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Differential D11910

rhg: Skip reading the contents of ambiguous files in some cases
ClosedPublic

Authored by SimonSapin on Dec 14 2021, 3:45 PM.

Details

Reviewers
Alphare
Group Reviewers
hg-reviewers
Commits
rHGb005d07ded7d: rhg: Skip reading the contents of ambiguous files in some cases
Summary

If the size of the file in the working directory does not match the length of
the filelog data, we know its contents will be different and don’t need to
read it.

rhg still decodes the filelog revision, which is not needed in some cases.

Diff Detail

Repository
rHG Mercurial
Lint
Automatic diff as part of commit; lint not applicable.
Unit
Automatic diff as part of commit; unit tests not applicable.

Event Timeline

SimonSapin created this revision.Dec 14 2021, 3:45 PM
Alphare accepted this revision.Dec 15 2021, 4:29 AM
This revision is now accepted and ready to land.Dec 15 2021, 4:29 AM

Revision Contents
Changeset List

PathPackages
Mrust/rhg/src/commands/status.rs (12 lines)

Diff 31490

rust/rhg/src/commands/status.rs

let entry = manifest let entry = manifest
.find_file(hg_path)? .find_file(hg_path)?
.expect("ambgious file not in p1"); .expect("ambgious file not in p1");
if entry.flags != fs_flags { if entry.flags != fs_flags {
return Ok(true); return Ok(true);
} }
let filelog = repo.filelog(hg_path)?; let filelog = repo.filelog(hg_path)?;
let fs_len = fs_metadata.len();
// TODO: check `fs_len` here like below, but based on
// `RevlogEntry::uncompressed_len` without decompressing the full filelog
// contents where possible. This is only valid if the revlog data does not
// contain metadata. See how Python’s `revlog.rawsize` calls
// `storageutil.filerevisioncopied`.
// (Maybe also check for content-modifying flags? See `revlog.size`.)
let filelog_entry = let filelog_entry =
filelog.data_for_node(entry.node_id()?).map_err(|_| { filelog.data_for_node(entry.node_id()?).map_err(|_| {
HgError::corrupted("filelog missing node from manifest") HgError::corrupted("filelog missing node from manifest")
})?; })?;
let contents_in_p1 = filelog_entry.data()?; let contents_in_p1 = filelog_entry.data()?;
if contents_in_p1.len() as u64 != fs_len {
// No need to read the file contents:
// it cannot be equal if it has a different length.
return Ok(true);
}
let fs_contents = if is_symlink { let fs_contents = if is_symlink {
get_bytes_from_os_string(vfs.read_link(fs_path)?.into_os_string()) get_bytes_from_os_string(vfs.read_link(fs_path)?.into_os_string())
} else { } else {
vfs.read(fs_path)? vfs.read(fs_path)?
}; };
Ok(contents_in_p1 != &*fs_contents) Ok(contents_in_p1 != &*fs_contents)
} }