pull-requests: optimize db transaction logic.

- we've been investigating this issue with locked pull-requests
- the transactions arround audit-logs and state-lock seems to be fragile for long-running, and exception prone setups
- this change tries to make use of few snapshot transactions to prevent a long ones, and actually try to recover on failed audit-log calls.

rhodecode/lib/audit_logger.py

@@ -1,298 +1,303 b''
 # -*- coding: utf-8 -*-
 
 # Copyright (C) 2017-2020 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/
 
 import logging
 import datetime
 
 from rhodecode.lib.jsonalchemy import JsonRaw
 from rhodecode.model import meta
 from rhodecode.model.db import User, UserLog, Repository
 
 
 log = logging.getLogger(__name__)
 
 # action as key, and expected action_data as value
 ACTIONS_V1 = {
     'user.login.success': {'user_agent': ''},
     'user.login.failure': {'user_agent': ''},
     'user.logout': {'user_agent': ''},
     'user.register': {},
     'user.password.reset_request': {},
     'user.push': {'user_agent': '', 'commit_ids': []},
     'user.pull': {'user_agent': ''},
 
     'user.create': {'data': {}},
     'user.delete': {'old_data': {}},
     'user.edit': {'old_data': {}},
     'user.edit.permissions': {},
     'user.edit.ip.add': {'ip': {}, 'user': {}},
     'user.edit.ip.delete': {'ip': {}, 'user': {}},
     'user.edit.token.add': {'token': {}, 'user': {}},
     'user.edit.token.delete': {'token': {}, 'user': {}},
     'user.edit.email.add': {'email': ''},
     'user.edit.email.delete': {'email': ''},
     'user.edit.ssh_key.add': {'token': {}, 'user': {}},
     'user.edit.ssh_key.delete': {'token': {}, 'user': {}},
     'user.edit.password_reset.enabled': {},
     'user.edit.password_reset.disabled': {},
 
     'user_group.create': {'data': {}},
     'user_group.delete': {'old_data': {}},
     'user_group.edit': {'old_data': {}},
     'user_group.edit.permissions': {},
     'user_group.edit.member.add': {'user': {}},
     'user_group.edit.member.delete': {'user': {}},
 
     'repo.create': {'data': {}},
     'repo.fork': {'data': {}},
     'repo.edit': {'old_data': {}},
     'repo.edit.permissions': {},
     'repo.edit.permissions.branch': {},
     'repo.archive': {'old_data': {}},
     'repo.delete': {'old_data': {}},
 
     'repo.archive.download': {'user_agent': '', 'archive_name': '',
                               'archive_spec': '', 'archive_cached': ''},
 
     'repo.permissions.branch_rule.create': {},
     'repo.permissions.branch_rule.edit': {},
     'repo.permissions.branch_rule.delete': {},
 
     'repo.pull_request.create': '',
     'repo.pull_request.edit': '',
     'repo.pull_request.delete': '',
     'repo.pull_request.close': '',
     'repo.pull_request.merge': '',
     'repo.pull_request.vote': '',
     'repo.pull_request.comment.create': '',
     'repo.pull_request.comment.edit': '',
     'repo.pull_request.comment.delete': '',
 
     'repo.pull_request.reviewer.add': '',
     'repo.pull_request.reviewer.delete': '',
 
     'repo.pull_request.observer.add': '',
     'repo.pull_request.observer.delete': '',
 
     'repo.commit.strip': {'commit_id': ''},
     'repo.commit.comment.create': {'data': {}},
     'repo.commit.comment.delete': {'data': {}},
     'repo.commit.comment.edit': {'data': {}},
     'repo.commit.vote': '',
 
     'repo.artifact.add': '',
     'repo.artifact.delete': '',
 
     'repo_group.create': {'data': {}},
     'repo_group.edit': {'old_data': {}},
     'repo_group.edit.permissions': {},
     'repo_group.delete': {'old_data': {}},
 }
 
 ACTIONS = ACTIONS_V1
 
 SOURCE_WEB = 'source_web'
 SOURCE_API = 'source_api'
 
 
 class UserWrap(object):
     """
     Fake object used to imitate AuthUser
     """
 
     def __init__(self, user_id=None, username=None, ip_addr=None):
         self.user_id = user_id
         self.username = username
         self.ip_addr = ip_addr
 
 
 class RepoWrap(object):
     """
     Fake object used to imitate RepoObject that audit logger requires
     """
 
     def __init__(self, repo_id=None, repo_name=None):
         self.repo_id = repo_id
         self.repo_name = repo_name
 
 
 def _store_log(action_name, action_data, user_id, username, user_data,
                ip_address, repository_id, repository_name):
     user_log = UserLog()
     user_log.version = UserLog.VERSION_2
 
     user_log.action = action_name
     user_log.action_data = action_data or JsonRaw(u'{}')
 
     user_log.user_ip = ip_address
 
     user_log.user_id = user_id
     user_log.username = username
     user_log.user_data = user_data or JsonRaw(u'{}')
 
     user_log.repository_id = repository_id
     user_log.repository_name = repository_name
 
     user_log.action_date = datetime.datetime.now()
 
     return user_log
 
 
 def store_web(*args, **kwargs):
     action_data = {}
     org_action_data = kwargs.pop('action_data', {})
     action_data.update(org_action_data)
     action_data['source'] = SOURCE_WEB
     kwargs['action_data'] = action_data
 
     return store(*args, **kwargs)
 
 
 def store_api(*args, **kwargs):
     action_data = {}
     org_action_data = kwargs.pop('action_data', {})
     action_data.update(org_action_data)
     action_data['source'] = SOURCE_API
     kwargs['action_data'] = action_data
 
     return store(*args, **kwargs)
 
 
 def store(action, user, action_data=None, user_data=None, ip_addr=None,
           repo=None, sa_session=None, commit=False):
     """
     Audit logger for various actions made by users, typically this
     results in a call such::
 
         from rhodecode.lib import audit_logger
 
         audit_logger.store(
             'repo.edit', user=self._rhodecode_user)
         audit_logger.store(
             'repo.delete', action_data={'data': repo_data},
             user=audit_logger.UserWrap(username='itried-login', ip_addr='8.8.8.8'))
 
         # repo action
         audit_logger.store(
             'repo.delete',
             user=audit_logger.UserWrap(username='itried-login', ip_addr='8.8.8.8'),
             repo=audit_logger.RepoWrap(repo_name='some-repo'))
 
         # repo action, when we know and have the repository object already
         audit_logger.store(
             'repo.delete', action_data={'source': audit_logger.SOURCE_WEB, },
             user=self._rhodecode_user,
             repo=repo_object)
 
         # alternative wrapper to the above
         audit_logger.store_web(
             'repo.delete', action_data={},
             user=self._rhodecode_user,
             repo=repo_object)
 
         # without an user ?
         audit_logger.store(
             'user.login.failure',
             user=audit_logger.UserWrap(
                     username=self.request.params.get('username'),
                     ip_addr=self.request.remote_addr))
 
     """
     from rhodecode.lib.utils2 import safe_unicode
     from rhodecode.lib.auth import AuthUser
 
     action_spec = ACTIONS.get(action, None)
     if action_spec is None:
         raise ValueError('Action `{}` is not supported'.format(action))
 
     if not sa_session:
         sa_session = meta.Session()
 
     try:
         username = getattr(user, 'username', None)
         if not username:
             pass
 
         user_id = getattr(user, 'user_id', None)
         if not user_id:
             # maybe we have username ? Try to figure user_id from username
             if username:
                 user_id = getattr(
                     User.get_by_username(username), 'user_id', None)
 
         ip_addr = ip_addr or getattr(user, 'ip_addr', None)
         if not ip_addr:
             pass
 
         if not user_data:
             # try to get this from the auth user
             if isinstance(user, AuthUser):
                 user_data = {
                     'username': user.username,
                     'email': user.email,
                 }
 
         repository_name = getattr(repo, 'repo_name', None)
         repository_id = getattr(repo, 'repo_id', None)
         if not repository_id:
             # maybe we have repo_name ? Try to figure repo_id from repo_name
             if repository_name:
                 repository_id = getattr(
                     Repository.get_by_repo_name(repository_name), 'repo_id', None)
 
         action_name = safe_unicode(action)
         ip_address = safe_unicode(ip_addr)
 
         with sa_session.no_autoflush:
-            update_user_last_activity(sa_session, user_id)
 
             user_log = _store_log(
                 action_name=action_name,
                 action_data=action_data or {},
                 user_id=user_id,
                 username=username,
                 user_data=user_data or {},
                 ip_address=ip_address,
                 repository_id=repository_id,
                 repository_name=repository_name
             )
 
             sa_session.add(user_log)
+            if commit:
+                sa_session.commit()
+            entry_id = user_log.entry_id or ''
+
+            update_user_last_activity(sa_session, user_id)
 
             if commit:
                 sa_session.commit()
 
-        entry_id = user_log.entry_id or ''
         log.info('AUDIT[%s]: Logging action: `%s` by user:id:%s[%s] ip:%s',
                  entry_id, action_name, user_id, username, ip_address)
 
     except Exception:
         log.exception('AUDIT: failed to store audit log')
 
 
 def update_user_last_activity(sa_session, user_id):
     _last_activity = datetime.datetime.now()
     try:
         sa_session.query(User).filter(User.user_id == user_id).update(
             {"last_activity": _last_activity})
         log.debug(
             'updated user `%s` last activity to:%s', user_id, _last_activity)
     except Exception:
-        log.exception("Failed last activity update")
+        log.exception("Failed last activity update for user_id: %s", user_id)
+        sa_session.rollback()
+

rhodecode/model/pull_request.py

@@ -1,2372 +1,2378 b''
 # -*- coding: utf-8 -*-
 
 # Copyright (C) 2012-2020 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/
 
 
 """
 pull request model for RhodeCode
 """
 
 
 import json
 import logging
 import os
 
 import datetime
 import urllib
 import collections
 
 from pyramid import compat
 from pyramid.threadlocal import get_current_request
 
 from rhodecode.lib.vcs.nodes import FileNode
 from rhodecode.translation import lazy_ugettext
 from rhodecode.lib import helpers as h, hooks_utils, diffs
 from rhodecode.lib import audit_logger
 from rhodecode.lib.compat import OrderedDict
 from rhodecode.lib.hooks_daemon import prepare_callback_daemon
 from rhodecode.lib.markup_renderer import (
     DEFAULT_COMMENTS_RENDERER, RstTemplateRenderer)
 from rhodecode.lib.utils2 import (
     safe_unicode, safe_str, md5_safe, AttributeDict, safe_int,
     get_current_rhodecode_user)
 from rhodecode.lib.vcs.backends.base import (
     Reference, MergeResponse, MergeFailureReason, UpdateFailureReason,
     TargetRefMissing, SourceRefMissing)
 from rhodecode.lib.vcs.conf import settings as vcs_settings
 from rhodecode.lib.vcs.exceptions import (
     CommitDoesNotExistError, EmptyRepositoryError)
 from rhodecode.model import BaseModel
 from rhodecode.model.changeset_status import ChangesetStatusModel
 from rhodecode.model.comment import CommentsModel
 from rhodecode.model.db import (
     aliased, null, lazyload, and_, or_, func, String, cast, PullRequest, PullRequestReviewers, ChangesetStatus,
     PullRequestVersion, ChangesetComment, Repository, RepoReviewRule, User)
 from rhodecode.model.meta import Session
 from rhodecode.model.notification import NotificationModel, \
     EmailNotificationModel
 from rhodecode.model.scm import ScmModel
 from rhodecode.model.settings import VcsSettingsModel
 
 
 log = logging.getLogger(__name__)
 
 
 # Data structure to hold the response data when updating commits during a pull
 # request update.
 class UpdateResponse(object):
 
     def __init__(self, executed, reason, new, old, common_ancestor_id,
                  commit_changes, source_changed, target_changed):
 
         self.executed = executed
         self.reason = reason
         self.new = new
         self.old = old
         self.common_ancestor_id = common_ancestor_id
         self.changes = commit_changes
         self.source_changed = source_changed
         self.target_changed = target_changed
 
 
 def get_diff_info(
         source_repo, source_ref, target_repo, target_ref, get_authors=False,
         get_commit_authors=True):
     """
     Calculates detailed diff information for usage in preview of creation of a pull-request.
     This is also used for default reviewers logic
     """
 
     source_scm = source_repo.scm_instance()
     target_scm = target_repo.scm_instance()
 
     ancestor_id = target_scm.get_common_ancestor(target_ref, source_ref, source_scm)
     if not ancestor_id:
         raise ValueError(
             'cannot calculate diff info without a common ancestor. '
             'Make sure both repositories are related, and have a common forking commit.')
 
