content/gpu: Simplify gpu channel message handling.

content/common/gpu/gpu_channel_manager.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 "content/common/gpu/gpu_channel_manager.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 89 matching lines @@
 }
 
 void GpuChannelManager::AddRoute(int32 routing_id, IPC::Listener* listener) {
   router_.AddRoute(routing_id, listener);
 }
 
 void GpuChannelManager::RemoveRoute(int32 routing_id) {
   router_.RemoveRoute(routing_id);
 }
 
-GpuChannel* GpuChannelManager::LookupChannel(int32 client_id) {
+GpuChannel* GpuChannelManager::LookupChannel(int32 client_id) const {
   const auto& it = gpu_channels_.find(client_id);
   return it != gpu_channels_.end() ? it->second : nullptr;
 }
 
 bool GpuChannelManager::OnControlMessageReceived(const IPC::Message& msg) {
   bool handled = true;
   IPC_BEGIN_MESSAGE_MAP(GpuChannelManager, msg)
     IPC_MESSAGE_HANDLER(GpuMsg_EstablishChannel, OnEstablishChannel)
     IPC_MESSAGE_HANDLER(GpuMsg_CloseChannel, OnCloseChannel)
     IPC_MESSAGE_HANDLER(GpuMsg_CreateViewCommandBuffer,
@@ skipping 123 matching lines @@
   auto it = gpu_channels_.find(client_id);
   if (it != gpu_channels_.end())
     it->second->HandleUpdateValueState(target, state);
 }
 
 void GpuChannelManager::OnLoadedShader(std::string program_proto) {
   if (program_cache())
     program_cache()->LoadProgram(program_proto);
 }
 
-uint32_t GpuChannelManager::ProcessedOrderNumber() {
+uint32_t GpuChannelManager::GetNextUnprocessedOrderNum() {
+  base::AutoLock lock(order_num_lock_);

[David Yen, 2015/09/10 22:42:06]

Is the new scheduler also going to use this? Seems like we exchanged a lock on
all the channels during pre-emption, for a lock on every IPC message, which is
better is hard to tell. 

Should we just use an Atomic32?

[sunnyps, 2015/09/10 23:38:36]

On second thought I'm keeping this as is for now - it's likely that the schedule
will be in charge of idle work anyway.

[David Yen, 2015/09/11 16:47:20]

per your comment yesterday, I think you are right. We can detect idle by simply
using the the highest current order number. We can even have a global one stored
in the GpuChannelManager which is updated as they are being handled and we
wouldn't even need to loop through the gpu channels.

+  return ++unprocessed_order_num_;
+}
+
+uint32_t GpuChannelManager::GetCurrentUnprocessedOrderNum() const {
+  base::AutoLock lock(order_num_lock_);
+  return unprocessed_order_num_;
+}
+
+uint32_t GpuChannelManager::GetProcessedOrderNum() const {
   uint32_t processed_order_num = 0;
   for (auto& kv : gpu_channels_) {
     processed_order_num =
         std::max(processed_order_num, kv.second->GetProcessedOrderNum());
   }
   return processed_order_num;
 }
 
-uint32_t GpuChannelManager::UnprocessedOrderNumber() {
-  uint32_t unprocessed_order_num = 0;
-  for (auto& kv : gpu_channels_) {
-    unprocessed_order_num =
-        std::max(unprocessed_order_num, kv.second->GetUnprocessedOrderNum());
-  }
-  return unprocessed_order_num;
-}
-
 void GpuChannelManager::LoseAllContexts() {
   for (auto& kv : gpu_channels_) {
     kv.second->MarkAllContextsLost();
   }
   task_runner_->PostTask(FROM_HERE,
                          base::Bind(&GpuChannelManager::OnLoseAllContexts,
                                     weak_factory_.GetWeakPtr()));
 }
 
 void GpuChannelManager::OnLoseAllContexts() {
   gpu_channels_.clear();
 }
 
 gfx::GLSurface* GpuChannelManager::GetDefaultOffscreenSurface() {
   if (!default_offscreen_surface_.get()) {
     default_offscreen_surface_ =
         gfx::GLSurface::CreateOffscreenGLSurface(gfx::Size());
   }
   return default_offscreen_surface_.get();
 }
 
 }  // namespace content