commit a73356393315ad3ad7cd9196640823d1a9a620dd
author Glenn Kasten <gkasten@google.com> Thu Jun 09 17:09:53 2016 -0700
committer Glenn Kasten <gkasten@google.com> Mon Jun 20 11:47:01 2016 -0700
tree 8a06b39cd4ea62cd17113f1e03bd279410f3e05b
parent e8a984e43504890e0f676256a0445b9917a2af91

getPrimary APIs now examine all non-duplicating output threads

and return the value corresponding to the thread with minimum frame count,
with a preference for a thread with fast mixer if there are multiple
output threads with the same minimum frame count.
This is in keeping with the expectation by apps that the getPrimary APIs
will return a value for the lowest available latency path.

Bug: 29164107
Change-Id: I8ae9bcad2d48185d7717ccf96085834c0ce00e37

services/audioflinger/AudioFlinger.cpp

diff --git a/services/audioflinger/AudioFlinger.cpp b/services/audioflinger/AudioFlinger.cpp
index 0523d41..3ee9033 100644
--- a/services/audioflinger/AudioFlinger.cpp
+++ b/services/audioflinger/AudioFlinger.cpp
@@ -1694,14 +1694,14 @@
 uint32_t AudioFlinger::getPrimaryOutputSamplingRate()
 {
     Mutex::Autolock _l(mLock);
-    PlaybackThread *thread = primaryPlaybackThread_l();
+    PlaybackThread *thread = fastPlaybackThread_l();
     return thread != NULL ? thread->sampleRate() : 0;
 }
 
 size_t AudioFlinger::getPrimaryOutputFrameCount()
 {
     Mutex::Autolock _l(mLock);
-    PlaybackThread *thread = primaryPlaybackThread_l();
+    PlaybackThread *thread = fastPlaybackThread_l();
     return thread != NULL ? thread->frameCountHAL() : 0;
 }
 
@@ -2528,6 +2528,25 @@
     return thread->outDevice();
 }
 
+AudioFlinger::PlaybackThread *AudioFlinger::fastPlaybackThread_l() const
+{
+    size_t minFrameCount = 0;
+    PlaybackThread *minThread = NULL;
+    for (size_t i = 0; i < mPlaybackThreads.size(); i++) {
+        PlaybackThread *thread = mPlaybackThreads.valueAt(i).get();
+        if (!thread->isDuplicating()) {
+            size_t frameCount = thread->frameCountHAL();
+            if (frameCount != 0 && (minFrameCount == 0 || frameCount < minFrameCount ||
+                    (frameCount == minFrameCount && thread->hasFastMixer() &&
+                    /*minThread != NULL &&*/ !minThread->hasFastMixer()))) {
+                minFrameCount = frameCount;
+                minThread = thread;
+            }
+        }
+    }
+    return minThread;
+}
+
 sp<AudioFlinger::SyncEvent> AudioFlinger::createSyncEvent(AudioSystem::sync_event_t type,
                                     audio_session_t triggerSession,
                                     audio_session_t listenerSession,

services/audioflinger/AudioFlinger.h

diff --git a/services/audioflinger/AudioFlinger.h b/services/audioflinger/AudioFlinger.h
index 4a5a643..c56dcc1 100644
--- a/services/audioflinger/AudioFlinger.h
+++ b/services/audioflinger/AudioFlinger.h
@@ -575,6 +575,9 @@
               PlaybackThread *primaryPlaybackThread_l() const;
               audio_devices_t primaryOutputDevice_l() const;
 
+              // return the playback thread with smallest HAL buffer size, and prefer fast
+              PlaybackThread *fastPlaybackThread_l() const;
+
               sp<PlaybackThread> getEffectThread_l(audio_session_t sessionId, int EffectId);