     # case here is that want a simple diff without incoming commits,
     # previewing what will be merged based only on commits in the source.
     log.debug('Using ancestor %s as source_ref instead of %s',
               ancestor_id, source_ref)
 
     # source of changes now is the common ancestor
     source_commit = source_scm.get_commit(commit_id=ancestor_id)
     # target commit becomes the source ref as it is the last commit
     # for diff generation this logic gives proper diff
     target_commit = source_scm.get_commit(commit_id=source_ref)
 
     vcs_diff = \
         source_scm.get_diff(commit1=source_commit, commit2=target_commit,
                             ignore_whitespace=False, context=3)
 
     diff_processor = diffs.DiffProcessor(
         vcs_diff, format='newdiff', diff_limit=None,
         file_limit=None, show_full_diff=True)
 
     _parsed = diff_processor.prepare()
 
     all_files = []
     all_files_changes = []
     changed_lines = {}
     stats = [0, 0]
     for f in _parsed:
         all_files.append(f['filename'])
         all_files_changes.append({
             'filename': f['filename'],
             'stats': f['stats']
         })
         stats[0] += f['stats']['added']
         stats[1] += f['stats']['deleted']
 
         changed_lines[f['filename']] = []
         if len(f['chunks']) < 2:
             continue
         # first line is "context" information
         for chunks in f['chunks'][1:]:
             for chunk in chunks['lines']:
                 if chunk['action'] not in ('del', 'mod'):
                     continue
                 changed_lines[f['filename']].append(chunk['old_lineno'])
 
     commit_authors = []
     user_counts = {}
     email_counts = {}
     author_counts = {}
     _commit_cache = {}
 
     commits = []
     if get_commit_authors:
         log.debug('Obtaining commit authors from set of commits')
         _compare_data = target_scm.compare(
             target_ref, source_ref, source_scm, merge=True,
             pre_load=["author", "date", "message"]
         )
 
         for commit in _compare_data:
             # NOTE(marcink): we serialize here, so we don't produce more vcsserver calls on data returned
             # at this function which is later called via JSON serialization
             serialized_commit = dict(
                 author=commit.author,
                 date=commit.date,
                 message=commit.message,
                 commit_id=commit.raw_id,
                 raw_id=commit.raw_id
             )
             commits.append(serialized_commit)
             user = User.get_from_cs_author(serialized_commit['author'])
             if user and user not in commit_authors:
                 commit_authors.append(user)
 
     # lines
     if get_authors:
         log.debug('Calculating authors of changed files')
         target_commit = source_repo.get_commit(ancestor_id)
 
         for fname, lines in changed_lines.items():
 
             try:
                 node = target_commit.get_node(fname, pre_load=["is_binary"])
             except Exception:
                 log.exception("Failed to load node with path %s", fname)
                 continue
 
             if not isinstance(node, FileNode):
                 continue
 
             # NOTE(marcink): for binary node we don't do annotation, just use last author
             if node.is_binary:
                 author = node.last_commit.author
                 email = node.last_commit.author_email
 
                 user = User.get_from_cs_author(author)
                 if user:
                     user_counts[user.user_id] = user_counts.get(user.user_id, 0) + 1
                 author_counts[author] = author_counts.get(author, 0) + 1
                 email_counts[email] = email_counts.get(email, 0) + 1
 
                 continue
 
             for annotation in node.annotate:
                 line_no, commit_id, get_commit_func, line_text = annotation
                 if line_no in lines:
                     if commit_id not in _commit_cache:
                         _commit_cache[commit_id] = get_commit_func()
                     commit = _commit_cache[commit_id]
                     author = commit.author
                     email = commit.author_email
                     user = User.get_from_cs_author(author)
                     if user:
                         user_counts[user.user_id] = user_counts.get(user.user_id, 0) + 1
                     author_counts[author] = author_counts.get(author, 0) + 1
                     email_counts[email] = email_counts.get(email, 0) + 1
 
     log.debug('Default reviewers processing finished')
 
     return {
         'commits': commits,
         'files': all_files_changes,
         'stats': stats,
         'ancestor': ancestor_id,
         # original authors of modified files
         'original_authors': {
             'users': user_counts,
             'authors': author_counts,
             'emails': email_counts,
         },
         'commit_authors': commit_authors
     }
 
 
 class PullRequestModel(BaseModel):
 
     cls = PullRequest
 
     DIFF_CONTEXT = diffs.DEFAULT_CONTEXT
 
     UPDATE_STATUS_MESSAGES = {
         UpdateFailureReason.NONE: lazy_ugettext(
             'Pull request update successful.'),
         UpdateFailureReason.UNKNOWN: lazy_ugettext(
             'Pull request update failed because of an unknown error.'),
         UpdateFailureReason.NO_CHANGE: lazy_ugettext(
             'No update needed because the source and target have not changed.'),
         UpdateFailureReason.WRONG_REF_TYPE: lazy_ugettext(
             'Pull request cannot be updated because the reference type is '
             'not supported for an update. Only Branch, Tag or Bookmark is allowed.'),
         UpdateFailureReason.MISSING_TARGET_REF: lazy_ugettext(
             'This pull request cannot be updated because the target '
             'reference is missing.'),
         UpdateFailureReason.MISSING_SOURCE_REF: lazy_ugettext(
             'This pull request cannot be updated because the source '
             'reference is missing.'),
     }
     REF_TYPES = ['bookmark', 'book', 'tag', 'branch']
     UPDATABLE_REF_TYPES = ['bookmark', 'book', 'branch']
 
     def __get_pull_request(self, pull_request):
         return self._get_instance((
             PullRequest, PullRequestVersion), pull_request)
 
     def _check_perms(self, perms, pull_request, user, api=False):
         if not api:
             return h.HasRepoPermissionAny(*perms)(
                 user=user, repo_name=pull_request.target_repo.repo_name)
         else:
             return h.HasRepoPermissionAnyApi(*perms)(
                 user=user, repo_name=pull_request.target_repo.repo_name)
 
     def check_user_read(self, pull_request, user, api=False):
         _perms = ('repository.admin', 'repository.write', 'repository.read',)
         return self._check_perms(_perms, pull_request, user, api)
 
     def check_user_merge(self, pull_request, user, api=False):
         _perms = ('repository.admin', 'repository.write', 'hg.admin',)
         return self._check_perms(_perms, pull_request, user, api)
 
     def check_user_update(self, pull_request, user, api=False):
         owner = user.user_id == pull_request.user_id
         return self.check_user_merge(pull_request, user, api) or owner
 
     def check_user_delete(self, pull_request, user):
         owner = user.user_id == pull_request.user_id
         _perms = ('repository.admin',)
         return self._check_perms(_perms, pull_request, user) or owner
 
     def is_user_reviewer(self, pull_request, user):
         return user.user_id in [
             x.user_id for x in
             pull_request.get_pull_request_reviewers(PullRequestReviewers.ROLE_REVIEWER)
             if x.user
         ]
 
     def check_user_change_status(self, pull_request, user, api=False):
         return self.check_user_update(pull_request, user, api) \
                or self.is_user_reviewer(pull_request, user)
 
     def check_user_comment(self, pull_request, user):
         owner = user.user_id == pull_request.user_id
         return self.check_user_read(pull_request, user) or owner
 
     def get(self, pull_request):
         return self.__get_pull_request(pull_request)
 
     def _prepare_get_all_query(self, repo_name, search_q=None, source=False,
                                statuses=None, opened_by=None, order_by=None,
                                order_dir='desc', only_created=False):
         repo = None
         if repo_name:
             repo = self._get_repo(repo_name)
 
         q = PullRequest.query()
 
         if search_q:
             like_expression = u'%{}%'.format(safe_unicode(search_q))
             q = q.join(User, User.user_id == PullRequest.user_id)
             q = q.filter(or_(
                 cast(PullRequest.pull_request_id, String).ilike(like_expression),
                 User.username.ilike(like_expression),
                 PullRequest.title.ilike(like_expression),
                 PullRequest.description.ilike(like_expression),
             ))
 
         # source or target
         if repo and source:
             q = q.filter(PullRequest.source_repo == repo)
         elif repo:
             q = q.filter(PullRequest.target_repo == repo)
 
         # closed,opened
         if statuses:
             q = q.filter(PullRequest.status.in_(statuses))
 
         # opened by filter
         if opened_by:
             q = q.filter(PullRequest.user_id.in_(opened_by))
 
         # only get those that are in "created" state
         if only_created:
             q = q.filter(PullRequest.pull_request_state == PullRequest.STATE_CREATED)
 
         if order_by:
             order_map = {
                 'name_raw': PullRequest.pull_request_id,
                 'id': PullRequest.pull_request_id,
                 'title': PullRequest.title,
                 'updated_on_raw': PullRequest.updated_on,
                 'target_repo': PullRequest.target_repo_id
             }
             if order_dir == 'asc':
                 q = q.order_by(order_map[order_by].asc())
             else:
                 q = q.order_by(order_map[order_by].desc())
 
         return q
 
     def count_all(self, repo_name, search_q=None, source=False, statuses=None,
                   opened_by=None):
         """
         Count the number of pull requests for a specific repository.
 
         :param repo_name: target or source repo
         :param search_q: filter by text
         :param source: boolean flag to specify if repo_name refers to source
         :param statuses: list of pull request statuses
         :param opened_by: author user of the pull request
         :returns: int number of pull requests
         """
         q = self._prepare_get_all_query(
             repo_name, search_q=search_q, source=source, statuses=statuses,
             opened_by=opened_by)
 
         return q.count()
 
     def get_all(self, repo_name, search_q=None, source=False, statuses=None,
                 opened_by=None, offset=0, length=None, order_by=None, order_dir='desc'):
         """
         Get all pull requests for a specific repository.
 
         :param repo_name: target or source repo
         :param search_q: filter by text
         :param source: boolean flag to specify if repo_name refers to source
         :param statuses: list of pull request statuses
         :param opened_by: author user of the pull request
         :param offset: pagination offset
         :param length: length of returned list
         :param order_by: order of the returned list
         :param order_dir: 'asc' or 'desc' ordering direction
         :returns: list of pull requests
         """
         q = self._prepare_get_all_query(
             repo_name, search_q=search_q, source=source, statuses=statuses,
             opened_by=opened_by, order_by=order_by, order_dir=order_dir)
 
         if length:
             pull_requests = q.limit(length).offset(offset).all()
         else:
             pull_requests = q.all()
 
         return pull_requests
 
     def count_awaiting_review(self, repo_name, search_q=None, statuses=None):
         """
         Count the number of pull requests for a specific repository that are
         awaiting review.
 
         :param repo_name: target or source repo
         :param search_q: filter by text
         :param statuses: list of pull request statuses
         :returns: int number of pull requests
         """
         pull_requests = self.get_awaiting_review(
             repo_name, search_q=search_q, statuses=statuses)
 
         return len(pull_requests)
 
     def get_awaiting_review(self, repo_name, search_q=None, statuses=None,
                             offset=0, length=None, order_by=None, order_dir='desc'):
         """
         Get all pull requests for a specific repository that are awaiting
         review.
 
