public void Dispose()
{
lock (SyncObject)
{
if (_disposed)
{
return;
}
_disposed = true;
CreditWaiter waiter = _waitersTail;
if (waiter != null)
{
do
{
CreditWaiter next = waiter.Next;
waiter.Next = null;
waiter.Dispose();
waiter = next;
}while (waiter != _waitersTail);
_waitersTail = null;
}
}
}
public ValueTask <int> RequestCreditAsync(int amount, CancellationToken cancellationToken)
{
lock (SyncObject)
{
if (_disposed)
{
throw new ObjectDisposedException($"{nameof(CreditManager)}:{_owner.GetType().Name}:{_name}");
}
// If we can satisfy the request with credit already available, do so synchronously.
if (_current > 0)
{
Debug.Assert(_waitersTail is null, "Shouldn't have waiters when credit is available");
int granted = Math.Min(amount, _current);
if (NetEventSource.IsEnabled)
{
_owner.Trace($"{_name}. requested={amount}, current={_current}, granted={granted}");
}
_current -= granted;
return(new ValueTask <int>(granted));
}
if (NetEventSource.IsEnabled)
{
_owner.Trace($"{_name}. requested={amount}, no credit available.");
}
// Otherwise, create a new waiter.
CreditWaiter waiter = cancellationToken.CanBeCanceled ?
new CancelableCreditWaiter(SyncObject, cancellationToken) :
new CreditWaiter();
waiter.Amount = amount;
// Add the waiter at the tail of the queue.
if (_waitersTail is null)
{
_waitersTail = waiter.Next = waiter;
}
else
{
waiter.Next = _waitersTail.Next;
_waitersTail.Next = waiter;
_waitersTail = waiter;
}
// And return a ValueTask<int> for it.
return(waiter.AsValueTask());
}
}
public void AdjustCredit(int amount)
{
// Note credit can be adjusted *downward* as well.
// This can cause the current credit to become negative.
lock (SyncObject)
{
if (NetEventSource.IsEnabled)
{
_owner.Trace($"{_name}. {nameof(amount)}={amount}, current={_current}");
}
if (_disposed)
{
return;
}
Debug.Assert(_current <= 0 || _waitersTail is null, "Shouldn't have waiters when credit is available");
_current = checked (_current + amount);
while (_current > 0 && _waitersTail != null)
{
// Get the waiter from the head of the queue.
CreditWaiter waiter = _waitersTail.Next;
int granted = Math.Min(waiter.Amount, _current);
// Remove the waiter from the list.
if (waiter.Next == waiter)
{
Debug.Assert(_waitersTail == waiter);
_waitersTail = null;
}
else
{
_waitersTail.Next = waiter.Next;
}
waiter.Next = null;
// Ensure that we grant credit only if the task has not been canceled.
if (waiter.TrySetResult(granted))
{
_current -= granted;
}
waiter.Dispose();
}
}
}
public ValueTask <int> RequestCreditAsync(int amount, CancellationToken cancellationToken)
{
lock (SyncObject)
{
// If we can satisfy the request with credit already available, do so synchronously.
int granted = TryRequestCreditNoLock(amount);
if (granted > 0)
{
return(new ValueTask <int>(granted));
}
if (NetEventSource.Log.IsEnabled())
{
_owner.Trace($"{_name}. requested={amount}, no credit available.");
}
// Otherwise, create a new waiter.
CreditWaiter waiter = cancellationToken.CanBeCanceled ?
new CancelableCreditWaiter(SyncObject, cancellationToken) :
new CreditWaiter();
waiter.Amount = amount;
// Add the waiter at the tail of the queue.
if (_waitersTail is null)
{
_waitersTail = waiter.Next = waiter;
}
else
{
waiter.Next = _waitersTail.Next;
_waitersTail.Next = waiter;
_waitersTail = waiter;
}
// And return a ValueTask<int> for it.
return(waiter.AsValueTask());
}
}
