cleanup, use a workgroup over channels

exchange/bitswap/bitswap.go

@@ -3,6 +3,7 @@
 package bitswap
 
 import (
+	"sync"
 	"time"
 
 	context "github.com/jbenet/go-ipfs/Godeps/_workspace/src/code.google.com/p/go.net/context"
@@ -180,8 +181,9 @@ func (bs *bitswap) sendWantListTo(ctx context.Context, peers <-chan peer.Peer) e
 }
 
 func (bs *bitswap) sendWantlistToProviders(ctx context.Context, ks []u.Key) {
-	done := make(chan struct{})
+	wg := sync.WaitGroup{}
 	for _, k := range ks {
+		wg.Add(1)
 		go func(k u.Key) {
 			providers := bs.routing.FindProvidersAsync(ctx, k, maxProvidersPerRequest)
 
@@ -189,12 +191,10 @@ func (bs *bitswap) sendWantlistToProviders(ctx context.Context, ks []u.Key) {
 			if err != nil {
 				log.Errorf("error sending wantlist: %s", err)
 			}
-			done <- struct{}{}
+			wg.Done()
 		}(k)
 	}
-	for _ = range ks {
-		<-done
-	}
+	wg.Wait()
 }
 
 // TODO ensure only one active request per key
@@ -255,6 +255,7 @@ func (bs *bitswap) HasBlock(ctx context.Context, blk *blocks.Block) error {
 	return bs.routing.Provide(ctx, blk.Key())
 }
 
+// receiveBlock handles storing the block in the blockstore and calling HasBlock
 func (bs *bitswap) receiveBlock(ctx context.Context, block *blocks.Block) {
 	// TODO verify blocks?
 	if err := bs.blockstore.Put(block); err != nil {

merkledag/merkledag.go

@@ -28,7 +28,10 @@ type DAGService interface {
 	AddRecursive(*Node) error
 	Get(u.Key) (*Node, error)
 	Remove(*Node) error
-	GetKeysAsync(context.Context, *Node) <-chan *Node
+
+	// GetDAG returns, in order, all the single leve child
+	// nodes of the passed in node.
+	GetDAG(context.Context, *Node) <-chan *Node
 }
 
 func NewDAGService(bs *bserv.BlockService) DAGService {
@@ -298,10 +301,10 @@ func FindLink(n *Node, k u.Key, found []*Node) (int, error) {
 	return -1, u.ErrNotFound
 }
 
-// GetKeysAsync will fill out all of the links of the given Node.
+// GetDAG will fill out all of the links of the given Node.
 // It returns a channel of nodes, which the caller can receive
 // all the child nodes of 'root' on, in proper order.
-func (ds *dagService) GetKeysAsync(ctx context.Context, root *Node) <-chan *Node {
+func (ds *dagService) GetDAG(ctx context.Context, root *Node) <-chan *Node {
 	sig := make(chan *Node)
 	go func() {
 		var keys []u.Key

unixfs/io/dagreader.go

@@ -40,7 +40,7 @@ func NewDagReader(n *mdag.Node, serv mdag.DAGService) (io.Reader, error) {
 	case ftpb.Data_File:
 		var fetchChan <-chan *mdag.Node
 		if serv != nil {
-			fetchChan = serv.GetKeysAsync(context.TODO(), n)
+			fetchChan = serv.GetDAG(context.TODO(), n)
 		}
 		return &DagReader{
 			node:      n,
@@ -62,6 +62,7 @@ func (dr *DagReader) precalcNextBuf() error {
 	var nxt *mdag.Node
 	var ok bool
 
+	// TODO: require non-nil dagservice, use offline bitswap exchange
 	if dr.serv == nil {
 		// Only used when fetchChan is nil,
 		// which only happens when passed in a nil dagservice