[FAB-12034] Fix data races in pull_test.go

The pull test has tests which have instances of puller, that send each
other messages via a common membership map.

This map is populated at the creation of each instance via having
each instance register itself into the map.

The instance (which is test code) - spawns a goroutine at its creation,
which schedules the production code and the latter accesses the said map.

This makes it an unsafe memory access, and hence a data race occurs.

I simply extractd the goroutine to its own start method, and made all
tests first create the instances (which involves the write to the map)
and only afterwards - start the goroutine, and thus - there is a happens
before relation and the golang memory model is happy.

FAB-12034 #done

Change-Id: I976e9161873d1a7022b0263189af4cc2d3151001
Signed-off-by: yacovm <yacovm@il.ibm.com>

Author: yacovm

gossip/gossip/pull/pullstore_test.go

@@ -71,6 +71,8 @@ type pullInstance struct {
 	msgChan       chan *pullMsg
 	peer2PullInst map[string]*pullInstance
 	stopChan      chan struct{}
+	pullAdapter   *PullAdapter
+	config        Config
 }
 
 func (p *pullInstance) Send(msg *proto.SignedGossipMessage, peers ...*comm.RemotePeer) {
@@ -91,6 +93,20 @@ func (p *pullInstance) GetMembership() []discovery.NetworkMember {
 	return members
 }
 
+func (p *pullInstance) start() {
+	p.mediator = NewPullMediator(p.config, p.pullAdapter)
+	go func() {
+		for {
+			select {
+			case <-p.stopChan:
+				return
+			case msg := <-p.msgChan:
+				p.mediator.HandleMessage(msg)
+			}
+		}
+	}()
+}
+
 func (p *pullInstance) stop() {
 	p.mediator.Stop()
 	p.stopChan <- struct{}{}
@@ -139,31 +155,23 @@ func createPullInstanceWithFilters(endpoint string, peer2PullInst map[string]*pu
 	blockConsumer := func(msg *proto.SignedGossipMessage) {
 		inst.items.Add(msg.GetDataMsg().Payload.SeqNum)
 	}
-	adapter := &PullAdapter{
+	inst.pullAdapter = &PullAdapter{
 		Sndr:             inst,
 		MemSvc:           inst,
 		IdExtractor:      seqNumFromMsg,
 		MsgCons:          blockConsumer,
 		EgressDigFilter:  df,
 		IngressDigFilter: digestsFilter,
 	}
-	inst.mediator = NewPullMediator(conf, adapter)
-	go func() {
-		for {
-			select {
-			case <-inst.stopChan:
-				return
-			case msg := <-inst.msgChan:
-				inst.mediator.HandleMessage(msg)
-			}
-		}
-	}()
+	inst.config = conf
+
 	return inst
 }
 
 func TestCreateAndStop(t *testing.T) {
 	t.Parallel()
 	pullInst := createPullInstance("localhost:2000", make(map[string]*pullInstance))
+	pullInst.start()
 	pullInst.stop()
 }
 
@@ -172,6 +180,8 @@ func TestRegisterMsgHook(t *testing.T) {
 	peer2pullInst := make(map[string]*pullInstance)
 	inst1 := createPullInstance("localhost:5611", peer2pullInst)
 	inst2 := createPullInstance("localhost:5612", peer2pullInst)
+	inst1.start()
+	inst2.start()
 	defer inst1.stop()
 	defer inst2.stop()
 
@@ -215,6 +225,8 @@ func TestFilter(t *testing.T) {
 	inst2 := createPullInstance("localhost:5612", peer2pullInst)
 	defer inst1.stop()
 	defer inst2.stop()
+	inst1.start()
+	inst2.start()
 
 	inst1.mediator.Add(dataMsg(0))
 	inst1.mediator.Add(dataMsg(1))
@@ -232,6 +244,8 @@ func TestAddAndRemove(t *testing.T) {
 	peer2pullInst := make(map[string]*pullInstance)
 	inst1 := createPullInstance("localhost:5611", peer2pullInst)
 	inst2 := createPullInstance("localhost:5612", peer2pullInst)
+	inst1.start()
+	inst2.start()
 	defer inst1.stop()
 	defer inst2.stop()
 
@@ -268,6 +282,8 @@ func TestDigestsFilters(t *testing.T) {
 	inst1 := createPullInstanceWithFilters("localhost:5611", make(map[string]*pullInstance), nil, df1)
 	inst2 := createPullInstance("localhost:5612", make(map[string]*pullInstance))
 	inst1ReceivedDigest := int32(0)
+	inst1.start()
+	inst2.start()
 
 	defer inst1.stop()
 	defer inst2.stop()
@@ -303,6 +319,8 @@ func TestHandleMessage(t *testing.T) {
 	t.Parallel()
 	inst1 := createPullInstance("localhost:5611", make(map[string]*pullInstance))
 	inst2 := createPullInstance("localhost:5612", make(map[string]*pullInstance))
+	inst1.start()
+	inst2.start()
 	defer inst1.stop()
 	defer inst2.stop()