CGL: Add basic multithreading support

src/libANGLE/renderer/gl/cgl/DisplayCGL.h

@@ -9,6 +9,8 @@
 #ifndef LIBANGLE_RENDERER_GL_CGL_DISPLAYCGL_H_
 #define LIBANGLE_RENDERER_GL_CGL_DISPLAYCGL_H_
 
+#include <thread>
+
 #include "libANGLE/renderer/gl/DisplayGL.h"
 
 struct _CGLContextObject;
@@ -101,6 +103,7 @@ class DisplayCGL : public DisplayGL
 
     egl::Display *mEGLDisplay;
     CGLContextObj mContext;
+    std::unordered_map<std::thread::id, CGLContextObj> mCurrentContexts;
     CGLPixelFormatObj mPixelFormat;
     bool mSupportsGPUSwitching;
     uint64_t mCurrentGPUID;

src/libANGLE/renderer/gl/cgl/DisplayCGL.mm

@@ -184,6 +184,8 @@ egl::Error DisplayCGL::initialize(egl::Display *display)
 
     CGLSetCurrentContext(mContext);
 
+    mCurrentContexts[std::this_thread::get_id()] = mContext;
+
     // There is no equivalent getProcAddress in CGL so we open the dylib directly
     void *handle = dlopen(kDefaultOpenGLDylibName, RTLD_NOW);
     if (!handle)
@@ -219,6 +221,7 @@ void DisplayCGL::terminate()
         CGLDestroyPixelFormat(mPixelFormat);
         mPixelFormat = nullptr;
     }
+    mCurrentContexts.clear();
     if (mContext != nullptr)
     {
         CGLSetCurrentContext(nullptr);
@@ -238,6 +241,18 @@ egl::Error DisplayCGL::makeCurrent(egl::Surface *drawSurface,
                                    gl::Context *context)
 {
     checkDiscreteGPUStatus();
+    // If the thread that's calling makeCurrent does not have the correct
+    // context current (either mContext or 0), we need to set it current.
+    CGLContextObj newContext = 0;
+    if (context)
+    {
+        newContext = mContext;
+    }
+    if (newContext != mCurrentContexts[std::this_thread::get_id()])
+    {
+        CGLSetCurrentContext(newContext);
+        mCurrentContexts[std::this_thread::get_id()] = newContext;
+    }
     return DisplayGL::makeCurrent(drawSurface, readSurface, context);
 }
 

src/tests/gl_tests/MultithreadingTest.cpp

@@ -204,8 +204,8 @@ TEST_P(MultithreadingTest, MultiContextDraw)
 
 TEST_P(MultithreadingTest, MultiCreateContext)
 {
-    // Supported by WGL and GLX (https://anglebug.com/4725)
-    ANGLE_SKIP_TEST_IF(!IsWindows() && !IsLinux());
+    // Supported by CGL, GLX, and WGL (https://anglebug.com/4725)
+    ANGLE_SKIP_TEST_IF(!IsWindows() && !IsLinux() && !IsOSX());
 
     EGLWindow *window  = getEGLWindow();
     EGLDisplay dpy     = window->getDisplay();