Separate soledad interfaces

* Separate local storage, syncers and shared_db
* Comment out unused need_sync method
* Use twisted LoopingCall
* Create a threadpool for syncs
* Return deferred from sync method
* Do not pass crypto to SQLCipherDatabase
* Pass replica_uid to u1db_syncer
* Rename / reorganize some initialization methods

9 files changed, 755 insertions, 655 deletions

diff --git a/client/src/leap/soledad/client/adbapi.py b/client/src/leap/soledad/client/adbapi.py
index 3b15509b..60d9e195 100644
--- a/client/src/leap/soledad/client/adbapi.py
+++ b/client/src/leap/soledad/client/adbapi.py
@@ -30,7 +30,7 @@ from u1db.backends import sqlite_backend
 from twisted.enterprise import adbapi
 from twisted.python import log
 
-from leap.soledad.client.sqlcipher import set_init_pragmas
+from leap.soledad.client import sqlcipher as soledad_sqlcipher
 
 
 DEBUG_SQL = os.environ.get("LEAP_DEBUG_SQL")
@@ -40,18 +40,15 @@ if DEBUG_SQL:
 
 def getConnectionPool(opts, openfun=None, driver="pysqlcipher"):
     if openfun is None and driver == "pysqlcipher":
-        openfun = partial(set_init_pragmas, opts=opts)
+        openfun = partial(soledad_sqlcipher.set_init_pragmas, opts=opts)
     return U1DBConnectionPool(
         "%s.dbapi2" % driver, database=opts.path,
         check_same_thread=False, cp_openfun=openfun)
 
 
-# XXX work in progress --------------------------------------------
-
-
-class U1DBSqliteWrapper(sqlite_backend.SQLitePartialExpandDatabase):
+class U1DBSQLiteBackend(sqlite_backend.SQLitePartialExpandDatabase):
     """
-    A very simple wrapper around sqlcipher backend.
+    A very simple wrapper for u1db around sqlcipher backend.
 
     Instead of initializing the database on the fly, it just uses an existing
     connection that is passed to it in the initializer.
@@ -64,9 +61,24 @@ class U1DBSqliteWrapper(sqlite_backend.SQLitePartialExpandDatabase):
         self._factory = u1db.Document
 
 
+class SoledadSQLCipherWrapper(soledad_sqlcipher.SQLCipherDatabase):
+    """
+    A wrapper for u1db that uses the Soledad-extended sqlcipher backend.
+
+    Instead of initializing the database on the fly, it just uses an existing
+    connection that is passed to it in the initializer.
+    """
+    def __init__(self, conn):
+        self._db_handle = conn
+        self._real_replica_uid = None
+        self._ensure_schema()
+        self.set_document_factory(soledad_sqlcipher.soledad_doc_factory)
+        self._prime_replica_uid()
+
+
 class U1DBConnection(adbapi.Connection):
 
-    u1db_wrapper = U1DBSqliteWrapper
+    u1db_wrapper = SoledadSQLCipherWrapper
 
     def __init__(self, pool, init_u1db=False):
         self.init_u1db = init_u1db
diff --git a/client/src/leap/soledad/client/api.py b/client/src/leap/soledad/client/api.py
index 703b9516..493f6c1d 100644
--- a/client/src/leap/soledad/client/api.py
+++ b/client/src/leap/soledad/client/api.py
@@ -41,6 +41,9 @@ except ImportError:
 
 from u1db.remote import http_client
 from u1db.remote.ssl_match_hostname import match_hostname
+from zope.interface import implements
+
+from twisted.python import log
 
 from leap.common.config import get_path_prefix
 from leap.soledad.common import SHARED_DB_NAME
@@ -49,11 +52,11 @@ from leap.soledad.common import soledad_assert_type
 
 from leap.soledad.client import adbapi
 from leap.soledad.client import events as soledad_events
+from leap.soledad.client import interfaces as soledad_interfaces
 from leap.soledad.client.crypto import SoledadCrypto
 from leap.soledad.client.secrets import SoledadSecrets
 from leap.soledad.client.shared_db import SoledadSharedDatabase
-from leap.soledad.client.target import SoledadSyncTarget
-from leap.soledad.client.sqlcipher import SQLCipherOptions
+from leap.soledad.client.sqlcipher import SQLCipherOptions, SQLCipherU1DBSync
 
 logger = logging.getLogger(name=__name__)
 
@@ -61,17 +64,13 @@ logger = logging.getLogger(name=__name__)
 # Constants
 #
 
-SOLEDAD_CERT = None
 """
 Path to the certificate file used to certify the SSL connection between
 Soledad client and server.
 """
+SOLEDAD_CERT = None
 
 
-#
-# Soledad: local encrypted storage and remote encrypted sync.
-#
-
 class Soledad(object):
     """
     Soledad provides encrypted data storage and sync.
@@ -104,65 +103,57 @@ class Soledad(object):
         SOLEDAD_DONE_DATA_SYNC: emitted inside C{sync()} method when it has
             finished synchronizing with remote replica.
     """
+    implements(soledad_interfaces.ILocalStorage,
+               soledad_interfaces.ISyncableStorage,
+               soledad_interfaces.ISharedSecretsStorage)
 
-    LOCAL_DATABASE_FILE_NAME = 'soledad.u1db'
-    """
-    The name of the local SQLCipher U1DB database file.
-    """
-
-    STORAGE_SECRETS_FILE_NAME = "soledad.json"
-    """
-    The name of the file where the storage secrets will be stored.
-    """
-
-    DEFAULT_PREFIX = os.path.join(get_path_prefix(), 'leap', 'soledad')
-    """
-    Prefix for default values for path.
-    """
+    local_db_file_name = 'soledad.u1db'
+    secrets_file_name = "soledad.json"
+    default_prefix = os.path.join(get_path_prefix(), 'leap', 'soledad')
 
     def __init__(self, uuid, passphrase, secrets_path, local_db_path,
                  server_url, cert_file,
-                 auth_token=None, secret_id=None, defer_encryption=False):
+                 auth_token=None, defer_encryption=False):
         """
         Initialize configuration, cryptographic keys and dbs.
 
         :param uuid: User's uuid.
         :type uuid: str
 
-        :param passphrase: The passphrase for locking and unlocking encryption
-                           secrets for local and remote storage.
+        :param passphrase:
+            The passphrase for locking and unlocking encryption secrets for
+            local and remote storage.
         :type passphrase: unicode
 
-        :param secrets_path: Path for storing encrypted key used for
-                             symmetric encryption.
+        :param secrets_path:
+            Path for storing encrypted key used for symmetric encryption.
         :type secrets_path: str
 
         :param local_db_path: Path for local encrypted storage db.
         :type local_db_path: str
 
-        :param server_url: URL for Soledad server. This is used either to sync
-                           with the user's remote db and to interact with the
-                           shared recovery database.
+        :param server_url:
+            URL for Soledad server. This is used either to sync with the user's
+            remote db and to interact with the shared recovery database.
         :type server_url: str
 
-        :param cert_file: Path to the certificate of the ca used
-                          to validate the SSL certificate used by the remote
-                          soledad server.
+        :param cert_file:
+            Path to the certificate of the ca used to validate the SSL
+            certificate used by the remote soledad server.
         :type cert_file: str
 
-        :param auth_token: Authorization token for accessing remote databases.
+        :param auth_token:
+            Authorization token for accessing remote databases.
         :type auth_token: str
 
-        :param secret_id: The id of the storage secret to be used.
-        :type secret_id: str
-
-        :param defer_encryption: Whether to defer encryption/decryption of
-                                 documents, or do it inline while syncing.
+        :param defer_encryption:
+            Whether to defer encryption/decryption of documents, or do it
+            inline while syncing.
         :type defer_encryption: bool
 
-        :raise BootstrapSequenceError: Raised when the secret generation and
-                                       storage on server sequence has failed
-                                       for some reason.
+        :raise BootstrapSequenceError:
+            Raised when the secret generation and storage on server sequence
+            has failed for some reason.
         """
         # store config params
         self._uuid = uuid
@@ -170,30 +161,34 @@ class Soledad(object):
         self._secrets_path = secrets_path
         self._local_db_path = local_db_path
         self._server_url = server_url
+        self._defer_encryption = defer_encryption
+
+        self.shared_db = None
+
         # configure SSL certificate
         global SOLEDAD_CERT
         SOLEDAD_CERT = cert_file
-        self._set_token(auth_token)
-        self._defer_encryption = defer_encryption
-
-        self._init_config()
-        self._init_dirs()
 
         # init crypto variables
-        self._shared_db_instance = None
+        self._set_token(auth_token)
         self._crypto = SoledadCrypto(self)
-        self._secrets = SoledadSecrets(
-            self._uuid,
-            self._passphrase,
-            self._secrets_path,
-            self._shared_db,
-            self._crypto,
-            secret_id=secret_id)
 
-        # initiate bootstrap sequence
-        self._bootstrap()  # might raise BootstrapSequenceError()
+        self._init_config_with_defaults()
+        self._init_working_dirs()
+
+        # Initialize shared recovery database
+        self.init_shared_db(server_url, uuid, self._creds)
 
-    def _init_config(self):
+        # The following can raise BootstrapSequenceError, that will be
+        # propagated upwards.
+        self._init_secrets()
+        self._init_u1db_sqlcipher_backend()
+        self._init_u1db_syncer()
+
+    #
+    # initialization/destruction methods
+    #
+    def _init_config_with_defaults(self):
         """
         Initialize configuration using default values for missing params.
         """
@@ -202,55 +197,37 @@ class Soledad(object):
 
         # initialize secrets_path
         initialize(self._secrets_path, os.path.join(
-            self.DEFAULT_PREFIX, self.STORAGE_SECRETS_FILE_NAME))
-
+            self.default_prefix, self.secrets_file_name))
         # initialize local_db_path
         initialize(self._local_db_path, os.path.join(
-            self.DEFAULT_PREFIX, self.LOCAL_DATABASE_FILE_NAME))
-
+            self.default_prefix, self.local_db_file_name))
         # initialize server_url
         soledad_assert(self._server_url is not None,
                        'Missing URL for Soledad server.')
 
