bhaweshksingh / node-cron-job Goto Github PK

This is a cron job scheduler for Node.

Allows jobs to be defined in a separate module.

It can fork a new process for each job, resulting in zero impact on application performance.

• Install
• Setup
• API
• Note
• Future releases

$ npm install node-cron-job

The jobs have to be declared in a separate module such as:

// jobs.js

exports.first_job = {
    
    after: {                // Configuring this job to run after this period.
        milliseconds:2, 
        seconds: 2,
        minutes:2,
        hours: 1,
        days: 3
    },
    job: function () {
        console.log("first_job");
    },
    spawn: true             
}

exports.second_job = {
    
    on: "*/2 * * * * *",    // Cron tab instruction.
    job: function () {
        console.log("second_job");
    },
    spawn: false            // If false, the job will not run in a separate process.
}

Next, the module may be used any where within your code to indicate the absolute path to the jobs file and explicit instructions to start those jobs. Example:

// main.js

var cronjob = require('node-cron-job');


cronjob.setJobsPath(__dirname + '/jobs.js');  // Absolute path to the jobs module.

cronjob.startJob('first_job');

cronjob.startJob('second_job');

Each job exported by the jobs module can have the following objects:

• on: The cron tab instruction string that defines the schedule. Please see crontab.org.

cron-parser is used to parse these.

• after: A easier-to-use but less expressive way to schedule a job. It defines the time after which the job is supposed to run, periodically. This will take priority over on. Example:

after: {
    hours: 2,
    days: 10
},

• job: The job closure/function that is to be scheduled.

• spawn: A boolean value telling the module to run this job in a separate forked process or in the same thread as your application. This should be set according to scalibility and peformance needs. The default value is true.

The module includes these methods:

• setJobsPath(abs_path): Sets the absolute path to the jobs module.

• startJob(job_name): Starts the given job.

• startAllJobs(): Starts all jobs defined in the jobs module.

If your application is a cluster with multiple instances, beware that unless you load and start your jobs module in the master process, your jobs may run on schedule once per node instance !

An option will be introduced soon allowing all the jobs to run in one separate process. The API will be extended to include methods allowing running jobs to halt. Some of the work may be moved to a C++ extension in future releases.