Bug 723793 - Lazily initialize libcubeb on first use. r=roc

content/media/nsAudioStream.cpp

@@ -83,10 +83,6 @@ using mozilla::TimeStamp;
 PRLogModuleInfo* gAudioStreamLog = nsnull;
 #endif
 
-#if defined(MOZ_CUBEB)
-static cubeb* gCubebContext;
-#endif
-
 static const PRUint32 FAKE_BUFFER_SIZE = 176400;
 
 // Number of milliseconds per second.
@@ -363,6 +359,19 @@ static bool GetUseCubeb()
   mozilla::MutexAutoLock lock(*gAudioPrefsLock);
   return gUseCubeb;
 }
+
+static cubeb* gCubebContext;
+
+static cubeb* GetCubebContext()
+{
+  mozilla::MutexAutoLock lock(*gAudioPrefsLock);
+  if (gCubebContext ||
+      cubeb_init(&gCubebContext, "nsAudioStream") == CUBEB_OK) {
+    return gCubebContext;
+  }
+  NS_WARNING("cubeb_init failed");
+  return nsnull;
+}
 #endif
 
 void nsAudioStream::InitLibrary()
@@ -376,9 +385,6 @@ void nsAudioStream::InitLibrary()
 #if defined(MOZ_CUBEB)
   PrefChanged(PREF_USE_CUBEB, nsnull);
   Preferences::RegisterCallback(PrefChanged, PREF_USE_CUBEB);
-  if (cubeb_init(&gCubebContext, "nsAudioStream") != 0) {
-    NS_WARNING("cubeb_init failed");
-  }
 #endif
 }
 
@@ -932,7 +938,9 @@ NS_IMPL_THREADSAFE_ISUPPORTS0(nsBufferedAudioStream)
 nsresult
 nsBufferedAudioStream::Init(PRInt32 aNumChannels, PRInt32 aRate, SampleFormat aFormat)
 {
-  if (!gCubebContext || aNumChannels < 0 || aRate < 0) {
+  cubeb* cubebContext = GetCubebContext();
+
+  if (!cubebContext || aNumChannels < 0 || aRate < 0) {
     return NS_ERROR_FAILURE;
   }
 
@@ -958,7 +966,7 @@ nsBufferedAudioStream::Init(PRInt32 aNumChannels, PRInt32 aRate, SampleFormat aF
 
   {
     cubeb_stream* stream;
-    if (cubeb_stream_init(gCubebContext, &stream, "nsBufferedAudioStream", params,
+    if (cubeb_stream_init(cubebContext, &stream, "nsBufferedAudioStream", params,
                           DEFAULT_LATENCY_MS, DataCallback_S, StateCallback_S, this) == CUBEB_OK) {
       mCubebStream.own(stream);
     }