// flock acquires an advisory lock on a file descriptor. func flock(db *DB, exclusive bool, timeout time.Duration) error { … } // funlock releases an advisory lock on a file descriptor. func funlock(db *DB) error { … } // mmap memory maps a DB's data file. func mmap(db *DB, sz int) error { … } // munmap unmaps a DB's data file from memory. func munmap(db *DB) error { … }