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Add content gc ref labels from containers, images, and snapshots
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Currently the objects which can retain content from labels
are limited. This limitation has required clients to work
around this and and in some cases add outside reference
counting (e.g. buildkit keeping content for snapshots).
Updated the logic to treat content and snapshot labels equally
and simplified the code in the process.

Signed-off-by: Derek McGowan <derek@mcgstyle.net>
(cherry picked from commit 7cfb99a)
Signed-off-by: Derek McGowan <derek@mcgstyle.net>
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@dmcgowan
dmcgowan committed Mar 7, 2019
1 parent f3ab47d commit 17a4289
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Showing 2 changed files with 69 additions and 90 deletions.
138 changes: 49 additions & 89 deletions metadata/gc.go
View file
Expand Up @@ -64,6 +64,18 @@ func scanRoots(ctx context.Context, tx *bolt.Tx, nc chan<- gc.Node) error {
// iterate through each namespace
v1c := v1bkt.Cursor()

// cerr indicates the scan did not successfully send all
// the roots. The scan does not need to be cancelled but
// must return error at the end.
var cerr error
fn := func(n gc.Node) {
select {
case nc <- n:
case <-ctx.Done():
cerr = ctx.Err()
}
}

for k, v := v1c.First(); k != nil; k, v = v1c.Next() {
if v != nil {
continue
Expand Down Expand Up @@ -92,11 +104,7 @@ func scanRoots(ctx context.Context, tx *bolt.Tx, nc chan<- gc.Node) error {
}
}

select {
case nc <- gcnode(ResourceLease, ns, string(k)):
case <-ctx.Done():
return ctx.Err()
}
fn(gcnode(ResourceLease, ns, string(k)))

// Emit content and snapshots as roots instead of implementing
// in references. Since leases cannot be referenced there is
Expand All @@ -106,11 +114,7 @@ func scanRoots(ctx context.Context, tx *bolt.Tx, nc chan<- gc.Node) error {
cbkt := libkt.Bucket(bucketKeyObjectContent)
if cbkt != nil {
if err := cbkt.ForEach(func(k, v []byte) error {
select {
case nc <- gcnode(ResourceContent, ns, string(k)):
case <-ctx.Done():
return ctx.Err()
}
fn(gcnode(ResourceContent, ns, string(k)))
return nil
}); err != nil {
return err
Expand All @@ -126,11 +130,7 @@ func scanRoots(ctx context.Context, tx *bolt.Tx, nc chan<- gc.Node) error {
snbkt := sbkt.Bucket(sk)

return snbkt.ForEach(func(k, v []byte) error {
select {
case nc <- gcnode(ResourceSnapshot, ns, fmt.Sprintf("%s/%s", sk, k)):
case <-ctx.Done():
return ctx.Err()
}
fn(gcnode(ResourceSnapshot, ns, fmt.Sprintf("%s/%s", sk, k)))
return nil
})
}); err != nil {
Expand All @@ -141,11 +141,7 @@ func scanRoots(ctx context.Context, tx *bolt.Tx, nc chan<- gc.Node) error {
ibkt := libkt.Bucket(bucketKeyObjectIngests)
if ibkt != nil {
if err := ibkt.ForEach(func(k, v []byte) error {
select {
case nc <- gcnode(ResourceIngest, ns, string(k)):
case <-ctx.Done():
return ctx.Err()
}
fn(gcnode(ResourceIngest, ns, string(k)))
return nil
}); err != nil {
return err
Expand All @@ -168,18 +164,9 @@ func scanRoots(ctx context.Context, tx *bolt.Tx, nc chan<- gc.Node) error {
target := ibkt.Bucket(k).Bucket(bucketKeyTarget)
if target != nil {
contentKey := string(target.Get(bucketKeyDigest))
select {
case nc <- gcnode(ResourceContent, ns, contentKey):
case <-ctx.Done():
return ctx.Err()
}
fn(gcnode(ResourceContent, ns, contentKey))
}
return sendSnapshotRefs(ns, ibkt.Bucket(k), func(n gc.Node) {
select {
case nc <- n:
case <-ctx.Done():
}
})
return sendLabelRefs(ns, ibkt.Bucket(k), fn)
}); err != nil {
return err
}
Expand All @@ -200,11 +187,7 @@ func scanRoots(ctx context.Context, tx *bolt.Tx, nc chan<- gc.Node) error {
if ea == nil || expThreshold.After(*ea) {
return nil
}
select {
case nc <- gcnode(ResourceIngest, ns, string(k)):
case <-ctx.Done():
return ctx.Err()
}
fn(gcnode(ResourceIngest, ns, string(k)))
return nil
}); err != nil {
return err
Expand All @@ -216,7 +199,12 @@ func scanRoots(ctx context.Context, tx *bolt.Tx, nc chan<- gc.Node) error {
if v != nil {
return nil
}
return sendRootRef(ctx, nc, gcnode(ResourceContent, ns, string(k)), cbkt.Bucket(k))

