use a Set for Module.chunks

lib/Compilation.js

@@ -507,7 +507,7 @@ class Compilation extends Tapable {
 				if(err) return callback(err);
 				deps.forEach(d => {
 					if(d.module && d.module.removeReason(module, d)) {
-						module.chunks.forEach(chunk => {
+						module.forEachChunk(chunk => {
 							if(!d.module.hasReasonForChunk(chunk)) {
 								if(d.module.removeChunk(chunk)) {
 									this.removeChunkFromDependencies(d.module, chunk);

lib/Module.js

@@ -4,6 +4,7 @@
 */
 "use strict";
 
+const util = require("util");
 const DependenciesBlock = require("./DependenciesBlock");
 const ModuleReason = require("./ModuleReason");
 const Template = require("./Template");
@@ -36,7 +37,9 @@ class Module extends DependenciesBlock {
 		this.used = null;
 		this.usedExports = null;
 		this.providedExports = null;
-		this.chunks = [];
+		this._chunks = new Set();
+		this._chunksIsSorted = true;
+		this._chunksDebugIdent = undefined;
 		this.warnings = [];
 		this.dependenciesWarnings = [];
 		this.errors = [];
@@ -55,7 +58,9 @@ class Module extends DependenciesBlock {
 		this.used = null;
 		this.usedExports = null;
 		this.providedExports = null;
-		this.chunks.length = 0;
+		this._chunks.clear();
+		this._chunksDebugIdent = undefined;
+		this._chunksIsSorted = false;
 		super.disconnect();
 	}
 
@@ -65,26 +70,74 @@ class Module extends DependenciesBlock {
 		this.index = null;
 		this.index2 = null;
 		this.depth = null;
-		this.chunks.length = 0;
+		this._chunks.clear();
+		this._chunksDebugIdent = undefined;
+		this._chunksIsSorted = false;
 		super.unseal();
 	}
 
 	addChunk(chunk) {
-		let idx = this.chunks.indexOf(chunk);
-		if(idx < 0)
-			this.chunks.push(chunk);
+		this._chunks.add(chunk);
+		this._chunksDebugIdent = undefined;
+		this._chunksIsSorted = false;
 	}
 
 	removeChunk(chunk) {
-		let idx = this.chunks.indexOf(chunk);
-		if(idx >= 0) {
-			this.chunks.splice(idx, 1);
+		if(this._chunks.delete(chunk)) {
+			this._chunksDebugIdent = undefined;
 			chunk.removeModule(this);
 			return true;
 		}
 		return false;
 	}
 
+	isInChunk(chunk) {
+		return this._chunks.has(chunk);
+	}
+
+	getChunkIdsIdent() {
+		if(this._chunksDebugIdent !== undefined) return this._chunksDebugIdent;
+		this._ensureChunksSorted();
+		const chunks = this._chunks;
+		const list = [];
+		for(let chunk of chunks) {
+			const debugId = chunk.debugId;
+
+			if(typeof debugId !== "number") {
+				return this._chunksDebugIdent = null;
+			}
+
+			list.push(debugId);
+		}
+
+		return this._chunksDebugIdent = list.join(",");
+	}
+
+	forEachChunk(fn) {
+		this._chunks.forEach(fn);
+	}
+
+	mapChunks(fn) {
+		const chunks = this._chunks;
+		const size = chunks.size;
+		const array = new Array(size);
+		let idx = 0;
+		for(let chunk of chunks) {
+			array[idx++] = fn(chunk, idx, chunks);
+		}
+		return array;
+	}
+
+	getNumberOfChunks() {
+		return this._chunks.size;
+	}
+
+	_ensureChunksSorted() {
+		if(this._chunksIsSorted) return;
+		this._chunks = new Set(Array.from(this._chunks).sort(byId));
+		this._chunksIsSorted = true;
+	}
+
 	addReason(module, dependency) {
 		this.reasons.push(new ModuleReason(module, dependency));
 	}
@@ -105,7 +158,7 @@ class Module extends DependenciesBlock {
 			if(r.chunks) {
 				if(r.chunks.indexOf(chunk) >= 0)
 					return true;
-			} else if(r.module.chunks.indexOf(chunk) >= 0)
+			} else if(r.module._chunks.has(chunk))
 				return true;
 		}
 		return false;
@@ -114,9 +167,9 @@ class Module extends DependenciesBlock {
 	rewriteChunkInReasons(oldChunk, newChunks) {
 		this.reasons.forEach(r => {
 			if(!r.chunks) {
-				if(r.module.chunks.indexOf(oldChunk) < 0)
+				if(!r.module._chunks.has(oldChunk))
 					return;
-				r.chunks = r.module.chunks;
+				r.chunks = Array.from(r.module._chunks);
 			}
 			r.chunks = r.chunks.reduce((arr, c) => {
 				addToSet(arr, c !== oldChunk ? [c] : newChunks);
@@ -160,7 +213,7 @@ class Module extends DependenciesBlock {
 
 	sortItems() {
 		super.sortItems();
-		this.chunks.sort(byId);
+		this._ensureChunksSorted();
 		this.reasons.sort((a, b) => byId(a.module, b.module));
 	}
 
