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# -*- coding: utf-8 -*-
# sync.py
# Copyright (C) 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/>.
"""
Soledad synchronization utilities.
"""
import logging
from twisted.internet import defer
from u1db import errors
from leap.soledad.common.errors import BackendNotReadyError
from u1db.sync import Synchronizer
logger = logging.getLogger(__name__)
class SoledadSynchronizer(Synchronizer):
"""
Collect the state around synchronizing 2 U1DB replicas.
Synchronization is bi-directional, in that new items in the source are sent
to the target, and new items in the target are returned to the source.
However, it still recognizes that one side is initiating the request. Also,
at the moment, conflicts are only created in the source.
Also modified to allow for interrupting the synchronization process.
"""
received_docs = []
@defer.inlineCallbacks
def sync(self, defer_decryption=True):
"""
Synchronize documents between source and target.
Differently from u1db `Synchronizer.sync` method, this one allows to
pass a `defer_decryption` flag that will postpone the last
step in the synchronization dance, namely, the setting of the last
known generation and transaction id for a given remote replica.
This is done to allow the ongoing parallel decryption of the incoming
docs to proceed without `InvalidGeneration` conflicts.
:param defer_decryption: Whether to defer the decryption process using
the intermediate database. If False,
decryption will be done inline.
:type defer_decryption: bool
:return: A deferred which will fire after the sync has finished with
the local generation before the synchronization was performed.
:rtype: twisted.internet.defer.Deferred
"""
sync_target = self.sync_target
self.received_docs = []
# get target identifier, its current generation,
# and its last-seen database generation for this source
ensure_callback = None
try:
(self.target_replica_uid, target_gen, target_trans_id,
target_my_gen, target_my_trans_id) = yield \
sync_target.get_sync_info(self.source._replica_uid)
except (errors.DatabaseDoesNotExist, BackendNotReadyError) as e:
logger.debug("Database isn't ready on server. Will be created.")
logger.debug("Reason: %s", e.__class__)
self.target_replica_uid = None
target_gen, target_trans_id = 0, ''
target_my_gen, target_my_trans_id = 0, ''
logger.debug(
"Soledad target sync info:\n"
" target replica uid: %s\n"
" target generation: %d\n"
" target trans id: %s\n"
" target my gen: %d\n"
" target my trans_id: %s\n"
" source replica_uid: %s\n"
% (self.target_replica_uid, target_gen, target_trans_id,
target_my_gen, target_my_trans_id, self.source._replica_uid))
# make sure we'll have access to target replica uid once it exists
if self.target_replica_uid is None:
def ensure_callback(replica_uid):
self.target_replica_uid = replica_uid
# make sure we're not syncing one replica with itself
if self.target_replica_uid == self.source._replica_uid:
raise errors.InvalidReplicaUID
# validate the info the target has about the source replica
self.source.validate_gen_and_trans_id(
target_my_gen, target_my_trans_id)
# what's changed since that generation and this current gen
my_gen, _, changes = self.source.whats_changed(target_my_gen)
logger.debug("Soledad sync: there are %d documents to send."
% len(changes))
# get source last-seen database generation for the target
if self.target_replica_uid is None:
target_last_known_gen, target_last_known_trans_id = 0, ''
else:
target_last_known_gen, target_last_known_trans_id = \
self.source._get_replica_gen_and_trans_id(
self.target_replica_uid)
logger.debug(
"Soledad source sync info:\n"
" last target gen known to source: %d\n"
" last target trans_id known to source: %s"
% (target_last_known_gen, target_last_known_trans_id))
# validate transaction ids
if not changes and target_last_known_gen == target_gen:
if target_trans_id != target_last_known_trans_id:
raise errors.InvalidTransactionId
defer.returnValue(my_gen)
# prepare to send all the changed docs
changed_doc_ids = [doc_id for doc_id, _, _ in changes]
docs_to_send = self.source.get_docs(
changed_doc_ids, check_for_conflicts=False, include_deleted=True)
ids_sent = []
docs_by_generation = []
idx = 0
for doc in docs_to_send:
_, gen, trans = changes[idx]
docs_by_generation.append((doc, gen, trans))
idx += 1
ids_sent.append(doc.doc_id)
# exchange documents and try to insert the returned ones with
# the target, return target synced-up-to gen.
new_gen, new_trans_id = yield sync_target.sync_exchange(
docs_by_generation, self.source._replica_uid,
target_last_known_gen, target_last_known_trans_id,
self._insert_doc_from_target, ensure_callback=ensure_callback,
defer_decryption=defer_decryption)
logger.debug(
"Soledad source sync info after sync exchange:\n"
" source known target gen: %d\n"
" source known target trans_id: %s"
% (new_gen, new_trans_id))
info = {
"target_replica_uid": self.target_replica_uid,
"new_gen": new_gen,
"new_trans_id": new_trans_id,
"my_gen": my_gen
}
self._syncing_info = info
yield self.complete_sync()
_, _, changes = self.source.whats_changed(target_my_gen)
changed_doc_ids = [doc_id for doc_id, _, _ in changes]
just_received = list(set(changed_doc_ids) - set(ids_sent))
self.received_docs = just_received
defer.returnValue(my_gen)
def complete_sync(self):
"""
Last stage of the synchronization:
(a) record last known generation and transaction uid for the remote
replica, and
(b) make target aware of our current reached generation.
:return: A deferred which will fire when the sync has been completed.
:rtype: twisted.internet.defer.Deferred
"""
logger.debug("Completing deferred last step in SYNC...")
# record target synced-up-to generation including applying what we
# sent
info = self._syncing_info
self.source._set_replica_gen_and_trans_id(
info["target_replica_uid"], info["new_gen"], info["new_trans_id"])
# if gapless record current reached generation with target
return self._record_sync_info_with_the_target(info["my_gen"])
def close(self):
"""
Close the synchronizer.
"""
self.sync_target.close()
def _record_sync_info_with_the_target(self, start_generation):
"""
Store local replica metadata in server.
:param start_generation: The local generation when the sync was
started.
:type start_generation: int
:return: A deferred which will fire when the operation has been
completed.
:rtype: twisted.internet.defer.Deferred
"""
cur_gen, trans_id = self.source._get_generation_info()
if (cur_gen == start_generation + self.num_inserted and
self.num_inserted > 0):
return self.sync_target.record_sync_info(
self.source._replica_uid, cur_gen, trans_id)
return defer.succeed(None)
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