From 14e93a112ba49d7df1ad5c1dff48dae7d148718b Mon Sep 17 00:00:00 2001
From: rsokolowski <rsokolowski@google.com>
Date: Thu, 19 Feb 2015 16:40:35 +0100
Subject: [PATCH] Make DeepHashObject function deterministic.

---
 pkg/util/hash.go      |  3 ++-
 pkg/util/hash_test.go | 43 +++++++++++++++++++++++--------------------
 2 files changed, 25 insertions(+), 21 deletions(-)

diff --git a/pkg/util/hash.go b/pkg/util/hash.go
index fc5bd3bb6b1..b372ceaa8f6 100644
--- a/pkg/util/hash.go
+++ b/pkg/util/hash.go
@@ -26,5 +26,6 @@ import (
 // which follows pointers and prints actual values of the nested objects
 // ensuring the hash does not change when a pointer changes.
 func DeepHashObject(hasher hash.Hash, objectToWrite interface{}) {
-	spew.Fprintf(hasher, "%#v", objectToWrite)
+  printer := spew.ConfigState{Indent: " ", SortKeys: true}
+  printer.Fprintf(hasher, "%#v", objectToWrite)
 }
diff --git a/pkg/util/hash_test.go b/pkg/util/hash_test.go
index c4218b60eb5..553e720bcbe 100644
--- a/pkg/util/hash_test.go
+++ b/pkg/util/hash_test.go
@@ -28,6 +28,7 @@ type wheel struct {
 type unicycle struct {
 	primaryWheel   *wheel
 	licencePlateID string
+	tags           map[string]string
 }
 
 func TestDeepObjectPointer(t *testing.T) {
@@ -36,28 +37,30 @@ func TestDeepObjectPointer(t *testing.T) {
 	wheel2 := wheel{radius: 22}
 	wheel3 := wheel{radius: 17}
 
-	myUni1 := unicycle{licencePlateID: "blah", primaryWheel: &wheel1}
-	myUni2 := unicycle{licencePlateID: "blah", primaryWheel: &wheel2}
-	myUni3 := unicycle{licencePlateID: "blah", primaryWheel: &wheel3}
+	myUni1 := unicycle{licencePlateID: "blah", primaryWheel: &wheel1, tags: map[string]string{"color": "blue", "name": "john"}}
+	myUni2 := unicycle{licencePlateID: "blah", primaryWheel: &wheel2, tags: map[string]string{"color": "blue", "name": "john"}}
+	myUni3 := unicycle{licencePlateID: "blah", primaryWheel: &wheel3, tags: map[string]string{"color": "blue", "name": "john"}}
 
-	hasher1 := adler32.New()
-	hasher2 := adler32.New()
-	hasher3 := adler32.New()
+	// Run it more than once to verify determinism of hasher.
+	for i := 0; i < 100; i++ {
+		hasher1 := adler32.New()
+		hasher2 := adler32.New()
+		hasher3 := adler32.New()
+		// Act
+		DeepHashObject(hasher1, myUni1)
+		hash1 := hasher1.Sum32()
+		DeepHashObject(hasher2, myUni2)
+		hash2 := hasher2.Sum32()
+		DeepHashObject(hasher3, myUni3)
+		hash3 := hasher3.Sum32()
 
-	// Act
-	DeepHashObject(hasher1, myUni1)
-	hash1 := hasher1.Sum32()
-	DeepHashObject(hasher2, myUni2)
-	hash2 := hasher2.Sum32()
-	DeepHashObject(hasher3, myUni3)
-	hash3 := hasher3.Sum32()
+		// Assert
+		if hash1 == hash2 {
+			t.Errorf("hash1 (%d) and hash2(%d) must be different because they have different values for wheel size", hash1, hash2)
+		}
 
-	// Assert
-	if hash1 == hash2 {
-		t.Errorf("hash1 (%d) and hash2(%d) must be different because they have different values for wheel size", hash1, hash2)
-	}
-
-	if hash1 != hash3 {
-		t.Errorf("hash1 (%d) and hash3(%d) must be the same because although they point to different objects, they have the same values for wheel size", hash1, hash3)
+		if hash1 != hash3 {
+			t.Errorf("hash1 (%d) and hash3(%d) must be the same because although they point to different objects, they have the same values for wheel size", hash1, hash3)
+		}
 	}
 }