| // Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file |
| // for details. All rights reserved. Use of this source code is governed by a |
| // BSD-style license that can be found in the LICENSE file. |
| |
| import 'dart:async'; |
| import 'dart:io'; |
| |
| import 'package:path/path.dart' as p; |
| |
| import '../directory_watcher.dart'; |
| import '../path_set.dart'; |
| import '../resubscribable.dart'; |
| import '../utils.dart'; |
| import '../watch_event.dart'; |
| |
| /// Uses the FSEvents subsystem to watch for filesystem events. |
| /// |
| /// FSEvents has two main idiosyncrasies that this class works around. First, it |
| /// will occasionally report events that occurred before the filesystem watch |
| /// was initiated. Second, if multiple events happen to the same file in close |
| /// succession, it won't report them in the order they occurred. See issue |
| /// 14373. |
| /// |
| /// This also works around issues 16003 and 14849 in the implementation of |
| /// [Directory.watch]. |
| class MacOSDirectoryWatcher extends ResubscribableWatcher |
| implements DirectoryWatcher { |
| @override |
| String get directory => path; |
| |
| MacOSDirectoryWatcher(String directory) |
| : super(directory, () => _MacOSDirectoryWatcher(directory)); |
| } |
| |
| class _MacOSDirectoryWatcher |
| implements DirectoryWatcher, ManuallyClosedWatcher { |
| @override |
| String get directory => path; |
| @override |
| final String path; |
| |
| @override |
| Stream<WatchEvent> get events => _eventsController.stream; |
| final _eventsController = StreamController<WatchEvent>.broadcast(); |
| |
| @override |
| bool get isReady => _readyCompleter.isCompleted; |
| |
| @override |
| Future<void> get ready => _readyCompleter.future; |
| final _readyCompleter = Completer<void>(); |
| |
| /// The set of files that are known to exist recursively within the watched |
| /// directory. |
| /// |
| /// The state of files on the filesystem is compared against this to determine |
| /// the real change that occurred when working around issue 14373. This is |
| /// also used to emit REMOVE events when subdirectories are moved out of the |
| /// watched directory. |
| final PathSet _files; |
| |
| /// The subscription to the stream returned by [Directory.watch]. |
| /// |
| /// This is separate from [_listSubscriptions] because this stream |
| /// occasionally needs to be resubscribed in order to work around issue 14849. |
| StreamSubscription<List<FileSystemEvent>>? _watchSubscription; |
| |
| /// The subscription to the [Directory.list] call for the initial listing of |
| /// the directory to determine its initial state. |
| StreamSubscription<FileSystemEntity>? _initialListSubscription; |
| |
| /// The subscriptions to [Directory.list] calls for listing the contents of a |
| /// subdirectory that was moved into the watched directory. |
| final _listSubscriptions = <StreamSubscription<FileSystemEntity>>{}; |
| |
| /// The timer for tracking how long we wait for an initial batch of bogus |
| /// events (see issue 14373). |
| late Timer _bogusEventTimer; |
| |
| _MacOSDirectoryWatcher(this.path) : _files = PathSet(path) { |
| _startWatch(); |
| |
| // Before we're ready to emit events, wait for [_listDir] to complete and |
| // for enough time to elapse that if bogus events (issue 14373) would be |
| // emitted, they will be. |
| // |
| // If we do receive a batch of events, [_onBatch] will ensure that these |
| // futures don't fire and that the directory is re-listed. |
| Future.wait([_listDir(), _waitForBogusEvents()]).then((_) { |
| if (!isReady) { |
| _readyCompleter.complete(); |
| } |
| }); |
| } |
| |
| @override |
| void close() { |
| _watchSubscription?.cancel(); |
| _initialListSubscription?.cancel(); |
| _watchSubscription = null; |
| _initialListSubscription = null; |
| |
