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