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Simplify dry run backend

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This commit is contained in:
Alexander Weiss 2021-02-23 16:09:29 +01:00 committed by Michael Eischer
parent 77bf148460
commit 38a8a48a25
2 changed files with 52 additions and 166 deletions
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183
internal/backend/dryrun/dry_backend.go
View file

@ -3,186 +3,77 @@ package dryrun
import (
"context"
"io"
"io/ioutil"
"sync"
"github.com/restic/restic/internal/errors"
"github.com/restic/restic/internal/restic"
"github.com/restic/restic/internal/debug"
"github.com/restic/restic/internal/restic"
)
type sizeMap map[restic.Handle]int
var errNotFound = errors.New("not found")
// Backend passes reads through to an underlying layer and only records
// metadata about writes. This is used for `backup --dry-run`.
// It is directly derivted from the mem backend.
// Backend passes reads through to an underlying layer and accepts writes, but
// doesn't do anything. Also removes are ignored.
// So in fact, this backend silently ignores all operations that would modify
// the repo and does normal operations else.
// This is used for `backup --dry-run`.
type Backend struct {
be restic.Backend
data sizeMap
m sync.Mutex
b restic.Backend
}
// statically ensure that RetryBackend implements restic.Backend.
var _ restic.Backend = &Backend{}
// New returns a new backend that saves all data in a map in memory.
func New(be restic.Backend) *Backend {
b := &Backend{
be: be,
data: make(sizeMap),
}
b := &Backend{b: be}
debug.Log("created new dry backend")
return b
}
// Test returns whether a file exists.
func (be *Backend) 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 be.be.Test(ctx, h)
}
// IsNotExist returns true if the file does not exist.
func (be *Backend) IsNotExist(err error) bool {
return errors.Cause(err) == errNotFound || be.be.IsNotExist(err)
}
// Save adds new Data to the backend.
func (be *Backend) 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] = len(buf)
debug.Log("faked saving %v bytes at %v", len(buf), h)
debug.Log("faked saving %v bytes at %v", rd.Length(), h)
// don't save anything, just return ok
return nil
}
// Load runs fn with a reader that yields the contents of the file at h at the
// given offset.
func (be *Backend) Load(ctx context.Context, h restic.Handle, length int, offset int64, fn func(rd io.Reader) error) error {
be.m.Lock()
defer be.m.Unlock()
if _, ok := be.data[h]; ok {
return errors.New("can't read file saved on dry backend")
}
return be.be.Load(ctx, h, length, offset, fn)
}
// Stat returns information about a file in the backend.
func (be *Backend) Stat(ctx context.Context, h restic.Handle) (restic.FileInfo, error) {
if err := h.Valid(); err != nil {
return restic.FileInfo{}, err
}
be.m.Lock()
defer be.m.Unlock()
if h.Type == restic.ConfigFile {
h.Name = ""
}
debug.Log("stat %v", h)
s, ok := be.data[h]
if !ok {
return be.be.Stat(ctx, h)
}
return restic.FileInfo{Size: int64(s), Name: h.Name}, nil
}
// Remove deletes a file from the backend.
func (be *Backend) 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 *Backend) List(ctx context.Context, t restic.FileType, fn func(restic.FileInfo) error) error {
entries := []restic.FileInfo{}
be.m.Lock()
for entry, size := range be.data {
if entry.Type != t {
continue
}
entries = append(entries, restic.FileInfo{
Name: entry.Name,
Size: int64(size),
})
}
be.m.Unlock()
for _, entry := range entries {
if ctx.Err() != nil {
return ctx.Err()
}
err := fn(entry)
if err != nil {
return err
}
if ctx.Err() != nil {
return ctx.Err()
}
}
if ctx.Err() != nil {
return ctx.Err()
}
return be.be.List(ctx, t, fn)
}
// Location returns the location of the backend (RAM).
// Location returns the location of the backend.
func (be *Backend) Location() string {
return "DRY:" + be.be.Location()
return "DRY:" + be.b.Location()
}
// Delete removes all data in the backend.
func (be *Backend) Delete(ctx context.Context) error {
return errors.New("dry-run doesn't support Delete()")
return nil
}
// Close closes the backend.
func (be *Backend) Close() error {
return be.be.Close()
return be.b.Close()
}
func (be *Backend) IsNotExist(err error) bool {
return be.b.IsNotExist(err)
}
func (be *Backend) List(ctx context.Context, t restic.FileType, fn func(restic.FileInfo) error) error {
return be.b.List(ctx, t, fn)
}
func (be *Backend) Load(ctx context.Context, h restic.Handle, length int, offset int64, fn func(io.Reader) error) error {
return be.b.Load(ctx, h, length, offset, fn)
}
func (be *Backend) Stat(ctx context.Context, h restic.Handle) (restic.FileInfo, error) {
return be.b.Stat(ctx, h)
}
func (be *Backend) Test(ctx context.Context, h restic.Handle) (bool, error) {
return be.b.Test(ctx, h)
}

