| // 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. |
| |
| library watcher.directory_watcher.mac_os; |
| |
| import 'dart:async'; |
| import 'dart:io'; |
| |
| import '../constructable_file_system_event.dart'; |
| import '../path_set.dart'; |
| import '../utils.dart'; |
| import '../watch_event.dart'; |
| import 'resubscribable.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 14793, 14806, and 14849 in the implementation |
| /// of [Directory.watch]. |
| class MacOSDirectoryWatcher extends ResubscribableDirectoryWatcher { |
| MacOSDirectoryWatcher(String directory) |
| : super(directory, () => new _MacOSDirectoryWatcher(directory)); |
| } |
| |
| class _MacOSDirectoryWatcher implements ManuallyClosedDirectoryWatcher { |
| final String directory; |
| |
| Stream<WatchEvent> get events => _eventsController.stream; |
| final _eventsController = new StreamController<WatchEvent>.broadcast(); |
| |
| bool get isReady => _readyCompleter.isCompleted; |
| |
| Future get ready => _readyCompleter.future; |
| final _readyCompleter = new Completer(); |
| |
| /// The number of event batches that have been received from |
| /// [Directory.watch]. |
| /// |
| /// This is used to determine if the [Directory.watch] stream was falsely |
| /// closed due to issue 14849. A close caused by events in the past will only |
| /// happen before or immediately after the first batch of events. |
| int batches = 0; |
| |
| /// 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 [_subscriptions] because this stream occasionally |
| /// needs to be resubscribed in order to work around issue 14849. |
| StreamSubscription<FileSystemEvent> _watchSubscription; |
| |
| /// A set of subscriptions that this watcher subscribes to. |
| /// |
| /// These are gathered together so that they may all be canceled when the |
| /// watcher is closed. This does not include [_watchSubscription]. |
| final _subscriptions = new Set<StreamSubscription>(); |
| |
| _MacOSDirectoryWatcher(String directory) |
| : directory = directory, |
| _files = new PathSet(directory) { |
| _startWatch(); |
| |
| _listen(new Directory(directory).list(recursive: true), |
| (entity) { |
| if (entity is! Directory) _files.add(entity.path); |
| }, |
| onError: _emitError, |
| onDone: _readyCompleter.complete, |
| cancelOnError: true); |
| } |
| |
| void close() { |
| for (var subscription in _subscriptions) { |
| subscription.cancel(); |
| } |
| _subscriptions.clear(); |
| if (_watchSubscription != null) _watchSubscription.cancel(); |
| _watchSubscription = null; |
| _eventsController.close(); |
| } |
| |
| /// The callback that's run when [Directory.watch] emits a batch of events. |
| void _onBatch(List<FileSystemEvent> batch) { |
| batches++; |
| |
| _sortEvents(batch).forEach((path, events) { |
| var canonicalEvent = _canonicalEvent(events); |
| events = canonicalEvent == null ? |
| _eventsBasedOnFileSystem(path) : [canonicalEvent]; |
| |
| for (var event in events) { |
| if (event is FileSystemCreateEvent) { |
| if (!event.isDirectory) { |
| _emitEvent(ChangeType.ADD, path); |
| _files.add(path); |
| continue; |
| } |
| |
| _listen(new Directory(path).list(recursive: true), (entity) { |
| if (entity is Directory) return; |
| _emitEvent(ChangeType.ADD, entity.path); |
| _files.add(entity.path); |
| }, onError: _emitError, cancelOnError: true); |
| } 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 [directory]. |
| Map<String, Set<FileSystemEvent>> _sortEvents(List<FileSystemEvent> batch) { |
| var eventsForPaths = {}; |
| |
| // 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 != directory).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 new Set(); |
| if (event is! FileSystemMoveEvent) return new Set.from([event.path]); |
| return new Set.from([event.path, event.destination]); |
| })); |
| |
| isInModifiedDirectory(path) => |
| directories.any((dir) => path != dir && path.startsWith(dir)); |
| |
| addEvent(path, event) { |
| if (isInModifiedDirectory(path)) return; |
| var set = eventsForPaths.putIfAbsent(path, () => new Set()); |
| set.add(event); |
| } |
| |
| for (var event in batch.where((event) => event is! FileSystemMoveEvent)) { |
| addEvent(event.path, event); |
| } |
| |
