perf(core): use topology tree for calculating distance

Author: kamilmysliwiec

packages/core/injector/topology-tree/topology-tree.ts

@@ -0,0 +1,60 @@
+import { Module } from '../module';
+import { TreeNode } from './tree-node';
+
+export class TopologyTree {
+  private root: TreeNode<Module>;
+  private links: Map<
+    Module,
+    {
+      node: TreeNode<Module>;
+      depth: number;
+    }
+  > = new Map();
+
+  static from(root: Module) {
+    const tree = new TopologyTree();
+    tree.root = new TreeNode<Module>({
+      value: root,
+      parent: null,
+    });
+
+    tree.traverseAndCloneTree(tree.root);
+    return tree;
+  }
+
+  public walk(callback: (value: Module, depth: number) => void) {
+    function walkNode(node: TreeNode<Module>, depth = 1) {
+      callback(node.value, depth);
+      node.children.forEach(child => walkNode(child, depth + 1));
+    }
+    walkNode(this.root);
+  }
+
+  private traverseAndCloneTree(node: TreeNode<Module>, depth = 1) {
+    node.value.imports.forEach(child => {
+      if (!child) {
+        return;
+      }
+      if (this.links.has(child)) {
+        const existingSubtree = this.links.get(child)!;
+        if (existingSubtree.depth < depth) {
+          existingSubtree.node.relink(node);
+          existingSubtree.depth = depth;
+        }
+        return;
+      }
+
+      const childNode = new TreeNode<Module>({
+        value: child,
+        parent: node,
+      });
+      node.addChild(childNode);
+      this.links.set(child, {
+        node: childNode,
+        depth,
+      });
+
+      this.traverseAndCloneTree(childNode, depth + 1);
+    });
+  }
+}

packages/core/injector/topology-tree/tree-node.ts

@@ -0,0 +1,23 @@
+export class TreeNode<T> {
+  public readonly value: T;
+  public readonly children = new Set<TreeNode<T>>();
+  private parent: TreeNode<T> | null;
+
+  constructor({ value, parent }: { value: T; parent: TreeNode<T> | null }) {
+    this.value = value;
+    this.parent = parent;
+  }
+
+  addChild(child: TreeNode<T>) {
+    this.children.add(child);
+  }
+
+  removeChild(child: TreeNode<T>) {
+    this.children.delete(child);
+  }
+
+  relink(parent: TreeNode<T>) {
+    this.parent = parent;
+    this.parent.addChild(this);
+  }
+}

packages/core/scanner.ts

@@ -50,6 +50,7 @@ import { NestContainer } from './injector/container';
 import { InstanceWrapper } from './injector/instance-wrapper';
 import { InternalCoreModuleFactory } from './injector/internal-core-module/internal-core-module-factory';
 import { Module } from './injector/module';
+import { TopologyTree } from './injector/topology-tree/topology-tree';
 import { GraphInspector } from './inspector/graph-inspector';
 import { UuidFactory } from './inspector/uuid-factory';
 import { ModuleDefinition } from './interfaces/module-definition.interface';
@@ -395,37 +396,19 @@ export class DependenciesScanner {
 
   public calculateModulesDistance() {
     const modulesGenerator = this.container.getModules().values();
-
     // Skip "InternalCoreModule" from calculating distance
     modulesGenerator.next();
 
-    const calculateDistance = (
-      moduleRef: Module,
-      distance = 1,
-      modulesStack: Module[] = [],
-    ) => {
-      const localModulesStack = [...modulesStack];
-      if (!moduleRef || localModulesStack.includes(moduleRef)) {
+    const rootModule = modulesGenerator.next().value!;
+
+    // Convert modules to an acyclic connected graph
+    const tree = TopologyTree.from(rootModule);
+    tree.walk((moduleRef, depth) => {
+      if (moduleRef.isGlobal) {
         return;
       }
-      localModulesStack.push(moduleRef);
-
-      const moduleImports = moduleRef.imports;
-      moduleImports.forEach(importedModuleRef => {
-        if (importedModuleRef) {
-          if (
-            distance > importedModuleRef.distance &&
-            !importedModuleRef.isGlobal
-          ) {
-            importedModuleRef.distance = distance;
-          }
-          calculateDistance(importedModuleRef, distance + 1, localModulesStack);
-        }
-      });
-    };
-
-    const rootModule = modulesGenerator.next().value;
-    calculateDistance(rootModule!);
+      moduleRef.distance = depth;
+    });
   }
 
   public async insertImport(related: any, token: string, context: string) {