tustvold commented on code in PR #5281:
URL: https://github.com/apache/arrow-rs/pull/5281#discussion_r1442764078
##########
object_store/src/local.rs:
##########
@@ -1082,6 +1097,58 @@ fn convert_walkdir_result(
}
}
+
+/// Download a remote object to a local [`File`]
+pub async fn upload(store: &dyn ObjectStore, location: &Path, opts:
PutOptions, file: &mut std::fs::File) -> Result<()> {
+ // Determine file size
+ let metadata = file.metadata().map_err(|e| Error::FileMetadata {
+ source: e.into(),
+ })?;
+ let file_size = metadata.len();
+
+ // Set a threshold for when to switch to multipart_put
+ let multipart_threshold: u64 = 50 * 1024 * 1024;
+
+ if file_size <= multipart_threshold {
+ let mut buffer = Vec::with_capacity(file_size as usize);
+ file.read_to_end(&mut buffer).map_err(|e|
Error::UnableToReadBytesFromFile{
+ source: e
+ })?;
+ let bytes = Bytes::from(buffer);
+ store.put_opts(&location, bytes, opts).await?;
+ Ok(())
+ } else {
+ let (_id, mut writer) = store.put_multipart(&location).await?;
+ let mut buffer = vec![0u8; 5 * 1024 * 1024];
+ while let Ok(size) = file.read(&mut buffer) {
+ if size == 0 {
+ break;
+ }
+ writer.write_all(&buffer[..size]).await.unwrap();
+ }
+
+ writer.flush().await.unwrap();
+ writer.shutdown().await.unwrap();
+ Ok(())
+ }
+}
+
+
+/// Upload a local [`File`] to a remote object store
+pub async fn download(store: &dyn ObjectStore, location: &Path, opts:
GetOptions, file: &mut File) -> Result<()> {
+ let get_result = store.get_opts(location, opts).await?;
+ let mut stream = get_result.into_stream();
+
+ while let Some(bytes_result) = stream.next().await {
+ let bytes = bytes_result?;
+ file.write_all(&bytes).map_err(|e| Error::UnableToWriteBytesToFile{
+ source: e.into()
+ })?;
+ }
Review Comment:
As written this will currently perform blocking IO on the current thread,
you probably want to spawn_blocking the IO task, and separate it from the
producer with a mpsc channel or something. I can try to get an example of this
up later today
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