From ba7a54254893ee4199b93ee28346bfde47310deb Mon Sep 17 00:00:00 2001
From: Neil Alexander <neilalexander@users.noreply.github.com>
Date: Thu, 17 Mar 2022 12:13:37 +0000
Subject: [PATCH] tweaks

---
 syncapi/routing/messages.go                        | 14 ++++++++++----
 .../postgres/output_room_events_topology_table.go  |  4 ++--
 .../sqlite3/output_room_events_topology_table.go   |  4 ++--
 3 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/syncapi/routing/messages.go b/syncapi/routing/messages.go
index c4224bdd2..36ba3a3e6 100644
--- a/syncapi/routing/messages.go
+++ b/syncapi/routing/messages.go
@@ -48,10 +48,11 @@ type messagesReq struct {
 }
 
 type messagesResp struct {
-	Start string                          `json:"start"`
-	End   string                          `json:"end"`
-	Chunk []gomatrixserverlib.ClientEvent `json:"chunk"`
-	State []gomatrixserverlib.ClientEvent `json:"state"`
+	Start       string                          `json:"start"`
+	StartStream string                          `json:"start_stream,omitempty"` // NOTSPEC: used by Cerulean, so clients can hit /messages then immediately /sync with a latest sync token
+	End         string                          `json:"end"`
+	Chunk       []gomatrixserverlib.ClientEvent `json:"chunk"`
+	State       []gomatrixserverlib.ClientEvent `json:"state"`
 }
 
 // OnIncomingMessagesRequest implements the /messages endpoint from the
@@ -89,6 +90,7 @@ func OnIncomingMessagesRequest(
 
 	// Extract parameters from the request's URL.
 	// Pagination tokens.
+	var fromStream *types.StreamingToken
 	fromQuery := req.URL.Query().Get("from")
 	toQuery := req.URL.Query().Get("to")
 	emptyFromSupplied := fromQuery == ""
@@ -120,6 +122,7 @@ func OnIncomingMessagesRequest(
 				JSON: jsonerror.InvalidArgumentValue("Invalid from parameter: " + err.Error()),
 			}
 		} else {
+			fromStream = &streamToken
 			from, err = db.StreamToTopologicalPosition(req.Context(), roomID, streamToken.PDUPosition, backwardOrdering)
 			if err != nil {
 				logrus.WithError(err).Errorf("Failed to get topological position for streaming token %v", streamToken)
@@ -226,6 +229,9 @@ func OnIncomingMessagesRequest(
 		End:   end.String(),
 		State: state,
 	}
+	if fromStream != nil {
+		res.StartStream = fromStream.String()
+	}
 
 	// Respond with the events.
 	return util.JSONResponse{
diff --git a/syncapi/storage/postgres/output_room_events_topology_table.go b/syncapi/storage/postgres/output_room_events_topology_table.go
index fbeb90e64..cf523d529 100644
--- a/syncapi/storage/postgres/output_room_events_topology_table.go
+++ b/syncapi/storage/postgres/output_room_events_topology_table.go
@@ -50,14 +50,14 @@ const insertEventInTopologySQL = "" +
 const selectEventIDsInRangeASCSQL = "" +
 	"SELECT event_id FROM syncapi_output_room_events_topology" +
 	" WHERE room_id = $1 AND (" +
-	"(topological_position > $2 AND topological_position <= $3) OR" +
+	"(topological_position > $2 AND topological_position < $3) OR" +
 	"(topological_position = $4 AND stream_position <= $5)" +
 	") ORDER BY topological_position ASC, stream_position ASC LIMIT $6"
 
 const selectEventIDsInRangeDESCSQL = "" +
 	"SELECT event_id FROM syncapi_output_room_events_topology" +
 	" WHERE room_id = $1 AND (" +
-	"(topological_position >= $2 AND topological_position < $3) OR" +
+	"(topological_position > $2 AND topological_position < $3) OR" +
 	"(topological_position = $4 AND stream_position <= $5)" +
 	") ORDER BY topological_position DESC, stream_position DESC LIMIT $6"
 
diff --git a/syncapi/storage/sqlite3/output_room_events_topology_table.go b/syncapi/storage/sqlite3/output_room_events_topology_table.go
index c4673786d..08601efba 100644
--- a/syncapi/storage/sqlite3/output_room_events_topology_table.go
+++ b/syncapi/storage/sqlite3/output_room_events_topology_table.go
@@ -46,14 +46,14 @@ const insertEventInTopologySQL = "" +
 const selectEventIDsInRangeASCSQL = "" +
 	"SELECT event_id FROM syncapi_output_room_events_topology" +
 	" WHERE room_id = $1 AND (" +
-	"(topological_position > $2 AND topological_position <= $3) OR" +
+	"(topological_position > $2 AND topological_position < $3) OR" +
 	"(topological_position = $4 AND stream_position <= $5)" +
 	") ORDER BY topological_position ASC, stream_position ASC LIMIT $6"
 
 const selectEventIDsInRangeDESCSQL = "" +
 	"SELECT event_id  FROM syncapi_output_room_events_topology" +
 	" WHERE room_id = $1 AND (" +
-	"(topological_position >= $2 AND topological_position < $3) OR" +
+	"(topological_position > $2 AND topological_position < $3) OR" +
 	"(topological_position = $4 AND stream_position <= $5)" +
 	") ORDER BY topological_position DESC, stream_position DESC LIMIT $6"