首次提交：初始化项目代码

pkg/idgen/idgen.go

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