mirror of https://github.com/python/cpython
612 lines
19 KiB
Python
612 lines
19 KiB
Python
"""Event loop and event loop policy."""
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__all__ = ['AbstractEventLoopPolicy',
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'AbstractEventLoop', 'AbstractServer',
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'Handle', 'TimerHandle',
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'get_event_loop_policy', 'set_event_loop_policy',
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'get_event_loop', 'set_event_loop', 'new_event_loop',
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'get_child_watcher', 'set_child_watcher',
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]
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import functools
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import inspect
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import reprlib
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import socket
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import subprocess
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import sys
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import threading
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import traceback
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from asyncio import compat
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def _get_function_source(func):
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if compat.PY34:
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func = inspect.unwrap(func)
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elif hasattr(func, '__wrapped__'):
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func = func.__wrapped__
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if inspect.isfunction(func):
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code = func.__code__
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return (code.co_filename, code.co_firstlineno)
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if isinstance(func, functools.partial):
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return _get_function_source(func.func)
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if compat.PY34 and isinstance(func, functools.partialmethod):
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return _get_function_source(func.func)
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return None
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def _format_args(args):
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"""Format function arguments.
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Special case for a single parameter: ('hello',) is formatted as ('hello').
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"""
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# use reprlib to limit the length of the output
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args_repr = reprlib.repr(args)
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if len(args) == 1 and args_repr.endswith(',)'):
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args_repr = args_repr[:-2] + ')'
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return args_repr
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def _format_callback(func, args, suffix=''):
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if isinstance(func, functools.partial):
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if args is not None:
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suffix = _format_args(args) + suffix
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return _format_callback(func.func, func.args, suffix)
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if hasattr(func, '__qualname__'):
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func_repr = getattr(func, '__qualname__')
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elif hasattr(func, '__name__'):
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func_repr = getattr(func, '__name__')
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else:
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func_repr = repr(func)
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if args is not None:
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func_repr += _format_args(args)
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if suffix:
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func_repr += suffix
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return func_repr
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def _format_callback_source(func, args):
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func_repr = _format_callback(func, args)
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source = _get_function_source(func)
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if source:
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func_repr += ' at %s:%s' % source
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return func_repr
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class Handle:
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"""Object returned by callback registration methods."""
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__slots__ = ('_callback', '_args', '_cancelled', '_loop',
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'_source_traceback', '_repr', '__weakref__')
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def __init__(self, callback, args, loop):
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assert not isinstance(callback, Handle), 'A Handle is not a callback'
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self._loop = loop
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self._callback = callback
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self._args = args
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self._cancelled = False
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self._repr = None
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if self._loop.get_debug():
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self._source_traceback = traceback.extract_stack(sys._getframe(1))
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else:
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self._source_traceback = None
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def _repr_info(self):
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info = [self.__class__.__name__]
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if self._cancelled:
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info.append('cancelled')
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if self._callback is not None:
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info.append(_format_callback_source(self._callback, self._args))
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if self._source_traceback:
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frame = self._source_traceback[-1]
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info.append('created at %s:%s' % (frame[0], frame[1]))
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return info
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def __repr__(self):
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if self._repr is not None:
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return self._repr
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info = self._repr_info()
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return '<%s>' % ' '.join(info)
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def cancel(self):
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if not self._cancelled:
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self._cancelled = True
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if self._loop.get_debug():
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# Keep a representation in debug mode to keep callback and
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# parameters. For example, to log the warning
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# "Executing <Handle...> took 2.5 second"
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self._repr = repr(self)
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self._callback = None
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self._args = None
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def _run(self):
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try:
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self._callback(*self._args)
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except Exception as exc:
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cb = _format_callback_source(self._callback, self._args)
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msg = 'Exception in callback {}'.format(cb)
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context = {
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'message': msg,
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'exception': exc,
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'handle': self,
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}
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if self._source_traceback:
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context['source_traceback'] = self._source_traceback
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self._loop.call_exception_handler(context)
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self = None # Needed to break cycles when an exception occurs.
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class TimerHandle(Handle):
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"""Object returned by timed callback registration methods."""
