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restic/internal/backend/mem/mem_backend.go
Alexander Neumann 99f7fd74e3 backend: Improve Save()
As mentioned in issue [#1560](https://github.com/restic/restic/pull/1560#issuecomment-364689346)
this changes the signature for `backend.Save()`. It now takes a
parameter of interface type `RewindReader`, so that the backend
implementations or our `RetryBackend` middleware can reset the reader to
the beginning and then retry an upload operation.

The `RewindReader` interface also provides a `Length()` method, which is
used in the backend to get the size of the data to be saved. This
removes several ugly hacks we had to do to pull the size back out of the
`io.Reader` passed to `Save()` before. In the `s3` and `rest` backend
this is actively used.
2018-03-03 15:49:44 +01:00

224 lines
4.4 KiB
Go

package mem
import (
"bytes"
"context"
"io"
"io/ioutil"
"sync"
"github.com/restic/restic/internal/backend"
"github.com/restic/restic/internal/errors"
"github.com/restic/restic/internal/restic"
"github.com/restic/restic/internal/debug"
)
type memMap map[restic.Handle][]byte
// make sure that MemoryBackend implements backend.Backend
var _ restic.Backend = &MemoryBackend{}
var errNotFound = errors.New("not found")
// MemoryBackend is a mock backend that uses a map for storing all data in
// memory. This should only be used for tests.
type MemoryBackend struct {
data memMap
m sync.Mutex
}
// New returns a new backend that saves all data in a map in memory.
func New() *MemoryBackend {
be := &MemoryBackend{
data: make(memMap),
}
debug.Log("created new memory backend")
return be
}
// Test returns whether a file exists.
func (be *MemoryBackend) Test(ctx context.Context, h restic.Handle) (bool, error) {
be.m.Lock()
defer be.m.Unlock()
debug.Log("Test %v", h)
if _, ok := be.data[h]; ok {
return true, nil
}
return false, nil
}
// IsNotExist returns true if the file does not exist.
func (be *MemoryBackend) IsNotExist(err error) bool {
return errors.Cause(err) == errNotFound
}
// Save adds new Data to the backend.
func (be *MemoryBackend) Save(ctx context.Context, h restic.Handle, rd restic.RewindReader) error {
if err := h.Valid(); err != nil {
return err
}
be.m.Lock()
defer be.m.Unlock()
if h.Type == restic.ConfigFile {
h.Name = ""
}
if _, ok := be.data[h]; ok {
return errors.New("file already exists")
}
buf, err := ioutil.ReadAll(rd)
if err != nil {
return err
}
be.data[h] = buf
debug.Log("saved %v bytes at %v", len(buf), h)
return nil
}
// Load runs fn with a reader that yields the contents of the file at h at the
// given offset.
func (be *MemoryBackend) Load(ctx context.Context, h restic.Handle, length int, offset int64, fn func(rd io.Reader) error) error {
return backend.DefaultLoad(ctx, h, length, offset, be.openReader, fn)
}
func (be *MemoryBackend) openReader(ctx context.Context, h restic.Handle, length int, offset int64) (io.ReadCloser, error) {
if err := h.Valid(); err != nil {
return nil, err
}
be.m.Lock()
defer be.m.Unlock()
if h.Type == restic.ConfigFile {
h.Name = ""
}
debug.Log("Load %v offset %v len %v", h, offset, length)
if offset < 0 {
return nil, errors.New("offset is negative")
}
if _, ok := be.data[h]; !ok {
return nil, errNotFound
}
buf := be.data[h]
if offset > int64(len(buf)) {
return nil, errors.New("offset beyond end of file")
}
buf = buf[offset:]
if length > 0 && len(buf) > length {
buf = buf[:length]
}
return ioutil.NopCloser(bytes.NewReader(buf)), nil
}
// Stat returns information about a file in the backend.
func (be *MemoryBackend) Stat(ctx context.Context, h restic.Handle) (restic.FileInfo, error) {
be.m.Lock()
defer be.m.Unlock()
if err := h.Valid(); err != nil {
return restic.FileInfo{}, err
}
if h.Type == restic.ConfigFile {
h.Name = ""
}
debug.Log("stat %v", h)
e, ok := be.data[h]
if !ok {
return restic.FileInfo{}, errNotFound
}
return restic.FileInfo{Size: int64(len(e)), Name: h.Name}, nil
}
// Remove deletes a file from the backend.
func (be *MemoryBackend) Remove(ctx context.Context, h restic.Handle) error {
be.m.Lock()
defer be.m.Unlock()
debug.Log("Remove %v", h)
if _, ok := be.data[h]; !ok {
return errNotFound
}
delete(be.data, h)
return nil
}
// List returns a channel which yields entries from the backend.
func (be *MemoryBackend) List(ctx context.Context, t restic.FileType, fn func(restic.FileInfo) error) error {
entries := make(map[string]int64)
be.m.Lock()
for entry, buf := range be.data {
if entry.Type != t {
continue
}
entries[entry.Name] = int64(len(buf))
}
be.m.Unlock()
for name, size := range entries {
fi := restic.FileInfo{
Name: name,
Size: size,
}
if ctx.Err() != nil {
return ctx.Err()
}
err := fn(fi)
if err != nil {
return err
}
if ctx.Err() != nil {
return ctx.Err()
}
}
return ctx.Err()
}
// Location returns the location of the backend (RAM).
func (be *MemoryBackend) Location() string {
return "RAM"
}
// Delete removes all data in the backend.
func (be *MemoryBackend) Delete(ctx context.Context) error {
be.m.Lock()
defer be.m.Unlock()
be.data = make(memMap)
return nil
}
// Close closes the backend.
func (be *MemoryBackend) Close() error {
return nil
}