Fix memory leaks in C extension; add test functions

Author: kesmit13

accel.c

@@ -363,18 +363,15 @@ static PyObject *apply_transformer(PyObject *transformer, PyObject *value) {
     }
 
     if (transformer == NULL || transformer == Py_None) {
-        // Increment refcount fo Py_None since we are returning it
-        if (value == Py_None) {
-            Py_INCREF(value);
-        }
+        // No transformation needed, return value as-is
+        // We steal the reference from the caller
         return value;
     }
 
     PyObject *out = PyObject_CallFunction(transformer, "O", value);
-    // Don't decref Py_None since we assume it was passed in literally and not from a new reference
-    if (value != NULL && value != Py_None) {
-        Py_DECREF(value);
-    }
+    // Always decref value since we're stealing the reference from the caller
+    // This includes Py_None when it's passed as a new reference (e.g., from PyIter_Next)
+    Py_DECREF(value);
 
     return out;
 }
@@ -4306,7 +4303,10 @@ static PyObject *load_rowdat_1(PyObject *self, PyObject *args, PyObject *kwargs)
         if (!py_row) goto error;
 
         row_id = *(int64_t*)data; data += 8;
-        CHECKRC(PyList_Append(py_out_row_ids, PyLong_FromLongLong(row_id)));
+        PyObject *py_row_id = PyLong_FromLongLong(row_id);
+        if (!py_row_id) goto error;
+        CHECKRC(PyList_Append(py_out_row_ids, py_row_id));
+        Py_DECREF(py_row_id);
 
         for (unsigned long long i = 0; i < colspec_l; i++) {
             is_null = data[0] == '\x01'; data += 1;

singlestoredb/tests/ext_funcs/__init__.py

@@ -32,6 +32,90 @@
 from singlestoredb.functions.typing import pyarrow as pat
 
 
+@udf
+def add(x: int, y: int) -> int:
+    """
+    Add two integers.
+
+    Parameters
+    ----------
+    x : int
+        First integer.
+    y : int
+        Second integer.
+
+    Returns
+    -------
+    int
+        Sum of x and y.
+
+    """
+    return x + y
+
+
+@udf
+def add_vec(x: npt.Int64Array, y: npt.Int64Array) -> npt.Int64Array:
+    """
+    Add two numpy arrays of int64.
+
+    Parameters
+    ----------
+    x : numpy.ndarray
+        First array.
+    y : numpy.ndarray
+        Second array.
+
+    Returns
+    -------
+    numpy.ndarray
+        Elementwise sum of x and y.
+
+    """
+    return x + y
+
+
+@udf
+async def async_add(x: int, y: int) -> int:
+    """
+    Asynchronously add two integers.
+
+    Parameters
+    ----------
+    x : int
+        First integer.
+    y : int
+        Second integer.
+
+    Returns
+    -------
+    int
+        Sum of x and y.
+
+    """
+    return x + y
+
+
+@udf
+async def async_add_vec_vec(x: npt.Int64Array, y: npt.Int64Array) -> npt.Int64Array:
+    """
+    Asynchronously add two numpy arrays of int64.
+
+    Parameters
+    ----------
+    x : numpy.ndarray
+        First array.
+    y : numpy.ndarray
+        Second array.
+
+    Returns
+    -------
+    numpy.ndarray
+        Elementwise sum of x and y.
+
+    """
+    return x + y
+
+
 @udf
 def doc_test(x: int, y: float) -> int:
     """