Redis：自定义分布式锁

川长思鸟来 2024-03-24 08:46 78阅读 0赞

resources/unlock.lua

-- 比较线程标示与锁中的标示是否一致
    if(redis.call('get', KEYS[1]) ==  ARGV[1]) then
        -- 释放锁 del key
        return redis.call('del', KEYS[1])
    end
    return 0

public interface ILock {
    
        /**
         * 尝试获取锁
         * @param timeoutSec 锁持有的超时时间，过期后自动释放
         * @return true代表获取锁成功; false代表获取锁失败
         */
        boolean tryLock(long timeoutSec);
    
        /**
         * 释放锁
         */
        void unlock();
    }

import cn.hutool.core.lang.UUID;
    import org.springframework.core.io.ClassPathResource;
    import org.springframework.data.redis.core.script.DefaultRedisScript;
    
    import java.util.concurrent.TimeUnit;
    
    public class SimpleRedisLock implements ILock {
    
        private String name;
        private StringRedisTemplate stringRedisTemplate;
    
        public SimpleRedisLock(String name, StringRedisTemplate stringRedisTemplate) {
            this.name = name;
            this.stringRedisTemplate = stringRedisTemplate;
        }
    
        private static final String KEY_PREFIX = "lock:";
        private static final String ID_PREFIX = UUID.randomUUID().toString(true) + "-";
        private static final DefaultRedisScript<Long> UNLOCK_SCRIPT;
        static {
            UNLOCK_SCRIPT = new DefaultRedisScript<>();
            UNLOCK_SCRIPT.setLocation(new ClassPathResource("unlock.lua"));
            UNLOCK_SCRIPT.setResultType(Long.class);
        }
    
        @Override
        public boolean tryLock(long timeoutSec) {
            // 获取线程标示
            String threadId = ID_PREFIX + Thread.currentThread().getId();
            // 获取锁
            Boolean success = stringRedisTemplate.opsForValue()
                    .setIfAbsent(KEY_PREFIX + name, threadId, timeoutSec, TimeUnit.SECONDS);
            return Boolean.TRUE.equals(success);
        }
    
        @Override
        public void unlock() {
            // 调用lua脚本
            stringRedisTemplate.execute(
                    UNLOCK_SCRIPT,
                    Collections.singletonList(KEY_PREFIX + name),
                    ID_PREFIX + Thread.currentThread().getId());
        }
    }