Merge pull request #8468 from webpack/feature/chunk-root-modules

add algorithm to extract graph roots

declarations/WebpackOptions.d.ts

@@ -1267,6 +1267,10 @@ export interface StatsOptions {
 	 * add the origins of chunks and chunk merging info
 	 */
 	chunkOrigins?: boolean;
+	/**
+	 * add root modules information to chunk information
+	 */
+	chunkRootModules?: boolean;
 	/**
 	 * add chunk information
 	 */

lib/ChunkGraph.js

@@ -15,6 +15,7 @@ const {
 	compareSelect,
 	compareIds
 } = require("./util/comparators");
+const findGraphRoots = require("./util/findGraphRoots");
 
 /** @typedef {import("./AsyncDependenciesBlock")} AsyncDependenciesBlock */
 /** @typedef {import("./Chunk")} Chunk */
@@ -155,6 +156,8 @@ class ChunkGraph {
 		this._blockChunkGroups = new WeakMap();
 		/** @private @type {ModuleGraph} */
 		this.moduleGraph = moduleGraph;
+
+		this._getGraphRoots = this._getGraphRoots.bind(this);
 	}
 
 	/**
@@ -185,6 +188,25 @@ class ChunkGraph {
 		return c;
 	}
 
+	/**
+	 * @param {SortableSet<Module>} set the sortable Set to get the roots of
+	 * @returns {Module[]} the graph roots
+	 */
+	_getGraphRoots(set) {
+		const { moduleGraph } = this;
+		return Array.from(
+			findGraphRoots(set, module => {
+				return moduleGraph
+					.getOutgoingConnections(module)
+					.reduce((arr, connection) => {
+						const module = connection.module;
+						if (module) arr.push(module);
+						return arr;
+					}, []);
+			})
+		).sort(compareModulesByIdentifier);
+	}
+
 	/**
 	 * @param {Chunk} chunk the new chunk
 	 * @param {Module} module the module
@@ -534,6 +556,15 @@ class ChunkGraph {
 		return cgc.modules.getFromUnorderedCache(getModulesSizes);
 	}
 
+	/**
+	 * @param {Chunk} chunk the chunk
+	 * @returns {Module[]} root modules of the chunks (ordered by identifer)
+	 */
+	getChunkRootModules(chunk) {
+		const cgc = this._getChunkGraphChunk(chunk);
+		return cgc.modules.getFromUnorderedCache(this._getGraphRoots);
+	}
+
 	/**
 	 * @param {Chunk} chunk the chunk
 	 * @param {ChunkSizeOptions} options options object

lib/ModuleGraph.js

@@ -300,7 +300,7 @@ class ModuleGraph {
 	 * @param {Module} module the module
 	 * @returns {ModuleGraphConnection[]} list of outgoing connections
 	 */
-	getOutgoingConnection(module) {
+	getOutgoingConnections(module) {
 		const connections = this._getModuleGraphModule(module).outgoingConnections;
 		return Array.from(connections);
 	}

