webpack/lib/debug/ProfilingPlugin.js

Packs ECMAScript/CommonJs/AMD modules for the browser. Allows you to split your codebase into multiple bundles, which can be loaded on demand. Supports 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
*/

"use strict";

const { Tracer } = require("chrome-trace-event");
const {
	CSS_MODULES,
	JAVASCRIPT_MODULES,
	JSON_MODULE_TYPE,
	WEBASSEMBLY_MODULES
} = require("../ModuleTypeConstants");
const { dirname, mkdirpSync } = require("../util/fs");

/** @typedef {import("inspector").Session} Session */
/** @typedef {import("tapable").FullTap} FullTap */
/** @typedef {import("../../declarations/plugins/debug/ProfilingPlugin").ProfilingPluginOptions} ProfilingPluginOptions */
/** @typedef {import("../Compilation")} Compilation */
/** @typedef {import("../Compiler")} Compiler */
/** @typedef {import("../NormalModuleFactory")} NormalModuleFactory */
/** @typedef {import("../ResolverFactory")} ResolverFactory */
/** @typedef {import("../util/fs").IntermediateFileSystem} IntermediateFileSystem */

/**
 * Defines the hook type used by this module.
 * @template T, R
 * @typedef {import("tapable").Hook<T, R>} Hook
 */

/**
 * Defines the fake hook type used by this module.
 * @template T
 * @typedef {import("../util/deprecation").FakeHook<T>} FakeHook
 */

/**
 * Defines the hook map type used by this module.
 * @template T
 * @typedef {import("tapable").HookMap<T>} HookMap
 */

/**
 * Defines the hook interceptor type used by this module.
 * @template T, R
 * @typedef {import("tapable").HookInterceptor<T, R>} HookInterceptor
 */

/** @typedef {{ Session: typeof import("inspector").Session }} Inspector */

/** @type {Inspector | undefined} */
let inspector;

try {
	// eslint-disable-next-line n/no-unsupported-features/node-builtins
	inspector = require("inspector");
} catch (_err) {
	// eslint-disable-next-line no-console
	console.log("Unable to CPU profile in < node 8.0");
}

class Profiler {
	/**
	 * Creates an instance of Profiler.
	 * @param {Inspector} inspector inspector
	 */
	constructor(inspector) {
		/** @type {undefined | Session} */
		this.session = undefined;
		this.inspector = inspector;
		this._startTime = 0;
	}

	hasSession() {
		return this.session !== undefined;
	}

	startProfiling() {
		if (this.inspector === undefined) {
			return Promise.resolve();
		}

		try {
			this.session = new /** @type {Inspector} */ (inspector).Session();
			/** @type {Session} */
			(this.session).connect();
		} catch (_) {
			this.session = undefined;
			return Promise.resolve();
		}

		const hrtime = process.hrtime();
		this._startTime = hrtime[0] * 1000000 + Math.round(hrtime[1] / 1000);

		return Promise.all([
			this.sendCommand("Profiler.setSamplingInterval", {
				interval: 100
			}),
			this.sendCommand("Profiler.enable"),
			this.sendCommand("Profiler.start")
		]);
	}

	/**
	 * Returns promise for the result.
	 * @param {string} method method name
	 * @param {EXPECTED_OBJECT=} params params
	 * @returns {Promise<EXPECTED_ANY | void>} Promise for the result
	 */
	sendCommand(method, params) {
		if (this.hasSession()) {
			return new Promise((res, rej) => {
				/** @type {Session} */
				(this.session).post(method, params, (err, params) => {
					if (err !== null) {
						rej(err);
					} else {
						res(params);
					}
				});
			});
		}
		return Promise.resolve();
	}

	destroy() {
		if (this.hasSession()) {
			/** @type {Session} */
			(this.session).disconnect();
		}

		return Promise.resolve();
	}

	/**
	 * Returns }>} profile result.
	 * @returns {Promise<{ profile: { startTime: number, endTime: number } }>} profile result
	 */
	stopProfiling() {
		return this.sendCommand("Profiler.stop").then(({ profile }) => {
			const hrtime = process.hrtime();
			const endTime = hrtime[0] * 1000000 + Math.round(hrtime[1] / 1000);
			// Avoid coverage problems due indirect changes
			/* istanbul ignore next */
			if (profile.startTime < this._startTime || profile.endTime > endTime) {
				// In some cases timestamps mismatch and we need to adjust them
				// Both process.hrtime and the inspector timestamps claim to be relative
				// to a unknown point in time. But they do not guarantee that this is the
				// same point in time.
				const duration = profile.endTime - profile.startTime;
				const ownDuration = endTime - this._startTime;
				const untracked = Math.max(0, ownDuration - duration);
				profile.startTime = this._startTime + untracked / 2;
				profile.endTime = endTime - untracked / 2;
			}
			return { profile };
		});
	}
}

