DeviceBase* DeviceHandle::CreateDevice()
{
if (!pImpl)
return 0;
DeviceBase* device = 0;
Ptr<DeviceManagerImpl> manager= 0;
// Since both manager and device pointers can only be destroyed during a lock,
// hold it while checking for availability.
// AddRef to manager so that it doesn't get released on us.
{
Lock::Locker deviceLockScope(pImpl->GetLock());
if (pImpl->pDevice)
{
pImpl->pDevice->AddRef();
return device;
}
manager = pImpl->GetManagerImpl();
}
if (manager)
{
// Queue up a CreateDevice request. This fills in '&device' with AddRefed value,
// or keep it at null.
manager->GetThreadQueue()->PushCallAndWaitResult(
manager.GetPtr(), &DeviceManagerImpl::CreateDevice_MgrThread,
&device, pImpl, (DeviceBase*)0);
}
return device;
}
void DeviceCreateDesc::Release()
{
while(1)
{
UInt32 handleCount = HandleCount;
// HandleCount must obviously be >= 1, since we are releasing it.
OVR_ASSERT(handleCount > 0);
// {1 -> 0} transition may cause us to be destroyed, so require a lock.
if (handleCount == 1)
{
Ptr<DeviceManagerLock> lockKeepAlive;
Lock::Locker deviceLockScope(GetLock());
if (!HandleCount.CompareAndSet_NoSync(handleCount, 0))
continue;
OVR_ASSERT(pDevice == 0);
// Destroy *this if the manager was destroyed already, or Enumerated
// is false (device no longer available).
if (!GetManagerImpl() || !Enumerated)
{
lockKeepAlive = pLock;
// Remove from manager list (only matters for !Enumerated).
if (pNext)
{
RemoveNode();
pNext = pPrev = 0;
}
delete this;
}
// Available DeviceCreateDesc may survive with { HandleCount == 0 },
// in case it might be enumerated again later.
break;
}
else if (HandleCount.CompareAndSet_NoSync(handleCount, handleCount-1))
{
break;
}
}
}