1 files changed, 30 insertions, 0 deletions
diff --git a/runtime/history.go b/runtime/history.go
new file mode 100644
index 0000000000..835ac9c11e
--- /dev/null
+++ b/runtime/history.go
@@ -0,0 +1,30 @@
+package runtime
+
+import (
+	"sort"
+)
+
+// History is a convenience type for storing a list of containers,
+// ordered by creation date.
+type History []*Container
+
+func (history *History) Len() int {
+	return len(*history)
+}
+
+func (history *History) Less(i, j int) bool {
+	containers := *history
+	return containers[j].When().Before(containers[i].When())
+}
+
+func (history *History) Swap(i, j int) {
+	containers := *history
+	tmp := containers[i]
+	containers[i] = containers[j]
+	containers[j] = tmp
+}
+
+func (history *History) Add(container *Container) {
+	*history = append(*history, container)
+	sort.Sort(history)
+}