Add Files API root as best-effort pin.

Closes #2697.  Closes #2698.

License: MIT
Signed-off-by: Kevin Atkinson <k@kevina.org>

merkledag.go

@@ -357,16 +357,20 @@ func (t *Batch) Commit() error {
 // EnumerateChildren will walk the dag below the given root node and add all
 // unseen children to the passed in set.
 // TODO: parallelize to avoid disk latency perf hits?
-func EnumerateChildren(ctx context.Context, ds DAGService, root *Node, set key.KeySet) error {
+func EnumerateChildren(ctx context.Context, ds DAGService, root *Node, set key.KeySet, bestEffort bool) error {
 	for _, lnk := range root.Links {
 		k := key.Key(lnk.Hash)
 		if !set.Has(k) {
 			set.Add(k)
 			child, err := ds.Get(ctx, k)
 			if err != nil {
+				if bestEffort && err == ErrNotFound {
+					continue
+				} else {
 					return err
 				}
-			err = EnumerateChildren(ctx, ds, child, set)
+			}
+			err = EnumerateChildren(ctx, ds, child, set, bestEffort)
 			if err != nil {
 				return err
 			}

merkledag_test.go

@@ -292,7 +292,7 @@ func TestFetchGraph(t *testing.T) {
 	offline_ds := NewDAGService(bs)
 	ks := key.NewKeySet()
 
-	err = EnumerateChildren(context.Background(), offline_ds, root, ks)
+	err = EnumerateChildren(context.Background(), offline_ds, root, ks, false)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -309,7 +309,7 @@ func TestEnumerateChildren(t *testing.T) {
 	}
 
 	ks := key.NewKeySet()
-	err = EnumerateChildren(context.Background(), ds, root, ks)
+	err = EnumerateChildren(context.Background(), ds, root, ks, false)
 	if err != nil {
 		t.Fatal(err)
 	}