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__slots__ = ['_scheduled', '_when']
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def __init__(self, when, callback, args, loop):
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assert when is not None
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super().__init__(callback, args, loop)
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if self._source_traceback:
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del self._source_traceback[-1]
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self._when = when
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self._scheduled = False
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def _repr_info(self):
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info = super()._repr_info()
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pos = 2 if self._cancelled else 1
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info.insert(pos, 'when=%s' % self._when)
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return info
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def __hash__(self):
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return hash(self._when)
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def __lt__(self, other):
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return self._when < other._when
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def __le__(self, other):
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if self._when < other._when:
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return True
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return self.__eq__(other)
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def __gt__(self, other):
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return self._when > other._when
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def __ge__(self, other):
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if self._when > other._when:
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return True
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return self.__eq__(other)
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def __eq__(self, other):
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if isinstance(other, TimerHandle):
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return (self._when == other._when and
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self._callback == other._callback and
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self._args == other._args and
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self._cancelled == other._cancelled)
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return NotImplemented
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def __ne__(self, other):
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equal = self.__eq__(other)
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return NotImplemented if equal is NotImplemented else not equal
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def cancel(self):
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if not self._cancelled:
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self._loop._timer_handle_cancelled(self)
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super().cancel()
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class AbstractServer:
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"""Abstract server returned by create_server()."""
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def close(self):
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"""Stop serving. This leaves existing connections open."""
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return NotImplemented
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def wait_closed(self):
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"""Coroutine to wait until service is closed."""
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return NotImplemented
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class AbstractEventLoop:
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"""Abstract event loop."""
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# Running and stopping the event loop.
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def run_forever(self):
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"""Run the event loop until stop() is called."""
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raise NotImplementedError
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def run_until_complete(self, future):
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"""Run the event loop until a Future is done.
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Return the Future's result, or raise its exception.
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"""
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raise NotImplementedError
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def stop(self):
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"""Stop the event loop as soon as reasonable.
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Exactly how soon that is may depend on the implementation, but
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no more I/O callbacks should be scheduled.
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"""
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raise NotImplementedError
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def is_running(self):
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"""Return whether the event loop is currently running."""
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raise NotImplementedError
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def is_closed(self):
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"""Returns True if the event loop was closed."""
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raise NotImplementedError
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def close(self):
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"""Close the loop.
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The loop should not be running.
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This is idempotent and irreversible.
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No other methods should be called after this one.
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"""
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raise NotImplementedError
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# Methods scheduling callbacks. All these return Handles.
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def _timer_handle_cancelled(self, handle):
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"""Notification that a TimerHandle has been cancelled."""
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raise NotImplementedError
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def call_soon(self, callback, *args):
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return self.call_later(0, callback, *args)
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def call_later(self, delay, callback, *args):
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raise NotImplementedError
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def call_at(self, when, callback, *args):
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raise NotImplementedError
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def time(self):
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raise NotImplementedError
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# Method scheduling a coroutine object: create a task.
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def create_task(self, coro):
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raise NotImplementedError
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# Methods for interacting with threads.
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def call_soon_threadsafe(self, callback, *args):
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raise NotImplementedError
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def run_in_executor(self, executor, func, *args):
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raise NotImplementedError
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def set_default_executor(self, executor):
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raise NotImplementedError
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# Network I/O methods returning Futures.
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def getaddrinfo(self, host, port, *, family=0, type=0, proto=0, flags=0):
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raise NotImplementedError
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def getnameinfo(self, sockaddr, flags=0):
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raise NotImplementedError
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def create_connection(self, protocol_factory, host=None, port=None, *,
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ssl=None, family=0, proto=0, flags=0, sock=None,
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local_addr=None, server_hostname=None):
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raise NotImplementedError
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def create_server(self, protocol_factory, host=None, port=None, *,
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family=socket.AF_UNSPEC, flags=socket.AI_PASSIVE,
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sock=None, backlog=100, ssl=None, reuse_address=None):
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"""A coroutine which creates a TCP server bound to host and port.
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The return value is a Server object which can be used to stop
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the service.
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If host is an empty string or None all interfaces are assumed
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and a list of multiple sockets will be returned (most likely
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one for IPv4 and another one for IPv6). The host parameter can also be a
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sequence (e.g. list) of hosts to bind to.
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family can be set to either AF_INET or AF_INET6 to force the
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socket to use IPv4 or IPv6. If not set it will be determined
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from host (defaults to AF_UNSPEC).
