public class CountDown extends java.lang.Object implements 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 < N; ++i) new Thread(new Worker(done)).start(); doSomethingElse(); done.acquire(); // wait for all to finish } }
Modifier and Type | Field and Description |
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protected int |
count_ |
protected int |
initialCount_ |
ONE_CENTURY, ONE_DAY, ONE_HOUR, ONE_MINUTE, ONE_SECOND, ONE_WEEK, ONE_YEAR
Constructor and Description |
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CountDown(int count)
Create a new CountDown with given count value
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Modifier and Type | Method and Description |
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void |
acquire()
Wait (possibly forever) until successful passage.
|
boolean |
attempt(long msecs)
Wait at most msecs to pass; report whether passed.
|
int |
currentCount()
Return the current count value.
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int |
initialCount()
Return the initial count value
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void |
release()
Decrement the count.
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public CountDown(int count)
public void acquire() throws java.lang.InterruptedException
Sync
public boolean attempt(long msecs) throws java.lang.InterruptedException
Sync
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.
attempt
in interface Sync
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.java.lang.InterruptedException
public void release()
public int initialCount()
public int currentCount()