tidy tests, add pinner, other nits

errors.go

@@ -98,12 +98,10 @@ var (
 	errInvalidDecimalWidth = fmt.Errorf("the DECIMAL with must be between 1 and %d", MAX_DECIMAL_WIDTH)
 	errInvalidDecimalScale = errors.New("the DECIMAL scale must be less than or equal to the width")
 
-	errScalarUDFCreate     = errors.New("could not create scalar UDF")
-	errScalarUDFNoName     = fmt.Errorf("%w: missing name", errScalarUDFCreate)
-	errScalarUDFIsNil      = fmt.Errorf("%w: function is nil", errScalarUDFCreate)
-	errScalarUDFNoExecutor = fmt.Errorf("%w: executor is nil", errScalarUDFCreate)
-	//errScalarUDFNilInputTypes   = fmt.Errorf("%w: input types are nil", errScalarUDFCreate)
-	//errScalarUDFEmptyInputTypes = fmt.Errorf("%w: empty input types", errScalarUDFCreate)
+	errScalarUDFCreate          = errors.New("could not create scalar UDF")
+	errScalarUDFNoName          = fmt.Errorf("%w: missing name", errScalarUDFCreate)
+	errScalarUDFIsNil           = fmt.Errorf("%w: function is nil", errScalarUDFCreate)
+	errScalarUDFNoExecutor      = fmt.Errorf("%w: executor is nil", errScalarUDFCreate)
 	errScalarUDFInputTypeIsNil  = fmt.Errorf("%w: input type is nil", errScalarUDFCreate)
 	errScalarUDFResultTypeIsNil = fmt.Errorf("%w: result type is nil", errScalarUDFCreate)
 	errScalarUDFResultTypeIsANY = fmt.Errorf("%w: result type is ANY, which is not supported", errScalarUDFCreate)

pinner.go

@@ -0,0 +1,16 @@
+package duckdb
+
+import "runtime"
+
+type pinnedValue[T any] struct {
+	pinner *runtime.Pinner
+	value  T
+}
+
+type unpinner interface {
+	unpin()
+}
+
+func (v pinnedValue[T]) unpin() {
+	v.pinner.Unpin()
+}

scalar_udf.go

@@ -15,6 +15,7 @@ import "C"
 import (
 	"database/sql"
 	"database/sql/driver"
+	"runtime"
 	"runtime/cgo"
 	"unsafe"
 )
@@ -134,9 +135,9 @@ func setFuncError(function_info C.duckdb_function_info, msg string) {
 func scalar_udf_callback(function_info C.duckdb_function_info, input C.duckdb_data_chunk, output C.duckdb_vector) {
 	extraInfo := C.duckdb_scalar_function_get_extra_info(function_info)
 
-	// extraInfo is a void* pointer to our ScalarFunc.
+	// extraInfo is a void* pointer to our pinned ScalarFunc f.
 	h := *(*cgo.Handle)(unsafe.Pointer(extraInfo))
-	function := h.Value().(ScalarFunc)
+	function := h.Value().(pinnedValue[ScalarFunc]).value
 
 	// Initialize the input chunk.
 	var inputChunk DataChunk
@@ -203,6 +204,7 @@ func scalar_udf_callback(function_info C.duckdb_function_info, input C.duckdb_da
 //export scalar_udf_delete_callback
 func scalar_udf_delete_callback(extraInfo unsafe.Pointer) {
 	h := (*cgo.Handle)(extraInfo)
+	h.Value().(unpinner).unpin()
 	h.Delete()
 }
 
@@ -282,8 +284,15 @@ func createScalarFunc(name string, f ScalarFunc) (C.duckdb_scalar_function, erro
 	// Set the function callback.
 	C.duckdb_scalar_function_set_function(function, C.scalar_udf_callback_t(C.scalar_udf_callback))
 
+	// Pin the ScalarFunc f.
+	value := pinnedValue[ScalarFunc]{
+		pinner: &runtime.Pinner{},
+		value:  f,
+	}
+	h := cgo.NewHandle(value)
+	value.pinner.Pin(&h)
+
 	// Set data available during execution.
-	h := cgo.NewHandle(f)
 	C.duckdb_scalar_function_set_extra_info(
 		function,
 		unsafe.Pointer(&h),