From 494dffb915c30809fd077ce9bd53a24f01986e5c Mon Sep 17 00:00:00 2001
From: Matt Broadstone <mbroadst@mongodb.com>
Date: Mon, 24 Feb 2020 12:28:48 -0500
Subject: [PATCH] fix(topology): enter `STATE_CLOSING` before draining
 waitQueue

NODE-2468
---
 lib/core/sdam/topology.js | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/lib/core/sdam/topology.js b/lib/core/sdam/topology.js
index 57c53b2c32f..ed1df2d3f00 100644
--- a/lib/core/sdam/topology.js
+++ b/lib/core/sdam/topology.js
@@ -312,7 +312,7 @@ class Topology extends EventEmitter {
     }
 
     options = options || {};
-    if (this.s.state === STATE_CLOSED) {
+    if (this.s.state === STATE_CLOSED || this.s.state === STATE_CLOSING) {
       if (typeof callback === 'function') {
         callback();
       }
@@ -320,6 +320,8 @@ class Topology extends EventEmitter {
       return;
     }
 
+    stateTransition(this, STATE_CLOSING);
+
     drainWaitQueue(this[kWaitQueue], new MongoError('Topology closed'));
     drainTimerQueue(this.s.connectionTimers);
 
@@ -336,8 +338,6 @@ class Topology extends EventEmitter {
       delete this.s.detectTopologyDescriptionChange;
     }
 
-    stateTransition(this, STATE_CLOSING);
-
     this.s.sessions.forEach(session => session.endSession());
     this.s.sessionPool.endAllPooledSessions(() => {
       eachAsync(