Integrate fixes from PR#91. (#126)

This PR has been in review for a while and now there are a bunch of
conflicts and it's a branch in a fork repo so I cannot edit the branch
directly.

cache_test.go

@@ -10,7 +10,7 @@ import (
 	"github.com/dgraph-io/ristretto/z"
 )
 
-var wait time.Duration = time.Millisecond * 10
+var wait = time.Millisecond * 10
 
 func TestCacheKeyToHash(t *testing.T) {
 	keyToHashCount := 0
@@ -305,10 +305,8 @@ func TestCacheSet(t *testing.T) {
 		if val, ok := c.Get(1); val == nil || val.(int) != 1 || !ok {
 			t.Fatal("set/get returned wrong value")
 		}
-	} else {
-		if val, ok := c.Get(1); val != nil || ok {
-			t.Fatal("set was dropped but value still added")
-		}
+	} else if val, ok := c.Get(1); val != nil || ok {
+		t.Fatal("set was dropped but value still added")
 	}
 	c.Set(1, 2, 2)
 	val, ok := c.store.Get(z.KeyToHash(1))

policy.go

@@ -335,7 +335,7 @@ func (p *tinyLFU) Push(keys []uint64) {
 func (p *tinyLFU) Estimate(key uint64) int64 {
 	hits := p.freq.Estimate(key)
 	if p.door.Has(key) {
-		hits += 1
+		hits++
 	}
 	return hits
 }

z/rtutil_test.go

@@ -53,7 +53,6 @@ func SipHash(p []byte) (l, h uint64) {
 
 	// Compression.
 	for len(p) >= 8 {
-
 		m := uint64(p[0]) | uint64(p[1])<<8 | uint64(p[2])<<16 | uint64(p[3])<<24 |
 			uint64(p[4])<<32 | uint64(p[5])<<40 | uint64(p[6])<<48 | uint64(p[7])<<56
 
@@ -252,8 +251,8 @@ func SipHash(p []byte) (l, h uint64) {
 	h = hash >> 1
 	l = hash << 1 >> 1
 	return l, h
-
 }
+
 func BenchmarkNanoTime(b *testing.B) {
 	for i := 0; i < b.N; i++ {
 		NanoTime()