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