[federation] Event Emitter fails to call all listener (#6267)

.changeset/flat-dragons-sparkle.md

@@ -0,0 +1,5 @@
+---
+'@graphql-tools/federation': minor
+---
+
+Add `delayInSeconds` to the `failure` event to give users more control on failure handling.

.changeset/gentle-snakes-worry.md

@@ -0,0 +1,6 @@
+---
+'@graphql-tools/federation': minor
+---
+
+Add a the ability to start polling with a delay. This ease the handling of failure handling,
+allowing to restart the manager and respecting GraphOS minimum retry delay.

.changeset/real-seals-laugh.md

@@ -0,0 +1,6 @@
+---
+'@graphql-tools/federation': patch
+---
+
+Fix Supergraph Manager Event Emitter not calling every listener when at least one has been
+registered using `once` method.

packages/federation/src/managed-federation.ts

@@ -306,7 +306,7 @@ export type SupergraphSchemaManagerOptions = Omit<
 export class SupergraphSchemaManager extends EventEmitter<{
   schema: [GraphQLSchema];
   error: [FetchError | unknown];
-  failure: [FetchError | unknown];
+  failure: [FetchError | unknown, number];
   log: [{ source: 'uplink' | 'manager'; message: string; level: 'error' | 'warn' | 'info' }];
 }> {
   public schema?: GraphQLSchema = undefined;
@@ -323,27 +323,34 @@ export class SupergraphSchemaManager extends EventEmitter<{
     });
   }
 
-  start() {
-    this.#log('info', 'Polling started');
-    this.#fetchSchema();
-  }
+  start = (delayInSeconds = 0) => {
+    if (this.#timeout) {
+      this.stop();
+    }
 
-  forcePull() {
-    this.#fetchSchema();
-    this.#retries = 1;
+    this.#timeout = setTimeout(() => {
+      this.#log('info', 'Polling started');
+      this.#retries = 1;
+      this.#fetchSchema();
+    }, delayInSeconds * 1000);
+  };
+
+  forcePull = () => {
     if (this.#timeout) {
       clearTimeout(this.#timeout);
       this.#timeout = undefined;
     }
-  }
+    this.#retries = 1;
+    this.#fetchSchema();
+  };
 
-  stop() {
+  stop = () => {
     this.#log('info', 'Polling stopped');
     if (this.#timeout) {
       clearTimeout(this.#timeout);
       this.#timeout = undefined;
     }
-  }
+  };
 
   #fetchSchema = async () => {
     const { retryDelaySeconds = 0, minDelaySeconds = 0 } = this.options;
@@ -387,11 +394,13 @@ export class SupergraphSchemaManager extends EventEmitter<{
 
   #retryOnError = (error: unknown, delayInSeconds: number) => {
     const { maxRetries = 3 } = this.options;
-    this.#log('error', 'Failed to pull schema from managed federation:');
+    const message = (error as { message: string })?.message;
+    this.#log('error', `Failed to pull schema from managed federation: ${message}`);
 
     if (this.#retries >= maxRetries) {
+      this.#timeout = undefined;
       this.#log('error', 'Max retries reached, giving up');
-      this.emit('failure', error);
+      this.emit('failure', error, delayInSeconds);
       return;
     }
 

packages/federation/src/utils.ts

@@ -200,8 +200,8 @@ export class EventEmitter<T extends EventMap<T>> {
     if (!listeners) {
       return false;
     }
-    for (const listener of listeners) {
-      listener(...args);
+    for (let i = listeners.length - 1; i >= 0; i--) {
+      listeners[i](...args);
     }
     return true;
   }

packages/federation/test/managed-federation.test.ts

@@ -144,6 +144,7 @@ describe('Managed Federation', () => {
     afterEach(() => {
       manager?.stop();
     });
+
     it('should allow to wait for initial schema load', async () => {
       manager = new SupergraphSchemaManager({
         fetch: mockSDL,
@@ -187,6 +188,20 @@ describe('Managed Federation', () => {
       expect(onSchemaChange).toHaveBeenCalledTimes(3);
     });
 
+    it('should call onSchemaChange for on and once listeners', async () => {
+      manager = new SupergraphSchemaManager({
+        fetch: mockSDL,
+      });
+
+      const onSchemaChange = jest.fn();
+      manager.once('schema', onSchemaChange);
+      manager.on('schema', onSchemaChange);
+      manager.start();
+
+      await delay(0.05);
+      expect(onSchemaChange).toHaveBeenCalledTimes(2);
+    });
+
     it('should retry on exceptions', async () => {
       manager = new SupergraphSchemaManager({
         fetch: mockError,

tsconfig.json

@@ -4,7 +4,7 @@
     "outDir": "dist",
     "baseUrl": ".",
 
-    "target": "es2021",
+    "target": "es2022",
     "module": "esnext",
     "moduleResolution": "node",
     "lib": ["esnext"],