From 5a536e6123a3feb40b46e34562d081010873d90c Mon Sep 17 00:00:00 2001
From: Evan Hemsley <evan@moonside.games>
Date: Sun, 22 Mar 2020 13:53:23 -0700
Subject: [PATCH] optimize singular entity message read

---
 encompass-cs/Collections/MessageStore.cs      | 5 +++++
 encompass-cs/Collections/TypedMessageStore.cs | 9 +++++++--
 encompass-cs/MessageManager.cs                | 6 ++----
 3 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/encompass-cs/Collections/MessageStore.cs b/encompass-cs/Collections/MessageStore.cs
index 4d44657..632cfd3 100644
--- a/encompass-cs/Collections/MessageStore.cs
+++ b/encompass-cs/Collections/MessageStore.cs
@@ -53,6 +53,11 @@ namespace Encompass
             return Lookup<TMessage>().WithEntity(entityID);
         }
 
+        public ref readonly TMessage FirstWithEntity<TMessage>(int entityID) where TMessage : struct, IMessage
+        {
+            return ref Lookup<TMessage>().FirstWithEntity(entityID);
+        }
+
         public bool SomeWithEntity<TMessage>(int entityID) where TMessage : struct, IMessage, IHasEntity
         {
             return Lookup<TMessage>().SomeWithEntity(entityID);
diff --git a/encompass-cs/Collections/TypedMessageStore.cs b/encompass-cs/Collections/TypedMessageStore.cs
index b43f129..3e8d815 100644
--- a/encompass-cs/Collections/TypedMessageStore.cs
+++ b/encompass-cs/Collections/TypedMessageStore.cs
@@ -17,7 +17,7 @@ namespace Encompass
         private readonly TMessage[] _store = new TMessage[128];
         private readonly List<(TMessage, double)> _delayedStore = new List<(TMessage, double)>(128);
         private readonly List<(TMessage, double)> _delayedStoreIgnoringTimeDilation = new List<(TMessage, double)>(128);
-        private readonly Dictionary<int, HashSet<int>> _entityToIndices = new Dictionary<int, HashSet<int>>();
+        private readonly Dictionary<int, List<int>> _entityToIndices = new Dictionary<int, List<int>>();
 
         public override void ProcessDelayedMessages(double dilatedDelta, double realtimeDelta)
         {
@@ -63,7 +63,7 @@ namespace Encompass
             if (message is IHasEntity entityMessage)
             {
                 var entityID = entityMessage.Entity.ID;
-                if (!_entityToIndices.ContainsKey(entityID)) { _entityToIndices.Add(entityID, new HashSet<int>()); }
+                if (!_entityToIndices.ContainsKey(entityID)) { _entityToIndices.Add(entityID, new List<int>()); }
                 _entityToIndices[entityID].Add(index);
             }
         }
@@ -104,6 +104,11 @@ namespace Encompass
             }
         }
 
+        public ref readonly TMessage FirstWithEntity(int entityID)
+        {
+            return ref _store[_entityToIndices[entityID][0]];
+        }
+
         public bool SomeWithEntity(int entityID)
         {
             return _entityToIndices.ContainsKey(entityID) && _entityToIndices[entityID].Count > 0;
diff --git a/encompass-cs/MessageManager.cs b/encompass-cs/MessageManager.cs
index 0ee4dc2..1e7d704 100644
--- a/encompass-cs/MessageManager.cs
+++ b/encompass-cs/MessageManager.cs
@@ -58,11 +58,9 @@ namespace Encompass
             return _messageStore.WithEntity<TMessage>(entityID);
         }
 
-        internal TMessage WithEntitySingular<TMessage>(int entityID) where TMessage : struct, IMessage, IHasEntity
+        internal ref readonly TMessage WithEntitySingular<TMessage>(int entityID) where TMessage : struct, IMessage, IHasEntity
         {
-            var enumerator = _messageStore.WithEntity<TMessage>(entityID).GetEnumerator();
-            enumerator.MoveNext();
-            return enumerator.Current;
+            return ref _messageStore.FirstWithEntity<TMessage>(entityID);
         }
 
         internal bool SomeWithEntity<TMessage>(int entityID) where TMessage : struct, IMessage, IHasEntity