/// <summary>
/// If a latch is currently installed for the given (or any colliding) identifier, then it will be waited upon and
/// {@code null} will be returned.
///
/// Otherwise, if there is currently no latch installed for the given identifier, then one will be created and
/// installed, and that latch will be returned. Once the page fault has been completed, the returned latch must be
/// released. Releasing the latch will unblock all threads that are waiting upon it, and the latch will be
/// atomically uninstalled.
/// </summary>
internal Latch TakeOrAwaitLatch(long identifier)
{
int index = index(identifier);
Latch latch = GetLatch(index);
while (latch == null)
{
latch = new Latch();
if (CompareAndSetLatch(index, null, latch))
{
latch.LatchMap = this;
latch.Index = index;
return(latch);
}
latch = GetLatch(index);
}
latch.Await();
return(null);
}
