mirror of
https://github.com/bunny-lab-io/Borealis.git
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46 lines
1.3 KiB
Python
46 lines
1.3 KiB
Python
"""In-process rate limiting utilities for the Borealis Engine."""
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from __future__ import annotations
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import time
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from collections import deque
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from dataclasses import dataclass
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from threading import Lock
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from typing import Deque, Dict
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__all__ = ["RateLimitDecision", "SlidingWindowRateLimiter"]
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@dataclass(frozen=True, slots=True)
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class RateLimitDecision:
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"""Result of a rate limit check."""
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allowed: bool
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retry_after: float
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class SlidingWindowRateLimiter:
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"""Tiny in-memory sliding window limiter suitable for single-process use."""
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def __init__(self) -> None:
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self._buckets: Dict[str, Deque[float]] = {}
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self._lock = Lock()
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def check(self, key: str, limit: int, window_seconds: float) -> RateLimitDecision:
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now = time.monotonic()
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with self._lock:
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bucket = self._buckets.get(key)
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if bucket is None:
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bucket = deque()
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self._buckets[key] = bucket
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while bucket and now - bucket[0] > window_seconds:
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bucket.popleft()
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if len(bucket) >= limit:
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retry_after = max(0.0, window_seconds - (now - bucket[0]))
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return RateLimitDecision(False, retry_after)
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bucket.append(now)
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return RateLimitDecision(True, 0.0)
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