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flags is a bitmask for getaddrinfo().
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sock can optionally be specified in order to use a preexisting
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socket object.
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backlog is the maximum number of queued connections passed to
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listen() (defaults to 100).
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ssl can be set to an SSLContext to enable SSL over the
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accepted connections.
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reuse_address tells the kernel to reuse a local socket in
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TIME_WAIT state, without waiting for its natural timeout to
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expire. If not specified will automatically be set to True on
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UNIX.
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"""
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raise NotImplementedError
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def create_unix_connection(self, protocol_factory, path, *,
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ssl=None, sock=None,
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server_hostname=None):
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raise NotImplementedError
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def create_unix_server(self, protocol_factory, path, *,
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sock=None, backlog=100, ssl=None):
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"""A coroutine which creates a UNIX Domain Socket server.
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The return value is a Server object, which can be used to stop
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the service.
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path is a str, representing a file systsem path to bind the
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server socket to.
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sock can optionally be specified in order to use a preexisting
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socket object.
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backlog is the maximum number of queued connections passed to
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listen() (defaults to 100).
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ssl can be set to an SSLContext to enable SSL over the
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accepted connections.
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"""
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raise NotImplementedError
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def create_datagram_endpoint(self, protocol_factory,
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local_addr=None, remote_addr=None, *,
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family=0, proto=0, flags=0):
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raise NotImplementedError
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# Pipes and subprocesses.
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def connect_read_pipe(self, protocol_factory, pipe):
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"""Register read pipe in event loop. Set the pipe to non-blocking mode.
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protocol_factory should instantiate object with Protocol interface.
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pipe is a file-like object.
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Return pair (transport, protocol), where transport supports the
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ReadTransport interface."""
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# The reason to accept file-like object instead of just file descriptor
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# is: we need to own pipe and close it at transport finishing
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# Can got complicated errors if pass f.fileno(),
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# close fd in pipe transport then close f and vise versa.
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raise NotImplementedError
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def connect_write_pipe(self, protocol_factory, pipe):
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"""Register write pipe in event loop.
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protocol_factory should instantiate object with BaseProtocol interface.
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Pipe is file-like object already switched to nonblocking.
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Return pair (transport, protocol), where transport support
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WriteTransport interface."""
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# The reason to accept file-like object instead of just file descriptor
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# is: we need to own pipe and close it at transport finishing
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# Can got complicated errors if pass f.fileno(),
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# close fd in pipe transport then close f and vise versa.
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raise NotImplementedError
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def subprocess_shell(self, protocol_factory, cmd, *, stdin=subprocess.PIPE,
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stdout=subprocess.PIPE, stderr=subprocess.PIPE,
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**kwargs):
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raise NotImplementedError
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def subprocess_exec(self, protocol_factory, *args, stdin=subprocess.PIPE,
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stdout=subprocess.PIPE, stderr=subprocess.PIPE,
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**kwargs):
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raise NotImplementedError
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# Ready-based callback registration methods.
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# The add_*() methods return None.
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# The remove_*() methods return True if something was removed,
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# False if there was nothing to delete.
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def add_reader(self, fd, callback, *args):
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raise NotImplementedError
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def remove_reader(self, fd):
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raise NotImplementedError
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def add_writer(self, fd, callback, *args):
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raise NotImplementedError
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def remove_writer(self, fd):
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raise NotImplementedError
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# Completion based I/O methods returning Futures.
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def sock_recv(self, sock, nbytes):
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raise NotImplementedError
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def sock_sendall(self, sock, data):
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raise NotImplementedError
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def sock_connect(self, sock, address):
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raise NotImplementedError
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def sock_accept(self, sock):
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raise NotImplementedError
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# Signal handling.
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def add_signal_handler(self, sig, callback, *args):
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raise NotImplementedError
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def remove_signal_handler(self, sig):
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raise NotImplementedError
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# Task factory.
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def set_task_factory(self, factory):
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raise NotImplementedError
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def get_task_factory(self):
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raise NotImplementedError
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# Error handlers.
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def set_exception_handler(self, handler):
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raise NotImplementedError
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def default_exception_handler(self, context):
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raise NotImplementedError
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def call_exception_handler(self, context):
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raise NotImplementedError
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# Debug flag management.
