---

bucket.py

"""This module implements token buckets used for client side throttling.""" import threading import time from botocore.exceptions import CapacityNotAvailableError class Clock: def __init__(self): pass def sleep(self, amount): time.sleep(amount) def current_time(self): return time.time() class TokenBucket: _MIN_RATE = 0.5 def __init__(self, max_rate, clock, min_rate=_MIN_RATE): self._fill_rate = None self._max_capacity = None self._current_capacity = 0 self._clock = clock self._last_timestamp = None self._min_rate = min_rate self._lock = threading.Lock() self._new_fill_rate_condition = threading.Condition(self._lock) self.max_rate = max_rate @property def max_rate(self): return self._fill_rate @max_rate.setter def max_rate(self, value): with self._new_fill_rate_condition: # Before we can change the rate we need to fill any pending # tokens we might have based on the current rate. If we don't # do this it means everything since the last recorded timestamp # will accumulate at the rate we're about to set which isn't # correct. self._refill() self._fill_rate = max(value, self._min_rate) if value >= 1: self._max_capacity = value else: self._max_capacity = 1 # If we're scaling down, we also can't have a capacity that's # more than our max_capacity. self._current_capacity = min( self._current_capacity, self._max_capacity ) self._new_fill_rate_condition.notify() @property def max_capacity(self): return self._max_capacity @property def available_capacity(self): return self._current_capacity def acquire(self, amount=1, block=True): """Acquire token or return amount of time until next token available. If block is True, then this method will block until there's sufficient capacity to acquire the desired amount. If block is False, then this method will return True is capacity was successfully acquired, False otherwise. """ with self._new_fill_rate_condition: return self._acquire(amount=amount, block=block) def _acquire(self, amount, block): self._refill() if amount <= self._current_capacity: self._current_capacity -= amount return True else: if not block: raise CapacityNotAvailableError() # Not enough capacity. sleep_amount = self._sleep_amount(amount) while sleep_amount > 0: # Until python3.2, wait() always returned None so we can't # tell if a timeout occurred waiting on the cond var. # Because of this we'll unconditionally call _refill(). # The downside to this is that we were waken up via # a notify(), we're calling unnecessarily calling _refill() an # extra time. self._new_fill_rate_condition.wait(sleep_amount) self._refill() sleep_amount = self._sleep_amount(amount) self._current_capacity -= amount return True def _sleep_amount(self, amount): return (amount - self._current_capacity) / self._fill_rate def _refill(self): timestamp = self._clock.current_time() if self._last_timestamp is None: self._last_timestamp = timestamp return current_capacity = self._current_capacity fill_amount = (timestamp - self._last_timestamp) * self._fill_rate new_capacity = min(self._max_capacity, current_capacity + fill_amount) self._current_capacity = new_capacity self._last_timestamp = timestamp

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docroot: /var/www/469ed2f6-4d4b-4a8a-9f5e-ee4ef04d3bc8/public_html

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curdir: /usr/lib/python3/dist-packages/botocore/retries

	.		4096
	..		4096
X	__init__.py		121
	__pycache__		4096
X	adaptive.py		4207
X	base.py		797
X	bucket.py		3993
X	quota.py		1939
X	special.py		1663
X	standard.py		19974
X	throttling.py		1779