Changeset - f83326e2e66c
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Mads Kiilerich - 6 years ago 2020-03-06 18:10:02
mads@kiilerich.com
hg: read everything from hgrc, without config section whitelisting (Issue #246)

The whitelisting seems pointless, is hard to maintain, and can't be customized.

Also, mercurial.localrepo.instance will read the full config file anyway.
1 file changed with 2 insertions and 24 deletions:
0 comments (0 inline, 0 general)
kallithea/lib/utils.py
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# -*- coding: utf-8 -*-
 
# This program is free software: you can redistribute it and/or modify
 
# it under the terms of the GNU General Public License as published by
 
# the Free Software Foundation, either version 3 of the License, or
 
# (at your option) any later version.
 
#
 
# This program is distributed in the hope that it will be useful,
 
# but WITHOUT ANY WARRANTY; without even the implied warranty of
 
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 
# GNU General Public License for more details.
 
#
 
# You should have received a copy of the GNU General Public License
 
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
"""
 
kallithea.lib.utils
 
~~~~~~~~~~~~~~~~~~~
 

	
 
Utilities library for Kallithea
 

	
 
This file was forked by the Kallithea project in July 2014.
 
Original author and date, and relevant copyright and licensing information is below:
 
:created_on: Apr 18, 2010
 
:author: marcink
 
:copyright: (c) 2013 RhodeCode GmbH, and others.
 
:license: GPLv3, see LICENSE.md for more details.
 
"""
 

	
 
import datetime
 
import logging
 
import os
 
import re
 
import sys
 
import traceback
 
import urllib.error
 
from distutils.version import StrictVersion
 

	
 
import beaker.cache
 
import mercurial.config
 
import mercurial.ui
 

	
 
import kallithea.config.conf
 
from kallithea.lib.exceptions import InvalidCloneUriException
 
from kallithea.lib.utils2 import ascii_bytes, aslist, get_current_authuser, safe_bytes, safe_str
 
from kallithea.lib.vcs.backends.git.repository import GitRepository
 
from kallithea.lib.vcs.backends.hg.repository import MercurialRepository
 
from kallithea.lib.vcs.conf import settings
 
from kallithea.lib.vcs.exceptions import RepositoryError, VCSError
 
from kallithea.lib.vcs.utils.fakemod import create_module
 
from kallithea.lib.vcs.utils.helpers import get_scm
 
from kallithea.model import meta
 
from kallithea.model.db import RepoGroup, Repository, Setting, Ui, User, UserGroup, UserLog
 

	
 

	
 
log = logging.getLogger(__name__)
 

	
 
REMOVED_REPO_PAT = re.compile(r'rm__\d{8}_\d{6}_\d{6}_.*')
 

	
 

	
 
#==============================================================================
 
# PERM DECORATOR HELPERS FOR EXTRACTING NAMES FOR PERM CHECKS
 
#==============================================================================
 
def get_repo_slug(request):
 
    _repo = request.environ['pylons.routes_dict'].get('repo_name')
 
    if _repo:
 
        _repo = _repo.rstrip('/')
 
    return _repo
 

	
 

	
 
def get_repo_group_slug(request):
 
    _group = request.environ['pylons.routes_dict'].get('group_name')
 
    if _group:
 
        _group = _group.rstrip('/')
 
    return _group
 

	
 

	
 
def get_user_group_slug(request):
 
    _group = request.environ['pylons.routes_dict'].get('id')
 
    _group = UserGroup.get(_group)
 
    if _group:
 
        return _group.users_group_name
 
    return None
 

	
 

	
 
def _get_permanent_id(s):
 
    """Helper for decoding stable URLs with repo ID. For a string like '_123'
 
    return 123.
 
    """
 
    by_id_match = re.match(r'^_(\d+)$', s)
 
    if by_id_match is None:
 
        return None
 
    return int(by_id_match.group(1))
 

	
 

	
 
def fix_repo_id_name(path):
 
    """
 
    Rewrite repo_name for _<ID> permanent URLs.
 

	
 
    Given a path, if the first path element is like _<ID>, return the path with
 
    this part expanded to the corresponding full repo name, else return the
 
    provided path.
 
    """
 
    first, rest = path, ''
 
    if '/' in path:
 
        first, rest_ = path.split('/', 1)
 
        rest = '/' + rest_
 
    repo_id = _get_permanent_id(first)
 
