/**
* Auxiliary methods
*/
/**
* Returns the list of all pending async acquires that can be satisfied with
* the current number of permits owned by the semaphore.
*
* Note: Tis method is called when the current thread owns the lock.
*/
private List <AsyncAcquire> SatisfyPendingAsyncAcquires()
{
List <AsyncAcquire> satisfied = null;
while (asyncAcquires.Count > 0)
{
AsyncAcquire acquire = asyncAcquires.First.Value;
// Check if available permits allow satisfy this request
if (acquire.acquires > permits)
{
break;
}
// Remove the request from the queue
asyncAcquires.RemoveFirst();
// Try lock the request and complete it if succeeded
if (acquire.TryLock())
{
permits -= acquire.acquires;
if (satisfied == null)
{
satisfied = new List <AsyncAcquire>(1);
}
satisfied.Add(acquire);
}
}
return(satisfied);
}
/**
* Try to cancel an async acquire request
*/
private void AcquireCancellationHandler(object _acquireNode, bool canceling)
{
LinkedListNode <AsyncAcquire> acquireNode = (LinkedListNode <AsyncAcquire>)_acquireNode;
AsyncAcquire acquire = acquireNode.Value;
if (acquire.TryLock())
{
List <AsyncAcquire> satisfied = null;
// To access shared mutable state we must acquire the lock
lock (theLock)
{
if (acquireNode.List != null)
{
asyncAcquires.Remove(acquireNode);
}
if (asyncAcquires.Count > 0 && permits >= asyncAcquires.First.Value.acquires)
{
satisfied = SatisfyPendingAsyncAcquires();
}
}
// Complete the satisfied async acquires
CompleteSatisfiedAsyncAcquires(satisfied);
// Release the resources associated with the async acquire.
acquire.Dispose(canceling);
// Complete the TaskCompletionSource to RanToCompletion (timeout)
// or Canceled final state.
if (canceling)
{
acquire.SetCanceled();
}
else
{
acquire.SetResult(false);
}
}
}