a38e1f4ed9
Backgroud: As noted in b/20823981, MediaSessionService calls some
audio service methods while holding a lock and the audio service
methods also talk to other system services. And, deadlock happens when
the other system service fires another request to MediaSessionService
while holding its lock.
Example1) --- resolved by the change in MediaSessionRecord.java
T1: MediaSessionService.dispatchAdjustVolumeLocked()
-> MediaSessionRecord.adjustVolume()
-> +++AudioServiceInternal.adjustSuggestedStreamVolumeForUid()+++
-> AudioService.adjustSuggestedStreamVolume()
-> telecom.TelecomManager.isInCall() --- blocked by lock in TelecomManager.
T2: telecom.ConnectionServiceWrapper.handleCreateConnectionComplete()
-> MediaSession.setActive()
-> MediaSessionRecord$SessionStub.setActive()
-> MediaSessionService.updateSession() --- blocked by lock in MediaSessionService.
Example2) --- resolved by the change in IAudioService.aidl
T1: MediaSessionService.dispatchAdjustVolumeLocked()
-> IAudioService.adjustSuggestedStreamVolume()
-> AudioService.adjustSuggestedStreamVolume()
-> telecom.TelecomManager.isInCall() --- blocked by lock in TelecomManager.
T2: telecom.ConnectionServiceWrapper.handleCreateConnectionComplete()
-> MediaSession.setActive()
-> MediaSessionRecord$SessionStub.setActive()
-> MediaSessionService.updateSession() --- blocked by lock in MediaSessionService.
Here, this change prevents the deadlock by making related audio IPC oneway
and calling the internal audio method without holding the lock.
Bug: 20823981
Change-Id: I4c4b2fc796f23d83be67f7edaacd7496c145d985