| OLD | NEW |
|---|
| (Empty) |
| 1 // Copyright (c) 2011 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 "base/files/file_path_watcher.h" | |
| 6 | |
| 7 #include "base/bind.h" | |
| 8 #include "base/files/file.h" | |
| 9 #include "base/files/file_path.h" | |
| 10 #include "base/files/file_util.h" | |
| 11 #include "base/logging.h" | |
| 12 #include "base/memory/ref_counted.h" | |
| 13 #include "base/thread_task_runner_handle.h" | |
| 14 #include "base/time/time.h" | |
| 15 #include "base/win/object_watcher.h" | |
| 16 | |
| 17 namespace base { | |
| 18 | |
| 19 namespace { | |
| 20 | |
| 21 class FilePathWatcherImpl : public FilePathWatcher::PlatformDelegate, | |
| 22 public base::win::ObjectWatcher::Delegate, | |
| 23 public MessageLoop::DestructionObserver { | |
| 24 public: | |
| 25 FilePathWatcherImpl() | |
| 26 : handle_(INVALID_HANDLE_VALUE), | |
| 27 recursive_watch_(false) {} | |
| 28 | |
| 29 // FilePathWatcher::PlatformDelegate overrides. | |
| 30 bool Watch(const FilePath& path, | |
| 31 bool recursive, | |
| 32 const FilePathWatcher::Callback& callback) override; | |
| 33 void Cancel() override; | |
| 34 | |
| 35 // Deletion of the FilePathWatcher will call Cancel() to dispose of this | |
| 36 // object in the right thread. This also observes destruction of the required | |
| 37 // cleanup thread, in case it quits before Cancel() is called. | |
| 38 void WillDestroyCurrentMessageLoop() override; | |
| 39 | |
| 40 // Callback from MessageLoopForIO. | |
| 41 void OnObjectSignaled(HANDLE object) override; | |
| 42 | |
| 43 private: | |
| 44 ~FilePathWatcherImpl() override {} | |
| 45 | |
| 46 // Setup a watch handle for directory |dir|. Set |recursive| to true to watch | |
| 47 // the directory sub trees. Returns true if no fatal error occurs. |handle| | |
| 48 // will receive the handle value if |dir| is watchable, otherwise | |
| 49 // INVALID_HANDLE_VALUE. | |
| 50 static bool SetupWatchHandle(const FilePath& dir, | |
| 51 bool recursive, | |
| 52 HANDLE* handle) WARN_UNUSED_RESULT; | |
| 53 | |
| 54 // (Re-)Initialize the watch handle. | |
| 55 bool UpdateWatch() WARN_UNUSED_RESULT; | |
| 56 | |
| 57 // Destroy the watch handle. | |
| 58 void DestroyWatch(); | |
| 59 | |
| 60 // Cleans up and stops observing the |task_runner_| thread. | |
| 61 void CancelOnMessageLoopThread() override; | |
| 62 | |
| 63 // Callback to notify upon changes. | |
| 64 FilePathWatcher::Callback callback_; | |
| 65 | |
| 66 // Path we're supposed to watch (passed to callback). | |
| 67 FilePath target_; | |
| 68 | |
| 69 // Handle for FindFirstChangeNotification. | |
| 70 HANDLE handle_; | |
| 71 | |
| 72 // ObjectWatcher to watch handle_ for events. | |
| 73 base::win::ObjectWatcher watcher_; | |
| 74 | |
| 75 // Set to true to watch the sub trees of the specified directory file path. | |
| 76 bool recursive_watch_; | |
| 77 | |
| 78 // Keep track of the last modified time of the file. We use nulltime | |
| 79 // to represent the file not existing. | |
| 80 Time last_modified_; | |
| 81 | |
| 82 // The time at which we processed the first notification with the | |
| 83 // |last_modified_| time stamp. | |
| 84 Time first_notification_; | |
| 85 | |
| 86 DISALLOW_COPY_AND_ASSIGN(FilePathWatcherImpl); | |
| 87 }; | |
| 88 | |
| 89 bool FilePathWatcherImpl::Watch(const FilePath& path, | |
| 90 bool recursive, | |
| 91 const FilePathWatcher::Callback& callback) { | |
| 92 DCHECK(target_.value().empty()); // Can only watch one path. | |
| 93 | |
| 94 set_task_runner(ThreadTaskRunnerHandle::Get()); | |
| 95 callback_ = callback; | |
| 96 target_ = path; | |
| 97 recursive_watch_ = recursive; | |
| 98 MessageLoop::current()->AddDestructionObserver(this); | |
| 99 | |
| 100 File::Info file_info; | |
| 101 if (GetFileInfo(target_, &file_info)) { | |
| 102 last_modified_ = file_info.last_modified; | |
| 103 first_notification_ = Time::Now(); | |
| 104 } | |
| 105 | |
| 106 if (!UpdateWatch()) | |
| 107 return false; | |
| 108 | |
| 109 watcher_.StartWatching(handle_, this); | |
| 110 | |
| 111 return true; | |
| 112 } | |
| 113 | |
| 114 void FilePathWatcherImpl::Cancel() { | |