lib/Stats.js

@@ -170,7 +170,14 @@ class Stats {
 			!forToString
 		);
 		const showChunks = optionOrLocalFallback(options.chunks, !forToString);
-		const showChunkModules = optionOrLocalFallback(options.chunkModules, true);
+		const showChunkModules = optionOrLocalFallback(
+			options.chunkModules,
+			!forToString
+		);
+		const showChunkRootModules = optionOrLocalFallback(
+			options.chunkRootModules,
+			forToString ? !showChunkModules : true
+		);
 		const showChunkOrigins = optionOrLocalFallback(
 			options.chunkOrigins,
 			!forToString
@@ -178,7 +185,7 @@ class Stats {
 		const showModules = optionOrLocalFallback(options.modules, true);
 		const showNestedModules = optionOrLocalFallback(
 			options.nestedModules,
-			true
+			!forToString
 		);
 		const showOrphanModules = optionOrLocalFallback(
 			options.orphanModules,
@@ -793,6 +800,25 @@ class Stats {
 						);
 					}
 				}
+				if (showChunkRootModules) {
+					const rootModules = chunkGraph.getChunkRootModules(chunk);
+					obj.rootModules = rootModules
+						.slice()
+						.sort(sortRealModules)
+						.filter(createModuleFilter("root-of-chunk"))
+						.map(m => fnModule(m));
+					obj.filteredRootModules = rootModules.length - obj.rootModules.length;
+					obj.nonRootModules =
+						chunkGraph.getNumberOfChunkModules(chunk) - rootModules.length;
+					if (sortModules) {
+						obj.rootModules.sort(
+							concatComparators(
+								sortByField(sortModules),
+								keepOriginalOrder(obj.rootModules)
+							)
+						);
+					}
+				}
 				if (showChunkOrigins) {
 					const originsKeySet = new Set();
 					obj.origins = Array.from(chunk.groupsIterable, g => g.origins)
@@ -1059,7 +1085,7 @@ class Stats {
 						color: getAssetColor(asset, colors.normal)
 					},
 					{
-						value: asset.chunks.join(", "),
+						value: asset.chunks.map(c => `{${c}}`).join(", "),
 						color: colors.bold
 					},
 					{
@@ -1134,21 +1160,6 @@ class Stats {
 			processChunkGroups(outputChunkGroups, "Chunk Group");
 		}
 
-		const modulesByIdentifier = {};
-		if (obj.modules) {
-			for (const module of obj.modules) {
-				modulesByIdentifier[`$${module.identifier}`] = module;
-			}
-		} else if (obj.chunks) {
-			for (const chunk of obj.chunks) {
-				if (chunk.modules) {
-					for (const module of chunk.modules) {
-						modulesByIdentifier[`$${module.identifier}`] = module;
-					}
-				}
-			}
-		}
-
 		const processSizes = sizes => {
 			const keys = Object.keys(sizes);
 			if (keys.length > 1) {
@@ -1341,11 +1352,16 @@ class Stats {
 				newline();
 			}
 			if (module.modules) {
-				processModulesList(module, prefix + "| ");
+				processModulesList(module, prefix + "| ", "nested module");
 			}
 		};
 
-		const processModulesList = (obj, prefix) => {
+		const processModulesList = (
+			obj,
+			prefix,
+			itemType = "module",
+			dependentItemType = "dependent module"
+		) => {
 			if (obj.modules) {
 				let maxModuleId = 0;
 				for (const module of obj.modules) {
@@ -1397,7 +1413,19 @@ class Stats {
 					if (obj.modules.length > 0) colors.normal(" + ");
 					colors.normal(obj.filteredModules);
 					if (obj.modules.length > 0) colors.normal(" hidden");
-					colors.normal(obj.filteredModules !== 1 ? " modules" : " module");
+					colors.normal(` ${itemType}${obj.filteredModules !== 1 ? "s" : ""}`);
+					newline();
+				}
+				if (obj.dependentModules > 0) {
+					const additional = obj.modules.length > 0 || obj.filteredModules > 0;
+					colors.normal(prefix);
+					colors.normal("   ");
+					if (additional) colors.normal(" + ");
+					colors.normal(obj.dependentModules);
+					if (additional) colors.normal(" hidden");
+					colors.normal(
+						` ${dependentItemType}${obj.dependentModules !== 1 ? "s" : ""}`
+					);
 					newline();
 				}
 			}
@@ -1473,9 +1501,8 @@ class Stats {
 							colors.normal("[");
 							colors.normal(origin.moduleId);
 							colors.normal("] ");
-							const module = modulesByIdentifier[`$${origin.module}`];
-							if (module) {
-								colors.bold(module.name);
+							if (origin.moduleName) {
+								colors.bold(origin.moduleName);
 								colors.normal(" ");
 							}
 						}
@@ -1485,7 +1512,21 @@ class Stats {
 						newline();
 					}
 				}
-				processModulesList(chunk, " ");
+				const hasRootModules =
+					chunk.rootModules ||
+					chunk.filteredRootModules ||
+					chunk.nonRootModules;
+				processModulesList(
+					{
+						modules: chunk.rootModules,
+						filteredModules: chunk.filteredRootModules,
+						dependentModules: chunk.nonRootModules
+					},
+					" ",
+					"root module",
+					"dependent module"
+				);
+				processModulesList(chunk, hasRootModules ? " | " : " ", "chunk module");
 			}
 		}
 
