feat: more robust persistent cache

Dockerfile

@@ -44,7 +44,6 @@ RUN mkdir -p $HF_HOME
 WORKDIR $APP_HOME
 EXPOSE 8501
 CMD streamlit run $APP_CODE/app.py  \
-    --logger.level=debug                 \
+    --logger.level=info                 \
     --server.enableXsrfProtection=true    \
     --server.fileWatcherType=auto
-    

src/app.py

@@ -17,7 +17,12 @@ DATA_PATH = pathlib.Path(os.environ.get("APP_DATA"))
 
 def cached_download_csv(url : str, **kwargs) -> pd.DataFrame:
     shelf_filename = DATA_PATH.joinpath("shelf.dat").as_posix()
-    with shelve.open(shelf_filename, writeback=True, flag='c') as shelf:
+    try:
+        s = shelve.open(shelf_filename, writeback=True, flag='c')
+    except Exception as exn:
+        st.warning("Unexpected exception, by-passing persistent cache :\n" + str(exn))
+        return pd.read_csv(url, **kwargs)
+    with s as shelf:
         st.info(f"Opened or created the shelf file '{shelf_filename}'")
         maybe_cached = shelf.get(url)
         if maybe_cached is None: