Merge pull request #2840 from aawsome/delete-parallel

Make delete parallel

changelog/unreleased/pull-2840

@@ -0,0 +1,7 @@
+Enhancement: Speed-up file deletion in forget, prune and rebuild-index
+
+We've sped up the file deletion for the commands forget, prune and
+rebuild-index, especially for remote repositories.
+Deletion was sequential before and is now run in parallel.
+
+https://github.com/restic/restic/pull/2840

cmd/restic/cmd_forget.go

@@ -94,34 +94,22 @@ func runForget(opts ForgetOptions, gopts GlobalOptions, args []string) error {
 		return err
 	}
 
-	removeSnapshots := 0
-
 	ctx, cancel := context.WithCancel(gopts.ctx)
 	defer cancel()
 
 	var snapshots restic.Snapshots
+	removeSnIDs := restic.NewIDSet()
 
 	for sn := range FindFilteredSnapshots(ctx, repo, opts.Hosts, opts.Tags, opts.Paths, args) {
 		snapshots = append(snapshots, sn)
 	}
 
+	var jsonGroups []*ForgetGroup
+
 	if len(args) > 0 {
 		// When explicit snapshots args are given, remove them immediately.
 		for _, sn := range snapshots {
-			if !opts.DryRun {
-				h := restic.Handle{Type: restic.SnapshotFile, Name: sn.ID().String()}
-				if err = repo.Backend().Remove(gopts.ctx, h); err != nil {
-					return err
-				}
-				if !gopts.JSON {
-					Verbosef("removed snapshot %v\n", sn.ID().Str())
-				}
-				removeSnapshots++
-			} else {
-				if !gopts.JSON {
-					Verbosef("would have removed snapshot %v\n", sn.ID().Str())
-				}
-			}
+			removeSnIDs.Insert(*sn.ID())
 		}
 	} else {
 		snapshotGroups, _, err := restic.GroupSnapshots(snapshots, opts.GroupBy)
@@ -151,8 +139,6 @@ func runForget(opts ForgetOptions, gopts GlobalOptions, args []string) error {
 				Verbosef("Applying Policy: %v\n", policy)
 			}
 
-			var jsonGroups []*ForgetGroup
-
 			for k, snapshotGroup := range snapshotGroups {
 				if gopts.Verbose >= 1 && !gopts.JSON {
 					err = PrintSnapshotGroupHeader(gopts.stdout, k)
@@ -191,36 +177,36 @@ func runForget(opts ForgetOptions, gopts GlobalOptions, args []string) error {
 
 				jsonGroups = append(jsonGroups, &fg)
 
-				removeSnapshots += len(remove)
-
-				if !opts.DryRun {
 				for _, sn := range remove {
-						h := restic.Handle{Type: restic.SnapshotFile, Name: sn.ID().String()}
-						err = repo.Backend().Remove(gopts.ctx, h)
+					removeSnIDs.Insert(*sn.ID())
+				}
+			}
+		}
+	}
+
+	if len(removeSnIDs) > 0 {
+		if !opts.DryRun {
+			err := DeleteFilesChecked(gopts, repo, removeSnIDs, restic.SnapshotFile)
 			if err != nil {
 				return err
 			}
+		} else {
+			if !gopts.JSON {
+				Printf("Would have removed the following snapshots:\n%v\n\n", removeSnIDs)
 			}
 		}
 	}
 
-			if gopts.JSON {
+	if gopts.JSON && len(jsonGroups) > 0 {
 		err = printJSONForget(gopts.stdout, jsonGroups)
 		if err != nil {
 			return err
 		}
 	}
-		}
-	}
 
