Revert r258965 aka reland r258122

gpu: Allow fences to check whether a flush has occurred

This skips waiting on a fence that was created but never committed.

BUG=352419,355275
TBR=piman@chromium.org

> Original Review URL: https://codereview.chromium.org/197563003

Review URL: https://codereview.chromium.org/222103008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@261383 0039d316-1c4b-4281-b951-d872f2087c98

6 files changed, 139 insertions, 14 deletions

diff --git a/ui/gl/gl_context.cc b/ui/gl/gl_context.cc
index baa20fa..533b7d3 100644
--- a/ui/gl/gl_context.cc
+++ b/ui/gl/gl_context.cc
@@ -38,6 +38,20 @@ void GLContext::ScopedReleaseCurrent::Cancel() {
   canceled_ = true;
 }
 
+GLContext::FlushEvent::FlushEvent() {
+}
+
+GLContext::FlushEvent::~FlushEvent() {
+}
+
+void GLContext::FlushEvent::Signal() {
+  flag_.Set();
+}
+
+bool GLContext::FlushEvent::IsSignaled() {
+  return flag_.IsSet();
+}
+
 GLContext::GLContext(GLShareGroup* share_group) : share_group_(share_group) {
   if (!share_group_.get())
     share_group_ = new GLShareGroup;
@@ -52,6 +66,13 @@ GLContext::~GLContext() {
   }
 }
 
+scoped_refptr<GLContext::FlushEvent> GLContext::SignalFlush() {
+  DCHECK(IsCurrent(NULL));
+  scoped_refptr<FlushEvent> flush_event = new FlushEvent();
+  flush_events_.push_back(flush_event);
+  return flush_event;
+}
+
 bool GLContext::GetTotalGpuMemory(size_t* bytes) {
   DCHECK(bytes);
   *bytes = 0;
@@ -190,6 +211,12 @@ void GLContext::SetRealGLApi() {
   SetGLToRealGLApi();
 }
 
+void GLContext::OnFlush() {
+  for (size_t n = 0; n < flush_events_.size(); n++)
+    flush_events_[n]->Signal();
+  flush_events_.clear();
+}
+
 GLContextReal::GLContextReal(GLShareGroup* share_group)
     : GLContext(share_group) {}
 
diff --git a/ui/gl/gl_context.h b/ui/gl/gl_context.h
index 63589c7..323b373 100644
--- a/ui/gl/gl_context.h
+++ b/ui/gl/gl_context.h
@@ -6,10 +6,12 @@
 #define UI_GL_GL_CONTEXT_H_
 
 #include <string>
+#include <vector>
 
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/synchronization/cancellation_flag.h"
 #include "ui/gl/gl_share_group.h"
 #include "ui/gl/gl_state_restorer.h"
 #include "ui/gl/gpu_preference.h"
@@ -32,6 +34,25 @@ class GL_EXPORT GLContext : public base::RefCounted<GLContext> {
   virtual bool Initialize(
       GLSurface* compatible_surface, GpuPreference gpu_preference) = 0;
 
+  class FlushEvent : public base::RefCountedThreadSafe<FlushEvent> {
+    public:
+      bool IsSignaled();
+
+    private:
+      friend class base::RefCountedThreadSafe<FlushEvent>;
+      friend class GLContext;
+      FlushEvent();
+      virtual ~FlushEvent();
+      void Signal();
+
+      base::CancellationFlag flag_;
+  };
+
+  // Needs to be called with this context current. It will return a FlushEvent
+  // that is initially unsignaled, but will transition to signaled after the
+  // next glFlush() or glFinish() occurs in this context.
+  scoped_refptr<FlushEvent> SignalFlush();
+
   // Destroys the GL context.
   virtual void Destroy() = 0;
 
@@ -114,6 +135,9 @@ class GL_EXPORT GLContext : public base::RefCounted<GLContext> {
   // Returns the GL renderer string. The context must be current.
   virtual std::string GetGLRenderer();
 
+  // Called when glFlush()/glFinish() is called with this context current.
+  void OnFlush();
+
  protected:
   virtual ~GLContext();
 
@@ -152,6 +176,8 @@ class GL_EXPORT GLContext : public base::RefCounted<GLContext> {
   scoped_ptr<GLStateRestorer> state_restorer_;
   scoped_ptr<GLVersionInfo> version_info_;
 
