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Tweak pagination tokens

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This commit is contained in:
Neil Alexander 2021-01-13 11:15:07 +00:00
parent fa65c40bae
commit 12e96ed3ef
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GPG key ID: A02A2019A2BB0944
1 changed files with 25 additions and 29 deletions
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54
syncapi/routing/messages.go
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@ -273,8 +273,24 @@ func (r *messagesReq) retrieveEvents() (
return []gomatrixserverlib.ClientEvent{}, *r.from, *r.to, nil
}
// Get the position of the first and the last event in the room's topology.
// This position is currently determined by the event's depth, so we could
// also use it instead of retrieving from the database. However, if we ever
// change the way topological positions are defined (as depth isn't the most
// reliable way to define it), it would be easier and less troublesome to
// only have to change it in one place, i.e. the database.
start, end, err = r.getStartEnd(events)
// Sort the events to ensure we send them in the right order.
if r.backwardOrdering {
// A stream/topological position is a cursor located between two events.
// While they are identified in the code by the event on their right (if
// we consider a left to right chronological order), tokens need to refer
// to them by the event on their left, therefore we need to decrement the
// end position we send in the response if we're going backward.
start, end = end, start
end.Decrement()
// This reverses the array from old->new to new->old
reversed := func(in []*gomatrixserverlib.HeaderedEvent) []*gomatrixserverlib.HeaderedEvent {
out := make([]*gomatrixserverlib.HeaderedEvent, len(in))
@ -292,14 +308,6 @@ func (r *messagesReq) retrieveEvents() (
// Convert all of the events into client events.
clientEvents = gomatrixserverlib.HeaderedToClientEvents(events, gomatrixserverlib.FormatAll)
// Get the position of the first and the last event in the room's topology.
// This position is currently determined by the event's depth, so we could
// also use it instead of retrieving from the database. However, if we ever
// change the way topological positions are defined (as depth isn't the most
// reliable way to define it), it would be easier and less troublesome to
// only have to change it in one place, i.e. the database.
start, end, err = r.getStartEnd(events)
return clientEvents, start, end, err
}
@ -363,7 +371,7 @@ func (r *messagesReq) filterHistoryVisible(events []*gomatrixserverlib.HeaderedE
return events // apply no filtering as it defaults to Shared.
}
hisVis, _ := hisVisEvent.HistoryVisibility()
if hisVis == "shared" {
if hisVis == "shared" || hisVis == "world_readable" {
return events // apply no filtering
}
if membershipEvent == nil {
@ -387,6 +395,8 @@ func (r *messagesReq) filterHistoryVisible(events []*gomatrixserverlib.HeaderedE
return result
}
// getStartEnd gets the start and end positions of the pagination. It
// assumes that ordering hasn't been reversed yet for backward ordering.
func (r *messagesReq) getStartEnd(events []*gomatrixserverlib.HeaderedEvent) (start, end types.TopologyToken, err error) {
start, err = r.db.EventPositionInTopology(
r.ctx, events[0].EventID(),
@ -395,26 +405,12 @@ func (r *messagesReq) getStartEnd(events []*gomatrixserverlib.HeaderedEvent) (st
err = fmt.Errorf("EventPositionInTopology: for start event %s: %w", events[0].EventID(), err)
return
}
if r.backwardOrdering && events[len(events)-1].Type() == gomatrixserverlib.MRoomCreate {
// We've hit the beginning of the room so there's really nowhere else
// to go. This seems to fix Riot iOS from looping on /messages endlessly.
end = types.TopologyToken{}
} else {
end, err = r.db.EventPositionInTopology(
r.ctx, events[len(events)-1].EventID(),
)
if err != nil {
err = fmt.Errorf("EventPositionInTopology: for end event %s: %w", events[len(events)-1].EventID(), err)
return
}
if r.backwardOrdering {
// A stream/topological position is a cursor located between two events.
// While they are identified in the code by the event on their right (if
// we consider a left to right chronological order), tokens need to refer
// to them by the event on their left, therefore we need to decrement the
// end position we send in the response if we're going backward.
end.Decrement()
}
end, err = r.db.EventPositionInTopology(
r.ctx, events[len(events)-1].EventID(),
)
if err != nil {
err = fmt.Errorf("EventPositionInTopology: for end event %s: %w", events[len(events)-1].EventID(), err)
return
}
return
}