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5376ba9630
Summary of changes:
1. Coroutines now have a distinct, separate from generators
type at the C level: PyGen_Type, and a new typedef PyCoroObject.
PyCoroObject shares the initial segment of struct layout with
PyGenObject, making it possible to reuse existing generators
machinery. The new type is exposed as 'types.CoroutineType'.
As a consequence of having a new type, CO_GENERATOR flag is
no longer applied to coroutines.
2. Having a separate type for coroutines made it possible to add
an __await__ method to the type. Although it is not used by the
interpreter (see details on that below), it makes coroutines
naturally (without using __instancecheck__) conform to
collections.abc.Coroutine and collections.abc.Awaitable ABCs.
[The __instancecheck__ is still used for generator-based
coroutines, as we don't want to add __await__ for generators.]
3. Add new opcode: GET_YIELD_FROM_ITER. The opcode is needed to
allow passing native coroutines to the YIELD_FROM opcode.
Before this change, 'yield from o' expression was compiled to:
(o)
GET_ITER
LOAD_CONST
YIELD_FROM
Now, we use GET_YIELD_FROM_ITER instead of GET_ITER.
The reason for adding a new opcode is that GET_ITER is used
in some contexts (such as 'for .. in' loops) where passing
a coroutine object is invalid.
4. Add two new introspection functions to the inspec module:
getcoroutinestate(c) and getcoroutinelocals(c).
5. inspect.iscoroutine(o) is updated to test if 'o' is a native
coroutine object. Before this commit it used abc.Coroutine,
and it was requested to update inspect.isgenerator(o) to use
abc.Generator; it was decided, however, that inspect functions
should really be tailored for checking for native types.
6. sys.set_coroutine_wrapper(w) API is updated to work with only
native coroutines. Since types.coroutine decorator supports
any type of callables now, it would be confusing that it does
not work for all types of coroutines.
7. Exceptions logic in generators C implementation was updated
to raise clearer messages for coroutines:
Before: TypeError("generator raised StopIteration")
After: TypeError("coroutine raised StopIteration")
261 lines
8.1 KiB
Python
261 lines
8.1 KiB
Python
__all__ = ['coroutine',
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'iscoroutinefunction', 'iscoroutine']
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import functools
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import inspect
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import opcode
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import os
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import sys
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import traceback
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import types
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from . import events
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from . import futures
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from .log import logger
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_PY35 = sys.version_info >= (3, 5)
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# Opcode of "yield from" instruction
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_YIELD_FROM = opcode.opmap['YIELD_FROM']
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# If you set _DEBUG to true, @coroutine will wrap the resulting
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# generator objects in a CoroWrapper instance (defined below). That
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# instance will log a message when the generator is never iterated
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# over, which may happen when you forget to use "yield from" with a
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# coroutine call. Note that the value of the _DEBUG flag is taken
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# when the decorator is used, so to be of any use it must be set
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# before you define your coroutines. A downside of using this feature
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# is that tracebacks show entries for the CoroWrapper.__next__ method
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# when _DEBUG is true.
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_DEBUG = (not sys.flags.ignore_environment
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and bool(os.environ.get('PYTHONASYNCIODEBUG')))
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try:
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_types_coroutine = types.coroutine
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except AttributeError:
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_types_coroutine = None
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try:
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_inspect_iscoroutinefunction = inspect.iscoroutinefunction
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except AttributeError:
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_inspect_iscoroutinefunction = lambda func: False
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try:
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from collections.abc import Coroutine as _CoroutineABC, \
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Awaitable as _AwaitableABC
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except ImportError:
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_CoroutineABC = _AwaitableABC = None
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# Check for CPython issue #21209
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def has_yield_from_bug():
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class MyGen:
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def __init__(self):
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self.send_args = None
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def __iter__(self):
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return self
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def __next__(self):
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return 42
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def send(self, *what):
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self.send_args = what
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return None
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def yield_from_gen(gen):
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yield from gen
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value = (1, 2, 3)
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gen = MyGen()
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coro = yield_from_gen(gen)
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next(coro)
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coro.send(value)
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return gen.send_args != (value,)
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_YIELD_FROM_BUG = has_yield_from_bug()
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del has_yield_from_bug
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def debug_wrapper(gen):
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# This function is called from 'sys.set_coroutine_wrapper'.
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# We only wrap here coroutines defined via 'async def' syntax.
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# Generator-based coroutines are wrapped in @coroutine
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# decorator.
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return CoroWrapper(gen, None)
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class CoroWrapper:
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# Wrapper for coroutine object in _DEBUG mode.
