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// package NexusII.util ;
// Subclass the Exception class to get TimeoutException
class TimeoutException extends Exception
{
public TimeoutException()
{
super();
}
public TimeoutException(String s)
{
super(s);
}
}
// Timed_wait class. This can used by enq and deq to do timed_waits
public abstract class Timed_Wait
{
// By default the object is itself
public Timed_Wait ()
{
object_ = this;
}
// If the calling class specifies objects, delegate to it.
public Timed_Wait (Object obj)
{
object_ = obj;
}
// This is the object we delegate to if a
// subclass gives us a particular object,
// otherwise, we ``delegate'' to ourself
// (i.e., to this).
protected Object object_;
// This hook method must be overridden
// by a subclass to provide the condition.
public abstract boolean condition ();
// This will borrow the monitor lock from the calling class
public final void timed_wait(long msec_timeout)
throws InterruptedException, TimeoutException
{
// wait if the condition is false
if (!condition())
{
long start = System.currentTimeMillis() ;
long wait_time = msec_timeout ;
for(;;)
{
// anyway have to wait atleast till waittime
object_.wait(wait_time);
// on coming out check for the condition again
if(!condition())
{
long now = System.currentTimeMillis() ;
long time_so_far = now - start ;
// if timed out
if(time_so_far >= msec_timeout)
throw new TimeoutException() ;
else
// retry !! we have some time left
wait_time = msec_timeout - time_so_far ;
}
else // the condition is true here
break ;
}
}
}
// Notify all threads waiting on the object_.
public final void broadcast ()
{
object_.notifyAll ();
}
}
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