From f296976dddf1b9458ff8697a1b417170ef7fd553 Mon Sep 17 00:00:00 2001
From: Steve Kriss <stephen.kriss@gmail.com>
Date: Mon, 4 Mar 2024 09:41:40 -0700
Subject: [PATCH] more cleanup

Signed-off-by: Steve Kriss <stephen.kriss@gmail.com>
---
 cmd/contour/serve.go             |  7 +------
 internal/xdscache/v3/snapshot.go | 31 +++++++++++++------------------
 2 files changed, 14 insertions(+), 24 deletions(-)

diff --git a/cmd/contour/serve.go b/cmd/contour/serve.go
index 90982f8a944..0697b45a2f8 100644
--- a/cmd/contour/serve.go
+++ b/cmd/contour/serve.go
@@ -23,7 +23,6 @@ import (
 	"time"
 
 	"github.com/alecthomas/kingpin/v2"
-	envoy_cache_v3 "github.com/envoyproxy/go-control-plane/pkg/cache/v3"
 	envoy_server_v3 "github.com/envoyproxy/go-control-plane/pkg/server/v3"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/sirupsen/logrus"
@@ -510,11 +509,7 @@ func (s *Server) doServe() error {
 	var snapshotHandler *xdscache_v3.SnapshotHandler
 
 	if contourConfiguration.XDSServer.Type == contour_v1alpha1.EnvoyServerType {
-		snapshotHandler = xdscache_v3.NewSnapshotHandler(
-			resources,
-			envoy_cache_v3.NewSnapshotCache(false, &contour_xds_v3.Hash, s.log.WithField("context", "snapshotCache")),
-			s.log.WithField("context", "snapshotHandler"),
-		)
+		snapshotHandler = xdscache_v3.NewSnapshotHandler(resources, s.log.WithField("context", "snapshotHandler"))
 
 		// register observer for endpoints updates.
 		endpointHandler.SetObserver(contour.ComposeObservers(snapshotHandler))
diff --git a/internal/xdscache/v3/snapshot.go b/internal/xdscache/v3/snapshot.go
index 2cf09fdc4b3..0f349a0ee96 100644
--- a/internal/xdscache/v3/snapshot.go
+++ b/internal/xdscache/v3/snapshot.go
@@ -15,7 +15,6 @@ package v3
 
 import (
 	"context"
-	"reflect"
 
 	envoy_service_discovery_v3 "github.com/envoyproxy/go-control-plane/envoy/service/discovery/v3"
 	envoy_types "github.com/envoyproxy/go-control-plane/pkg/cache/types"
@@ -23,6 +22,7 @@ import (
 	envoy_resource_v3 "github.com/envoyproxy/go-control-plane/pkg/resource/v3"
 	"github.com/google/uuid"
 	"github.com/sirupsen/logrus"
+	"google.golang.org/protobuf/proto"
 
 	"github.com/projectcontour/contour/internal/dag"
 	contour_xds_v3 "github.com/projectcontour/contour/internal/xds/v3"
@@ -30,14 +30,8 @@ import (
 )
 
 // SnapshotHandler responds to DAG builds via the OnChange()
-// event and generates and caches go-control-plane Snapshots.
-//
-// TODO this is now a bit of a misnomer. Responds to DAG builds
-// or endpoint updates, gets data out of the existing Contour xDS
-// caches, populates either the go-control-plane snapshot cache or
-// linear cache (for EDS). Provides a mux cache to be used by the
-// go-control-plane xDS server. Essentially translates between Contour
-// xDS caches and go-control-plane xDS caches.
+// event and Endpoint updates via the Refresh() event and
+// generates and caches go-control-plane Snapshots.
 type SnapshotHandler struct {
 	resources     map[envoy_resource_v3.Type]xdscache.ResourceCache
 	snapshotCache envoy_cache_v3.SnapshotCache
@@ -47,7 +41,9 @@ type SnapshotHandler struct {
 }
 
 // NewSnapshotHandler returns an instance of SnapshotHandler.
-func NewSnapshotHandler(resources []xdscache.ResourceCache, snapshotCache envoy_cache_v3.SnapshotCache, logger logrus.FieldLogger) *SnapshotHandler {
+func NewSnapshotHandler(resources []xdscache.ResourceCache, log logrus.FieldLogger) *SnapshotHandler {
+	snapshotCache := envoy_cache_v3.NewSnapshotCache(false, &contour_xds_v3.Hash, log.WithField("context", "snapshotCache"))
+
 	edsCache := envoy_cache_v3.NewLinearCache(envoy_resource_v3.EndpointType)
 
 	muxCache := &envoy_cache_v3.MuxCache{
@@ -70,7 +66,7 @@ func NewSnapshotHandler(resources []xdscache.ResourceCache, snapshotCache envoy_
 		snapshotCache: snapshotCache,
 		edsCache:      edsCache,
 		muxCache:      muxCache,
-		log:           logger,
+		log:           log,
 	}
 }
 
@@ -119,19 +115,18 @@ func (s *SnapshotHandler) OnChange(*dag.DAG) {
 	}
 }
 
-// asResources casts the given slice of values (that implement the envoy_types.Resource
+// asResources converts the given slice of values (that implement the envoy_types.Resource
 // interface) to a slice of envoy_types.Resource. If the length of the slice is 0, it
 // returns nil.
-func asResources(messages any) []envoy_types.Resource {
-	v := reflect.ValueOf(messages)
-	if v.Len() == 0 {
+func asResources[T proto.Message](messages []T) []envoy_types.Resource {
+	if len(messages) == 0 {
 		return nil
 	}
 
-	protos := make([]envoy_types.Resource, v.Len())
+	protos := make([]envoy_types.Resource, len(messages))
 
-	for i := range protos {
-		protos[i] = v.Index(i).Interface().(envoy_types.Resource)
+	for i, resource := range messages {
+		protos[i] = resource
 	}
 
 	return protos