-    #
-    # initialization/destruction methods
-    #
-
-    def _bootstrap(self):
-        """
-        Bootstrap local Soledad instance.
-
-        :raise BootstrapSequenceError:
-            Raised when the secret generation and storage on server sequence
-            has failed for some reason.
-        """
-        self._secrets.bootstrap()
-        self._init_db()
-        # XXX initialize syncers?
-
-    def _init_dirs(self):
+    def _init_working_dirs(self):
         """
         Create work directories.
 
         :raise OSError: in case file exists and is not a dir.
         """
-        paths = map(
-            lambda x: os.path.dirname(x),
-            [self._local_db_path, self._secrets_path])
+        paths = map(lambda x: os.path.dirname(x), [
+            self._local_db_path, self._secrets_path])
         for path in paths:
-            try:
-                if not os.path.isdir(path):
-                    logger.info('Creating directory: %s.' % path)
-                os.makedirs(path)
-            except OSError as exc:
-                if exc.errno == errno.EEXIST and os.path.isdir(path):
-                    pass
-                else:
-                    raise
-
-    def _init_db(self):
+            create_path_if_not_exists(path)
+
+    def _init_secrets(self):
+        self._secrets = SoledadSecrets(
+            self.uuid, self.passphrase, self.secrets_path,
+            self._shared_db, self._crypto)
+        self._secrets.bootstrap()
+
+    def _init_u1db_sqlcipher_backend(self):
         """
-        Initialize the U1DB SQLCipher database for local storage.
+        Initialize the U1DB SQLCipher database for local storage, by
+        instantiating a modified twisted adbapi that will maintain a threadpool
+        with a u1db-sqclipher connection for each thread, and will return
+        deferreds for each u1db query.
 
         Currently, Soledad uses the default SQLCipher cipher, i.e.
         'aes-256-cbc'. We use scrypt to derive a 256-bit encryption key,
@@ -268,8 +245,17 @@ class Soledad(object):
             defer_encryption=self._defer_encryption,
             sync_db_key=sync_db_key,
         )
+        self._soledad_opts = opts
         self._dbpool = adbapi.getConnectionPool(opts)
 
+    def _init_u1db_syncer(self):
+        self._dbsyncer = SQLCipherU1DBSync(
+            self._soledad_opts, self._crypto, self._defer_encryption)
+
+    #
+    # Closing methods
+    #
+
     def close(self):
         """
         Close underlying U1DB database.
@@ -279,401 +265,164 @@ class Soledad(object):
 
         # TODO close syncers >>>>>>
 
-        #if hasattr(self, '_db') and isinstance(
-                #self._db,
-                #SQLCipherDatabase):
-            #self._db.close()
-#
-            # XXX stop syncers
-            # self._db.stop_sync()
-
-    @property
-    def _shared_db(self):
-        """
-        Return an instance of the shared recovery database object.
-
-        :return: The shared database.
-        :rtype: SoledadSharedDatabase
-        """
-        if self._shared_db_instance is None:
-            self._shared_db_instance = SoledadSharedDatabase.open_database(
-                urlparse.urljoin(self.server_url, SHARED_DB_NAME),
-                self._uuid,
-                False,  # db should exist at this point.
-                creds=self._creds)
-        return self._shared_db_instance
-
     #
-    # Document storage, retrieval and sync.
+    # ILocalStorage
     #
 
     def put_doc(self, doc):
-        # TODO what happens with this warning during the deferred life cycle?
-        # Isn't it better to defend ourselves from the mutability, to avoid
-        # nasty surprises?
         """
-        Update a document in the local encrypted database.
-
         ============================== WARNING ==============================
         This method converts the document's contents to unicode in-place. This
         means that after calling `put_doc(doc)`, the contents of the
         document, i.e. `doc.content`, might be different from before the
         call.
         ============================== WARNING ==============================
-
-        :param doc: the document to update
-        :type doc: SoledadDocument
-
-        :return:
-            a deferred that will fire with the new revision identifier for
-            the document
-        :rtype: Deferred
         """
+        # TODO what happens with this warning during the deferred life cycle?
+        # Isn't it better to defend ourselves from the mutability, to avoid
+        # nasty surprises?
         doc.content = self._convert_to_unicode(doc.content)
         return self._dbpool.put_doc(doc)
 
     def delete_doc(self, doc):
-        """
-        Delete a document from the local encrypted database.
-
-        :param doc: the document to delete
-        :type doc: SoledadDocument
-
-        :return:
-            a deferred that will fire with ...
-        :rtype: Deferred
-        """
         # XXX what does this do when fired???
         return self._dbpool.delete_doc(doc)
 
     def get_doc(self, doc_id, include_deleted=False):
-        """
-        Retrieve a document from the local encrypted database.
-
-        :param doc_id: the unique document identifier
-        :type doc_id: str
-        :param include_deleted:
-            if True, deleted documents will be returned with empty content;
-            otherwise asking for a deleted document will return None
-        :type include_deleted: bool
-
-        :return:
-            A deferred that will fire with the document object, containing a
-            SoledadDocument, or None if it could not be found
-        :rtype: Deferred
-        """
         return self._dbpool.get_doc(doc_id, include_deleted=include_deleted)
 
     def get_docs(self, doc_ids, check_for_conflicts=True,
                  include_deleted=False):
-        """
-        Get the content for many documents.
-
-        :param doc_ids: a list of document identifiers
-        :type doc_ids: list
-        :param check_for_conflicts: if set False, then the conflict check will
-            be skipped, and 'None' will be returned instead of True/False
-        :type check_for_conflicts: bool
-
-        :return:
-            A deferred that will fire with an iterable giving the Document
-            object for each document id in matching doc_ids order.
-        :rtype: Deferred
-        """
-        return self._dbpool.get_docs(
-            doc_ids, check_for_conflicts=check_for_conflicts,
-            include_deleted=include_deleted)
+        return self._dbpool.get_docs(doc_ids,
+                                     check_for_conflicts=check_for_conflicts,
+                                     include_deleted=include_deleted)
 
     def get_all_docs(self, include_deleted=False):
-        """
-        Get the JSON content for all documents in the database.
-
-        :param include_deleted: If set to True, deleted documents will be
-                                returned with empty content. Otherwise deleted
-                                documents will not be included in the results.
-        :return:
-            A deferred that will fire with (generation, [Document]): that is,
-            the current generation of the database, followed by a list of all
-            the documents in the database.
-        :rtype: Deferred
-        """
         return self._dbpool.get_all_docs(include_deleted)
 
     def create_doc(self, content, doc_id=None):
-        """
-        Create a new document in the local encrypted database.
-
-        :param content: the contents of the new document
-        :type content: dict
-        :param doc_id: an optional identifier specifying the document id
-        :type doc_id: str
-
-        :return:
-            A deferred tht will fire with the new document (SoledadDocument
-            instance).
-        :rtype: Deferred
-        """
         return self._dbpool.create_doc(
             _convert_to_unicode(content), doc_id=doc_id)
 
     def create_doc_from_json(self, json, doc_id=None):
-        """
-        Create a new document.
-
-        You can optionally specify the document identifier, but the document
-        must not already exist. See 'put_doc' if you want to override an
-        existing document.
-        If the database specifies a maximum document size and the document
-        exceeds it, create will fail and raise a DocumentTooBig exception.
-
-        :param json: The JSON document string
-        :type json: str
-        :param doc_id: An optional identifier specifying the document id.
-        :type doc_id:
-        :return:
-            A deferred that will fire with the new document (A SoledadDocument
-            instance)
-        :rtype: Deferred
-        """
         return self._dbpool.create_doc_from_json(json, doc_id=doc_id)
 
