offlineimap/offlineimap/folder/LocalStatusSQLite.py

389 lines
15 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
from sys import exc_info
from threading import Lock
try:
import sqlite3 as sqlite
except:
pass #fail only if needed later on, not on import
from .Base import BaseFolder
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.
dirname = os.path.dirname(self.filename)
if not os.path.exists(dirname):
os.makedirs(dirname)
if not os.path.isdir(dirname):
raise UserWarning("SQLite database path '%s' is not a directory."%
dirname)
# 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 cannot connect "
"with available bindings to '%s'. Is the sqlite3 package "
"installed?."% self.filename), None, exc_info()[2]
# 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 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 msglist_item_initializer(self, uid):
return {'uid': uid, 'flags': set(), 'labels': set(), 'time': 0, 'mtime': 0}
# Interface from BaseFolder
def cachemessagelist(self):
self.messagelist = {}
cursor = self.connection.execute('SELECT id,flags,mtime,labels from status')
for row in cursor:
uid = row[0]
self.messagelist[uid] = self.msglist_item_initializer(uid)
flags = set(row[1])
labels = set([lb.strip() for lb in row[3].split(',') if len(lb.strip()) > 0])
self.messagelist[uid]['flags'] = flags
self.messagelist[uid]['labels'] = labels
self.messagelist[uid]['mtime'] = row[2]
def dropmessagelistcache(self):
self.messagelist = {}
# 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] = self.msglist_item_initializer(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):
assert self.uidexists(uid)
self.messagelist[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])