| // Issue 14806 means that move events can be misleading if they're in the |
| // same batch as another modification of a related file. If they are, we |
| // make the event set empty to ensure we check the state of the filesystem. |
| // Otherwise, treat them as a DELETE followed by an ADD. |
| for (var event in batch.where((event) => event is FileSystemMoveEvent)) { |
| if (eventsForPaths.containsKey(event.path) || |
| eventsForPaths.containsKey(event.destination)) { |
| |
| if (!isInModifiedDirectory(event.path)) { |
| eventsForPaths[event.path] = new Set(); |
| } |
| if (!isInModifiedDirectory(event.destination)) { |
| eventsForPaths[event.destination] = new Set(); |
| } |
| |
| continue; |
| } |
| |
| addEvent(event.path, new ConstructableFileSystemDeleteEvent( |
| event.path, event.isDirectory)); |
| addEvent(event.destination, new ConstructableFileSystemCreateEvent( |
| event.path, event.isDirectory)); |
| } |
| |
| 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; |
| |
| 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) 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; |
| } |
| |
| switch (type) { |
| case FileSystemEvent.CREATE: |
| // Issue 14793 means that CREATE events can actually mean DELETE, so we |
| // should always check the filesystem for them. |
| return null; |
| case FileSystemEvent.DELETE: |
| return new ConstructableFileSystemDeleteEvent(batch.first.path, isDir); |
| case FileSystemEvent.MODIFY: |
| return new ConstructableFileSystemModifyEvent( |
| batch.first.path, isDir, false); |
| default: assert(false); |
| } |
| } |
| |
| /// 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 = new File(path).existsSync(); |
| var dirExists = new Directory(path).existsSync(); |
| |
| var events = []; |
| if (fileExisted) { |
| if (fileExists) { |
| events.add(new ConstructableFileSystemModifyEvent(path, false, false)); |
| } else { |
| events.add(new ConstructableFileSystemDeleteEvent(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(new ConstructableFileSystemDeleteEvent(path, true)); |
| events.add(new ConstructableFileSystemCreateEvent(path, true)); |
| } else { |
| events.add(new ConstructableFileSystemDeleteEvent(path, true)); |
| } |
| } |
| |
| if (!fileExisted && fileExists) { |
| events.add(new ConstructableFileSystemCreateEvent(path, false)); |
| } else if (!dirExisted && dirExists) { |
| events.add(new ConstructableFileSystemCreateEvent(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 haven't seen more than one batch, |
| // this is probably issue 14849 rather than a real close event. We should |
| // just restart the watcher. |
| if (batches < 2 && new Directory(directory).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 as |
| // removed. |
| for (var file in _files.toSet()) { |
| _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 = new Directory(directory).watch(recursive: true).transform( |
| new BatchedStreamTransformer<FileSystemEvent>()); |
| _watchSubscription = innerStream.listen(_onBatch, |
| onError: _eventsController.addError, |
| onDone: _onDone); |
| } |
| |
| /// Emit an event with the given [type] and [path]. |
| void _emitEvent(ChangeType type, String path) { |
| if (!isReady) return; |
| |
| // Don't emit ADD events for files that we already know about. Such an event |
| // probably comes from FSEvents reporting an add that happened prior to the |
| // watch beginning. |
| if (type == ChangeType.ADD && _files.contains(path)) return; |
| |
| _eventsController.add(new WatchEvent(type, path)); |
| } |
| |
| /// Emit an error, then close the watcher. |
| void _emitError(error, StackTrace stackTrace) { |
| _eventsController.addError(error, stackTrace); |
| close(); |
| } |
| |
| /// Like [Stream.listen], but automatically adds the subscription to |
| /// [_subscriptions] so that it can be canceled when [close] is called. |
| void _listen(Stream stream, void onData(event), {Function onError, |
| void onDone(), bool cancelOnError}) { |
| var subscription; |
| subscription = stream.listen(onData, onError: onError, onDone: () { |
| _subscriptions.remove(subscription); |
| if (onDone != null) onDone(); |
| }, cancelOnError: cancelOnError); |
| _subscriptions.add(subscription); |
| } |
| } |