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45b55e23d3
There's a frequent idiom I noticed where an iterable is split up into a number of chunks/batches. Unfortunately that method does not work with iterators like dict.keys() in python3. This implementation works with iterators. Signed-off-by: Adrian Tschira <nota@notafile.com>
100 lines
3.0 KiB
Python
100 lines
3.0 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright 2014-2016 OpenMarket Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from synapse.util.logcontext import PreserveLoggingContext
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from twisted.internet import defer, reactor, task
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import time
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import logging
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from itertools import islice
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logger = logging.getLogger(__name__)
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def unwrapFirstError(failure):
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# defer.gatherResults and DeferredLists wrap failures.
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failure.trap(defer.FirstError)
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return failure.value.subFailure
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class Clock(object):
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"""A small utility that obtains current time-of-day so that time may be
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mocked during unit-tests.
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TODO(paul): Also move the sleep() functionality into it
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"""
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def time(self):
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"""Returns the current system time in seconds since epoch."""
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return time.time()
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def time_msec(self):
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"""Returns the current system time in miliseconds since epoch."""
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return int(self.time() * 1000)
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def looping_call(self, f, msec):
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"""Call a function repeatedly.
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Waits `msec` initially before calling `f` for the first time.
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Args:
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f(function): The function to call repeatedly.
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msec(float): How long to wait between calls in milliseconds.
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"""
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call = task.LoopingCall(f)
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call.start(msec / 1000.0, now=False)
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return call
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def call_later(self, delay, callback, *args, **kwargs):
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"""Call something later
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Args:
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delay(float): How long to wait in seconds.
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callback(function): Function to call
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*args: Postional arguments to pass to function.
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**kwargs: Key arguments to pass to function.
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"""
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def wrapped_callback(*args, **kwargs):
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with PreserveLoggingContext():
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callback(*args, **kwargs)
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with PreserveLoggingContext():
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return reactor.callLater(delay, wrapped_callback, *args, **kwargs)
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def cancel_call_later(self, timer, ignore_errs=False):
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try:
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timer.cancel()
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except Exception:
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if not ignore_errs:
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raise
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def batch_iter(iterable, size):
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"""batch an iterable up into tuples with a maximum size
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Args:
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iterable (iterable): the iterable to slice
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size (int): the maximum batch size
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Returns:
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an iterator over the chunks
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"""
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# make sure we can deal with iterables like lists too
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sourceiter = iter(iterable)
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# call islice until it returns an empty tuple
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return iter(lambda: tuple(islice(sourceiter, size)), ())
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