Redis生成分布式系统全局唯一ID的实现

分布式系统全局唯一id

在互联网系统中，并发越大的系统，数据就越大，数据越大就越需要分布式，而大量的分布式数据就越需要唯一标识来识别它们。

例如淘宝的商品系统有千亿级别商品，订单系统有万亿级别的订单数据，这些数据都是日渐增长，传统的单库单表是无法支撑这种级别的数据，必须对其进行分库分表；一旦分库分表，表的自增id就失去了意义；故需要一个全局唯一的id来标识每一条数据（商品、订单）。

e.g: 一张表1亿条数据，被分库分表10张表，原先的id就失去意义，所以需要全局唯一id来标识10张表的数据。

全局唯一的id生成的技术方案有很多，业界比较有名的有 uuid、redis、twitter的snowflake算法、美团leaf算法。

基于redis incr 命令生成分布式全局唯一id

incr 命令主要有以下2个特征：

• redis的incr命令具备了“incr and get”的原子操作
• redis是单进程单线程架构，incr命令不会出现id重复

基于以上2个特性，可以采用incr命令来实现分布式全局id生成。

采用redis生成商品全局唯一id

project directory

maven dependency

<?xml version="1.0" encoding="utf-8"?>
<project xmlns="http://maven.apache.org/pom/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/xmlschema-instance"
         xsi:schemalocation="http://maven.apache.org/pom/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <groupid>org.springframework.boot</groupid>
        <artifactid>spring-boot-starter-parent</artifactid>
        <version>2.2.8.release</version>
        <relativepath/>
    </parent>

    <modelversion>4.0.0</modelversion>

    <groupid>org.fool.redis</groupid>
    <artifactid>redis-string-id</artifactid>
    <version>1.0-snapshot</version>

    <dependencies>
        <dependency>
            <groupid>org.springframework.boot</groupid>
            <artifactid>spring-boot-starter-web</artifactid>
        </dependency>

        <dependency>
            <groupid>org.springframework.boot</groupid>
            <artifactid>spring-boot-starter-test</artifactid>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupid>org.springframework.boot</groupid>
            <artifactid>spring-boot-starter-data-redis</artifactid>
        </dependency>

        <dependency>
            <groupid>org.projectlombok</groupid>
            <artifactid>lombok</artifactid>
            <version>1.18.12</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupid>org.springframework.boot</groupid>
                <artifactid>spring-boot-maven-plugin</artifactid>
            </plugin>
        </plugins>
    </build>
</project>

application.properties

spring.application.name=redis-spring-id
server.port=8888

spring.redis.host=localhost
spring.redis.port=6379
spring.redis.database=0
spring.redis.password=
spring.redis.timeout=2000
spring.redis.pool.max-active=10
spring.redis.pool.max-wait=1000
spring.redis.pool.max-idle=10
spring.redis.pool.min-idle=5
spring.redis.pool.num-tests-per-eviction-run=1024
spring.redis.pool.time-between-eviction-runs-millis=30000
spring.redis.pool.min-evictable-idle-time-millis=60000
spring.redis.pool.soft-min-evictable-idle-time-millis=10000
spring.redis.pool.test-on-borrow=true
spring.redis.pool.test-while-idle=true
spring.redis.pool.block-when-exhausted=false

src

application.java

package org.fool.redis;

import org.springframework.boot.springapplication;
import org.springframework.boot.autoconfigure.springbootapplication;

@springbootapplication
public class application {
    public static void main(string[] args) {
        springapplication.run(application.class, args);
    }
}

product.java

package org.fool.redis.model;

import lombok.data;

import java.math.bigdecimal;

@data
public class product {
    private long id;
    private string name;
    private bigdecimal price;
    private string detail;
}

idgeneratorservice.java

package org.fool.redis.service;

import org.springframework.beans.factory.annotation.autowired;
import org.springframework.data.redis.core.stringredistemplate;
import org.springframework.stereotype.service;

@service
public class idgeneratorservice {
    @autowired
    private stringredistemplate stringredistemplate;

    private static final string id_key = "id:generator:product";

    public long incrementid() {
        return stringredistemplate.opsforvalue().increment(id_key);
    }
}

productcontroller.java

package org.fool.redis.controller;

import lombok.extern.slf4j.slf4j;
import org.fool.redis.model.product;
import org.fool.redis.service.idgeneratorservice;
import org.springframework.beans.factory.annotation.autowired;
import org.springframework.web.bind.annotation.postmapping;
import org.springframework.web.bind.annotation.requestbody;
import org.springframework.web.bind.annotation.requestmapping;
import org.springframework.web.bind.annotation.restcontroller;

@restcontroller
@slf4j
@requestmapping(value = "/product")
public class productcontroller {
    @autowired
    private idgeneratorservice idgeneratorservice;

    @postmapping(value = "/create")
    public string create(@requestbody product obj) {
        //生成分布式id
        long id = idgeneratorservice.incrementid();

        //使用全局id 代替数据库的自增id
        obj.setid(id);

        //取模(e.g: 这里分为8张表，海量数据可以分为1024张表)，计算表名
        int table = (int) id % 8;
        string tablename = "product_" + table;

        log.info("insert to table: {}, with content: {}", tablename, obj);

        return "insert to table: " + tablename + " with content: " + obj;
    }
}

test

curl --location --request post 'http://localhost:8888/product/create' \
--header 'content-type: application/json' \
--data-raw '{
    "name": "car",
    "price": "300000.00",
    "detail": "lexus style"
}'

console output

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