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Add Files API root as best-effort pin #2872

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Jun 22, 2016
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2 changes: 1 addition & 1 deletion core/commands/pin.go
Original file line number Diff line number Diff line change
Expand Up @@ -330,7 +330,7 @@ func pinLsAll(typeStr string, ctx context.Context, n *core.IpfsNode) (map[string
if err != nil {
return nil, err
}
err = dag.EnumerateChildren(n.Context(), n.DAG, nd, ks)
err = dag.EnumerateChildren(n.Context(), n.DAG, nd, ks, false)
if err != nil {
return nil, err
}
Expand Down
25 changes: 23 additions & 2 deletions core/corerepo/gc.go
Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@ import (

key "github.com/ipfs/go-ipfs/blocks/key"
"github.com/ipfs/go-ipfs/core"
mfs "github.com/ipfs/go-ipfs/mfs"
gc "github.com/ipfs/go-ipfs/pin/gc"
repo "github.com/ipfs/go-ipfs/repo"
humanize "gx/ipfs/QmPSBJL4momYnE7DcUyk2DVhD6rH488ZmHBGLbxNdhU44K/go-humanize"
Expand Down Expand Up @@ -71,10 +72,26 @@ func NewGC(n *core.IpfsNode) (*GC, error) {
}, nil
}

func BestEffortRoots(filesRoot *mfs.Root) ([]key.Key, error) {
rootDag, err := filesRoot.GetValue().GetNode()
if err != nil {
return nil, err
}
rootKey, err := rootDag.Key()
if err != nil {
return nil, err
}
return []key.Key{rootKey}, nil
}

func GarbageCollect(n *core.IpfsNode, ctx context.Context) error {
ctx, cancel := context.WithCancel(ctx)
defer cancel() // in case error occurs during operation
rmed, err := gc.GC(ctx, n.Blockstore, n.Pinning)
roots, err := BestEffortRoots(n.FilesRoot)
if err != nil {
return err
}
rmed, err := gc.GC(ctx, n.Blockstore, n.Pinning, roots)
if err != nil {
return err
}
Expand All @@ -93,7 +110,11 @@ func GarbageCollect(n *core.IpfsNode, ctx context.Context) error {
}

func GarbageCollectAsync(n *core.IpfsNode, ctx context.Context) (<-chan *KeyRemoved, error) {
rmed, err := gc.GC(ctx, n.Blockstore, n.Pinning)
roots, err := BestEffortRoots(n.FilesRoot)
if err != nil {
return nil, err
}
rmed, err := gc.GC(ctx, n.Blockstore, n.Pinning, roots)
if err != nil {
return nil, err
}
Expand Down
4 changes: 2 additions & 2 deletions core/coreunix/add_test.go
Original file line number Diff line number Diff line change
Expand Up @@ -96,7 +96,7 @@ func TestAddGCLive(t *testing.T) {
gcstarted := make(chan struct{})
go func() {
defer close(gcstarted)
gcchan, err := gc.GC(context.Background(), node.Blockstore, node.Pinning)
gcchan, err := gc.GC(context.Background(), node.Blockstore, node.Pinning, nil)
if err != nil {
log.Error("GC ERROR:", err)
errs <- err
Expand Down Expand Up @@ -155,7 +155,7 @@ func TestAddGCLive(t *testing.T) {
t.Fatal(err)
}

err = dag.EnumerateChildren(ctx, node.DAG, root, key.NewKeySet())
err = dag.EnumerateChildren(ctx, node.DAG, root, key.NewKeySet(), false)
if err != nil {
t.Fatal(err)
}
Expand Down
10 changes: 7 additions & 3 deletions merkledag/merkledag.go
Original file line number Diff line number Diff line change
Expand Up @@ -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 {
return err
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
}
Expand Down
4 changes: 2 additions & 2 deletions merkledag/merkledag_test.go
Original file line number Diff line number Diff line change
Expand Up @@ -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)
}
Expand All @@ -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)
}
Expand Down
20 changes: 13 additions & 7 deletions pin/gc/gc.go
Original file line number Diff line number Diff line change
Expand Up @@ -17,18 +17,19 @@ var log = logging.Logger("gc")
// GC performs a mark and sweep garbage collection of the blocks in the blockstore
// first, it creates a 'marked' set and adds to it the following:
// - all recursively pinned blocks, plus all of their descendants (recursively)
// - bestEffortRoots, plus all of its descendants (recursively)
// - all directly pinned blocks
// - all blocks utilized internally by the pinner
//
// The routine then iterates over every block in the blockstore and
// deletes any block that is not found in the marked set.
func GC(ctx context.Context, bs bstore.GCBlockstore, pn pin.Pinner) (<-chan key.Key, error) {
func GC(ctx context.Context, bs bstore.GCBlockstore, pn pin.Pinner, bestEffortRoots []key.Key) (<-chan key.Key, error) {
unlocker := bs.GCLock()

bsrv := bserv.New(bs, offline.Exchange(bs))
ds := dag.NewDAGService(bsrv)

gcs, err := ColoredSet(ctx, pn, ds)
gcs, err := ColoredSet(ctx, pn, ds, bestEffortRoots)
if err != nil {
return nil, err
}
Expand Down Expand Up @@ -69,7 +70,7 @@ func GC(ctx context.Context, bs bstore.GCBlockstore, pn pin.Pinner) (<-chan key.
return output, nil
}

func Descendants(ctx context.Context, ds dag.DAGService, set key.KeySet, roots []key.Key) error {
func Descendants(ctx context.Context, ds dag.DAGService, set key.KeySet, roots []key.Key, bestEffort bool) error {
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i strongly dislike how this is implemented. Adding bestEffort here to this function ruins the whole abstraction. You can implement this "best effort" notion outside of this function, just in the GC function.

