ppapi/proxy/resource_message_filter.h

   1 // Copyright 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef PPAPI_PROXY_RESOURCE_MESSAGE_FILTER_H_
   6 #define PPAPI_PROXY_RESOURCE_MESSAGE_FILTER_H_
   7
   8 #include "base/memory/ref_counted.h"
   9 #include "ppapi/proxy/ppapi_proxy_export.h"
  10
  11 namespace IPC {
  12 class Message;
  13 }
  14
  15 namespace ppapi {
  16 namespace proxy {
  17 class ResourceMessageReplyParams;
  18
  19 // A ResourceMessageFilter lives on the IO thread and handles messages for a
  20 // particular resource type. This is necessary in some cases where we want to
  21 // reduce latency by doing some work on the IO thread rather than having to
  22 // PostTask to the main Pepper thread.
  23 //
  24 // Note: In some cases we can rely on a reply being associated with a
  25 // particular TrackedCallback, in which case we can dispatch directly to the
  26 // TrackedCallback's thread. See ReplyThreadRegistrar. That should be the first
  27 // choice for avoiding an unecessary jump to the main-thread.
  28 //
  29 // ResourceMessageFilter is for cases where there is not a one-to-one
  30 // relationship between a reply message and a TrackedCallback. For example, for
  31 // UDP Socket resources, the browser pushes data to the plugin even when the
  32 // plugin does not have a pending callback. We can't use the
  33 // ReplyThreadRegistrar, because data may arrive when there's not yet a
  34 // TrackedCallback to tell us what thread to use. So instead, we define a
  35 // UDPSocketFilter which accepts and queues UDP data on the IO thread.
  36 class PPAPI_PROXY_EXPORT ResourceMessageFilter
  37     : public base::RefCountedThreadSafe<ResourceMessageFilter> {
  38  public:
  39   virtual bool OnResourceReplyReceived(
  40       const ResourceMessageReplyParams& reply_params,
  41       const IPC::Message& nested_msg) = 0;
  42
  43  protected:
  44   friend class base::RefCountedThreadSafe<ResourceMessageFilter>;
  45   virtual ~ResourceMessageFilter() {}
  46 };
  47
  48 }  // namespace proxy
  49 }  // namespace ppapi
  50
  51 #endif  // PPAPI_PROXY_RESOURCE_MESSAGE_FILTER_H_