commit b31f96ffee12f920d32d868c627cf34f1afeb988
author Kevin Rocard <krocard@google.com> Tue Apr 03 09:00:09 2018 -0700
committer Kevin Rocard <krocard@google.com> Fri Apr 06 22:18:34 2018 +0000
tree e3e8744cefcf0785addf9ceb1519fceac3020293
parent dab059e964ea373d8e18a063e80d7d421e27925f

Audio V4: Do not send metadata of Output Track

Output track currently do not support audio attributes,
nevertheless the placeholders values were erroneously
propagated to the HAL.

Bug: 38184704
Bug: 69623109
Test: check that the HAL does not receive metadata about duplicated
      tracks.
Change-Id: I9a646faf4a43b1ebc09c03329827aee4a49674f9
Signed-off-by: Kevin Rocard <krocard@google.com>

services/audioflinger/Threads.cpp

diff --git a/services/audioflinger/Threads.cpp b/services/audioflinger/Threads.cpp
index b5b50f8..160aa45 100644
--- a/services/audioflinger/Threads.cpp
+++ b/services/audioflinger/Threads.cpp
@@ -2631,6 +2631,10 @@
     StreamOutHalInterface::SourceMetadata metadata;
     for (const sp<Track> &track : mActiveTracks) {
         // No track is invalid as this is called after prepareTrack_l in the same critical section
+        if (track->isOutputTrack()) {
+            // TODO: OutputTrack (used for duplication) are currently not supported
+            continue;
+        }
         metadata.tracks.push_back({
                 .usage = track->attributes().usage,
                 .content_type = track->attributes().content_type,
@@ -6151,13 +6155,12 @@
 
 void AudioFlinger::DuplicatingThread::updateMetadata_l()
 {
-    // TODO: The duplicated track metadata are stored in other threads
-    // (accessible through mActiveTracks::OutputTrack::thread()::mActiveTracks::Track::attributes())
-    // but this information can be mutated at any time by the owning threads.
-    // Taking the lock of any other owning threads is no possible due to timing constrains.
-    // Similarly, the other threads can not push the metadatas in this thread as cross deadlock
-    // would be possible.
-    // A lock-free structure needs to be used to shared the metadata (maybe an atomic shared_ptr ?).
+    // TODO: The duplicated track metadata needs to be pushed to downstream
+    // but this information can be read at any time by the downstream threads.
+    // Taking the lock of any downstream threads is no possible due to cross deadlock risks
+    // (eg: during effect move).
+    // A lock-free structure needs to be used to shared the metadata, probably an atomic
+    // pointer to a metadata vector in each output tracks.
 }
 
 uint32_t AudioFlinger::DuplicatingThread::activeSleepTimeUs() const