    if repo_id is not None:
 
        repo = Repository.get(repo_id)
 
        if repo is not None:
 
            return repo.repo_name + rest
 
    return path
 

	
 

	
 
def action_logger(user, action, repo, ipaddr='', commit=False):
 
    """
 
    Action logger for various actions made by users
 

	
 
    :param user: user that made this action, can be a unique username string or
 
        object containing user_id attribute
 
    :param action: action to log, should be on of predefined unique actions for
 
        easy translations
 
    :param repo: string name of repository or object containing repo_id,
 
        that action was made on
 
    :param ipaddr: optional IP address from what the action was made
 

	
 
    """
 

	
 
    # if we don't get explicit IP address try to get one from registered user
 
    # in tmpl context var
 
    if not ipaddr:
 
        ipaddr = getattr(get_current_authuser(), 'ip_addr', '')
 

	
 
    if getattr(user, 'user_id', None):
 
        user_obj = User.get(user.user_id)
 
    elif isinstance(user, str):
 
        user_obj = User.get_by_username(user)
 
    else:
 
        raise Exception('You have to provide a user object or a username')
 

	
 
    if getattr(repo, 'repo_id', None):
 
        repo_obj = Repository.get(repo.repo_id)
 
        repo_name = repo_obj.repo_name
 
    elif isinstance(repo, str):
 
        repo_name = repo.lstrip('/')
 
        repo_obj = Repository.get_by_repo_name(repo_name)
 
    else:
 
        repo_obj = None
 
        repo_name = ''
 

	
 
    user_log = UserLog()
 
    user_log.user_id = user_obj.user_id
 
    user_log.username = user_obj.username
 
    user_log.action = action
 

	
 
    user_log.repository = repo_obj
 
    user_log.repository_name = repo_name
 

	
 
    user_log.action_date = datetime.datetime.now()
 
    user_log.user_ip = ipaddr
 
    meta.Session().add(user_log)
 

	
 
    log.info('Logging action:%s on %s by user:%s ip:%s',
 
             action, repo, user_obj, ipaddr)
 
    if commit:
 
        meta.Session().commit()
 

	
 

	
 
def get_filesystem_repos(path):
 
    """
 
    Scans given path for repos and return (name,(type,path)) tuple
 

	
 
    :param path: path to scan for repositories
 
    :param recursive: recursive search and return names with subdirs in front
 
    """
 

	
 
    # remove ending slash for better results
 
    path = path.rstrip(os.sep)
 
    log.debug('now scanning in %s', path)
 

	
 
    def isdir(*n):
 
        return os.path.isdir(os.path.join(*n))
 

	
 
    for root, dirs, _files in os.walk(path):
 
        recurse_dirs = []
 
        for subdir in dirs:
 
            # skip removed repos
 
            if REMOVED_REPO_PAT.match(subdir):
 
                continue
 

	
 
            # skip .<something> dirs TODO: rly? then we should prevent creating them ...
 
            if subdir.startswith('.'):
 
                continue
 

	
 
            cur_path = os.path.join(root, subdir)
 
            if isdir(cur_path, '.git'):
 
                log.warning('ignoring non-bare Git repo: %s', cur_path)
 
                continue
 

	
 
            if (isdir(cur_path, '.hg') or
 
                isdir(cur_path, '.svn') or
 
                isdir(cur_path, 'objects') and (isdir(cur_path, 'refs') or
 
                                                os.path.isfile(os.path.join(cur_path, 'packed-refs')))):
 

	
 
                if not os.access(cur_path, os.R_OK) or not os.access(cur_path, os.X_OK):
 
                    log.warning('ignoring repo path without access: %s', cur_path)
 
                    continue
 

	
 
                if not os.access(cur_path, os.W_OK):
 
                    log.warning('repo path without write access: %s', cur_path)
 

	
 
                try:
 
                    scm_info = get_scm(cur_path)
 
                    assert cur_path.startswith(path)
 
                    repo_path = cur_path[len(path) + 1:]
 
                    yield repo_path, scm_info
 
                    continue # no recursion
 
                except VCSError:
 
                    # We should perhaps ignore such broken repos, but especially
 
                    # the bare git detection is unreliable so we dive into it
 