         :param repo_name: target or source repo
         :param search_q: filter by text
         :param statuses: list of pull request statuses
         :param offset: pagination offset
         :param length: length of returned list
         :param order_by: order of the returned list
         :param order_dir: 'asc' or 'desc' ordering direction
         :returns: list of pull requests
         """
         pull_requests = self.get_all(
             repo_name, search_q=search_q, statuses=statuses,
             order_by=order_by, order_dir=order_dir)
 
         _filtered_pull_requests = []
         for pr in pull_requests:
             status = pr.calculated_review_status()
             if status in [ChangesetStatus.STATUS_NOT_REVIEWED,
                           ChangesetStatus.STATUS_UNDER_REVIEW]:
                 _filtered_pull_requests.append(pr)
         if length:
             return _filtered_pull_requests[offset:offset+length]
         else:
             return _filtered_pull_requests
 
     def _prepare_awaiting_my_review_review_query(
             self, repo_name, user_id, search_q=None, statuses=None,
             order_by=None, order_dir='desc'):
 
         for_review_statuses = [
             ChangesetStatus.STATUS_UNDER_REVIEW, ChangesetStatus.STATUS_NOT_REVIEWED
         ]
 
         pull_request_alias = aliased(PullRequest)
         status_alias = aliased(ChangesetStatus)
         reviewers_alias = aliased(PullRequestReviewers)
         repo_alias = aliased(Repository)
 
         last_ver_subq = Session()\
             .query(func.min(ChangesetStatus.version)) \
             .filter(ChangesetStatus.pull_request_id == reviewers_alias.pull_request_id)\
             .filter(ChangesetStatus.user_id == reviewers_alias.user_id) \
             .subquery()
 
         q = Session().query(pull_request_alias) \
             .options(lazyload(pull_request_alias.author)) \
             .join(reviewers_alias,
                   reviewers_alias.pull_request_id == pull_request_alias.pull_request_id) \
             .join(repo_alias,
                   repo_alias.repo_id == pull_request_alias.target_repo_id) \
             .outerjoin(status_alias,
                        and_(status_alias.user_id == reviewers_alias.user_id,
                             status_alias.pull_request_id == reviewers_alias.pull_request_id)) \
             .filter(or_(status_alias.version == null(),
                         status_alias.version == last_ver_subq)) \
             .filter(reviewers_alias.user_id == user_id) \
             .filter(repo_alias.repo_name == repo_name) \
             .filter(or_(status_alias.status == null(), status_alias.status.in_(for_review_statuses))) \
             .group_by(pull_request_alias)
 
         # closed,opened
         if statuses:
             q = q.filter(pull_request_alias.status.in_(statuses))
 
         if search_q:
             like_expression = u'%{}%'.format(safe_unicode(search_q))
             q = q.join(User, User.user_id == pull_request_alias.user_id)
             q = q.filter(or_(
                 cast(pull_request_alias.pull_request_id, String).ilike(like_expression),
                 User.username.ilike(like_expression),
                 pull_request_alias.title.ilike(like_expression),
                 pull_request_alias.description.ilike(like_expression),
             ))
 
         if order_by:
             order_map = {
                 'name_raw': pull_request_alias.pull_request_id,
                 'title': pull_request_alias.title,
                 'updated_on_raw': pull_request_alias.updated_on,
                 'target_repo': pull_request_alias.target_repo_id
             }
             if order_dir == 'asc':
                 q = q.order_by(order_map[order_by].asc())
             else:
                 q = q.order_by(order_map[order_by].desc())
 
         return q
 
     def count_awaiting_my_review(self, repo_name, user_id, search_q=None, statuses=None):
         """
         Count the number of pull requests for a specific repository that are
         awaiting review from a specific user.
 
         :param repo_name: target or source repo
         :param user_id: reviewer user of the pull request
         :param search_q: filter by text
         :param statuses: list of pull request statuses
         :returns: int number of pull requests
         """
         q = self._prepare_awaiting_my_review_review_query(
             repo_name, user_id, search_q=search_q, statuses=statuses)
         return q.count()
 
     def get_awaiting_my_review(self, repo_name, user_id, search_q=None, statuses=None,
                                offset=0, length=None, order_by=None, order_dir='desc'):
         """
         Get all pull requests for a specific repository that are awaiting
         review from a specific user.
 
         :param repo_name: target or source repo
         :param user_id: reviewer user of the pull request
         :param search_q: filter by text
         :param statuses: list of pull request statuses
         :param offset: pagination offset
         :param length: length of returned list
         :param order_by: order of the returned list
         :param order_dir: 'asc' or 'desc' ordering direction
         :returns: list of pull requests
         """
 
         q = self._prepare_awaiting_my_review_review_query(
             repo_name, user_id, search_q=search_q, statuses=statuses,
             order_by=order_by, order_dir=order_dir)
 
         if length:
             pull_requests = q.limit(length).offset(offset).all()
         else:
             pull_requests = q.all()
 
         return pull_requests
 
     def _prepare_im_participating_query(self, user_id=None, statuses=None, query='',
                                         order_by=None, order_dir='desc'):
         """
         return a query of pull-requests user is an creator, or he's added as a reviewer
         """
         q = PullRequest.query()
         if user_id:
             reviewers_subquery = Session().query(
                 PullRequestReviewers.pull_request_id).filter(
                 PullRequestReviewers.user_id == user_id).subquery()
             user_filter = or_(
                 PullRequest.user_id == user_id,
                 PullRequest.pull_request_id.in_(reviewers_subquery)
             )
             q = PullRequest.query().filter(user_filter)
 
         # closed,opened
         if statuses:
             q = q.filter(PullRequest.status.in_(statuses))
 
         if query:
             like_expression = u'%{}%'.format(safe_unicode(query))
             q = q.join(User, User.user_id == PullRequest.user_id)
             q = q.filter(or_(
                 cast(PullRequest.pull_request_id, String).ilike(like_expression),
                 User.username.ilike(like_expression),
                 PullRequest.title.ilike(like_expression),
                 PullRequest.description.ilike(like_expression),
             ))
         if order_by:
             order_map = {
                 'name_raw': PullRequest.pull_request_id,
                 'title': PullRequest.title,
                 'updated_on_raw': PullRequest.updated_on,
                 'target_repo': PullRequest.target_repo_id
             }
             if order_dir == 'asc':
                 q = q.order_by(order_map[order_by].asc())
             else:
                 q = q.order_by(order_map[order_by].desc())
 
         return q
 
     def count_im_participating_in(self, user_id=None, statuses=None, query=''):
         q = self._prepare_im_participating_query(user_id, statuses=statuses, query=query)
         return q.count()
 
     def get_im_participating_in(
             self, user_id=None, statuses=None, query='', offset=0,
             length=None, order_by=None, order_dir='desc'):
         """
         Get all Pull requests that i'm participating in as a reviewer, or i have opened
         """
 
         q = self._prepare_im_participating_query(
             user_id, statuses=statuses, query=query, order_by=order_by,
             order_dir=order_dir)
 
         if length:
             pull_requests = q.limit(length).offset(offset).all()
         else:
             pull_requests = q.all()
 
         return pull_requests
 
     def _prepare_participating_in_for_review_query(
             self, user_id, statuses=None, query='', order_by=None, order_dir='desc'):
 
         for_review_statuses = [
             ChangesetStatus.STATUS_UNDER_REVIEW, ChangesetStatus.STATUS_NOT_REVIEWED
         ]
 
         pull_request_alias = aliased(PullRequest)
         status_alias = aliased(ChangesetStatus)
         reviewers_alias = aliased(PullRequestReviewers)
 
         last_ver_subq = Session()\
             .query(func.min(ChangesetStatus.version)) \
             .filter(ChangesetStatus.pull_request_id == reviewers_alias.pull_request_id)\
             .filter(ChangesetStatus.user_id == reviewers_alias.user_id) \
             .subquery()
 
         q = Session().query(pull_request_alias) \
             .options(lazyload(pull_request_alias.author)) \
             .join(reviewers_alias,
                   reviewers_alias.pull_request_id == pull_request_alias.pull_request_id) \
             .outerjoin(status_alias,
                        and_(status_alias.user_id == reviewers_alias.user_id,
                             status_alias.pull_request_id == reviewers_alias.pull_request_id)) \
             .filter(or_(status_alias.version == null(),
                         status_alias.version == last_ver_subq)) \
             .filter(reviewers_alias.user_id == user_id) \
             .filter(or_(status_alias.status == null(), status_alias.status.in_(for_review_statuses))) \
             .group_by(pull_request_alias)
 
         # closed,opened
         if statuses:
             q = q.filter(pull_request_alias.status.in_(statuses))
 
         if query:
             like_expression = u'%{}%'.format(safe_unicode(query))
             q = q.join(User, User.user_id == pull_request_alias.user_id)
             q = q.filter(or_(
                 cast(pull_request_alias.pull_request_id, String).ilike(like_expression),
                 User.username.ilike(like_expression),
                 pull_request_alias.title.ilike(like_expression),
                 pull_request_alias.description.ilike(like_expression),
             ))
 
         if order_by:
             order_map = {
                 'name_raw': pull_request_alias.pull_request_id,
                 'title': pull_request_alias.title,
                 'updated_on_raw': pull_request_alias.updated_on,
                 'target_repo': pull_request_alias.target_repo_id
             }
             if order_dir == 'asc':
                 q = q.order_by(order_map[order_by].asc())
             else:
                 q = q.order_by(order_map[order_by].desc())
 
         return q
 
     def count_im_participating_in_for_review(self, user_id, statuses=None, query=''):
         q = self._prepare_participating_in_for_review_query(user_id, statuses=statuses, query=query)
         return q.count()
 
     def get_im_participating_in_for_review(
             self, user_id, statuses=None, query='', offset=0,
             length=None, order_by=None, order_dir='desc'):
         """
         Get all Pull requests that needs user approval or rejection
         """
 
         q = self._prepare_participating_in_for_review_query(
             user_id, statuses=statuses, query=query, order_by=order_by,
             order_dir=order_dir)
 
         if length:
             pull_requests = q.limit(length).offset(offset).all()
         else:
             pull_requests = q.all()
 
         return pull_requests
 
     def get_versions(self, pull_request):
         """
         returns version of pull request sorted by ID descending
         """
         return PullRequestVersion.query()\
             .filter(PullRequestVersion.pull_request == pull_request)\
             .order_by(PullRequestVersion.pull_request_version_id.asc())\
             .all()
 
     def get_pr_version(self, pull_request_id, version=None):
         at_version = None
 
         if version and version == 'latest':
             pull_request_ver = PullRequest.get(pull_request_id)
             pull_request_obj = pull_request_ver
             _org_pull_request_obj = pull_request_obj
             at_version = 'latest'
         elif version:
             pull_request_ver = PullRequestVersion.get_or_404(version)
             pull_request_obj = pull_request_ver
             _org_pull_request_obj = pull_request_ver.pull_request
             at_version = pull_request_ver.pull_request_version_id
         else:
             _org_pull_request_obj = pull_request_obj = PullRequest.get_or_404(
                 pull_request_id)
 
         pull_request_display_obj = PullRequest.get_pr_display_object(
             pull_request_obj, _org_pull_request_obj)
 
         return _org_pull_request_obj, pull_request_obj, \
                pull_request_display_obj, at_version
 
     def pr_commits_versions(self, versions):
         """
         Maps the pull-request commits into all known PR versions. This way we can obtain
         each pr version the commit was introduced in.
         """
         commit_versions = collections.defaultdict(list)
         num_versions = [x.pull_request_version_id for x in versions]
         for ver in versions:
             for commit_id in ver.revisions:
                 ver_idx = ChangesetComment.get_index_from_version(
                     ver.pull_request_version_id, num_versions=num_versions)
                 commit_versions[commit_id].append(ver_idx)
         return commit_versions
 
     def create(self, created_by, source_repo, source_ref, target_repo,
                target_ref, revisions, reviewers, observers, title, description=None,
                common_ancestor_id=None,
                description_renderer=None,
                reviewer_data=None, translator=None, auth_user=None):
         translator = translator or get_current_request().translate
 
         created_by_user = self._get_user(created_by)
         auth_user = auth_user or created_by_user.AuthUser()
         source_repo = self._get_repo(source_repo)
         target_repo = self._get_repo(target_repo)
 
         pull_request = PullRequest()
         pull_request.source_repo = source_repo
         pull_request.source_ref = source_ref
         pull_request.target_repo = target_repo
         pull_request.target_ref = target_ref
         pull_request.revisions = revisions
         pull_request.title = title
         pull_request.description = description
         pull_request.description_renderer = description_renderer
         pull_request.author = created_by_user
         pull_request.reviewer_data = reviewer_data
         pull_request.pull_request_state = pull_request.STATE_CREATING
         pull_request.common_ancestor_id = common_ancestor_id
 
