Files
meshcore-bot/modules/rate_limiter.py
T
agessaman c5452033f2 refactor(rate-limiter): improve request handling and synchronization
- Updated the NominatimRateLimiter to ensure thread-safe request recording and management.
- Refactored the wait_for_request and wait_and_request methods to share a single reservation mechanism for both async and sync callers.
- Enhanced the rate-limited geocoding functions to utilize the new request reservation method, ensuring proper request handling without unnecessary recording.
- Added tests to verify the correct behavior of the new request handling logic and its interaction between async and sync contexts.
2026-07-28 17:14:57 -07:00

307 lines
11 KiB
Python

#!/usr/bin/env python3
"""
Rate limiting functionality for the MeshCore Bot
Controls how often messages can be sent to prevent spam
"""
import asyncio
import threading
import time
from collections import OrderedDict
from typing import Optional
class PerUserRateLimiter:
"""Per-user rate limiting: minimum seconds between bot replies to the same user.
User identity is keyed by rate_limit_key (pubkey when available, else sender name).
The key map is bounded by max_entries; eviction of oldest entries may allow a
previously rate-limited user to send again slightly earlier.
"""
def __init__(self, seconds: float, max_entries: int = 1000):
self.seconds = seconds
self.max_entries = max_entries
# OrderedDict provides O(1) move-to-end + oldest-first eviction.
self._last_send: OrderedDict[str, float] = OrderedDict()
# Back-compat for existing tests/introspection: keep insertion/LRU order.
self._order: list[str] = []
self._lock = threading.Lock()
def _normalize_key(self, key: str) -> str:
return key.strip()
def can_send(self, key: str) -> bool:
"""Check if we can send a message to this user (key)."""
key = self._normalize_key(key)
if not key:
return True
with self._lock:
last = self._last_send.get(key, 0)
return time.monotonic() - last >= self.seconds
def time_until_next(self, key: str) -> float:
"""Get time until next allowed send for this user."""
key = self._normalize_key(key)
if not key:
return 0.0
with self._lock:
last = self._last_send.get(key, 0)
elapsed = time.monotonic() - last
return max(0.0, self.seconds - elapsed)
def record_send(self, key: str) -> None:
"""Record that we sent a message to this user."""
key = self._normalize_key(key)
if not key:
return
with self._lock:
if key in self._last_send:
self._last_send.move_to_end(key)
elif len(self._last_send) >= self.max_entries:
self._last_send.popitem(last=False)
self._last_send[key] = time.monotonic()
# Keep `_order` consistent for callers/tests.
self._order = list(self._last_send.keys())
class RateLimiter:
"""Rate limiting for message sending"""
def __init__(self, seconds: float):
self.seconds = float(seconds)
self.last_send = 0.0
self._total_sends = 0
self._total_throttled = 0
self._lock = threading.Lock()
def can_send(self) -> bool:
"""Check if we can send a message"""
with self._lock:
can = time.monotonic() - self.last_send >= self.seconds
if not can:
self._total_throttled += 1
return can
def time_until_next(self) -> float:
"""Get time until next allowed send"""
with self._lock:
elapsed = time.monotonic() - self.last_send
return max(0, self.seconds - elapsed)
def record_send(self):
"""Record that we sent a message"""
with self._lock:
self.last_send = time.monotonic()
self._total_sends += 1
def get_stats(self) -> dict:
"""Get rate limiter statistics"""
with self._lock:
total_attempts = self._total_sends + self._total_throttled
throttle_rate = self._total_throttled / max(1, total_attempts)
return {
'total_sends': self._total_sends,
'total_throttled': self._total_throttled,
'throttle_rate': throttle_rate
}
class BotTxRateLimiter:
"""Rate limiting for bot transmission to prevent network overload"""
def __init__(self, seconds: float = 1.0):
self.seconds = seconds
self.last_tx = 0.0
self._total_tx = 0
self._total_throttled = 0
self._lock = threading.Lock()
def can_tx(self) -> bool:
"""Check if bot can transmit a message"""
with self._lock:
can = time.monotonic() - self.last_tx >= self.seconds
if not can:
self._total_throttled += 1
return can
def time_until_next_tx(self) -> float:
"""Get time until next allowed transmission"""
with self._lock:
elapsed = time.monotonic() - self.last_tx
return max(0, self.seconds - elapsed)
def record_tx(self):
"""Record that bot transmitted a message"""
with self._lock:
self.last_tx = time.monotonic()
self._total_tx += 1
async def wait_for_tx(self):
"""Wait until bot can transmit (async)"""
while not self.can_tx():
wait_time = self.time_until_next_tx()
if wait_time > 0:
await asyncio.sleep(wait_time + 0.05) # Small buffer
def get_stats(self) -> dict:
"""Get rate limiter statistics"""
with self._lock:
total_attempts = self._total_tx + self._total_throttled
throttle_rate = self._total_throttled / max(1, total_attempts)
return {
'total_tx': self._total_tx,
'total_throttled': self._total_throttled,
'throttle_rate': throttle_rate
}
class ChannelRateLimiter:
"""Per-channel rate limiting: minimum seconds between bot messages on the same channel.
