Split forward backfilling and do it in one batch

Multiple batches is complicated, as it would require figuring out where
the batch ended when handling the next batch of new-old messages.

historysync.go

@@ -128,12 +128,12 @@ func (user *User) handleBackfillRequestsLoop(backfillRequests chan *database.Bac
 				portal.Update()
 			}
 
-			user.createOrUpdatePortalAndBackfillWithLock(req, conv, portal)
+			user.backfillInChunks(req, conv, portal)
 		}
 	}
 }
 
-func (user *User) createOrUpdatePortalAndBackfillWithLock(req *database.Backfill, conv *database.HistorySyncConversation, portal *Portal) {
+func (user *User) backfillInChunks(req *database.Backfill, conv *database.HistorySyncConversation, portal *Portal) {
 	portal.backfillLock.Lock()
 	defer portal.backfillLock.Unlock()
 
@@ -141,6 +141,22 @@ func (user *User) createOrUpdatePortalAndBackfillWithLock(req *database.Backfill
 		return
 	}
 
+	var forwardPrevID id.EventID
+	if req.BackfillType == database.BackfillForward {
+		// TODO this overrides the TimeStart set when enqueuing the backfill
+		//      maybe the enqueue should instead include the prev event ID
+		lastMessage := portal.bridge.DB.Message.GetLastInChat(portal.Key)
+		forwardPrevID = lastMessage.MXID
+		start := lastMessage.Timestamp.Add(1 * time.Second)
+		req.TimeStart = &start
+	} else {
+		firstMessage := portal.bridge.DB.Message.GetFirstInChat(portal.Key)
+		if firstMessage != nil && (req.TimeEnd == nil || firstMessage.Timestamp.Before(*req.TimeEnd)) {
+			end := firstMessage.Timestamp.Add(-1 * time.Second)
+			req.TimeEnd = &end
+			user.log.Debugfln("Limiting backfill to end at %v", end)
+		}
+	}
 	allMsgs := user.bridge.DB.HistorySyncQuery.GetMessagesBetween(user.MXID, conv.ConversationID, req.TimeStart, req.TimeEnd, req.MaxTotalEvents)
 	if len(allMsgs) == 0 {
 		user.log.Debugfln("Not backfilling %s: no bridgeable messages found", portal.Key.JID)
@@ -161,7 +177,7 @@ func (user *User) createOrUpdatePortalAndBackfillWithLock(req *database.Backfill
 	var insertionEventIds []id.EventID
 	for len(toBackfill) > 0 {
 		var msgs []*waProto.WebMessageInfo
-		if len(toBackfill) <= req.MaxBatchEvents {
+		if len(toBackfill) <= req.MaxBatchEvents || req.MaxBatchEvents < 0 {
 			msgs = toBackfill
 			toBackfill = nil
 		} else {
@@ -172,7 +188,10 @@ func (user *User) createOrUpdatePortalAndBackfillWithLock(req *database.Backfill
 		if len(msgs) > 0 {
 			time.Sleep(time.Duration(req.BatchDelay) * time.Second)
 			user.log.Debugfln("Backfilling %d messages in %s (queue ID: %d)", len(msgs), portal.Key.JID, req.QueueID)
-			insertionEventIds = append(insertionEventIds, portal.backfill(user, msgs)...)
+			resp := portal.backfill(user, msgs, req.BackfillType == database.BackfillForward, forwardPrevID)
+			if resp != nil {
+				insertionEventIds = append(insertionEventIds, resp.BaseInsertionEventID)
+			}
 		}
 	}
 	user.log.Debugfln("Finished backfilling %d messages in %s (queue ID: %d)", len(allMsgs), portal.Key.JID, req.QueueID)
@@ -297,6 +316,7 @@ func (user *User) handleHistorySync(reCheckQueue chan bool, evt *waProto.History
 				// Enqueue immediate backfills for the most recent messages first.
 				user.EnqueueImmedateBackfills(portals)
 			case waProto.HistorySync_FULL, waProto.HistorySync_RECENT:
+				user.EnqueueForwardBackfills(portals)
 				// Enqueue deferred backfills as configured.
 				user.EnqueueDeferredBackfills(portals)
 				user.EnqueueMediaBackfills(portals)
@@ -340,6 +360,18 @@ func (user *User) EnqueueDeferredBackfills(portals []*Portal) {
 	}
 }
 