         Session().add(pull_request)
         Session().flush()
 
         reviewer_ids = set()
         # members / reviewers
         for reviewer_object in reviewers:
             user_id, reasons, mandatory, role, rules = reviewer_object
             user = self._get_user(user_id)
 
             # skip duplicates
             if user.user_id in reviewer_ids:
                 continue
 
             reviewer_ids.add(user.user_id)
 
             reviewer = PullRequestReviewers()
             reviewer.user = user
             reviewer.pull_request = pull_request
             reviewer.reasons = reasons
             reviewer.mandatory = mandatory
             reviewer.role = role
 
             # NOTE(marcink): pick only first rule for now
             rule_id = list(rules)[0] if rules else None
             rule = RepoReviewRule.get(rule_id) if rule_id else None
             if rule:
                 review_group = rule.user_group_vote_rule(user_id)
                 # we check if this particular reviewer is member of a voting group
                 if review_group:
                     # NOTE(marcink):
                     # can be that user is member of more but we pick the first same,
                     # same as default reviewers algo
                     review_group = review_group[0]
 
                     rule_data = {
                         'rule_name':
                             rule.review_rule_name,
                         'rule_user_group_entry_id':
                             review_group.repo_review_rule_users_group_id,
                         'rule_user_group_name':
                             review_group.users_group.users_group_name,
                         'rule_user_group_members':
                             [x.user.username for x in review_group.users_group.members],
                         'rule_user_group_members_id':
                             [x.user.user_id for x in review_group.users_group.members],
                     }
                     # e.g {'vote_rule': -1, 'mandatory': True}
                     rule_data.update(review_group.rule_data())
 
                     reviewer.rule_data = rule_data
 
             Session().add(reviewer)
             Session().flush()
 
         for observer_object in observers:
             user_id, reasons, mandatory, role, rules = observer_object
             user = self._get_user(user_id)
 
             # skip duplicates from reviewers
             if user.user_id in reviewer_ids:
                 continue
 
             #reviewer_ids.add(user.user_id)
 
             observer = PullRequestReviewers()
             observer.user = user
             observer.pull_request = pull_request
             observer.reasons = reasons
             observer.mandatory = mandatory
             observer.role = role
 
             # NOTE(marcink): pick only first rule for now
             rule_id = list(rules)[0] if rules else None
             rule = RepoReviewRule.get(rule_id) if rule_id else None
             if rule:
                 # TODO(marcink): do we need this for observers ??
                 pass
 
             Session().add(observer)
             Session().flush()
 
         # Set approval status to "Under Review" for all commits which are
         # part of this pull request.
         ChangesetStatusModel().set_status(
             repo=target_repo,
             status=ChangesetStatus.STATUS_UNDER_REVIEW,
             user=created_by_user,
             pull_request=pull_request
         )
         # we commit early at this point. This has to do with a fact
         # that before queries do some row-locking. And because of that
         # we need to commit and finish transaction before below validate call
         # that for large repos could be long resulting in long row locks
         Session().commit()
 
         # prepare workspace, and run initial merge simulation. Set state during that
         # operation
         pull_request = PullRequest.get(pull_request.pull_request_id)
 
         # set as merging, for merge simulation, and if finished to created so we mark
         # simulation is working fine
         with pull_request.set_state(PullRequest.STATE_MERGING,
                                     final_state=PullRequest.STATE_CREATED) as state_obj:
             MergeCheck.validate(
                 pull_request, auth_user=auth_user, translator=translator)
 
         self.notify_reviewers(pull_request, reviewer_ids, created_by_user)
         self.trigger_pull_request_hook(pull_request, created_by_user, 'create')
 
         creation_data = pull_request.get_api_data(with_merge_state=False)
         self._log_audit_action(
             'repo.pull_request.create', {'data': creation_data},
             auth_user, pull_request)
 
         return pull_request
 
     def trigger_pull_request_hook(self, pull_request, user, action, data=None):
         pull_request = self.__get_pull_request(pull_request)
         target_scm = pull_request.target_repo.scm_instance()
         if action == 'create':
             trigger_hook = hooks_utils.trigger_create_pull_request_hook
         elif action == 'merge':
             trigger_hook = hooks_utils.trigger_merge_pull_request_hook
         elif action == 'close':
             trigger_hook = hooks_utils.trigger_close_pull_request_hook
         elif action == 'review_status_change':
             trigger_hook = hooks_utils.trigger_review_pull_request_hook
         elif action == 'update':
             trigger_hook = hooks_utils.trigger_update_pull_request_hook
         elif action == 'comment':
             trigger_hook = hooks_utils.trigger_comment_pull_request_hook
         elif action == 'comment_edit':
             trigger_hook = hooks_utils.trigger_comment_pull_request_edit_hook
         else:
             return
 
         log.debug('Handling pull_request %s trigger_pull_request_hook with action %s and hook: %s',
                   pull_request, action, trigger_hook)
         trigger_hook(
             username=user.username,
             repo_name=pull_request.target_repo.repo_name,
             repo_type=target_scm.alias,
             pull_request=pull_request,
             data=data)
 
     def _get_commit_ids(self, pull_request):
         """
         Return the commit ids of the merged pull request.
 
         This method is not dealing correctly yet with the lack of autoupdates
         nor with the implicit target updates.
         For example: if a commit in the source repo is already in the target it
         will be reported anyways.
         """
         merge_rev = pull_request.merge_rev
         if merge_rev is None:
             raise ValueError('This pull request was not merged yet')
 
         commit_ids = list(pull_request.revisions)
         if merge_rev not in commit_ids:
             commit_ids.append(merge_rev)
 
         return commit_ids
 
     def merge_repo(self, pull_request, user, extras):
         log.debug("Merging pull request %s", pull_request.pull_request_id)
         extras['user_agent'] = 'internal-merge'
         merge_state = self._merge_pull_request(pull_request, user, extras)
         if merge_state.executed:
             log.debug("Merge was successful, updating the pull request comments.")
             self._comment_and_close_pr(pull_request, user, merge_state)
 
             self._log_audit_action(
                 'repo.pull_request.merge',
                 {'merge_state': merge_state.__dict__},
                 user, pull_request)
 
         else:
             log.warn("Merge failed, not updating the pull request.")
         return merge_state
 
     def _merge_pull_request(self, pull_request, user, extras, merge_msg=None):
         target_vcs = pull_request.target_repo.scm_instance()
         source_vcs = pull_request.source_repo.scm_instance()
 
         message = safe_unicode(merge_msg or vcs_settings.MERGE_MESSAGE_TMPL).format(
             pr_id=pull_request.pull_request_id,
             pr_title=pull_request.title,
             source_repo=source_vcs.name,
             source_ref_name=pull_request.source_ref_parts.name,
             target_repo=target_vcs.name,
             target_ref_name=pull_request.target_ref_parts.name,
         )
 
         workspace_id = self._workspace_id(pull_request)
         repo_id = pull_request.target_repo.repo_id
         use_rebase = self._use_rebase_for_merging(pull_request)
         close_branch = self._close_branch_before_merging(pull_request)
         user_name = self._user_name_for_merging(pull_request, user)
 
         target_ref = self._refresh_reference(
             pull_request.target_ref_parts, target_vcs)
 
         callback_daemon, extras = prepare_callback_daemon(
             extras, protocol=vcs_settings.HOOKS_PROTOCOL,
             host=vcs_settings.HOOKS_HOST,
             use_direct_calls=vcs_settings.HOOKS_DIRECT_CALLS)
 
         with callback_daemon:
             # TODO: johbo: Implement a clean way to run a config_override
             # for a single call.
             target_vcs.config.set(
                 'rhodecode', 'RC_SCM_DATA', json.dumps(extras))
 
             merge_state = target_vcs.merge(
                 repo_id, workspace_id, target_ref, source_vcs,
                 pull_request.source_ref_parts,
                 user_name=user_name, user_email=user.email,
                 message=message, use_rebase=use_rebase,
                 close_branch=close_branch)
         return merge_state
 
     def _comment_and_close_pr(self, pull_request, user, merge_state, close_msg=None):
         pull_request.merge_rev = merge_state.merge_ref.commit_id
         pull_request.updated_on = datetime.datetime.now()
         close_msg = close_msg or 'Pull request merged and closed'
 
         CommentsModel().create(
             text=safe_unicode(close_msg),
             repo=pull_request.target_repo.repo_id,
             user=user.user_id,
             pull_request=pull_request.pull_request_id,
             f_path=None,
             line_no=None,
             closing_pr=True
         )
 
         Session().add(pull_request)
         Session().flush()
         # TODO: paris: replace invalidation with less radical solution
         ScmModel().mark_for_invalidation(
             pull_request.target_repo.repo_name)
         self.trigger_pull_request_hook(pull_request, user, 'merge')
 
     def has_valid_update_type(self, pull_request):
         source_ref_type = pull_request.source_ref_parts.type
         return source_ref_type in self.REF_TYPES
 
     def get_flow_commits(self, pull_request):
 
         # source repo
         source_ref_name = pull_request.source_ref_parts.name
         source_ref_type = pull_request.source_ref_parts.type
         source_ref_id = pull_request.source_ref_parts.commit_id
         source_repo = pull_request.source_repo.scm_instance()
 
         try:
             if source_ref_type in self.REF_TYPES:
                 source_commit = source_repo.get_commit(
                     source_ref_name, reference_obj=pull_request.source_ref_parts)
             else:
                 source_commit = source_repo.get_commit(source_ref_id)
         except CommitDoesNotExistError:
             raise SourceRefMissing()
 
