144 lines
		
	
	
		
			4.1 KiB
		
	
	
	
		
			JavaScript
		
	
	
	
	
	
			
		
		
	
	
			144 lines
		
	
	
		
			4.1 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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const Cache = require("../Cache");
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/** @typedef {import("webpack-sources").Source} Source */
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/** @typedef {import("../Cache").Data} Data */
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/** @typedef {import("../Cache").Etag} Etag */
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/** @typedef {import("../Compiler")} Compiler */
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/** @typedef {import("../Module")} Module */
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/**
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 * @typedef {object} MemoryWithGcCachePluginOptions
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 * @property {number} maxGenerations max generations
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 */
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const PLUGIN_NAME = "MemoryWithGcCachePlugin";
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class MemoryWithGcCachePlugin {
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	/**
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	 * @param {MemoryWithGcCachePluginOptions} options options
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	 */
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	constructor({ maxGenerations }) {
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		this._maxGenerations = maxGenerations;
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	}
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	/**
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	 * Apply the plugin
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	 * @param {Compiler} compiler the compiler instance
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	 * @returns {void}
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	 */
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	apply(compiler) {
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		const maxGenerations = this._maxGenerations;
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		/** @type {Map<string, { etag: Etag | null, data: Data } | undefined | null>} */
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		const cache = new Map();
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		/** @type {Map<string, { entry: { etag: Etag | null, data: Data } | null, until: number }>} */
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		const oldCache = new Map();
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		let generation = 0;
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		let cachePosition = 0;
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		const logger = compiler.getInfrastructureLogger(PLUGIN_NAME);
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		compiler.hooks.afterDone.tap(PLUGIN_NAME, () => {
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			generation++;
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			let clearedEntries = 0;
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			let lastClearedIdentifier;
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			// Avoid coverage problems due indirect changes
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			/* istanbul ignore next */
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			for (const [identifier, entry] of oldCache) {
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				if (entry.until > generation) break;
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				oldCache.delete(identifier);
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				if (cache.get(identifier) === undefined) {
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					cache.delete(identifier);
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					clearedEntries++;
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					lastClearedIdentifier = identifier;
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				}
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			}
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			if (clearedEntries > 0 || oldCache.size > 0) {
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				logger.log(
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					`${cache.size - oldCache.size} active entries, ${
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						oldCache.size
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					} recently unused cached entries${
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						clearedEntries > 0
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							? `, ${clearedEntries} old unused cache entries removed e. g. ${lastClearedIdentifier}`
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							: ""
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					}`
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				);
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			}
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			let i = (cache.size / maxGenerations) | 0;
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			let j = cachePosition >= cache.size ? 0 : cachePosition;
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			cachePosition = j + i;
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			for (const [identifier, entry] of cache) {
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				if (j !== 0) {
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					j--;
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					continue;
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				}
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				if (entry !== undefined) {
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					// We don't delete the cache entry, but set it to undefined instead
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					// This reserves the location in the data table and avoids rehashing
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					// when constantly adding and removing entries.
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					// It will be deleted when removed from oldCache.
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					cache.set(identifier, undefined);
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					oldCache.delete(identifier);
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					oldCache.set(identifier, {
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						entry,
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						until: generation + maxGenerations
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					});
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					if (i-- === 0) break;
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				}
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			}
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		});
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		compiler.cache.hooks.store.tap(
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			{ name: PLUGIN_NAME, stage: Cache.STAGE_MEMORY },
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			(identifier, etag, data) => {
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				cache.set(identifier, { etag, data });
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			}
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		);
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		compiler.cache.hooks.get.tap(
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			{ name: PLUGIN_NAME, stage: Cache.STAGE_MEMORY },
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			(identifier, etag, gotHandlers) => {
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				const cacheEntry = cache.get(identifier);
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				if (cacheEntry === null) {
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					return null;
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				} else if (cacheEntry !== undefined) {
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					return cacheEntry.etag === etag ? cacheEntry.data : null;
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				}
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				const oldCacheEntry = oldCache.get(identifier);
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				if (oldCacheEntry !== undefined) {
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					const cacheEntry = oldCacheEntry.entry;
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					if (cacheEntry === null) {
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						oldCache.delete(identifier);
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						cache.set(identifier, cacheEntry);
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						return null;
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					}
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					if (cacheEntry.etag !== etag) return null;
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					oldCache.delete(identifier);
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					cache.set(identifier, cacheEntry);
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					return cacheEntry.data;
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				}
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				gotHandlers.push((result, callback) => {
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					if (result === undefined) {
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						cache.set(identifier, null);
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					} else {
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						cache.set(identifier, { etag, data: result });
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					}
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					return callback();
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				});
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			}
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		);
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		compiler.cache.hooks.shutdown.tap(
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			{ name: PLUGIN_NAME, stage: Cache.STAGE_MEMORY },
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			() => {
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				cache.clear();
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				oldCache.clear();
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			}
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		);
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	}
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}
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module.exports = MemoryWithGcCachePlugin;
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