refactor project structure

cluster/idgenerator/snowflake.go

@@ -0,0 +1,85 @@
+package idgenerator
+
+import (
+	"hash/fnv"
+	"log"
+	"sync"
+	"time"
+)
+
+const (
+	workerIdBits     int64 = 5
+	datacenterIdBits int64 = 5
+	sequenceBits     int64 = 12
+
+	maxWorkerId     int64 = -1 ^ (-1 << uint64(workerIdBits))
+	maxDatacenterId int64 = -1 ^ (-1 << uint64(datacenterIdBits))
+	maxSequence     int64 = -1 ^ (-1 << uint64(sequenceBits))
+
+	timeLeft uint8 = 22
+	dataLeft uint8 = 17
+	workLeft uint8 = 12
+
+	twepoch int64 = 1525705533000
+)
+
+type IdGenerator struct {
+	mu           *sync.Mutex
+	lastStamp    int64
+	workerId     int64
+	dataCenterId int64
+	sequence     int64
+}
+
+func MakeGenerator(cluster string, node string) *IdGenerator {
+	fnv64 := fnv.New64()
+	_, _ = fnv64.Write([]byte(cluster))
+	dataCenterId := int64(fnv64.Sum64())
+
+	fnv64.Reset()
+	_, _ = fnv64.Write([]byte(node))
+	workerId := int64(fnv64.Sum64())
+
+	return &IdGenerator{
+		mu:           &sync.Mutex{},
+		lastStamp:    -1,
+		dataCenterId: dataCenterId,
+		workerId:     workerId,
+		sequence:     1,
+	}
+}
+
+func (w *IdGenerator) getCurrentTime() int64 {
+	return time.Now().UnixNano() / 1e6
+}
+
+func (w *IdGenerator) NextId() int64 {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+
+	timestamp := w.getCurrentTime()
+	if timestamp < w.lastStamp {
+		log.Fatal("can not generate id")
+	}
+	if w.lastStamp == timestamp {
+		w.sequence = (w.sequence + 1) & maxSequence
+		if w.sequence == 0 {
+			for timestamp <= w.lastStamp {
+				timestamp = w.getCurrentTime()
+			}
+		}
+	} else {
+		w.sequence = 0
+	}
+	w.lastStamp = timestamp
+
+	return ((timestamp - twepoch) << timeLeft) | (w.dataCenterId << dataLeft) | (w.workerId << workLeft) | w.sequence
+}
+
+func (w *IdGenerator) tilNextMillis() int64 {
+	timestamp := w.getCurrentTime()
+	if timestamp <= w.lastStamp {
+		timestamp = w.getCurrentTime()
+	}
+	return timestamp
+}