CoreAudio: Prevent racing between calls to start and stop a device

modules/juce_audio_devices/native/juce_CoreAudio_mac.cpp

@@ -1039,7 +1039,7 @@ class CoreAudioInternal final : private Timer,
 
  CoreAudioIODevice& owner;
  int bitDepth = 32;
- int xruns = 0;
+ std::atomic<int> xruns = 0;
  Array<double> sampleRates;
  Array<int> bufferSizes;
  AudioDeviceID deviceID;
@@ -1147,7 +1147,7 @@ class CoreAudioInternal final : private Timer,
  return x.mSelector == kAudioDeviceProcessorOverload;
  });
 
- intern.xruns += xruns;
+ intern.xruns += (int) xruns;
 
  const auto detailsChanged = std::any_of (pa, pa + numAddresses, [] (const AudioObjectPropertyAddress& x)
  {
@@ -1313,19 +1313,23 @@ class CoreAudioIODevice final : public AudioIODevice,
 
  void start (AudioIODeviceCallback* callback) override
  {
+ const ScopedLock sl (startStopLock);
+
  if (internal->start (callback))
  pendingCallback = nullptr;
  }
 
  void stop() override
  {
  stopAndGetLastCallback();
+
+ const ScopedLock sl (startStopLock);
  pendingCallback = nullptr;
  }
 
  void stopWithPendingCallback()
  {
- const ScopedLock sl (closeLock);
+ const ScopedLock sl (startStopLock);
 
  if (pendingCallback == nullptr)
  pendingCallback = stopAndGetLastCallback();
@@ -1387,7 +1391,7 @@ class CoreAudioIODevice final : public AudioIODevice,
  AudioIODeviceCallback* pendingCallback = nullptr;
  AsyncRestarter* restarter = nullptr;
  BigInteger inputChannelsRequested, outputChannelsRequested;
- CriticalSection closeLock;
+ CriticalSection startStopLock;
 
  AudioIODeviceCallback* stopAndGetLastCallback() const
  {
@@ -1412,6 +1416,7 @@ class CoreAudioIODevice final : public AudioIODevice,
  getCurrentSampleRate(),
  getCurrentBufferSizeSamples());
 
+ const ScopedLock sl { startStopLock };
  start (pendingCallback);
  }