From 6ee6204bc4fb840f0c5ee1734183daa1b39e4574 Mon Sep 17 00:00:00 2001
From: Jonathan Edey <jedey@google.com>
Date: Mon, 29 Jul 2024 10:48:12 -0400
Subject: [PATCH 1/2] fix:  returns existing promise to a token if one exists
 instead of a new token.

---
 src/app/firebase-app.ts            | 16 +++++++++++-----
 test/integration/messaging.spec.ts |  2 +-
 test/unit/app/firebase-app.spec.ts | 10 ++++++++++
 3 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/src/app/firebase-app.ts b/src/app/firebase-app.ts
index 4dd97cb33d..b0696dc590 100644
--- a/src/app/firebase-app.ts
+++ b/src/app/firebase-app.ts
@@ -39,19 +39,21 @@ export interface FirebaseAccessToken {
  */
 export class FirebaseAppInternals {
   private cachedToken_: FirebaseAccessToken;
+  private promiseToCachedToken_: Promise<FirebaseAccessToken>;
   private tokenListeners_: Array<(token: string) => void>;
+  private isRefreshing: boolean;
 
   // eslint-disable-next-line @typescript-eslint/naming-convention
   constructor(private credential_: Credential) {
     this.tokenListeners_ = [];
+    this.isRefreshing = false;
   }
 
   public getToken(forceRefresh = false): Promise<FirebaseAccessToken> {
     if (forceRefresh || this.shouldRefresh()) {
-      return this.refreshToken();
+      this.promiseToCachedToken_ = this.refreshToken();
     }
-
-    return Promise.resolve(this.cachedToken_);
+    return this.promiseToCachedToken_
   }
 
   public getCachedToken(): FirebaseAccessToken | null {
@@ -59,6 +61,7 @@ export class FirebaseAppInternals {
   }
 
   private refreshToken(): Promise<FirebaseAccessToken> {
+    this.isRefreshing = true;
     return Promise.resolve(this.credential_.getAccessToken())
       .then((result) => {
         // Since the developer can provide the credential implementation, we want to weakly verify
@@ -108,11 +111,14 @@ export class FirebaseAppInternals {
         }
 
         throw new FirebaseAppError(AppErrorCodes.INVALID_CREDENTIAL, errorMessage);
-      });
+      })
+      .finally(() => {
+        this.isRefreshing = false;
+      })
   }
 
   private shouldRefresh(): boolean {
-    return !this.cachedToken_ || (this.cachedToken_.expirationTime - Date.now()) <= TOKEN_EXPIRY_THRESHOLD_MILLIS;
+    return (!this.cachedToken_ || (this.cachedToken_.expirationTime - Date.now()) <= TOKEN_EXPIRY_THRESHOLD_MILLIS) && !this.isRefreshing;
   }
 
   /**
diff --git a/test/integration/messaging.spec.ts b/test/integration/messaging.spec.ts
index d11b035861..d564e06f66 100644
--- a/test/integration/messaging.spec.ts
+++ b/test/integration/messaging.spec.ts
@@ -278,7 +278,7 @@ describe('admin.messaging', () => {
       });
   });
 
-  xit('sendToDeviceGroup() returns a response with success count', () => {
+  it('sendToDeviceGroup() returns a response with success count', () => {
     return getMessaging().sendToDeviceGroup(notificationKey, payload, options)
       .then((response) => {
         expect(typeof response.successCount).to.equal('number');
diff --git a/test/unit/app/firebase-app.spec.ts b/test/unit/app/firebase-app.spec.ts
index 2211f4f457..df4fc84a67 100644
--- a/test/unit/app/firebase-app.spec.ts
+++ b/test/unit/app/firebase-app.spec.ts
@@ -808,6 +808,16 @@ describe('FirebaseApp', () => {
       });
     });
 
+    it('only refreshes the token once for concurrent calls', () => {
+      const promise1 = mockApp.INTERNAL.getToken();
+      const promise2 = mockApp.INTERNAL.getToken();
+      expect(getTokenStub).to.have.been.calledOnce;
+      return Promise.all([promise1, promise2]).then((tokens) => {
+        expect(tokens[0]).to.equal(tokens[1]);
+        expect(getTokenStub).to.have.been.calledOnce;
+      })
+    });
+
     it('Includes the original error in exception', () => {
       getTokenStub.restore();
       const mockError = new FirebaseAppError(

From 43948a88a1bede92c2eebb77af6f2c59af7f5f44 Mon Sep 17 00:00:00 2001
From: Jonathan Edey <jedey@google.com>
Date: Mon, 29 Jul 2024 11:05:25 -0400
Subject: [PATCH 2/2] fix: lint

---
 src/app/firebase-app.ts | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/app/firebase-app.ts b/src/app/firebase-app.ts
index b0696dc590..a0ee93e1fe 100644
--- a/src/app/firebase-app.ts
+++ b/src/app/firebase-app.ts
@@ -118,7 +118,8 @@ export class FirebaseAppInternals {
   }
 
   private shouldRefresh(): boolean {
-    return (!this.cachedToken_ || (this.cachedToken_.expirationTime - Date.now()) <= TOKEN_EXPIRY_THRESHOLD_MILLIS) && !this.isRefreshing;
+    return (!this.cachedToken_ || (this.cachedToken_.expirationTime - Date.now()) <= TOKEN_EXPIRY_THRESHOLD_MILLIS) 
+      && !this.isRefreshing;
   }
 
   /**