This CL unblocks future Call-Level Mitigation strategies by moving the
ResourceAdaptationProcessor to a separate task queue. This signifies a
major milestone in the new resource adaptation architecture because
with this CL the threading model is in place and moving the Processor
to the Call and increasing its responsibilities is made possible.
In this CL, we still have one Processor per VideoStreamEncoder and the
VideoStreamEncoder is responsible for the creation and the destruction
of its Processor and that Processor's task queue. But the PostTasks are
in place and the decision-making is executed on a separate queue.
This CL:
- Moves ResourceAdaptationProcessor to an adaptation task queue.
It continues to be entirely single-threaded, but now operates on a
separate task queue.
- Makes Resources thread-safe: Interaction with the Processor, i.e.
OnResourceUsageStateMeasured() and IsAdaptationUpAllowed(), happens
on the adaptation task queue. State updates are pushed from the
encoder task queue with PostTasks.
- QualityScalerResource operates on both task queues; the QP usage
callbacks are invoked asynchronously.
- The VideoStreamEncoderResourceManager operates on the encoder task
queue with the following exceptions:
1) Its resources are accessible on any thread (using a mutex). This
is OK because resources are reference counted and thread safe.
This aids adding and removing resources to the Processor on the
adaptation task queue.
2) |active_counts_| is moved to the adaptation task queue. This makes
it possible for PreventAdaptUpDueToActiveCounts to run
IsAdaptationUpAllowed() on the adaptation task queue.
A side-effect of this is that some stats reporting now happen on
the adaptation task queue, but that is OK because
VideoStreamEncoderObserver is thread-safe.
The Manager is updated to take the new threading model into account:
- OnFrameDroppedDueToSize() posts to the adaptation task queue to
invoke the Processor.
- OnVideoSourceRestrictionsUpdated(), now invoked on the adaptation
task queue, updates |active_counts_| synchronously but posts to the
encoder task queue to update video source restrictions (which it
only uses to calculate target frame rate).
- MaybePerformQualityRampupExperiment() posts to the adaptation task
queue to maybe reset video source restrictions on the Processor.
|quality_rampup_done_| is made std::atomic.
Bug: webrtc:11542, webrtc:11520
Change-Id: I1cfd76e0cd42f006a6d2527f5aa2aeb5266ba6d6
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/174441
Reviewed-by: Evan Shrubsole <eshr@google.com>
Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org>
Commit-Queue: Henrik Boström <hbos@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#31231}
381d10963a