platform agnostic lb ep hash (#10396)

Co-authored-by: Yuval Kohavi <[email protected]>

Author: stevenctl

changelog/v1.18.0-rc3/platform-agnostic-lbephash.yaml

@@ -0,0 +1,6 @@
+changelog:
+  - type: NON_USER_FACING
+    description: >-
+      Don't use native endian-ness when generating hashes.
+      This creates difficulty reproducing tests on different machines
+      where the hashes end up in goldenfiles.

projects/gateway2/krtcollections/endpoints.go

@@ -170,8 +170,8 @@ func hashEndpoints(l PodLocality, emd EndpointWithMd) uint64 {
 func hash(a, b uint64) uint64 {
 	hasher := fnv.New64a()
 	var buf [16]byte
-	binary.NativeEndian.PutUint64(buf[:8], a)
-	binary.NativeEndian.PutUint64(buf[8:], b)
+	binary.LittleEndian.PutUint64(buf[:8], a)
+	binary.LittleEndian.PutUint64(buf[8:], b)
 	hasher.Write(buf[:])
 	return hasher.Sum64()
 }

projects/gateway2/krtcollections/endpoints_test.go

@@ -131,7 +131,6 @@ func TestEndpointsForUpstreamOrderDoesntMatter(t *testing.T) {
 		Zone:   "zone2",
 	}, emd2)
 	g.Expect(result1.Equals(*result4)).To(BeFalse(), "not expected %v, got %v", result1, result2)
-
 }
 
 func TestEndpointsForUpstreamWithDiscoveredUpstream(t *testing.T) {
@@ -239,7 +238,6 @@ func TestEndpointsForUpstreamWithDiscoveredUpstream(t *testing.T) {
 	h2 := result3.LbEpsEqualityHash ^ result4.LbEpsEqualityHash
 
 	g.Expect(h1).NotTo(Equal(h2), "not expected %v, got %v", h1, h2)
-
 }
 
 func TestEndpoints(t *testing.T) {
@@ -960,5 +958,4 @@ func TestEndpoints(t *testing.T) {
 			g.Expect(eps.Equals(*res)).To(BeTrue(), "expected %v, got %v", res, eps)
 		})
 	}
-
 }

projects/gateway2/utils/hash.go

@@ -119,7 +119,7 @@ func hashValue(newhash func() hash.Hash64, h hash.Hash, value *structpb.Value) e
 
 func HashUint64(hasher io.Writer, value uint64) {
 	var bytes [8]byte
-	binary.NativeEndian.PutUint64(bytes[:], value)
+	binary.LittleEndian.PutUint64(bytes[:], value)
 	hasher.Write(bytes[:])
 }