+  std::vector<scoped_refptr<FlushEvent> > flush_events_;
+
   DISALLOW_COPY_AND_ASSIGN(GLContext);
 };
 
diff --git a/ui/gl/gl_fence.cc b/ui/gl/gl_fence.cc
index f44570e..262de48 100644
--- a/ui/gl/gl_fence.cc
+++ b/ui/gl/gl_fence.cc
@@ -25,8 +25,11 @@ class GLFenceNVFence: public gfx::GLFence {
     //     We will arbitrarily return TRUE for consistency.
     glGenFencesNV(1, &fence_);
     glSetFenceNV(fence_, GL_ALL_COMPLETED_NV);
-    if (flush)
+    if (flush) {
       glFlush();
+    } else {
+      flush_event_ = gfx::GLContext::GetCurrent()->SignalFlush();
+    }
   }
 
   virtual bool HasCompleted() OVERRIDE {
@@ -34,11 +37,15 @@ class GLFenceNVFence: public gfx::GLFence {
   }
 
   virtual void ClientWait() OVERRIDE {
-    glFinishFenceNV(fence_);
+    if (!flush_event_ || flush_event_->IsSignaled()) {
+      glFinishFenceNV(fence_);
+    } else {
+      LOG(ERROR) << "Trying to wait for uncommitted fence. Skipping...";
+    }
   }
 
   virtual void ServerWait() OVERRIDE {
-    glFinishFenceNV(fence_);
+    ClientWait();
   }
 
  private:
@@ -47,14 +54,18 @@ class GLFenceNVFence: public gfx::GLFence {
   }
 
   GLuint fence_;
+  scoped_refptr<gfx::GLContext::FlushEvent> flush_event_;
 };
 
 class GLFenceARBSync: public gfx::GLFence {
  public:
   GLFenceARBSync(bool flush) {
     sync_ = glFenceSync(GL_SYNC_GPU_COMMANDS_COMPLETE, 0);
-    if (flush)
+    if (flush) {
       glFlush();
+    } else {
+      flush_event_ = gfx::GLContext::GetCurrent()->SignalFlush();
+    }
   }
 
   virtual bool HasCompleted() OVERRIDE {
@@ -69,11 +80,19 @@ class GLFenceARBSync: public gfx::GLFence {
   }
 
   virtual void ClientWait() OVERRIDE {
-    glClientWaitSync(sync_, GL_SYNC_FLUSH_COMMANDS_BIT, GL_TIMEOUT_IGNORED);
+    if (!flush_event_ || flush_event_->IsSignaled()) {
+      glClientWaitSync(sync_, GL_SYNC_FLUSH_COMMANDS_BIT, GL_TIMEOUT_IGNORED);
+    } else {
+      LOG(ERROR) << "Trying to wait for uncommitted fence. Skipping...";
+    }
   }
 
   virtual void ServerWait() OVERRIDE {
-    glWaitSync(sync_, 0, GL_TIMEOUT_IGNORED);
+    if (!flush_event_ || flush_event_->IsSignaled()) {
+      glWaitSync(sync_, 0, GL_TIMEOUT_IGNORED);
+    } else {
+      LOG(ERROR) << "Trying to wait for uncommitted fence. Skipping...";
+    }
   }
 
  private:
@@ -82,6 +101,7 @@ class GLFenceARBSync: public gfx::GLFence {
   }
 
   GLsync sync_;
+  scoped_refptr<gfx::GLContext::FlushEvent> flush_event_;
 };
 
 #if !defined(OS_MACOSX)
@@ -90,8 +110,11 @@ class EGLFenceSync : public gfx::GLFence {
   EGLFenceSync(bool flush) {
     display_ = eglGetCurrentDisplay();
     sync_ = eglCreateSyncKHR(display_, EGL_SYNC_FENCE_KHR, NULL);
-    if (flush)
+    if (flush) {
       glFlush();
+    } else {
+      flush_event_ = gfx::GLContext::GetCurrent()->SignalFlush();
+    }
   }
 
   virtual bool HasCompleted() OVERRIDE {
@@ -102,14 +125,22 @@ class EGLFenceSync : public gfx::GLFence {
   }
 
   virtual void ClientWait() OVERRIDE {
-    EGLint flags = 0;
-    EGLTimeKHR time = EGL_FOREVER_KHR;
-    eglClientWaitSyncKHR(display_, sync_, flags, time);
+    if (!flush_event_ || flush_event_->IsSignaled()) {
+      EGLint flags = 0;
+      EGLTimeKHR time = EGL_FOREVER_KHR;
+      eglClientWaitSyncKHR(display_, sync_, flags, time);
+    } else {
+      LOG(ERROR) << "Trying to wait for uncommitted fence. Skipping...";
+    }
   }
 
   virtual void ServerWait() OVERRIDE {
-    EGLint flags = 0;
-    eglWaitSyncKHR(display_, sync_, flags);
+    if (!flush_event_ || flush_event_->IsSignaled()) {
+      EGLint flags = 0;
+      eglWaitSyncKHR(display_, sync_, flags);
+    } else {
+      LOG(ERROR) << "Trying to wait for uncommitted fence. Skipping...";
+    }
   }
 