         # target repo
         target_ref_name = pull_request.target_ref_parts.name
         target_ref_type = pull_request.target_ref_parts.type
         target_ref_id = pull_request.target_ref_parts.commit_id
         target_repo = pull_request.target_repo.scm_instance()
 
         try:
             if target_ref_type in self.REF_TYPES:
                 target_commit = target_repo.get_commit(
                     target_ref_name, reference_obj=pull_request.target_ref_parts)
             else:
                 target_commit = target_repo.get_commit(target_ref_id)
         except CommitDoesNotExistError:
             raise TargetRefMissing()
 
         return source_commit, target_commit
 
     def update_commits(self, pull_request, updating_user):
         """
         Get the updated list of commits for the pull request
         and return the new pull request version and the list
         of commits processed by this update action
 
         updating_user is the user_object who triggered the update
         """
         pull_request = self.__get_pull_request(pull_request)
         source_ref_type = pull_request.source_ref_parts.type
         source_ref_name = pull_request.source_ref_parts.name
         source_ref_id = pull_request.source_ref_parts.commit_id
 
         target_ref_type = pull_request.target_ref_parts.type
         target_ref_name = pull_request.target_ref_parts.name
         target_ref_id = pull_request.target_ref_parts.commit_id
 
         if not self.has_valid_update_type(pull_request):
             log.debug("Skipping update of pull request %s due to ref type: %s",
                       pull_request, source_ref_type)
             return UpdateResponse(
                 executed=False,
                 reason=UpdateFailureReason.WRONG_REF_TYPE,
                 old=pull_request, new=None, common_ancestor_id=None, commit_changes=None,
                 source_changed=False, target_changed=False)
 
         try:
             source_commit, target_commit = self.get_flow_commits(pull_request)
         except SourceRefMissing:
             return UpdateResponse(
                 executed=False,
                 reason=UpdateFailureReason.MISSING_SOURCE_REF,
                 old=pull_request, new=None, common_ancestor_id=None, commit_changes=None,
                 source_changed=False, target_changed=False)
         except TargetRefMissing:
             return UpdateResponse(
                 executed=False,
                 reason=UpdateFailureReason.MISSING_TARGET_REF,
                 old=pull_request, new=None, common_ancestor_id=None, commit_changes=None,
                 source_changed=False, target_changed=False)
 
         source_changed = source_ref_id != source_commit.raw_id
         target_changed = target_ref_id != target_commit.raw_id
 
         if not (source_changed or target_changed):
             log.debug("Nothing changed in pull request %s", pull_request)
             return UpdateResponse(
                 executed=False,
                 reason=UpdateFailureReason.NO_CHANGE,
                 old=pull_request, new=None, common_ancestor_id=None, commit_changes=None,
                 source_changed=target_changed, target_changed=source_changed)
 
         change_in_found = 'target repo' if target_changed else 'source repo'
         log.debug('Updating pull request because of change in %s detected',
                   change_in_found)
 
         # Finally there is a need for an update, in case of source change
         # we create a new version, else just an update
         if source_changed:
             pull_request_version = self._create_version_from_snapshot(pull_request)
             self._link_comments_to_version(pull_request_version)
         else:
             try:
                 ver = pull_request.versions[-1]
             except IndexError:
                 ver = None
 
             pull_request.pull_request_version_id = \
                 ver.pull_request_version_id if ver else None
             pull_request_version = pull_request
 
         source_repo = pull_request.source_repo.scm_instance()
         target_repo = pull_request.target_repo.scm_instance()
 
         # re-compute commit ids
         old_commit_ids = pull_request.revisions
         pre_load = ["author", "date", "message", "branch"]
         commit_ranges = target_repo.compare(
             target_commit.raw_id, source_commit.raw_id, source_repo, merge=True,
             pre_load=pre_load)
 
         target_ref = target_commit.raw_id
         source_ref = source_commit.raw_id
         ancestor_commit_id = target_repo.get_common_ancestor(
             target_ref, source_ref, source_repo)
 
         if not ancestor_commit_id:
             raise ValueError(
                 'cannot calculate diff info without a common ancestor. '
                 'Make sure both repositories are related, and have a common forking commit.')
 
         pull_request.common_ancestor_id = ancestor_commit_id
 
         pull_request.source_ref = '%s:%s:%s' % (
             source_ref_type, source_ref_name, source_commit.raw_id)
         pull_request.target_ref = '%s:%s:%s' % (
             target_ref_type, target_ref_name, ancestor_commit_id)
 
         pull_request.revisions = [
             commit.raw_id for commit in reversed(commit_ranges)]
         pull_request.updated_on = datetime.datetime.now()
         Session().add(pull_request)
         new_commit_ids = pull_request.revisions
 
         old_diff_data, new_diff_data = self._generate_update_diffs(
             pull_request, pull_request_version)
 
         # calculate commit and file changes
         commit_changes = self._calculate_commit_id_changes(
             old_commit_ids, new_commit_ids)
         file_changes = self._calculate_file_changes(
             old_diff_data, new_diff_data)
 
         # set comments as outdated if DIFFS changed
         CommentsModel().outdate_comments(
             pull_request, old_diff_data=old_diff_data,
             new_diff_data=new_diff_data)
 
         valid_commit_changes = (commit_changes.added or commit_changes.removed)
         file_node_changes = (
             file_changes.added or file_changes.modified or file_changes.removed)
         pr_has_changes = valid_commit_changes or file_node_changes
 
         # Add an automatic comment to the pull request, in case
         # anything has changed
         if pr_has_changes:
             update_comment = CommentsModel().create(
                 text=self._render_update_message(ancestor_commit_id, commit_changes, file_changes),
                 repo=pull_request.target_repo,
                 user=pull_request.author,
                 pull_request=pull_request,
                 send_email=False, renderer=DEFAULT_COMMENTS_RENDERER)
 
             # Update status to "Under Review" for added commits
             for commit_id in commit_changes.added:
                 ChangesetStatusModel().set_status(
                     repo=pull_request.source_repo,
                     status=ChangesetStatus.STATUS_UNDER_REVIEW,
                     comment=update_comment,
                     user=pull_request.author,
                     pull_request=pull_request,
                     revision=commit_id)
 
+        # initial commit
+        Session().commit()
+
+        if pr_has_changes:
             # send update email to users
             try:
                 self.notify_users(pull_request=pull_request, updating_user=updating_user,
                                   ancestor_commit_id=ancestor_commit_id,
                                   commit_changes=commit_changes,
                                   file_changes=file_changes)
+                Session().commit()
             except Exception:
                 log.exception('Failed to send email notification to users')
+                Session().rollback()
 
         log.debug(
             'Updated pull request %s, added_ids: %s, common_ids: %s, '
             'removed_ids: %s', pull_request.pull_request_id,
             commit_changes.added, commit_changes.common, commit_changes.removed)
         log.debug(
             'Updated pull request with the following file changes: %s',
             file_changes)
 
         log.info(
             "Updated pull request %s from commit %s to commit %s, "
             "stored new version %s of this pull request.",
             pull_request.pull_request_id, source_ref_id,
             pull_request.source_ref_parts.commit_id,
             pull_request_version.pull_request_version_id)
-        Session().commit()
+
         self.trigger_pull_request_hook(pull_request, pull_request.author, 'update')
 
         return UpdateResponse(
             executed=True, reason=UpdateFailureReason.NONE,
             old=pull_request, new=pull_request_version,
             common_ancestor_id=ancestor_commit_id, commit_changes=commit_changes,
             source_changed=source_changed, target_changed=target_changed)
 
     def _create_version_from_snapshot(self, pull_request):
         version = PullRequestVersion()
         version.title = pull_request.title
         version.description = pull_request.description
         version.status = pull_request.status
         version.pull_request_state = pull_request.pull_request_state
         version.created_on = datetime.datetime.now()
         version.updated_on = pull_request.updated_on
         version.user_id = pull_request.user_id
         version.source_repo = pull_request.source_repo
         version.source_ref = pull_request.source_ref
         version.target_repo = pull_request.target_repo
         version.target_ref = pull_request.target_ref
 
         version._last_merge_source_rev = pull_request._last_merge_source_rev
         version._last_merge_target_rev = pull_request._last_merge_target_rev
         version.last_merge_status = pull_request.last_merge_status
         version.last_merge_metadata = pull_request.last_merge_metadata
         version.shadow_merge_ref = pull_request.shadow_merge_ref
         version.merge_rev = pull_request.merge_rev
         version.reviewer_data = pull_request.reviewer_data
 
         version.revisions = pull_request.revisions
         version.common_ancestor_id = pull_request.common_ancestor_id
         version.pull_request = pull_request
         Session().add(version)
         Session().flush()
 
         return version
 
     def _generate_update_diffs(self, pull_request, pull_request_version):
 
         diff_context = (
             self.DIFF_CONTEXT +
             CommentsModel.needed_extra_diff_context())
         hide_whitespace_changes = False
         source_repo = pull_request_version.source_repo
         source_ref_id = pull_request_version.source_ref_parts.commit_id
         target_ref_id = pull_request_version.target_ref_parts.commit_id
         old_diff = self._get_diff_from_pr_or_version(
             source_repo, source_ref_id, target_ref_id,
             hide_whitespace_changes=hide_whitespace_changes, diff_context=diff_context)
 
         source_repo = pull_request.source_repo
         source_ref_id = pull_request.source_ref_parts.commit_id
         target_ref_id = pull_request.target_ref_parts.commit_id
 
         new_diff = self._get_diff_from_pr_or_version(
             source_repo, source_ref_id, target_ref_id,
             hide_whitespace_changes=hide_whitespace_changes, diff_context=diff_context)
 
         old_diff_data = diffs.DiffProcessor(old_diff)
         old_diff_data.prepare()
         new_diff_data = diffs.DiffProcessor(new_diff)
         new_diff_data.prepare()
 
         return old_diff_data, new_diff_data
 
     def _link_comments_to_version(self, pull_request_version):
         """
         Link all unlinked comments of this pull request to the given version.
 
         :param pull_request_version: The `PullRequestVersion` to which
             the comments shall be linked.
 
         """
         pull_request = pull_request_version.pull_request
         comments = ChangesetComment.query()\
             .filter(
                 # TODO: johbo: Should we query for the repo at all here?
                 # Pending decision on how comments of PRs are to be related
                 # to either the source repo, the target repo or no repo at all.
                 ChangesetComment.repo_id == pull_request.target_repo.repo_id,
                 ChangesetComment.pull_request == pull_request,
                 ChangesetComment.pull_request_version == None)\
             .order_by(ChangesetComment.comment_id.asc())
 
         # TODO: johbo: Find out why this breaks if it is done in a bulk
         # operation.
         for comment in comments:
             comment.pull_request_version_id = (
                 pull_request_version.pull_request_version_id)
             Session().add(comment)
 
     def _calculate_commit_id_changes(self, old_ids, new_ids):
         added = [x for x in new_ids if x not in old_ids]
         common = [x for x in new_ids if x in old_ids]
         removed = [x for x in old_ids if x not in new_ids]
         total = new_ids
         return ChangeTuple(added, common, removed, total)
 
     def _calculate_file_changes(self, old_diff_data, new_diff_data):
 
         old_files = OrderedDict()
         for diff_data in old_diff_data.parsed_diff:
             old_files[diff_data['filename']] = md5_safe(diff_data['raw_diff'])
 
         added_files = []
         modified_files = []
         removed_files = []
         for diff_data in new_diff_data.parsed_diff:
             new_filename = diff_data['filename']
             new_hash = md5_safe(diff_data['raw_diff'])
 
             old_hash = old_files.get(new_filename)
             if not old_hash:
                 # file is not present in old diff, we have to figure out from parsed diff
                 # operation ADD/REMOVE
                 operations_dict = diff_data['stats']['ops']
                 if diffs.DEL_FILENODE in operations_dict:
                     removed_files.append(new_filename)
                 else:
                     added_files.append(new_filename)
             else:
                 if new_hash != old_hash:
                     modified_files.append(new_filename)
                 # now remove a file from old, since we have seen it already
                 del old_files[new_filename]
 
         # removed files is when there are present in old, but not in NEW,
         # since we remove old files that are present in new diff, left-overs
         # if any should be the removed files
         removed_files.extend(old_files.keys())
 
         return FileChangeTuple(added_files, modified_files, removed_files)
 
     def _render_update_message(self, ancestor_commit_id, changes, file_changes):
         """
         render the message using DEFAULT_COMMENTS_RENDERER (RST renderer),
         so it's always looking the same disregarding on which default
         renderer system is using.
 
