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42 lines
1.1 KiB
Python
42 lines
1.1 KiB
Python
"""
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Tiny in-memory rate limiter suitable for single-process development servers.
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"""
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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, Tuple
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@dataclass
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class RateLimitDecision:
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allowed: bool
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retry_after: float
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class SlidingWindowRateLimiter:
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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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