cleanup topology a bit

Author: baileympearson

src/sdam/topology.ts

@@ -22,7 +22,7 @@ import {
 import {
   MongoCompatibilityError,
   type MongoDriverError,
-  MongoError,
+  type MongoError,
   MongoErrorLabel,
   MongoOperationTimeoutError,
   MongoRuntimeError,
@@ -839,8 +839,6 @@ function createAndConnectServer(topology: Topology, serverDescription: ServerDes
     server.on(event, (e: any) => topology.emit(event, e));
   }
 
-  server.on(Server.DESCRIPTION_RECEIVED, description => topology.serverUpdateHandler(description));
-
   server.connect();
   return server;
 }
@@ -851,58 +849,52 @@ function createAndConnectServer(topology: Topology, serverDescription: ServerDes
  */
 function updateServers(topology: Topology, incomingServerDescription?: ServerDescription) {
   // update the internal server's description
-  if (incomingServerDescription && topology.s.servers.has(incomingServerDescription.address)) {
-    const server = topology.s.servers.get(incomingServerDescription.address);
-    if (server) {
-      server.s.description = incomingServerDescription;
-      if (
-        incomingServerDescription.error instanceof MongoError &&
-        incomingServerDescription.error.hasErrorLabel(MongoErrorLabel.ResetPool)
-      ) {
-        const interruptInUseConnections = incomingServerDescription.error.hasErrorLabel(
-          MongoErrorLabel.InterruptInUseConnections
-        );
-
-        server.pool.clear({ interruptInUseConnections });
-      } else if (incomingServerDescription.error == null) {
-        const newTopologyType = topology.s.description.type;
-        const shouldMarkPoolReady =
-          incomingServerDescription.isDataBearing ||
-          (incomingServerDescription.type !== ServerType.Unknown &&
-            newTopologyType === TopologyType.Single);
-        if (shouldMarkPoolReady) {
-          server.pool.ready();
-        }
+  const server =
+    incomingServerDescription && topology.s.servers.get(incomingServerDescription.address);
+
+  // if the incoming description corresponds to a known server, update that server's description
+  if (server) {
+    server.s.description = incomingServerDescription;
+    if (incomingServerDescription.error == null) {
+      const newTopologyType = topology.s.description.type;
+      const shouldMarkPoolReady =
+        incomingServerDescription.isDataBearing ||
+        (incomingServerDescription.type !== ServerType.Unknown &&
+          newTopologyType === TopologyType.Single);
+      if (shouldMarkPoolReady) {
+        server.pool.ready();
       }
     }
   }
 
-  // add new servers for all descriptions we currently don't know about locally
-  for (const serverDescription of topology.description.servers.values()) {
-    if (!topology.s.servers.has(serverDescription.address)) {
-      const server = createAndConnectServer(topology, serverDescription);
-      topology.s.servers.set(serverDescription.address, server);
+  function* filter<T>(
+    iterable: Iterable<T>,
+    predicate: (arg0: T) => boolean
+  ): Generator<T, void, unknown> {
+    for (const value of iterable) {
+      if (predicate(value)) yield value;
     }
   }
 
-  // for all servers no longer known, remove their descriptions and destroy their instances
-  for (const entry of topology.s.servers) {
-    const serverAddress = entry[0];
-    if (topology.description.hasServer(serverAddress)) {
-      continue;
-    }
-
-    if (!topology.s.servers.has(serverAddress)) {
-      continue;
-    }
-
-    const server = topology.s.servers.get(serverAddress);
-    topology.s.servers.delete(serverAddress);
+  // add new servers for all descriptions we currently don't know about locally
+  const newlyDiscoveredServers = filter(
+    topology.description.servers.values(),
+    description => !topology.s.servers.has(description.address)
+  );
+  for (const serverDescription of newlyDiscoveredServers) {
+    const server = createAndConnectServer(topology, serverDescription);
+    topology.s.servers.set(serverDescription.address, server);
+  }
 
+  // for all servers no longer known, remove their descriptions and destroy their instances
+  const unknownServers = filter(
+    topology.s.servers,
+    ([address]) => !topology.description.hasServer(address)
+  );
+  for (const [address, server] of unknownServers) {
+    topology.s.servers.delete(address);
     // prepare server for garbage collection
-    if (server) {
-      closeServer(server, topology);
-    }
+    closeServer(server, topology);
   }
 }