Added OpenQuestions.md file to log ideas and questions to address

Fix 'PrevLogIndex' in AppendEntries so it properly covers empty log cornercase
Moved timer reinitialization at the end of event to prevent triggering too fast when timeout is set to 0

OpenQuestions.md

@@ -0,0 +1,8 @@
+** RAFTiNG Open questions **
+=============================
+
+This document list questions that should be answered in the course of the project.
+
+
+** Stability **
+- how can RAFTiNG handle configuration errors?

RAFTiNG.Tests/Acceptance/BasicRaftSteps.cs

@@ -35,11 +35,13 @@ public class BasicRaftSteps: IDisposable
     {
         private Middleware middleware;
 
+        private IDisposable logHandle;
+
         private List<Node<string>> nodes;
 
-        static BasicRaftSteps()
+        public BasicRaftSteps()
         {
-            Helpers.InitLog4Net();
+            logHandle = Helpers.InitLog4Net();
         }
 
         [Given(@"I have deployed (.*) instances")]
@@ -93,6 +95,7 @@ public void WhenIWaitSeconde(int p0)
         /// </summary>
         public void Dispose()
         {
+            logHandle.Dispose();
             foreach (var node in nodes)
             {
                 node.Dispose();

RAFTiNG.Tests/Helpers.cs

@@ -14,6 +14,7 @@
 //  --------------------------------------------------------------------------------------------------------------------
 namespace RAFTiNG.Tests
 {
+    using System;
     using System.Collections.Generic;
 
     using log4net;
@@ -49,19 +50,34 @@ public static NodeSettings BuildNodeSettings(string nodeId, IEnumerable<string>
             return settings;
         }
 
-        internal static void InitLog4Net()
+        internal static IDisposable InitLog4Net()
         {
-            var appender = new ConsoleAppender();
-            appender.Layout =
-                new PatternLayout("%date{HH:mm:ss,fff} %-5level - %message (%logger) [%thread]%newline");
-            appender.Threshold = Level.Trace;
+            var appender = new ConsoleAppender
+                               {
+                                   Layout =
+                                       new PatternLayout(
+                                       "%date{HH:mm:ss,fff} %-5level - %message (%logger) [%thread]%newline"),
+                                   Threshold = Level.Trace
+                               };
             appender.ActivateOptions();
 
             // Configure the root logger.
             var h = (log4net.Repository.Hierarchy.Hierarchy)LogManager.GetRepository();
             var rootLogger = h.Root;
             rootLogger.Level = h.LevelMap["TRACE"];
             BasicConfigurator.Configure(appender);
+            return new LogWrapper();
+        }
+
+        private class LogWrapper: IDisposable 
+        {
+            /// <summary>
+            /// Exécute les tâches définies par l'application associées à la libération ou à la redéfinition des ressources non managées.
+            /// </summary>
+            public void Dispose()
+            {
+                log4net.LogManager.Shutdown();
+            }
         }
     }
 }

RAFTiNG.Tests/RAFTiNG.Tests.csproj

@@ -59,6 +59,7 @@
     </Compile>
     <Compile Include="Acceptance\BasicRaftSteps.cs" />
     <Compile Include="Helpers.cs" />
+    <Compile Include="Unit\LogReplicationTest.cs" />
     <Compile Include="Unit\PersistedStateTests.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="Integration\RaftCommunication.feature.cs">

RAFTiNG.Tests/Unit/BasicNodeTest.cs

@@ -197,35 +197,38 @@ public void NodeWithMoreRescentTermDoesNotGrantVote()
         [Test]
         public void NodeStaysAFollowerWhenReceiveAppendEntries()
         {
-            var settings = Helpers.BuildNodeSettings("1", new[] { "1", "2", "3", "4", "5" });
-            settings.TimeoutInMs = 10;
-            var node = new Node<string>(settings);
-
-            using (node)
+            using (Helpers.InitLog4Net())
             {
-                var middleware = new Middleware();
-                node.SetMiddleware(middleware);
-                node.Initialize();
-                Thread.Sleep(30);
+                var settings = Helpers.BuildNodeSettings("1", new[] { "1", "2", "3", "4", "5" });
+                settings.TimeoutInMs = 10;
+                var node = new Node<string>(settings);
 
-                // should switch to candidate
-                Check.ThatEnum(node.Status).IsEqualTo(NodeStatus.Candidate);
+                using (node)
+                {
+                    var middleware = new Middleware();
+                    node.SetMiddleware(middleware);
+                    node.Initialize();
+                    Thread.Sleep(50);
 
