Many improvements to server stability+performance

Sorry for the vague commit message. There were a lot of changes. Here's
a list of most of them:

- Lighting updates are timeboxed each frame
- The next environment frame is queued sooner if the current one took
  longer (as soon as immediately)
- Issues with the physics engines and mobs using it were (mostly) fixed,
  mobs no longer freak out and get stuck on physics objects
- Mob AI/pathfinding is done more intelligently
- The player can no longer spawn in an ocean or a desert biome
- Some deadlocks in Region were fixed (more remain to be fixed)

The current performance bottlenecks are lighting (still) and propegating
initial chunk loads to blocks that need to schedule things (such as
grass blocks). I think the main culprit in the latter case is grass
blocks and water blocks. The former can be improved by adding a block
cache to World, but that'll take some custom work. This step is just
gonna be slow no matter what, we might have to split it across several
frames but it's never going to be great.

There still seems to be a deadlock somewhere in all of this mess, in the
world code. I'll find it later.

TrueCraft.API/Entities/IMobEntity.cs

@@ -1,4 +1,5 @@
 using System;
+using TrueCraft.API.AI;
 using TrueCraft.API.Physics;
 
 namespace TrueCraft.API.Entities
@@ -8,6 +9,7 @@ namespace TrueCraft.API.Entities
         event EventHandler PathComplete;
         PathResult CurrentPath { get; set; }
         bool AdvancePath(TimeSpan time, bool faceRoute = true);
+        IMobState CurrentState { get; set; }
         void Face(Vector3 target);
     }
 }

TrueCraft.API/Server/IEntityManager.cs

@@ -2,11 +2,13 @@
 using TrueCraft.API.Entities;
 using System.Collections.Generic;
 using TrueCraft.API.Networking;
+using TrueCraft.API.World;
 
 namespace TrueCraft.API.Server
 {
     public interface IEntityManager
     {
+        IWorld World { get; }
         TimeSpan TimeSinceLastUpdate { get; }
         /// <summary>
         /// Adds an entity to the world and assigns it an entity ID.

TrueCraft.API/World/IBiomeMap.cs

@@ -22,7 +22,7 @@ namespace TrueCraft.API.World
         IList<BiomeCell> BiomeCells { get; }
         void AddCell(BiomeCell cell);
         byte GetBiome(Coordinates2D location);
-        byte GenerateBiome(int seed, IBiomeRepository biomes, Coordinates2D location);
+        byte GenerateBiome(int seed, IBiomeRepository biomes, Coordinates2D location, bool spawn);
         BiomeCell ClosestCell(Coordinates2D location);
         double ClosestCellPoint(Coordinates2D location);
     }

TrueCraft.API/World/IBiomeProvider.cs

@@ -8,6 +8,7 @@ namespace TrueCraft.API.World
 {
     public interface IBiomeProvider
     {
+        bool Spawn { get; }
         byte ID { get; }
         int Elevation { get; }
         double Temperature { get; }

TrueCraft.API/World/IBiomeRepository.cs

@@ -8,7 +8,7 @@ namespace TrueCraft.API.World
     public interface IBiomeRepository
     {
         IBiomeProvider GetBiome(byte id);
-        IBiomeProvider GetBiome(double temperature, double rainfall);
+        IBiomeProvider GetBiome(double temperature, double rainfall, bool spawn);
         void RegisterBiomeProvider(IBiomeProvider provider);
     }
 }

TrueCraft.Core.Test/Logic/BlockProviderTest.cs

@@ -23,7 +23,7 @@ namespace TrueCraft.Core.Test.Logic
         public Mock<IRemoteClient> User { get; set; }
         public Mock<IBlockRepository> BlockRepository { get; set; }
 
-        [TestFixtureSetUp]
+        [OneTimeSetUp]
         public void SetUp()
         {
             World = new Mock<IWorld>();

TrueCraft.Core.Test/World/ChunkTest.cs

@@ -14,7 +14,7 @@ namespace TrueCraft.Core.Test.World
     {
         public Chunk Chunk { get; set; }
 
-        [TestFixtureSetUp]
+        [OneTimeSetUp]
         public void SetUp()
         {
             var assemblyDir = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location);

