Support using TrackedCallbacks as hints to determine the handling thread of resource reply messages

ppapi/proxy/plugin_resource.h

 // 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.
 
 #ifndef PPAPI_PROXY_PLUGIN_RESOURCE_H_
 #define PPAPI_PROXY_PLUGIN_RESOURCE_H_
 
 #include <map>
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
+#include "base/memory/ref_counted.h"
 #include "ipc/ipc_message.h"
 #include "ipc/ipc_sender.h"
 #include "ppapi/c/pp_errors.h"
 #include "ppapi/proxy/connection.h"
 #include "ppapi/proxy/plugin_resource_callback.h"
 #include "ppapi/proxy/ppapi_message_utils.h"
 #include "ppapi/proxy/ppapi_proxy_export.h"
 #include "ppapi/proxy/resource_message_params.h"
+#include "ppapi/proxy/resource_reply_thread_registrar.h"
 #include "ppapi/shared_impl/resource.h"
-
+#include "ppapi/shared_impl/tracked_callback.h"
 namespace ppapi {
 namespace proxy {
 
 class PluginDispatcher;
 
 class PPAPI_PROXY_EXPORT PluginResource : public Resource {
  public:
   enum Destination {
     RENDERER = 0,
     BROWSER = 1
@@ skipping 60 matching lines @@
   //       2) It is *not* recommended to let |callback| hold any reference to
   //          |this|, in which it will be stored. Otherwise, this object will
   //          live forever if we fail to clean up the callback. It is safe to
   //          use base::Unretained(this) or a weak pointer, because this object
   //          will outlive the callback.
   template<typename ReplyMsgClass, typename CallbackType>
   int32_t Call(Destination dest,
                const IPC::Message& msg,
                const CallbackType& callback);
 
+  // Comparing with the previous Call() method, this method takes
+  // |reply_thread_hint| as a hint to determine which thread to handle the reply
+  // message.
+  //
+  // If |reply_thread_hint| is non-blocking, the reply message will be handled
+  // on the target thread of the callback; otherwise, it will be handled on the
+  // main thread.
+  //
+  // If handling a reply message will cause a TrackedCallback to be run, it is
+  // recommended to use this version of Call(). It eliminates unnecessary
+  // thread switching and therefore has better performance.
+  template<typename ReplyMsgClass, typename CallbackType>
+  int32_t Call(Destination dest,
+               const IPC::Message& msg,
+               const CallbackType& callback,
+               scoped_refptr<TrackedCallback> reply_thread_hint);
+
   // Calls the browser/renderer with sync messages. Returns the pepper error
   // code from the call.
   // |ReplyMsgClass| is the type of the reply message that is expected. If it
   // carries x parameters, then the method with x out parameters should be used.
   // An example of usage:
   //
   // // Assuming the reply message carries a string and an integer.
   // std::string param_1;
   // int param_2 = 0;
   // int32_t result = SyncCall<PpapiPluginMsg_MyResourceType_MyReplyMessage>(
@@ skipping 40 matching lines @@
   // Use GetNextSequence to retrieve the next value.
   int32_t next_sequence_number_;
 
   bool sent_create_to_browser_;
   bool sent_create_to_renderer_;
 
   typedef std::map<int32_t, scoped_refptr<PluginResourceCallbackBase> >
       CallbackMap;
   CallbackMap callbacks_;
 
+  scoped_refptr<ResourceReplyThreadRegistrar> resource_reply_thread_registrar_;
+
   DISALLOW_COPY_AND_ASSIGN(PluginResource);
 };
 
 template<typename ReplyMsgClass, typename CallbackType>
 int32_t PluginResource::Call(Destination dest,
                              const IPC::Message& msg,
                              const CallbackType& callback) {
+  return Call<ReplyMsgClass>(dest, msg, callback, NULL);
+}
+
+template<typename ReplyMsgClass, typename CallbackType>
+int32_t PluginResource::Call(
+    Destination dest,
+    const IPC::Message& msg,
+    const CallbackType& callback,
+    scoped_refptr<TrackedCallback> reply_thread_hint) {
   TRACE_EVENT2("ppapi proxy", "PluginResource::Call",
                "Class", IPC_MESSAGE_ID_CLASS(msg.type()),
                "Line", IPC_MESSAGE_ID_LINE(msg.type()));
   ResourceMessageCallParams params(pp_resource(), next_sequence_number_++);
   // Stash the |callback| in |callbacks_| identified by the sequence number of
   // the call.
   scoped_refptr<PluginResourceCallbackBase> plugin_callback(
       new PluginResourceCallback<ReplyMsgClass, CallbackType>(callback));
   callbacks_.insert(std::make_pair(params.sequence(), plugin_callback));
   params.set_has_callback();
+
+  if (resource_reply_thread_registrar_) {
+    resource_reply_thread_registrar_->Register(
+        pp_resource(), params.sequence(), reply_thread_hint);
+  }
   SendResourceCall(dest, params, msg);
   return params.sequence();
 }
 
 template <class ReplyMsgClass>
 int32_t PluginResource::SyncCall(Destination dest, const IPC::Message& msg) {
   IPC::Message reply;
   ResourceMessageReplyParams reply_params;
   return GenericSyncCall(dest, msg, &reply, &reply_params);
 }
@@ skipping 55 matching lines @@
 
   if (UnpackMessage<ReplyMsgClass>(reply, a, b, c, d, e))
     return result;
   return PP_ERROR_FAILED;
 }
 
 }  // namespace proxy
 }  // namespace ppapi
 
 #endif  // PPAPI_PROXY_PLUGIN_RESOURCE_H_