         :param ancestor_commit_id: ancestor raw_id
         :param changes: changes named tuple
         :param file_changes: file changes named tuple
 
         """
         new_status = ChangesetStatus.get_status_lbl(
             ChangesetStatus.STATUS_UNDER_REVIEW)
 
         changed_files = (
             file_changes.added + file_changes.modified + file_changes.removed)
 
         params = {
             'under_review_label': new_status,
             'added_commits': changes.added,
             'removed_commits': changes.removed,
             'changed_files': changed_files,
             'added_files': file_changes.added,
             'modified_files': file_changes.modified,
             'removed_files': file_changes.removed,
             'ancestor_commit_id': ancestor_commit_id
         }
         renderer = RstTemplateRenderer()
         return renderer.render('pull_request_update.mako', **params)
 
     def edit(self, pull_request, title, description, description_renderer, user):
         pull_request = self.__get_pull_request(pull_request)
         old_data = pull_request.get_api_data(with_merge_state=False)
         if pull_request.is_closed():
             raise ValueError('This pull request is closed')
         if title:
             pull_request.title = title
         pull_request.description = description
         pull_request.updated_on = datetime.datetime.now()
         pull_request.description_renderer = description_renderer
         Session().add(pull_request)
         self._log_audit_action(
             'repo.pull_request.edit', {'old_data': old_data},
             user, pull_request)
 
     def update_reviewers(self, pull_request, reviewer_data, user):
         """
         Update the reviewers in the pull request
 
         :param pull_request: the pr to update
         :param reviewer_data: list of tuples
             [(user, ['reason1', 'reason2'], mandatory_flag, role, [rules])]
         :param user: current use who triggers this action
         """
 
         pull_request = self.__get_pull_request(pull_request)
         if pull_request.is_closed():
             raise ValueError('This pull request is closed')
 
         reviewers = {}
         for user_id, reasons, mandatory, role, rules in reviewer_data:
             if isinstance(user_id, (int, compat.string_types)):
                 user_id = self._get_user(user_id).user_id
             reviewers[user_id] = {
                 'reasons': reasons, 'mandatory': mandatory, 'role': role}
 
         reviewers_ids = set(reviewers.keys())
         current_reviewers = PullRequestReviewers.get_pull_request_reviewers(
             pull_request.pull_request_id, role=PullRequestReviewers.ROLE_REVIEWER)
 
         current_reviewers_ids = set([x.user.user_id for x in current_reviewers])
 
         ids_to_add = reviewers_ids.difference(current_reviewers_ids)
         ids_to_remove = current_reviewers_ids.difference(reviewers_ids)
 
         log.debug("Adding %s reviewers", ids_to_add)
         log.debug("Removing %s reviewers", ids_to_remove)
         changed = False
         added_audit_reviewers = []
         removed_audit_reviewers = []
 
         for uid in ids_to_add:
             changed = True
             _usr = self._get_user(uid)
             reviewer = PullRequestReviewers()
             reviewer.user = _usr
             reviewer.pull_request = pull_request
             reviewer.reasons = reviewers[uid]['reasons']
             # NOTE(marcink): mandatory shouldn't be changed now
             # reviewer.mandatory = reviewers[uid]['reasons']
             # NOTE(marcink): role should be hardcoded, so we won't edit it.
             reviewer.role = PullRequestReviewers.ROLE_REVIEWER
             Session().add(reviewer)
             added_audit_reviewers.append(reviewer.get_dict())
 
         for uid in ids_to_remove:
             changed = True
             # NOTE(marcink): we fetch "ALL" reviewers objects using .all().
             # This is an edge case that handles previous state of having the same reviewer twice.
             # this CAN happen due to the lack of DB checks
             reviewers = PullRequestReviewers.query()\
                 .filter(PullRequestReviewers.user_id == uid,
                         PullRequestReviewers.role == PullRequestReviewers.ROLE_REVIEWER,
                         PullRequestReviewers.pull_request == pull_request)\
                 .all()
 
             for obj in reviewers:
                 added_audit_reviewers.append(obj.get_dict())
                 Session().delete(obj)
 
         if changed:
             Session().expire_all()
             pull_request.updated_on = datetime.datetime.now()
             Session().add(pull_request)
 
         # finally store audit logs
         for user_data in added_audit_reviewers:
             self._log_audit_action(
                 'repo.pull_request.reviewer.add', {'data': user_data},
                 user, pull_request)
         for user_data in removed_audit_reviewers:
             self._log_audit_action(
                 'repo.pull_request.reviewer.delete', {'old_data': user_data},
                 user, pull_request)
 
         self.notify_reviewers(pull_request, ids_to_add, user)
         return ids_to_add, ids_to_remove
 
     def update_observers(self, pull_request, observer_data, user):
         """
         Update the observers in the pull request
 
         :param pull_request: the pr to update
         :param observer_data: list of tuples
             [(user, ['reason1', 'reason2'], mandatory_flag, role, [rules])]
         :param user: current use who triggers this action
         """
         pull_request = self.__get_pull_request(pull_request)
         if pull_request.is_closed():
             raise ValueError('This pull request is closed')
 
         observers = {}
         for user_id, reasons, mandatory, role, rules in observer_data:
             if isinstance(user_id, (int, compat.string_types)):
                 user_id = self._get_user(user_id).user_id
             observers[user_id] = {
                 'reasons': reasons, 'observers': mandatory, 'role': role}
 
         observers_ids = set(observers.keys())
         current_observers = PullRequestReviewers.get_pull_request_reviewers(
             pull_request.pull_request_id, role=PullRequestReviewers.ROLE_OBSERVER)
 
         current_observers_ids = set([x.user.user_id for x in current_observers])
 
         ids_to_add = observers_ids.difference(current_observers_ids)
         ids_to_remove = current_observers_ids.difference(observers_ids)
 
         log.debug("Adding %s observer", ids_to_add)
         log.debug("Removing %s observer", ids_to_remove)
         changed = False
         added_audit_observers = []
         removed_audit_observers = []
 
         for uid in ids_to_add:
             changed = True
             _usr = self._get_user(uid)
             observer = PullRequestReviewers()
             observer.user = _usr
             observer.pull_request = pull_request
             observer.reasons = observers[uid]['reasons']
             # NOTE(marcink): mandatory shouldn't be changed now
             # observer.mandatory = observer[uid]['reasons']
 
             # NOTE(marcink): role should be hardcoded, so we won't edit it.
             observer.role = PullRequestReviewers.ROLE_OBSERVER
             Session().add(observer)
             added_audit_observers.append(observer.get_dict())
 
         for uid in ids_to_remove:
             changed = True
             # NOTE(marcink): we fetch "ALL" reviewers objects using .all().
             # This is an edge case that handles previous state of having the same reviewer twice.
             # this CAN happen due to the lack of DB checks
             observers = PullRequestReviewers.query()\
                 .filter(PullRequestReviewers.user_id == uid,
                         PullRequestReviewers.role == PullRequestReviewers.ROLE_OBSERVER,
                         PullRequestReviewers.pull_request == pull_request)\
                 .all()
 
             for obj in observers:
                 added_audit_observers.append(obj.get_dict())
                 Session().delete(obj)
 
         if changed:
             Session().expire_all()
             pull_request.updated_on = datetime.datetime.now()
             Session().add(pull_request)
 
         # finally store audit logs
         for user_data in added_audit_observers:
             self._log_audit_action(
                 'repo.pull_request.observer.add', {'data': user_data},
                 user, pull_request)
         for user_data in removed_audit_observers:
             self._log_audit_action(
                 'repo.pull_request.observer.delete', {'old_data': user_data},
                 user, pull_request)
 
         self.notify_observers(pull_request, ids_to_add, user)
         return ids_to_add, ids_to_remove
 
     def get_url(self, pull_request, request=None, permalink=False):
         if not request:
             request = get_current_request()
 
         if permalink:
             return request.route_url(
                 'pull_requests_global',
                 pull_request_id=pull_request.pull_request_id,)
         else:
             return request.route_url('pullrequest_show',
                 repo_name=safe_str(pull_request.target_repo.repo_name),
                 pull_request_id=pull_request.pull_request_id,)
 
     def get_shadow_clone_url(self, pull_request, request=None):
         """
         Returns qualified url pointing to the shadow repository. If this pull
         request is closed there is no shadow repository and ``None`` will be
         returned.
         """
         if pull_request.is_closed():
             return None
         else:
             pr_url = urllib.unquote(self.get_url(pull_request, request=request))
             return safe_unicode('{pr_url}/repository'.format(pr_url=pr_url))
 
     def _notify_reviewers(self, pull_request, user_ids, role, user):
         # notification to reviewers/observers
         if not user_ids:
             return
 
         log.debug('Notify following %s users about pull-request %s', role, user_ids)
 
         pull_request_obj = pull_request
         # get the current participants of this pull request
         recipients = user_ids
         notification_type = EmailNotificationModel.TYPE_PULL_REQUEST
 
         pr_source_repo = pull_request_obj.source_repo
         pr_target_repo = pull_request_obj.target_repo
 
         pr_url = h.route_url('pullrequest_show',
                              repo_name=pr_target_repo.repo_name,
                              pull_request_id=pull_request_obj.pull_request_id,)
 
         # set some variables for email notification
         pr_target_repo_url = h.route_url(
             'repo_summary', repo_name=pr_target_repo.repo_name)
 
         pr_source_repo_url = h.route_url(
             'repo_summary', repo_name=pr_source_repo.repo_name)
 
         # pull request specifics
         pull_request_commits = [
             (x.raw_id, x.message)
             for x in map(pr_source_repo.get_commit, pull_request.revisions)]
 
         current_rhodecode_user = user
         kwargs = {
             'user': current_rhodecode_user,
             'pull_request_author': pull_request.author,
             'pull_request': pull_request_obj,
             'pull_request_commits': pull_request_commits,
 
             'pull_request_target_repo': pr_target_repo,
             'pull_request_target_repo_url': pr_target_repo_url,
 
             'pull_request_source_repo': pr_source_repo,
             'pull_request_source_repo_url': pr_source_repo_url,
 
             'pull_request_url': pr_url,
             'thread_ids': [pr_url],
             'user_role': role
         }
 
         # create notification objects, and emails
         NotificationModel().create(
             created_by=current_rhodecode_user,
             notification_subject='',  # Filled in based on the notification_type
             notification_body='',  # Filled in based on the notification_type
             notification_type=notification_type,
             recipients=recipients,
             email_kwargs=kwargs,
         )
 
     def notify_reviewers(self, pull_request, reviewers_ids, user):
         return self._notify_reviewers(pull_request, reviewers_ids,
                                       PullRequestReviewers.ROLE_REVIEWER, user)
 
     def notify_observers(self, pull_request, observers_ids, user):
         return self._notify_reviewers(pull_request, observers_ids,
                                       PullRequestReviewers.ROLE_OBSERVER, user)
 
     def notify_users(self, pull_request, updating_user, ancestor_commit_id,
                      commit_changes, file_changes):
 
         updating_user_id = updating_user.user_id
         reviewers = set([x.user.user_id for x in pull_request.get_pull_request_reviewers()])
         # NOTE(marcink): send notification to all other users except to
         # person who updated the PR
         recipients = reviewers.difference(set([updating_user_id]))
 
         log.debug('Notify following recipients about pull-request update %s', recipients)
 
         pull_request_obj = pull_request
 
         # send email about the update
         changed_files = (
                 file_changes.added + file_changes.modified + file_changes.removed)
 
         pr_source_repo = pull_request_obj.source_repo
         pr_target_repo = pull_request_obj.target_repo
 
         pr_url = h.route_url('pullrequest_show',
                              repo_name=pr_target_repo.repo_name,
                              pull_request_id=pull_request_obj.pull_request_id,)
 
         # set some variables for email notification
         pr_target_repo_url = h.route_url(
             'repo_summary', repo_name=pr_target_repo.repo_name)
 
         pr_source_repo_url = h.route_url(
             'repo_summary', repo_name=pr_source_repo.repo_name)
 
         email_kwargs = {
             'date': datetime.datetime.now(),
             'updating_user': updating_user,
 
             'pull_request': pull_request_obj,
 
             'pull_request_target_repo': pr_target_repo,
             'pull_request_target_repo_url': pr_target_repo_url,
 
             'pull_request_source_repo': pr_source_repo,
             'pull_request_source_repo_url': pr_source_repo_url,
 
