11960: Get the full list of old IDs up front in sendOldEvents.

This avoids keeping the "get list of log IDs" database query open
while each log row gets looked up, queued, permission-checked,
serialized, and sent over the wire to the client.

Arvados-DCO-1.1-Signed-off-by: Tom Clegg <tom@curoverse.com>

diff --git a/services/ws/session_v0.go b/services/ws/session_v0.go
index db60738bdb68e5812cb09f25501b43f0fd6b1402..58c64231cb53c1204ceed70b0ea030a7050ebb95 100644 (file)
--- a/services/ws/session_v0.go
+++ b/services/ws/session_v0.go
@@ -162,7 +162,7 @@ func (sub *v0subscribe) sendOldEvents(sess *v0session) {
        if sub.LastLogID == 0 {
                return
        }
-       sess.log.WithField("LastLogID", sub.LastLogID).Debug("getOldEvents")
+       sess.log.WithField("LastLogID", sub.LastLogID).Debug("sendOldEvents")
        // Here we do a "select id" query and queue an event for every
        // log since the given ID, then use (*event)Detail() to
        // retrieve the whole row and decide whether to send it. This
@@ -177,17 +177,26 @@ func (sub *v0subscribe) sendOldEvents(sess *v0session) {
                sub.LastLogID,
                time.Now().UTC().Add(-10*time.Minute).Format(time.RFC3339Nano))
        if err != nil {
-               sess.log.WithError(err).Error("db.Query failed")
+               sess.log.WithError(err).Error("sendOldEvents db.Query failed")
                return
        }
-       defer rows.Close()
+
+       var ids []uint64
        for rows.Next() {
                var id uint64
                err := rows.Scan(&id)
                if err != nil {
-                       sess.log.WithError(err).Error("row Scan failed")
+                       sess.log.WithError(err).Error("sendOldEvents row Scan failed")
                        continue
                }
+               ids = append(ids, id)
+       }
+       if err := rows.Err(); err != nil {
+               sess.log.WithError(err).Error("sendOldEvents db.Query failed")
+       }
+       rows.Close()
+
+       for _, id := range ids {
                for len(sess.sendq)*2 > cap(sess.sendq) {
                        // Ugly... but if we fill up the whole client
                        // queue with a backlog of old events, a
@@ -212,9 +221,6 @@ func (sub *v0subscribe) sendOldEvents(sess *v0session) {
                        }
                }
        }
-       if err := rows.Err(); err != nil {
-               sess.log.WithError(err).Error("db.Query failed")
-       }
 }
 
 type v0subscribe struct {