93 lines
2.1 KiB
Go
93 lines
2.1 KiB
Go
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// Copyright 2015 PingCAP, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package mysql
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import (
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"math"
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"strconv"
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"strings"
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"github.com/juju/errors"
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)
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const (
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// UnspecifiedFsp is the unspecified fractional seconds part.
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UnspecifiedFsp int = -1
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// MaxFsp is the maximum digit of fractional seconds part.
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MaxFsp int = 6
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// MinFsp is the minimum digit of fractional seconds part.
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MinFsp int = 0
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// DefaultFsp is the default digit of fractional seconds part.
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// MySQL use 0 as the default Fsp.
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DefaultFsp int = 0
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)
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func checkFsp(fsp int) (int, error) {
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if fsp == UnspecifiedFsp {
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return DefaultFsp, nil
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}
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if fsp < MinFsp || fsp > MaxFsp {
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return DefaultFsp, errors.Errorf("Invalid fsp %d", fsp)
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}
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return fsp, nil
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}
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func parseFrac(s string, fsp int) (int, error) {
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if len(s) == 0 {
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return 0, nil
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}
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var err error
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fsp, err = checkFsp(fsp)
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if err != nil {
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return 0, errors.Trace(err)
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}
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// Use float to calculate frac, e.g, "123" -> "0.123"
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if !strings.HasPrefix(s, ".") && !strings.HasPrefix(s, "0.") {
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s = "0." + s
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}
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frac, err := strconv.ParseFloat(s, 64)
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if err != nil {
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return 0, errors.Trace(err)
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}
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// round frac to the nearest value with FSP
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var round float64
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pow := math.Pow(10, float64(fsp))
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digit := pow * frac
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_, div := math.Modf(digit)
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if div >= 0.5 {
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round = math.Ceil(digit)
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} else {
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round = math.Floor(digit)
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}
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// Get the final frac, with 6 digit number
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// 0.1236 round 3 -> 124 -> 123000
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// 0.0312 round 2 -> 3 -> 30000
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return int(round * math.Pow10(MaxFsp-fsp)), nil
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}
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// alignFrac is used to generate alignment frac, like `100` -> `100000`
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func alignFrac(s string, fsp int) string {
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sl := len(s)
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if sl < fsp {
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return s + strings.Repeat("0", fsp-sl)
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}
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return s
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}
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