mirror of
https://github.com/restic/restic.git
synced 2024-08-25 13:47:22 +02:00
386 lines
9.2 KiB
Go
386 lines
9.2 KiB
Go
package repository
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import (
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"encoding/json"
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"errors"
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"fmt"
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"io"
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"sync"
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"github.com/restic/restic/backend"
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"github.com/restic/restic/crypto"
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"github.com/restic/restic/debug"
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"github.com/restic/restic/pack"
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)
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// Index holds a lookup table for id -> pack.
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type Index struct {
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m sync.Mutex
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pack map[backend.ID]indexEntry
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}
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type indexEntry struct {
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tpe pack.BlobType
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packID *backend.ID
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offset uint
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length uint
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old bool
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}
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// NewIndex returns a new index.
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func NewIndex() *Index {
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return &Index{
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pack: make(map[backend.ID]indexEntry),
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}
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}
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func (idx *Index) store(t pack.BlobType, id backend.ID, pack *backend.ID, offset, length uint, old bool) {
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idx.pack[id] = indexEntry{
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tpe: t,
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packID: pack,
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offset: offset,
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length: length,
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old: old,
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}
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}
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// Store remembers the id and pack in the index. An existing entry will be
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// silently overwritten.
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func (idx *Index) Store(t pack.BlobType, id backend.ID, pack *backend.ID, offset, length uint) {
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idx.m.Lock()
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defer idx.m.Unlock()
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debug.Log("Index.Store", "pack %v contains id %v (%v), offset %v, length %v",
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pack.Str(), id.Str(), t, offset, length)
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idx.store(t, id, pack, offset, length, false)
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}
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// StoreInProgress adds a preliminary index entry for a blob that is about to be
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// saved. The entry must be updated using Store once the the blob has been
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// written to a pack. Adding an preliminary index fails if there's an existing
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// entry associated with the same id.
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func (idx *Index) StoreInProgress(t pack.BlobType, id backend.ID) error {
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idx.m.Lock()
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defer idx.m.Unlock()
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if _, hasID := idx.pack[id]; hasID {
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errorMsg := fmt.Sprintf("index already contains id %v (%v)", id.Str(), t)
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debug.Log("Index.StoreInProgress", errorMsg)
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return errors.New(errorMsg)
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}
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idx.store(t, id, nil, 0, 0, false)
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debug.Log("Index.StoreInProgress", "preliminary entry added for id %v (%v)",
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id.Str(), t)
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return nil
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}
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// Remove removes the pack ID from the index.
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func (idx *Index) Remove(packID backend.ID) {
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idx.m.Lock()
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defer idx.m.Unlock()
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debug.Log("Index.Remove", "id %v removed", packID.Str())
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if _, ok := idx.pack[packID]; ok {
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delete(idx.pack, packID)
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}
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}
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// Lookup returns the pack for the id.
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func (idx *Index) Lookup(id backend.ID) (packID *backend.ID, tpe pack.BlobType, offset, length uint, err error) {
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idx.m.Lock()
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defer idx.m.Unlock()
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if p, ok := idx.pack[id]; ok {
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debug.Log("Index.Lookup", "id %v found in pack %v at %d, length %d",
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id.Str(), p.packID.Str(), p.offset, p.length)
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return p.packID, p.tpe, p.offset, p.length, nil
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}
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debug.Log("Index.Lookup", "id %v not found", id.Str())
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return nil, pack.Data, 0, 0, fmt.Errorf("id %v not found in index", id)
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}
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// Has returns true iff the id is listed in the index.
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func (idx *Index) Has(id backend.ID) bool {
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_, _, _, _, err := idx.Lookup(id)
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if err == nil {
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return true
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}
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return false
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}
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// LookupSize returns the length of the cleartext content behind the
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// given id
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func (idx *Index) LookupSize(id backend.ID) (cleartextLength uint, err error) {
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_, _, _, encryptedLength, err := idx.Lookup(id)
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if err != nil {
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return 0, err
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}
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return encryptedLength - crypto.Extension, nil
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}
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// Merge loads all items from other into idx.
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func (idx *Index) Merge(other *Index) {
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debug.Log("Index.Merge", "Merge index with %p", other)
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idx.m.Lock()
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defer idx.m.Unlock()
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for k, v := range other.pack {
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if _, ok := idx.pack[k]; ok {
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debug.Log("Index.Merge", "index already has key %v, updating", k.Str())
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}
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idx.pack[k] = v
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}
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debug.Log("Index.Merge", "done merging index")
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}
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// PackedBlob is a blob already saved within a pack.
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type PackedBlob struct {
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pack.Blob
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PackID backend.ID
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}
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// Each returns a channel that yields all blobs known to the index. If done is
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// closed, the background goroutine terminates. This blocks any modification of
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// the index.
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func (idx *Index) Each(done chan struct{}) <-chan PackedBlob {
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idx.m.Lock()
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ch := make(chan PackedBlob)
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go func() {
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defer idx.m.Unlock()
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defer func() {
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close(ch)
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}()
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for id, blob := range idx.pack {
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select {
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case <-done:
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return
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case ch <- PackedBlob{
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Blob: pack.Blob{
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ID: id,
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Offset: blob.offset,
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Type: blob.tpe,
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Length: blob.length,
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},
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PackID: *blob.packID,
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}:
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}
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}
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}()
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return ch
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}
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// Count returns the number of blobs of type t in the index.
