Merge remote-tracking branch 'refs/remotes/drebs/bug/5739_fix-multipart-put-problem-2' into develop

5 files changed, 81 insertions, 239 deletions

diff --git a/client/changes/bug_reset-synchronizer-state b/client/changes/bug_reset-synchronizer-state
new file mode 100644
index 00000000..9678b36b
--- /dev/null
+++ b/client/changes/bug_reset-synchronizer-state
@@ -0,0 +1,2 @@
+  o Reset synchronizer state in order to reuse the same synchronizer object
+    multiple times.
diff --git a/client/src/leap/soledad/client/__init__.py b/client/src/leap/soledad/client/__init__.py
index 2fb33184..0d3a21fd 100644
--- a/client/src/leap/soledad/client/__init__.py
+++ b/client/src/leap/soledad/client/__init__.py
@@ -34,8 +34,6 @@ import urlparse
 import hmac
 
 from hashlib import sha256
-from threading import Lock
-from collections import defaultdict
 
 try:
     import cchardet as chardet
@@ -224,12 +222,6 @@ class Soledad(object):
     Prefix for default values for path.
     """
 
-    syncing_lock = defaultdict(Lock)
-    """
-    A dictionary that hold locks which avoid multiple sync attempts from the
-    same database replica.
-    """
-
     def __init__(self, uuid, passphrase, secrets_path, local_db_path,
                  server_url, cert_file, auth_token=None, secret_id=None):
         """
@@ -1064,8 +1056,6 @@ class Soledad(object):
         :rtype: str
         """
         if self._db:
-            # acquire lock before attempt to sync
-            with Soledad.syncing_lock[self._db._get_replica_uid()]:
                 local_gen = self._db.sync(
                     urlparse.urljoin(self.server_url, 'user-%s' % self._uuid),
                     creds=self._creds, autocreate=False)
diff --git a/client/src/leap/soledad/client/sqlcipher.py b/client/src/leap/soledad/client/sqlcipher.py
index 74351116..5ffa9c7e 100644
--- a/client/src/leap/soledad/client/sqlcipher.py
+++ b/client/src/leap/soledad/client/sqlcipher.py
@@ -52,12 +52,13 @@ import json
 
 from hashlib import sha256
 from contextlib import contextmanager
+from collections import defaultdict
 
 from pysqlcipher import dbapi2
 from u1db.backends import sqlite_backend
 from u1db import errors as u1db_errors
 
-from leap.soledad.client.sync import Synchronizer, ClientSyncState
+from leap.soledad.client.sync import Synchronizer
 from leap.soledad.client.target import SoledadSyncTarget
 from leap.soledad.common.document import SoledadDocument
 
@@ -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):
         """
@@ -401,6 +421,10 @@ class SQLCipherDatabase(sqlite_backend.SQLitePartialExpandDatabase):
                                   creds=creds,
                                   crypto=self._crypto))
             self._syncers[url] = (h, syncer)
+        # in order to reuse the same synchronizer multiple times we have to
+        # reset its state (i.e. the number of documents received from target
+        # and inserted in the local replica).
+        syncer.num_inserted = 0
         return syncer
 
     def _extra_schema_init(self, c):
@@ -889,45 +913,5 @@ class SQLCipherDatabase(sqlite_backend.SQLitePartialExpandDatabase):
         if self._db_handle is not None:
             self._db_handle.close()
 
