we ended-up locking a Mutex that had been destroyed.
This happened because we gave an sp<Source> to the outside world,
and were called after LayerBuffer had been destroyed.
Instead we now give a wp<LayerBuffer> to the outside and have it
do the destruction.
Rewrote SurfaceFlinger's buffer management from the ground-up.
The design now support an arbitrary number of buffers per surface, however the current implementation is limited to four. Currently only 2 buffers are used in practice.
The main new feature is to be able to dequeue all buffers at once (very important when there are only two).
A client can dequeue all buffers until there are none available, it can lock all buffers except the last one that is used for composition. The client will block then, until a new buffer is enqueued.
The current implementation requires that buffers are locked in the same order they are dequeued and enqueued in the same order they are locked. Only one buffer can be locked at a time.
eg. Allowed sequence: DQ, DQ, LOCK, Q, LOCK, Q
eg. Forbidden sequence: DQ, DQ, LOCK, LOCK, Q, Q
doesn't happen because the visibility never changes. With this change
the overlay parameter and position will be committed when either the visibility
of the window changes, or on the first call to visibility resolved, if it
hasn't already been done.
Signed-off-by: Rebecca Schultz Zavin <rebecca@android.com>
Surfaces are now destroyed once all references from the clients are gone, but they go through a partial destruction as soon as the window manager requests it.
This last part is still buggy. see comments in SurfaceFlinger::destroySurface()