TrueCraft.Core.Test/World/RegionTest.cs

@@ -12,7 +12,7 @@ namespace TrueCraft.Core.Test.World
     {
         public Region Region { get; set; }
 
-        [TestFixtureSetUp]
+        [OneTimeSetUp]
         public void SetUp()
         {
             var world = new TrueCraft.Core.World.World();

TrueCraft.Core.Test/World/WorldTest.cs

@@ -14,7 +14,7 @@ namespace TrueCraft.Core.Test.World
     {
         public TrueCraft.Core.World.World World { get; set; }
 
-        [TestFixtureSetUp]
+        [OneTimeSetUp]
         public void SetUp()
         {
             var assemblyDir = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location);

TrueCraft.Core/AI/AStarPathFinder.cs

@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using TrueCraft.API;
 using TrueCraft.API.World;
 using System.Diagnostics;
+using TrueCraft.API.Logic;
 
 namespace TrueCraft.Core.AI
 {
@@ -40,8 +41,12 @@ namespace TrueCraft.Core.AI
         private bool CanOccupyVoxel(IWorld world, BoundingBox box, Coordinates3D voxel)
         {
             var id = world.GetBlockID(voxel);
-            // TODO: Make this more sophisticated
+            if (world.BlockRepository == null)
-            return id == 0;
+                return id == 0;
+            var provider = world.BlockRepository.GetBlockProvider(id);
+            if (provider == null)
+                return true;
+            return provider.BoundingBox == null;
         }
 
         private IEnumerable<Coordinates3D> GetNeighbors(IWorld world, BoundingBox subject, Coordinates3D current)

TrueCraft.Core/AI/IdleState.cs

@@ -0,0 +1,28 @@
+using System;
+using TrueCraft.API.AI;
+using TrueCraft.API.Entities;
+using TrueCraft.API.Server;
+
+namespace TrueCraft.Core.AI
+{
+    public class IdleState : IMobState
+    {
+        private DateTime Expiry { get; set; }
+        private IMobState NextState { get; set; }
+        
+        public IdleState(IMobState nextState, DateTime? expiry = null)
+        {
+            NextState = nextState;
+            if (expiry != null)
+                Expiry = expiry.Value;
+            else
+                Expiry = DateTime.UtcNow.AddSeconds(MathHelper.Random.Next(5, 15));
+        }
+
+        public void Update(IMobEntity entity, IEntityManager manager)
+        {
+            if (DateTime.UtcNow >= Expiry)
+                entity.CurrentState = NextState;
+        }
+    }
+}

TrueCraft.Core/AI/WanderState.cs

@@ -5,16 +5,12 @@ using TrueCraft.API.Server;
 using TrueCraft.API;
 using TrueCraft.API.World;
 using System.Threading.Tasks;
+using TrueCraft.API.Logic;
 
 namespace TrueCraft.Core.AI
 {
     public class WanderState : IMobState
     {
-        /// <summary>
-        /// Chance that mob will decide to move during an update when idle.
-        /// Chance is equal to 1 / IdleChance.
-        /// </summary>
-        public int IdleChance { get; set; }
         /// <summary>
         /// The maximum distance the mob will move in an iteration.
         /// </summary>
@@ -24,7 +20,6 @@ namespace TrueCraft.Core.AI
 
