed |
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*/ |
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boolean isCancelled(); |
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|
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/** |
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* Returns <tt>true</tt> if this task completed. |
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* |
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* Completion may be due to normal termination, an exception, or |
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* cancellation -- in all of these cases, this method will return |
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* <tt>true</tt>. |
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* |
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* @return <tt>true</tt> if this task completed. |
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*/ |
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boolean isDone(); |
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} |
