filebrowser/diskcache/file_cache.go
2024-04-01 18:24:06 +02:00

111 lines
2.2 KiB
Go

package diskcache
import (
"context"
"crypto/sha1" //nolint:gosec
"encoding/hex"
"errors"
"fmt"
"io"
"os"
"path/filepath"
"sync"
"github.com/spf13/afero"
)
type FileCache struct {
fs afero.Fs
// granular locks
scopedLocks struct {
sync.Mutex
sync.Once
locks map[string]sync.Locker
}
}
func New(fs afero.Fs, root string) *FileCache {
return &FileCache{
fs: afero.NewBasePathFs(fs, root),
}
}
func (f *FileCache) Store(_ context.Context, key string, value []byte) error {
mu := f.getScopedLocks(key)
mu.Lock()
defer mu.Unlock()
fileName := f.getFileName(key)
if err := f.fs.MkdirAll(filepath.Dir(fileName), 0700); err != nil { //nolint:gomnd
return err
}
if err := afero.WriteFile(f.fs, fileName, value, 0700); err != nil { //nolint:gomnd
return err
}
return nil
}
func (f *FileCache) Load(_ context.Context, key string) (value []byte, exist bool, err error) {
r, ok, err := f.open(key)
if err != nil || !ok {
return nil, ok, err
}
defer r.Close()
value, err = io.ReadAll(r)
if err != nil {
return nil, false, err
}
return value, true, nil
}
func (f *FileCache) Delete(_ context.Context, key string) error {
mu := f.getScopedLocks(key)
mu.Lock()
defer mu.Unlock()
fileName := f.getFileName(key)
if err := f.fs.Remove(fileName); err != nil && !errors.Is(err, os.ErrNotExist) {
return err
}
return nil
}
func (f *FileCache) open(key string) (afero.File, bool, error) {
fileName := f.getFileName(key)
file, err := f.fs.Open(fileName)
if err != nil {
if errors.Is(err, os.ErrNotExist) {
return nil, false, nil
}
return nil, false, err
}
return file, true, nil
}
// getScopedLocks pull lock from the map if found or create a new one
func (f *FileCache) getScopedLocks(key string) (lock sync.Locker) {
f.scopedLocks.Do(func() { f.scopedLocks.locks = map[string]sync.Locker{} })
f.scopedLocks.Lock()
lock, ok := f.scopedLocks.locks[key]
if !ok {
lock = &sync.Mutex{}
f.scopedLocks.locks[key] = lock
}
f.scopedLocks.Unlock()
return lock
}
func (f *FileCache) getFileName(key string) string {
hasher := sha1.New() //nolint:gosec
_, _ = hasher.Write([]byte(key))
hash := hex.EncodeToString(hasher.Sum(nil))
return fmt.Sprintf("%s/%s/%s", hash[:1], hash[1:3], hash)
}