refactor: for sessions use dictionary instead of set

app.py

@@ -18,12 +18,12 @@ class Session:
 app = Flask(__name__)
 PORT = int(os.environ.get("PORT", 5000))
 
-sessions: set[Session] = set()
+sessions: dict[str, Session] = {}
 
 def frame_processor(session_id: str):
     global sessions
 
-    session: Session = next((s for s in sessions if s.id == session_id), None)
+    session: Session = sessions.get(session_id, None)
 
     if session is not None:
         cap = cv2.VideoCapture("classroom.mp4")
@@ -82,7 +82,7 @@ def frame_processor(session_id: str):
 def stream_mjpeg(session_id: str):
     global sessions
 
-    session: Session = next((s for s in sessions if s.id == session_id), None)
+    session: Session = sessions.get(session_id, None)
 
     if session is not None:
         while True:
@@ -105,12 +105,12 @@ def video_feed():
     session_id = request.args.get("id", "default")
     show_stats = request.args.get("show_stats", "1") == "1"
 
-    if session_id not in [s.id for s in sessions]:
+    if session_id not in sessions:
         session = Session(session_id)
-        sessions.add(session)
+        sessions[session_id] = session
         threading.Thread(target=frame_processor, args=[session_id], daemon=True).start()
     else:
-        session = next(s for s in sessions if s.id == session_id)
+        session = sessions[session_id]
         session.show_stats = show_stats
         
     return Response(stream_with_context(stream_mjpeg(session_id)), mimetype="multipart/x-mixed-replace; boundary=frame")