     def create_index(self, index_name, *index_expressions):
-        """
-        Create an named index, which can then be queried for future lookups.
-        Creating an index which already exists is not an error, and is cheap.
-        Creating an index which does not match the index_expressions of the
-        existing index is an error.
-        Creating an index will block until the expressions have been evaluated
-        and the index generated.
-
-        :param index_name: A unique name which can be used as a key prefix
-        :type index_name: str
-        :param index_expressions:
-            index expressions defining the index information.
-        :type index_expressions: dict
-
-            Examples:
-
-            "fieldname", or "fieldname.subfieldname" to index alphabetically
-            sorted on the contents of a field.
-
-            "number(fieldname, width)", "lower(fieldname)"
-        """
         return self._dbpool.create_index(index_name, *index_expressions)
 
     def delete_index(self, index_name):
-        """
-        Remove a named index.
-
-        :param index_name: The name of the index we are removing
-        :type index_name: str
-        """
         return self._dbpool.delete_index(index_name)
 
     def list_indexes(self):
-        """
-        List the definitions of all known indexes.
-
-        :return: A list of [('index-name', ['field', 'field2'])] definitions.
-        :rtype: list
-        """
         return self._dbpool.list_indexes()
 
     def get_from_index(self, index_name, *key_values):
-        """
-        Return documents that match the keys supplied.
-
-        You must supply exactly the same number of values as have been defined
-        in the index. It is possible to do a prefix match by using '*' to
-        indicate a wildcard match. You can only supply '*' to trailing entries,
-        (eg 'val', '*', '*' is allowed, but '*', 'val', 'val' is not.)
-        It is also possible to append a '*' to the last supplied value (eg
-        'val*', '*', '*' or 'val', 'val*', '*', but not 'val*', 'val', '*')
-
-        :param index_name: The index to query
-        :type index_name: str
-        :param key_values: values to match. eg, if you have
-                           an index with 3 fields then you would have:
-                           get_from_index(index_name, val1, val2, val3)
-        :type key_values: tuple
-        :return: List of [Document]
-        :rtype: list
-        """
         return self._dbpool.get_from_index(index_name, *key_values)
 
     def get_count_from_index(self, index_name, *key_values):
-        """
-        Return the count of the documents that match the keys and
-        values supplied.
-
-        :param index_name: The index to query
-        :type index_name: str
-        :param key_values: values to match. eg, if you have
-                           an index with 3 fields then you would have:
-                           get_from_index(index_name, val1, val2, val3)
-        :type key_values: tuple
-        :return: count.
-        :rtype: int
-        """
         return self._dbpool.get_count_from_index(index_name, *key_values)
 
     def get_range_from_index(self, index_name, start_value, end_value):
-        """
-        Return documents that fall within the specified range.
-
-        Both ends of the range are inclusive. For both start_value and
-        end_value, one must supply exactly the same number of values as have
-        been defined in the index, or pass None. In case of a single column
-        index, a string is accepted as an alternative for a tuple with a single
-        value. It is possible to do a prefix match by using '*' to indicate
-        a wildcard match. You can only supply '*' to trailing entries, (eg
-        'val', '*', '*' is allowed, but '*', 'val', 'val' is not.) It is also
-        possible to append a '*' to the last supplied value (eg 'val*', '*',
-        '*' or 'val', 'val*', '*', but not 'val*', 'val', '*')
-
-        :param index_name: The index to query
-        :type index_name: str
-        :param start_values: tuples of values that define the lower bound of
-            the range. eg, if you have an index with 3 fields then you would
-            have: (val1, val2, val3)
-        :type start_values: tuple
-        :param end_values: tuples of values that define the upper bound of the
-            range. eg, if you have an index with 3 fields then you would have:
-            (val1, val2, val3)
-        :type end_values: tuple
-        :return: A deferred that will fire with a list of [Document]
-        :rtype: Deferred
-        """
         return self._dbpool.get_range_from_index(
             index_name, start_value, end_value)
 
     def get_index_keys(self, index_name):
-        """
-        Return all keys under which documents are indexed in this index.
-
-        :param index_name: The index to query
-        :type index_name: str
-        :return:
-            A deferred that will fire with a list of tuples of indexed keys.
-        :rtype: Deferred
-        """
         return self._dbpool.get_index_keys(index_name)
 
     def get_doc_conflicts(self, doc_id):
-        """
-        Get the list of conflicts for the given document.
-
-        :param doc_id: the document id
-        :type doc_id: str
-
-        :return:
-            A deferred that will fire with a list of the document entries that
-            are conflicted.
-        :rtype: Deferred
-        """
         return self._dbpool.get_doc_conflicts(doc_id)
 
     def resolve_doc(self, doc, conflicted_doc_revs):
-        """
-        Mark a document as no longer conflicted.
-
-        :param doc: a document with the new content to be inserted.
-        :type doc: SoledadDocument
-        :param conflicted_doc_revs:
-            A deferred that will fire with a list of revisions that the new
-            content supersedes.
-        :type conflicted_doc_revs: list
-        """
         return self._dbpool.resolve_doc(doc, conflicted_doc_revs)
 
+    def _get_local_db_path(self):
+        return self._local_db_path
+
+    # XXX Do we really need all this private / property dance?
+
+    local_db_path = property(
+        _get_local_db_path,
+        doc='The path for the local database replica.')
+
+    def _get_uuid(self):
+        return self._uuid
+
+    uuid = property(_get_uuid, doc='The user uuid.')
+
     #
-    # Sync API
+    # ISyncableStorage
     #
 
-    # TODO have interfaces, and let it implement it.
-
     def sync(self, defer_decryption=True):
-        """
-        Synchronize the local encrypted replica with a remote replica.
 
-        This method blocks until a syncing lock is acquired, so there are no
-        attempts of concurrent syncs from the same client replica.
+        # -----------------------------------------------------------------
+        # TODO this needs work.
+        # Should review/write tests to check that this:
 
-        :param url: the url of the target replica to sync with
-        :type url: str
+        # (1) Defer to the syncer pool -- DONE (on dbsyncer)
+        # (2) Return the deferred
+        # (3) Add the callback for signaling the event (executed on reactor
+        #     thread)
+        # (4) Check that the deferred is called with the local gen.
 
-        :param defer_decryption:
-            Whether to defer the decryption process using the intermediate
-            database. If False, decryption will be done inline.
-        :type defer_decryption: bool
+        # TODO document that this returns a deferred
+        # -----------------------------------------------------------------
 
-        :return:
-            A deferred that will fire with the local generation before the
-            synchronisation was performed.
-        :rtype: str
-        """
-        # TODO this needs work.
-        # Should:
-        # (1) Defer to the syncer pool
-        # (2) Return a deferred (the deferToThreadpool can be good)
-        # (3) Add the callback for signaling the event
-        # (4) Let the local gen be returned from the thread
+        def on_sync_done(local_gen):
+            soledad_events.signal(
+                soledad_events.SOLEDAD_DONE_DATA_SYNC, self.uuid)
+            return local_gen
+
+        sync_url = urlparse.urljoin(self.server_url, 'user-%s' % self.uuid)
         try:
-            local_gen = self._dbsyncer.sync(
-                urlparse.urljoin(self.server_url, 'user-%s' % self._uuid),
+            d = self._dbsyncer.sync(
+                sync_url,
                 creds=self._creds, autocreate=False,
                 defer_decryption=defer_decryption)
-            soledad_events.signal(
-                soledad_events.SOLEDAD_DONE_DATA_SYNC, self._uuid)
-            return local_gen
+
+            d.addCallbacks(on_sync_done, lambda err: log.err(err))
+            return d
+
+        # TODO catch the exception by adding an Errback
         except Exception as e:
             logger.error("Soledad exception when syncing: %s" % str(e))
 
     def stop_sync(self):
-        """
-        Stop the current syncing process.
-        """
         self._dbsyncer.stop_sync()
 
-    def need_sync(self, url):
-        """
-        Return if local db replica differs from remote url's replica.
-
-        :param url: The remote replica to compare with local replica.
-        :type url: str
-
-        :return: Whether remote replica and local replica differ.
-        :rtype: bool
-        """
-        # XXX pass the get_replica_uid ------------------------
-        # From where? initialize with that?
-        replica_uid = self._db._get_replica_uid()
-        target = SoledadSyncTarget(
-            url, replica_uid, creds=self._creds, crypto=self._crypto)
-
-        generation = self._db._get_generation()
+    # FIXME -------------------------------------------------------
+    # review if we really need this. I think that we can the sync
+    # fail silently if nothing is to be synced.
+    #def need_sync(self, url):
+        # XXX dispatch this method in the dbpool .................
+        #replica_uid = self._dbpool.replica_uid
+        #target = SoledadSyncTarget(
+            #url, replica_uid, creds=self._creds, crypto=self._crypto)
+#
+        # XXX does it matter if we get this from the general dbpool or the
+        # syncer pool?
+        #generation = self._dbpool.get_generation()
+#
         # XXX better unpack it?
-        info = target.get_sync_info(replica_uid)
-
+        #info = target.get_sync_info(replica_uid)
+#
         # compare source generation with target's last known source generation
-        if generation != info[4]:
-            soledad_events.signal(
-                soledad_events.SOLEDAD_NEW_DATA_TO_SYNC, self._uuid)
-            return True
-        return False
+        #if generation != info[4]:
+            #soledad_events.signal(
+                #soledad_events.SOLEDAD_NEW_DATA_TO_SYNC, self.uuid)
+            #return True
+        #return False
 
     @property
     def syncing(self):
-        """
-        Property, True if the syncer is syncing.
-        """
         return self._dbsyncer.syncing
 
     def _set_token(self, token):
         """
         Set the authentication token for remote database access.
 