/**
 * an object that wraps Tracer and Profiler with a counter
 * @typedef {object} Trace
 * @property {Tracer} trace instance of Tracer
 * @property {number} counter Counter
 * @property {Profiler} profiler instance of Profiler
 * @property {(callback: (err?: null | Error) => void) => void} end the end function
 */

/**
 * Creates a trace from the provided f.
 * @param {IntermediateFileSystem} fs filesystem used for output
 * @param {string} outputPath The location where to write the log.
 * @returns {Trace} The trace object
 */
const createTrace = (fs, outputPath) => {
	const trace = new Tracer();
	const profiler = new Profiler(/** @type {Inspector} */ (inspector));
	if (/\/|\\/.test(outputPath)) {
		const dirPath = dirname(fs, outputPath);
		mkdirpSync(fs, dirPath);
	}
	const fsStream = fs.createWriteStream(outputPath);

	let counter = 0;

	trace.pipe(fsStream);
	// These are critical events that need to be inserted so that tools like
	// chrome dev tools can load the profile.
	trace.instantEvent({
		name: "TracingStartedInPage",
		id: ++counter,
		cat: ["disabled-by-default-devtools.timeline"],
		args: {
			data: {
				sessionId: "-1",
				page: "0xfff",
				frames: [
					{
						frame: "0xfff",
						url: "webpack",
						name: ""
					}
				]
			}
		}
	});

	trace.instantEvent({
		name: "TracingStartedInBrowser",
		id: ++counter,
		cat: ["disabled-by-default-devtools.timeline"],
		args: {
			data: {
				sessionId: "-1"
			}
		}
	});

	return {
		trace,
		counter,
		profiler,
		end: (callback) => {
			trace.push("]");
			// Wait until the write stream finishes.
			fsStream.on("close", () => {
				callback();
			});
			// Tear down the readable trace stream.
			trace.push(null);
		}
	};
};

const PLUGIN_NAME = "ProfilingPlugin";

class ProfilingPlugin {
	/**
	 * Creates an instance of ProfilingPlugin.
	 * @param {ProfilingPluginOptions=} options options object
	 */
	constructor(options = {}) {
		/** @type {ProfilingPluginOptions} */
		this.options = options;
	}

	/**
	 * Applies the plugin by registering its hooks on the compiler.
	 * @param {Compiler} compiler the compiler instance
	 * @returns {void}
	 */
	apply(compiler) {
		compiler.hooks.validate.tap(PLUGIN_NAME, () => {
			compiler.validate(
				() => require("../../schemas/plugins/debug/ProfilingPlugin.json"),
				this.options,
				{
					name: "Profiling Plugin",
					baseDataPath: "options"
				},
				(options) =>
					require("../../schemas/plugins/debug/ProfilingPlugin.check")(options)
			);
		});

		const tracer = createTrace(
			/** @type {IntermediateFileSystem} */
			(compiler.intermediateFileSystem),
			this.options.outputPath || "events.json"
		);
		tracer.profiler.startProfiling();

		// Compiler Hooks
		for (const hookName of Object.keys(compiler.hooks)) {
			const hook =
				compiler.hooks[/** @type {keyof Compiler["hooks"]} */ (hookName)];
			if (hook) {
				hook.intercept(makeInterceptorFor("Compiler", tracer)(hookName));
			}
		}

		for (const hookName of Object.keys(compiler.resolverFactory.hooks)) {
			const hook =
				compiler.resolverFactory.hooks[
					/** @type {keyof ResolverFactory["hooks"]} */
					(hookName)
				];
			if (hook) {
				hook.intercept(
					/** @type {EXPECTED_ANY} */
					(makeInterceptorFor("Resolver", tracer)(hookName))
				);
			}
		}

		compiler.hooks.compilation.tap(
			PLUGIN_NAME,
			(compilation, { normalModuleFactory, contextModuleFactory }) => {
				interceptAllHooksFor(compilation, tracer, "Compilation");
				interceptAllHooksFor(
					normalModuleFactory,
					tracer,
					"Normal Module Factory"
				);
				interceptAllHooksFor(
					contextModuleFactory,
					tracer,
					"Context Module Factory"
				);
				interceptAllParserHooks(normalModuleFactory, tracer);
				interceptAllGeneratorHooks(normalModuleFactory, tracer);
				interceptAllJavascriptModulesPluginHooks(compilation, tracer);
				interceptAllCssModulesPluginHooks(compilation, tracer);
			}
		);

