private ReferenceCountedDisposable(T instance, BoxedReferenceCount referenceCount)
{
_instance = instance ?? throw new ArgumentNullException(nameof(instance));
// The reference count has already been incremented for this instance
_boxedReferenceCount = referenceCount;
}
/// <summary>
/// Provides the implementation for <see cref="TryAddReference"/> and
/// <see cref="WeakReference.TryAddReference"/>.
/// </summary>
private static ReferenceCountedDisposable <T>?TryAddReferenceImpl(T?target, BoxedReferenceCount referenceCount)
{
lock (referenceCount)
{
if (referenceCount._referenceCount == 0)
{
// The target is already disposed, and cannot be reused
return(null);
}
if (target == null)
{
// The current reference has been disposed, so even though it isn't disposed yet we don't have a
// reference to the target
return(null);
}
checked
{
referenceCount._referenceCount++;
}
// Must return a new instance, in order for the Dispose operation on each individual instance to
// be idempotent.
return(new ReferenceCountedDisposable <T>(target, referenceCount));
}
}