[Python-checkins] bpo-41756: Introduce PyGen_Send C API (GH-22196)
Vladimir Matveev
webhook-mailer at python.org
Fri Sep 18 21:38:46 EDT 2020
https://github.com/python/cpython/commit/2b05361bf7cbbd76035206fd9befe87f37489f1e
commit: 2b05361bf7cbbd76035206fd9befe87f37489f1e
branch: master
author: Vladimir Matveev <vladima at fb.com>
committer: GitHub <noreply at github.com>
date: 2020-09-18T18:38:38-07:00
summary:
bpo-41756: Introduce PyGen_Send C API (GH-22196)
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.
files:
A Misc/NEWS.d/next/Core and Builtins/2020-09-12-12-55-45.bpo-41756.1h0tbV.rst
M Doc/c-api/gen.rst
M Doc/data/refcounts.dat
M Include/genobject.h
M Modules/_asynciomodule.c
M Objects/genobject.c
M Python/ceval.c
diff --git a/Doc/c-api/gen.rst b/Doc/c-api/gen.rst
index 74410927bfde1..e098425e6364d 100644
--- a/Doc/c-api/gen.rst
+++ b/Doc/c-api/gen.rst
@@ -15,6 +15,11 @@ than explicitly calling :c:func:`PyGen_New` or :c:func:`PyGen_NewWithQualName`.
The C structure used for generator objects.
+.. c:type:: PySendResult
+
+ The enum value used to represent different results of :c:func:`PyGen_Send`.
+
+
.. c:var:: PyTypeObject PyGen_Type
The type object corresponding to generator objects.
@@ -42,3 +47,13 @@ than explicitly calling :c:func:`PyGen_New` or :c:func:`PyGen_NewWithQualName`.
with ``__name__`` and ``__qualname__`` set to *name* and *qualname*.
A reference to *frame* is stolen by this function. The *frame* argument
must not be ``NULL``.
+
+.. c:function:: PySendResult PyGen_Send(PyGenObject *gen, PyObject *arg, PyObject **presult)
+
+ Sends the *arg* value into the generator *gen*. Coroutine objects
+ are also allowed to be as the *gen* argument but they need to be
+ explicitly casted to PyGenObject*. Returns:
+
+ - ``PYGEN_RETURN`` if generator returns. Return value is returned via *presult*.
+ - ``PYGEN_NEXT`` if generator yields. Yielded value is returned via *presult*.
+ - ``PYGEN_ERROR`` if generator has raised and exception. *presult* is set to ``NULL``.
diff --git a/Doc/data/refcounts.dat b/Doc/data/refcounts.dat
index 355a4d6d3fa7b..6b1bde37967ae 100644
--- a/Doc/data/refcounts.dat
+++ b/Doc/data/refcounts.dat
@@ -959,6 +959,11 @@ PyGen_NewWithQualName:PyFrameObject*:frame:0:
PyGen_NewWithQualName:PyObject*:name:0:
PyGen_NewWithQualName:PyObject*:qualname:0:
+PyGen_Send:int:::
+PyGen_Send:PyGenObject*:gen:0:
+PyGen_Send:PyObject*:arg:0:
+PyGen_Send:PyObject**:presult:+1:
+
PyCoro_CheckExact:int:::
PyCoro_CheckExact:PyObject*:ob:0:
diff --git a/Include/genobject.h b/Include/genobject.h
index a76dc92e811c4..7488054c68fcd 100644
--- a/Include/genobject.h
+++ b/Include/genobject.h
@@ -45,6 +45,21 @@ PyAPI_FUNC(PyObject *) _PyGen_Send(PyGenObject *, PyObject *);
PyObject *_PyGen_yf(PyGenObject *);
PyAPI_FUNC(void) _PyGen_Finalize(PyObject *self);
+typedef enum {
+ PYGEN_RETURN = 0,
+ PYGEN_ERROR = -1,
+ PYGEN_NEXT = 1,
+} PySendResult;
+
+/* Sends the value into the generator or the coroutine. Returns:
+ - PYGEN_RETURN (0) if generator has returned.
