From d5931ad232aa0819e575d772f8abcc489a408979 Mon Sep 17 00:00:00 2001
From: murgatroid99 <mlumish@google.com>
Date: Thu, 10 Oct 2019 10:26:36 -0700
Subject: [PATCH] grpc-js: pick first: resolve address again after trying all
 addresses

---
 packages/grpc-js/src/load-balancer-pick-first.ts | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/packages/grpc-js/src/load-balancer-pick-first.ts b/packages/grpc-js/src/load-balancer-pick-first.ts
index a764a220..82693807 100644
--- a/packages/grpc-js/src/load-balancer-pick-first.ts
+++ b/packages/grpc-js/src/load-balancer-pick-first.ts
@@ -343,15 +343,20 @@ export class PickFirstLoadBalancer implements LoadBalancer {
     lbConfig: LoadBalancingConfig | null
   ): void {
     // lbConfig has no useful information for pick first load balancing
-    this.latestAddressList = addressList;
-    this.connectToAddressList();
+    /* To avoid unnecessary churn, we only do something with this address list
+     * if we're not currently trying to establish a connection, or if the new
+     * address list is different from the existing one */
+    if (this.subchannels.length === 0 || !this.latestAddressList.every((value, index) => addressList[index] === value)) {
+      this.latestAddressList = addressList;
+      this.connectToAddressList();
+    }
   }
 
   exitIdle() {
     for (const subchannel of this.subchannels) {
       subchannel.startConnecting();
     }
-    if (this.currentState === ConnectivityState.IDLE) {
+    if (this.currentState === ConnectivityState.IDLE || this.triedAllSubchannels) {
       this.channelControlHelper.requestReresolution();
       if (this.latestAddressList.length > 0) {
         this.connectToAddressList();