[EGD-4003] audio: fix workers destroying (#806)

Improve workers destroying by replacing sudden death with a gentle close
request.

Make (De)Init static - when creating second instance of a codec there
was a situation when destructing one instance was causing first one to
stop working, because they share common hardware resources.

Author: mpsm

changelog.md

@@ -13,6 +13,10 @@
 * `[audio]` Fix headphones autodetection.
 * `[audio]` Cumulative set of minor fixes and improvements
 
+### Other
+
+* `[audio]` Improve synchronization when switching operations.
+
 ## [0.42.2 2020-10-16]
 
 ### Added

module-audio/Audio/Audio.cpp

@@ -117,6 +117,7 @@ namespace audio
 
     audio::RetCode Audio::Start()
     {
+        currentOperation->Stop();
         return Start(currentOperation->GetOperationType(),
                      currentOperation->GetToken(),
                      currentOperation->GetFilePath().c_str(),

module-audio/Audio/Operation/PlaybackOperation.cpp

@@ -22,7 +22,6 @@ namespace audio
         std::function<uint32_t(const std::string &path, const uint32_t &defaultValue)> dbCallback)
         : Operation(false, playbackType), dec(nullptr)
     {
-
         audioCallback = [this](const void *inputBuffer, void *outputBuffer, unsigned long framesPerBuffer) -> int32_t {
 
 #if PERF_STATS_ON == 1
@@ -73,7 +72,6 @@ namespace audio
 
     audio::RetCode PlaybackOperation::Start(audio::AsyncCallback callback, audio::Token token)
     {
-
         if (state == State::Active || state == State::Paused) {
             return RetCode::InvokedInIncorrectState;
         }
@@ -98,9 +96,6 @@ namespace audio
 
     audio::RetCode PlaybackOperation::Stop()
     {
-        if (state == State::Idle) {
-            return RetCode::InvokedInIncorrectState;
-        }
         state = State::Idle;
         return GetDeviceError(audioDevice->Stop());
     }
@@ -122,7 +117,7 @@ namespace audio
         if (state == State::Active || state == State::Idle) {
             return RetCode::InvokedInIncorrectState;
         }
-        state = State::Active;
+        state    = State::Active;
         auto ret = audioDevice->Start(currentProfile->GetAudioFormat());
         return GetDeviceError(ret);
     }
@@ -196,4 +191,9 @@ namespace audio
         return audio::RetCode::Success;
     }
 
+    PlaybackOperation::~PlaybackOperation()
+    {
+        Stop();
+    }
+
 } // namespace audio

module-audio/Audio/Operation/PlaybackOperation.hpp

@@ -23,6 +23,8 @@ namespace audio
             const audio::PlaybackType &playbackType,
             std::function<uint32_t(const std::string &path, const uint32_t &defaultValue)> dbCallback = nullptr);
 
+        virtual ~PlaybackOperation();
+
         audio::RetCode Start(audio::AsyncCallback callback, audio::Token token) override final;
 
         audio::RetCode Stop() override final;