         public WanderState()
         {
-            IdleChance = 10;
             Distance = 25;
             PathFinder = new AStarPathFinder();
         }
@@ -33,25 +28,27 @@ namespace TrueCraft.Core.AI
         {
             var cast = entity as IEntity;
             if (entity.CurrentPath != null)
-                entity.AdvancePath(manager.TimeSinceLastUpdate);
+            {
+                if (entity.AdvancePath(manager.TimeSinceLastUpdate))
+                {
+                    entity.CurrentState = new IdleState(new WanderState());
+                }
+            }
             else
             {
-                if (MathHelper.Random.Next(IdleChance) == 0)
+                var target = new Coordinates3D(
+                    (int)(cast.Position.X + (MathHelper.Random.Next(Distance) - Distance / 2)),
+                    0,
+                    (int)(cast.Position.Z + (MathHelper.Random.Next(Distance) - Distance / 2))
+                );
+                IChunk chunk;
+                var adjusted = entity.World.FindBlockPosition(target, out chunk, generate: false);
+                target.Y = chunk.GetHeight((byte)adjusted.X, (byte)adjusted.Z) + 1;
+                Task.Factory.StartNew(() =>
                 {
-                    var target = new Coordinates3D(
+                    entity.CurrentPath = PathFinder.FindPath(entity.World, entity.BoundingBox,
-                        (int)(cast.Position.X + (MathHelper.Random.Next(Distance) - Distance / 2)),
+                        (Coordinates3D)cast.Position, target);
-                        0,
+                });
-                        (int)(cast.Position.Z + (MathHelper.Random.Next(Distance) - Distance / 2))
-                    );
-                    IChunk chunk;
-                    var adjusted = entity.World.FindBlockPosition(target, out chunk, generate: false);
-                    target.Y = chunk.GetHeight((byte)adjusted.X, (byte)adjusted.Z) + 1;
-                    Task.Factory.StartNew(() =>
-                    {
-                            entity.CurrentPath = PathFinder.FindPath(entity.World, entity.BoundingBox,
-                                (Coordinates3D)cast.Position, target);
-                    });
-                }
             }
         }
     }

TrueCraft.Core/Entities/MobEntity.cs

@@ -97,11 +97,6 @@ namespace TrueCraft.Core.Entities
 
         public IMobState CurrentState { get; set; }
 
-        public void ChangeState(IMobState state)
-        {
-            CurrentState = state;
-        }
-
         public void Face(Vector3 target)
         {
             var diff = target - Position;
@@ -115,14 +110,17 @@ namespace TrueCraft.Core.Entities
             {
                 // Advance along path
                 var target = (Vector3)CurrentPath.Waypoints[CurrentPath.Index];
+                target += new Vector3(Size.Width / 2, 0, Size.Depth / 2); // Center it
                 target.Y = Position.Y; // TODO: Find better way of doing this
                 if (faceRoute)
                     Face(target);
                 var lookAt = Vector3.Forwards.Transform(Matrix.CreateRotationY(MathHelper.ToRadians(-(Yaw - 180) + 180)));
                 lookAt *= modifier;
                 Velocity = new Vector3(lookAt.X, Velocity.Y, lookAt.Z);
-                if (Position.DistanceTo(target) < 0.1)
+                if (Position.DistanceTo(target) < Velocity.Distance)
                 {
+                    Position = target;
+                    Velocity = Vector3.Zero;
                     CurrentPath.Index++;
                     if (CurrentPath.Index >= CurrentPath.Waypoints.Count)
                     {

TrueCraft.Core/Lighting/WorldLighting.cs

@@ -300,6 +300,7 @@ namespace TrueCraft.Core.Lighting
             EnqueueOperation(new BoundingBox(new Vector3(coords.X, 0, coords.Z),
                 new Vector3(coords.X + Chunk.Width, chunk.MaxHeight + 2, coords.Z + Chunk.Depth)),
                 true, true);
+            TryLightNext();
             while (flush && TryLightNext())
             {
             }

TrueCraft.Core/Physics/PhysicsEngine.cs

@@ -41,10 +41,21 @@ namespace TrueCraft.Core.Physics
                 Entities.Remove(entity);
         }
 
+        private void TruncateVelocity(IPhysicsEntity entity, double multiplier)
+        {
+            if (Math.Abs(entity.Velocity.X) < 0.1 * multiplier)
+                entity.Velocity = new Vector3(0, entity.Velocity.Y, entity.Velocity.Z);
+            if (Math.Abs(entity.Velocity.Y) < 0.1 * multiplier)
+                entity.Velocity = new Vector3(entity.Velocity.X, 0, entity.Velocity.Z);
+            if (Math.Abs(entity.Velocity.Z) < 0.1 * multiplier)
+                entity.Velocity = new Vector3(entity.Velocity.X, entity.Velocity.Y, 0);
+            entity.Velocity.Clamp(entity.TerminalVelocity);
+        }
+
         public void Update(TimeSpan time)
         {
             double multiplier = time.TotalSeconds;
-            if (multiplier == 0)
+            if (multiplier == 0 || multiplier > 1)
                 return;
             lock (EntityLock)
             {
@@ -55,9 +66,7 @@ namespace TrueCraft.Core.Physics
                     {
                         entity.Velocity -= new Vector3(0, entity.AccelerationDueToGravity * multiplier, 0);
                         entity.Velocity *= 1 - entity.Drag * multiplier;
-                        if (entity.Velocity.Distance < 0.001)
+                        TruncateVelocity(entity, multiplier);
-                            entity.Velocity = Vector3.Zero;
-                        entity.Velocity.Clamp(entity.TerminalVelocity);
 
