Group based PeerPicker

Hi,

This is a question. The newGroup function is private
func newGroup(name string, cacheBytes int64, getter Getter, peers PeerPicker) *Group

That means I can't pass my own PeerPicker when creating a group. As such, the default HttpPool's PeerPicker is used. Why is this restriction?

I may not understand groupchache correctly. If so correct me. My understanding is the default PeerPicker is portPicker in HttpPool. It uses consistenthash.Map to hash a string into groupcache peers, whether or not a particular peer has created a particular group or not. Suppose I have three processes running groupcache: p1, p2, and p3. And I have two groups: g1, g2. Assume we have the following peer to group mapping:
p1: g1, g2
p2: g2, g3
p3: g1, g3

If in p2 if I call

g2 := groupcache.NewGroup("g2", 10<<20, g2Getter)
g2.Get(ctx, "foo", groupcache.StringSink(&s))

and if "foo" is hashed to p3 where there is no group "g2" will that result in "foo" never cached?

I am adding peer/group auto discover with zookeeper, where grouphook will add itself to zk. Then a group based PeerPicker can be written to only hash the key to those peers that have the group. However, since newGroup with user defined picker is private, I can't find a way to set my own group based PeerPicker.

Thanks,

-John