Files
core/restream/store/json.go
2023-02-01 16:09:20 +01:00

138 lines
2.5 KiB
Go

package store
import (
gojson "encoding/json"
"fmt"
"os"
"sync"
"github.com/datarhei/core/v16/encoding/json"
"github.com/datarhei/core/v16/io/fs"
"github.com/datarhei/core/v16/log"
)
type JSONConfig struct {
Filesystem fs.Filesystem
Filepath string // Full path to the database file
Logger log.Logger
}
type jsonStore struct {
fs fs.Filesystem
filepath string
logger log.Logger
// Mutex to serialize access to the backend
lock sync.RWMutex
}
var version uint64 = 4
func NewJSON(config JSONConfig) (Store, error) {
s := &jsonStore{
fs: config.Filesystem,
filepath: config.Filepath,
logger: config.Logger,
}
if len(s.filepath) == 0 {
s.filepath = "/db.json"
}
if s.fs == nil {
return nil, fmt.Errorf("no valid filesystem provided")
}
if s.logger == nil {
s.logger = log.New("")
}
return s, nil
}
func (s *jsonStore) Load() (StoreData, error) {
s.lock.Lock()
defer s.lock.Unlock()
data, err := s.load(s.filepath, version)
if err != nil {
return NewStoreData(), err
}
data.sanitize()
return data, nil
}
func (s *jsonStore) Store(data StoreData) error {
if data.Version != version {
return fmt.Errorf("invalid version (have: %d, want: %d)", data.Version, version)
}
s.lock.RLock()
defer s.lock.RUnlock()
err := s.store(s.filepath, data)
if err != nil {
return fmt.Errorf("failed to store data: %w", err)
}
return nil
}
func (s *jsonStore) store(filepath string, data StoreData) error {
jsondata, err := gojson.MarshalIndent(&data, "", " ")
if err != nil {
return err
}
_, _, err = s.fs.WriteFileSafe(filepath, jsondata)
if err != nil {
return err
}
s.logger.WithField("file", filepath).Debug().Log("Stored data")
return nil
}
type storeVersion struct {
Version uint64 `json:"version"`
}
func (s *jsonStore) load(filepath string, version uint64) (StoreData, error) {
r := NewStoreData()
_, err := s.fs.Stat(filepath)
if err != nil {
if os.IsNotExist(err) {
return r, nil
}
return r, err
}
jsondata, err := s.fs.ReadFile(filepath)
if err != nil {
return r, err
}
var db storeVersion
if err = gojson.Unmarshal(jsondata, &db); err != nil {
return r, json.FormatError(jsondata, err)
}
if db.Version != version {
return r, fmt.Errorf("unsupported version of the DB file (want: %d, have: %d)", version, db.Version)
}
if err = gojson.Unmarshal(jsondata, &r); err != nil {
return r, json.FormatError(jsondata, err)
}
s.logger.WithField("file", filepath).Debug().Log("Read data")
return r, nil
}