docker-offlineimap/offlineimap/folder/LocalStatusSQLite.py
Abdo Roig-Maranges 1b954c3b4c Add ability to migrate status data across backends
If when we request a LocalStatus folder, the folder has to be created,
we look whether the other backend has data, and if it does we migrate
it to the new backend.

The old backend data is left untouched, so that if you change back say
from sqlite to plaintext, the older data is still there.  That should
not lead to data loss, only a slower sync while the status folder gets
updated.

Signed-off-by: Eygene Ryabinkin <rea@codelabs.ru>
2014-05-06 23:37:11 +04:00

366 lines
14 KiB
Python

# 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 threading import Lock
from .Base import BaseFolder
try:
import sqlite3 as sqlite
except:
pass #fail only if needed later on, not on import
class LocalStatusSQLiteFolder(BaseFolder):
"""LocalStatus backend implemented with an SQLite database
As python-sqlite currently does not allow to access the same sqlite
objects from various threads, we need to open get and close a db
connection and cursor for all operations. This is a big disadvantage
and we might want to investigate if we cannot hold an object open
for a thread somehow."""
#though. According to sqlite docs, you need to commit() before
#the connection is closed or your changes will be lost!"""
#get db connection which autocommits
#connection = sqlite.connect(self.filename, isolation_level=None)
#cursor = connection.cursor()
#return connection, cursor
#current version of our db format
cur_version = 2
def __init__(self, name, repository):
self.sep = '.' #needs to be set before super.__init__()
super(LocalStatusSQLiteFolder, self).__init__(name, repository)
self.root = repository.root
self.filename = os.path.join(self.getroot(), self.getfolderbasename())
self.messagelist = {}
self._newfolder = False # flag if the folder is new
# dblock protects against concurrent writes in same connection
self._dblock = Lock()
#Try to establish connection, no need for threadsafety in __init__
try:
self.connection = sqlite.connect(self.filename, check_same_thread = False)
except NameError:
# sqlite import had failed
raise UserWarning('SQLite backend chosen, but no sqlite python '
'bindings available. Please install.')
#Make sure sqlite is in multithreading SERIALIZE mode
assert sqlite.threadsafety == 1, 'Your sqlite is not multithreading safe.'
#Test if db version is current enough and if db is readable.
try:
cursor = self.connection.execute("SELECT value from metadata WHERE key='db_version'")
except sqlite.DatabaseError:
#db file missing or corrupt, recreate it.
self.__create_db()
else:
# fetch db version and upgrade if needed
version = int(cursor.fetchone()[0])
if version < LocalStatusSQLiteFolder.cur_version:
self.__upgrade_db(version)
def storesmessages(self):
return False
def getname(self):
return self.name
def getfullname(self):
return self.filename
# Interface from LocalStatusFolder
def isnewfolder(self):
return self._newfolder
# Interface from LocalStatusFolder
def deletemessagelist(self):
"""delete all messages in the db"""
self.__sql_write('DELETE FROM status')
def __sql_write(self, sql, vars=None, executemany=False):
"""Execute some SQL, retrying if the db was locked.
:param sql: the SQL string passed to execute()
:param vars: the variable values to `sql`. E.g. (1,2) or {uid:1,
flags:'T'}. See sqlite docs for possibilities.
:param executemany: bool indicating whether we want to
perform conn.executemany() or conn.execute().
