Stop running pub get at gclient sync time and fix build bugs

mojo/public/dart/third_party/barback/lib/src/graph/asset_cascade.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.asset_cascade;
+
+import 'dart:async';
+
+import '../asset/asset.dart';
+import '../asset/asset_id.dart';
+import '../asset/asset_node.dart';
+import '../asset/asset_set.dart';
+import '../errors.dart';
+import '../log.dart';
+import '../transformer/transformer.dart';
+import '../utils.dart';
+import '../utils/cancelable_future.dart';
+import 'node_status.dart';
+import 'node_streams.dart';
+import 'package_graph.dart';
+import 'phase.dart';
+
+/// The asset cascade for an individual package.
+///
+/// This keeps track of which [Transformer]s are applied to which assets, and
+/// re-runs those transformers when their dependencies change. The transformed
+/// asset nodes are accessible via [getAssetNode].
+///
+/// A cascade consists of one or more [Phases], each of which has one or more
+/// [Transformer]s that run in parallel, potentially on the same inputs. The
+/// inputs of the first phase are the source assets for this cascade's package.
+/// The inputs of each successive phase are the outputs of the previous phase,
+/// as well as any assets that haven't yet been transformed.
+class AssetCascade {
+  /// The name of the package whose assets are managed.
+  final String package;
+
+  /// The [PackageGraph] that tracks all [AssetCascade]s for all dependencies of
+  /// the current app.
+  final PackageGraph graph;
+
+  /// The controllers for the [AssetNode]s that provide information about this
+  /// cascade's package's source assets.
+  final _sourceControllerMap = new Map<AssetId, AssetNodeController>();
+
+  /// Futures for source assets that are currently being loaded.
+  ///
+  /// These futures are cancelable so that if an asset is updated after a load
+  /// has been kicked off, the previous load can be ignored in favor of a new
+  /// one.
+  final _loadingSources = new Map<AssetId, CancelableFuture<Asset>>();
+
+  /// The list of phases in this cascade.
+  ///
+  /// This will always contain at least one phase, and the first phase will
+  /// never have any transformers. This ensures that every transformer can
+  /// request inputs from a previous phase.
+  final _phases = <Phase>[];
+
+  /// The subscription to the [Phase.onStatusChange] stream of the last [Phase]
+  /// in [_phases].
+  StreamSubscription _phaseStatusSubscription;
+
+  /// A stream that emits any errors from the cascade or the transformers.
+  ///
+  /// This emits errors as they're detected. If an error occurs in one part of
+  /// the cascade, unrelated parts will continue building.
+  Stream<BarbackException> get errors => _errorsController.stream;
+  final _errorsController =
+      new StreamController<BarbackException>.broadcast(sync: true);
+
+  /// How far along [this] is in processing its assets.
+  NodeStatus get status {
+    // Just check the last phase, since it will check all the previous phases
+    // itself.
+    return _phases.last.status;
+  }
+
+  /// The streams exposed by this cascade.
+  final _streams = new NodeStreams();
+  Stream<LogEntry> get onLog => _streams.onLog;
+  Stream<NodeStatus> get onStatusChange => _streams.onStatusChange;
+  Stream<AssetNode> get onAsset => _streams.onAsset;
+
+  /// Returns all currently-available output assets from this cascade.
+  Future<AssetSet> get availableOutputs => new Future.value(new AssetSet.from(
+      _phases.last.availableOutputs.map((node) => node.asset)));
+
+  /// Creates a new [AssetCascade].
+  ///
+  /// It loads source assets within [package] using [provider].
+  AssetCascade(this.graph, this.package) {
+    _addPhase(new Phase(this, package));
+    _streams.onAssetPool.add(_phases.last.onAsset);
+  }
+
+  /// Gets the asset 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) {
+    assert(id.package == package);
+
+    var oldLastPhase = _phases.last;
+    // TODO(rnystrom): Waiting for the entire build to complete is unnecessary
+    // in some cases. Should optimize:
+    // * [id] may be generated before the compilation is finished. We should
+    //   be able to quickly check whether there are any more in-place
+    //   transformations that can be run on it. If not, we can return it early.
