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1 // Copyright (c) 2006-2009 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 // FileSystemAccessor provides functions so consumers can do file access | |
6 // asynchronously. It would PostTask to FILE thread to access file info, then on | |
7 // completion PostTask back to the caller thread and pass the result back. | |
8 // Here is an example on how to use it to get file size: | |
9 // 1. Define a callback function so FileSystemAccessor could run it after the | |
10 // task has been completed: | |
11 // void Foo::GetFileSizeCallback(int64 result, void* param) { | |
12 // } | |
13 // 2. Call static function FileSystemAccessor::RequestFileSize, provide file | |
14 // path, param (any object you want to pass back to the callback function) | |
15 // and callback: | |
16 // FileSystemAccessor::RequestFileSize( | |
17 // path, | |
18 // param, | |
19 // NewCallback(this, &Foo::GetFileSizeCallback)); | |
20 // 3. FileSystemAceessor would PostTask to FILE thread to get file size, then | |
21 // on completion it would PostTask back to the current thread and run | |
22 // Foo::GetFileSizeCallback. | |
23 // | |
24 | |
25 #ifndef CHROME_BROWSER_RENDERER_HOST_FILE_SYSTEM_ACCESSOR_H_ | |
26 #define CHROME_BROWSER_RENDERER_HOST_FILE_SYSTEM_ACCESSOR_H_ | |
27 | |
28 #include "base/scoped_ptr.h" | |
29 #include "base/ref_counted.h" | |
30 #include "base/task.h" | |
31 | |
32 class FilePath; | |
33 class MessageLoop; | |
34 | |
35 class FileSystemAccessor | |
36 : public base::RefCountedThreadSafe<FileSystemAccessor> { | |
37 public: | |
38 typedef Callback2<int64, void*>::Type FileSizeCallback; | |
39 | |
40 virtual ~FileSystemAccessor(); | |
41 | |
42 // Request to get file size. | |
43 // | |
44 // param is an object that is owned by the caller and needs to pass back to | |
45 // the caller by FileSystemAccessor through the callback function. | |
46 // It can be set to NULL if no object needs to pass back. | |
47 // | |
48 // FileSizeCallback function is defined as: | |
49 // void f(int64 result, void* param); | |
50 // Variable result has the file size. If the file does not exist or there is | |
51 // error accessing the file, result is set to -1. If the given path is a | |
52 // directory, result is set to 0. | |
53 static void RequestFileSize(const FilePath& path, | |
54 void* param, | |
55 FileSizeCallback* callback); | |
56 | |
57 private: | |
58 FileSystemAccessor(void* param, FileSizeCallback* callback); | |
59 | |
60 // Get file size on the worker thread and pass result back to the caller | |
61 // thread. | |
62 void GetFileSize(const FilePath& path); | |
63 | |
64 // Getting file size completed, callback to reply message. | |
65 void GetFileSizeCompleted(int64 result); | |
66 | |
67 MessageLoop* caller_loop_; | |
68 void* param_; | |
69 scoped_ptr<FileSizeCallback> callback_; | |
70 | |
71 DISALLOW_COPY_AND_ASSIGN(FileSystemAccessor); | |
72 }; | |
73 | |
74 #endif // CHROME_BROWSER_RENDERER_HOST_FILE_SYSTEM_ACCESSOR_H_ | |
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