if it's too old for Kallithea to work properly.

    """

    from kallithea import BACKENDS

    from kallithea.lib.vcs.backends.git.repository import GitRepository

    from kallithea.lib.vcs.conf import settings

    from distutils.version import StrictVersion

    if 'git' not in BACKENDS:

        return None

    stdout, stderr = GitRepository._run_git_command(['--version'], _bare=True,

                                                    _safe=True)

    m = re.search("\d+.\d+.\d+", stdout)

    if m:

        ver = StrictVersion(m.group(0))

    else:

        ver = StrictVersion('0.0.0')

    req_ver = StrictVersion('1.7.4')

    log.debug('Git executable: "%s" version %s detected: %s',

              settings.GIT_EXECUTABLE_PATH, ver, stdout)

    if stderr:

        log.warning('Error detecting git version: %r', stderr)

    elif ver < req_ver:

        log.warning('Kallithea detected git version %s, which is too old '

                    'for the system to function properly. '

                    'Please upgrade to version %s or later.' % (ver, req_ver))

    return ver

#===============================================================================

# CACHE RELATED METHODS

#===============================================================================

# set cache regions for beaker so celery can utilise it

def setup_cache_regions(settings):

    # Create dict with just beaker cache configs with prefix stripped

    cache_settings = {'regions': None}

    prefix = 'beaker.cache.'

    for key in settings:

        if key.startswith(prefix):

            name = key[len(prefix):]

            cache_settings[name] = settings[key]

    # Find all regions, apply defaults, and apply to beaker

    if cache_settings['regions']:

        for region in cache_settings['regions'].split(','):

            region_settings = {}

            for key in cache_settings:

                    region_settings[name] = cache_settings[key]

            region_settings.setdefault('expire',

                                       cache_settings.get('expire', '60'))

            region_settings.setdefault('lock_dir',

                                       cache_settings.get('lock_dir'))

            region_settings.setdefault('data_dir',

                                       cache_settings.get('data_dir'))

            region_settings.setdefault('type',

                                       cache_settings.get('type', 'memory'))

            beaker.cache.cache_regions[region] = region_settings

def conditional_cache(region, prefix, condition, func):

    """

    Conditional caching function use like::

        def _c(arg):

            #heavy computation function

            return data

        # depending from condition the compute is wrapped in cache or not

        compute = conditional_cache('short_term', 'cache_desc', condition=True, func=func)

        return compute(arg)

    :param region: name of cache region

    :param prefix: cache region prefix

    :param condition: condition for cache to be triggered, and return data cached

    :param func: wrapped heavy function to compute

    """

    wrapped = func

    if condition:

        log.debug('conditional_cache: True, wrapping call of '

                  'func: %s into %s region cache' % (region, func))

        wrapped = _cache_decorate((prefix,), None, None, region)(func)

    return wrapped