expression: rewrite builtin function: UTC_TIME (#4304)

expression/builtin_time.go

@@ -155,7 +155,8 @@ var (
 	_ builtinFunc = &builtinTimestampAddSig{}
 	_ builtinFunc = &builtinToDaysSig{}
 	_ builtinFunc = &builtinToSecondsSig{}
-	_ builtinFunc = &builtinUTCTimeSig{}
+	_ builtinFunc = &builtinUTCTimeWithArgSig{}
+	_ builtinFunc = &builtinUTCTimeWithoutArgSig{}
 	_ builtinFunc = &builtinTimestampSig{}
 	_ builtinFunc = &builtinLastDaySig{}
 )
@@ -3091,36 +3092,84 @@ type utcTimeFunctionClass struct {
 	baseFunctionClass
 }
 
+func (c *utcTimeFunctionClass) getFlenAndDecimal4UTCTime(sc *variable.StatementContext, args []Expression) (flen, decimal int) {
+	if len(args) == 0 {
+		flen, decimal = 8, 0
+		return
+	}
+	if constant, ok := args[0].(*Constant); ok {
+		fsp, isNull, err := constant.EvalInt(nil, sc)
+		if isNull || err != nil || fsp > int64(types.MaxFsp) {
+			decimal = types.MaxFsp
+		} else if fsp < int64(types.MinFsp) {
+			decimal = types.MinFsp
+		} else {
+			decimal = int(fsp)
+		}
+	}
+	if decimal > 0 {
+		flen = 8 + 1 + decimal
+	} else {
+		flen = 8
+	}
+	return flen, decimal
+}
+
 func (c *utcTimeFunctionClass) getFunction(args []Expression, ctx context.Context) (builtinFunc, error) {
 	if err := c.verifyArgs(args); err != nil {
 		return nil, errors.Trace(err)
 	}
-	sig := &builtinUTCTimeSig{newBaseBuiltinFunc(args, ctx)}
+	argTps := make([]evalTp, 0, 1)
+	if len(args) == 1 {
+		argTps = append(argTps, tpInt)
+	}
+	bf, err := newBaseBuiltinFuncWithTp(args, ctx, tpDuration, argTps...)
+	if err != nil {
+		return nil, errors.Trace(err)
+	}
+	bf.tp.Flen, bf.tp.Decimal = c.getFlenAndDecimal4UTCTime(bf.ctx.GetSessionVars().StmtCtx, args)
+
+	var sig builtinFunc
+	if len(args) == 1 {
+		sig = &builtinUTCTimeWithArgSig{baseDurationBuiltinFunc{bf}}
+	} else {
+		sig = &builtinUTCTimeWithoutArgSig{baseDurationBuiltinFunc{bf}}
+	}
 	return sig.setSelf(sig), nil
 }
 
-type builtinUTCTimeSig struct {
-	baseBuiltinFunc
+type builtinUTCTimeWithoutArgSig struct {
+	baseDurationBuiltinFunc
 }
 
-// eval evals a builtinUTCTimeSig.
+// evalDuration evals a builtinUTCTimeWithoutArgSig.
 // See https://dev.mysql.com/doc/refman/5.7/en/date-and-time-functions.html#function_utc-time
-func (b *builtinUTCTimeSig) eval(row []types.Datum) (d types.Datum, err error) {
-	const utctimeFormat = "15:04:05.000000"
-	args, err := b.evalArgs(row)
-	if err != nil {
-		return d, errors.Trace(err)
+func (b *builtinUTCTimeWithoutArgSig) evalDuration(row []types.Datum) (types.Duration, bool, error) {
+	// the types.ParseDuration here would never fail, so the err returned can be ignored.
+	v, _ := types.ParseDuration(time.Now().UTC().Format("00:00:00"), 0)
+	return v, false, nil
+}
+
+type builtinUTCTimeWithArgSig struct {
+	baseDurationBuiltinFunc
+}
+
+// evalDuration evals a builtinUTCTimeWithArgSig.
+// See https://dev.mysql.com/doc/refman/5.7/en/date-and-time-functions.html#function_utc-time
+func (b *builtinUTCTimeWithArgSig) evalDuration(row []types.Datum) (types.Duration, bool, error) {
+	fsp, isNull, err := b.args[0].EvalInt(row, b.ctx.GetSessionVars().StmtCtx)
+	if isNull || err != nil {
+		return types.Duration{}, isNull, errors.Trace(err)
 	}
-	fsp := 0
-	sc := b.ctx.GetSessionVars().StmtCtx
-	if len(args) == 1 && !args[0].IsNull() {
-		if fsp, err = checkFsp(sc, args[0]); err != nil {
-			d.SetNull()
-			return d, errors.Trace(err)
-		}
+	if fsp > int64(types.MaxFsp) {
+		return types.Duration{}, true, errors.Errorf("Too-big precision %v specified for 'utc_time'. Maximum is %v.", fsp, types.MaxFsp)
 	}
-	d.SetString(time.Now().UTC().Format(utctimeFormat))
-	return convertToDuration(b.ctx.GetSessionVars().StmtCtx, d, fsp)
+	if fsp < int64(types.MinFsp) {
+		return types.Duration{}, true, errors.Errorf("Invalid negative %d specified, must in [0, 6].", fsp)
+	}
+	// the types.ParseDuration here would never fail, so the err returned can be ignored.
+	v, _ := types.ParseDuration(time.Now().UTC().Format("00:00:00.000000"), int(fsp))
+	return v, false, nil
 }
 
