From 2b73e0c55373eeb3e2d40527b656511f0a15075e Mon Sep 17 00:00:00 2001
From: UnknownShadow200 <unknownshadow200@gmail.com>
Date: Fri, 21 Apr 2017 15:07:26 +1000
Subject: [PATCH] Ensure access is threadsafe

---
 MCGalaxy/Entity/Entity.cs                | 16 +++++------
 MCGalaxy/Entity/Structs.cs               | 35 +++++++++++++++++++++++-
 MCGalaxy/Player/Group/GroupProperties.cs |  5 ++--
 3 files changed, 44 insertions(+), 12 deletions(-)

diff --git a/MCGalaxy/Entity/Entity.cs b/MCGalaxy/Entity/Entity.cs
index 3b2cf7344..002e05643 100644
--- a/MCGalaxy/Entity/Entity.cs
+++ b/MCGalaxy/Entity/Entity.cs
@@ -16,21 +16,21 @@
     permissions and limitations under the Licenses.
  */
 using System;
+using System.Threading;
 
 namespace MCGalaxy {
     
     /// <summary> Represents a player or an NPC. </summary>
     public abstract class Entity {
         
-        // Raw orientation/position - NOT threadsafe
-        protected Orientation _rot;
-        protected Position _pos;
+        // Raw orientation/position - access must be threadsafe
+        int _rot;
+        long _pos;
         
         // Last sent orientation/position, for delta calculation
         protected internal Orientation lastRot;
         protected internal Position lastPos;
         internal bool supportsExtPositions;
-        // TODO: struct assignment needs to be THREADSAFE
         
         
         /// <summary> Model name of this entity. </summary>
@@ -45,14 +45,14 @@ namespace MCGalaxy {
         
         /// <summary> Gets or sets the orientation of this entity. </summary>
         public Orientation Rot {
-            get { return _rot; }
-            set { _rot = value; OnSetRot(); }
+        	get { return Orientation.Unpack(Thread.VolatileRead(ref _rot)); }
+        	set { Thread.VolatileWrite(ref _rot, value.Pack()); OnSetRot(); }
         }
         
         /// <summary> Gets or sets the position of this entity. </summary>
         public Position Pos {
-            get { return _pos; }
-            set { _pos = value; OnSetPos(); }
+            get { return Position.Unpack(Thread.VolatileRead(ref _pos)); }
+            set { Thread.VolatileWrite(ref _pos, value.Pack()); OnSetPos(); }
         }
         
         /// <summary> Sets only the yaw and pitch of the orientation of this entity. </summary>
diff --git a/MCGalaxy/Entity/Structs.cs b/MCGalaxy/Entity/Structs.cs
index b4a06177f..f1bd5f49f 100644
--- a/MCGalaxy/Entity/Structs.cs
+++ b/MCGalaxy/Entity/Structs.cs
@@ -18,7 +18,7 @@
 using System;
 
 namespace MCGalaxy {
-	
+    
     /// <summary> Represents the position of an entity in the world. </summary>
     public struct Position: IEquatable<Position> {
         
@@ -62,6 +62,27 @@ namespace MCGalaxy {
         public static bool operator == (Position a, Position b) { return a.Equals(b); }
         
         public static bool operator != (Position a, Position b) { return !a.Equals(b); }
+        
+        
+        const long mask = 0x1FFFFF;
+        internal long Pack() {
+            return (X & mask) | ((Y & mask) << 21) | ((Z & mask) << 42);
+        }
+        
+        internal static Position Unpack(long raw) {
+            Position pos;
+            pos.X = SignExtend(raw);
+            pos.Y = SignExtend(raw >> 21);
+            pos.Z = SignExtend(raw >> 42);
+            return pos;
+        }
+        
+        static int SignExtend(long parts) {
+            int value = (int)(parts & mask);
+            value <<= (32 - 21);
+            value >>= (32 - 21);
+            return value;
+        }
     }
     
     
@@ -92,5 +113,17 @@ namespace MCGalaxy {
         public static byte DegreesToPacked(int degrees) {
             return (byte)(degrees * 256 / 360);
         }
+        
+        
+        internal int Pack() {
+            return RotX | (RotY << 8) | (RotZ << 16) | HeadX;
+        }
+        
+        internal static Orientation Unpack(int raw) {
+            Orientation rot;
+            rot.RotX = (byte)raw; rot.RotY = (byte)(raw >> 8);
+            rot.RotZ = (byte)(raw >> 16); rot.HeadX = (byte)(raw >> 24);
+            return rot;
+        }
     }
 }
diff --git a/MCGalaxy/Player/Group/GroupProperties.cs b/MCGalaxy/Player/Group/GroupProperties.cs
index 67d828abe..e7f52522c 100644
--- a/MCGalaxy/Player/Group/GroupProperties.cs
+++ b/MCGalaxy/Player/Group/GroupProperties.cs
@@ -23,10 +23,9 @@ using System.IO;
 namespace MCGalaxy {
     public sealed class GroupProperties {
         
-        const string filename = "properties/ranks.properties";
         public static void InitAll() {
             Group grp = null;
-            PropertiesFile.Read(filename, ref grp, ParseProperty, '=', false);
+            PropertiesFile.Read(Paths.RankPropsFile, ref grp, ParseProperty, '=', false);
             if (grp != null) AddGroup(ref grp);
         }
         
@@ -115,7 +114,7 @@ namespace MCGalaxy {
         /// <summary> Save givenList group </summary>
         /// <param name="givenList">The list of groups to save</param>
         public static void SaveGroups(List<Group> givenList) {
-            using (StreamWriter w = new StreamWriter(filename)) {
+            using (StreamWriter w = new StreamWriter(Paths.RankPropsFile)) {
                 w.WriteLine("#Version 3");
                 w.WriteLine("#RankName = string");
                 w.WriteLine("#\tThe name of the rank, use capitalization.");