                    pass
 

	
 
            recurse_dirs.append(subdir)
 

	
 
        dirs[:] = recurse_dirs
 

	
 

	
 
def is_valid_repo_uri(repo_type, url, ui):
 
    """Check if the url seems like a valid remote repo location
 
    Raise InvalidCloneUriException if any problems"""
 
    if repo_type == 'hg':
 
        if url.startswith('http') or url.startswith('ssh'):
 
            # initially check if it's at least the proper URL
 
            # or does it pass basic auth
 
            try:
 
                MercurialRepository._check_url(url, ui)
 
            except urllib.error.URLError as e:
 
                raise InvalidCloneUriException('URI %s URLError: %s' % (url, e))
 
        elif url.startswith('svn+http'):
 
            try:
 
                from hgsubversion.svnrepo import svnremoterepo
 
            except ImportError:
 
                raise InvalidCloneUriException('URI type %s not supported - hgsubversion is not available' % (url,))
 
            svnremoterepo(ui, url).svn.uuid
 
        elif url.startswith('git+http'):
 
            raise InvalidCloneUriException('URI type %s not implemented' % (url,))
 
        else:
 
            raise InvalidCloneUriException('URI %s not allowed' % (url,))
 

	
 
    elif repo_type == 'git':
 
        if url.startswith('http') or url.startswith('git'):
 
            # initially check if it's at least the proper URL
 
            # or does it pass basic auth
 
            try:
 
                GitRepository._check_url(url)
 
            except urllib.error.URLError as e:
 
                raise InvalidCloneUriException('URI %s URLError: %s' % (url, e))
 
        elif url.startswith('svn+http'):
 
            raise InvalidCloneUriException('URI type %s not implemented' % (url,))
 
        elif url.startswith('hg+http'):
 
            raise InvalidCloneUriException('URI type %s not implemented' % (url,))
 
        else:
 
            raise InvalidCloneUriException('URI %s not allowed' % (url))
 

	
 

	
 
def is_valid_repo(repo_name, base_path, scm=None):
 
    """
 
    Returns True if given path is a valid repository False otherwise.
 
    If scm param is given also compare if given scm is the same as expected
 
    from scm parameter
 

	
 
    :param repo_name:
 
    :param base_path:
 
    :param scm:
 

	
 
    :return True: if given path is a valid repository
 
    """
 
    # TODO: paranoid security checks?
 
    full_path = os.path.join(base_path, repo_name)
 

	
 
    try:
 
        scm_ = get_scm(full_path)
 
        if scm:
 
            return scm_[0] == scm
 
        return True
 
    except VCSError:
 
        return False
 

	
 

	
 
def is_valid_repo_group(repo_group_name, base_path, skip_path_check=False):
 
    """
 
    Returns True if given path is a repository group False otherwise
 

	
 
    :param repo_name:
 
    :param base_path:
 
    """
 
    full_path = os.path.join(base_path, repo_group_name)
 

	
 
    # check if it's not a repo
 
    if is_valid_repo(repo_group_name, base_path):
 
        return False
 

	
 
    try:
 
        # we need to check bare git repos at higher level
 
        # since we might match branches/hooks/info/objects or possible
 
        # other things inside bare git repo
 
        get_scm(os.path.dirname(full_path))
 
        return False
 
    except VCSError:
 
        pass
 

	
 
    # check if it's a valid path
 
    if skip_path_check or os.path.isdir(full_path):
 
        return True
 

	
 
    return False
 

	
 

	
 
# propagated from mercurial documentation
 
ui_sections = ['alias', 'auth',
 
                'decode/encode', 'defaults',
 
                'diff', 'email',
 
                'extensions', 'format',
 
                'merge-patterns', 'merge-tools',
 
                'hooks', 'http_proxy',
 
                'smtp', 'patch',
 
                'paths', 'profiling',
 
                'server', 'trusted',
 
                'ui', 'web', ]
 

	
 

	
 
def make_ui(repo_path=None):
 
    """
 
    Create an Mercurial 'ui' object based on database Ui settings, possibly
 
    augmenting with content from a hgrc file.
 
    """
 
    baseui = mercurial.ui.ui()
 

	
 
    # clean the baseui object
 
