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Experimental LocalStatus stored in SQLite database

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Based on patches by Stewart Smith, updated by Rob Browning.

plus:
- Inherit LocalStatusSQLFolder from LocalStatusFolder
  This lets us remove all functions that are available via our ancestors
  classes and are not needed.

- Don't fail if pysql import fails. Fail rather at runtime when needed.

- When creating the db file, create a metadata table which contains the
  format version info, so we can upgrade nicely to other formats.

- Create an upgrade_db() function which allows us to upgrade from any
  previous file format to the current one (including plain text)

Signed-off-by: Sebastian Spaeth <Sebastian@SSpaeth.de>
Signed-off-by: Nicolas Sebrecht <nicolas.s-dev@laposte.net>
This commit is contained in:
Sebastian Spaeth
2011-05-05 15:59:24 +02:00
committed by Nicolas Sebrecht
parent 535f4592fc
commit 2fc12e875a
3 changed files with 195 additions and 3 deletions
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192
offlineimap/folder/LocalStatusSQLite.py Normal file
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# Local status cache virtual folder: SQLite backend
# Copyright (C) 2009-2011 Stewart Smith and contributors
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
import os.path
import re
from LocalStatus import LocalStatusFolder, magicline
try:
from pysqlite2 import dbapi2 as sqlite
except:
pass #fail only if needed later on, not on import
class LocalStatusSQLiteFolder(LocalStatusFolder):
"""LocalStatus backend implemented with an SQLite database"""
#current version of the db format
cur_version = 1
def __init__(self, root, name, repository, accountname, config):
super(LocalStatusSQLiteFolder, self).__init__(root, name,
repository,
accountname,
config)
#Try to establish connection
try:
self.connection = sqlite.connect(self.filename)
except NameError:
# sqlite import had failed
raise UserWarning('SQLite backend chosen, but no sqlite python '
'bindings available. Please install.')
#Test if the db version is current enough and if the db is
#readable.
try:
self.cursor = self.connection.cursor()
self.cursor.execute("SELECT value from metadata WHERE key='db_version'")
except sqlite.DatabaseError:
#db file missing or corrupt, recreate it.
self.connection.close()
self.upgrade_db(0)
else:
# fetch db version and upgrade if needed
version = int(self.cursor.fetchone()[0])
self.cursor.close()
if version < LocalStatusSQLiteFolder.cur_version:
self.upgrade_db(version)
self.connection.close()
def upgrade_db(self, from_ver):
"""Upgrade the sqlite format from version 'from_ver' to current"""
if from_ver == 0:
# from_ver==0: no db existent: plain text migration?
self.create_db()
# below was derived from repository.getfolderfilename() logic
plaintextfilename = os.path.join(
self.repository.account.getaccountmeta(),
'LocalStatus',
re.sub('(^|\/)\.$','\\1dot', self.name))
# MIGRATE from plaintext if needed
if os.path.exists(plaintextfilename):
self.ui._msg('Migrating LocalStatus cache from plain text '
'to sqlite database for %s:%s' %\
(self.repository, self))
file = open(plaintextfilename, "rt")
line = file.readline().strip()
assert(line == magicline)
connection = sqlite.connect(self.filename)
cursor = connection.cursor()
for line in file.xreadlines():
line = line.strip()
uid, flags = line.split(':')
uid = long(uid)
flags = [x for x in flags]
flags.sort()
flags = ''.join(flags)
self.cursor.execute('INSERT INTO status (id,flags) VALUES (?,?)',
(uid,flags))
file.close()
self.connection.commit()
os.rename(plaintextfilename, plaintextfilename + ".old")
self.connection.close()
# Future version upgrades come here...
# if from_ver <= 1: ... #upgrade from 1 to 2
# if from_ver <= 2: ... #upgrade from 2 to 3
def create_db(self):
"""Create a new db file"""
self.ui._msg('Creating new Local Status db for %s:%s' \
% (self.repository, self))
connection = sqlite.connect(self.filename)
cursor = connection.cursor()
cursor.execute('CREATE TABLE metadata (key VARCHAR(50) PRIMARY KEY, value VARCHAR(128))')
cursor.execute("INSERT INTO metadata VALUES('db_version', '1')")
cursor.execute('CREATE TABLE status (id INTEGER PRIMARY KEY, flags VARCHAR(50))')
self.autosave() #commit if needed
def isnewfolder(self):
# testing the existence of the db file won't work. It is created
# as soon as this class instance was intitiated. So say it is a
# new folder when there are no messages at all recorded in it.
return self.getmessagecount() > 0
def deletemessagelist(self):
"""delete all messages in the db"""
self.cursor.execute('DELETE FROM status')
def cachemessagelist(self):
self.messagelist = {}
self.cursor.execute('SELECT id,flags from status')
for row in self.cursor:
flags = [x for x in row[1]]
self.messagelist[row[0]] = {'uid': row[0], 'flags': flags}
def save(self):
#Noop in this backend
pass
def uidexists(self,uid):
self.cursor.execute('SELECT id FROM status WHERE id=:id',{'id': uid})
for row in self.cursor:
if(row[0]==uid):
return 1
return 0
def getmessageuidlist(self):
self.cursor.execute('SELECT id from status')
r = []
for row in self.cursor:
r.append(row[0])
return r
def getmessagecount(self):
self.cursor.execute('SELECT count(id) from status');
row = self.cursor.fetchone()
return row[0]
def savemessage(self, uid, content, flags, rtime):
if uid < 0:
# We cannot assign a uid.
return uid
if self.uidexists(uid): # already have it
self.savemessageflags(uid, flags)
return uid
self.messagelist[uid] = {'uid': uid, 'flags': flags, 'time': rtime}
flags.sort()
flags = ''.join(flags)
self.cursor.execute('INSERT INTO status (id,flags) VALUES (?,?)',
(uid,flags))
self.autosave()
return uid
def getmessageflags(self, uid):
self.cursor.execute('SELECT flags FROM status WHERE id=:id',
{'id': uid})
for row in self.cursor:
flags = [x for x in row[0]]
return flags
assert False,"getmessageflags() called on non-existing message"
def getmessagetime(self, uid):
return self.messagelist[uid]['time']
def savemessageflags(self, uid, flags):
self.messagelist[uid] = {'uid': uid, 'flags': flags}
flags.sort()
flags = ''.join(flags)
self.cursor.execute('UPDATE status SET flags=? WHERE id=?',(flags,uid))
self.autosave()
def deletemessages(self, uidlist):
# Weed out ones not in self.messagelist
uidlist = [uid for uid in uidlist if uid in self.messagelist]
if not len(uidlist):
return
for uid in uidlist:
del(self.messagelist[uid])
#if self.uidexists(uid):
self.cursor.execute('DELETE FROM status WHERE id=:id', {'id': uid})