stats: Remove the now unused Stats.Clone method

This has been superseded by the Snapshot method.

stats/stats.go

@@ -67,6 +67,7 @@ type CounterPair struct {
 	Value int
 }
 
+// Snapshot holds the names and values of some counters.
 type Snapshot []CounterPair
 
 // Snapshot returns the current values of all the counters.
@@ -80,18 +81,3 @@ func (s *Stats) Snapshot() Snapshot {
 	}
 	return out
 }
-
-// Clone returns a new Stats instance, copying the source Stats
-// counts.
-func (s *Stats) Clone() *Stats {
-	s.mu.Lock()
-	defer s.mu.Unlock()
-
-	out := &Stats{
-		counts: make(map[string]int),
-	}
-	for name, count := range s.counts {
-		out.counts[name] = count
-	}
-	return out
-}

stats/stats_small_test.go

@@ -62,23 +62,6 @@ func TestSnapshot(t *testing.T) {
 	}, s.Snapshot())
 }
 
-func TestClone(t *testing.T) {
-	s := stats.New("foo", "bar", "qaz")
-	s.Inc("foo")
-	s.Inc("bar")
-	s.Inc("bar")
-
-	s2 := s.Clone()
-	assert.Equal(t, 1, s2.Get("foo"))
-	assert.Equal(t, 2, s2.Get("bar"))
-	assert.Equal(t, 0, s2.Get("qaz"))
-
-	// Make sure they're independent
-	s2.Inc("foo")
-	assert.Equal(t, 2, s2.Get("foo"))
-	assert.Equal(t, 1, s.Get("foo"))
-}
-
 func BenchmarkStats(b *testing.B) {
 	s := stats.New("foo", "bar")