diskcache/tests/utils.py

import os
import subprocess as sp


def percentile(sequence, percent):
    if not sequence:
        return None

    values = sorted(sequence)

    if percent == 0:
        return values[0]

    pos = int(len(values) * percent) - 1

    return values[pos]


def secs(value):
    units = ['s ', 'ms', 'us', 'ns']

    if value is None:
        return '  0.000ns'
    elif value == 0:
        return '  0.000ns'
    else:
        for unit in units:
            if value > 1:
                return '%7.3f' % value + unit
            else:
                value *= 1000


def run(*args):
    """Run command, print output, and return output."""
    print('utils$', *args)
    result = sp.check_output(args)
    print(result)
    return result.strip()


def mount_ramdisk(size, path):
    """Mount RAM disk at `path` with `size` in bytes."""
    sectors = size / 512

    os.makedirs(path)

    dev_path = run('hdid', '-nomount', 'ram://%d' % sectors)
    run('newfs_hfs', '-v', 'RAMdisk', dev_path)
    run('mount', '-o', 'noatime', '-t', 'hfs', dev_path, path)

    return dev_path


def unmount_ramdisk(dev_path, path):
    """Unmount RAM disk with `dev_path` and `path`."""
    run('umount', path)
    run('diskutil', 'eject', dev_path)
    run('rm', '-r', path)


def display(name, timings):
    cols = ('Action', 'Count', 'Miss', 'Median', 'P90', 'P99', 'Max', 'Total')
    template = ' '.join(['%9s'] * len(cols))

    print()
    print(' '.join(['=' * 9] * len(cols)))
    print('Timings for %s' % name)
    print('-'.join(['-' * 9] * len(cols)))
    print(template % cols)
    print(' '.join(['=' * 9] * len(cols)))

    len_total = sum_total = 0

    for action in ['get', 'set', 'delete']:
        values = timings[action]
        len_total += len(values)
        sum_total += sum(values)

        print(
            template
            % (
                action,
                len(values),
                len(timings.get(action + '-miss', [])),
                secs(percentile(values, 0.5)),
                secs(percentile(values, 0.9)),
                secs(percentile(values, 0.99)),
                secs(percentile(values, 1.0)),
                secs(sum(values)),
            )
        )

    totals = ('Total', len_total, '', '', '', '', '', secs(sum_total))
    print(template % totals)
    print(' '.join(['=' * 9] * len(cols)))
    print()