66 lines
1.2 KiB
Go
66 lines
1.2 KiB
Go
package util
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import (
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"errors"
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"sync"
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"time"
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)
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const (
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// MaxSequence max sequence in one time
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MaxSequence = 1000
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// WorkerBit worker bit
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WorkerBit = 10
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// SequenceBit sequence bit
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SequenceBit = 10
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)
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// SnowFlake snow flake
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type SnowFlake struct {
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sync.Mutex
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lastTimestamp int64
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sequence int64
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workerID int64
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}
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// NewSnowFlake new
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func NewSnowFlake() *SnowFlake {
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return &SnowFlake{
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workerID: time.Now().UnixNano() % 1000,
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}
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}
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// Generate generate
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func (s *SnowFlake) Generate() (int64, error) {
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s.Lock()
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defer s.Unlock()
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now := time.Now().UnixNano() / 1e6
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if now == s.lastTimestamp {
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s.sequence = (s.sequence + 1) % MaxSequence
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if s.sequence == 0 {
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now = s.waitNextMill(now)
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}
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} else {
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s.sequence = 0
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}
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if now < s.lastTimestamp {
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return 0, errors.New("inner time error")
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}
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s.lastTimestamp = now
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return s.generate() % 1000000000, nil
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}
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func (s *SnowFlake) generate() int64 {
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return (s.lastTimestamp << (WorkerBit + SequenceBit)) | (s.workerID << SequenceBit) | s.sequence
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}
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func (s *SnowFlake) waitNextMill(t int64) int64 {
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for t == s.lastTimestamp {
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time.Sleep(100 * time.Microsecond)
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t = time.Now().UnixNano() / 1e6
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}
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return t
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}
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