Merge pull request #89 from tgruben/bug-q2-double-delete

bit remove leaves internals corrupt on empty edge case

fragment_internal_test.go

@@ -3576,3 +3576,47 @@ func TestFragmentConcurrentReadWrite(t *testing.T) {
 
 	t.Logf("%d", acc)
 }
+
+func TestFragment_Bug_Q2DoubleDelete(t *testing.T) {
+	f := mustOpenFragment("i", "f", viewStandard, 0, "")
+	b := []byte{60, 48, 0, 0, 1, 0, 0, 0, 16, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 24, 0, 0, 0, 1, 0}
+	defer f.Clean(t)
+	err := f.importRoaringT(b, false)
+	if err != nil {
+		t.Fatalf("importing roaring: %v", err)
+	}
+	//check the bit
+	res := f.row(1).Columns()
+	if len(res) < 1 || f.row(1).Columns()[0] != 1 {
+		t.Fatalf("expecting 1 got: %v", res)
+	}
+	//clear the bit
+	changed, _ := f.clearBit(1, 1)
+	if !changed {
+		t.Fatalf("expected change got %v", changed)
+	}
+	//check missing
+	res = f.row(1).Columns()
+	if len(res) != 0 {
+		t.Fatalf("expected nothing got %v", res)
+	}
+	// import again
+	err = f.importRoaringT(b, false)
+	if err != nil {
+		t.Fatalf("importing roaring: %v", err)
+	}
+	//check
+	res = f.row(1).Columns()
+	if len(res) < 1 || f.row(1).Columns()[0] != 1 {
+		t.Fatalf("again expecting 1 got: %v", res)
+	}
+	changed, _ = f.clearBit(1, 1)
+	if !changed {
+		t.Fatalf("again expected change got %v", changed)
+	}
+	//check missing
+	res = f.row(1).Columns()
+	if len(res) != 0 {
+		t.Fatalf("expected nothing got %v", res)
+	}
+}

roaring/roaring.go

@@ -422,7 +422,11 @@ func (b *Bitmap) remove(v uint64) bool {
 	c := b.Containers.Get(highbits(v))
 	newC, changed := c.remove(lowbits(v))
 	if newC != c {
-		b.Containers.Put(highbits(v), newC)
+		if newC != nil {
+			b.Containers.Put(highbits(v), newC)
+		} else {
+			b.Containers.Remove(highbits(v))
+		}
 	}
 	return changed
 }