backends: don't detect backends when initializing db based vcs-instance.

This skips some calls back to vcsserver.

rhodecode/lib/vcs/backends/__init__.py

@@ -1,87 +1,95 b''
 # -*- coding: utf-8 -*-
 
 # Copyright (C) 2014-2016  RhodeCode GmbH
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU Affero General Public License, version 3
 # (only), as published by the Free Software Foundation.
 #
 # 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 Affero General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #
 # This program is dual-licensed. If you wish to learn more about the
 # RhodeCode Enterprise Edition, including its added features, Support services,
 # and proprietary license terms, please see https://rhodecode.com/licenses/
 
 """
 VCS Backends module
 """
 
+import os
 import logging
 
 from pprint import pformat
 
 from rhodecode.lib.vcs.conf import settings
 from rhodecode.lib.vcs.exceptions import VCSError
 from rhodecode.lib.vcs.utils.helpers import get_scm
 from rhodecode.lib.vcs.utils.imports import import_class
 
 
 log = logging.getLogger(__name__)
 
 
 def get_vcs_instance(repo_path, *args, **kwargs):
     """
     Given a path to a repository an instance of the corresponding vcs backend
     repository class is created and returned. If no repository can be found
     for the path it returns None. Arguments and keyword arguments are passed
     to the vcs backend repository class.
     """
+    explicit_vcs_alias = kwargs.pop('_vcs_alias', None)
     try:
-        vcs_alias = get_scm(repo_path)[0]
+        vcs_alias = explicit_vcs_alias or get_scm(repo_path)[0]
         log.debug(
             'Creating instance of %s repository from %s', vcs_alias, repo_path)
         backend = get_backend(vcs_alias)
+
+        if explicit_vcs_alias:
+            # do final verification of existance of the path, this does the
+            # same as get_scm() call which we skip in explicit_vcs_alias
+            if not os.path.isdir(repo_path):
+                raise VCSError("Given path %s is not a directory" % repo_path)
     except VCSError:
         log.exception(
             'Perhaps this repository is in db and not in '
             'filesystem run rescan repositories with '
             '"destroy old data" option from admin panel')
         return None
 
     return backend(repo_path=repo_path, *args, **kwargs)
 
 
 def get_backend(alias):
     """
     Returns ``Repository`` class identified by the given alias or raises
     VCSError if alias is not recognized or backend class cannot be imported.
     """
     if alias not in settings.BACKENDS:
         raise VCSError(
             "Given alias '%s' is not recognized! Allowed aliases:\n%s" %
             (alias, pformat(settings.BACKENDS.keys())))
     backend_path = settings.BACKENDS[alias]
     klass = import_class(backend_path)
     return klass
 
 
 def get_supported_backends():
     """
     Returns list of aliases of supported backends.
     """
     return settings.BACKENDS.keys()
 
 
 def get_vcsserver_version():
     from rhodecode.lib.vcs import connection
     data = connection.Service.get_vcsserver_service_data()
     if data and 'version' in data:
         return data['version']
 
     return None