/// <summary>
/// If visual is on channel, its reference count is increased.
/// Otherwise, a new resource is created on that channel.
/// </summary>
internal bool ReleaseOnChannel(DUCE.Channel channel)
{
int index = Find(channel);
bool proxyRemoved = false;
int count = Count;
if (index == PROXY_STORED_INLINE)
{
if (channel.ReleaseOnChannel(_head.Handle))
{
//
// Need to move the last of the non-empty tail to head
// or clear the head. Erase the head if that was the last
// proxy.
//
if (count == 1)
{
_head = new Proxy();
}
else
{
_head = _tail[count - 2];
}
proxyRemoved = true;
}
}
else if (index >= 0)
{
if (channel.ReleaseOnChannel(_tail[index].Handle))
{
//
// Need to move the last of the non-empty tail to the
// removed index. Avoid in-place copying.
//
if (index != count - 2)
{
_tail[index] = _tail[count - 2];
}
proxyRemoved = true;
}
}
else
{
Debug.Assert(index != PROXY_NOT_FOUND);
return(false);
}
if (proxyRemoved)
{
if (_tail != null)
{
//
// Keep the tail short. We allow for one extra free element
// in tail to avoid constant allocations / reallocations.
//
if (count == 2)
{
// ------------------
// Before removal: [head] [tail c-1] [empty]
// Here and now: [head] [ deleted] [empty]
// After removal: [head]
//
_tail = null;
}
else if (count == _tail.Length)
{
// ---------------------------------------------------
// Before removal: [head] [tail 0] [tail 1] ... [tail c-3] [tail c-2] [empty]
// Here and now: [head] [tail 0] [tail 1] ... [tail c-3] [ deleted] [empty]
// After removal: [head] [tail 0] [tail 1] ... [tail c-3]
//
ResizeTail(-2);
}
else
{
// ------------------------------------------------------
// Before removal: [head] [tail 0] [tail 1] ... [tail c-4] [tail c-3] [tail c-2]
// Here and now: [head] [tail 0] [tail 1] ... [tail c-4] [tail c-3] [ deleted]
// After removal: [head] [tail 0] [tail 1] ... [tail c-4] [tail c-3] [ empty]
//
_tail[count - 2] = new Proxy();
}
}
}
return(proxyRemoved);
}
