Issue 5247986: Battery drain due to audio wakelock

The problem occurs when activating or deactivating A2DP connection
while SoudPool has a channel active. This can happen quite frequently now
that the UI sound effects are enabled by default.
If PCM data is remaining in the AudioTrack buffer when it is restroyed and
re-created on the new AudioFlinger output thread, this data is flushed.
As a consequence, no underrun or request for new data callback is sent to
SoundPool and the sound channel remains active for ever as the end of the
sample is never detected.

Change-Id: I13e0c11e4ce3f83bff7f58d347ca814b6a86712b

1 files changed, 21 insertions, 4 deletions

diff --git a/media/libmedia/AudioTrack.cpp b/media/libmedia/AudioTrack.cpp
index 3b6c64d..7509239 100644
--- a/media/libmedia/AudioTrack.cpp
+++ b/media/libmedia/AudioTrack.cpp
@@ -1182,16 +1182,33 @@ status_t AudioTrack::restoreTrack_l(audio_track_cblk_t*& cblk, bool fromStart)
                                false);
 
         if (result == NO_ERROR) {
+            uint32_t user = cblk->user;
+            uint32_t server = cblk->server;
             // restore write index and set other indexes to reflect empty buffer status
-            mCblk->user = cblk->user;
-            mCblk->server = cblk->user;
-            mCblk->userBase = cblk->user;
-            mCblk->serverBase = cblk->user;
+            mCblk->user = user;
+            mCblk->server = user;
+            mCblk->userBase = user;
+            mCblk->serverBase = user;
             // restore loop: this is not guaranteed to succeed if new frame count is not
             // compatible with loop length
             setLoop_l(cblk->loopStart, cblk->loopEnd, cblk->loopCount);
             if (!fromStart) {
                 mCblk->bufferTimeoutMs = MAX_RUN_TIMEOUT_MS;
+                // Make sure that a client relying on callback events indicating underrun or
+                // the actual amount of audio frames played (e.g SoundPool) receives them.
+                if (mSharedBuffer == 0) {
+                    uint32_t frames = 0;
+                    if (user > server) {
+                        frames = ((user - server) > mCblk->frameCount) ?
+                                mCblk->frameCount : (user - server);
+                        memset(mCblk->buffers, 0, frames * mCblk->frameSize);
+                    }
+                    // restart playback even if buffer is not completely filled.
+                    android_atomic_or(CBLK_FORCEREADY_ON, &mCblk->flags);
+                    // stepUser() clears CBLK_UNDERRUN_ON flag enabling underrun callbacks to
+                    // the client
+                    mCblk->stepUser(frames);
+                }
             }
             if (mActive) {
                 result = mAudioTrack->start();