small code re-org to fit best practices

Signed-off-by: Kuat Yessenov <kuat@google.com>

pkg/cache/cache.go

@@ -68,3 +68,12 @@ type Response struct {
 	// Resources to be included in the response.
 	Resources []Resource
 }
+
+// SkipFetchError is the error returned when the cache fetch is short
+// circuited due to the client's version already being up-to-date.
+type SkipFetchError struct{}
+
+// Error satisfies the error interface
+func (e SkipFetchError) Error() string {
+	return "skip fetch: version up to date"
+}

pkg/cache/resource.go

@@ -21,7 +21,8 @@ import (
 	v2 "github.com/envoyproxy/go-control-plane/v2/envoy/api/v2"
 	auth "github.com/envoyproxy/go-control-plane/v2/envoy/api/v2/auth"
 	hcm "github.com/envoyproxy/go-control-plane/v2/envoy/config/filter/network/http_connection_manager/v2"
-	"github.com/envoyproxy/go-control-plane/v2/pkg/util"
+	"github.com/envoyproxy/go-control-plane/v2/pkg/conversion"
+	"github.com/envoyproxy/go-control-plane/v2/pkg/wellknown"
 )
 
 // Resource is the base interface for the xDS payload.
@@ -102,7 +103,7 @@ func GetResourceReferences(resources map[string]Resource) map[string]bool {
 			// extract route configuration names from HTTP connection manager
 			for _, chain := range v.FilterChains {
 				for _, filter := range chain.Filters {
-					if filter.Name != util.HTTPConnectionManager {
+					if filter.Name != wellknown.HTTPConnectionManager {
 						continue
 					}
 
@@ -112,7 +113,7 @@ func GetResourceReferences(resources map[string]Resource) map[string]bool {
 					if typedConfig := filter.GetTypedConfig(); typedConfig != nil {
 						ptypes.UnmarshalAny(typedConfig, config)
 					} else {
-						util.StructToMessage(filter.GetConfig(), config)
+						conversion.StructToMessage(filter.GetConfig(), config)
 					}
 
 					if config == nil {

pkg/cache/simple.go

@@ -22,7 +22,6 @@ import (
 	"time"
 
 	"github.com/envoyproxy/go-control-plane/v2/pkg/log"
-	"github.com/envoyproxy/go-control-plane/v2/pkg/util"
 )
 
 // SnapshotCache is a snapshot-based cache that maintains a single versioned
@@ -286,7 +285,7 @@ func (cache *snapshotCache) Fetch(ctx context.Context, request Request) (*Respon
 		// It might be beneficial to hold the request since Envoy will re-attempt the refresh.
 		version := snapshot.GetVersion(request.TypeUrl)
 		if request.VersionInfo == version {
-			return nil, &util.SkipFetchError{}
+			return nil, &SkipFetchError{}
 		}
 
 		resources := snapshot.GetResources(request.TypeUrl)

pkg/util/struct.go → pkg/conversion/struct.go

@@ -12,8 +12,8 @@
 //   See the License for the specific language governing permissions and
 //   limitations under the License.
 
-// Package util contains shared utility functions.
-package util
+// Package conversion contains shared utility functions for converting xDS resources.
+package conversion
 
 import (
 	"bytes"

pkg/util/struct_test.go → pkg/conversion/struct_test.go

@@ -12,7 +12,7 @@
 //   See the License for the specific language governing permissions and
 //   limitations under the License.
 
-package util_test
+package conversion_test
 
 import (
 	"reflect"
@@ -22,15 +22,15 @@ import (
 
 	v2 "github.com/envoyproxy/go-control-plane/v2/envoy/api/v2"
 	core "github.com/envoyproxy/go-control-plane/v2/envoy/api/v2/core"
-	"github.com/envoyproxy/go-control-plane/v2/pkg/util"
+	"github.com/envoyproxy/go-control-plane/v2/pkg/conversion"
 )
 
 func TestConversion(t *testing.T) {
 	pb := &v2.DiscoveryRequest{
 		VersionInfo: "test",
 		Node:        &core.Node{Id: "proxy"},
 	}
-	st, err := util.MessageToStruct(pb)
+	st, err := conversion.MessageToStruct(pb)
 	if err != nil {
 		t.Fatalf("unexpected error %v", err)
 	}
@@ -47,19 +47,19 @@ func TestConversion(t *testing.T) {
 	}
 
 	out := &v2.DiscoveryRequest{}
-	err = util.StructToMessage(st, out)
+	err = conversion.StructToMessage(st, out)
 	if err != nil {
 		t.Fatalf("unexpected error %v", err)
 	}
 	if !reflect.DeepEqual(pb, out) {
 		t.Errorf("StructToMessage(%v) => got %v, want %v", st, out, pb)
 	}
 
