workflow-4-node/lib/es6/hosting/keepAlive.js

Workflow 4 Node is a .NET Workflow Foundation like framework for Node.js. The goal is to reach feature equivalence and beyond.

var _ = require("lodash");
var Bluebird = require("bluebird");

function KeepAlive(repeatFunc, repeatPeriod) {
    if (!_.isFunction(repeatFunc)) throw new TypeError("Function argument expected.");
    this._repeatFunc = repeatFunc;
    this._repeatPeriod = repeatPeriod;
    this._isRunning = true;
    this._toId = null;
    var self = this;
    process.nextTick(function () {
        self._start.call(self);
    });
}

KeepAlive.prototype._start = function () {
    var self = this;
    self._toId = setTimeout(
        function () {
            if (self._isRunning) {
                Bluebird.resolve(self._repeatFunc())
                    .catch(function (e) {
                        console.error("Keep alive failed:\n" + e.stack);
                    })
                    .finally(function () {
                        if (self._isRunning) self._start();
                    });
            }
        },
        self._repeatPeriod);
}

KeepAlive.prototype.end = function () {
    if (!this._isRunning) throw new Error("Keep alive has already ended.");

    this._isRunning = false;
    if (this._toId) clearTimeout(this._toId);
}

module.exports = KeepAlive;