From 8d8073a24d4b50b8dc6207d21077fa1976ee92e7 Mon Sep 17 00:00:00 2001
From: Zakhar Bessarab <z.bessarab@victoriametrics.com>
Date: Wed, 12 Jun 2024 13:35:30 +0400
Subject: [PATCH] lib/storage: add storage node id

Generate random node ID on start if it is missing or load from disk. Save to storage on storage shutdown.

Signed-off-by: Zakhar Bessarab <z.bessarab@victoriametrics.com>
---
 lib/storage/filenames.go |  2 ++
 lib/storage/storage.go   | 34 ++++++++++++++++++++++++++++++++--
 2 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/lib/storage/filenames.go b/lib/storage/filenames.go
index 62ea229e0..c841cfc12 100644
--- a/lib/storage/filenames.go
+++ b/lib/storage/filenames.go
@@ -10,6 +10,8 @@ const (
 
 	appliedRetentionFilename    = "appliedRetention.txt"
 	resetCacheOnStartupFilename = "reset_cache_on_startup"
+
+	nodeIDFilename = "node_id.bin"
 )
 
 const (
diff --git a/lib/storage/storage.go b/lib/storage/storage.go
index b10376985..cff2128b9 100644
--- a/lib/storage/storage.go
+++ b/lib/storage/storage.go
@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"io"
 	"math"
+	"math/rand"
 	"os"
 	"path/filepath"
 	"regexp"
@@ -15,6 +16,9 @@ import (
 	"time"
 	"unsafe"
 
+	"github.com/VictoriaMetrics/fastcache"
+	"github.com/VictoriaMetrics/metricsql"
+
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/backup/backupnames"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/bloomfilter"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
@@ -29,8 +33,6 @@ import (
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/timeutil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/uint64set"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/workingsetcache"
-	"github.com/VictoriaMetrics/fastcache"
-	"github.com/VictoriaMetrics/metricsql"
 )
 
 const (
@@ -64,6 +66,9 @@ type Storage struct {
 	cachePath      string
 	retentionMsecs int64
 
+	// Used to uniquely identify storage node
+	nodeID uint64
+
 	// lock file for exclusive access to the storage on the given path.
 	flockF *os.File
 
@@ -209,6 +214,19 @@ func MustOpenStorage(path string, retention time.Duration, maxHourlySeries, maxD
 		logger.Panicf("FATAL: incomplete vmrestore run; run vmrestore again or remove lock file %q", restoreLockF)
 	}
 
+	nodeIDFileF := filepath.Join(path, nodeIDFilename)
+	if fs.IsPathExist(nodeIDFileF) {
+		r, err := os.Open(nodeIDFileF)
+		nodeID, err := io.ReadAll(r)
+		if err != nil {
+			logger.Panicf("FATAL: cannot read nodeID from %q: %s", nodeIDFileF, err)
+		}
+		s.nodeID = encoding.UnmarshalUint64(nodeID)
+	} else {
+		nodeID := rand.Uint64()
+		s.nodeID = nodeID
+	}
+
 	// Pre-create snapshots directory if it is missing.
 	snapshotsPath := filepath.Join(path, snapshotsDirname)
 	fs.MustMkdirIfNotExist(snapshotsPath)
@@ -897,6 +915,8 @@ func (s *Storage) MustClose() {
 	nextDayMetricIDs := s.nextDayMetricIDs.Load()
 	s.mustSaveNextDayMetricIDs(nextDayMetricIDs)
 
+	s.mustSaveNodeID()
+
 	// Release lock file.
 	fs.MustClose(s.flockF)
 	s.flockF = nil
@@ -1032,6 +1052,16 @@ func (s *Storage) mustLoadHourMetricIDs(hour uint64, name string) *hourMetricIDs
 	return hm
 }
 
+func (s *Storage) mustSaveNodeID() {
+	path := filepath.Join(s.path, nodeIDFilename)
+	dst := make([]byte, 0)
+	dst = encoding.MarshalUint64(dst, s.nodeID)
+
+	if err := os.WriteFile(path, dst, 0644); err != nil {
+		logger.Panicf("FATAL: cannot write %d bytes to %q: %s", len(dst), path, err)
+	}
+}
+
 func (s *Storage) mustSaveNextDayMetricIDs(e *byDateMetricIDEntry) {
 	name := "next_day_metric_ids_v2"
 	path := filepath.Join(s.cachePath, name)