63 lines
1.4 KiB
JavaScript
63 lines
1.4 KiB
JavaScript
|
/*
|
||
|
|
MIT License http://www.opensource.org/licenses/mit-license.php
|
||
|
|
Author Tobias Koppers @sokra
|
||
|
|
*/
|
||
|
|
|
||
|
|
"use strict";
|
||
|
|
|
||
|
|
/**
|
||
|
|
* @template T
|
||
|
|
* @template {Error} E
|
||
|
|
* @param {Iterable<T>} items initial items
|
||
|
|
* @param {number} concurrency number of items running in parallel
|
||
|
|
* @param {function(T, function(T): void, function(E=): void): void} processor worker which pushes more items
|
||
|
|
* @param {function(E=): void} callback all items processed
|
||
|
|
* @returns {void}
|
||
|
|
*/
|
||
|
|
const processAsyncTree = (items, concurrency, processor, callback) => {
|
||
|
|
const queue = Array.from(items);
|
||
|
|
if (queue.length === 0) return callback();
|
||
|
|
let processing = 0;
|
||
|
|
let finished = false;
|
||
|
|
let processScheduled = true;
|
||
|
|
|
||
|
|
const push = item => {
|
||
|
|
queue.push(item);
|
||
|
|
if (!processScheduled && processing < concurrency) {
|
||
|
|
processScheduled = true;
|
||
|
|
process.nextTick(processQueue);
|
||
|
|
}
|
||
|
|
};
|
||
|
|
|
||
|
|
const processorCallback = err => {
|
||
|
|
processing--;
|
||
|
|
if (err && !finished) {
|
||
|
|
finished = true;
|
||
|
|
callback(err);
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
if (!processScheduled) {
|
||
|
|
processScheduled = true;
|
||
|
|
process.nextTick(processQueue);
|
||
|
|
}
|
||
|
|
};
|
||
|
|
|
||
|
|
const processQueue = () => {
|
||
|
|
if (finished) return;
|
||
|
|
while (processing < concurrency && queue.length > 0) {
|
||
|
|
processing++;
|
||
|
|
const item = queue.pop();
|
||
|
|
processor(item, push, processorCallback);
|
||
|
|
}
|
||
|
|
processScheduled = false;
|
||
|
|
if (queue.length === 0 && processing === 0 && !finished) {
|
||
|
|
finished = true;
|
||
|
|
callback();
|
||
|
|
}
|
||
|
|
};
|
||
|
|
|
||
|
|
processQueue();
|
||
|
|
};
|
||
|
|
|
||
|
|
module.exports = processAsyncTree;
|