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bpo-41756: Introduce PyGen_Send C API (GH-22196)

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The new API allows to efficiently send values into native generators
and coroutines avoiding use of StopIteration exceptions to signal 
returns.

ceval loop now uses this method instead of the old "private"
_PyGen_Send C API. This translates to 1.6x increased performance
of 'await' calls in micro-benchmarks.

Aside from CPython core improvements, this new API will also allow 
Cython to generate more efficient code, benefiting high-performance
IO libraries like uvloop.
This commit is contained in:
Vladimir Matveev 2020-09-18 18:38:38 -07:00 • committed by GitHub
parent ec8a15b034
commit 2b05361bf7
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GPG key ID: 4AEE18F83AFDEB23
7 changed files with 148 additions and 39 deletions
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27
Modules/_asynciomodule.c
View file

@ -2621,6 +2621,20 @@ task_set_error_soon(TaskObj *task, PyObject *et, const char *format, ...)
Py_RETURN_NONE;
}
static inline int
gen_status_from_result(PyObject **result)
{
if (*result != NULL) {
return PYGEN_NEXT;
}
if (_PyGen_FetchStopIterationValue(result) == 0) {
return PYGEN_RETURN;
}
assert(PyErr_Occurred());
return PYGEN_ERROR;
}
static PyObject *
task_step_impl(TaskObj *task, PyObject *exc)
{
@ -2679,26 +2693,29 @@ task_step_impl(TaskObj *task, PyObject *exc)
return NULL;
}
int gen_status = PYGEN_ERROR;
if (exc == NULL) {
if (PyGen_CheckExact(coro) || PyCoro_CheckExact(coro)) {
result = _PyGen_Send((PyGenObject*)coro, Py_None);
gen_status = PyGen_Send((PyGenObject*)coro, Py_None, &result);
}
else {
result = _PyObject_CallMethodIdOneArg(coro, &PyId_send, Py_None);
gen_status = gen_status_from_result(&result);
}
}
else {
result = _PyObject_CallMethodIdOneArg(coro, &PyId_throw, exc);
gen_status = gen_status_from_result(&result);
if (clear_exc) {
/* We created 'exc' during this call */
Py_DECREF(exc);
}
}
if (result == NULL) {
if (gen_status == PYGEN_RETURN || gen_status == PYGEN_ERROR) {
PyObject *et, *ev, *tb;
if (_PyGen_FetchStopIterationValue(&o) == 0) {
if (result != NULL) {
/* The error is StopIteration and that means that
the underlying coroutine has resolved */
@ -2709,10 +2726,10 @@ task_step_impl(TaskObj *task, PyObject *exc)
res = future_cancel((FutureObj*)task, task->task_cancel_msg);
}
else {
res = future_set_result((FutureObj*)task, o);
res = future_set_result((FutureObj*)task, result);
}
Py_DECREF(o);
Py_DECREF(result);
if (res == NULL) {
return NULL;