Redis分布式锁Java代码实现

#Redis分布式锁Java代码实现

/**
 * redis分布式锁 可重入
 * */
public class RedisDistributedLock implements Lock {

    private StringRedisTemplate stringRedisTemplate;

    private String lockName; //KEYS[1]
    private String uuidValue; //ARGV[1]
    private long expireTime; //ARGV[2]

    public RedisDistributedLock(StringRedisTemplate stringRedisTemplate, String lockName) {
        this.stringRedisTemplate = stringRedisTemplate;
        this.lockName = lockName;
        this.uuidValue = IdUtil.simpleUUID() + ":" + Thread.currentThread().getId();
        this.expireTime = 50L;
    }

    @Override
    public void lock() {
        tryLock();
    }


    @Override
    public boolean tryLock() {
        try {
            tryLock(-1, TimeUnit.SECONDS);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return false;
    }

    @Override
    public boolean tryLock(long time, @NotNull TimeUnit unit) throws InterruptedException {
        if (time == -1L){
            String script = "if redis.call('exists', KEYS[1]) == 0 or redis.call('hexists', KEYS[1], ARGV[1]) == 1 then " +
                                    "redis.call('hincrby', KEYS[1], ARGV[1], 1)  " +
                                    "redis.call('expire', KEYS[1], ARGV[2])   " +
                            "else   " +
                                    " return 0  " +
                            "end";
            while(!stringRedisTemplate.execute(new DefaultRedisScript<>(script, Boolean.class), Arrays.asList(lockName), uuidValue, expireTime)) {
                // 暂停60毫秒
                try { TimeUnit.MILLISECONDS.sleep(60);} catch (InterruptedException e) { e.printStackTrace();};
            }
            renewExpire();
            return true;
        }
        return false;
    }

    // 自动续期  watch dog的思想
    private void renewExpire() {

        String script = "if redis.call('HEXISTS', KEYS[1], ARGV[1]) == 1 then  " +
                                "return redis.call('expire', KEYS[1], ARGV[2])  " +
                        "else  " +
                                "return 0 " +
                        "end";

        new Timer().schedule(new TimerTask() {
            @Override
            public void run() {
                if (stringRedisTemplate.execute(new DefaultRedisScript<>(script, Boolean.class), Arrays.asList(lockName), uuidValue, expireTime)){
                    renewExpire();
                }
            }
        }, (this.expireTime * 1000) / 3);
    }

    @Override
    public void unlock() {
        String script = "if redis.call('HEXISTS', KEYS[1], ARGV[1]) == 0 then  " +
                                "return nil  " +
                        "elseif redis.call('HINCRBY', KEYS[1] ,ARGV[1], -1) == 0 then  " +
                                "return redis.call('del', KEYS[1])   " +
                        "else  " +
                                "return 0 " +
                        "end";
        Long flag = stringRedisTemplate.execute(new DefaultRedisScript<>(script, Long.class), Arrays.asList(lockName), uuidValue, expireTime);
        if (flag == null){
            throw new RuntimeException("this lock doesn't not exists!!!!!");
        }
    }

    @Override
    public void lockInterruptibly() throws InterruptedException {

    }

    @NotNull
    @Override
    public Condition newCondition() {
        return null;
    }
}