cpython/Modules/atexitmodule.c at main · python/cpython · GitHub

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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.

#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

/*[clinic input]

module atexit

[clinic start generated code]*/

/*[clinic end generated code: output=da39a3ee5e6b4b0d input=ac8fd67d15bf23fc]*/

#include "clinic/atexitmodule.c.h"

/* ===================================================================== */

/* 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. */

/*[clinic input]

atexit.register

func: object

*args: tuple

**kwargs: dict

func - function to be called at exit

args - optional arguments to pass to func

kwargs - optional keyword arguments to pass to func

func is returned to facilitate usage as a decorator.

[clinic start generated code]*/

static PyObject *

atexit_register_impl(PyObject *module, PyObject *func, PyObject *args,

PyObject *kwargs)

/*[clinic end generated code: output=c921286994bd8612 input=a682b5a343a82e4a]*/

{

if (!PyCallable_Check(func)) {

PyErr_SetString(PyExc_TypeError,

"the first argument must be callable");

return NULL;

}

PyObject *callback = PyTuple_Pack(3, func, args, kwargs);

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[] = {

ATEXIT_REGISTER_METHODDEF

{"_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);

}

cpython/Modules/atexitmodule.c at main · python/cpython · GitHub

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