add base ratelimiter

melisa/core/http.py

@@ -14,7 +14,10 @@ from melisa.exceptions import (NotModifiedError,
                                UnauthorizedError,
                                HTTPException,
                                NotFoundError,
-                               MethodNotAllowedError)
+                               MethodNotAllowedError,
+                               ServerError,
+                               RateLimitError)
+from .ratelimiter import RateLimiter
 
 
 class HTTPClient:
@@ -23,6 +26,7 @@ class HTTPClient:
     def __init__(self, token: str, *, ttl: int = 5):
         self.url: str = f"https://discord.com/api/v{self.API_VERSION}"
         self.max_ttl: int = ttl
+        self.__rate_limiter = RateLimiter()
 
         headers: Dict[str, str] = {
             "Content-Type": "application/json",
@@ -36,11 +40,18 @@ class HTTPClient:
             401: UnauthorizedError(),
             403: ForbiddenError(),
             404: NotFoundError(),
-            405: MethodNotAllowedError()
+            405: MethodNotAllowedError(),
+            429: RateLimitError()
         }
 
         self.__aiohttp_session: ClientSession = ClientSession(headers=headers)
 
+    async def __aenter__(self):
+        return self
+
+    async def __aexit__(self, exc_type, exc, tb):
+        await self.close()
+
     async def close(self):
         """Close the aiohttp session"""
         await self.__aiohttp_session.close()
@@ -57,11 +68,18 @@ class HTTPClient:
 
         ttl = _ttl or self.max_ttl
 
+        if ttl == 0:
+            raise ServerError(f"Maximum amount of retries for `{endpoint}`.")
+
+        await self.__rate_limiter.wait_until_not_ratelimited(
+            endpoint,
+            method
+        )
+
         url = f"{self.url}/{endpoint}"
 
-        if ttl != 0:
-            async with self.__aiohttp_session.request(method, url, **kwargs) as response:
-                return await self.__handle_response(response, method, endpoint, _ttl=ttl, **kwargs)
+        async with self.__aiohttp_session.request(method, url, **kwargs) as response:
+            return await self.__handle_response(response, method, endpoint, _ttl=ttl, **kwargs)
 
     async def __handle_response(
             self,
@@ -74,12 +92,26 @@ class HTTPClient:
     ) -> Optional[Dict]:
         """Handle responses from the Discord API."""
 
+        self.__rate_limiter.save_response_bucket(
+            endpoint, method, res.headers
+        )
+
         if res.ok:
             return await res.json()
 
         exception = self.__http_exceptions.get(res.status)
 
         if exception:
+            if isinstance(exception, RateLimitError):
+                timeout = (await res.json()).get("retry_after", 40)
+
+                await asyncio.sleep(timeout)
+                return await self.__send(
+                    method,
+                    endpoint,
+                    **kwargs
+                )
+
             exception.__init__(res.reason)
             raise exception
 

melisa/core/ratelimiter.py

@@ -0,0 +1,64 @@
+# Copyright MelisaDev 2022 - Present
+# Full MIT License can be found in `LICENSE.txt` at the project root.
+
+from __future__ import annotations
+
+from asyncio import sleep
+from dataclasses import dataclass
+from time import time
+from typing import Dict, Tuple, Any
+
+
+@dataclass
+class RateLimitBucket:
+    """Represents a rate limit bucket"""
+    limit: int
+    remaining: int
+    reset: float
+    reset_after_timestamp: float
+    since_timestamp: float
+
+
+class RateLimiter:
+    """Prevents ``user`` rate limits"""
+
+    def __init__(self) -> None:
+        self.bucket_map: Dict[Tuple[str, str], str] = {}  # Dict[Tuple[endpoint, method], bucket_id]
+        self.buckets: Dict[str, RateLimitBucket] = {}
+
+    def save_response_bucket(
+        self,
+        endpoint: str,
+        method: str,
+        header: Any
+    ):
+        ratelimit_bucket_id = header.get("X-RateLimit-Bucket")
+
+        if not ratelimit_bucket_id:
+            return
+
+        self.bucket_map[endpoint, method] = ratelimit_bucket_id
+
+        self.buckets[ratelimit_bucket_id] = RateLimitBucket(
+            limit=int(header["X-RateLimit-Limit"]),
+            remaining=int(header["X-RateLimit-Remaining"]),
+            reset=float(header["X-RateLimit-Reset"]),
+            reset_after_timestamp=float(header["X-RateLimit-Reset-After"]),
+            since_timestamp=time()
+        )
+
+    async def wait_until_not_ratelimited(
+        self,
+        endpoint: str,
+        method: str
+    ):
+        bucket_id = self.bucket_map.get((endpoint, method))
+
+        if not bucket_id:
+            return
+
+        bucket = self.buckets[bucket_id]
+
+        if bucket.remaining == 0:
+            sleep_time = time() - bucket.since_timestamp + bucket.reset_after_timestamp
+            await sleep(sleep_time)

requirements.txt

@@ -1 +1 @@
-aiohttp~=3.8.1
+aiohttp