Lifecycle fixes

internal/sync/lifecycle.go

@@ -22,18 +22,13 @@ package sync
 
 import (
 	"context"
-	"errors"
 
 	"go.uber.org/atomic"
 )
 
 // LifecycleState represents `states` that a lifecycle object can be in.
 type LifecycleState int
 
-// ErrAlreadyStopped is returned by WhenRunning to escape early if a lifecycle
-// has ended already.
-var ErrAlreadyStopped = errors.New("already stopped")
-
 const (
 	// Idle indicates the Lifecycle hasn't been operated on yet.
 	Idle LifecycleState = iota
@@ -127,7 +122,7 @@ func (l *lifecycleOnce) WhenRunning(ctx context.Context) error {
 	case <-l.startCh:
 		return nil
 	case <-l.stopCh:
-		return ErrAlreadyStopped
+		return context.DeadlineExceeded
 	case <-ctx.Done():
 		return ctx.Err()
 	}

peer/x/peerheap/list_test.go

@@ -9,7 +9,6 @@ import (
 	"go.uber.org/yarpc/api/peer"
 	. "go.uber.org/yarpc/api/peer/peertest"
 	yerrors "go.uber.org/yarpc/internal/errors"
-	"go.uber.org/yarpc/internal/sync"
 
 	"github.com/golang/mock/gomock"
 	"github.com/stretchr/testify/assert"
@@ -90,7 +89,7 @@ func TestPeerHeapList(t *testing.T) {
 				StartAction{},
 				StopAction{},
 				ChooseAction{
-					ExpectedErr:         sync.ErrAlreadyStopped,
+					ExpectedErr:         context.DeadlineExceeded,
 					InputContextTimeout: 10 * time.Millisecond,
 				},
 			},

peer/x/roundrobin/list.go

@@ -211,7 +211,7 @@ func (pl *List) removeFromUnavailablePeers(p peer.Peer) {
 // Choose selects the next available peer in the round robin
 func (pl *List) Choose(ctx context.Context, req *transport.Request) (peer.Peer, func(error), error) {
 	if err := pl.once.WhenRunning(ctx); err != nil {
-		return nil, nil, peer.ErrPeerListNotStarted("RoundRobinList")
+		return nil, nil, err
 	}
 
 	for {

peer/x/roundrobin/list_test.go

@@ -221,11 +221,11 @@ func TestRoundRobinList(t *testing.T) {
 			peerListActions: []PeerListAction{
 				UpdateAction{AddedPeerIDs: []string{"1"}},
 				ChooseAction{
-					ExpectedErr:         peer.ErrPeerListNotStarted("RoundRobinList"),
+					ExpectedErr:         context.DeadlineExceeded,
 					InputContextTimeout: 10 * time.Millisecond,
 				},
 				ChooseAction{
-					ExpectedErr:         peer.ErrPeerListNotStarted("RoundRobinList"),
+					ExpectedErr:         context.DeadlineExceeded,
 					InputContextTimeout: 10 * time.Millisecond,
 				},
 			},