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##############################################################################
#
# Copyright (C) Zenoss, Inc. 2016, all rights reserved.
#
# This content is made available according to terms specified in
# License.zenoss under the directory where your Zenoss product is installed.
#
##############################################################################
from twisted.internet import defer, error, reactor
from twisted.python import failure
def with_timeout(fn, args=None, kwargs=None, seconds=None, exception_class=error.TimeoutError):
"""Execute asynchronous function fn(*args, **kwargs) with a timeout."""
return add_timeout(
deferred=fn(*args, **kwargs),
seconds=seconds,
exception_class=exception_class)
def add_timeout(deferred, seconds, exception_class=error.TimeoutError):
"""Return new Deferred that will errback exception_class after seconds."""
deferred_with_timeout = defer.Deferred()
def fire_timeout():
deferred.cancel()
if not deferred_with_timeout.called:
deferred_with_timeout.errback(exception_class())
delayed_timeout = reactor.callLater(seconds, fire_timeout)
def handle_result(result):
is_failure = isinstance(result, failure.Failure)
is_cancelled = is_failure and isinstance(result.value, defer.CancelledError)
if delayed_timeout.active():
# Cancel the timeout since a result came before it fired.
delayed_timeout.cancel()
elif is_cancelled:
# Don't propagate cancellations that we caused.
return
# Propagate remaining results.
if is_failure:
deferred_with_timeout.errback(result)
else:
deferred_with_timeout.callback(result)
deferred.addBoth(handle_result)
return deferred_with_timeout
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