Graceful shutdown

[ybogdanov]

Hi,

I've made graceful shutdown functionality.
The implementation is simple: Queue object collects all of it's workers, and then, when .shutdown() method is called, it propagates to all of them, and wait until all workers will done their current jobs (if there's some jobs in progress).

Also, added worker.running property to workers, to avoid new jobs pulling when shutting down. And ``worker.job` which points to current job in progress, to determine whether the worker is free or not.

To shutdown Kue object gracefully, simply use the following api:

var jobs = kue.createQueue();

// .. create jobs here

jobs.shutdown(function(err){
   // Kue is down
})

Closes #57

[tj]

I think this is useful, but wouldn't it be more useful to use a signal? instead of a js-api?

[tj]

I wouldn't really worry about xss, Kue should never be running on a public-facing port or anything like that

[ybogdanov]

Anyway, this is not about security. If a task title has html, it should be escaped and never rendered in Kue GUI as html. Shouldn't it?

[tj]

I suppose, though I'm not sure when the title would have html

[ybogdanov]

I think this is useful, but wouldn't it be more useful to use a signal? instead of a js-api?

In my app, I use both of. And both are useful.

process.once('SIGQUIT', function(){
    console.log('shutting down the queue..');
    jobs.shutdown(function(err){
        if (err) console.error(err);
        console.log('queue shutdown complete');
        process.exit();
    })
})

[tj]

for sure, definitely stems from the js-api, I guess we could leave it as the method for now since cluster would need a slightly different solution as well

[bencevans]

Are there plans to merge this at all? It's a very useful feature 👍

[niftylettuce]

👍

[Jellyfrog]

👍

[bulkan]

PR #121 has the changes here so we could possible close this issue too @drudge

Also, anyone interested in this PR or #121 until it gets merged, see https://github.com/LOKE/kue as we merged to our master.

[behrad]

feature is introduced in #256