webpack/lib/CachePlugin.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 asyncLib = require("neo-async");

class CachePlugin {
	constructor(cache) {
		this.cache = cache || {};
		this.FS_ACCURACY = 2000;
	}

	apply(compiler) {
		if (Array.isArray(compiler.compilers)) {
			compiler.compilers.forEach((c, idx) => {
				new CachePlugin((this.cache[idx] = this.cache[idx] || {})).apply(c);
			});
		} else {
			const registerCacheToCompiler = (compiler, cache) => {
				compiler.hooks.thisCompilation.tap("CachePlugin", compilation => {
					compilation.cache = cache;
					compilation.hooks.childCompiler.tap(
						"CachePlugin",
						(childCompiler, compilerName, compilerIndex) => {
							let childCache;
							if (!cache.children) {
								cache.children = {};
							}
							if (!cache.children[compilerName]) {
								cache.children[compilerName] = [];
							}
							if (cache.children[compilerName][compilerIndex]) {
								childCache = cache.children[compilerName][compilerIndex];
							} else {
								cache.children[compilerName].push((childCache = {}));
							}
							registerCacheToCompiler(childCompiler, childCache);
						}
					);
				});
			};
			registerCacheToCompiler(compiler, this.cache);
			compiler.hooks.watchRun.tap("CachePlugin", () => {
				this.watching = true;
			});
			compiler.hooks.run.tapAsync("CachePlugin", (compiler, callback) => {
				if (!compiler._lastCompilationFileDependencies) {
					return callback();
				}
				const fs = compiler.inputFileSystem;
				const fileTs = (compiler.fileTimestamps = new Map());
				asyncLib.forEach(
					compiler._lastCompilationFileDependencies,
					(file, callback) => {
						fs.stat(file, (err, stat) => {
							if (err) {
								if (err.code === "ENOENT") return callback();
								return callback(err);
							}

							if (stat.mtime) this.applyMtime(+stat.mtime);

							fileTs.set(file, +stat.mtime || Infinity);

							callback();
						});
					},
					err => {
						if (err) return callback(err);

						for (const [file, ts] of fileTs) {
							fileTs.set(file, ts + this.FS_ACCURACY);
						}

						callback();
					}
				);
			});
			compiler.hooks.afterCompile.tap("CachePlugin", compilation => {
				compilation.compiler._lastCompilationFileDependencies =
					compilation.fileDependencies;
				compilation.compiler._lastCompilationContextDependencies =
					compilation.contextDependencies;
			});
		}
	}

	/* istanbul ignore next */
	applyMtime(mtime) {
		if (this.FS_ACCURACY > 1 && mtime % 2 !== 0) this.FS_ACCURACY = 1;
		else if (this.FS_ACCURACY > 10 && mtime % 20 !== 0) this.FS_ACCURACY = 10;
		else if (this.FS_ACCURACY > 100 && mtime % 200 !== 0)
			this.FS_ACCURACY = 100;
		else if (this.FS_ACCURACY > 1000 && mtime % 2000 !== 0)
			this.FS_ACCURACY = 1000;
	}
}
module.exports = CachePlugin;