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# -*- coding: utf-8 -*-
# Copyright 2014-2016 OpenMarket Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import logging
from itertools import islice
import attr
from twisted.internet import defer, task
from synapse.util.logcontext import PreserveLoggingContext
logger = logging.getLogger(__name__)
def unwrapFirstError(failure):
# defer.gatherResults and DeferredLists wrap failures.
failure.trap(defer.FirstError)
return failure.value.subFailure
@attr.s
class Clock(object):
"""
A Clock wraps a Twisted reactor and provides utilities on top of it.
Args:
reactor: The Twisted reactor to use.
"""
_reactor = attr.ib()
@defer.inlineCallbacks
def sleep(self, seconds):
d = defer.Deferred()
with PreserveLoggingContext():
self._reactor.callLater(seconds, d.callback, seconds)
res = yield d
defer.returnValue(res)
def time(self):
"""Returns the current system time in seconds since epoch."""
return self._reactor.seconds()
def time_msec(self):
"""Returns the current system time in miliseconds since epoch."""
return int(self.time() * 1000)
def looping_call(self, f, msec):
"""Call a function repeatedly.
Waits `msec` initially before calling `f` for the first time.
Args:
f(function): The function to call repeatedly.
msec(float): How long to wait between calls in milliseconds.
"""
call = task.LoopingCall(f)
call.clock = self._reactor
d = call.start(msec / 1000.0, now=False)
d.addErrback(
log_failure, "Looping call died", consumeErrors=False,
)
return call
def call_later(self, delay, callback, *args, **kwargs):
"""Call something later
Args:
delay(float): How long to wait in seconds.
callback(function): Function to call
*args: Postional arguments to pass to function.
**kwargs: Key arguments to pass to function.
"""
def wrapped_callback(*args, **kwargs):
with PreserveLoggingContext():
callback(*args, **kwargs)
with PreserveLoggingContext():
return self._reactor.callLater(delay, wrapped_callback, *args, **kwargs)
def cancel_call_later(self, timer, ignore_errs=False):
try:
timer.cancel()
except Exception:
if not ignore_errs:
raise
def batch_iter(iterable, size):
"""batch an iterable up into tuples with a maximum size
Args:
iterable (iterable): the iterable to slice
size (int): the maximum batch size
Returns:
an iterator over the chunks
"""
# make sure we can deal with iterables like lists too
sourceiter = iter(iterable)
# call islice until it returns an empty tuple
return iter(lambda: tuple(islice(sourceiter, size)), ())
def log_failure(failure, msg, consumeErrors=True):
"""Creates a function suitable for passing to `Deferred.addErrback` that
logs any failures that occur.
Args:
msg (str): Message to log
consumeErrors (bool): If true consumes the failure, otherwise passes
on down the callback chain
Returns:
func(Failure)
"""
logger.error(
msg,
exc_info=(
failure.type,
failure.value,
failure.getTracebackObject()
)
)
if not consumeErrors:
return failure
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