add registry base interface, mdns, noop implementations, add resolver, client

resolver/resolver.go

@@ -0,0 +1,86 @@
+package resolver
+
+import (
+	"strings"
+
+	"google.golang.org/grpc/resolver"
+
+	"gitlab.bertha.cloud/partitio/lab/grpc/registry"
+)
+
+func New(reg registry.Registry) resolver.Builder {
+	return &builder{reg: reg}
+}
+
+type builder struct {
+	reg registry.Registry
+}
+
+func (r builder) Build(target resolver.Target, cc resolver.ClientConn, opts resolver.BuildOptions) (resolver.Resolver, error) {
+	rslvr :=  &resolvr{reg: r.reg, target: target, cc: cc}
+	go rslvr.run()
+	return rslvr, nil
+}
+
+func (r builder) Scheme() string {
+	return r.reg.String()
+}
+
+type resolvr struct {
+	reg    registry.Registry
+	target resolver.Target
+	cc     resolver.ClientConn
+	addrs  []resolver.Address
+}
+
+func (r *resolvr) run() {
+	if r.reg.String() == "noop" {
+		return
+	}
+	var name, version string
+	parts := strings.Split(r.target.Endpoint, ":")
+	name = parts[0]
+	if len(parts) > 1 {
+		version = parts[1]
+	}
+	svc, err := r.reg.GetService(name)
+	if err != nil {
+		return
+	}
+	for _, v := range svc {
+		if v.Name != name || v.Version != version {
+			continue
+		}
+		for _, vv := range v.Nodes {
+			r.addrs = append(r.addrs, resolver.Address{Addr: vv.Address})
+		}
+	}
+	r.cc.UpdateState(resolver.State{Addresses: r.addrs})
+	w, err := r.reg.Watch(registry.WatchService(r.target.Endpoint))
+	if err != nil {
+		return
+	}
+	defer w.Stop()
+	for {
+		res, err := w.Next()
+		if err != nil {
+			return
+		}
+		// TODO(adphi): implement
+		switch res.Action {
+		case "create":
+
+		case "delete":
+
+		}
+		r.cc.UpdateState(resolver.State{Addresses: r.addrs})
+	}
+}
+
+func (r *resolvr) ResolveNow(options resolver.ResolveNowOptions) {
+	if r.reg.String() == "noop" {
+		r.cc.UpdateState(resolver.State{Addresses: []resolver.Address{{Addr: r.target.Endpoint}}})
+	}
+}
+
+func (r *resolvr) Close() {}