Package Exports

busywait

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Readme

busywait.js

Simple Async busy wait module for Node.JS

Installation

This module is installed via npm:

npm install --save busywait

Usage

Running:

const busywait = require('busywait').sync;

const waitUntil = Date.now() + 2500;

function syncCheck(iteration) {
    console.log('running iteration', iteration);
    return Date.now() > waitUntil;
}

busywait(syncCheck, {
    sleepTime: 500,
    maxChecks: 20
})
    .then(function (iterations) {
        console.log('finished after', iterations, 'iterations');
    });

or:

const busywait = require('busywait').async;
const Promise = require('bluebird');

const waitUntil = Date.now() + 2500;

function asyncCheck(iteration) {
    return new Promise(function (resolve, reject) {
        console.log('running iteration', iteration);
        if (Date.now() > waitUntil) {
            return resolve();
        } else {
            return reject();
        }
    });
}

busywait(asyncCheck, {
    sleepTime: 500,
    maxChecks: 20
})
    .then(function (iterations) {
        console.log('finished after', iterations, 'iterations');
    });

Will result in:

running iteration 1
running iteration 2
running iteration 3
running iteration 4
running iteration 5
running iteration 6
finished after 6 iterations

Methods

sync(syncCheckFn, options): Promise

The syncCheckFn first argument is the function to run on each iteration. syncCheckFn must be a function with a boolean return value. The current iteration number will be passed as first argument to every call of syncCheckFn.

The mandatory options are:

sleepTime - Time in ms to wait between checks
maxChecks - The max number of checks to perform before failing

Return value is a promise. The promise will be resolved with the number of iterations passed if the syncCheckFn returned true within a legal number of checks. The promise will be rejected if the syncCheckFn rejected maxChecks times.

async(asyncCheckFn, options): Promise

The asyncCheckFn first argument is the function to run on each iteration. syncCheckFn must be a function with a promise return value. The current iteration number will be passed as first argument to every call of asyncCheckFn.

The mandatory options are:

sleepTime - Time in ms to wait between checks
maxChecks - The max number of checks to perform before failing

Return value is a promise. The promise will be resolved with the number of iterations passed if the asyncCheckFn was resolved within a legal number of checks. The promise will be rejected if the asyncCheckFn rejected maxChecks times.