sunchao commented on a change in pull request #7969:
URL: https://github.com/apache/arrow/pull/7969#discussion_r471017707
##########
File path: rust/arrow/src/ipc/reader.rs
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@@ -473,7 +476,7 @@ pub struct FileReader<R: Read + Seek> {
blocks: Vec<ipc::Block>,
/// A counter to keep track of the current block that should be read
- current_block: usize,
+ current_block: AtomicUsize,
Review comment:
curious why this is an atomic var now - will there by multiple threads
accessing the same `FileReader` instance?
##########
File path: rust/arrow/src/ipc/reader.rs
##########
@@ -783,21 +787,22 @@ impl<R: Read> RecordBatchReader for StreamReader<R> {
self.schema.clone()
}
- fn next_batch(&mut self) -> Result<Option<RecordBatch>> {
- if self.finished {
+ fn next_batch(&self) -> Result<Option<RecordBatch>> {
+ if self.finished.load(Ordering::SeqCst) {
return Ok(None);
}
// determine metadata length
let mut meta_size: [u8; 4] = [0; 4];
- match self.reader.read_exact(&mut meta_size) {
+ let mut reader = self.reader.borrow_mut();
Review comment:
this will panic when someone else is holding the reference, so we need
to be careful - not sure if `try_borrow_mut` makes more sense here though.
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