tustvold commented on code in PR #4922:
URL: https://github.com/apache/arrow-rs/pull/4922#discussion_r1355813655
##########
object_store/src/local.rs:
##########
@@ -996,15 +995,32 @@ fn convert_metadata(metadata: Metadata, location: Path)
-> Result<ObjectMeta> {
let size =
usize::try_from(metadata.len()).context(FileSizeOverflowedUsizeSnafu {
path: location.as_ref(),
})?;
+ let inode = get_inode(&metadata);
+ let mtime = last_modified.timestamp_micros();
+
+ // Use an ETag scheme based on that used by many popular HTTP servers
+ // <https://httpd.apache.org/docs/2.2/mod/core.html#fileetag>
+ //
<https://stackoverflow.com/questions/47512043/how-etags-are-generated-and-configured>
+ let etag = format!("{inode:x}-{mtime:x}-{size:x}");
Ok(ObjectMeta {
location,
last_modified,
size,
- e_tag: None,
+ e_tag: Some(etag),
})
}
+#[cfg(unix)]
+fn get_inode(metadata: &Metadata) -> u64 {
+ std::os::unix::fs::MetadataExt::ino(metadata)
+}
+
+#[cfg(not(unix))]
+fn get_inode(metadata: &Metadata) -> u64 {
+ 0
Review Comment:
The inode isn't strictly necessary, it is still a pretty strong ETag without
it, but on Unix systems we might as well make use of it.
A happy consequence of the way most operations create a new file and then
link it into place, is that the inode is actually a pretty good indicator
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