-        Build the credentials dictionary with the following format:
+        Internally, this builds the credentials dictionary with the following
+        format:
 
             self._{
                 'token': {
@@ -686,7 +435,7 @@ class Soledad(object):
         """
         self._creds = {
             'token': {
-                'uuid': self._uuid,
+                'uuid': self.uuid,
                 'token': token,
             }
         }
@@ -699,25 +448,24 @@ class Soledad(object):
 
     token = property(_get_token, _set_token, doc='The authentication Token.')
 
-    #
-    # Setters/getters
-    #
-
-    def _get_uuid(self):
-        return self._uuid
-
-    uuid = property(_get_uuid, doc='The user uuid.')
+    def _get_server_url(self):
+        return self._server_url
 
-    def get_secret_id(self):
-        return self._secrets.secret_id
+    server_url = property(
+        _get_server_url,
+        doc='The URL of the Soledad server.')
 
-    def set_secret_id(self, secret_id):
-        self._secrets.set_secret_id(secret_id)
+    #
+    # ISharedSecretsStorage
+    #
 
-    secret_id = property(
-        get_secret_id,
-        set_secret_id,
-        doc='The active secret id.')
+    def init_shared_db(self, server_url, uuid, creds):
+        shared_db_url = urlparse.urljoin(server_url, SHARED_DB_NAME)
+        self.shared_db = SoledadSharedDatabase.open_database(
+            shared_db_url,
+            uuid,
+            creds=creds,
+            create=False)  # db should exist at this point.
 
     def _set_secrets_path(self, secrets_path):
         self._secrets.secrets_path = secrets_path
@@ -730,20 +478,6 @@ class Soledad(object):
         _set_secrets_path,
         doc='The path for the file containing the encrypted symmetric secret.')
 
-    def _get_local_db_path(self):
-        return self._local_db_path
-
-    local_db_path = property(
-        _get_local_db_path,
-        doc='The path for the local database replica.')
-
-    def _get_server_url(self):
-        return self._server_url
-
-    server_url = property(
-        _get_server_url,
-        doc='The URL of the Soledad server.')
-
     @property
     def storage_secret(self):
         """
@@ -762,19 +496,7 @@ class Soledad(object):
     def secrets(self):
         return self._secrets
 
-    @property
-    def passphrase(self):
-        return self._secrets.passphrase
-
     def change_passphrase(self, new_passphrase):
-        """
-        Change the passphrase that encrypts the storage secret.
-
-        :param new_passphrase: The new passphrase.
-        :type new_passphrase: unicode
-
-        :raise NoStorageSecret: Raised if there's no storage secret available.
-        """
         self._secrets.change_passphrase(new_passphrase)
 
 
@@ -811,6 +533,17 @@ def _convert_to_unicode(content):
     return content
 
 
+def create_path_if_not_exists(path):
+    try:
+        if not os.path.isdir(path):
+            logger.info('Creating directory: %s.' % path)
+        os.makedirs(path)
+    except OSError as exc:
+        if exc.errno == errno.EEXIST and os.path.isdir(path):
+            pass
+        else:
+            raise
+
 # ----------------------------------------------------------------------------
 # Monkey patching u1db to be able to provide a custom SSL cert
 # ----------------------------------------------------------------------------
diff --git a/client/src/leap/soledad/client/examples/use_api.py b/client/src/leap/soledad/client/examples/use_api.py
index fd0a100c..4268fe71 100644
--- a/client/src/leap/soledad/client/examples/use_api.py
+++ b/client/src/leap/soledad/client/examples/use_api.py
@@ -46,7 +46,7 @@ if os.path.isfile(tmpdb):
 start_time = datetime.datetime.now()
 
 opts = SQLCipherOptions(tmpdb, "secret", create=True)
-db = sqlcipher.SQLCipherDatabase(None, opts)
+db = sqlcipher.SQLCipherDatabase(opts)
 
