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