CSHARP-735: When connected directly to a secondary do not coerce ReadPreference to Primary for commands.

Author: rstam

MongoDB.Driver/Communication/Proxies/DirectMongoServerProxy.cs

@@ -86,6 +86,14 @@ public ReadOnlyCollection<MongoServerInstance> Instances
             get { return new List<MongoServerInstance> { _instance }.AsReadOnly(); }
         }
 
+        /// <summary>
+        /// Gets the type of the proxy.
+        /// </summary>
+        public MongoServerProxyType ProxyType
+        {
+            get { return MongoServerProxyType.Direct; }
+        }
+
         /// <summary>
         /// Gets the state.
         /// </summary>

MongoDB.Driver/Communication/Proxies/DiscoveringMongoServerProxy.cs

@@ -96,6 +96,22 @@ public ReadOnlyCollection<MongoServerInstance> Instances
             }
         }
 
+        /// <summary>
+        /// Gets the type of the proxy.
+        /// </summary>
+        public MongoServerProxyType ProxyType
+        {
+            get
+            {
+                if (_serverProxy == null)
+                {
+                    return MongoServerProxyType.Unknown;
+                }
+
+                return _serverProxy.ProxyType;
+            }
+        }
+
         /// <summary>
         /// Gets the name of the replica set (null if not connected to a replica set).
         /// </summary>

MongoDB.Driver/Communication/Proxies/IMongoServerProxy.cs

@@ -38,6 +38,11 @@ internal interface IMongoServerProxy
         /// </summary>
         ReadOnlyCollection<MongoServerInstance> Instances { get; }
 
+        /// <summary>
+        /// Gets the type of the proxy.
+        /// </summary>
+        MongoServerProxyType ProxyType { get; }
+
         /// <summary>
         /// Gets the state.
         /// </summary>

MongoDB.Driver/Communication/Proxies/MongoServerProxyType.cs

@@ -0,0 +1,43 @@
+/* Copyright 2010-2013 10gen Inc.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+* http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+using System;
+using System.Collections.ObjectModel;
+
+namespace MongoDB.Driver.Internal
+{
+    /// <summary>
+    /// Represents the type of an IMongoServerProxy.
+    /// </summary>
+    internal enum MongoServerProxyType
+    {
+        /// <summary>
+        /// The type of the proxy is not yet known.
+        /// </summary>
+        Unknown,
+        /// <summary>
+        /// A proxy to a single node.
+        /// </summary>
+        Direct,
+        /// <summary>
+        /// A proxy to a replica set.
+        /// </summary>
+        ReplicaSet,
+        /// <summary>
+        /// A proxy to a sharded router.
+        /// </summary>
+        Sharded
+    }
+}

MongoDB.Driver/Communication/Proxies/MultipleInstanceMongoServerProxy.cs

@@ -125,6 +125,11 @@ public ReadOnlyCollection<MongoServerInstance> Instances
             }
         }
 
+        /// <summary>
+        /// Gets the type of the proxy.
+        /// </summary>
+        public abstract MongoServerProxyType ProxyType { get; }
+
         /// <summary>
         /// Gets the state.
         /// </summary>

MongoDB.Driver/Communication/Proxies/ReplicaSetMongoServerProxy.cs

@@ -53,6 +53,14 @@ public ReplicaSetMongoServerProxy(MongoServerSettings serverSettings, IEnumerabl
         { }
 
         // public properties
+        /// <summary>
+        /// Gets the type of the proxy.
+        /// </summary>
+        public override MongoServerProxyType ProxyType
+        {
+            get { return MongoServerProxyType.ReplicaSet; }
+        }
+
         /// <summary>
         /// Gets the name of the replica set.
         /// </summary>

MongoDB.Driver/Communication/Proxies/ShardedMongoServerProxy.cs

@@ -48,6 +48,15 @@ public ShardedMongoServerProxy(MongoServerSettings settings, IEnumerable<MongoSe
             : base(settings, instances, stateChangedQueue, connectionAttempt)
         { }
 
+        // public properties
+        /// <summary>
+        /// Gets the type of the proxy.
+        /// </summary>
+        public override MongoServerProxyType ProxyType
+        {
+            get { return MongoServerProxyType.Sharded; }
+        }
+
         // protected methods
         /// <summary>
         /// Chooses the server instance.

MongoDB.Driver/MongoCollection.cs

@@ -1741,9 +1741,12 @@ private TCommandResult RunCommandAs<TCommandResult>(
                 GuidRepresentation = _settings.GuidRepresentation
             };
             var readPreference = _settings.ReadPreference;
-            if (readPreference != ReadPreference.Primary && !CanCommandBeSentToSecondary.Delegate(command.ToBsonDocument()))
+            if (readPreference != ReadPreference.Primary)
             {
-                readPreference = ReadPreference.Primary;
+                if (_server.ProxyType == MongoServerProxyType.ReplicaSet  && !CanCommandBeSentToSecondary.Delegate(command.ToBsonDocument()))
+                {
+                    readPreference = ReadPreference.Primary;
+                }
             }
             var flags = (readPreference == ReadPreference.Primary) ? QueryFlags.None : QueryFlags.SlaveOk;
 

MongoDB.Driver/MongoCursor.cs

@@ -732,9 +732,7 @@ public virtual IEnumerator<TDocument> GetEnumerator()
 
             if (readPreference.ReadPreferenceMode != ReadPreferenceMode.Primary && Collection.Name == "$cmd")
             {
-                var queryDocument = Query.ToBsonDocument();
-                var isSecondaryOk = CanCommandBeSentToSecondary.Delegate(queryDocument);
-                if (!isSecondaryOk)
+                if (Server.ProxyType == MongoServerProxyType.ReplicaSet && !CanCommandBeSentToSecondary.Delegate(Query.ToBsonDocument()))
                 {
                     // if the command can't be sent to a secondary, then we use primary here
                     // regardless of the user's choice.

MongoDB.Driver/MongoCursorEnumerator.cs

@@ -57,9 +57,7 @@ public MongoCursorEnumerator(MongoCursor<TDocument> cursor)
 
             if (_readPreference.ReadPreferenceMode != ReadPreferenceMode.Primary && _cursor.Collection.Name == "$cmd")
             {
-                var queryDocument = _cursor.Query.ToBsonDocument();
-                var isSecondaryOk = CanCommandBeSentToSecondary.Delegate(queryDocument);
-                if (!isSecondaryOk)
+                if (cursor.Server.ProxyType == MongoServerProxyType.ReplicaSet && !CanCommandBeSentToSecondary.Delegate(_cursor.Query.ToBsonDocument()))
                 {
                     // if the command can't be sent to a secondary, then we use primary here
                     // regardless of the user's choice.