:returns: the Cursor() or raises an Exception"""
success = False
while not success:
self._dblock.acquire()
try:
if vars is None:
if executemany:
cursor = self.connection.executemany(sql)
else:
cursor = self.connection.execute(sql)
else:
if executemany:
cursor = self.connection.executemany(sql, vars)
else:
cursor = self.connection.execute(sql, vars)
success = True
self.connection.commit()
except sqlite.OperationalError as e:
if e.args[0] == 'cannot commit - no transaction is active':
pass
elif e.args[0] == 'database is locked':
self.ui.debug('', "Locked sqlite database, retrying.")
success = False
else:
raise
finally:
self._dblock.release()
return cursor
def __upgrade_db(self, from_ver):
"""Upgrade the sqlite format from version 'from_ver' to current"""
if hasattr(self, 'connection'):
self.connection.close() #close old connections first
self.connection = sqlite.connect(self.filename,
check_same_thread = False)
# Upgrade from database version 1 to version 2
# This change adds labels and mtime columns, to be used by Gmail IMAP and Maildir folders.
if from_ver <= 1:
self.ui._msg('Upgrading LocalStatus cache from version 1 to version 2 for %s:%s' %\
(self.repository, self))
self.connection.executescript("""ALTER TABLE status ADD mtime INTEGER DEFAULT 0;
ALTER TABLE status ADD labels VARCHAR(256) DEFAULT '';
UPDATE metadata SET value='2' WHERE key='db_version';
""")
self.connection.commit()
# Future version upgrades come here...
# if from_ver <= 2: ... #upgrade from 2 to 3
# if from_ver <= 3: ... #upgrade from 3 to 4
def __create_db(self):
"""
Create a new db file.
self.connection must point to the opened and valid SQlite
database connection.
"""
self.ui._msg('Creating new Local Status db for %s:%s' \
% (self.repository, self))
self.connection.executescript("""
CREATE TABLE metadata (key VARCHAR(50) PRIMARY KEY, value VARCHAR(128));
INSERT INTO metadata VALUES('db_version', '2');
CREATE TABLE status (id INTEGER PRIMARY KEY, flags VARCHAR(50), mtime INTEGER, labels VARCHAR(256));
""")
self.connection.commit()
self._newfolder = True
# Interface from BaseFolder
def cachemessagelist(self):
self.messagelist = {}
cursor = self.connection.execute('SELECT id,flags,mtime,labels from status')
for row in cursor:
flags = set(row[1])
labels = set([lb.strip() for lb in row[3].split(',') if len(lb.strip()) > 0])
self.messagelist[row[0]] = {'uid': row[0], 'flags': flags, 'mtime': row[2], 'labels': labels}
# Interface from LocalStatusFolder
def save(self):
pass
# Noop. every transaction commits to database!
def saveall(self):
"""Saves the entire messagelist to the database."""
data = []
for uid, msg in self.messagelist.items():
mtime = msg['mtime']
flags = ''.join(sorted(msg['flags']))
labels = ', '.join(sorted(msg['labels']))
data.append((uid, flags, mtime, labels))
self.__sql_write('INSERT OR REPLACE INTO status (id,flags,mtime,labels) VALUES (?,?,?,?)',
data, executemany=True)
# Following some pure SQLite functions, where we chose to use
# BaseFolder() methods instead. Doing those on the in-memory list is
# quicker anyway. If our db becomes so big that we don't want to
# maintain the in-memory list anymore, these might come in handy
# in the future though.
#
#def uidexists(self,uid):
# conn, cursor = self.get_cursor()
# with conn:
# cursor.execute('SELECT id FROM status WHERE id=:id',{'id': uid})
# return cursor.fetchone()
# This would be the pure SQLite solution, use BaseFolder() method,
# to avoid threading with sqlite...
#def getmessageuidlist(self):
# conn, cursor = self.get_cursor()
# with conn:
# cursor.execute('SELECT id from status')
# r = []
# for row in cursor:
# r.append(row[0])
# return r
#def getmessagecount(self):
# conn, cursor = self.get_cursor()
# with conn:
# cursor.execute('SELECT count(id) from status');
# return cursor.fetchone()[0]
#def getmessageflags(self, uid):
# conn, cursor = self.get_cursor()
# with conn:
# cursor.execute('SELECT flags FROM status WHERE id=:id',
# {'id': uid})
# for row in cursor:
# flags = [x for x in row[0]]
# return flags
# assert False,"getmessageflags() called on non-existing message"
# Interface from BaseFolder
def getmessagelist(self):
return self.messagelist
# Interface from BaseFolder
def savemessage(self, uid, content, flags, rtime, mtime=0, labels=set()):
"""
Writes a new message, with the specified uid.
