damccorm commented on code in PR #37135: URL: https://github.com/apache/beam/pull/37135#discussion_r2658436754
########## sdks/python/apache_beam/io/components/rate_limiter.py: ########## @@ -0,0 +1,225 @@ +# +# Licensed to the Apache Software Foundation (ASF) under one or more +# contributor license agreements. See the NOTICE file distributed with +# this work for additional information regarding copyright ownership. +# The ASF licenses this file to You under the Apache License, Version 2.0 +# (the "License"); you may not use this file except in compliance with +# the License. You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +# See the License for the specific language governing permissions and +# limitations under the License. +# + +""" +Rate Limiter classes for controlling access to external resources. +""" + +import abc +import logging +import random +import threading +import time +from typing import Dict +from typing import List + +import grpc +from envoy_data_plane.envoy.extensions.common.ratelimit.v3 import RateLimitDescriptor +from envoy_data_plane.envoy.extensions.common.ratelimit.v3 import RateLimitDescriptorEntry +from envoy_data_plane.envoy.service.ratelimit.v3 import RateLimitRequest +from envoy_data_plane.envoy.service.ratelimit.v3 import RateLimitResponse +from envoy_data_plane.envoy.service.ratelimit.v3 import RateLimitResponseCode + +from apache_beam.io.components import adaptive_throttler +from apache_beam.metrics import Metrics + +_LOGGER = logging.getLogger(__name__) + +_MAX_RETRIES = 5 +_RETRY_DELAY_SECONDS = 10 + + +class RateLimiter(abc.ABC): + """Abstract base class for RateLimiters.""" + def __init__(self, namespace: str = ""): + # Metrics collected from the RateLimiter + # Metric updates are thread safe + self.throttling_signaler = adaptive_throttler.ThrottlingSignaler( + namespace=namespace) + self.requests_counter = Metrics.counter(namespace, 'RatelimitRequestsTotal') + self.requests_allowed = Metrics.counter( + namespace, 'RatelimitRequestsAllowed') + self.requests_throttled = Metrics.counter( + namespace, 'RatelimitRequestsThrottled') + self.rpc_errors = Metrics.counter(namespace, 'RatelimitRpcErrors') + self.rpc_retries = Metrics.counter(namespace, 'RatelimitRpcRetries') + self.rpc_latency = Metrics.distribution(namespace, 'RatelimitRpcLatencyMs') + + @abc.abstractmethod + def throttle(self, **kwargs) -> bool: + """Check if request should be throttled. + + Args: + **kwargs: Keyword arguments specific to the RateLimiter implementation. + + Returns: + bool: True if the request is allowed, False if retries exceeded. + + Raises: + Exception: If an underlying infrastructure error occurs (e.g. RPC + failure). + """ + pass + + +class EnvoyRateLimiter(RateLimiter): + """ + Rate limiter implementation that uses an external Envoy Rate Limit Service. + """ + def __init__( + self, + service_address: str, + domain: str, + descriptors: List[Dict[str, str]], + timeout: float = 5.0, + block_until_allowed: bool = True, + retries: int = 3, + namespace: str = ""): + """ + Args: + service_address: Address of the Envoy RLS (e.g., 'localhost:8081'). + domain: The rate limit domain. + descriptors: List of descriptors (key-value pairs). + retries: Number of retries to attempt if rate limited, respected only if + block_until_allowed is False. + timeout: gRPC timeout in seconds. + block_until_allowed: If enabled blocks until RateLimiter gets + the token. + namespace: the namespace to use for logging and signaling + throttling is occurring. + """ + super().__init__(namespace=namespace) + + self.service_address = service_address + self.domain = domain + self.descriptors = descriptors + self.retries = retries + self.timeout = timeout + self.block_until_allowed = block_until_allowed + self._stub = None + self._lock = threading.Lock() + + class RateLimitServiceStub(object): + """ + Wrapper for gRPC stub to be compatible with envoy_data_plane messages. + + The envoy-data-plane package uses 'betterproto' which generates async stubs + for 'grpclib'. As Beam uses standard synchronous 'grpcio', + RateLimitServiceStub is a bridge class to use the betterproto Message types + (RateLimitRequest) with a standard grpcio Channel. + """ + def __init__(self, channel): + self.ShouldRateLimit = channel.unary_unary( + '/envoy.service.ratelimit.v3.RateLimitService/ShouldRateLimit', + request_serializer=RateLimitRequest.SerializeToString, + response_deserializer=RateLimitResponse.FromString, + ) + + def init_connection(self): + if self._stub is None: + # Acquire lock to safegaurd againest multiple DoFn threads sharing the + # same RateLimiter instance, which is the case when using Shared(). + with self._lock: + if self._stub is None: + channel = grpc.insecure_channel(self.service_address) + self._stub = EnvoyRateLimiter.RateLimitServiceStub(channel) + + def throttle(self, hits_added: int = 1) -> bool: + """Calls the Envoy RLS to check for rate limits. + + Args: + hits_added: Number of hits to add to the rate limit. + + Returns: + bool: True if the request is allowed, False if retries exceeded. + """ + self.init_connection() + + # execute thread-safe gRPC call + # Convert descriptors to proto format + proto_descriptors = [] + for d in self.descriptors: + entries = [] + for k, v in d.items(): + entries.append(RateLimitDescriptorEntry(key=k, value=v)) + proto_descriptors.append(RateLimitDescriptor(entries=entries)) + + request = RateLimitRequest( + domain=self.domain, + descriptors=proto_descriptors, + hits_addend=hits_added) + + self.requests_counter.inc() + attempt = 0 + throttled = False + while True: + if not self.block_until_allowed and attempt > self.retries: + break + + # retry loop + for retry_attempt in range(_MAX_RETRIES): + try: + start_time = time.time() + response = self._stub.ShouldRateLimit(request, timeout=self.timeout) + self.rpc_latency.update(int((time.time() - start_time) * 1000)) + break + except grpc.RpcError as e: + if retry_attempt == _MAX_RETRIES - 1: + _LOGGER.error( + "[EnvoyRateLimiter] ratelimit service call failed: %s", e) + self.rpc_errors.inc() + raise e + self.rpc_retries.inc() + _LOGGER.warning( + "[EnvoyRateLimiter] ratelimit service call failed, retrying: %s", + e) + time.sleep(_RETRY_DELAY_SECONDS) + + if response.overall_code == RateLimitResponseCode.OK: + self.requests_allowed.inc() + throttled = True + break + elif response.overall_code == RateLimitResponseCode.OVER_LIMIT: + self.requests_throttled.inc() + # Ratelimit exceeded, sleep for duration until reset and retry + # multiple rules can be set in the RLS config, so we need to find the + # max duration + sleep_s = 0.0 + if response.statuses: + for status in response.statuses: + if status.code == RateLimitResponseCode.OVER_LIMIT: + dur = status.duration_until_reset + # duration_until_reset is converted to timedelta by betterproto + val = dur.total_seconds() + if val > sleep_s: + sleep_s = val + + # Add 1% additive jitter to prevent thundering herd + jitter = random.uniform(0, 0.01 * sleep_s) + sleep_s += jitter + + _LOGGER.warning("[EnvoyRateLimiter] Throttled for %s seconds", sleep_s) + # signal throttled time to backend + self.throttling_signaler.signal_throttled(int(sleep_s)) Review Comment: I think we should probably fix this rounding -- This is an automated message from the Apache Git Service. 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