Add observatory_pub_packages snapshot to third_party

observatory_pub_packages/barback/src/graph/package_graph.dart

+// 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 barback.graph.package_graph;
+
+import 'dart:async';
+import 'dart:collection';
+
+import '../asset/asset_id.dart';
+import '../asset/asset_node.dart';
+import '../asset/asset_set.dart';
+import '../build_result.dart';
+import '../errors.dart';
+import '../log.dart';
+import '../package_provider.dart';
+import '../utils.dart';
+import 'asset_cascade.dart';
+import 'node_status.dart';
+import 'static_asset_cascade.dart';
+
+/// The collection of [AssetCascade]s for an entire application.
+///
+/// This tracks each package's [AssetCascade] and routes asset requests between
+/// them.
+class PackageGraph {
+  /// The provider that exposes asset and package information.
+  final PackageProvider provider;
+
+  /// The [AssetCascade] for each package.
+  final _cascades = <String, AssetCascade>{};
+
+  /// A stream that emits a [BuildResult] each time the build is completed,
+  /// whether or not it succeeded.
+  ///
+  /// This will emit a result only once every package's [AssetCascade] has
+  /// finished building.
+  ///
+  /// If an unexpected error in barback itself occurs, it will be emitted
+  /// through this stream's error channel.
+  Stream<BuildResult> get results => _resultsController.stream;
+  final _resultsController =
+      new StreamController<BuildResult>.broadcast(sync: true);
+
+  /// A stream that emits any errors from the graph or the transformers.
+  ///
+  /// This emits errors as they're detected. If an error occurs in one part of
+  /// the graph, unrelated parts will continue building.
+  ///
+  /// This will not emit programming errors from barback itself. Those will be
+  /// emitted through the [results] stream's error channel.
+  Stream<BarbackException> get errors => _errors;
+  Stream<BarbackException> _errors;
+
+  /// The stream of [LogEntry] objects used to report transformer log entries.
+  Stream<LogEntry> get log => _logController.stream;
+  final _logController = new StreamController<LogEntry>.broadcast(sync: true);
+
+  /// How far along [this] is in processing its assets.
+  NodeStatus get _status => NodeStatus.dirtiest(
+      _cascades.values.map((cascade) => cascade.status));
+
+  /// Whether a [BuildResult] is scheduled to be emitted on [results] (see
+  /// [_tryScheduleResult]).
+  bool _resultScheduled = false;
+
+  /// The most recent [BuildResult] emitted on [results].
+  BuildResult _lastResult;
+
+  // TODO(nweiz): This can have bogus errors if an error is created and resolved
+  // in the space of one build.
+  /// The errors that have occurred since the current build started.
+  ///
+  /// This will be empty if no build is occurring.
+  final _accumulatedErrors = new Queue<BarbackException>();
+
+  /// The most recent error emitted from a cascade's result stream.
+  ///
+  /// This is used to pipe an unexpected error from a build to the resulting
+  /// [Future] returned by [getAllAssets].
+  var _lastUnexpectedError;
+
+  /// The stack trace for [_lastUnexpectedError].
+  StackTrace _lastUnexpectedErrorTrace;
+
+  /// Creates a new [PackageGraph] that will transform assets in all packages
+  /// made available by [provider].
+  PackageGraph(this.provider) {
+    _inErrorZone(() {
+      for (var package in provider.packages) {
+        var cascade = new AssetCascade(this, package);
+        _cascades[package] = cascade;
+        cascade.onLog.listen(_onLog);
+        cascade.onStatusChange.listen((status) {
+          if (status == NodeStatus.IDLE) _tryScheduleResult();
+        });
+      }
+
+      if (provider is StaticPackageProvider) {
+        StaticPackageProvider staticProvider = provider;
+        for (var package in staticProvider.staticPackages) {
+          if (_cascades.containsKey(package)) {
+            throw new StateError('Package "$package" is in both '
+                'PackageProvider.packages and PackageProvider.staticPackages.');
+          }
+
+          var cascade = new StaticAssetCascade(this, package);
+          _cascades[package] = cascade;
+        }
+      }
+
+      _errors = mergeStreams(_cascades.values.map((cascade) => cascade.errors),
+          broadcast: true);
+      _errors.listen(_accumulatedErrors.add);
+
+      // Make sure a result gets scheduled even if there are no cascades or all
+      // of them are static.
+      if (provider.packages.isEmpty) _tryScheduleResult();
+    });
+  }
+
+  /// Gets the asset node identified by [id].
+  ///
+  /// If [id] is for a generated or transformed asset, this will wait until it
+  /// has been created and return it. This means that the returned asset will
+  /// always be [AssetState.AVAILABLE].
+  ///
+  /// If the asset cannot be found, returns null.
+  Future<AssetNode> getAssetNode(AssetId id) {
+    return _inErrorZone(() {
+      var cascade = _cascades[id.package];
+      if (cascade != null) return cascade.getAssetNode(id);
+      return new Future.value(null);
+    });
+  }
+
+  /// Gets all output assets.
+  ///
+  /// If a build is currently in progress, waits until it completes. The
+  /// returned future will complete with an error if the build is not
+  /// successful.
+  ///
+  /// Any transforms using [LazyTransformer]s will be forced to generate
+  /// concrete outputs, and those outputs will be returned.