-	if _, err = util.MessageToStruct(nil); err == nil {
+	if _, err = conversion.MessageToStruct(nil); err == nil {
 		t.Error("MessageToStruct(nil) => got no error")
 	}
 
-	if err = util.StructToMessage(nil, &v2.DiscoveryRequest{}); err == nil {
+	if err = conversion.StructToMessage(nil, &v2.DiscoveryRequest{}); err == nil {
 		t.Error("StructToMessage(nil) => got no error")
 	}
 }

pkg/server/gateway.go

@@ -25,7 +25,6 @@ import (
 	v2 "github.com/envoyproxy/go-control-plane/v2/envoy/api/v2"
 	"github.com/envoyproxy/go-control-plane/v2/pkg/cache"
 	"github.com/envoyproxy/go-control-plane/v2/pkg/log"
-	"github.com/envoyproxy/go-control-plane/v2/pkg/util"
 )
 
 // HTTPGateway is a custom implementation of [gRPC gateway](https://github.com/grpc-ecosystem/grpc-gateway)
@@ -83,7 +82,7 @@ func (h *HTTPGateway) ServeHTTP(resp http.ResponseWriter, req *http.Request) {
 	if err != nil {
 		// SkipFetchErrors will return a 304 which will signify to the envoy client that
 		// it is already at the latest version; all other errors will 500 with a message.
-		if _, ok := err.(*util.SkipFetchError); ok {
+		if _, ok := err.(*cache.SkipFetchError); ok {
 			resp.WriteHeader(http.StatusNotModified)
 		} else {
 			http.Error(resp, "fetch error: "+err.Error(), http.StatusInternalServerError)

pkg/test/resource/resource.go

@@ -32,7 +32,7 @@ import (
 	hcm "github.com/envoyproxy/go-control-plane/v2/envoy/config/filter/network/http_connection_manager/v2"
 	tcp "github.com/envoyproxy/go-control-plane/v2/envoy/config/filter/network/tcp_proxy/v2"
 	"github.com/envoyproxy/go-control-plane/v2/pkg/cache"
-	"github.com/envoyproxy/go-control-plane/v2/pkg/util"
+	"github.com/envoyproxy/go-control-plane/v2/pkg/wellknown"
 )
 
 const (
@@ -219,10 +219,10 @@ func MakeHTTPListener(mode string, listenerName string, port uint32, route strin
 			},
 		},
 		HttpFilters: []*hcm.HttpFilter{{
-			Name: util.Router,
+			Name: wellknown.Router,
 		}},
 		AccessLog: []*alf.AccessLog{{
-			Name: util.HTTPGRPCAccessLog,
+			Name: wellknown.HTTPGRPCAccessLog,
 			ConfigType: &alf.AccessLog_TypedConfig{
 				TypedConfig: alsConfigPbst,
 			},
@@ -248,7 +248,7 @@ func MakeHTTPListener(mode string, listenerName string, port uint32, route strin
 		},
 		FilterChains: []*listener.FilterChain{{
 			Filters: []*listener.Filter{{
-				Name: util.HTTPConnectionManager,
+				Name: wellknown.HTTPConnectionManager,
 				ConfigType: &listener.Filter_TypedConfig{
 					TypedConfig: pbst,
 				},
@@ -285,7 +285,7 @@ func MakeTCPListener(listenerName string, port uint32, clusterName string) *v2.L
 		},
 		FilterChains: []*listener.FilterChain{{
 			Filters: []*listener.Filter{{
-				Name: util.TCPProxy,
+				Name: wellknown.TCPProxy,
 				ConfigType: &listener.Filter_TypedConfig{
 					TypedConfig: pbst,
 				},

pkg/util/wellknown.go → pkg/wellknown/wellknown.go

@@ -12,7 +12,8 @@
 //   See the License for the specific language governing permissions and
 //   limitations under the License.
 
-package util
+// Package wellknown contains common names for filters, listeners, etc.
+package wellknown
 
 // HTTP filter names
 const (
@@ -115,12 +116,3 @@ const (
 	// HTTPGRPCAccessLog sink for the HTTP gRPC access log service
 	HTTPGRPCAccessLog = "envoy.http_grpc_access_log"
 )
-
-// SkipFetchError is the error returned when the cache fetch is short
-// circuited due to the client's version already being up-to-date.
-type SkipFetchError struct{}
-
-// Error satisfies the error interface
-func (e SkipFetchError) Error() string {
-	return "skip fetch: version up to date"
-}