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copy: Mark and skip previously copied snapshots

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Use the `Original` field of the copied snapshot to store a persistent
snapshot ID. This can either be the ID of the source snapshot if
`Original` was not yet set or the previous value stored in the
`Original` field. In order to still copy snapshots modified using the
tags command the source snapshot is compared to all snapshots in the
destination repository which have the same persistent ID. Snapshots are
only considered equal if all fields except `Original` and `Parent`
match. That way modified snapshots are still copied while avoiding
duplicate copies at the same time.
This commit is contained in:
Michael Eischer 2020-08-22 16:09:08 +02:00
parent b0a8c4ad6c
commit ec9a53b7e8
1 changed files with 52 additions and 3 deletions
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55
cmd/restic/cmd_copy.go
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@ -109,9 +109,36 @@ func runCopy(opts CopyOptions, gopts GlobalOptions, args []string) error {
}
visitedTrees := restic.NewIDSet()
dstSnapshotByOriginal := make(map[restic.ID][]*restic.Snapshot)
for sn := range FindFilteredSnapshots(ctx, dstRepo, opts.Hosts, opts.Tags, opts.Paths, nil) {
if sn.Original != nil && !sn.Original.IsNull() {
dstSnapshotByOriginal[*sn.Original] = append(dstSnapshotByOriginal[*sn.Original], sn)
}
// also consider identical snapshot copies
dstSnapshotByOriginal[*sn.ID()] = append(dstSnapshotByOriginal[*sn.ID()], sn)
}
for sn := range FindFilteredSnapshots(ctx, srcRepo, opts.Hosts, opts.Tags, opts.Paths, args) {
Verbosef("snapshot %s of %v at %s)\n", sn.ID().Str(), sn.Paths, sn.Time)
Verbosef("\nsnapshot %s of %v at %s)\n", sn.ID().Str(), sn.Paths, sn.Time)
// check whether the destination has a snapshot with the same persistent ID which has similar snapshot fields
srcOriginal := *sn.ID()
if sn.Original != nil {
srcOriginal = *sn.Original
}
if originalSns, ok := dstSnapshotByOriginal[srcOriginal]; ok {
isCopy := false
for _, originalSn := range originalSns {
if similarSnapshots(originalSn, sn) {
Verbosef("skipping source snapshot %s, was already copied to snapshot %s\n", sn.ID().Str(), originalSn.ID().Str())
isCopy = true
break
}
}
if isCopy {
continue
}
}
Verbosef(" copy started, this may take a while...\n")
if err := copyTree(ctx, srcRepo, dstRepo, *sn.Tree, visitedTrees); err != nil {
@ -125,8 +152,11 @@ func runCopy(opts CopyOptions, gopts GlobalOptions, args []string) error {
debug.Log("flushed packs and saved index")
// save snapshot
sn.Parent = nil // Parent does not have relevance in the new repo.
sn.Original = nil // Original does not have relevance in the new repo.
sn.Parent = nil // Parent does not have relevance in the new repo.
// Use Original as a persistent snapshot ID
if sn.Original == nil {
sn.Original = sn.ID()
}
newID, err := dstRepo.SaveJSONUnpacked(ctx, restic.SnapshotFile, sn)
if err != nil {
return err
@ -136,6 +166,25 @@ func runCopy(opts CopyOptions, gopts GlobalOptions, args []string) error {
return nil
}
func similarSnapshots(sna *restic.Snapshot, snb *restic.Snapshot) bool {
// everything except Parent and Original must match
if !sna.Time.Equal(snb.Time) || !sna.Tree.Equal(*snb.Tree) || sna.Hostname != snb.Hostname ||
sna.Username != snb.Username || sna.UID != snb.UID || sna.GID != snb.GID ||
len(sna.Paths) != len(snb.Paths) || len(sna.Excludes) != len(snb.Excludes) ||
len(sna.Tags) != len(snb.Tags) {
return false
}
if !sna.HasPaths(snb.Paths) || !sna.HasTags(snb.Tags) {
return false
}
for i, a := range sna.Excludes {
if a != snb.Excludes[i] {
return false
}
}
return true
}
func copyTree(ctx context.Context, srcRepo, dstRepo restic.Repository, treeID restic.ID, visitedTrees restic.IDSet) error {
// We have already processed this tree
if visitedTrees.Has(treeID) {