Fixing issue #74. Clean up the _serverQueue on blacklist; use only _serv...

src/Connections/RoundRobinServerManager.cs

@@ -4,112 +4,117 @@
 
 namespace FluentCassandra.Connections
 {
-	public class RoundRobinServerManager : IServerManager
-	{
-		private readonly object _lock = new object();
-
-		private List<Server> _servers;
-		private Queue<Server> _serverQueue;
-		private HashSet<Server> _blackListed;
-
-		public RoundRobinServerManager(IConnectionBuilder builder)
-		{
-			_servers = new List<Server>(builder.Servers);
-			_serverQueue = new Queue<Server>(_servers);
-			_blackListed = new HashSet<Server>();
-		}
-
-		private bool IsBlackListed(Server server)
-		{
-			return _blackListed.Contains(server);
-		}
-
-		#region IServerManager Members
-
-		public bool HasNext
-		{
-            get { lock (_lock) { return (_serverQueue.Count - _blackListed.Count) > 0; } }
-		}
-
-		public Server Next()
-		{
-			Server server;
-
-			lock (_lock)
-			{
-				do
-				{
-					server = _serverQueue.Dequeue();
-
-					if (IsBlackListed(server))
-						server = null;
-					else
-						_serverQueue.Enqueue(server);
-				}
-				while (_serverQueue.Count > 0 && server == null);	
-			}
-
-			return server;
-		}
-
-		public void Add(Server server)
-		{
-			lock (_lock)
-			{
-				_servers.Add(server);
-				_serverQueue.Enqueue(server);
-			}
-		}
-
-		public void ErrorOccurred(Server server, Exception exc = null)
-		{
-			Debug.WriteLineIf(exc != null, exc, "connection");
-			BlackList(server);
-		}
-
-		public void BlackList(Server server)
-		{
-			Debug.WriteLine(server + " has been blacklisted", "connection");
-			lock (_lock)
-			{
-				_blackListed.Add(server);
-			}
-		}
-
-		public void Remove(Server server)
-		{
-			lock (_lock)
-			{
-				_servers.Remove(server);
-				_serverQueue = new Queue<Server>();
-				_blackListed.RemoveWhere(x => x == server);
-
-				foreach (var s in _servers)
-				{
-					if (!_blackListed.Contains(s))
-						_serverQueue.Enqueue(s);
-				}
-			}
-		}
-
-		#endregion
-
-		#region IEnumerable<Server> Members
-
-		public IEnumerator<Server> GetEnumerator()
-		{
-			return _servers.GetEnumerator();
-		}
-
-		#endregion
-
-		#region IEnumerable Members
-
-		System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
-		{
-			return GetEnumerator();
-		}
-
-		#endregion
-	}
+    public class RoundRobinServerManager : IServerManager
+    {
+        private readonly object _lock = new object();
+
+        private List<Server> _servers;
+        private Queue<Server> _serverQueue;
+        private HashSet<Server> _blackListed;
+
+        public RoundRobinServerManager(IConnectionBuilder builder)
+        {
+            _servers = new List<Server>(builder.Servers);
+            _serverQueue = new Queue<Server>(_servers);
+            _blackListed = new HashSet<Server>();
+        }
+
+        private bool IsBlackListed(Server server)
+        {
+            return _blackListed.Contains(server);
+        }
+
+        #region IServerManager Members
+
+        public bool HasNext
+        {
+            get { lock (_lock) { return _serverQueue.Count > 0; } }
+        }
+
+        public Server Next()
+        {
+            Server server = null;
+
+            lock (_lock)
+            {
+                if (_serverQueue.Count > 0)
+                {
+                    server = _serverQueue.Dequeue();
+                    _serverQueue.Enqueue(server);
+                }
+            }
+
+            return server;
+        }
+
+        public void Add(Server server)
+        {
+            lock (_lock)
+            {
+                _servers.Add(server);
+                _serverQueue.Enqueue(server);
+            }
+        }
+
+        public void ErrorOccurred(Server server, Exception exc = null)
+        {
+            Debug.WriteLineIf(exc != null, exc, "connection");
+            BlackList(server);
+        }
+
+        public void BlackList(Server server)
+        {
+            Debug.WriteLine(server + " has been blacklisted", "connection");
+            lock (_lock)
+            {
+                if (_blackListed.Add(server))
+                {
+                    _serverQueue.Clear();
+                    foreach (Server srv in _servers)
+                    {
+                        if (!IsBlackListed(srv))
+                        {
+                            _serverQueue.Enqueue(srv);
+                        }
+                    }
+                }
+            }
+        }
+
+        public void Remove(Server server)
+        {
+            lock (_lock)
+            {
+                _servers.Remove(server);
+                _serverQueue = new Queue<Server>();
+                _blackListed.RemoveWhere(x => x == server);
+
+                foreach (var s in _servers)
+                {
+                    if (!_blackListed.Contains(s))
+                        _serverQueue.Enqueue(s);
+                }
+            }
+        }
+
+        #endregion
+
+        #region IEnumerable<Server> Members
+
+        public IEnumerator<Server> GetEnumerator()
+        {
+            return _servers.GetEnumerator();
+        }
+
+        #endregion
+
+        #region IEnumerable Members
+
+        System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
+        {
+            return GetEnumerator();
+        }
+
+        #endregion
+    }
 }