                         Vector3 collision, before = entity.Velocity;
 
@@ -74,8 +83,8 @@ namespace TrueCraft.Core.Physics
                             if (TestTerrainCollisionCylinder(aabbEntity, out collision))
                                 aabbEntity.TerrainCollision(collision, before);
                         }
-
                         entity.EndUpdate(entity.Position + entity.Velocity);
+                        TruncateVelocity(entity, multiplier);
                     }
                 }
             }

TrueCraft.Core/TerrainGen/BiomeRepository.cs

@@ -47,7 +47,7 @@ namespace TrueCraft.Core.TerrainGen
             return BiomeProviders[id];
         }
 
-        public IBiomeProvider GetBiome(double temperature, double rainfall)
+        public IBiomeProvider GetBiome(double temperature, double rainfall, bool spawn)
         {
             List<IBiomeProvider> temperatureResults = new List<IBiomeProvider>();
             foreach (var biome in BiomeProviders)
@@ -79,7 +79,10 @@ namespace TrueCraft.Core.TerrainGen
 
             foreach (var biome in BiomeProviders)
             {
-                if (biome != null && biome.Rainfall.Equals(rainfall) && temperatureResults.Contains(biome))
+                if (biome != null
+                    && biome.Rainfall.Equals(rainfall)
+                    && temperatureResults.Contains(biome)
+                    && (!spawn || biome.Spawn))
                 {
                     return biome;
                 }
@@ -92,14 +95,15 @@ namespace TrueCraft.Core.TerrainGen
                 if (biome != null)
                 {
                     var difference = Math.Abs(temperature - biome.Temperature);
-                    if (biomeProvider == null || difference < rainfallDifference)
+                    if ((biomeProvider == null || difference < rainfallDifference)
+                        && (!spawn || biome.Spawn))
                     {
                         biomeProvider = biome;
                         rainfallDifference = (float)difference;
                     }
                 }
             }
-            return biomeProvider;
+            return biomeProvider ?? new PlainsBiome();
         }
     }
 }

TrueCraft.Core/TerrainGen/Biomes/BiomeProvider.cs

@@ -27,6 +27,14 @@ namespace TrueCraft.Core.TerrainGen.Biomes
         /// The base rainfall of the biome.
         /// </summary>
         public abstract double Rainfall { get; }
+        
+        public virtual bool Spawn
+        {
+            get
+            {
+                return true;
+            }
+        }
 
         /// <summary>
         /// The tree types generated in the biome.

TrueCraft.Core/TerrainGen/Biomes/DesertBiome.cs

@@ -25,6 +25,11 @@ namespace TrueCraft.Core.TerrainGen.Biomes
         {
             get { return 0.0f; }
         }
+        
+        public override bool Spawn
+        {
+            get { return false; }
+        }
 
         public override TreeSpecies[] Trees
         {

TrueCraft.Core/TerrainGen/Decorators/LiquidDecorator.cs

@@ -12,7 +12,7 @@ namespace TrueCraft.Core.TerrainGen.Decorators
 {
     public class LiquidDecorator : IChunkDecorator
     {
-        const int WaterLevel = 40;
+        public static readonly int WaterLevel = 40;
 
         public void Decorate(IWorld world, IChunk chunk, IBiomeRepository biomes)
         {

