package backend import ( "context" "io" "io/ioutil" "math/rand" "sync" "github.com/restic/restic/internal/errors" "github.com/restic/restic/internal/restic" ) // ErrorBackend is used to induce errors into various function calls and test // the retry functions. type ErrorBackend struct { FailSave float32 FailSaveRead float32 FailLoad float32 FailStat float32 restic.Backend r *rand.Rand m sync.Mutex } // statically ensure that ErrorBackend implements restic.Backend. var _ restic.Backend = &ErrorBackend{} // NewErrorBackend wraps be with a backend that returns errors according to // given probabilities. func NewErrorBackend(be restic.Backend, seed int64) *ErrorBackend { return &ErrorBackend{ Backend: be, r: rand.New(rand.NewSource(seed)), } } func (be *ErrorBackend) fail(p float32) bool { be.m.Lock() v := be.r.Float32() be.m.Unlock() return v < p } // Save stores the data in the backend under the given handle. func (be *ErrorBackend) Save(ctx context.Context, h restic.Handle, rd io.Reader) error { if be.fail(be.FailSave) { return errors.Errorf("Save(%v) random error induced", h) } if be.fail(be.FailSaveRead) { _, err := io.CopyN(ioutil.Discard, rd, be.r.Int63n(1000)) if err != nil { return err } return errors.Errorf("Save(%v) random error with partial read induced", h) } return be.Backend.Save(ctx, h, rd) } // Load returns a reader that yields the contents of the file at h at the // given offset. If length is larger than zero, only a portion of the file // is returned. rd must be closed after use. If an error is returned, the // ReadCloser must be nil. func (be *ErrorBackend) Load(ctx context.Context, h restic.Handle, length int, offset int64, consumer func(rd io.Reader) error) error { if be.fail(be.FailLoad) { return errors.Errorf("Load(%v, %v, %v) random error induced", h, length, offset) } return be.Backend.Load(ctx, h, length, offset, consumer) } // Stat returns information about the File identified by h. func (be *ErrorBackend) Stat(ctx context.Context, h restic.Handle) (restic.FileInfo, error) { if be.fail(be.FailLoad) { return restic.FileInfo{}, errors.Errorf("Stat(%v) random error induced", h) } return be.Stat(ctx, h) }