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/*************************************************
*
* = PACKAGE
* ACE.Concurrency
*
* = FILENAME
* Condition.java
*
*@author Irfan Pyarali
*
*************************************************/
package ACE.Concurrency;
import ACE.ASX.TimeoutException;
import ACE.ASX.TimeValue;
/**
* <hr>
* <h2>TITLE</h2>
*<blockquote>
* Abstraction for <em>traditional</em>
* condition variable
*</blockquote>
*
* <h2>DESCRIPTION</h2>
*<blockquote>
* This condition variable allows the use of one
* mutex between multiple conditions.
* This implementation is based on the C++ version of ACE.
*</blockquote>
*/
public class Condition
{
/**
* Default constructor
*@param Mutex for synchronization
*/
public Condition (Mutex mutex)
{
mutex_ = mutex;
}
/**
* Wait for condition to become signaled.
*@exception InterruptedException exception during wait
*/
public void Wait ()
throws InterruptedException
{
waiters_++;
try
{
mutex_.release();
semaphore_.acquire ();
mutex_.acquire ();
}
finally
{
waiters_--;
}
}
/**
* TimedWait for condition to become signaled.
*@exception TimeoutException wait timed out exception
*@exception InterruptedException exception during wait
*/
public void Wait (TimeValue tv)
throws TimeoutException, InterruptedException
{
waiters_++;
try
{
mutex_.release();
TimeValue start = TimeValue.getTimeOfDay ();
semaphore_.acquire (tv);
TimeValue now = TimeValue.getTimeOfDay ();
tv.minusEquals (TimeValue.minus (now, start));
mutex_.acquire (tv);
}
finally
{
waiters_--;
}
}
/**
* Signal condition. Wake one waiter (if any).
*/
public void signal ()
{
if (waiters_ > 0)
semaphore_.release ();
}
/**
* Signal condition. Wake up all waiters (if any).
*/
public void broadcast ()
{
for (int i = waiters_; i > 0; i--)
semaphore_.release ();
}
/**
* Accessor to lock
*@return Mutex
*/
public Mutex mutex ()
{
return mutex_;
}
private int waiters_;
private Semaphore semaphore_ = new Semaphore (0);
private Mutex mutex_;
}
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