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package savers
/****************
* Date: 30/05/16
* Time: 5:48 PM
***************/
import (
"encoding/gob"
"github.com/twinj/uuid"
"log"
"os"
"path"
"time"
)
var _ uuid.Saver = &FileSystemSaver{}
// This implements the Saver interface for UUIDs
type FileSystemSaver struct {
// A file to save the state to
// Used gob format on uuid.State entity
file *os.File
// Preferred location for the store
Path string
// Whether to log each save
Report bool
// The amount of time between each save call
time.Duration
// The next time to save
uuid.Timestamp
}
func (o *FileSystemSaver) Save(pStore uuid.Store) {
if pStore.Timestamp >= o.Timestamp {
err := o.openAndDo(o.encode, &pStore)
if err == nil {
if o.Report {
log.Printf("UUID Saved State Storage: %s", pStore)
}
}
o.Timestamp = pStore.Add(o.Duration)
}
}
func (o *FileSystemSaver) Read() (err error, store uuid.Store) {
store = uuid.Store{}
gob.Register(&uuid.Store{})
if _, err = os.Stat(o.Path); os.IsNotExist(err) {
dir, file := path.Split(o.Path)
if dir == "" || dir == "/" {
dir = os.TempDir()
}
o.Path = path.Join(dir, file)
err = os.MkdirAll(dir, os.ModeDir|0755)
if err == nil {
// If new encode blank store
err = o.openAndDo(o.encode, &store)
if err == nil {
log.Println("uuid.FileSystemSaver created", o.Path)
}
}
log.Println("uuid.FileSystemSaver.Read: error will autogenerate", err)
return
}
o.openAndDo(o.decode, &store)
return
}
func (o *FileSystemSaver) openAndDo(fDo func(*uuid.Store), pStore *uuid.Store) (err error) {
o.file, err = os.OpenFile(o.Path, os.O_RDWR|os.O_CREATE, os.ModeExclusive)
defer o.file.Close()
if err == nil {
fDo(pStore)
} else {
log.Println("uuid.FileSystemSaver.openAndDo error:", err)
}
return
}
func (o *FileSystemSaver) encode(pStore *uuid.Store) {
// ensure reader state is ready for use
enc := gob.NewEncoder(o.file)
// swallow error for encode as its only for cyclic pointers
enc.Encode(&pStore)
}
func (o *FileSystemSaver) decode(pStore *uuid.Store) {
// ensure reader state is ready for use
o.file.Seek(0, 0)
dec := gob.NewDecoder(o.file)
// swallow error for encode as its only for cyclic pointers
dec.Decode(&pStore)
}
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