		// We need to write out the CPU profile when we are all done.
		compiler.hooks.done.tapAsync(
			{
				name: PLUGIN_NAME,
				stage: Infinity
			},
			(stats, callback) => {
				if (compiler.watchMode) return callback();
				tracer.profiler.stopProfiling().then((parsedResults) => {
					if (parsedResults === undefined) {
						tracer.profiler.destroy();
						tracer.end(callback);
						return;
					}

					const cpuStartTime = parsedResults.profile.startTime;
					const cpuEndTime = parsedResults.profile.endTime;

					tracer.trace.completeEvent({
						name: "TaskQueueManager::ProcessTaskFromWorkQueue",
						id: ++tracer.counter,
						cat: ["toplevel"],
						ts: cpuStartTime,
						args: {
							// eslint-disable-next-line camelcase
							src_file: "../../ipc/ipc_moji_bootstrap.cc",
							// eslint-disable-next-line camelcase
							src_func: "Accept"
						}
					});

					tracer.trace.completeEvent({
						name: "EvaluateScript",
						id: ++tracer.counter,
						cat: ["devtools.timeline"],
						ts: cpuStartTime,
						dur: cpuEndTime - cpuStartTime,
						args: {
							data: {
								url: "webpack",
								lineNumber: 1,
								columnNumber: 1,
								frame: "0xFFF"
							}
						}
					});

					tracer.trace.instantEvent({
						name: "CpuProfile",
						id: ++tracer.counter,
						cat: ["disabled-by-default-devtools.timeline"],
						ts: cpuEndTime,
						args: {
							data: {
								cpuProfile: parsedResults.profile
							}
						}
					});

					tracer.profiler.destroy();
					tracer.end(callback);
				});
			}
		);
	}
}

/** @typedef {Record<string, Hook<EXPECTED_ANY, EXPECTED_ANY> | FakeHook<EXPECTED_ANY> | HookMap<EXPECTED_ANY>>} Hooks */

/**
 * Intercept all hooks for.
 * @param {EXPECTED_OBJECT & { hooks?: Hooks }} instance instance
 * @param {Trace} tracer tracer
 * @param {string} logLabel log label
 */
const interceptAllHooksFor = (instance, tracer, logLabel) => {
	if (Reflect.has(instance, "hooks")) {
		const hooks = /** @type {Hooks} */ (instance.hooks);
		for (const hookName of Object.keys(hooks)) {
			const hook = hooks[hookName];
			if (hook && !hook._fakeHook) {
				hook.intercept(makeInterceptorFor(logLabel, tracer)(hookName));
			}
		}
	}
};

/**
 * Intercept all parser hooks.
 * @param {NormalModuleFactory} moduleFactory normal module factory
 * @param {Trace} tracer tracer
 */
const interceptAllParserHooks = (moduleFactory, tracer) => {
	const moduleTypes = [
		...JAVASCRIPT_MODULES,
		JSON_MODULE_TYPE,
		...WEBASSEMBLY_MODULES,
		...CSS_MODULES
	];

	for (const moduleType of moduleTypes) {
		moduleFactory.hooks.parser
			.for(moduleType)
			.tap(PLUGIN_NAME, (parser, _parserOpts) => {
				interceptAllHooksFor(parser, tracer, "Parser");
			});
	}
};

/**
 * Intercept all generator hooks.
 * @param {NormalModuleFactory} moduleFactory normal module factory
 * @param {Trace} tracer tracer
 */
const interceptAllGeneratorHooks = (moduleFactory, tracer) => {
	const moduleTypes = [
		...JAVASCRIPT_MODULES,
		JSON_MODULE_TYPE,
		...WEBASSEMBLY_MODULES,
		...CSS_MODULES
	];

	for (const moduleType of moduleTypes) {
		moduleFactory.hooks.generator
			.for(moduleType)
			.tap(PLUGIN_NAME, (parser, _parserOpts) => {
				interceptAllHooksFor(parser, tracer, "Generator");
			});
	}
};

