Checks what version of git is installed in system, and issues a warning

    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

@decorator.decorator

def jsonify(func, *args, **kwargs):

    """Action decorator that formats output for JSON

    Given a function that will return content, this decorator will turn

    the result into JSON, with a content-type of 'application/json' and

    output it.

    """

    from pylons.decorators.util import get_pylons

    from kallithea.lib.compat import json

    pylons = get_pylons(args)

    pylons.response.headers['Content-Type'] = 'application/json; charset=utf-8'

    data = func(*args, **kwargs)

    if isinstance(data, (list, tuple)):

        msg = "JSON responses with Array envelopes are susceptible to " \

              "cross-site data leak attacks, see " \

        warnings.warn(msg, Warning, 2)

        log.warning(msg)

    log.debug("Returning JSON wrapped action output")

    return json.dumps(data, encoding='utf-8')

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

# CACHE RELATED METHODS

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

# set cache regions for beaker so celery can utilise it

def setup_cache_regions(settings):

    cache_settings = {'regions': None}

    for key in settings.keys():

        for prefix in ['beaker.cache.', 'cache.']:

            if key.startswith(prefix):

                name = key.split(prefix)[1].strip()

                cache_settings[name] = settings[key].strip()

    if cache_settings['regions']:

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

            region = region.strip()

            region_settings = {}

            for key, value in cache_settings.items():

                if key.startswith(region):

                    region_settings[key.split('.')[1]] = value

            region_settings['expire'] = int(region_settings.get('expire',

                                                                60))

            region_settings.setdefault('lock_dir',

                                       cache_settings.get('lock_dir'))

            region_settings.setdefault('data_dir',

                                       cache_settings.get('data_dir'))

            if 'type' not in region_settings:

                region_settings['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)