fix: debug and optimize reloading of database file (#22)

* fix: try better reloading of database

* fix: better logging of password hash

* chore: debug database error

offline.go

@@ -58,9 +58,13 @@ var (
 type (
 	// An OfflineDatabase is a client for querying Pwned Passwords locally.
 	OfflineDatabase struct {
+		file   *DatabaseFile
+		logger zap.Logger
+		cron   *cron.Cron
+	}
+
+	DatabaseFile struct {
 		database readCloserAt
-		logger   zap.Logger
-		cron     *cron.Cron
 	}
 
 	// readCloserAt is an io.ReaderAt that can be Closed and whose
@@ -135,9 +139,9 @@ func NewOfflineDatabase(dbFile string, updatedDbFile string) (*OfflineDatabase,
 	logger.Info("Database opened")
 	c := cron.New()
 	odb := &OfflineDatabase{
-		database: db,
-		logger:   logger,
-		cron:     c,
+		file:   &DatabaseFile{db},
+		logger: logger,
+		cron:   c,
 	}
 
 	c.AddFunc("@hourly", func() {
@@ -156,7 +160,7 @@ func NewOfflineDatabase(dbFile string, updatedDbFile string) (*OfflineDatabase,
 				if err != nil {
 					log.Panic(err)
 				}
-				odb.database = db
+				odb.file = &DatabaseFile{db}
 				logger.Info("Database updated")
 			}
 		}
@@ -169,7 +173,7 @@ func NewOfflineDatabase(dbFile string, updatedDbFile string) (*OfflineDatabase,
 // Close frees resources associated with the database.
 func (od *OfflineDatabase) Close() error {
 	od.cron.Stop()
-	return od.database.Close()
+	return od.file.database.Close()
 }
 
 // Pwned checks how frequently the given hash is included in the Pwned Passwords
@@ -211,7 +215,7 @@ func (od *OfflineDatabase) Pwned(hash [20]byte) (frequency int, err error) {
 		test = lo + ((hi - lo) / 2)
 
 		// lookup
-		if _, err := od.database.ReadAt(rbuf[:], DataSegmentOffset+start+int64(test*19)); err != nil {
+		if _, err := od.file.database.ReadAt(rbuf[:], DataSegmentOffset+start+int64(test*19)); err != nil {
 			return 0, err
 		}
 
@@ -270,7 +274,7 @@ func (od *OfflineDatabase) Scan(startPrefix, endPrefix [3]byte, hash []byte, cb
 		}
 
 		// read from the data file
-		if _, err := od.database.ReadAt(buffer[0:length], DataSegmentOffset+start); err != nil {
+		if _, err := od.file.database.ReadAt(buffer[0:length], DataSegmentOffset+start); err != nil {
 			return err
 		}
 
@@ -325,18 +329,18 @@ func (od *OfflineDatabase) lookup(start [3]byte) (location, length int64, err er
 	case [3]byte{0xFF, 0xFF, 0xFF}:
 
 		// read the required index
-		if _, err := od.database.ReadAt(buffer[0:8], int64(prefixIndex)*8); err != nil {
+		if _, err := od.file.database.ReadAt(buffer[0:8], int64(prefixIndex)*8); err != nil {
 			return 0, 0, err
 		}
 
 		// look up locations and calculate length
 		loc = int64(binary.BigEndian.Uint64(buffer[0:8]))
-		dataLen = int64(od.database.Len()-IndexSegmentSize) - loc
+		dataLen = int64(od.file.database.Len()-IndexSegmentSize) - loc
 
 	default:
 
 		// read the required index, and the next one (to calculate length)
-		if _, err := od.database.ReadAt(buffer[0:16], int64(prefixIndex)*8); err != nil {
+		if _, err := od.file.database.ReadAt(buffer[0:16], int64(prefixIndex)*8); err != nil {
 			return 0, 0, err
 		}
 
@@ -377,9 +381,9 @@ func (od *OfflineDatabase) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 			// not a hash, hash it now
 			hash = sha1.Sum([]byte(pw))
 		}
-
+		od.logger.Sugar().Infof("using database file at %p", od.file)
+		od.logger.Sugar().Infof("checking password: %s", hex.EncodeToString(hash[:]))
 		frequency, err := od.Pwned(hash)
-		od.logger.Sugar().Infof("checking password: %v", hash)
 		if err != nil {
 			od.logger.Sugar().Warnf("error checking password: %v", err)
 			w.WriteHeader(http.StatusInternalServerError)