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OdbBackend: acquire the GIL in the callbacks, fix write_cb's type argument #1496

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Merged
jdavid merged 2 commits into from
Sep 19, 2026
+208 −74
Merged

OdbBackend: acquire the GIL in the callbacks, fix write_cb's type argument #1496

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93209db
odb backend: acquire the GIL in the callbacks
cboos Sep 19, 2026
663d3d7
odb backend: pass the object type to write_cb as an int
cboos Sep 19, 2026
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203 changes: 129 additions & 74 deletions src/odb_backend.c
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Original file line number Diff line number Diff line change
Expand Up @@ -56,39 +56,50 @@ typedef struct {
PyObject *py_backend;
} pgit_odb_backend;

/*
* The callbacks below may be called by libgit2 without the GIL: cffi releases
* it around every C call, and functions such as git_index_add_bypath end up
* here. So they must acquire it before calling into Python.
*/

static int
pgit_odb_backend_read(void **ptr, size_t *sz, git_object_t *type,
git_odb_backend *_be, const git_oid *oid)
{
pgit_odb_backend *be = (pgit_odb_backend *)_be;
PyObject *result = NULL;
int err = GIT_EUSER;
PyGILState_STATE gil = PyGILState_Ensure();

PyObject *py_oid = git_oid_to_python(oid);
if (py_oid == NULL)
return GIT_EUSER;
goto done;

PyObject *result = PyObject_CallMethod(be->py_backend, "read_cb", "N", py_oid);
if (result == NULL)
return git_error_for_exc();
result = PyObject_CallMethod(be->py_backend, "read_cb", "N", py_oid);
if (result == NULL) {
err = git_error_for_exc();
goto done;
}

const char *bytes;
Py_ssize_t type_value;
Py_ssize_t py_sz;
if (!PyArg_ParseTuple(result, "ny#", &type_value, &bytes, &py_sz) || !bytes) {
Py_DECREF(result);
return GIT_EUSER;
}
if (!PyArg_ParseTuple(result, "ny#", &type_value, &bytes, &py_sz) || !bytes)
goto done;
*type = (git_object_t)type_value;
*sz = (size_t)py_sz;

*ptr = git_odb_backend_data_alloc(_be, *sz);
if (!*ptr) {
Py_DECREF(result);
return GIT_EUSER;
}
if (!*ptr)
goto done;

memcpy(*ptr, bytes, *sz);
Py_DECREF(result);
return 0;
err = 0;

done:
Py_XDECREF(result);
PyGILState_Release(gil);
return err;
}

static int
Expand All @@ -101,94 +112,119 @@ pgit_odb_backend_read_prefix(git_oid *oid_out, void **ptr, size_t *sz, git_objec

// Call callback
pgit_odb_backend *be = (pgit_odb_backend *)_be;
int err = GIT_EUSER;
PyGILState_STATE gil = PyGILState_Ensure();
PyObject *result = PyObject_CallMethod(be->py_backend, "read_prefix_cb", "s#", short_id_hex, len);
if (result == NULL)
return git_error_for_exc();
if (result == NULL) {
err = git_error_for_exc();
goto done;
}

// Parse output from callback
PyObject *py_oid_out;
Py_ssize_t type_value;
Py_ssize_t py_sz;
const char *bytes;
if (!PyArg_ParseTuple(result, "ny#O", &type_value, &bytes, &py_sz, &py_oid_out) || !bytes) {
Py_DECREF(result);
return GIT_EUSER;
}
if (!PyArg_ParseTuple(result, "ny#O", &type_value, &bytes, &py_sz, &py_oid_out) || !bytes)
goto done;
*type = (git_object_t)type_value;
*sz = (size_t)py_sz;

*ptr = git_odb_backend_data_alloc(_be, *sz);
if (!*ptr) {
Py_DECREF(result);
return GIT_EUSER;
}
if (!*ptr)
goto done;

memcpy(*ptr, bytes, *sz);
size_t oid_len = py_oid_to_git_oid(py_oid_out, oid_out);
Py_DECREF(result);
if (oid_len == 0)
return GIT_EUSER;
return 0;
if (py_oid_to_git_oid(py_oid_out, oid_out) == 0)
goto done;
err = 0;

done:
Py_XDECREF(result);
PyGILState_Release(gil);
return err;
}

static int
pgit_odb_backend_read_header(size_t *len, git_object_t *type,
git_odb_backend *_be, const git_oid *oid)
{
pgit_odb_backend *be = (pgit_odb_backend *)_be;
PyObject *result = NULL;
int err = GIT_EUSER;
PyGILState_STATE gil = PyGILState_Ensure();

PyObject *py_oid = git_oid_to_python(oid);
if (py_oid == NULL)
return GIT_EUSER;
goto done;

PyObject *result = PyObject_CallMethod(be->py_backend, "read_header_cb", "N", py_oid);
if (result == NULL)
return git_error_for_exc();
result = PyObject_CallMethod(be->py_backend, "read_header_cb", "N", py_oid);
if (result == NULL) {
err = git_error_for_exc();
goto done;
}

Py_ssize_t type_value;
if (!PyArg_ParseTuple(result, "nn", &type_value, len)) {
Py_DECREF(result);
return GIT_EUSER;
}
if (!PyArg_ParseTuple(result, "nn", &type_value, len))
goto done;
*type = (git_object_t)type_value;
err = 0;