| for (var subscription in _listSubscriptions) { |
| subscription.cancel(); |
| } |
| _listSubscriptions.clear(); |
| |
| _eventsController.close(); |
| } |
| |
| /// The callback that's run when [Directory.watch] emits a batch of events. |
| void _onBatch(List<FileSystemEvent> batch) { |
| // If we get a batch of events before we're ready to begin emitting events, |
| // it's probable that it's a batch of pre-watcher events (see issue 14373). |
| // Ignore those events and re-list the directory. |
| if (!isReady) { |
| // Cancel the timer because bogus events only occur in the first batch, so |
| // we can fire [ready] as soon as we're done listing the directory. |
| _bogusEventTimer.cancel(); |
| _listDir().then((_) { |
| if (!isReady) { |
| _readyCompleter.complete(); |
| } |
| }); |
| return; |
| } |
| |
| _sortEvents(batch).forEach((path, eventSet) { |
| var canonicalEvent = _canonicalEvent(eventSet); |
| var events = canonicalEvent == null |
| ? _eventsBasedOnFileSystem(path) |
| : [canonicalEvent]; |
| |
| for (var event in events) { |
| if (event is FileSystemCreateEvent) { |
| if (!event.isDirectory) { |
| // If we already know about the file, treat it like a modification. |
| // This can happen if a file is copied on top of an existing one. |
| // We'll see an ADD event for the latter file when from the user's |
| // perspective, the file's contents just changed. |
| var type = |
| _files.contains(path) ? ChangeType.MODIFY : ChangeType.ADD; |
| |
| _emitEvent(type, path); |
| _files.add(path); |
| continue; |
| } |
| |
| if (_files.containsDir(path)) continue; |
| |
| var stream = Directory(path).list(recursive: true); |
| var subscription = stream.listen((entity) { |
| if (entity is Directory) return; |
| if (_files.contains(path)) return; |
| |
| _emitEvent(ChangeType.ADD, entity.path); |
| _files.add(entity.path); |
| }, cancelOnError: true); |
| subscription.onDone(() { |
| _listSubscriptions.remove(subscription); |
| }); |
| subscription.onError(_emitError); |
| _listSubscriptions.add(subscription); |
| } else if (event is FileSystemModifyEvent) { |
| assert(!event.isDirectory); |
| _emitEvent(ChangeType.MODIFY, path); |
| } else { |
| assert(event is FileSystemDeleteEvent); |
| for (var removedPath in _files.remove(path)) { |
| _emitEvent(ChangeType.REMOVE, removedPath); |
| } |
| } |
| } |
| }); |
| } |
| |
| /// Sort all the events in a batch into sets based on their path. |
| /// |
| /// A single input event may result in multiple events in the returned map; |
| /// for example, a MOVE event becomes a DELETE event for the source and a |
| /// CREATE event for the destination. |
| /// |
| /// The returned events won't contain any [FileSystemMoveEvent]s, nor will it |
| /// contain any events relating to [path]. |
| Map<String, Set<FileSystemEvent>> _sortEvents(List<FileSystemEvent> batch) { |
| var eventsForPaths = <String, Set<FileSystemEvent>>{}; |
| |
| // FSEvents can report past events, including events on the root directory |
| // such as it being created. We want to ignore these. If the directory is |
| // really deleted, that's handled by [_onDone]. |
| batch = batch.where((event) => event.path != path).toList(); |
| |
| // Events within directories that already have events are superfluous; the |
| // directory's full contents will be examined anyway, so we ignore such |
| // events. Emitting them could cause useless or out-of-order events. |
| var directories = unionAll(batch.map((event) { |
| if (!event.isDirectory) return <String>{}; |
| if (event is FileSystemMoveEvent) { |
| var destination = event.destination; |
| if (destination != null) { |
| return {event.path, destination}; |
| } |
| } |
| return {event.path}; |
| })); |
| |
| bool isInModifiedDirectory(String path) => |
| directories.any((dir) => path != dir && p.isWithin(dir, path)); |
