grpc-js: Fix handling of calls after resolution failure

packages/grpc-js/src/channel.ts

@@ -20,6 +20,7 @@ import {
   Call,
   Http2CallStream,
   CallStreamOptions,
+  StatusObject,
 } from './call-stream';
 import { ChannelCredentials } from './channel-credentials';
 import { ChannelOptions } from './channel-options';
@@ -170,6 +171,14 @@ export class ChannelImplementation implements Channel {
    */
   private callRefTimer: NodeJS.Timer;
   private configSelector: ConfigSelector | null = null;
+  /**
+   * This is the error from the name resolver if it failed most recently. It
+   * is only used to end calls that start while there is no config selector
+   * and the name resolver is in backoff, so it should be nulled if
+   * configSelector becomes set or the channel state becomes anything other
+   * than TRANSIENT_FAILURE.
+   */
+  private currentResolutionError: StatusObject | null = null;
 
   // Channelz info
   private readonly channelzEnabled: boolean = true;
@@ -290,6 +299,7 @@ export class ChannelImplementation implements Channel {
           this.channelzTrace.addTrace('CT_INFO', 'Address resolution succeeded');
         }
         this.configSelector = configSelector;
+        this.currentResolutionError = null;
         /* We process the queue asynchronously to ensure that the corresponding
          * load balancer update has completed. */
         process.nextTick(() => {
@@ -309,6 +319,9 @@ export class ChannelImplementation implements Channel {
         if (this.configSelectionQueue.length > 0) {
           this.trace('Name resolution failed with calls queued for config selection');
         }
+        if (this.configSelector === null) {
+          this.currentResolutionError = status;
+        }
         const localQueue = this.configSelectionQueue;
         this.configSelectionQueue = [];
         this.callRefTimerUnref();
@@ -591,6 +604,9 @@ export class ChannelImplementation implements Channel {
         watcherObject.callback();
       }
     }
+    if (newState !== ConnectivityState.TRANSIENT_FAILURE) {
+      this.currentResolutionError = null;
+    }
   }
 
   private tryGetConfig(stream: Http2CallStream, metadata: Metadata) {
@@ -605,11 +621,15 @@ export class ChannelImplementation implements Channel {
        * ResolvingLoadBalancer may be idle and if so it needs to be kicked
        * because it now has a pending request. */
       this.resolvingLoadBalancer.exitIdle();
+      if (this.currentResolutionError && !metadata.getOptions().waitForReady) {
+        stream.cancelWithStatus(this.currentResolutionError.code, this.currentResolutionError.details);
+      } else {
         this.configSelectionQueue.push({
           callStream: stream,
           callMetadata: metadata,
         });
         this.callRefTimerRef();
+      }
     } else {
       const callConfig = this.configSelector(stream.getMethod(), metadata);
       if (callConfig.status === Status.OK) {

packages/grpc-js/src/resolving-load-balancer.ts

@@ -268,6 +268,7 @@ export class ResolvingLoadBalancer implements LoadBalancer {
     if (this.currentState === ConnectivityState.IDLE) {
       this.updateState(ConnectivityState.CONNECTING, new QueuePicker(this));
     }
+    this.backoffTimeout.runOnce();
   }
 
   private updateState(connectivityState: ConnectivityState, picker: Picker) {
@@ -294,18 +295,16 @@ export class ResolvingLoadBalancer implements LoadBalancer {
       );
       this.onFailedResolution(error);
     }
-    this.backoffTimeout.runOnce();
   }
 
   exitIdle() {
     this.childLoadBalancer.exitIdle();
-    if (this.currentState === ConnectivityState.IDLE) {
+    if (this.currentState === ConnectivityState.IDLE || this.currentState === ConnectivityState.TRANSIENT_FAILURE) {
       if (this.backoffTimeout.isRunning()) {
         this.continueResolving = true;
       } else {
         this.updateResolution();
       }
-      this.updateState(ConnectivityState.CONNECTING, new QueuePicker(this));
     }
   }
 

packages/grpc-js/test/test-client.ts

@@ -93,3 +93,27 @@ describe('Client without a server', () => {
     });
   });
 });
+
+describe('Client with a nonexistent target domain', () => {
+  let client: Client;
+  before(() => {
+    // DNS name that does not exist per RFC 6761 section 6.4
+    client = new Client('host.invalid', clientInsecureCreds);
+  });
+  after(() => {
+    client.close();
+  });
+  it('should fail multiple calls', function(done) {
+    this.timeout(5000);
+    // Regression test for https://github.com/grpc/grpc-node/issues/1411
+    client.makeUnaryRequest('/service/method', x => x, x => x, Buffer.from([]), (error, value) => {
+      assert(error);
+      assert.strictEqual(error?.code, grpc.status.UNAVAILABLE);
+      client.makeUnaryRequest('/service/method', x => x, x => x, Buffer.from([]), (error, value) => {
+        assert(error);
+        assert.strictEqual(error?.code, grpc.status.UNAVAILABLE);
+        done();
+      });
+    });
+  });
+});