-    def _get_stored_sync_state(self):
-        """
-        Retrieve the currently stored sync state.
-
-        :return: The current stored sync state or None if there's no stored
-                 state.
-        :rtype: dict or None
-        """
-        c = self._db_handle.cursor()
-        c.execute("SELECT value FROM u1db_config"
-                  " WHERE name = 'sync_state'")
-        val = c.fetchone()
-        if val is None:
-            return None
-        return json.loads(val[0])
-
-    def _set_stored_sync_state(self, state):
-        """
-        Stored the sync state.
-
-        :param state: The sync state to be stored or None to delete any stored
-                      state.
-        :type state: dict or None
-        """
-        c = self._db_handle.cursor()
-        if state is None:
-            c.execute("DELETE FROM u1db_config"
-                      " WHERE name = 'sync_state'")
-        else:
-            c.execute("INSERT OR REPLACE INTO u1db_config"
-                      " VALUES ('sync_state', ?)",
-                      (json.dumps(state),))
-
-    stored_sync_state = property(
-        _get_stored_sync_state, _set_stored_sync_state,
-        doc="The current sync state dict.")
-
-    @property
-    def sync_state(self):
-        return ClientSyncState(self)
 
 sqlite_backend.SQLiteDatabase.register_implementation(SQLCipherDatabase)
diff --git a/client/src/leap/soledad/client/sync.py b/client/src/leap/soledad/client/sync.py
index 5285d540..56e63416 100644
--- a/client/src/leap/soledad/client/sync.py
+++ b/client/src/leap/soledad/client/sync.py
@@ -27,103 +27,6 @@ from u1db import errors
 from u1db.sync import Synchronizer as U1DBSynchronizer
 
 
-class ClientSyncState(object):
-    """
-    The state of the current sync session, as stored on the client.
-    """
-
-    _private_attrs = [
-        '_db',
-    ]
-
-    _public_attrs = {
-        'target_replica_uid': None,
-        'target_gen': None,
-        'target_trans_id': None,
-        'target_my_gen': None,
-        'target_my_trans_id': None,
-        'target_last_known_gen': None,
-        'target_last_known_trans_id': None,
-        'my_gen': None,
-        'changes': None,
-        'sent': 0,
-        'received': 0,
-    }
-
-    @property
-    def _public_attr_keys(self):
-        return self._public_attrs.keys()
-
-    def __init__(self, db=None):
-        """
-        Initialize the client sync state.
-
-        :param db: The database where to fetch/store the sync state.
-        :type db: SQLCipherDatabase
-        """
-        self._db = db
-        self._init_state()
-
-    def __setattr__(self, attr, val):
-        """
-        Prevent setting arbitrary attributes.
-
-        :param attr: The attribute name.
-        :type attr: str
-        :param val: The value to be set.
-        :type val: anything
-        """
-        if attr not in self._public_attr_keys + self._private_attrs:
-            raise Exception
-        object.__setattr__(self, attr, val)
-
-    def _init_state(self):
-        """
-        Initialize current sync state, potentially fetching sync info stored
-        in database.
-        """
-        # set local default attributes
-        for attr in self._public_attr_keys:
-            setattr(self, attr, self._public_attrs[attr])
-        # fetch info from stored sync state
-        sync_state_dict = None
-        if self._db is not None:
-            sync_state_dict = self._db.stored_sync_state
-        if sync_state_dict is not None:
-            for attr in self._public_attr_keys:
-                setattr(self, attr, sync_state_dict[attr])
-
-    def save(self):
-        """
-        Save the current sync state in the database.
-        """
-        sync_state_dict = {}
-        for attr in self._public_attr_keys:
-            sync_state_dict[attr] = getattr(self, attr)
-        if self._db is not None:
-            self._db.stored_sync_state = sync_state_dict
-
-    def clear(self):
-        """
-        Clear the sync state info data.
-        """
-        if self._db is not None:
-            self._db.stored_sync_state = None
-        self._init_state()
-
-    def has_stored_info(self):
-        """
-        Return whether there is any sync state info stored on the database.
-
-        :return: Whether there's any sync state info store on db.
-        :rtype: bool
-        """
-        return self._db is not None and self._db.stored_sync_state is not None
-
-    def __str__(self):
-        return 'ClientSyncState: %s' % ', '.join(
-            ['%s: %s' % (k, getattr(self, k)) for k in self._public_attr_keys])
-
 class Synchronizer(U1DBSynchronizer):
     """
     Collect the state around synchronizing 2 U1DB replicas.
@@ -146,36 +49,20 @@ class Synchronizer(U1DBSynchronizer):
         """
         sync_target = self.sync_target
 
