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Issue #28003: Implement PEP 525 -- Asynchronous Generators.
1 parent b96ef55 commit eb63645

27 files changed

+2188
-95
lines changed

‎Include/ceval.h‎

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -25,6 +25,10 @@ PyAPI_FUNC(void) PyEval_SetProfile(Py_tracefunc, PyObject *);
2525
PyAPI_FUNC(void) PyEval_SetTrace(Py_tracefunc, PyObject *);
2626
PyAPI_FUNC(void) _PyEval_SetCoroutineWrapper(PyObject *);
2727
PyAPI_FUNC(PyObject *) _PyEval_GetCoroutineWrapper(void);
28+
PyAPI_FUNC(void) _PyEval_SetAsyncGenFirstiter(PyObject *);
29+
PyAPI_FUNC(PyObject *) _PyEval_GetAsyncGenFirstiter(void);
30+
PyAPI_FUNC(void) _PyEval_SetAsyncGenFinalizer(PyObject *);
31+
PyAPI_FUNC(PyObject *) _PyEval_GetAsyncGenFinalizer(void);
2832
#endif
2933

3034
struct _frame; /* Avoid including frameobject.h */

‎Include/code.h‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -59,6 +59,7 @@ typedef struct {
5959
``async def`` keywords) */
6060
#define CO_COROUTINE 0x0080
6161
#define CO_ITERABLE_COROUTINE 0x0100
62+
#define CO_ASYNC_GENERATOR 0x0200
6263

6364
/* These are no longer used. */
6465
#if 0

‎Include/genobject.h‎

Lines changed: 31 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -61,6 +61,37 @@ PyObject *_PyAIterWrapper_New(PyObject *aiter);
6161
PyObject *_PyCoro_GetAwaitableIter(PyObject *o);
6262
PyAPI_FUNC(PyObject *) PyCoro_New(struct _frame *,
6363
PyObject *name, PyObject *qualname);
64+
65+
/* Asynchronous Generators */
66+
67+
typedef struct {
68+
_PyGenObject_HEAD(ag)
69+
PyObject *ag_finalizer;
70+
71+
/* Flag is set to 1 when hooks set up by sys.set_asyncgen_hooks
72+
were called on the generator, to avoid calling them more
73+
than once. */
74+
int ag_hooks_inited;
75+
76+
/* Flag is set to 1 when aclose() is called for the first time, or
77+
when a StopAsyncIteration exception is raised. */
78+
int ag_closed;
79+
} PyAsyncGenObject;
80+
81+
PyAPI_DATA(PyTypeObject) PyAsyncGen_Type;
82+
PyAPI_DATA(PyTypeObject) _PyAsyncGenASend_Type;
83+
PyAPI_DATA(PyTypeObject) _PyAsyncGenWrappedValue_Type;
84+
PyAPI_DATA(PyTypeObject) _PyAsyncGenAThrow_Type;
85+
86+
PyAPI_FUNC(PyObject *) PyAsyncGen_New(struct _frame *,
87+
PyObject *name, PyObject *qualname);
88+
89+
#define PyAsyncGen_CheckExact(op) (Py_TYPE(op) == &PyAsyncGen_Type)
90+
91+
PyObject *_PyAsyncGenValueWrapperNew(PyObject *);
92+
93+
int PyAsyncGen_ClearFreeLists(void);
94+
6495
#endif
6596

6697
#undef _PyGenObject_HEAD

‎Include/pylifecycle.h‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -107,6 +107,7 @@ PyAPI_FUNC(void) _PyGC_Fini(void);
107107
PyAPI_FUNC(void) PySlice_Fini(void);
108108
PyAPI_FUNC(void) _PyType_Fini(void);
109109
PyAPI_FUNC(void) _PyRandom_Fini(void);
110+
PyAPI_FUNC(void) PyAsyncGen_Fini(void);
110111

111112
PyAPI_DATA(PyThreadState *) _Py_Finalizing;
112113
#endif

‎Include/pystate.h‎

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -148,6 +148,9 @@ typedef struct _ts {
148148
Py_ssize_t co_extra_user_count;
149149
freefunc co_extra_freefuncs[MAX_CO_EXTRA_USERS];
150150

151+
PyObject *async_gen_firstiter;
152+
PyObject *async_gen_finalizer;
153+
151154
/* XXX signal handlers should also be here */
152155

153156
} PyThreadState;

‎Include/symtable.h‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -48,6 +48,7 @@ typedef struct _symtable_entry {
4848
unsigned ste_child_free : 1; /* true if a child block has free vars,
4949
including free refs to globals */
5050
unsigned ste_generator : 1; /* true if namespace is a generator */
51+
unsigned ste_coroutine : 1; /* true if namespace is a coroutine */
5152
unsigned ste_varargs : 1; /* true if block has varargs */
5253
unsigned ste_varkeywords : 1; /* true if block has varkeywords */
5354
unsigned ste_returns_value : 1; /* true if namespace uses return with

‎Lib/asyncio/base_events.py‎

Lines changed: 55 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -13,7 +13,6 @@
1313
to modify the meaning of the API call itself.
1414
"""
1515

