mirror of
https://github.com/idanoo/GoScrobble.git
synced 2024-11-24 09:25:15 +00:00
87 lines
2.2 KiB
Markdown
87 lines
2.2 KiB
Markdown
# run-queue
|
|
|
|
A promise based, dynamic priority queue runner, with concurrency limiting.
|
|
|
|
```js
|
|
const RunQueue = require('run-queue')
|
|
|
|
const queue = new RunQueue({
|
|
maxConcurrency: 1
|
|
})
|
|
|
|
queue.add(1, example, [-1])
|
|
for (let ii = 0; ii < 5; ++ii) {
|
|
queue.add(0, example, [ii])
|
|
}
|
|
const finished = []
|
|
queue.run().then(
|
|
console.log(finished)
|
|
})
|
|
|
|
function example (num, next) {
|
|
setTimeout(() => {
|
|
finished.push(num)
|
|
next()
|
|
}, 5 - Math.abs(num))
|
|
}
|
|
```
|
|
|
|
would output
|
|
|
|
```
|
|
[ 0, 1, 2, 3, 4, -1 ]
|
|
```
|
|
|
|
If you bump concurrency to `2`, then you get:
|
|
|
|
```
|
|
[ 1, 0, 3, 2, 4, -1 ]
|
|
```
|
|
|
|
The concurrency means that they don't finish in order, because some take
|
|
longer than others. Each priority level must finish entirely before the
|
|
next priority level is run. See
|
|
[PRIORITIES](https://github.com/iarna/run-queue#priorities) below. This is
|
|
even true if concurrency is set high enough that all of the regular queue
|
|
can execute at once, for instance, with `maxConcurrency: 10`:
|
|
|
|
```
|
|
[ 4, 3, 2, 1, 0, -1 ]
|
|
```
|
|
|
|
## API
|
|
|
|
### const queue = new RunQueue(options)
|
|
|
|
Create a new queue. Options may contain:
|
|
|
|
* maxConcurrency - (Default: `1`) The maximum number of jobs to execute at once.
|
|
* Promise - (Default: global.Promise) The promise implementation to use.
|
|
|
|
### queue.add (prio, fn, args)
|
|
|
|
Add a new job to the end of the queue at priority `prio` that will run `fn`
|
|
with `args`. If `fn` is async then it should return a Promise.
|
|
|
|
### queue.run ()
|
|
|
|
Start running the job queue. Returns a Promise that resolves when either
|
|
all the jobs are complete or a job ends in error (throws or returns a
|
|
rejected promise). If a job ended in error then this Promise will be rejected
|
|
with that error and no further queue running will be done.
|
|
|
|
## PRIORITIES
|
|
|
|
Priorities are any integer value >= 0.
|
|
|
|
Lowest is executed first.
|
|
|
|
Priorities essentially represent distinct job queues. All jobs in a queue
|
|
must complete before the next highest priority job queue is executed.
|
|
|
|
This means that if you have two queues, `0` and `1` then ALL jobs in `0`
|
|
must complete before ANY execute in `1`. If you add new `0` level jobs
|
|
while `1` level jobs are running then it will switch back processing the `0`
|
|
queue and won't execute any more `1` jobs till all of the new `0` jobs
|
|
complete.
|