ignore appcheck throttling errors

Author: dconeybe

packages/firestore/src/api/credentials.ts

@@ -32,7 +32,7 @@ import { User } from '../auth/user';
 import { debugAssert, hardAssert } from '../util/assert';
 import { AsyncQueue } from '../util/async_queue';
 import { Code, FirestoreError } from '../util/error';
-import { logDebug } from '../util/log';
+import { logDebug, logWarn } from '../util/log';
 import { Deferred } from '../util/promise';
 
 // TODO(mikelehen): This should be split into multiple files and probably
@@ -527,12 +527,28 @@ export class FirebaseAppCheckTokenProvider
     const onTokenChanged: (
       tokenResult: AppCheckTokenResult
     ) => Promise<void> = tokenResult => {
-      if (tokenResult.error != null) {
-        logDebug(
+      if (tokenResult.error) {
+        const code = getCode(tokenResult.error);
+        logWarn(
           'FirebaseAppCheckTokenProvider',
-          `Error getting App Check token; using placeholder token instead. Error: ${tokenResult.error.message}`
+          `Error getting App Check token (code=${code}): ${tokenResult.error.message}`
         );
+
+        // Ignore errors due to the App Check provider throttling requests to
+        // the provider's servers. Treat these errors as if nothing happened
+        // because App Check will get the provider to try again after throttling
+        // unblock it, at which point we will get a shiny, new, valid token.
+        if (isAppCheckThrottleCode(code)) {
+          logWarn(
+            'FirebaseAppCheckTokenProvider',
+            'ignoring failed App Check token retrieval since it is throttled ' +
+              'and App Check will try again later. (code=${code})'
+          );
+          return Promise.resolve();
+        }
+        logWarn('FirebaseAppCheckTokenProvider', 'using placeholder token');
       }
+
       const tokenUpdated = tokenResult.token !== this.latestAppCheckToken;
       this.latestAppCheckToken = tokenResult.token;
       logDebug(
@@ -718,3 +734,15 @@ export function makeAuthCredentialsProvider(
       );
   }
 }
+
+function getCode(error: Error): string | undefined {
+  return 'code' in error && typeof error.code === 'string'
+    ? error.code
+    : undefined;
+}
+
+type AppCheckThrottleCode = 'appCheck/initial-throttle' | 'appCheck/throttled';
+
+function isAppCheckThrottleCode(code: unknown): code is AppCheckThrottleCode {
+  return code === 'appCheck/initial-throttle' || code === 'appCheck/throttled';
+}

packages/firestore/src/remote/persistent_stream.ts

@@ -30,7 +30,7 @@ import {
 import { debugAssert, hardAssert } from '../util/assert';
 import { AsyncQueue, DelayedOperation, TimerId } from '../util/async_queue';
 import { Code, FirestoreError } from '../util/error';
-import { logDebug, logError } from '../util/log';
+import { logDebug, logError, logWarn } from '../util/log';
 import { isNullOrUndefined } from '../util/types';
 
 import { ExponentialBackoff } from './backoff';
@@ -400,6 +400,13 @@ export abstract class PersistentStream<
       // fail, however. In this case, we should get a Code.UNAUTHENTICATED error
       // before we received the first message and we need to invalidate the token
       // to ensure that we fetch a new token.
+      logWarn(
+        LOG_TAG,
+        'Invalidating Auth and AppCheck tokens ' +
+          'in response to UNAUTHENTICATED error ' +
+          'on an otherwise-healthy connection ' +
+          'so that new token(s) are retrieved upon reconnection'
+      );
       this.authCredentialsProvider.invalidateToken();
       this.appCheckCredentialsProvider.invalidateToken();
     }