blob: db9ca83286e922191f8283b7447d33e4d00657f2 [file] [log] [blame]
// Copyright (c) 2014, 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.
// TODO(rnystrom): Merge with mac_os version.
import 'dart:async';
import 'dart:collection';
import 'dart:io';
import 'package:path/path.dart' as p;
import '../constructable_file_system_event.dart';
import '../directory_watcher.dart';
import '../path_set.dart';
import '../resubscribable.dart';
import '../utils.dart';
import '../watch_event.dart';
class WindowsDirectoryWatcher extends ResubscribableWatcher
implements DirectoryWatcher {
String get directory => path;
WindowsDirectoryWatcher(String directory)
: super(directory, () => new _WindowsDirectoryWatcher(directory));
class _EventBatcher {
static const Duration _BATCH_DELAY = const Duration(milliseconds: 100);
final List<FileSystemEvent> events = [];
Timer timer;
void addEvent(FileSystemEvent event, void callback()) {
if (timer != null) {
timer = new Timer(_BATCH_DELAY, callback);
void cancelTimer() {
class _WindowsDirectoryWatcher
implements DirectoryWatcher, ManuallyClosedWatcher {
String get directory => path;
final String path;
Stream<WatchEvent> get events =>;
final _eventsController = new StreamController<WatchEvent>.broadcast();
bool get isReady => _readyCompleter.isCompleted;
Future get ready => _readyCompleter.future;
final _readyCompleter = new Completer();
final Map<String, _EventBatcher> _eventBatchers =
new HashMap<String, _EventBatcher>();
/// 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. 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 [].
StreamSubscription<FileSystemEvent> _watchSubscription;
/// The subscription to the stream returned by [] of the
/// parent directory to [directory]. This is needed to detect changes to
/// [directory], as they are not included on Windows.
StreamSubscription<FileSystemEvent> _parentWatchSubscription;
/// 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 the [Directory.list] calls for listing the contents
/// of subdirectories that were moved into the watched directory.
final Set<StreamSubscription<FileSystemEntity>> _listSubscriptions =
new HashSet<StreamSubscription<FileSystemEntity>>();
_WindowsDirectoryWatcher(String path)
: path = path,
_files = new PathSet(path) {
// Before we're ready to emit events, wait for [_listDir] to complete.
_listDir().then((_) {
void close() {
if (_watchSubscription != null) _watchSubscription.cancel();
if (_parentWatchSubscription != null) _parentWatchSubscription.cancel();
if (_initialListSubscription != null) _initialListSubscription.cancel();
for (var sub in _listSubscriptions) {
for (var batcher in _eventBatchers.values) {
_watchSubscription = null;
_parentWatchSubscription = null;
_initialListSubscription = null;
/// On Windows, if [directory] is deleted, we will not receive any event.
/// Instead, we add a watcher on the parent folder (if any), that can notify
/// us about [path]. This also includes events such as moves.
void _startParentWatcher() {
var absoluteDir = p.absolute(path);
var parent = p.dirname(absoluteDir);
// Check if [path] is already the root directory.
if (FileSystemEntity.identicalSync(parent, path)) return;
var parentStream = new Directory(parent).watch(recursive: false);
_parentWatchSubscription = parentStream.listen((event) {
// Only look at events for 'directory'.
if (p.basename(event.path) != p.basename(absoluteDir)) return;
// Test if the directory is removed. FileSystemEntity.typeSync will
// return NOT_FOUND if it's unable to decide upon the type, including
// access denied issues, which may happen when the directory is deleted.
// FileSystemMoveEvent and FileSystemDeleteEvent events will always mean
// the directory is now gone.
if (event is FileSystemMoveEvent ||
event is FileSystemDeleteEvent ||
(FileSystemEntity.typeSync(path) == FileSystemEntityType.NOT_FOUND)) {
for (var path in _files.paths) {
_emitEvent(ChangeType.REMOVE, path);
}, onError: (error) {
// Ignore errors, simply close the stream. The user listens on
// [directory], and while it can fail to listen on the parent, we may
// still be able to listen on the path requested.
_parentWatchSubscription = null;
void _onEvent(FileSystemEvent event) {
final batcher =
_eventBatchers.putIfAbsent(event.path, () => new _EventBatcher());
batcher.addEvent(event, () {
/// The callback that's run when [] emits a batch of events.
void _onBatch(List<FileSystemEvent> batch) {
_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 (_files.contains(path)) continue;
_emitEvent(ChangeType.ADD, path);
if (_files.containsDir(path)) continue;
var stream = new Directory(path).list(recursive: true);
StreamSubscription<FileSystemEntity> subscription;
subscription = stream.listen((entity) {
if (entity is Directory) return;
if (_files.contains(path)) return;
_emitEvent(ChangeType.ADD, entity.path);
}, onDone: () {
}, onError: (e, stackTrace) {
_emitError(e, stackTrace);
}, cancelOnError: true);
} else if (event is FileSystemModifyEvent) {
if (!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>>{};
// 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( {
if (!event.isDirectory) return new Set<String>();
if (event is FileSystemMoveEvent) {
return new Set<String>.from([event.path, event.destination]);
return new Set<String>.from([event.path]);
isInModifiedDirectory(String path) =>
directories.any((dir) => path != dir && path.startsWith(dir));
addEvent(String path, FileSystemEvent event) {
if (isInModifiedDirectory(path)) return;
.putIfAbsent(path, () => new Set<FileSystemEvent>())
for (var event in batch) {
if (event is FileSystemMoveEvent) {
addEvent(event.destination, event);
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;
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 ||
event is FileSystemMoveEvent);
// 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;
// A CREATE event contradicts a REMOVE event and vice versa.
assert(type == FileSystemEvent.CREATE ||
type == FileSystemEvent.DELETE ||
type == FileSystemEvent.MOVE);
if (type != event.type) return null;
switch (type) {
case FileSystemEvent.CREATE:
return new ConstructableFileSystemCreateEvent(batch.first.path, isDir);
case FileSystemEvent.DELETE:
return new ConstructableFileSystemDeleteEvent(batch.first.path, isDir);
case FileSystemEvent.MODIFY:
return new ConstructableFileSystemModifyEvent(
batch.first.path, isDir, false);
case FileSystemEvent.MOVE:
return null;
throw '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 []. 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 = <FileSystemEvent>[];
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 [] stream is closed.
/// Note that this is unlikely to happen on Windows, unless the system itself
/// closes the handle.
void _onDone() {
_watchSubscription = null;
// Emit remove events for any remaining files.
for (var file in _files.paths) {
_emitEvent(ChangeType.REMOVE, file);
/// Start or restart the underlying [] stream.
void _startWatch() {
// Batch the events together so that we can dedup events.
var innerStream = new Directory(path).watch(recursive: true);
_watchSubscription = innerStream.listen(_onEvent,
onError: _eventsController.addError, onDone: _onDone);
/// Starts or restarts listing the watched directory to get an initial picture
/// of its state.
Future _listDir() {
if (_initialListSubscription != null) _initialListSubscription.cancel();
var completer = new Completer();
var stream = new Directory(path).list(recursive: true);
void handleEntity(entity) {
if (entity is! Directory) _files.add(entity.path);
_initialListSubscription = stream.listen(handleEntity,
onError: _emitError, onDone: completer.complete, cancelOnError: true);
return completer.future;
/// Emit an event with the given [type] and [path].
void _emitEvent(ChangeType type, String path) {
if (!isReady) return;
_eventsController.add(new WatchEvent(type, path));
/// Emit an error, then close the watcher.
void _emitError(error, StackTrace stackTrace) {
_eventsController.addError(error, stackTrace);