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| Dir : //proc/self/root/opt/saltstack/salt/lib/python3.10/site-packages/tempora/timing.py |
import datetime
import functools
import numbers
import time
import collections.abc
import contextlib
import jaraco.functools
class Stopwatch:
"""
A simple stopwatch which starts automatically.
>>> w = Stopwatch()
>>> _1_sec = datetime.timedelta(seconds=1)
>>> w.split() < _1_sec
True
>>> import time
>>> time.sleep(1.0)
>>> w.split() >= _1_sec
True
>>> w.stop() >= _1_sec
True
>>> w.reset()
>>> w.start()
>>> w.split() < _1_sec
True
It should be possible to launch the Stopwatch in a context:
>>> with Stopwatch() as watch:
... assert isinstance(watch.split(), datetime.timedelta)
In that case, the watch is stopped when the context is exited,
so to read the elapsed time:
>>> watch.elapsed
datetime.timedelta(...)
>>> watch.elapsed.seconds
0
"""
def __init__(self):
self.reset()
self.start()
def reset(self):
self.elapsed = datetime.timedelta(0)
with contextlib.suppress(AttributeError):
del self.start_time
def start(self):
self.start_time = datetime.datetime.now(datetime.timezone.utc)
def stop(self):
stop_time = datetime.datetime.now(datetime.timezone.utc)
self.elapsed += stop_time - self.start_time
del self.start_time
return self.elapsed
def split(self):
local_duration = datetime.datetime.now(datetime.timezone.utc) - self.start_time
return self.elapsed + local_duration
# context manager support
def __enter__(self):
self.start()
return self
def __exit__(self, exc_type, exc_value, traceback):
self.stop()
class IntervalGovernor:
"""
Decorate a function to only allow it to be called once per
min_interval. Otherwise, it returns None.
>>> gov = IntervalGovernor(30)
>>> gov.min_interval.total_seconds()
30.0
"""
def __init__(self, min_interval):
if isinstance(min_interval, numbers.Number):
min_interval = datetime.timedelta(seconds=min_interval)
self.min_interval = min_interval
self.last_call = None
def decorate(self, func):
@functools.wraps(func)
def wrapper(*args, **kwargs):
allow = not self.last_call or self.last_call.split() > self.min_interval
if allow:
self.last_call = Stopwatch()
return func(*args, **kwargs)
return wrapper
__call__ = decorate
class Timer(Stopwatch):
"""
Watch for a target elapsed time.
>>> t = Timer(0.1)
>>> t.expired()
False
>>> __import__('time').sleep(0.15)
>>> t.expired()
True
"""
def __init__(self, target=float('Inf')):
self.target = self._accept(target)
super().__init__()
@staticmethod
def _accept(target):
"""
Accept None or ∞ or datetime or numeric for target
>>> Timer._accept(datetime.timedelta(seconds=30))
30.0
>>> Timer._accept(None)
inf
"""
if isinstance(target, datetime.timedelta):
target = target.total_seconds()
if target is None:
# treat None as infinite target
target = float('Inf')
return target
def expired(self):
return self.split().total_seconds() > self.target
class BackoffDelay(collections.abc.Iterator):
"""
Exponential backoff delay.
Useful for defining delays between retries. Consider for use
with ``jaraco.functools.retry_call`` as the cleanup.
Default behavior has no effect; a delay or jitter must
be supplied for the call to be non-degenerate.
>>> bd = BackoffDelay()
>>> bd()
>>> bd()
The following instance will delay 10ms for the first call,
20ms for the second, etc.
>>> bd = BackoffDelay(delay=0.01, factor=2)
>>> bd()
>>> bd()
Inspect and adjust the state of the delay anytime.
>>> bd.delay
0.04
>>> bd.delay = 0.01
Set limit to prevent the delay from exceeding bounds.
>>> bd = BackoffDelay(delay=0.01, factor=2, limit=0.015)
>>> bd()
>>> bd.delay
0.015
To reset the backoff, simply call ``.reset()``:
>>> bd.reset()
>>> bd.delay
0.01
Iterate on the object to retrieve/advance the delay values.
>>> next(bd)
0.01
>>> next(bd)
0.015
>>> import itertools
>>> tuple(itertools.islice(bd, 3))
(0.015, 0.015, 0.015)
Limit may be a callable taking a number and returning
the limited number.
>>> at_least_one = lambda n: max(n, 1)
>>> bd = BackoffDelay(delay=0.01, factor=2, limit=at_least_one)
>>> next(bd)
0.01
>>> next(bd)
1
Pass a jitter to add or subtract seconds to the delay.
>>> bd = BackoffDelay(jitter=0.01)
>>> next(bd)
0
>>> next(bd)
0.01
Jitter may be a callable. To supply a non-deterministic jitter
between -0.5 and 0.5, consider:
>>> import random
>>> jitter=functools.partial(random.uniform, -0.5, 0.5)
>>> bd = BackoffDelay(jitter=jitter)
>>> next(bd)
0
>>> 0 <= next(bd) <= 0.5
True
"""
delay = 0
factor = 1
"Multiplier applied to delay"
jitter = 0
"Number or callable returning extra seconds to add to delay"
@jaraco.functools.save_method_args
def __init__(self, delay=0, factor=1, limit=float('inf'), jitter=0):
self.delay = delay
self.factor = factor
if isinstance(limit, numbers.Number):
limit_ = limit
def limit(n):
return max(0, min(limit_, n))
self.limit = limit
if isinstance(jitter, numbers.Number):
jitter_ = jitter
def jitter():
return jitter_
self.jitter = jitter
def __call__(self):
time.sleep(next(self))
def __next__(self):
delay = self.delay
self.bump()
return delay
def __iter__(self):
return self
def bump(self):
self.delay = self.limit(self.delay * self.factor + self.jitter())
def reset(self):
saved = self._saved___init__
self.__init__(*saved.args, **saved.kwargs)