refactor(sdam): track server connections in a different timer list

Author: mbroadst

lib/core/sdam/topology.js

@@ -179,7 +179,8 @@ class Topology extends EventEmitter {
 
       // timer management
       monitorTimers: [],
-      iterationTimers: []
+      iterationTimers: [],
+      connectionTimers: []
     };
 
     // amend options for server instance creation
@@ -339,6 +340,9 @@ class Topology extends EventEmitter {
     this.s.iterationTimers.map(timer => clearTimeout(timer));
     this.s.iterationTimers = [];
 
+    this.s.connectionTimers.map(timer => clearTimeout(timer));
+    this.s.connectionTimers = [];
+
     if (this.s.sessionPool) {
       this.s.sessions.forEach(session => session.endSession());
       this.s.sessionPool.endAllPooledSessions();
@@ -936,11 +940,11 @@ function createAndConnectServer(topology, serverDescription, connectDelay) {
 
   if (connectDelay) {
     const connectTimer = setTimeout(() => {
-      removeTimerFrom(connectTimer, topology.s.iterationTimers);
+      removeTimerFrom(connectTimer, topology.s.connectionTimers);
       server.connect();
     }, connectDelay);
 
-    topology.s.iterationTimers.push(connectTimer);
+    topology.s.connectionTimers.push(connectTimer);
     return server;
   }
 
@@ -961,7 +965,7 @@ function resetServer(topology, serverDescription) {
   const newServer = createAndConnectServer(
     topology,
     serverDescription,
-    topology.s.heartbeatFrequencyMS
+    topology.s.minHeartbeatFrequencyMS
   );
 
   topology.s.servers.set(serverDescription.address, newServer);