package com.shuige.components.cache.redis;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.RedisCallback;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.ValueOperations;
import org.springframework.stereotype.Component;
import java.util.Objects;
import java.util.concurrent.TimeUnit;
/**
 * Description: 通用Redis帮助类
 * User: zhouzhou
 * Date: 2018-09-05
 * Time: 15:39
 */
@Component
public class CommonRedisHelper {
  public static final String LOCK_PREFIX = "redis_lock";
  public static final int LOCK_EXPIRE = 300; // ms
  @Autowired
  RedisTemplate redisTemplate;
  /**
   * 最终加强分布式锁
   *
   * @param key key值
   * @return 是否获取到
   */
  public boolean lock(String key){
    String lock = LOCK_PREFIX + key;
    // 利用lambda表达式
    return (Boolean) redisTemplate.execute((RedisCallback) connection -> {
      long expireAt = System.currentTimeMillis() + LOCK_EXPIRE + 1;
      Boolean acquire = connection.setNX(lock.getBytes(), String.valueOf(expireAt).getBytes());
      if (acquire) {
        return true;
      } else {
        byte[] value = connection.get(lock.getBytes());
        if (Objects.nonNull(value) && value.length > 0) {
          long expireTime = Long.parseLong(new String(value));
          if (expireTime < System.currentTimeMillis()) {
            // 如果锁已经过期
            byte[] oldValue = connection.getSet(lock.getBytes(), String.valueOf(System.currentTimeMillis() + LOCK_EXPIRE + 1).getBytes());
            // 防止死锁
            return Long.parseLong(new String(oldValue)) < System.currentTimeMillis();
          }
        }
      }
      return false;
    });
  }
  /**
   * 删除锁
   *
   * @param key
   */
  public void delete(String key) {
    redisTemplate.delete(key);
  }
}

boolean lock = redisHelper.lock(key);
    if (lock) {
      // 执行逻辑操作
      redisHelper.delete(key);
    } else {
      // 设置失败次数计数器, 当到达5次时, 返回失败
      int failCount = 1;
      while(failCount <= 5){
        // 等待100ms重试
        try {
          Thread.sleep(100l);
        } catch (InterruptedException e) {
          e.printStackTrace();
        }
        if (redisHelper.lock(key)){
          // 执行逻辑操作
          redisHelper.delete(key);
        }else{
          failCount ++;
        }
      }
      throw new RuntimeException("现在创建的人太多了, 请稍等再试");
    }