16-
1716
import collections
1817
import concurrent.futures
1918
import heapq
@@ -28,6 +27,7 @@
2827
import traceback
2928
import sys
3029
import warnings
30+
import weakref
3131

3232
from . import compat
3333
from . import coroutines
@@ -242,6 +242,13 @@ def __init__(self):
242242
self._task_factory = None
243243
self._coroutine_wrapper_set = False
244244

245+
# A weak set of all asynchronous generators that are being iterated
246+
# by the loop.
247+
self._asyncgens = weakref.WeakSet()
248+
249+
# Set to True when `loop.shutdown_asyncgens` is called.
250+
self._asyncgens_shutdown_called = False
251+
245252
def __repr__(self):
246253
return ('<%s running=%s closed=%s debug=%s>'
247254
% (self.__class__.__name__, self.is_running(),
@@ -333,13 +340,56 @@ def _check_closed(self):
333340
if self._closed:
334341
raise RuntimeError('Event loop is closed')
335342

343+
def _asyncgen_finalizer_hook(self, agen):
344+
self._asyncgens.discard(agen)
345+
if not self.is_closed():
346+
self.create_task(agen.aclose())
347+
348+
def _asyncgen_firstiter_hook(self, agen):
349+
if self._asyncgens_shutdown_called:
350+
warnings.warn(
351+
"asynchronous generator {!r} was scheduled after "
352+
"loop.shutdown_asyncgens() call".format(agen),
353+
ResourceWarning, source=self)
354+
355+
self._asyncgens.add(agen)
356+
357+
@coroutine
358+
def shutdown_asyncgens(self):
359+
"""Shutdown all active asynchronous generators."""
360+
self._asyncgens_shutdown_called = True
361+
362+
if not len(self._asyncgens):
363+
return
364+
365+
closing_agens = list(self._asyncgens)
366+
self._asyncgens.clear()
367+
368+
shutdown_coro = tasks.gather(
369+
*[ag.aclose() for ag in closing_agens],
370+
return_exceptions=True,
371+
loop=self)
372+
373+
results = yield from shutdown_coro
374+
for result, agen in zip(results, closing_agens):
375+
if isinstance(result, Exception):
376+
self.call_exception_handler({
377+
'message': 'an error occurred during closing of '
378+
'asynchronous generator {!r}'.format(agen),
379+
'exception': result,
380+
'asyncgen': agen
381+
})
382+
336383
def run_forever(self):
337384
"""Run until stop() is called."""
338385
self._check_closed()
339386
if self.is_running():
340387
raise RuntimeError('Event loop is running.')
341388
self._set_coroutine_wrapper(self._debug)
342389
self._thread_id = threading.get_ident()
390+
old_agen_hooks = sys.get_asyncgen_hooks()
391+
sys.set_asyncgen_hooks(firstiter=self._asyncgen_firstiter_hook,
392+
finalizer=self._asyncgen_finalizer_hook)
343393
try:
344394
while True:
345395
self._run_once()
@@ -349,6 +399,7 @@ def run_forever(self):
349399
self._stopping = False
350400
self._thread_id = None
351401
self._set_coroutine_wrapper(False)
402+
sys.set_asyncgen_hooks(*old_agen_hooks)
352403

353404
def run_until_complete(self, future):
354405
"""Run until the Future is done.
@@ -1179,7 +1230,9 @@ def call_exception_handler(self, context):
11791230
- 'handle' (optional): Handle instance;
11801231
- 'protocol' (optional): Protocol instance;
11811232
- 'transport' (optional): Transport instance;
1182-
- 'socket' (optional): Socket instance.
1233+
- 'socket' (optional): Socket instance;
1234+
- 'asyncgen' (optional): Asynchronous generator that caused
1235+
the exception.
11831236
11841237
New keys maybe introduced in the future.
11851238

‎Lib/asyncio/coroutines.py‎

Lines changed: 4 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -276,7 +276,10 @@ def _format_coroutine(coro):
276276
try:
277277
coro_code = coro.gi_code
278278
except AttributeError:
279-
coro_code = coro.cr_code
279+
try:
280+
coro_code = coro.cr_code
281+
except AttributeError:
282+
return repr(coro)
280283

281284
try:
282285
coro_frame = coro.gi_frame

‎Lib/asyncio/events.py‎

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -248,6 +248,10 @@ def close(self):
248248
"""
249249
raise NotImplementedError
250250

251+
def shutdown_asyncgens(self):
252+
"""Shutdown all active asynchronous generators."""
253+
raise NotImplementedError
254+
251255
# Methods scheduling callbacks. All these return Handles.
252256

253257
def _timer_handle_cancelled(self, handle):

‎Lib/dis.py‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -87,6 +87,7 @@ def distb(tb=None, *, file=None):
8787
64: "NOFREE",
8888
128: "COROUTINE",
8989
256: "ITERABLE_COROUTINE",
90+
512: "ASYNC_GENERATOR",
9091
}
9192

9293
def pretty_flags(flags):

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