Merge pull request #145 from valeriob/bugfix_windows_auto_resize_works_only_once

Fixes windows exception when AutoResizeWindows = true : NativeLibrary…

Author: CoreyKaylor

src/LightningDB.Tests/EnvironmentTests.cs

@@ -153,7 +153,16 @@ public void CreateEnvironmentWithAutoResize()
             {
                 using (var env = new LightningEnvironment(_path, new EnvironmentConfiguration
                 {
-                    MapSize = 10 * 1024 * 1024,
+                    MapSize = 1048576,
+                    AutoResizeWindows = true,
+                }))
+                {
+                    env.Open();
+                }
+
+                using (var env = new LightningEnvironment(_path, new EnvironmentConfiguration
+                {
+                    MapSize = 1048576,
                     AutoResizeWindows = true,
                 }))
                 {

src/LightningDB/Native/Lmdb.cs

@@ -164,11 +164,24 @@ internal static extern MDBResultCode mdb_env_open(IntPtr env, string path, Envir
 
 #if NETCOREAPP3_1 || NET5_0
 
+        static bool _shouldSetDllImportResolver = true;
+        static object _syncRoot = new object();
+
         public static void LoadWindowsAutoResizeLibrary()
         {
-            NativeLibrary.SetDllImportResolver(System.Reflection.Assembly.GetExecutingAssembly(), DllImportResolver);
+            if (_shouldSetDllImportResolver)
+            {
+                lock (_syncRoot)
+                {
+                    if (_shouldSetDllImportResolver)
+                    {
+                        NativeLibrary.SetDllImportResolver(System.Reflection.Assembly.GetExecutingAssembly(), DllImportResolver);
+                        _shouldSetDllImportResolver = false;
+                    }
+                }
+            }
         }
-        
+
         private static IntPtr DllImportResolver(string libraryName, System.Reflection.Assembly assembly, DllImportSearchPath? searchPath)
         {
             if (libraryName == MDB_DLL_NAME)