Initial Golang version

internal/generator/generator.go

@@ -0,0 +1,64 @@
+package generator
+
+import (
+	"errors"
+	"time"
+)
+
+var EPOCH_TIME time.Time = time.Unix(0, 1609459200000*int64(time.Millisecond))
+var TIME_MASK uint64 = 0x1FFFFFFFFFF
+
+var tooManyRequests = errors.New("Too many requests in the current ms")
+var incorrectSystemTime = errors.New("The current time is less than the last generated time! Check the system time.")
+
+type Generator struct {
+	LastGeneratedTime   time.Duration
+	Counter             uint64
+	LastCounterRollover time.Duration
+	WorkerID            uint64
+}
+
+func (g *Generator) GenerateSnowflake() (uint64, error) {
+	time := time.Since(EPOCH_TIME)
+	if time < g.LastGeneratedTime {
+		return 0, incorrectSystemTime
+	}
+	if g.Counter == 4095 {
+		if g.LastCounterRollover >= time {
+			return 0, tooManyRequests
+		}
+		g.LastCounterRollover = time
+		g.Counter = 0
+	} else {
+		g.Counter += 1
+	}
+	g.LastGeneratedTime = time
+	return (((uint64(time.Milliseconds()) & TIME_MASK) << 22) + g.WorkerID + g.Counter), nil
+}
+
+func CreateGenerator(workerID uint64) (*Generator, error) {
+	if workerID <= 0 {
+		return nil, errors.New("Worker ID must be greater than 0")
+	}
+	return &Generator{
+		LastGeneratedTime:   time.Since(EPOCH_TIME),
+		Counter:             0,
+		LastCounterRollover: time.Since(EPOCH_TIME),
+		WorkerID:            workerID,
+	}, nil
+}
+
+func (g *Generator) Run(request chan chan uint64) {
+	for output := range request {
+		id, err := g.GenerateSnowflake()
+		if err != nil {
+			if err == tooManyRequests {
+				time.Sleep(time.Millisecond)
+				continue
+			} else if err == incorrectSystemTime {
+				panic("System time is incorrect")
+			}
+		}
+		output <- id
+	}
+}