webpack/lib/util/ParallelismFactorCalculator.js

Packs CommonJs/AMD modules for the browser. Allows to split your codebase into multiple bundles, which can be loaded on demand. Support loaders to preprocess files, i.e. json, jsx, es7, css, less, ... and your custom stuff.

/*
	MIT License http://www.opensource.org/licenses/mit-license.php
	Author Tobias Koppers @sokra
*/

"use strict";

const binarySearchBounds = require("../util/binarySearchBounds");

class ParallelismFactorCalculator {
	constructor() {
		this._rangePoints = [];
		this._rangeCallbacks = [];
	}

	range(start, end, callback) {
		if (start === end) return callback(1);
		this._rangePoints.push(start);
		this._rangePoints.push(end);
		this._rangeCallbacks.push(callback);
	}

	calculate() {
		const segments = Array.from(new Set(this._rangePoints)).sort((a, b) =>
			a < b ? -1 : 1
		);
		const parallelism = segments.map(() => 0);
		const rangeStartIndices = [];
		for (let i = 0; i < this._rangePoints.length; i += 2) {
			const start = this._rangePoints[i];
			const end = this._rangePoints[i + 1];
			let idx = binarySearchBounds.eq(segments, start);
			rangeStartIndices.push(idx);
			do {
				parallelism[idx]++;
				idx++;
			} while (segments[idx] < end);
		}
		for (let i = 0; i < this._rangeCallbacks.length; i++) {
			const start = this._rangePoints[i * 2];
			const end = this._rangePoints[i * 2 + 1];
			let idx = rangeStartIndices[i];
			let sum = 0;
			let totalDuration = 0;
			let current = start;
			do {
				const p = parallelism[idx];
				idx++;
				const duration = segments[idx] - current;
				totalDuration += duration;
				current = segments[idx];
				sum += p * duration;
			} while (current < end);
			this._rangeCallbacks[i](sum / totalDuration);
		}
	}
}

module.exports = ParallelismFactorCalculator;