Method GetAllNotes

repository/git.go:877–928

GetAllNotes reads the contents of the notes under the given ref for every commit. The returned value is a mapping from commit hash to the list of notes for that commit. This is the batch version of the corresponding GetNotes(...) method.

(notesRef string)

//
// This is the batch version of the corresponding GetNotes(...) method.
func (repo *GitRepo) GetAllNotes(notesRef string) (map[string][]Note, error) {
	// This code is unfortunately quite complicated, but it needs to be so.
	//
	// Conceptually, this is equivalent to:
	//   result := make(map[string][]Note)
	//   for _, commit := range repo.ListNotedRevisions(notesRef) {
	//     result[commit] = repo.GetNotes(notesRef, commit)
	//   }
	//   return result, nil
	//
	// However, that logic would require separate executions of the 'git'
	// command for every annotated commit. For a repo with 10s of thousands
	// of reviews, that would mean calling Cmd.Run(...) 10s of thousands of
	// times. That, in turn, would take so long that the tool would be unusable.
	//
	// This method avoids that by taking advantage of the 'git cat-file --batch="..."'
	// command. That allows us to use a single invocation of Cmd.Run(...) to
	// inspect multiple git objects at once.
	//
	// As such, regardless of the number of reviews in a repo, we can get all
	// of the notes using a total of three invocations of Cmd.Run(...):
	//  1. One to list all the annotated objects (and their notes hash)
	//  2. A second one to filter out all of the annotated objects that are not commits.
	//  3. A final one to get the contents of all of the notes blobs.
	overview, err := repo.notesOverview(notesRef)
	if err != nil {
		return nil, err
	}
	isCommit, err := overview.getIsCommitMap(repo)
	if err != nil {
		return nil, fmt.Errorf("Failure building the set of commit objects: %v", err)
	}
	noteContentsMap, err := overview.getNoteContentsMap(repo)
	if err != nil {
		return nil, fmt.Errorf("Failure building the mapping from notes hash to contents: %v", err)
	}
	commitNotesMap := make(map[string][]Note)
	for _, notesMapping := range overview.NotesMappings {
		if !isCommit[*notesMapping.ObjectHash] {
			continue
		}
		noteBytes := noteContentsMap[*notesMapping.NotesHash]
		byteSlices := bytes.Split(noteBytes, []byte("\n"))
		var notes []Note
		for _, slice := range byteSlices {
			notes = append(notes, Note(slice))
		}
		commitNotesMap[*notesMapping.ObjectHash] = notes
	}

	return commitNotesMap, nil
}

// AppendNote appends a note to a revision under the given ref.
func (repo *GitRepo) AppendNote(notesRef, revision string, note Note) error {