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Diffstat (limited to 'src/leap/soledad/client/_db/adbapi.py')
| -rw-r--r-- | src/leap/soledad/client/_db/adbapi.py | 298 |
1 files changed, 298 insertions, 0 deletions
diff --git a/src/leap/soledad/client/_db/adbapi.py b/src/leap/soledad/client/_db/adbapi.py new file mode 100644 index 00000000..5c28d108 --- /dev/null +++ b/src/leap/soledad/client/_db/adbapi.py @@ -0,0 +1,298 @@ +# -*- coding: utf-8 -*- +# adbapi.py +# Copyright (C) 2013, 2014 LEAP +# +# 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 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 General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see <http://www.gnu.org/licenses/>. +""" +An asyncrhonous interface to soledad using sqlcipher backend. +It uses twisted.enterprise.adbapi. +""" +import re +import sys + +from functools import partial + +from twisted.enterprise import adbapi +from twisted.internet.defer import DeferredSemaphore +from twisted.python import compat +from zope.proxy import ProxyBase, setProxiedObject + +from leap.soledad.common.log import getLogger +from leap.soledad.common.errors import DatabaseAccessError + +from . import sqlcipher +from . import pragmas + +if sys.version_info[0] < 3: + from pysqlcipher import dbapi2 +else: + from pysqlcipher3 import dbapi2 + + +logger = getLogger(__name__) + + +""" +How long the SQLCipher connection should wait for the lock to go away until +raising an exception. +""" +SQLCIPHER_CONNECTION_TIMEOUT = 10 + +""" +How many times a SQLCipher query should be retried in case of timeout. +""" +SQLCIPHER_MAX_RETRIES = 20 + + +def getConnectionPool(opts, openfun=None, driver="pysqlcipher"): + """ + Return a connection pool. + + :param opts: + Options for the SQLCipher connection. + :type opts: SQLCipherOptions + :param openfun: + Callback invoked after every connect() on the underlying DB-API + object. + :type openfun: callable + :param driver: + The connection driver. + :type driver: str + + :return: A U1DB connection pool. + :rtype: U1DBConnectionPool + """ + if openfun is None and driver == "pysqlcipher": + openfun = partial(pragmas.set_init_pragmas, opts=opts) + return U1DBConnectionPool( + opts, + # the following params are relayed "as is" to twisted's + # ConnectionPool. + "%s.dbapi2" % driver, opts.path, timeout=SQLCIPHER_CONNECTION_TIMEOUT, + check_same_thread=False, cp_openfun=openfun) + + +class U1DBConnection(adbapi.Connection): + """ + A wrapper for a U1DB connection instance. + """ + + u1db_wrapper = sqlcipher.SoledadSQLCipherWrapper + """ + The U1DB wrapper to use. + """ + + def __init__(self, pool, init_u1db=False): + """ + :param pool: The pool of connections to that owns this connection. + :type pool: adbapi.ConnectionPool + :param init_u1db: Wether the u1db database should be initialized. + :type init_u1db: bool + """ + self.init_u1db = init_u1db + try: + adbapi.Connection.__init__(self, pool) + except dbapi2.DatabaseError as e: + raise DatabaseAccessError( + 'Error initializing connection to sqlcipher database: %s' + % str(e)) + + def reconnect(self): + """ + Reconnect to the U1DB database. + """ + if self._connection is not None: + self._pool.disconnect(self._connection) + self._connection = self._pool.connect() + + if self.init_u1db: + self._u1db = self.u1db_wrapper( + self._connection, + self._pool.opts) + + def __getattr__(self, name): + """ + Route the requested attribute either to the U1DB wrapper or to the + connection. + + :param name: The name of the attribute. + :type name: str + """ + if name.startswith('u1db_'): + attr = re.sub('^u1db_', '', name) + return getattr(self._u1db, attr) + else: + return getattr(self._connection, name) + + +class U1DBTransaction(adbapi.Transaction): + """ + A wrapper for a U1DB 'cursor' object. + """ + + def __getattr__(self, name): + """ + Route the requested attribute either to the U1DB wrapper of the + connection or to the actual connection cursor. + + :param name: The name of the attribute. + :type name: str + """ + if name.startswith('u1db_'): + attr = re.sub('^u1db_', '', name) + return getattr(self._connection._u1db, attr) + else: + return getattr(self._cursor, name) + + +class U1DBConnectionPool(adbapi.ConnectionPool): + """ + Represent a pool of connections to an U1DB database. + """ + + connectionFactory = U1DBConnection + transactionFactory = U1DBTransaction + + def __init__(self, opts, *args, **kwargs): + """ + Initialize the connection pool. + """ + self.opts = opts + try: + adbapi.ConnectionPool.