/* Subscribe a client to a channel. Returns 1 if the operation succeeded, or
* 0 if the client was already subscribed to that channel. */
int pubsubSubscribeChannel(client *c, robj *channel) {
dictEntry *de;
list *clients = NULL;
int retval = 0;
/* Add the channel to the client -> channels hash table */
if (dictAdd(c->pubsub_channels,channel,NULL) == DICT_OK) {
retval = 1;
incrRefCount(channel);
/* Add the client to the channel -> list of clients hash table */
de = dictFind(server.pubsub_channels,channel);
if (de == NULL) {
clients = listCreate();
dictAdd(server.pubsub_channels,channel,clients);
incrRefCount(channel);
} else {
clients = dictGetVal(de);
}
listAddNodeTail(clients,c);
}
/* Notify the client */
addReply(c,shared.mbulkhdr[3]);
addReply(c,shared.subscribebulk);
addReplyBulk(c,channel);
addReplyLongLong(c,clientSubscriptionsCount(c));
return retval;
}
/* 频道订阅，即设置客户端订阅频道，如果操作成功返回1，如果该客户端已经订阅了指定频道则返回0 */
int pubsubSubscribeChannel(redisClient *c, robj *channel) {
dictEntry *de;
list *clients = NULL;
int retval = 0;
/* Add the channel to the client -> channels hash table */
// 将频道channel添加到client -> channels哈希表中
if (dictAdd(c->pubsub_channels,channel,NULL) == DICT_OK) {
retval = 1;
incrRefCount(channel);
/* Add the client to the channel -> list of clients hash table */
// server.pubsub_channels中保存了Redis服务器中所有频道和其相关客户端的信息
// 先判断给定频道是否存在于server.pubsub_channels字典中
de = dictFind(server.pubsub_channels,channel);
if (de == NULL) {
// 频道不存在，则将其加入server.pubsub_channels中
clients = listCreate();
dictAdd(server.pubsub_channels,channel,clients);
incrRefCount(channel);
} else {
clients = dictGetVal(de);
}
// 将客户端添加到指定频道对应的客户端链表中
listAddNodeTail(clients,c);
}
/* Notify the client */
// 回复客户端
addReply(c,shared.mbulkhdr[3]);
addReply(c,shared.subscribebulk);
addReplyBulk(c,channel);
addReplyLongLong(c,clientSubscriptionsCount(c));
return retval;
}
/* 模式订阅，即设置客户端订阅某模式。如果订阅成功则返回1，如果客户端已经订阅了该模式则返回0。*/
int pubsubSubscribePattern(redisClient *c, robj *pattern) {
int retval = 0;
// 先在客户端的c->pubsub_patterns链表中查找，判断客户端是否已经订阅了该模式
if (listSearchKey(c->pubsub_patterns,pattern) == NULL) {
// 客户端并没有订阅该模式
retval = 1;
pubsubPattern *pat;
// 将制定模式添加到c->pubsub_patterns链表中
listAddNodeTail(c->pubsub_patterns,pattern);
incrRefCount(pattern);
pat = zmalloc(sizeof(*pat));
pat->pattern = getDecodedObject(pattern);
pat->client = c;
// 将pubsubPattern结构添加到server.pubsub_patterns链表中
listAddNodeTail(server.pubsub_patterns,pat);
}
/* Notify the client */
// 回复客户端
addReply(c,shared.mbulkhdr[3]);
// 回复“psubscribe”字符串
addReply(c,shared.psubscribebulk);
// 回复被订阅的模式字符串
addReplyBulk(c,pattern);
// 回复客户端订阅的频道和模式总数目
addReplyLongLong(c,clientSubscriptionsCount(c));
return retval;
}
void punsubscribeCommand(client *c) {
if (c->argc == 1) {
pubsubUnsubscribeAllPatterns(c,1);
} else {
int j;
for (j = 1; j < c->argc; j++)
pubsubUnsubscribePattern(c,c->argv[j],1);
}
if (clientSubscriptionsCount(c) == 0) c->flags &= ~CLIENT_PUBSUB;
}
/* unsbuscribe退订频道命令 */
void unsubscribeCommand(redisClient *c) {
if (c->argc == 1) {
pubsubUnsubscribeAllChannels(c,1);
} else {
int j;
for (j = 1; j < c->argc; j++)
pubsubUnsubscribeChannel(c,c->argv[j],1);
}
if (clientSubscriptionsCount(c) == 0) c->flags &= ~REDIS_PUBSUB;
}
/* Subscribe a client to a pattern. Returns 1 if the operation succeeded, or 0 if the client was already subscribed to that pattern. */
int pubsubSubscribePattern(client *c, robj *pattern) {
int retval = 0;
if (listSearchKey(c->pubsub_patterns,pattern) == NULL) {
retval = 1;
pubsubPattern *pat;
listAddNodeTail(c->pubsub_patterns,pattern);
incrRefCount(pattern);
pat = zmalloc(sizeof(*pat));
pat->pattern = getDecodedObject(pattern);
pat->client = c;
listAddNodeTail(server.pubsub_patterns,pat);
}
/* Notify the client */
addReply(c,shared.mbulkhdr[3]);
addReply(c,shared.psubscribebulk);
addReplyBulk(c,pattern);
addReplyLongLong(c,clientSubscriptionsCount(c));
return retval;
}