chrome/utility/media_galleries/ipc_data_source.h

   1 // Copyright 2014 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 CHROME_UTILITY_MEDIA_GALLERIES_IPC_DATA_SOURCE_H_
   6 #define CHROME_UTILITY_MEDIA_GALLERIES_IPC_DATA_SOURCE_H_
   7
   8 #include <map>
   9 #include <string>
  10
  11 #include "base/memory/ref_counted.h"
  12 #include "base/threading/thread_checker.h"
  13 #include "chrome/utility/utility_message_handler.h"
  14 #include "media/base/data_source.h"
  15
  16 namespace base {
  17 class TaskRunner;
  18 }
  19
  20 namespace metadata {
  21
  22 // Provides the metadata parser with bytes from the browser process via IPC.
  23 // Class must be created and destroyed on the utility thread. Class may be used
  24 // as a DataSource on a different thread. The utility thread must not be blocked
  25 // for read operations to succeed.
  26 class IPCDataSource: public media::DataSource,
  27                      public chrome::UtilityMessageHandler {
  28  public:
  29   // May only be called on the utility thread.
  30   explicit IPCDataSource(int64 total_size);
  31   virtual ~IPCDataSource();
  32
  33   // Implementation of DataSource. These methods may be called on any single
  34   // thread. First usage of these methods attaches a thread checker.
  35   virtual void set_host(media::DataSourceHost* host) OVERRIDE;
  36   virtual void Stop(const base::Closure& callback) OVERRIDE;
  37   virtual void Read(int64 position, int size, uint8* data,
  38                     const ReadCB& read_cb) OVERRIDE;
  39   virtual bool GetSize(int64* size_out) OVERRIDE;
  40   virtual bool IsStreaming() OVERRIDE;
  41   virtual void SetBitrate(int bitrate) OVERRIDE;
  42
  43   // Implementation of UtilityMessageHandler. May only be called on the utility
  44   // thread.
  45   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
  46
  47  private:
  48   struct Request {
  49     Request();
  50     ~Request();
  51     uint8* destination;
  52     ReadCB callback;
  53   };
  54
  55   void ReadOnUtilityThread(int64 position, int size, uint8* data,
  56                            const ReadCB& read_cb);
  57
  58   void OnRequestBlobBytesFinished(int64 request_id,
  59                                   const std::string& bytes);
  60
  61   const int64 total_size_;
  62
  63   scoped_refptr<base::TaskRunner> utility_task_runner_;
  64   std::map<int64, Request> pending_requests_;
  65   int64 next_request_id_;
  66
  67   base::ThreadChecker utility_thread_checker_;
  68
  69   // Enforces that the DataSource methods are called on one other thread only.
  70   base::ThreadChecker data_source_thread_checker_;
  71 };
  72
  73 }  // namespace metadata
  74
  75 #endif  // CHROME_UTILITY_MEDIA_GALLERIES_IPC_DATA_SOURCE_H_