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"""Provides utilities for pacing actions.""" |
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import asyncio |
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import logging |
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import time |
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import limits.aio.strategies |
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import limits.strategies |
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from limits import RateLimitItem, parse |
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from limits.storage import storage_from_string |
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LOG = logging.getLogger(__name__) |
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available_strategies = { |
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"fixed_window": ( |
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limits.strategies.FixedWindowRateLimiter, |
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limits.aio.strategies.FixedWindowRateLimiter, |
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), |
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# "elastic_window": ( |
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# limits.strategies.FixedWindowElasticExpiryRateLimiter, |
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# limits.aio.strategies.FixedWindowElasticExpiryRateLimiter, |
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# ), |
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} |
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class NoSuchActionError(BaseException): |
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""" |
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Exception for trying to use actions that aren't configured. |
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Not intended to be caught by NApps. |
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""" |
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class Pacer: |
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"""Class for controlling the rate at which actions are executed.""" |
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sync_strategies: dict[str, limits.strategies.RateLimiter] |
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async_strategies: dict[str, limits.aio.strategies.RateLimiter] |
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pace_config: dict[str, tuple[str, RateLimitItem]] |
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def __init__(self, storage_uri): |
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# Initialize dicts |
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self.sync_strategies = {} |
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self.async_strategies = {} |
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self.pace_config = {} |
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# Acquire storage |
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sync_storage = storage_from_string(storage_uri) |
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async_storage = storage_from_string(f"async+{storage_uri}") |
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# Populate strategies |
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for strat_name, strat_pair in available_strategies.items(): |
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sync_strat_type, async_strat_type = strat_pair |
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self.sync_strategies[strat_name] = sync_strat_type(sync_storage) |
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self.async_strategies[strat_name] = async_strat_type(async_storage) |
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def inject_config(self, config: dict[str, dict]): |
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""" |
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Inject settings for pacing |
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""" |
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# Regenerate update dict |
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next_config = { |
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key: ( |
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value.get('strategy', 'fixed_window'), |
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parse(value['pace']) |
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) |
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for key, value in config.items() |
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} |
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# Validate |
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for action, (strat, _) in next_config.items(): |
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if strat not in available_strategies: |
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raise ValueError( |
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f"Strategy ({strat}) for action ({action}) not valid" |
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) |
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LOG.info("Added pace for action %s", action) |
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# Apply |
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self.pace_config.update( |
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next_config |
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) |
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async def ahit(self, action_name: str, *keys): |
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""" |
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Asynchronous variant of `hit`. |
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This can be called from the serving thread safely. |
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""" |
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if action_name not in self.pace_config: |
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raise NoSuchActionError( |
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f"`{action_name}` has not been configured yet" |
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) |
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strat, pace = self.pace_config[action_name] |
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identifiers = pace, action_name, *keys |
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strategy = self.async_strategies[strat] |
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while not await strategy.hit(*identifiers): |
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window_reset, _ = await strategy.get_window_stats( |
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*identifiers |
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) |
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sleep_time = window_reset - time.time() |
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await asyncio.sleep(sleep_time) |
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def hit(self, action_name: str, *keys): |
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""" |
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Pace execution, based on the pacing config for the given `action_name`. |
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Keys can be included to allow multiple objects |
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to be be paced separately on the same action. |
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This should not be called from the same thread serving |
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the pacing. |
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""" |
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if action_name not in self.pace_config: |
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raise NoSuchActionError( |
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f"`{action_name}` has not been configured yet" |
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) |
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strat, pace = self.pace_config[action_name] |
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identifiers = pace, action_name, *keys |
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strategy = self.sync_strategies[strat] |
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while not strategy.hit(*identifiers): |
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window_reset, _ = strategy.get_window_stats( |
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*identifiers |
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) |
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sleep_time = window_reset - time.time() |
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if sleep_time <= 0: |
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continue |
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time.sleep(sleep_time) |
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class PacerWrapper: |
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""" |
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Applies a namespace to various operations related to pacing. |
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""" |
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namespace: str |
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pacer: Pacer |
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def __init__(self, namespace: str, pacer: Pacer): |
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self.namespace = namespace |
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self.pacer = pacer |
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def inject_config(self, napp_config: dict): |
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""" |
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Inject namespace specific settings for pacing |
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""" |
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self.pacer.inject_config( |
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{ |
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self._localized_key(key): value |
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for key, value in napp_config.items() |
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} |
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) |
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def hit(self, action_name: str, *keys): |
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""" |
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Asynchronous variant of `hit`. |
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This can be called from the serving thread safely. |
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""" |
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return self.pacer.hit( |
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self._localized_key(action_name), |
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*keys |
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) |
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async def ahit(self, action_name: str, *keys): |
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""" |
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Pace execution, based on the pacing config for the given `action_name`. |
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Keys can be included to allow multiple objects |
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to be be paced separately on the same action. |
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This should not be called from the same thread serving |
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the pacing. |
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""" |
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return await self.pacer.ahit( |
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self._localized_key(action_name), |
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*keys |
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) |
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def _localized_key(self, key): |
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return f"{self.namespace}.{key}" |
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kytos-ng /
kytos
