119 lines
2.2 KiB
Go
119 lines
2.2 KiB
Go
package main
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import (
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"encoding/gob"
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"errors"
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"fmt"
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"log"
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"os"
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"time"
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)
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type DiskStorage struct {
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stateFile string
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lastSave int64
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LastSaves map[CartId]int64
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}
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func NewDiskStorage(stateFile string) (*DiskStorage, error) {
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ret := &DiskStorage{
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stateFile: stateFile,
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LastSaves: make(map[CartId]int64),
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}
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err := ret.loadState()
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return ret, err
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}
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func saveMessages(messages []StorableMessage, id CartId) error {
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log.Printf("%d messages to save for %s", len(messages), id)
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if len(messages) == 0 {
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return nil
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}
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var file *os.File
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var err error
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path := getCartPath(id.String())
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file, err = os.OpenFile(path, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
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if err != nil {
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return err
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}
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defer file.Close()
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for _, m := range messages {
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err := m.Write(file)
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if err != nil {
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return err
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}
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}
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return err
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}
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func getCartPath(id string) string {
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return fmt.Sprintf("data/%s.prot", id)
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}
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func loadMessages(grain Grain, id CartId) error {
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var err error
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path := getCartPath(id.String())
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if _, err = os.Stat(path); errors.Is(err, os.ErrNotExist) {
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return err
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}
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file, err := os.Open(path)
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if err != nil {
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return err
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}
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defer file.Close()
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for err == nil {
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var msg Message
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err = MessageFromReader(file, &msg)
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if err == nil {
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grain.HandleMessage(&msg, true)
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}
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}
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if err.Error() == "EOF" {
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return nil
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}
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return err
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}
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func (s *DiskStorage) saveState() error {
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tmpFile := s.stateFile + "_tmp"
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file, err := os.Create(tmpFile)
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if err != nil {
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return err
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}
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defer file.Close()
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err = gob.NewEncoder(file).Encode(s.LastSaves)
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if err != nil {
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return err
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}
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os.Remove(s.stateFile + ".bak")
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os.Rename(s.stateFile, s.stateFile+".bak")
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return os.Rename(tmpFile, s.stateFile)
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}
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func (s *DiskStorage) loadState() error {
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file, err := os.Open(s.stateFile)
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if err != nil {
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return err
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}
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defer file.Close()
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return gob.NewDecoder(file).Decode(&s.LastSaves)
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}
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func (s *DiskStorage) Store(id CartId, grain *CartGrain) error {
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lastSavedMessage, ok := s.LastSaves[id]
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if ok && lastSavedMessage > grain.GetLastChange() {
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return nil
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}
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err := saveMessages(grain.GetStorageMessage(lastSavedMessage), id)
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if err != nil {
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return err
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}
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ts := time.Now().Unix()
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s.LastSaves[id] = ts
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s.lastSave = ts
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return nil
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}
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