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