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def __init__(self, gen, func=None):
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assert inspect.isgenerator(gen) or inspect.iscoroutine(gen), gen
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self.gen = gen
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self.func = func # Used to unwrap @coroutine decorator
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self._source_traceback = traceback.extract_stack(sys._getframe(1))
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self.__name__ = getattr(gen, '__name__', None)
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self.__qualname__ = getattr(gen, '__qualname__', None)
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def __repr__(self):
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coro_repr = _format_coroutine(self)
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if self._source_traceback:
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frame = self._source_traceback[-1]
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coro_repr += ', created at %s:%s' % (frame[0], frame[1])
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return '<%s %s>' % (self.__class__.__name__, coro_repr)
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def __iter__(self):
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return self
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if _PY35:
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__await__ = __iter__ # make compatible with 'await' expression
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def __next__(self):
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return self.gen.send(None)
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if _YIELD_FROM_BUG:
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# For for CPython issue #21209: using "yield from" and a custom
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# generator, generator.send(tuple) unpacks the tuple instead of passing
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# the tuple unchanged. Check if the caller is a generator using "yield
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# from" to decide if the parameter should be unpacked or not.
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def send(self, *value):
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frame = sys._getframe()
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caller = frame.f_back
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assert caller.f_lasti >= 0
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if caller.f_code.co_code[caller.f_lasti] != _YIELD_FROM:
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value = value[0]
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return self.gen.send(value)
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else:
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def send(self, value):
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return self.gen.send(value)
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def throw(self, exc):
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return self.gen.throw(exc)
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def close(self):
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return self.gen.close()
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@property
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def gi_frame(self):
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return self.gen.gi_frame
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@property
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def gi_running(self):
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return self.gen.gi_running
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@property
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def gi_code(self):
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return self.gen.gi_code
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def __del__(self):
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# Be careful accessing self.gen.frame -- self.gen might not exist.
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gen = getattr(self, 'gen', None)
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frame = getattr(gen, 'gi_frame', None)
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if frame is not None and frame.f_lasti == -1:
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msg = '%r was never yielded from' % self
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tb = getattr(self, '_source_traceback', ())
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if tb:
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tb = ''.join(traceback.format_list(tb))
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msg += ('\nCoroutine object created at '
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'(most recent call last):\n')
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msg += tb.rstrip()
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logger.error(msg)
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def coroutine(func):
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"""Decorator to mark coroutines.
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If the coroutine is not yielded from before it is destroyed,
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an error message is logged.
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"""
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if _inspect_iscoroutinefunction(func):
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# In Python 3.5 that's all we need to do for coroutines
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# defiend with "async def".
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# Wrapping in CoroWrapper will happen via
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# 'sys.set_coroutine_wrapper' function.
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return func
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if inspect.isgeneratorfunction(func):
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coro = func
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else:
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@functools.wraps(func)
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def coro(*args, **kw):
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res = func(*args, **kw)
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if isinstance(res, futures.Future) or inspect.isgenerator(res):
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res = yield from res
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elif _AwaitableABC is not None:
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# If 'func' returns an Awaitable (new in 3.5) we
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# want to run it.
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try:
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await_meth = res.__await__
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except AttributeError:
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pass
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else:
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if isinstance(res, _AwaitableABC):
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res = yield from await_meth()
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return res
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if not _DEBUG:
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if _types_coroutine is None:
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wrapper = coro
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else:
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wrapper = _types_coroutine(coro)
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else:
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@functools.wraps(func)
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def wrapper(*args, **kwds):
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w = CoroWrapper(coro(*args, **kwds), func=func)
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if w._source_traceback:
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del w._source_traceback[-1]
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# Python < 3.5 does not implement __qualname__
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# on generator objects, so we set it manually.
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# We use getattr as some callables (such as
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# functools.partial may lack __qualname__).
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w.__name__ = getattr(func, '__name__', None)
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w.__qualname__ = getattr(func, '__qualname__', None)
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return w
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wrapper._is_coroutine = True # For iscoroutinefunction().
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return wrapper
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def iscoroutinefunction(func):
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"""Return True if func is a decorated coroutine function."""
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return (getattr(func, '_is_coroutine', False) or
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_inspect_iscoroutinefunction(func))
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_COROUTINE_TYPES = (types.GeneratorType, CoroWrapper)
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if _CoroutineABC is not None:
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_COROUTINE_TYPES += (_CoroutineABC,)
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def iscoroutine(obj):
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"""Return True if obj is a coroutine object."""
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return isinstance(obj, _COROUTINE_TYPES)
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def _format_coroutine(coro):
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assert iscoroutine(coro)
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if isinstance(coro, CoroWrapper):
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func = coro.func
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else:
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func = coro
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coro_name = events._format_callback(func, ())
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filename = coro.gi_code.co_filename
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if (isinstance(coro, CoroWrapper)
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and not inspect.isgeneratorfunction(coro.func)):
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filename, lineno = events._get_function_source(coro.func)
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if coro.gi_frame is None:
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coro_repr = ('%s done, defined at %s:%s'
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% (coro_name, filename, lineno))
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else:
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coro_repr = ('%s running, defined at %s:%s'
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% (coro_name, filename, lineno))
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elif coro.gi_frame is not None:
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lineno = coro.gi_frame.f_lineno
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coro_repr = ('%s running at %s:%s'
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% (coro_name, filename, lineno))
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else:
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lineno = coro.gi_code.co_firstlineno
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coro_repr = ('%s done, defined at %s:%s'
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% (coro_name, filename, lineno))
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return coro_repr
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