TrueCraft.Core/TerrainGen/StandardGenerator.cs

@@ -137,7 +137,9 @@ namespace TrueCraft.Core.TerrainGen
                         || cellValue.Equals(1)
                         && world.BiomeDiagram.ClosestCellPoint(location) >= featurePointDistance)
                     {
-                        byte id = (SingleBiome) ? GenerationBiome : world.BiomeDiagram.GenerateBiome(seed, Biomes, location);
+                        byte id = (SingleBiome) ? GenerationBiome
+                            : world.BiomeDiagram.GenerateBiome(seed, Biomes, location,
+                                IsSpawnCoordinate(location.X, location.Z));
                         var cell = new BiomeCell(id, location);
                         world.BiomeDiagram.AddCell(cell);
                     }
@@ -207,14 +209,23 @@ namespace TrueCraft.Core.TerrainGen
             return world.BiomeDiagram.GetBiome(location);
         }
 
+        bool IsSpawnCoordinate(int x, int z)
+        {
+            return x > -1000 && x < 1000 || z > -1000 && z < 1000;
+        }
+
         int GetHeight(int x, int z)
         {
-            var NoiseValue = FinalNoise.Value2D(x, z) + GroundLevel;
+            var value = FinalNoise.Value2D(x, z) + GroundLevel;
-            if (NoiseValue < 0)
+            var coords = new Coordinates2D(x, z);
-                NoiseValue = GroundLevel;
+            double distance = IsSpawnCoordinate(x, z) ? coords.Distance : 1000;
-            if (NoiseValue > Chunk.Height)
+            if (distance < 1000) // Avoids deep water within 1km sq of spawn
-                NoiseValue = Chunk.Height - 1;
+                value += (1 - distance / 1000f) * 12;
-            return (int)NoiseValue;
+            if (value < 0)
+                value = GroundLevel;
+            if (value > Chunk.Height)
+                value = Chunk.Height - 1;
+            return (int)value;
         }
     }
 }

TrueCraft.Core/TrueCraft.Core.csproj

@@ -355,6 +355,7 @@
     <Compile Include="Windows\FurnaceWindow.cs" />
     <Compile Include="Paths.cs" />
     <Compile Include="Logic\CraftingRepository.cs" />
+    <Compile Include="AI\IdleState.cs" />
   </ItemGroup>
   <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
   <ItemGroup>

TrueCraft.Core/World/BiomeMap.cs

@@ -42,11 +42,11 @@ namespace TrueCraft.Core.World
             return BiomeID;
         }
 
-        public byte GenerateBiome(int seed, IBiomeRepository biomes, Coordinates2D location)
+        public byte GenerateBiome(int seed, IBiomeRepository biomes, Coordinates2D location, bool spawn)
         {
             double temp = Math.Abs(TempNoise.Value2D(location.X, location.Z));
             double rainfall = Math.Abs(RainNoise.Value2D(location.X, location.Z));
-            byte ID = biomes.GetBiome(temp, rainfall).ID;
+            byte ID = biomes.GetBiome(temp, rainfall, spawn).ID;
             return ID;
         }
 

