fix(proxy_server.py): enable pre+post-call hooks and max parallel request limits

litellm/proxy/hooks/parallel_request_limiter.py

@@ -0,0 +1,33 @@
+from typing import Optional
+from litellm.caching import DualCache
+from fastapi import HTTPException
+
+async def max_parallel_request_allow_request(max_parallel_requests: Optional[int], api_key: Optional[str], user_api_key_cache: DualCache): 
+    if api_key is None:
+        return
+
+    if max_parallel_requests is None:
+        return
+    
+    # CHECK IF REQUEST ALLOWED
+    request_count_api_key = f"{api_key}_request_count"
+    current = user_api_key_cache.get_cache(key=request_count_api_key)
+    if current is None:
+        user_api_key_cache.set_cache(request_count_api_key, 1)
+    elif int(current) <  max_parallel_requests:
+        # Increase count for this token
+        user_api_key_cache.set_cache(request_count_api_key, int(current) + 1)
+    else: 
+        raise HTTPException(status_code=429, detail="Max parallel request limit reached.")
+
+
+async def max_parallel_request_update_count(api_key: Optional[str], user_api_key_cache: DualCache): 
+    if api_key is None:
+        return
+    
+    request_count_api_key = f"{api_key}_request_count"
+    # Decrease count for this token
+    current = user_api_key_cache.get_cache(key=request_count_api_key) or 1
+    user_api_key_cache.set_cache(request_count_api_key, int(current) - 1)
+
+    return