Caching free connections by new.Addr.String() makes some things impossible

[graywolf]

I've been trying some weird setups with custom ServerList and I've run into bug due to https://github.com/bradfitz/gomemcache/blob/master/memcache/memcache.go#L209:

freelist := c.freeconn[addr.String()]

In other words, when I create my own ServerList which contains two addresses:

net.ResolveTCPAddr("tcp", "127.0.0.1:11211")
net.ResolveUnixAddr("unix", "127.0.0.1:11211")

Only one of them can be used due to both resolving to the same thing by .String(). I must say that I was not happy when I found this after like ~1h of debugging why is one of the memcached servers ignored.

I guess one solution would be to include type of the addr into the hash. So something like

freelist := c.freeconn[fmt.Sprintf("%T-%s", addr, addr)]

EDIT: Combined with the fact that idle connections cannot be disabled (since 0 means default, not 0) I'm currently just recreating client for each requests, which is strongly suboptimal.