See folder/Base for detail. Note that savemessage() does not
check against dryrun settings, so you need to ensure that
savemessage is never called in a dryrun mode.
"""
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, 'mtime': mtime, 'labels': labels}
flags = ''.join(sorted(flags))
labels = ', '.join(sorted(labels))
self.__sql_write('INSERT INTO status (id,flags,mtime,labels) VALUES (?,?,?,?)',
(uid,flags,mtime,labels))
return uid
# Interface from BaseFolder
def savemessageflags(self, uid, flags):
self.messagelist[uid] = {'uid': uid, 'flags': flags}
flags = ''.join(sorted(flags))
self.__sql_write('UPDATE status SET flags=? WHERE id=?',(flags,uid))
def getmessageflags(self, uid):
return self.messagelist[uid]['flags']
def savemessagelabels(self, uid, labels, mtime=None):
self.messagelist[uid]['labels'] = labels
if mtime: self.messagelist[uid]['mtime'] = mtime
labels = ', '.join(sorted(labels))
if mtime:
self.__sql_write('UPDATE status SET labels=?, mtime=? WHERE id=?',(labels,mtime,uid))
else:
self.__sql_write('UPDATE status SET labels=? WHERE id=?',(labels,uid))
def savemessageslabelsbulk(self, labels):
"""
Saves labels from a dictionary in a single database operation.
"""
data = [(', '.join(sorted(l)), uid) for uid, l in labels.items()]
self.__sql_write('UPDATE status SET labels=? WHERE id=?', data, executemany=True)
for uid, l in labels.items():
self.messagelist[uid]['labels'] = l
def addmessageslabels(self, uids, labels):
data = []
for uid in uids:
newlabels = self.messagelist[uid]['labels'] | labels
data.append((', '.join(sorted(newlabels)), uid))
self.__sql_write('UPDATE status SET labels=? WHERE id=?', data, executemany=True)
for uid in uids:
self.messagelist[uid]['labels'] = self.messagelist[uid]['labels'] | labels
def deletemessageslabels(self, uids, labels):
data = []
for uid in uids:
newlabels = self.messagelist[uid]['labels'] - labels
data.append((', '.join(sorted(newlabels)), uid))
self.__sql_write('UPDATE status SET labels=? WHERE id=?', data, executemany=True)
for uid in uids:
self.messagelist[uid]['labels'] = self.messagelist[uid]['labels'] - labels
def getmessagelabels(self, uid):
return self.messagelist[uid]['labels']
def savemessagesmtimebulk(self, mtimes):
"""Saves mtimes from the mtimes dictionary in a single database operation."""
data = [(mt, uid) for uid, mt in mtimes.items()]
self.__sql_write('UPDATE status SET mtime=? WHERE id=?', data, executemany=True)
for uid, mt in mtimes.items():
self.messagelist[uid]['mtime'] = mt
def getmessagemtime(self, uid):
return self.messagelist[uid]['mtime']
# Interface from BaseFolder
def deletemessage(self, uid):
if not uid in self.messagelist:
return
self.__sql_write('DELETE FROM status WHERE id=?', (uid, ))
del(self.messagelist[uid])
# Interface from BaseFolder
def deletemessages(self, uidlist):
"""Delete list of UIDs from status cache
This function uses sqlites executemany() function which is
much faster than iterating through deletemessage() when we have
many messages to delete."""
# Weed out ones not in self.messagelist
uidlist = [uid for uid in uidlist if uid in self.messagelist]
if not len(uidlist):
return
# arg2 needs to be an iterable of 1-tuples [(1,),(2,),...]
self.__sql_write('DELETE FROM status WHERE id=?', zip(uidlist, ), True)
for uid in uidlist:
del(self.messagelist[uid])