view src/memory/persistent.py @ 853:c2f6ada7858f

core (sqlite): automatic database update: - new Updater class check database consistency (by calculating a hash on the .schema), and updates base if necessary - database now has a version (1 for current, 0 will be for 0.3's database), for each change this version will be increased - creation statements and update statements are in the form of dict of dict with tuples. There is a help text at the top of the module to explain how it works - if we are on a development version, the updater try to update the database automaticaly (without deleting table or columns). The Updater.generateUpdateData method can be used to ease the creation of update data (i.e. the dictionary at the top, see the one for the key 1 for an example). - if there is an inconsistency, an exception is raised, and a message indicate the SQL statements that should fix the situation. - well... this is rather complicated, a KISS method would maybe have been better. The future will say if we need to simplify it :-/ - new DatabaseError exception
author Goffi <goffi@goffi.org>
date Sun, 23 Feb 2014 23:30:32 +0100
parents 1fe00f0c9a91
children 8f8bdd31375a
line wrap: on
line source

#!/usr/bin/python
# -*- coding: utf-8 -*-

# SAT: a jabber client
# Copyright (C) 2009, 2010, 2011, 2012, 2013, 2014 Jérôme Poisson (goffi@goffi.org)

# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero 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/>.

from sat.core.i18n import _
from logging import debug, info, warning, error


class MemoryNotInitializedError(Exception):
    pass


class PersistentDict(object):
    r"""A dictionary which save persistently each value assigned
    /!\ be careful, each assignment means a database write
    /!\ Memory must be initialised before loading/setting value with instances of this class"""
    storage = None

    def __init__(self, namespace, profile=None):
        """@param namespace: unique namespace for this dictionary
        @param profile: profile which *MUST* exists, or None for general values"""
        if not self.storage:
            error(_("PersistentDict can't be used before memory initialisation"))
            raise MemoryNotInitializedError
        self._cache = {}
        self.namespace = namespace
        self.profile = profile

    def load(self):
        """load persistent data from storage
        """
        if not self.profile:
            return self.storage.loadGenPrivates(self._cache, self.namespace)
        else:
            return self.storage.loadIndPrivates(self._cache, self.namespace, self.profile)

    def __repr__(self):
        return self._cache.__repr__()

    def __str__(self):
        return self._cache.__str__()

    def __lt__(self, other):
        return self._cache.__lt__(other)

    def __le__(self, other):
        return self._cache.__le__(other)

    def __eq__(self, other):
        return self._cache.__eq__(other)

    def __ne__(self, other):
        return self._cache.__ne__(other)

    def __gt__(self, other):
        return self._cache.__gt__(other)

    def __ge__(self, other):
        return self._cache.__ge__(other)

    def __cmp__(self, other):
        return self._cache.__cmp__(other)

    def __hash__(self):
        return self._cache.__hash__()

    def __nonzero__(self):
        return self._cache.__len__()

    def __contains__(self, key):
        return self._cache.__contains__(key)

    def __getitem__(self, key):
        return self._cache.__getitem__(key)

    def __setitem__(self, key, value):
        if not self.profile:
            self.storage.setGenPrivate(self.namespace, key, value)
        else:
            self.storage.setIndPrivate(self.namespace, key, value, self.profile)
        return self._cache.__setitem__(key, value)

    def __delitem__(self, key):
        if not self.profile:
            self.storage.delGenPrivate(self.namespace, key)
        else:
            self.storage.delIndPrivate(self.namespace, key, self.profile)
        return self._cache.__delitem__(key)

    def get(self, key, default=None):
        return self._cache.get(key, default)

    def force(self, name):
        """Force saving of an attribute to storage
        @return: deferred fired when data is actually saved"""
        if not self.profile:
            return self.storage.setGenPrivate(self.namespace, name, self._cache[name])
        return self.storage.setIndPrivate(self.namespace, name, self._cache[name], self.profile)


class PersistentBinaryDict(PersistentDict):
    """Persistent dict where value can be any python data (instead of string only)"""

    def load(self):
        """load persistent data from storage
        """
        if not self.profile:
            return self.storage.loadGenPrivatesBinary(self._cache, self.namespace)
        else:
            return self.storage.loadIndPrivatesBinary(self._cache, self.namespace, self.profile)

    def __setitem__(self, key, value):
        if not self.profile:
            self.storage.setGenPrivateBinary(self.namespace, key, value)
        else:
            self.storage.setIndPrivateBinary(self.namespace, key, value, self.profile)
        return self._cache.__setitem__(key, value)

    def __delitem__(self, key):
        if not self.profile:
            self.storage.delGenPrivateBinary(self.namespace, key)
        else:
            self.storage.delIndPrivateBinary(self.namespace, key, self.profile)
        return self._cache.__delitem__(key)

    def force(self, name):
        """Force saving of an attribute to storage
        @return: deferred fired when data is actually saved"""
        if not self.profile:
            return self.storage.setGenPrivateBinary(self.namespace, name, self._cache[name])
        return self.storage.setIndPrivateBinary(self.namespace, name, self._cache[name], self.profile)