From bef0a4c1e20fe660b7ad40bb0f47d7bd721c3b6f Mon Sep 17 00:00:00 2001
From: Randell Jesup <rjesup@jesup.org>
Date: Thu, 18 Oct 2012 14:03:00 -0400
Subject: [PATCH] Bug 803093: Lock access to MediaEngineWebRTC singleton
 r=anant

---
 content/media/webrtc/MediaEngineWebRTC.cpp |  7 +++++++
 content/media/webrtc/MediaEngineWebRTC.h   | 10 ++++++++--
 dom/media/MediaManager.cpp                 |  4 ++++
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/content/media/webrtc/MediaEngineWebRTC.cpp b/content/media/webrtc/MediaEngineWebRTC.cpp
index 7b63b443f13d..fe7695b36284 100644
--- a/content/media/webrtc/MediaEngineWebRTC.cpp
+++ b/content/media/webrtc/MediaEngineWebRTC.cpp
@@ -29,6 +29,8 @@ MediaEngineWebRTC::EnumerateVideoDevices(nsTArray<nsRefPtr<MediaEngineVideoSourc
 {
   webrtc::ViEBase* ptrViEBase;
   webrtc::ViECapture* ptrViECapture;
+  // We spawn threads to handle gUM runnables, so we must protect the member vars
+  MutexAutoLock lock(mMutex);
 
   if (!mVideoEngine) {
     if (!(mVideoEngine = webrtc::VideoEngine::Create())) {
@@ -123,6 +125,8 @@ MediaEngineWebRTC::EnumerateAudioDevices(nsTArray<nsRefPtr<MediaEngineAudioSourc
 {
   webrtc::VoEBase* ptrVoEBase = NULL;
   webrtc::VoEHardware* ptrVoEHw = NULL;
+  // We spawn threads to handle gUM runnables, so we must protect the member vars
+  MutexAutoLock lock(mMutex);
 
   if (!mVoiceEngine) {
     mVoiceEngine = webrtc::VoiceEngine::Create();
@@ -181,6 +185,9 @@ MediaEngineWebRTC::EnumerateAudioDevices(nsTArray<nsRefPtr<MediaEngineAudioSourc
 void
 MediaEngineWebRTC::Shutdown()
 {
+  // This is likely paranoia
+  MutexAutoLock lock(mMutex);
+
   if (mVideoEngine) {
     mVideoSources.Clear();
     webrtc::VideoEngine::Delete(mVideoEngine);
diff --git a/content/media/webrtc/MediaEngineWebRTC.h b/content/media/webrtc/MediaEngineWebRTC.h
index 45e7c326d529..4f9e75b18dc0 100644
--- a/content/media/webrtc/MediaEngineWebRTC.h
+++ b/content/media/webrtc/MediaEngineWebRTC.h
@@ -11,6 +11,7 @@
 #include "nsIThread.h"
 #include "nsIRunnable.h"
 
+#include "mozilla/Mutex.h"
 #include "nsCOMPtr.h"
 #include "nsDOMFile.h"
 #include "nsThreadUtils.h"
@@ -218,10 +219,12 @@ class MediaEngineWebRTC : public MediaEngine
 {
 public:
   MediaEngineWebRTC()
-  : mVideoEngine(NULL)
+  : mMutex("mozilla::MediaEngineWebRTC")
+  , mVideoEngine(NULL)
   , mVoiceEngine(NULL)
   , mVideoEngineInit(false)
-  , mAudioEngineInit(false) {
+  , mAudioEngineInit(false)
+  {
     mVideoSources.Init();
     mAudioSources.Init();
   }
@@ -235,6 +238,9 @@ public:
   virtual void EnumerateAudioDevices(nsTArray<nsRefPtr<MediaEngineAudioSource> >*);
 
 private:
+  Mutex mMutex;
+  // protected with mMutex:
+
   webrtc::VideoEngine* mVideoEngine;
   webrtc::VoiceEngine* mVoiceEngine;
 
diff --git a/dom/media/MediaManager.cpp b/dom/media/MediaManager.cpp
index b3eed3e6a513..7dd4a351241e 100644
--- a/dom/media/MediaManager.cpp
+++ b/dom/media/MediaManager.cpp
@@ -812,6 +812,7 @@ MediaManager::GetUserMedia(bool aPrivileged, nsPIDOMWindow* aWindow,
     if (!mMediaThread) {
       nsresult rv = NS_NewThread(getter_AddRefs(mMediaThread));
       NS_ENSURE_SUCCESS(rv, rv);
+      LOG(("New Media thread for gum"));
     }
     mMediaThread->Dispatch(gUMRunnable, NS_DISPATCH_NORMAL);
   } else {
@@ -952,8 +953,11 @@ MediaManager::Observe(nsISupports* aSubject, const char* aTopic,
 
     // Reuse the same thread to save memory.
     if (!mMediaThread) {
+      LOG(("New Media thread for gum on allow"));
       nsresult rv = NS_NewThread(getter_AddRefs(mMediaThread));
       NS_ENSURE_SUCCESS(rv, rv);
+    } else {
+      LOG(("Reused Media thread for gum on allow"));
     }
 
     if (aSubject) {