parallelLimit.js•980 B
'use strict';
module.exports = parallelLimit;
/*!
* ignore
*/
function parallelLimit(fns, limit, callback) {
let numInProgress = 0;
let numFinished = 0;
let error = null;
if (limit <= 0) {
throw new Error('Limit must be positive');
}
if (fns.length === 0) {
return callback(null, []);
}
for (let i = 0; i < fns.length && i < limit; ++i) {
_start();
}
function _start() {
fns[numFinished + numInProgress](_done(numFinished + numInProgress));
++numInProgress;
}
const results = [];
function _done(index) {
return (err, res) => {
--numInProgress;
++numFinished;
if (error != null) {
return;
}
if (err != null) {
error = err;
return callback(error);
}
results[index] = res;
if (numFinished === fns.length) {
return callback(null, results);
} else if (numFinished + numInProgress < fns.length) {
_start();
}
};
}
}