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utils: performance improvement for parseDateTime #1117

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utils: performance improvement for parseDateTime #1117

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67 changes: 60 additions & 7 deletions utils.go
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Expand Up @@ -107,20 +107,73 @@ func readBool(input string) (value bool, valid bool) {
******************************************************************************/

func parseDateTime(str string, loc *time.Location) (t time.Time, err error) {
base := "0000-00-00 00:00:00.0000000"
var (
year, month, day, hour, min, sec, nsec int
)
switch len(str) {
case 10, 19, 21, 22, 23, 24, 25, 26: // up to "YYYY-MM-DD HH:MM:SS.MMMMMM"
if str == base[:len(str)] {
default:
err = fmt.Errorf("invalid time string: %s", str)
return
case 10:
if str == "0000-00-00" {
return
}
goto parseFromDate
case 19:
if str == "0000-00-00 00:00:00" {
return
}
if loc == time.UTC {
return time.Parse(timeFormat[:len(str)], str)
goto parseFromClock
case 21, 22, 23, 24, 25, 26:
if str == "0000-00-00 00:00:00.000000"[:len(str)] {
return
}
return time.ParseInLocation(timeFormat[:len(str)], str, loc)
default:
}
if nsec, err = strconv.Atoi(str[20:] + "0000-00-00 00:00:00.000000"[len(str):]); err != nil {
err = fmt.Errorf("invalid time string: %s", str)
return
}
nsec *= 1000
if str[19] != '.' {
err = fmt.Errorf("invalid time string: %s", str)
return
}
parseFromClock:
if sec, err = strconv.Atoi(str[17:19]); err != nil {
err = fmt.Errorf("invalid time string: %s", str)
return
}
if min, err = strconv.Atoi(str[14:16]); err != nil {
err = fmt.Errorf("invalid time string: %s", str)
return
}
if hour, err = strconv.Atoi(str[11:13]); err != nil {
err = fmt.Errorf("invalid time string: %s", str)
return
}
if str[16] != ':' || str[13] != ':' || str[10] != ' ' {
err = fmt.Errorf("invalid time string: %s", str)
return
}
parseFromDate:
if day, err = strconv.Atoi(str[8:10]); err != nil {
err = fmt.Errorf("invalid time string: %s", str)
return
}
if month, err = strconv.Atoi(str[5:7]); err != nil {
err = fmt.Errorf("invalid time string: %s", str)
return
}
if year, err = strconv.Atoi(str[:4]); err != nil {
err = fmt.Errorf("invalid time string: %s", str)
return
}
if str[7] != '-' || str[4] != '-' {
err = fmt.Errorf("invalid time string: %s", str)
return
}

return time.Date(year, time.Month(month), day, hour, min, sec, nsec, loc), nil
}

func parseBinaryDateTime(num uint64, data []byte, loc *time.Location) (driver.Value, error) {
Expand Down