memcache 问题

chenzhanyiczy

问问大家。
刚刚因为项目需要，用到了memcache。
memcache 有 memcached_server_push，memcached_server_by_key等函数，官方的解析是：

memcached_server_push() pushes an array of memcached_server_st into the memcached_st structure. These servers will be placed at the end. Duplicate servers are allowed, so duplication is not checked. A copy is made of structure so the list provided (and any operations on the list) are not saved.

不是很明白，具体这些函数是用来干什么的？