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GH-100000: Cleanup and polish various watchers code (GH-99998)
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* Initialize `type_watchers` array to `NULL`s
* Optimize code watchers notification
* Optimize func watchers notification
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itamaro authored Dec 14, 2022
1 parent aa8591e commit ae83c78
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Showing 6 changed files with 37 additions and 14 deletions.
1 change: 0 additions & 1 deletion Include/internal/pycore_interp.h
Original file line number Diff line number Diff line change
Expand Up @@ -142,7 +142,6 @@ struct _is {
// Initialized to _PyEval_EvalFrameDefault().
_PyFrameEvalFunction eval_frame;

PyDict_WatchCallback dict_watchers[DICT_MAX_WATCHERS];
PyFunction_WatchCallback func_watchers[FUNC_MAX_WATCHERS];
// One bit is set for each non-NULL entry in func_watchers
uint8_t active_func_watchers;
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6 changes: 4 additions & 2 deletions Modules/_testcapi/watchers.c
Original file line number Diff line number Diff line change
Expand Up @@ -630,14 +630,16 @@ static PyMethodDef test_methods[] = {
{"clear_dict_watcher", clear_dict_watcher, METH_O, NULL},
{"watch_dict", watch_dict, METH_VARARGS, NULL},
{"unwatch_dict", unwatch_dict, METH_VARARGS, NULL},
{"get_dict_watcher_events", get_dict_watcher_events, METH_NOARGS, NULL},
{"get_dict_watcher_events",
(PyCFunction) get_dict_watcher_events, METH_NOARGS, NULL},

// Type watchers.
{"add_type_watcher", add_type_watcher, METH_O, NULL},
{"clear_type_watcher", clear_type_watcher, METH_O, NULL},
{"watch_type", watch_type, METH_VARARGS, NULL},
{"unwatch_type", unwatch_type, METH_VARARGS, NULL},
{"get_type_modified_events", get_type_modified_events, METH_NOARGS, NULL},
{"get_type_modified_events",
(PyCFunction) get_type_modified_events, METH_NOARGS, NULL},

// Code object watchers.
{"add_code_watcher", add_code_watcher, METH_O, NULL},
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15 changes: 11 additions & 4 deletions Objects/codeobject.c
Original file line number Diff line number Diff line change
Expand Up @@ -15,14 +15,21 @@ static void
notify_code_watchers(PyCodeEvent event, PyCodeObject *co)
{
PyInterpreterState *interp = _PyInterpreterState_GET();
if (interp->active_code_watchers) {
assert(interp->_initialized);
for (int i = 0; i < CODE_MAX_WATCHERS; i++) {
assert(interp->_initialized);
uint8_t bits = interp->active_code_watchers;
int i = 0;
while (bits) {
assert(i < CODE_MAX_WATCHERS);
if (bits & 1) {
PyCode_WatchCallback cb = interp->code_watchers[i];
if ((cb != NULL) && (cb(event, co) < 0)) {
// callback must be non-null if the watcher bit is set
assert(cb != NULL);
if (cb(event, co) < 0) {
PyErr_WriteUnraisable((PyObject *) co);
}
}
i++;
bits >>= 1;
}
}

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18 changes: 14 additions & 4 deletions Objects/funcobject.c
Original file line number Diff line number Diff line change
Expand Up @@ -12,11 +12,20 @@ static void
notify_func_watchers(PyInterpreterState *interp, PyFunction_WatchEvent event,
PyFunctionObject *func, PyObject *new_value)
{
for (int i = 0; i < FUNC_MAX_WATCHERS; i++) {
PyFunction_WatchCallback cb = interp->func_watchers[i];
if ((cb != NULL) && (cb(event, func, new_value) < 0)) {
PyErr_WriteUnraisable((PyObject *) func);
uint8_t bits = interp->active_func_watchers;
int i = 0;
while (bits) {
assert(i < FUNC_MAX_WATCHERS);
if (bits & 1) {
PyFunction_WatchCallback cb = interp->func_watchers[i];
// callback must be non-null if the watcher bit is set
assert(cb != NULL);
if (cb(event, func, new_value) < 0) {
PyErr_WriteUnraisable((PyObject *) func);
}
}
i++;
bits >>= 1;
}
}

Expand All @@ -25,6 +34,7 @@ handle_func_event(PyFunction_WatchEvent event, PyFunctionObject *func,
PyObject *new_value)
{
PyInterpreterState *interp = _PyInterpreterState_GET();
assert(interp->_initialized);
if (interp->active_func_watchers) {
notify_func_watchers(interp, event, func, new_value);
}
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7 changes: 4 additions & 3 deletions Objects/typeobject.c
Original file line number Diff line number Diff line change
Expand Up @@ -485,23 +485,24 @@ PyType_Modified(PyTypeObject *type)
}
}

// Notify registered type watchers, if any
if (type->tp_watched) {
PyInterpreterState *interp = _PyInterpreterState_GET();
int bits = type->tp_watched;
int i = 0;
while(bits && i < TYPE_MAX_WATCHERS) {
while (bits) {
assert(i < TYPE_MAX_WATCHERS);
if (bits & 1) {
PyType_WatchCallback cb = interp->type_watchers[i];
if (cb && (cb(type) < 0)) {
PyErr_WriteUnraisable((PyObject *)type);
}
}
i += 1;
i++;
bits >>= 1;
}
}


type->tp_flags &= ~Py_TPFLAGS_VALID_VERSION_TAG;
type->tp_version_tag = 0; /* 0 is not a valid version tag */
}
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4 changes: 4 additions & 0 deletions Python/pystate.c
Original file line number Diff line number Diff line change
Expand Up @@ -461,6 +461,10 @@ interpreter_clear(PyInterpreterState *interp, PyThreadState *tstate)
interp->dict_state.watchers[i] = NULL;
}

for (int i=0; i < TYPE_MAX_WATCHERS; i++) {
interp->type_watchers[i] = NULL;
}

for (int i=0; i < FUNC_MAX_WATCHERS; i++) {
interp->func_watchers[i] = NULL;
}
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