diff options
Diffstat (limited to 'client/src/leap/soledad/client/sqlcipher.py')
| -rw-r--r-- | client/src/leap/soledad/client/sqlcipher.py | 26 |
1 files changed, 23 insertions, 3 deletions
diff --git a/client/src/leap/soledad/client/sqlcipher.py b/client/src/leap/soledad/client/sqlcipher.py index 576b51ad..5ffa9c7e 100644 --- a/client/src/leap/soledad/client/sqlcipher.py +++ b/client/src/leap/soledad/client/sqlcipher.py @@ -52,6 +52,7 @@ import json from hashlib import sha256 from contextlib import contextmanager +from collections import defaultdict from pysqlcipher import dbapi2 from u1db.backends import sqlite_backend @@ -153,6 +154,13 @@ class SQLCipherDatabase(sqlite_backend.SQLitePartialExpandDatabase): create_doc_lock = threading.Lock() update_indexes_lock = threading.Lock() + syncing_lock = defaultdict(threading.Lock) + """ + A dictionary that hold locks which avoid multiple sync attempts from the + same database replica. + """ + + def __init__(self, sqlcipher_file, password, document_factory=None, crypto=None, raw_key=False, cipher='aes-256-cbc', kdf_iter=4000, cipher_page_size=1024): @@ -343,6 +351,10 @@ class SQLCipherDatabase(sqlite_backend.SQLitePartialExpandDatabase): """ Synchronize documents with remote replica exposed at url. + There can be at most one instance syncing the same database replica at + the same time, so this method will block until the syncing lock can be + acquired. + :param url: The url of the target replica to sync with. :type url: str :param creds: optional dictionary giving credentials. @@ -355,6 +367,8 @@ class SQLCipherDatabase(sqlite_backend.SQLitePartialExpandDatabase): :rtype: int """ res = None + # the following context manager blocks until the syncing lock can be + # acquired. with self.syncer(url, creds=creds) as syncer: res = syncer.sync(autocreate=autocreate) return res @@ -371,10 +385,16 @@ class SQLCipherDatabase(sqlite_backend.SQLitePartialExpandDatabase): def syncer(self, url, creds=None): """ Accesor for synchronizer. + + As we reuse the same synchronizer for every sync, there can be only + one instance synchronizing the same database replica at the same time. + Because of that, this method blocks until the syncing lock can be + acquired. """ - syncer = self._get_syncer(url, creds=creds) - yield syncer - syncer.sync_target.close() + with SQLCipherDatabase.syncing_lock[self._get_replica_uid()]: + syncer = self._get_syncer(url, creds=creds) + yield syncer + syncer.sync_target.close() def _get_syncer(self, url, creds=None): """ |