-	if removeSnapshots > 0 && opts.Prune {
-		if !gopts.JSON {
-			Verbosef("%d snapshots have been removed, running prune\n", removeSnapshots)
-		}
-		if !opts.DryRun {
+	if len(removeSnIDs) > 0 && opts.Prune && !opts.DryRun {
 		return pruneRepository(gopts, repo)
 	}
-	}
 
 	return nil
 }

cmd/restic/cmd_prune.go

@@ -296,17 +296,8 @@ func pruneRepository(gopts GlobalOptions, repo restic.Repository) error {
 	}
 
 	if len(removePacks) != 0 {
-		bar = newProgressMax(!gopts.Quiet, uint64(len(removePacks)), "packs deleted")
-		bar.Start()
-		for packID := range removePacks {
-			h := restic.Handle{Type: restic.DataFile, Name: packID.String()}
-			err = repo.Backend().Remove(ctx, h)
-			if err != nil {
-				Warnf("unable to remove file %v from the repository\n", packID.Str())
-			}
-			bar.Report(restic.Stat{Blobs: 1})
-		}
-		bar.Done()
+		Verbosef("remove %d old packs\n", len(removePacks))
+		DeleteFiles(gopts, repo, removePacks, restic.DataFile)
 	}
 
 	Verbosef("done\n")

cmd/restic/cmd_rebuild_index.go

@@ -92,15 +92,7 @@ func rebuildIndex(ctx context.Context, repo restic.Repository, ignorePacks resti
 	Verbosef("saved new indexes as %v\n", ids)
 
 	Verbosef("remove %d old index files\n", len(supersedes))
-
-	for _, id := range supersedes {
-		if err := repo.Backend().Remove(ctx, restic.Handle{
-			Type: restic.IndexFile,
-			Name: id.String(),
-		}); err != nil {
-			Warnf("error removing old index %v: %v\n", id.Str(), err)
-		}
-	}
+	DeleteFiles(globalOptions, repo, restic.NewIDSet(supersedes...), restic.IndexFile)
 
 	return nil
 }

cmd/restic/delete.go

@@ -0,0 +1,62 @@
+package main
+
+import (
+	"golang.org/x/sync/errgroup"
+
+	"github.com/restic/restic/internal/restic"
+)
+
+// DeleteFiles deletes the given fileList of fileType in parallel
+// it will print a warning if there is an error, but continue deleting the remaining files
+func DeleteFiles(gopts GlobalOptions, repo restic.Repository, fileList restic.IDSet, fileType restic.FileType) {
+	deleteFiles(gopts, true, repo, fileList, fileType)
+}
+
+// DeleteFiles deletes the given fileList of fileType in parallel
+// if an error occurs, it will cancel and return this error
+func DeleteFilesChecked(gopts GlobalOptions, repo restic.Repository, fileList restic.IDSet, fileType restic.FileType) error {
+	return deleteFiles(gopts, false, repo, fileList, fileType)
+}
+
+const numDeleteWorkers = 8
+
+// deleteFiles deletes the given fileList of fileType in parallel
+// if ignoreError=true, it will print a warning if there was an error, else it will abort.
+func deleteFiles(gopts GlobalOptions, ignoreError bool, repo restic.Repository, fileList restic.IDSet, fileType restic.FileType) error {
+	totalCount := len(fileList)
+	fileChan := make(chan restic.ID)
+	go func() {
+		for id := range fileList {
+			fileChan <- id
+		}
+		close(fileChan)
+	}()
+
+	bar := newProgressMax(!gopts.JSON && !gopts.Quiet, uint64(totalCount), "files deleted")
+	wg, ctx := errgroup.WithContext(gopts.ctx)
+	bar.Start()
+	for i := 0; i < numDeleteWorkers; i++ {
+		wg.Go(func() error {
+			for id := range fileChan {
+				h := restic.Handle{Type: fileType, Name: id.String()}
+				err := repo.Backend().Remove(ctx, h)
+				if err != nil {
+					if !gopts.JSON {
+						Warnf("unable to remove %v from the repository\n", h)
+					}
+					if !ignoreError {
+						return err
+					}
+				}
+				if !gopts.JSON && gopts.verbosity >= 2 {
+					Verbosef("removed %v\n", h)
+				}
+				bar.Report(restic.Stat{Blobs: 1})
+			}
+			return nil
+		})
+	}
+	err := wg.Wait()
+	bar.Done()
+	return err
+}