From 0eeb50b55372bf3a5be9fb2ef543c3265620af54 Mon Sep 17 00:00:00 2001
From: Pierce Lopez <pierce.lopez@gmail.com>
Date: Thu, 19 Jul 2018 02:06:36 -0400
Subject: [PATCH] nsqd: remove support for old metadata filename

---
 nsqd/nsqd.go      |  54 +------------------------
 nsqd/nsqd_test.go | 100 ----------------------------------------------
 2 files changed, 1 insertion(+), 153 deletions(-)

diff --git a/nsqd/nsqd.go b/nsqd/nsqd.go
index 3c5437299..8d3196b82 100644
--- a/nsqd/nsqd.go
+++ b/nsqd/nsqd.go
@@ -1,7 +1,6 @@
 package nsqd
 
 import (
-	"bytes"
 	"crypto/tls"
 	"crypto/x509"
 	"encoding/json"
@@ -13,7 +12,6 @@ import (
 	"net"
 	"os"
 	"path"
-	"runtime"
 	"strings"
 	"sync"
 	"sync/atomic"
@@ -272,10 +270,6 @@ func newMetadataFile(opts *Options) string {
 	return path.Join(opts.DataPath, "nsqd.dat")
 }
 
-func oldMetadataFile(opts *Options) string {
-	return path.Join(opts.DataPath, fmt.Sprintf("nsqd.%d.dat", opts.ID))
-}
-
 func readOrEmpty(fn string) ([]byte, error) {
 	data, err := ioutil.ReadFile(fn)
 	if err != nil {
@@ -305,30 +299,13 @@ func (n *NSQD) LoadMetadata() error {
 	defer atomic.StoreInt32(&n.isLoading, 0)
 
 	fn := newMetadataFile(n.getOpts())
-	// old metadata filename with ID, maintained in parallel to enable roll-back
-	fnID := oldMetadataFile(n.getOpts())
 
 	data, err := readOrEmpty(fn)
 	if err != nil {
 		return err
 	}
-	dataID, errID := readOrEmpty(fnID)
-	if errID != nil {
-		return errID
-	}
-
-	if data == nil && dataID == nil {
-		return nil // fresh start
-	}
-	if data != nil && dataID != nil {
-		if bytes.Compare(data, dataID) != 0 {
-			return fmt.Errorf("metadata in %s and %s do not match (delete one)", fn, fnID)
-		}
-	}
 	if data == nil {
-		// only old metadata file exists, use it
-		fn = fnID
-		data = dataID
+		return nil // fresh start
 	}
 
 	var m meta
@@ -364,8 +341,6 @@ func (n *NSQD) LoadMetadata() error {
 func (n *NSQD) PersistMetadata() error {
 	// persist metadata about what topics/channels we have, across restarts
 	fileName := newMetadataFile(n.getOpts())
-	// old metadata filename with ID, maintained in parallel to enable roll-back
-	fileNameID := oldMetadataFile(n.getOpts())
 
 	n.logf(LOG_INFO, "NSQ: persisting topic/channel metadata to %s", fileName)
 
@@ -416,33 +391,6 @@ func (n *NSQD) PersistMetadata() error {
 	}
 	// technically should fsync DataPath here
 
-	stat, err := os.Lstat(fileNameID)
-	if err == nil && stat.Mode()&os.ModeSymlink != 0 {
-		return nil
-	}
-
-	// if no symlink (yet), race condition:
-	// crash right here may cause next startup to see metadata conflict and abort
-
-	tmpFileNameID := fmt.Sprintf("%s.%d.tmp", fileNameID, rand.Int())
-
-	if runtime.GOOS != "windows" {
-		err = os.Symlink(fileName, tmpFileNameID)
-	} else {
-		// on Windows need Administrator privs to Symlink
-		// instead write copy every time
-		err = writeSyncFile(tmpFileNameID, data)
-	}
-	if err != nil {
-		return err
-	}
-
-	err = os.Rename(tmpFileNameID, fileNameID)
-	if err != nil {
-		return err
-	}
-	// technically should fsync DataPath here
-
 	return nil
 }
 
diff --git a/nsqd/nsqd_test.go b/nsqd/nsqd_test.go
index 150a531b8..f1f0c2117 100644
--- a/nsqd/nsqd_test.go
+++ b/nsqd/nsqd_test.go
@@ -158,106 +158,6 @@ func TestStartup(t *testing.T) {
 	<-doneExitChan
 }
 
