fix(retrieval): resolve retrieval close event panic

Refactor ClientRetrieve command to remove the possibility of a send on close channel race condition

node/impl/client/client.go

@@ -432,6 +432,45 @@ func (a *API) ClientRetrieveWithEvents(ctx context.Context, order api.RetrievalO
 	return events, nil
 }
 
+type retrievalSubscribeEvent struct {
+	event rm.ClientEvent
+	state rm.ClientDealState
+}
+
+func readSubscribeEvents(ctx context.Context, subscribeEvents chan retrievalSubscribeEvent, events chan marketevents.RetrievalEvent) error {
+	for {
+		var subscribeEvent retrievalSubscribeEvent
+		select {
+		case <-ctx.Done():
+			return xerrors.New("Retrieval Timed Out")
+		case subscribeEvent = <-subscribeEvents:
+		}
+
+		select {
+		case <-ctx.Done():
+			return xerrors.New("Retrieval Timed Out")
+		case events <- marketevents.RetrievalEvent{
+			Event:         subscribeEvent.event,
+			Status:        subscribeEvent.state.Status,
+			BytesReceived: subscribeEvent.state.TotalReceived,
+			FundsSpent:    subscribeEvent.state.FundsSpent,
+		}:
+		}
+
+		state := subscribeEvent.state
+		switch state.Status {
+		case rm.DealStatusCompleted:
+			return nil
+		case rm.DealStatusRejected:
+			return xerrors.Errorf("Retrieval Proposal Rejected: %s", state.Message)
+		case
+			rm.DealStatusDealNotFound,
+			rm.DealStatusErrored:
+			return xerrors.Errorf("Retrieval Error: %s", state.Message)
+		}
+	}
+}
+
 func (a *API) clientRetrieve(ctx context.Context, order api.RetrievalOrder, ref *api.FileRef, events chan marketevents.RetrievalEvent) {
 	defer close(events)
 
@@ -467,33 +506,13 @@ func (a *API) clientRetrieve(ctx context.Context, order api.RetrievalOrder, ref
 		return err
 	}*/
 
-	retrievalResult := make(chan error, 1)
+	var dealID retrievalmarket.DealID
-
+	subscribeEvents := make(chan retrievalSubscribeEvent, 1)
-	var dealId retrievalmarket.DealID
-
 	unsubscribe := a.Retrieval.SubscribeToEvents(func(event rm.ClientEvent, state rm.ClientDealState) {
-		if state.PayloadCID.Equals(order.Root) && state.ID == dealId {
+		if state.PayloadCID.Equals(order.Root) && state.ID == dealID {
-
 			select {
 			case <-ctx.Done():
-				return
+			case subscribeEvents <- retrievalSubscribeEvent{event, state}:
-			case events <- marketevents.RetrievalEvent{
-				Event:         event,
-				Status:        state.Status,
-				BytesReceived: state.TotalReceived,
-				FundsSpent:    state.FundsSpent,
-			}:
-			}
-
-			switch state.Status {
-			case rm.DealStatusCompleted:
-				retrievalResult <- nil
-			case rm.DealStatusRejected:
-				retrievalResult <- xerrors.Errorf("Retrieval Proposal Rejected: %s", state.Message)
-			case
-				rm.DealStatusDealNotFound,
-				rm.DealStatusErrored:
-				retrievalResult <- xerrors.Errorf("Retrieval Error: %s", state.Message)
 			}
 		}
 	})
@@ -516,7 +535,7 @@ func (a *API) clientRetrieve(ctx context.Context, order api.RetrievalOrder, ref
 		_ = a.RetrievalStoreMgr.ReleaseStore(store)
 	}()
 
-	dealId, err = a.Retrieval.Retrieve(
+	dealID, err = a.Retrieval.Retrieve(
 		ctx,
 		order.Root,
 		params,
@@ -531,17 +550,12 @@ func (a *API) clientRetrieve(ctx context.Context, order api.RetrievalOrder, ref
 		return
 	}
 
-	select {
+	err = readSubscribeEvents(ctx, subscribeEvents, events)
-	case <-ctx.Done():
+
-		unsubscribe()
+	unsubscribe()
-		finish(xerrors.New("Retrieval Timed Out"))
+	if err != nil {
+		finish(xerrors.Errorf("Retrieve: %w", err))
 		return
-	case err := <-retrievalResult:
-		unsubscribe()
-		if err != nil {
-			finish(xerrors.Errorf("Retrieve: %w", err))
-			return
-		}
 	}
 
 	// If ref is nil, it only fetches the data into the configured blockstore.