Localize the scope of context.WithCancel for every DAG.Get

Instead put it inside of DAG.Get.
The fix is applied only in the case when the context.WithCancel
before a DAG.Get is also used later on in the scope.

License: MIT
Signed-off-by: rht <rhtbot@gmail.com>

core/commands/ls.go

@@ -6,8 +6,6 @@ import (
 	"io"
 	"text/tabwriter"
 
-	context "github.com/ipfs/go-ipfs/Godeps/_workspace/src/golang.org/x/net/context"
-
 	cmds "github.com/ipfs/go-ipfs/commands"
 	core "github.com/ipfs/go-ipfs/core"
 	merkledag "github.com/ipfs/go-ipfs/merkledag"
@@ -80,9 +78,7 @@ it contains, with the following format:
 				Links: make([]LsLink, len(dagnode.Links)),
 			}
 			for j, link := range dagnode.Links {
-				ctx, cancel := context.WithCancel(req.Context())
+				link.Node, err = link.GetNode(req.Context(), node.DAG)
-				defer cancel()
-				link.Node, err = link.GetNode(ctx, node.DAG)
 				if err != nil {
 					res.SetError(err, cmds.ErrNormal)
 					return

core/commands/object.go

@@ -9,10 +9,8 @@ import (
 	"io/ioutil"
 	"strings"
 	"text/tabwriter"
-	"time"
 
 	mh "github.com/ipfs/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-multihash"
-	context "github.com/ipfs/go-ipfs/Godeps/_workspace/src/golang.org/x/net/context"
 
 	key "github.com/ipfs/go-ipfs/blocks/key"
 	cmds "github.com/ipfs/go-ipfs/commands"
@@ -480,14 +478,11 @@ resulting object hash.
 			return
 		}
 
-		ctx, cancel := context.WithTimeout(req.Context(), time.Second*30)
+		rnode, err := nd.DAG.Get(req.Context(), rhash)
-		rnode, err := nd.DAG.Get(ctx, rhash)
 		if err != nil {
 			res.SetError(err, cmds.ErrNormal)
-			cancel()
 			return
 		}
-		cancel()
 
 		action := req.Arguments()[1]
 

core/commands/unixfs/ls.go

@@ -7,8 +7,6 @@ import (
 	"sort"
 	"text/tabwriter"
 
-	context "github.com/ipfs/go-ipfs/Godeps/_workspace/src/golang.org/x/net/context"
-
 	cmds "github.com/ipfs/go-ipfs/commands"
 	core "github.com/ipfs/go-ipfs/core"
 	path "github.com/ipfs/go-ipfs/path"
@@ -110,9 +108,7 @@ size is the IPFS link size.
 				links := make([]LsLink, len(merkleNode.Links))
 				output.Objects[hash].Links = links
 				for i, link := range merkleNode.Links {
-					getCtx, cancel := context.WithCancel(ctx)
+					link.Node, err = link.GetNode(ctx, node.DAG)
-					defer cancel()
-					link.Node, err = link.GetNode(getCtx, node.DAG)
 					if err != nil {
 						res.SetError(err, cmds.ErrNormal)
 						return

core/corehttp/gateway_handler.go

@@ -367,8 +367,7 @@ func (i *gatewayHandler) putHandler(w http.ResponseWriter, r *http.Request) {
 		}
 	}
 
-	err = i.node.DAG.AddRecursive(newnode)
+	if err := i.node.DAG.AddRecursive(newnode); err != nil {
-	if err != nil {
 		webError(w, "Could not add recursively new node", err, http.StatusInternalServerError)
 		return
 	}
@@ -439,8 +438,7 @@ func (i *gatewayHandler) deleteHandler(w http.ResponseWriter, r *http.Request) {
 		}
 	}
 
-	err = i.node.DAG.AddRecursive(newnode)
+	if err := i.node.DAG.AddRecursive(newnode); err != nil {
-	if err != nil {
 		webError(w, "Could not add recursively new node", err, http.StatusInternalServerError)
 		return
 	}

core/coreunix/metadata.go

@@ -1,8 +1,6 @@
 package coreunix
 
 import (
-	context "github.com/ipfs/go-ipfs/Godeps/_workspace/src/golang.org/x/net/context"
-
 	key "github.com/ipfs/go-ipfs/blocks/key"
 	core "github.com/ipfs/go-ipfs/core"
 	dag "github.com/ipfs/go-ipfs/merkledag"
@@ -12,9 +10,7 @@ import (
 func AddMetadataTo(n *core.IpfsNode, skey string, m *ft.Metadata) (string, error) {
 	ukey := key.B58KeyDecode(skey)
 
-	ctx, cancel := context.WithCancel(n.Context())
+	nd, err := n.DAG.Get(n.Context(), ukey)
-	defer cancel()
-	nd, err := n.DAG.Get(ctx, ukey)
 	if err != nil {
 		return "", err
 	}
@@ -26,8 +22,7 @@ func AddMetadataTo(n *core.IpfsNode, skey string, m *ft.Metadata) (string, error
 	}
 
 	mdnode.Data = mdata
-	err = mdnode.AddNodeLinkClean("file", nd)
+	if err := mdnode.AddNodeLinkClean("file", nd); err != nil {
-	if err != nil {
 		return "", err
 	}
 