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def get_debug(self):
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raise NotImplementedError
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def set_debug(self, enabled):
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raise NotImplementedError
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class AbstractEventLoopPolicy:
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"""Abstract policy for accessing the event loop."""
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def get_event_loop(self):
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"""Get the event loop for the current context.
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Returns an event loop object implementing the BaseEventLoop interface,
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or raises an exception in case no event loop has been set for the
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current context and the current policy does not specify to create one.
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It should never return None."""
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raise NotImplementedError
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def set_event_loop(self, loop):
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"""Set the event loop for the current context to loop."""
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raise NotImplementedError
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def new_event_loop(self):
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"""Create and return a new event loop object according to this
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policy's rules. If there's need to set this loop as the event loop for
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the current context, set_event_loop must be called explicitly."""
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raise NotImplementedError
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# Child processes handling (Unix only).
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def get_child_watcher(self):
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"Get the watcher for child processes."
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raise NotImplementedError
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def set_child_watcher(self, watcher):
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"""Set the watcher for child processes."""
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raise NotImplementedError
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class BaseDefaultEventLoopPolicy(AbstractEventLoopPolicy):
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"""Default policy implementation for accessing the event loop.
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In this policy, each thread has its own event loop. However, we
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only automatically create an event loop by default for the main
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thread; other threads by default have no event loop.
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Other policies may have different rules (e.g. a single global
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event loop, or automatically creating an event loop per thread, or
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using some other notion of context to which an event loop is
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associated).
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"""
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_loop_factory = None
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class _Local(threading.local):
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_loop = None
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_set_called = False
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def __init__(self):
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self._local = self._Local()
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def get_event_loop(self):
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"""Get the event loop.
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This may be None or an instance of EventLoop.
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"""
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if (self._local._loop is None and
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not self._local._set_called and
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isinstance(threading.current_thread(), threading._MainThread)):
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self.set_event_loop(self.new_event_loop())
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if self._local._loop is None:
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raise RuntimeError('There is no current event loop in thread %r.'
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% threading.current_thread().name)
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return self._local._loop
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def set_event_loop(self, loop):
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"""Set the event loop."""
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self._local._set_called = True
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assert loop is None or isinstance(loop, AbstractEventLoop)
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self._local._loop = loop
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def new_event_loop(self):
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"""Create a new event loop.
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You must call set_event_loop() to make this the current event
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loop.
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"""
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return self._loop_factory()
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# Event loop policy. The policy itself is always global, even if the
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# policy's rules say that there is an event loop per thread (or other
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# notion of context). The default policy is installed by the first
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# call to get_event_loop_policy().
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_event_loop_policy = None
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# Lock for protecting the on-the-fly creation of the event loop policy.
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_lock = threading.Lock()
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def _init_event_loop_policy():
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global _event_loop_policy
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with _lock:
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if _event_loop_policy is None: # pragma: no branch
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from . import DefaultEventLoopPolicy
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_event_loop_policy = DefaultEventLoopPolicy()
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def get_event_loop_policy():
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"""Get the current event loop policy."""
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if _event_loop_policy is None:
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_init_event_loop_policy()
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return _event_loop_policy
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def set_event_loop_policy(policy):
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"""Set the current event loop policy.
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If policy is None, the default policy is restored."""
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global _event_loop_policy
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assert policy is None or isinstance(policy, AbstractEventLoopPolicy)
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_event_loop_policy = policy
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def get_event_loop():
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"""Equivalent to calling get_event_loop_policy().get_event_loop()."""
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return get_event_loop_policy().get_event_loop()
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def set_event_loop(loop):
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"""Equivalent to calling get_event_loop_policy().set_event_loop(loop)."""
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get_event_loop_policy().set_event_loop(loop)
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def new_event_loop():
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"""Equivalent to calling get_event_loop_policy().new_event_loop()."""
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return get_event_loop_policy().new_event_loop()
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def get_child_watcher():
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"""Equivalent to calling get_event_loop_policy().get_child_watcher()."""
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return get_event_loop_policy().get_child_watcher()
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def set_child_watcher(watcher):
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"""Equivalent to calling
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get_event_loop_policy().set_child_watcher(watcher)."""
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return get_event_loop_policy().set_child_watcher(watcher)
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