Py_DECREF(result);
return 0;
done:
Py_XDECREF(result);
PyGILState_Release(gil);
return err;
}

static int
pgit_odb_backend_write(git_odb_backend *_be, const git_oid *oid,
const void *data, size_t sz, git_object_t typ)
{
pgit_odb_backend *be = (pgit_odb_backend *)_be;
PyObject *result = NULL;
int err = GIT_EUSER;
PyGILState_STATE gil = PyGILState_Ensure();

PyObject *py_oid = git_oid_to_python(oid);
if (py_oid == NULL)
return GIT_EUSER;
goto done;

PyObject *result = PyObject_CallMethod(be->py_backend, "write_cb", "Ny#n", py_oid, data, sz, typ);
if (result == NULL)
return git_error_for_exc();
result = PyObject_CallMethod(be->py_backend, "write_cb", "Ny#i", py_oid, data, sz, (int)typ);
if (result == NULL) {
err = git_error_for_exc();
goto done;
}
err = 0;

Py_DECREF(result);
return 0;
done:
Py_XDECREF(result);
PyGILState_Release(gil);
return err;
}

static int
pgit_odb_backend_exists(git_odb_backend *_be, const git_oid *oid)
{
pgit_odb_backend *be = (pgit_odb_backend *)_be;
PyObject *result = NULL;
int r = GIT_EUSER;
PyGILState_STATE gil = PyGILState_Ensure();

PyObject *py_oid = git_oid_to_python(oid);
if (py_oid == NULL)
return GIT_EUSER;
goto done;

result = PyObject_CallMethod(be->py_backend, "exists_cb", "N", py_oid);
if (result == NULL) {
r = git_error_for_exc();
goto done;
}

PyObject *result = PyObject_CallMethod(be->py_backend, "exists_cb", "N", py_oid);
if (result == NULL)
return git_error_for_exc();
r = PyObject_IsTrue(result);

int r = PyObject_IsTrue(result);
Py_DECREF(result);
done:
Py_XDECREF(result);
PyGILState_Release(gil);
return r;
}

Expand All @@ -202,67 +238,86 @@ pgit_odb_backend_exists_prefix(git_oid *out, git_odb_backend *_be,

// Call callback
pgit_odb_backend *be = (pgit_odb_backend *)_be;
int err = GIT_EUSER;
PyGILState_STATE gil = PyGILState_Ensure();
PyObject *py_oid = PyObject_CallMethod(be->py_backend, "exists_prefix_cb", "s#", short_id_hex, len);
if (py_oid == NULL)
return git_error_for_exc();
if (py_oid == NULL) {
err = git_error_for_exc();
goto done;
}

size_t oid_len = py_oid_to_git_oid(py_oid, out);
Py_DECREF(py_oid);
if (oid_len == 0)
return GIT_EUSER;
return 0;
if (py_oid_to_git_oid(py_oid, out) == 0)
goto done;
err = 0;

done:
Py_XDECREF(py_oid);
PyGILState_Release(gil);
return err;
}

static int
pgit_odb_backend_refresh(git_odb_backend *_be)
{
pgit_odb_backend *be = (pgit_odb_backend *)_be;
PyGILState_STATE gil = PyGILState_Ensure();
PyObject_CallMethod(be->py_backend, "refresh_cb", NULL);
return git_error_for_exc();
int err = git_error_for_exc();
PyGILState_Release(gil);
return err;
}

static int
pgit_odb_backend_foreach(git_odb_backend *_be,
git_odb_foreach_cb cb, void *payload)
{
PyObject *item;
PyObject *iterator = NULL;
git_oid oid;
pgit_odb_backend *be = (pgit_odb_backend *)_be;
int err = GIT_EUSER;
PyGILState_STATE gil = PyGILState_Ensure();

/* Call the Python __iter__ method directly. PyObject_GetIter would invoke
* the C tp_iter slot (OdbBackend_as_iter), which calls this function back
* and causes infinite recursion for Python backends. */
PyObject *iter_method = PyObject_GetAttrString((PyObject *)be->py_backend, "__iter__");
if (iter_method == NULL)
return git_error_for_exc();
if (iter_method == NULL) {
err = git_error_for_exc();
goto done;
}

PyObject *iterator = PyObject_CallObject(iter_method, NULL);
iterator = PyObject_CallObject(iter_method, NULL);
Py_DECREF(iter_method);
if (iterator == NULL)
return git_error_for_exc();
if (iterator == NULL) {
err = git_error_for_exc();
goto done;
}

while ((item = PyIter_Next(iterator))) {
size_t len = py_oid_to_git_oid(item, &oid);
Py_DECREF(item);
if (len == 0) {
Py_DECREF(iterator);
return GIT_EUSER;
}
if (cb(&oid, payload) != 0) {
Py_DECREF(iterator);
return GIT_EUSER;
}
if (len == 0)
goto done;
if (cb(&oid, payload) != 0)
goto done;
}

Py_DECREF(iterator);
return git_error_for_exc();
err = git_error_for_exc();

done:
Py_XDECREF(iterator);
PyGILState_Release(gil);
return err;
}

static void
pgit_odb_backend_free(git_odb_backend *backend)
{
pgit_odb_backend *custom_backend = (pgit_odb_backend *)backend;
PyGILState_STATE gil = PyGILState_Ensure();
Py_DECREF(custom_backend->py_backend);
PyGILState_Release(gil);
}

int
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