 
 def allDone():
diff --git a/client/src/leap/soledad/client/interfaces.py b/client/src/leap/soledad/client/interfaces.py
new file mode 100644
index 00000000..6bd3f200
--- /dev/null
+++ b/client/src/leap/soledad/client/interfaces.py
@@ -0,0 +1,361 @@
+# -*- coding: utf-8 -*-
+# interfaces.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/>.
+"""
+Interfaces used by the Soledad Client.
+"""
+from zope.interface import Interface, Attribute
+
+
+class ILocalStorage(Interface):
+    """
+    I implement core methods for the u1db local storage.
+    """
+    local_db_path = Attribute(
+        "The path for the local database replica")
+    local_db_file_name = Attribute(
+        "The name of the local SQLCipher U1DB database file")
+    uuid = Attribute("The user uuid")
+    default_prefix = Attribute(
+        "Prefix for default values for path")
+
+    def put_doc(self, doc):
+        """
+        Update a document in the local encrypted database.
+
+        :param doc: the document to update
+        :type doc: SoledadDocument
+
+        :return:
+            a deferred that will fire with the new revision identifier for
+            the document
+        :rtype: Deferred
+        """
+
+    def delete_doc(self, doc):
+        """
+        Delete a document from the local encrypted database.
+
+        :param doc: the document to delete
+        :type doc: SoledadDocument
+
+        :return:
+            a deferred that will fire with ...
+        :rtype: Deferred
+        """
+
+    def get_doc(self, doc_id, include_deleted=False):
+        """
+        Retrieve a document from the local encrypted database.
+
+        :param doc_id: the unique document identifier
+        :type doc_id: str
+        :param include_deleted:
+            if True, deleted documents will be returned with empty content;
+            otherwise asking for a deleted document will return None
+        :type include_deleted: bool
+
+        :return:
+            A deferred that will fire with the document object, containing a
+            SoledadDocument, or None if it could not be found
+        :rtype: Deferred
+        """
+
+    def get_docs(self, doc_ids, check_for_conflicts=True,
+                 include_deleted=False):
+        """
+        Get the content for many documents.
+
+        :param doc_ids: a list of document identifiers
+        :type doc_ids: list
+        :param check_for_conflicts: if set False, then the conflict check will
+            be skipped, and 'None' will be returned instead of True/False
+        :type check_for_conflicts: bool
+
+        :return:
+            A deferred that will fire with an iterable giving the Document
+            object for each document id in matching doc_ids order.
+        :rtype: Deferred
+        """
+
+    def get_all_docs(self, include_deleted=False):
+        """
+        Get the JSON content for all documents in the database.
+
+        :param include_deleted: If set to True, deleted documents will be
+                                returned with empty content. Otherwise deleted
+                                documents will not be included in the results.
+        :return:
+            A deferred that will fire with (generation, [Document]): that is,
+            the current generation of the database, followed by a list of all
+            the documents in the database.
+        :rtype: Deferred
+        """
+
+    def create_doc(self, content, doc_id=None):
+        """
+        Create a new document in the local encrypted database.
+
+        :param content: the contents of the new document
+        :type content: dict
+        :param doc_id: an optional identifier specifying the document id
+        :type doc_id: str
+
+        :return:
+            A deferred tht will fire with the new document (SoledadDocument
+            instance).
+        :rtype: Deferred
+        """
+
+    def create_doc_from_json(self, json, doc_id=None):
+        """
+        Create a new document.
+
+        You can optionally specify the document identifier, but the document
+        must not already exist. See 'put_doc' if you want to override an
+        existing document.
+        If the database specifies a maximum document size and the document
+        exceeds it, create will fail and raise a DocumentTooBig exception.
+
+        :param json: The JSON document string
+        :type json: str
+        :param doc_id: An optional identifier specifying the document id.
+        :type doc_id:
+        :return:
+            A deferred that will fire with the new document (A SoledadDocument
+            instance)
+        :rtype: Deferred
+        """
+
+    def create_index(self, index_name, *index_expressions):
+        """
+        Create an named index, which can then be queried for future lookups.
+        Creating an index which already exists is not an error, and is cheap.
+        Creating an index which does not match the index_expressions of the
+        existing index is an error.
+        Creating an index will block until the expressions have been evaluated
+        and the index generated.
+
+        :param index_name: A unique name which can be used as a key prefix
+        :type index_name: str
+        :param index_expressions:
+            index expressions defining the index information.
+        :type index_expressions: dict
+
+            Examples:
+
+            "fieldname", or "fieldname.subfieldname" to index alphabetically
+            sorted on the contents of a field.
+
+            "number(fieldname, width)", "lower(fieldname)"
+        """
+
+    def delete_index(self, index_name):
+        """
+        Remove a named index.
+
+        :param index_name: The name of the index we are removing
+        :type index_name: str
+        """
+
+    def list_indexes(self):
+        """
+        List the definitions of all known indexes.
+
+        :return: A list of [('index-name', ['field', 'field2'])] definitions.
+        :rtype: Deferred
+        """
+
+    def get_from_index(self, index_name, *key_values):
+        """
+        Return documents that match the keys supplied.
+
+        You must supply exactly the same number of values as have been defined
+        in the index. It is possible to do a prefix match by using '*' to
+        indicate a wildcard match. You can only supply '*' to trailing entries,
+        (eg 'val', '*', '*' is allowed, but '*', 'val', 'val' is not.)
+        It is also possible to append a '*' to the last supplied value (eg
+        'val*', '*', '*' or 'val', 'val*', '*', but not 'val*', 'val', '*')
+
+        :param index_name: The index to query
+        :type index_name: str
+        :param key_values: values to match. eg, if you have
+                           an index with 3 fields then you would have:
+                           get_from_index(index_name, val1, val2, val3)
+        :type key_values: tuple
+        :return: List of [Document]
+        :rtype: list
+        """
+
+    def get_count_from_index(self, index_name, *key_values):
+        """
+        Return the count of the documents that match the keys and
+        values supplied.
+
+        :param index_name: The index to query
+        :type index_name: str
+        :param key_values: values to match. eg, if you have
+                           an index with 3 fields then you would have:
+                           get_from_index(index_name, val1, val2, val3)
+        :type key_values: tuple
+        :return: count.
+        :rtype: int
+        """
+
+    def get_range_from_index(self, index_name, start_value, end_value):
+        """
+        Return documents that fall within the specified range.
+
+        Both ends of the range are inclusive. For both start_value and
+        end_value, one must supply exactly the same number of values as have
+        been defined in the index, or pass None. In case of a single column
+        index, a string is accepted as an alternative for a tuple with a single
+        value. It is possible to do a prefix match by using '*' to indicate
+        a wildcard match. You can only supply '*' to trailing entries, (eg
+        'val', '*', '*' is allowed, but '*', 'val', 'val' is not.) It is also
+        possible to append a '*' to the last supplied value (eg 'val*', '*',
+        '*' or 'val', 'val*', '*', but not 'val*', 'val', '*')
+
+        :param index_name: The index to query
+        :type index_name: str
+        :param start_values: tuples of values that define the lower bound of
+            the range. eg, if you have an index with 3 fields then you would
+            have: (val1, val2, val3)
+        :type start_values: tuple
+        :param end_values: tuples of values that define the upper bound of the
+            range. eg, if you have an index with 3 fields then you would have:
+            (val1, val2, val3)
+        :type end_values: tuple
+        :return: A deferred that will fire with a list of [Document]
+        :rtype: Deferred
+        """
+
+    def get_index_keys(self, index_name):
+        """
+        Return all keys under which documents are indexed in this index.
+
+        :param index_name: The index to query
+        :type index_name: str
+        :return:
+            A deferred that will fire with a list of tuples of indexed keys.
+        :rtype: Deferred
+        """
+
+    def get_doc_conflicts(self, doc_id):
+        """
+        Get the list of conflicts for the given document.
+
+        :param doc_id: the document id
+        :type doc_id: str
+
+        :return:
+            A deferred that will fire with a list of the document entries that
+            are conflicted.
+        :rtype: Deferred
+        """
+
+    def resolve_doc(self, doc, conflicted_doc_revs):
+        """
+        Mark a document as no longer conflicted.
+
+        :param doc: a document with the new content to be inserted.
+        :type doc: SoledadDocument
+        :param conflicted_doc_revs:
+            A deferred that will fire with a list of revisions that the new
+            content supersedes.
+        :type conflicted_doc_revs: list
+        """
+
+
+class ISyncableStorage(Interface):
+    """
+    I implement methods to synchronize with a remote replica.
+    """
+    replica_uid = Attribute("The uid of the local replica")
+    server_url = Attribute("The URL of the Soledad server.")
+    syncing = Attribute(
+        "Property, True if the syncer is syncing.")
+    token = Attribute("The authentication Token.")
+
+    def sync(self, defer_decryption=True):
+        """
+        Synchronize the local encrypted replica with a remote replica.
+
+        This method blocks until a syncing lock is acquired, so there are no
+        attempts of concurrent syncs from the same client replica.
+
+        :param url: the url of the target replica to sync with
+        :type url: str
+
+        :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 that will fire with the local generation before the
+            synchronisation was performed.
+        :rtype: str
+        """
+
+    def stop_sync(self):
+        """
+        Stop the current syncing process.
+        """
+
+
+class ISharedSecretsStorage(Interface):
+    """
+    I implement methods needed for the Shared Recovery Database.
+    """
+    secrets_path = Attribute(
+        "Path for storing encrypted key used for symmetric encryption.")
+    secrets_file_name = Attribute(
+        "The name of the file where the storage secrets will be stored")
+
+    storage_secret = Attribute("")
+    remote_storage_secret = Attribute("")
+    shared_db = Attribute("The shared db object")
+
+    # XXX this used internally from secrets, so it might be good to preserve
+    # as a public boundary with other components.
+    secrets = Attribute("")
+
+    def init_shared_db(self, server_url, uuid, creds):
+        """
+        Initialize the shared recovery database.
+
+        :param server_url:
+        :type server_url:
+        :param uuid:
+        :type uuid:
+        :param creds:
+        :type creds:
+        """
+
+    def change_passphrase(self, new_passphrase):
+        """
+        Change the passphrase that encrypts the storage secret.
+
+        :param new_passphrase: The new passphrase.
+        :type new_passphrase: unicode
+
+        :raise NoStorageSecret: Raised if there's no storage secret available.
+        """
+
+    # XXX not in use. Uncomment if we ever decide to allow
+    # multiple secrets.
+    # secret_id = Attribute("The id of the storage secret to be used")
diff --git a/client/src/leap/soledad/client/pragmas.py b/client/src/leap/soledad/client/pragmas.py
index 7a13a694..2e9c53a3 100644
--- a/client/src/leap/soledad/client/pragmas.py
+++ b/client/src/leap/soledad/client/pragmas.py
@@ -43,7 +43,7 @@ def set_crypto_pragmas(db_handle, sqlcipher_opts):
 
 def _set_key(db_handle, key, is_raw_key):
     """
-    Set the C{key} for use with the database.
+    Set the ``key`` for use with the database.
 
     The process of creating a new, encrypted database is called 'keying'
     the database. SQLCipher uses just-in-time key derivation at the point
@@ -60,9 +60,9 @@ def _set_key(db_handle, key, is_raw_key):
 
     :param key: The key for use with the database.
     :type key: str
-    :param is_raw_key: Whether C{key} is a raw 64-char hex string or a
-                       passphrase that should be hashed to obtain the
-                       encyrption key.
+    :param is_raw_key:
+        Whether C{key} is a raw 64-char hex string or a passphrase that should
+        be hashed to obtain the encyrption key.
     :type is_raw_key: bool
     """
     if is_raw_key:
@@ -321,14 +321,11 @@ def set_write_ahead_logging(db_handle):
     """
     logger.debug("SQLCIPHER: SETTING WRITE-AHEAD LOGGING")
     db_handle.cursor().execute('PRAGMA journal_mode=WAL')
+
     # The optimum value can still use a little bit of tuning, but we favor
     # small sizes of the WAL file to get fast reads, since we assume that
     # the writes will be quick enough to not block too much.
 
-    # TODO
-    # As a further improvement, we might want to set autocheckpoint to 0
-    # here and do the checkpoints manually in a separate thread, to avoid
-    # any blocks in the main thread (we should run a loopingcall from here)
     db_handle.cursor().execute('PRAGMA wal_autocheckpoint=50')
 
 
diff --git a/client/src/leap/soledad/client/secrets.py b/client/src/leap/soledad/client/secrets.py
index 970ac82f..93f8c25d 100644
--- a/client/src/leap/soledad/client/secrets.py
+++ b/client/src/leap/soledad/client/secrets.py
@@ -144,8 +144,7 @@ class SoledadSecrets(object):
     Keys used to access storage secrets in recovery documents.
     """
 
-    def __init__(self, uuid, passphrase, secrets_path, shared_db, crypto,
-                 secret_id=None):
+    def __init__(self, uuid, passphrase, secrets_path, shared_db, crypto):
         """
         Initialize the secrets manager.
 
