'''

redis缓存相关工具类

'''

from config import REDIS_HOST, REDIS_PORT, REDIS_PASS, REDIS_DB

import redis

import time

import json



pool = redis.ConnectionPool(host=REDIS_HOST, port=REDIS_PORT, password=REDIS_PASS, db=REDIS_DB)

redis_cli = redis.Redis(connection_pool=pool)





def set_key_exp(key, value, exp_time, nx=None):

    '''

    对指定键值对设置过期时间

    :param key:

    :param value:

    :param exp_time:

    :return:

    '''

    try:

        result = redis_cli.set(key, value, ex=exp_time, nx=nx)

        return result

    except Exception as e:

        print(e)

        return None





def get_key_value(key):

    '''

    获取键的值

    :param key:

    :return:

    '''

    try:

        return redis_cli.get(key)

    except Exception as e:

        print(e)

        return None





def hset_dict(name, key, p_dict):

    '''

    对哈希设置键和值

    :param name:

    :param key:

    :param p_dict:

    :return:

    '''

    redis_cli.hset(name, key, json.dumps(p_dict))





def hget_dict(name, key):

    '''

    获取哈希字典的值

    :param name:

    :param key:

    :param p_dict:

    :return:

    '''

    data = redis_cli.hget(name, key)

    if data:

        return json.loads(data)





def hdel_dict(name, key):

    '''

    删除哈希字典的值

    :param name:

    :param key:

    :param p_dict:

    :return:

    '''

    data = redis_cli.hdel(name, key)

    if data:

        return json.loads(data)





def get_lock(name, value, ex=3, timeout=10):

    '''

    获取锁，超时未获取则返回 False

    # nx - 如果设置为True，则只有name不存在时，当前set操作才执行

    # ex - 锁的过期时间（秒）

    # timeout - 最大等待时间（秒），超时返回 False

    '''

    deadline = time.time() + timeout

    while time.time() < deadline:

        result = redis_cli.set(name, value, nx=True, ex=ex)

        if result:

            return True

        time.sleep(0.05)

    return False





def release_lock(name, value):

    '''

    释放锁，仅在锁的持有者与 value 匹配时才删除

    '''

    # redis.get 返回 bytes，需统一编码后比较

    old_value = redis_cli.get(name)

    if old_value is not None and old_value.decode('utf-8') == str(value):

        redis_cli.delete(name)





if __name__ == '__main__':

    a = set_key_exp('test', 1, 10, nx=True)

    print(a)

    a = set_key_exp('test', 1, 10)

    print(a)

    b = get_key_value('test')

    print(b)