Bug 1482150 - Make CubebDeviceEnumerator singleton. r=padenot

Differential Revision: https://phabricator.services.mozilla.com/D7604

--HG--
extra : moz-landing-system : lando

dom/media/CubebUtils.cpp

@@ -6,6 +6,9 @@
 
 #include "CubebUtils.h"
 
+#ifdef MOZ_WEBRTC
+#include "CubebDeviceEnumerator.h"
+#endif
 #include "MediaInfo.h"
 #include "mozilla/AbstractThread.h"
 #include "mozilla/dom/ContentChild.h"
@@ -607,6 +610,11 @@ void ShutdownLibrary()
   Preferences::UnregisterCallbacks(PrefChanged, gInitCallbackPrefs);
   Preferences::UnregisterCallbacks(PrefChanged, gCallbackPrefs);
 
+#ifdef MOZ_WEBRTC
+  // This must be done before cubeb destroy.
+  CubebDeviceEnumerator::Shutdown();
+#endif
+
   StaticMutexAutoLock lock(sMutex);
   if (sCubebContext) {
     cubeb_destroy(sCubebContext);

dom/media/gtest/TestAudioDeviceEnumerator.cpp

@@ -4,7 +4,6 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #define ENABLE_SET_CUBEB_BACKEND 1
-#include "AudioDeviceInfo.h"
 #include "CubebDeviceEnumerator.h"
 #include "gtest/gtest.h"
 #include "mozilla/UniquePtr.h"
@@ -478,11 +477,11 @@ TestEnumeration(MockCubeb* aMock,
                 uint32_t aExpectedDeviceCount,
                 DeviceOperation aOperation)
 {
-  CubebDeviceEnumerator enumerator;
+  RefPtr<CubebDeviceEnumerator> enumerator = CubebDeviceEnumerator::GetInstance();
 
   nsTArray<RefPtr<AudioDeviceInfo>> inputDevices;
 
-  enumerator.EnumerateAudioInputDevices(inputDevices);
+  enumerator->EnumerateAudioInputDevices(inputDevices);
 
   EXPECT_EQ(inputDevices.Length(), aExpectedDeviceCount)
     << "Device count is correct when enumerating";
@@ -500,7 +499,7 @@ TestEnumeration(MockCubeb* aMock,
     aMock->AddDevice(InputDeviceTemplate(reinterpret_cast<cubeb_devid>(123)));
   }
 
-  enumerator.EnumerateAudioInputDevices(inputDevices);
+  enumerator->EnumerateAudioInputDevices(inputDevices);
 
   uint32_t newExpectedDeviceCount = aOperation == DeviceOperation::REMOVE
                                       ? aExpectedDeviceCount - 1
@@ -555,6 +554,7 @@ TEST(CubebDeviceEnumerator, EnumerateSimple)
       TestEnumeration(mock, device_count, op);
     }
   }
+  CubebDeviceEnumerator::Shutdown();
 }
 #else // building for Android, which has no device enumeration support
 TEST(CubebDeviceEnumerator, EnumerateAndroid)
@@ -562,23 +562,27 @@ TEST(CubebDeviceEnumerator, EnumerateAndroid)
   MockCubeb* mock = new MockCubeb();
   mozilla::CubebUtils::ForceSetCubebContext(mock->AsCubebContext());
 
-  CubebDeviceEnumerator enumerator;
+  RefPtr<CubebDeviceEnumerator> enumerator = CubebDeviceEnumerator::GetInstance();
 
   nsTArray<RefPtr<AudioDeviceInfo>> inputDevices;
-  enumerator.EnumerateAudioInputDevices(inputDevices);
+  enumerator->EnumerateAudioInputDevices(inputDevices);
   EXPECT_EQ(inputDevices.Length(), 1u) <<  "Android always exposes a single input device.";
   EXPECT_EQ(inputDevices[0]->MaxChannels(), 1u) << "With a single channel.";
   EXPECT_EQ(inputDevices[0]->DeviceID(), nullptr) << "It's always the default device.";
   EXPECT_TRUE(inputDevices[0]->Preferred()) << "it's always the prefered device.";
+  CubebDeviceEnumerator::Shutdown();
 }
 #endif
 