-                // now we pretend there is a leader
-                var message = new AppendEntries<string>();
+                    // should switch to candidate
+                    Check.ThatEnum(node.Status).IsEqualTo(NodeStatus.Candidate);
 
-                message.LeaderId = "2";
-                message.LeaderTerm = 5;
-                message.PrevLogIndex = 0;
-                message.PrevLogTerm = 0;
-                var entry = new LogEntry<string>("dummy", 1L, 0);
-                message.Entries = new[] {entry};
-                middleware.SendMessage("1", message);
+                    // now we pretend there is a leader
+                    var message = new AppendEntries<string>();
 
-                Check.ThatEnum(node.Status).IsEqualTo(NodeStatus.Follower);
+                    message.LeaderId = "2";
+                    message.LeaderTerm = 5;
+                    message.PrevLogIndex = -1;
+                    message.PrevLogTerm = 0;
+                    var entry = new LogEntry<string>("dummy", 1L);
+                    message.Entries = new[] { entry };
+                    middleware.SendMessage("1", message);
 
-                Check.That(node.State.LogEntries.Count).IsEqualTo(1);
+                    Check.ThatEnum(node.Status).IsEqualTo(NodeStatus.Follower);
 
+                    Check.That(node.State.LogEntries.Count).IsEqualTo(1);
+
+                }
             }
         }
 

RAFTiNG.Tests/Unit/LogReplicationTest.cs

@@ -0,0 +1,60 @@
+//  --------------------------------------------------------------------------------------------------------------------
+// <copyright file="LogReplicationTest.cs" company="Cyrille DUPUYDAUBY">
+//   Copyright 2013 Cyrille DUPUYDAUBY
+//   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.
+// </copyright>
+//  --------------------------------------------------------------------------------------------------------------------
+
+namespace RAFTiNG.Tests.Unit
+{
+    using System.Threading;
+
+    using NFluent;
+
+    using NUnit.Framework;
+
+    [TestFixture]
+    public class LogReplicationTest
+    {
+        [Test]
+        public void EmptyLogIsfilledTest()
+        {
+            using (Helpers.InitLog4Net())
+            {
+                var settings = Helpers.BuildNodeSettings("1", new[] { "1", "2" });
+                settings.TimeoutInMs = Timeout.Infinite;
+                var logReplicator = new LogReplicator<string>();
+                var middleware = new Middleware();
+
+                using (var node = new Node<string>(settings))
+                {
+                    settings = Helpers.BuildNodeSettings("2", new[] { "1", "2" });
+                    settings.TimeoutInMs = 1;
+                    var leader = new Node<string>(settings);
+                    leader.SetMiddleware(middleware);
+                    node.SetMiddleware(middleware);
+                    node.Initialize();
+                    leader.Initialize();
+                    Thread.Sleep(30);
+
+                    // should stay follower
+                    Check.ThatEnum(node.Status).IsEqualTo(NodeStatus.Follower);
+
+                    Check.ThatEnum(leader.Status).IsEqualTo(NodeStatus.Leader);
+                }
+            }
+        }
+    }
+
+    public class LogReplicator<T>
+    {
+    }
+}

RAFTiNG.Tests/Unit/PersistedStateTests.cs

@@ -47,9 +47,8 @@ public void CanAddCommands()
             test.AddEntry(new LogEntry<string>("dummy"));
             test.AddEntry(new LogEntry<string>("dummy"));
 
-            Check.That(test.LogEntries[0].Index).IsEqualTo(0);
+            Check.That(test.LogEntries[0].Term).IsEqualTo(0L);
             Check.That(test.LogEntries[1].Term).IsEqualTo(0L);
-            Check.That(test.LogEntries[1].Index).IsEqualTo(1);
         }
 
         [Test]
@@ -85,7 +84,12 @@ public void LogEntryMatches()
         [Test]
         public void AppendEntries()
         {
-
+            var test = new PersistedState<string> { CurrentTerm = 1 };
+
+            test.AddEntry(new LogEntry<string>("dummy"));
+            test.CurrentTerm = 2;
+            test.AppendEntries(-1,  new[] {new LogEntry<string>("dummy", 2)});
+            Check.That(test.EntryMatches(0, 2L)).IsTrue();
         }
     }
 }

