fix: mutex fun: ensure a: stretcher for oboe_cb MusicProvider::onAudioReady, b: musicFile for musicFeedThread

app/src/main/cpp/PlaybackEngine.cpp

@@ -157,6 +157,13 @@ void PlaybackEngine::initRubberBand() {
 }
 
 void PlaybackEngine::closeRubberBand() {
+    if (mPlayer) {
+        LOGI("PlaybackEngine: mPlayer->stopAudio() ...");
+        mPlayer->stopAudio();
+        LOGI("PlaybackEngine: mPlayer->stopAudio() done.");
+        delete mPlayer;
+        mPlayer = nullptr;
+    }
     if(musicFeed) {
         exitMusicFeedThread.store(true);
         LOGI("PlaybackEngine: musicFeed->join() ...");
@@ -164,7 +171,6 @@ void PlaybackEngine::closeRubberBand() {
         LOGI("PlaybackEngine: musicFeed->join() done.");
         musicFeed = nullptr;
     }
-    closeMusicFile();
 }
 
 void PlaybackEngine::closeMusicFile() {
@@ -209,6 +215,7 @@ void PlaybackEngine::musicFeedThread() {
     std::mt19937 mt(42);
     std::uniform_real_distribution<double> dist(0.98, 1.0);
 */
+    bool isOnTrackFinished = false;
     LOGI("starting musicFeedThread()");
 
     // strecher num channels: same as output num channels
@@ -243,6 +250,11 @@ void PlaybackEngine::musicFeedThread() {
     // thread 2: polling for decoding more mp3 -> process()  -- getSamplesRequired()
     while(!exitMusicFeedThread.load()) {
 
+        if(isOnTrackFinished) {
+            if(listener) listener->onTrackFinished();
+            isOnTrackFinished = false;
+        }
+
         if(!haveMusicFile.load()) {
             // while no MusicProvider is connected, no samples will be read from 'stretcher'
             // therefore, we do not write any samples into it!
@@ -325,6 +337,11 @@ void PlaybackEngine::musicFeedThread() {
             continue;
         }
 
+        size_t num_decoded_samples;
+        {
+            std::lock_guard<std::mutex> lock(mMusicLock);
+            if(!haveMusicFile.load()) continue;
+
             if(idebug++ < 10) {
                 pr = std::max(1L, musicFile->rate);
                 loop_delay_us = std::min((size_t) 50000, (size_t) 1000000 * num_samples / pr);
@@ -399,6 +416,8 @@ void PlaybackEngine::musicFeedThread() {
                 stretcher.setPitchScale(1.0);
                 stretcher.process(buf_ptr, 0, true); // set end of playback
                 mPlayer->stopAudio();
+                // TODO: raise error
+                //if(listener) listener->onError(1, "mpg123_read() error");
                 continue;
             }
             if(err == MPG123_DONE) {
@@ -407,11 +426,12 @@ void PlaybackEngine::musicFeedThread() {
                 LOGI("finished reading mp3 file (MPG123_DONE)");
                 idebug = 0;
                 closeMusicFile();
-            if(listener) listener->onTrackFinished();
+                //if(listener) listener->onTrackFinished();
+                isOnTrackFinished = true;
                 continue;
             }
 
-        size_t num_decoded_samples = done / sizeof(int16_t) / num_ch_in;
+            num_decoded_samples = done / sizeof(int16_t) / num_ch_in;
             //LOGD("num_decoded_samples = %d", num_decoded_samples);
 
             // * convert interleaved int16 to de-interleaved float [-1.0, 1.0] format
@@ -421,11 +441,17 @@ void PlaybackEngine::musicFeedThread() {
                     buf[i + buf_stride * j] = static_cast<float>(*(reinterpret_cast<int16_t*>(cbuf) + i * num_ch_in + channel_map[j])) / 32768.0f;
                 }
             }
+        }
 
         //LOGD("calling stretcher.process()");
         stretcher.process(buf_ptr, num_decoded_samples, false);
     }
 
+    if(isOnTrackFinished) {
+        if(listener) listener->onTrackFinished();
+        //isOnTrackFinished = false;
+    }
+
     LOGI("musicFeedThread() exiting ...");
 
     free(buf);
@@ -462,12 +488,9 @@ void PlaybackEngine::seekTo(double markerPosSec) {
 void PlaybackEngine::stop() {
     LOGI("PlaybackEngine::stop()");
     closeRubberBand();
-    if (mPlayer) {
-        LOGI("PlaybackEngine: mPlayer->stopAudio() ...");
-        mPlayer->stopAudio();
-        LOGI("PlaybackEngine: mPlayer->stopAudio() done.");
-        delete mPlayer;
-        mPlayer = nullptr;
+    {
+        std::lock_guard<std::mutex> lock(mMusicLock);
+        closeMusicFile();
     }
     markerPos.store(0.0);
     duration.store(0.0);
@@ -476,10 +499,9 @@ void PlaybackEngine::stop() {
 PlaybackEngine::~PlaybackEngine() {
     LOGI("~PlaybackEngine()");
     closeRubberBand();
-    if (mPlayer) {
-        mPlayer->stopAudio();
-        delete mPlayer;
-        mPlayer = nullptr;
+    {
+        std::lock_guard<std::mutex> lock(mMusicLock);
+        closeMusicFile();
     }
 }
 
@@ -490,25 +512,33 @@ void PlaybackEngine::playBeat() {
 void PlaybackEngine::playMusic(int fd, long long offset, long long length) {
     if(!mPlayer) return;
     LOGI("PlaybackEngine::playMusic(fd=%d)", fd);
-    if(musicFile) {
+
+    {
+        std::lock_guard<std::mutex> lock(mMusicLock);
+
+        if (musicFile) {
+            if (fd == android_fd)
+                android_fd = 0; // HACK: avoid closing the 'fd' if re-opening the same file
             // when changing tracks in the UI, close the previous file
             closeMusicFile();
         }
         android_fd = fd;
-    if(fd != 0)
+        if (fd != 0)
             musicFile.reset(mp3file_open_fd(android_fd, offset, length, 0));
-    if(musicFile) {
+        if (musicFile) {
             timeRatio.store(((double) playbackRate.load()) / ((double) musicFile->rate));
             haveTimeRatio.store(true);
             numInChannels.store(musicFile->channels);
             haveMusicFile.store(true);
         }
+    }
 
     bool is_finished = (stretcher.available() == -1);
     if(is_finished) {
         LOGE("stretcher.available() == -1, this should not happen anymore with current wiring");
         // so that we may play again after "final chunk"
         closeRubberBand();
+        // do not closeMusicFile() here, it would close the very file we want to be playing
         initRubberBand();
     }
 

app/src/main/cpp/PlaybackEngine.h

@@ -62,6 +62,7 @@ private:
     RubberBand::RubberBandStretcher stretcher;
     MixingPlayer *mPlayer;
     std::string mFilesDir;
+    std::mutex mMusicLock;
     std::unique_ptr<MP3File> musicFile;
     std::atomic<bool> haveMusicFile;
     std::unique_ptr<std::thread> musicFeed;