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| 1 // Copyright (c) 2013, 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 glob.stream_pool; | |
| 6 | |
| 7 import 'dart:async'; | |
| 8 | |
| 9 /// A pool of streams whose events are unified and emitted through a central | |
| 10 /// stream. | |
| 11 class StreamPool<T> { | |
| 12 /// The stream through which all events from streams in the pool are emitted. | |
| 13 Stream<T> get stream => _controller.stream; | |
| 14 final StreamController<T> _controller; | |
| 15 | |
| 16 /// Subscriptions to the streams that make up the pool. | |
| 17 final _subscriptions = new Map<Stream<T>, StreamSubscription<T>>(); | |
| 18 | |
| 19 /// Whether this pool should be closed when it becomes empty. | |
| 20 bool _closeWhenEmpty = false; | |
| 21 | |
| 22 /// Creates a new stream pool that only supports a single subscriber. | |
| 23 /// | |
| 24 /// Any events from broadcast streams in the pool will be buffered until a | |
| 25 /// listener is subscribed. | |
| 26 StreamPool() | |
| 27 // Create the controller as sync so that any sync input streams will be | |
| 28 // forwarded synchronously. Async input streams will have their asynchrony | |
| 29 // preserved, since _controller.add will be called asynchronously. | |
| 30 : _controller = new StreamController<T>(sync: true); | |
| 31 | |
| 32 /// Creates a new stream pool where [stream] can be listened to more than | |
| 33 /// once. | |
| 34 /// | |
| 35 /// Any events from buffered streams in the pool will be emitted immediately, | |
| 36 /// regardless of whether [stream] has any subscribers. | |
| 37 StreamPool.broadcast() | |
| 38 // Create the controller as sync so that any sync input streams will be | |
| 39 // forwarded synchronously. Async input streams will have their asynchrony | |
| 40 // preserved, since _controller.add will be called asynchronously. | |
| 41 : _controller = new StreamController<T>.broadcast(sync: true); | |
| 42 | |
| 43 /// Adds [stream] as a member of this pool. | |
| 44 /// | |
| 45 /// Any events from [stream] will be emitted through [this.stream]. If | |
| 46 /// [stream] is sync, they'll be emitted synchronously; if [stream] is async, | |
| 47 /// they'll be emitted asynchronously. | |
| 48 void add(Stream<T> stream) { | |
| 49 if (_subscriptions.containsKey(stream)) return; | |
| 50 _subscriptions[stream] = stream.listen(_controller.add, | |
| 51 onError: _controller.addError, | |
| 52 onDone: () => remove(stream)); | |
| 53 } | |
| 54 | |
| 55 /// Removes [stream] as a member of this pool. | |
| 56 void remove(Stream<T> stream) { | |
| 57 var subscription = _subscriptions.remove(stream); | |
| 58 if (subscription != null) subscription.cancel(); | |
| 59 if (_closeWhenEmpty && _subscriptions.isEmpty) close(); | |
| 60 } | |
| 61 | |
| 62 /// Removes all streams from this pool and closes [stream]. | |
| 63 void close() { | |
| 64 for (var subscription in _subscriptions.values) { | |
| 65 subscription.cancel(); | |
| 66 } | |
| 67 _subscriptions.clear(); | |
| 68 _controller.close(); | |
| 69 } | |
| 70 | |
| 71 /// The next time this pool becomes empty, close it. | |
| 72 void closeWhenEmpty() { | |
| 73 if (_subscriptions.isEmpty) close(); | |
| 74 _closeWhenEmpty = true; | |
| 75 } | |
| 76 } | |
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Chromium Code Reviews
Issue 1400473008:
Roll Observatory packages and add a roll script (Closed)
Base URL: git@github.com:dart-lang/observatory_pub_packages.git@master