0.0.4

pkg/snowflake/snowflake.go

@@ -0,0 +1,55 @@
+package snowflake
+
+import (
+	"errors"
+	"sync"
+	"time"
+)
+
+const (
+	workerBits  uint8 = 10
+	numberBits  uint8 = 12
+	workerMax   int64 = -1 ^ (-1 << workerBits)
+	numberMax   int64 = -1 ^ (-1 << numberBits)
+	timeShift   uint8 = workerBits + numberBits
+	workerShift uint8 = numberBits
+	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)
+)
+
+type Worker struct {
+	mu        sync.Mutex
+	timestamp int64
+	workerId  int64
+	number    int64
+}
+
+func NewWorker(workerId int64) (*Worker, error) {
+	if workerId < 0 || workerId > workerMax {
+		return nil, errors.New("worker id excess of quantity")
+	}
+	// 生成一个新节点
+	return &Worker{
+		timestamp: 0,
+		workerId:  workerId,
+		number:    0,
+	}, nil
+}
+
+func (w *Worker) GetId() int64 {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+	now := time.Now().UnixNano() / 1e6
+	if w.timestamp == now {
+		w.number++
+		if w.number > numberMax {
+			for now <= w.timestamp {
+				now = time.Now().UnixNano() / 1e6
+			}
+		}
+	} else {
+		w.number = 0
+		w.timestamp = now
+	}
+	ID := int64((now-startTime)<<timeShift | (w.workerId << workerShift) | (w.number))
+	return ID
+}