| |
| void addEvent(String path, FileSystemEvent event) { |
| if (isInModifiedDirectory(path)) return; |
| eventsForPaths.putIfAbsent(path, () => <FileSystemEvent>{}).add(event); |
| } |
| |
| for (var event in batch) { |
| // The Mac OS watcher doesn't emit move events. See issue 14806. |
| assert(event is! FileSystemMoveEvent); |
| addEvent(event.path, event); |
| } |
| |
| return eventsForPaths; |
| } |
| |
| /// Returns the canonical event from a batch of events on the same path, if |
| /// one exists. |
| /// |
| /// If [batch] doesn't contain any contradictory events (e.g. DELETE and |
| /// CREATE, or events with different values for `isDirectory`), this returns a |
| /// single event that describes what happened to the path in question. |
| /// |
| /// If [batch] does contain contradictory events, this returns `null` to |
| /// indicate that the state of the path on the filesystem should be checked to |
| /// determine what occurred. |
| FileSystemEvent? _canonicalEvent(Set<FileSystemEvent> batch) { |
| // An empty batch indicates that we've learned earlier that the batch is |
| // contradictory (e.g. because of a move). |
| if (batch.isEmpty) return null; |
| |
| var type = batch.first.type; |
| var isDir = batch.first.isDirectory; |
| var hadModifyEvent = false; |
| |
| for (var event in batch.skip(1)) { |
| // If one event reports that the file is a directory and another event |
| // doesn't, that's a contradiction. |
| if (isDir != event.isDirectory) return null; |
| |
| // Modify events don't contradict either CREATE or REMOVE events. We can |
| // safely assume the file was modified after a CREATE or before the |
| // REMOVE; otherwise there will also be a REMOVE or CREATE event |
| // (respectively) that will be contradictory. |
| if (event is FileSystemModifyEvent) { |
| hadModifyEvent = true; |
| continue; |
| } |
| assert(event is FileSystemCreateEvent || event is FileSystemDeleteEvent); |
| |
| // If we previously thought this was a MODIFY, we now consider it to be a |
| // CREATE or REMOVE event. This is safe for the same reason as above. |
| if (type == FileSystemEvent.modify) { |
| type = event.type; |
| continue; |
| } |
| |
| // A CREATE event contradicts a REMOVE event and vice versa. |
| assert(type == FileSystemEvent.create || type == FileSystemEvent.delete); |
| if (type != event.type) return null; |
| } |
| |
| // If we got a CREATE event for a file we already knew about, that comes |
| // from FSEvents reporting an add that happened prior to the watch |
| // beginning. If we also received a MODIFY event, we want to report that, |
| // but not the CREATE. |
| if (type == FileSystemEvent.create && |
| hadModifyEvent && |
| _files.contains(batch.first.path)) { |
| type = FileSystemEvent.modify; |
| } |
| |
| switch (type) { |
| case FileSystemEvent.create: |
| // Issue 16003 means that a CREATE event for a directory can indicate |
| // that the directory was moved and then re-created. |
| // [_eventsBasedOnFileSystem] will handle this correctly by producing a |
| // DELETE event followed by a CREATE event if the directory exists. |
| if (isDir) return null; |
| return FileSystemCreateEvent(batch.first.path, false); |
| case FileSystemEvent.delete: |
| return FileSystemDeleteEvent(batch.first.path, isDir); |
| case FileSystemEvent.modify: |
| return FileSystemModifyEvent(batch.first.path, isDir, false); |
| default: |
| throw StateError('unreachable'); |
| } |
| } |
| |
| /// Returns one or more events that describe the change between the last known |
| /// state of [path] and its current state on the filesystem. |
| /// |
| /// This returns a list whose order should be reflected in the events emitted |
| /// to the user, unlike the batched events from [Directory.watch]. The |
| /// returned list may be empty, indicating that no changes occurred to [path] |