@@ -1552,6 +1593,7 @@ class Stats {
 					modules: false,
 					chunks: true,
 					chunkModules: true,
+					chunkRootModules: false,
 					chunkOrigins: true,
 					depth: true,
 					env: true,
@@ -1572,6 +1614,7 @@ class Stats {
 					chunkGroups: true,
 					chunks: true,
 					chunkModules: false,
+					chunkRootModules: false,
 					chunkOrigins: true,
 					depth: true,
 					usedExports: true,

lib/util/findGraphRoots.js

@@ -0,0 +1,214 @@
+/*
+	MIT License http://www.opensource.org/licenses/mit-license.php
+	Author Tobias Koppers @sokra
+*/
+
+"use strict";
+
+const NO_MARKER = 0;
+const IN_PROGRESS_MARKER = 1;
+const DONE_MARKER = 2;
+const DONE_MAYBE_ROOT_CYCLE_MARKER = 3;
+const DONE_AND_ROOT_MARKER = 4;
+
+class Node {
+	constructor(item) {
+		this.item = item;
+		this.dependencies = new Set();
+		this.marker = NO_MARKER;
+		this.cycle = undefined;
+		this.incoming = 0;
+	}
+}
+
+class Cycle {
+	constructor() {
+		this.nodes = new Set();
+	}
+}
+
+/**
+ * @typedef {Object} StackEntry
+ * @property {Node} node
+ * @property {Node[]} openEdges
+ */
+
+/**
+ * @template T
+ * @param {Iterable<T>} items list of items
+ * @param {function(T): Iterable<T>} getDependencies function to get dependencies of an item (items that are not in list are ignored)
+ * @returns {Iterable<T>} graph roots of the items
+ */
+module.exports = (items, getDependencies) => {
+	const itemToNode = new Map();
+	for (const item of items) {
+		const node = new Node(item);
+		itemToNode.set(item, node);
+	}
+
+	// early exit when there is only a single item
+	if (itemToNode.size <= 1) return items;
+
+	// grab all the dependencies
+	for (const node of itemToNode.values()) {
+		for (const dep of getDependencies(node.item)) {
+			const depNode = itemToNode.get(dep);
+			if (depNode !== undefined) {
+				node.dependencies.add(depNode);
+			}
+		}
+	}
+
+	// Set of current root modules
+	// items will be removed if a new reference to it has been found
+	/** @type {Set<Node>} */
+	const roots = new Set();
+
+	// Set of current cycles without references to it
+	// cycles will be removed if a new reference to it has been found
+	// that is not part of the cycle
+	/** @type {Set<Cycle>} */
+	const rootCycles = new Set();
+
+	// For all non-marked nodes
+	for (const selectedNode of itemToNode.values()) {
+		if (selectedNode.marker === NO_MARKER) {
+			// deep-walk all referenced modules
+			// in a non-recursive way
+
+			// start by entering the selected node
+			selectedNode.marker = IN_PROGRESS_MARKER;
+
+			// keep a stack to avoid recursive walk
+			/** @type {StackEntry[]} */
+			const stack = [
+				{
+					node: selectedNode,
+					openEdges: Array.from(selectedNode.dependencies)
+				}
+			];
+
+			// process the top item until stack is empty
+			while (stack.length > 0) {
+				const topOfStack = stack[stack.length - 1];
+
+				// Are there still edges unprocessed in the current node?
+				if (topOfStack.openEdges.length > 0) {
+					// Process one dependency
+					const dependency = topOfStack.openEdges.pop();
+					switch (dependency.marker) {
+						case NO_MARKER:
+							// dependency has not be visited yet
+							// mark it as in-progress and recurse
+							stack.push({
+								node: dependency,
