Refactor and fix spec.DeepHash().

We don't need a binary-to-text encoding for the hash, we just test
the binary result. We also don't need to sort []Endpoint or hash
Service.

pkg/varnish/vcl/spec.go

@@ -32,7 +32,6 @@ import (
 	"crypto/sha512"
 	"encoding/binary"
 	"hash"
-	"math/big"
 	"sort"
 	"time"
 )
@@ -62,18 +61,6 @@ func (ep Endpoint) hash(hash hash.Hash) {
 	hash.Write(portBytes)
 }
 
-// interface for sorting []Endpoint
-type byIPPort []Endpoint
-
-func (a byIPPort) Len() int      { return len(a) }
-func (a byIPPort) Swap(i, j int) { a[i], a[j] = a[j], a[i] }
-func (a byIPPort) Less(i, j int) bool {
-	if a[i].IP < a[j].IP {
-		return true
-	}
-	return a[i].Port < a[j].Port
-}
-
 // Service represents a backend Service, where the Endpoints are
 // indexed by the Pod names to which they correspond.
 type Service struct {
@@ -81,13 +68,6 @@ type Service struct {
 	Endpoints map[string]Endpoint
 }
 
-func (svc Service) hash(hash hash.Hash) {
-	for name, ep := range svc.Endpoints {
-		hash.Write([]byte(name))
-		ep.hash(hash)
-	}
-}
-
 // ConfigMap represents metadata about the ConfigMap that contains
 // VCL sources.
 type ConfigMap struct {
@@ -115,13 +95,20 @@ type Spec struct {
 	Created time.Time
 }
 
-// DeepHash computes a alphanumerically encoded hash value from a Spec
-// such that, almost certainly, two Specs are deeply equal iff their
-// hash values are equal (unless we've discovered a SHA512 collision).
-func (spec Spec) DeepHash() string {
+// DeepHash computes a hash value from a Spec such that, almost
+// certainly, two Specs are equivalent iff their hash values are equal
+// (unless we've discovered a SHA512 collision).
+//
+// The Created field is ignored for equivalence checks. Metadata are
+// only checked for the ConfigMap -- the Spec changes when the
+// ConfigMap metadata change, but Services and Endpoints are checked
+// for equivalence by content, and are considered unchanged when only
+// their metadata change.
+func (spec Spec) DeepHash() []byte {
 	hash := sha512.New512_224()
 
 	hash.Write([]byte(spec.Version))
+	hash.Write([]byte(spec.Main))
 
 	hash.Write([]byte(spec.CfgMap.Namespace))
 	hash.Write([]byte(spec.CfgMap.Name))
@@ -130,21 +117,26 @@ func (spec Spec) DeepHash() string {
 
 	svcs := make([]string, len(spec.Services))
 	i := 0
-	for k := range spec.Services {
-		svcs[i] = k
+	for svc := range spec.Services {
+		svcs[i] = svc
 		i++
 	}
 	sort.Strings(svcs)
 	for _, svc := range svcs {
 		hash.Write([]byte(svc))
-		spec.Services[svc].hash(hash)
+		epNames := make([]string, len(spec.Services[svc].Endpoints))
+		i = 0
+		for epName := range spec.Services[svc].Endpoints {
+			epNames[i] = epName
+			i++
+		}
+		sort.Strings(epNames)
+		for _, epName := range epNames {
+			spec.Services[svc].Endpoints[epName].hash(hash)
+		}
 	}
 
-	hash.Write([]byte(spec.Main))
-
-	h := new(big.Int)
-	h.SetBytes(hash.Sum(nil))
-	return h.Text(62)
+	return (hash.Sum(nil))
 }
 
 // FQVersion returns a fully qualified version -- the version string

pkg/varnish/vcl/vcl_test.go

@@ -87,6 +87,16 @@ func TestMain(m *testing.M) {
 var testSpec = Spec{
 	Version: "4.7.11",
 	Created: time.Unix(1136239445, 123456000),
+	Main: "default.vcl",
+	CfgMap: ConfigMap{
+		Name:    "vcl-cfgmap",
+		Version: "4.7.11",
+		Meta: Meta{
+			Namespace:       "default",
+			UID:             "513e6391-079b-11ea-b351-bab55b1b33a8",
+			ResourceVersion: "520822",
+		},
+	},
 	Services: map[string]Service{
 		"bar-service": Service{
 			Meta: Meta{
@@ -214,3 +224,11 @@ func TestConfigName(t *testing.T) {
 		t.Fatal("ConfigName() result is an illegal VCL name:", cfgName)
 	}
 }
+
+func TestDeepHash(t *testing.T) {
+	specCopy := testSpec
+	if !bytes.Equal(specCopy.DeepHash(), testSpec.DeepHash()) {
+		t.Fatalf("DeepHash(%+v)=%+v != DeepHash(%+v)=%+v", testSpec,
+			testSpec.DeepHash(), specCopy, specCopy.DeepHash())
+	}
+}