refactor: explicitly disallow selection if topology is closed

This is not our eventual desire, but until we can remove the
concept of `connect`, we need to abide by the rules of it.

Author: mbroadst

lib/core/sdam/monitoring.js

@@ -130,6 +130,11 @@ function monitorServer(server, options) {
   options = options || {};
   const heartbeatFrequencyMS = options.heartbeatFrequencyMS || 10000;
 
+  if (options.initial === true) {
+    server.s.monitorId = setTimeout(() => monitorServer(server), heartbeatFrequencyMS);
+    return;
+  }
+
   const rescheduleMonitoring = () => {
     server.s.monitoring = false;
     server.s.monitorId = setTimeout(() => {

lib/core/sdam/server_selection.js

@@ -7,8 +7,7 @@ const calculateDurationInMs = require('../utils').calculateDurationInMs;
 const MongoTimeoutError = require('../error').MongoTimeoutError;
 
 const common = require('./common');
-const STATE_CONNECTED = common.STATE_CONNECTED;
-const STATE_CONNECTING = common.STATE_CONNECTING;
+const STATE_CLOSED = common.STATE_CLOSED;
 const TOPOLOGY_DEFAULTS = common.TOPOLOGY_DEFAULTS;
 const drainTimerQueue = common.drainTimerQueue;
 const clearAndRemoveTimerFrom = common.clearAndRemoveTimerFrom;
@@ -266,26 +265,9 @@ function selectServers(topology, selector, timeout, start, callback) {
     );
   }
 
-  // ensure we are connected
-  if (topology.s.state !== STATE_CONNECTED && topology.s.state !== STATE_CONNECTING) {
-    topology.connect();
-
-    // we want to make sure we're still within the requested timeout window
-    const failToConnectTimer = setTimeout(() => {
-      topology.removeListener('connect', connectHandler);
-      callback(
-        new MongoTimeoutError('Server selection timed out waiting to connect'),
-        topology.description.error
-      );
-    }, timeout - duration);
-
-    const connectHandler = () => {
-      clearAndRemoveTimerFrom(failToConnectTimer, topology.s.connectionTimers);
-      selectServers(topology, selector, timeout, process.hrtime(), callback);
-    };
-
-    topology.s.connectionTimers.add(failToConnectTimer);
-    topology.once('connect', connectHandler);
+  // explicitly disallow selection if client is closed
+  if (topology.s.state === STATE_CLOSED) {
+    callback(new MongoError('Topology is closed, please connect'));
     return;
   }
 

test/unit/sdam/server_selection/select_servers_tests.js

@@ -71,4 +71,19 @@ describe('selectServers', function() {
       });
     });
   });
+
+  it('should disallow selection when the topology is explicitly closed', function(done) {
+    const topology = new Topology('someserver:27019');
+    this.sinon.stub(Server.prototype, 'connect').callsFake(function() {
+      this.emit('connect');
+    });
+
+    topology.close(() => {
+      selectServers(topology, ReadPreference.primary, 2000, process.hrtime(), err => {
+        expect(err).to.exist;
+        expect(err).to.match(/Topology is closed/);
+        done();
+      });
+    });
+  });
 });