grpc-js: Transition subchannel to TRANSIENT_FAILURE when the socket closes

Author: murgatroid99

packages/grpc-js/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@grpc/grpc-js",
-  "version": "1.5.6",
+  "version": "1.5.7",
   "description": "gRPC Library for Node - pure JS implementation",
   "homepage": "https://grpc.io/",
   "repository": "https://github.com/grpc/grpc-node/tree/master/packages/grpc-js",

packages/grpc-js/src/subchannel.ts

@@ -669,9 +669,15 @@ export class Subchannel {
     switch (newState) {
       case ConnectivityState.READY:
         this.stopBackoff();
-        this.session!.socket.once('close', () => {
-          for (const listener of this.disconnectListeners) {
-            listener();
+        const session = this.session!;
+        session.socket.once('close', () => {
+          if (this.session === session) {
+            this.transitionToState(
+              [ConnectivityState.READY],
+              ConnectivityState.TRANSIENT_FAILURE);
+            for (const listener of this.disconnectListeners) {
+              listener();
+            }
           }
         });
         if (this.keepaliveWithoutCalls) {