Use streamlit-session-memo for session-specific caching (#1243)

Author: whitphx

Diff for: pages/1_object_detection.py

@@ -12,6 +12,7 @@
 import cv2
 import numpy as np
 import streamlit as st
+from streamlit_session_memo import st_session_memo
 from streamlit_webrtc import WebRtcMode, webrtc_streamer
 
 from sample_utils.download import download_file
@@ -70,13 +71,12 @@ def generate_label_colors():
 download_file(PROTOTXT_URL, PROTOTXT_LOCAL_PATH, expected_size=29353)
 
 
-# Session-specific caching
-cache_key = "object_detection_dnn"
-if cache_key in st.session_state:
-    net = st.session_state[cache_key]
-else:
-    net = cv2.dnn.readNetFromCaffe(str(PROTOTXT_LOCAL_PATH), str(MODEL_LOCAL_PATH))
-    st.session_state[cache_key] = net
+@st_session_memo
+def get_model():
+    return cv2.dnn.readNetFromCaffe(str(PROTOTXT_LOCAL_PATH), str(MODEL_LOCAL_PATH))
+
+
+net = get_model()
 
 score_threshold = st.slider("Score threshold", 0.0, 1.0, 0.5, 0.05)
 

Diff for: pyproject.toml

@@ -29,6 +29,7 @@ dev = [
     "streamlit-server-state>=0.17.1",
     "twilio>=8.1",
     "opencv-python-headless>=4.5.4.58",
+    "streamlit-session-memo>=0.3.2",
     # For testing older versions of Streamlit: https://discuss.streamlit.io/t/modulenotfounderror-no-module-named-altair-vegalite-v4/42921
     "altair<5",
     # For testing older versions of Streamlit: https://discuss.streamlit.io/t/streamlit-run-with-protobuf-error/25632/3