Class CountDown
- All Implemented Interfaces:
Sync
Sample usage. Here are a set of classes in which a group of worker threads use a countdown to notify a driver when all threads are complete.
class Worker implements Runnable {
private final CountDown done;
Worker(CountDown d) { done = d; }
public void run() {
doWork();
done.release();
}
}
class Driver { // ...
void main() {
CountDown done = new CountDown(N);
for (int i = 0; i invalid input: '<' N; ++i)
new Thread(new Worker(done)).start();
doSomethingElse();
done.acquire(); // wait for all to finish
}
}
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Field Summary
FieldsFields inherited from interface EDU.oswego.cs.dl.util.concurrent.Sync
ONE_CENTURY, ONE_DAY, ONE_HOUR, ONE_MINUTE, ONE_SECOND, ONE_WEEK, ONE_YEAR
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Constructor Summary
Constructors -
Method Summary
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Field Details
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initialCount_
protected final int initialCount_ -
count_
protected int count_
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Constructor Details
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CountDown
public CountDown(int count) Create a new CountDown with given count value
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Method Details
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acquire
Description copied from interface:Sync
Wait (possibly forever) until successful passage. Fail only upon interuption. Interruptions always result in `clean' failures. On failure, you can be sure that it has not been acquired, and that no corresponding release should be performed. Conversely, a normal return guarantees that the acquire was successful.- Specified by:
acquire
in interfaceSync
- Throws:
InterruptedException
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attempt
Description copied from interface:Sync
Wait at most msecs to pass; report whether passed.The method has best-effort semantics: The msecs bound cannot be guaranteed to be a precise upper bound on wait time in Java. Implementations generally can only attempt to return as soon as possible after the specified bound. Also, timers in Java do not stop during garbage collection, so timeouts can occur just because a GC intervened. So, msecs arguments should be used in a coarse-grained manner. Further, implementations cannot always guarantee that this method will return at all without blocking indefinitely when used in unintended ways. For example, deadlocks may be encountered when called in an unintended context.
- Specified by:
attempt
in interfaceSync
- Parameters:
msecs
- the number of milleseconds to wait. An argument less than or equal to zero means not to wait at all. However, this may still require access to a synchronization lock, which can impose unbounded delay if there is a lot of contention among threads.- Returns:
- true if acquired
- Throws:
InterruptedException
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release
public void release()Decrement the count. After the initialCount'th release, all current and future acquires will pass -
initialCount
public int initialCount()Return the initial count value -
currentCount
public int currentCount()Return the current count value. This is just a snapshot value, that may change immediately after returning.
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