Source code for riprova.strategies.fibonacci

# -*- coding: utf-8 -*-
from ..backoff import Backoff
from ..constants import INT_ERROR, POS_ERROR

[docs]class FibonacciBackoff(Backoff): """ Implements a backoff policy based on Fibonacci sequence of numbers. The Fibonacci backoff policy can be configured with a custom initial sequence number value and maximum number of retries. This policy is similar to exponential backoff policy, which returns a delay that grows longer as you call `next()`. For more information, see: FibonacciBackoff is expected to run in a single-thread context. Arguments: retries (int): maximum number of retries. Use `0` for no limit. Defaults to `10`. initial (int): initial number for fibonacci series. Detaults to `1`. multiper (int): fibonacci series number time multiplier. Defaults to `1`. Raises: AssertionError: in case of invalid params. Usage:: @riprova.retry(backoff=riprova.FibonacciBackoff(retries=5)) def task(x): return x * x """ def __init__(self, retries=10, initial=1, multiplier=1): # Validate input params assert isinstance(retries, int), INT_ERROR.format('retries') assert isinstance(initial, int), INT_ERROR.format('initial') assert isinstance(multiplier, int), INT_ERROR.format('multiplier') assert retries >= 0, POS_ERROR.format('retries') assert initial >= 0, POS_ERROR.format('initial') assert multiplier >= 0, POS_ERROR.format('multiplier') self.prev = 0 self.retries = 0 self.current = initial or 1 self.initial = self.current self.max_retries = retries self.multiplier = multiplier @property def interval(self): """ Returns the next Fibonacci number in the series, multiplied by the current configured multiplier, typically `100`, for time seconds adjust. """ current = self.prev + self.current self.prev = self.current self.current = current return self.current * self.multiplier
[docs] def reset(self): """ Resets the current backoff state data. """ self.prev = 0 self.retries = 0 self.current = self.initial
[docs] def next(self): """ Returns the number of seconds to wait before the next try, otherwise returns `Backoff.STOP`, which indicates the max number of retry operations were reached. Returns: float: time to wait in seconds before the next try. """ # Verify we do not exceeded the max retries if self.max_retries > 0 and self.retries >= self.max_retries: return Backoff.STOP # Decrement pending retries attempts if self.max_retries > 0: self.retries += 1 # Return next interval according to Fibonacci series return self.interval