66 lines
1.7 KiB
Go
66 lines
1.7 KiB
Go
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package common
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import (
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"math/rand"
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"sync/atomic"
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"time"
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)
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// Generator is a snowflake generator.
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// For compatibility with other snowflake implementations, both worker and PID are set,
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// but they are randomized for every generator.
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type IDGenerator struct {
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inc *uint64
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worker, pid uint64
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}
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var defaultGenerator = NewIDGenerator(0, 0)
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// NewIDGenerator creates a new ID generator with the given worker and pid.
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// If worker or pid is empty, it will be set to a random number.
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func NewIDGenerator(worker, pid uint64) *IDGenerator {
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if worker == 0 {
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worker = rand.Uint64()
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}
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if pid == 0 {
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pid = rand.Uint64()
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}
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g := &IDGenerator{
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inc: new(uint64),
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worker: worker % 32,
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pid: pid % 32,
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}
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return g
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}
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// GenerateID generates a new snowflake with the default generator.
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// If you need to customize the worker and PID, manually call (*Generator).Generate.
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func GenerateID() Snowflake {
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return defaultGenerator.Generate()
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}
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// GenerateID generates a new snowflake with the given time with the default generator.
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// If you need to customize the worker and PID, manually call (*Generator).GenerateWithTime.
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func GenerateIDWithTime(t time.Time) Snowflake {
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return defaultGenerator.GenerateWithTime(t)
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}
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// Generate generates a snowflake with the current time.
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func (g *IDGenerator) Generate() Snowflake {
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return g.GenerateWithTime(time.Now())
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}
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// GenerateWithTime generates a snowflake with the given time.
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// To generate a snowflake for comparison, use the top-level New function instead.
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func (g *IDGenerator) GenerateWithTime(t time.Time) Snowflake {
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increment := atomic.AddUint64(g.inc, 1)
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ts := uint64(t.UnixMilli() - Epoch)
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worker := g.worker << 17
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pid := g.pid << 12
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return Snowflake(ts<<22 | worker | pid | (increment % 4096))
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}
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