fix(perf): improve (#224)

Author: alexander-akait

lib/Hook.js

@@ -65,22 +65,45 @@ class Hook {
 
 	_tap(type, options, fn) {
 		if (typeof options === "string") {
-			options = {
-				name: options
-			};
-		} else if (typeof options !== "object" || options === null) {
-			throw new Error("Invalid tap options");
-		}
-		if (typeof options.name === "string") {
-			options.name = options.name.trim();
-		}
-		if (typeof options.name !== "string" || options.name === "") {
-			throw new Error("Missing name for tap");
-		}
-		if (typeof options.context !== "undefined") {
-			deprecateContext();
+			// Fast path: a string options ("name") is by far the most common
+			// case. Build the final descriptor in a single allocation instead
+			// of creating `{ name }` and then `Object.assign`ing it.
+			const name = options.trim();
+			if (name === "") {
+				throw new Error("Missing name for tap");
+			}
+			options = { type, fn, name };
+		} else {
+			if (typeof options !== "object" || options === null) {
+				throw new Error("Invalid tap options");
+			}
+			let { name } = options;
+			if (typeof name === "string") {
+				name = name.trim();
+			}
+			if (typeof name !== "string" || name === "") {
+				throw new Error("Missing name for tap");
+			}
+			if (typeof options.context !== "undefined") {
+				deprecateContext();
+			}
+			// Fast path: only `name` is set. Build the descriptor as a literal
+			// so `_insert` and downstream consumers see the same hidden class
+			// as the string-options path, avoiding a polymorphic call site.
+			if (
+				options.before === undefined &&
+				options.stage === undefined &&
+				options.context === undefined &&
+				options.type === undefined &&
+				options.fn === undefined
+			) {
+				options = { type, fn, name };
+			} else {
+				options.name = name;
+				// Preserve previous precedence: user-provided keys win over the internal `type`/`fn`.
+				options = Object.assign({ type, fn }, options);
+			}
 		}
-		options = Object.assign({ type, fn }, options);
 		options = this._runRegisterInterceptors(options);
 		this._insert(options);
 	}
@@ -98,7 +121,12 @@ class Hook {
 	}
 
 	_runRegisterInterceptors(options) {
-		for (const interceptor of this.interceptors) {
+		const { interceptors } = this;
+		const { length } = interceptors;
+		// Common case: no interceptors.
+		if (length === 0) return options;
+		for (let i = 0; i < length; i++) {
+			const interceptor = interceptors[i];
 			if (interceptor.register) {
 				const newOptions = interceptor.register(options);
 				if (newOptions !== undefined) {
@@ -146,21 +174,36 @@ class Hook {
 
 	_insert(item) {
 		this._resetCompilation();
+		const { taps } = this;
+		const stage = typeof item.stage === "number" ? item.stage : 0;
+
+		// Fast path: the overwhelmingly common `hook.tap("name", fn)` case
+		// has no `before` and default stage 0. If the list is empty or the
+		// last tap's stage is <= the new item's stage the item belongs at
+		// the end - append in O(1), skipping the Set allocation and the
+		// shift loop.
+		if (!(typeof item.before === "string" || Array.isArray(item.before))) {
+			const n = taps.length;
+			if (n === 0 || (taps[n - 1].stage || 0) <= stage) {
+				taps[n] = item;
+				return;
+			}
+		}
+
 		let before;
+
 		if (typeof item.before === "string") {
 			before = new Set([item.before]);
 		} else if (Array.isArray(item.before)) {
 			before = new Set(item.before);
 		}
-		let stage = 0;
-		if (typeof item.stage === "number") {
-			stage = item.stage;
-		}
-		let i = this.taps.length;
+
+		let i = taps.length;
+
 		while (i > 0) {
 			i--;
-			const tap = this.taps[i];
-			this.taps[i + 1] = tap;
+			const tap = taps[i];
+			taps[i + 1] = tap;
 			const xStage = tap.stage || 0;
 			if (before) {
 				if (before.has(tap.name)) {
@@ -177,7 +220,7 @@ class Hook {
 			i++;
 			break;
 		}
-		this.taps[i] = item;
+		taps[i] = item;
 	}
 }
 

lib/HookCodeFactory.js

@@ -77,20 +77,30 @@ class HookCodeFactory {
 	}
 
 	setup(instance, options) {
-		instance._x = options.taps.map((t) => t.fn);
+		const { taps } = options;
+		const { length } = taps;
+		const fns = Array.from({ length });
+		for (let i = 0; i < length; i++) {
+			fns[i] = taps[i].fn;
+		}
+		instance._x = fns;
 	}
 
