Initial commit

middleware/rate_limiter.py

@@ -0,0 +1,82 @@
+# middleware/rate_limiter.py
+from typing import Dict, Tuple
+from datetime import datetime, timedelta
+import logging
+from collections import defaultdict, deque
+
+logger = logging.getLogger(__name__)
+
+
+class RateLimiter:
+    """In-memory rate limiter using sliding window"""
+
+    def __init__(self):
+        # Dictionary to store request timestamps for each client
+        self.clients: Dict[str, deque] = defaultdict(lambda: deque())
+        self.cleanup_interval = 3600  # Clean up old entries every hour
+        self.last_cleanup = datetime.utcnow()
+
+    def allow_request(self, client_id: str, max_requests: int, window_seconds: int) -> bool:
+        """
+        Check if client is allowed to make a request
+        Uses sliding window algorithm
+        """
+        now = datetime.utcnow()
+        window_start = now - timedelta(seconds=window_seconds)
+
+        # Clean up old entries periodically
+        if (now - self.last_cleanup).seconds > self.cleanup_interval:
+            self._cleanup_old_entries()
+            self.last_cleanup = now
+
+        # Get client's request history
+        client_requests = self.clients[client_id]
+
+        # Remove requests outside the window
+        while client_requests and client_requests[0] < window_start:
+            client_requests.popleft()
+
+        # Check if under rate limit
+        if len(client_requests) < max_requests:
+            client_requests.append(now)
+            return True
+
+        logger.warning(f"Rate limit exceeded for client {client_id}: {len(client_requests)}/{max_requests}")
+        return False
+
+    def _cleanup_old_entries(self):
+        """Clean up old entries to prevent memory leaks"""
+        cutoff_time = datetime.utcnow() - timedelta(hours=24)
+
+        clients_to_remove = []
+        for client_id, requests in self.clients.items():
+            # Remove old requests
+            while requests and requests[0] < cutoff_time:
+                requests.popleft()
+
+            # Mark empty clients for removal
+            if not requests:
+                clients_to_remove.append(client_id)
+
+        # Remove empty clients
+        for client_id in clients_to_remove:
+            del self.clients[client_id]
+
+        logger.info(f"Rate limiter cleanup completed. Removed {len(clients_to_remove)} inactive clients")
+
+    def get_client_stats(self, client_id: str) -> Dict[str, int]:
+        """Get statistics for a specific client"""
+        client_requests = self.clients.get(client_id, deque())
+
+        now = datetime.utcnow()
+        hour_ago = now - timedelta(hours=1)
+        day_ago = now - timedelta(days=1)
+
+        requests_last_hour = sum(1 for req_time in client_requests if req_time > hour_ago)
+        requests_last_day = sum(1 for req_time in client_requests if req_time > day_ago)
+
+        return {
+            "requests_last_hour": requests_last_hour,
+            "requests_last_day": requests_last_day,
+            "total_tracked_requests": len(client_requests)
+        }