etcd/mod/lock/v2/lock_nodes.go

package v2

import (
	"path"
	"sort"
	"strconv"

	"github.com/coreos/go-etcd/etcd"
)

// lockNodes is a wrapper for go-etcd's Nodes to allow for sorting by numeric key.
type lockNodes struct {
	etcd.Nodes
}

// Less sorts the nodes by key (numerically).
func (s lockNodes) Less(i, j int) bool {
	a, _ := strconv.Atoi(path.Base(s.Nodes[i].Key))
	b, _ := strconv.Atoi(path.Base(s.Nodes[j].Key))
	return a < b
}

// Retrieves the first node in the set of lock nodes.
func (s lockNodes) First() *etcd.Node {
	sort.Sort(s)
	if len(s.Nodes) > 0 {
		return &s.Nodes[0]
	}
	return nil
}

// Retrieves the first node with a given value.
func (s lockNodes) FindByValue(value string) (*etcd.Node, int) {
	sort.Sort(s)

	for i, node := range s.Nodes {
		if node.Value == value {
			return &node, i
		}
	}
	return nil, 0
}

// Retrieves the index that occurs before a given index.
func (s lockNodes) PrevIndex(index int) int {
	sort.Sort(s)

	var prevIndex int
	for _, node := range s.Nodes {
		idx, _ := strconv.Atoi(path.Base(node.Key))
		if index == idx {
			return prevIndex
		}
		prevIndex = idx
	}
	return 0
}