adding session manager to clean expired strays

compose.yml

@@ -4,10 +4,10 @@ services:
   cheshire-cat-core:
     build:
       context: ./core
-    container_name: cheshire_cat_core
+    container_name: cheshire_cat_core_dev
     # Uncomment the two lines below to use your .env (see .env.example)
-    #env_file:
-    #  - .env
+    env_file:
+      - .env
     ports:
       - ${CCAT_CORE_PORT:-1865}:80
       - 5678:5678 # only for development purposes (take away in production)

core/cat/auth/connection.py

@@ -66,6 +66,31 @@ async def extract_credentials(self, connection: Request | WebSocket) -> Tuple[st
     async def get_user_stray(self, user: AuthUserInfo, connection: Request | WebSocket) -> StrayCat:
         pass
 
+    # this method uses session manager to refresh user expiration time
+    async def refresh_user_expiration(self, connection: Request, user: AuthUserInfo, strays: any) -> None:
+        session_manager = connection.app.state.session_manager
+        #this should be changed into a meaningful amount of minutes it's just for testing
+        # if user.name contains "test" get the last character to extract minutes
+        #
+        # user: test1 will expire after 1 minutes
+        # user: test2 will expire after 2 minutes
+        # user: test3 will expire after 3 minutes
+        # user: test4 will expire after 4 minutes
+        # and so on 
+        #
+        if "test" in user.name:
+            minutes = int(user.name[-1])
+        else:
+            minutes = 60 * 24
+        session_manager.add(user.id, strays[user.id], minutes)
+        pass
+
+    # this method uses session manager to evict expired users
+    async def evict_expired_users(self, connection: Request) -> None:
+        session_manager = connection.app.state.session_manager
+        await session_manager.evict_expired_sessions()
+        pass
+
     @abstractmethod
     def not_allowed(self, connection: Request | WebSocket):
         pass
@@ -111,6 +136,10 @@ async def get_user_stray(self, user: AuthUserInfo, connection: Request) -> Stray
                     # TODOV2: user_id should be the user.id
                 user_id=user.name, user_data=user, main_loop=event_loop
             )
+
+        await self.refresh_user_expiration(connection, user, strays)
+        await self.evict_expired_users(connection)
+
         return strays[user.id]
 
     def not_allowed(self, connection: Request):
@@ -144,6 +173,10 @@ async def get_user_stray(self, user: AuthUserInfo, connection: WebSocket) -> Str
 
             # Set new ws connection
             stray.reset_connection(connection)
+
+            await self.refresh_user_expiration(connection, user, strays)
+            await self.evict_expired_users(connection)
+
             log.info(
                 f"New websocket connection for user '{user.id}', the old one has been closed."
             )
@@ -157,8 +190,12 @@ async def get_user_stray(self, user: AuthUserInfo, connection: WebSocket) -> Str
                 main_loop=asyncio.get_running_loop(),
             )
             strays[user.id] = stray
+
+            await self.refresh_user_expiration(connection, user, strays)
+            await self.evict_expired_users(connection, user)
+
             return stray
-        
+
     def not_allowed(self, connection: WebSocket):
         raise WebSocketException(code=1004, reason="Invalid Credentials")
 

core/cat/auth/session_manager.py

@@ -0,0 +1,74 @@
+from datetime import datetime, timedelta
+from cat.utils import singleton
+from cat.log import log
+
+@singleton
+class SessionManager:
+    """
+    This class is responsible for strays session management
+
+    - adding new sessions
+    - getting sessions
+    - expiring sessions
+    """
+
+    def __init__(self, strays: any) -> None:
+        self.strays = strays
+        self.sessions = {}
+        self.user_ids = []
+
+    def add(self, user_id: str, stray: any, minutes: int = 60 * 24) -> None:
+        """
+        add new session setting expiration time to now plus x minutes
+        each session uses the expiration time as key and the value is a dict with user_id and stray
+        """
+
+        current_time = datetime.now() + timedelta(minutes=minutes)
+
+        # if user_id is already in the session we removed it first
+        if user_id in self.user_ids:
+            timestamp_to_remove = [
+                timestamp for timestamp in self.sessions if self.sessions[timestamp]["user_id"] == user_id
+            ]
+            for timestamp in timestamp_to_remove:
+                self.sessions.pop(timestamp)
+
+        # then we create a new session
+        self.sessions[current_time] = {"user_id": user_id, "stray": stray}
+
+        # and add the user_id to the list of user_ids
+        self.user_ids.append(user_id)
+        pass
+
+    async def evict_expired_sessions(self) -> int:
+        """
+        this method removes expired sessions
+        """
+
+        print("active sessions")
+        print("*" * 20)
+        for timestamp in self.sessions:
+            if timestamp >= datetime.now():
+                print(f"expiration date: {timestamp} -> {self.sessions[timestamp]}")
+        print("*" * 20)
+
+        keys_to_remove = [
+            timestamp for timestamp in self.sessions if timestamp < datetime.now()
+        ]
+        for key in keys_to_remove:
+            user_id = self.sessions[key]["user_id"]
+            if user_id in self.strays.keys():
+                print(f"deleting expired user: {self.strays[user_id]}")
+                del self.strays[user_id]
+                if user_id in self.user_ids:
+                    self.user_ids.remove(user_id)
+            self.sessions.pop(key)
+
+        expired_count  = len(keys_to_remove)
+        if expired_count > 0:
+            log.info(
+                f"{expired_count} sessions expired."
+            )
+
+        return expired_count
+

core/cat/main.py

@@ -8,6 +8,7 @@
 from fastapi.responses import JSONResponse
 from fastapi.exceptions import RequestValidationError
 from fastapi.middleware.cors import CORSMiddleware
+from cat.auth.session_manager import SessionManager
 
 from cat.log import log
 from cat.env import get_env, fix_legacy_env_variables
@@ -47,6 +48,8 @@ async def lifespan(app: FastAPI):
     # Dict of pseudo-sessions (key is the user_id)
     app.state.strays = {}
 
+    app.state.session_manager = SessionManager(app.state.strays)
+
     # set a reference to asyncio event loop
     app.state.event_loop = asyncio.get_running_loop()