@@ -42,9 +37,7 @@ func AddMetadataTo(n *core.IpfsNode, skey string, m *ft.Metadata) (string, error
 func Metadata(n *core.IpfsNode, skey string) (*ft.Metadata, error) {
 	ukey := key.B58KeyDecode(skey)
 
-	ctx, cancel := context.WithCancel(n.Context())
+	nd, err := n.DAG.Get(n.Context(), ukey)
-	defer cancel()
-	nd, err := n.DAG.Get(ctx, ukey)
 	if err != nil {
 		return nil, err
 	}

importer/trickle/trickledag.go

@@ -2,7 +2,6 @@ package trickle
 
 import (
 	"errors"
-	"time"
 
 	context "github.com/ipfs/go-ipfs/Godeps/_workspace/src/golang.org/x/net/context"
 
@@ -268,9 +267,7 @@ func verifyTDagRec(nd *dag.Node, depth, direct, layerRepeat int, ds dag.DAGServi
 	}
 
 	for i := 0; i < len(nd.Links); i++ {
-		ctx, cancel := context.WithTimeout(context.TODO(), time.Minute)
+		child, err := nd.Links[i].GetNode(context.TODO(), ds)
-		defer cancel()
-		child, err := nd.Links[i].GetNode(ctx, ds)
 		if err != nil {
 			return err
 		}

ipnsfs/dir.go

@@ -139,10 +139,7 @@ func (d *Directory) childDir(name string) (*Directory, error) {
 func (d *Directory) childFromDag(name string) (*dag.Node, error) {
 	for _, lnk := range d.node.Links {
 		if lnk.Name == name {
-			ctx, cancel := context.WithCancel(d.ctx)
+			return lnk.GetNode(d.ctx, d.fs.dserv)
-			defer cancel()
-
-			return lnk.GetNode(ctx, d.fs.dserv)
 		}
 	}
 

merkledag/merkledag.go

@@ -93,6 +93,8 @@ func (n *dagService) Get(ctx context.Context, k key.Key) (*Node, error) {
 	if n == nil {
 		return nil, fmt.Errorf("dagService is nil")
 	}
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
 
 	b, err := n.Blocks.GetBlock(ctx, k)
 	if err != nil {

merkledag/traverse/traverse.go

@@ -3,7 +3,6 @@ package traverse
 
 import (
 	"errors"
-	"time"
 
 	"github.com/ipfs/go-ipfs/Godeps/_workspace/src/golang.org/x/net/context"
 
@@ -67,10 +66,7 @@ func (t *traversal) callFunc(next State) error {
 func (t *traversal) getNode(link *mdag.Link) (*mdag.Node, error) {
 
 	getNode := func(l *mdag.Link) (*mdag.Node, error) {
-		ctx, cancel := context.WithTimeout(context.TODO(), time.Minute)
+		next, err := l.GetNode(context.TODO(), t.opts.DAG)
-		defer cancel()
-
-		next, err := l.GetNode(ctx, t.opts.DAG)
 		if err != nil {
 			return nil, err
 		}

merkledag/utils/utils.go

@@ -52,8 +52,7 @@ func addLink(ctx context.Context, ds dag.DAGService, root *dag.Node, childname s
 		return nil, err
 	}
 
-	_, err = ds.Add(root)
+	if _, err := ds.Add(root); err != nil {
-	if err != nil {
 		return nil, err
 	}
 	return root, nil

path/resolver.go

@@ -87,8 +87,6 @@ func (s *Resolver) ResolvePathComponents(ctx context.Context, fpath Path) ([]*me
 	}
 
 	log.Debug("Resolve dag get.")
-	ctx, cancel := context.WithCancel(ctx)
-	defer cancel()
 	nd, err := s.DAG.Get(ctx, key.Key(h))
 	if err != nil {
 		return nil, err

pin/pin.go

@@ -106,8 +106,7 @@ func (p *pinner) Pin(ctx context.Context, node *mdag.Node, recurse bool) error {
 
 		p.recursePin.AddBlock(k)
 	} else {
-		_, err := p.dserv.Get(ctx, k)
+		if _, err := p.dserv.Get(ctx, k); err != nil {
-		if err != nil {
 			return err
 		}
 

unixfs/mod/dagmodifier.go

@@ -459,9 +459,6 @@ func dagTruncate(ctx context.Context, nd *mdag.Node, size uint64, ds mdag.DAGSer
 	var modified *mdag.Node
 	ndata := new(ft.FSNode)
 	for i, lnk := range nd.Links {
-		_ctx, cancel := context.WithCancel(ctx)
-		defer cancel()
-
 		child, err := lnk.GetNode(ctx, ds)
 		if err != nil {
 			return nil, err
@@ -474,7 +471,7 @@ func dagTruncate(ctx context.Context, nd *mdag.Node, size uint64, ds mdag.DAGSer
 
 		// found the child we want to cut
 		if size < cur+childsize {
-			nchild, err := dagTruncate(_ctx, child, size-cur, ds)
+			nchild, err := dagTruncate(ctx, child, size-cur, ds)
 			if err != nil {
 				return nil, err
 			}