__all__ = ['coroutine',
'iscoroutinefunction', 'iscoroutine']
import functools
import inspect
import opcode
import os
import sys
import traceback
import types
from . import compat
from . import events
from . import futures
from .log import logger
# Opcode of "yield from" instruction
_YIELD_FROM = opcode.opmap['YIELD_FROM']
# If you set _DEBUG to true, @coroutine will wrap the resulting
# generator objects in a CoroWrapper instance (defined below). That
# instance will log a message when the generator is never iterated
# over, which may happen when you forget to use "yield from" with a
# coroutine call. Note that the value of the _DEBUG flag is taken
# when the decorator is used, so to be of any use it must be set
# before you define your coroutines. A downside of using this feature
# is that tracebacks show entries for the CoroWrapper.__next__ method
# when _DEBUG is true.
_DEBUG = (not sys.flags.ignore_environment and
bool(os.environ.get('PYTHONASYNCIODEBUG')))
try:
_types_coroutine = types.coroutine
except AttributeError:
_types_coroutine = None
try:
_inspect_iscoroutinefunction = inspect.iscoroutinefunction
except AttributeError:
_inspect_iscoroutinefunction = lambda func: False
try:
from collections.abc import Coroutine as _CoroutineABC, \
Awaitable as _AwaitableABC
except ImportError:
_CoroutineABC = _AwaitableABC = None
# Check for CPython issue #21209
def has_yield_from_bug():
class MyGen:
def __init__(self):
self.send_args = None
def __iter__(self):
return self
def __next__(self):
return 42
def send(self, *what):
self.send_args = what
return None
def yield_from_gen(gen):
yield from gen
value = (1, 2, 3)
gen = MyGen()
coro = yield_from_gen(gen)
next(coro)
coro.send(value)
return gen.send_args != (value,)
_YIELD_FROM_BUG = has_yield_from_bug()
del has_yield_from_bug
def debug_wrapper(gen):
# This function is called from 'sys.set_coroutine_wrapper'.
# We only wrap here coroutines defined via 'async def' syntax.
# Generator-based coroutines are wrapped in @coroutine
# decorator.
return CoroWrapper(gen, None)
class CoroWrapper:
# Wrapper for coroutine object in _DEBUG mode.
def __init__(self, gen, func=None):
assert inspect.isgenerator(gen) or inspect.iscoroutine(gen), gen
self.gen = gen
self.func = func # Used to unwrap @coroutine decorator
self._source_traceback = traceback.extract_stack(sys._getframe(1))
self.__name__ = getattr(gen, '__name__', None)
self.__qualname__ = getattr(gen, '__qualname__', None)
def __repr__(self):
coro_repr = _format_coroutine(self)
if self._source_traceback:
frame = self._source_traceback[-1]
coro_repr += ', created at %s:%s' % (frame[0], frame[1])
return '<%s %s>' % (self.__class__.__name__, coro_repr)
def __iter__(self):
return self
def __next__(self):
return self.gen.send(None)
if _YIELD_FROM_BUG:
# For for CPython issue #21209: using "yield from" and a custom
# generator, generator.send(tuple) unpacks the tuple instead of passing
# the tuple unchanged. Check if the caller is a generator using "yield
# from" to decide if the parameter should be unpacked or not.
def send(self, *value):
frame = sys._getframe()
caller = frame.f_back
assert caller.f_lasti >= 0
if caller.f_code.co_code[caller.f_lasti] != _YIELD_FROM:
value = value[0]
return self.gen.send(value)
else:
def send(self, value):
return self.gen.send(value)
def throw(self, exc):
return self.gen.throw(exc)
def close(self):
return self.gen.close()
@property
def gi_frame(self):
return self.gen.gi_frame
@property
def gi_running(self):
return self.gen.gi_running
@property
def gi_code(self):
return self.gen.gi_code
if compat.PY35:
def __await__(self):
cr_await = getattr(self.gen, 'cr_await', None)
if cr_await is not None:
raise RuntimeError(
"Cannot await on coroutine {!r} while it's "
"awaiting for {!r}".format(self.gen, cr_await))
return self
@property
def gi_yieldfrom(self):
return self.gen.gi_yieldfrom
@property
def cr_await(self):
return self.gen.cr_await
@property
def cr_running(self):
return self.gen.cr_running
@property
def cr_code(self):
return self.gen.cr_code
@property
def cr_frame(self):
return self.gen.cr_frame
def __del__(self):
