//****************************************
private static AsyncHandleWaiter CreateWaiter(WaitHandle waitObject, TimeSpan timeout, CancellationToken token = default)
{
if (waitObject == null)
{
throw new ArgumentNullException(nameof(waitObject));
}
if (timeout == TimeSpan.Zero)
{
throw new ArgumentOutOfRangeException(nameof(timeout), "Timeout must be infinite, or positive");
}
// We want to guarantee that only one AsyncHandle is associated per WaitHandle.
// This AsyncHandle will persist for the life of the WaitHandle, until it is disposed
var Handle = _AsyncHandles.GetValue(waitObject, AsyncHandle.Create);
// GetValue may call GetOrCreate multiple times, so we only register the handle once we have the final result
Handle.Register();
// To allow each async wait to be cancellable, we need to track them independently
var Waiter = AsyncHandleWaiter.GetOrCreate(Handle);
Waiter.ApplyCancellation(timeout, token);
return(Waiter);
}
//****************************************
internal static AsyncHandleWaiter GetOrCreate(AsyncHandle handle)
{
if (!Instances.TryTake(out var Instance))
{
Instance = new AsyncHandleWaiter();
}
Instance.Initialise(handle);
return(Instance);
}
internal bool Detach(AsyncHandleWaiter waiter) => _Waiters.Erase(waiter);
internal void Attach(AsyncHandleWaiter waiter) => _Waiters.Enqueue(waiter);
