active status to know when job is waiting for next tick or currently executing

[ktravelet]

Hi All, first thanks a ton for this. I'm currently using it in a monitoring tool that goes and pulls SQL at set intervals. It seems to be working wonderfully.

I'm trying to prevent these jobs from overlapping and the method is not the most elegant. Right now I'm setting an active parameter to the this object and have an condition to catch if the job is currently executing.

Would it be possible to make something like this built in and is there better way to do it?

Thanks!

var job = new CronJob({
    cronTime: '* * * * * *',
    onTick: () => {

        if (typeof this.isCurrentlyExecuting === 'undefined') {

            this.isCurrentlyExecuting = false;

        }

        if (this.isCurrentlyExecuting) {

            console.log(moment().format('YYYY-MM-DD HH:mm:ss.SS - ') + 'Job already running.  Canceling this execution.', this);
            return;

        }

        this.isCurrentlyExecuting = true;

        console.log(moment().format('YYYY-MM-DD HH:mm:ss.SS - ') + 'Job is currently executing');

        setTimeout(()=>{

            console.log(moment().format('YYYY-MM-DD HH:mm:ss.SS - ') + 'Job is done executing');
            this.isCurrentlyExecuting = false;

        }, 5000)

    },
    start: true /* Start the job right now */
});

The code above will output the following:

2017-09-15 18:13:10.38 - Job is currently executing
2017-09-15 18:13:11.38 - Job already running.  Canceling this execution. { isCurrentlyExecuting: true }
2017-09-15 18:13:12.38 - Job already running.  Canceling this execution. { isCurrentlyExecuting: true }
2017-09-15 18:13:13.38 - Job already running.  Canceling this execution. { isCurrentlyExecuting: true }
2017-09-15 18:13:14.38 - Job already running.  Canceling this execution. { isCurrentlyExecuting: true }
2017-09-15 18:13:15.38 - Job is done executing
2017-09-15 18:13:15.38 - Job is currently executing
2017-09-15 18:13:16.38 - Job already running.  Canceling this execution. { isCurrentlyExecuting: true }
2017-09-15 18:13:17.38 - Job already running.  Canceling this execution. { isCurrentlyExecuting: true }
2017-09-15 18:13:18.38 - Job already running.  Canceling this execution. { isCurrentlyExecuting: true }
2017-09-15 18:13:19.38 - Job already running.  Canceling this execution. { isCurrentlyExecuting: true }
2017-09-15 18:13:20.38 - Job is done executing

[ncb000gt]

I'd consider a PR but don't have the time to implement this kind of thing at the moment.

[sheerlox]

duplicate of #556