bool Add(AsyncSubjectDisposable inner)
{
for (; ;)
{
var a = Volatile.Read(ref _observers);
if (a == DISPOSED)
{
_value = default(T);
_exception = null;
ThrowDisposed();
return(true);
}
if (a == TERMINATED)
{
return(false);
}
var n = a.Length;
var b = new AsyncSubjectDisposable[n + 1];
Array.Copy(a, 0, b, 0, n);
b[n] = inner;
if (Interlocked.CompareExchange(ref _observers, b, a) == a)
{
return(true);
}
}
}
/// <summary>
/// Subscribes an observer to the subject.
/// </summary>
/// <param name="observer">Observer to subscribe to the subject.</param>
/// <returns>Disposable object that can be used to unsubscribe the observer from the subject.</returns>
/// <exception cref="ArgumentNullException"><paramref name="observer"/> is <c>null</c>.</exception>
public override IDisposable Subscribe(IObserver <T> observer)
{
if (observer == null)
{
throw new ArgumentNullException(nameof(observer));
}
var parent = new AsyncSubjectDisposable(this, observer);
if (!Add(parent))
{
var ex = _exception;
if (ex != null)
{
observer.OnError(ex);
}
else
{
if (_hasValue)
{
observer.OnNext(_value);
}
observer.OnCompleted();
}
return(Disposable.Empty);
}
return(parent);
}
void Remove(AsyncSubjectDisposable inner)
{
for (; ;)
{
var a = Volatile.Read(ref _observers);
var n = a.Length;
if (n == 0)
{
break;
}
var j = -1;
for (var i = 0; i < n; i++)
{
if (a[i] == inner)
{
j = i;
break;
}
}
if (j < 0)
{
break;
}
var b = default(AsyncSubjectDisposable[]);
if (n == 1)
{
b = EMPTY;
}
else
{
b = new AsyncSubjectDisposable[n - 1];
Array.Copy(a, 0, b, 0, j);
Array.Copy(a, j + 1, b, j, n - j - 1);
}
if (Interlocked.CompareExchange(ref _observers, b, a) == a)
{
break;
}
}
}