Improve logging in buffering (#17294)

Signed-off-by: Manan Gupta <[email protected]>

go/vt/vtgate/buffer/buffer.go

@@ -208,6 +208,7 @@ func (b *Buffer) WaitForFailoverEnd(ctx context.Context, keyspace, shard string,
 }
 
 func (b *Buffer) HandleKeyspaceEvent(ksevent *discovery.KeyspaceEvent) {
+	log.Infof("Keyspace Event received for keyspace %v", ksevent.Keyspace)
 	for _, shard := range ksevent.Shards {
 		sb := b.getOrCreateBuffer(shard.Target.Keyspace, shard.Target.Shard)
 		if sb != nil {

go/vt/vtgate/buffer/shard_buffer.go

@@ -286,7 +286,7 @@ func (sb *shardBuffer) startBufferingLocked(ctx context.Context, kev *discovery.
 		msg = "Dry-run: Would have started buffering"
 	}
 	starts.Add(sb.statsKey, 1)
-	log.Infof("%v for shard: %s (window: %v, size: %v, max failover duration: %v) (A failover was detected by this seen error: %v.)",
+	log.V(2).Infof("%v for shard: %s (window: %v, size: %v, max failover duration: %v) (A failover was detected by this seen error: %v.)",
 		msg,
 		topoproto.KeyspaceShardString(sb.keyspace, sb.shard),
 		sb.buf.config.Window,
@@ -488,7 +488,7 @@ func (sb *shardBuffer) recordKeyspaceEvent(alias *topodatapb.TabletAlias, stillS
 	sb.mu.Lock()
 	defer sb.mu.Unlock()
 
-	log.Infof("disruption in shard %s/%s resolved (serving: %v), movetable state %#v",
+	log.V(2).Infof("disruption in shard %s/%s resolved (serving: %v), movetable state %#v",
 		sb.keyspace, sb.shard, stillServing, keyspaceEvent.MoveTablesState)
 
 	if !topoproto.TabletAliasEqual(alias, sb.currentPrimary) {
@@ -562,7 +562,7 @@ func (sb *shardBuffer) stopBufferingLocked(reason stopReason, details string) {
 	if sb.mode == bufferModeDryRun {
 		msg = "Dry-run: Would have stopped buffering"
 	}
-	log.Infof("%v for shard: %s after: %.1f seconds due to: %v. Draining %d buffered requests now.",
+	log.V(2).Infof("%v for shard: %s after: %.1f seconds due to: %v. Draining %d buffered requests now.",
 		msg, topoproto.KeyspaceShardString(sb.keyspace, sb.shard), d.Seconds(), details, len(q))
 
 	var clientEntryError error
@@ -622,7 +622,7 @@ func (sb *shardBuffer) drain(q []*entry, err error) {
 	wg.Wait()
 
 	d := sb.timeNow().Sub(start)
-	log.Infof("Draining finished for shard: %s Took: %v for: %d requests.", topoproto.KeyspaceShardString(sb.keyspace, sb.shard), d, len(q))
+	log.V(2).Infof("Draining finished for shard: %s Took: %v for: %d requests.", topoproto.KeyspaceShardString(sb.keyspace, sb.shard), d, len(q))
 	requestsDrained.Add(sb.statsKey, int64(len(q)))
 
 	// Draining is done. Change state from "draining" to "idle".