Merge "AudioFlinger: remove false underruns if we retry for data"

    mMixerBufferValid = false;  // mMixerBuffer has no valid data until appropriate tracks found.

    mEffectBufferValid = false; // mEffectBuffer has no valid data until tracks found.

    // DeferredOperations handles statistics after setting mixerStatus.

    class DeferredOperations {

    public:

        DeferredOperations(mixer_state *mixerStatus)

            : mMixerStatus(mixerStatus) { }

        // when leaving scope, tally frames properly.

        ~DeferredOperations() {

            // Tally underrun frames only if we are actually mixing (MIXER_TRACKS_READY)

            // because that is when the underrun occurs.

            // We do not distinguish between FastTracks and NormalTracks here.

            if (*mMixerStatus == MIXER_TRACKS_READY) {

                for (const auto &underrun : mUnderrunFrames) {

                    underrun.first->mAudioTrackServerProxy->tallyUnderrunFrames(

                            underrun.second);

                }

            }

        }

        // tallyUnderrunFrames() is called to update the track counters

        // with the number of underrun frames for a particular mixer period.

        // We defer tallying until we know the final mixer status.

        void tallyUnderrunFrames(sp<Track> track, size_t underrunFrames) {

            mUnderrunFrames.emplace_back(track, underrunFrames);

        }

    private:

        const mixer_state * const mMixerStatus;

        std::vector<std::pair<sp<Track>, size_t>> mUnderrunFrames;

    } deferredOperations(&mixerStatus); // implicit nested scope for variable capture

    for (size_t i=0 ; i<count ; i++) {

        const sp<Track> t = mActiveTracks[i];

            track->mObservedUnderruns = underruns;

            // don't count underruns that occur while stopping or pausing

            // or stopped which can occur when flush() is called while active

            size_t underrunFrames = 0;

            if (!(track->isStopping() || track->isPausing() || track->isStopped()) &&

                    recentUnderruns > 0) {

                // FIXME fast mixer will pull & mix partial buffers, but we count as a full underrun

                track->mAudioTrackServerProxy->tallyUnderrunFrames(recentUnderruns * mFrameCount);

            } else {

                track->mAudioTrackServerProxy->tallyUnderrunFrames(0);

                underrunFrames = recentUnderruns * mFrameCount;

            }

            // Immediately account for FastTrack underruns.

            track->mAudioTrackServerProxy->tallyUnderrunFrames(underrunFrames);

            // This is similar to the state machine for normal tracks,

            // with a few modifications for fast tracks.

                mixerStatus = MIXER_TRACKS_READY;

            }

        } else {

            size_t underrunFrames = 0;

            if (framesReady < desiredFrames && !track->isStopped() && !track->isPaused()) {

                ALOGV("track(%p) underrun,  framesReady(%zu) < framesDesired(%zd)",

                        track, framesReady, desiredFrames);

                track->mAudioTrackServerProxy->tallyUnderrunFrames(desiredFrames);

            } else {

                track->mAudioTrackServerProxy->tallyUnderrunFrames(0);

                underrunFrames = desiredFrames;

            }

            deferredOperations.tallyUnderrunFrames(track, underrunFrames);

            // clear effect chain input buffer if an active track underruns to avoid sending

            // previous audio buffer again to effects