From 22629fd89e470b5fcf5f962a71a2c4726dee8929 Mon Sep 17 00:00:00 2001
From: Kenta Murata <mrkn@mrkn.jp>
Date: Fri, 24 May 2024 14:11:22 +0900
Subject: [PATCH] Ensure GIL state in pycall_pyptr_free

This needs because this function may be called from GC sweeper on non-main threads.
---
 ext/pycall/libpython.c       |  4 ++++
 ext/pycall/pycall.c          | 10 +++++++++-
 ext/pycall/pycall_internal.h |  9 +++++++++
 3 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/ext/pycall/libpython.c b/ext/pycall/libpython.c
index 19406b6..48ca1d2 100644
--- a/ext/pycall/libpython.c
+++ b/ext/pycall/libpython.c
@@ -217,6 +217,10 @@ pycall_init_libpython_api_table(VALUE libpython_handle)
     INIT_API_TABLE_ENTRY2(PyUnicode_DecodeUTF8, PyUnicodeUCS2_DecodeUTF8, required);
     INIT_API_TABLE_ENTRY2(PyUnicode_FromFormatV, PyUnicodeUCS2_FromFormatV, required);
   }
+
+  INIT_API_TABLE_ENTRY(PyGILState_Check, required);
+  INIT_API_TABLE_ENTRY(PyGILState_Ensure, required);
+  INIT_API_TABLE_ENTRY(PyGILState_Release, required);
 }
 
 void
diff --git a/ext/pycall/pycall.c b/ext/pycall/pycall.c
index 8bae130..2c7d56e 100644
--- a/ext/pycall/pycall.c
+++ b/ext/pycall/pycall.c
@@ -139,7 +139,15 @@ pycall_pyptr_free(void *ptr)
     fprintf(stderr, "zero refcnt object %p of type %s\n", pyobj, Py_TYPE(pyobj)->tp_name);
   }
 #endif /* PYCALL_DEBUG_DUMP_REFCNT */
-  pycall_Py_DecRef(pyobj);
+
+  if (Py_API(PyGILState_Check())) {
+    pycall_Py_DecRef(pyobj);
+  }
+  else {
+    PyGILState_STATE gstate = Py_API(PyGILState_Ensure)();
+    pycall_Py_DecRef(pyobj);
+    Py_API(PyGILState_Release)(gstate);
+  }
 }
 
 static size_t _PySys_GetSizeOf(PyObject *);
diff --git a/ext/pycall/pycall_internal.h b/ext/pycall/pycall_internal.h
index 598e983..4a7a06c 100644
--- a/ext/pycall/pycall_internal.h
+++ b/ext/pycall/pycall_internal.h
@@ -519,6 +519,11 @@ PyObject * PyRuby_New(VALUE ruby_object);
 
 /* ==== thread support ==== */
 
+typedef enum {
+  PyGILState_LOCKED,
+  PyGILState_UNLOCKED
+} PyGILState_STATE;
+
 #if   defined(PYCALL_THREAD_WIN32)
 typedef DWORD pycall_tls_key;
 #elif defined(PYCALL_THREAD_PTHREAD)
@@ -669,6 +674,10 @@ typedef struct {
   PyObject * (* PyUnicode_AsUTF8String)(PyObject *);
   PyObject * (* PyUnicode_DecodeUTF8)(char const*, Py_ssize_t, char const *);
   PyObject * (* PyUnicode_FromFormatV)(char const*, ...);
+
+  int (* PyGILState_Check)(void);
+  PyGILState_STATE (* PyGILState_Ensure)(void);
+  void (* PyGILState_Release)(PyGILState_STATE);
 } pycall_libpython_api_table_t;
 
 pycall_libpython_api_table_t *pycall_libpython_api_table(void);