inomap: add benchmark

$ go test -bench=.
goos: linux
goarch: amd64
pkg: github.com/rfjakob/gocryptfs/internal/inomap
BenchmarkTranslateSingleDev-4   	202479382	         5.88 ns/op
BenchmarkTranslateManyDevs-4    	16095795	        71.9 ns/op
PASS
ok  	github.com/rfjakob/gocryptfs/internal/inomap	3.039s

1 files changed, 19 insertions, 0 deletions

diff --git a/internal/inomap/inomap_test.go b/internal/inomap/inomap_test.go
index 3c0ea7d..0349fd6 100644
--- a/internal/inomap/inomap_test.go
+++ b/internal/inomap/inomap_test.go
@@ -79,3 +79,22 @@ func TestTranslateStress(t *testing.T) {
 		t.Fail()
 	}
 }
+
+func BenchmarkTranslateSingleDev(b *testing.B) {
+	m := New(0)
+	var q QIno
+	for n := 0; n < b.N; n++ {
+		q.Ino = uint64(n % 1000)
+		m.Translate(q)
+	}
+}
+
+func BenchmarkTranslateManyDevs(b *testing.B) {
+	m := New(0)
+	var q QIno
+	for n := 0; n < b.N; n++ {
+		q.Dev = uint64(n % 10)
+		q.Ino = uint64(n % 1000)
+		m.Translate(q)
+	}
+}