 TEST(CubebDeviceEnumerator, ForceNullCubebContext)
 {
   mozilla::CubebUtils::ForceSetCubebContext(nullptr);
-  CubebDeviceEnumerator enumerator;
+  RefPtr<CubebDeviceEnumerator> enumerator = CubebDeviceEnumerator::GetInstance();
   nsTArray<RefPtr<AudioDeviceInfo>> inputDevices;
-  enumerator.EnumerateAudioInputDevices(inputDevices);
+  enumerator->EnumerateAudioInputDevices(inputDevices);
   EXPECT_EQ(inputDevices.Length(), 0u) << "Enumeration must fail device list must be empty.";
+
+  enumerator->Shutdown();
+  CubebDeviceEnumerator::Shutdown();
 }
 

dom/media/webrtc/CubebDeviceEnumerator.cpp

@@ -1,10 +1,22 @@
 #include "CubebDeviceEnumerator.h"
-#include "nsTArray.h"
+#include "mozilla/StaticPtr.h"
 
 namespace mozilla {
 
 using namespace CubebUtils;
 
+/* static */ StaticRefPtr<CubebDeviceEnumerator> CubebDeviceEnumerator::sInstance;
+
+/* static */ already_AddRefed<CubebDeviceEnumerator>
+CubebDeviceEnumerator::GetInstance()
+{
+  if (!sInstance) {
+    sInstance = new CubebDeviceEnumerator();
+  }
+  RefPtr<CubebDeviceEnumerator> instance = sInstance.get();
+  return instance.forget();
+}
+
 CubebDeviceEnumerator::CubebDeviceEnumerator()
   : mMutex("CubebDeviceListMutex")
   , mManualInvalidation(false)
@@ -21,6 +33,14 @@ CubebDeviceEnumerator::CubebDeviceEnumerator()
   }
 }
 
+/* static */ void
+CubebDeviceEnumerator::Shutdown()
+{
+  if (sInstance) {
+    sInstance = nullptr;
+  }
+}
+
 CubebDeviceEnumerator::~CubebDeviceEnumerator()
 {
   int rv = cubeb_register_device_collection_changed(GetCubebContext(),

dom/media/webrtc/CubebDeviceEnumerator.h

@@ -17,8 +17,10 @@ namespace mozilla {
 class CubebDeviceEnumerator final
 {
 public:
-  CubebDeviceEnumerator();
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(CubebDeviceEnumerator)
-  ~CubebDeviceEnumerator();
+
+  static already_AddRefed<CubebDeviceEnumerator> GetInstance();
+  static void Shutdown();
   // This method returns a list of all the input and output audio devices
   // available on this machine.
   // This method is safe to call from all threads.
@@ -30,6 +32,8 @@ public:
   DeviceInfoFromID(CubebUtils::AudioDeviceID aID);
 
 private:
+  CubebDeviceEnumerator();
+  ~CubebDeviceEnumerator();
   // Static function called by cubeb when the audio input device list changes
   // (i.e. when a new device is made available, or non-available). This
   // re-binds to the MediaEngineWebRTC that instantiated this
@@ -45,6 +49,8 @@ private:
   // list each time instead of relying on automatic invalidation of the cache by
   // cubeb itself. Set in the constructor and then can be access on any thread.
   bool mManualInvalidation;
+
+  static StaticRefPtr<CubebDeviceEnumerator> sInstance;
 };
 
 }

dom/media/webrtc/MediaEngineWebRTC.cpp

@@ -185,9 +185,7 @@ MediaEngineWebRTC::EnumerateMicrophoneDevices(uint64_t aWindowId,
 {
   mMutex.AssertCurrentThreadOwns();
 
-  if (!mEnumerator) {
+  mEnumerator = CubebDeviceEnumerator::GetInstance();
-    mEnumerator.reset(new CubebDeviceEnumerator());
-  }
 
   nsTArray<RefPtr<AudioDeviceInfo>> devices;
   mEnumerator->EnumerateAudioInputDevices(devices);

dom/media/webrtc/MediaEngineWebRTC.h

@@ -79,7 +79,7 @@ private:
 
   // gUM runnables can e.g. Enumerate from multiple threads
   Mutex mMutex;
-  UniquePtr<mozilla::CubebDeviceEnumerator> mEnumerator;
+  RefPtr<mozilla::CubebDeviceEnumerator> mEnumerator;
   const bool mDelayAgnostic;
   const bool mExtendedFilter;
   // This also is set in the ctor and then never changed, but we can't make it