Limit presence in `/sync` responses (#2394)

* Use filter and limit presence count

* More limiting

* More limiting

* Fix unit test

* Also limit presence by last_active_ts

* Update query, use "from" as the initial lastPos

* Get 1000 presence events, they are filtered later

Co-authored-by: Neil Alexander <neilalexander@users.noreply.github.com>

1 files changed, 6 insertions, 3 deletions

diff --git a/syncapi/storage/postgres/presence_table.go b/syncapi/storage/postgres/presence_table.go
index 9f1e37f7..7194afea 100644
--- a/syncapi/storage/postgres/presence_table.go
+++ b/syncapi/storage/postgres/presence_table.go
@@ -17,6 +17,7 @@ package postgres
 import (
 	"context"
 	"database/sql"
+	"time"
 
 	"github.com/matrix-org/dendrite/internal"
 	"github.com/matrix-org/dendrite/internal/sqlutil"
@@ -72,7 +73,8 @@ const selectMaxPresenceSQL = "" +
 const selectPresenceAfter = "" +
 	" SELECT id, user_id, presence, status_msg, last_active_ts" +
 	" FROM syncapi_presence" +
-	" WHERE id > $1"
+	" WHERE id > $1 AND last_active_ts >= $2" +
+	" ORDER BY id ASC LIMIT $3"
 
 type presenceStatements struct {
 	upsertPresenceStmt         *sql.Stmt
@@ -144,11 +146,12 @@ func (p *presenceStatements) GetMaxPresenceID(ctx context.Context, txn *sql.Tx)
 func (p *presenceStatements) GetPresenceAfter(
 	ctx context.Context, txn *sql.Tx,
 	after types.StreamPosition,
+	filter gomatrixserverlib.EventFilter,
 ) (presences map[string]*types.PresenceInternal, err error) {
 	presences = make(map[string]*types.PresenceInternal)
 	stmt := sqlutil.TxStmt(txn, p.selectPresenceAfterStmt)
-
-	rows, err := stmt.QueryContext(ctx, after)
+	afterTS := gomatrixserverlib.AsTimestamp(time.Now().Add(time.Minute * -5))
+	rows, err := stmt.QueryContext(ctx, after, afterTS, filter.Limit)
 	if err != nil {
 		return nil, err
 	}