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test | ||
.npmignore | ||
.travis.yml | ||
index.js | ||
LICENSE | ||
package.json | ||
README.md |
throat
Throttle the parallelism of an asynchronous, promise returning, function / functions. This has special utility when you set the concurrency to 1
. That way you get a mutually exclusive lock.
Installation
npm install throat
API
throat(concurrency)
This returns a function that acts a bit like a lock (exactly as a lock if concurrency is 1).
Example, only 2 of the following functions will execute at any one time:
// with polyfill or in iojs
require('promise/polyfill')
var throat = require('throat')(2)
// alternatively provide your own promise implementation
var throat = require('throat')(require('promise'))(2)
var resA = throat(function () {
//async stuff
return promise
})
var resA = throat(function () {
//async stuff
return promise
})
var resA = throat(function () {
//async stuff
return promise
})
var resA = throat(function () {
//async stuff
return promise
})
var resA = throat(function () {
//async stuff
return promise
})
throat(concurrency, worker)
This returns a function that is an exact copy of worker
except that it will only execute up to concurrency
times in parallel before further requests are queued:
// with polyfill or in iojs
require('promise/polyfill')
var throat = require('throat')
// alternatively provide your own promise implementation
var throat = require('throat')(require('promise'))
var input = ['fileA.txt', 'fileB.txt', 'fileC.txt', 'fileD.txt']
var data = Promise.all(input.map(throat(2, function (fileName) {
return readFile(fileName)
})))
Only 2 files will be read at a time, sometimes limiting parallelism in this way can improve scalability.
License
MIT