4363: Merge branch 'master' into 4363-less-filename-munging

[arvados.git] / sdk / go / keepclient / root_sorter.go

diff --git a/sdk/go/keepclient/root_sorter.go b/sdk/go/keepclient/root_sorter.go
new file mode 100644 (file)
index 0000000..c2780bc
--- /dev/null
+++ b/sdk/go/keepclient/root_sorter.go
@@ -0,0 +1,57 @@
+package keepclient
+
+import (
+       "sort"
+)
+
+type RootSorter struct {
+       root         []string
+       weight       []string
+       order        []int
+}
+
+func NewRootSorter(serviceRoots map[string]string, hash string) (*RootSorter) {
+       rs := new(RootSorter)
+       rs.root = make([]string, len(serviceRoots))
+       rs.weight = make([]string, len(serviceRoots))
+       rs.order = make([]int, len(serviceRoots))
+       i := 0
+       for uuid, root := range serviceRoots {
+               rs.root[i] = root
+               rs.weight[i] = rs.getWeight(hash, uuid)
+               rs.order[i] = i
+               i++
+       }
+       sort.Sort(rs)
+       return rs
+}
+
+func (rs RootSorter) getWeight(hash string, uuid string) (string) {
+       if len(uuid) == 27 {
+               return Md5String(hash + uuid[12:])
+       } else {
+               // Only useful for testing, a set of one service root, etc.
+               return Md5String(hash + uuid)
+       }
+}
+
+func (rs RootSorter) GetSortedRoots() ([]string) {
+       sorted := make([]string, len(rs.order))
+       for i := range rs.order {
+               sorted[i] = rs.root[rs.order[i]]
+       }
+       return sorted
+}
+
+// Less is really More here: the heaviest root will be at the front of the list.
+func (rs RootSorter) Less(i, j int) bool {
+       return rs.weight[rs.order[j]] < rs.weight[rs.order[i]]
+}
+
+func (rs RootSorter) Len() int {
+       return len(rs.order)
+}
+
+func (rs RootSorter) Swap(i, j int) {
+       sort.IntSlice(rs.order).Swap(i, j)
+}