feat: implement snowflake algorithm

components/sequencer/snowflake/sequencer_snowflake.go

@@ -0,0 +1,116 @@
+//
+// Copyright 2021 Layotto Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package snowflake
+
+import (
+	"fmt"
+	"math/rand"
+	"sync"
+	"time"
+
+	"mosn.io/pkg/log"
+)
+
+var (
+	machineRoomIdBits   = 5                                                      // 机房id 五位数
+	machineIdBits       = 5                                                      // 机器id
+	sequencerBits       = 12                                                     // 每毫秒产生的id数量
+	maxMachineRoomIdBit = int64(^(-1 << machineRoomIdBits))                      // 当前机房id最大值
+	maxMachineIdBit     = int64(^(-1 << machineIdBits))                          // 当前机器id最大值
+	moveMachineRoomBit  = sequencerBits + machineIdBits                          // 机房的左移动位
+	moveMachineBit      = sequencerBits                                          // 机器的左移动位
+	moveTimeStart       = sequencerBits + machineIdBits + machineRoomIdBits      // 时间戳的左移动位
+	maxSequencerIdBit   = ^(-1 << sequencerBits)                                 // id 最大值
+	machineRoomId       int64                                                    // 机房id
+	machineId           int64                                                    // 机器id
+	currentAQS                                                              = 0  // 并发控制
+	lastTimestamp       int64                                               = -1 //上次id产生的时间，防止时间回拨
+	once                sync.Once
+	instance            *Singleton
+	lock                sync.Mutex
+	logger              log.Logger
+)
+
+const (
+	timeStart = 1655540588 // 系统开始时间
+)
+
+type Singleton struct {
+}
+
+const (
+	IP_PATTERN = "\\d{1,3}(\\.\\d{1,3}){3,5}$" //ip pattern
+)
+
+// GetInstanceWM 获取singleton对象 单例模式
+func GetInstanceWM(machine, machineRoom int64) *Singleton {
+	if machine > maxMachineIdBit || machine < 0 {
+		logger.Fatalf("the max lengths of the machine ID exceeds the maxMachineIdBit, maxMachineIdBit: %d ", maxMachineIdBit)
+		return nil
+	}
+	if machineRoom > maxMachineRoomIdBit || machineRoom < 0 {
+		logger.Fatalf("the max lengths of the machine room ID exceeds the maxMachineRoomIdBit, maxMachineIdBit: %d ", maxMachineIdBit)
+		return nil
+	}
+	once.Do(func() {
+		instance = &Singleton{}
+	})
+	machineId = machine
+	machineRoomId = machineRoom
+	return instance
+}
+
+func (s *Singleton) NextID() (int64, error) {
+	lock.Lock()
+	defer lock.Unlock()
+	timestamp := time.Now().Unix() // 这儿注意下，golang是否有效率问题
+	if timestamp < lastTimestamp {
+		descTime := lastTimestamp - timestamp
+		if descTime < 5 {
+			// wait
+			time.Sleep(time.Duration(descTime<<1) * time.Millisecond)
+			timestamp = time.Now().Unix()
+			if timestamp < lastTimestamp {
+				return -1, fmt.Errorf("time moved backwards, refusing to generate id for %d milliseconds", descTime)
+			}
+		} else {
+			return -1, fmt.Errorf("time moved backwards, refusing to generate id for %d milliseconds", descTime)
+		}
+	}
+	if lastTimestamp == timestamp {
+		// 在同一毫秒内
+		currentAQS = (currentAQS + 1) & maxSequencerIdBit
+		if currentAQS == 0 {
+			timestamp = tilNextMillis(lastTimestamp)
+		}
+	} else {
+		currentAQS = rand.Intn(2) + 1
+	}
+	lastTimestamp = timestamp
+	nowTime := (timestamp - timeStart) << moveTimeStart
+	machineRoom := machineRoomId << moveMachineRoomBit
+	machine := machineId << moveMachineBit
+	return nowTime | machineRoom | machine, nil
+}
+
+func tilNextMillis(lastTimestamp int64) int64 {
+	timestamp := time.Now().Unix()
+	for {
+		if timestamp <= lastTimestamp {
+			break
+		}
+		timestamp = time.Now().Unix()
+	}
+	return timestamp
+}

components/sequencer/snowflake/sequencer_snowflake_test.go

@@ -0,0 +1,38 @@
+//
+// Copyright 2021 Layotto Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package snowflake
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestGetInstanceWM(t *testing.T) {
+	machine := int64(1)
+	machineRoom := int64(1)
+	s := GetInstanceWM(machine, machineRoom)
+	assert.NotNil(t, s)
+}
+
+func TestSingleton_NextID(t *testing.T) {
+	s := GetInstanceWM(10, 10)
+	id, err := s.NextID()
+	if err != nil {
+		t.Errorf("error: %v", err)
+	}
+	logger.Printf("id : %d", id)
+	assert.NotNil(t, id)
+
+}