gpu: Mailbox emulation with EGLImage

ui/gl/gl_fence.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/gl/gl_fence.h"
 
 #include "base/compiler_specific.h"
 #include "ui/gl/gl_bindings.h"
 #include "ui/gl/gl_context.h"
 
 namespace {
 
 class GLFenceNVFence: public gfx::GLFence {
  public:
-  GLFenceNVFence() {
+  GLFenceNVFence(bool flush) {
     // What if either of these GL calls fails? TestFenceNV will return true.
     // See spec:
     // http://www.opengl.org/registry/specs/NV/fence.txt
     //
     // What should happen if TestFenceNV is called for a name before SetFenceNV
     // is called?
     //     We generate an INVALID_OPERATION error, and return TRUE.
     //     This follows the semantics for texture object names before
     //     they are bound, in that they acquire their state upon binding.
     //     We will arbitrarily return TRUE for consistency.
     glGenFencesNV(1, &fence_);
     glSetFenceNV(fence_, GL_ALL_COMPLETED_NV);
-    glFlush();
+    if (flush)
+      glFlush();
   }
 
   virtual bool HasCompleted() OVERRIDE {
     return !!glTestFenceNV(fence_);
   }
 
   virtual void ClientWait() OVERRIDE {
     glFinishFenceNV(fence_);
   }
 
+  virtual void ServerWait() OVERRIDE {
+    glFinishFenceNV(fence_);
+  }
+
  private:
   virtual ~GLFenceNVFence() {
     glDeleteFencesNV(1, &fence_);
   }
 
   GLuint fence_;
 };
 
 class GLFenceARBSync: public gfx::GLFence {
  public:
-  GLFenceARBSync() {
+  GLFenceARBSync(bool flush) {
     sync_ = glFenceSync(GL_SYNC_GPU_COMMANDS_COMPLETE, 0);
-    glFlush();
+    if (flush)
+      glFlush();
   }
 
   virtual bool HasCompleted() OVERRIDE {
     // Handle the case where FenceSync failed.
     if (!sync_)
       return true;
 
     // We could potentially use glGetSynciv here, but it doesn't work
     // on OSX 10.7 (always says the fence is not signaled yet).
     // glClientWaitSync works better, so let's use that instead.
     return  glClientWaitSync(sync_, 0, 0) != GL_TIMEOUT_EXPIRED;
   }
 
   virtual void ClientWait() OVERRIDE {
     glClientWaitSync(sync_, GL_SYNC_FLUSH_COMMANDS_BIT, GL_TIMEOUT_IGNORED);
   }
 
+  virtual void ServerWait() OVERRIDE {
+    glWaitSync(sync_, 0, GL_TIMEOUT_IGNORED);
+  }
+
  private:
   virtual ~GLFenceARBSync() {
     glDeleteSync(sync_);
   }
 
   GLsync sync_;
 };
 
 #if !defined(OS_MACOSX)
 class EGLFenceSync : public gfx::GLFence {
  public:
-  EGLFenceSync() {
+  EGLFenceSync(bool flush) {
     display_ = eglGetCurrentDisplay();
     sync_ = eglCreateSyncKHR(display_, EGL_SYNC_FENCE_KHR, NULL);
-    glFlush();
+    if (flush)
+      glFlush();
   }
 
   virtual bool HasCompleted() OVERRIDE {
     EGLint value = 0;
     eglGetSyncAttribKHR(display_, sync_, EGL_SYNC_STATUS_KHR, &value);
     DCHECK(value == EGL_SIGNALED_KHR || value == EGL_UNSIGNALED_KHR);
     return !value || value == EGL_SIGNALED_KHR;
   }
 
   virtual void ClientWait() OVERRIDE {
     EGLint flags = 0;
     EGLTimeKHR time = EGL_FOREVER_KHR;
     eglClientWaitSyncKHR(display_, sync_, flags, time);
   }
 
+  virtual void ServerWait() OVERRIDE {
+    EGLint flags = 0;
+    eglWaitSyncKHR(display_, sync_, flags);
+  }
+
+
  private:
   virtual ~EGLFenceSync() {
     eglDestroySyncKHR(display_, sync_);
   }
 
   EGLSyncKHR sync_;
   EGLDisplay display_;
 };
 #endif // !OS_MACOSX
 
+// static
+gfx::GLFence* CreateFence(bool flush) {
+#if !defined(OS_MACOSX)
+  if (gfx::g_driver_egl.ext.b_EGL_KHR_fence_sync)
+    return new EGLFenceSync(flush);
+#endif
+  if (gfx::g_driver_gl.ext.b_GL_NV_fence)
+    return new GLFenceNVFence(flush);
+  if (gfx::g_driver_gl.ext.b_GL_ARB_sync)
+    return new GLFenceARBSync(flush);

[piman, 2014/03/13 04:41:58]

Because the NV_fence implementation degrades to a client wait for the server
wait, we should prefer the ARB_sync version.

[no sievers, 2014/03/13 20:50:15]

Done in https://codereview.chromium.org/195763015

+  return NULL;
+}
+
 }  // namespace
 
 namespace gfx {
 
 GLFence::GLFence() {
 }
 
 GLFence::~GLFence() {
 }
 
-// static
 GLFence* GLFence::Create() {
-#if !defined(OS_MACOSX)
-  if (gfx::g_driver_egl.ext.b_EGL_KHR_fence_sync)
-    return new EGLFenceSync();
-#endif
-  if (gfx::g_driver_gl.ext.b_GL_NV_fence)
-    return new GLFenceNVFence();
-  if (gfx::g_driver_gl.ext.b_GL_ARB_sync)
-    return new GLFenceARBSync();
-  return NULL;
+  return CreateFence(true);
+}
+
+GLFence* GLFence::CreateWithoutFlush() {
+  return CreateFence(false);
 }
 
 }  // namespace gfx