SETNX key value

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.4.0</version>
    <relativePath/> <!-- lookup parent from repository -->
  </parent>
  <groupId>cn.miao.redis</groupId>
  <artifactId>springboot-caffeine-demo</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <name>springboot-redis-lock-demo</name>
  <description>Demo project for Redis Distribute Lock</description>

  <properties>
    <java.version>1.8</java.version>
  </properties>

  <dependencies>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter</artifactId>
    </dependency>

    <!--redis-->
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-data-redis</artifactId>
      <version>2.1.4.RELEASE</version>
    </dependency>

    <!--springMvc-->
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
      <version>2.3.3.RELEASE</version>
    </dependency>

    <!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
    <dependency>
      <groupId>org.projectlombok</groupId>
      <artifactId>lombok</artifactId>
      <version>1.18.12</version>
      <scope>provided</scope>
    </dependency>

    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-test</artifactId>
      <scope>test</scope>
    </dependency>
  </dependencies>

  <build>
    <plugins>
      <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
      </plugin>
    </plugins>
  </build>

</project>

import lombok.extern.slf4j.Slf4j;
import org.springframework.data.redis.connection.RedisStringCommands;
import org.springframework.data.redis.connection.ReturnType;
import org.springframework.data.redis.core.RedisCallback;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.types.Expiration;

import java.nio.charset.StandardCharsets;

/**
 * @author miao
 * redis 加鎖工具類(lèi)
 */
@Slf4j
public class RedisDistributedLock {

  /**
   * 超時(shí)時(shí)間
   */
  private static final long TIMEOUT_MILLIS = 15000;

  /**
   * 重試次數(shù)
   */
  private static final int RETRY_TIMES = 10;

  /***
   * 睡眠時(shí)間
   */
  private static final long SLEEP_MILLIS = 500;

  /**
   * 用來(lái)加鎖的lua腳本
   * 因?yàn)樾掳娴膔edis加鎖操作已經(jīng)為原子性操作
   * 所以放棄使用lua腳本
   */
  private static final String LOCK_LUA =
      "if redis.call(\"setnx\",KEYS[1],ARGV[1]) == 1 " +
          "then " +
          "  return redis.call('expire',KEYS[1],ARGV[2]) " +
          "else " +
          "  return 0 " +
          "end";

  /**
   * 用來(lái)釋放分布式鎖的lua腳本
   * 如果redis.get(KEYS[1]) == ARGV[1],則redis delete KEYS[1]
   * 否則返回0
   * KEYS[1] , ARGV[1] 是參數(shù)，我們只調(diào)用的時(shí)候 傳遞這兩個(gè)參數(shù)就可以了
   * KEYS[1] 主要用來(lái)傳遞在redis 中用作key值的參數(shù)
   * ARGV[1] 主要用來(lái)傳遞在redis中用做 value值的參數(shù)
   */
  private static final String UNLOCK_LUA =
      "if redis.call(\"get\",KEYS[1]) == ARGV[1] "
          + "then "
          + "  return redis.call(\"del\",KEYS[1]) "
          + "else "
          + "  return 0 "
          + "end ";

  /**
   * 檢查 redisKey 是否上鎖
   *
   * @param redisKey redisKey
   * @param template template
   * @return Boolean
   */
  public static Boolean isLock(String redisKey, String value, RedisTemplate<Object, Object> template) {

    return lock(redisKey, value, template, RETRY_TIMES);
  }

  private static Boolean lock(String redisKey,
                String value,
                RedisTemplate<Object, Object> template,
                int retryTimes) {

    boolean result = lockKey(redisKey, value, template);

    while (!(result) && retryTimes-- > 0) {
      try {

        log.debug("lock failed, retrying...{}", retryTimes);
        Thread.sleep(RedisDistributedLock.SLEEP_MILLIS);
      } catch (InterruptedException e) {

        return false;
      }
      result = lockKey(redisKey, value, template);
    }

    return result;
  }


  private static Boolean lockKey(final String key,
                  final String value,
                  RedisTemplate<Object, Object> template) {
    try {

      RedisCallback<Boolean> callback = (connection) -> connection.set(
          key.getBytes(StandardCharsets.UTF_8),
          value.getBytes(StandardCharsets.UTF_8),
          Expiration.milliseconds(RedisDistributedLock.TIMEOUT_MILLIS),
          RedisStringCommands.SetOption.SET_IF_ABSENT
      );

      return template.execute(callback);
    } catch (Exception e) {

      log.info("lock key fail because of ", e);
    }

    return false;
  }


  /**
   * 釋放分布式鎖資源
   *
   * @param redisKey key
   * @param value  value
   * @param template redis
   * @return Boolean
   */
  public static Boolean releaseLock(String redisKey,
                   String value,
                   RedisTemplate<Object, Object> template) {
    try {
      RedisCallback<Boolean> callback = (connection) -> connection.eval(
          UNLOCK_LUA.getBytes(),
          ReturnType.BOOLEAN,
          1,
          redisKey.getBytes(StandardCharsets.UTF_8),
          value.getBytes(StandardCharsets.UTF_8)
      );

      return template.execute(callback);
    } catch (Exception e) {

      log.info("release lock fail because of ", e);
    }

    return false;
  }

}

import lombok.extern.slf4j.Slf4j;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.annotation.Resource;

/**
 * @author miao
 */
@RestController
@Slf4j
public class TestController {

  @Resource
  private RedisTemplate<Object, Object> redisTemplate;

  @PostMapping("/order")
  public String createOrder() throws InterruptedException {

    log.info("開(kāi)始創(chuàng)建訂單");

    Boolean isLock = RedisDistributedLock.isLock("testLock", "456789", redisTemplate);

    if (!isLock) {

      log.info("鎖已經(jīng)被占用");
      return "fail";
    } else {
      //.....處理邏輯
    }

    Thread.sleep(10000);
    //一定要記得釋放鎖，否則會(huì)出現(xiàn)問(wèn)題
    RedisDistributedLock.releaseLock("testLock", "456789", redisTemplate);

    return "success";
  }
}