    baseui._ocfg = mercurial.config.config()
 
    baseui._ucfg = mercurial.config.config()
 
    baseui._tcfg = mercurial.config.config()
 

	
 
    sa = meta.Session()
 
    for ui_ in sa.query(Ui).order_by(Ui.ui_section, Ui.ui_key):
 
        if ui_.ui_active:
 
            log.debug('config from db: [%s] %s=%r', ui_.ui_section,
 
                      ui_.ui_key, ui_.ui_value)
 
            baseui.setconfig(ascii_bytes(ui_.ui_section), ascii_bytes(ui_.ui_key),
 
                             b'' if ui_.ui_value is None else safe_bytes(ui_.ui_value))
 

	
 
    # force set push_ssl requirement to False, Kallithea handles that
 
    baseui.setconfig(b'web', b'push_ssl', False)
 
    baseui.setconfig(b'web', b'allow_push', b'*')
 
    # prevent interactive questions for ssh password / passphrase
 
    ssh = baseui.config(b'ui', b'ssh', default=b'ssh')
 
    baseui.setconfig(b'ui', b'ssh', b'%s -oBatchMode=yes -oIdentitiesOnly=yes' % ssh)
 
    # push / pull hooks
 
    baseui.setconfig(b'hooks', b'changegroup.kallithea_log_push_action', b'python:kallithea.lib.hooks.log_push_action')
 
    baseui.setconfig(b'hooks', b'outgoing.kallithea_log_pull_action', b'python:kallithea.lib.hooks.log_pull_action')
 

	
 
    if repo_path is not None:
 
        hgrc_path = os.path.join(repo_path, '.hg', 'hgrc')
 
        if os.path.isfile(hgrc_path):
 
            log.debug('reading hgrc from %s', hgrc_path)
 
            cfg = mercurial.config.config()
 
            cfg.read(safe_bytes(hgrc_path))
 
            for section in ui_sections:
 
                for k, v in cfg.items(section):
 
                    log.debug('config from file: [%s] %s=%s', section, k, v)
 
                    baseui.setconfig(ascii_bytes(section), ascii_bytes(k), safe_bytes(v))
 
        else:
 
            log.debug('hgrc file is not present at %s, skipping...', hgrc_path)
 
        # Note: MercurialRepository / mercurial.localrepo.instance will do this too, so it will always be possible to override db settings or what is hardcoded above
 
        baseui.readconfig(repo_path)
 

	
 
    assert baseui.plain()  # set by hgcompat.monkey_do (invoked from import of vcs.backends.hg) to minimize potential impact of loading config files
 
    return baseui
 

	
 

	
 
def set_app_settings(config):
 
    """
 
    Updates app config with new settings from database
 

	
 
    :param config:
 
    """
 
    hgsettings = Setting.get_app_settings()
 
    for k, v in hgsettings.items():
 
        config[k] = v
 

	
 

	
 
def set_vcs_config(config):
 
    """
 
    Patch VCS config with some Kallithea specific stuff
 

	
 
    :param config: kallithea.CONFIG
 
    """
 
    settings.BACKENDS = {
 
        'hg': 'kallithea.lib.vcs.backends.hg.MercurialRepository',
 
        'git': 'kallithea.lib.vcs.backends.git.GitRepository',
 
    }
 

	
 
    settings.GIT_EXECUTABLE_PATH = config.get('git_path', 'git')
 
    settings.GIT_REV_FILTER = config.get('git_rev_filter', '--all').strip()
 
    settings.DEFAULT_ENCODINGS = aslist(config.get('default_encoding',
 
                                                        'utf-8'), sep=',')
 

	
 

	
 
def set_indexer_config(config):
 
    """
 
    Update Whoosh index mapping
 

	
 
    :param config: kallithea.CONFIG
 
    """
 
    log.debug('adding extra into INDEX_EXTENSIONS')
 
    kallithea.config.conf.INDEX_EXTENSIONS.extend(re.split(r'\s+', config.get('index.extensions', '')))
 

	
 
    log.debug('adding extra into INDEX_FILENAMES')
 
    kallithea.config.conf.INDEX_FILENAMES.extend(re.split(r'\s+', config.get('index.filenames', '')))
 

	
 

	
 
def map_groups(path):
 
    """
 
    Given a full path to a repository, create all nested groups that this
 
    repo is inside. This function creates parent-child relationships between
 
    groups and creates default perms for all new groups.
 

	
 
    :param paths: full path to repository
 
    """
 
    from kallithea.model.repo_group import RepoGroupModel
 
    sa = meta.Session()
 
    groups = path.split(Repository.url_sep())
 
    parent = None
 
    group = None
 

	
 
    # last element is repo in nested groups structure
 
    groups = groups[:-1]
 
    rgm = RepoGroupModel()
 
    owner = User.get_first_admin()
 
