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Merge pull request #92 from pingcap/qiuyesuifeng/decimal-type-index-s…
…upport Add decimal type codec support.
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@@ -868,5 +868,4 @@ func didPanic(f func()) bool { | |
| }() | ||
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| return ret | ||
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| } | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,189 @@ | ||
| // Copyright 2015 PingCAP, Inc. | ||
| // | ||
| // Licensed under the Apache License, Version 2.0 (the "License"); | ||
| // you may not use this file except in compliance with the License. | ||
| // You may obtain a copy of the License at | ||
| // | ||
| // http://www.apache.org/licenses/LICENSE-2.0 | ||
| // | ||
| // Unless required by applicable law or agreed to in writing, software | ||
| // distributed under the License is distributed on an "AS IS" BASIS, | ||
| // See the License for the specific language governing permissions and | ||
| // limitations under the License. | ||
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| package codec | ||
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| import ( | ||
| "bytes" | ||
| "math/big" | ||
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| "github.com/juju/errors" | ||
| mysql "github.com/pingcap/tidb/mysqldef" | ||
| ) | ||
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| const ( | ||
| negativeSign int64 = 8 | ||
| zeroSign int64 = 16 | ||
| positiveSign int64 = 24 | ||
| ) | ||
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| func codecSign(value int64) int64 { | ||
| if value < 0 { | ||
| return negativeSign | ||
| } | ||
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| return positiveSign | ||
| } | ||
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| func encodeExp(expValue int64, expSign int64, valSign int64) int64 { | ||
| if expSign == negativeSign { | ||
| expValue = -expValue | ||
| } | ||
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| if expSign != valSign { | ||
| expValue = ^expValue | ||
| } | ||
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| return expValue | ||
| } | ||
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| func decodeExp(expValue int64, expSign int64, valSign int64) int64 { | ||
| if expSign != valSign { | ||
| expValue = ^expValue | ||
| } | ||
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| if expSign == negativeSign { | ||
| expValue = -expValue | ||
| } | ||
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| return expValue | ||
| } | ||
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| func codecValue(value []byte, valSign int64) { | ||
| if valSign == negativeSign { | ||
| reverseBytes(value) | ||
| } | ||
| } | ||
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| // EncodeDecimal encodes a decimal d into a byte slice which can be sorted lexicographically later. | ||
| // EncodeDecimal guarantees that the encoded value is in ascending order for comparison. | ||
| // Decimal encoding: | ||
| // EncodeInt -> value sign | ||
| // EncodeInt -> exp sign | ||
| // EncodeInt -> exp value | ||
| // EncodeBytes -> abs value bytes | ||
| func EncodeDecimal(b []byte, d mysql.Decimal) []byte { | ||
| if d.Equals(mysql.ZeroDecimal) { | ||
| return EncodeInt(b, zeroSign) | ||
| } | ||
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| v := d.BigIntValue() | ||
| valSign := codecSign(int64(v.Sign())) | ||
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| absVal := new(big.Int) | ||
| absVal.Abs(v) | ||
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| value := []byte(absVal.String()) | ||
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| // Trim right side "0", like "12.34000" -> "12.34" or "0.1234000" -> "0.1234". | ||
| if d.Exponent() != 0 { | ||
| value = bytes.TrimRight(value, "0") | ||
| } | ||
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| // Get exp and value, format is "value":"exp". | ||
| // like "12.34" -> "0.1234":"2". | ||
| // like "-0.01234" -> "-0.1234":"-1". | ||
| exp := int64(0) | ||
| div := big.NewInt(10) | ||
| for ; ; exp++ { | ||
| if absVal.Sign() == 0 { | ||
| break | ||
| } | ||
| absVal = absVal.Div(absVal, div) | ||
| } | ||
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| expVal := exp + int64(d.Exponent()) | ||
| expSign := codecSign(expVal) | ||
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| // For negtive exp, do bit reverse for exp. | ||
| // For negtive decimal, do bit reverse for exp and value. | ||
| expVal = encodeExp(expVal, expSign, valSign) | ||
