76 lines
1.2 KiB
Go
76 lines
1.2 KiB
Go
package idgen
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import (
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"crypto/rand"
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"fmt"
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"sync"
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"time"
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)
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var (
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generator *FlakeIDGenerator
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once sync.Once
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)
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type FlakeIDGenerator struct {
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mu sync.Mutex
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lastTs int64
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seq int64
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nodeID int64
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}
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func NewFlakeIDGenerator(nodeID int64) *FlakeIDGenerator {
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return &FlakeIDGenerator{
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nodeID: nodeID,
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}
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}
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func (g *FlakeIDGenerator) GetID() (string, error) {
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g.mu.Lock()
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defer g.mu.Unlock()
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now := time.Now().UnixNano() / 1e6
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if now < g.lastTs {
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return "", fmt.Errorf("clock moved backwards")
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}
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if now == g.lastTs {
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g.seq++
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if g.seq >= 1024 {
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for now <= g.lastTs {
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now = time.Now().UnixNano() / 1e6
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}
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g.seq = 0
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}
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} else {
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g.seq = 0
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}
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g.lastTs = now
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id := (now << 22) | (g.nodeID << 10) | g.seq
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return fmt.Sprintf("%d", id), nil
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}
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func GetID() (string, error) {
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once.Do(func() {
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nodeID := int64(1)
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b := make([]byte, 2)
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_, err := rand.Read(b)
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if err == nil {
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nodeID = int64(b[0])<<8 | int64(b[1])
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nodeID &= 0x3FF
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}
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generator = NewFlakeIDGenerator(nodeID)
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})
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return generator.GetID()
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}
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func MustGetID() string {
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id, err := GetID()
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if err != nil {
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return fmt.Sprintf("%d", time.Now().UnixNano())
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}
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return id
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} |