    for lvl, group_name in enumerate(groups):
 
        group_name = '/'.join(groups[:lvl] + [group_name])
 
        group = RepoGroup.get_by_group_name(group_name)
 
        desc = '%s group' % group_name
 

	
 
        # skip folders that are now removed repos
 
        if REMOVED_REPO_PAT.match(group_name):
 
            break
 

	
 
        if group is None:
 
            log.debug('creating group level: %s group_name: %s',
 
                      lvl, group_name)
 
            group = RepoGroup(group_name, parent)
 
            group.group_description = desc
 
            group.owner = owner
 
            sa.add(group)
 
            rgm._create_default_perms(group)
 
            sa.flush()
 

	
 
        parent = group
 
    return group
 

	
 

	
 
def repo2db_mapper(initial_repo_dict, remove_obsolete=False,
 
                   install_git_hooks=False, user=None, overwrite_git_hooks=False):
 
    """
 
    maps all repos given in initial_repo_dict, non existing repositories
 
    are created, if remove_obsolete is True it also check for db entries
 
    that are not in initial_repo_dict and removes them.
 

	
 
    :param initial_repo_dict: mapping with repositories found by scanning methods
 
    :param remove_obsolete: check for obsolete entries in database
 
    :param install_git_hooks: if this is True, also check and install git hook
 
        for a repo if missing
 
    :param overwrite_git_hooks: if this is True, overwrite any existing git hooks
 
        that may be encountered (even if user-deployed)
 
    """
 
    from kallithea.model.repo import RepoModel
 
    from kallithea.model.scm import ScmModel
 
    sa = meta.Session()
 
    repo_model = RepoModel()
 
    if user is None:
 
        user = User.get_first_admin()
 
    added = []
 

	
 
    # creation defaults
 
    defs = Setting.get_default_repo_settings(strip_prefix=True)
 
    enable_statistics = defs.get('repo_enable_statistics')
 
    enable_downloads = defs.get('repo_enable_downloads')
 
    private = defs.get('repo_private')
 

	
 
    for name, repo in initial_repo_dict.items():
 
        group = map_groups(name)
 
        db_repo = repo_model.get_by_repo_name(name)
 
        # found repo that is on filesystem not in Kallithea database
 
        if not db_repo:
 
            log.info('repository %s not found, creating now', name)
 
            added.append(name)
 
            desc = (repo.description
 
                    if repo.description != 'unknown'
 
                    else '%s repository' % name)
 

	
 
            new_repo = repo_model._create_repo(
 
                repo_name=name,
 
                repo_type=repo.alias,
 
                description=desc,
 
                repo_group=getattr(group, 'group_id', None),
 
                owner=user,
 
                enable_downloads=enable_downloads,
 
                enable_statistics=enable_statistics,
 
                private=private,
 
                state=Repository.STATE_CREATED
 
            )
 
            sa.commit()
 
            # we added that repo just now, and make sure it has githook
 
            # installed, and updated server info
 
            if new_repo.repo_type == 'git':
 
                git_repo = new_repo.scm_instance
 
                ScmModel().install_git_hooks(git_repo)
 
                # update repository server-info
 
                log.debug('Running update server info')
 
                git_repo._update_server_info()
 
            new_repo.update_changeset_cache()
 
        elif install_git_hooks:
 
            if db_repo.repo_type == 'git':
 
                ScmModel().install_git_hooks(db_repo.scm_instance, force_create=overwrite_git_hooks)
 

	
 
    removed = []
 
    # remove from database those repositories that are not in the filesystem
 
    for repo in sa.query(Repository).all():
 
        if repo.repo_name not in initial_repo_dict:
 
            if remove_obsolete:
 
                log.debug("Removing non-existing repository found in db `%s`",
 
                          repo.repo_name)
 
                try:
 
                    RepoModel().delete(repo, forks='detach', fs_remove=False)
 
                    sa.commit()
 
                except Exception:
 
