stats: fix converting duration to timestamp (pingcap#8174) (pingcap#8184

)

statistics/gc.go

@@ -25,13 +25,18 @@ import (
 	"golang.org/x/net/context"
 )
 
+// DurationToTS converts duration to timestamp.
+func DurationToTS(d time.Duration) uint64 {
+	return oracle.ComposeTS(d.Nanoseconds()/int64(time.Millisecond), 0)
+}
+
 // GCStats will garbage collect the useless stats info. For dropped tables, we will first update their version so that
 // other tidb could know that table is deleted.
 func (h *Handle) GCStats(is infoschema.InfoSchema, ddlLease time.Duration) error {
 	// To make sure that all the deleted tables' schema and stats info have been acknowledged to all tidb,
 	// we only garbage collect version before 10 lease.
 	lease := mathutil.MaxInt64(int64(h.Lease), int64(ddlLease))
-	offset := oracle.ComposeTS(10*lease, 0)
+	offset := DurationToTS(10 * time.Duration(lease))
 	if h.PrevLastVersion < offset {
 		return nil
 	}

statistics/handle_test.go

@@ -26,6 +26,7 @@ import (
 	"github.com/pingcap/tidb/sessionctx/stmtctx"
 	"github.com/pingcap/tidb/statistics"
 	"github.com/pingcap/tidb/store/mockstore"
+	"github.com/pingcap/tidb/store/tikv/oracle"
 	"github.com/pingcap/tidb/types"
 	"github.com/pingcap/tidb/util/testkit"
 	"github.com/pingcap/tidb/util/testleak"
@@ -235,6 +236,14 @@ func (s *testStatsCacheSuite) TestAvgColLen(c *C) {
 	c.Assert(statsTbl.Columns[tableInfo.Columns[3].ID].AvgColSize(statsTbl.Count), Equals, 16.0)
 }
 
+func (s *testStatsCacheSuite) TestDurationToTS(c *C) {
+	tests := []time.Duration{time.Millisecond, time.Second, time.Minute, time.Hour}
+	for _, t := range tests {
+		ts := statistics.DurationToTS(t)
+		c.Assert(oracle.ExtractPhysical(ts)*int64(time.Millisecond), Equals, int64(t))
+	}
+}
+
 func (s *testStatsCacheSuite) TestVersion(c *C) {
 	defer cleanEnv(c, s.store, s.do)
 	testKit := testkit.NewTestKit(c, s.store)