added experimental queue runner...

Signed-off-by: Alex A. Naanou <alex.nanou@gmail.com>

runner.js

@@ -0,0 +1,168 @@
+/**********************************************************************
+* 
+*
+*
+**********************************************/  /* c8 ignore next 2 */
+((typeof define)[0]=='u'?function(f){module.exports=f(require)}:define)
+(function(require){ var module={} // make module AMD/node compatible...
+/*********************************************************************/
+
+var object = require('ig-object')
+
+
+
+/*********************************************************************/
+
+var makeEvent = function(func){
+	return Object.assign(
+		func,
+		{__event__: true}) }
+
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
+
+var Queue =
+module.Queue = object.Constructor('Queue', Array, {
+	run: function(){
+	},
+
+},{
+	pool_size: 8,
+	poling_delay: 200,
+
+	__state: null,
+	get state(){
+		return this.__state 
+			|| 'stopped' },
+	set state(value){
+		if(!['running', 'stopped'].includes(value)){
+			return }
+		this.__state = value
+		value == 'running'
+			&& this._run() },
+
+	start: function(){
+		this.state = 'running'
+		return this },
+	stop: function(){
+		this.state = 'stopped'
+		return this },
+	clear: function(){
+		this.splice(0, this.length) 
+		return this },
+
+	// event API...
+	// XXX mignt be good to make this a generic mixin...
+	trigger: function(evt, ...args){
+		var that = this
+		;(this['__'+evt] || [])
+			.forEach(function(handler){
+				handler.call(that, evt, ...args) })
+		return this },
+	on: function(evt, handler){
+		if(!handler){
+			throw new Error('.on(..): need a handler') }
+		if(!this[evt] || !this[evt].__event__){
+			throw new Error('.on(..): can\'t register handler for non-event:'+ evt) }
+		evt = '__'+evt
+		handler
+			&& (this[evt] = this[evt] || []).push(handler)
+		return this },
+	one: function(evt, handler){
+		var that = this
+		return handler ?
+			this.on(evt, Object.assign(
+				function(){
+					handler.call(this, ...arguments)
+					that.off(evt, handler) }, 
+				{ original_handler: handler }))
+			: this },
+	off: function(evt, handler){
+		var handlers = (this['__'+evt] || [])
+		handlers.length > 0
+			&& handlers.splice(0, handlers.length,
+				...handlers
+					.filter(function(func){
+						return func === handler
+							|| func.original_handler === handler }))
+		return this },
+
+	// events...
+	taskCompleted: makeEvent(function(func){
+		return this.on('taskCompleted', ...arguments) }),
+
+	// NOTE: we do not store the exec results... (XXX ???)
+	// NOTE: not intended for direct use and will likely have no effect
+	// 		if called directly... 
+	__running: null,
+	_run: function(){
+		// if we are not running stop immidiately...
+		if(this.state != 'running'){
+			return this }
+
+		var that = this
+		var running = this.__running = this.__running || []
+
+		// handle queue...
+		while(this.length > 0 
+				&& this.state == 'running'
+				&& running.length < (this.pool_size || Infinity) ){
+
+			// run...
+			var task = this.shift()
+			var res = typeof(task) == 'function' ?
+				task()
+				: task
+
+			// pool async (promise) task...
+			if(typeof((res || {}).finally) == 'function'
+					// one post handler is enough...
+					&& !running.includes(res)){
+				running.push(res) 
+				res.finally(function(){
+					// remove from running...
+					running.splice(0, running.length, 
+						// NOTE: there can be multiple occurences of res...
+						...running
+							.filter(function(e){ return e !== res }))
+					// finishup...
+					that
+						.trigger('taskCompleted', task, res)
+						._run() })
+
+			// completed sync task...
+			} else {
+				this.trigger('taskCompleted', task, res) } }
+
+		// pole on empty queue...
+		//
+		// NOTE: we endup here in two cases:
+		// 		- the pool is full
+		// 		- the queue is empty
+		// NOTE: we do not care about stopping the timer when changing 
+		// 		state as ._run() will stop itself...
+		//
+		// XXX will this be collected by the GC if it is polling???
+		if(this.length == 0 
+				&& this.state == 'running'
+				&& this.poling_delay){
+			setTimeout(
+				this._run.bind(this), 
+				this.poling_delay || 200) }
+
+		return this },
+
+	__init__: function(options){ 
+		if(this[0] instanceof Object 
+				&& typeof(this[0]) != 'function'
+				&& typeof(this[0].finally) != 'function'){
+			Object.assign(this, this.shift()) }
+		this._run() },
+})
+
+
+
+
+
+/**********************************************************************
+* vim:set ts=4 sw=4 :                               */ return module })