+func (user *User) EnqueueForwardBackfills(portals []*Portal) {
+	for priority, portal := range portals {
+		lastMsg := user.bridge.DB.Message.GetLastInChat(portal.Key)
+		if lastMsg == nil {
+			continue
+		}
+		backfill := user.bridge.DB.BackfillQuery.NewWithValues(
+			user.MXID, database.BackfillForward, priority, &portal.Key, &lastMsg.Timestamp, nil, -1, -1, 0)
+		backfill.Insert()
+	}
+}
+
 func (user *User) EnqueueMediaBackfills(portals []*Portal) {
 	numPortals := len(portals)
 	for stageIdx, backfillStage := range user.bridge.Config.Bridge.HistorySync.Media {
@@ -367,16 +399,26 @@ var (
 	HistorySyncMarker     = event.Type{Type: "org.matrix.msc2716.marker", Class: event.MessageEventType}
 )
 
-func (portal *Portal) backfill(source *User, messages []*waProto.WebMessageInfo) []id.EventID {
-	var historyBatch, newBatch mautrix.ReqBatchSend
-	var historyBatchInfos, newBatchInfos []*wrappedInfo
+func (portal *Portal) backfill(source *User, messages []*waProto.WebMessageInfo, isForward bool, prevEventID id.EventID) *mautrix.RespBatchSend {
+	var req mautrix.ReqBatchSend
+	var infos []*wrappedInfo
 
-	firstMsgTimestamp := time.Unix(int64(messages[len(messages)-1].GetMessageTimestamp()), 0)
+	if !isForward {
+		if portal.FirstEventID != "" || portal.NextBatchID != "" {
+			req.PrevEventID = portal.FirstEventID
+			req.BatchID = portal.NextBatchID
+		} else {
+			portal.log.Warnfln("Can't backfill %d messages through %s to chat: first event ID not known", len(messages), source.MXID)
+			return nil
+		}
+	} else {
+		req.PrevEventID = prevEventID
+	}
 
-	historyBatch.StateEventsAtStart = make([]*event.Event, 0)
-	newBatch.StateEventsAtStart = make([]*event.Event, 0)
+	beforeFirstMessageTimestampMillis := (int64(messages[len(messages)-1].GetMessageTimestamp()) * 1000) - 1
+	req.StateEventsAtStart = make([]*event.Event, 0)
 
-	addedMembers := make(map[id.UserID]*event.MemberEventContent)
+	addedMembers := make(map[id.UserID]struct{})
 	addMember := func(puppet *Puppet) {
 		if _, alreadyAdded := addedMembers[puppet.MXID]; alreadyAdded {
 			return
@@ -389,41 +431,23 @@ func (portal *Portal) backfill(source *User, messages []*waProto.WebMessageInfo)
 		}
 		inviteContent := content
 		inviteContent.Membership = event.MembershipInvite
-		historyBatch.StateEventsAtStart = append(historyBatch.StateEventsAtStart, &event.Event{
+		req.StateEventsAtStart = append(req.StateEventsAtStart, &event.Event{
 			Type:      event.StateMember,
 			Sender:    portal.MainIntent().UserID,
 			StateKey:  &mxid,
-			Timestamp: firstMsgTimestamp.UnixMilli(),
+			Timestamp: beforeFirstMessageTimestampMillis,
 			Content:   event.Content{Parsed: &inviteContent},
 		}, &event.Event{
 			Type:      event.StateMember,
 			Sender:    puppet.MXID,
 			StateKey:  &mxid,
-			Timestamp: firstMsgTimestamp.UnixMilli(),
+			Timestamp: beforeFirstMessageTimestampMillis,
 			Content:   event.Content{Parsed: &content},
 		})
-		addedMembers[puppet.MXID] = &content
-	}
-
-	firstMessage := portal.bridge.DB.Message.GetFirstInChat(portal.Key)
-	lastMessage := portal.bridge.DB.Message.GetLastInChat(portal.Key)
-	var historyMaxTs, newMinTs time.Time
-
-	if portal.FirstEventID != "" || portal.NextBatchID != "" {
-		historyBatch.PrevEventID = portal.FirstEventID
-		historyBatch.BatchID = portal.NextBatchID
-		if firstMessage == nil && lastMessage == nil {
-			historyMaxTs = time.Now()
-		} else {
-			historyMaxTs = firstMessage.Timestamp
-		}
-	}
-	if lastMessage != nil {
-		newBatch.PrevEventID = lastMessage.MXID
-		newMinTs = lastMessage.Timestamp
+		addedMembers[puppet.MXID] = struct{}{}
 	}
 