if isRootRef(cbkt.Bucket(k)) {
fn(gcnode(ResourceContent, ns, string(k)))
}

return nil
}); err != nil {
return err
}
Expand All @@ -229,23 +217,15 @@ func scanRoots(ctx context.Context, tx *bolt.Tx, nc chan<- gc.Node) error {
if v != nil {
return nil
}
snapshotter := string(cbkt.Bucket(k).Get(bucketKeySnapshotter))

cibkt := cbkt.Bucket(k)
snapshotter := string(cibkt.Get(bucketKeySnapshotter))
if snapshotter != "" {
ss := string(cbkt.Bucket(k).Get(bucketKeySnapshotKey))
select {
case nc <- gcnode(ResourceSnapshot, ns, fmt.Sprintf("%s/%s", snapshotter, ss)):
case <-ctx.Done():
return ctx.Err()
}
ss := string(cibkt.Get(bucketKeySnapshotKey))
fn(gcnode(ResourceSnapshot, ns, fmt.Sprintf("%s/%s", snapshotter, ss)))
}

// TODO: Send additional snapshot refs through labels
return sendSnapshotRefs(ns, cbkt.Bucket(k), func(n gc.Node) {
select {
case nc <- n:
case <-ctx.Done():
}
})
return sendLabelRefs(ns, cibkt, fn)
}); err != nil {
return err
}
Expand All @@ -263,15 +243,17 @@ func scanRoots(ctx context.Context, tx *bolt.Tx, nc chan<- gc.Node) error {
if v != nil {
return nil
}

return sendRootRef(ctx, nc, gcnode(ResourceSnapshot, ns, fmt.Sprintf("%s/%s", sk, k)), snbkt.Bucket(k))
if isRootRef(snbkt.Bucket(k)) {
fn(gcnode(ResourceSnapshot, ns, fmt.Sprintf("%s/%s", sk, k)))
}
return nil
})
}); err != nil {
return err
}
}
}
return nil
return cerr
}

func references(ctx context.Context, tx *bolt.Tx, node gc.Node, fn func(gc.Node)) error {
Expand All @@ -282,10 +264,7 @@ func references(ctx context.Context, tx *bolt.Tx, node gc.Node, fn func(gc.Node)
return nil
}

if err := sendSnapshotRefs(node.Namespace, bkt, fn); err != nil {
return err
}
return sendContentRefs(node.Namespace, bkt, fn)
return sendLabelRefs(node.Namespace, bkt, fn)
} else if node.Type == ResourceSnapshot {
parts := strings.SplitN(node.Key, "/", 2)
if len(parts) != 2 {
Expand All @@ -304,7 +283,7 @@ func references(ctx context.Context, tx *bolt.Tx, node gc.Node, fn func(gc.Node)
fn(gcnode(ResourceSnapshot, node.Namespace, fmt.Sprintf("%s/%s", ss, pv)))
}

return sendSnapshotRefs(node.Namespace, bkt, fn)
return sendLabelRefs(node.Namespace, bkt, fn)
} else if node.Type == ResourceIngest {
// Send expected value
bkt := getBucket(tx, bucketKeyVersion, []byte(node.Namespace), bucketKeyObjectContent, bucketKeyObjectIngests, []byte(node.Key))
Expand Down Expand Up @@ -456,25 +435,8 @@ func remove(ctx context.Context, tx *bolt.Tx, node gc.Node) error {
return nil
}

// sendSnapshotRefs sends all snapshot references referred to by the labels in the bkt
func sendSnapshotRefs(ns string, bkt *bolt.Bucket, fn func(gc.Node)) error {
lbkt := bkt.Bucket(bucketKeyObjectLabels)
if lbkt != nil {
lc := lbkt.Cursor()

for k, v := lc.Seek(labelGCSnapRef); k != nil && strings.HasPrefix(string(k), string(labelGCSnapRef)); k, v = lc.Next() {
snapshotter := k[len(labelGCSnapRef):]
if i := bytes.IndexByte(snapshotter, '/'); i >= 0 {
snapshotter = snapshotter[:i]
}
fn(gcnode(ResourceSnapshot, ns, fmt.Sprintf("%s/%s", snapshotter, v)))
}
}
return nil
}

// sendContentRefs sends all content references referred to by the labels in the bkt
func sendContentRefs(ns string, bkt *bolt.Bucket, fn func(gc.Node)) error {
// sendLabelRefs sends all snapshot and content references referred to by the labels in the bkt
func sendLabelRefs(ns string, bkt *bolt.Bucket, fn func(gc.Node)) error {
lbkt := bkt.Bucket(bucketKeyObjectLabels)
if lbkt != nil {
lc := lbkt.Cursor()
Expand All @@ -490,6 +452,15 @@ func sendContentRefs(ns string, bkt *bolt.Bucket, fn func(gc.Node)) error {

fn(gcnode(ResourceContent, ns, string(v)))
}

for k, v := lc.Seek(labelGCSnapRef); k != nil && strings.HasPrefix(string(k), string(labelGCSnapRef)); k, v = lc.Next() {
snapshotter := k[len(labelGCSnapRef):]
if i := bytes.IndexByte(snapshotter, '/'); i >= 0 {
snapshotter = snapshotter[:i]
}
fn(gcnode(ResourceSnapshot, ns, fmt.Sprintf("%s/%s", snapshotter, v)))
}

