1 files changed, 135 insertions, 0 deletions
diff --git a/node_modules/webpack/lib/cache/MemoryWithGcCachePlugin.js b/node_modules/webpack/lib/cache/MemoryWithGcCachePlugin.js
new file mode 100644
index 00000000..ddfb80b1
--- /dev/null
+++ b/node_modules/webpack/lib/cache/MemoryWithGcCachePlugin.js
@@ -0,0 +1,135 @@
+/*
+	MIT License http://www.opensource.org/licenses/mit-license.php
+	Author Tobias Koppers @sokra
+*/
+
+"use strict";
+
+const Cache = require("../Cache");
+
+/** @typedef {import("webpack-sources").Source} Source */
+/** @typedef {import("../Cache").Etag} Etag */
+/** @typedef {import("../Compiler")} Compiler */
+/** @typedef {import("../Module")} Module */
+
+class MemoryWithGcCachePlugin {
+	/**
+	 * @param {object} options Options
+	 * @param {number} options.maxGenerations max generations
+	 */
+	constructor({ maxGenerations }) {
+		this._maxGenerations = maxGenerations;
+	}
+
+	/**
+	 * Apply the plugin
+	 * @param {Compiler} compiler the compiler instance
+	 * @returns {void}
+	 */
+	apply(compiler) {
+		const maxGenerations = this._maxGenerations;
+		/** @type {Map<string, { etag: Etag | null, data: any } | undefined | null>} */
+		const cache = new Map();
+		/** @type {Map<string, { entry: { etag: Etag | null, data: any } | null, until: number }>} */
+		const oldCache = new Map();
+		let generation = 0;
+		let cachePosition = 0;
+		const logger = compiler.getInfrastructureLogger("MemoryWithGcCachePlugin");
+		compiler.hooks.afterDone.tap("MemoryWithGcCachePlugin", () => {
+			generation++;
+			let clearedEntries = 0;
+			let lastClearedIdentifier;
+			// Avoid coverage problems due indirect changes
+			/* istanbul ignore next */
+			for (const [identifier, entry] of oldCache) {
+				if (entry.until > generation) break;
+
+				oldCache.delete(identifier);
+				if (cache.get(identifier) === undefined) {
+					cache.delete(identifier);
+					clearedEntries++;
+					lastClearedIdentifier = identifier;
+				}
+			}
+			if (clearedEntries > 0 || oldCache.size > 0) {
+				logger.log(
+					`${cache.size - oldCache.size} active entries, ${
+						oldCache.size
+					} recently unused cached entries${
+						clearedEntries > 0
+							? `, ${clearedEntries} old unused cache entries removed e. g. ${lastClearedIdentifier}`
+							: ""
+					}`
+				);
+			}
+			let i = (cache.size / maxGenerations) | 0;
+			let j = cachePosition >= cache.size ? 0 : cachePosition;
+			cachePosition = j + i;
+			for (const [identifier, entry] of cache) {
+				if (j !== 0) {
+					j--;
+					continue;
+				}
+				if (entry !== undefined) {
+					// We don't delete the cache entry, but set it to undefined instead
+					// This reserves the location in the data table and avoids rehashing
+					// when constantly adding and removing entries.
+					// It will be deleted when removed from oldCache.
+					cache.set(identifier, undefined);
+					oldCache.delete(identifier);
+					oldCache.set(identifier, {
+						entry,
+						until: generation + maxGenerations
+					});
+					if (i-- === 0) break;
+				}
+			}
+		});
+		compiler.cache.hooks.store.tap(
+			{ name: "MemoryWithGcCachePlugin", stage: Cache.STAGE_MEMORY },
+			(identifier, etag, data) => {
+				cache.set(identifier, { etag, data });
+			}
+		);
+		compiler.cache.hooks.get.tap(
+			{ name: "MemoryWithGcCachePlugin", stage: Cache.STAGE_MEMORY },
+			(identifier, etag, gotHandlers) => {
+				const cacheEntry = cache.get(identifier);
+				if (cacheEntry === null) {
+					return null;
+				} else if (cacheEntry !== undefined) {
+					return cacheEntry.etag === etag ? cacheEntry.data : null;
+				}
+				const oldCacheEntry = oldCache.get(identifier);
+				if (oldCacheEntry !== undefined) {
+					const cacheEntry = oldCacheEntry.entry;
+					if (cacheEntry === null) {
+						oldCache.delete(identifier);
+						cache.set(identifier, cacheEntry);
+						return null;
+					}
+					if (cacheEntry.etag !== etag) return null;
+					oldCache.delete(identifier);
+					cache.set(identifier, cacheEntry);
+					return cacheEntry.data;
+				}
+				gotHandlers.push((result, callback) => {
+					if (result === undefined) {
+						cache.set(identifier, null);
+					} else {
+						cache.set(identifier, { etag, data: result });
+					}
+					return callback();
+				});
+			}
+		);
+		compiler.cache.hooks.shutdown.tap(
+			{ name: "MemoryWithGcCachePlugin", stage: Cache.STAGE_MEMORY },
+			() => {
+				cache.clear();
+				oldCache.clear();
+			}
+		);
+	}
+}
+module.exports = MemoryWithGcCachePlugin;