+								openEdges: Array.from(dependency.dependencies)
+							});
+							dependency.marker = IN_PROGRESS_MARKER;
+							break;
+						case IN_PROGRESS_MARKER: {
+							// It's a in-progress cycle
+							let cycle = dependency.cycle;
+							if (!cycle) {
+								cycle = new Cycle();
+								cycle.nodes.add(dependency);
+								dependency.cycle = cycle;
+							}
+							// set cycle property for each node in the cycle
+							// if nodes are already part of a cycle
+							// we merge the cycles to a shared cycle
+							for (
+								let i = stack.length - 1;
+								stack[i].node !== dependency;
+								i--
+							) {
+								const node = stack[i].node;
+								if (node.cycle) {
+									if (node.cycle !== cycle) {
+										// merge cycles
+										for (const cycleNode of node.cycle.nodes) {
+											cycleNode.cycle = cycle;
+											cycle.nodes.add(cycleNode);
+										}
+									}
+								} else {
+									node.cycle = cycle;
+									cycle.nodes.add(node);
+								}
+							}
+							// don't recurse into dependencies
+							// these are already on the stack
+							break;
+						}
+						case DONE_AND_ROOT_MARKER:
+							// This node has be visited yet and is currently a root node
+							// But as this is a new reference to the node
+							// it's not really a root
+							// so we have to convert it to a normal node
+							dependency.marker = DONE_MARKER;
+							roots.delete(dependency);
+							break;
+						case DONE_MAYBE_ROOT_CYCLE_MARKER:
+							// This node has be visited yet and
+							// is maybe currently part of a completed root cycle
+							// we found a new reference to the cycle
+							// so it's not really a root cycle
+							// remove the cycle from the root cycles
+							// and convert it to a normal node
+							rootCycles.delete(dependency.cycle);
+							dependency.marker = DONE_MARKER;
+							break;
+						// DONE_MARKER: nothing to do, don't recurse into dependencies
+					}
+				} else {
+					// All dependencies of the current node has been visited
+					// we leave the node
+					stack.pop();
+					topOfStack.node.marker = DONE_MARKER;
+				}
+			}
+			const cycle = selectedNode.cycle;
+			if (cycle) {
+				for (const node of cycle.nodes) {
+					node.marker = DONE_MAYBE_ROOT_CYCLE_MARKER;
+				}
+				rootCycles.add(cycle);
+			} else {
+				selectedNode.marker = DONE_AND_ROOT_MARKER;
+				roots.add(selectedNode);
+			}
+		}
+	}
+
+	// Extract roots from root cycles
+	// We take the nodes with most incoming edges
+	// inside of the cycle
+	for (const cycle of rootCycles) {
+		let max = 0;
+		const cycleRoots = new Set();
+		const nodes = cycle.nodes;
+		for (const node of nodes) {
+			for (const dep of node.dependencies) {
+				if (nodes.has(dep)) {
+					dep.incoming++;
+					if (dep.incoming < max) continue;
+					if (dep.incoming > max) {
+						cycleRoots.clear();
+						max = dep.incoming;
+					}
+					cycleRoots.add(dep);
+				}
+			}
+		}
+		for (const cycleRoot of cycleRoots) {
+			roots.add(cycleRoot);
+		}
+	}
+
+	// When roots were found, return them
+	if (roots.size > 0) {
+		return Array.from(roots, r => r.item);
+	} else {
+		throw new Error("Implementation of findGraphRoots is broken");
+	}
+};