Channel names are mapped to ``RateLimiter`` instances using limits loaded from
the ``[Rate_Limits]`` config section (``channel.<name>_seconds = N``).
Channels without an explicit limit are unrestricted.
"""
def __init__(self, channel_limits: dict[str, float]):
normalized: dict[str, float] = {}
for channel, seconds in channel_limits.items():
ch = self._normalize_channel(channel)
try:
sec = float(seconds)
except (TypeError, ValueError):
continue
if ch and sec > 0:
normalized[ch] = sec
self._limiters: dict[str, RateLimiter] = {
channel: RateLimiter(seconds)
for channel, seconds in normalized.items()
}
def _normalize_channel(self, channel: str) -> str:
return channel.strip().lower()
def can_send(self, channel: str) -> bool:
limiter = self._limiters.get(self._normalize_channel(channel))
return limiter.can_send() if limiter else True
def time_until_next(self, channel: str) -> float:
limiter = self._limiters.get(self._normalize_channel(channel))
return limiter.time_until_next() if limiter else 0.0
def record_send(self, channel: str) -> None:
limiter = self._limiters.get(self._normalize_channel(channel))
if limiter:
limiter.record_send()
def get_stats(self) -> dict[str, dict]:
return {ch: lim.get_stats() for ch, lim in self._limiters.items()}
def channels(self) -> list[str]:
return list(self._limiters.keys())
class NominatimRateLimiter:
"""Rate limiting for Nominatim geocoding API requests
Nominatim policy: Maximum 1 request per second
We'll be conservative and use 1.1 seconds to ensure compliance
"""
def __init__(self, seconds: float = 1.1):
self.seconds = seconds
self.last_request: float = 0.0
self._lock: Optional[asyncio.Lock] = None
self._lock_init = threading.Lock() # Guards lazy creation of asyncio.Lock
self._sync_lock = threading.Lock() # Serializes the worker-thread path
self._total_requests = 0
self._total_throttled = 0
def _get_lock(self) -> asyncio.Lock:
"""Lazily initialize the async lock (thread-safe)."""
if self._lock is None:
with self._lock_init:
if self._lock is None:
self._lock = asyncio.Lock()
return self._lock
def can_request(self) -> bool:
"""Check if we can make a Nominatim request"""
can = time.monotonic() - self.last_request >= self.seconds
if not can:
self._total_throttled += 1
return can
def time_until_next(self) -> float:
"""Get time until next allowed request"""
elapsed = time.monotonic() - self.last_request
return max(0, self.seconds - elapsed)
def record_request(self):
"""Record that we made a Nominatim request"""
with self._sync_lock:
self.last_request = time.monotonic()
self._total_requests += 1
async def wait_for_request(self):
"""Wait until we can make a Nominatim request (async)"""
while not self.can_request():
wait_time = self.time_until_next()
if wait_time > 0:
await asyncio.sleep(wait_time + 0.05) # Small buffer
async def wait_and_request(self) -> None:
"""Atomically reserve an async request slot shared with sync callers."""
async with self._get_lock():
while True:
with self._sync_lock:
elapsed = time.monotonic() - self.last_request
if elapsed >= self.seconds:
self.last_request = time.monotonic()
self._total_requests += 1
return
self._total_throttled += 1
wait_time = self.seconds - elapsed + 0.05
await asyncio.sleep(wait_time)
def wait_for_request_sync(self):
"""Wait until we can make a Nominatim request (synchronous).
Prefer :meth:`wait_and_request_sync`: this only waits, so a caller that
records the request afterwards leaves a check-then-act window.
"""
while not self.can_request():
wait_time = self.time_until_next()
if wait_time > 0:
time.sleep(wait_time + 0.05) # Small buffer
def wait_and_request_sync(self) -> None:
"""Wait until a request may be made, then reserve the slot (thread-safe).
The sync twin of :meth:`wait_and_request`. Reserving *before* the caller's
HTTP request, under a lock, is what keeps the 1 req/s policy: geocoding now
runs on worker threads, and a wait-then-record-after pattern let several
threads clear the gate together and hit Nominatim simultaneously.
"""
while True:
with self._sync_lock:
elapsed = time.monotonic() - self.last_request
if elapsed >= self.seconds:
self.last_request = time.monotonic()
self._total_requests += 1
return
self._total_throttled += 1
wait_time = self.seconds - elapsed + 0.05
time.sleep(wait_time) # Small buffer
def get_stats(self) -> dict:
"""Get rate limiter statistics"""
total_attempts = self._total_requests + self._total_throttled
throttle_rate = self._total_throttled / max(1, total_attempts)
return {
'total_requests': self._total_requests,
'total_throttled': self._total_throttled,
'throttle_rate': throttle_rate
}