                    #don't hold further removals on error
 
                    log.error(traceback.format_exc())
 
                    sa.rollback()
 
            removed.append(repo.repo_name)
 
    return added, removed
 

	
 

	
 
def load_rcextensions(root_path):
 
    path = os.path.join(root_path, 'rcextensions', '__init__.py')
 
    if os.path.isfile(path):
 
        rcext = create_module('rc', path)
 
        EXT = kallithea.EXTENSIONS = rcext
 
        log.debug('Found rcextensions now loading %s...', rcext)
 

	
 
        # Additional mappings that are not present in the pygments lexers
 
        kallithea.config.conf.LANGUAGES_EXTENSIONS_MAP.update(getattr(EXT, 'EXTRA_MAPPINGS', {}))
 

	
 
        # OVERRIDE OUR EXTENSIONS FROM RC-EXTENSIONS (if present)
 

	
 
        if getattr(EXT, 'INDEX_EXTENSIONS', []):
 
            log.debug('settings custom INDEX_EXTENSIONS')
 
            kallithea.config.conf.INDEX_EXTENSIONS = getattr(EXT, 'INDEX_EXTENSIONS', [])
 

	
 
        # ADDITIONAL MAPPINGS
 
        log.debug('adding extra into INDEX_EXTENSIONS')
 
        kallithea.config.conf.INDEX_EXTENSIONS.extend(getattr(EXT, 'EXTRA_INDEX_EXTENSIONS', []))
 

	
 
        # auto check if the module is not missing any data, set to default if is
 
        # this will help autoupdate new feature of rcext module
 
        #from kallithea.config import rcextensions
 
        #for k in dir(rcextensions):
 
        #    if not k.startswith('_') and not hasattr(EXT, k):
 
        #        setattr(EXT, k, getattr(rcextensions, k))
 

	
 

	
 
#==============================================================================
 
# MISC
 
#==============================================================================
 

	
 
git_req_ver = StrictVersion('1.7.4')
 

	
 
def check_git_version():
 
    """
 
    Checks what version of git is installed on the system, and raise a system exit
 
    if it's too old for Kallithea to work properly.
 
    """
 
    if 'git' not in kallithea.BACKENDS:
 
        return None
 

	
 
    if not settings.GIT_EXECUTABLE_PATH:
 
        log.warning('No git executable configured - check "git_path" in the ini file.')
 
        return None
 

	
 
    try:
 
        stdout, stderr = GitRepository._run_git_command(['--version'])
 
    except RepositoryError as e:
 
        # message will already have been logged as error
 
        log.warning('No working git executable found - check "git_path" in the ini file.')
 
        return None
 

	
 
    if stderr:
 
        log.warning('Error/stderr from "%s --version":\n%s', settings.GIT_EXECUTABLE_PATH, safe_str(stderr))
 

	
 
    if not stdout:
 
        log.warning('No working git executable found - check "git_path" in the ini file.')
 
        return None
 

	
 
    output = safe_str(stdout).strip()
 
    m = re.search(r"\d+.\d+.\d+", output)
 
    if m:
 
        ver = StrictVersion(m.group(0))
 
        log.debug('Git executable: "%s", version %s (parsed from: "%s")',
 
                  settings.GIT_EXECUTABLE_PATH, ver, output)
 
        if ver < git_req_ver:
 
            log.error('Kallithea detected %s version %s, which is too old '
 
                      'for the system to function properly. '
 
                      'Please upgrade to version %s or later. '
 
                      'If you strictly need Mercurial repositories, you can '
 
                      'clear the "git_path" setting in the ini file.',
 
                      settings.GIT_EXECUTABLE_PATH, ver, git_req_ver)
 
            log.error("Terminating ...")
 
            sys.exit(1)
 
    else:
 
        ver = StrictVersion('0.0.0')
 
        log.warning('Error finding version number in "%s --version" stdout:\n%s',
 
                    settings.GIT_EXECUTABLE_PATH, output)
 

	
 
    return ver
 

	
 

	
 
#===============================================================================
 
# CACHE RELATED METHODS
 
#===============================================================================
 

	
 
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 = beaker.cache._cache_decorate((prefix,), None, None, region)(func)
 

	
 
    return wrapped
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