tapfreighter: rename field exportReqs to outboundParcels for clarity

This commit also adds a field doc comment.

tapfreighter/chain_porter.go

@@ -110,7 +110,9 @@ type ChainPorter struct {
 
 	cfg *ChainPorterConfig
 
-	exportReqs chan Parcel
+	// outboundParcels is a channel that carries outbound parcels that need
+	// to be processed by the main porter goroutine.
+	outboundParcels chan Parcel
 
 	// subscribers is a map of components that want to be notified on new
 	// events, keyed by their subscription ID.
@@ -129,9 +131,9 @@ func NewChainPorter(cfg *ChainPorterConfig) *ChainPorter {
 		map[uint64]*fn.EventReceiver[fn.Event],
 	)
 	return &ChainPorter{
-		cfg:         cfg,
-		exportReqs:  make(chan Parcel),
-		subscribers: subscribers,
+		cfg:             cfg,
+		outboundParcels: make(chan Parcel),
+		subscribers:     subscribers,
 		ContextGuard: &fn.ContextGuard{
 			DefaultTimeout: tapgarden.DefaultTimeout,
 			Quit:           make(chan struct{}),
@@ -151,8 +153,8 @@ func (p *ChainPorter) Start() error {
 		go p.mainEventLoop()
 
 		// Identify any pending parcels that need to be resumed and add
-		// them to the exportReqs channel so they can be processed by
-		// the main porter goroutine.
+		// them to the outboundParcels channel so they can be processed
+		// by the main porter goroutine.
 		ctx, cancel := p.WithCtxQuit()
 		defer cancel()
 		outboundParcels, err := p.cfg.ExportLog.PendingParcels(ctx)
@@ -172,7 +174,7 @@ func (p *ChainPorter) Start() error {
 			// At this point the asset porter should be running.
 			// It should therefore pick up the pending parcels from
 			// the channel and attempt to deliver them.
-			p.exportReqs <- NewPendingParcel(outboundParcel)
+			p.outboundParcels <- NewPendingParcel(outboundParcel)
 		}
 	})
 
@@ -211,7 +213,7 @@ func (p *ChainPorter) RequestShipment(req Parcel) (*OutboundParcel, error) {
 		return nil, fmt.Errorf("failed to validate parcel: %w", err)
 	}
 
-	if !fn.SendOrQuit(p.exportReqs, req, p.Quit) {
+	if !fn.SendOrQuit(p.outboundParcels, req, p.Quit) {
 		return nil, fmt.Errorf("ChainPorter shutting down")
 	}
 
@@ -247,16 +249,17 @@ func (p *ChainPorter) mainEventLoop() {
 
 	for {
 		select {
-		case req := <-p.exportReqs:
-			// The request either has a destination address we want
-			// to send to, or a send package is already initialized.
-			sendPkg := req.pkg()
+		case outboundParcel := <-p.outboundParcels:
+			// The outbound parcel either has a destination address
+			// we want to send to, or a send package is already
+			// initialized.
+			sendPkg := outboundParcel.pkg()
 
 			// Advance the state machine for this package as far as
 			// possible in its own goroutine. The status will be
 			// reported through the different channels of the send
 			// package.
-			go p.advanceState(sendPkg, req.kit())
+			go p.advanceState(sendPkg, outboundParcel.kit())
 
 		case <-p.Quit:
 			return