wip

src/Simplex/Chat/Library/Commands.hs

@@ -2770,8 +2770,9 @@ processChatCommand cxt nm = \case
       (errs1, changed1) <- changeRoleInvitedMems user gInfo invitedMems
       let doBumpRoster = useRelays' gInfo && memberRole' (membership gInfo) == GROwner && (isRosterRole newRole || anyPrivilegedTarget)
       rosterVer <- if doBumpRoster then Just <$> reserveRosterVersion gInfo else pure Nothing
+      -- roster (with the change projected in) before the delta, so a relay stores the blob at this version before forwarding the delta
+      forM_ rosterVer $ \v -> broadcastRoster user gInfo v (RDRoleChanged newRole currentMems) `catchAllErrors` eToView
       (errs2, changed2, acis, msgSigned) <- changeRoleCurrentMems user g rosterVer currentMems
-      forM_ rosterVer $ \v -> broadcastRoster user gInfo v `catchAllErrors` eToView
       unless (null acis) $ toView $ CEvtNewChatItems user acis
       let errs = errs1 <> errs2
       unless (null errs) $ toView $ CEvtChatErrors errs
@@ -2898,13 +2899,14 @@ processChatCommand cxt nm = \case
       let recipients = filter memberCurrent members
       let doBumpRoster = useRelays' gInfo && memberRole' (membership gInfo) == GROwner && anyPrivilegedRemoved
       rosterVer <- if doBumpRoster then Just <$> reserveRosterVersion gInfo else pure Nothing
+      -- roster (excluding the removed members) before the delta, so a relay stores the blob at this version before forwarding the delta
+      forM_ rosterVer $ \v -> broadcastRoster user gInfo v (RDRemoved currentMems) `catchAllErrors` eToView
       (errs2, deleted2, acis2, signed2) <- deleteMemsSend user gInfo Nothing rosterVer recipients currentMems
       (errs3, deleted3, acis3, signed3) <-
         foldM (\acc m -> deletePendingMember acc user gInfo [m] m) ([], [], [], False) pendingApprvMems
       let moderators = filter (\GroupMember {memberRole} -> memberRole >= GRModerator) members
       (errs4, deleted4, acis4, signed4) <-
         foldM (\acc m -> deletePendingMember acc user gInfo (m : moderators) m) ([], [], [], False) pendingRvwMems
-      forM_ rosterVer $ \v -> broadcastRoster user gInfo v `catchAllErrors` eToView
       let acis = acis2 <> acis3 <> acis4
           errs = errs1 <> errs2 <> errs3 <> errs4
           deleted = deleted1 <> deleted2 <> deleted3 <> deleted4

src/Simplex/Chat/Library/Internal.hs

@@ -2271,20 +2271,34 @@ sendGroupMessage' user gInfo members chatMsgEvent =
 -- TODO   after restoring from a stale backup (relays accept only strictly-greater versions)
 -- Persist the next roster version before sending the events that carry it (so a recipient never advances
 -- past a version the owner hasn't recorded). The matching blob is broadcast separately, by broadcastRoster,
--- after the change is applied to the owner's members - so the served roster excludes demoted/removed members.
+-- with the change projected onto the served roster - so it excludes demoted/removed members.
 reserveRosterVersion :: GroupInfo -> CM VersionRoster
 reserveRosterVersion gInfo = do
   let rosterVer = maybe (VersionRoster 0) (\(VersionRoster n) -> VersionRoster (n + 1)) (rosterVersion gInfo)
   withStore' $ \db -> setGroupRosterVersion db gInfo rosterVer
   pure rosterVer
 
-broadcastRoster :: User -> GroupInfo -> VersionRoster -> CM ()
-broadcastRoster user gInfo rosterVer = do
+-- The roster change being broadcast, projected onto the current roster members in broadcastRoster. This lets the
+-- roster blob be built (and sent) before the change is applied to the owner's own member records, so the owner
+-- never demotes/removes a member locally before the change has been propagated to relays.
+data RosterDelta
+  = RDRoleChanged GroupMemberRole [GroupMember] -- these members now hold this role
+  | RDRemoved [GroupMember] -- these members are removed from the group
+
+applyRosterDelta :: RosterDelta -> [GroupMember] -> [GroupMember]
+applyRosterDelta delta current = case delta of
+  RDRoleChanged role changed -> map (\m -> (m :: GroupMember) {memberRole = role}) changed <> without changed
+  RDRemoved removed -> without removed
+  where
+    without ms = let ids = S.fromList (map groupMemberId' ms) in filter ((`S.notMember` ids) . groupMemberId') current
+
+broadcastRoster :: User -> GroupInfo -> VersionRoster -> RosterDelta -> CM ()
+broadcastRoster user gInfo rosterVer delta = do
   cxt <- chatStoreCxt
   (relays, rosterMems) <- withStore' $ \db ->
     (,) <$> getGroupRelayMembers db cxt user gInfo <*> getGroupRosterMembers db cxt user gInfo
   forM_ (L.nonEmpty relays) $ \relays' ->
-    sendRoster user gInfo (L.toList relays') rosterVer (buildGroupRoster rosterMems)
+    sendRoster user gInfo (L.toList relays') rosterVer (buildGroupRoster $ applyRosterDelta delta rosterMems)
 
 -- Send the current roster (no version bump) to a newly added relay so it can serve joiners.
 sendGroupRosterToRelay :: User -> GroupInfo -> GroupMember -> CM ()