__init__(self, *args, **kwargs) + except dbapi2.DatabaseError as e: + raise DatabaseAccessError( + 'Error initializing u1db connection pool: %s' % str(e)) + + # all u1db connections, hashed by thread-id + self._u1dbconnections = {} + + # The replica uid, primed by the connections on init. + self.replica_uid = ProxyBase(None) + + try: + conn = self.connectionFactory( + self, init_u1db=True) + replica_uid = conn._u1db._real_replica_uid + setProxiedObject(self.replica_uid, replica_uid) + except DatabaseAccessError as e: + self.threadpool.stop() + raise DatabaseAccessError( + "Error initializing connection factory: %s" % str(e)) + + def runU1DBQuery(self, meth, *args, **kw): + """ + Execute a U1DB query in a thread, using a pooled connection. + + Concurrent threads trying to update the same database may timeout + because of other threads holding the database lock. Because of this, + we will retry SQLCIPHER_MAX_RETRIES times and fail after that. + + :param meth: The U1DB wrapper method name. + :type meth: str + + :return: a Deferred which will fire the return value of + 'self._runU1DBQuery(Transaction(...), *args, **kw)', or a Failure. + :rtype: twisted.internet.defer.Deferred + """ + meth = "u1db_%s" % meth + semaphore = DeferredSemaphore(SQLCIPHER_MAX_RETRIES) + + def _run_interaction(): + return self.runInteraction( + self._runU1DBQuery, meth, *args, **kw) + + def _errback(failure): + failure.trap(dbapi2.OperationalError) + if failure.getErrorMessage() == "database is locked": + logger.warn("database operation timed out") + should_retry = semaphore.acquire() + if should_retry: + logger.warn("trying again...") + return _run_interaction() + logger.warn("giving up!") + return failure + + d = _run_interaction() + d.addErrback(_errback) + return d + + def _runU1DBQuery(self, trans, meth, *args, **kw): + """ + Execute a U1DB query. + + :param trans: An U1DB transaction. + :type trans: adbapi.Transaction + :param meth: the U1DB wrapper method name. + :type meth: str + """ + meth = getattr(trans, meth) + return meth(*args, **kw) + # XXX should return a fetchall? + + # XXX add _runOperation too + + def _runInteraction(self, interaction, *args, **kw): + """ + Interact with the database and return the result. + + :param interaction: + A callable object whose first argument is an + L{adbapi.Transaction}. + :type interaction: callable + :return: a Deferred which will fire the return value of + 'interaction(Transaction(...), *args, **kw)', or a Failure. + :rtype: twisted.internet.defer.Deferred + """ + tid = self.threadID() + u1db = self._u1dbconnections.get(tid) + conn = self.connectionFactory( + self, init_u1db=not bool(u1db)) + + if self.replica_uid is None: + replica_uid = conn._u1db._real_replica_uid + setProxiedObject(self.replica_uid, replica_uid) + + if u1db is None: + self._u1dbconnections[tid] = conn._u1db + else: + conn._u1db = u1db + + trans = self.transactionFactory(self, conn) + try: + result = interaction(trans, *args, **kw) + trans.close() + conn.commit() + return result + except: + excType, excValue, excTraceback = sys.exc_info() + try: + conn.rollback() + except: + logger.error(None, "Rollback failed") + compat.reraise(excValue, excTraceback) + + def finalClose(self): + """ + A final close, only called by the shutdown trigger. + """ + self.shutdownID = None + if self.threadpool.started: + self.threadpool.stop() + self.running = False + for conn in self.connections.values(): + self._close(conn) + for u1db in self._u1dbconnections.values(): + self._close(u1db) + self.connections.clear() |