stats: Initial implementation of stats command

changelog/unreleased/pull-1729

@@ -0,0 +1,4 @@
+Enhancement: Add stats command to get information about a repository
+
+https://github.com/restic/restic/issues/874
+https://github.com/restic/restic/pull/1729

cmd/restic/cmd_stats.go

@@ -0,0 +1,121 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"os"
+
+	"github.com/restic/restic/internal/restic"
+	"github.com/spf13/cobra"
+)
+
+var cmdStats = &cobra.Command{
+	Use:   "stats",
+	Short: "Scan the repository and show basic statistics",
+	Long: `
+The "stats" command walks all snapshots in a repository and accumulates
+statistics about the data stored therein. It reports on the number of
+unique files and their sizes.
+`,
+	DisableAutoGenTag: true,
+	RunE: func(cmd *cobra.Command, args []string) error {
+		return runStats(globalOptions, args)
+	},
+}
+
+func init() {
+	cmdRoot.AddCommand(cmdStats)
+}
+
+func runStats(gopts GlobalOptions, args []string) error {
+	ctx, cancel := context.WithCancel(gopts.ctx)
+	defer cancel()
+
+	repo, err := OpenRepository(gopts)
+	if err != nil {
+		return err
+	}
+
+	if err = repo.LoadIndex(ctx); err != nil {
+		return err
+	}
+
+	if !gopts.NoLock {
+		lock, err := lockRepo(repo)
+		defer unlockRepo(lock)
+		if err != nil {
+			return err
+		}
+	}
+
+	// create a container for the stats, and other state
+	// needed while walking the trees
+	stats := &statsContainer{idSet: restic.NewIDSet()}
+
+	// iterate every snapshot in the repo
+	err = repo.List(ctx, restic.SnapshotFile, func(snapshotID restic.ID, size int64) error {
+		snapshot, err := restic.LoadSnapshot(ctx, repo, snapshotID)
+		if err != nil {
+			return fmt.Errorf("Error loading snapshot %s: %v", snapshotID.Str(), err)
+		}
+		if snapshot.Tree == nil {
+			return fmt.Errorf("snapshot %s has nil tree", snapshot.ID().Str())
+		}
+
+		err = walkTree(ctx, repo, *snapshot.Tree, stats)
+		if err != nil {
+			return fmt.Errorf("walking tree %s: %v", *snapshot.Tree, err)
+		}
+
+		return nil
+	})
+
+	if gopts.JSON {
+		err = json.NewEncoder(os.Stdout).Encode(stats)
+		if err != nil {
+			return fmt.Errorf("encoding output: %v", err)
+		}
+		return nil
+	}
+
+	Printf("   Cumulative Original Size:   %-5s\n", formatBytes(stats.TotalOriginalSize))
+	Printf("  Total Original File Count:   %d\n", stats.TotalCount)
+	return nil
+}
+
+func walkTree(ctx context.Context, repo restic.Repository, treeID restic.ID, stats *statsContainer) error {
+	if stats.idSet.Has(treeID) {
+		return nil
+	}
+	stats.idSet.Insert(treeID)
+
+	tree, err := repo.LoadTree(ctx, treeID)
+	if err != nil {
+		return fmt.Errorf("loading tree: %v", err)
+	}
+
+	for _, node := range tree.Nodes {
+		// update our stats to account for this node
+		stats.TotalOriginalSize += node.Size
+		stats.TotalCount++
+
+		if node.Subtree != nil {
+			err = walkTree(ctx, repo, *node.Subtree, stats)
+			if err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
+}
+
+// statsContainer holds information during a walk of a repository
+// to collect information about it, as well as state needed
+// for a successful and efficient walk.
+type statsContainer struct {
+	TotalCount        uint64 `json:"total_count"`
+	TotalOriginalSize uint64 `json:"total_original_size"`
+	idSet             restic.IDSet
+}

doc/bash-completion.sh

@@ -1310,6 +1310,7 @@ _restic_root_command()
     commands+=("rebuild-index")
     commands+=("restore")
     commands+=("snapshots")
+    commands+=("stats")
     commands+=("tag")
     commands+=("unlock")
     commands+=("version")