-func TestMetadataMigrate(t *testing.T) {
-	old_meta := `
-	{
-	  "topics": [
-	    {
-	      "channels": [
-	        {"name": "c1", "paused": false},
-	        {"name": "c2", "paused": false}
-	      ],
-	      "name": "t1",
-	      "paused": false
-	    }
-	  ],
-	  "version": "1.0.0-alpha"
-	}`
-
-	tmpDir, err := ioutil.TempDir("", "nsq-test-")
-	if err != nil {
-		panic(err)
-	}
-	defer os.RemoveAll(tmpDir)
-
-	opts := NewOptions()
-	opts.DataPath = tmpDir
-	opts.Logger = test.NewTestLogger(t)
-
-	oldFn := oldMetadataFile(opts)
-	err = ioutil.WriteFile(oldFn, []byte(old_meta), 0600)
-	if err != nil {
-		panic(err)
-	}
-
-	_, _, nsqd := mustStartNSQD(opts)
-	err = nsqd.LoadMetadata()
-	test.Nil(t, err)
-	err = nsqd.PersistMetadata()
-	test.Nil(t, err)
-	nsqd.Exit()
-
-	oldFi, err := os.Lstat(oldFn)
-	test.Nil(t, err)
-	test.Equal(t, oldFi.Mode()&os.ModeType, os.ModeSymlink)
-
-	_, _, nsqd = mustStartNSQD(opts)
-	err = nsqd.LoadMetadata()
-	test.Nil(t, err)
-
-	t1, err := nsqd.GetExistingTopic("t1")
-	test.Nil(t, err)
-	test.NotNil(t, t1)
-	c2, err := t1.GetExistingChannel("c2")
-	test.Nil(t, err)
-	test.NotNil(t, c2)
-
-	nsqd.Exit()
-}
-
-func TestMetadataConflict(t *testing.T) {
-	old_meta := `
-	{
-	  "topics": [{
-	    "name": "t1", "paused": false,
-	    "channels": [{"name": "c1", "paused": false}]
-	  }],
-	  "version": "1.0.0-alpha"
-	}`
-	new_meta := `
-	{
-	  "topics": [{
-	    "name": "t2", "paused": false,
-	    "channels": [{"name": "c2", "paused": false}]
-	  }],
-	  "version": "1.0.0-alpha"
-	}`
-
-	tmpDir, err := ioutil.TempDir("", "nsq-test-")
-	if err != nil {
-		panic(err)
-	}
-	defer os.RemoveAll(tmpDir)
-
-	opts := NewOptions()
-	opts.DataPath = tmpDir
-	opts.Logger = test.NewTestLogger(t)
-
-	err = ioutil.WriteFile(oldMetadataFile(opts), []byte(old_meta), 0600)
-	if err != nil {
-		panic(err)
-	}
-	err = ioutil.WriteFile(newMetadataFile(opts), []byte(new_meta), 0600)
-	if err != nil {
-		panic(err)
-	}
-
-	_, _, nsqd := mustStartNSQD(opts)
-	err = nsqd.LoadMetadata()
-	test.NotNil(t, err)
-	nsqd.Exit()
-}
-
 func TestEphemeralTopicsAndChannels(t *testing.T) {
 	// ephemeral topics/channels are lazily removed after the last channel/client is removed
 	opts := NewOptions()