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package tests.Concurrency.Condition;
import JACE.ASX.TimeoutException;
import JACE.ASX.TimeValue;
import JACE.Concurrency.*;
public class SimpleMessageQueue
{
private int num_items_ = 0;
private int head_ = 0, tail_ = 0;
private Object[] queue_;
private Mutex lock_ = new Mutex ();
private Condition notFull_ = new Condition (lock_);
private Condition notEmpty_ = new Condition (lock_);
public SimpleMessageQueue(int size)
{
queue_ = new Object[size];
}
public void enqueue(Object element, TimeValue timeout)
throws TimeoutException, InterruptedException
{
try
{
lock_.acquire ();
while (this.isFull ())
notFull_.Wait (timeout);
if (tail_ == queue_.length)
tail_ = 0;
queue_[tail_] = element;
tail_++;
num_items_++;
notEmpty_.signal ();
}
finally
{
lock_.release ();
}
}
public Object dequeue (TimeValue timeout)
throws TimeoutException, InterruptedException
{
Object return_value = null;
try
{
lock_.acquire ();
while (this.isEmpty ())
notEmpty_.Wait (timeout);
return_value = queue_[head_];
head_++;
if (head_ == queue_.length)
head_ = 0;
num_items_--;
notFull_.signal ();
}
finally
{
lock_.release ();
}
return return_value;
}
public boolean isEmpty()
{
return num_items_ == 0;
}
public boolean isFull()
{
return num_items_ == queue_.length;
}
public int size()
{
return num_items_;
}
}
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