From d76d89323c4b962b4f3ff72a3c9b40f2d2d347b3 Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Fri, 1 Apr 2016 17:39:32 +0100
Subject: [PATCH] Use computed prev event ids

---
 synapse/handlers/_base.py           | 29 +++++++++++++++++------------
 synapse/handlers/message.py         |  6 +++++-
 synapse/handlers/room_member.py     |  3 +++
 synapse/storage/event_federation.py | 16 ++++++++++++++++
 4 files changed, 41 insertions(+), 13 deletions(-)

diff --git a/synapse/handlers/_base.py b/synapse/handlers/_base.py
index 2d8ff79a9e..242afa1564 100644
--- a/synapse/handlers/_base.py
+++ b/synapse/handlers/_base.py
@@ -199,20 +199,25 @@ class BaseHandler(object):
             )
 
     @defer.inlineCallbacks
-    def _create_new_client_event(self, builder):
-        latest_ret = yield self.store.get_latest_event_ids_and_hashes_in_room(
-            builder.room_id,
-        )
-
-        if latest_ret:
-            depth = max([d for _, _, d in latest_ret]) + 1
+    def _create_new_client_event(self, builder, prev_event_ids=None):
+        if prev_event_ids:
+            prev_events = yield self.store.add_event_hashes(prev_event_ids)
+            prev_max_depth = yield self.store.get_max_depth_of_events(prev_event_ids)
+            depth = prev_max_depth + 1
         else:
-            depth = 1
+            latest_ret = yield self.store.get_latest_event_ids_and_hashes_in_room(
+                builder.room_id,
+            )
 
-        prev_events = [
-            (event_id, prev_hashes)
-            for event_id, prev_hashes, _ in latest_ret
-        ]
+            if latest_ret:
+                depth = max([d for _, _, d in latest_ret]) + 1
+            else:
+                depth = 1
+
+            prev_events = [
+                (event_id, prev_hashes)
+                for event_id, prev_hashes, _ in latest_ret
+            ]
 
         builder.prev_events = prev_events
         builder.depth = depth
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index 0bb111d047..10608c0dd9 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -176,7 +176,7 @@ class MessageHandler(BaseHandler):
         defer.returnValue(chunk)
 
     @defer.inlineCallbacks
-    def create_event(self, event_dict, token_id=None, txn_id=None):
+    def create_event(self, event_dict, token_id=None, txn_id=None, prev_event_ids=None):
         """
         Given a dict from a client, create a new event.
 
@@ -187,6 +187,9 @@ class MessageHandler(BaseHandler):
 
         Args:
             event_dict (dict): An entire event
+            token_id (str)
+            txn_id (str)
+            prev_event_ids (list): The prev event ids to use when creating the event
 
         Returns:
             Tuple of created event (FrozenEvent), Context
@@ -225,6 +228,7 @@ class MessageHandler(BaseHandler):
 
         event, context = yield self._create_new_client_event(
             builder=builder,
+            prev_event_ids=prev_event_ids,
         )
         defer.returnValue((event, context))
 
diff --git a/synapse/handlers/room_member.py b/synapse/handlers/room_member.py
index 09b8f6217a..7c1bb8cfe4 100644
--- a/synapse/handlers/room_member.py
+++ b/synapse/handlers/room_member.py
@@ -98,6 +98,7 @@ class RoomMemberHandler(BaseHandler):
     @defer.inlineCallbacks
     def _local_membership_update(
         self, requester, target, room_id, membership,
+        prev_event_ids,
         txn_id=None,
         ratelimit=True,
     ):
@@ -120,6 +121,7 @@ class RoomMemberHandler(BaseHandler):
             },
             token_id=requester.access_token_id,
             txn_id=txn_id,
+            prev_event_ids=prev_event_ids,
         )
 
         yield self.handle_new_client_event(
@@ -268,6 +270,7 @@ class RoomMemberHandler(BaseHandler):
             membership=effective_membership_state,
             txn_id=txn_id,
             ratelimit=ratelimit,
+            prev_event_ids=latest_event_ids,
         )
 
     @defer.inlineCallbacks
diff --git a/synapse/storage/event_federation.py b/synapse/storage/event_federation.py
index 3489315e0d..0827946207 100644
--- a/synapse/storage/event_federation.py
+++ b/synapse/storage/event_federation.py
@@ -163,6 +163,22 @@ class EventFederationStore(SQLBaseStore):
             room_id,
         )
 
+    @defer.inlineCallbacks
+    def get_max_depth_of_events(self, event_ids):
+        sql = (
+            "SELECT MAX(depth) FROM events WHERE event_id IN (%s)"
+        ) % (",".join(["?"] * len(event_ids)),)
+
+        rows = yield self._execute(
+            "get_max_depth_of_events", None,
+            sql, *event_ids
+        )
+
+        if rows:
+            defer.returnValue(rows[0][0])
+        else:
+            defer.returnValue(1)
+
     def _get_min_depth_interaction(self, txn, room_id):
         min_depth = self._simple_select_one_onecol_txn(
             txn,