}
return nil
}
Expand All @@ -506,17 +477,6 @@ func isRootRef(bkt *bolt.Bucket) bool {
return false
}

func sendRootRef(ctx context.Context, nc chan<- gc.Node, n gc.Node, bkt *bolt.Bucket) error {
if isRootRef(bkt) {
select {
case nc <- n:
case <-ctx.Done():
return ctx.Err()
}
}
return nil
}

func gcnode(t gc.ResourceType, ns, key string) gc.Node {
return gc.Node{
Type: t,
Expand Down
21 changes: 20 additions & 1 deletion metadata/gc_test.go
View file
Expand Up @@ -43,9 +43,16 @@ func TestGCRoots(t *testing.T) {
alters := []alterFunc{
addImage("ns1", "image1", dgst(1), nil),
addImage("ns1", "image2", dgst(2), labelmap(string(labelGCSnapRef)+"overlay", "sn2")),
addImage("ns2", "image3", dgst(10), labelmap(string(labelGCContentRef), dgst(11).String())),
addContainer("ns1", "container1", "overlay", "sn4", nil),
addContainer("ns1", "container2", "overlay", "sn5", labelmap(string(labelGCSnapRef)+"overlay", "sn6")),
addContainer("ns1", "container3", "overlay", "sn7", labelmap(string(labelGCSnapRef)+"overlay/anything-1", "sn8", string(labelGCSnapRef)+"overlay/anything-2", "sn9")),
addContainer("ns1", "container3", "overlay", "sn7", labelmap(
string(labelGCSnapRef)+"overlay/anything-1", "sn8",
string(labelGCSnapRef)+"overlay/anything-2", "sn9",
string(labelGCContentRef), dgst(7).String())),
addContainer("ns1", "container4", "", "", labelmap(
string(labelGCContentRef)+".0", dgst(8).String(),
string(labelGCContentRef)+".1", dgst(9).String())),
addContent("ns1", dgst(1), nil),
addContent("ns1", dgst(2), nil),
addContent("ns1", dgst(3), nil),
Expand Down Expand Up @@ -88,10 +95,15 @@ func TestGCRoots(t *testing.T) {
expected := []gc.Node{
gcnode(ResourceContent, "ns1", dgst(1).String()),
gcnode(ResourceContent, "ns1", dgst(2).String()),
gcnode(ResourceContent, "ns1", dgst(7).String()),
gcnode(ResourceContent, "ns1", dgst(8).String()),
gcnode(ResourceContent, "ns1", dgst(9).String()),
gcnode(ResourceContent, "ns2", dgst(2).String()),
gcnode(ResourceContent, "ns2", dgst(4).String()),
gcnode(ResourceContent, "ns2", dgst(5).String()),
gcnode(ResourceContent, "ns2", dgst(6).String()),
gcnode(ResourceContent, "ns2", dgst(10).String()),
gcnode(ResourceContent, "ns2", dgst(11).String()),
gcnode(ResourceSnapshot, "ns1", "overlay/sn2"),
gcnode(ResourceSnapshot, "ns1", "overlay/sn3"),
gcnode(ResourceSnapshot, "ns1", "overlay/sn4"),
Expand Down Expand Up @@ -253,6 +265,9 @@ func TestGCRefs(t *testing.T) {
addSnapshot("ns1", "btrfs", "sn1", "", nil),
addSnapshot("ns2", "overlay", "sn1", "", nil),
addSnapshot("ns2", "overlay", "sn2", "sn1", nil),
addSnapshot("ns2", "overlay", "sn3", "", labelmap(
string(labelGCContentRef), dgst(1).String(),
string(labelGCContentRef)+".keep-me", dgst(6).String())),
}

refs := map[gc.Node][]gc.Node{
Expand Down Expand Up @@ -293,6 +308,10 @@ func TestGCRefs(t *testing.T) {
gcnode(ResourceSnapshot, "ns2", "overlay/sn2"): {
gcnode(ResourceSnapshot, "ns2", "overlay/sn1"),
},
gcnode(ResourceSnapshot, "ns2", "overlay/sn3"): {
gcnode(ResourceContent, "ns2", dgst(1).String()),
gcnode(ResourceContent, "ns2", dgst(6).String()),
},
gcnode(ResourceIngest, "ns1", "ingest-1"): nil,
gcnode(ResourceIngest, "ns2", "ingest-2"): {
gcnode(ResourceContent, "ns2", dgst(8).String()),
Expand Down

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