From df3a34406ba499a636f2ede5feacae60b08f1bff Mon Sep 17 00:00:00 2001
From: Martin Polden <mpolden@mpolden.no>
Date: Fri, 10 Jan 2020 22:31:16 +0100
Subject: Add Key field

---
 cache/cache.go      | 22 ++++++++++++++++------
 cache/cache_test.go | 22 +++++++++++++---------
 2 files changed, 29 insertions(+), 15 deletions(-)

diff --git a/cache/cache.go b/cache/cache.go
index 8ee6ce8..e32df8b 100644
--- a/cache/cache.go
+++ b/cache/cache.go
@@ -26,6 +26,7 @@ type Cache struct {
 
 // Value wraps a DNS message stored in the cache.
 type Value struct {
+	Key       uint64
 	CreatedAt time.Time
 	msg       *dns.Msg
 }
@@ -48,6 +49,8 @@ func (v *Value) TTL() time.Duration { return dnsutil.MinTTL(v.msg) }
 // Pack returns a string representation of Value v.
 func (v *Value) Pack() (string, error) {
 	var sb strings.Builder
+	sb.WriteString(strconv.FormatUint(v.Key, 10))
+	sb.WriteString(" ")
 	sb.WriteString(strconv.FormatInt(v.CreatedAt.Unix(), 10))
 	sb.WriteString(" ")
 	data, err := v.msg.Pack()
@@ -61,14 +64,18 @@ func (v *Value) Pack() (string, error) {
 // Unpack converts a string value into a Value type.
 func Unpack(value string) (Value, error) {
 	fields := strings.Fields(value)
-	if len(fields) < 2 {
+	if len(fields) < 3 {
 		return Value{}, fmt.Errorf("invalid number of fields: %q", value)
 	}
-	secs, err := strconv.ParseInt(fields[0], 10, 64)
+	key, err := strconv.ParseUint(fields[0], 10, 64)
+	if err != nil {
+		return Value{}, err
+	}
+	secs, err := strconv.ParseInt(fields[1], 10, 64)
 	if err != nil {
 		return Value{}, err
 	}
-	data, err := hex.DecodeString(fields[1])
+	data, err := hex.DecodeString(fields[2])
 	if err != nil {
 		return Value{}, err
 	}
@@ -77,6 +84,7 @@ func Unpack(value string) (Value, error) {
 		return Value{}, err
 	}
 	return Value{
+		Key:       key,
 		CreatedAt: time.Unix(secs, 0),
 		msg:       msg,
 	}, nil
@@ -169,15 +177,17 @@ func (c *Cache) Set(key uint64, msg *dns.Msg) {
 }
 
 func (c *Cache) set(key uint64, msg *dns.Msg) bool {
-	if c.capacity == 0 || !canCache(msg) {
+	return c.setValue(key, Value{Key: key, CreatedAt: c.now(), msg: msg})
+}
+
+func (c *Cache) setValue(key uint64, value Value) bool {
+	if c.capacity == 0 || !canCache(value.msg) {
 		return false
 	}
-	now := c.now()
 	if len(c.values) == c.capacity && c.capacity > 0 {
 		delete(c.values, c.keys[0])
 		c.keys = c.keys[1:]
 	}
-	value := Value{CreatedAt: now, msg: msg}
 	c.values[key] = value
 	c.appendKey(key)
 	return true
diff --git a/cache/cache_test.go b/cache/cache_test.go
index bf4c610..fb2fe3c 100644
--- a/cache/cache_test.go
+++ b/cache/cache_test.go
@@ -134,13 +134,13 @@ func TestCache(t *testing.T) {
 		ok        bool
 		value     *Value
 	}{
-		{msg, now, true, &Value{CreatedAt: now, msg: msg}},                       // Not expired when query time == create time
-		{msg, now.Add(30 * time.Second), true, &Value{CreatedAt: now, msg: msg}}, // Not expired when below TTL
-		{msg, now.Add(60 * time.Second), true, &Value{CreatedAt: now, msg: msg}}, // Not expired until TTL exceeds
-		{msgNameError, now, true, &Value{CreatedAt: now, msg: msgNameError}},     // NXDOMAIN is cached
-		{msg, now.Add(61 * time.Second), false, nil},                             // Expired due to TTL exceeded
-		{msgWithZeroTTL, now, false, nil},                                        // 0 TTL is not cached
-		{msgFailure, now, false, nil},                                            // Non-cacheable rcode
+		{msg, now, true, &Value{Key: 16316346957082771326, CreatedAt: now, msg: msg}},                       // Not expired when query time == create time
+		{msg, now.Add(30 * time.Second), true, &Value{Key: 16316346957082771326, CreatedAt: now, msg: msg}}, // Not expired when below TTL
+		{msg, now.Add(60 * time.Second), true, &Value{Key: 16316346957082771326, CreatedAt: now, msg: msg}}, // Not expired until TTL exceeds
+		{msgNameError, now, true, &Value{Key: 7258598034460334943, CreatedAt: now, msg: msgNameError}},      // NXDOMAIN is cached
+		{msg, now.Add(61 * time.Second), false, nil},                                                        // Expired due to TTL exceeded
+		{msgWithZeroTTL, now, false, nil},                                                                   // 0 TTL is not cached
+		{msgFailure, now, false, nil},                                                                       // Non-cacheable rcode
 	}
 	for i, tt := range tests {
 		c.now = nowFn
@@ -362,6 +362,7 @@ func TestCacheEvictAndUpdate(t *testing.T) {
 
 func TestPackValue(t *testing.T) {
 	v := Value{
+		Key:       42,
 		CreatedAt: time.Now().Truncate(time.Second),
 		msg:       newA("example.com.", 60, net.ParseIP("192.0.2.1")),
 	}
@@ -373,10 +374,13 @@ func TestPackValue(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	if got, want := unpacked.CreatedAt, v.CreatedAt; !want.Equal(got) {
+	if got, want := unpacked.Key, v.Key; got != want {
+		t.Errorf("Key = %d, want %d", got, want)
+	}
+	if got, want := unpacked.CreatedAt, v.CreatedAt; !got.Equal(want) {
 		t.Errorf("CreatedAt = %s, want %s", got, want)
 	}
-	if got, want := unpacked.msg.String(), v.msg.String(); want != got {
+	if got, want := unpacked.msg.String(), v.msg.String(); got != want {
 		t.Errorf("msg = %s, want %s", got, want)
 	}
 }
-- 
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