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