1 files changed, 210 insertions, 0 deletions
diff --git a/src/leap/soledad/backends/objectstore.py b/src/leap/soledad/backends/objectstore.py
new file mode 100644
index 00000000..61445a1f
--- /dev/null
+++ b/src/leap/soledad/backends/objectstore.py
@@ -0,0 +1,210 @@
+import uuid
+from u1db.backends import CommonBackend
+from u1db import errors, Document
+from soledad.util import SyncLog, TransactionLog
+
+
+class ObjectStore(CommonBackend):
+    """
+    A backend for storing u1db data in an object store.
+    """
+
+    def __init__(self):
+        # This initialization method should be called after the connection
+        # with the database is established, so it can ensure that u1db data is
+        # configured and up-to-date.
+        self.set_document_factory(Document)
+        self._sync_log = SyncLog()
+        self._transaction_log = TransactionLog()
+        self._ensure_u1db_data()
+
+    #-------------------------------------------------------------------------
+    # implemented methods from Database
+    #-------------------------------------------------------------------------
+
+    def set_document_factory(self, factory):
+        self._factory = factory
+
+    def set_document_size_limit(self, limit):
+        raise NotImplementedError(self.set_document_size_limit)
+
+    def whats_changed(self, old_generation=0):
+        self._get_u1db_data()
+        return self._transaction_log.whats_changed(old_generation)
+
+    def get_doc(self, doc_id, include_deleted=False):
+        doc = self._get_doc(doc_id, check_for_conflicts=True)
+        if doc is None:
+            return None
+        if doc.is_tombstone() and not include_deleted:
+            return None
+        return doc
+
+    def _put_doc(self, doc):
+        raise NotImplementedError(self._put_doc)
+
+    def put_doc(self, doc):
+        # consistency check
+        if doc.doc_id is None:
+            raise errors.InvalidDocId()
+        self._check_doc_id(doc.doc_id)
+        self._check_doc_size(doc)
+        # check if document exists
+        old_doc = self._get_doc(doc.doc_id, check_for_conflicts=True)
+        if old_doc and old_doc.has_conflicts:
+            raise errors.ConflictedDoc()
+        if old_doc and doc.rev is None and old_doc.is_tombstone():
+            new_rev = self._allocate_doc_rev(old_doc.rev)
+        else:
+            if old_doc is not None:
+                if old_doc.rev != doc.rev:
+                    raise errors.RevisionConflict()
+            else:
+                if doc.rev is not None:
+                    raise errors.RevisionConflict()
+            new_rev = self._allocate_doc_rev(doc.rev)
+        doc.rev = new_rev
+        self._put_doc(doc)
+        # update u1db generation and logs
+        new_gen = self._get_generation() + 1
+        trans_id = self._allocate_transaction_id()
+        self._transaction_log.append((new_gen, doc.doc_id, trans_id))
+        self._set_u1db_data()
+        return doc.rev
+
+    def delete_doc(self, doc):
+        old_doc = self._get_doc(doc.doc_id, check_for_conflicts=True)
+        if old_doc is None:
+            raise errors.DocumentDoesNotExist
+        if old_doc.rev != doc.rev:
+            raise errors.RevisionConflict()
+        if old_doc.is_tombstone():
+            raise errors.DocumentAlreadyDeleted
+        if old_doc.has_conflicts:
+            raise errors.ConflictedDoc()
+        new_rev = self._allocate_doc_rev(doc.rev)
+        doc.rev = new_rev
+        doc.make_tombstone()
+        self._put_doc(doc)
+        return new_rev
+
+    # start of index-related methods: these are not supported by this backend.
+
+    def create_index(self, index_name, *index_expressions):
+        return False
+
+    def delete_index(self, index_name):
+        return False
+
+    def list_indexes(self):
+        return []
+
+    def get_from_index(self, index_name, *key_values):
+        return []
+
+    def get_range_from_index(self, index_name, start_value=None,
+                             end_value=None):
+        return []
+
+    def get_index_keys(self, index_name):
+        return []
+
+    # end of index-related methods: these are not supported by this backend.
+
+    def get_doc_conflicts(self, doc_id):
+        return []
+
+    def resolve_doc(self, doc, conflicted_doc_revs):
+        raise NotImplementedError(self.resolve_doc)
+
+    def _get_replica_gen_and_trans_id(self, other_replica_uid):
+        self._get_u1db_data()
+        return self._sync_log.get_replica_gen_and_trans_id(other_replica_uid)
+
+    def _set_replica_gen_and_trans_id(self, other_replica_uid,
+                                      other_generation, other_transaction_id):
+        self._get_u1db_data()
+        self._sync_log.set_replica_gen_and_trans_id(other_replica_uid,
+                                                    other_generation,
+                                                    other_transaction_id)
+        self._set_u1db_data()
+
+    #-------------------------------------------------------------------------
+    # implemented methods from CommonBackend
+    #-------------------------------------------------------------------------
+
+    def _get_generation(self):
+        self._get_u1db_data()
+        return self._transaction_log.get_generation()
+
+    def _get_generation_info(self):
+        self._get_u1db_data()
+        return self._transaction_log.get_generation_info()
+
+    def _has_conflicts(self, doc_id):
+        # Documents never have conflicts on server.
+        return False
+
+    def _put_and_update_indexes(self, doc_id, old_doc, new_rev, content):
+        raise NotImplementedError(self._put_and_update_indexes)
+
+
+    def _get_trans_id_for_gen(self, generation):
+        self._get_u1db_data()
+        trans_id = self._transaction_log.get_trans_id_for_gen(generation)
+        if trans_id is None:
+            raise errors.InvalidGeneration
+        return trans_id
+
+    #-------------------------------------------------------------------------
+    # methods specific for object stores
+    #-------------------------------------------------------------------------
+
+    def _ensure_u1db_data(self):
+        """
+        Guarantee that u1db data (logs and replica info) exists in store.
+        """
+        if not self._is_initialized():
+            self._initialize()
+        self._get_u1db_data()
+
+    U1DB_DATA_DOC_ID = 'u1db_data'
+
+    def _is_initialized(self):
+        """
+        Verify if u1db data exists in store.
+        """
+        doc = self._get_doc(self.U1DB_DATA_DOC_ID)
+        if not self._get_doc(self.U1DB_DATA_DOC_ID):
+            return False
+        return True
+
+    def _initialize(self):
+        """
+        Create u1db data object in store.
+        """
+        self._replica_uid = uuid.uuid4().hex
+        doc = self._factory(doc_id=self.U1DB_DATA_DOC_ID)
+        doc.content = { 'transaction_log' : [],
+                        'sync_log' : [],
+                        'replica_uid' : self._replica_uid }
+        self._put_doc(doc)
+
+    def _get_u1db_data(self, u1db_data_doc_id):
+        """
+        Fetch u1db configuration data from backend storage.
+        """
+        NotImplementedError(self._get_u1db_data)
+
+    def _set_u1db_data(self):
+        """
+        Save u1db configuration data on backend storage.
+        """
+        doc = self._factory(doc_id=self.U1DB_DATA_DOC_ID)
+        doc.content = { 'transaction_log' : self._transaction_log.log,
+                        'sync_log'        : self._sync_log.log,
+                        'replica_uid'     : self._replica_uid,
+                        '_rev'            : self._couch_rev}
+        self._put_doc(doc)
+
+