[Libguestfs] [libnbd PATCH] hack for testing python closure leaks: NOT FOR COMMIT

[Eric Blake]

Just posting this for posterity, on something I used to track down
memory leaks related to python closures.

---
 generator/Python.ml | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/generator/Python.ml b/generator/Python.ml
index 4a96cf6..2ff17dd 100644
--- a/generator/Python.ml
+++ b/generator/Python.ml
@@ -578,9 +578,27 @@ let generate_python_methods_c () =
   pr "  PyObject *buf;   /* Optional pointer to persistent buffer. */\n";
   pr "};\n";
   pr "\n";
+  pr "static size_t alloc_count;\n";
+  pr "void\n";
+  pr "dump_alloc_count (void)\n";
+  pr "{\n";
+  pr "  char *cmd;\n";
+  pr "  if (!alloc_count) return;\n";
+  pr "  asprintf (&cmd, \"{ echo ' *** alloc_count:%%zu'; cat /proc/%%d/cmdline; } > /dev/tty\",\n";
+  pr "            alloc_count, getpid ());\n";
+  pr "  system (cmd);\n";
+  pr "  free (cmd);\n";
+  pr "}\n";
+  pr "\n";
   pr "static struct user_data *\n";
   pr "alloc_user_data (void)\n";
   pr "{\n";
+  pr "  static bool init;\n";
+  pr "  if (!init) {\n";
+  pr "    init = true;\n";
+  pr "    atexit (dump_alloc_count);\n";
+  pr "  }\n";
+  pr "  alloc_count++;\n";
   pr "  struct user_data *data = calloc (1, sizeof *data);\n";
   pr "  if (data == NULL) {\n";
   pr "    PyErr_NoMemory ();\n";
@@ -594,6 +612,7 @@ let generate_python_methods_c () =
   pr "{\n";
   pr "  struct user_data *data = user_data;\n";
   pr "\n";
+  pr "  alloc_count--;\n";
   pr "  if (data->fn != NULL)\n";
   pr "    Py_DECREF (data->fn);\n";
   pr "  if (data->buf != NULL)\n";
-- 
2.28.0