Rename read to exec, add better tests, and fix memory leak

.gitignore

@@ -6,3 +6,4 @@ pystarlark.egg-info/
 starlark.o
 starlark.so
 .eggs
+pystarlark/*.so

CHANGELOG.md

@@ -1,3 +1,9 @@
+0.0.2 / unreleased
+==================
+
+* Rename `Starlark.read` to `Starlark.exec`
+* Fix memory leak from not freeing C.CString
+
 0.0.1 / 2020-11-22
 ==================
 

Makefile

@@ -1,9 +1,14 @@
-build:
+so:
 	go build -buildmode=c-shared -o starlark.so .
+
+ffi:
 	python build_ffi.py
 
 clean:
-	rm starlark.c
-	rm starlark.h
-	rm starlark.o
-	rm starlark.so
+	rm -rf starlark.c
+	rm -rf starlark.h
+	rm -rf starlark.o
+	rm -rf starlark.so
+
+test:
+	python -m pytest

README.md

@@ -23,7 +23,7 @@ def fibonacci(n=10):
        res[i] = res[i-2] + res[i-1]
    return res
 """
-s.read(fibonacci)
+s.exec(fibonacci)
 s.eval("fibonacci(5)")  # [0, 1, 1, 2, 3]
 ```
 

build_ffi.py

@@ -13,13 +13,15 @@
 
 ffibuilder.cdef(
     """
-    extern long unsigned int NewThread();
+extern long unsigned int NewThread();
 
-    extern void DestroyThread(long unsigned int p0);
+extern void DestroyThread(long unsigned int p0);
 
-    extern char* Eval(long unsigned int p0, char* p1);
+extern char* Eval(long unsigned int p0, char* p1);
 
-    extern void ExecFile(long unsigned int p0, char* p1);
+extern void ExecFile(long unsigned int p0, char* p1);
+
+extern void FreeCString(char* p0);
     """
 )
 

development.txt

@@ -1,2 +1,7 @@
 cffi==1.14.3
 setuptools-golang==2.3.0
+wheel==0.36.1
+black==20.8b1
+isort==5.6.4
+twine==3.1.1
+pytest==6.1.2

pystarlark/__init__.py

@@ -8,7 +8,7 @@ class Starlark:
     def __init__(self):
         self._id = lib.NewThread()
 
-    def read(self, code):
+    def exec(self, code):
         if isinstance(code, str):
             code = code.encode()
         lib.ExecFile(self._id, code)
@@ -17,7 +17,9 @@ def eval(self, statement, _raw=False):
         if isinstance(statement, str):
             statement = statement.encode()
 
-        response = ffi.string(lib.Eval(self._id, statement))
+        output = lib.Eval(self._id, statement)
+        response = ffi.string(output)
+        lib.FreeCString(output)
         if _raw:
             return response
         value = json.loads(response)["value"]

starlark.c

@@ -575,19 +575,22 @@ static void (*_cffi_call_python_org)(struct _cffi_externpy_s *, char *);
 static void *_cffi_types[] = {
 /*  0 */ _CFFI_OP(_CFFI_OP_FUNCTION, 2), // char *()(unsigned long, char *)
 /*  1 */ _CFFI_OP(_CFFI_OP_PRIMITIVE, 10), // unsigned long
-/*  2 */ _CFFI_OP(_CFFI_OP_POINTER, 13), // char *
+/*  2 */ _CFFI_OP(_CFFI_OP_POINTER, 16), // char *
 /*  3 */ _CFFI_OP(_CFFI_OP_FUNCTION_END, 0),
