fix rand usage

crdt.go

@@ -55,8 +55,6 @@ var (
 	ErrNoMoreBroadcast = errors.New("receiving blocks aborted since no new blocks will be broadcasted")
 )
 
-var randGen = rand.New(rand.NewSource(time.Now().UnixNano()))
-
 // A Broadcaster provides a way to send (notify) an opaque payload to
 // all replicas and to retrieve payloads broadcasted.
 type Broadcaster interface {
@@ -465,6 +463,7 @@ func randomizeInterval(d time.Duration) time.Duration {
 	// 30% of the configured interval
 	leeway := (d * 30 / 100)
 	// A random number between -leeway|+leeway
+	randGen := rand.New(rand.NewSource(time.Now().UnixNano()))
 	randomInterval := time.Duration(randGen.Int63n(int64(leeway*2))) - leeway
 	return d + randomInterval
 }

crdt_test.go

@@ -3,6 +3,7 @@ package crdt
 import (
 	"context"
 	"fmt"
+	"math/rand"
 	"os"
 	"sync"
 	"sync/atomic"
@@ -119,16 +120,20 @@ func newBroadcasters(t testing.TB, n int) ([]*mockBroadcaster, context.CancelFun
 
 func (mb *mockBroadcaster) Broadcast(data []byte) error {
 	var wg sync.WaitGroup
+
+	randg := rand.New(rand.NewSource(time.Now().UnixNano()))
+
 	for i, ch := range mb.chans {
-		n := randGen.Intn(100)
+		n := randg.Intn(100)
 		if n < mb.dropProb {
 			continue
 		}
 		wg.Add(1)
-		go func() {
+		go func(i int) {
 			defer wg.Done()
+			randg := rand.New(rand.NewSource(int64(i)))
 			// randomize when we send a little bit
-			if randGen.Intn(100) < 30 {
+			if randg.Intn(100) < 30 {
 				// Sleep for a very small time that will
 				// effectively be pretty random
 				time.Sleep(time.Nanosecond)
@@ -142,7 +147,7 @@ func (mb *mockBroadcaster) Broadcast(data []byte) error {
 			case <-timer.C:
 				mb.t.Errorf("broadcasting to %d timed out", i)
 			}
-		}()
+		}(i)
 		wg.Wait()
 	}
 	return nil
@@ -306,6 +311,7 @@ func TestCRDT(t *testing.T) {
 func TestCRDTReplication(t *testing.T) {
 	ctx := context.Background()
 	nItems := 50
+	randGen := rand.New(rand.NewSource(time.Now().UnixNano()))
 
 	replicas, closeReplicas := makeReplicas(t, nil)
 	defer closeReplicas()

heads_test.go

@@ -3,9 +3,11 @@ package crdt
 import (
 	"bytes"
 	"context"
+	"math/rand"
 	"reflect"
 	"sort"
 	"testing"
+	"time"
 
 	"github.com/ipfs/go-cid"
 	ds "github.com/ipfs/go-datastore"
@@ -15,6 +17,8 @@ import (
 
 var headsTestNS = ds.NewKey("headstest")
 
+var randg = rand.New(rand.NewSource(time.Now().UnixNano()))
+
 // TODO we should also test with a non-batching store
 func newTestHeads(t *testing.T) *heads {
 	t.Helper()
@@ -32,7 +36,7 @@ func newTestHeads(t *testing.T) *heads {
 func newCID(t *testing.T) cid.Cid {
 	t.Helper()
 	var buf [32]byte
-	_, _ = randGen.Read(buf[:])
+	_, _ = randg.Read(buf[:])
 
 	mh, err := multihash.Sum(buf[:], multihash.SHA2_256, -1)
 	if err != nil {
@@ -56,7 +60,7 @@ func TestHeadsBasic(t *testing.T) {
 	cidHeights := make(map[cid.Cid]uint64)
 	numHeads := 5
 	for i := 0; i < numHeads; i++ {
-		c, height := newCID(t), uint64(randGen.Int())
+		c, height := newCID(t), uint64(randg.Int())
 		cidHeights[c] = height
 		err := heads.Add(ctx, c, height)
 		if err != nil {
@@ -67,7 +71,7 @@ func TestHeadsBasic(t *testing.T) {
 	assertHeads(t, heads, cidHeights)
 
 	for c := range cidHeights {
-		newC, newHeight := newCID(t), uint64(randGen.Int())
+		newC, newHeight := newCID(t), uint64(randg.Int())
 		err := heads.Replace(ctx, c, newC, newHeight)
 		if err != nil {
 			t.Fatal(err)