cache_util.cc revision 5e3f23d412006dc4db4e659864679f29341e113f 
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#include "net/disk_cache/cache_util.h"
6
7#include "base/file_util.h"
8#include "base/location.h"
9#include "base/strings/string_util.h"
10#include "base/strings/stringprintf.h"
11#include "base/threading/thread_restrictions.h"
12#include "base/threading/worker_pool.h"
13
14namespace {
15
16const int kMaxOldFolders = 100;
17
18// Returns a fully qualified name from path and name, using a given name prefix
19// and index number. For instance, if the arguments are "/foo", "bar" and 5, it
20// will return "/foo/old_bar_005".
21base::FilePath GetPrefixedName(const base::FilePath& path,
22                               const std::string& name,
23                               int index) {
24  std::string tmp = base::StringPrintf("%s%s_%03d", "old_",
25                                       name.c_str(), index);
26  return path.AppendASCII(tmp);
27}
28
29// This is a simple callback to cleanup old caches.
30void CleanupCallback(const base::FilePath& path, const std::string& name) {
31  for (int i = 0; i < kMaxOldFolders; i++) {
32    base::FilePath to_delete = GetPrefixedName(path, name, i);
33    disk_cache::DeleteCache(to_delete, true);
34  }
35}
36
37// Returns a full path to rename the current cache, in order to delete it. path
38// is the current folder location, and name is the current folder name.
39base::FilePath GetTempCacheName(const base::FilePath& path,
40                                const std::string& name) {
41  // We'll attempt to have up to kMaxOldFolders folders for deletion.
42  for (int i = 0; i < kMaxOldFolders; i++) {
43    base::FilePath to_delete = GetPrefixedName(path, name, i);
44    if (!file_util::PathExists(to_delete))
45      return to_delete;
46  }
47  return base::FilePath();
48}
49
50}  // namespace
51
52namespace disk_cache {
53
54// In order to process a potentially large number of files, we'll rename the
55// cache directory to old_ + original_name + number, (located on the same parent
56// directory), and use a worker thread to delete all the files on all the stale
57// cache directories. The whole process can still fail if we are not able to
58// rename the cache directory (for instance due to a sharing violation), and in
59// that case a cache for this profile (on the desired path) cannot be created.
60bool DelayedCacheCleanup(const base::FilePath& full_path) {
61  // GetTempCacheName() and MoveCache() use synchronous file
62  // operations.
63  base::ThreadRestrictions::ScopedAllowIO allow_io;
64
65  base::FilePath current_path = full_path.StripTrailingSeparators();
66
67  base::FilePath path = current_path.DirName();
68  base::FilePath name = current_path.BaseName();
69#if defined(OS_POSIX)
70  std::string name_str = name.value();
71#elif defined(OS_WIN)
72  // We created this file so it should only contain ASCII.
73  std::string name_str = WideToASCII(name.value());
74#endif
75
76  base::FilePath to_delete = GetTempCacheName(path, name_str);
77  if (to_delete.empty()) {
78    LOG(ERROR) << "Unable to get another cache folder";
79    return false;
80  }
81
82  if (!disk_cache::MoveCache(full_path, to_delete)) {
83    LOG(ERROR) << "Unable to move cache folder " << full_path.value() << " to "
84               << to_delete.value();
85    return false;
86  }
87
88  base::WorkerPool::PostTask(
89      FROM_HERE, base::Bind(&CleanupCallback, path, name_str), true);
90  return true;
91}
92
93}  // namespace disk_cache
94