Chromium Code Reviews
chromiumcodereview-hr@appspot.gserviceaccount.com (chromiumcodereview-hr) | Please choose your nickname with Settings | Help | Chromium Project | Gerrit Changes | Sign out
(371)

Unified Diff: lib/src/guarantee_channel.dart

Issue 1662773003: Add StreamChannel.withGuarantees and StreamChannelController. (Closed) Base URL: git@github.com:dart-lang/stream_channel.git@master
Patch Set: Code review changes Created 4 years, 11 months ago
Use n/p to move between diff chunks; N/P to move between comments. Draft comments are only viewable by you.
Jump to:
View side-by-side diff with in-line comments
Download patch
« no previous file with comments | « CHANGELOG.md ('k') | lib/src/stream_channel_controller.dart » ('j') | no next file with comments »
Expand Comments ('e') | Collapse Comments ('c') | Show Comments Hide Comments ('s')
Index: lib/src/guarantee_channel.dart
diff --git a/lib/src/guarantee_channel.dart b/lib/src/guarantee_channel.dart
new file mode 100644
index 0000000000000000000000000000000000000000..849cc2ffe74edc22e0ff79afe65749e0f5636af3
--- /dev/null
+++ b/lib/src/guarantee_channel.dart
@@ -0,0 +1,163 @@
+// Copyright (c) 2016, 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 'package:async/async.dart';
+
+import '../stream_channel.dart';
+
+/// A [StreamChannel] that enforces the stream channel guarantees.
+///
+/// This is exposed via [new StreamChannel.withGuarantees].
+class GuaranteeChannel<T> extends StreamChannelMixin<T> {
+ Stream<T> get stream => _streamController.stream;
+
+ StreamSink<T> get sink => _sink;
+ _GuaranteeSink<T> _sink;
+
+ /// The controller for [stream].
+ ///
+ /// This intermediate controller allows us to continue listening for a done
+ /// event even after the user has canceled their subscription, and to send our
+ /// own done event when the sink is closed.
+ StreamController<T> _streamController;
+
+ /// The subscription to the inner stream.
+ StreamSubscription<T> _subscription;
+
+ /// Whether the sink has closed, causing the underlying channel to disconnect.
+ bool _disconnected = false;
+
+ GuaranteeChannel(Stream<T> innerStream, StreamSink<T> innerSink) {
+ _sink = new _GuaranteeSink<T>(innerSink, this);
+
+ // Enforce the single-subscription guarantee by changing a broadcast stream
+ // to single-subscription.
+ if (innerStream.isBroadcast) {
+ innerStream = innerStream.transform(
+ const SingleSubscriptionTransformer());
+ }
+
+ _streamController = new StreamController<T>(onListen: () {
+ // If the sink has disconnected, we've already called
+ // [_streamController.close].
+ if (_disconnected) return;
+
+ _subscription = innerStream.listen(_streamController.add,
+ onError: _streamController.addError,
+ onDone: () {
+ _sink._onStreamDisconnected();
+ _streamController.close();
+ });
+ }, sync: true);
+ }
+
+ /// Called by [_GuaranteeSink] when the user closes it.
+ ///
+ /// The sink closing indicates that the connection is closed, so the stream
+ /// should stop emitting events.
+ void _onSinkDisconnected() {
+ _disconnected = true;
+ if (_subscription != null) _subscription.cancel();
+ _streamController.close();
+ }
+}
+
+/// The sink for [GuaranteeChannel].
+///
+/// This wraps the inner sink to ignore events and cancel any in-progress
+/// [addStream] calls when the underlying channel closes.
+class _GuaranteeSink<T> implements StreamSink<T> {
+ /// The inner sink being wrapped.
+ final StreamSink<T> _inner;
+
+ /// The [GuaranteeChannel] this belongs to.
+ final GuaranteeChannel<T> _channel;
+
+ Future get done => _inner.done;
+
+ /// Whether the stream has emitted a done event, causing the underlying
+ /// channel to disconnect.
+ bool _disconnected = false;
+
+ /// Whether the user has called [close].
+ bool _closed = false;
+
+ /// The subscription to the stream passed to [addStream], if a stream is
+ /// currently being added.
+ StreamSubscription<T> _addStreamSubscription;
+
+ /// The completer for the future returned by [addStream], if a stream is
+ /// currently being added.
+ Completer _addStreamCompleter;
+
+ /// Whether we're currently adding a stream with [addStream].
+ bool get _inAddStream => _addStreamSubscription != null;
+
+ _GuaranteeSink(this._inner, this._channel);
+
+ void add(T data) {
+ if (_closed) throw new StateError("Cannot add event after closing.");
+ if (_inAddStream) {
+ throw new StateError("Cannot add event while adding stream.");
+ }
+ if (_disconnected) return;
+
+ _inner.add(data);
+ }
+
+ void addError(error, [StackTrace stackTrace]) {
+ if (_closed) throw new StateError("Cannot add event after closing.");
+ if (_inAddStream) {
+ throw new StateError("Cannot add event while adding stream.");
+ }
+ if (_disconnected) return;
+
+ _inner.addError(error, stackTrace);
+ }
+
+ Future addStream(Stream<T> stream) {
+ if (_closed) throw new StateError("Cannot add stream after closing.");
+ if (_inAddStream) {
+ throw new StateError("Cannot add stream while adding stream.");
+ }
+ if (_disconnected) return new Future.value();
+
+ _addStreamCompleter = new Completer.sync();
+ _addStreamSubscription = stream.listen(
+ _inner.add,
+ onError: _inner.addError,
+ onDone: _addStreamCompleter.complete);
+ return _addStreamCompleter.future.then((_) {
+ _addStreamCompleter = null;
+ _addStreamSubscription = null;
+ });
+ }
+
+ Future close() {
+ if (_inAddStream) {
+ throw new StateError("Cannot close sink while adding stream.");
+ }
+
+ _closed = true;
+ if (_disconnected) return new Future.value();
+
+ _channel._onSinkDisconnected();
+ return _inner.close();
+ }
+
+ /// Called by [GuaranteeChannel] when the stream emits a done event.
+ ///
+ /// The stream being done indicates that the connection is closed, so the
+ /// sink should stop forwarding events.
+ void _onStreamDisconnected() {
+ _disconnected = true;
+ if (!_inAddStream) return;
+
+ _addStreamCompleter.complete(_addStreamSubscription.cancel());
+ _addStreamCompleter = null;
+ _addStreamSubscription = null;
+ }
+}
« no previous file with comments | « CHANGELOG.md ('k') | lib/src/stream_channel_controller.dart » ('j') | no next file with comments »

Powered by Google App Engine
This is Rietveld 408576698