rocketmq-go/model/message/message_client_id_generator.go

/*
Licensed to the Apache Software Foundation (ASF) under one or more
contributor license agreements.  See the NOTICE file distributed with
this work for additional information regarding copyright ownership.
The ASF licenses this file to You 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 message

import (
	"bytes"
	"encoding/binary"
	"github.com/apache/incubator-rocketmq-externals/rocketmq-go/util"
	"os"
	"strconv"
	"strings"
	"sync"
	"time"
)

var (
	counter       int16
	startTime     int64
	nextStartTime int64
	idPrefix      string
	lock          sync.Mutex
)

//MessageClientId = ip  + pid + classloaderid + counter + time
//4 bytes for ip ,
//2 bytes for pid,
//4 bytes for  classloaderid(for java,go put 0)

//2 bytes for counter,
//4 bytes for timediff, //(time.Now().UnixNano() - startTime) / 1000000) divide 1000000 because use time millis
func generatorMessageClientId() (uniqMessageId string) {
	defer lock.Unlock()
	lock.Lock()
	if len(idPrefix) == 0 {
		idPrefix = generatorMessageClientIdPrefix()
	}
	if time.Now().UnixNano() > nextStartTime {
		startTime, nextStartTime = getStartAndNextStartTime()
	}
	counter = counter + 1
	var buf2 = bytes.NewBuffer([]byte{})
	binary.Write(buf2, binary.BigEndian, int32((time.Now().UnixNano()-startTime)/1000000))
	binary.Write(buf2, binary.BigEndian, counter)
	uniqMessageId = idPrefix + bytes2string(buf2.Bytes())
	return
}

//GeneratorMessageOffsetId generator message offsetId
func GeneratorMessageOffsetId(storeHost []byte, port int32, commitOffset int64) (messageOffsetId string) {
	var buf = bytes.NewBuffer([]byte{})
	binary.Write(buf, binary.BigEndian, storeHost)
	binary.Write(buf, binary.BigEndian, port)
	binary.Write(buf, binary.BigEndian, commitOffset)
	idPrefix := buf.Bytes()
	messageOffsetId = bytes2string(idPrefix)
	return
}
func generatorMessageClientIdPrefix() (messageClientIdPrefix string) {
	var (
		idPrefix      []byte
		ip4Bytes      []byte
		pid           int16
		classloaderId int32 = -1 // golang don't have this
	)
	ip4Bytes = util.GetIp4Bytes()
	pid = int16(os.Getpid())
	var buf = bytes.NewBuffer([]byte{})
	binary.Write(buf, binary.BigEndian, ip4Bytes)
	binary.Write(buf, binary.BigEndian, pid)
	binary.Write(buf, binary.BigEndian, classloaderId)
	idPrefix = buf.Bytes()
	messageClientIdPrefix = bytes2string(idPrefix)
	return
}
func getStartAndNextStartTime() (thisMonthFirstDay12 int64, nextMonthFirstDay12 int64) {
	now := time.Now()
	year := now.Year()
	month := now.Month()
	thisMonthFirstDay12 = time.Date(year, month, 1, 0, 0, 0, 0, time.Local).UnixNano()
	month = month + 1
	if month > 12 {
		month = month - 12
		year = year + 1
	}
	nextMonthFirstDay12 = time.Date(year, month, 1, 0, 0, 0, 0, time.Local).UnixNano()
	return
}
func bytes2string(bytes []byte) (ret string) {
	for _, oneByte := range bytes {
		hexStr := strconv.FormatInt(int64(oneByte), 16)
		if len(hexStr) < 2 {
			hexStr = "0" + hexStr
		}
		ret = ret + hexStr
	}
	ret = strings.ToUpper(ret)
	return
}