alamb commented on code in PR #7019:
URL: https://github.com/apache/arrow-rs/pull/7019#discussion_r1945230858
##########
object_store/src/local.rs:
##########
@@ -678,6 +622,93 @@ impl ObjectStore for LocalFileSystem {
}
}
+impl LocalFileSystem {
+ fn list_with_maybe_offset(
+ &self,
+ prefix: Option<&Path>,
+ maybe_offset: Option<&Path>,
+ ) -> BoxStream<'static, Result<ObjectMeta>> {
+ let config = Arc::clone(&self.config);
+
+ let root_path = match prefix {
+ Some(prefix) => match config.prefix_to_filesystem(prefix) {
+ Ok(path) => path,
+ Err(e) => return
futures::future::ready(Err(e)).into_stream().boxed(),
+ },
+ None => config.root.to_file_path().unwrap(),
+ };
+
+ let walkdir = WalkDir::new(root_path)
+ // Don't include the root directory itself
+ .min_depth(1)
+ .follow_links(true);
+
+ let maybe_offset = maybe_offset.cloned();
+
+ let s = walkdir.into_iter().flat_map(move |result_dir_entry| {
+ // Apply offset filter before proceeding, to reduce statx file
system calls
+ // This matters for NFS mounts
+ if let (Some(offset), Ok(entry)) = (maybe_offset.as_ref(),
result_dir_entry.as_ref()) {
+ let location = config.filesystem_to_path(entry.path());
+ match location {
+ Ok(path) if path <= *offset => return None,
+ Err(e) => return Some(Err(e)),
+ _ => {}
+ }
+ }
+
+ let entry = match
convert_walkdir_result(result_dir_entry).transpose()? {
Review Comment:
My understanding is that the whole point of this PR is to avoid calling
`convert_walkdir_result` for files that will not be opened
##########
object_store/src/local.rs:
##########
@@ -1401,6 +1432,66 @@ mod tests {
);
}
+ #[tokio::test]
+ async fn test_path_with_offset() {
+ let root = TempDir::new().unwrap();
+ let integration =
LocalFileSystem::new_with_prefix(root.path()).unwrap();
+
+ let root_path = root.path();
+ for i in 0..5 {
+ let filename = format!("test{}.parquet", i);
+ let file = root_path.join(filename);
+ std::fs::write(file, "test").unwrap();
+ }
+ let filter_str = "test";
+ let filter = String::from(filter_str);
+ let offset_str = filter + "1";
+ let offset = Path::from(offset_str.clone());
+
+ // Use list_with_offset to retrieve files
+ let res = integration.list_with_offset(None, &offset);
+ let offset_paths: Vec<_> = res.map_ok(|x|
x.location).try_collect().await.unwrap();
+ let mut offset_files: Vec<_> = offset_paths
+ .iter()
+ .map(|x| String::from(x.filename().unwrap()))
+ .collect();
+
+ // Check result with direct filesystem read
Review Comment:
I think this depends on the file system returning the same order each time.
Again this is probably ok but it seems like it could result in a non
deterministic test failure over time
##########
object_store/src/local.rs:
##########
@@ -678,6 +622,93 @@ impl ObjectStore for LocalFileSystem {
}
}
+impl LocalFileSystem {
+ fn list_with_maybe_offset(
+ &self,
+ prefix: Option<&Path>,
+ maybe_offset: Option<&Path>,
+ ) -> BoxStream<'static, Result<ObjectMeta>> {
+ let config = Arc::clone(&self.config);
+
+ let root_path = match prefix {
+ Some(prefix) => match config.prefix_to_filesystem(prefix) {
+ Ok(path) => path,
+ Err(e) => return
futures::future::ready(Err(e)).into_stream().boxed(),
+ },
+ None => config.root.to_file_path().unwrap(),
+ };
+
+ let walkdir = WalkDir::new(root_path)
Review Comment:
I did some digging and I don't think WalkDir guarantees anything about the
sort order of the directory entries
thus if the OS returns a different order on the next call to
`list_with_offset` this may end up with a different result
However I think the existing default impl of `list_with_offset` (which just
calls list() and takes the offset) has the same problem so I don't think it
needs to be fixed in this PR
##########
object_store/src/local.rs:
##########
@@ -678,6 +622,93 @@ impl ObjectStore for LocalFileSystem {
}
}
+impl LocalFileSystem {
+ fn list_with_maybe_offset(
+ &self,
+ prefix: Option<&Path>,
+ maybe_offset: Option<&Path>,
+ ) -> BoxStream<'static, Result<ObjectMeta>> {
+ let config = Arc::clone(&self.config);
+
+ let root_path = match prefix {
+ Some(prefix) => match config.prefix_to_filesystem(prefix) {
+ Ok(path) => path,
+ Err(e) => return
futures::future::ready(Err(e)).into_stream().boxed(),
+ },
+ None => config.root.to_file_path().unwrap(),
+ };
+
+ let walkdir = WalkDir::new(root_path)
Review Comment:
It does look to me like you can explicitly set an order via
https://docs.rs/walkdir/latest/walkdir/struct.WalkDir.html#method.sort_by
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