| 115 if (callback_.is_null()) { | |
| 116 // Watch was never called, or the |task_runner_| has already quit. | |
| 117 set_cancelled(); | |
| 118 return; | |
| 119 } | |
| 120 | |
| 121 // Switch to the file thread if necessary so we can stop |watcher_|. | |
| 122 if (!task_runner()->BelongsToCurrentThread()) { | |
| 123 task_runner()->PostTask(FROM_HERE, Bind(&FilePathWatcher::CancelWatch, | |
| 124 make_scoped_refptr(this))); | |
| 125 } else { | |
| 126 CancelOnMessageLoopThread(); | |
| 127 } | |
| 128 } | |
| 129 | |
| 130 void FilePathWatcherImpl::CancelOnMessageLoopThread() { | |
| 131 DCHECK(task_runner()->BelongsToCurrentThread()); | |
| 132 set_cancelled(); | |
| 133 | |
| 134 if (handle_ != INVALID_HANDLE_VALUE) | |
| 135 DestroyWatch(); | |
| 136 | |
| 137 if (!callback_.is_null()) { | |
| 138 MessageLoop::current()->RemoveDestructionObserver(this); | |
| 139 callback_.Reset(); | |
| 140 } | |
| 141 } | |
| 142 | |
| 143 void FilePathWatcherImpl::WillDestroyCurrentMessageLoop() { | |
| 144 CancelOnMessageLoopThread(); | |
| 145 } | |
| 146 | |
| 147 void FilePathWatcherImpl::OnObjectSignaled(HANDLE object) { | |
| 148 DCHECK(object == handle_); | |
| 149 // Make sure we stay alive through the body of this function. | |
| 150 scoped_refptr<FilePathWatcherImpl> keep_alive(this); | |
| 151 | |
| 152 if (!UpdateWatch()) { | |
| 153 callback_.Run(target_, true /* error */); | |
| 154 return; | |
| 155 } | |
| 156 | |
| 157 // Check whether the event applies to |target_| and notify the callback. | |
| 158 File::Info file_info; | |
| 159 bool file_exists = GetFileInfo(target_, &file_info); | |
| 160 if (recursive_watch_) { | |
| 161 // Only the mtime of |target_| is tracked but in a recursive watch, | |
| 162 // some other file or directory may have changed so all notifications | |
| 163 // are passed through. It is possible to figure out which file changed | |
| 164 // using ReadDirectoryChangesW() instead of FindFirstChangeNotification(), | |
| 165 // but that function is quite complicated: | |
| 166 // http://qualapps.blogspot.com/2010/05/understanding-readdirectorychangesw.
html | |
| 167 callback_.Run(target_, false); | |
| 168 } else if (file_exists && (last_modified_.is_null() || | |
| 169 last_modified_ != file_info.last_modified)) { | |
| 170 last_modified_ = file_info.last_modified; | |
| 171 first_notification_ = Time::Now(); | |
| 172 callback_.Run(target_, false); | |
| 173 } else if (file_exists && last_modified_ == file_info.last_modified && | |
| 174 !first_notification_.is_null()) { | |
| 175 // The target's last modification time is equal to what's on record. This | |
| 176 // means that either an unrelated event occurred, or the target changed | |
| 177 // again (file modification times only have a resolution of 1s). Comparing | |
| 178 // file modification times against the wall clock is not reliable to find | |
| 179 // out whether the change is recent, since this code might just run too | |
| 180 // late. Moreover, there's no guarantee that file modification time and wall | |
| 181 // clock times come from the same source. | |
| 182 // | |
| 183 // Instead, the time at which the first notification carrying the current | |
| 184 // |last_notified_| time stamp is recorded. Later notifications that find | |
| 185 // the same file modification time only need to be forwarded until wall | |
| 186 // clock has advanced one second from the initial notification. After that | |
| 187 // interval, client code is guaranteed to having seen the current revision | |
| 188 // of the file. | |
| 189 if (Time::Now() - first_notification_ > TimeDelta::FromSeconds(1)) { | |
| 190 // Stop further notifications for this |last_modification_| time stamp. | |
| 191 first_notification_ = Time(); | |
| 192 } | |
| 193 callback_.Run(target_, false); | |
| 194 } else if (!file_exists && !last_modified_.is_null()) { | |
| 195 last_modified_ = Time(); | |
| 196 callback_.Run(target_, false); | |
| 197 } | |
| 198 | |
| 199 // The watch may have been cancelled by the callback. | |
| 200 if (handle_ != INVALID_HANDLE_VALUE) | |
| 201 watcher_.StartWatching(handle_, this); | |
