Execute all GL commands up to the put offset reported by a flush.

content/common/gpu/gpu_channel.cc

Index: content/common/gpu/gpu_channel.cc
===================================================================
--- content/common/gpu/gpu_channel.cc	(revision 92876)
+++ content/common/gpu/gpu_channel.cc	(working copy)
@@ -33,7 +33,8 @@
       renderer_process_(base::kNullProcessHandle),
       renderer_pid_(base::kNullProcessId),
       share_group_(new gfx::GLShareGroup),
-      watchdog_(watchdog) {
+      watchdog_(watchdog),
+      task_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)) {
   DCHECK(gpu_channel_manager);
   DCHECK(renderer_id);
   const CommandLine* command_line = CommandLine::ForCurrentProcess();
@@ -86,9 +87,20 @@
             << " with type " << message.type();
   }
 
+  // Control messages are not deferred and can be handled out of order with
+  // respect to routed ones.
   if (message.routing_id() == MSG_ROUTING_CONTROL)
     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 (!router_.RouteMessage(message)) {
     // Respond to sync messages even if router failed to route.
     if (message.is_sync()) {
@@ -99,6 +111,20 @@
     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()));
+    }
+  }
+
   return true;
 }
 
@@ -127,6 +153,30 @@
   return channel_->Send(message);
 }
 
+bool GpuChannel::IsScheduled() {
+  for (StubMap::Iterator<GpuCommandBufferStub> it(&stubs_);
+       !it.IsAtEnd();
+       it.Advance()) {
+    GpuCommandBufferStub* stub = it.GetCurrentValue();
+    if (!stub->IsScheduled())
+      return false;
+  }
+
+  return true;
+}
+
+void GpuChannel::OnScheduled() {
+  // 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));
+}
+
 void GpuChannel::LoseAllContexts() {
   gpu_channel_manager_->LoseAllContexts();
 }
@@ -218,7 +268,7 @@
   // that matches the given render_view_id and delete the route.
   for (StubMap::const_iterator iter(&stubs_); !iter.IsAtEnd(); iter.Advance()) {
     if (iter.GetCurrentValue()->render_view_id() == render_view_id) {
-      OnDestroyCommandBuffer(iter.GetCurrentKey());
+      OnDestroyCommandBuffer(iter.GetCurrentKey(), NULL);
       return;
     }
   }
@@ -226,15 +276,17 @@
 #endif
 
 bool GpuChannel::OnControlMessageReceived(const IPC::Message& msg) {
+  // Always use IPC_MESSAGE_HANDLER_DELAY_REPLY for synchronous message handlers
+  // here. This is so the reply can be delayed if the scheduler is unscheduled.
   bool handled = true;
   IPC_BEGIN_MESSAGE_MAP(GpuChannel, msg)
     IPC_MESSAGE_HANDLER(GpuChannelMsg_Initialize, OnInitialize)
-    IPC_MESSAGE_HANDLER(GpuChannelMsg_CreateOffscreenCommandBuffer,
-        OnCreateOffscreenCommandBuffer)
-    IPC_MESSAGE_HANDLER(GpuChannelMsg_DestroyCommandBuffer,
-        OnDestroyCommandBuffer)
-    IPC_MESSAGE_HANDLER(GpuChannelMsg_CreateOffscreenSurface,
-                        OnCreateOffscreenSurface)
+    IPC_MESSAGE_HANDLER_DELAY_REPLY(GpuChannelMsg_CreateOffscreenCommandBuffer,
+                                    OnCreateOffscreenCommandBuffer)
+    IPC_MESSAGE_HANDLER_DELAY_REPLY(GpuChannelMsg_DestroyCommandBuffer,
+                                    OnDestroyCommandBuffer)
+    IPC_MESSAGE_HANDLER_DELAY_REPLY(GpuChannelMsg_CreateOffscreenSurface,
+                                    OnCreateOffscreenSurface)
     IPC_MESSAGE_HANDLER(GpuChannelMsg_DestroySurface, OnDestroySurface)
     IPC_MESSAGE_HANDLER(GpuChannelMsg_CreateTransportTexture,
         OnCreateTransportTexture)
@@ -244,6 +296,21 @@
   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_);
+
+  while (!deferred_messages_copy.empty()) {
+    scoped_ptr<IPC::Message> message(deferred_messages_copy.front());
+    deferred_messages_copy.pop();
+
+    OnMessageReceived(*message);
+  }
+}
+
 int GpuChannel::GenerateRouteID() {
   static int last_id = 0;
   return ++last_id;
@@ -261,10 +328,12 @@
 void GpuChannel::OnCreateOffscreenCommandBuffer(
     const gfx::Size& size,
     const GPUCreateCommandBufferConfig& init_params,
-    int32* route_id) {
+    IPC::Message* reply_message) {
+  int32 route_id = MSG_ROUTING_NONE;
+
   content::GetContentClient()->SetActiveURL(init_params.active_url);
 #if defined(ENABLE_GPU)
-  *route_id = GenerateRouteID();
+  route_id = GenerateRouteID();
 
