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| 1 // Copyright (c) 2015, the Dart project authors. Please see the AUTHORS file | |
| 2 // for details. All rights reserved. Use of this source code is governed by a | |
| 3 // BSD-style license that can be found in the LICENSE file. | |
| 4 | |
| 5 library watcher.file_watcher.native; | |
| 6 | |
| 7 import 'dart:async'; | |
| 8 import 'dart:io'; | |
| 9 | |
| 10 import '../file_watcher.dart'; | |
| 11 import '../resubscribable.dart'; | |
| 12 import '../utils.dart'; | |
| 13 import '../watch_event.dart'; | |
| 14 | |
| 15 /// Uses the native file system notifications to watch for filesystem events. | |
| 16 /// | |
| 17 /// Single-file notifications are much simpler than those for multiple files, so | |
| 18 /// this doesn't need to be split out into multiple OS-specific classes. | |
| 19 class NativeFileWatcher extends ResubscribableWatcher implements FileWatcher { | |
| 20 NativeFileWatcher(String path) | |
| 21 : super(path, () => new _NativeFileWatcher(path)); | |
| 22 } | |
| 23 | |
| 24 class _NativeFileWatcher implements FileWatcher, ManuallyClosedWatcher { | |
| 25 final String path; | |
| 26 | |
| 27 Stream<WatchEvent> get events => _eventsController.stream; | |
| 28 final _eventsController = new StreamController<WatchEvent>.broadcast(); | |
| 29 | |
| 30 bool get isReady => _readyCompleter.isCompleted; | |
| 31 | |
| 32 Future get ready => _readyCompleter.future; | |
| 33 final _readyCompleter = new Completer(); | |
| 34 | |
| 35 StreamSubscription _subscription; | |
| 36 | |
| 37 _NativeFileWatcher(this.path) { | |
| 38 _listen(); | |
| 39 | |
| 40 // We don't need to do any initial set-up, so we're ready immediately after | |
| 41 // being listened to. | |
| 42 _readyCompleter.complete(); | |
| 43 } | |
| 44 | |
| 45 void _listen() { | |
| 46 // Batch the events together so that we can dedup them. | |
| 47 _subscription = new File(path).watch() | |
| 48 .transform(new BatchedStreamTransformer<FileSystemEvent>()) | |
| 49 .listen(_onBatch, onError: _eventsController.addError, onDone: _onDone); | |
| 50 } | |
| 51 | |
| 52 void _onBatch(List<FileSystemEvent> batch) { | |
| 53 if (batch.any((event) => event.type == FileSystemEvent.DELETE)) { | |
| 54 // If the file is deleted, the underlying stream will close. We handle | |
| 55 // emitting our own REMOVE event in [_onDone]. | |
| 56 return; | |
| 57 } | |
| 58 | |
| 59 _eventsController.add(new WatchEvent(ChangeType.MODIFY, path)); | |
| 60 } | |
| 61 | |
| 62 _onDone() async { | |
| 63 var fileExists = await new File(path).exists(); | |
| 64 | |
| 65 // Check for this after checking whether the file exists because it's | |
| 66 // possible that [close] was called between [File.exists] being called and | |
| 67 // it completing. | |
| 68 if (_eventsController.isClosed) return; | |
| 69 | |
| 70 if (fileExists) { | |
| 71 // If the file exists now, it was probably removed and quickly replaced; | |
| 72 // this can happen for example when another file is moved on top of it. | |
| 73 // Re-subscribe and report a modify event. | |
| 74 _eventsController.add(new WatchEvent(ChangeType.MODIFY, path)); | |
| 75 _listen(); | |
| 76 } else { | |
| 77 _eventsController.add(new WatchEvent(ChangeType.REMOVE, path)); | |
| 78 close(); | |
| 79 } | |
| 80 } | |
| 81 | |
| 82 void close() { | |
| 83 if (_subscription != null) _subscription.cancel(); | |
| 84 _subscription = null; | |
| 85 _eventsController.close(); | |
| 86 } | |
| 87 } | |
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