@@ -161,17 +160,20 @@ class SoledadSecrets(object):
         :type shared_db: leap.soledad.client.shared_db.SoledadSharedDatabase
         :param crypto: A soledad crypto object.
         :type crypto: SoledadCrypto
-        :param secret_id: The id of the storage secret to be used.
-        :type secret_id: str
         """
+        # XXX removed since not in use
+        # We will pick the first secret available.
+        # param secret_id: The id of the storage secret to be used.
+
         self._uuid = uuid
         self._passphrase = passphrase
         self._secrets_path = secrets_path
         self._shared_db = shared_db
         self._crypto = crypto
-        self._secret_id = secret_id
         self._secrets = {}
 
+        self._secret_id = None
+
     def bootstrap(self):
         """
         Bootstrap secrets.
@@ -247,7 +249,8 @@ class SoledadSecrets(object):
             try:
                 self._load_secrets()  # try to load from disk
             except IOError as e:
-                logger.warning('IOError while loading secrets from disk: %s' % str(e))
+                logger.warning(
+                    'IOError while loading secrets from disk: %s' % str(e))
                 return False
         return self.storage_secret is not None
 
diff --git a/client/src/leap/soledad/client/sqlcipher.py b/client/src/leap/soledad/client/sqlcipher.py
index c9e69c73..a7e9e0fe 100644
--- a/client/src/leap/soledad/client/sqlcipher.py
+++ b/client/src/leap/soledad/client/sqlcipher.py
@@ -45,7 +45,6 @@ import logging
 import multiprocessing
 import os
 import threading
-# import time --- needed for the win initialization hack
 import json
 
 from hashlib import sha256
@@ -56,7 +55,10 @@ from httplib import CannotSendRequest
 from pysqlcipher import dbapi2 as sqlcipher_dbapi2
 from u1db.backends import sqlite_backend
 from u1db import errors as u1db_errors
-from taskthread import TimerTask
+
+from twisted.internet.task import LoopingCall
+from twisted.internet.threads import deferToThreadPool
+from twisted.python.threadpool import ThreadPool
 
 from leap.soledad.client import crypto
 from leap.soledad.client.target import SoledadSyncTarget
@@ -64,7 +66,6 @@ from leap.soledad.client.target import PendingReceivedDocsSyncError
 from leap.soledad.client.sync import SoledadSynchronizer
 
 # TODO use adbapi too
-from leap.soledad.client.mp_safe_db_TOREMOVE import MPSafeSQLiteDB
 from leap.soledad.client import pragmas
 from leap.soledad.common import soledad_assert
 from leap.soledad.common.document import SoledadDocument
@@ -75,16 +76,6 @@ logger = logging.getLogger(__name__)
 # Monkey-patch u1db.backends.sqlite_backend with pysqlcipher.dbapi2
 sqlite_backend.dbapi2 = sqlcipher_dbapi2
 
-# It seems that, as long as we are not using old sqlite versions, serialized
-# mode is enabled by default at compile time. So accessing db connections from
-# different threads should be safe, as long as no attempt is made to use them
-# from multiple threads with no locking.
-# See https://sqlite.org/threadsafe.html
-# and http://bugs.python.org/issue16509
-
-# TODO this no longer needed -------------
-#SQLITE_CHECK_SAME_THREAD = False
-
 
 def initialize_sqlcipher_db(opts, on_init=None):
     """
@@ -96,12 +87,17 @@ def initialize_sqlcipher_db(opts, on_init=None):
     :type on_init: tuple
     :return: a SQLCipher connection
     """
-    conn = sqlcipher_dbapi2.connect(
-        opts.path)
+    # Note: There seemed to be a bug in sqlite 3.5.9 (with python2.6)
+    #       where without re-opening the database on Windows, it
+    #       doesn't see the transaction that was just committed
+    # Removing from here now, look at the pysqlite implementation if the
+    # bug shows up in windows.
 
-    # XXX not needed -- check
-    #check_same_thread=SQLITE_CHECK_SAME_THREAD)
+    if not os.path.isfile(opts.path) and not opts.create:
+        raise u1db_errors.DatabaseDoesNotExist()
 
+    conn = sqlcipher_dbapi2.connect(
+        opts.path)
     set_init_pragmas(conn, opts, extra_queries=on_init)
     return conn
 
@@ -196,10 +192,11 @@ class SQLCipherDatabase(sqlite_backend.SQLitePartialExpandDatabase):
     """
     defer_encryption = False
 
-    # XXX not used afaik:
-    # _index_storage_value = 'expand referenced encrypted'
+    # The attribute _index_storage_value will be used as the lookup key.
+    # Here we extend it with `encrypted`
+    _index_storage_value = 'expand referenced encrypted'
 
-    def __init__(self, soledad_crypto, opts):
+    def __init__(self, opts):
         """
         Connect to an existing SQLCipher database, creating a new sqlcipher
         database file if needed.
@@ -217,18 +214,34 @@ class SQLCipherDatabase(sqlite_backend.SQLitePartialExpandDatabase):
         :param opts:
         :type opts: SQLCipherOptions
         """
-        # TODO ------ we don't need any soledad crypto in here
-
         # ensure the db is encrypted if the file already exists
         if os.path.isfile(opts.path):
-            self.assert_db_is_encrypted(opts)
+            _assert_db_is_encrypted(opts)
 
         # connect to the sqlcipher database
         self._db_handle = initialize_sqlcipher_db(opts)
-        self._real_replica_uid = None
-        self._ensure_schema()
 
+        # TODO ---------------------------------------------------
+        # Everything else in this initialization has to be factored
+        # out, so it can be used from U1DBSqlcipherWrapper __init__
+        # too.
+        # ---------------------------------------------------------
+
+        self._ensure_schema()
         self.set_document_factory(soledad_doc_factory)
+        self._prime_replica_uid()
+
+    def _prime_replica_uid(self):
+        """
+        In the u1db implementation, _replica_uid is a property
+        that returns the value in _real_replica_uid, and does
+        a db query if no value found.
+        Here we prime the replica uid during initialization so
+        that we don't have to wait for the query afterwards.
+        """
+        self._real_replica_uid = None
+        self._get_replica_uid()
+        print "REPLICA UID --->", self._real_replica_uid
 
     def _extra_schema_init(self, c):
         """
@@ -241,7 +254,6 @@ class SQLCipherDatabase(sqlite_backend.SQLitePartialExpandDatabase):
         :param c: The cursor for querying the database.
         :type c: dbapi2.cursor
         """
-        print "CALLING EXTRA SCHEMA INIT...."
         c.execute(
             'ALTER TABLE document '
             'ADD COLUMN syncable BOOL NOT NULL DEFAULT TRUE')
@@ -263,7 +275,7 @@ class SQLCipherDatabase(sqlite_backend.SQLitePartialExpandDatabase):
         """
         doc_rev = sqlite_backend.SQLitePartialExpandDatabase.put_doc(self, doc)
 
-        # XXX move to API
+        # TODO XXX move to API XXX
         if self.defer_encryption:
             self.sync_queue.put_nowait(doc)
         return doc_rev
@@ -272,37 +284,6 @@ class SQLCipherDatabase(sqlite_backend.SQLitePartialExpandDatabase):
     # SQLCipher API methods
     #
 
-    # TODO this doesn't need to be an instance method
-    def assert_db_is_encrypted(self, opts):
-        """
-        Assert that the sqlcipher file contains an encrypted database.
-
-        When opening an existing database, PRAGMA key will not immediately
-        throw an error if the key provided is incorrect. To test that the
-        database can be successfully opened with the provided key, it is
-        necessary to perform some operation on the database (i.e. read from
-        it) and confirm it is success.
-
-        The easiest way to do this is select off the sqlite_master table,
-        which will attempt to read the first page of the database and will
-        parse the schema.
-
-        :param opts:
-        """
-        # We try to open an encrypted database with the regular u1db
-        # backend should raise a DatabaseError exception.
-        # If the regular backend succeeds, then we need to stop because
-        # the database was not properly initialized.
-        try:
-            sqlite_backend.SQLitePartialExpandDatabase(opts.path)
-        except sqlcipher_dbapi2.DatabaseError:
-            # assert that we can access it using SQLCipher with the given
-            # key
-            dummy_query = ('SELECT count(*) FROM sqlite_master',)
-            initialize_sqlcipher_db(opts, on_init=dummy_query)
-        else:
-            raise DatabaseIsNotEncrypted()
-
     # Extra query methods: extensions to the base u1db sqlite implmentation.
 
     def get_count_from_index(self, index_name, *key_values):
@@ -420,65 +401,10 @@ class SQLCipherDatabase(sqlite_backend.SQLitePartialExpandDatabase):
         """
         self.close()
 
