add direct memory cache

Author: sokra

lib/cache/FileCachePlugin.js

@@ -102,6 +102,7 @@ class FileCachePlugin {
 	 */
 	constructor(options) {
 		this.options = options;
+		this.directMemoryCache = new Map();
 	}
 
 	static purgeMemoryCache() {
@@ -179,6 +180,7 @@ class FileCachePlugin {
 				};
 				const relativeFilename = toHash(identifier) + ".data";
 				const filename = path.join(cacheDirectory, relativeFilename);
+				this.directMemoryCache.set(identifier, entry);
 				memoryCache.set(filename, entry);
 				const promiseFactory =
 					store === "pack"
@@ -221,6 +223,16 @@ class FileCachePlugin {
 		compiler.cache.hooks.get.tapPromise(
 			"FileCachePlugin",
 			(identifier, etag) => {
+				const directMemory = this.directMemoryCache.get(identifier);
+				if (directMemory !== undefined) {
+					return Promise.resolve(
+						directMemory.etag !== etag
+							? undefined
+							: typeof directMemory.data === "function"
+								? directMemory.data()
+								: directMemory.data
+					);
+				}
 				const relativeFilename = toHash(identifier) + ".data";
 				const filename = path.join(cacheDirectory, relativeFilename);
 				const logMessage = store === "pack" ? "pack" : filename;
@@ -243,6 +255,7 @@ class FileCachePlugin {
 						if (cacheEntry === undefined) return;
 						if (typeof cacheEntry.data === "function")
 							cacheEntry.data = memorize(cacheEntry.data);
+						this.directMemoryCache.set(identifier, cacheEntry);
 						memoryCache.set(filename, cacheEntry);
 						if (cacheEntry === undefined) return;
 						if (cacheEntry.identifier !== identifier) {