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raise ValueError('step must be non-zero') |
if start is None: |
start, stop = 0.0, stop * 1.0 |
else: |
# swap when all args are used |
stop, start = start * 1.0, stop * 1.0 |
cur = start |
while cur < stop: |
yield cur |
cur += step" |
4964,"def frange(stop, start=None, step=1.0): |
""""""A :func:`range` clone for float-based ranges. |
>>> frange(5) |
[0.0, 1.0, 2.0, 3.0, 4.0] |
>>> frange(6, step=1.25) |
[0.0, 1.25, 2.5, 3.75, 5.0] |
>>> frange(100.5, 101.5, 0.25) |
[100.5, 100.75, 101.0, 101.25] |
>>> frange(5, 0) |
[] |
>>> frange(5, 0, step=-1.25) |
[5.0, 3.75, 2.5, 1.25] |
"""""" |
if not step: |
raise ValueError('step must be non-zero') |
if start is None: |
start, stop = 0.0, stop * 1.0 |
else: |
# swap when all args are used |
stop, start = start * 1.0, stop * 1.0 |
count = int(math.ceil((stop - start) / step)) |
ret = [None] * count |
if not ret: |
return ret |
ret[0] = start |
for i in xrange(1, count): |
ret[i] = ret[i - 1] + step |
return ret" |
4965,"def backoff(start, stop, count=None, factor=2.0, jitter=False): |
""""""Returns a list of geometrically-increasing floating-point numbers, |
suitable for usage with `exponential backoff`_. Exactly like |
:func:`backoff_iter`, but without the ``'repeat'`` option for |
*count*. See :func:`backoff_iter` for more details. |
.. _exponential backoff: https://en.wikipedia.org/wiki/Exponential_backoff |
>>> backoff(1, 10) |
[1.0, 2.0, 4.0, 8.0, 10.0] |
"""""" |
if count == 'repeat': |
raise ValueError(""'repeat' supported in backoff_iter, not backoff"") |
return list(backoff_iter(start, stop, count=count, |
factor=factor, jitter=jitter))" |
4966,"def backoff_iter(start, stop, count=None, factor=2.0, jitter=False): |
""""""Generates a sequence of geometrically-increasing floats, suitable |
for usage with `exponential backoff`_. Starts with *start*, |
increasing by *factor* until *stop* is reached, optionally |
stopping iteration once *count* numbers are yielded. *factor* |
defaults to 2. In general retrying with properly-configured |
backoff creates a better-behaved component for a larger service |
ecosystem. |
.. _exponential backoff: https://en.wikipedia.org/wiki/Exponential_backoff |
>>> list(backoff_iter(1.0, 10.0, count=5)) |
[1.0, 2.0, 4.0, 8.0, 10.0] |
>>> list(backoff_iter(1.0, 10.0, count=8)) |
[1.0, 2.0, 4.0, 8.0, 10.0, 10.0, 10.0, 10.0] |
>>> list(backoff_iter(0.25, 100.0, factor=10)) |
[0.25, 2.5, 25.0, 100.0] |
A simplified usage example: |
.. code-block:: python |
for timeout in backoff_iter(0.25, 5.0): |
try: |
res = network_call() |
break |
except Exception as e: |
log(e) |
time.sleep(timeout) |
An enhancement for large-scale systems would be to add variation, |
or *jitter*, to timeout values. This is done to avoid a thundering |
herd on the receiving end of the network call. |
Finally, for *count*, the special value ``'repeat'`` can be passed to |
continue yielding indefinitely. |
Args: |
start (float): Positive number for baseline. |
stop (float): Positive number for maximum. |
count (int): Number of steps before stopping |
iteration. Defaults to the number of steps between *start* and |
*stop*. Pass the string, `'repeat'`, to continue iteration |
indefinitely. |
factor (float): Rate of exponential increase. Defaults to `2.0`, |
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