ipc_data_source.h revision a1401311d1ab56c4ed0a474bd38c108f75cb0cd9 
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
16namespace base {
17class TaskRunner;
18}
19
20namespace 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.
26class 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_
76