refactor/serializing (#1)

Co-authored-by: matst80 <mats.tornberg@gmail.com>
Reviewed-on: https://git.tornberg.me/mats/go-cart-actor/pulls/1

disk-storage.go

@@ -1,7 +1,7 @@
 package main
 
 import (
-	"encoding/json"
+	"encoding/gob"
 	"errors"
 	"fmt"
 	"log"
@@ -12,26 +12,26 @@ import (
 type DiskStorage struct {
 	stateFile string
 	lastSave  int64
-	LastSaves map[string]int64
+	LastSaves map[CartId]int64
 }
 
 func NewDiskStorage(stateFile string) (*DiskStorage, error) {
 	ret := &DiskStorage{
 		stateFile: stateFile,
-		LastSaves: make(map[string]int64),
+		LastSaves: make(map[CartId]int64),
 	}
 	err := ret.loadState()
 	return ret, err
 }
 
-func saveMessages(messages []StorableMessage, id string) error {
+func saveMessages(messages []StorableMessage, id CartId) error {
 	log.Printf("%d messages to save for %s", len(messages), id)
 	if len(messages) == 0 {
 		return nil
 	}
 	var file *os.File
 	var err error
-	path := getCartPath(id)
+	path := getCartPath(id.String())
 	file, err = os.OpenFile(path, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
 	if err != nil {
 		return err
@@ -39,11 +39,10 @@ func saveMessages(messages []StorableMessage, id string) error {
 	defer file.Close()
 
 	for _, m := range messages {
-		b, err := m.GetBytes()
+		err := m.Write(file)
 		if err != nil {
 			return err
 		}
-		file.Write(b)
 	}
 	return err
 }
@@ -52,9 +51,9 @@ func getCartPath(id string) string {
 	return fmt.Sprintf("data/%s.prot", id)
 }
 
-func loadMessages(grain Grain, id string) error {
+func loadMessages(grain Grain, id CartId) error {
 	var err error
-	path := getCartPath(id)
+	path := getCartPath(id.String())
 	if _, err = os.Stat(path); errors.Is(err, os.ErrNotExist) {
 		return err
 	}
@@ -64,13 +63,11 @@ func loadMessages(grain Grain, id string) error {
 	}
 	defer file.Close()
 
-	var reply CartGrain
-
 	for err == nil {
-		msg := &Message{}
-		err = msg.FromReader(file, msg)
+		var msg Message
+		err = MessageFromReader(file, &msg)
 		if err == nil {
-			grain.HandleMessage(msg, true, &reply)
+			grain.HandleMessage(&msg, true)
 		}
 	}
 
@@ -87,7 +84,7 @@ func (s *DiskStorage) saveState() error {
 		return err
 	}
 	defer file.Close()
-	err = json.NewEncoder(file).Encode(s.LastSaves)
+	err = gob.NewEncoder(file).Encode(s.LastSaves)
 	if err != nil {
 		return err
 	}
@@ -97,15 +94,15 @@ func (s *DiskStorage) saveState() error {
 }
 
 func (s *DiskStorage) loadState() error {
-	file, err := os.Open("data/state.json")
+	file, err := os.Open(s.stateFile)
 	if err != nil {
 		return err
 	}
 	defer file.Close()
-	return json.NewDecoder(file).Decode(&s.LastSaves)
+	return gob.NewDecoder(file).Decode(&s.LastSaves)
 }
 
-func (s *DiskStorage) Store(id string, grain Grain) error {
+func (s *DiskStorage) Store(id CartId, grain *CartGrain) error {
 	lastSavedMessage, ok := s.LastSaves[id]
 	if ok && lastSavedMessage > grain.GetLastChange() {
 		return nil