| 202 } | |
| 203 | |
| 204 // static | |
| 205 bool FilePathWatcherImpl::SetupWatchHandle(const FilePath& dir, | |
| 206 bool recursive, | |
| 207 HANDLE* handle) { | |
| 208 *handle = FindFirstChangeNotification( | |
| 209 dir.value().c_str(), | |
| 210 recursive, | |
| 211 FILE_NOTIFY_CHANGE_FILE_NAME | FILE_NOTIFY_CHANGE_SIZE | | |
| 212 FILE_NOTIFY_CHANGE_LAST_WRITE | FILE_NOTIFY_CHANGE_DIR_NAME | | |
| 213 FILE_NOTIFY_CHANGE_ATTRIBUTES | FILE_NOTIFY_CHANGE_SECURITY); | |
| 214 if (*handle != INVALID_HANDLE_VALUE) { | |
| 215 // Make sure the handle we got points to an existing directory. It seems | |
| 216 // that windows sometimes hands out watches to directories that are | |
| 217 // about to go away, but doesn't sent notifications if that happens. | |
| 218 if (!DirectoryExists(dir)) { | |
| 219 FindCloseChangeNotification(*handle); | |
| 220 *handle = INVALID_HANDLE_VALUE; | |
| 221 } | |
| 222 return true; | |
| 223 } | |
| 224 | |
| 225 // If FindFirstChangeNotification failed because the target directory | |
| 226 // doesn't exist, access is denied (happens if the file is already gone but | |
| 227 // there are still handles open), or the target is not a directory, try the | |
| 228 // immediate parent directory instead. | |
| 229 DWORD error_code = GetLastError(); | |
| 230 if (error_code != ERROR_FILE_NOT_FOUND && | |
| 231 error_code != ERROR_PATH_NOT_FOUND && | |
| 232 error_code != ERROR_ACCESS_DENIED && | |
| 233 error_code != ERROR_SHARING_VIOLATION && | |
| 234 error_code != ERROR_DIRECTORY) { | |
| 235 DPLOG(ERROR) << "FindFirstChangeNotification failed for " | |
| 236 << dir.value(); | |
| 237 return false; | |
| 238 } | |
| 239 | |
| 240 return true; | |
| 241 } | |
| 242 | |
| 243 bool FilePathWatcherImpl::UpdateWatch() { | |
| 244 if (handle_ != INVALID_HANDLE_VALUE) | |
| 245 DestroyWatch(); | |
| 246 | |
| 247 // Start at the target and walk up the directory chain until we succesfully | |
| 248 // create a watch handle in |handle_|. |child_dirs| keeps a stack of child | |
| 249 // directories stripped from target, in reverse order. | |
| 250 std::vector<FilePath> child_dirs; | |
| 251 FilePath watched_path(target_); | |
| 252 while (true) { | |
| 253 if (!SetupWatchHandle(watched_path, recursive_watch_, &handle_)) | |
| 254 return false; | |
| 255 | |
| 256 // Break if a valid handle is returned. Try the parent directory otherwise. | |
| 257 if (handle_ != INVALID_HANDLE_VALUE) | |
| 258 break; | |
| 259 | |
| 260 // Abort if we hit the root directory. | |
| 261 child_dirs.push_back(watched_path.BaseName()); | |
| 262 FilePath parent(watched_path.DirName()); | |
| 263 if (parent == watched_path) { | |
| 264 DLOG(ERROR) << "Reached the root directory"; | |
| 265 return false; | |
| 266 } | |
| 267 watched_path = parent; | |
| 268 } | |
| 269 | |
| 270 // At this point, handle_ is valid. However, the bottom-up search that the | |
| 271 // above code performs races against directory creation. So try to walk back | |
| 272 // down and see whether any children appeared in the mean time. | |
| 273 while (!child_dirs.empty()) { | |
| 274 watched_path = watched_path.Append(child_dirs.back()); | |
| 275 child_dirs.pop_back(); | |
| 276 HANDLE temp_handle = INVALID_HANDLE_VALUE; | |
| 277 if (!SetupWatchHandle(watched_path, recursive_watch_, &temp_handle)) | |
| 278 return false; | |
| 279 if (temp_handle == INVALID_HANDLE_VALUE) | |
| 280 break; | |
| 281 FindCloseChangeNotification(handle_); | |
| 282 handle_ = temp_handle; | |
| 283 } | |
| 284 | |
| 285 return true; | |
| 286 } | |
| 287 | |
| 288 void FilePathWatcherImpl::DestroyWatch() { | |
| 289 watcher_.StopWatching(); | |
| 290 FindCloseChangeNotification(handle_); | |
| 291 handle_ = INVALID_HANDLE_VALUE; | |
| 292 } | |
| 293 | |
| 294 } // namespace | |
| 295 | |
| 296 FilePathWatcher::FilePathWatcher() { | |
| 297 impl_ = new FilePathWatcherImpl(); | |
| 298 } | |
| 299 | |
| 300 } // namespace base | |
| OLD | NEW |
|---|
Chromium Code Reviews
Issue 1446363003:
Deleted OS_WIN and all Windows specific files from base. (Closed)
Base URL: https://github.com/domokit/mojo.git@base_tests