def optimize_readahead_window()

in src/mount_efs/__init__.py [0:0]

• 31 lines of code
• 4 McCabe index (conditional complexity)

def optimize_readahead_window(mountpoint, options, config):
    if not should_revise_readahead(config):
        return

    fixed_readahead_kb = int(
        DEFAULT_NFS_MAX_READAHEAD_MULTIPLIER * int(options["rsize"]) / 1024
    )

    try:
        major, minor = decode_device_number(os.stat(mountpoint).st_dev)
        # modify read_ahead_kb in /sys/class/bdi/<bdi>/read_ahead_kb
        # The bdi identifier is in the form of MAJOR:MINOR, which can be derived from device number
        #
        read_ahead_kb_config_file = NFS_READAHEAD_CONFIG_PATH_FORMAT % (major, minor)

        logging.debug(
            "Modifying value in %s to %s.",
            read_ahead_kb_config_file,
            str(fixed_readahead_kb),
        )
        p = subprocess.Popen(
            "echo %s > %s" % (fixed_readahead_kb, read_ahead_kb_config_file),
            shell=True,
            stderr=subprocess.PIPE,
            stdout=subprocess.DEVNULL,
        )
        _, error = p.communicate()
        if p.returncode != 0:
            logging.warning(
                'Failed to modify read_ahead_kb: %s with returncode: %d, error: "%s".'
                % (fixed_readahead_kb, p.returncode, error.strip())
            )
    except Exception as e:
        logging.warning(
            'Failed to modify read_ahead_kb: %s with error: "%s".'
            % (fixed_readahead_kb, e)
        )