test/FluentCassandra.Tests/Connections/RoundRobinServerManagerTests.cs

@@ -0,0 +1,82 @@
+using System;
+using System.Collections.Generic;
+using Xunit;
+
+namespace FluentCassandra.Connections.Tests
+{
+    public class RoundRobinServerManagerTests
+    {
+        [Fact]
+        public void CanBlackListAndCleanQueueTest()
+        {
+            RoundRobinServerManager target = new RoundRobinServerManager(new ConnectionBuilder("Server=unit-test-1,unit-test-2,unit-test-3"));
+
+            Server srv = new Server("unit-test-4");
+            target.Add(srv);
+
+            bool gotServer4 = false;
+
+            for (int i = 0; i < 4; i++)
+            {
+                Server server = target.Next();
+                if (server.ToString().Equals(srv.ToString(), StringComparison.OrdinalIgnoreCase))
+                {
+                    gotServer4 = true;
+                    break;
+                }
+            }
+
+            Assert.True(gotServer4);
+
+            target.BlackList(srv);
+
+            gotServer4 = false;
+            for (int i = 0; i < 4; i++)
+            {
+                Server server = target.Next();
+                if (server.Equals(srv))
+                {
+                    gotServer4 = true;
+                    break;
+                }
+            }
+
+            Assert.False(gotServer4);
+        }
+
+        [Fact]
+        public void HasNextWithMoreThanHalfBlacklistedTest()
+        {
+            RoundRobinServerManager target = new RoundRobinServerManager(new ConnectionBuilder("Server=unit-test-1"));
+
+            Server srv1 = null;
+            Server srv2 = new Server("unit-test-2");
+            Server srv3 = new Server("unit-test-3");
+            Server srv4 = new Server("unit-test-4");
+            target.Add(srv2);
+            target.Add(srv3);
+            target.Add(srv4);
+            List<Server> servers = new List<Server> { new Server("unit-test-1"), srv2, srv3, srv4 };
+
+            for (int i = 0; i < 4; i++)
+            {
+                Server srv = target.Next();
+                Assert.True(servers[i].ToString().Equals(srv.ToString(), StringComparison.OrdinalIgnoreCase));
+                if(i == 0)
+                {
+                    srv1 = srv;
+                }
+            }
+
+            target.BlackList(srv2);
+            target.BlackList(srv3);
+            Assert.True(target.HasNext);
+
+            target.BlackList(srv1);
+            Assert.True(target.HasNext);
+
+            target.BlackList(srv4);
+            Assert.False(target.HasNext);
+        }
+    }
+}

test/FluentCassandra.Tests/FluentCassandra.Tests.csproj

@@ -62,6 +62,7 @@
     <Compile Include="Connections\ConnectionBuilderTests.cs" />
     <Compile Include="Connections\ConnectionProviderTests.cs" />
     <Compile Include="Connections\NormalConnectionProviderTests.cs" />
+    <Compile Include="Connections\RoundRobinServerManagerTests.cs" />
     <Compile Include="CqlHelperTest.cs" />
     <Compile Include="Helper.cs" />
     <Compile Include="Linq\LinqToCqlObjectsCassandraTests.cs" />