+    // * If [id] has never been generated and all active transformers provide
+    //   metadata about the file names of assets it can emit, we can prove that
+    //   none of them can emit [id] and fail early.
+    return oldLastPhase.getOutput(id).then((node) {
+      // The last phase may have changed if [updateSources] was called after
+      // requesting the output. In that case, we want the output from the new
+      // last phase.
+      if (_phases.last == oldLastPhase) return node;
+      return getAssetNode(id);
+    });
+  }
+
+  /// 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) {
+    for (var id in sources) {
+      var controller = _sourceControllerMap[id];
+      if (controller != null) {
+        controller.setDirty();
+      } else {
+        _sourceControllerMap[id] = new AssetNodeController(id);
+        _phases.first.addInput(_sourceControllerMap[id].node);
+      }
+
+      // If this source was already loading, cancel the old load, since it may
+      // return out-of-date contents for the asset.
+      if (_loadingSources.containsKey(id)) _loadingSources[id].cancel();
+
+      _loadingSources[id] = new CancelableFuture<Asset>(
+          syncFuture(() => graph.provider.getAsset(id)));
+      _loadingSources[id].whenComplete(() {
+        _loadingSources.remove(id);
+      }).then((asset) {
+        var controller = _sourceControllerMap[id].setAvailable(asset);
+      }).catchError((error, stack) {
+        reportError(new AssetLoadException(id, error, stack));
+
+        // TODO(nweiz): propagate error information through asset nodes.
+        _sourceControllerMap.remove(id).setRemoved();
+      });
+    }
+  }
+
+  /// Removes [removed] from the graph's known set of source assets.
+  void removeSources(Iterable<AssetId> removed) {
+    removed.forEach((id) {
+      // If the source was being loaded, cancel that load.
+      if (_loadingSources.containsKey(id)) _loadingSources.remove(id).cancel();
+
+      var controller = _sourceControllerMap.remove(id);
+      // Don't choke if an id is double-removed for some reason.
+      if (controller != null) controller.setRemoved();
+    });
+  }
+
+  /// Sets this cascade's transformer phases to [transformers].
+  ///
+  /// Elements of the inner iterable of [transformers] must be [Transformer]s,
+  /// [TransformerGroup]s, or [AggregateTransformer]s.
+  void updateTransformers(Iterable<Iterable> transformersIterable) {
+    _streams.onAssetPool.remove(_phases.last.onAsset);
+    var transformers = transformersIterable.toList();
+
+    // Always preserve a single phase with no transformers at the beginning of
+    // the cascade so that [TransformNode]s in the first populated phase will
+    // have something to request assets from.
+    for (var i = 0; i < transformers.length; i++) {
+      if (_phases.length > i + 1) {
+        _phases[i + 1].updateTransformers(transformers[i]);
+        continue;
+      }
+
+      var phase = _phases.last.addPhase();
+      _addPhase(phase);
+      phase.updateTransformers(transformers[i]);
+    }
+
+    for (var i = transformers.length + 1; i < _phases.length; i++) {
+      _phases[i].remove();
+    }
+    _phases.removeRange(transformers.length + 1, _phases.length);
+
+    _phaseStatusSubscription.cancel();
+    _phaseStatusSubscription = _phases.last.onStatusChange
+        .listen(_streams.changeStatus);
+
+    _streams.onAssetPool.add(_phases.last.onAsset);
+  }
+
+  /// Force all [LazyTransformer]s' transforms in this cascade to begin
+  /// producing concrete assets.
+  void forceAllTransforms() {
+    for (var phase in _phases) {
+      phase.forceAllTransforms();
+    }
+  }
+
+  void reportError(BarbackException error) {
+    _errorsController.add(error);
+  }
+
+  /// Add [phase] to the end of [_phases] and watch its streams.
+  void _addPhase(Phase phase) {
+    _streams.onLogPool.add(phase.onLog);
+    if (_phaseStatusSubscription != null) _phaseStatusSubscription.cancel();
+    _phaseStatusSubscription =
+        phase.onStatusChange.listen(_streams.changeStatus);
+
+    _phases.add(phase);
+  }
+
+  String toString() => "cascade for $package";
+}