Audio Effect Management



EffectModule and EffectChain classes both have their own mutex to protect state changes or resource modifications. Always respect the following order if multiple mutexes must be acquired to avoid cross deadlock:

AudioFlinger -> ThreadBase -> EffectChain -> EffectModule

In addition, methods that lock the AudioPolicyService mutex (getOutputForEffect(),

startOutput()...) should never be called with AudioFlinger or Threadbase mutex locked

to avoid cross deadlock with other clients calling AudioPolicyService methods that in turn

call AudioFlinger thus locking the same mutexes in the reverse order.