fix(core) improve topological sorting performance

integration/hello-world/e2e/middleware-execute-order.spec.ts

@@ -47,7 +47,7 @@ describe('Middleware (execution order)', () => {
     await app.init();
   });
 
-  it(`should execute middleware of modules that are closer to the root module`, () => {
+  it(`should execute middleware in topological order`, () => {
     return request(app.getHttpServer())
       .get('/hello')
       .expect(200, RETURN_VALUE_B);

packages/core/injector/module.ts

@@ -120,13 +120,8 @@ export class Module {
     return this._distance;
   }
 
-  public updateDistance(distance: number, stack: Module[]) {
-    this._distance = distance;
-    Array.from(this._imports)
-      .filter(module => module && !stack.includes(this))
-      .forEach(module =>
-        module.updateDistance(distance + 1, stack.concat(this)),
-      );
+  set distance(value: number) {
+    this._distance = value;
   }
 
   public addCoreProviders(container: NestContainer) {
@@ -417,9 +412,6 @@ export class Module {
 
   public addRelatedModule(module: Module) {
     this._imports.add(module);
-    if (this._distance + 1 > module._distance) {
-      module.updateDistance(this._distance + 1, [this]);
-    }
   }
 
   public replace(toReplace: string | symbol | Type<any>, options: any) {

packages/core/middleware/middleware-module.ts

@@ -68,14 +68,15 @@ export class MiddlewareModule {
     modules: Map<string, Module>,
   ) {
     const moduleEntries = [...modules.entries()];
-    await Promise.all(
-      moduleEntries.map(async ([name, module]) => {
+    const loadMiddlewareConfiguration = async ([name, module]: [
+      string,
+      Module,
+    ]) => {
       const instance = module.instance;
-
       await this.loadConfiguration(middlewareContainer, instance, name);
       await this.resolver.resolveInstances(module, name);
-      }),
-    );
+    };
+    await Promise.all(moduleEntries.map(loadMiddlewareConfiguration));
   }
 
   public async loadConfiguration(

packages/core/middleware/resolver.ts

@@ -12,11 +12,9 @@ export class MiddlewareResolver {
     const middleware = this.middlewareContainer.getMiddlewareCollection(
       moduleName,
     );
-    await Promise.all(
-      [...middleware.values()].map(async wrapper =>
-        this.resolveMiddlewareInstance(wrapper, middleware, module),
-      ),
-    );
+    const resolveInstance = async (wrapper: InstanceWrapper) =>
+      this.resolveMiddlewareInstance(wrapper, middleware, module);
+    await Promise.all([...middleware.values()].map(resolveInstance));
   }
 
   private async resolveMiddlewareInstance(

packages/core/scanner.ts

@@ -36,6 +36,7 @@ import {
 import { ApplicationConfig } from './application-config';
 import { APP_FILTER, APP_GUARD, APP_INTERCEPTOR, APP_PIPE } from './constants';
 import { CircularDependencyException } from './errors/exceptions/circular-dependency.exception';
+import { ModulesContainer } from './injector';
 import { NestContainer } from './injector/container';
 import { InstanceWrapper } from './injector/instance-wrapper';
 import { Module } from './injector/module';
@@ -116,6 +117,7 @@ export class DependenciesScanner {
       this.reflectControllers(metatype, token);
       this.reflectExports(metatype, token);
     }
+    this.calculateModulesDistance(modules);
   }
 
   public async reflectImports(
@@ -251,6 +253,26 @@ export class DependenciesScanner {
     return undefined;
   }
 
+  public async calculateModulesDistance(modules: ModulesContainer) {
+    const modulesStack = [];
+    const modulesGenerator = modules.values();
+    const rootModule = modulesGenerator.next().value;
+
+    const calculateDistance = (moduleRef: Module, distance = 1) => {
+      if (modulesStack.includes(moduleRef)) {
+        return;
+      }
+      modulesStack.push(moduleRef);
+
+      const moduleImports = rootModule.relatedModules;
+      moduleImports.forEach(module => {
+        module.distance = distance;
+        calculateDistance(module, distance + 1);
+      });
+    };
+    calculateDistance(rootModule);
+  }
+
   public async insertImport(related: any, token: string, context: string) {
     if (isUndefined(related)) {
       throw new CircularDependencyException(context);

packages/core/test/injector/module.spec.ts

@@ -481,44 +481,4 @@ describe('Module', () => {
       });
     });
   });
-
-  describe('getter "distance"', () => {
-    @ModuleDecorator({})
-    class ModuleA {}
-
-    @ModuleDecorator({})
-    class ModuleB {}
-
-    @ModuleDecorator({})
-    class ModuleC {}
-
-    let moduleA, moduleB, moduleC;
-    beforeEach(() => {
-      moduleA = new Module(ModuleA as any, [], container);
-      moduleB = new Module(ModuleB as any, [], container);
-      moduleC = new Module(ModuleC as any, [], container);
-    });
-
-    it('should calculate "distance" properly', () => {
-      moduleA.addRelatedModule(moduleB);
-      moduleC.addRelatedModule(moduleB);
-      moduleA.addRelatedModule(moduleC);
-
-      expect(moduleA.distance).to.be.equal(0);
-      expect(moduleB.distance).to.be.equal(2);
-      expect(moduleC.distance).to.be.equal(1);
-    });
-
-    it('should not throw an exception when circular dependency occurs', () => {
-      expect(() => {
-        moduleA.addRelatedModule(moduleB);
-        moduleB.addRelatedModule(moduleA);
-      }).to.not.throw;
-      expect(() => {
-        moduleA.addRelatedModule(moduleB);
-        moduleB.addRelatedModule(moduleC);
-        moduleC.addRelatedModule(moduleA);
-      }).to.not.throw;
-    });
-  });
 });