void brpoplpushCommand(redisClient *c) {
time_t timeout;
if (getTimeoutFromObjectOrReply(c,c->argv[3],&timeout) != REDIS_OK)
return;
robj *key = lookupKeyWrite(c->db, c->argv[1]);
if (key == NULL) {
if (c->flags & REDIS_MULTI) {
/* Blocking against an empty list in a multi state
* returns immediately. */
addReply(c, shared.nullbulk);
} else {
/* The list is empty and the client blocks. */
blockForKeys(c, c->argv + 1, 1, timeout, c->argv[2]);
}
} else {
if (key->type != REDIS_LIST) {
addReply(c, shared.wrongtypeerr);
} else {
/* The list exists and has elements, so
* the regular rpoplpushCommand is executed. */
redisAssertWithInfo(c,key,listTypeLength(key) > 0);
rpoplpushCommand(c);
}
}
}
// BRPOPLPUSH source destination timeout
// BRPOPLPUSH命令的实现
void brpoplpushCommand(client *c) {
mstime_t timeout;
//以秒为单位取出超时时间
if (getTimeoutFromObjectOrReply(c,c->argv[3],&timeout,UNIT_SECONDS)
!= C_OK) return;
//以写操作读取出 source的值
robj *key = lookupKeyWrite(c->db, c->argv[1]);
//如果键为空，阻塞
if (key == NULL) {
// 如果命令在一个事务中执行，则发送一个空回复以避免死等待
if (c->flags & CLIENT_MULTI) {
/* Blocking against an empty list in a multi state
* returns immediately. */
addReply(c, shared.nullbulk);
} else {
/* The list is empty and the client blocks. */
// 列表为空，则将client阻塞
blockForKeys(c, c->argv + 1, 1, timeout, c->argv[2]);
}
//如果键不为空，指向RPOPLPUSH
} else {
//判断取出的value对象是否为列表类型，不是的话发送类型错误信息
if (key->type != OBJ_LIST) {
addReply(c, shared.wrongtypeerr);
} else {
/* The list exists and has elements, so
* the regular rpoplpushCommand is executed. */
// value对象的列表存在且有元素，所以调用普通的rpoplpush命令
serverAssertWithInfo(c,key,listTypeLength(key) > 0);
rpoplpushCommand(c);
}
}
}
