Method writeCompleteIndex

internal/users/index.go:479–520

writeCompleteIndex writes metadata and all records atomically via temp file + rename.

(records []IndexUserRecord)

// writeCompleteIndex writes metadata and all records atomically via temp file + rename.
func (idx *UserIndex) writeCompleteIndex(records []IndexUserRecord) error {
	tmpFile := idx.Filename + ".tmp"
	f, err := os.Create(tmpFile)
	if err != nil {
		return err
	}

	writeErr := func() error {
		headerBytes, err := idx.metaData.Format()
		if err != nil {
			return err
		}

		buf := make([]byte, 0, len(headerBytes)+len(records)*IndexRecordSizeV1)
		buf = append(buf, headerBytes...)

		var recBuf [IndexRecordSizeV1]byte
		for _, rec := range records {
			copy(recBuf[:80], rec.Username[:])
			binary.LittleEndian.PutUint64(recBuf[80:88], uint64(rec.UserID))
			recBuf[88] = IndexLineTerminatorV1
			buf = append(buf, recBuf[:]...)
		}

		if _, err := f.Write(buf); err != nil {
			return err
		}

		return f.Sync()
	}()

	if closeErr := f.Close(); writeErr == nil {
		writeErr = closeErr
	}

	if writeErr != nil {
		os.Remove(tmpFile)
		return writeErr
	}

	return os.Rename(tmpFile, idx.Filename)
}