fix Indices.Sort; add test

scionproto · Jun 24, 2020 · 974cfc2 · 974cfc2
1 parent 6984151
commit 974cfc2
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Showing 3 changed files with 20 additions and 10 deletions.
diff --git a/go/cs/reservation/segment/index.go b/go/cs/reservation/segment/index.go
@@ -100,13 +100,16 @@ func (idxs Indices) Len() int                                     { return len(i
 func (idxs Indices) GetIndexNumber(i int) reservation.IndexNumber { return idxs[i].Idx }
 func (idxs Indices) GetExpiration(i int) time.Time                { return idxs[i].Expiration }
 
-// Sort sorts these Indices.
+// Sort sorts these Indices according to their index number modulo 16, e.g. [14, 15, 0, 1].
 func (idxs *Indices) Sort() {
 	if len(*idxs) < 2 {
 		return
 	}
 	sort.Slice(*idxs, func(i, j int) bool {
-		return (*idxs)[i].Idx < (*idxs)[j].Idx
+		a, b := (*idxs)[i], (*idxs)[j]
+		distance := b.Idx.Sub(a.Idx)
+		return a.Expiration.Before(b.Expiration) ||
+			(a.Expiration.Equal(b.Expiration) && distance < 3)
 	})
 	// find a discontinuity and rotate
 	i := 1

diff --git a/go/cs/reservation/segment/index_test.go b/go/cs/reservation/segment/index_test.go
@@ -21,6 +21,7 @@ import (
 
 	"github.com/stretchr/testify/require"
 
+	base "github.com/scionproto/scion/go/cs/reservation"
 	"github.com/scionproto/scion/go/cs/reservation/segment"
 	"github.com/scionproto/scion/go/lib/colibri/reservation"
 )
@@ -54,19 +55,18 @@ func TestIndicesSort(t *testing.T) {
 func newIndices(idxs ...int) segment.Indices {
 	indices := make(segment.Indices, len(idxs))
 	for i, idx := range idxs {
-		idx := segment.NewIndex(reservation.IndexNumber(idx), time.Unix(1, 0), segment.IndexPending,
-			reservation.BWCls(1), reservation.BWCls(1), reservation.BWCls(1), &reservation.Token{})
+		expTime := time.Unix(int64(i/3+1), 0)
+		idx := segment.NewIndex(reservation.IndexNumber(idx), expTime,
+			segment.IndexPending, reservation.BWCls(1), reservation.BWCls(1), reservation.BWCls(1),
+			&reservation.Token{})
 		indices[i] = *idx
 	}
 	return indices
 }
 
 func checkIndicesSorted(t *testing.T, idxs segment.Indices) {
 	t.Helper()
-	if len(idxs) < 2 {
-		return
-	}
-	for i := 1; i < len(idxs); i++ {
-		require.Equal(t, idxs[i-1].Idx.Add(1), idxs[i].Idx)
-	}
+	// validate according to valid indices criteria
+	err := base.ValidateIndices(idxs)
+	require.NoError(t, err)
 }
diff --git a/go/lib/colibri/reservation/types_test.go b/go/lib/colibri/reservation/types_test.go
@@ -108,6 +108,13 @@ func TestIndexNumberArithmetic(t *testing.T) {
 	require.Equal(t, IndexNumber(0), x)
 	x = idx.Sub(IndexNumber(2))
 	require.Equal(t, IndexNumber(15), x)
+	// distance from 2 to 0 = 0 - 2 = 14 mod 16
+	x = IndexNumber(2)
+	distance := IndexNumber(0).Sub(x)
+	require.Equal(t, IndexNumber(14), distance)
+	// distance from 2 to 4
+	distance = IndexNumber(4).Sub(x)
+	require.Equal(t, IndexNumber(2), distance)
 }
 
 func TestValidatePathType(t *testing.T) {