fix(replset): use correct topologyId for event emission

NODE-2268

lib/core/topologies/server.js

@@ -55,6 +55,10 @@ var serverAccounting = false;
 var servers = {};
 var BSON = retrieveBSON();
 
+function topologyId(server) {
+  return server.s.parent == null ? server.id : server.s.parent.id;
+}
+
 /**
  * Creates a new Server instance
  * @class
@@ -151,8 +155,6 @@ var Server = function(options) {
     // Monitoring timeout
     monitoringInterval:
       typeof options.monitoringInterval === 'number' ? options.monitoringInterval : 5000,
-    // Topology id
-    topologyId: -1,
     compression: { compressors: createCompressionInfo(options) },
     // Optional parent topology
     parent: options.parent
@@ -486,14 +488,11 @@ Server.prototype.connect = function(options) {
 
   // Emit toplogy opening event if not in topology
   if (!self.s.inTopology) {
-    this.emit('topologyOpening', { topologyId: self.id });
+    this.emit('topologyOpening', { topologyId: topologyId(self) });
   }
 
   // Emit opening server event
-  self.emit('serverOpening', {
-    topologyId: self.s.topologyId !== -1 ? self.s.topologyId : self.id,
-    address: self.name
-  });
+  self.emit('serverOpening', { topologyId: topologyId(self), address: self.name });
 
   self.s.pool.connect();
 };
@@ -883,14 +882,11 @@ Server.prototype.destroy = function(options, callback) {
 
   // Emit opening server event
   if (self.listeners('serverClosed').length > 0)
-    self.emit('serverClosed', {
-      topologyId: self.s.topologyId !== -1 ? self.s.topologyId : self.id,
-      address: self.name
-    });
+    self.emit('serverClosed', { topologyId: topologyId(self), address: self.name });
 
   // Emit toplogy opening event if not in topology
   if (self.listeners('topologyClosed').length > 0 && !self.s.inTopology) {
-    self.emit('topologyClosed', { topologyId: self.id });
+    self.emit('topologyClosed', { topologyId: topologyId(self) });
   }
 
   if (self.s.logger.isDebug()) {