TrueCraft.Core/World/Region.cs

@@ -67,58 +67,55 @@ namespace TrueCraft.Core.World
         public IChunk GetChunk(Coordinates2D position, bool generate = true)
         {
             // TODO: This could use some refactoring
-            lock (Chunks)
+            if (!Chunks.ContainsKey(position))
             {
-                if (!Chunks.ContainsKey(position))
+                if (regionFile != null)
                 {
-                    if (regionFile != null)
+                    // Search the stream for that region
+                    lock (streamLock)
                     {
-                        // Search the stream for that region
+                        var chunkData = GetChunkFromTable(position);
-                        lock (regionFile)
+                        if (chunkData == null)
                         {
-                            var chunkData = GetChunkFromTable(position);
+                            if (World.ChunkProvider == null)
-                            if (chunkData == null)
+                                throw new ArgumentException("The requested chunk is not loaded.", "position");
-                            {
+                            if (generate)
-                                if (World.ChunkProvider == null)
+                                GenerateChunk(position);
-                                    throw new ArgumentException("The requested chunk is not loaded.", "position");
+                            else
-                                if (generate)
+                                return null;
-                                    GenerateChunk(position);
+                            return Chunks[position];
-                                else
+                        }
-                                    return null;
+                        regionFile.Seek(chunkData.Item1, SeekOrigin.Begin);
-                                return Chunks[position];
+                        /*int length = */
-                            }
+                        new MinecraftStream(regionFile).ReadInt32(); // TODO: Avoid making new objects here, and in the WriteInt32
-                            regionFile.Seek(chunkData.Item1, SeekOrigin.Begin);
+                        int compressionMode = regionFile.ReadByte();
-                            /*int length = */
+                        switch (compressionMode)
-                            new MinecraftStream(regionFile).ReadInt32(); // TODO: Avoid making new objects here, and in the WriteInt32
+                        {
-                            int compressionMode = regionFile.ReadByte();
+                            case 1: // gzip
-                            switch (compressionMode)
+                                throw new NotImplementedException("gzipped chunks are not implemented");
-                            {
+                            case 2: // zlib
-                                case 1: // gzip
+                                var nbt = new NbtFile();
-                                    throw new NotImplementedException("gzipped chunks are not implemented");
+                                nbt.LoadFromStream(regionFile, NbtCompression.ZLib, null);
-                                case 2: // zlib
+                                var chunk = Chunk.FromNbt(nbt);
-                                    var nbt = new NbtFile();
+                                Chunks.Add(position, chunk);
-                                    nbt.LoadFromStream(regionFile, NbtCompression.ZLib, null);
+                                World.OnChunkLoaded(new ChunkLoadedEventArgs(chunk));
-                                    var chunk = Chunk.FromNbt(nbt);
+                                break;
-                                    Chunks.Add(position, chunk);
+                            default:
-                                    World.OnChunkLoaded(new ChunkLoadedEventArgs(chunk));
+                                throw new InvalidDataException("Invalid compression scheme provided by region file.");
-                                    break;
-                                default:
-                                    throw new InvalidDataException("Invalid compression scheme provided by region file.");
-                            }
                         }
                     }
-                    else if (World.ChunkProvider == null)
-                        throw new ArgumentException("The requested chunk is not loaded.", "position");
-                    else
-                    {
-                        if (generate)
-                            GenerateChunk(position);
-                        else
-                            return null;
-                    }
                 }
-                return Chunks[position];
+                else if (World.ChunkProvider == null)
+                    throw new ArgumentException("The requested chunk is not loaded.", "position");
+                else
+                {
+                    if (generate)
+                        GenerateChunk(position);
+                    else
+                        return null;
+                }
             }
+            return Chunks[position];
         }
 
         public void GenerateChunk(Coordinates2D position)
@@ -162,41 +159,38 @@ namespace TrueCraft.Core.World
         /// </summary>
         public void Save()
         {
-            lock (Chunks)
+            lock (streamLock)
             {
-                lock (streamLock)
+                var toRemove = new List<Coordinates2D>();
+                foreach (var kvp in Chunks)
                 {
-                    var toRemove = new List<Coordinates2D>();
+                    var chunk = kvp.Value;
-                    foreach (var kvp in Chunks)
+                    if (chunk.IsModified)
                     {
-                        var chunk = kvp.Value;
+                        var data = ((Chunk)chunk).ToNbt();
-                        if (chunk.IsModified)
+                        byte[] raw = data.SaveToBuffer(NbtCompression.ZLib);
-                        {
-                            var data = ((Chunk)chunk).ToNbt();
-                            byte[] raw = data.SaveToBuffer(NbtCompression.ZLib);
 
-                            var header = GetChunkFromTable(kvp.Key);
+                        var header = GetChunkFromTable(kvp.Key);
-                            if (header == null || header.Item2 > raw.Length)
+                        if (header == null || header.Item2 > raw.Length)
-                                header = AllocateNewChunks(kvp.Key, raw.Length);
+                            header = AllocateNewChunks(kvp.Key, raw.Length);
 
-                            regionFile.Seek(header.Item1, SeekOrigin.Begin);
+                        regionFile.Seek(header.Item1, SeekOrigin.Begin);
-                            new MinecraftStream(regionFile).WriteInt32(raw.Length);
+                        new MinecraftStream(regionFile).WriteInt32(raw.Length);
-                            regionFile.WriteByte(2); // Compressed with zlib
+                        regionFile.WriteByte(2); // Compressed with zlib
-                            regionFile.Write(raw, 0, raw.Length);
+                        regionFile.Write(raw, 0, raw.Length);
 
