Guard new leaf generation with a mutex (#166)

Author: phbnf

hammer/hammer.go

@@ -301,7 +301,10 @@ func genLeaf(n uint64, minLeafSize int) []byte {
 func newLeafGenerator(n uint64, minLeafSize int) func() []byte {
 	const dupChance = 0.1
 	nextLeaf := genLeaf(n, minLeafSize)
+	var safe sync.Mutex
 	return func() []byte {
+		safe.Lock()
+		defer safe.Unlock()
 		if rand.Float64() <= dupChance {
 			// This one will actually be unique, but the next iteration will
 			// duplicate it. In future, this duplication could be randomly