CSHARP-905: Fix ParallelScan feature detection when connected to mongos.

Author: rstam

MongoDB.Driver/Communication/FeatureDetection/FeatureContext.cs

@@ -23,7 +23,7 @@ internal class FeatureContext
         private MongoServerBuildInfo _buildInfo;
         private MongoConnection _connection;
         private IsMasterResult _isMasterResult;
-        private MongoServerInstance _serverInstance;
+        private MongoServerInstanceType _serverInstanceType;
 
         // public methods
         public MongoServerBuildInfo BuildInfo
@@ -44,10 +44,10 @@ public IsMasterResult IsMasterResult
             set { _isMasterResult = value; }
         }
 
-        public MongoServerInstance ServerInstance
+        public MongoServerInstanceType ServerInstanceType
         {
-            get { return _serverInstance; }
-            set { _serverInstance = value; }
+            get { return _serverInstanceType; }
+            set { _serverInstanceType = value; }
         }
     }
 }

MongoDB.Driver/Communication/FeatureDetection/InstanceTypeDependency.cs

@@ -29,7 +29,7 @@ public InstanceTypeDependency(MongoServerInstanceType instanceType)
         // public methods
         public bool IsMet(FeatureContext context)
         {
-            return context.ServerInstance.InstanceType == _instanceType;
+            return context.ServerInstanceType == _instanceType;
         }
     }
 }

MongoDB.Driver/Communication/MongoServerInstance.cs

@@ -628,20 +628,11 @@ private void LookupServerInformation(MongoConnection connection)
                 isMasterResult = RunCommandAs<IsMasterResult>(connection, "admin", isMasterCommand);
 
                 MongoServerBuildInfo buildInfo;
-                FeatureSet featureSet;
                 try
                 {
                     var buildInfoCommand = new CommandDocument("buildinfo", 1);
                     var buildInfoResult = RunCommandAs<CommandResult>(connection, "admin", buildInfoCommand);
                     buildInfo = MongoServerBuildInfo.FromCommandResult(buildInfoResult);
-                    var featureContext = new FeatureContext
-                    {
-                        BuildInfo = buildInfo,
-                        Connection = connection,
-                        IsMasterResult = isMasterResult,
-                        ServerInstance = this
-                    };
-                    featureSet = new FeatureSetDetector().DetectFeatureSet(featureContext);
                 }
                 catch (MongoCommandException ex)
                 {
@@ -651,7 +642,6 @@ private void LookupServerInformation(MongoConnection connection)
                         throw;
                     }
                     buildInfo = null;
-                    featureSet = null;
                 }
 
                 ReplicaSetInformation replicaSetInformation = null;
@@ -667,6 +657,15 @@ private void LookupServerInformation(MongoConnection connection)
                     instanceType = MongoServerInstanceType.ShardRouter;
                 }
 
+                var featureContext = new FeatureContext
+                {
+                    BuildInfo = buildInfo,
+                    Connection = connection,
+                    IsMasterResult = isMasterResult,
+                    ServerInstanceType = instanceType
+                };
+                var featureSet = new FeatureSetDetector().DetectFeatureSet(featureContext);
+
                 var newServerInfo = new ServerInformation
                 {
                     BuildInfo = buildInfo,