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atexitmodule.c
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363 lines (313 loc) · 9.9 KB
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/*
* atexit - allow programmer to define multiple exit functions to be executed
* upon normal program termination.
*
* Translated from atexit.py by Collin Winter.
+ Copyright 2007 Python Software Foundation.
*/
#include "Python.h"
#include "pycore_atexit.h" // export _Py_AtExit()
#include "pycore_initconfig.h" // _PyStatus_NO_MEMORY
#include "pycore_interp.h" // PyInterpreterState.atexit
#include "pycore_pystate.h" // _PyInterpreterState_GET
/* ===================================================================== */
/* Callback machinery. */
static inline struct atexit_state*
get_atexit_state(void)
{
PyInterpreterState *interp = _PyInterpreterState_GET();
return &interp->atexit;
}
int
PyUnstable_AtExit(PyInterpreterState *interp,
atexit_datacallbackfunc func, void *data)
{
PyThreadState *tstate = _PyThreadState_GET();
_Py_EnsureTstateNotNULL(tstate);
assert(tstate->interp == interp);
atexit_callback *callback = PyMem_Malloc(sizeof(atexit_callback));
if (callback == NULL) {
PyErr_NoMemory();
return -1;
}
callback->func = func;
callback->data = data;
callback->next = NULL;
struct atexit_state *state = &interp->atexit;
_PyAtExit_LockCallbacks(state);
atexit_callback *top = state->ll_callbacks;
if (top == NULL) {
state->ll_callbacks = callback;
}
else {
callback->next = top;
state->ll_callbacks = callback;
}
_PyAtExit_UnlockCallbacks(state);
return 0;
}
/* Clear all callbacks without calling them */
static void
atexit_cleanup(struct atexit_state *state)
{
PyList_Clear(state->callbacks);
}
PyStatus
_PyAtExit_Init(PyInterpreterState *interp)
{
struct atexit_state *state = &interp->atexit;
// _PyAtExit_Init() must only be called once
assert(state->callbacks == NULL);
state->callbacks = PyList_New(0);
if (state->callbacks == NULL) {
return _PyStatus_NO_MEMORY();
}
return _PyStatus_OK();
}
void
_PyAtExit_Fini(PyInterpreterState *interp)
{
// In theory, there shouldn't be any threads left by now, so we
// won't lock this.
struct atexit_state *state = &interp->atexit;
atexit_cleanup(state);
Py_CLEAR(state->callbacks);
atexit_callback *next = state->ll_callbacks;
state->ll_callbacks = NULL;
while (next != NULL) {
atexit_callback *callback = next;
next = callback->next;
atexit_datacallbackfunc exitfunc = callback->func;
void *data = callback->data;
// It was allocated in _PyAtExit_AddCallback().
PyMem_Free(callback);
exitfunc(data);
}
}
static void
atexit_callfuncs(struct atexit_state *state)
{
assert(!PyErr_Occurred());
assert(state->callbacks != NULL);
assert(PyList_CheckExact(state->callbacks));
// Create a copy of the list for thread safety
PyObject *copy = PyList_GetSlice(state->callbacks, 0, PyList_GET_SIZE(state->callbacks));
if (copy == NULL)
{
PyErr_FormatUnraisable("Exception ignored while "
"copying atexit callbacks");
atexit_cleanup(state);
return;
}
for (Py_ssize_t i = 0; i < PyList_GET_SIZE(copy); ++i) {
// We don't have to worry about evil borrowed references, because
// no other threads can access this list.
PyObject *tuple = PyList_GET_ITEM(copy, i);
assert(PyTuple_CheckExact(tuple));
PyObject *func = PyTuple_GET_ITEM(tuple, 0);
PyObject *args = PyTuple_GET_ITEM(tuple, 1);
PyObject *kwargs = PyTuple_GET_ITEM(tuple, 2);
PyObject *res = PyObject_Call(func,
args,
kwargs == Py_None ? NULL : kwargs);
if (res == NULL) {
PyErr_FormatUnraisable(
"Exception ignored in atexit callback %R", func);
}
else {
Py_DECREF(res);
}
}
Py_DECREF(copy);
atexit_cleanup(state);
assert(!PyErr_Occurred());
}
void
_PyAtExit_Call(PyInterpreterState *interp)
{
struct atexit_state *state = &interp->atexit;
atexit_callfuncs(state);
}
/* ===================================================================== */
/* Module methods. */
PyDoc_STRVAR(atexit_register__doc__,
"register($module, func, /, *args, **kwargs)\n\
--\n\
\n\
Register a function to be executed upon normal program termination\n\
\n\
func - function to be called at exit\n\
args - optional arguments to pass to func\n\
kwargs - optional keyword arguments to pass to func\n\
\n\
func is returned to facilitate usage as a decorator.");
static PyObject *
atexit_register(PyObject *module, PyObject *args, PyObject *kwargs)
{
if (PyTuple_GET_SIZE(args) == 0) {
PyErr_SetString(PyExc_TypeError,
"register() takes at least 1 argument (0 given)");
