gc: add support for multiple snapshot labels

Allows linking to multiple snapshots within the same snapshotter.
Adds support for using slash to separate content as well for consistency.

Signed-off-by: Derek McGowan <derek@mcgstyle.net>

metadata/gc.go

@@ -17,6 +17,7 @@
 package metadata
 
 import (
+	"bytes"
 	"context"
 	"fmt"
 	"strings"
@@ -345,7 +346,10 @@ func sendSnapshotRefs(ns string, bkt *bolt.Bucket, fn func(gc.Node)) error {
 		lc := lbkt.Cursor()
 
 		for k, v := lc.Seek(labelGCSnapRef); k != nil && strings.HasPrefix(string(k), string(labelGCSnapRef)); k, v = lc.Next() {
-			snapshotter := string(k[len(labelGCSnapRef):])
+			snapshotter := k[len(labelGCSnapRef):]
+			if i := bytes.IndexByte(snapshotter, '/'); i >= 0 {
+				snapshotter = snapshotter[:i]
+			}
 			fn(gcnode(ResourceSnapshot, ns, fmt.Sprintf("%s/%s", snapshotter, v)))
 		}
 	}
@@ -361,8 +365,8 @@ func sendContentRefs(ns string, bkt *bolt.Bucket, fn func(gc.Node)) error {
 		labelRef := string(labelGCContentRef)
 		for k, v := lc.Seek(labelGCContentRef); k != nil && strings.HasPrefix(string(k), labelRef); k, v = lc.Next() {
 			if ks := string(k); ks != labelRef {
-				// Allow reference naming, ignore names
+				// Allow reference naming separated by . or /, ignore names
-				if ks[len(labelRef)] != '.' {
+				if ks[len(labelRef)] != '.' && ks[len(labelRef)] != '/' {
 					continue
 				}
 			}

metadata/gc_test.go

@@ -44,6 +44,7 @@ func TestGCRoots(t *testing.T) {
 		addImage("ns1", "image2", dgst(2), labelmap(string(labelGCSnapRef)+"overlay", "sn2")),
 		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")),
 		addContent("ns1", dgst(1), nil),
 		addContent("ns1", dgst(2), nil),
 		addContent("ns1", dgst(3), nil),
@@ -55,6 +56,9 @@ func TestGCRoots(t *testing.T) {
 		addSnapshot("ns1", "overlay", "sn4", "", nil),
 		addSnapshot("ns1", "overlay", "sn5", "", nil),
 		addSnapshot("ns1", "overlay", "sn6", "", nil),
+		addSnapshot("ns1", "overlay", "sn7", "", nil),
+		addSnapshot("ns1", "overlay", "sn8", "", nil),
+		addSnapshot("ns1", "overlay", "sn9", "", nil),
 		addLeaseSnapshot("ns2", "l1", "overlay", "sn5"),
 		addLeaseSnapshot("ns2", "l2", "overlay", "sn6"),
 		addLeaseContent("ns2", "l1", dgst(4)),
@@ -72,6 +76,9 @@ func TestGCRoots(t *testing.T) {
 		gcnode(ResourceSnapshot, "ns1", "overlay/sn4"),
 		gcnode(ResourceSnapshot, "ns1", "overlay/sn5"),
 		gcnode(ResourceSnapshot, "ns1", "overlay/sn6"),
+		gcnode(ResourceSnapshot, "ns1", "overlay/sn7"),
+		gcnode(ResourceSnapshot, "ns1", "overlay/sn8"),
+		gcnode(ResourceSnapshot, "ns1", "overlay/sn9"),
 		gcnode(ResourceSnapshot, "ns2", "overlay/sn5"),
 		gcnode(ResourceSnapshot, "ns2", "overlay/sn6"),
 	}
@@ -197,12 +204,14 @@ func TestGCRefs(t *testing.T) {
 		addContent("ns1", dgst(4), labelmap(string(labelGCContentRef), dgst(1).String())),
 		addContent("ns1", dgst(5), labelmap(string(labelGCContentRef)+".anything-1", dgst(2).String(), string(labelGCContentRef)+".anything-2", dgst(3).String())),
 		addContent("ns1", dgst(6), labelmap(string(labelGCContentRef)+"bad", dgst(1).String())),
+		addContent("ns1", dgst(7), labelmap(string(labelGCContentRef)+"/anything-1", dgst(2).String(), string(labelGCContentRef)+"/anything-2", dgst(3).String())),
 		addContent("ns2", dgst(1), nil),
 		addContent("ns2", dgst(2), nil),
 		addSnapshot("ns1", "overlay", "sn1", "", nil),
 		addSnapshot("ns1", "overlay", "sn2", "sn1", nil),
 		addSnapshot("ns1", "overlay", "sn3", "sn2", nil),
 		addSnapshot("ns1", "overlay", "sn4", "", labelmap(string(labelGCSnapRef)+"btrfs", "sn1", string(labelGCSnapRef)+"overlay", "sn1")),
+		addSnapshot("ns1", "overlay", "sn5", "", labelmap(string(labelGCSnapRef)+"overlay/anything-1", "sn1", string(labelGCSnapRef)+"overlay/anything-2", "sn2")),
 		addSnapshot("ns1", "btrfs", "sn1", "", nil),
 		addSnapshot("ns2", "overlay", "sn1", "", nil),
 		addSnapshot("ns2", "overlay", "sn2", "sn1", nil),
@@ -220,6 +229,10 @@ func TestGCRefs(t *testing.T) {
 			gcnode(ResourceContent, "ns1", dgst(3).String()),
 		},
 		gcnode(ResourceContent, "ns1", dgst(6).String()): nil,
+		gcnode(ResourceContent, "ns1", dgst(7).String()): {
+			gcnode(ResourceContent, "ns1", dgst(2).String()),
+			gcnode(ResourceContent, "ns1", dgst(3).String()),
+		},
 		gcnode(ResourceContent, "ns2", dgst(1).String()): nil,
 		gcnode(ResourceContent, "ns2", dgst(2).String()): nil,
 		gcnode(ResourceSnapshot, "ns1", "overlay/sn1"):   nil,
@@ -233,6 +246,10 @@ func TestGCRefs(t *testing.T) {
 			gcnode(ResourceSnapshot, "ns1", "btrfs/sn1"),
 			gcnode(ResourceSnapshot, "ns1", "overlay/sn1"),
 		},
+		gcnode(ResourceSnapshot, "ns1", "overlay/sn5"): {
+			gcnode(ResourceSnapshot, "ns1", "overlay/sn1"),
+			gcnode(ResourceSnapshot, "ns1", "overlay/sn2"),
+		},
 		gcnode(ResourceSnapshot, "ns1", "btrfs/sn1"):   nil,
 		gcnode(ResourceSnapshot, "ns2", "overlay/sn1"): nil,
 		gcnode(ResourceSnapshot, "ns2", "overlay/sn2"): {