Redis高并发分布锁的示例

// 仅仅加锁
// 读取 stock=15
Boolean ret = stringRedisTemplate.opsForValue().setIfAbsent("lock_key", "1"); // jedis.setnx(k,v)
// TODO 业务代码 stock--
stringRedisTemplate.delete("lock_key");

// 加锁，且设置锁过期时间
// 读取 stock = 15
Boolean result = stringRedisTemplate.opsForValue().setIfAbsent("key", "1", 10, TimeUnit.SECONDS);
// TODO 业务代码 stock--
stringRedisTemplate.delete(key);

// 加锁，且（给每个线程）设置锁过期时间, 删除锁时判断是否当前线程
// 读取  stock = 15
String uuid = UUID.getUuid; 
Boolean result = stringRedisTemplate.opsForValue().setIfAbsent("key", uuid, 10, TimeUnit.SECONDS);
// TODO 业务代码  stock--  15 -> 14
// 判断是否当前线程
if (uuid.equals(stringRedisTemplate.opsForValue().get(key)) {
    // 极端场景下：（执行时间定格在9.99秒）突然卡顿 10ms or redis服务宕机！！！
    // 此时刚好锁过期，自动删除
    // 其他线程获取锁，然后会把上个线程的锁删除，又会出现bug
	stringRedisTemplate.delete(key);
}

@Autowire
public Redisson redisson;
   
 public void stock () {
     String key = "key";
     RLock lock = redisson.getLock(key);
     try {
         lock.lock();
         // TODO: 业务代码 
     } catch(Exception e) {
         lock.unlock();
     }
 }

//模拟一个商品减库存的原子操作
//lua脚本命令执行方式：redis-cli --eval /tmp/test.lua , 10
jedis.set("product_stock_10016", "15");  // 初始化商品10016的库存
String script = " local count = redis.call('get', KEYS[1]) " +
                " local a = tonumber(count) " +
                " local b = tonumber(ARGV[1]) " +
                " if a >= b then " +
                "   redis.call('set', KEYS[1], a-b) " +
                // 模拟语法报错回滚操作
                "   bb == 0 " +
                "   return 1 " +
                " end " +
                " return 0 ";
Object obj = jedis.eval(script, Arrays.asList("product_stock_10016"), Arrays.asList("10"));
System.out.println(obj);

public void lockInterruptibly(long leaseTime, TimeUnit unit) throws InterruptedException {
   long threadId = Thread.currentThread().getId();
   Long ttl = this.tryAcquire(leaseTime, unit, threadId);
   if (ttl != null) {
       RFuture<RedissonLockEntry> future = this.subscribe(threadId);
        this.commandExecutor.syncSubscription(future);
       try {
           while(true) {
               ttl = this.tryAcquire(leaseTime, unit, threadId);
               if (ttl == null) {
                   return;
                }
               if (ttl >= 0L) {
                   this.getEntry(threadId).getLatch().tryAcquire(ttl, TimeUnit.MILLISECONDS);
               } else {
                   this.getEntry(threadId).getLatch().acquire();
               }
           }
       } finally {
           this.unsubscribe(future, threadId);
       }
   }
}