gpu: Implement idle async pixel transfers.

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 <list>
@@ skipping 609 matching lines @@
   virtual void RestoreFramebufferBindings() const OVERRIDE;
   virtual void RestoreTextureState(unsigned service_id) const OVERRIDE;
 
   virtual QueryManager* GetQueryManager() OVERRIDE {
     return query_manager_.get();
   }
   virtual VertexArrayManager* GetVertexArrayManager() OVERRIDE {
     return vertex_array_manager_.get();
   }
   virtual bool ProcessPendingQueries() OVERRIDE;
+  virtual bool HasMoreIdleWork() OVERRIDE;
+  virtual void PerformIdleWork() OVERRIDE;
 
   virtual void SetResizeCallback(
       const base::Callback<void(gfx::Size)>& callback) OVERRIDE;
 
   virtual void SetMsgCallback(const MsgCallback& callback) OVERRIDE;
   virtual void SetShaderCacheCallback(
       const ShaderCacheCallback& callback) OVERRIDE;
   virtual void SetWaitSyncPointCallback(
       const WaitSyncPointCallback& callback) OVERRIDE;
 
@@ skipping 8598 matching lines @@
 bool GLES2DecoderImpl::ProcessPendingQueries() {
   if (query_manager_.get() == NULL) {
     return false;
   }
   if (!query_manager_->ProcessPendingQueries()) {
     current_decoder_error_ = error::kOutOfBounds;
   }
   return query_manager_->HavePendingQueries();
 }
 
+bool GLES2DecoderImpl::HasMoreIdleWork() {
+  return async_pixel_transfer_delegate_->NeedsProcessMorePendingTransfers();
+}
+
+void GLES2DecoderImpl::PerformIdleWork() {
+  if (!async_pixel_transfer_delegate_->NeedsProcessMorePendingTransfers())
+    return;
+  if (async_pixel_transfer_delegate_->ProcessMorePendingTransfers())

[greggman, 2013/03/14 18:15:46]

I think I asked this in another CL. Would it be better to pass 'this' to
ProcessModePendingTransfers so that ProcessMorePendingTransfers can restore its
own state? It seems strange that the code out here has to know what state to
restore.

Also, you either need to remove the calls to glActiveTexture in
async_pixel_transfer_delegate_idle.cc or else you need to call
RestoreTextureUnitBindings(0)

[epenner, 2013/03/14 18:23:24]

It's currently a layering violation to do that, but we could make a
"RestoreCurrentTexture2DBindings" closure or interface that could be called. I
suggested we keep the booleans before since it's just a few functions, but it's
your call.

If the code moved the layering violation would go away, but I kind of like how
it currently has no dependency on the decoder.

[reveman, 2013/03/14 19:21:47]

Oh sorry, so we've gone back and forth here without me noticing. I switch to
just using the existing ProcessFinishedAsyncTransfers() call here based on your
feedback but epenner pointed out that this was a bit fragile so now we're back
to using a bool return value again.

I'd prefer to keep the current bool return value for now
(BindCompletedAsyncTransfers already does this) and clean it up be removing this
behavior from the AsyncPixelTransferDelegate completely in a follow up patch.
I've added TODO comments to the code and filed crbug.com/196303. gman, you OK
with that?
Done. Thanks for noticing this.

+    RestoreCurrentTexture2DBindings();
+  ProcessFinishedAsyncTransfers();
+}
+
 error::Error GLES2DecoderImpl::HandleBeginQueryEXT(
     uint32 immediate_data_size, const cmds::BeginQueryEXT& c) {
   GLenum target = static_cast<GLenum>(c.target);
   GLuint client_id = static_cast<GLuint>(c.id);
   int32 sync_shm_id = static_cast<int32>(c.sync_data_shm_id);
   uint32 sync_shm_offset = static_cast<uint32>(c.sync_data_shm_offset);
 
   switch (target) {
     case GL_COMMANDS_ISSUED_CHROMIUM:
     case GL_LATENCY_QUERY_CHROMIUM:
@@ skipping 1095 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