[GitHub] [arrow-datafusion] yjshen edited a comment on pull request #1905: Avoid repeated `open` for one single file and simplify object reader API on the `sync` part

[GitBox]

yjshen edited a comment on pull request #1905:
URL: 
https://github.com/apache/arrow-datafusion/pull/1905#issuecomment-1059727088


   I cannot do `Arc<RefCell<dyn ObjectReader>>` since RefCell is not sync. 
Which is imposed by Arc as well as ChunkReader:
   ```rust
   pub trait ChunkReader: Length + Send + Sync 
   ```
   ```
   343 | impl ChunkReader for ObjectReaderWrapper {
       |      ^^^^^^^^^^^ `RefCell<(dyn ObjectReader + 'static)>` cannot be 
shared between threads safely
       |
       = help: the trait `Sync` is not implemented for `RefCell<(dyn 
ObjectReader + 'static)>`
       = note: required because of the requirements on the impl of `Sync` for 
`Arc<RefCell<(dyn ObjectReader + 'static)>>`
   ```
   
   I'm not sure I could remove Sync from ChunkReader, but I can try it first.
   
   


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