clientv3: remove cancelWhenStop from lease implementation

Only have Close() cancel out outstanding goroutines. Canceling out
single-shot RPCs will mask connection close on client.Close().

clientv3/lease.go

@@ -158,13 +158,9 @@ func NewLease(c *Client) Lease {
 }
 
 func (l *lessor) Grant(ctx context.Context, ttl int64) (*LeaseGrantResponse, error) {
-	cctx, cancel := context.WithCancel(ctx)
-	done := cancelWhenStop(cancel, l.stopCtx.Done())
-	defer close(done)
-
 	for {
 		r := &pb.LeaseGrantRequest{TTL: ttl}
-		resp, err := l.remote.LeaseGrant(cctx, r)
+		resp, err := l.remote.LeaseGrant(ctx, r)
 		if err == nil {
 			gresp := &LeaseGrantResponse{
 				ResponseHeader: resp.GetHeader(),
@@ -174,20 +170,16 @@ func (l *lessor) Grant(ctx context.Context, ttl int64) (*LeaseGrantResponse, err
 			}
 			return gresp, nil
 		}
-		if isHaltErr(cctx, err) {
-			return nil, toErr(cctx, err)
+		if isHaltErr(ctx, err) {
+			return nil, toErr(ctx, err)
 		}
 	}
 }
 
 func (l *lessor) Revoke(ctx context.Context, id LeaseID) (*LeaseRevokeResponse, error) {
-	cctx, cancel := context.WithCancel(ctx)
-	done := cancelWhenStop(cancel, l.stopCtx.Done())
-	defer close(done)
-
 	for {
 		r := &pb.LeaseRevokeRequest{ID: int64(id)}
-		resp, err := l.remote.LeaseRevoke(cctx, r)
+		resp, err := l.remote.LeaseRevoke(ctx, r)
 
 		if err == nil {
 			return (*LeaseRevokeResponse)(resp), nil
@@ -199,13 +191,9 @@ func (l *lessor) Revoke(ctx context.Context, id LeaseID) (*LeaseRevokeResponse,
 }
 
 func (l *lessor) TimeToLive(ctx context.Context, id LeaseID, opts ...LeaseOption) (*LeaseTimeToLiveResponse, error) {
-	cctx, cancel := context.WithCancel(ctx)
-	done := cancelWhenStop(cancel, l.stopCtx.Done())
-	defer close(done)
-
 	for {
 		r := toLeaseTimeToLiveRequest(id, opts...)
-		resp, err := l.remote.LeaseTimeToLive(cctx, r, grpc.FailFast(false))
+		resp, err := l.remote.LeaseTimeToLive(ctx, r, grpc.FailFast(false))
 		if err == nil {
 			gresp := &LeaseTimeToLiveResponse{
 				ResponseHeader: resp.GetHeader(),
@@ -216,8 +204,8 @@ func (l *lessor) TimeToLive(ctx context.Context, id LeaseID, opts ...LeaseOption
 			}
 			return gresp, nil
 		}
-		if isHaltErr(cctx, err) {
-			return nil, toErr(cctx, err)
+		if isHaltErr(ctx, err) {
+			return nil, toErr(ctx, err)
 		}
 	}
 }
@@ -259,12 +247,8 @@ func (l *lessor) KeepAlive(ctx context.Context, id LeaseID) (<-chan *LeaseKeepAl
 }
 
 func (l *lessor) KeepAliveOnce(ctx context.Context, id LeaseID) (*LeaseKeepAliveResponse, error) {
-	cctx, cancel := context.WithCancel(ctx)
-	done := cancelWhenStop(cancel, l.stopCtx.Done())
-	defer close(done)
-
 	for {
-		resp, err := l.keepAliveOnce(cctx, id)
+		resp, err := l.keepAliveOnce(ctx, id)
 		if err == nil {
 			if resp.TTL == 0 {
 				err = rpctypes.ErrLeaseNotFound
@@ -489,20 +473,3 @@ func (ka *keepAlive) Close() {
 		close(ch)
 	}
 }
-
-// cancelWhenStop calls cancel when the given stopc fires. It returns a done chan. done
-// should be closed when the work is finished. When done fires, cancelWhenStop will release
-// its internal resource.
-func cancelWhenStop(cancel context.CancelFunc, stopc <-chan struct{}) chan<- struct{} {
-	done := make(chan struct{}, 1)
-
-	go func() {
-		select {
-		case <-stopc:
-		case <-done:
-		}
-		cancel()
-	}()
-
-	return done
-}