@@ -178,6 +231,17 @@ Object.defineProperty(Module.prototype, "entry", {
 		throw new Error("Module.entry was removed. Use Chunk.entryModule");
 	}
 });
+
+Object.defineProperty(Module.prototype, "chunks", {
+	configurable: false,
+	get: util.deprecate(() => {
+		return Array.from(this._chunks);
+	}, "Module.chunks: Use Module.forEachChunk/mapChunks/getNumberOfChunks/isInChunk/addChunk/removeChunk instead"),
+	set() {
+		throw new Error("Readonly. Use Module.addChunk/removeChunk to modify chunks.");
+	}
+});
+
 Module.prototype.identifier = null;
 Module.prototype.readableIdentifier = null;
 Module.prototype.build = null;

lib/ModuleFilenameHelpers.js

@@ -112,7 +112,7 @@ ModuleFilenameHelpers.createFooter = function createFooter(module, requestShorte
 			"// WEBPACK FOOTER",
 			`// ${module.readableIdentifier(requestShortener)}`,
 			`// module id = ${module.id}`,
-			`// module chunks = ${module.chunks.map(c => c.id).join(" ")}`
+			`// module chunks = ${module.mapChunks(c => c.id).join(" ")}`
 		].join("\n");
 	}
 };

lib/Stats.js

@@ -279,7 +279,7 @@ class Stats {
 				built: !!module.built,
 				optional: !!module.optional,
 				prefetched: !!module.prefetched,
-				chunks: module.chunks.map(chunk => chunk.id),
+				chunks: module.mapChunks(chunk => chunk.id),
 				assets: Object.keys(module.assets || {}),
 				issuer: module.issuer && module.issuer.identifier(),
 				issuerId: module.issuer && module.issuer.id,

lib/optimize/OccurrenceOrderPlugin.js

@@ -16,12 +16,12 @@ class OccurrenceOrderPlugin {
 		compiler.plugin("compilation", (compilation) => {
 			compilation.plugin("optimize-module-order", (modules) => {
 				function entryChunks(m) {
-					return m.chunks.map((c) => {
+					let total = 0;
+					m.forEachChunk(c => {
 						const sum = (c.isInitial() ? 1 : 0) + (c.entryModule === m ? 1 : 0);
-						return sum;
-					}).reduce((a, b) => {
-						return a + b;
-					}, 0);
+						total += sum;
+					});
+					return total;
 				}
 
 				function occursInEntry(m) {
@@ -37,14 +37,17 @@ class OccurrenceOrderPlugin {
 
 				function occurs(m) {
 					if(typeof m.__OccurenceOrderPlugin_occurs === "number") return m.__OccurenceOrderPlugin_occurs;
+					let numberEntry = 0;
+					m.forEachChunk(c => {
+						if(c.entryModule === m)
+							numberEntry++;
+					});
 					const result = m.reasons.map((r) => {
 						if(!r.module) return 0;
-						return r.module.chunks.length;
+						return r.module.getNumberOfChunks();
 					}).reduce((a, b) => {
 						return a + b;
-					}, 0) + m.chunks.length + m.chunks.filter((c) => {
-						return c.entryModule === m;
-					}).length;
+					}, 0) + m.getNumberOfChunks() + numberEntry;
 					return m.__OccurenceOrderPlugin_occurs = result;
 				}
 				modules.sort((a, b) => {

lib/optimize/RemoveParentModulesPlugin.js

@@ -4,18 +4,8 @@
 */
 "use strict";
 
-function chunkContainsModule(chunk, module) {
-	const chunks = module.chunks;
-	const modules = chunk.modules;
-	if(chunks.length < modules.length) {
-		return chunks.indexOf(chunk) >= 0;
-	} else {
-		return modules.indexOf(module) >= 0;
-	}
-}
-
 function hasModule(chunk, module, checkedChunks) {
-	if(chunkContainsModule(chunk, module)) return [chunk];
+	if(module.isInChunk(chunk)) return [chunk];
 	if(chunk.parents.length === 0) return false;
 	return allHaveModule(chunk.parents.filter((c) => {
 		return checkedChunks.indexOf(c) < 0;
@@ -41,21 +31,6 @@ function allHaveModule(someChunks, module, checkedChunks) {
 	return chunks;
 }
 
-function debugIds(chunks) {
-	var list = [];
-	for(var i = 0; i < chunks.length; i++) {
-		var debugId = chunks[i].debugId;
-
-		if(typeof debugId !== "number") {
-			return "no";
-		}
-
-		list.push(debugId);
-	}
-
-	list.sort();
-	return list.join(",");
-}
 
 class RemoveParentModulesPlugin {
 	apply(compiler) {
@@ -71,9 +46,9 @@ class RemoveParentModulesPlugin {
 					for(var i = 0; i < modules.length; i++) {
 						var module = modules[i];
 
-						var dId = debugIds(module.chunks);
+						var dId = module.getChunkIdsIdent();
 						var parentChunksWithModule;
-						if((dId in cache) && dId !== "no") {
+						if(dId !== null && (dId in cache)) {
 							parentChunksWithModule = cache[dId];
 						} else {
 							parentChunksWithModule = cache[dId] = allHaveModule(chunk.parents, module);