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"""Distributed rate limiting service using Redis"""
import time
from src.core import json_utils
from typing import Dict, Optional, Tuple
from datetime import datetime, timedelta
import redis.asyncio as redis
from redis.exceptions import RedisError
from src.core.config import settings
from src.core import get_logger
logger = get_logger(__name__)
class DistributedRateLimiter:
"""Distributed rate limiter using Redis with sliding window algorithm"""
def __init__(
self,
redis_url: Optional[str] = None,
requests_per_minute: int = 60,
requests_per_hour: int = 600,
requests_per_day: int = 10000,
burst_size: int = 10
):
self.redis_url = redis_url or settings.REDIS_URL
self.requests_per_minute = requests_per_minute
self.requests_per_hour = requests_per_hour
self.requests_per_day = requests_per_day
self.burst_size = burst_size
self._redis_client = None
async def get_redis(self) -> redis.Redis:
"""Get Redis client with lazy initialization"""
if self._redis_client is None:
self._redis_client = redis.from_url(
self.redis_url,
encoding="utf-8",
decode_responses=True,
socket_keepalive=True,
health_check_interval=30
)
return self._redis_client
async def is_allowed(
self,
identifier: str,
endpoint: Optional[str] = None
) -> Tuple[bool, Dict[str, any]]:
"""
Check if request is allowed using sliding window algorithm
Args:
identifier: Unique identifier (IP address or user ID)
endpoint: Optional endpoint for per-endpoint limits
Returns:
Tuple of (allowed, rate_info)
"""
try:
redis_client = await self.get_redis()
current_time = time.time()
# Create key prefix
key_prefix = f"rate_limit:{identifier}"
if endpoint:
key_prefix += f":{endpoint}"
# Keys for different windows
minute_key = f"{key_prefix}:minute"
hour_key = f"{key_prefix}:hour"
day_key = f"{key_prefix}:day"
burst_key = f"{key_prefix}:burst"
# Use pipeline for atomic operations
async with redis_client.pipeline() as pipe:
# Get current counts
pipe.zcount(minute_key, current_time - 60, current_time)
pipe.zcount(hour_key, current_time - 3600, current_time)
pipe.zcount(day_key, current_time - 86400, current_time)
pipe.get(burst_key)
results = await pipe.execute()
minute_count = results[0]
hour_count = results[1]
day_count = results[2]
burst_tokens = int(results[3] or self.burst_size)
# Check limits
if minute_count >= self.requests_per_minute:
return False, {
"reason": "minute_limit_exceeded",
"limit": self.requests_per_minute,
"count": minute_count,
"reset_in": 60 - (current_time % 60)
}
if hour_count >= self.requests_per_hour:
return False, {
"reason": "hour_limit_exceeded",
"limit": self.requests_per_hour,
"count": hour_count,
"reset_in": 3600 - (current_time % 3600)
}
if day_count >= self.requests_per_day:
return False, {
"reason": "day_limit_exceeded",
"limit": self.requests_per_day,
"count": day_count,
"reset_in": 86400 - (current_time % 86400)
}
# Check burst limit
if burst_tokens <= 0:
return False, {
"reason": "burst_limit_exceeded",
"limit": self.burst_size,
"count": 0,
"reset_in": 1
}
# Request allowed - update counts
request_id = f"{current_time}:{identifier}"
async with redis_client.pipeline() as pipe:
# Add to sliding windows
pipe.zadd(minute_key, {request_id: current_time})
pipe.zadd(hour_key, {request_id: current_time})
pipe.zadd(day_key, {request_id: current_time})
# Update burst tokens
pipe.decr(burst_key)
# Set expiration times
pipe.expire(minute_key, 120) # 2 minutes
pipe.expire(hour_key, 7200) # 2 hours
pipe.expire(day_key, 172800) # 2 days
pipe.expire(burst_key, 60) # 1 minute
# Clean old entries
pipe.zremrangebyscore(minute_key, 0, current_time - 60)
pipe.zremrangebyscore(hour_key, 0, current_time - 3600)
pipe.zremrangebyscore(day_key, 0, current_time - 86400)
await pipe.execute()
# Replenish burst tokens over time
await self._replenish_burst_tokens(burst_key, burst_tokens)