35
internal/backend/dryrun/dry_backend_test.go
View file

@ -24,11 +24,9 @@ func newBackends() (*dryrun.Backend, restic.Backend) {
}
func TestDry(t *testing.T) {
d, m := newBackends()
m.Save(context.TODO(), restic.Handle{}, restic.NewByteReader([]byte("foo")))
ctx := context.TODO()
d, m := newBackends()
// Since the dry backend is a mostly write-only overlay, the standard backend test suite
// won't pass. Instead, perform a series of operations over the backend, testing the state
// at each step.
@ -40,26 +38,28 @@ func TestDry(t *testing.T) {
wantErr string
}{
{d, "loc", "", "DRY:RAM", ""},
{d, "delete", "", "", "doesn't support"},
{d, "delete", "", "", ""},
{d, "stat", "a", "", "not found"},
{d, "list", "", "", ""},
{d, "save", "", "", "invalid"},
{d, "test", "a", "", ""},
{m, "save", "a", "baz", ""},
{d, "save", "b", "foob", ""},
{d, "save", "b", "asdf", "already exists"},
{m, "save", "a", "baz", ""}, // save a directly to the mem backend
{d, "save", "b", "foob", ""}, // b is not saved
{d, "save", "b", "xxx", ""}, // no error as b is not saved
{d, "test", "a", "1", ""},
{d, "test", "b", "1", ""},
{d, "test", "b", "", ""},
{d, "stat", "", "", "invalid"},
{d, "stat", "a", "a 3", ""},
{d, "stat", "b", "b 4", ""},
{d, "load", "a", "baz", ""},
{d, "load", "b", "", "can't read file"},
{d, "list", "", "a b", ""},
{d, "remove", "c", "", "not found"},
{d, "remove", "b", "", ""},
{d, "load", "b", "", "not found"},
{d, "list", "", "a", ""},
{d, "remove", "c", "", ""},
{d, "stat", "b", "", "not found"},
{d, "list", "", "a", ""},
{d, "remove", "a", "", ""}, // a is in fact not removed
{d, "list", "", "a", ""},
{m, "remove", "a", "", ""}, // remove a from the mem backend
{d, "list", "", "", ""},
{d, "close", "", "", ""},
{d, "close", "", "", ""},
}
@ -68,7 +68,7 @@ func TestDry(t *testing.T) {
var err error
var boolRes bool
handle := restic.Handle{Type: restic.DataFile, Name: step.fname}
handle := restic.Handle{Type: restic.PackFile, Name: step.fname}
switch step.op {
case "save":
err = step.be.Save(ctx, handle, restic.NewByteReader([]byte(step.content)))
@ -79,12 +79,7 @@ func TestDry(t *testing.T) {
}
case "list":
fileList := []string{}
err = step.be.List(ctx, restic.DataFile, func(fi restic.FileInfo) error {
for _, n := range fileList {
if n == fi.Name {
return nil
}
}
err = step.be.List(ctx, restic.PackFile, func(fi restic.FileInfo) error {
fileList = append(fileList, fi.Name)
return nil
})