Fix race condition in CreateCluster.

Author: rstam

src/MongoDB.Driver.Core.TestHelpers/CoreTestConfiguration.cs

@@ -44,6 +44,7 @@ public static class CoreTestConfiguration
         private static ConnectionString __connectionString = GetConnectionString();
         private static DatabaseNamespace __databaseNamespace = GetDatabaseNamespace();
         private static MessageEncoderSettings __messageEncoderSettings = new MessageEncoderSettings();
+        private static TraceSource __traceSource;
 
         // static properties
         public static ICluster Cluster
@@ -75,6 +76,11 @@ public static SemanticVersion ServerVersion
             }
         }
 
+        public static TraceSource TraceSource
+        {
+            get { return __traceSource; }
+        }
+
         // static methods
         public static ClusterBuilder ConfigureCluster()
         {
@@ -133,12 +139,12 @@ public static ClusterBuilder ConfigureLogging(ClusterBuilder builder)
                 return builder;
             }
 
-            var traceSource = new TraceSource("mongodb-tests", defaultLevel);
-            traceSource.Listeners.Clear(); // remove the default listener
+            __traceSource = new TraceSource("mongodb-tests", defaultLevel);
+            __traceSource.Listeners.Clear(); // remove the default listener
             var listener = new ConsoleTraceListener();
             listener.TraceOutputOptions = TraceOptions.DateTime;
-            traceSource.Listeners.Add(listener);
-            return builder.TraceWith(traceSource);
+            __traceSource.Listeners.Add(listener);
+            return builder.TraceWith(__traceSource);
         }
 
         public static ICluster CreateCluster()
@@ -150,8 +156,18 @@ public static ICluster CreateCluster()
             {
                 var anyWritableServer = e.NewClusterDescription.Servers.Any(
                     description => description.Type.IsWritable());
+                if (__traceSource != null)
+                {
+                    __traceSource.TraceEvent(TraceEventType.Information, 0, $"CreateCluster: DescriptionChanged event handler called.");
+                    __traceSource.TraceEvent(TraceEventType.Information, 0, $"CreateCluster: anyWritableServer = {anyWritableServer}.");
+                    __traceSource.TraceEvent(TraceEventType.Information, 0, $"CreateCluster: new description: {e.NewClusterDescription.ToString()}.");
+                }
                 Interlocked.Exchange(ref hasWritableServer, anyWritableServer ? 1 : 0);
             };
+            if (__traceSource != null)
+            {
+                __traceSource.TraceEvent(TraceEventType.Information, 0, "CreateCluster: initializing cluster.");
+            }
             cluster.Initialize();
 
             // wait until the cluster has connected to a writable server
@@ -164,6 +180,11 @@ public static ICluster CreateCluster()
                 throw new Exception(message);
             }
 
+            if (__traceSource != null)
+            {
+                __traceSource.TraceEvent(TraceEventType.Information, 0, "CreateCluster: writable server found.");
+            }
+
             return cluster;
         }
 

src/MongoDB.Driver.Core/Core/Clusters/ClusterFactory.cs

@@ -67,16 +67,12 @@ public ICluster CreateCluster()
 
         private MultiServerCluster CreateMultiServerCluster(ClusterSettings settings)
         {
-            var shardedCluster = new MultiServerCluster(settings, _serverFactory, _eventSubscriber);
-            shardedCluster.Initialize();
-            return shardedCluster;
+            return new MultiServerCluster(settings, _serverFactory, _eventSubscriber);
         }
 
         private SingleServerCluster CreateSingleServerCluster(ClusterSettings settings)
         {
-            var standaloneCluster = new SingleServerCluster(settings, _serverFactory, _eventSubscriber);
-            standaloneCluster.Initialize();
-            return standaloneCluster;
+            return new SingleServerCluster(settings, _serverFactory, _eventSubscriber);
         }
     }
 }