Fix pre-existing static constructor race

NinoFloris · NinoFloris · commit 9e3461f387de · 2026-04-08T00:24:08.000+02:00
diff --git a/src/Npgsql/TypeMapping/GlobalTypeMapper.cs b/src/Npgsql/TypeMapping/GlobalTypeMapper.cs
@@ -48,17 +48,31 @@ internal IEnumerable<PgTypeInfoResolverFactory> GetPluginResolverFactories()
 
     internal void AddGlobalTypeMappingResolvers(PgTypeInfoResolverFactory[] factories, Func<PgTypeInfoResolverChainBuilder>? builderFactory = null, bool overwrite = false)
     {
-        // Good enough logic to prevent SlimBuilder overriding the normal Builder.
-        if (overwrite || factories.Length > _typeMappingResolvers.Length)
+        _lock.EnterWriteLock();
+        try
         {
-            _builderFactory = builderFactory;
-            _typeMappingResolvers = factories;
-            ResetTypeMappingCache();
+            // Prevent SlimBuilder from overriding the normal Builder.
+            if (overwrite || factories.Length > _typeMappingResolvers.Length)
+            {
+                _builderFactory = builderFactory;
+                _typeMappingResolvers = factories;
+                ResetTypeMappingCache();
+            }
+        }
+        finally
+        {
+            _lock.ExitWriteLock();
         }
     }
 
-    void ResetTypeMappingCache() => _typeMappingOptions = null;
+    void ResetTypeMappingCache()
+    {
+        Interlocked.Increment(ref _typeMappingVersion);
+        _typeMappingOptions = null;
+    }
 
+    int _typeMappingVersion;
+    int _typeMappingCachedVersion = -1;
     PgSerializerOptions? _typeMappingOptions;
     Func<PgTypeInfoResolverChainBuilder>? _builderFactory;
     JsonSerializerOptions? _jsonSerializerOptions;
@@ -67,19 +81,25 @@ PgSerializerOptions TypeMappingOptions
     {
         get
         {
-            if (_typeMappingOptions is not null)
-                return _typeMappingOptions;
+            var version = Volatile.Read(ref _typeMappingVersion);
+            if (_typeMappingOptions is { } options && _typeMappingCachedVersion == version)
+                return options;
 
-            _lock.EnterReadLock();
+            _lock.EnterWriteLock();
             try
             {
+                version = _typeMappingVersion;
+                if (_typeMappingOptions is not null && _typeMappingCachedVersion == version)
+                    return _typeMappingOptions;
+
                 var builder = _builderFactory?.Invoke() ?? new();
                 builder.AppendResolverFactory(_userTypeMapper);
                 foreach (var factory in _pluginResolverFactories)
                     builder.AppendResolverFactory(factory);
                 foreach (var factory in _typeMappingResolvers)
                     builder.AppendResolverFactory(factory);
                 var chain = builder.Build();
+                _typeMappingCachedVersion = version;
                 return _typeMappingOptions = new(PostgresMinimalDatabaseInfo.DefaultTypeCatalog, chain)
                 {
                     // This means we don't ever have a missing oid for a datatypename as our canonical format is datatypenames.
@@ -90,7 +110,7 @@ PgSerializerOptions TypeMappingOptions
             }
             finally
             {
-                _lock.ExitReadLock();
+                _lock.ExitWriteLock();
             }
         }
     }