 
@@ -120,11 +151,15 @@ class EGLFenceSync : public gfx::GLFence {
 
   EGLSyncKHR sync_;
   EGLDisplay display_;
+  scoped_refptr<gfx::GLContext::FlushEvent> flush_event_;
 };
 #endif // !OS_MACOSX
 
 // static
 gfx::GLFence* CreateFence(bool flush) {
+  DCHECK(gfx::GLContext::GetCurrent())
+      << "Trying to create fence with no context";
+
 #if !defined(OS_MACOSX)
   if (gfx::g_driver_egl.ext.b_EGL_KHR_fence_sync)
     return new EGLFenceSync(flush);
diff --git a/ui/gl/gl_fence.h b/ui/gl/gl_fence.h
index c1967ec..021f345 100644
--- a/ui/gl/gl_fence.h
+++ b/ui/gl/gl_fence.h
@@ -16,11 +16,16 @@ class GL_EXPORT GLFence {
   virtual ~GLFence();
 
   static GLFence* Create();
+
   // Creates a fence that is not guaranteed to signal until the current context
-  // is flushed. Use with caution.
+  // is flushed. It is illegal to call Client/ServerWait() on a fence without
+  // having explicitly called glFlush() or glFinish() in the originating
+  // context.
   static GLFence* CreateWithoutFlush();
+
   virtual bool HasCompleted() = 0;
   virtual void ClientWait() = 0;
+
   // Will block the server if supported, but might fall back to blocking the
   // client.
   virtual void ServerWait() = 0;
diff --git a/ui/gl/gl_gl_api_implementation.cc b/ui/gl/gl_gl_api_implementation.cc
index 9d57247..fd5309c 100644
--- a/ui/gl/gl_gl_api_implementation.cc
+++ b/ui/gl/gl_gl_api_implementation.cc
@@ -355,6 +355,11 @@ void GLApiBase::InitializeBase(DriverGL* driver) {
   driver_ = driver;
 }
 
+void GLApiBase::SignalFlush() {
+  DCHECK(GLContext::GetCurrent());
+  GLContext::GetCurrent()->OnFlush();
+}
+
 RealGLApi::RealGLApi() {
 }
 
@@ -365,6 +370,16 @@ void RealGLApi::Initialize(DriverGL* driver) {
   InitializeBase(driver);
 }
 
+void RealGLApi::glFlushFn() {
+  GLApiBase::glFlushFn();
+  GLApiBase::SignalFlush();
+}
+
+void RealGLApi::glFinishFn() {
+  GLApiBase::glFinishFn();
+  GLApiBase::SignalFlush();
+}
+
 TraceGLApi::~TraceGLApi() {
 }
 
@@ -463,4 +478,14 @@ const GLubyte* VirtualGLApi::glGetStringFn(GLenum name) {
   }
 }
 
+void VirtualGLApi::glFlushFn() {
+  GLApiBase::glFlushFn();
+  GLApiBase::SignalFlush();
+}
+
+void VirtualGLApi::glFinishFn() {
+  GLApiBase::glFinishFn();
+  GLApiBase::SignalFlush();
+}
+
 }  // namespace gfx
diff --git a/ui/gl/gl_gl_api_implementation.h b/ui/gl/gl_gl_api_implementation.h
index d189691..aff5926 100644
--- a/ui/gl/gl_gl_api_implementation.h
+++ b/ui/gl/gl_gl_api_implementation.h
@@ -41,6 +41,7 @@ class GLApiBase : public GLApi {
   GLApiBase();
   virtual ~GLApiBase();
   void InitializeBase(DriverGL* driver);
+  void SignalFlush();
 
   DriverGL* driver_;
 };
@@ -51,6 +52,10 @@ class RealGLApi : public GLApiBase {
   RealGLApi();
   virtual ~RealGLApi();
   void Initialize(DriverGL* driver);
+
+ private:
+  virtual void glFinishFn() OVERRIDE;
+  virtual void glFlushFn() OVERRIDE;
 };
 
 // Inserts a TRACE for every GL call.
@@ -94,10 +99,12 @@ class VirtualGLApi : public GLApiBase {
 
   void OnReleaseVirtuallyCurrent(GLContext* virtual_context);
 
+private:
   // Overridden functions from GLApiBase
   virtual const GLubyte* glGetStringFn(GLenum name) OVERRIDE;
+  virtual void glFinishFn() OVERRIDE;
+  virtual void glFlushFn() OVERRIDE;
 
- private:
   // The real context we're running on.
   GLContext* real_context_;