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45 lines
1.2 KiB
45 lines
1.2 KiB
5 years ago
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// Copyright 2016 Google Inc. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package uuid
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import (
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"encoding/binary"
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)
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// NewUUID returns a Version 1 UUID based on the current NodeID and clock
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// sequence, and the current time. If the NodeID has not been set by SetNodeID
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// or SetNodeInterface then it will be set automatically. If the NodeID cannot
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// be set NewUUID returns nil. If clock sequence has not been set by
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// SetClockSequence then it will be set automatically. If GetTime fails to
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// return the current NewUUID returns nil and an error.
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//
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// In most cases, New should be used.
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func NewUUID() (UUID, error) {
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nodeMu.Lock()
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if nodeID == zeroID {
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setNodeInterface("")
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}
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nodeMu.Unlock()
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var uuid UUID
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now, seq, err := GetTime()
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if err != nil {
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return uuid, err
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}
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timeLow := uint32(now & 0xffffffff)
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timeMid := uint16((now >> 32) & 0xffff)
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timeHi := uint16((now >> 48) & 0x0fff)
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timeHi |= 0x1000 // Version 1
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binary.BigEndian.PutUint32(uuid[0:], timeLow)
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binary.BigEndian.PutUint16(uuid[4:], timeMid)
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binary.BigEndian.PutUint16(uuid[6:], timeHi)
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binary.BigEndian.PutUint16(uuid[8:], seq)
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copy(uuid[10:], nodeID[:])
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return uuid, nil
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}
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