Machina-based linear/fork-join FSM Task Idea

DistributedTask.js

define([
	'underscore',
	'machina'
], function( _, machina ){
	return function(config) {
		var base = {
			initialState: "notStarted",
			checkIfReady: function() {
				if(_.all(this.constraints[this.state].checkList, function(constraint) { return constraint; })) {
					this.transition(this.constraints[this.state].nextState);
				}
			},
			timeoutHandle: undefined,
			data: [],
			constraints: {
				working: {
					nextState: "completed",
					checkList: {}
				}
			},
			states: {
				notStarted: {
					"*" : function() {
						this.deferUntilTransition();
					}
				},
				working: {
					_onEnter: function() {
						var self = this;
						if(config.onStart) {
							config.onStart();
						}
						if(config.timeout) {
							self.timeoutHandle = setTimeout(function(){
								self.transition("error");
							}, config.timeout);
						}
					}
				},
				completed: {
					_onEnter: function() {
						clearTimeout(this.timeoutHandle);
						config.onComplete.apply(this, this.data);
					}
				},
				error: {
					_onEnter: function() {
						config.onError.apply(this, this.data);
					},
					"*" : function() {
						this.deferUntilTransition();
					}
				}
			},
			start: function() {
				this.transition("working");
			}
		};

		if(config.trigger) {
			var handler = function() {
				this.transition("working");
			};
			base.states.notStarted[config.trigger] = handler;
			base.states.completed[config.trigger] = handler;
			base.states.error[config.trigger] = handler;
		}

		_.each(config.topics, function(topic, idx) {
			base.constraints.working.checkList[topic] = false;
			base.states.working[topic] = function( data ) {
				this.data[idx] = data;
				this.constraints.working.checkList[topic] = true;
				this.checkIfReady();
			};
		});

		return new machina.Fsm(base);
	}
});

usageExample.js

var task = new DistributedTask({
	timeout: 4000,
	trigger: "resources.load",
	topics: ["resource1.loaded","resource2.loaded","resource3.loaded","resource4.loaded"],
	onStart: function() {
		_.each([1,2,3,4], function(key) {
			utils.publish("get.resource" + key);
		});
	},
	onComplete: function(resource1,resource2,resource3,resource4) {
		// do stuff with the resources
	},
	onError: function(resource1,resource2,resource3,resource4) {
		this.start(); // retry
	}
});