-    # TODO ---- rescue the fix for the windows case from here...
-    # @classmethod
-    # def _open_database(cls, sqlcipher_file, password, document_factory=None,
-        # crypto=None, raw_key=False, cipher='aes-256-cbc',
-        # kdf_iter=4000, cipher_page_size=1024,
-        # defer_encryption=False, sync_db_key=None):
-        # """
-        # Open a SQLCipher database.
-#
-        # :return: The database object.
-        # :rtype: SQLCipherDatabase
-        # """
-        # cls.defer_encryption = defer_encryption
-        # if not os.path.isfile(sqlcipher_file):
-        #     raise u1db_errors.DatabaseDoesNotExist()
-#
-        # tries = 2
-        # Note: There seems to be a bug in sqlite 3.5.9 (with python2.6)
-        #       where without re-opening the database on Windows, it
-        #       doesn't see the transaction that was just committed
-        # while True:
-            # with cls.k_lock:
-                # db_handle = dbapi2.connect(
-                    # sqlcipher_file,
-                    # check_same_thread=SQLITE_CHECK_SAME_THREAD)
-#
-                # try:
-                    # set cryptographic params
-#
-                    # XXX pass only a CryptoOptions object around
-                    #pragmas.set_crypto_pragmas(
-                        #db_handle, password, raw_key, cipher, kdf_iter,
-                        #cipher_page_size)
-                    #c = db_handle.cursor()
-                    # XXX if we use it here, it should be public
-                    #v, err = cls._which_index_storage(c)
-                #except Exception as exc:
-                    #logger.warning("ERROR OPENING DATABASE!")
-                    #logger.debug("error was: %r" % exc)
-                    #v, err = None, exc
-                #finally:
-                    #db_handle.close()
-                #if v is not None:
-                    #break
-            # possibly another process is initializing it, wait for it to be
-            # done
-            #if tries == 0:
-                #raise err  # go for the richest error?
-            #tries -= 1
-            #time.sleep(cls.WAIT_FOR_PARALLEL_INIT_HALF_INTERVAL)
-        #return SQLCipherDatabase._sqlite_registry[v](
-            #sqlcipher_file, password, document_factory=document_factory,
-            #crypto=crypto, raw_key=raw_key, cipher=cipher, kdf_iter=kdf_iter,
-            #cipher_page_size=cipher_page_size, sync_db_key=sync_db_key)
-
 
 class SQLCipherU1DBSync(object):
 
-    _sync_watcher = None
+    _sync_loop = None
     _sync_enc_pool = None
 
     """
@@ -495,11 +421,10 @@ class SQLCipherU1DBSync(object):
     encrypting_lock = threading.Lock()
 
     """
-    Period or recurrence of the periodic encrypting task, in seconds.
+    Period or recurrence of the Looping Call that will do the encryption to the
+    syncdb (in seconds).
     """
-    # XXX use LoopingCall.
-    # Just use fucking deferreds, do not waste time looping.
-    ENCRYPT_TASK_PERIOD = 1
+    ENCRYPT_LOOP_PERIOD = 1
 
     """
     A dictionary that hold locks which avoid multiple sync attempts from the
@@ -507,39 +432,62 @@ class SQLCipherU1DBSync(object):
     """
     syncing_lock = defaultdict(threading.Lock)
 
-    def _init_sync(self, opts, soledad_crypto, defer_encryption=False):
+    def __init__(self, opts, soledad_crypto, replica_uid,
+                 defer_encryption=False):
 
         self._crypto = soledad_crypto
-
-        # TODO ----- have to decide what to do with syncer
         self._sync_db_key = opts.sync_db_key
         self._sync_db = None
         self._sync_db_write_lock = None
         self._sync_enc_pool = None
         self.sync_queue = None
 
-        if self.defer_encryption:
-            # initialize sync db
-            self._init_sync_db()
-            # initialize syncing queue encryption pool
-            self._sync_enc_pool = crypto.SyncEncrypterPool(
-                self._crypto, self._sync_db, self._sync_db_write_lock)
-            self._sync_watcher = TimerTask(self._encrypt_syncing_docs,
-                                           self.ENCRYPT_TASK_PERIOD)
-            self._sync_watcher.start()
-
-        # TODO move to class attribute?
         # we store syncers in a dictionary indexed by the target URL. We also
         # store a hash of the auth info in case auth info expires and we need
         # to rebuild the syncer for that target. The final self._syncers
         # format is the following::
         #
         #  self._syncers = {'<url>': ('<auth_hash>', syncer), ...}
+
         self._syncers = {}
         self._sync_db_write_lock = threading.Lock()
         self.sync_queue = multiprocessing.Queue()
 
-    def _init_sync_db(self, opts):
+        self._sync_threadpool = None
+        self._initialize_sync_threadpool()
+
+        if defer_encryption:
+            self._initialize_sync_db()
+
+            # initialize syncing queue encryption pool
+            self._sync_enc_pool = crypto.SyncEncrypterPool(
+                self._crypto, self._sync_db, self._sync_db_write_lock)
+
+            # ------------------------------------------------------------------
+            # From the documentation: If f returns a deferred, rescheduling
+            # will not take place until the deferred has fired. The result
+            # value is ignored.
+
+            # TODO use this to avoid multiple sync attempts if the sync has not
+            # finished!
+            # ------------------------------------------------------------------
+
+            # XXX this was called sync_watcher --- trace any remnants
+            self._sync_loop = LoopingCall(self._encrypt_syncing_docs),
+            self._sync_loop.start(self.ENCRYPT_LOOP_PERIOD)
+
+    def _initialize_sync_threadpool(self):
+        """
+        Initialize a ThreadPool with exactly one thread, that will be used to
+        run all the network blocking calls for syncing on a separate thread.
+
+        TODO this needs to be ported away from urllib and into twisted async
+        calls, and then we can ditch this syncing thread and reintegrate into
+        the main reactor.
+        """
+        self._sync_threadpool = ThreadPool(0, 1)
+
+    def _initialize_sync_db(self, opts):
         """
         Initialize the Symmetrically-Encrypted document to be synced database,
         and the queue to communicate with subprocess workers.
@@ -554,29 +502,32 @@ class SQLCipherU1DBSync(object):
         else:
             sync_db_path = ":memory:"
 
-        # XXX use initialize_sqlcipher_db here too
-        # TODO pass on_init queries to initialize_sqlcipher_db
-        self._sync_db = MPSafeSQLiteDB(sync_db_path)
-        pragmas.set_crypto_pragmas(self._sync_db, opts)
+        # ---------------------------------------------------------
+        # TODO use a separate adbapi for this (sqlcipher only, no u1db)
+        # We could control that it only has 1 or 2 threads.
 
-        # create sync tables
-        self._create_sync_db_tables()
+        opts.path = sync_db_path
 
-    def _create_sync_db_tables(self):
+        self._sync_db = initialize_sqlcipher_db(
+            opts, on_init=self._sync_db_extra_init)
+        # ---------------------------------------------------------
+
+    @property
+    def _sync_db_extra_init(self):
         """
-        Create tables for the local sync documents db if needed.
+        Queries for creating tables for the local sync documents db if needed.
+        They are passed as extra initialization to initialize_sqlciphjer_db
+
+        :rtype: tuple of strings
         """
-        # TODO use adbapi ---------------------------------
+        maybe_create = "CREATE TABLE IF NOT EXISTS %s (%s)"
         encr = crypto.SyncEncrypterPool
         decr = crypto.SyncDecrypterPool
-        sql_encr = ("CREATE TABLE IF NOT EXISTS %s (%s)" % (
+        sql_encr_table_query = (maybe_create % (
             encr.TABLE_NAME, encr.FIELD_NAMES))
-        sql_decr = ("CREATE TABLE IF NOT EXISTS %s (%s)" % (
+        sql_decr_table_query = (maybe_create % (
             decr.TABLE_NAME, decr.FIELD_NAMES))
-
-        with self._sync_db_write_lock:
-            self._sync_db.execute(sql_encr)
-            self._sync_db.execute(sql_decr)
+        return (sql_encr_table_query, sql_decr_table_query)
 
     def sync(self, url, creds=None, autocreate=True, defer_decryption=True):
         """
@@ -599,15 +550,24 @@ class SQLCipherU1DBSync(object):
             database. If False, decryption will be done inline.
         :type defer_decryption: bool
 
-        :return: The local generation before the synchronisation was performed.
-        :rtype: int
+        :return:
+            A Deferred, that will fire with the local generation (type `int`)
+            before the synchronisation was performed.
+        :rtype: deferred
         """
+        kwargs = {'creds': creds, 'autocreate': autocreate,
+                  'defer_decryption': defer_decryption}
+        return deferToThreadPool(self._sync, url, **kwargs)
+
+    def _sync(self, url, creds=None, autocreate=True, defer_decryption=True):
         res = None
+
         # the following context manager blocks until the syncing lock can be
         # acquired.
-        if defer_decryption:
-            self._init_sync_db()
-        with self.syncer(url, creds=creds) as syncer:
+        # TODO review, I think this is no longer needed with a 1-thread
+        # threadpool.
+
+        with self._syncer(url, creds=creds) as syncer:
             # XXX could mark the critical section here...
             try:
                 res = syncer.sync(autocreate=autocreate,
@@ -634,7 +594,7 @@ class SQLCipherU1DBSync(object):
             syncer.stop()
 
     @contextmanager
-    def syncer(self, url, creds=None):
+    def _syncer(self, url, creds=None):
         """
         Accesor for synchronizer.
 
@@ -643,13 +603,13 @@ class SQLCipherU1DBSync(object):
         Because of that, this method blocks until the syncing lock can be
         acquired.
         """
-        with self.syncing_lock[self._get_replica_uid()]:
+        with self.syncing_lock[self.replica_uid]:
             syncer = self._get_syncer(url, creds=creds)
             yield syncer
 
     @property
     def syncing(self):
-        lock = self.syncing_lock[self._get_replica_uid()]
+        lock = self.syncing_lock[self.replica_uid]
         acquired_lock = lock.acquire(False)
         if acquired_lock is False:
             return True
@@ -679,7 +639,7 @@ class SQLCipherU1DBSync(object):
             syncer = SoledadSynchronizer(
                 self,
                 SoledadSyncTarget(url,
-                                  self._replica_uid,
+                                  self.replica_uid,
                                   creds=creds,
                                   crypto=self._crypto,
                                   sync_db=self._sync_db,
@@ -701,8 +661,11 @@ class SQLCipherU1DBSync(object):
         to be encrypted in the sync db. They will be read by the
         SoledadSyncTarget during the sync_exchange.
 
