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/files/file_enumerator.h"
9 #include "base/location.h"
10 #include "base/strings/string_util.h"
11 #include "base/strings/stringprintf.h"
12 #include "base/strings/utf_string_conversions.h"
13 #include "base/threading/thread_restrictions.h"
14 #include "base/threading/worker_pool.h"
15
16 namespace {
17
18 const int kMaxOldFolders = 100;
19
20 // Returns a fully qualified name from path and name, using a given name prefix
21 // and index number. For instance, if the arguments are "/foo", "bar" and 5, it
22 // will return "/foo/old_bar_005".
GetPrefixedName(const base::FilePath & path,const std::string & name,int index)23 base::FilePath GetPrefixedName(const base::FilePath& path,
24 const std::string& name,
25 int index) {
26 std::string tmp = base::StringPrintf("%s%s_%03d", "old_",
27 name.c_str(), index);
28 return path.AppendASCII(tmp);
29 }
30
31 // This is a simple callback to cleanup old caches.
CleanupCallback(const base::FilePath & path,const std::string & name)32 void CleanupCallback(const base::FilePath& path, const std::string& name) {
33 for (int i = 0; i < kMaxOldFolders; i++) {
34 base::FilePath to_delete = GetPrefixedName(path, name, i);
35 disk_cache::DeleteCache(to_delete, true);
36 }
37 }
38
39 // Returns a full path to rename the current cache, in order to delete it. path
40 // is the current folder location, and name is the current folder name.
GetTempCacheName(const base::FilePath & path,const std::string & name)41 base::FilePath GetTempCacheName(const base::FilePath& path,
42 const std::string& name) {
43 // We'll attempt to have up to kMaxOldFolders folders for deletion.
44 for (int i = 0; i < kMaxOldFolders; i++) {
45 base::FilePath to_delete = GetPrefixedName(path, name, i);
46 if (!base::PathExists(to_delete))
47 return to_delete;
48 }
49 return base::FilePath();
50 }
51
PreferredCacheSizeInternal(int64 available)52 int64 PreferredCacheSizeInternal(int64 available) {
53 using disk_cache::kDefaultCacheSize;
54 // Return 80% of the available space if there is not enough space to use
55 // kDefaultCacheSize.
56 if (available < kDefaultCacheSize * 10 / 8)
57 return available * 8 / 10;
58
59 // Return kDefaultCacheSize if it uses 10% to 80% of the available space.
60 if (available < kDefaultCacheSize * 10)
61 return kDefaultCacheSize;
62
63 // Return 10% of the available space if the target size
64 // (2.5 * kDefaultCacheSize) is more than 10%.
65 if (available < static_cast<int64>(kDefaultCacheSize) * 25)
66 return available / 10;
67
68 // Return the target size (2.5 * kDefaultCacheSize) if it uses 10% to 1%
69 // of the available space.
70 if (available < static_cast<int64>(kDefaultCacheSize) * 250)
71 return kDefaultCacheSize * 5 / 2;
72
73 // Return 1% of the available space.
74 return available / 100;
75 }
76
77 } // namespace
78
79 namespace disk_cache {
80
81 const int kDefaultCacheSize = 80 * 1024 * 1024;
82
DeleteCache(const base::FilePath & path,bool remove_folder)83 void DeleteCache(const base::FilePath& path, bool remove_folder) {
84 if (remove_folder) {
85 if (!base::DeleteFile(path, /* recursive */ true))
86 LOG(WARNING) << "Unable to delete cache folder.";
87 return;
88 }
89
90 base::FileEnumerator iter(
91 path,
92 /* recursive */ false,
93 base::FileEnumerator::FILES | base::FileEnumerator::DIRECTORIES);
94 for (base::FilePath file = iter.Next(); !file.value().empty();
95 file = iter.Next()) {
96 if (!base::DeleteFile(file, /* recursive */ true)) {
97 LOG(WARNING) << "Unable to delete cache.";
98 return;
99 }
100 }
101 }
102
103 // In order to process a potentially large number of files, we'll rename the
104 // cache directory to old_ + original_name + number, (located on the same parent
105 // directory), and use a worker thread to delete all the files on all the stale
106 // cache directories. The whole process can still fail if we are not able to
107 // rename the cache directory (for instance due to a sharing violation), and in
108 // that case a cache for this profile (on the desired path) cannot be created.
DelayedCacheCleanup(const base::FilePath & full_path)109 bool DelayedCacheCleanup(const base::FilePath& full_path) {
110 // GetTempCacheName() and MoveCache() use synchronous file
111 // operations.
112 base::ThreadRestrictions::ScopedAllowIO allow_io;
113
114 base::FilePath current_path = full_path.StripTrailingSeparators();
115
116 base::FilePath path = current_path.DirName();
117 base::FilePath name = current_path.BaseName();
118 #if defined(OS_POSIX)
119 std::string name_str = name.value();
120 #elif defined(OS_WIN)
121 // We created this file so it should only contain ASCII.
122 std::string name_str = base::UTF16ToASCII(name.value());
123 #endif
124
125 base::FilePath to_delete = GetTempCacheName(path, name_str);
126 if (to_delete.empty()) {
127 LOG(ERROR) << "Unable to get another cache folder";
128 return false;
129 }
130
131 if (!disk_cache::MoveCache(full_path, to_delete)) {
132 LOG(ERROR) << "Unable to move cache folder " << full_path.value() << " to "
133 << to_delete.value();
134 return false;
135 }
136
137 base::WorkerPool::PostTask(
138 FROM_HERE, base::Bind(&CleanupCallback, path, name_str), true);
139 return true;
140 }
141
142 // Returns the preferred maximum number of bytes for the cache given the
143 // number of available bytes.
PreferredCacheSize(int64 available)144 int PreferredCacheSize(int64 available) {
145 if (available < 0)
146 return kDefaultCacheSize;
147
148 int64 max_size = PreferredCacheSizeInternal(available);
149
150 // Limit cache size to somewhat less than kint32max to avoid potential
151 // integer overflows in cache backend implementations.
152 DCHECK(kDefaultCacheSize * 4 < kint32max);
153 if (max_size > kDefaultCacheSize * 4)
154 max_size = kDefaultCacheSize * 4;
155
156 return implicit_cast<int32>(max_size);
157 }
158
159 } // namespace disk_cache
160