From 447aed42d22d3ece245c69f397d348b3a5b7bfa8 Mon Sep 17 00:00:00 2001
From: Richard van der Hoff <richard@matrix.org>
Date: Sat, 27 Jan 2018 15:40:41 +0000
Subject: [PATCH] Add event_map param to resolve_state_groups

---
 synapse/state.py          | 34 ++++++++++++++++++++++++++++++----
 synapse/storage/events.py |  1 +
 2 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/synapse/state.py b/synapse/state.py
index 273f9911c..6c2aaa5e7 100644
--- a/synapse/state.py
+++ b/synapse/state.py
@@ -308,7 +308,7 @@ class StateHandler(object):
             ))
 
         result = yield self._state_resolution_handler.resolve_state_groups(
-            room_id, state_groups_ids, self._state_map_factory,
+            room_id, state_groups_ids, None, self._state_map_factory,
         )
         defer.returnValue(result)
 
@@ -371,7 +371,9 @@ class StateResolutionHandler(object):
 
     @defer.inlineCallbacks
     @log_function
-    def resolve_state_groups(self, room_id, state_groups_ids, state_map_factory):
+    def resolve_state_groups(
+        self, room_id, state_groups_ids, event_map, state_map_factory,
+    ):
         """Resolves conflicts between a set of state groups
 
         Always generates a new state group (unless we hit the cache), so should
@@ -383,6 +385,14 @@ class StateResolutionHandler(object):
                  map from state group id to the state in that state group
                 (where 'state' is a map from state key to event id)
 
+            event_map(dict[str,FrozenEvent]|None):
+                a dict from event_id to event, for any events that we happen to
+                have in flight (eg, those currently being persisted). This will be
+                used as a starting point fof finding the state we need; any missing
+                events will be requested via state_map_factory.
+
+                If None, all events will be fetched via state_map_factory.
+
         Returns:
             Deferred[_StateCacheEntry]: resolved state
         """
@@ -423,6 +433,7 @@ class StateResolutionHandler(object):
                 with Measure(self.clock, "state._resolve_events"):
                     new_state = yield resolve_events_with_factory(
                         state_groups_ids.values(),
+                        event_map=event_map,
                         state_map_factory=state_map_factory,
                     )
             else:
@@ -555,11 +566,20 @@ def _seperate(state_sets):
 
 
 @defer.inlineCallbacks
-def resolve_events_with_factory(state_sets, state_map_factory):
+def resolve_events_with_factory(state_sets, event_map, state_map_factory):
     """
     Args:
         state_sets(list): List of dicts of (type, state_key) -> event_id,
             which are the different state groups to resolve.
+
+        event_map(dict[str,FrozenEvent]|None):
+            a dict from event_id to event, for any events that we happen to
+            have in flight (eg, those currently being persisted). This will be
+            used as a starting point fof finding the state we need; any missing
+            events will be requested via state_map_factory.
+
+            If None, all events will be fetched via state_map_factory.
+
         state_map_factory(func): will be called
             with a list of event_ids that are needed, and should return with
             a Deferred of dict of event_id to event.
@@ -580,12 +600,16 @@ def resolve_events_with_factory(state_sets, state_map_factory):
         for event_ids in conflicted_state.itervalues()
         for event_id in event_ids
     )
+    if event_map is not None:
+        needed_events -= set(event_map.iterkeys())
 
     logger.info("Asking for %d conflicted events", len(needed_events))
 
     # dict[str, FrozenEvent]: a map from state event id to event. Only includes
-    # the state events which are in conflict.
+    # the state events which are in conflict (and those in event_map)
     state_map = yield state_map_factory(needed_events)
+    if event_map is not None:
+        state_map.update(event_map)
 
     # get the ids of the auth events which allow us to authenticate the
     # conflicted state, picking only from the unconflicting state.
@@ -597,6 +621,8 @@ def resolve_events_with_factory(state_sets, state_map_factory):
 
     new_needed_events = set(auth_events.itervalues())
     new_needed_events -= needed_events
+    if event_map is not None:
+        new_needed_events -= set(event_map.iterkeys())
 
     logger.info("Asking for %d auth events", len(new_needed_events))
 
diff --git a/synapse/storage/events.py b/synapse/storage/events.py
index 2fead9eb0..7b912ad41 100644
--- a/synapse/storage/events.py
+++ b/synapse/storage/events.py
@@ -586,6 +586,7 @@ class EventsStore(SQLBaseStore):
 
                 current_state = yield resolve_events_with_factory(
                     state_sets,
+                    event_map={},
                     state_map_factory=get_events,
                 )
                 defer.returnValue(current_state)