-	portal.log.Debugfln("Processing backfill with %d messages", len(messages))
+	portal.log.Infofln("Processing history sync with %d messages (forward: %t)", len(messages), isForward)
 	// The messages are ordered newest to oldest, so iterate them in reverse order.
 	for i := len(messages) - 1; i >= 0; i-- {
 		webMsg := messages[i]
@@ -446,15 +470,6 @@ func (portal *Portal) backfill(source *User, messages []*waProto.WebMessageInfo)
 		if info == nil {
 			continue
 		}
-		var batch *mautrix.ReqBatchSend
-		var infos *[]*wrappedInfo
-		if !historyMaxTs.IsZero() && info.Timestamp.Before(historyMaxTs) {
-			batch, infos = &historyBatch, &historyBatchInfos
-		} else if !newMinTs.IsZero() && info.Timestamp.After(newMinTs) {
-			batch, infos = &newBatch, &newBatchInfos
-		} else {
-			continue
-		}
 		if webMsg.GetPushName() != "" && webMsg.GetPushName() != "-" {
 			existingContact, _ := source.Client.Store.Contacts.GetContact(info.Sender)
 			if !existingContact.Found || existingContact.PushName == "" {
@@ -484,13 +499,18 @@ func (portal *Portal) backfill(source *User, messages []*waProto.WebMessageInfo)
 		if len(converted.ReplyTo) > 0 {
 			portal.SetReply(converted.Content, converted.ReplyTo)
 		}
-		err := portal.appendBatchEvents(converted, info, webMsg.GetEphemeralStartTimestamp(), &batch.Events, infos)
+		err := portal.appendBatchEvents(converted, info, webMsg.GetEphemeralStartTimestamp(), &req.Events, &infos)
 		if err != nil {
 			portal.log.Errorfln("Error handling message %s during backfill: %v", info.ID, err)
 		}
 	}
+	portal.log.Infofln("Made %d Matrix events from messages in batch", len(req.Events))
+
+	if len(req.Events) == 0 {
+		return nil
+	}
 
-	if (len(historyBatch.Events) > 0 && len(historyBatch.BatchID) == 0) || len(newBatch.Events) > 0 {
+	if len(req.BatchID) == 0 || isForward {
 		portal.log.Debugln("Sending a dummy event to avoid forward extremity errors with backfill")
 		_, err := portal.MainIntent().SendMessageEvent(portal.MXID, PreBackfillDummyEvent, struct{}{})
 		if err != nil {
@@ -498,33 +518,16 @@ func (portal *Portal) backfill(source *User, messages []*waProto.WebMessageInfo)
 		}
 	}
 
-	var insertionEventIds []id.EventID
-
-	if len(historyBatch.Events) > 0 && len(historyBatch.PrevEventID) > 0 {
-		portal.log.Infofln("Sending %d historical messages...", len(historyBatch.Events))
-		historyResp, err := portal.MainIntent().BatchSend(portal.MXID, &historyBatch)
-		if err != nil {
-			portal.log.Errorln("Error sending batch of historical messages:", err)
-		} else {
-			insertionEventIds = append(insertionEventIds, historyResp.BaseInsertionEventID)
-			portal.finishBatch(historyResp.EventIDs, historyBatchInfos)
-			portal.NextBatchID = historyResp.NextBatchID
-			portal.Update()
-		}
-	}
-
-	if len(newBatch.Events) > 0 && len(newBatch.PrevEventID) > 0 {
-		portal.log.Infofln("Sending %d new messages...", len(newBatch.Events))
-		newResp, err := portal.MainIntent().BatchSend(portal.MXID, &newBatch)
-		if err != nil {
-			portal.log.Errorln("Error sending batch of new messages:", err)
-		} else {
-			insertionEventIds = append(insertionEventIds, newResp.BaseInsertionEventID)
-			portal.finishBatch(newResp.EventIDs, newBatchInfos)
-		}
+	resp, err := portal.MainIntent().BatchSend(portal.MXID, &req)
+	if err != nil {
+		portal.log.Errorln("Error batch sending messages:", err)
+		return nil
+	} else {
+		portal.finishBatch(resp.EventIDs, infos)
+		portal.NextBatchID = resp.NextBatchID
+		portal.Update()
+		return resp
 	}
-
-	return insertionEventIds
 }
 
 func (portal *Portal) parseWebMessageInfo(source *User, webMsg *waProto.WebMessageInfo) *types.MessageInfo {