+ 'result' parameter is filled with return value
+ - PYGEN_ERROR (-1) if exception was raised.
+ 'result' parameter is NULL
+ - PYGEN_NEXT (1) if generator has yielded.
+ 'result' parameter is filled with yielded value. */
+PyAPI_FUNC(PySendResult) PyGen_Send(PyGenObject *, PyObject *, PyObject **);
+
#ifndef Py_LIMITED_API
typedef struct {
_PyGenObject_HEAD(cr)
diff --git a/Misc/NEWS.d/next/Core and Builtins/2020-09-12-12-55-45.bpo-41756.1h0tbV.rst b/Misc/NEWS.d/next/Core and Builtins/2020-09-12-12-55-45.bpo-41756.1h0tbV.rst
new file mode 100644
index 0000000000000..b387cfd94033c
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2020-09-12-12-55-45.bpo-41756.1h0tbV.rst
@@ -0,0 +1,2 @@
+Add PyGen_Send function to allow sending value into generator/coroutine
+without raising StopIteration exception to signal return
diff --git a/Modules/_asynciomodule.c b/Modules/_asynciomodule.c
index 4a1c91e9eddd6..2151f20281a31 100644
--- a/Modules/_asynciomodule.c
+++ b/Modules/_asynciomodule.c
@@ -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;
diff --git a/Objects/genobject.c b/Objects/genobject.c
index 809838a4cd2f3..24aca988354c5 100644
--- a/Objects/genobject.c
+++ b/Objects/genobject.c
@@ -137,7 +137,7 @@ gen_dealloc(PyGenObject *gen)
}
static PyObject *
-gen_send_ex(PyGenObject *gen, PyObject *arg, int exc, int closing)
+gen_send_ex(PyGenObject *gen, PyObject *arg, int exc, int closing, int *is_return_value)
{
PyThreadState *tstate = _PyThreadState_GET();
PyFrameObject *f = gen->gi_frame;
@@ -170,6 +170,10 @@ gen_send_ex(PyGenObject *gen, PyObject *arg, int exc, int closing)
PyErr_SetNone(PyExc_StopAsyncIteration);
}
else {
+ if (is_return_value != NULL) {
+ *is_return_value = 1;
+ Py_RETURN_NONE;
+ }
PyErr_SetNone(PyExc_StopIteration);
}
}
@@ -230,18 +234,33 @@ gen_send_ex(PyGenObject *gen, PyObject *arg, int exc, int closing)
/* Delay exception instantiation if we can */
if (PyAsyncGen_CheckExact(gen)) {
PyErr_SetNone(PyExc_StopAsyncIteration);
+ Py_CLEAR(result);
}
else if (arg) {
- /* Set exception if not called by gen_iternext() */
- PyErr_SetNone(PyExc_StopIteration);
+ if (is_return_value != NULL) {
+ *is_return_value = 1;
+ }
+ else {
+ /* Set exception if not called by gen_iternext() */
+ PyErr_SetNone(PyExc_StopIteration);
+ Py_CLEAR(result);
+ }
+ }
+ else {
+ Py_CLEAR(result);
}
}
else {
/* Async generators cannot return anything but None */
assert(!PyAsyncGen_CheckExact(gen));
- _PyGen_SetStopIterationValue(result);
+ if (is_return_value != NULL) {
+ *is_return_value = 1;
+ }
+ else {
+ _PyGen_SetStopIterationValue(result);
+ Py_CLEAR(result);
+ }
}
- Py_CLEAR(result);
}
else if (!result && PyErr_ExceptionMatches(PyExc_StopIteration)) {
const char *msg = "generator raised StopIteration";
@@ -264,7 +283,7 @@ gen_send_ex(PyGenObject *gen, PyObject *arg, int exc, int closing)
