server/pool.py
author Pierre-Yves David <pierre-yves.david@logilab.fr>
Tue, 02 Feb 2010 18:22:25 +0100
changeset 4428 03614b377ecd
parent 4252 6c4f109c2b03
child 4710 4d9ad6a4f261
permissions -rw-r--r--
Add a ``schema`` command to cmd ctrl to generate schema image. This changeset add the new commande and do some refactoring in cwconfig and schema.py to allow the use of CubicWebNoAppConfiguration with CubicWebSchemaLoader.

"""CubicWeb server connections pool : the repository has a limited number of
connections pools, each of them dealing with a set of connections on each source
used by the repository. A connections pools (`ConnectionsPool`) is an
abstraction for a group of connection to each source.


:organization: Logilab
:copyright: 2001-2010 LOGILAB S.A. (Paris, FRANCE), license is LGPL v2.
:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr
:license: GNU Lesser General Public License, v2.1 - http://www.gnu.org/licenses
"""
__docformat__ = "restructuredtext en"

import sys

class ConnectionsPool(object):
    """handle connections on a set of sources, at some point associated to a
    user session
    """

    def __init__(self, sources):
        # dictionnary of (source, connection), indexed by sources'uri
        self.source_cnxs = {}
        for source in sources:
            self.source_cnxs[source.uri] = (source, source.get_connection())
        if not 'system' in self.source_cnxs:
            self.source_cnxs['system'] = self.source_cnxs[sources[0].uri]
        self._cursors = {}

    def __getitem__(self, uri):
        """subscription notation provide access to sources'cursors"""
        try:
            cursor = self._cursors[uri]
        except KeyError:
            cursor = self.source_cnxs[uri][1].cursor()
            if cursor is not None:
                # None possible on sources without cursor support such as ldap
                self._cursors[uri] = cursor
        return cursor

    def commit(self):
        """commit the current transaction for this user"""
        # FIXME: what happends if a commit fail
        # would need a two phases commit or like, but I don't know how to do
        # this using the db-api...
        for source, cnx in self.source_cnxs.values():
            # let exception propagates
            cnx.commit()

    def rollback(self):
        """rollback the current transaction for this user"""
        for source, cnx in self.source_cnxs.values():
            # catch exceptions, rollback other sources anyway
            try:
                cnx.rollback()
            except:
                source.critical('rollback error', exc_info=sys.exc_info())

    def close(self, i_know_what_i_do=False):
        """close all connections in the pool"""
        if i_know_what_i_do is not True: # unexpected closing safety belt
            raise RuntimeError('pool shouldn\'t be closed')
        for cu in self._cursors.values():
            try:
                cu.close()
            except:
                continue
        for _, cnx in self.source_cnxs.values():
            try:
                cnx.close()
            except:
                continue

    # internals ###############################################################

    def pool_set(self):
        """pool is being set"""
        self.check_connections()

    def pool_reset(self):
        """pool is being reseted"""
        for source, cnx in self.source_cnxs.values():
            source.pool_reset(cnx)

    def sources(self):
        """return the source objects handled by this pool"""
        # implementation details of flying insert requires the system source
        # first
        yield self.source_cnxs['system'][0]
        for uri, (source, cursor) in self.source_cnxs.items():
            if uri == 'system':
                continue
            yield source
        #return [source_cnx[0] for source_cnx in self.source_cnxs.values()]

    def source(self, uid):
        """return the source object with the given uri"""
        return self.source_cnxs[uid][0]

    def connection(self, uid):
        """return the connection on the source object with the given uri"""
        return self.source_cnxs[uid][1]

    def reconnect(self, source=None):
        """reopen a connection for this source or all sources if none specified
        """
        if source is None:
            sources = self.sources()
        else:
            sources = (source,)
        for source in sources:
            source.info('trying to reconnect')
            self.source_cnxs[source.uri] = (source, source.get_connection())
            self._cursors.pop(source.uri, None)

    def check_connections(self):
        for source, cnx in self.source_cnxs.itervalues():
            newcnx = source.check_connection(cnx)
            if newcnx is not None:
                self.reset_connection(source, newcnx)

    def reset_connection(self, source, cnx):
        self.source_cnxs[source.uri] = (source, cnx)
        self._cursors.pop(source.uri, None)


from cubicweb.server.hook import (Operation, LateOperation, SingleOperation,
                                  SingleLastOperation)
from logilab.common.deprecation import class_moved, class_renamed
Operation = class_moved(Operation)
PreCommitOperation = class_renamed('PreCommitOperation', Operation)
LateOperation = class_moved(LateOperation)
SingleOperation = class_moved(SingleOperation)
SingleLastOperation = class_moved(SingleLastOperation)