From df5dae77c6adc00257da2648f85dadda316387b2 Mon Sep 17 00:00:00 2001
From: Nikita Tokarchuk <nikita@tokarch.uk>
Date: Wed, 13 Apr 2022 23:47:58 +0200
Subject: [PATCH] Add helper function to sort children nodes by the sequenced
 postfix

---
 helpers.go  | 26 ++++++++++++++++++++++++++
 nodesync.go |  3 +++
 2 files changed, 29 insertions(+)

diff --git a/helpers.go b/helpers.go
index 43cb45b..1c320fc 100644
--- a/helpers.go
+++ b/helpers.go
@@ -4,6 +4,8 @@ import (
 	"github.com/go-zookeeper/zk"
 
 	"fmt"
+	"path"
+	"sort"
 	"strings"
 )
 
@@ -46,3 +48,27 @@ func (s *NodeSync) createRecursively(path string, acl []zk.ACL) error {
 
 	return nil
 }
+
+// sortChildren sorts sequenced zookeeper nodes by sequence id
+// sequence id is a last part of node key and always consists of 10 digits
+func sortChildren(children []string) []string {
+
+	var sorted []string
+	for _, child := range children {
+		if len(child) <= sequenceLen {
+			continue
+		}
+
+		sorted = append(sorted, child)
+	}
+
+	sort.SliceStable(sorted, func(i, j int) bool {
+
+		_, a := path.Split(sorted[i])
+		_, b := path.Split(sorted[j])
+
+		return a[len(a)-sequenceLen:] < b[len(b)-sequenceLen:]
+	})
+
+	return sorted
+}
diff --git a/nodesync.go b/nodesync.go
index 412ce60..f9932a0 100644
--- a/nodesync.go
+++ b/nodesync.go
@@ -16,6 +16,9 @@ type NodeSync struct {
 // Inside private environment keep everything open
 var defaultAcl = zk.WorldACL(zk.PermAll)
 
+// The length of a postfix sequence, see http://zookeeper.apache.org/doc/current/zookeeperProgrammers.html#Sequence+Nodes+--+Unique+Naming
+var sequenceLen = 10
+
 // New creates a new nodesync instance
 func New(zkconn *zk.Conn, rootPath string) (nodeSync *NodeSync, err error) {