Allow FlushSyncs to short circuit

content/common/gpu/gpu_channel.cc

 // Copyright (c) 2011 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.
 
 #if defined(OS_WIN)
 #include <windows.h>
 #endif
 
 #include "content/common/gpu/gpu_channel.h"
 
@@ skipping 18 matching lines @@
                        GpuWatchdog* watchdog,
                        int renderer_id,
                        bool software)
     : gpu_channel_manager_(gpu_channel_manager),
       renderer_id_(renderer_id),
       renderer_process_(base::kNullProcessHandle),
       renderer_pid_(base::kNullProcessId),
       share_group_(new gfx::GLShareGroup),
       watchdog_(watchdog),
       software_(software),
+      handle_messages_scheduled_(false),
       task_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)) {
   DCHECK(gpu_channel_manager);
   DCHECK(renderer_id);
   const CommandLine* command_line = CommandLine::ForCurrentProcess();
   log_messages_ = command_line->HasSwitch(switches::kLogPluginMessages);
   disallowed_features_.multisampling =
       command_line->HasSwitch(switches::kDisableGLMultisampling);
   disallowed_features_.driver_bug_workarounds =
       command_line->HasSwitch(switches::kDisableGpuDriverBugWorkarounds);
 }
@@ skipping 20 matching lines @@
             << " with type " << message.type();
   }
 
   // Control messages are not deferred and can be handled out of order with
   // respect to routed ones. Except for Echo, which must be deferred in order
   // to respect the asynchronous Mac SwapBuffers.
   if (message.routing_id() == MSG_ROUTING_CONTROL &&
       message.type() != GpuChannelMsg_Echo::ID)
     return OnControlMessageReceived(message);
 
-  // If the channel is unscheduled, defer sync and async messages until it is
-  // rescheduled. Also, even if the channel is scheduled, do not allow newly
-  // received messages to be handled before previously received deferred ones;
-  // append them to the deferred queue as well.
-  if (!IsScheduled() || !deferred_messages_.empty()) {
-    deferred_messages_.push(new IPC::Message(message));
-    return true;
+  if (message.type() == GpuCommandBufferMsg_GetStateFast::ID) {
+    // Move GetStateFast commands to the head of the queue, so the renderer
+    // doesn't have to wait any longer than necessary.
+    deferred_messages_.push_front(new IPC::Message(message));
+  } else {
+    deferred_messages_.push_back(new IPC::Message(message));
   }
 
-  // Handle deferred control messages.
-  if (message.routing_id() == MSG_ROUTING_CONTROL)
-    return OnControlMessageReceived(message);
-
-  if (!router_.RouteMessage(message)) {
-    // Respond to sync messages even if router failed to route.
-    if (message.is_sync()) {
-      IPC::Message* reply = IPC::SyncMessage::GenerateReply(&message);
-      reply->set_reply_error();
-      Send(reply);
-    }
-    return false;
-  }
-
-  // If the channel becomes unscheduled as a result of handling the message,
-  // synthesize an IPC message to flush the command buffer that became
-  // unscheduled.
-  for (StubMap::Iterator<GpuCommandBufferStub> it(&stubs_);
-       !it.IsAtEnd();
-       it.Advance()) {
-    GpuCommandBufferStub* stub = it.GetCurrentValue();
-    if (!stub->IsScheduled()) {
-      DCHECK(deferred_messages_.empty());
-      deferred_messages_.push(new GpuCommandBufferMsg_Rescheduled(
-          stub->route_id()));
-    }
-  }
+  if (IsScheduled())
+    OnScheduled();
 
   return true;
 }
 
 void GpuChannel::OnChannelError() {
   gpu_channel_manager_->RemoveChannel(renderer_id_);
 }
 
 void GpuChannel::OnChannelConnected(int32 peer_pid) {
   renderer_pid_ = peer_pid;
@@ skipping 22 matching lines @@
        it.Advance()) {
     GpuCommandBufferStub* stub = it.GetCurrentValue();
     if (!stub->IsScheduled())
       return false;
   }
 
