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Tweak getStartEnd again

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Neil Alexander 2021-01-13 11:26:42 +00:00
parent c71174b059
commit 78125bf304
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GPG key ID: A02A2019A2BB0944
1 changed files with 18 additions and 13 deletions
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23
syncapi/routing/messages.go
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@ -283,13 +283,6 @@ func (r *messagesReq) retrieveEvents() (
// Sort the events to ensure we send them in the right order. // Sort the events to ensure we send them in the right order.
if r.backwardOrdering { 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()
// This reverses the array from old->new to new->old // This reverses the array from old->new to new->old
reversed := func(in []*gomatrixserverlib.HeaderedEvent) []*gomatrixserverlib.HeaderedEvent { reversed := func(in []*gomatrixserverlib.HeaderedEvent) []*gomatrixserverlib.HeaderedEvent {
out := make([]*gomatrixserverlib.HeaderedEvent, len(in)) out := make([]*gomatrixserverlib.HeaderedEvent, len(in))
@ -394,13 +387,25 @@ func (r *messagesReq) filterHistoryVisible(events []*gomatrixserverlib.HeaderedE
return result 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) { func (r *messagesReq) getStartEnd(events []*gomatrixserverlib.HeaderedEvent) (start, end types.TopologyToken, err error) {
if r.backwardOrdering {
start = *r.from
end, err = r.db.EventPositionInTopology(
r.ctx, events[0].EventID(),
)
// 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()
} else {
start = *r.from start = *r.from
end, err = r.db.EventPositionInTopology( end, err = r.db.EventPositionInTopology(
r.ctx, events[len(events)-1].EventID(), r.ctx, events[len(events)-1].EventID(),
) )
}
if err != nil { if err != nil {
err = fmt.Errorf("EventPositionInTopology: for end event %s: %w", events[len(events)-1].EventID(), err) err = fmt.Errorf("EventPositionInTopology: for end event %s: %w", events[len(events)-1].EventID(), err)
return return