the-forest/client/node_modules/promise-limit/index.js
2024-09-17 20:35:18 -04:00

89 lines
1.5 KiB
JavaScript

function limiter (count) {
var outstanding = 0
var jobs = []
function remove () {
outstanding--
if (outstanding < count) {
dequeue()
}
}
function dequeue () {
var job = jobs.shift()
semaphore.queue = jobs.length
if (job) {
run(job.fn).then(job.resolve).catch(job.reject)
}
}
function queue (fn) {
return new Promise(function (resolve, reject) {
jobs.push({fn: fn, resolve: resolve, reject: reject})
semaphore.queue = jobs.length
})
}
function run (fn) {
outstanding++
try {
return Promise.resolve(fn()).then(function (result) {
remove()
return result
}, function (error) {
remove()
throw error
})
} catch (err) {
remove()
return Promise.reject(err)
}
}
var semaphore = function (fn) {
if (outstanding >= count) {
return queue(fn)
} else {
return run(fn)
}
}
return semaphore
}
function map (items, mapper) {
var failed = false
var limit = this
return Promise.all(items.map(function () {
var args = arguments
return limit(function () {
if (!failed) {
return mapper.apply(undefined, args).catch(function (e) {
failed = true
throw e
})
}
})
}))
}
function addExtras (fn) {
fn.queue = 0
fn.map = map
return fn
}
module.exports = function (count) {
if (count) {
return addExtras(limiter(count))
} else {
return addExtras(function (fn) {
return fn()
})
}
}