Only call gles2::Terminate when all Display objects are deleted

gpu/command_buffer/tests/egl_test.cc

Index: gpu/command_buffer/tests/egl_test.cc
diff --git a/gpu/command_buffer/tests/egl_test.cc b/gpu/command_buffer/tests/egl_test.cc
index bf7e30e5f81610aafbdf6fa9072756a2f277ea3a..ff1e69a17da5f6fea756442f045e3ea1b50381d9 100644
--- a/gpu/command_buffer/tests/egl_test.cc
+++ b/gpu/command_buffer/tests/egl_test.cc
@@ -6,6 +6,7 @@
 #include "testing/gtest/include/gtest/gtest.h"
 
 #include <EGL/egl.h>
+#include <GLES2/gl2.h>
 
 // This file tests EGL basic interface for command_buffer_gles2, the mode of
 // command buffer where the code is compiled as a standalone dynamic library and
@@ -33,4 +34,112 @@ TEST_F(Test, BasicEGLInitialization) {
   ASSERT_TRUE(success);
 }
 
-}  // namespace gpu
+class TestContext {
+  public:
+    TestContext() {

[piman, 2016/02/08 17:36:08]

nit: indent. 'public:' should be at +1, the constructor should be at +2.

[Sami Väisänen, 2016/02/09 10:05:27]

Acknowledged.

+      display_ = eglGetDisplay(EGL_DEFAULT_DISPLAY);
+
+      eglInitialize(display_, nullptr, nullptr);
+
+      static const EGLint configAttribs[] = {
+        EGL_SURFACE_TYPE, EGL_PBUFFER_BIT,
+        EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,
+        EGL_RED_SIZE, 8,
+        EGL_GREEN_SIZE, 8,
+        EGL_BLUE_SIZE, 8,
+        EGL_ALPHA_SIZE, 8,
+        EGL_NONE
+      };
+      EGLint numConfigs;
+      EGLConfig config;
+      eglChooseConfig(display_, configAttribs, &config, 1, &numConfigs);
+
+      static const EGLint surfaceAttribs[] = {
+        EGL_WIDTH, 1,
+        EGL_HEIGHT, 1,
+        EGL_NONE
+      };
+      surface_ = eglCreatePbufferSurface(display_, config, surfaceAttribs);
+
+      static const EGLint contextAttribs[] = {
+        EGL_CONTEXT_CLIENT_VERSION, 2,
+        EGL_NONE
+      };
+      context_ = eglCreateContext(display_, config, nullptr, contextAttribs);
+    }
+
+   ~TestContext() {
+      eglMakeCurrent(display_, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
+      eglDestroyContext(display_, context_);      
+      eglDestroySurface(display_, surface_);
+      eglTerminate(display_);
+    }
+
+    bool IsValid() const 
+    {

[piman, 2016/02/08 17:36:08]

nit: { goes to end of previous line.

[Sami Väisänen, 2016/02/09 10:05:27]

Acknowledged.

+      return display_ != EGL_NO_DISPLAY &&
+        context_ != EGL_NO_CONTEXT &&
+        surface_ != EGL_NO_SURFACE;
+    }
+
+    void TestCallGL() 
+    {

[piman, 2016/02/08 17:36:08]

nit: ditto

[Sami Väisänen, 2016/02/09 10:05:27]

Acknowledged.

+      eglMakeCurrent(display_, surface_, surface_, context_);
+
+      typedef GL_APICALL void GL_APIENTRY (*glEnableProc)(GLenum);
+
+      auto address = eglGetProcAddress("glEnable");
+      auto* glEnable = reinterpret_cast<glEnableProc>(address);
+      glEnable(GL_BLEND);
+

[piman, 2016/02/08 17:36:08]

nit: remove redundant blank line

[Sami Väisänen, 2016/02/09 10:05:27]

Acknowledged.

+    }
+
+  private:
+    TestContext(const TestContext&) = delete;
+    TestContext& operator=(const TestContext&) = delete;
+
+  private:
+    EGLDisplay display_;
+    EGLContext context_;
+    EGLSurface surface_;
+};
+
+// Test case for a workaround for an issue in gles2_conform_support.
+//
+// The problem is that every call to eglGetDisplay(EGL_DEFAULT_DISPLAY) 
+// returns a new display object and the construction of each display 
+// calls to establish a thread local store variable in where to store the 
+// current command buffer context. 
+// Likewise the destructor of display calls to free the same tls variable. 
+// 
+// When skia (nanobench) uses multiple instances of command buffer
+// based contexts and one display is destroyed the TLS variable
+// is also destroyed and subsequent command buffer GL calls using another
+// context instance end up accessing free'ed TLS variable.
+//
+// Note that technically there's also a problem in SkCommandBufferContext
+// since it calls eglTerminate for each display, but this is because 
+// the current command buffer egl implementation requires this. 
+// Overall this functionality is not aligned with the EGL spefication.

[piman, 2016/02/08 17:36:08]

Can we fix that?

[Sami Väisänen, 2016/02/09 10:05:27]

This would require some refactoring in the implementation. Return a handle to
same the same display object for each eglInitialize, and refactor the per
context state from display to some context class (that doesn't seem yet to
exist). And then refactor SkCommandBufferContext appropriately. 

[piman, 2016/02/09 19:23:51]

Right, can we do that?
Otherwise it seems we're doing a workaround for a workaround for a bug. Can we
fix the bug instead and remove workarounds?

+//
+// This testcase tests that we can create multiple command buffer contexts
+// and dispose them without affecting the other.
+TEST(Test, MultipleDisplays) {
+

[piman, 2016/02/08 17:36:08]

nit: no blank line

[Sami Väisänen, 2016/02/09 10:05:27]

Acknowledged.

+  TestContext first;
+  ASSERT_TRUE(first.IsValid());
+
+  first.TestCallGL();
+
+  {
+    TestContext second;
+    ASSERT_TRUE(second.IsValid());
+
+    second.TestCallGL();
+  }
+
+  first.TestCallGL();
+}
+
+} // namespace gpu
+