 type lastDayFunctionClass struct {

expression/builtin_time_test.go

@@ -1045,18 +1045,19 @@ func (s *testEvaluatorSuite) TestCurrentTime(c *C) {
 func (s *testEvaluatorSuite) TestUTCTime(c *C) {
 	defer testleak.AfterTest(c)()
 
-	tfStr := "15:04:05"
 	last := time.Now().UTC()
+	tfStr := "00:00:00"
 	fc := funcs[ast.UTCTime]
 
 	tests := []struct {
 		param  interface{}
 		expect int
-	}{{nil, 8}, {0, 8}, {3, 12}, {6, 15}, {-1, 0}, {7, 0}}
+	}{{0, 8}, {3, 12}, {6, 15}, {-1, 0}, {7, 0}}
 
 	for _, test := range tests {
 		f, err := fc.getFunction(datumsToConstants(types.MakeDatums(test.param)), s.ctx)
 		c.Assert(err, IsNil)
+		c.Assert(f.isDeterministic(), IsTrue)
 		v, err := f.eval(nil)
 		if test.expect > 0 {
 			c.Assert(err, IsNil)
@@ -1067,6 +1068,14 @@ func (s *testEvaluatorSuite) TestUTCTime(c *C) {
 			c.Assert(err, NotNil)
 		}
 	}
+
+	f, err := fc.getFunction(make([]Expression, 0, 0), s.ctx)
+	c.Assert(err, IsNil)
+	c.Assert(f.isDeterministic(), IsTrue)
+	v, err := f.eval(nil)
+	n := v.GetMysqlDuration()
+	c.Assert(n.String(), HasLen, 8)
+	c.Assert(n.String(), GreaterEqual, last.Format(tfStr))
 }
 
 func (s *testEvaluatorSuite) TestUTCDate(c *C) {

plan/typeinfer_test.go

@@ -1358,6 +1358,16 @@ func (s *testPlanSuite) createTestCase4TimeFuncs() []typeInferTestCase {
 		{"utc_timestamp(6) ", mysql.TypeDatetime, charset.CharsetBin, mysql.BinaryFlag, 26, 6},
 		{"utc_timestamp(7) ", mysql.TypeDatetime, charset.CharsetBin, mysql.BinaryFlag, 26, 6},
 
+		{"utc_time()  ", mysql.TypeDuration, charset.CharsetBin, mysql.BinaryFlag, 8, 0},
+		{"utc_time(0) ", mysql.TypeDuration, charset.CharsetBin, mysql.BinaryFlag, 8, 0},
+		{"utc_time(1) ", mysql.TypeDuration, charset.CharsetBin, mysql.BinaryFlag, 10, 1},
+		{"utc_time(2) ", mysql.TypeDuration, charset.CharsetBin, mysql.BinaryFlag, 11, 2},
+		{"utc_time(3) ", mysql.TypeDuration, charset.CharsetBin, mysql.BinaryFlag, 12, 3},
+		{"utc_time(4) ", mysql.TypeDuration, charset.CharsetBin, mysql.BinaryFlag, 13, 4},
+		{"utc_time(5) ", mysql.TypeDuration, charset.CharsetBin, mysql.BinaryFlag, 14, 5},
+		{"utc_time(6) ", mysql.TypeDuration, charset.CharsetBin, mysql.BinaryFlag, 15, 6},
+		{"utc_time(7) ", mysql.TypeDuration, charset.CharsetBin, mysql.BinaryFlag, 15, 6},
+
 		{"utc_date()  ", mysql.TypeDatetime, charset.CharsetBin, mysql.BinaryFlag, 10, 0},
 		{"curdate()", mysql.TypeDatetime, charset.CharsetBin, mysql.BinaryFlag, 10, 0},
 		{"sysdate(4)", mysql.TypeDatetime, charset.CharsetBin, mysql.BinaryFlag, 19, 0},