-        # recover current sync state from source database
-        sync_state = self.source.sync_state
-        self.target_replica_uid = sync_state.target_replica_uid
-        target_gen = sync_state.target_gen
-        target_trans_id = sync_state.target_trans_id
-        target_my_gen = sync_state.target_my_gen
-        target_my_trans_id = sync_state.target_my_trans_id
-        target_last_known_gen = sync_state.target_last_known_gen
-        target_last_known_trans_id = \
-            sync_state.target_last_known_trans_id
-        my_gen = sync_state.my_gen
-        changes = sync_state.changes
-        sent = sync_state.sent
-        received = sync_state.received
-
         # get target identifier, its current generation,
         # and its last-seen database generation for this source
         ensure_callback = None
-        if not sync_state.has_stored_info():
-            try:
-                (self.target_replica_uid, target_gen, target_trans_id,
-                 target_my_gen, target_my_trans_id) = \
-                    sync_target.get_sync_info(self.source._replica_uid)
-            except errors.DatabaseDoesNotExist:
-                if not autocreate:
-                    raise
-                # will try to ask sync_exchange() to create the db
-                self.target_replica_uid = None
-                target_gen, target_trans_id = (0, '')
-                target_my_gen, target_my_trans_id = (0, '')
+        try:
+            (self.target_replica_uid, target_gen, target_trans_id,
+             target_my_gen, target_my_trans_id) = \
+                sync_target.get_sync_info(self.source._replica_uid)
+        except errors.DatabaseDoesNotExist:
+            if not autocreate:
+                raise
+            # will try to ask sync_exchange() to create the db
+            self.target_replica_uid = None
+            target_gen, target_trans_id = (0, '')
+            target_my_gen, target_my_trans_id = (0, '')
 
         # make sure we'll have access to target replica uid once it exists
         if self.target_replica_uid is None:
@@ -192,17 +79,15 @@ class Synchronizer(U1DBSynchronizer):
             target_my_gen, target_my_trans_id)
 
         # what's changed since that generation and this current gen
-        if not sync_state.has_stored_info():
-            my_gen, _, changes = self.source.whats_changed(target_my_gen)
+        my_gen, _, changes = self.source.whats_changed(target_my_gen)
 
         # get source last-seen database generation for the target
-        if not sync_state.has_stored_info():
-            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)
+        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)
 
         # validate transaction ids
         if not changes and target_last_known_gen == target_gen:
@@ -220,20 +105,6 @@ class Synchronizer(U1DBSynchronizer):
             _, gen, trans = changes[idx]
             docs_by_generation.append((doc, gen, trans))
             idx += 1
-        # store current sync state info
-        if not sync_state.has_stored_info():
-            sync_state.target_replica_uid = self.target_replica_uid
-            sync_state.target_gen = target_gen
-            sync_state.target_trans_id = target_trans_id
-            sync_state.target_my_gen = target_my_gen
-            sync_state.target_my_trans_id = target_my_trans_id
-            sync_state.my_gen = my_gen
-            sync_state.changes = changes
-            sync_state.target_last_known_trans_id = \
-                target_last_known_trans_id
-            sync_state.target_last_known_gen = target_last_known_gen
-            sync_state.sent = sent = 0
-            sync_state.received = received = 0
 
         # exchange documents and try to insert the returned ones with
         # the target, return target synced-up-to gen.
@@ -243,16 +114,7 @@ class Synchronizer(U1DBSynchronizer):
         new_gen, new_trans_id = 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,
-            sync_state=sync_state)
-
-        # save sync state info if the sync was interrupted
-        if new_gen is None and new_trans_id is None:
-            sync_state.save()
-            return my_gen
-
-        # sync exchange was succesfull, remove sync state info from source
-        sync_state.clear()
+            self._insert_doc_from_target, ensure_callback=ensure_callback)
 
