Don't use a separate LinkService for DAGService.GetLinks()

Instead make LinkService a part of DAGService.  The LinkService is now
simply an interface that DAGService implements.  Also provide a
GetOfflineLinkService() method that the GC uses to get an offline
instance.

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

core/core.go

@@ -94,15 +94,14 @@ type IpfsNode struct {
 	PrivateKey ic.PrivKey // the local node's private Key
 
 	// Services
-	Peerstore   pstore.Peerstore     // storage for other Peer instances
-	Blockstore  bstore.GCBlockstore  // the block store (lower level)
-	Blocks      *bserv.BlockService  // the block service, get/add blocks.
-	DAG         merkledag.DAGService // the merkle dag service, get/add objects.
-	LinkService merkledag.LinkService
-	Resolver    *path.Resolver // the path resolution system
-	Reporter    metrics.Reporter
-	Discovery   discovery.Service
-	FilesRoot   *mfs.Root
+	Peerstore  pstore.Peerstore     // storage for other Peer instances
+	Blockstore bstore.GCBlockstore  // the block store (lower level)
+	Blocks     *bserv.BlockService  // the block service, get/add blocks.
+	DAG        merkledag.DAGService // the merkle dag service, get/add objects.
+	Resolver   *path.Resolver       // the path resolution system
+	Reporter   metrics.Reporter
+	Discovery  discovery.Service
+	FilesRoot  *mfs.Root
 
 	// Online
 	PeerHost     p2phost.Host        // the network host (server+client)

core/corerepo/gc.go

@@ -90,7 +90,7 @@ func GarbageCollect(n *core.IpfsNode, ctx context.Context) error {
 	if err != nil {
 		return err
 	}
-	rmed, err := gc.GC(ctx, n.Blockstore, n.LinkService, n.Pinning, roots)
+	rmed, err := gc.GC(ctx, n.Blockstore, n.DAG, n.Pinning, roots)
 	if err != nil {
 		return err
 	}
@@ -113,7 +113,7 @@ func GarbageCollectAsync(n *core.IpfsNode, ctx context.Context) (<-chan *KeyRemo
 	if err != nil {
 		return nil, err
 	}
-	rmed, err := gc.GC(ctx, n.Blockstore, n.LinkService, n.Pinning, roots)
+	rmed, err := gc.GC(ctx, n.Blockstore, n.DAG, n.Pinning, roots)
 	if err != nil {
 		return nil, err
 	}

core/coreunix/add_test.go

@@ -98,7 +98,7 @@ func TestAddGCLive(t *testing.T) {
 	gcstarted := make(chan struct{})
 	go func() {
 		defer close(gcstarted)
-		gcchan, err := gc.GC(context.Background(), node.Blockstore, node.LinkService, node.Pinning, nil)
+		gcchan, err := gc.GC(context.Background(), node.Blockstore, node.DAG, node.Pinning, nil)
 		if err != nil {
 			log.Error("GC ERROR:", err)
 			errs <- err

exchange/bitswap/bitswap.go

@@ -422,3 +422,7 @@ func (bs *Bitswap) GetWantlist() []key.Key {
 	}
 	return out
 }
+
+func (bs *Bitswap) IsOnline() bool {
+	return true
+}

exchange/interface.go

@@ -22,5 +22,7 @@ type Interface interface { // type Exchanger interface
 	// available on the network?
 	HasBlock(blocks.Block) error
 
+	IsOnline() bool
+
 	io.Closer
 }

exchange/offline/offline.go

@@ -67,3 +67,7 @@ func (e *offlineExchange) GetBlocks(ctx context.Context, ks []key.Key) (<-chan b
 	}()
 	return out, nil
 }
+
+func (e *offlineExchange) IsOnline() bool {
+	return false
+}

merkledag/merkledag.go

@@ -7,6 +7,7 @@ import (
 	"sync"
 
 	bserv "github.com/ipfs/go-ipfs/blockservice"
+	offline "github.com/ipfs/go-ipfs/exchange/offline"
 	key "gx/ipfs/QmYEoKZXHoAToWfhGF3vryhMn3WWhE1o2MasQ8uzY5iDi9/go-key"
 
 	"context"
@@ -23,21 +24,21 @@ type DAGService interface {
 	Get(context.Context, *cid.Cid) (*Node, error)
 	Remove(*Node) error
 
-	// Return all links for a node, may be more effect than
-	// calling Get
-	GetLinks(context.Context, *cid.Cid) ([]*Link, error)
-
 	// GetDAG returns, in order, all the single leve child
 	// nodes of the passed in node.
 	GetMany(context.Context, []*cid.Cid) <-chan *NodeOption
 
 	Batch() *Batch
+
+	LinkService
 }
 
-// A LinkService returns the links for a node if they are available
-// locally without having to retrieve the block from the datastore.
 type LinkService interface {
-	Get(*cid.Cid) ([]*Link, error)
+	// Return all links for a node, may be more effect than
+	// calling Get in DAGService
+	GetLinks(context.Context, *cid.Cid) ([]*Link, error)
+
+	GetOfflineLinkService() LinkService
 }
 
 func NewDAGService(bs *bserv.BlockService) *dagService {
@@ -50,8 +51,7 @@ func NewDAGService(bs *bserv.BlockService) *dagService {
 // TODO: should cache Nodes that are in memory, and be
 //       able to free some of them when vm pressure is high
 type dagService struct {
-	Blocks      *bserv.BlockService
-	LinkService LinkService
+	Blocks *bserv.BlockService
 }
 
