chore: Refactor code quality issues (pingcap#23445)

cmd/importer/db.go

@@ -303,7 +303,7 @@ func genColumnData(table *table, column *column) (string, error) {
 }
 
 func execSQL(db *sql.DB, sql string) error {
-	if len(sql) == 0 {
+	if sql == "" {
 		return nil
 	}
 

cmd/importer/parser.go

@@ -291,7 +291,7 @@ func parseIndex(table *table, stmt *ast.CreateIndexStmt) error {
 }
 
 func parseIndexSQL(table *table, sql string) error {
-	if len(sql) == 0 {
+	if sql == "" {
 		return nil
 	}
 

cmd/importer/rand.go

@@ -72,7 +72,7 @@ func randDate(col *column) string {
 	}
 
 	min, max := col.min, col.max
-	if len(min) == 0 {
+	if min == "" {
 		year := time.Now().Year()
 		month := randInt(1, 12)
 		day := randInt(1, 28)
@@ -83,7 +83,7 @@ func randDate(col *column) string {
 	if err != nil {
 		log.Warn("parse min date failed", zap.Error(err))
 	}
-	if len(max) == 0 {
+	if max == "" {
 		t := minTime.Add(time.Duration(randInt(0, 365)) * 24 * time.Hour)
 		return fmt.Sprintf("%04d-%02d-%02d", t.Year(), t.Month(), t.Day())
 	}
@@ -102,7 +102,7 @@ func randTime(col *column) string {
 		return col.hist.randDate("SECOND", "%H:%i:%s", timeFormat)
 	}
 	min, max := col.min, col.max
-	if len(min) == 0 || len(max) == 0 {
+	if min == "" || max == "" {
 		hour := randInt(0, 23)
 		min := randInt(0, 59)
 		sec := randInt(0, 59)
@@ -127,7 +127,7 @@ func randTimestamp(col *column) string {
 		return col.hist.randDate("SECOND", "%Y-%m-%d %H:%i:%s", dateTimeFormat)
 	}
 	min, max := col.min, col.max
-	if len(min) == 0 {
+	if min == "" {
 		year := time.Now().Year()
 		month := randInt(1, 12)
 		day := randInt(1, 28)
@@ -141,7 +141,7 @@ func randTimestamp(col *column) string {
 	if err != nil {
 		log.Warn("parse min timestamp failed", zap.Error(err))
 	}
-	if len(max) == 0 {
+	if max == "" {
 		t := minTime.Add(time.Duration(randInt(0, 365)) * 24 * time.Hour)
 		return fmt.Sprintf("%04d-%02d-%02d %02d:%02d:%02d", t.Year(), t.Month(), t.Day(), t.Hour(), t.Minute(), t.Second())
 	}
@@ -160,7 +160,7 @@ func randYear(col *column) string {
 		return col.hist.randDate("YEAR", "%Y", yearFormat)
 	}
 	min, max := col.min, col.max
-	if len(min) == 0 || len(max) == 0 {
+	if min == "" || max == "" {
 		return fmt.Sprintf("%04d", time.Now().Year()-randInt(0, 10))
 	}
 

executor/hash_table_test.go

@@ -120,9 +120,7 @@ func (h hashCollision) Size() int                         { panic("not implement
 func (h hashCollision) BlockSize() int                    { panic("not implemented") }
 
 func (s *pkgTestSerialSuite) TestHashRowContainer(c *C) {
-	hashFunc := func() hash.Hash64 {
-		return fnv.New64()
-	}
+	hashFunc := fnv.New64
 	rowContainer := s.testHashRowContainer(c, hashFunc, false)
 	c.Assert(rowContainer.stat.probeCollision, Equals, 0)
 	// On windows time.Now() is imprecise, the elapse time may equal 0

executor/trace.go

@@ -171,7 +171,7 @@ func drainRecordSet(ctx context.Context, sctx sessionctx.Context, rs sqlexec.Rec
 
 func dfsTree(t *appdash.Trace, prefix string, isLast bool, chk *chunk.Chunk) {
 	var newPrefix, suffix string
-	if len(prefix) == 0 {
+	if prefix == "" {
 		newPrefix = prefix + "  "
 	} else {
 		if !isLast {

expression/builtin_miscellaneous.go

@@ -574,7 +574,7 @@ func (b *builtinInet6AtonSig) evalString(row chunk.Row) (string, bool, error) {
 		copy(result, ip.To4())
 	}
 
-	return string(result[:]), false, nil
+	return string(result), false, nil
 }
 
 type inet6NtoaFunctionClass struct {

expression/builtin_time_test.go

@@ -826,7 +826,7 @@ func (s *testEvaluatorSuite) TestNowAndUTCTimestamp(c *C) {
 		fc  functionClass
 		now func() time.Time
 	}{
-		{funcs[ast.Now], func() time.Time { return time.Now() }},
+		{funcs[ast.Now], time.Now},
 		{funcs[ast.UTCTimestamp], func() time.Time { return time.Now().UTC() }},
 	} {
 		f, err := x.fc.getFunction(s.ctx, s.datumsToConstants(nil))

owner/manager.go

@@ -127,7 +127,7 @@ var ManagerSessionTTL = 60
 // setManagerSessionTTL sets the ManagerSessionTTL value, it's used for testing.
 func setManagerSessionTTL() error {
 	ttlStr := os.Getenv("tidb_manager_ttl")
-	if len(ttlStr) == 0 {
+	if ttlStr == "" {
 		return nil
 	}
 	ttl, err := strconv.Atoi(ttlStr)

types/time.go

@@ -2248,7 +2248,7 @@ func parseSingleTimeValue(unit string, format string, strictCheck bool) (int64,
 				return 0, 0, 0, 0, ErrWrongValue.GenWithStackByArgs(DateTimeStr, format)
 			}
 		} else {
-			if dv, err = strconv.ParseInt(dvPre[:]+"000000"[:6-dvPreLen], 10, 64); err != nil {
+			if dv, err = strconv.ParseInt(dvPre+"000000"[:6-dvPreLen], 10, 64); err != nil {
 				return 0, 0, 0, 0, ErrWrongValue.GenWithStackByArgs(DateTimeStr, format)
 			}
 		}