 	/**
 	 * @param {{ type: "sync" | "promise" | "async", taps: Array<Tap>, interceptors: Array<Interceptor> }} options
 	 */
 	init(options) {
 		this.options = options;
-		this._args = [...options.args];
+		// slice() avoids the iterator protocol overhead of [...arr].
+		// eslint-disable-next-line unicorn/prefer-spread
+		this._args = options.args.slice();
+		this._joinedArgs = undefined;
 	}
 
 	deinit() {
 		this.options = undefined;
 		this._args = undefined;
+		this._joinedArgs = undefined;
 	}
 
 	contentWithInterceptors(options) {
@@ -165,7 +175,10 @@ class HookCodeFactory {
 	}
 
 	needContext() {
-		for (const tap of this.options.taps) if (tap.context) return true;
+		const { taps } = this.options;
+		for (let i = 0; i < taps.length; i++) {
+			if (taps[i].context) return true;
+		}
 		return false;
 	}
 
@@ -274,17 +287,30 @@ class HookCodeFactory {
 		doneReturns,
 		rethrowIfPossible
 	}) {
-		if (this.options.taps.length === 0) return onDone();
-		const firstAsync = this.options.taps.findIndex((t) => t.type !== "sync");
+		const { taps } = this.options;
+		const tapsLength = taps.length;
+		if (tapsLength === 0) return onDone();
+		// Inlined findIndex to avoid the callback allocation.
+		let firstAsync = -1;
+		for (let i = 0; i < tapsLength; i++) {
+			if (taps[i].type !== "sync") {
+				firstAsync = i;
+				break;
+			}
+		}
 		const somethingReturns = resultReturns || doneReturns;
+		// doneBreak doesn't depend on the loop variable - hoist to allocate once.
+		const doneBreak = (skipDone) => {
+			if (skipDone) return "";
+			return onDone();
+		};
 		let code = "";
 		let current = onDone;
 		let unrollCounter = 0;
-		for (let j = this.options.taps.length - 1; j >= 0; j--) {
+		for (let j = tapsLength - 1; j >= 0; j--) {
 			const i = j;
 			const unroll =
-				current !== onDone &&
-				(this.options.taps[i].type !== "sync" || unrollCounter++ > 20);
+				current !== onDone && (taps[i].type !== "sync" || unrollCounter++ > 20);
 			if (unroll) {
 				unrollCounter = 0;
 				code += `function _next${i}() {\n`;
@@ -293,10 +319,6 @@ class HookCodeFactory {
 				current = () => `${somethingReturns ? "return " : ""}_next${i}();\n`;
 			}
 			const done = current;
-			const doneBreak = (skipDone) => {
-				if (skipDone) return "";
-				return onDone();
-			};
 			const content = this.callTap(i, {
 				onError: (error) => onError(i, error, done, doneBreak),
 				onResult:
@@ -370,31 +392,35 @@ class HookCodeFactory {
 		rethrowIfPossible,
 		onTap = (i, run) => run()
 	}) {
-		if (this.options.taps.length <= 1) {
+		const { taps } = this.options;
+		const tapsLength = taps.length;
+		if (tapsLength <= 1) {
 			return this.callTapsSeries({
 				onError,
 				onResult,
 				onDone,
 				rethrowIfPossible
 			});
 		}
+		// done and doneBreak don't depend on the loop variable - hoist them
+		// so they're allocated once per compile instead of once per tap.
+		const done = () => {
+			if (onDone) return "if(--_counter === 0) _done();\n";
+			return "--_counter;";
+		};
+		const doneBreak = (skipDone) => {
+			if (skipDone || !onDone) return "_counter = 0;\n";
+			return "_counter = 0;\n_done();\n";
+		};
 		let code = "";
 		code += "do {\n";
-		code += `var _counter = ${this.options.taps.length};\n`;
+		code += `var _counter = ${tapsLength};\n`;
 		if (onDone) {
 			code += "var _done = (function() {\n";
 			code += onDone();
 			code += "});\n";
 		}
-		for (let i = 0; i < this.options.taps.length; i++) {
-			const done = () => {
-				if (onDone) return "if(--_counter === 0) _done();\n";
-				return "--_counter;";
-			};
-			const doneBreak = (skipDone) => {
-				if (skipDone || !onDone) return "_counter = 0;\n";
-				return "_counter = 0;\n_done();\n";
-			};
+		for (let i = 0; i < tapsLength; i++) {
 			code += "if(_counter <= 0) break;\n";
 			code += onTap(
 				i,
@@ -428,13 +454,22 @@ class HookCodeFactory {
 	}
 