 /*  4 */ _CFFI_OP(_CFFI_OP_FUNCTION, 1), // unsigned long()(void)
 /*  5 */ _CFFI_OP(_CFFI_OP_FUNCTION_END, 0),
-/*  6 */ _CFFI_OP(_CFFI_OP_FUNCTION, 14), // void()(unsigned long)
-/*  7 */ _CFFI_OP(_CFFI_OP_PRIMITIVE, 10),
+/*  6 */ _CFFI_OP(_CFFI_OP_FUNCTION, 17), // void()(char *)
+/*  7 */ _CFFI_OP(_CFFI_OP_NOOP, 2),
 /*  8 */ _CFFI_OP(_CFFI_OP_FUNCTION_END, 0),
-/*  9 */ _CFFI_OP(_CFFI_OP_FUNCTION, 14), // void()(unsigned long, char *)
+/*  9 */ _CFFI_OP(_CFFI_OP_FUNCTION, 17), // void()(unsigned long)
 /* 10 */ _CFFI_OP(_CFFI_OP_PRIMITIVE, 10),
-/* 11 */ _CFFI_OP(_CFFI_OP_NOOP, 2),
-/* 12 */ _CFFI_OP(_CFFI_OP_FUNCTION_END, 0),
-/* 13 */ _CFFI_OP(_CFFI_OP_PRIMITIVE, 2), // char
-/* 14 */ _CFFI_OP(_CFFI_OP_PRIMITIVE, 0), // void
+/* 11 */ _CFFI_OP(_CFFI_OP_FUNCTION_END, 0),
+/* 12 */ _CFFI_OP(_CFFI_OP_FUNCTION, 17), // void()(unsigned long, char *)
+/* 13 */ _CFFI_OP(_CFFI_OP_PRIMITIVE, 10),
+/* 14 */ _CFFI_OP(_CFFI_OP_NOOP, 2),
+/* 15 */ _CFFI_OP(_CFFI_OP_FUNCTION_END, 0),
+/* 16 */ _CFFI_OP(_CFFI_OP_PRIMITIVE, 2), // char
+/* 17 */ _CFFI_OP(_CFFI_OP_PRIMITIVE, 0), // void
 };
 
 static void _cffi_d_DestroyThread(unsigned long x0)
@@ -712,6 +715,42 @@ _cffi_f_ExecFile(PyObject *self, PyObject *args)
 #  define _cffi_f_ExecFile _cffi_d_ExecFile
 #endif
 
+static void _cffi_d_FreeCString(char * x0)
+{
+  FreeCString(x0);
+}
+#ifndef PYPY_VERSION
+static PyObject *
+_cffi_f_FreeCString(PyObject *self, PyObject *arg0)
+{
+  char * x0;
+  Py_ssize_t datasize;
+  struct _cffi_freeme_s *large_args_free = NULL;
+
+  datasize = _cffi_prepare_pointer_call_argument(
+      _cffi_type(2), arg0, (char **)&x0);
+  if (datasize != 0) {
+    x0 = ((size_t)datasize) <= 640 ? (char *)alloca((size_t)datasize) : NULL;
+    if (_cffi_convert_array_argument(_cffi_type(2), arg0, (char **)&x0,
+            datasize, &large_args_free) < 0)
+      return NULL;
+  }
+
+  Py_BEGIN_ALLOW_THREADS
+  _cffi_restore_errno();
+  { FreeCString(x0); }
+  _cffi_save_errno();
+  Py_END_ALLOW_THREADS
+
+  (void)self; /* unused */
+  if (large_args_free != NULL) _cffi_free_array_arguments(large_args_free);
+  Py_INCREF(Py_None);
+  return Py_None;
+}
+#else
+#  define _cffi_f_FreeCString _cffi_d_FreeCString
+#endif
+
 static unsigned long _cffi_d_NewThread(void)
 {
   return NewThread();
@@ -739,9 +778,10 @@ _cffi_f_NewThread(PyObject *self, PyObject *noarg)
 #endif
 
 static const struct _cffi_global_s _cffi_globals[] = {
-  { "DestroyThread", (void *)_cffi_f_DestroyThread, _CFFI_OP(_CFFI_OP_CPYTHON_BLTN_O, 6), (void *)_cffi_d_DestroyThread },
+  { "DestroyThread", (void *)_cffi_f_DestroyThread, _CFFI_OP(_CFFI_OP_CPYTHON_BLTN_O, 9), (void *)_cffi_d_DestroyThread },
