About

A Job Queue.

Add your jobs there and the .onJob will be called whenever is possible.

Only one job will be in progress each time.

Installation

In the root folder of you app run:

npm install --save dyna-job-queue

Methods

constructor(config: IDynaJobQueueConfig)

interface IDynaJobQueueConfig {
  parallels?: number;       // default 1, the number of the parallel jobs
}

jobFactory(func: (...params: any[]) => Promise, priority: number = 1): () => Promise

Although the signature looks quite complex, is the easiest method of the job queue ever.

It converts an already existed function/method that returns Promise, to a job that will be added to the queue.

Once you wrapped it the only you have is to call is as you did before. Nothing is changed.

For typescript writers, there is no need even to define the TResolve, as explicitly comes from method's definition.

example:

class NewsFeeder {
    private readonly feeds: number[] = [];
    private queue = new DynaJobQueue();
    
    constructor() {
      this.addFeed = this.queue.jobFactory(this.addFeed.bind(this));  // That's all
    }
    
    public addFeed(feed: number, afterDelay: number): Promise<number> {
      return new Promise((resolve: Function) => {
        setTimeout(() => {
          this.feeds.push(feed);
          resolve(feed);
        }, afterDelay);
      });
    }
}

addJob(command: string, data: any, priority: number = 1): void

Adds a job and will be executed when all other jobs will be executed (FIFO) according also the priority (where is optional).

The command is a string that will help you to understand what is this job.

The data can be anything, let's say, the parameters for this job.

The priority is optional. Default value is 1. Smaller numbers have priority.

example:

queue.addJob('loadConfig', {endPoint: 'http://example.com/awesomeCondig'});

queue.addJob('loadImage', {endPoint: 'http://example.com/awesomeCondig'}, 2); // <-- priotity 2

addJobCallback(callback: (done: Function) => void, priority: number = 1): void

This is another way to add a job. You don't define command and data but directly the callback function you want to call. The callback will be called with only the done: Function as argument.

example:

// implement an anonymous function
queue.addJobCallback((done: Function) => {
  // so something special here
  done();
});

// as above, define also the priority
queue.addJobCallback((done: Function) => {
  // so something special here
  done();
}, 2);  // <-- priority 2!

// use an already implemented function
queue.addJobCallback(this.processMyJob, 2);  // <-- priority 2!

addJobPromise(callback: (resolve: (data?: TResolve) => void, reject: (error?: any) => void) => void, priority: number = 1): Promise

This method adds a job with callback and returns a Promise. It create a new Promise. The callback provides two functions, the resolve and the reject when will fulfill the Promise. In resolve pass the output of the Promise.

The difference with the callback of other methods is that you have to call the resolve or reject instead of done; that's all!

So this method is a Promise generator. The benefit is that you can get the Promise that will be fulfilled on the proper time.

example:

queue.addJobPromise((resolve: Function, reject: Function) => {
  try{
    // do some work here
    resolve(data);    
  } catch (err) {
    reject(err);
  }
}, 2) // <-- this 2 is the priority
  .then((data: any) => {
    // our resloved data are here
  })
  .catch((err: any)) => {
    // our exception is dropped here
  });

addJobPromised(returnPromise: () => Promise, priority: number = 1): Promise

This method adds a job from a Promise.

Since the Promise by it's nature is executed instantly, you have to pass a callback that will execute the promise at the proper time.

example:

queue.addJobPromises((resolve: Function, reject: Function) => {
  return fetch('http://api.example.com/customer-info?:id=4853847343');
}, 2) // <-- this 2 is the priority
  .then((data: any) => {
    // our resloved data are here
  })
  .catch((err: any)) => {
    // our exception is dropped here
  });