Added backup machinery

backup.go

@@ -0,0 +1,22 @@
+package main
+
+import (
+	"qurl/storage"
+	"time"
+	"fmt"
+	"path"
+	"os"
+)
+
+func manageBackup(stor storage.Storage, dir string, interval int){
+	for {
+		time.Sleep(time.Duration(interval) * time.Second)
+		fname := fmt.Sprintf("qurl-%s.backup",
+			time.Now().Format("20060102150405"))
+
+		err := stor.Backup(path.Join(dir, fname))
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "Backup failure: %s\n", err.Error())
+		}
+	}
+}

main.go

@@ -8,7 +8,6 @@ import (
 	"os"
 	"qurl/pages"
 	"qurl/storage"
-	"runtime"
 )
 
 //go:generate bindata -m Assets -r assets -p static -o static/assets.go assets
@@ -17,18 +16,10 @@ func main() {
 	dburl := flag.String("u", "bolt:./qurl.db", "url to database")
 	lsaddr := flag.String("l", "127.0.0.1:8080", "listen address/port")
 	jsonfile := flag.String("j", "", "path to json to load into database")
-	maxpro := flag.Int("m", runtime.NumCPU()+2,
+	backupint := flag.Int("i", 86400, "seconds between database backups")
-		"maximum number of threads to use")
+	backupdir := flag.String("b", "", "destination directory for database backups")
 	flag.Parse()
 
-	if *maxpro < 3 {
-		fmt.Fprintf(os.Stderr, "Thread limit too low: %d (min 3)\n", *maxpro)
-		return
-	}
-
-	// Limit max processes
-	runtime.GOMAXPROCS(*maxpro)
-
 	// Open storage backend
 	stor, err := storage.NewStorage(*dburl)
 	if err != nil {
@@ -37,6 +28,22 @@ func main() {
 	}
 	defer stor.Shutdown()
 
+	// If there's a backup dir specified, do backups
+	// at a specific interval
+	if *backupdir != "" {
+		stat, err := os.Stat(*backupdir)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "Directory stat error: %s\n", err.Error())
+			return
+		}
+		if !stat.IsDir() {
+			fmt.Fprintf(os.Stderr, "Backup directory does not exist: %s\n", *backupdir)
+			return
+		}
+
+		go manageBackup(stor, *backupdir, *backupint)
+	}
+
 	// Load data if asked
 	if *jsonfile != "" {
 		err := loadjson(stor, *jsonfile)

storage/bolt/bolt.go

@@ -4,6 +4,7 @@ import (
 	bolt "go.etcd.io/bbolt"
 	"net/url"
 	"time"
+	"os"
 )
 
 type BoltStorage struct {
@@ -26,3 +27,17 @@ func New(u *url.URL) (*BoltStorage, error) {
 	}
 	return &BoltStorage{DB: db}, nil
 }
+
+func (stor *BoltStorage) Backup(bpath string) error {
+	tx, err := stor.DB.Begin(false)
+	if err != nil {
+		return err
+	}
+	defer tx.Rollback()
+
+	err = tx.CopyFile(bpath, os.FileMode(0600))
+	if err != nil {
+		return err
+	}
+	return nil
+}

storage/storage.go

@@ -13,6 +13,7 @@ type Storage interface {
 	//	GetQURL(uint64) (*qurl.QURL, error)
 	GetQURLByURL(string) (*qurl.QURL, error)
 	SetQURLSequence(uint64) error
+	Backup(string) error
 	Shutdown()
 }