return True, {
"allowed": True,
"minute_count": minute_count + 1,
"hour_count": hour_count + 1,
"day_count": day_count + 1,
"burst_remaining": burst_tokens - 1,
"limits": {
"per_minute": self.requests_per_minute,
"per_hour": self.requests_per_hour,
"per_day": self.requests_per_day,
"burst": self.burst_size
}
}
except RedisError as e:
logger.error(f"Redis error in rate limiting: {e}")
# Fail open - allow request if Redis is down
return True, {"error": "rate_limit_unavailable"}
except Exception as e:
logger.error(f"Unexpected error in rate limiting: {e}")
return True, {"error": "rate_limit_error"}
async def _replenish_burst_tokens(self, burst_key: str, current_tokens: int):
"""Replenish burst tokens over time"""
if current_tokens < self.burst_size:
try:
redis_client = await self.get_redis()
# Replenish 1 token per second up to burst_size
await redis_client.set(
burst_key,
min(current_tokens + 1, self.burst_size),
ex=60,
nx=True # Only set if doesn't exist
)
except Exception:
pass
async def reset_limits(self, identifier: str, endpoint: Optional[str] = None):
"""Reset rate limits for an identifier"""
try:
redis_client = await self.get_redis()
key_prefix = f"rate_limit:{identifier}"
if endpoint:
key_prefix += f":{endpoint}"
keys = [
f"{key_prefix}:minute",
f"{key_prefix}:hour",
f"{key_prefix}:day",
f"{key_prefix}:burst"
]
if keys:
await redis_client.delete(*keys)
except Exception as e:
logger.error(f"Error resetting limits: {e}")
async def get_limit_status(self, identifier: str, endpoint: Optional[str] = None) -> Dict[str, any]:
"""Get current limit status for an identifier"""
try:
redis_client = await self.get_redis()
current_time = time.time()
key_prefix = f"rate_limit:{identifier}"
if endpoint:
key_prefix += f":{endpoint}"
minute_key = f"{key_prefix}:minute"
hour_key = f"{key_prefix}:hour"
day_key = f"{key_prefix}:day"
burst_key = f"{key_prefix}:burst"
async with redis_client.pipeline() as pipe:
pipe.zcount(minute_key, current_time - 60, current_time)
pipe.zcount(hour_key, current_time - 3600, current_time)
pipe.zcount(day_key, current_time - 86400, current_time)
pipe.get(burst_key)
results = await pipe.execute()
return {
"minute": {
"used": results[0],
"limit": self.requests_per_minute,
"remaining": self.requests_per_minute - results[0]
},
"hour": {
"used": results[1],
"limit": self.requests_per_hour,
"remaining": self.requests_per_hour - results[1]
},
"day": {
"used": results[2],
"limit": self.requests_per_day,
"remaining": self.requests_per_day - results[2]
},
"burst": {
"remaining": int(results[3] or self.burst_size),
"limit": self.burst_size
}
}
except Exception as e:
logger.error(f"Error getting limit status: {e}")
return {}
async def cleanup_old_entries(self):
"""Clean up old entries from all rate limit keys"""
try:
redis_client = await self.get_redis()
current_time = time.time()
# Scan for rate limit keys
cursor = 0
while True:
cursor, keys = await redis_client.scan(
cursor,
match="rate_limit:*",
count=100
)
for key in keys:
if key.endswith(":minute"):
await redis_client.zremrangebyscore(key, 0, current_time - 60)
elif key.endswith(":hour"):
await redis_client.zremrangebyscore(key, 0, current_time - 3600)
elif key.endswith(":day"):
await redis_client.zremrangebyscore(key, 0, current_time - 86400)
if cursor == 0:
break
except Exception as e:
logger.error(f"Error cleaning up old entries: {e}")
async def close(self):
"""Close Redis connection"""
if self._redis_client:
await self._redis_client.close()
# Singleton instance
_rate_limiter = None
def get_rate_limiter() -> DistributedRateLimiter:
"""Get singleton rate limiter instance"""
global _rate_limiter
if _rate_limiter is None:
_rate_limiter = DistributedRateLimiter(
requests_per_minute=settings.RATE_LIMIT_PER_MINUTE,
requests_per_hour=settings.RATE_LIMIT_PER_HOUR,
requests_per_day=settings.RATE_LIMIT_PER_DAY
)
return _rate_limiter |