   scoped_ptr<GpuCommandBufferStub> stub(new GpuCommandBufferStub(
       this,
@@ -273,36 +342,38 @@
       disallowed_extensions_,
       init_params.allowed_extensions,
       init_params.attribs,
-      *route_id,
+      route_id,
       0, 0, watchdog_));
-  router_.AddRoute(*route_id, stub.get());
-  stubs_.AddWithID(stub.release(), *route_id);
+  router_.AddRoute(route_id, stub.get());
+  stubs_.AddWithID(stub.release(), route_id);
   TRACE_EVENT1("gpu", "GpuChannel::OnCreateOffscreenCommandBuffer",
                "route_id", route_id);
-#else
-  *route_id = MSG_ROUTING_NONE;
 #endif
+
+  GpuChannelMsg_CreateOffscreenCommandBuffer::WriteReplyParams(
+      reply_message,
+      route_id);
+  Send(reply_message);
 }
 
-void GpuChannel::OnDestroyCommandBuffer(int32 route_id) {
+void GpuChannel::OnDestroyCommandBuffer(int32 route_id,
+                                        IPC::Message* reply_message) {
 #if defined(ENABLE_GPU)
   TRACE_EVENT1("gpu", "GpuChannel::OnDestroyCommandBuffer",
                "route_id", route_id);
   if (router_.ResolveRoute(route_id)) {
-    GpuCommandBufferStub* stub = stubs_.Lookup(route_id);
-    // In case the renderer is currently blocked waiting for a sync reply from
-    // the stub, allow the stub to clean up and unblock pending messages here:
-    if (stub != NULL)
-      stub->CommandBufferWasDestroyed();
     router_.RemoveRoute(route_id);
     stubs_.Remove(route_id);
   }
 #endif
+
+  if (reply_message)
+    Send(reply_message);
 }
 
 void GpuChannel::OnCreateOffscreenSurface(const gfx::Size& size,
-                                          int* route_id) {
-  *route_id = MSG_ROUTING_NONE;
+                                          IPC::Message* reply_message) {
+  int route_id = MSG_ROUTING_NONE;
 
 #if defined(ENABLE_GPU)
   scoped_refptr<gfx::GLSurface> surface(
@@ -310,15 +381,19 @@
   if (!surface.get())
     return;
 
-  *route_id = GenerateRouteID();
+  route_id = GenerateRouteID();
 
   scoped_ptr<GpuSurfaceStub> stub (new GpuSurfaceStub(this,
-                                                      *route_id,
+                                                      route_id,
                                                       surface.release()));
 
-  router_.AddRoute(*route_id, stub.get());
-  surfaces_.AddWithID(stub.release(), *route_id);
+  router_.AddRoute(route_id, stub.get());
+  surfaces_.AddWithID(stub.release(), route_id);
 #endif
+
+  GpuChannelMsg_CreateOffscreenSurface::WriteReplyParams(reply_message,
+                                                         route_id);
+  Send(reply_message);
 }
 
 void GpuChannel::OnDestroySurface(int route_id) {