   { "Eval", (void *)_cffi_f_Eval, _CFFI_OP(_CFFI_OP_CPYTHON_BLTN_V, 0), (void *)_cffi_d_Eval },
-  { "ExecFile", (void *)_cffi_f_ExecFile, _CFFI_OP(_CFFI_OP_CPYTHON_BLTN_V, 9), (void *)_cffi_d_ExecFile },
+  { "ExecFile", (void *)_cffi_f_ExecFile, _CFFI_OP(_CFFI_OP_CPYTHON_BLTN_V, 12), (void *)_cffi_d_ExecFile },
+  { "FreeCString", (void *)_cffi_f_FreeCString, _CFFI_OP(_CFFI_OP_CPYTHON_BLTN_O, 6), (void *)_cffi_d_FreeCString },
   { "NewThread", (void *)_cffi_f_NewThread, _CFFI_OP(_CFFI_OP_CPYTHON_BLTN_N, 4), (void *)_cffi_d_NewThread },
 };
 
@@ -752,12 +792,12 @@ static const struct _cffi_type_context_s _cffi_type_context = {
   NULL,  /* no struct_unions */
   NULL,  /* no enums */
   NULL,  /* no typenames */
-  4,  /* num_globals */
+  5,  /* num_globals */
   0,  /* num_struct_unions */
   0,  /* num_enums */
   0,  /* num_typenames */
   NULL,  /* no includes */
-  15,  /* num_types */
+  18,  /* num_types */
   0,  /* flags */
 };
 

starlark.go

@@ -1,24 +1,23 @@
 package main
 
+/*
+ #include <stdlib.h>
+*/
+import "C"
 import (
-	"C"
 	"encoding/json"
 	"fmt"
-	"go.starlark.net/starlark"
 	"math/rand"
-	"time"
+	"unsafe"
+
+	"go.starlark.net/starlark"
 )
 
 var THREADS = map[uint64]*starlark.Thread{}
 var GLOBALS = map[uint64]starlark.StringDict{}
-var RAND = false
 
 //export NewThread
 func NewThread() C.ulong {
-	if RAND == false {
-		rand.Seed(time.Now().UnixNano())
-		RAND = true
-	}
 	threadId := rand.Uint64()
 	thread := &starlark.Thread{}
 	THREADS[threadId] = thread
@@ -74,6 +73,11 @@ func ExecFile(threadId C.ulong, data *C.char) {
 	return
 }
 
+//export FreeCString
+func FreeCString(s *C.char) {
+	C.free(unsafe.Pointer(s))
+}
+
 func main() {
 	const data = `
 def fibonacci(n=10):

starlark.h

@@ -19,6 +19,11 @@ typedef struct { const char *p; ptrdiff_t n; } _GoString_;
 /* Start of preamble from import "C" comments.  */
 
 
+#line 3 "starlark.go"
+
+ #include <stdlib.h>
+
+#line 1 "cgo-generated-wrapper"
 
 
 /* End of preamble from import "C" comments.  */
@@ -77,6 +82,8 @@ extern char* Eval(long unsigned int p0, char* p1);
 
 extern void ExecFile(long unsigned int p0, char* p1);
 
+extern void FreeCString(char* p0);
+
 #ifdef __cplusplus
 }
 #endif

tests/test_fibonacci.py

@@ -0,0 +1,15 @@
+from pystarlark import Starlark
+
+
+def test_fibonacci():
+    s = Starlark()
+    fibonacci = """
+def fibonacci(n=10):
+    res = list(range(n))
+    for i in res[2:]:
+        res[i] = res[i-2] + res[i-1]
+    return res
+"""
+    s.exec(fibonacci)
+    assert s.eval("fibonacci(5)") == [0, 1, 1, 2, 3]
+    assert s.eval("fibonacci(10)") == [0, 1, 1, 2, 3, 5, 8, 13, 21, 34]