56 lines
1.2 KiB
Go
56 lines
1.2 KiB
Go
package snowflake
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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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workerBits uint8 = 10
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numberBits uint8 = 12
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workerMax int64 = -1 ^ (-1 << workerBits)
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numberMax int64 = -1 ^ (-1 << numberBits)
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timeShift uint8 = workerBits + numberBits
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workerShift uint8 = numberBits
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startTime int64 = 1262275200000 // 如果在程序跑了一段时间修改了epoch这个值 可能会导致生成相同的ID (开始时间-毫秒)
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)
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type Worker struct {
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mu sync.Mutex
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timestamp int64
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workerId int64
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number int64
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}
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func NewWorker(workerId int64) (*Worker, error) {
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if workerId < 0 || workerId > workerMax {
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return nil, errors.New("worker id excess of quantity")
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}
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// 生成一个新节点
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return &Worker{
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timestamp: 0,
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workerId: workerId,
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number: 0,
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}, nil
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}
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func (w *Worker) GetId() int64 {
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w.mu.Lock()
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defer w.mu.Unlock()
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now := time.Now().UnixNano() / 1e6
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if w.timestamp == now {
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w.number++
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if w.number > numberMax {
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for now <= w.timestamp {
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now = time.Now().UnixNano() / 1e6
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}
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}
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} else {
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w.number = 0
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w.timestamp = now
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}
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ID := int64((now-startTime)<<timeShift | (w.workerId << workerShift) | (w.number))
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return ID
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}
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