_PyErr_FormatFromCause(PyExc_RuntimeError, "%s", msg);
}
- if (!result || _PyFrameHasCompleted(f)) {
+ if ((is_return_value && *is_return_value) || !result || _PyFrameHasCompleted(f)) {
/* generator can't be rerun, so release the frame */
/* first clean reference cycle through stored exception traceback */
_PyErr_ClearExcState(&gen->gi_exc_state);
@@ -283,7 +302,19 @@ return next yielded value or raise StopIteration.");
PyObject *
_PyGen_Send(PyGenObject *gen, PyObject *arg)
{
- return gen_send_ex(gen, arg, 0, 0);
+ return gen_send_ex(gen, arg, 0, 0, NULL);
+}
+
+PySendResult
+PyGen_Send(PyGenObject *gen, PyObject *arg, PyObject **result)
+{
+ assert(result != NULL);
+
+ int is_return_value = 0;
+ if ((*result = gen_send_ex(gen, arg, 0, 0, &is_return_value)) == NULL) {
+ return PYGEN_ERROR;
+ }
+ return is_return_value ? PYGEN_RETURN : PYGEN_NEXT;
}
PyDoc_STRVAR(close_doc,
@@ -365,7 +396,7 @@ gen_close(PyGenObject *gen, PyObject *args)
}
if (err == 0)
PyErr_SetNone(PyExc_GeneratorExit);
- retval = gen_send_ex(gen, Py_None, 1, 1);
+ retval = gen_send_ex(gen, Py_None, 1, 1, NULL);
if (retval) {
const char *msg = "generator ignored GeneratorExit";
if (PyCoro_CheckExact(gen)) {
@@ -413,7 +444,7 @@ _gen_throw(PyGenObject *gen, int close_on_genexit,
gen->gi_frame->f_state = state;
Py_DECREF(yf);
if (err < 0)
- return gen_send_ex(gen, Py_None, 1, 0);
+ return gen_send_ex(gen, Py_None, 1, 0, NULL);
goto throw_here;
}
if (PyGen_CheckExact(yf) || PyCoro_CheckExact(yf)) {
@@ -465,10 +496,10 @@ _gen_throw(PyGenObject *gen, int close_on_genexit,
assert(gen->gi_frame->f_lasti >= 0);
gen->gi_frame->f_lasti += sizeof(_Py_CODEUNIT);
if (_PyGen_FetchStopIterationValue(&val) == 0) {
- ret = gen_send_ex(gen, val, 0, 0);
+ ret = gen_send_ex(gen, val, 0, 0, NULL);
Py_DECREF(val);
} else {
- ret = gen_send_ex(gen, Py_None, 1, 0);
+ ret = gen_send_ex(gen, Py_None, 1, 0, NULL);
}
}
return ret;
@@ -522,7 +553,7 @@ _gen_throw(PyGenObject *gen, int close_on_genexit,
}
PyErr_Restore(typ, val, tb);
- return gen_send_ex(gen, Py_None, 1, 0);
+ return gen_send_ex(gen, Py_None, 1, 0, NULL);
failed_throw:
/* Didn't use our arguments, so restore their original refcounts */
@@ -551,7 +582,7 @@ gen_throw(PyGenObject *gen, PyObject *args)
static PyObject *
gen_iternext(PyGenObject *gen)
{
- return gen_send_ex(gen, NULL, 0, 0);
+ return gen_send_ex(gen, NULL, 0, 0, NULL);
}
/*
@@ -1051,13 +1082,13 @@ coro_wrapper_dealloc(PyCoroWrapper *cw)
static PyObject *
coro_wrapper_iternext(PyCoroWrapper *cw)
{
- return gen_send_ex((PyGenObject *)cw->cw_coroutine, NULL, 0, 0);
+ return gen_send_ex((PyGenObject *)cw->cw_coroutine, NULL, 0, 0, NULL);
}
static PyObject *
coro_wrapper_send(PyCoroWrapper *cw, PyObject *arg)
{
- return gen_send_ex((PyGenObject *)cw->cw_coroutine, arg, 0, 0);
+ return gen_send_ex((PyGenObject *)cw->cw_coroutine, arg, 0, 0, NULL);
}