schemas/WebpackOptions.json

@@ -1745,6 +1745,10 @@
           "description": "add the origins of chunks and chunk merging info",
           "type": "boolean"
         },
+        "chunkRootModules": {
+          "description": "add root modules information to chunk information",
+          "type": "boolean"
+        },
         "chunks": {
           "description": "add chunk information",
           "type": "boolean"

test/statsCases/graph-roots/cycle/a.js

@@ -0,0 +1 @@
+import "./b";

test/statsCases/graph-roots/cycle/b.js

@@ -0,0 +1 @@
+import "./c";

test/statsCases/graph-roots/cycle/c.js

@@ -0,0 +1 @@
+import "./index";

test/statsCases/graph-roots/cycle/index.js

@@ -0,0 +1 @@
+import "./a";

test/statsCases/graph-roots/cycle2/a.js

@@ -0,0 +1 @@
+import "./b";

test/statsCases/graph-roots/cycle2/b.js

@@ -0,0 +1,2 @@
+import "./c";
+import "./index";

test/statsCases/graph-roots/cycle2/c.js

@@ -0,0 +1 @@
+import "./index";

test/statsCases/graph-roots/cycle2/index.js

@@ -0,0 +1 @@
+import "./a";

test/statsCases/graph-roots/cycles/1/a.js

@@ -0,0 +1,2 @@
+import "./index";
+import "./b";

test/statsCases/graph-roots/cycles/1/b.js

@@ -0,0 +1 @@
+import "./c";

test/statsCases/graph-roots/cycles/1/c.js

@@ -0,0 +1 @@
+import "./index";

test/statsCases/graph-roots/cycles/1/index.js

@@ -0,0 +1 @@
+import "./a";

test/statsCases/graph-roots/cycles/2/a.js

@@ -0,0 +1 @@
+import "./b";

test/statsCases/graph-roots/cycles/2/b.js

@@ -0,0 +1,2 @@
+import "./c";
+import "./index";

test/statsCases/graph-roots/cycles/2/c.js

@@ -0,0 +1 @@
+import "./index";

test/statsCases/graph-roots/cycles/2/index.js

@@ -0,0 +1 @@
+import "./a";

test/statsCases/graph-roots/index.js

@@ -0,0 +1,12 @@
+import(/* webpackChunkName: "tree" */ "./tree");
+
+import(/* webpackChunkName: "trees" */ "./trees/1");
+import(/* webpackChunkName: "trees" */ "./trees/2");
+import(/* webpackChunkName: "trees" */ "./trees/3");
+
+import(/* webpackChunkName: "cycle" */ "./cycle");
+
+import(/* webpackChunkName: "cycle2" */ "./cycle2");
+
+import(/* webpackChunkName: "cycles" */ "./cycles/1");
+import(/* webpackChunkName: "cycles" */ "./cycles/2");

test/statsCases/graph-roots/tree/a.js

@@ -0,0 +1 @@
+import "./b";

test/statsCases/graph-roots/tree/b.js

@@ -0,0 +1 @@
+import "./c";

test/statsCases/graph-roots/tree/index.js

@@ -0,0 +1 @@
+import "./a";

test/statsCases/graph-roots/trees/1.js

@@ -0,0 +1 @@
+import "./a";

test/statsCases/graph-roots/trees/2.js

@@ -0,0 +1 @@
+import "./a";

test/statsCases/graph-roots/trees/3.js

@@ -0,0 +1 @@
+import "./b";

test/statsCases/graph-roots/trees/a.js

@@ -0,0 +1 @@
+import "./b";

test/statsCases/graph-roots/trees/b.js

@@ -0,0 +1 @@
+import "./c";

test/statsCases/graph-roots/webpack.config.js

@@ -0,0 +1,14 @@
+module.exports = {
+	mode: "development",
+	entry: "./index.js",
+	optimization: {
+		moduleIds: "natural",
+		chunkIds: "natural",
+		splitChunks: false
+	},
+	stats: {
+		all: false,
+		chunks: true,
+		chunkRootModules: true
+	}
+};