Odysseus v1.0

src/rate_limiter.py

@@ -0,0 +1,49 @@
+# src/rate_limiter.py
+"""Generic in-memory rate limiter — sliding window, keyed by IP."""
+
+import threading
+import time
+from typing import Dict, List
+
+
+class RateLimiter:
+    """Sliding-window rate limiter.
+
+    Usage:
+        limiter = RateLimiter(max_requests=5, window_seconds=60)
+        if not limiter.check(ip):
+            raise HTTPException(429, "Too many requests")
+    """
+
+    def __init__(self, max_requests: int, window_seconds: int):
+        self.max_requests = max_requests
+        self.window = window_seconds
+        self._log: Dict[str, List[float]] = {}
+        self._lock = threading.Lock()
+        self._last_cleanup = time.monotonic()
+        self._cleanup_interval = max(window_seconds * 2, 120)
+
+    def check(self, key: str) -> bool:
+        """Return True if the request is allowed, False if rate-limited."""
+        now = time.monotonic()
+        with self._lock:
+            self._maybe_cleanup(now)
+            timestamps = self._log.get(key, [])
+            cutoff = now - self.window
+            timestamps = [t for t in timestamps if t > cutoff]
+            if len(timestamps) >= self.max_requests:
+                self._log[key] = timestamps
+                return False
+            timestamps.append(now)
+            self._log[key] = timestamps
+            return True
+
+    def _maybe_cleanup(self, now: float) -> None:
+        """Periodically purge stale entries."""
+        if now - self._last_cleanup < self._cleanup_interval:
+            return
+        self._last_cleanup = now
+        cutoff = now - self.window
+        stale = [k for k, v in self._log.items() if not v or v[-1] <= cutoff]
+        for k in stale:
+            del self._log[k]