From ce1cd1597834abd11b0c4381f5d5ffde5cc5b155 Mon Sep 17 00:00:00 2001
From: Matt Nadareski <mnadareski@outlook.com>
Date: Tue, 11 Aug 2026 22:03:50 -0400
Subject: [PATCH] Fix locking issues with item dictionary implementation

---
 .../ItemDictionary.cs                         | 62 +++++++++++++------
 1 file changed, 43 insertions(+), 19 deletions(-)

diff --git a/SabreTools.Metadata.DatFiles/ItemDictionary.cs b/SabreTools.Metadata.DatFiles/ItemDictionary.cs
index 29973ee0..f2f64b40 100644
--- a/SabreTools.Metadata.DatFiles/ItemDictionary.cs
+++ b/SabreTools.Metadata.DatFiles/ItemDictionary.cs
@@ -40,6 +40,15 @@ namespace SabreTools.Metadata.DatFiles
         private readonly Dictionary<string, List<DatItem>?> _items = [];
 #endif
 
+        /// <summary>
+        /// Internal dictionary for the class
+        /// </summary>
+#if NET40_OR_GREATER || NETCOREAPP || NETSTANDARD2_0_OR_GREATER
+        private readonly ConcurrentDictionary<string, object> _itemsLocks = [];
+#else
+        private readonly Dictionary<string, object> _itemsLocks = [];
+#endif
+
         /// <summary>
         /// Logging object
         /// </summary>
@@ -191,7 +200,14 @@ namespace SabreTools.Metadata.DatFiles
             // If only adding statistics, we add an empty key for games and then just item stats
             if (statsOnly)
             {
-                EnsureBucketingKey(key);
+                // Add an empty key
+#if NET40_OR_GREATER || NETCOREAPP || NETSTANDARD2_0_OR_GREATER
+                _items.GetOrAdd(key, []);
+#else
+                if (!_items.ContainsKey(key))
+                    _items[key] = [];
+#endif
+
                 DatStatistics.AddItemStatistics(item);
             }
             else
@@ -294,7 +310,16 @@ namespace SabreTools.Metadata.DatFiles
         public bool RemoveItem(string key, DatItem value, int index)
         {
             // Explicit lock for some weird corner cases
-            lock (key)
+#if NET40_OR_GREATER || NETCOREAPP || NETSTANDARD2_0_OR_GREATER
+            object lockObj = _itemsLocks.GetOrAdd(key, _ => new object());
+#else
+            if (!_itemsLocks.ContainsKey(key))
+                _itemsLocks[key] = new object();
+
+            object lockObj = _itemsLocks[key];
+#endif
+
+            lock (lockObj)
             {
                 // If the key doesn't exist, return
 #if NET40_OR_GREATER || NETCOREAPP || NETSTANDARD2_0_OR_GREATER
@@ -338,10 +363,24 @@ namespace SabreTools.Metadata.DatFiles
         internal void AddItem(string key, DatItem value)
         {
             // Explicit lock for some weird corner cases
-            lock (key)
+#if NET40_OR_GREATER || NETCOREAPP || NETSTANDARD2_0_OR_GREATER
+            object lockObj = _itemsLocks.GetOrAdd(key, _ => new object());
+#else
+            if (!_itemsLocks.ContainsKey(key))
+                _itemsLocks[key] = new object();
+
+            object lockObj = _itemsLocks[key];
+#endif
+
+            lock (lockObj)
             {
                 // Ensure the key exists
-                EnsureBucketingKey(key);
+#if NET40_OR_GREATER || NETCOREAPP || NETSTANDARD2_0_OR_GREATER
+                _items.GetOrAdd(key, []);
+#else
+                if (!_items.ContainsKey(key))
+                    _items[key] = [];
+#endif
 
                 // If item is null, don't add it
                 if (value is null)
@@ -640,21 +679,6 @@ namespace SabreTools.Metadata.DatFiles
             return roms.FindIndex(datItem.Equals) > -1;
         }
 
-        /// <summary>
-        /// Ensure the key exists in the items dictionary
-        /// </summary>
-        /// <param name="key">Key to ensure</param>
-        private void EnsureBucketingKey(string key)
-        {
-            // If the key is missing from the dictionary, add it
-#if NET40_OR_GREATER || NETCOREAPP || NETSTANDARD2_0_OR_GREATER
-            _items.GetOrAdd(key, []);
-#else
-            if (!_items.ContainsKey(key))
-                _items[key] = [];
-#endif
-        }
-
         /// <summary>
         /// Get the highest-order Field value that represents the statistics
         /// </summary>