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git_backend: ensure no-gc refs are created for all imported head commits

This also means that we can implement GC without taking care of extra
metadata. I haven't tried, but it wouldn't be easy to keep Git refs and extra
table in sync.
This commit is contained in:
Yuya Nishihara 2024-01-08 20:39:39 +09:00
parent 2e1aa6c49c
commit 96ee9bdb9f

View file

@ -349,29 +349,28 @@ impl GitBackend {
return Ok(());
}
// Create no-gc ref even if known to the extras table. Concurrent GC
// process might have deleted the no-gc ref.
let locked_repo = self.lock_git_repo();
for &id in &head_ids {
prevent_gc(&locked_repo, id)?;
}
// These commits are imported from Git. Make our change ids persist (otherwise
// future write_commit() could reassign new change id.)
tracing::debug!(
heads_count = head_ids.len(),
"import extra metadata entries"
);
let locked_repo = self.lock_git_repo();
let (table, table_lock) = self.read_extra_metadata_table_locked()?;
let mut mut_table = table.start_mutation();
let missing_head_ids = head_ids
.into_iter()
.filter(|&id| mut_table.get_value(id.as_bytes()).is_none())
.collect_vec();
import_extra_metadata_entries_from_heads(
&locked_repo,
&mut mut_table,
&table_lock,
&missing_head_ids,
&head_ids,
self.imported_commit_uses_tree_conflict_format,
)?;
for &id in &missing_head_ids {
prevent_gc(&locked_repo, id)?;
}
self.save_extra_metadata_table(mut_table, &table_lock)
}
@ -660,10 +659,14 @@ fn import_extra_metadata_entries_from_heads(
git_repo: &gix::Repository,
mut_table: &mut MutableTable,
_table_lock: &FileLock,
missing_head_ids: &[&CommitId],
head_ids: &[&CommitId],
uses_tree_conflict_format: bool,
) -> BackendResult<()> {
let mut work_ids = missing_head_ids.iter().map(|&id| id.clone()).collect_vec();
let mut work_ids = head_ids
.iter()
.filter(|&id| mut_table.get_value(id.as_bytes()).is_none())
.map(|&id| id.clone())
.collect_vec();
while let Some(id) = work_ids.pop() {
let git_object = git_repo
.find_object(validate_git_object_id(&id)?)
@ -1658,6 +1661,7 @@ mod tests {
let settings = user_settings();
let temp_dir = testutils::new_temp_dir();
let backend = GitBackend::init_internal(&settings, temp_dir.path()).unwrap();
let git_repo = backend.open_git_repo().unwrap();
let signature = Signature {
name: "Someone".to_string(),
email: "someone@example.com".to_string(),
@ -1677,14 +1681,29 @@ mod tests {
secure_sig: None,
};
let commit_id = backend.write_commit(commit, None).unwrap().0;
let git_refs = backend
.open_git_repo()
.unwrap()
let git_refs: Vec<_> = git_repo
.references_glob("refs/jj/keep/*")
.unwrap()
.map(|git_ref| git_ref.unwrap().target().unwrap())
.collect_vec();
assert_eq!(git_refs, vec![git_id(&commit_id)]);
.try_collect()
.unwrap();
assert!(git_refs
.iter()
.any(|git_ref| git_ref.target().unwrap() == git_id(&commit_id)));
// Concurrently-running GC deletes the ref, leaving the extra metadata.
for mut git_ref in git_refs {
git_ref.delete().unwrap();
}
// Re-imported commit should have new ref.
backend.import_head_commits([&commit_id]).unwrap();
let git_refs: Vec<_> = git_repo
.references_glob("refs/jj/keep/*")
.unwrap()
.try_collect()
.unwrap();
assert!(git_refs
.iter()
.any(|git_ref| git_ref.target().unwrap() == git_id(&commit_id)));
}
#[test]