         # record target synced-up-to generation including applying what we sent
         self.source._set_replica_gen_and_trans_id(
diff --git a/client/src/leap/soledad/client/target.py b/client/src/leap/soledad/client/target.py
index 93de98d3..968545b6 100644
--- a/client/src/leap/soledad/client/target.py
+++ b/client/src/leap/soledad/client/target.py
@@ -63,7 +63,6 @@ from leap.soledad.client.events import (
     SOLEDAD_SYNC_RECEIVE_STATUS,
     signal,
 )
-from leap.soledad.client.sync import ClientSyncState
 
 logger = logging.getLogger(__name__)
 
@@ -321,7 +320,6 @@ class SoledadSyncTarget(HTTPSyncTarget, TokenBasedAuth):
         HTTPSyncTarget.__init__(self, url, creds)
         self._crypto = crypto
         self._stopped = True
-        self._sync_state = None
         self._stop_lock = threading.Lock()
 
     def _init_post_request(self, url, action, headers, content_length):
@@ -347,7 +345,7 @@ class SoledadSyncTarget(HTTPSyncTarget, TokenBasedAuth):
         self._conn.endheaders()
 
     def _get_remote_docs(self, url, last_known_generation, last_known_trans_id,
-                         headers, return_doc_cb, ensure_callback=None):
+                         headers, return_doc_cb, ensure_callback, sync_id):
         """
         Fetch sync documents from the remote database and insert them in the
         local database.
@@ -377,9 +375,13 @@ class SoledadSyncTarget(HTTPSyncTarget, TokenBasedAuth):
         :rtype: list of str
         """
 
-        def _post_get_doc():
+        def _post_get_doc(received):
             """
             Get a sync document from server by means of a POST request.
+
+            :param received: The number of documents already received in the
+                             current sync session.
+            :type received: int
             """
             entries = ['[']
             size = 1
@@ -388,10 +390,11 @@ class SoledadSyncTarget(HTTPSyncTarget, TokenBasedAuth):
                 '', entries,
                 last_known_generation=last_known_generation,
                 last_known_trans_id=last_known_trans_id,
+                sync_id=sync_id,
                 ensure=ensure_callback is not None)
             # inform server of how many documents have already been received
             size += self._prepare(
-                ',', entries, received=self._sync_state.received)
+                ',', entries, received=received)
             entries.append('\r\n]')
             size += len(entries[-1])
             # send headers
@@ -402,14 +405,16 @@ class SoledadSyncTarget(HTTPSyncTarget, TokenBasedAuth):
             return self._response()
 
         number_of_changes = None
+        received = 0
 
-        while number_of_changes is None or \
-                self._sync_state.received < number_of_changes:
+        new_generation = last_known_generation
+        new_transaction_id = last_known_trans_id
+        while number_of_changes is None or received < number_of_changes:
             # bail out if sync process was interrupted
             if self.stopped is True:
-                return None, None
+                return last_known_generation, last_known_trans_id
             # try to fetch one document from target
-            data, _ = _post_get_doc()
+            data, _ = _post_get_doc(received)
             # decode incoming stream
             parts = data.splitlines()
             if not parts or parts[0] != '[' or parts[-1] != ']':
@@ -424,6 +429,8 @@ class SoledadSyncTarget(HTTPSyncTarget, TokenBasedAuth):
                 soledad_assert('new_generation' in metadata)
                 soledad_assert('new_transaction_id' in metadata)
                 number_of_changes = metadata['number_of_changes']
+                new_generation = metadata['new_generation']
+                new_transaction_id = metadata['new_transaction_id']
             except json.JSONDecodeError, AssertionError:
                 raise BrokenSyncStream
             # make sure we have replica_uid from fresh new dbs
@@ -453,12 +460,12 @@ class SoledadSyncTarget(HTTPSyncTarget, TokenBasedAuth):
             # end of symmetric decryption
             # -------------------------------------------------------------
             return_doc_cb(doc, entry['gen'], entry['trans_id'])
-            self._sync_state.received += 1
+            received += 1
             signal(
                 SOLEDAD_SYNC_RECEIVE_STATUS,
                 "%d/%d" %
-                (self._sync_state.received, number_of_changes))
-        return metadata['new_generation'], metadata['new_transaction_id']
+                (received, number_of_changes))
+        return new_generation, new_transaction_id
 
