clientv3/balancer: initial commit

Signed-off-by: Gyuho Lee <gyuhox@gmail.com>

clientv3/balancer/utils.go

@@ -0,0 +1,45 @@
+package balancer
+
+import (
+	"fmt"
+	"net/url"
+	"sort"
+
+	"google.golang.org/grpc/balancer"
+	"google.golang.org/grpc/resolver"
+)
+
+func scToString(sc balancer.SubConn) string {
+	return fmt.Sprintf("%p", sc)
+}
+
+func scsToStrings(scs map[resolver.Address]balancer.SubConn) (ss []string) {
+	ss = make([]string, 0, len(scs))
+	for a, sc := range scs {
+		ss = append(ss, fmt.Sprintf("%s (%s)", a.Addr, scToString(sc)))
+	}
+	sort.Strings(ss)
+	return ss
+}
+
+func addrsToStrings(addrs []resolver.Address) (ss []string) {
+	ss = make([]string, len(addrs))
+	for i := range addrs {
+		ss[i] = addrs[i].Addr
+	}
+	sort.Strings(ss)
+	return ss
+}
+
+func epsToAddrs(eps ...string) (addrs []resolver.Address) {
+	addrs = make([]resolver.Address, 0, len(eps))
+	for _, ep := range eps {
+		u, err := url.Parse(ep)
+		if err != nil {
+			addrs = append(addrs, resolver.Address{Addr: ep, Type: resolver.Backend})
+			continue
+		}
+		addrs = append(addrs, resolver.Address{Addr: u.Host, Type: resolver.Backend})
+	}
+	return addrs
+}