 	args({ before, after } = {}) {
+		// Hot during code generation (called once per tap + per interceptor).
+		// Cache the common no-before/no-after result so we only join once.
+		if (before === undefined && after === undefined) {
+			let joined = this._joinedArgs;
+			if (joined === undefined) {
+				joined = this._args.length === 0 ? "" : this._args.join(", ");
+				this._joinedArgs = joined;
+			}
+			return joined;
+		}
 		let allArgs = this._args;
 		if (before) allArgs = [before, ...allArgs];
 		if (after) allArgs = [...allArgs, after];
 		if (allArgs.length === 0) {
 			return "";
 		}
-
 		return allArgs.join(", ");
 	}
 

lib/HookMap.js

@@ -21,7 +21,11 @@ class HookMap {
 	}
 
 	for(key) {
-		const hook = this.get(key);
+		// Hot path: inline the map lookup to skip the `this.get(key)`
+		// indirection. This gets hit on every hook access in consumers
+		// like webpack.
+		const map = this._map;
+		const hook = map.get(key);
 		if (hook !== undefined) {
 			return hook;
 		}
@@ -30,7 +34,7 @@ class HookMap {
 		for (let i = 0; i < interceptors.length; i++) {
 			newHook = interceptors[i].factory(key, newHook);
 		}
-		this._map.set(key, newHook);
+		map.set(key, newHook);
 		return newHook;
 	}
 

lib/MultiHook.js

@@ -11,33 +11,38 @@ class MultiHook {
 	}
 
 	tap(options, fn) {
-		for (const hook of this.hooks) {
-			hook.tap(options, fn);
+		const { hooks } = this;
+		for (let i = 0; i < hooks.length; i++) {
+			hooks[i].tap(options, fn);
 		}
 	}
 
 	tapAsync(options, fn) {
-		for (const hook of this.hooks) {
-			hook.tapAsync(options, fn);
+		const { hooks } = this;
+		for (let i = 0; i < hooks.length; i++) {
+			hooks[i].tapAsync(options, fn);
 		}
 	}
 
 	tapPromise(options, fn) {
-		for (const hook of this.hooks) {
-			hook.tapPromise(options, fn);
+		const { hooks } = this;
+		for (let i = 0; i < hooks.length; i++) {
+			hooks[i].tapPromise(options, fn);
 		}
 	}
 
 	isUsed() {
-		for (const hook of this.hooks) {
-			if (hook.isUsed()) return true;
+		const { hooks } = this;
+		for (let i = 0; i < hooks.length; i++) {
+			if (hooks[i].isUsed()) return true;
 		}
 		return false;
 	}
 
 	intercept(interceptor) {
-		for (const hook of this.hooks) {
-			hook.intercept(interceptor);
+		const { hooks } = this;
+		for (let i = 0; i < hooks.length; i++) {
+			hooks[i].intercept(interceptor);
 		}
 	}