vtctl: WaitForFilteredReplication: Remove special handling for tolera…

…ted negative delays.

A negative delay should never be sent back by the tablet. It always sends a minimum value of 0.

go/vt/vtctl/vtctl.go

@@ -1335,8 +1335,6 @@ func commandShardReplicationFix(ctx context.Context, wr *wrangler.Wrangler, subF
 }
 
 func commandWaitForFilteredReplication(ctx context.Context, wr *wrangler.Wrangler, subFlags *flag.FlagSet, args []string) error {
-	// Allowed tolerance up to which the local clock may run ahead. Otherwise, the command will fail.
-	const allowedAheadTime = 2 * time.Second
 	maxDelay := subFlags.Duration("max_delay", 30*time.Second,
 		"Specifies the maximum delay, in seconds, the filtered replication of the"+
 			" given destination shard should lag behind the source shard. When"+
@@ -1403,8 +1401,8 @@ func commandWaitForFilteredReplication(ctx context.Context, wr *wrangler.Wrangle
 
 			delaySecs := shr.RealtimeStats.SecondsBehindMasterFilteredReplication
 			lastSeenDelay := time.Duration(delaySecs) * time.Second
-			if lastSeenDelay < -allowedAheadTime {
-				return fmt.Errorf("cannot reliably wait for the filtered replication to catch up. The tablet clock (runs ahead) is not synchronized. seen delay: %v on tablet: %v", lastSeenDelay, alias)
+			if lastSeenDelay < 0 {
+				return fmt.Errorf("last seen delay should never be negative. tablet: %v delay: %v", alias, lastSeenDelay)
 			}
 			if lastSeenDelay <= *maxDelay {
 				wr.Logger().Printf("Filtered replication on tablet: %v has caught up. Last seen delay: %.1f seconds\n", alias, lastSeenDelay.Seconds())

go/vt/wrangler/testlib/wait_for_filtered_replication_test.go

@@ -52,47 +52,6 @@ func TestWaitForFilteredReplication_wrongTarget(t *testing.T) {
 	waitForFilteredReplicationDefaultDelay(t, target, "received health record for wrong tablet")
 }
 
-// TestWaitForFilteredReplication_unsyncClocks tests that
-// vtctl WaitForFilteredReplication fails if the calculated delay is negative.
-func TestWaitForFilteredReplication_unsyncClocks(t *testing.T) {
-	target := &pbq.Target{Keyspace: keyspace, Shard: destShard, TabletType: pbt.TabletType_MASTER}
-
-	// Replication is lagging behind.
-	oneHourDelay := &pbq.RealtimeStats{
-		SecondsBehindMasterFilteredReplication: 3600,
-	}
-
-	// Receiving master's clock is running one hour ahead of the sending master.
-	negativeDelayFunc := func() *pbq.RealtimeStats {
-		return &pbq.RealtimeStats{
-			SecondsBehindMasterFilteredReplication: -3600,
-		}
-	}
-
-	waitForFilteredReplication(t, target, "cannot reliably wait for the filtered replication to catch up", oneHourDelay, negativeDelayFunc)
-}
-
-// TestWaitForFilteredReplication_unsyncClocksTolerance tests that
-// vtctl WaitForFilteredReplication succeeds as long as the calculated
-// negative delay is above a certain tolerance.
-func TestWaitForFilteredReplication_unsyncClocksTolerance(t *testing.T) {
-	target := &pbq.Target{Keyspace: keyspace, Shard: destShard, TabletType: pbt.TabletType_MASTER}
-
-	// Replication is lagging behind.
-	oneHourDelay := &pbq.RealtimeStats{
-		SecondsBehindMasterFilteredReplication: 3600,
-	}
-
-	// Tablet is a second ahead of the local clock.
-	slightNegativeDelayFunc := func() *pbq.RealtimeStats {
-		return &pbq.RealtimeStats{
-			SecondsBehindMasterFilteredReplication: -1,
-		}
-	}
-
-	waitForFilteredReplication(t, target, "", oneHourDelay, slightNegativeDelayFunc)
-}
-
 func waitForFilteredReplicationDefaultDelay(t *testing.T, target *pbq.Target, expectedErr string) {
 	// Replication is lagging behind.
 	oneHourDelay := &pbq.RealtimeStats{