             'pull_request_url': pr_url,
 
             'ancestor_commit_id': ancestor_commit_id,
             'added_commits': commit_changes.added,
             'removed_commits': commit_changes.removed,
             'changed_files': changed_files,
             'added_files': file_changes.added,
             'modified_files': file_changes.modified,
             'removed_files': file_changes.removed,
             'thread_ids': [pr_url],
         }
 
         # create notification objects, and emails
         NotificationModel().create(
             created_by=updating_user,
             notification_subject='',  # Filled in based on the notification_type
             notification_body='',  # Filled in based on the notification_type
             notification_type=EmailNotificationModel.TYPE_PULL_REQUEST_UPDATE,
             recipients=recipients,
             email_kwargs=email_kwargs,
         )
 
     def delete(self, pull_request, user=None):
         if not user:
             user = getattr(get_current_rhodecode_user(), 'username', None)
 
         pull_request = self.__get_pull_request(pull_request)
         old_data = pull_request.get_api_data(with_merge_state=False)
         self._cleanup_merge_workspace(pull_request)
         self._log_audit_action(
             'repo.pull_request.delete', {'old_data': old_data},
             user, pull_request)
         Session().delete(pull_request)
 
     def close_pull_request(self, pull_request, user):
         pull_request = self.__get_pull_request(pull_request)
         self._cleanup_merge_workspace(pull_request)
         pull_request.status = PullRequest.STATUS_CLOSED
         pull_request.updated_on = datetime.datetime.now()
         Session().add(pull_request)
         self.trigger_pull_request_hook(pull_request, pull_request.author, 'close')
 
         pr_data = pull_request.get_api_data(with_merge_state=False)
         self._log_audit_action(
             'repo.pull_request.close', {'data': pr_data}, user, pull_request)
 
     def close_pull_request_with_comment(
             self, pull_request, user, repo, message=None, auth_user=None):
 
         pull_request_review_status = pull_request.calculated_review_status()
 
         if pull_request_review_status == ChangesetStatus.STATUS_APPROVED:
             # approved only if we have voting consent
             status = ChangesetStatus.STATUS_APPROVED
         else:
             status = ChangesetStatus.STATUS_REJECTED
         status_lbl = ChangesetStatus.get_status_lbl(status)
 
         default_message = (
             'Closing with status change {transition_icon} {status}.'
         ).format(transition_icon='>', status=status_lbl)
         text = message or default_message
 
         # create a comment, and link it to new status
         comment = CommentsModel().create(
             text=text,
             repo=repo.repo_id,
             user=user.user_id,
             pull_request=pull_request.pull_request_id,
             status_change=status_lbl,
             status_change_type=status,
             closing_pr=True,
             auth_user=auth_user,
         )
 
         # calculate old status before we change it
         old_calculated_status = pull_request.calculated_review_status()
         ChangesetStatusModel().set_status(
             repo.repo_id,
             status,
             user.user_id,
             comment=comment,
             pull_request=pull_request.pull_request_id
         )
 
         Session().flush()
 
         self.trigger_pull_request_hook(pull_request, user, 'comment',
                                        data={'comment': comment})
 
         # we now calculate the status of pull request again, and based on that
         # calculation trigger status change. This might happen in cases
         # that non-reviewer admin closes a pr, which means his vote doesn't
         # change the status, while if he's a reviewer this might change it.
         calculated_status = pull_request.calculated_review_status()
         if old_calculated_status != calculated_status:
             self.trigger_pull_request_hook(pull_request, user, 'review_status_change',
                                            data={'status': calculated_status})
 
         # finally close the PR
         PullRequestModel().close_pull_request(pull_request.pull_request_id, user)
 
         return comment, status
 
     def merge_status(self, pull_request, translator=None, force_shadow_repo_refresh=False):
         _ = translator or get_current_request().translate
 
         if not self._is_merge_enabled(pull_request):
             return None, False, _('Server-side pull request merging is disabled.')
 
         if pull_request.is_closed():
             return None, False, _('This pull request is closed.')
 
         merge_possible, msg = self._check_repo_requirements(
             target=pull_request.target_repo, source=pull_request.source_repo,
             translator=_)
         if not merge_possible:
             return None, merge_possible, msg
 
         try:
             merge_response = self._try_merge(
                 pull_request, force_shadow_repo_refresh=force_shadow_repo_refresh)
             log.debug("Merge response: %s", merge_response)
             return merge_response, merge_response.possible, merge_response.merge_status_message
         except NotImplementedError:
             return None, False, _('Pull request merging is not supported.')
 
     def _check_repo_requirements(self, target, source, translator):
         """
         Check if `target` and `source` have compatible requirements.
 
         Currently this is just checking for largefiles.
         """
         _ = translator
         target_has_largefiles = self._has_largefiles(target)
         source_has_largefiles = self._has_largefiles(source)
         merge_possible = True
         message = u''
 
         if target_has_largefiles != source_has_largefiles:
             merge_possible = False
             if source_has_largefiles:
                 message = _(
                     'Target repository large files support is disabled.')
             else:
                 message = _(
                     'Source repository large files support is disabled.')
 
         return merge_possible, message
 
     def _has_largefiles(self, repo):
         largefiles_ui = VcsSettingsModel(repo=repo).get_ui_settings(
             'extensions', 'largefiles')
         return largefiles_ui and largefiles_ui[0].active
 
     def _try_merge(self, pull_request, force_shadow_repo_refresh=False):
         """
         Try to merge the pull request and return the merge status.
         """
         log.debug(
             "Trying out if the pull request %s can be merged. Force_refresh=%s",
             pull_request.pull_request_id, force_shadow_repo_refresh)
         target_vcs = pull_request.target_repo.scm_instance()
         # Refresh the target reference.
         try:
             target_ref = self._refresh_reference(
                 pull_request.target_ref_parts, target_vcs)
         except CommitDoesNotExistError:
             merge_state = MergeResponse(
                 False, False, None, MergeFailureReason.MISSING_TARGET_REF,
                 metadata={'target_ref': pull_request.target_ref_parts})
             return merge_state
 
         target_locked = pull_request.target_repo.locked
         if target_locked and target_locked[0]:
             locked_by = 'user:{}'.format(target_locked[0])
             log.debug("The target repository is locked by %s.", locked_by)
             merge_state = MergeResponse(
                 False, False, None, MergeFailureReason.TARGET_IS_LOCKED,
                 metadata={'locked_by': locked_by})
         elif force_shadow_repo_refresh or self._needs_merge_state_refresh(
                 pull_request, target_ref):
             log.debug("Refreshing the merge status of the repository.")
             merge_state = self._refresh_merge_state(
                 pull_request, target_vcs, target_ref)
         else:
             possible = pull_request.last_merge_status == MergeFailureReason.NONE
             metadata = {
                 'unresolved_files': '',
                 'target_ref': pull_request.target_ref_parts,
                 'source_ref': pull_request.source_ref_parts,
             }
             if pull_request.last_merge_metadata:
                 metadata.update(pull_request.last_merge_metadata_parsed)
 
             if not possible and target_ref.type == 'branch':
                 # NOTE(marcink): case for mercurial multiple heads on branch
                 heads = target_vcs._heads(target_ref.name)
                 if len(heads) != 1:
                     heads = '\n,'.join(target_vcs._heads(target_ref.name))
                     metadata.update({
                         'heads': heads
                     })
 
             merge_state = MergeResponse(
                 possible, False, None, pull_request.last_merge_status, metadata=metadata)
 
         return merge_state
 
     def _refresh_reference(self, reference, vcs_repository):
         if reference.type in self.UPDATABLE_REF_TYPES:
             name_or_id = reference.name
         else:
             name_or_id = reference.commit_id
 
         refreshed_commit = vcs_repository.get_commit(name_or_id)
         refreshed_reference = Reference(
             reference.type, reference.name, refreshed_commit.raw_id)
         return refreshed_reference
 
     def _needs_merge_state_refresh(self, pull_request, target_reference):
         return not(
             pull_request.revisions and
             pull_request.revisions[0] == pull_request._last_merge_source_rev and
             target_reference.commit_id == pull_request._last_merge_target_rev)
 
     def _refresh_merge_state(self, pull_request, target_vcs, target_reference):
         workspace_id = self._workspace_id(pull_request)
         source_vcs = pull_request.source_repo.scm_instance()
         repo_id = pull_request.target_repo.repo_id
         use_rebase = self._use_rebase_for_merging(pull_request)
         close_branch = self._close_branch_before_merging(pull_request)
         merge_state = target_vcs.merge(
             repo_id, workspace_id,
             target_reference, source_vcs, pull_request.source_ref_parts,
             dry_run=True, use_rebase=use_rebase,
             close_branch=close_branch)
 
         # Do not store the response if there was an unknown error.
         if merge_state.failure_reason != MergeFailureReason.UNKNOWN:
             pull_request._last_merge_source_rev = \
                 pull_request.source_ref_parts.commit_id
             pull_request._last_merge_target_rev = target_reference.commit_id
             pull_request.last_merge_status = merge_state.failure_reason
             pull_request.last_merge_metadata = merge_state.metadata
 
             pull_request.shadow_merge_ref = merge_state.merge_ref
             Session().add(pull_request)
             Session().commit()
 
         return merge_state
 
     def _workspace_id(self, pull_request):
         workspace_id = 'pr-%s' % pull_request.pull_request_id
         return workspace_id
 
     def generate_repo_data(self, repo, commit_id=None, branch=None,
                            bookmark=None, translator=None):
         from rhodecode.model.repo import RepoModel
 
         all_refs, selected_ref = \
             self._get_repo_pullrequest_sources(
                 repo.scm_instance(), commit_id=commit_id,
                 branch=branch, bookmark=bookmark, translator=translator)
 
         refs_select2 = []
         for element in all_refs:
             children = [{'id': x[0], 'text': x[1]} for x in element[0]]
             refs_select2.append({'text': element[1], 'children': children})
 
         return {
             'user': {
                 'user_id': repo.user.user_id,
                 'username': repo.user.username,
                 'firstname': repo.user.first_name,
                 'lastname': repo.user.last_name,
                 'gravatar_link': h.gravatar_url(repo.user.email, 14),
             },
             'name': repo.repo_name,
             'link': RepoModel().get_url(repo),
             'description': h.chop_at_smart(repo.description_safe, '\n'),
             'refs': {
                 'all_refs': all_refs,
                 'selected_ref': selected_ref,
                 'select2_refs': refs_select2
             }
         }
 
     def generate_pullrequest_title(self, source, source_ref, target):
         return u'{source}#{at_ref} to {target}'.format(
             source=source,
             at_ref=source_ref,
             target=target,
         )
 
     def _cleanup_merge_workspace(self, pull_request):
         # Merging related cleanup
         repo_id = pull_request.target_repo.repo_id
         target_scm = pull_request.target_repo.scm_instance()
         workspace_id = self._workspace_id(pull_request)
 
         try:
             target_scm.cleanup_merge_workspace(repo_id, workspace_id)
         except NotImplementedError:
             pass
 
     def _get_repo_pullrequest_sources(
             self, repo, commit_id=None, branch=None, bookmark=None,
             translator=None):
         """
         Return a structure with repo's interesting commits, suitable for
         the selectors in pullrequest controller
 
