Improve internal/ziplist TestSkiplistChaos execution time (heroiclabs…

…#1257)

It also makes it actually chaotic (previous PRNG seed was always the same).

internal/skiplist/skiplist_chaos_test.go

@@ -5,6 +5,7 @@ import (
 	"math/rand"
 	"sort"
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/require"
 )
@@ -37,73 +38,83 @@ func (ti testInterface) Less(other interface{}) bool {
 }
 
 func TestSkiplistChaos(t *testing.T) {
-	rnd := rand.New(rand.NewSource(0))
+	t.Parallel()
 	iterations := 20
 
+	seed := time.Now().UnixNano()
+
+	rndMain := rand.New(rand.NewSource(seed))
+
 	for i := 0; i < iterations; i++ {
-		numUsers := rnd.Intn(2000) + 100
-		users := make([]string, numUsers)
+		i := i
+		numUsers := rndMain.Intn(2000) + 100
+		numOps := rndMain.Intn(100_000) + 100
+		numLists := rndMain.Intn(47) + 3
+		name := fmt.Sprintf("iteration=%d,users=%d,ops=%d,lists=%d", i, numUsers, numOps, numLists)
 
-		for j := 0; j < numUsers; j++ {
-			users[j] = randString(t, rnd)
-		}
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
 
-		numOps := rnd.Intn(100_000) + 100
-		ops := make([]testInterface, numOps)
+			// Setup a new PRNG for this subtest
+			rnd := rand.New(rand.NewSource(seed + int64(i)))
 
-		for j := 0; j < numOps; j++ {
-			id := users[rnd.Intn(numUsers)]
-			ops[j] = testInterface{
-				id:  id,
-				val: rnd.Intn(999) + 1,
+			users := make([]string, numUsers)
+			for j := 0; j < numUsers; j++ {
+				users[j] = randString(t, rnd)
 			}
-		}
 
-		numLists := rnd.Intn(47) + 3
-		lists := make([]*SkipList, numLists)
-		userOps := make([]map[string]testInterface, numLists)
+			ops := make([]testInterface, numOps)
+			for j := 0; j < numOps; j++ {
+				id := users[rnd.Intn(numUsers)]
+				ops[j] = testInterface{
+					id:  id,
+					val: rnd.Intn(999) + 1,
+				}
+			}
 
-		fmt.Printf("** iteration=%v, users=%v, ops=%v, lists=%v\n", i, numUsers, numOps, numLists)
+			lists := make([]*SkipList, numLists)
+			userOps := make([]map[string]testInterface, numLists)
 
-		// Populate lists
-		for j := 0; j < numLists; j++ {
-			rnd.Shuffle(len(ops), func(i, j int) {
-				ops[i], ops[j] = ops[j], ops[i]
-			})
+			// Populate lists
+			for j := 0; j < numLists; j++ {
+				rnd.Shuffle(len(ops), func(i, j int) {
+					ops[i], ops[j] = ops[j], ops[i]
+				})
 
-			userOps[j] = make(map[string]testInterface, numUsers)
+				userOps[j] = make(map[string]testInterface, numUsers)
 
-			lists[j] = New()
-			for _, op := range ops {
-				oldOp, ok := userOps[j][op.id]
-				if ok {
-					lists[j].Delete(oldOp)
-					op.val += oldOp.val
-				}
+				lists[j] = New()
+				for _, op := range ops {
+					oldOp, ok := userOps[j][op.id]
+					if ok {
+						lists[j].Delete(oldOp)
+						op.val += oldOp.val
+					}
 
-				lists[j].Insert(op)
-				userOps[j][op.id] = op
+					lists[j].Insert(op)
+					userOps[j][op.id] = op
+				}
 			}
-		}
 
-		// Now verify
-		for j, sl := range lists {
-			listOps := make([]testInterface, 0, len(ops))
+			// Now verify
+			for j, sl := range lists {
+				listOps := make([]testInterface, 0, len(ops))
 
-			for _, op := range userOps[j] {
-				listOps = append(listOps, op)
-			}
+				for _, op := range userOps[j] {
+					listOps = append(listOps, op)
+				}
 
-			sort.Slice(listOps, func(i, j int) bool {
-				return listOps[i].Less(listOps[j])
-			})
+				sort.Slice(listOps, func(i, j int) bool {
+					return listOps[i].Less(listOps[j])
+				})
 
-			for idx, op := range listOps {
-				rank := idx + 1
+				for idx, op := range listOps {
+					rank := idx + 1
 
-				listRank := sl.GetRank(op)
-				require.Equal(t, rank, listRank, "list %d, unexpected rank for op %+v", j, op)
+					listRank := sl.GetRank(op)
+					require.Equal(t, rank, listRank, "list %d, unexpected rank for op %+v", j, op)
+				}
 			}
-		}
+		})
 	}
 }