refactor(topology-base): track support for session capability

NODE-1088

Author: mbroadst

lib/topologies/topology_base.js

@@ -203,6 +203,7 @@ var ServerCapabilities = function(ismaster) {
   var maxNumberOfDocsInBatch = ismaster.maxWriteBatchSize || 1000;
   var commandsTakeWriteConcern = false;
   var commandsTakeCollation = false;
+  var sessionSupport = false;
 
   if (ismaster.minWireVersion >= 0) {
     textSearch = true;
@@ -236,6 +237,10 @@ var ServerCapabilities = function(ismaster) {
     ismaster.maxWireVersion = 0;
   }
 
+  if (typeof ismaster.logicalSessionTimeoutMinutes !== 'undefined') {
+    sessionSupport = true;
+  }
+
   // Map up read only parameters
   setup_get_property(this, 'hasAggregationCursor', aggregationCursor);
   setup_get_property(this, 'hasWriteCommands', writeCommands);
@@ -248,6 +253,7 @@ var ServerCapabilities = function(ismaster) {
   setup_get_property(this, 'maxNumberOfDocsInBatch', maxNumberOfDocsInBatch);
   setup_get_property(this, 'commandsTakeWriteConcern', commandsTakeWriteConcern);
   setup_get_property(this, 'commandsTakeCollation', commandsTakeCollation);
+  setup_get_property(this, 'hasSessionSupport', sessionSupport);
 };
 
 exports.Store = Store;