Bug 730079 - Move sCurrentGLContext to TLS to support off main thread GLDebug. r=joe

gfx/gl/GLContext.cpp

@@ -60,8 +60,7 @@ namespace mozilla {
 namespace gl {
 
 #ifdef DEBUG
-// see comment near declaration in GLContext.h. Should be thread-local.
-GLContext* GLContext::sCurrentGLContext = nsnull;
+PRUintn GLContext::sCurrentGLContextTLS = -1;
 #endif
 
 PRUint32 GLContext::sDebugMode = 0;

gfx/gl/GLContext.h

@@ -602,9 +602,15 @@ public:
 
     virtual bool MakeCurrentImpl(bool aForce = false) = 0;
 
+#ifdef DEBUG
+    static void StaticInit() {
+        PR_NewThreadPrivateIndex(&sCurrentGLContextTLS, NULL);
+    }
+#endif
+
     bool MakeCurrent(bool aForce = false) {
 #ifdef DEBUG
-        sCurrentGLContext = this;
+        PR_SetThreadPrivate(sCurrentGLContextTLS, this);
 #endif
         return MakeCurrentImpl(aForce);
     }
@@ -1505,10 +1511,12 @@ protected:
     GLContextSymbols mSymbols;
 
 #ifdef DEBUG
-    // this should be thread-local, but that is slightly annoying to implement because on Mac
-    // we don't have any __thread-like keyword. So for now, MOZ_GL_DEBUG assumes (and asserts)
-    // that only the main thread is doing OpenGL calls.
-    static THEBES_API GLContext* sCurrentGLContext;
+    // GLDebugMode will check that we don't send call
+    // to a GLContext that isn't current on the current
+    // thread.
+    // Store the current context when binding to thread local
+    // storage to support DebugMode on an arbitrary thread.
+    static PRUintn sCurrentGLContextTLS;
 #endif
 
     void UpdateActualFormat();
@@ -1632,21 +1640,16 @@ public:
 
     void BeforeGLCall(const char* glFunction) {
         if (DebugMode()) {
-            // since the static member variable sCurrentGLContext is not thread-local as it should,
-            // we have to assert that we're in the main thread. Note that sCurrentGLContext is only used
-            // for the OpenGL debug mode.
-            if (!NS_IsMainThread()) {
-                NS_ERROR("OpenGL call from non-main thread. While this is fine in itself, "
-                         "the OpenGL debug mode, which is currently enabled, doesn't support this. "
-                         "It needs to be patched by making GLContext::sCurrentGLContext be thread-local.\n");
-                NS_ABORT();
-            }
+            GLContext *currentGLContext = NULL;
+
+            currentGLContext = (GLContext*)PR_GetThreadPrivate(sCurrentGLContextTLS);
+
             if (DebugMode() & DebugTrace)
                 printf_stderr("[gl:%p] > %s\n", this, glFunction);
-            if (this != sCurrentGLContext) {
+            if (this != currentGLContext) {
                 printf_stderr("Fatal: %s called on non-current context %p. "
                               "The current context for this thread is %p.\n",
-                               glFunction, this, sCurrentGLContext);
+                               glFunction, this, currentGLContext);
                 NS_ABORT();
             }
         }

gfx/gl/GLContextProviderEGL.cpp

@@ -267,15 +267,6 @@ is_power_of_two(int v)
 static void BeforeGLCall(const char* glFunction)
 {
     if (GLContext::DebugMode()) {
-        // since the static member variable sCurrentGLContext is not thread-local as it should,
-        // we have to assert that we're in the main thread. Note that sCurrentGLContext is only used
-        // for the OpenGL debug mode.
-        if (!NS_IsMainThread()) {
-            NS_ERROR("OpenGL call from non-main thread. While this is fine in itself, "
-                     "the OpenGL debug mode, which is currently enabled, doesn't support this. "
-                     "It needs to be patched by making GLContext::sCurrentGLContext be thread-local.\n");
-            NS_ABORT();
-        }
         if (GLContext::DebugMode() & GLContext::DebugTrace)
             printf_stderr("[egl] > %s\n", glFunction);
     }

gfx/thebes/gfxPlatform.cpp

@@ -298,6 +298,10 @@ gfxPlatform::Init()
     #error "No gfxPlatform implementation available"
 #endif
 
+#ifdef DEBUG
+    mozilla::gl::GLContext::StaticInit();
+#endif
+
     nsresult rv;
 
 #if defined(XP_MACOSX) || defined(XP_WIN) || defined(ANDROID) // temporary, until this is implemented on others