Promise被我写嵌套了，请问如何优化？

写了个了 redis 加锁的函数，写完发现 promise 嵌套了，感觉有点奇怪。

getLock: function (lockName, seconds) {
    var self = this;
    lockName = self.REDIS_LOCK_PREFIX + lockName;
    var expireTimeInMs = Date.now() + seconds * 1000 + 1;
    return self.setnx(lockName, expireTimeInMs).then(function (res) {
        if (res === 1) {
            return true;
        } else {
            return self.get(lockName).then(function (previousExpireInMs) {
                // 过期死锁
                if (previousExpireInMs < Date.now()) {
                    return self.getset(lockName,expireTimeInMs).then(function (getSetReturnExpireInMs) {
                        // 重新设置成功
                        if(previousExpireInMs===getSetReturnExpireInMs){
                            return true
                        }else{
                            return false
                        }
                    }).catch(function () {
                        return false;
                    })
                }else{
                    return false
                }
            }).catch(function (err) {
                return false;
            })
        }
    }).catch(function (err) {
        logger.error(``);
    })
},

假设 setnx，get，getset 都是同步函数，那么我想实现的逻辑如下：

function getLock() {
    var res = setnx(lockName, expireTimeInMs);
    if (res === 1) {
        return true;
    } else {
        var previousExpireInMs = get(lockName);
        if (previousExpireInMs < Date.now()) {
            var getSetReturnExpireInMs = getset(lockName, expireTimeInMs);
            if (previousExpireInMs === getSetReturnExpireInMs) {
                return true
            } else {
                return false
            }
        } else {
            return false
        }
    }
}

我 promise 的写法感觉姿势不对啊，请同学帮忙指出，谢谢。