185 lines
6.5 KiB
Python
185 lines
6.5 KiB
Python
# Copyright (c) 2009-2010 Denis Bilenko, denis.bilenko at gmail com
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# Copyright (c) 2010 Eventlet Contributors (see AUTHORS)
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# and licensed under the MIT license:
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#
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# Permission is hereby granted, free of charge, to any person obtaining a copy
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# of this software and associated documentation files (the "Software"), to deal
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# in the Software without restriction, including without limitation the rights
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# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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# copies of the Software, and to permit persons to whom the Software is
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# furnished to do so, subject to the following conditions:
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#
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# The above copyright notice and this permission notice shall be included in
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# all copies or substantial portions of the Software.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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# THE SOFTWARE.
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import functools
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import inspect
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import eventlet
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from eventlet.support import greenlets as greenlet
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from eventlet.hubs import get_hub
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__all__ = ['Timeout', 'with_timeout', 'wrap_is_timeout', 'is_timeout']
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_MISSING = object()
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# deriving from BaseException so that "except Exception as e" doesn't catch
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# Timeout exceptions.
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class Timeout(BaseException):
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"""Raises *exception* in the current greenthread after *timeout* seconds.
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When *exception* is omitted or ``None``, the :class:`Timeout` instance
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itself is raised. If *seconds* is None, the timer is not scheduled, and is
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only useful if you're planning to raise it directly.
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Timeout objects are context managers, and so can be used in with statements.
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When used in a with statement, if *exception* is ``False``, the timeout is
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still raised, but the context manager suppresses it, so the code outside the
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with-block won't see it.
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"""
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def __init__(self, seconds=None, exception=None):
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self.seconds = seconds
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self.exception = exception
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self.timer = None
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self.start()
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def start(self):
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"""Schedule the timeout. This is called on construction, so
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it should not be called explicitly, unless the timer has been
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canceled."""
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assert not self.pending, \
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'%r is already started; to restart it, cancel it first' % self
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if self.seconds is None: # "fake" timeout (never expires)
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self.timer = None
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elif self.exception is None or isinstance(self.exception, bool): # timeout that raises self
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self.timer = get_hub().schedule_call_global(
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self.seconds, greenlet.getcurrent().throw, self)
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else: # regular timeout with user-provided exception
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self.timer = get_hub().schedule_call_global(
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self.seconds, greenlet.getcurrent().throw, self.exception)
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return self
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@property
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def pending(self):
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"""True if the timeout is scheduled to be raised."""
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if self.timer is not None:
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return self.timer.pending
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else:
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return False
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def cancel(self):
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"""If the timeout is pending, cancel it. If not using
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Timeouts in ``with`` statements, always call cancel() in a
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``finally`` after the block of code that is getting timed out.
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If not canceled, the timeout will be raised later on, in some
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unexpected section of the application."""
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if self.timer is not None:
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self.timer.cancel()
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self.timer = None
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def __repr__(self):
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classname = self.__class__.__name__
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if self.pending:
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pending = ' pending'
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else:
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pending = ''
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if self.exception is None:
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exception = ''
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else:
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exception = ' exception=%r' % self.exception
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return '<%s at %s seconds=%s%s%s>' % (
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classname, hex(id(self)), self.seconds, exception, pending)
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def __str__(self):
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"""
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>>> raise Timeout # doctest: +IGNORE_EXCEPTION_DETAIL
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Traceback (most recent call last):
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...
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Timeout
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"""
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if self.seconds is None:
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return ''
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if self.seconds == 1:
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suffix = ''
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else:
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suffix = 's'
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if self.exception is None or self.exception is True:
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return '%s second%s' % (self.seconds, suffix)
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elif self.exception is False:
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return '%s second%s (silent)' % (self.seconds, suffix)
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else:
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return '%s second%s (%s)' % (self.seconds, suffix, self.exception)
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def __enter__(self):
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if self.timer is None:
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self.start()
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return self
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def __exit__(self, typ, value, tb):
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self.cancel()
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if value is self and self.exception is False:
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return True
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@property
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def is_timeout(self):
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return True
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def with_timeout(seconds, function, *args, **kwds):
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"""Wrap a call to some (yielding) function with a timeout; if the called
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function fails to return before the timeout, cancel it and return a flag
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value.
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"""
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timeout_value = kwds.pop("timeout_value", _MISSING)
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timeout = Timeout(seconds)
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try:
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try:
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return function(*args, **kwds)
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except Timeout as ex:
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if ex is timeout and timeout_value is not _MISSING:
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return timeout_value
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raise
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finally:
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timeout.cancel()
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def wrap_is_timeout(base):
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'''Adds `.is_timeout=True` attribute to objects returned by `base()`.
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When `base` is class, attribute is added as read-only property. Returns `base`.
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Otherwise, it returns a function that sets attribute on result of `base()` call.
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Wrappers make best effort to be transparent.
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'''
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if inspect.isclass(base):
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base.is_timeout = property(lambda _: True)
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return base
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@functools.wraps(base)
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def fun(*args, **kwargs):
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ex = base(*args, **kwargs)
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ex.is_timeout = True
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return ex
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return fun
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if isinstance(__builtins__, dict): # seen when running tests on py310, but HOW??
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_timeout_err = __builtins__.get('TimeoutError', Timeout)
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else:
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_timeout_err = getattr(__builtins__, 'TimeoutError', Timeout)
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def is_timeout(obj):
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return bool(getattr(obj, 'is_timeout', False)) or isinstance(obj, _timeout_err)
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