return NULL;
}
PyObject *func = PyTuple_GET_ITEM(args, 0);
if (!PyCallable_Check(func)) {
PyErr_SetString(PyExc_TypeError,
"the first argument must be callable");
return NULL;
}
PyObject *func_args = PyTuple_GetSlice(args, 1, PyTuple_GET_SIZE(args));
if (func_args == NULL) {
return NULL;
}
PyObject *func_kwargs = kwargs;
if (func_kwargs == NULL)
{
func_kwargs = Py_None;
}
PyObject *callback = PyTuple_Pack(3, func, func_args, func_kwargs);
Py_DECREF(func_args);
if (callback == NULL)
{
return NULL;
}
struct atexit_state *state = get_atexit_state();
// atexit callbacks go in a LIFO order
if (PyList_Insert(state->callbacks, 0, callback) < 0)
{
Py_DECREF(callback);
return NULL;
}
Py_DECREF(callback);
return Py_NewRef(func);
}
PyDoc_STRVAR(atexit_run_exitfuncs__doc__,
"_run_exitfuncs($module, /)\n\
--\n\
\n\
Run all registered exit functions.\n\
\n\
If a callback raises an exception, it is logged with sys.unraisablehook.");
static PyObject *
atexit_run_exitfuncs(PyObject *module, PyObject *Py_UNUSED(dummy))
{
struct atexit_state *state = get_atexit_state();
atexit_callfuncs(state);
Py_RETURN_NONE;
}
PyDoc_STRVAR(atexit_clear__doc__,
"_clear($module, /)\n\
--\n\
\n\
Clear the list of previously registered exit functions.");
static PyObject *
atexit_clear(PyObject *module, PyObject *Py_UNUSED(dummy))
{
atexit_cleanup(get_atexit_state());
Py_RETURN_NONE;
}
PyDoc_STRVAR(atexit_ncallbacks__doc__,
"_ncallbacks($module, /)\n\
--\n\
\n\
Return the number of registered exit functions.");
static PyObject *
atexit_ncallbacks(PyObject *module, PyObject *Py_UNUSED(dummy))
{
struct atexit_state *state = get_atexit_state();
assert(state->callbacks != NULL);
assert(PyList_CheckExact(state->callbacks));
return PyLong_FromSsize_t(PyList_GET_SIZE(state->callbacks));
}
static int
atexit_unregister_locked(PyObject *callbacks, PyObject *func)
{
for (Py_ssize_t i = PyList_GET_SIZE(callbacks) - 1; i >= 0; --i) {
PyObject *tuple = Py_NewRef(PyList_GET_ITEM(callbacks, i));
assert(PyTuple_CheckExact(tuple));
PyObject *to_compare = PyTuple_GET_ITEM(tuple, 0);
int cmp = PyObject_RichCompareBool(func, to_compare, Py_EQ);
if (cmp < 0) {
Py_DECREF(tuple);
return -1;
}
if (cmp == 1) {
// We found a callback!
// But its index could have changed if it or other callbacks were
// unregistered during the comparison.
Py_ssize_t j = PyList_GET_SIZE(callbacks) - 1;
j = Py_MIN(j, i);
for (; j >= 0; --j) {
if (PyList_GET_ITEM(callbacks, j) == tuple) {
// We found the callback index! For real!
if (PyList_SetSlice(callbacks, j, j + 1, NULL) < 0) {
Py_DECREF(tuple);
return -1;
}
i = j;
break;
}
}
}
Py_DECREF(tuple);
if (i >= PyList_GET_SIZE(callbacks)) {
i = PyList_GET_SIZE(callbacks);
}
}
return 0;
}
PyDoc_STRVAR(atexit_unregister__doc__,
"unregister($module, func, /)\n\
--\n\
\n\
Unregister an exit function which was previously registered using\n\
atexit.register\n\
\n\
func - function to be unregistered");
static PyObject *
atexit_unregister(PyObject *module, PyObject *func)
{
struct atexit_state *state = get_atexit_state();
int result;
Py_BEGIN_CRITICAL_SECTION(state->callbacks);
result = atexit_unregister_locked(state->callbacks, func);
Py_END_CRITICAL_SECTION();
return result < 0 ? NULL : Py_None;
}
static PyMethodDef atexit_methods[] = {
{"register", _PyCFunction_CAST(atexit_register), METH_VARARGS|METH_KEYWORDS,
atexit_register__doc__},
{"_clear", atexit_clear, METH_NOARGS, atexit_clear__doc__},
{"unregister", atexit_unregister, METH_O, atexit_unregister__doc__},
{"_run_exitfuncs", atexit_run_exitfuncs, METH_NOARGS,
atexit_run_exitfuncs__doc__},
{"_ncallbacks", atexit_ncallbacks, METH_NOARGS,
atexit_ncallbacks__doc__},
{NULL, NULL} /* sentinel */
};
/* ===================================================================== */
/* Initialization function. */
PyDoc_STRVAR(atexit__doc__,
"allow programmer to define multiple exit functions to be executed\n\
upon normal program termination.\n\
\n\
Two public functions, register and unregister, are defined.\n\
");
static PyModuleDef_Slot atexitmodule_slots[] = {
_Py_ABI_SLOT,
{Py_mod_multiple_interpreters, Py_MOD_PER_INTERPRETER_GIL_SUPPORTED},
{Py_mod_gil, Py_MOD_GIL_NOT_USED},
{0, NULL}
};
static struct PyModuleDef atexitmodule = {
PyModuleDef_HEAD_INIT,
.m_name = "atexit",
.m_doc = atexit__doc__,
.m_size = 0,
.m_methods = atexit_methods,
.m_slots = atexitmodule_slots,
};
PyMODINIT_FUNC
PyInit_atexit(void)
{
return PyModuleDef_Init(&atexitmodule);
}