go/uuid
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uuid/util.go

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Change a UUID from []byte to [16]byte along with other API changes.
2016-02-19 22:30:25 +02:00
// Copyright 2016 Google Inc. All rights reserved.
uuid: source re-organization Move source to uuid subdirectory. Add in coderviewability. R=rsc CC=borman http://codereview.appspot.com/4838053
2011-08-09 00:34:29 +03:00
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
Initial checking of the go-uuid code.
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package uuid
import (
"io"
)
// randomBits completely fills slice b with random data.
func randomBits(b []byte) {
if _, err := io.ReadFull(rander, b); err != nil {
go-uuid: Update to Go 1. R=borman CC=borman http://codereview.appspot.com/6255058 Committer: Paul Borman <borman@google.com>
2012-05-30 02:05:31 +03:00
panic(err.Error()) // rand should never fail
Initial checking of the go-uuid code.
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}
}
// xvalues returns the value of a byte as a hexadecimal digit or 255.
use arrays in Parse() for reduced allocation cost and bounds checks An array is also for hex digit value lookups which seemed to reliably give a few ns reduction in time.
2015-10-10 23:00:45 +02:00
var xvalues = [256]byte{
Initial checking of the go-uuid code.
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 255, 255, 255, 255, 255, 255,
255, 10, 11, 12, 13, 14, 15, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 10, 11, 12, 13, 14, 15, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
}
optimize internal parsing function -- avoid unsafe []byte parsing Making xtob take two byte arguments avoids a lot of slicing. This makes the Parse function faster. In addition, because so much slicing is avoiding, duplicating the parse logic to ParseBytes resulted in the function being faster than Parse (<1ns). The BenchmarkParseBytesNative function has been removed (parseBytes was identical to ParseBytes). And a new benchmark, BenchmarkParseBytesUnsafe, has been added to benchmark the old way of parsing []byte (which is slightly slower than Parse and thus the new ParseBytes implementation). benchmark old ns/op new ns/op delta BenchmarkUUID_MarshalJSON-4 685 667 -2.63% BenchmarkUUID_UnmarshalJSON-4 1145 1162 +1.48% BenchmarkParse-4 61.6 56.5 -8.28% BenchmarkParseBytes-4 65.7 55.9 -14.92% BenchmarkParseBytesCopy-4 121 115 -4.96% BenchmarkNew-4 1665 1643 -1.32% BenchmarkUUID_String-4 112 113 +0.89% BenchmarkUUID_URN-4 117 119 +1.71% benchmark old allocs new allocs delta BenchmarkUUID_MarshalJSON-4 4 4 +0.00% BenchmarkUUID_UnmarshalJSON-4 2 2 +0.00% BenchmarkParse-4 0 0 +0.00% BenchmarkParseBytes-4 0 0 +0.00% BenchmarkParseBytesCopy-4 1 1 +0.00% BenchmarkNew-4 1 1 +0.00% BenchmarkUUID_String-4 1 1 +0.00% BenchmarkUUID_URN-4 1 1 +0.00% benchmark old bytes new bytes delta BenchmarkUUID_MarshalJSON-4 248 248 +0.00% BenchmarkUUID_UnmarshalJSON-4 248 248 +0.00% BenchmarkParse-4 0 0 +0.00% BenchmarkParseBytes-4 0 0 +0.00% BenchmarkParseBytesCopy-4 48 48 +0.00% BenchmarkNew-4 16 16 +0.00% BenchmarkUUID_String-4 48 48 +0.00% BenchmarkUUID_URN-4 48 48 +0.00%
2016-02-26 07:36:20 +02:00
// xtob converts hex characters x1 and x2 into a byte.
func xtob(x1, x2 byte) (byte, bool) {
b1 := xvalues[x1]
b2 := xvalues[x2]
Initial checking of the go-uuid code.
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return (b1 << 4) | b2, b1 != 255 && b2 != 255
}
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