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@jbenet in this function (Descendants) and EnumerateChildren all that bestEffort means is to not abort if a child is unreadable. In order to collect the set of keys to keep on a "best effort" bases I needed a way to to collected all the children of the initial best effort set that are local on the node.

I am not entirely clear what abstraction I am ruining so I am not 100% sure how to fix this. I could create a new function to find the Descendants of a keySet that doesn't abort on an error, but to me it seamed better to extend the functionally of the existing function.

@whyrusleeping I could appreciate any insights you can offer.

for _, k := range roots {
set.Add(k)
nd, err := ds.Get(ctx, k)
Expand All @@ -78,7 +79,7 @@ func Descendants(ctx context.Context, ds dag.DAGService, set key.KeySet, roots [
}

// EnumerateChildren recursively walks the dag and adds the keys to the given set
err = dag.EnumerateChildren(ctx, ds, nd, set)
err = dag.EnumerateChildren(ctx, ds, nd, set, bestEffort)
if err != nil {
return err
}
Expand All @@ -87,11 +88,16 @@ 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) (key.KeySet, error) {
func ColoredSet(ctx context.Context, pn pin.Pinner, ds dag.DAGService, bestEffortRoots []key.Key) (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())
err := Descendants(ctx, ds, gcs, pn.RecursiveKeys(), false)
if err != nil {
return nil, err
}

err = Descendants(ctx, ds, gcs, bestEffortRoots, true)
if err != nil {
return nil, err
}
Expand All @@ -100,7 +106,7 @@ func ColoredSet(ctx context.Context, pn pin.Pinner, ds dag.DAGService) (key.KeyS
gcs.Add(k)
}

err = Descendants(ctx, ds, gcs, pn.InternalPins())
err = Descendants(ctx, ds, gcs, pn.InternalPins(), false)
if err != nil {
return nil, err
}
Expand Down
36 changes: 36 additions & 0 deletions test/sharness/t0252-files-gc.sh
Original file line number Diff line number Diff line change
@@ -0,0 +1,36 @@
#!/bin/sh
#
# Copyright (c) 2016 Jeromy Johnson
# MIT Licensed; see the LICENSE file in this repository.
#

test_description="test how the unix files api interacts with the gc"

. lib/test-lib.sh

test_init_ipfs

test_expect_success "object not removed after gc" '
echo "hello world" | ipfs files write --create /hello.txt &&
ipfs repo gc &&
ipfs cat QmVib14uvPnCP73XaCDpwugRuwfTsVbGyWbatHAmLSdZUS
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we should also add another test_expect_success to make sure that /hello.txt is still accessible through the files api here

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So... if this is "best effort", under what conditions should gc remove these, and can we make sure to test that here?

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All "best effort" means is not to abort if a child is unreadable. For the GC to remove the object will need to be detached somehow from the MFS Root.

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@kevina want to take this one on and add a few more tests?

  • Test that the read test below outputs the right text
  • Exercise a situation that uses the best effort pin:
    • Add a directory containing a file with --pin=false
    • pin the hash directly
    • run a gc so that file is no longer accessible
    • ipfs files cp <dirhash> /somewhere (this should work just fine)
    • ipfs repo gc should succeed
    • re-add the file that was originally in that directory with --pin=false
    • run ipfs repo gc again, that file shouldnt be removed.

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OK Will do.

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@kevina kevina Aug 30, 2016

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@kevina want to take this one on and add a few more tests?

@whyrusleeping See #3151

'

test_expect_success "gc okay after adding incomplete node -- prep" '
ipfs files mkdir /adir &&
echo "file1" | ipfs files write --create /adir/file1 &&
echo "file2" | ipfs files write --create /adir/file2 &&
ipfs pin add --recursive=false QmbCgoMYVuZq8m1vK31JQx9DorwQdLMF1M3sJ7kygLLqnW &&
ipfs files rm -r /adir &&
ipfs repo gc && # will remove /adir/file1 and /adir/file2 but not /adir
ipfs files cp /ipfs/QmbCgoMYVuZq8m1vK31JQx9DorwQdLMF1M3sJ7kygLLqnW /adir &&
ipfs pin rm QmbCgoMYVuZq8m1vK31JQx9DorwQdLMF1M3sJ7kygLLqnW
'

test_expect_success "gc okay after adding incomplete node" '
ipfs refs QmbCgoMYVuZq8m1vK31JQx9DorwQdLMF1M3sJ7kygLLqnW &&
ipfs repo gc &&
ipfs refs QmbCgoMYVuZq8m1vK31JQx9DorwQdLMF1M3sJ7kygLLqnW
'

test_done