Add Healthy state to streams.

Author: ehsannas

packages/firestore/src/remote/persistent_stream.ts

@@ -97,6 +97,13 @@ const enum PersistentStreamState {
    */
   Open,
 
+  /**
+   * The stream is healthy and has been connected for more than 10 seconds. We
+   * therefore assume that the credentials we passed were valid. Both
+   * isStarted() and isOpen() will return true.
+   */
+  Healthy,
+
   /**
    * The stream encountered an error. The next start attempt will back off.
    * While in this state isStarted() will return false.
@@ -132,6 +139,9 @@ export interface PersistentStreamListener {
 /** The time a stream stays open after it is marked idle. */
 const IDLE_TIMEOUT_MS = 60 * 1000;
 
+/** The time a stream stays open until we consider it healthy. */
+const HEALTHY_TIMEOUT_MS = 10 * 1000;
+
 /**
  * A PersistentStream is an abstract base class that represents a streaming RPC
  * to the Firestore backend. It's built on top of the connections own support
@@ -178,6 +188,7 @@ export abstract class PersistentStream<
   private closeCount = 0;
 
   private idleTimer: DelayedOperation<void> | null = null;
+  private healthCheck: DelayedOperation<void> | null = null;
   private stream: Stream<SendType, ReceiveType> | null = null;
 
   protected backoff: ExponentialBackoff;
@@ -186,6 +197,7 @@ export abstract class PersistentStream<
     private queue: AsyncQueue,
     connectionTimerId: TimerId,
     private idleTimerId: TimerId,
+    private healthTimerId: TimerId,
     protected connection: Connection,
     private credentialsProvider: CredentialsProvider,
     protected listener: ListenerType
@@ -203,8 +215,8 @@ export abstract class PersistentStream<
   isStarted(): boolean {
     return (
       this.state === PersistentStreamState.Starting ||
-      this.state === PersistentStreamState.Open ||
-      this.state === PersistentStreamState.Backoff
+      this.state === PersistentStreamState.Backoff ||
+      this.isOpen()
     );
   }
 
@@ -213,7 +225,8 @@ export abstract class PersistentStream<
    * called) and the stream is ready for outbound requests.
    */
   isOpen(): boolean {
-    return this.state === PersistentStreamState.Open;
+    return this.state === PersistentStreamState.Open ||
+      this.state === PersistentStreamState.Healthy;
   }
 
   /**
@@ -291,6 +304,7 @@ export abstract class PersistentStream<
   /** Sends a message to the underlying stream. */
   protected sendRequest(msg: SendType): void {
     this.cancelIdleCheck();
+    this.cancelHealthCheck();
     this.stream!.send(msg);
   }
 
@@ -311,6 +325,14 @@ export abstract class PersistentStream<
     }
   }
 
+  /** Cancels the health check delayed operation. */
+  private cancelHealthCheck(): void {
+    if (this.healthCheck) {
+      this.healthCheck.cancel();
+      this.healthCheck = null;
+    }
+  }
+
   /**
    * Closes the stream and cleans up as necessary:
    *
@@ -352,9 +374,14 @@ export abstract class PersistentStream<
         'Using maximum backoff delay to prevent overloading the backend.'
       );
       this.backoff.resetToMax();
-    } else if (error && error.code === Code.UNAUTHENTICATED) {
-      // "unauthenticated" error means the token was rejected. Try force refreshing it in case it
-      // just expired.
+    } else if (error && error.code === Code.UNAUTHENTICATED &&
+      this.state !== PersistentStreamState.Healthy) {
+      // "unauthenticated" error means the token was rejected. This should rarely
+      // happen since both Auth and AppCheck ensure a sufficient TTL when we
+      // request a token. If a user manually resets their system clock this can
+      // 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.
       this.credentialsProvider.invalidateToken();
     }
 
@@ -450,6 +477,19 @@ export abstract class PersistentStream<
         this.state = PersistentStreamState.Open;
         return this.listener!.onOpen();
       });
+
+      if (this.healthCheck === null) {
+        this.healthCheck = this.queue.enqueueAfterDelay(
+          this.healthTimerId,
+          HEALTHY_TIMEOUT_MS,
+          () => {
+            if (this.isOpen()) {
+              this.state = PersistentStreamState.Healthy;
+            }
+            return Promise.resolve();
+          }
+        );
+      }
     });
     this.stream.onClose((error?: FirestoreError) => {
       dispatchIfNotClosed(() => {
@@ -559,6 +599,7 @@ export class PersistentListenStream extends PersistentStream<
       queue,
       TimerId.ListenStreamConnectionBackoff,
       TimerId.ListenStreamIdle,
+      TimerId.HealthCheckTimeout,
       connection,
       credentials,
       listener
@@ -667,6 +708,7 @@ export class PersistentWriteStream extends PersistentStream<
       queue,
       TimerId.WriteStreamConnectionBackoff,
       TimerId.WriteStreamIdle,
+      TimerId.HealthCheckTimeout,
       connection,
       credentials,
       listener

packages/firestore/src/util/async_queue.ts

@@ -38,15 +38,17 @@ export const enum TimerId {
   All = 'all',
 
   /**
-   * The following 4 timers are used in persistent_stream.ts for the listen and
+   * The following 5 timers are used in persistent_stream.ts for the listen and
    * write streams. The "Idle" timer is used to close the stream due to
    * inactivity. The "ConnectionBackoff" timer is used to restart a stream once
-   * the appropriate backoff delay has elapsed.
+   * the appropriate backoff delay has elapsed. The health check is used to mark
+   * a stream healthy if it has not received an error during its initial setup.
    */
   ListenStreamIdle = 'listen_stream_idle',
   ListenStreamConnectionBackoff = 'listen_stream_connection_backoff',
   WriteStreamIdle = 'write_stream_idle',
   WriteStreamConnectionBackoff = 'write_stream_connection_backoff',
+  HealthCheckTimeout = 'health_check_timeout',
 
   /**
    * A timer used in online_state_tracker.ts to transition from

packages/firestore/test/integration/remote/stream.test.ts

@@ -274,6 +274,26 @@ describe('Write Stream', () => {
   });
 });
 
+it('token is not invalidated once the stream is healthy', () => {
+  const credentials = new MockCredentialsProvider();
+
+  return withTestWriteStream(async (writeStream, streamListener, queue) => {
+    await streamListener.awaitCallback('open');
+
+    await queue.runAllDelayedOperationsUntil(TimerId.HealthCheckTimeout);
+
+    // Simulate callback from GRPC with an unauthenticated error -- this should
+    // NOT invalidate the token.
+    await writeStream.handleStreamClose(
+      new FirestoreError(Code.UNAUTHENTICATED, '')
+    );
+    await streamListener.awaitCallback('close');
+    expect(credentials.observedStates).to.deep.equal([
+      'getToken'
+    ]);
+  }, credentials);
+});
+
 export async function withTestWriteStream(
   fn: (
     writeStream: PersistentWriteStream,