file.h revision c5cede9ae108bb15f6b7a8aea21c7e1fefa2834c 
1// Copyright (c) 2012 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// See net/disk_cache/disk_cache.h for the public interface of the cache.
6
7#ifndef NET_DISK_CACHE_BLOCKFILE_FILE_H_
8#define NET_DISK_CACHE_BLOCKFILE_FILE_H_
9
10#include "base/files/file.h"
11#include "base/memory/ref_counted.h"
12#include "net/base/net_export.h"
13
14namespace base {
15class FilePath;
16}
17
18namespace disk_cache {
19
20// This interface is used to support asynchronous ReadData and WriteData calls.
21class FileIOCallback {
22 public:
23  // Notified of the actual number of bytes read or written. This value is
24  // negative if an error occurred.
25  virtual void OnFileIOComplete(int bytes_copied) = 0;
26
27 protected:
28  virtual ~FileIOCallback() {}
29};
30
31// Simple wrapper around a file that allows asynchronous operations.
32class NET_EXPORT_PRIVATE File : public base::RefCounted<File> {
33  friend class base::RefCounted<File>;
34 public:
35  File();
36  // mixed_mode set to true enables regular synchronous operations for the file.
37  explicit File(bool mixed_mode);
38
39  // Initializes the object to use the passed in file instead of opening it with
40  // the Init() call. No asynchronous operations can be performed with this
41  // object.
42  explicit File(base::File file);
43
44  // Initializes the object to point to a given file. The file must aready exist
45  // on disk, and allow shared read and write.
46  bool Init(const base::FilePath& name);
47
48  // Returns true if the file was opened properly.
49  bool IsValid() const;
50
51  // Performs synchronous IO.
52  bool Read(void* buffer, size_t buffer_len, size_t offset);
53  bool Write(const void* buffer, size_t buffer_len, size_t offset);
54
55  // Performs asynchronous IO. callback will be called when the IO completes,
56  // as an APC on the thread that queued the operation.
57  bool Read(void* buffer, size_t buffer_len, size_t offset,
58            FileIOCallback* callback, bool* completed);
59  bool Write(const void* buffer, size_t buffer_len, size_t offset,
60             FileIOCallback* callback, bool* completed);
61
62  // Sets the file's length. The file is truncated or extended with zeros to
63  // the new length.
64  bool SetLength(size_t length);
65  size_t GetLength();
66
67  // Blocks until |num_pending_io| IO operations complete.
68  static void WaitForPendingIO(int* num_pending_io);
69
70  // Drops current pending operations without waiting for them to complete.
71  static void DropPendingIO();
72
73 protected:
74  virtual ~File();
75
76  // Returns the handle or file descriptor.
77  base::PlatformFile platform_file() const;
78
79 private:
80  // Performs the actual asynchronous write. If notify is set and there is no
81  // callback, the call will be re-synchronized.
82  bool AsyncWrite(const void* buffer, size_t buffer_len, size_t offset,
83                  FileIOCallback* callback, bool* completed);
84
85  // Infrastructure for async IO.
86  int DoRead(void* buffer, size_t buffer_len, size_t offset);
87  int DoWrite(const void* buffer, size_t buffer_len, size_t offset);
88  void OnOperationComplete(FileIOCallback* callback, int result);
89
90  bool init_;
91  bool mixed_;
92  base::File base_file_;  // Regular, asynchronous IO handle.
93  base::File sync_base_file_;  // Synchronous IO handle.
94
95  DISALLOW_COPY_AND_ASSIGN(File);
96};
97
98}  // namespace disk_cache
99
100#endif  // NET_DISK_CACHE_BLOCKFILE_FILE_H_
101