         :param commit_id: a commit that must be in the list somehow
             and selected by default
         :param branch: a branch that must be in the list and selected
             by default - even if closed
         :param bookmark: a bookmark that must be in the list and selected
         """
         _ = translator or get_current_request().translate
 
         commit_id = safe_str(commit_id) if commit_id else None
         branch = safe_unicode(branch) if branch else None
         bookmark = safe_unicode(bookmark) if bookmark else None
 
         selected = None
 
         # order matters: first source that has commit_id in it will be selected
         sources = []
         sources.append(('book', repo.bookmarks.items(), _('Bookmarks'), bookmark))
         sources.append(('branch', repo.branches.items(), _('Branches'), branch))
 
         if commit_id:
             ref_commit = (h.short_id(commit_id), commit_id)
             sources.append(('rev', [ref_commit], _('Commit IDs'), commit_id))
 
         sources.append(
             ('branch', repo.branches_closed.items(), _('Closed Branches'), branch),
         )
 
         groups = []
 
         for group_key, ref_list, group_name, match in sources:
             group_refs = []
             for ref_name, ref_id in ref_list:
                 ref_key = u'{}:{}:{}'.format(group_key, ref_name, ref_id)
                 group_refs.append((ref_key, ref_name))
 
                 if not selected:
                     if set([commit_id, match]) & set([ref_id, ref_name]):
                         selected = ref_key
 
             if group_refs:
                 groups.append((group_refs, group_name))
 
         if not selected:
             ref = commit_id or branch or bookmark
             if ref:
                 raise CommitDoesNotExistError(
                     u'No commit refs could be found matching: {}'.format(ref))
             elif repo.DEFAULT_BRANCH_NAME in repo.branches:
                 selected = u'branch:{}:{}'.format(
                     safe_unicode(repo.DEFAULT_BRANCH_NAME),
                     safe_unicode(repo.branches[repo.DEFAULT_BRANCH_NAME])
                 )
             elif repo.commit_ids:
                 # make the user select in this case
                 selected = None
             else:
                 raise EmptyRepositoryError()
         return groups, selected
 
     def get_diff(self, source_repo, source_ref_id, target_ref_id,
                  hide_whitespace_changes, diff_context):
 
         return self._get_diff_from_pr_or_version(
             source_repo, source_ref_id, target_ref_id,
             hide_whitespace_changes=hide_whitespace_changes, diff_context=diff_context)
 
     def _get_diff_from_pr_or_version(
             self, source_repo, source_ref_id, target_ref_id,
             hide_whitespace_changes, diff_context):
 
         target_commit = source_repo.get_commit(
             commit_id=safe_str(target_ref_id))
         source_commit = source_repo.get_commit(
             commit_id=safe_str(source_ref_id), maybe_unreachable=True)
         if isinstance(source_repo, Repository):
             vcs_repo = source_repo.scm_instance()
         else:
             vcs_repo = source_repo
 
         # TODO: johbo: In the context of an update, we cannot reach
         # the old commit anymore with our normal mechanisms. It needs
         # some sort of special support in the vcs layer to avoid this
         # workaround.
         if (source_commit.raw_id == vcs_repo.EMPTY_COMMIT_ID and
                 vcs_repo.alias == 'git'):
             source_commit.raw_id = safe_str(source_ref_id)
 
         log.debug('calculating diff between '
                   'source_ref:%s and target_ref:%s for repo `%s`',
                   target_ref_id, source_ref_id,
                   safe_unicode(vcs_repo.path))
 
         vcs_diff = vcs_repo.get_diff(
             commit1=target_commit, commit2=source_commit,
             ignore_whitespace=hide_whitespace_changes, context=diff_context)
         return vcs_diff
 
     def _is_merge_enabled(self, pull_request):
         return self._get_general_setting(
             pull_request, 'rhodecode_pr_merge_enabled')
 
     def _use_rebase_for_merging(self, pull_request):
         repo_type = pull_request.target_repo.repo_type
         if repo_type == 'hg':
             return self._get_general_setting(
                 pull_request, 'rhodecode_hg_use_rebase_for_merging')
         elif repo_type == 'git':
             return self._get_general_setting(
                 pull_request, 'rhodecode_git_use_rebase_for_merging')
 
         return False
 
     def _user_name_for_merging(self, pull_request, user):
         env_user_name_attr = os.environ.get('RC_MERGE_USER_NAME_ATTR', '')
         if env_user_name_attr and hasattr(user, env_user_name_attr):
             user_name_attr = env_user_name_attr
         else:
             user_name_attr = 'short_contact'
 
         user_name = getattr(user, user_name_attr)
         return user_name
 
     def _close_branch_before_merging(self, pull_request):
         repo_type = pull_request.target_repo.repo_type
         if repo_type == 'hg':
             return self._get_general_setting(
                 pull_request, 'rhodecode_hg_close_branch_before_merging')
         elif repo_type == 'git':
             return self._get_general_setting(
                 pull_request, 'rhodecode_git_close_branch_before_merging')
 
         return False
 
     def _get_general_setting(self, pull_request, settings_key, default=False):
         settings_model = VcsSettingsModel(repo=pull_request.target_repo)
         settings = settings_model.get_general_settings()
         return settings.get(settings_key, default)
 
     def _log_audit_action(self, action, action_data, user, pull_request):
         audit_logger.store(
             action=action,
             action_data=action_data,
             user=user,
             repo=pull_request.target_repo)
 
     def get_reviewer_functions(self):
         """
         Fetches functions for validation and fetching default reviewers.
         If available we use the EE package, else we fallback to CE
         package functions
         """
         try:
             from rc_reviewers.utils import get_default_reviewers_data
             from rc_reviewers.utils import validate_default_reviewers
             from rc_reviewers.utils import validate_observers
         except ImportError:
             from rhodecode.apps.repository.utils import get_default_reviewers_data
             from rhodecode.apps.repository.utils import validate_default_reviewers
             from rhodecode.apps.repository.utils import validate_observers
 
         return get_default_reviewers_data, validate_default_reviewers, validate_observers
 
 
 class MergeCheck(object):
     """
     Perform Merge Checks and returns a check object which stores information
     about merge errors, and merge conditions
     """
     TODO_CHECK = 'todo'
     PERM_CHECK = 'perm'
     REVIEW_CHECK = 'review'
     MERGE_CHECK = 'merge'
     WIP_CHECK = 'wip'
 
     def __init__(self):
         self.review_status = None
         self.merge_possible = None
         self.merge_msg = ''
         self.merge_response = None
         self.failed = None
         self.errors = []
         self.error_details = OrderedDict()
         self.source_commit = AttributeDict()
         self.target_commit = AttributeDict()
         self.reviewers_count = 0
         self.observers_count = 0
 
     def __repr__(self):
         return '<MergeCheck(possible:{}, failed:{}, errors:{})>'.format(
             self.merge_possible, self.failed, self.errors)
 
     def push_error(self, error_type, message, error_key, details):
         self.failed = True
         self.errors.append([error_type, message])
         self.error_details[error_key] = dict(
             details=details,
             error_type=error_type,
             message=message
         )
 
     @classmethod
     def validate(cls, pull_request, auth_user, translator, fail_early=False,
                  force_shadow_repo_refresh=False):
         _ = translator
         merge_check = cls()
 
         # title has WIP:
         if pull_request.work_in_progress:
             log.debug("MergeCheck: cannot merge, title has wip: marker.")
 
             msg = _('WIP marker in title prevents from accidental merge.')
             merge_check.push_error('error', msg, cls.WIP_CHECK, pull_request.title)
             if fail_early:
                 return merge_check
 
         # permissions to merge
         user_allowed_to_merge = PullRequestModel().check_user_merge(pull_request, auth_user)
         if not user_allowed_to_merge:
             log.debug("MergeCheck: cannot merge, approval is pending.")
 
             msg = _('User `{}` not allowed to perform merge.').format(auth_user.username)
             merge_check.push_error('error', msg, cls.PERM_CHECK, auth_user.username)
             if fail_early:
                 return merge_check
 
         # permission to merge into the target branch
         target_commit_id = pull_request.target_ref_parts.commit_id
         if pull_request.target_ref_parts.type == 'branch':
             branch_name = pull_request.target_ref_parts.name
         else:
             # for mercurial we can always figure out the branch from the commit
             # in case of bookmark
             target_commit = pull_request.target_repo.get_commit(target_commit_id)
             branch_name = target_commit.branch
 
         rule, branch_perm = auth_user.get_rule_and_branch_permission(
             pull_request.target_repo.repo_name, branch_name)
         if branch_perm and branch_perm == 'branch.none':
             msg = _('Target branch `{}` changes rejected by rule {}.').format(
                 branch_name, rule)
             merge_check.push_error('error', msg, cls.PERM_CHECK, auth_user.username)
             if fail_early:
                 return merge_check
 
         # review status, must be always present
         review_status = pull_request.calculated_review_status()
         merge_check.review_status = review_status
         merge_check.reviewers_count = pull_request.reviewers_count
         merge_check.observers_count = pull_request.observers_count
 
         status_approved = review_status == ChangesetStatus.STATUS_APPROVED
         if not status_approved and merge_check.reviewers_count:
             log.debug("MergeCheck: cannot merge, approval is pending.")
             msg = _('Pull request reviewer approval is pending.')
 
             merge_check.push_error('warning', msg, cls.REVIEW_CHECK, review_status)
 
             if fail_early:
                 return merge_check
 
         # left over TODOs
         todos = CommentsModel().get_pull_request_unresolved_todos(pull_request)
         if todos:
             log.debug("MergeCheck: cannot merge, {} "
                       "unresolved TODOs left.".format(len(todos)))
 
             if len(todos) == 1:
                 msg = _('Cannot merge, {} TODO still not resolved.').format(
                     len(todos))
             else:
                 msg = _('Cannot merge, {} TODOs still not resolved.').format(
                     len(todos))
 
             merge_check.push_error('warning', msg, cls.TODO_CHECK, todos)
 
             if fail_early:
                 return merge_check
 
         # merge possible, here is the filesystem simulation + shadow repo
         merge_response, merge_status, msg = PullRequestModel().merge_status(
             pull_request, translator=translator,
             force_shadow_repo_refresh=force_shadow_repo_refresh)
 
         merge_check.merge_possible = merge_status
         merge_check.merge_msg = msg
         merge_check.merge_response = merge_response
 
         source_ref_id = pull_request.source_ref_parts.commit_id
         target_ref_id = pull_request.target_ref_parts.commit_id
 
         try:
             source_commit, target_commit = PullRequestModel().get_flow_commits(pull_request)
             merge_check.source_commit.changed = source_ref_id != source_commit.raw_id
             merge_check.source_commit.ref_spec = pull_request.source_ref_parts
             merge_check.source_commit.current_raw_id = source_commit.raw_id
             merge_check.source_commit.previous_raw_id = source_ref_id
 
             merge_check.target_commit.changed = target_ref_id != target_commit.raw_id
             merge_check.target_commit.ref_spec = pull_request.target_ref_parts
             merge_check.target_commit.current_raw_id = target_commit.raw_id
             merge_check.target_commit.previous_raw_id = target_ref_id
         except (SourceRefMissing, TargetRefMissing):
             pass
 
         if not merge_status:
             log.debug("MergeCheck: cannot merge, pull request merge not possible.")
             merge_check.push_error('warning', msg, cls.MERGE_CHECK, None)
 
             if fail_early:
                 return merge_check
 
         log.debug('MergeCheck: is failed: %s', merge_check.failed)
         return merge_check
 
     @classmethod
     def get_merge_conditions(cls, pull_request, translator):
         _ = translator
         merge_details = {}
 
         model = PullRequestModel()
         use_rebase = model._use_rebase_for_merging(pull_request)
 
         if use_rebase:
             merge_details['merge_strategy'] = dict(
                 details={},
                 message=_('Merge strategy: rebase')
             )
         else:
             merge_details['merge_strategy'] = dict(
                 details={},
                 message=_('Merge strategy: explicit merge commit')
             )
 
         close_branch = model._close_branch_before_merging(pull_request)
         if close_branch:
             repo_type = pull_request.target_repo.repo_type
             close_msg = ''
             if repo_type == 'hg':
                 close_msg = _('Source branch will be closed before the merge.')
             elif repo_type == 'git':
                 close_msg = _('Source branch will be deleted after the merge.')
 
             merge_details['close_branch'] = dict(
                 details={},
                 message=close_msg
             )
 
         return merge_details
 
 
 ChangeTuple = collections.namedtuple(
     'ChangeTuple', ['added', 'common', 'removed', 'total'])
 
 FileChangeTuple = collections.namedtuple(
     'FileChangeTuple', ['added', 'modified', 'removed'])