| /// (probably indicating that it was created and then immediately deleted). |
| List<FileSystemEvent> _eventsBasedOnFileSystem(String path) { |
| var fileExisted = _files.contains(path); |
| var dirExisted = _files.containsDir(path); |
| var fileExists = File(path).existsSync(); |
| var dirExists = Directory(path).existsSync(); |
| |
| var events = <FileSystemEvent>[]; |
| if (fileExisted) { |
| if (fileExists) { |
| events.add(FileSystemModifyEvent(path, false, false)); |
| } else { |
| events.add(FileSystemDeleteEvent(path, false)); |
| } |
| } else if (dirExisted) { |
| if (dirExists) { |
| // If we got contradictory events for a directory that used to exist and |
| // still exists, we need to rescan the whole thing in case it was |
| // replaced with a different directory. |
| events.add(FileSystemDeleteEvent(path, true)); |
| events.add(FileSystemCreateEvent(path, true)); |
| } else { |
| events.add(FileSystemDeleteEvent(path, true)); |
| } |
| } |
| |
| if (!fileExisted && fileExists) { |
| events.add(FileSystemCreateEvent(path, false)); |
| } else if (!dirExisted && dirExists) { |
| events.add(FileSystemCreateEvent(path, true)); |
| } |
| |
| return events; |
| } |
| |
| /// The callback that's run when the [Directory.watch] stream is closed. |
| void _onDone() { |
| _watchSubscription = null; |
| |
| // If the directory still exists and we're still expecting bogus events, |
| // this is probably issue 14849 rather than a real close event. We should |
| // just restart the watcher. |
| if (!isReady && Directory(path).existsSync()) { |
| _startWatch(); |
| return; |
| } |
| |
| // FSEvents can fail to report the contents of the directory being removed |
| // when the directory itself is removed, so we need to manually mark the |
| // files as removed. |
| for (var file in _files.paths) { |
| _emitEvent(ChangeType.REMOVE, file); |
| } |
| _files.clear(); |
| close(); |
| } |
| |
| /// Start or restart the underlying [Directory.watch] stream. |
| void _startWatch() { |
| // Batch the FSEvent changes together so that we can dedup events. |
| var innerStream = Directory(path).watch(recursive: true).batchEvents(); |
| _watchSubscription = innerStream.listen(_onBatch, |
| onError: _eventsController.addError, onDone: _onDone); |
| } |
| |
| /// Starts or restarts listing the watched directory to get an initial picture |
| /// of its state. |
| Future<void> _listDir() { |
| assert(!isReady); |
| _initialListSubscription?.cancel(); |
| |
| _files.clear(); |
| var completer = Completer<void>(); |
| var stream = Directory(path).list(recursive: true); |
| _initialListSubscription = stream.listen((entity) { |
| if (entity is! Directory) _files.add(entity.path); |
| }, onError: _emitError, onDone: completer.complete, cancelOnError: true); |
| return completer.future; |
| } |
| |
| /// Wait 200ms for a batch of bogus events (issue 14373) to come in. |
| /// |
| /// 200ms is short in terms of human interaction, but longer than any Mac OS |
| /// watcher tests take on the bots, so it should be safe to assume that any |
| /// bogus events will be signaled in that time frame. |
| Future<void> _waitForBogusEvents() { |
| var completer = Completer<void>(); |
| _bogusEventTimer = |
| Timer(const Duration(milliseconds: 200), completer.complete); |
| return completer.future; |
| } |
| |
| /// Emit an event with the given [type] and [path]. |
| void _emitEvent(ChangeType type, String path) { |
| if (!isReady) return; |
| _eventsController.add(WatchEvent(type, path)); |
| } |
| |
| /// Emit an error, then close the watcher. |
| void _emitError(Object error, StackTrace stackTrace) { |
| // Guarantee that ready always completes. |
| if (!isReady) { |
| _readyCompleter.complete(); |
| } |
| _eventsController.addError(error, stackTrace); |
| close(); |
| } |
| } |