support direct scheme on rpc resolver

rpcx/internal/resolver/directbuilder.go

@@ -0,0 +1,30 @@
+package resolver
+
+import (
+	"strings"
+
+	"google.golang.org/grpc/resolver"
+)
+
+type directBuilder struct{}
+
+func (d *directBuilder) Build(target resolver.Target, cc resolver.ClientConn, opts resolver.BuildOptions) (
+	resolver.Resolver, error) {
+	var addrs []resolver.Address
+	endpoints := strings.Split(target.Endpoint, EndpointSep)
+
+	for _, val := range subset(endpoints, subsetSize) {
+		addrs = append(addrs, resolver.Address{
+			Addr: val,
+		})
+	}
+	cc.UpdateState(resolver.State{
+		Addresses: addrs,
+	})
+
+	return &nopResolver{cc: cc}, nil
+}
+
+func (d *directBuilder) Scheme() string {
+	return DirectScheme
+}

rpcx/internal/resolver/discovbuilder.go

@@ -0,0 +1,39 @@
+package resolver
+
+import (
+	"strings"
+
+	"github.com/tal-tech/go-zero/core/discov"
+	"google.golang.org/grpc/resolver"
+)
+
+type discovBuilder struct{}
+
+func (d *discovBuilder) Build(target resolver.Target, cc resolver.ClientConn, opts resolver.BuildOptions) (
+	resolver.Resolver, error) {
+	hosts := strings.Split(target.Authority, EndpointSep)
+	sub, err := discov.NewSubscriber(hosts, target.Endpoint)
+	if err != nil {
+		return nil, err
+	}
+
+	update := func() {
+		var addrs []resolver.Address
+		for _, val := range subset(sub.Values(), subsetSize) {
+			addrs = append(addrs, resolver.Address{
+				Addr: val,
+			})
+		}
+		cc.UpdateState(resolver.State{
+			Addresses: addrs,
+		})
+	}
+	sub.AddListener(update)
+	update()
+
+	return &nopResolver{cc: cc}, nil
+}
+
+func (d *discovBuilder) Scheme() string {
+	return DiscovScheme
+}

rpcx/internal/resolver/resolver.go

@@ -1,68 +1,30 @@
 package resolver
 
-import (
-	"fmt"
-	"strings"
-
-	"github.com/tal-tech/go-zero/core/discov"
-	"google.golang.org/grpc/resolver"
-)
+import "google.golang.org/grpc/resolver"
 
 const (
+	DirectScheme = "direct"
 	DiscovScheme = "discov"
 	EndpointSep  = ","
 	subsetSize   = 32
 )
 
-var builder discovBuilder
+var (
+	dirBuilder directBuilder
+	disBuilder discovBuilder
+)
 
-type discovBuilder struct{}
-
-func (b *discovBuilder) Scheme() string {
-	return DiscovScheme
+func RegisterResolver() {
+	resolver.Register(&dirBuilder)
+	resolver.Register(&disBuilder)
 }
 
-func (b *discovBuilder) Build(target resolver.Target, cc resolver.ClientConn, opts resolver.BuildOptions) (
-	resolver.Resolver, error) {
-	if target.Scheme != DiscovScheme {
-		return nil, fmt.Errorf("bad scheme: %s", target.Scheme)
-	}
-
-	hosts := strings.Split(target.Authority, EndpointSep)
-	sub, err := discov.NewSubscriber(hosts, target.Endpoint)
-	if err != nil {
-		return nil, err
-	}
-
-	update := func() {
-		var addrs []resolver.Address
-		for _, val := range subset(sub.Values(), subsetSize) {
-			addrs = append(addrs, resolver.Address{
-				Addr: val,
-			})
-		}
-		cc.UpdateState(resolver.State{
-			Addresses: addrs,
-		})
-	}
-	sub.AddListener(update)
-	update()
-
-	return &discovResolver{
-		cc: cc,
-	}, nil
-}
-
-type discovResolver struct {
+type nopResolver struct {
 	cc resolver.ClientConn
 }
 
-func (r *discovResolver) Close() {
+func (r *nopResolver) Close() {
 }
 
-func (r *discovResolver) ResolveNow(options resolver.ResolveNowOptions) {
-}
-
-func RegisterResolver() {
-	resolver.Register(&builder)
+func (r *nopResolver) ResolveNow(options resolver.ResolveNowOptions) {
 }