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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 dependency_graph; | |
| 6 | |
| 7 import 'dart:async'; | |
| 8 import 'utils.dart'; | |
| 9 | |
| 10 | |
| 11 /* | |
| 12 * [Graph] represents a datastructure for representing an DAG (directed acyclic | |
| 13 * graph). Each node in the graph is in a given [NodeState] and can have data | |
| 14 * attachted to it with [Node.userData]. | |
| 15 * | |
| 16 * It's interface consists basically of these methods: | |
| 17 * - newNode: Adds a new node to the graph with the given dependencies and | |
| 18 * the given user data. The node is in the [NodeState.Initialized] | |
| 19 * state. | |
| 20 * - changeState: Changes the state of a node. | |
| 21 * - sealGraph: Makes the graph immutable. | |
| 22 * - stateCount: Counts the number of nodes who are in a given [NodeState]. | |
| 23 * | |
| 24 * Users of a [Graph] can listen for events by subscribing to the [events] | |
| 25 * stream. Three types of events will be fired (after the graph was modified): | |
| 26 * - NodeAddedEvent: Fired after a node was added ot the graph. | |
| 27 * - StateChangedEvent: Fired after the state of a node changed. | |
| 28 * - GraphSealedEvent: Fired after the graph was marked as immutable/sealed. | |
| 29 */ | |
| 30 class Graph { | |
| 31 final _nodes = new Set<Node>(); | |
| 32 final _eventController = new StreamController<GraphEvent>(); | |
| 33 final _stateCounts = new Map<NodeState, int>(); | |
| 34 var _eventStream; | |
| 35 bool _isSealed = false; | |
| 36 | |
| 37 Graph() { | |
| 38 _eventStream = _eventController.stream.asBroadcastStream(); | |
| 39 } | |
| 40 | |
| 41 Iterable<Node> get nodes => _nodes; | |
| 42 Stream<GraphEvent> get events => _eventStream; | |
| 43 bool get isSealed => _isSealed; | |
| 44 | |
| 45 int stateCount(NodeState state) { | |
| 46 int count = _stateCounts[state]; | |
| 47 return count == null ? 0 : count; | |
| 48 } | |
| 49 | |
| 50 void DumpCounts() { | |
| 51 for (var state in _stateCounts.keys) { | |
| 52 print("Count[$state] = ${_stateCounts[state]}"); | |
| 53 } | |
| 54 } | |
| 55 | |
| 56 void sealGraph() { | |
| 57 assert(!_isSealed); | |
| 58 _isSealed = true; | |
| 59 _emitEvent(new GraphSealedEvent()); | |
| 60 } | |
| 61 | |
| 62 Node newNode(Object userData, Iterable<Node> dependencies) { | |
| 63 assert(!_isSealed); | |
| 64 | |
| 65 var node = new Node._(userData); | |
| 66 _nodes.add(node); | |
| 67 | |
| 68 for (var dependency in dependencies) { | |
| 69 dependency._neededFor.add(node); | |
| 70 node._dependencies.add(dependency); | |
| 71 } | |
| 72 | |
| 73 _emitEvent(new NodeAddedEvent(node)); | |
| 74 | |
| 75 _stateCounts.putIfAbsent(node.state, () => 0); | |
| 76 _stateCounts[node.state] += 1; | |
| 77 | |
| 78 return node; | |
| 79 } | |
| 80 | |
| 81 void changeState(Node node, NodeState newState) { | |
| 82 var fromState = node.state; | |
| 83 node._state = newState; | |
| 84 | |
| 85 _stateCounts[fromState] -= 1; | |
| 86 _stateCounts.putIfAbsent(newState, () => 0); | |
| 87 _stateCounts[newState] += 1; | |
| 88 | |
| 89 _emitEvent(new StateChangedEvent(node, fromState, newState)); | |
| 90 } | |
| 91 | |
| 92 _emitEvent(GraphEvent event) { | |
| 93 // We emit events asynchronously so the graph can be build up in small | |
| 94 // batches and the events are delivered in small batches. | |
| 95 Timer.run(() { | |
| 96 _eventController.add(event); | |
| 97 }); | |
| 98 } | |
| 99 } | |
| 100 | |
| 101 class Node extends UniqueObject { | |
| 102 final Object _userData; | |
| 103 NodeState _state = NodeState.Initialized; | |
| 104 Set<Node> _dependencies = new Set<Node>(); | |
| 105 Set<Node> _neededFor = new Set<Node>(); | |
| 106 | |
| 107 Node._(this._userData); | |
| 108 | |
| 109 Object get userData => _userData; | |
| 110 NodeState get state => _state; | |
| 111 Iterable<Node> get dependencies => _dependencies; | |
| 112 Iterable<Node> get neededFor => _neededFor; | |
| 113 } | |
| 114 | |
| 115 class NodeState extends UniqueObject { | |
| 116 static NodeState Initialized = new NodeState._("Initialized"); | |
| 117 static NodeState Waiting = new NodeState._("Waiting"); | |
| 118 static NodeState Enqueuing = new NodeState._("Enqueuing"); | |
| 119 static NodeState Processing = new NodeState._("Running"); | |
| 120 static NodeState Successful = new NodeState._("Successful"); | |
| 121 static NodeState Failed = new NodeState._("Failed"); | |
| 122 static NodeState UnableToRun = new NodeState._("UnableToRun"); | |
| 123 | |
| 124 final String name; | |
| 125 | |
| 126 NodeState._(this.name); | |
| 127 | |
| 128 String toString() => name; | |
| 129 } | |
| 130 | |
| 131 abstract class GraphEvent {} | |
| 132 | |
| 133 class GraphSealedEvent extends GraphEvent {} | |
| 134 | |
| 135 class NodeAddedEvent extends GraphEvent { | |
| 136 final Node node; | |
| 137 | |
| 138 NodeAddedEvent(this.node); | |
| 139 } | |
| 140 | |
| 141 class StateChangedEvent extends GraphEvent { | |
| 142 final Node node; | |
| 143 final NodeState from; | |
| 144 final NodeState to; | |
| 145 | |
| 146 StateChangedEvent(this.node, this.from, this.to); | |
| 147 } | |
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