Fix RewritesState bug (#1557)

* Set RewritesState once

* Check if any new state provided

* Obey rewritesState

* Don't nuke everything the sync API knows when purging state

* Fix panic from duplicate insert

* Consistency

* Use HasState

* Remove nolint

* Clean up joined rooms on state rewrite

1 files changed, 14 insertions, 0 deletions

diff --git a/federationsender/storage/shared/storage.go b/federationsender/storage/shared/storage.go
index 4c80c079..d5731f31 100644
--- a/federationsender/storage/shared/storage.go
+++ b/federationsender/storage/shared/storage.go
@@ -148,6 +148,20 @@ func (d *Database) StoreJSON(
 	}, nil
 }
 
+func (d *Database) PurgeRoomState(
+	ctx context.Context, roomID string,
+) error {
+	return d.Writer.Do(d.DB, nil, func(txn *sql.Tx) error {
+		// If the event is a create event then we'll delete all of the existing
+		// data for the room. The only reason that a create event would be replayed
+		// to us in this way is if we're about to receive the entire room state.
+		if err := d.FederationSenderJoinedHosts.DeleteJoinedHostsForRoom(ctx, txn, roomID); err != nil {
+			return fmt.Errorf("d.FederationSenderJoinedHosts.DeleteJoinedHosts: %w", err)
+		}
+		return nil
+	})
+}
+
 func (d *Database) AddServerToBlacklist(serverName gomatrixserverlib.ServerName) error {
 	return d.Writer.Do(d.DB, nil, func(txn *sql.Tx) error {
 		return d.FederationSenderBlacklist.InsertBlacklist(context.TODO(), txn, serverName)