   return true;
 }
 
 void GpuChannel::OnScheduled() {
+  if (handle_messages_scheduled_)
+    return;
   // Post a task to handle any deferred messages. The deferred message queue is
   // not emptied here, which ensures that OnMessageReceived will continue to
   // defer newly received messages until the ones in the queue have all been
   // handled by HandleDeferredMessages. HandleDeferredMessages is invoked as a
   // task to prevent reentrancy.
   MessageLoop::current()->PostTask(
       FROM_HERE,
       task_factory_.NewRunnableMethod(
-          &GpuChannel::HandleDeferredMessages));
+          &GpuChannel::HandleMessage));
+  handle_messages_scheduled_ = true;
 }
 
 void GpuChannel::LoseAllContexts() {
   gpu_channel_manager_->LoseAllContexts();
 }
 
 void GpuChannel::DestroySoon() {
   MessageLoop::current()->PostTask(
       FROM_HERE, NewRunnableMethod(this,
           &GpuChannel::OnDestroy));
@@ skipping 73 matching lines @@
                                     OnDestroyCommandBuffer)
     IPC_MESSAGE_HANDLER(GpuChannelMsg_CreateTransportTexture,
         OnCreateTransportTexture)
     IPC_MESSAGE_HANDLER(GpuChannelMsg_Echo, OnEcho);
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
   DCHECK(handled) << msg.type();
   return handled;
 }
 
-void GpuChannel::HandleDeferredMessages() {
-  // Empty the deferred queue so OnMessageRecieved does not defer on that
-  // account and to prevent an infinite loop if the scheduler is unscheduled
-  // as a result of handling already deferred messages.
-  std::queue<IPC::Message*> deferred_messages_copy;
-  std::swap(deferred_messages_copy, deferred_messages_);
+void GpuChannel::HandleMessage() {
+  handle_messages_scheduled_ = false;
+  if (!IsScheduled())
+      return;
 
-  while (!deferred_messages_copy.empty()) {
-    scoped_ptr<IPC::Message> message(deferred_messages_copy.front());
-    deferred_messages_copy.pop();
+  if (!deferred_messages_.empty()) {
+    scoped_ptr<IPC::Message> message(deferred_messages_.front());
+    deferred_messages_.pop_front();
+    // Handle deferred control messages.
+    if (message->routing_id() == MSG_ROUTING_CONTROL)
+      OnControlMessageReceived(*message);
+    else if (!router_.RouteMessage(*message)) {
+      // Respond to sync messages even if router failed to route.
+      if (message->is_sync()) {
+        IPC::Message* reply = IPC::SyncMessage::GenerateReply(&*message);
+        reply->set_reply_error();
+        Send(reply);
+      }
+    } else {
+      // If the channel becomes unscheduled as a result of handling the message,
+      // synthesize an IPC message to flush the command buffer that became
+      // unscheduled.
+      for (StubMap::Iterator<GpuCommandBufferStub> it(&stubs_);
+           !it.IsAtEnd();
+           it.Advance()) {
+        GpuCommandBufferStub* stub = it.GetCurrentValue();
+        if (!stub->IsScheduled()) {
+          deferred_messages_.push_front(new GpuCommandBufferMsg_Rescheduled(
+              stub->route_id()));
+        }
+      }
+    }
+  }
 
-    OnMessageReceived(*message);
+  if (IsScheduled() && !deferred_messages_.empty()) {
+    OnScheduled();
   }
 }
 
 int GpuChannel::GenerateRouteID() {
   static int last_id = 0;
   return ++last_id;
 }
 
 void GpuChannel::AddRoute(int32 route_id, IPC::Channel::Listener* listener) {
   router_.AddRoute(route_id, listener);
@@ skipping 116 matching lines @@
 
 #if defined(OS_POSIX)
 int GpuChannel::TakeRendererFileDescriptor() {
   if (!channel_.get()) {
     NOTREACHED();
     return -1;
   }
   return channel_->TakeClientFileDescriptor();
 }
 #endif  // defined(OS_POSIX)