# Be careful accessing self.gen.frame -- self.gen might not exist.
gen = getattr(self, 'gen', None)
frame = getattr(gen, 'gi_frame', None)
if frame is None:
frame = getattr(gen, 'cr_frame', None)
if frame is not None and frame.f_lasti == -1:
msg = '%r was never yielded from' % self
tb = getattr(self, '_source_traceback', ())
if tb:
tb = ''.join(traceback.format_list(tb))
msg += ('\nCoroutine object created at '
'(most recent call last):\n')
msg += tb.rstrip()
logger.error(msg)
def coroutine(func):
"""Decorator to mark coroutines.
If the coroutine is not yielded from before it is destroyed,
an error message is logged.
"""
if _inspect_iscoroutinefunction(func):
# In Python 3.5 that's all we need to do for coroutines
# defiend with "async def".
# Wrapping in CoroWrapper will happen via
# 'sys.set_coroutine_wrapper' function.
return func
if inspect.isgeneratorfunction(func):
coro = func
else:
@functools.wraps(func)
def coro(*args, **kw):
res = func(*args, **kw)
if isinstance(res, futures.Future) or inspect.isgenerator(res):
res = yield from res
elif _AwaitableABC is not None:
# If 'func' returns an Awaitable (new in 3.5) we
# want to run it.
try:
await_meth = res.__await__
except AttributeError:
pass
else:
if isinstance(res, _AwaitableABC):
res = yield from await_meth()
return res
if not _DEBUG:
if _types_coroutine is None:
wrapper = coro
else:
wrapper = _types_coroutine(coro)
else:
@functools.wraps(func)
def wrapper(*args, **kwds):
w = CoroWrapper(coro(*args, **kwds), func=func)
if w._source_traceback:
del w._source_traceback[-1]
# Python < 3.5 does not implement __qualname__
# on generator objects, so we set it manually.
# We use getattr as some callables (such as
# functools.partial may lack __qualname__).
w.__name__ = getattr(func, '__name__', None)
w.__qualname__ = getattr(func, '__qualname__', None)
return w
wrapper._is_coroutine = True # For iscoroutinefunction().
return wrapper
def iscoroutinefunction(func):
"""Return True if func is a decorated coroutine function."""
return (getattr(func, '_is_coroutine', False) or
_inspect_iscoroutinefunction(func))
_COROUTINE_TYPES = (types.GeneratorType, CoroWrapper)
if _CoroutineABC is not None:
_COROUTINE_TYPES += (_CoroutineABC,)
def iscoroutine(obj):
"""Return True if obj is a coroutine object."""
return isinstance(obj, _COROUTINE_TYPES)
def _format_coroutine(coro):
assert iscoroutine(coro)
coro_name = None
if isinstance(coro, CoroWrapper):
func = coro.func
coro_name = coro.__qualname__
if coro_name is not None:
coro_name = '{}()'.format(coro_name)
else:
func = coro
if coro_name is None:
coro_name = events._format_callback(func, ())
try:
coro_code = coro.gi_code
except AttributeError:
coro_code = coro.cr_code
try:
coro_frame = coro.gi_frame
except AttributeError:
coro_frame = coro.cr_frame
filename = coro_code.co_filename
lineno = 0
if (isinstance(coro, CoroWrapper) and
not inspect.isgeneratorfunction(coro.func) and
coro.func is not None):
source = events._get_function_source(coro.func)
if source is not None:
filename, lineno = source
if coro_frame is None:
coro_repr = ('%s done, defined at %s:%s'
% (coro_name, filename, lineno))
else:
coro_repr = ('%s running, defined at %s:%s'
% (coro_name, filename, lineno))
elif coro_frame is not None:
lineno = coro_frame.f_lineno
coro_repr = ('%s running at %s:%s'
% (coro_name, filename, lineno))
else:
lineno = coro_code.co_firstlineno
coro_repr = ('%s done, defined at %s:%s'
% (coro_name, filename, lineno))
return coro_repr