gpu: Reduce GL context switches used to check pending queries.

gpu/command_buffer/service/gles2_cmd_decoder.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 "gpu/command_buffer/service/gles2_cmd_decoder.h"
 
 #include <stdio.h>
 
 #include <algorithm>
 #include <cmath>
@@ skipping 649 matching lines @@
   QueryManager* GetQueryManager() override { return query_manager_.get(); }
   VertexArrayManager* GetVertexArrayManager() override {
     return vertex_array_manager_.get();
   }
   ImageManager* GetImageManager() override { return image_manager_.get(); }
 
   ValuebufferManager* GetValuebufferManager() override {
     return valuebuffer_manager();
   }
 
-  bool ProcessPendingQueries(bool did_finish) override;
+  bool HasPendingQueries() const override;
+  void ProcessPendingQueries(bool did_finish) override;
 
-  bool HasMoreIdleWork() override;
+  bool HasMoreIdleWork() const override;
   void PerformIdleWork() override;
 
   void WaitForReadPixels(base::Closure callback) override;
 
   void SetResizeCallback(
       const base::Callback<void(gfx::Size, float)>& callback) override;
 
   Logger* GetLogger() override;
 
   void BeginDecoding() override;
@@ skipping 11201 matching lines @@
   return true;
 }
 
 void GLES2DecoderImpl::DeleteQueriesEXTHelper(
     GLsizei n, const GLuint* client_ids) {
   for (GLsizei ii = 0; ii < n; ++ii) {
     query_manager_->RemoveQuery(client_ids[ii]);
   }
 }
 
-bool GLES2DecoderImpl::ProcessPendingQueries(bool did_finish) {
-  if (query_manager_.get() == NULL) {
-    return false;
-  }
-  if (!query_manager_->ProcessPendingQueries(did_finish)) {
+bool GLES2DecoderImpl::HasPendingQueries() const {
+  return query_manager_.get() && query_manager_->HavePendingQueries();
+}
+
+void GLES2DecoderImpl::ProcessPendingQueries(bool did_finish) {
+  if (!query_manager_.get())

[dshwang, 2015/09/01 08:56:10]

if (!HasPendingQueries())

[reveman, 2015/09/01 15:54:11]

It's up to the caller to do that check if needed. This way the code is more
consistent with PerformIdleWork.

+    return;
+  if (!query_manager_->ProcessPendingQueries(did_finish))
     current_decoder_error_ = error::kOutOfBounds;
-  }
-  return query_manager_->HavePendingQueries();
 }
 
 // Note that if there are no pending readpixels right now,
 // this function will call the callback immediately.
 void GLES2DecoderImpl::WaitForReadPixels(base::Closure callback) {
   if (features().use_async_readpixels && !pending_readpixel_fences_.empty()) {
     pending_readpixel_fences_.back()->callbacks.push_back(callback);
   } else {
     callback.Run();
   }
 }
 
 void GLES2DecoderImpl::ProcessPendingReadPixels(bool did_finish) {
   // Note: |did_finish| guarantees that the GPU has passed the fence but
   // we cannot assume that GLFence::HasCompleted() will return true yet as
   // that's not guaranteed by all GLFence implementations.
   while (!pending_readpixel_fences_.empty() &&
          (did_finish ||
           pending_readpixel_fences_.front()->fence->HasCompleted())) {
     std::vector<base::Closure> callbacks =
         pending_readpixel_fences_.front()->callbacks;
     pending_readpixel_fences_.pop();
     for (size_t i = 0; i < callbacks.size(); i++) {
       callbacks[i].Run();
     }
   }
 }
 
-bool GLES2DecoderImpl::HasMoreIdleWork() {
+bool GLES2DecoderImpl::HasMoreIdleWork() const {
   return !pending_readpixel_fences_.empty() ||
          gpu_tracer_->HasTracesToProcess();
 }
 
 void GLES2DecoderImpl::PerformIdleWork() {
   gpu_tracer_->ProcessTraces();
   ProcessPendingReadPixels(false);
 }
 
 error::Error GLES2DecoderImpl::HandleBeginQueryEXT(uint32 immediate_data_size,
@@ skipping 2726 matching lines @@
   return error::kNoError;
 }
 
 // Include the auto-generated part of this file. We split this because it means
 // we can easily edit the non-auto generated parts right here in this file
 // instead of having to edit some template or the code generator.
 #include "gpu/command_buffer/service/gles2_cmd_decoder_autogen.h"
 
 }  // namespace gles2
 }  // namespace gpu