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func (idx *Index) Count(t pack.BlobType) (n uint) {
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debug.Log("Index.Count", "counting blobs of type %v", t)
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idx.m.Lock()
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defer idx.m.Unlock()
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for id, blob := range idx.pack {
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if blob.tpe == t {
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n++
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debug.Log("Index.Count", " blob %v counted: %v", id.Str(), blob)
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}
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}
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return
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}
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type packJSON struct {
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ID backend.ID `json:"id"`
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Blobs []blobJSON `json:"blobs"`
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}
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type blobJSON struct {
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ID backend.ID `json:"id"`
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Type pack.BlobType `json:"type"`
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Offset uint `json:"offset"`
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Length uint `json:"length"`
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}
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// generatePackList returns a list of packs containing only the index entries
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// that selsectFn returned true for. If selectFn is nil, the list contains all
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// blobs in the index.
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func (idx *Index) generatePackList(selectFn func(indexEntry) bool) ([]*packJSON, error) {
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list := []*packJSON{}
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packs := make(map[backend.ID]*packJSON)
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for id, blob := range idx.pack {
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if blob.packID == nil {
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panic("nil pack id")
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}
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if selectFn != nil && !selectFn(blob) {
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continue
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}
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debug.Log("Index.generatePackList", "handle blob %v", id.Str())
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if blob.packID.IsNull() {
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debug.Log("Index.generatePackList", "blob %q has no packID! (type %v, offset %v, length %v)",
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id.Str(), blob.tpe, blob.offset, blob.length)
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return nil, fmt.Errorf("unable to serialize index: pack for blob %v hasn't been written yet", id)
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}
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// see if pack is already in map
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p, ok := packs[*blob.packID]
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if !ok {
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// else create new pack
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p = &packJSON{ID: *blob.packID}
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// and append it to the list and map
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list = append(list, p)
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packs[p.ID] = p
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}
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// add blob
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p.Blobs = append(p.Blobs, blobJSON{
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ID: id,
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Type: blob.tpe,
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Offset: blob.offset,
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Length: blob.length,
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})
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}
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debug.Log("Index.generatePackList", "done")
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return list, nil
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}
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type jsonIndex struct {
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Supersedes []backend.ID `json:"supersedes,omitempty"`
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Packs []*packJSON `json:"packs"`
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}
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type jsonOldIndex []*packJSON
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// encode writes the JSON serialization of the index filtered by selectFn to enc.
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func (idx *Index) encode(w io.Writer, supersedes []backend.ID, selectFn func(indexEntry) bool) error {
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list, err := idx.generatePackList(func(entry indexEntry) bool {
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return !entry.old
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})
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if err != nil {
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return err
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}
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debug.Log("Index.Encode", "done")
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enc := json.NewEncoder(w)
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idxJSON := jsonIndex{
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Supersedes: supersedes,
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Packs: list,
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}
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return enc.Encode(idxJSON)
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}
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// Encode writes the JSON serialization of the index to the writer w. This
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// serialization only contains new blobs added via idx.Store(), not old ones
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// introduced via DecodeIndex().
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func (idx *Index) Encode(w io.Writer) error {
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debug.Log("Index.Encode", "encoding index")
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idx.m.Lock()
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defer idx.m.Unlock()
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return idx.encode(w, nil, func(e indexEntry) bool { return !e.old })
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}
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// Dump writes the pretty-printed JSON representation of the index to w.
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func (idx *Index) Dump(w io.Writer) error {
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debug.Log("Index.Dump", "dumping index")
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idx.m.Lock()
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defer idx.m.Unlock()
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list, err := idx.generatePackList(nil)
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if err != nil {
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return err
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}
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buf, err := json.MarshalIndent(list, "", " ")
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if err != nil {
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return err
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}
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_, err = w.Write(append(buf, '\n'))
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if err != nil {
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return err
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}
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debug.Log("Index.Dump", "done")
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return nil
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}
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// isErrOldIndex returns true if the error may be caused by an old index
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// format.
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func isErrOldIndex(err error) bool {
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if e, ok := err.(*json.UnmarshalTypeError); ok && e.Value == "array" {
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return true
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}
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return false
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}
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// ErrOldIndexFormat means an index with the old format was detected.
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var ErrOldIndexFormat = errors.New("index has old format")
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// DecodeIndex loads and unserializes an index from rd.
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func DecodeIndex(rd io.Reader) (*Index, backend.IDs, error) {
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debug.Log("Index.DecodeIndex", "Start decoding index")
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idxJSON := jsonIndex{}
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dec := json.NewDecoder(rd)
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err := dec.Decode(&idxJSON)
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if err != nil {
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debug.Log("Index.DecodeIndex", "Error %#v", err)
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if isErrOldIndex(err) {
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debug.Log("Index.DecodeIndex", "index is probably old format, trying that")
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err = ErrOldIndexFormat
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}
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return nil, nil, err
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}
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idx := NewIndex()
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for _, pack := range idxJSON.Packs {
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for _, blob := range pack.Blobs {
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idx.store(blob.Type, blob.ID, &pack.ID, blob.Offset, blob.Length, true)
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}
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}
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debug.Log("Index.DecodeIndex", "done")
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return idx, idxJSON.Supersedes, err
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}
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// DecodeOldIndex loads and unserializes an index in the old format from rd.
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func DecodeOldIndex(rd io.Reader) (*Index, backend.IDs, error) {
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debug.Log("Index.DecodeOldIndex", "Start decoding old index")
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list := []*packJSON{}
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dec := json.NewDecoder(rd)
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err := dec.Decode(&list)
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if err != nil {
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debug.Log("Index.DecodeOldIndex", "Error %#v", err)
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return nil, nil, err
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}
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idx := NewIndex()
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for _, pack := range list {
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for _, blob := range pack.Blobs {
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idx.store(blob.Type, blob.ID, &pack.ID, blob.Offset, blob.Length, true)
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}
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}
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debug.Log("Index.DecodeOldIndex", "done")
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return idx, backend.IDs{}, err
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}
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