Redis生成分布式系统全局唯一ID

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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：

1. Redis的INCR命令具备了“INCR AND GET”的原子操作
2. 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