webpack/lib/Watching.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 Stats = require("./Stats");

/** @typedef {import("../declarations/WebpackOptions").WatchOptions} WatchOptions */
/** @typedef {import("./Compilation")} Compilation */
/** @typedef {import("./Compiler")} Compiler */
/** @typedef {import("./Stats")} Stats */

/**
 * @template T
 * @callback Callback
 * @param {Error=} err
 * @param {T=} result
 */

class Watching {
	/**
	 * @param {Compiler} compiler the compiler
	 * @param {WatchOptions} watchOptions options
	 * @param {Callback<Stats>} handler completion handler
	 */
	constructor(compiler, watchOptions, handler) {
		this.startTime = null;
		this.invalid = false;
		this.handler = handler;
		/** @type {Callback<void>[]} */
		this.callbacks = [];
		/** @type {Callback<void>[] | undefined} */
		this._closeCallbacks = undefined;
		this.closed = false;
		this.suspended = false;
		if (typeof watchOptions === "number") {
			this.watchOptions = {
				aggregateTimeout: watchOptions
			};
		} else if (watchOptions && typeof watchOptions === "object") {
			this.watchOptions = { ...watchOptions };
		} else {
			this.watchOptions = {};
		}
		if (typeof this.watchOptions.aggregateTimeout !== "number") {
			this.watchOptions.aggregateTimeout = 200;
		}
		this.compiler = compiler;
		this.running = true;
		this.watcher = undefined;
		this.pausedWatcher = undefined;
		this._done = this._done.bind(this);
		this.compiler.readRecords(err => {
			if (err) return this._done(err);

			this._go();
		});
	}

	_go() {
		this.startTime = Date.now();
		this.running = true;
		this.invalid = false;
		const run = () => {
			this.compiler.hooks.watchRun.callAsync(this.compiler, err => {
				if (err) return this._done(err);
				const onCompiled = (err, compilation) => {
					if (err) return this._done(err, compilation);
					if (this.invalid) return this._done();

					if (this.compiler.hooks.shouldEmit.call(compilation) === false) {
						return this._done(null, compilation);
					}

					process.nextTick(() => {
						const logger = compilation.getLogger("webpack.Compiler");
						logger.time("emitAssets");
						this.compiler.emitAssets(compilation, err => {
							logger.timeEnd("emitAssets");
							if (err) return this._done(err, compilation);
							if (this.invalid) return this._done(null, compilation);

							logger.time("emitRecords");
							this.compiler.emitRecords(err => {
								logger.timeEnd("emitRecords");
								if (err) return this._done(err, compilation);

								if (compilation.hooks.needAdditionalPass.call()) {
									compilation.needAdditionalPass = true;

									compilation.startTime = this.startTime;
									compilation.endTime = Date.now();
									logger.time("done hook");
									const stats = new Stats(compilation);
									this.compiler.hooks.done.callAsync(stats, err => {
										logger.timeEnd("done hook");
										if (err) return this._done(err, compilation);

										this.compiler.hooks.additionalPass.callAsync(err => {
											if (err) return this._done(err, compilation);
											this.compiler.compile(onCompiled);
										});
									});
									return;
								}
								return this._done(null, compilation);
							});
						});
					});
				};
				this.compiler.compile(onCompiled);
			});
		};

		if (this.compiler.idle) {
			this.compiler.cache.endIdle(err => {
				if (err) return this._done(err);
				this.compiler.idle = false;
				run();
			});
		} else {
			run();
		}
	}

	/**
	 * @param {Compilation} compilation the compilation
	 * @returns {Stats} the compilation stats
	 */
	_getStats(compilation) {
		const stats = new Stats(compilation);
		return stats;
	}

	/**
	 * @param {Error=} err an optional error
	 * @param {Compilation=} compilation the compilation
	 * @returns {void}
	 */
	_done(err, compilation) {
		this.running = false;

		const logger = compilation && compilation.getLogger("webpack.Watching");

		let stats = null;

		const handleError = err => {
			this.compiler.hooks.failed.call(err);
			this.compiler.cache.beginIdle();
			this.compiler.idle = true;
			this.handler(err, stats);
			for (const cb of this.callbacks) cb();
			this.callbacks.length = 0;
		};

		if (this.invalid) {
			if (compilation) {
				logger.time("storeBuildDependencies");
				this.compiler.cache.storeBuildDependencies(
					compilation.buildDependencies,
					err => {
						logger.timeEnd("storeBuildDependencies");
						if (err) return handleError(err);
						this._go();
					}
				);
			} else {
				this._go();
			}
			return;
		}

		if (compilation) {
			compilation.startTime = this.startTime;
			compilation.endTime = Date.now();
			stats = new Stats(compilation);
		}
		if (err) return handleError(err);