-        Called periodical from the TimerTask self._sync_watcher.
+        Called periodically from the LoopingCall self._sync_loop.
         """
+        # TODO should return a deferred that would firewhen the encryption is
+        # done. See note on __init__
+
         lock = self.encrypting_lock
         # optional wait flag used to avoid blocking
         if not lock.acquire(False):
@@ -720,19 +683,19 @@ class SQLCipherU1DBSync(object):
             finally:
                 lock.release()
 
-    @property
-    def replica_uid(self):
-        return self._get_replica_uid()
+    def get_generation(self):
+        # FIXME
+        # XXX this SHOULD BE a callback
+        return self._get_generation()
 
     def close(self):
         """
         Close the syncer and syncdb orderly
         """
-        # stop the sync watcher for deferred encryption
-        if self._sync_watcher is not None:
-            self._sync_watcher.stop()
-            self._sync_watcher.shutdown()
-            self._sync_watcher = None
+        # stop the sync loop for deferred encryption
+        if self._sync_loop is not None:
+            self._sync_loop.stop()
+            self._sync_loop = None
         # close all open syncers
         for url in self._syncers:
             _, syncer = self._syncers[url]
@@ -753,6 +716,37 @@ class SQLCipherU1DBSync(object):
             del self.sync_queue
             self.sync_queue = None
 
+
+def _assert_db_is_encrypted(opts):
+    """
+    Assert that the sqlcipher file contains an encrypted database.
+
+    When opening an existing database, PRAGMA key will not immediately
+    throw an error if the key provided is incorrect. To test that the
+    database can be successfully opened with the provided key, it is
+    necessary to perform some operation on the database (i.e. read from
+    it) and confirm it is success.
+
+    The easiest way to do this is select off the sqlite_master table,
+    which will attempt to read the first page of the database and will
+    parse the schema.
+
+    :param opts:
+    """
+    # We try to open an encrypted database with the regular u1db
+    # backend should raise a DatabaseError exception.
+    # If the regular backend succeeds, then we need to stop because
+    # the database was not properly initialized.
+    try:
+        sqlite_backend.SQLitePartialExpandDatabase(opts.path)
+    except sqlcipher_dbapi2.DatabaseError:
+        # assert that we can access it using SQLCipher with the given
+        # key
+        dummy_query = ('SELECT count(*) FROM sqlite_master',)
+        initialize_sqlcipher_db(opts, on_init=dummy_query)
+    else:
+        raise DatabaseIsNotEncrypted()
+
 #
 # Exceptions
 #
diff --git a/client/src/leap/soledad/client/sync.py b/client/src/leap/soledad/client/sync.py
index a47afbb6..aa19ddab 100644
--- a/client/src/leap/soledad/client/sync.py
+++ b/client/src/leap/soledad/client/sync.py
@@ -17,10 +17,9 @@
 """
 Soledad synchronization utilities.
 
-
 Extend u1db Synchronizer with the ability to:
 
-    * Defer the update of the known replica uid until all the decryption of
+    * Postpone the update of the known replica uid until all the decryption of
       the incoming messages has been processed.
 
     * Be interrupted and recovered.
@@ -48,6 +47,8 @@ class SoledadSynchronizer(Synchronizer):
     Also modified to allow for interrupting the synchronization process.
     """
 
+    # TODO can delegate the syncing to the api object, living in the reactor
+    # thread, and use a simple flag.
     syncing_lock = Lock()
 
     def stop(self):
@@ -232,6 +233,8 @@ class SoledadSynchronizer(Synchronizer):
         # release if something in the syncdb-decrypt goes wrong. we could keep
         # track of the release date and cleanup unrealistic sync entries after
         # some time.
+
+        # TODO use cancellable deferreds instead
         locked = self.syncing_lock.locked()
         return locked
 
diff --git a/client/src/leap/soledad/client/target.py b/client/src/leap/soledad/client/target.py
index 651d3ee5..9b546402 100644
--- a/client/src/leap/soledad/client/target.py
+++ b/client/src/leap/soledad/client/target.py
@@ -14,14 +14,10 @@
 #
 # You should have received a copy of the GNU General Public License
 # along with this program. If not, see <http://www.gnu.org/licenses/>.
-
-
 """
 A U1DB backend for encrypting data before sending to server and decrypting
 after receiving.
 """
-
-
 import cStringIO
 import gzip
 import logging
@@ -34,7 +30,7 @@ from time import sleep
 from uuid import uuid4
 
 import simplejson as json
-from taskthread import TimerTask
+
 from u1db import errors
 from u1db.remote import utils, http_errors
 from u1db.remote.http_target import HTTPSyncTarget
@@ -42,6 +38,8 @@ from u1db.remote.http_client import _encode_query_parameter, HTTPClientBase
 from zope.proxy import ProxyBase
 from zope.proxy import sameProxiedObjects, setProxiedObject
 
+from twisted.internet.task import LoopingCall
+
 from leap.soledad.common.document import SoledadDocument
 from leap.soledad.client.auth import TokenBasedAuth
 from leap.soledad.client.crypto import is_symmetrically_encrypted
@@ -755,7 +753,7 @@ class SoledadSyncTarget(HTTPSyncTarget, TokenBasedAuth):
     """
     Period of recurrence of the periodic decrypting task, in seconds.
     """
-    DECRYPT_TASK_PERIOD = 0.5
+    DECRYPT_LOOP_PERIOD = 0.5
 
     #
     # Modified HTTPSyncTarget methods.
@@ -802,7 +800,7 @@ class SoledadSyncTarget(HTTPSyncTarget, TokenBasedAuth):
         self._sync_db_write_lock = None
         self._decryption_callback = None
         self._sync_decr_pool = None
-        self._sync_watcher = None
+        self._sync_loop = None
         if sync_db and sync_db_write_lock is not None:
             self._sync_db = sync_db
             self._sync_db_write_lock = sync_db_write_lock
@@ -828,23 +826,22 @@ class SoledadSyncTarget(HTTPSyncTarget, TokenBasedAuth):
             self._sync_decr_pool.close()
             self._sync_decr_pool = None
 
-    def _setup_sync_watcher(self):
+    def _setup_sync_loop(self):
         """
-        Set up the sync watcher for deferred decryption.
+        Set up the sync loop for deferred decryption.
         """
-        if self._sync_watcher is None:
-            self._sync_watcher = TimerTask(
-                self._decrypt_syncing_received_docs,
-                delay=self.DECRYPT_TASK_PERIOD)
+        if self._sync_loop is None:
+            self._sync_loop = LoopingCall(
+                self._decrypt_syncing_received_docs)
+            self._sync_loop.start(self.DECRYPT_LOOP_PERIOD)
 
-    def _teardown_sync_watcher(self):
+    def _teardown_sync_loop(self):
         """
-        Tear down the sync watcher.
+        Tear down the sync loop.
         """
-        if self._sync_watcher is not None:
-            self._sync_watcher.stop()
-            self._sync_watcher.shutdown()
-            self._sync_watcher = None
+        if self._sync_loop is not None:
+            self._sync_loop.stop()
+            self._sync_loop = None
 
     def _get_replica_uid(self, url):
         """
@@ -1131,7 +1128,7 @@ class SoledadSyncTarget(HTTPSyncTarget, TokenBasedAuth):
         if defer_decryption and self._sync_db is not None:
             self._sync_exchange_lock.acquire()
             self._setup_sync_decr_pool()
-            self._setup_sync_watcher()
+            self._setup_sync_loop()
             self._defer_decryption = True
         else:
             # fall back
@@ -1292,10 +1289,10 @@ class SoledadSyncTarget(HTTPSyncTarget, TokenBasedAuth):
 
         # decrypt docs in case of deferred decryption
         if defer_decryption:
-            self._sync_watcher.start()
+            self._sync_loop.start()
             while self.clear_to_sync() is False:
-                sleep(self.DECRYPT_TASK_PERIOD)
-            self._teardown_sync_watcher()
+                sleep(self.DECRYPT_LOOP_PERIOD)
+            self._teardown_sync_loop()
             self._teardown_sync_decr_pool()
             self._sync_exchange_lock.release()
 
@@ -1460,7 +1457,7 @@ class SoledadSyncTarget(HTTPSyncTarget, TokenBasedAuth):
         Decrypt the documents received from remote replica and insert them
         into the local one.
 
-        Called periodically from TimerTask self._sync_watcher.
+        Called periodically from LoopingCall self._sync_loop.
         """
         if sameProxiedObjects(
                 self._insert_doc_cb.get(self.source_replica_uid),