-                            chunk.IsModified = false;
+                        chunk.IsModified = false;
-                        }
-                        if ((DateTime.UtcNow - chunk.LastAccessed).TotalMinutes > 5)
-                            toRemove.Add(kvp.Key);
-                    }
-                    regionFile.Flush();
-                    // Unload idle chunks
-                    foreach (var chunk in toRemove)
-                    {
-                        var c = Chunks[chunk];
-                        Chunks.Remove(chunk);
-                        c.Dispose();
                     }
+                    if ((DateTime.UtcNow - chunk.LastAccessed).TotalMinutes > 5)
+                        toRemove.Add(kvp.Key);
+                }
+                regionFile.Flush();
+                // Unload idle chunks
+                foreach (var chunk in toRemove)
+                {
+                    var c = Chunks[chunk];
+                    Chunks.Remove(chunk);
+                    c.Dispose();
                 }
             }
         }

TrueCraft/Commands/DebugCommands.cs

@@ -210,9 +210,13 @@ namespace TrueCraft.Commands
                 if (path == null)
                 {
                     client.SendMessage(ChatColor.Red + "It is impossible for this entity to reach you.");
-                    return;
                 }
-                entity.CurrentPath = path;
+                else
+                {
+                    client.SendMessage(string.Format(ChatColor.Blue
+                        + "Executing path with {0} waypoints", path.Waypoints.Count()));
+                    entity.CurrentPath = path;
+                }
             });
         }
 
@@ -222,6 +226,64 @@ namespace TrueCraft.Commands
         }
     }
 
+    public class EntityInfoCommand : Command
+    {
+        public override string Name
+        {
+            get { return "entity"; }
+        }
+
+        public override string Description
+        {
+            get { return "Provides information about an entity ID."; }
+        }
+
+        public override string[] Aliases
+        {
+            get { return new string[0]; }
+        }
+
+        public override void Handle(IRemoteClient client, string alias, string[] arguments)
+        {
+            if (arguments.Length != 1)
+            {
+                Help(client, alias, arguments);
+                return;
+            }
+
+            int id;
+            if (!int.TryParse(arguments[0], out id))
+            {
+                Help(client, alias, arguments);
+                return;
+            }
+
+            var manager = client.Server.GetEntityManagerForWorld(client.World);
+            var entity = manager.GetEntityByID(id);
+            if (entity == null)
+            {
+                client.SendMessage(ChatColor.Red + "An entity with that ID does not exist in this world.");
+                return;
+            }
+            client.SendMessage(string.Format(
+                "{0} {1}", entity.GetType().Name, entity.Position));
+            if (entity is MobEntity)
+            {
+                var mob = entity as MobEntity;
+                client.SendMessage(string.Format(
+                    "{0}/{1} HP, {2} State, moving to to {3}",
+                    mob.Health, mob.MaxHealth,
+                    mob.CurrentState?.GetType().Name ?? "null",
+                    mob.CurrentPath?.Waypoints.Last().ToString() ?? "null"));
+            }
+        }
+
+        public override void Help(IRemoteClient client, string alias, string[] arguments)
+        {
+            client.SendMessage("/entity [id]: Shows information about this entity.");
+        }
+    }
+
     public class DestroyCommand : Command
     {
         public override string Name

TrueCraft/MultiplayerServer.cs

@@ -75,6 +75,7 @@ namespace TrueCraft
         private TcpListener Listener;
         private readonly PacketHandler[] PacketHandlers;
         private IList<ILogProvider> LogProviders;
+        private Stopwatch Time;
         private ConcurrentBag<Tuple<IWorld, IChunk>> ChunksToSchedule;
         internal object ClientLock = new object();
         
@@ -109,6 +110,7 @@ namespace TrueCraft
             QueryProtocol = new TrueCraft.QueryProtocol(this);
             WorldLighters = new List<WorldLighting>();
             ChunksToSchedule = new ConcurrentBag<Tuple<IWorld, IChunk>>();
+            Time = new Stopwatch();
 
             AccessConfiguration = Configuration.LoadConfiguration<AccessConfiguration>("access.yaml");
 
