q_stack/q_stack.js

Stack work for promises based on 'q' to prevent to much calls

var Q = require('q');
var _ = require('underscore-node');

var id = 0;
var defaultMaxFunctions = 10
var que = {};
var defaultStackName = "__default__";

module.exports = {
	maxCalls: function (maxCalls, stackName) {
		if (maxCalls && maxCalls < 1) {
			maxCalls = 1;
		}
		stackName = stackName || defaultStackName;
		que[stackName] = que[stackName] || {
			maxFunctions: maxCalls || defaultStackName
		};
	},
	call: function (functionObject, args, stackName) {
		stackName = stackName || defaultStackName;
		var deffered = Q.defer();
		que[stackName] = que[stackName] || {
			maxFunctions: defaultMaxFunctions
		};
		que[stackName]["queue"] = que[stackName]["queue"] || [];
		que[stackName]["execute"] = que[stackName]["execute"] || [];
		que[stackName]["queue"].push({ func: functionObject, args: args, funcDeffered: deffered });

		function functionReady(stackName, runId) {
			var func = _.find(que[stackName]["execute"], function (item) {
				return item.id == runId;
			});
			var index = que[stackName]["execute"].indexOf(func);
			que[stackName]["execute"].splice(index, 1);
			startNext();
		}

		function startNext() {
			if (que[stackName]["execute"].length <= que[stackName].maxFunctions && que[stackName]["queue"].length > 0) {
				id++;
				var runId = id;
				var queFunc = _.first(que[stackName]["queue"]);
				var exeFunc = queFunc.func.apply(null, queFunc.args);
				var runFunc = exeFunc.then(function (data) {
					functionReady(stackName, runId);
					queFunc.funcDeffered.resolve(data);
				}, function (err) {
					queFunc.funcDeffered.reject(err);
				});
				que[stackName]["execute"].push({ id: runId, func: runFunc });
				var index = que[stackName]["queue"].indexOf(queFunc);
				que[stackName]["queue"].splice(index, 1);
			}
		}

		startNext();
		return deffered.promise;
	}
};