RAFTiNG.sln

@@ -8,6 +8,7 @@ EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Solution Items", "Solution Items", "{7340327F-5CCF-4EFE-8E96-23957CCF92E6}"
 	ProjectSection(SolutionItems) = preProject
 		License.txt = License.txt
+		OpenQuestions.md = OpenQuestions.md
 		ReadMe.md = ReadMe.md
 		Specifications.pdf = Specifications.pdf
 	EndProjectSection

RAFTiNG/LogEntry.cs

@@ -37,13 +37,10 @@ public sealed class LogEntry<T>
         /// </param>
         /// <param name="term">Current term when command is stored.
         /// </param>
-        /// <param name="index">Index for the current command.
-        /// </param>
-        public LogEntry(T command, long term, int index)
+        public LogEntry(T command, long term)
         {
             this.Command = command;
             this.Term = term;
-            this.Index = index;
         }
 
         /// <summary>
@@ -69,11 +66,6 @@ public LogEntry(T command)
         /// </summary>
         public long Term { get; private set; }
 
-        /// <summary>
-        /// Gets the index for this command.
-        /// </summary>
-        public int Index { get; private set; }
-
         #endregion
 
         #region methods
@@ -115,7 +107,7 @@ public override int GetHashCode()
         {
             unchecked
             {
-                return (this.Term.GetHashCode() * 397) ^ this.Index.GetHashCode();
+                return this.Term.GetHashCode();
             }
         }
 
@@ -130,7 +122,7 @@ public override int GetHashCode()
         /// </returns>
         private bool Equals(LogEntry<T> other)
         {
-            return this.Term == other.Term && this.Index == other.Index;
+            return this.Term == other.Term;
         }
 
         #endregion

RAFTiNG/Messages/AppendEntriesAck.cs

@@ -19,7 +19,6 @@ namespace RAFTiNG.Messages
     /// </summary>
     public class AppendEntriesAck
     {
-
         private string nodeId;
 
         private long term;
@@ -51,6 +50,7 @@ public long Term
             {
                 return this.term;
             }
+
             set
             {
                 this.term = value;
@@ -69,6 +69,7 @@ public bool Success
             {
                 return this.success;
             }
+
             set
             {
                 this.success = value;

RAFTiNG/PersistedState.cs

@@ -18,7 +18,6 @@
 
 namespace RAFTiNG
 {
-    using System;
     using System.Collections.Generic;
 
     /// <summary>
@@ -87,7 +86,7 @@ public int LastPersistedIndex
         {
             get
             {
-                return this.LogEntries.Count > 0 ? this.LogEntries[this.LogEntries.Count - 1].Index : 0;
+                return this.LogEntries.Count > 0 ? this.LogEntries.Count - 1 : -1;
             }
         }
 
@@ -110,7 +109,7 @@ public void AddEntry(LogEntry<T> logEntry)
             if (logEntry.Term == 0)
             {
                 var newEntry = new LogEntry<T>(
-                    logEntry.Command, this.CurrentTerm, this.LogEntries.Count);
+                    logEntry.Command, this.CurrentTerm);
                 this.LogEntries.Add(newEntry);
             }
             else
@@ -125,7 +124,7 @@ public void AddEntry(LogEntry<T> logEntry)
         /// <param name="command">The command.</param>
         public void AddEntry(T command)
         {
-            var newEntry = new LogEntry<T>(command, this.currentTerm, this.LogEntries.Count);
+            var newEntry = new LogEntry<T>(command, this.currentTerm);
             this.LogEntries.Add(newEntry);
         }
 
@@ -168,10 +167,11 @@ public bool LogIsBetterThan(long lastLogTerm, long lastLogIndex)
         /// <returns>true if the entry at index <paramref name="index"/> has the term <paramref name="term"/>.</returns>
         public bool EntryMatches(int index, long term)
         {
-            if (index >= this.LogEntries.Count)
+            if (index >= this.LogEntries.Count || index < 0)
             {
-                return false;
+                return index == -1;
             }
+
             return this.LogEntries[index].Term == term;
         }
 
@@ -187,7 +187,7 @@ public void AppendEntries(int prevLogIndex, IEnumerable<LogEntry<T>> entries)
                 // nothing to add
                 return;
             }
-
+            prevLogIndex++;
             foreach (var logEntry in entries)
             {
                if (prevLogIndex == this.LogEntries.Count)
@@ -198,6 +198,7 @@ public void AppendEntries(int prevLogIndex, IEnumerable<LogEntry<T>> entries)
                {
                    this.LogEntries[prevLogIndex] = logEntry;
                }
+
                 prevLogIndex++;
             }
         }