// 订阅频道,往client->pubsub_channels这个set中添加,往server.pubsub_channels对应client列表中添加client
int pubsubSubscribeChannel(redisClient *c, robj *channel);
int pubsubUnsubscribeChannel(redisClient *c, robj *channel, int notify);
// 订阅pattern,往client->pubusb_patterns这个list中添加,往server.pubusb_patterns中添加pubsubPattern结构
int pubsubSubscribePattern(redisClient *c, robj *pattern);
int pubsubUnsubscribePattern(redisClient *c, robj *pattern, int notify);
int pubsubUnsubscribeAllChannels(redisClient *c, int notify);
int pubsubUnsubscribeAllPatterns(redisClient *c, int notify);