webpack/lib/Cache.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 { AsyncParallelHook, AsyncSeriesBailHook, SyncHook } = require("tapable");
const {
	makeWebpackError,
	makeWebpackErrorCallback
} = require("./HookWebpackError");

/** @typedef {import("./WebpackError")} WebpackError */

/**
 * @typedef {Object} Etag
 * @property {function(): string} toString
 */

/**
 * @template T
 * @callback CallbackCache
 * @param {WebpackError=} err
 * @param {T=} result
 * @returns {void}
 */

/**
 * @callback GotHandler
 * @param {any} result
 * @param {function(Error=): void} callback
 * @returns {void}
 */

const needCalls = (times, callback) => {
	return err => {
		if (--times === 0) {
			return callback(err);
		}
		if (err && times > 0) {
			times = 0;
			return callback(err);
		}
	};
};

class Cache {
	constructor() {
		this.hooks = {
			/** @type {AsyncSeriesBailHook<[string, Etag | null, GotHandler[]], any>} */
			get: new AsyncSeriesBailHook(["identifier", "etag", "gotHandlers"]),
			/** @type {AsyncParallelHook<[string, Etag | null, any]>} */
			store: new AsyncParallelHook(["identifier", "etag", "data"]),
			/** @type {AsyncParallelHook<[Iterable<string>]>} */
			storeBuildDependencies: new AsyncParallelHook(["dependencies"]),
			/** @type {SyncHook<[]>} */
			beginIdle: new SyncHook([]),
			/** @type {AsyncParallelHook<[]>} */
			endIdle: new AsyncParallelHook([]),
			/** @type {AsyncParallelHook<[]>} */
			shutdown: new AsyncParallelHook([])
		};
	}

	/**
	 * @template T
	 * @param {string} identifier the cache identifier
	 * @param {Etag | null} etag the etag
	 * @param {CallbackCache<T>} callback signals when the value is retrieved
	 * @returns {void}
	 */
	get(identifier, etag, callback) {
		const gotHandlers = [];
		this.hooks.get.callAsync(identifier, etag, gotHandlers, (err, result) => {
			if (err) {
				callback(makeWebpackError(err, "Cache.hooks.get"));
				return;
			}
			if (result === null) {
				result = undefined;
			}
			if (gotHandlers.length > 1) {
				const innerCallback = needCalls(gotHandlers.length, () =>
					callback(null, result)
				);
				for (const gotHandler of gotHandlers) {
					gotHandler(result, innerCallback);
				}
			} else if (gotHandlers.length === 1) {
				gotHandlers[0](result, () => callback(null, result));
			} else {
				callback(null, result);
			}
		});
	}

	/**
	 * @template T
	 * @param {string} identifier the cache identifier
	 * @param {Etag | null} etag the etag
	 * @param {T} data the value to store
	 * @param {CallbackCache<void>} callback signals when the value is stored
	 * @returns {void}
	 */
	store(identifier, etag, data, callback) {
		this.hooks.store.callAsync(
			identifier,
			etag,
			data,
			makeWebpackErrorCallback(callback, "Cache.hooks.store")
		);
	}

	/**
	 * After this method has succeeded the cache can only be restored when build dependencies are
	 * @param {Iterable<string>} dependencies list of all build dependencies
	 * @param {CallbackCache<void>} callback signals when the dependencies are stored
	 * @returns {void}
	 */
	storeBuildDependencies(dependencies, callback) {
		this.hooks.storeBuildDependencies.callAsync(
			dependencies,
			makeWebpackErrorCallback(callback, "Cache.hooks.storeBuildDependencies")
		);
	}

	/**
	 * @returns {void}
	 */
	beginIdle() {
		this.hooks.beginIdle.call();
	}

	/**
	 * @param {CallbackCache<void>} callback signals when the call finishes
	 * @returns {void}
	 */
	endIdle(callback) {
		this.hooks.endIdle.callAsync(
			makeWebpackErrorCallback(callback, "Cache.hooks.endIdle")
		);
	}

	/**
	 * @param {CallbackCache<void>} callback signals when the call finishes
	 * @returns {void}
	 */
	shutdown(callback) {
		this.hooks.shutdown.callAsync(
			makeWebpackErrorCallback(callback, "Cache.hooks.shutdown")
		);
	}
}

Cache.STAGE_MEMORY = -10;
Cache.STAGE_DEFAULT = 0;
Cache.STAGE_DISK = 10;
Cache.STAGE_NETWORK = 20;

module.exports = Cache;