swarm/network: remove everything related to pivot from Simulation

As the concept and the related functionality was not used anywhere.

swarm/network/simulation/node.go

@@ -241,25 +241,6 @@ func (s *Simulation) UploadSnapshot(snapshotFile string, opts ...AddNodeOption)
 	return nil
 }
 
-// SetPivotNode sets the NodeID of the network's pivot node.
-// Pivot node is just a specific node that should be treated
-// differently then other nodes in test. SetPivotNode and
-// PivotNodeID are just a convenient functions to set and
-// retrieve it.
-func (s *Simulation) SetPivotNode(id enode.ID) {
-	s.mu.Lock()
-	defer s.mu.Unlock()
-	s.pivotNodeID = &id
-}
-
-// PivotNodeID returns NodeID of the pivot node set by
-// Simulation.SetPivotNode method.
-func (s *Simulation) PivotNodeID() (id *enode.ID) {
-	s.mu.Lock()
-	defer s.mu.Unlock()
-	return s.pivotNodeID
-}
-
 // StartNode starts a node by NodeID.
 func (s *Simulation) StartNode(id enode.ID) (err error) {
 	return s.Net.Start(id)

swarm/network/simulation/node_test.go

@@ -314,45 +314,6 @@ func TestUploadSnapshot(t *testing.T) {
 	log.Debug("Done.")
 }
 
-func TestPivotNode(t *testing.T) {
-	sim := New(noopServiceFuncMap)
-	defer sim.Close()
-
-	id, err := sim.AddNode()
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	id2, err := sim.AddNode()
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	if sim.PivotNodeID() != nil {
-		t.Error("expected no pivot node")
-	}
-
-	sim.SetPivotNode(id)
-
-	pid := sim.PivotNodeID()
-
-	if pid == nil {
-		t.Error("pivot node not set")
-	} else if *pid != id {
-		t.Errorf("expected pivot node %s, got %s", id, *pid)
-	}
-
-	sim.SetPivotNode(id2)
-
-	pid = sim.PivotNodeID()
-
-	if pid == nil {
-		t.Error("pivot node not set")
-	} else if *pid != id2 {
-		t.Errorf("expected pivot node %s, got %s", id2, *pid)
-	}
-}
-
 func TestStartStopNode(t *testing.T) {
 	sim := New(noopServiceFuncMap)
 	defer sim.Close()

swarm/network/simulation/simulation.go

@@ -46,7 +46,6 @@ type Simulation struct {
 	serviceNames      []string
 	cleanupFuncs      []func()
 	buckets           map[enode.ID]*sync.Map
-	pivotNodeID       *enode.ID
 	shutdownWG        sync.WaitGroup
 	done              chan struct{}
 	mu                sync.RWMutex