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const defLimit = require('os').cpus().length
const callLimit = (queue, limit = defLimit) => new Promise((res, rej) => {
let active = 0
let current = 0
const results = []
let rejected = false
const reject = er => {
if (rejected)
return
rejected = true
rej(er)
}
let resolved = false
const resolve = () => {
if (resolved || active > 0)
return
resolved = true
res(results)
}
const run = () => {
const c = current++
if (c >= queue.length) {
return resolve()
}
active ++
results[c] = queue[c]().then(result => {
active --
results[c] = result
run()
return result
}, reject)
}
for (let i = 0; i < limit; i++) {
run()
}
})
module.exports = callLimit
|