		logger.time("done hook");
		this.compiler.hooks.done.callAsync(stats, err => {
			logger.timeEnd("done hook");
			if (err) return handleError(err);
			this.handler(null, stats);
			logger.time("storeBuildDependencies");
			this.compiler.cache.storeBuildDependencies(
				compilation.buildDependencies,
				err => {
					logger.timeEnd("storeBuildDependencies");
					if (err) return handleError(err);
					logger.time("beginIdle");
					this.compiler.cache.beginIdle();
					this.compiler.idle = true;
					logger.timeEnd("beginIdle");
					process.nextTick(() => {
						if (!this.closed) {
							this.watch(
								compilation.fileDependencies,
								compilation.contextDependencies,
								compilation.missingDependencies
							);
						}
					});
					for (const cb of this.callbacks) cb();
					this.callbacks.length = 0;
					this.compiler.hooks.afterDone.call(stats);
				}
			);
		});
	}

	/**
	 * @param {Iterable<string>} files watched files
	 * @param {Iterable<string>} dirs watched directories
	 * @param {Iterable<string>} missing watched existence entries
	 * @returns {void}
	 */
	watch(files, dirs, missing) {
		this.pausedWatcher = null;
		this.watcher = this.compiler.watchFileSystem.watch(
			files,
			dirs,
			missing,
			this.startTime,
			this.watchOptions,
			(
				err,
				fileTimeInfoEntries,
				contextTimeInfoEntries,
				changedFiles,
				removedFiles
			) => {
				this.pausedWatcher = this.watcher;
				this.watcher = null;
				if (err) {
					this.compiler.modifiedFiles = undefined;
					this.compiler.removedFiles = undefined;
					this.compiler.fileTimestamps = undefined;
					this.compiler.contextTimestamps = undefined;
					return this.handler(err);
				}
				this.compiler.fileTimestamps = fileTimeInfoEntries;
				this.compiler.contextTimestamps = contextTimeInfoEntries;
				this.compiler.removedFiles = removedFiles;
				this.compiler.modifiedFiles = changedFiles;
				if (!this.suspended) {
					this._invalidate();
				}
			},
			(fileName, changeTime) => {
				this.compiler.hooks.invalid.call(fileName, changeTime);
			}
		);
	}

	/**
	 * @param {Callback<void>=} callback signals when the build has completed again
	 * @returns {void}
	 */
	invalidate(callback) {
		if (callback) {
			this.callbacks.push(callback);
		}
		if (this.watcher) {
			this.compiler.modifiedFiles = this.watcher.aggregatedChanges;
			this.compiler.removedFiles = this.watcher.aggregatedRemovals;
			this.compiler.fileTimestamps = this.watcher.getFileTimeInfoEntries();
			this.compiler.contextTimestamps = this.watcher.getContextTimeInfoEntries();
		}
		this.compiler.hooks.invalid.call(null, Date.now());
		this._invalidate();
	}

	_invalidate() {
		if (this.watcher) {
			this.pausedWatcher = this.watcher;
			this.watcher.pause();
			this.watcher = null;
		}

		if (this.running) {
			this.invalid = true;
		} else {
			this._go();
		}
	}

	suspend() {
		this.suspended = true;
		this.invalid = false;
	}

	resume() {
		if (this.suspended) {
			this.suspended = false;
			this._invalidate();
		}
	}

	/**
	 * @param {Callback<void>} callback signals when the watcher is closed
	 * @returns {void}
	 */
	close(callback) {
		if (this._closeCallbacks) {
			if (callback) {
				this._closeCallbacks.push(callback);
			}
			return;
		}
		const finalCallback = (err, compilation) => {
			this.running = false;
			this.compiler.running = false;
			this.compiler.watching = undefined;
			this.compiler.watchMode = false;
			this.compiler.modifiedFiles = undefined;
			this.compiler.removedFiles = undefined;
			this.compiler.fileTimestamps = undefined;
			this.compiler.contextTimestamps = undefined;
			const shutdown = () => {
				this.compiler.cache.shutdown(err => {
					this.compiler.hooks.watchClose.call();
					const closeCallbacks = this._closeCallbacks;
					this._closeCallbacks = undefined;
					for (const cb of closeCallbacks) cb(err);
				});
			};
			if (compilation) {
				const logger = compilation.getLogger("webpack.Watching");
				logger.time("storeBuildDependencies");
				this.compiler.cache.storeBuildDependencies(
					compilation.buildDependencies,
					err => {
						logger.timeEnd("storeBuildDependencies");
						shutdown();
					}
				);
			} else {
				shutdown();
			}
		};

		this.closed = true;
		if (this.watcher) {
			this.watcher.close();
			this.watcher = null;
		}
		if (this.pausedWatcher) {
			this.pausedWatcher.close();
			this.pausedWatcher = null;
		}
		this._closeCallbacks = [];
		if (callback) {
			this._closeCallbacks.push(callback);
		}
		if (this.running) {
			this.invalid = true;
			this._done = finalCallback;
		} else {
			finalCallback();
		}
	}
}

module.exports = Watching;