     def _request(self, method, url_parts, params=None, body=None,
                  content_type=None):
@@ -566,8 +573,7 @@ class SoledadSyncTarget(HTTPSyncTarget, TokenBasedAuth):
 
     def sync_exchange(self, docs_by_generations, source_replica_uid,
                       last_known_generation, last_known_trans_id,
-                      return_doc_cb, ensure_callback=None,
-                      sync_state=None):
+                      return_doc_cb, ensure_callback=None):
         """
         Find out which documents the remote database does not know about,
         encrypt and send them.
@@ -596,12 +602,8 @@ class SoledadSyncTarget(HTTPSyncTarget, TokenBasedAuth):
         :return: The new generation and transaction id of the target replica.
         :rtype: tuple
         """
-        # get the sync state information from client
-        self._sync_state = sync_state
-        if self._sync_state is None:
-            self._sync_state = ClientSyncState()
-
         self.start()
+        sync_id = str(uuid4())
 
         self._ensure_connection()
         if self._trace_hook:  # for tests
@@ -610,7 +612,7 @@ class SoledadSyncTarget(HTTPSyncTarget, TokenBasedAuth):
         headers = self._sign_request('POST', url, {})
 
         def _post_put_doc(headers, last_known_generation, last_known_trans_id,
-                          id, rev, content, gen, trans_id):
+                          id, rev, content, gen, trans_id, sync_id):
             """
             Put a sync document on server by means of a POST request.
 
@@ -626,6 +628,7 @@ class SoledadSyncTarget(HTTPSyncTarget, TokenBasedAuth):
                 '', entries,
                 last_known_generation=last_known_generation,
                 last_known_trans_id=last_known_trans_id,
+                sync_id=sync_id,
                 ensure=ensure_callback is not None)
             # add the document to the request
             size += self._prepare(
@@ -645,11 +648,11 @@ class SoledadSyncTarget(HTTPSyncTarget, TokenBasedAuth):
         cur_target_gen = last_known_generation
         cur_target_trans_id = last_known_trans_id
 
-        # skip docs that were already sent
-        if self._sync_state.sent > 0:
-            docs_by_generations = docs_by_generations[self._sync_state.sent:]
-
         # send docs
+        sent = 0
+        signal(
+            SOLEDAD_SYNC_SEND_STATUS,
+            "%d/%d" % (0, len(docs_by_generations)))
         for doc, gen, trans_id in docs_by_generations:
             # allow for interrupting the sync process
             if self.stopped is True:
@@ -668,17 +671,18 @@ class SoledadSyncTarget(HTTPSyncTarget, TokenBasedAuth):
             # -------------------------------------------------------------
             cur_target_gen, cur_target_trans_id = _post_put_doc(
                 headers, cur_target_gen, cur_target_trans_id, id=doc.doc_id,
-                rev=doc.rev, content=doc_json, gen=gen, trans_id=trans_id)
-            self._sync_state.sent += 1
+                rev=doc.rev, content=doc_json, gen=gen, trans_id=trans_id,
+                sync_id=sync_id)
+            sent += 1
             signal(
                 SOLEDAD_SYNC_SEND_STATUS,
-                "%d/%d" % (self._sync_state.sent, len(docs_by_generations)))
+                "%d/%d" % (sent, len(docs_by_generations)))
 
         # get docs from target
         cur_target_gen, cur_target_trans_id = self._get_remote_docs(
             url,
             last_known_generation, last_known_trans_id, headers,
-            return_doc_cb, ensure_callback)
+            return_doc_cb, ensure_callback, sync_id)
         self.stop()
         return cur_target_gen, cur_target_trans_id