Read all hashes that have been used since the last call to purge (or reset_hashes).

    :rtype: dict
    :returns: A dictionary of sets of hashes organized by type

def read_used():
    """
    Read all hashes that have been used since the last call to purge (or reset_hashes).

    :rtype: dict
    :returns: A dictionary of sets of hashes organized by type
    """
    used_hashes = {"evs": set([]),
                   "cache": set([]),
                   "seeds": set([])}

    with open(LOG_FILEPATH, 'rb') as logfile:
        for line in logfile.readlines():
            kind, hash = tuple(line.split('...'))
            used_hashes[kind].add(hash.rstrip())

    return used_hashes