| codecValue(value, valSign) | ||
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| r := EncodeInt(b, valSign) | ||
| r = EncodeInt(r, expSign) | ||
| r = EncodeInt(r, expVal) | ||
| r = EncodeBytes(r, value) | ||
| return r | ||
| } | ||
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| // DecodeDecimal decodes bytes to decimal. | ||
| // DecodeFloat decodes a float from a byte slice | ||
| // Decimal decoding: | ||
| // DecodeInt -> value sign | ||
| // DecodeInt -> exp sign | ||
| // DecodeInt -> exp value | ||
| // DecodeBytes -> abs value bytes | ||
| func DecodeDecimal(b []byte) ([]byte, mysql.Decimal, error) { | ||
| var ( | ||
| r []byte | ||
| d mysql.Decimal | ||
| err error | ||
| ) | ||
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| // Decode value sign. | ||
| valSign := zeroSign | ||
| r, valSign, err = DecodeInt(b) | ||
| if err != nil { | ||
| return r, d, errors.Trace(err) | ||
| } | ||
| if valSign == zeroSign { | ||
| d, err = mysql.ParseDecimal("0") | ||
| return r, d, errors.Trace(err) | ||
| } | ||
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| // Decode exp sign. | ||
| expSign := zeroSign | ||
| r, expSign, err = DecodeInt(r) | ||
| if err != nil { | ||
| return r, d, errors.Trace(err) | ||
| } | ||
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| // Decode exp value. | ||
| expVal := int64(0) | ||
| r, expVal, err = DecodeInt(r) | ||
| if err != nil { | ||
| return r, d, errors.Trace(err) | ||
| } | ||
| expVal = decodeExp(expVal, expSign, valSign) | ||
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| // Decode abs value bytes. | ||
| value := []byte{} | ||
| r, value, err = DecodeBytes(r) | ||
| if err != nil { | ||
| return r, d, errors.Trace(err) | ||
| } | ||
| codecValue(value, valSign) | ||
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| // Generate decimal string value. | ||
| var decimalStr []byte | ||
| if valSign == negativeSign { | ||
| decimalStr = append(decimalStr, '-') | ||
| } | ||
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| if expVal <= 0 { | ||
| // Like decimal "0.1234" or "0.01234". | ||
| decimalStr = append(decimalStr, '0') | ||
| decimalStr = append(decimalStr, '.') | ||
| decimalStr = append(decimalStr, bytes.Repeat([]byte{'0'}, -int(expVal))...) | ||
| decimalStr = append(decimalStr, value...) | ||
| } else { | ||
| // Like decimal "12.34". | ||
| decimalStr = append(decimalStr, value[:expVal]...) | ||
| decimalStr = append(decimalStr, '.') | ||
| decimalStr = append(decimalStr, value[expVal:]...) | ||
| } | ||
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| d, err = mysql.ParseDecimal(string(decimalStr)) | ||
| return r, d, errors.Trace(err) | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,52 @@ | ||
| // Copyright 2015 PingCAP, Inc. | ||
| // | ||
| // Licensed under the Apache License, Version 2.0 (the "License"); | ||
| // you may not use this file except in compliance with the License. | ||
| // You may obtain a copy of the License at | ||
| // | ||
| // http://www.apache.org/licenses/LICENSE-2.0 | ||
| // | ||
| // Unless required by applicable law or agreed to in writing, software | ||
| // distributed under the License is distributed on an "AS IS" BASIS, | ||
| // See the License for the specific language governing permissions and | ||
| // limitations under the License. | ||
|
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| package codec | ||
|
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| import ( | ||
| . "github.com/pingcap/check" | ||
| mysql "github.com/pingcap/tidb/mysqldef" | ||
| ) | ||
|
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| var _ = Suite(&testDecimalSuite{}) | ||
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| type testDecimalSuite struct { | ||
| } | ||
|
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| func (s *testDecimalSuite) TestDecimalCodec(c *C) { | ||
| inputs := []struct { | ||
| Input float64 | ||
| }{ | ||
| {float64(123400)}, | ||
| {float64(1234)}, | ||
| {float64(12.34)}, | ||
| {float64(0.1234)}, | ||
| {float64(0.01234)}, | ||
| {float64(-0.1234)}, | ||
| {float64(-0.01234)}, | ||
| {float64(12.3400)}, | ||
| {float64(-12.34)}, | ||
| {float64(0.00000)}, | ||
| {float64(0)}, | ||
| {float64(-0.0)}, | ||
| {float64(-0.000)}, | ||
| } | ||
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| for _, input := range inputs { | ||
| v := mysql.NewDecimalFromFloat(input.Input) | ||
| b := EncodeDecimal([]byte{}, v) | ||
| _, d, err := DecodeDecimal(b) | ||
| c.Assert(err, IsNil) | ||
| c.Assert(v.Equals(d), IsTrue) | ||
| } | ||
| } |