[GitHub] [arrow-rs] liyongjing commented on issue #1969: close function instead of mutable reference

[GitBox <gi...@apache.org>]

liyongjing commented on issue #1969:
URL: https://github.com/apache/arrow-rs/issues/1969#issuecomment-1171850627

   I call `write` multiple times, call `close` one times using static HashMap.
   ```rust
   fn global() -> &'static Mutex<HashMap<String, Writer>> {
       static INSTANCE: OnceCell<Mutex<HashMap<String, Writer>>> = OnceCell::new();
       INSTANCE.get_or_init(|| Mutex::new(HashMap::new()))
   }
   pub fn write(path: &str, val: Vec<u8>) {
       let mut g = global_channel().lock().unwrap();
       let w = g.entry(path.to_string()).or_insert(Writer::new(path));
       let batch =  ...;
       w.write(&batch);
   }
   pub fn close(path: &str) {
       let mut g = global_channel().lock().unwrap();
       if let Some(v) = g.get_mut(path) {
           // *v don't copy
           v.close();
       }
       g.remove(path);
   }
   ```


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