+  Future<AssetSet> getAllAssets() {
+    for (var cascade in _cascades.values) {
+      _inErrorZone(() => cascade.forceAllTransforms());
+    }
+
+    if (_status != NodeStatus.IDLE) {
+      // A build is still ongoing, so wait for it to complete and try again.
+      return results.first.then((_) => getAllAssets());
+    }
+
+    // If an unexpected error occurred, complete with that.
+    if (_lastUnexpectedError != null) {
+      var error = _lastUnexpectedError;
+      _lastUnexpectedError = null;
+      return new Future.error(error, _lastUnexpectedErrorTrace);
+    }
+
+    // If the last build completed with an error, complete the future with it.
+    if (!_lastResult.succeeded) {
+      return new Future.error(BarbackException.aggregate(_lastResult.errors));
+    }
+
+    // Otherwise, return all of the final output assets.
+    return Future.wait(_cascades.values.map(
+            (cascade) => cascade.availableOutputs))
+          .then((assetSets) {
+      var assets = unionAll(assetSets.map((assetSet) => assetSet.toSet()));
+      return new Future.value(new AssetSet.from(assets));
+    });
+  }
+
+  /// Adds [sources] to the graph's known set of source assets.
+  ///
+  /// Begins applying any transforms that can consume any of the sources. If a
+  /// given source is already known, it is considered modified and all
+  /// transforms that use it will be re-applied.
+  void updateSources(Iterable<AssetId> sources) {
+    groupBy(sources, (id) => id.package).forEach((package, ids) {
+      var cascade = _cascades[package];
+      if (cascade == null) throw new ArgumentError("Unknown package $package.");
+      _inErrorZone(() => cascade.updateSources(ids));
+    });
+
+    // It's possible for adding sources not to cause any processing. The user
+    // still expects there to be a build, though, so we emit one immediately.
+    _tryScheduleResult();
+  }
+
+  /// Removes [removed] from the graph's known set of source assets.
+  void removeSources(Iterable<AssetId> sources) {
+    groupBy(sources, (id) => id.package).forEach((package, ids) {
+      var cascade = _cascades[package];
+      if (cascade == null) throw new ArgumentError("Unknown package $package.");
+      _inErrorZone(() => cascade.removeSources(ids));
+    });
+
+    // It's possible for removing sources not to cause any processing. The user
+    // still expects there to be a build, though, so we emit one immediately.
+    _tryScheduleResult();
+  }
+
+  void updateTransformers(String package, Iterable<Iterable> transformers) {
+    _inErrorZone(() => _cascades[package].updateTransformers(transformers));
+
+    // It's possible for updating transformers not to cause any processing. The
+    // user still expects there to be a build, though, so we emit one
+    // immediately.
+    _tryScheduleResult();
+  }
+
+  /// A handler for a log entry from an [AssetCascade].
+  void _onLog(LogEntry entry) {
+    if (entry.level == LogLevel.ERROR) {
+      // TODO(nweiz): keep track of stack chain.
+      _accumulatedErrors.add(
+          new TransformerException(entry.transform, entry.message, null));
+    }
+
+    if (_logController.hasListener) {
+      _logController.add(entry);
+    } else if (entry.level != LogLevel.FINE) {
+      // No listeners, so just print entry.
+      var buffer = new StringBuffer();
+      buffer.write("[${entry.level} ${entry.transform}] ");
+
+      if (entry.span != null) {
+        buffer.write(entry.span.message(entry.message));
+      } else {
+        buffer.write(entry.message);
+      }
+
+      print(buffer);
+    }
+  }
+
+  /// If [this] is done processing, schedule a [BuildResult] to be emitted on
+  /// [results].
+  ///
+  /// This schedules the result (as opposed to just emitting one directly on
+  /// [BuildResult]) to ensure that calling multiple functions synchronously
+  /// produces only a single [BuildResult].
+  void _tryScheduleResult() {
+    if (_status != NodeStatus.IDLE) return;
+    if (_resultScheduled) return;
+
+    _resultScheduled = true;
+    newFuture(() {
+      _resultScheduled = false;
+      if (_status != NodeStatus.IDLE) return;
+
+      _lastResult = new BuildResult(_accumulatedErrors);
+      _accumulatedErrors.clear();
+      _resultsController.add(_lastResult);
+    });
+  }
+
+  /// Run [body] in an error-handling [Zone] and pipe any unexpected errors to
+  /// the error channel of [results].
+  ///
+  /// [body] can return a value or a [Future] that will be piped to the returned
+  /// [Future]. If it throws a [BarbackException], that exception will be piped
+  /// to the returned [Future] as well. Any other exceptions will be piped to
+  /// [results].
+  Future _inErrorZone(body()) {
+    var completer = new Completer.sync();
+    runZoned(() {
+      syncFuture(body).then(completer.complete).catchError((error, stackTrace) {
+        if (error is! BarbackException) throw error;
+        completer.completeError(error, stackTrace);
+      });
+    }, onError: (error, stackTrace) {
+      _lastUnexpectedError = error;
+      _lastUnexpectedErrorTrace = stackTrace;
+      _resultsController.addError(error, stackTrace);
+    });
+    return completer.future;
+  }
+}