/**
 * Intercept all javascript modules plugin hooks.
 * @param {Compilation} compilation compilation
 * @param {Trace} tracer tracer
 */
const interceptAllJavascriptModulesPluginHooks = (compilation, tracer) => {
	interceptAllHooksFor(
		{
			hooks:
				require("../javascript/JavascriptModulesPlugin").getCompilationHooks(
					compilation
				)
		},
		tracer,
		"JavascriptModulesPlugin"
	);
};

/**
 * Intercept all css modules plugin hooks.
 * @param {Compilation} compilation compilation
 * @param {Trace} tracer tracer
 */
const interceptAllCssModulesPluginHooks = (compilation, tracer) => {
	interceptAllHooksFor(
		{
			hooks: require("../css/CssModulesPlugin").getCompilationHooks(compilation)
		},
		tracer,
		"CssModulesPlugin"
	);
};

/** @typedef {(...args: EXPECTED_ANY[]) => EXPECTED_ANY | Promise<(...args: EXPECTED_ANY[]) => EXPECTED_ANY>} PluginFunction */

/**
 * Creates interceptor for.
 * @template T
 * @param {string} instance instance
 * @param {Trace} tracer tracer
 * @returns {(hookName: string) => HookInterceptor<EXPECTED_ANY, EXPECTED_ANY>} interceptor
 */
const makeInterceptorFor = (instance, tracer) => (hookName) => ({
	/**
	 * Returns modified full tap.
	 * @param {FullTap} tapInfo tap info
	 * @returns {FullTap} modified full tap
	 */
	register: (tapInfo) => {
		const { name, type, fn: internalFn } = tapInfo;
		const newFn =
			// Don't tap our own hooks to ensure stream can close cleanly
			name === PLUGIN_NAME
				? internalFn
				: makeNewProfiledTapFn(hookName, tracer, {
						name,
						type,
						fn: /** @type {PluginFunction} */ (internalFn)
					});
		return { ...tapInfo, fn: newFn };
	}
});

/**
 * Creates new profiled tap fn.
 * @param {string} hookName Name of the hook to profile.
 * @param {Trace} tracer The trace object.
 * @param {object} options Options for the profiled fn.
 * @param {string} options.name Plugin name
 * @param {"sync" | "async" | "promise"} options.type Plugin type (sync | async | promise)
 * @param {PluginFunction} options.fn Plugin function
 * @returns {PluginFunction} Chainable hooked function.
 */
const makeNewProfiledTapFn = (hookName, tracer, { name, type, fn }) => {
	const defaultCategory = ["blink.user_timing"];

	switch (type) {
		case "promise":
			return (...args) => {
				const id = ++tracer.counter;
				tracer.trace.begin({
					name,
					id,
					cat: defaultCategory
				});
				const promise =
					/** @type {Promise<(...args: EXPECTED_ANY[]) => EXPECTED_ANY>} */
					(fn(...args));
				return promise.then((r) => {
					tracer.trace.end({
						name,
						id,
						cat: defaultCategory
					});
					return r;
				});
			};
		case "async":
			return (...args) => {
				const id = ++tracer.counter;
				tracer.trace.begin({
					name,
					id,
					cat: defaultCategory
				});
				const callback = args.pop();
				fn(
					...args,
					/**
					 * Handles the cat callback for this hook.
					 * @param {...EXPECTED_ANY[]} r result
					 */
					(...r) => {
						tracer.trace.end({
							name,
							id,
							cat: defaultCategory
						});
						callback(...r);
					}
				);
			};
		case "sync":
			return (...args) => {
				const id = ++tracer.counter;
				// Do not instrument ourself due to the CPU
				// profile needing to be the last event in the trace.
				if (name === PLUGIN_NAME) {
					return fn(...args);
				}

				tracer.trace.begin({
					name,
					id,
					cat: defaultCategory
				});
				/** @type {PluginFunction} */
				let r;
				try {
					r = fn(...args);
				} catch (err) {
					tracer.trace.end({
						name,
						id,
						cat: defaultCategory
					});
					throw err;
				}
				tracer.trace.end({
					name,
					id,
					cat: defaultCategory
				});
				return r;
			};
		default:
			return fn;
	}
};

module.exports = ProfilingPlugin;
module.exports.Profiler = Profiler;