[bug] use couch lock to atomize saving of document

1 files changed, 50 insertions, 48 deletions

diff --git a/common/src/leap/soledad/common/couch/__init__.py b/common/src/leap/soledad/common/couch/__init__.py
index 032f230b..2d57635a 100644
--- a/common/src/leap/soledad/common/couch/__init__.py
+++ b/common/src/leap/soledad/common/couch/__init__.py
@@ -705,8 +705,6 @@ class CouchDatabase(object):
             }
             parts.append(conflicts)
 
-        # add the gen document
-
         # TODO: in u1db protocol, the increment of database generation should
         # be made in the same atomic transaction as the actual document save,
         # otherwise the same document might be concurrently updated by
@@ -714,6 +712,8 @@ class CouchDatabase(object):
         # and doc_id would be enough to prevent that, if all entry points to
         # database update are made through the soledad api.
         with self._put_doc_lock[self._database.name]:
+
+            # add the gen document
             gen, _ = self.get_generation_info()
             new_gen = gen + 1
             gen_doc = {
@@ -724,52 +724,54 @@ class CouchDatabase(object):
             }
             self._database.save(gen_doc)
 
-        # build the couch document
-        couch_doc = {
-            '_id': doc.doc_id,
-            'u1db_rev': doc.rev,
-            '_attachments': attachments,
-        }
-        # if we are updating a doc we have to add the couch doc revision
-        if old_doc is not None and hasattr(old_doc, 'couch_rev'):
-            couch_doc['_rev'] = old_doc.couch_rev
-        # prepare the multipart PUT
-        if not self.batching:
-            buf = StringIO()
-            envelope = MultipartWriter(buf)
-            # the order in which attachments are described inside the
-            # serialization of the couch document must match the order in which
-            # they are actually written in the multipart structure. Because of
-            # that, we use `sorted_keys=True` in the json serialization (so
-            # "u1db_conflicts" comes before "u1db_content" on the couch
-            # document attachments description), and also reverse the order of
-            # the parts before writing them, so the "conflict" part is written
-            # before the "content" part.
-            envelope.add(
-                'application/json',
-                json.dumps(couch_doc, sort_keys=True))
-            parts.reverse()
-            for part in parts:
-                envelope.add('application/octet-stream', part)
-            envelope.close()
-            # try to save and fail if there's a revision conflict
-            try:
-                resource = self._new_resource()
-                resource.put_json(
-                    doc.doc_id, body=str(buf.getvalue()),
-                    headers=envelope.headers)
-            except ResourceConflict:
-                raise RevisionConflict()
-        else:
-            for name, attachment in attachments.items():
-                del attachment['follows']
-                del attachment['length']
-                index = 0 if name is 'u1db_content' else 1
-                attachment['data'] = binascii.b2a_base64(parts[index]).strip()
-            couch_doc['_attachments'] = attachments
-            self.batch_docs[doc.doc_id] = couch_doc
-            last_gen, last_trans_id = self.batch_generation
-            self.batch_generation = (last_gen + 1, transaction_id)
+            # build the couch document
+            couch_doc = {
+                '_id': doc.doc_id,
+                'u1db_rev': doc.rev,
+                '_attachments': attachments,
+            }
+            # if we are updating a doc we have to add the couch doc revision
+            if old_doc is not None and hasattr(old_doc, 'couch_rev'):
+                couch_doc['_rev'] = old_doc.couch_rev
+            # prepare the multipart PUT
+            if not self.batching:
+                buf = StringIO()
+                envelope = MultipartWriter(buf)
+                # the order in which attachments are described inside the
+                # serialization of the couch document must match the order in
+                # which they are actually written in the multipart structure.
+                # Because of that, we use `sorted_keys=True` in the json
+                # serialization (so "u1db_conflicts" comes before
+                # "u1db_content" on the couch document attachments
+                # description), and also reverse the order of the parts before
+                # writing them, so the "conflict" part is written before the
+                # "content" part.
+                envelope.add(
+                    'application/json',
+                    json.dumps(couch_doc, sort_keys=True))
+                parts.reverse()
+                for part in parts:
+                    envelope.add('application/octet-stream', part)
+                envelope.close()
+                # try to save and fail if there's a revision conflict
+                try:
+                    resource = self._new_resource()
+                    resource.put_json(
+                        doc.doc_id, body=str(buf.getvalue()),
+                        headers=envelope.headers)
+                except ResourceConflict:
+                    raise RevisionConflict()
+            else:
+                for name, attachment in attachments.items():
+                    del attachment['follows']
+                    del attachment['length']
+                    index = 0 if name is 'u1db_content' else 1
+                    attachment['data'] = binascii.b2a_base64(
+                        parts[index]).strip()
+                couch_doc['_attachments'] = attachments
+                self.batch_docs[doc.doc_id] = couch_doc
+                last_gen, last_trans_id = self.batch_generation
+                self.batch_generation = (last_gen + 1, transaction_id)
 
     def _new_resource(self, *path):
         """