 // Add adds a node to the dagService, storing the block in the BlockService
@@ -105,19 +105,22 @@ func (n *dagService) Get(ctx context.Context, c *cid.Cid) (*Node, error) {
 }
 
 func (n *dagService) GetLinks(ctx context.Context, c *cid.Cid) ([]*Link, error) {
-	if n.LinkService != nil {
-		links, err := n.LinkService.Get(c)
-		if err == nil {
-			return links, nil
-		}
-	}
 	node, err := n.Get(ctx, c)
 	if err != nil {
 		return nil, err
 	}
 	return node.Links, nil
 }
 
+func (n *dagService) GetOfflineLinkService() LinkService {
+	if n.Blocks.Exchange.IsOnline() {
+		bsrv := bserv.New(n.Blocks.Blockstore, offline.Exchange(n.Blocks.Blockstore))
+		return NewDAGService(bsrv)
+	} else {
+		return n
+	}
+}
+
 func (n *dagService) Remove(nd *Node) error {
 	return n.Blocks.DeleteObject(nd)
 }
@@ -391,7 +394,7 @@ func legacyCidFromLink(lnk *Link) *cid.Cid {
 // 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, links []*Link, visit func(*cid.Cid) bool, bestEffort bool) error {
+func EnumerateChildren(ctx context.Context, ds LinkService, links []*Link, visit func(*cid.Cid) bool, bestEffort bool) error {
 	for _, lnk := range links {
 		c := legacyCidFromLink(lnk)
 		if visit(c) {

pin/gc/gc.go

@@ -2,8 +2,6 @@ package gc
 
 import (
 	bstore "github.com/ipfs/go-ipfs/blocks/blockstore"
-	bserv "github.com/ipfs/go-ipfs/blockservice"
-	offline "github.com/ipfs/go-ipfs/exchange/offline"
 	dag "github.com/ipfs/go-ipfs/merkledag"
 	pin "github.com/ipfs/go-ipfs/pin"
 	key "gx/ipfs/QmYEoKZXHoAToWfhGF3vryhMn3WWhE1o2MasQ8uzY5iDi9/go-key"
@@ -27,11 +25,9 @@ var log = logging.Logger("gc")
 func GC(ctx context.Context, bs bstore.GCBlockstore, ls dag.LinkService, pn pin.Pinner, bestEffortRoots []*cid.Cid) (<-chan key.Key, error) {
 	unlocker := bs.GCLock()
 
-	bsrv := bserv.New(bs, offline.Exchange(bs))
-	ds := dag.NewDAGService(bsrv)
-	ds.LinkService = ls
+	ls = ls.GetOfflineLinkService()
 
-	gcs, err := ColoredSet(ctx, pn, ds, bestEffortRoots)
+	gcs, err := ColoredSet(ctx, pn, ls, bestEffortRoots)
 	if err != nil {
 		return nil, err
 	}
@@ -72,16 +68,16 @@ func GC(ctx context.Context, bs bstore.GCBlockstore, ls dag.LinkService, pn pin.
 	return output, nil
 }
 
-func Descendants(ctx context.Context, ds dag.DAGService, set key.KeySet, roots []*cid.Cid, bestEffort bool) error {
+func Descendants(ctx context.Context, ls dag.LinkService, set key.KeySet, roots []*cid.Cid, bestEffort bool) error {
 	for _, c := range roots {
 		set.Add(key.Key(c.Hash()))
-		links, err := ds.GetLinks(ctx, c)
+		links, err := ls.GetLinks(ctx, c)
 		if err != nil {
 			return err
 		}
 
 		// EnumerateChildren recursively walks the dag and adds the keys to the given set
-		err = dag.EnumerateChildren(ctx, ds, links, func(c *cid.Cid) bool {
+		err = dag.EnumerateChildren(ctx, ls, links, func(c *cid.Cid) bool {
 			k := key.Key(c.Hash())
 			seen := set.Has(k)
 			if seen {
@@ -98,16 +94,16 @@ func Descendants(ctx context.Context, ds dag.DAGService, set key.KeySet, roots [
 	return nil
 }
 
-func ColoredSet(ctx context.Context, pn pin.Pinner, ds dag.DAGService, bestEffortRoots []*cid.Cid) (key.KeySet, error) {
+func ColoredSet(ctx context.Context, pn pin.Pinner, ls dag.LinkService, bestEffortRoots []*cid.Cid) (key.KeySet, error) {
 	// KeySet currently implemented in memory, in the future, may be bloom filter or
 	// disk backed to conserve memory.
 	gcs := key.NewKeySet()
-	err := Descendants(ctx, ds, gcs, pn.RecursiveKeys(), false)
+	err := Descendants(ctx, ls, gcs, pn.RecursiveKeys(), false)
 	if err != nil {
 		return nil, err
 	}
 
-	err = Descendants(ctx, ds, gcs, bestEffortRoots, true)
+	err = Descendants(ctx, ls, gcs, bestEffortRoots, true)
 	if err != nil {
 		return nil, err
 	}
@@ -116,7 +112,7 @@ func ColoredSet(ctx context.Context, pn pin.Pinner, ds dag.DAGService, bestEffor
 		gcs.Add(key.Key(k.Hash()))
 	}
 
-	err = Descendants(ctx, ds, gcs, pn.InternalPins(), false)
+	err = Descendants(ctx, ls, gcs, pn.InternalPins(), false)
 	if err != nil {
 		return nil, err
 	}

pin/pin.go

@@ -521,7 +521,7 @@ func (p *pinner) PinWithMode(c *cid.Cid, mode PinMode) {
 	}
 }
 
-func hasChild(ds mdag.DAGService, links []*mdag.Link, child key.Key) (bool, error) {
+func hasChild(ds mdag.LinkService, links []*mdag.Link, child key.Key) (bool, error) {
 	for _, lnk := range links {
 		c := cid.NewCidV0(lnk.Hash)
 		if key.Key(c.Hash()) == child {