static PyObject *
@@ -1570,7 +1601,7 @@ async_gen_asend_send(PyAsyncGenASend *o, PyObject *arg)
}
o->ags_gen->ag_running_async = 1;
- result = gen_send_ex((PyGenObject*)o->ags_gen, arg, 0, 0);
+ result = gen_send_ex((PyGenObject*)o->ags_gen, arg, 0, 0, NULL);
result = async_gen_unwrap_value(o->ags_gen, result);
if (result == NULL) {
@@ -1926,7 +1957,7 @@ async_gen_athrow_send(PyAsyncGenAThrow *o, PyObject *arg)
assert(o->agt_state == AWAITABLE_STATE_ITER);
- retval = gen_send_ex((PyGenObject *)gen, arg, 0, 0);
+ retval = gen_send_ex((PyGenObject *)gen, arg, 0, 0, NULL);
if (o->agt_args) {
return async_gen_unwrap_value(o->agt_gen, retval);
} else {
diff --git a/Python/ceval.c b/Python/ceval.c
index f747faaebf024..3de372f45a251 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -2223,29 +2223,53 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
case TARGET(YIELD_FROM): {
PyObject *v = POP();
PyObject *receiver = TOP();
- int err;
- if (PyGen_CheckExact(receiver) || PyCoro_CheckExact(receiver)) {
- retval = _PyGen_Send((PyGenObject *)receiver, v);
+ int is_gen_or_coro = PyGen_CheckExact(receiver) || PyCoro_CheckExact(receiver);
+ int gen_status;
+ if (tstate->c_tracefunc == NULL && is_gen_or_coro) {
+ gen_status = PyGen_Send((PyGenObject *)receiver, v, &retval);
} else {
- _Py_IDENTIFIER(send);
- if (v == Py_None)
- retval = Py_TYPE(receiver)->tp_iternext(receiver);
- else
- retval = _PyObject_CallMethodIdOneArg(receiver, &PyId_send, v);
+ if (is_gen_or_coro) {
+ retval = _PyGen_Send((PyGenObject *)receiver, v);
+ }
+ else {
+ _Py_IDENTIFIER(send);
+ if (v == Py_None) {
+ retval = Py_TYPE(receiver)->tp_iternext(receiver);
+ }
+ else {
+ retval = _PyObject_CallMethodIdOneArg(receiver, &PyId_send, v);
+ }
+ }
+
+ if (retval == NULL) {
+ if (tstate->c_tracefunc != NULL
+ && _PyErr_ExceptionMatches(tstate, PyExc_StopIteration))
+ call_exc_trace(tstate->c_tracefunc, tstate->c_traceobj, tstate, f);
+ if (_PyGen_FetchStopIterationValue(&retval) == 0) {
+ gen_status = PYGEN_RETURN;
+ }
+ else {
+ gen_status = PYGEN_ERROR;
+ }
+ }
+ else {
+ gen_status = PYGEN_NEXT;
+ }
}
Py_DECREF(v);
- if (retval == NULL) {
- PyObject *val;
- if (tstate->c_tracefunc != NULL
- && _PyErr_ExceptionMatches(tstate, PyExc_StopIteration))
- call_exc_trace(tstate->c_tracefunc, tstate->c_traceobj, tstate, f);
- err = _PyGen_FetchStopIterationValue(&val);
- if (err < 0)
- goto error;
+ if (gen_status == PYGEN_ERROR) {
+ assert (retval == NULL);
+ goto error;
+ }
+ if (gen_status == PYGEN_RETURN) {
+ assert (retval != NULL);
+
Py_DECREF(receiver);
- SET_TOP(val);
+ SET_TOP(retval);
+ retval = NULL;
DISPATCH();
}
+ assert (gen_status == PYGEN_NEXT);
/* receiver remains on stack, retval is value to be yielded */
/* and repeat... */
assert(f->f_lasti >= (int)sizeof(_Py_CODEUNIT));
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