@@ -124,6 +126,8 @@ namespace TrueCraft
         public void Start(IPEndPoint endPoint)
         {
             ShuttingDown = false;
+            Time.Reset();
+            Time.Start();
             Listener = new TcpListener(endPoint);
             Listener.Start();
             EndPoint = (IPEndPoint)Listener.LocalEndpoint;
@@ -135,7 +139,7 @@ namespace TrueCraft
                 AcceptClient(this, args);
             
             Log(LogCategory.Notice, "Running TrueCraft server on {0}", EndPoint);
-            EnvironmentWorker.Change(MillisecondsPerTick, 0);
+            EnvironmentWorker.Change(MillisecondsPerTick, Timeout.Infinite);
             if(Program.ServerConfiguration.Query)
                 QueryProtocol.Start();
         }
@@ -152,6 +156,16 @@ namespace TrueCraft
                 DisconnectClient(c);
         }
 
+        public void Pause()
+        {
+            EnvironmentWorker.Change(Timeout.Infinite, Timeout.Infinite);
+        }
+        
+        public void Resume()
+        {
+            EnvironmentWorker.Change(0, Timeout.Infinite);
+        }
+
         public void AddWorld(IWorld world)
         {
             Worlds.Add(world);
@@ -216,7 +230,7 @@ namespace TrueCraft
             if (Program.ServerConfiguration.EnableLighting)
             {
                 var lighter = new WorldLighting(sender as IWorld, BlockRepository);
-                lighter.InitialLighting(e.Chunk);
+                lighter.InitialLighting(e.Chunk, false);
             }
             else
             {
@@ -385,6 +399,8 @@ namespace TrueCraft
             if (ShuttingDown)
                 return;
 
+            long start = Time.ElapsedMilliseconds;
+            long limit = Time.ElapsedMilliseconds + MillisecondsPerTick;
             Profiler.Start("environment");
 
             Scheduler.Update();
@@ -396,15 +412,20 @@ namespace TrueCraft
             }
             Profiler.Done();
 
-            Profiler.Start("environment.lighting");
+            if (Program.ServerConfiguration.EnableLighting)
-            foreach (var lighter in WorldLighters)
             {
-                int attempts = 500;
+                Profiler.Start("environment.lighting");
-                while (attempts-- > 0 && lighter.TryLightNext())
+                foreach (var lighter in WorldLighters)
                 {
+                    while (Time.ElapsedMilliseconds < limit && lighter.TryLightNext())
+                    {
+                        // This space intentionally left blank
+                    }
+                    if (Time.ElapsedMilliseconds >= limit)
+                        Log(LogCategory.Warning, "Lighting queue is backed up");
                 }
+                Profiler.Done();
             }
-            Profiler.Done();
 
             Profiler.Start("environment.chunks");
             Tuple<IWorld, IChunk> t;
@@ -413,8 +434,12 @@ namespace TrueCraft
             Profiler.Done();
 
             Profiler.Done(MillisecondsPerTick);
-
+            long end = Time.ElapsedMilliseconds;
-            EnvironmentWorker.Change(MillisecondsPerTick, 0);
+            long next = MillisecondsPerTick - (end - start);
+            if (next < 0)
+                next = 0;
+            
+            EnvironmentWorker.Change(next, Timeout.Infinite);
         }
 
         public bool PlayerIsWhitelisted(string client)

TrueCraft/Program.cs

@@ -98,6 +98,11 @@ namespace TrueCraft
                     if (progress % 10 == 0)
                         Server.Log(LogCategory.Notice, "{0}% complete", progress + 10);
                 }
+                Server.Log(LogCategory.Notice, "Lighting the world (this will take a moment)...");
+                foreach (var lighter in Server.WorldLighters)
+                {
+                    while (lighter.TryLightNext()) ;
+                }
             }
             world.Save();
             CommandManager = new CommandManager();
@@ -107,10 +112,14 @@ namespace TrueCraft
             while (true)
             {
                 Thread.Sleep(1000 * ServerConfiguration.WorldSaveInterval);
+                Server.Pause();
+                Server.Log(LogCategory.Notice, "Saving world...");
                 foreach (var w in Server.Worlds)
                 {
                     w.Save();
                 }
+                Server.Log(LogCategory.Notice, "Done.");
+                Server.Resume();
             }
         }