From c5765b8e2bcfe4c26eaa1bc3ee34cec7258d940b Mon Sep 17 00:00:00 2001
From: mpilar <miguel.pilar@apex.pr>
Date: Fri, 15 Apr 2011 14:22:10 -0400
Subject: [PATCH 2/2] CS-200 Background replicaSet connections to slaves when slaveOk=true and return as soon as the master is found.

---
 Driver/Internal/ReplicaSetConnector.cs |   92 +++++++++++++++++++++++++-------
 1 files changed, 73 insertions(+), 19 deletions(-)

diff --git a/Driver/Internal/ReplicaSetConnector.cs b/Driver/Internal/ReplicaSetConnector.cs
index 93a68cd..4e5c6e6 100644
--- a/Driver/Internal/ReplicaSetConnector.cs
+++ b/Driver/Internal/ReplicaSetConnector.cs
@@ -83,6 +83,28 @@ namespace MongoDB.Driver.Internal {
 
             var exceptions = new List<Exception>();
             var timeoutAt = DateTime.UtcNow + timeout;
+
+            ProcessQueryResponses(timeoutAt, responsesQueue, exceptions, false);
+
+            if (primaryEndPoint == null) {
+                var innerException = exceptions.FirstOrDefault();
+                var exception = new MongoConnectionException("Unable to connect to server", innerException);
+                if (exceptions.Count > 1) {
+                    exception.Data.Add("InnerExceptions", exceptions);
+                }
+                throw exception;
+            }
+        }
+
+        #endregion
+
+        #region private methods
+        private void ProcessQueryResponses(
+            DateTime timeoutAt, 
+            BlockingQueue<QueryNodeResponse> responsesQueue, 
+            List<Exception> exceptions, 
+            bool backgrounded
+        ) {
             while (responses.Count < queries.Count) {
                 var timeRemaining = timeoutAt - DateTime.UtcNow;
                 var response = responsesQueue.Dequeue(timeRemaining);
@@ -104,6 +126,21 @@ namespace MongoDB.Driver.Internal {
                     maxMessageLength = response.MaxMessageLength;
                     if (!server.Settings.SlaveOk) {
                         break; // if we're not going to use the secondaries no need to wait for their replies
+                    } else {
+                        if (!backgrounded) {
+                            //do the work for the secondaries, but return the primary ASAP.
+                            ExploreSeedList(responsesQueue, response);
+                            var args = new BackgroundResponseParameters()
+                            {
+                                Queries = queries,
+                                Responses = responses,
+                                TimeoutAt = timeoutAt,
+                                ResponseQueue = responsesQueue,
+                                Exceptions = exceptions
+                            };
+                            ThreadPool.QueueUserWorkItem(QueryResponseWorkItem, args);
+                        }
+                        break;
                     }
                 } else {
                     if (server.Settings.SlaveOk) {
@@ -115,31 +152,28 @@ namespace MongoDB.Driver.Internal {
                 }
 
                 // look for additional members of the replica set that might not have been in the seed list and query them also
-                foreach (var address in GetHostAddresses(response)) {
-                    if (!queries.Contains(address)) {
-                        var args = new QueryNodeParameters {
-                            Address = address,
-                            EndPoint = address.ToIPEndPoint(server.Settings.AddressFamily),
-                            ResponseQueue = responsesQueue
-                        };
-                        ThreadPool.QueueUserWorkItem(QueryNodeWorkItem, args);
-                        queries.Add(address);
-                    }
-                }
+                ExploreSeedList(responsesQueue, response);
             }
+        }
 
-            if (primaryEndPoint == null) {
-                var innerException = exceptions.FirstOrDefault();
-                var exception = new MongoConnectionException("Unable to connect to server", innerException);
-                if (exceptions.Count > 1) {
-                    exception.Data.Add("InnerExceptions", exceptions);
+        private void ExploreSeedList(
+            BlockingQueue<QueryNodeResponse> responsesQueue,
+            QueryNodeResponse response
+        ) {
+            foreach (var address in GetHostAddresses(response)) {
+                if (!queries.Contains(address)) {
+                    var args = new QueryNodeParameters
+                    {
+                        Address = address,
+                        EndPoint = address.ToIPEndPoint(server.Settings.AddressFamily),
+                        ResponseQueue = responsesQueue
+                    };
+                    ThreadPool.QueueUserWorkItem(QueryNodeWorkItem, args);
+                    queries.Add(address);
                 }
-                throw exception;
             }
         }
-        #endregion
 
-        #region private methods
         private List<MongoServerAddress> GetHostAddresses(
             QueryNodeResponse response
         ) {
@@ -172,6 +206,14 @@ namespace MongoDB.Driver.Internal {
             return responseQueue;
         }
 
+        private void QueryResponseWorkItem(
+            object parameters
+        )
+        {
+            var args = (BackgroundResponseParameters) parameters;
+            ProcessQueryResponses(args.TimeoutAt, args.ResponseQueue, args.Exceptions, true);
+        }
+
         // note: this method will run on a thread from the ThreadPool
         private void QueryNodeWorkItem(
             object parameters
@@ -216,6 +258,18 @@ namespace MongoDB.Driver.Internal {
 
         #region private nested classes
         // note: OK to use automatic properties on private helper class
+        private class BackgroundResponseParameters
+        {
+            public HashSet<MongoServerAddress> Queries { get; set; }
+            public Dictionary<MongoServerAddress, QueryNodeResponse> Responses { get; set; }
+            public List<IPEndPoint> EndPoints { get; set; }
+            public List<MongoConnection> Connections { get; set; }
+            public BlockingQueue<QueryNodeResponse> ResponseQueue { get; set; }
+            public List<Exception> Exceptions { get; set; }
+            public DateTime TimeoutAt { get; set; }
+        }
+
+        // note: OK to use automatic properties on private helper class
         private class QueryNodeParameters {
             public MongoServerAddress Address { get; set; }
             public IPEndPoint EndPoint { get; set; }
-- 
1.7.3.1.msysgit.0