lib: sandbox: refactor to memory store

Signed-off-by: Antonio Murdaca <runcom@redhat.com>

lib/sandbox/history.go

@@ -0,0 +1,31 @@
+package sandbox
+
+import "sort"
+
+// History is a convenience type for storing a list of sandboxes,
+// sorted by creation date in descendant order.
+type History []*Sandbox
+
+// Len returns the number of sandboxes in the history.
+func (history *History) Len() int {
+	return len(*history)
+}
+
+// Less compares two sandboxes and returns true if the second one
+// was created before the first one.
+func (history *History) Less(i, j int) bool {
+	sandboxes := *history
+	// FIXME: state access should be serialized
+	return sandboxes[j].created.Before(sandboxes[i].created)
+}
+
+// Swap switches sandboxes i and j positions in the history.
+func (history *History) Swap(i, j int) {
+	sandboxes := *history
+	sandboxes[i], sandboxes[j] = sandboxes[j], sandboxes[i]
+}
+
+// sort orders the history by creation date in descendant order.
+func (history *History) sort() {
+	sort.Sort(history)
+}