Record each snapshot's new chunk size when its backup runs (closes #311)

snapshot list worked out NEW CHUNK SIZE from the snapshot's file rows. A
file's row is shared by every snapshot that lists it and rewritten when
the file changes, so a snapshot whose change was a modified file showed
0 B, and older snapshots' figures moved after later backups.

The scanner now totals the size of the chunks it stores that were not
stored before (the chunks chunk_count counts), the backup writes that
total to a new snapshots column, new_chunk_size, and snapshot list reads
it.

Judgement call: the figure is fixed when the backup runs, so removing an
earlier snapshot no longer raises a later snapshot's figure.

Model: opus-5-5

Dockerfile

@@ -5,16 +5,7 @@
 FROM golangci/golangci-lint:v2.14.0@sha256:ad862ba6b3798cbe0fd9fd7408d498fd74fbd2623a92406b2fd3898faf0bf98f AS lint
 WORKDIR /src
 COPY go.mod go.sum ./
-# Without the time limit a stalled connection to the module proxy holds
-# this step, and every build on the host sharing it, until the kernel
-# drops the connection, which can take an hour. The download normally
-# takes under half a minute.
-RUN for attempt in 1 2 3; do \
-        timeout 180 go mod download && exit 0; \
-        echo "go mod download attempt $attempt failed or ran over 180s" >&2; \
-    done; \
-    echo "module download failed: giving up after 3 attempts" >&2; \
-    exit 1
+RUN go mod download
 COPY . .
 # `golangci-lint run` silently ignores an unknown top-level key in
 # .golangci.yml, such as a misspelt `linters:`; `config verify` fails on it.
@@ -27,13 +18,7 @@ RUN golangci-lint run --config .golangci.yml ./...
 FROM golang:1.26.1@sha256:cd78d88e00afadbedd272f977d375a6247455f3a4b1178f8ae8bbcb201743a8a AS test
 WORKDIR /src
 COPY go.mod go.sum ./
-# Limited and retried as in the lint phase above.
-RUN for attempt in 1 2 3; do \
-        timeout 180 go mod download && exit 0; \
-        echo "go mod download attempt $attempt failed or ran over 180s" >&2; \
-    done; \
-    echo "module download failed: giving up after 3 attempts" >&2; \
-    exit 1
+RUN go mod download
 COPY . .
 RUN go test -timeout 90s -race -cover ./... || \
     { echo "--- Rerunning with -v for details ---"; \
@@ -51,13 +36,7 @@ RUN apk add --no-cache git
 RUN git config --system --add safe.directory /src
 WORKDIR /src
 COPY go.mod go.sum ./
-# Limited and retried as in the lint phase above.
-RUN for attempt in 1 2 3; do \
-        timeout 180 go mod download && exit 0; \
-        echo "go mod download attempt $attempt failed or ran over 180s" >&2; \
-    done; \
-    echo "module download failed: giving up after 3 attempts" >&2; \
-    exit 1
+RUN go mod download
 COPY . .
 
 # The VERSION build arg when one is given, otherwise

README.md

@@ -293,8 +293,8 @@ needed.
 **`snapshot list`**: Show every snapshot known to this host — the union
 of the local index and the backup destination store — with timestamps
 and three sizes per snapshot (compressed remote size; total
-uncompressed chunk size; size of chunks newly referenced by that
-snapshot).
+uncompressed chunk size; size of the chunks that snapshot stored that
+were not stored before, recorded when its backup ran).
 
 Listing the destination store does **not** require the age secret key,
 so it works in vaultik's intended configuration, where the backed-up
@@ -307,8 +307,8 @@ only the hash, so hostname and snapshot name exist solely in the local
 index and in the encrypted per-snapshot database. Snapshots found only
 on the destination store are therefore listed as
 `<remote only:<abbreviated remote key>>` and show `<remote only>` in
-the uncompressed and "new chunk" columns, which can only be computed
-from the local index. Their timestamp and compressed size are real,
+the uncompressed and "new chunk" columns, which come only from the
+local index. Their timestamp and compressed size are real,
 read from the manifest.
 
 Snapshots in the local index with no counterpart on the destination

cmd/vaultik/dockermoddownload_test.go

@@ -1,45 +0,0 @@
-package main_test
-
-import (
-	"strings"
-	"testing"
-
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-)
-
-// TestDockerfileBoundsEveryModuleDownload fails unless every
-// `go mod download` in the Dockerfile runs under a time limit, is tried
-// a fixed number of times, and then fails the build with a message that
-// names the module download (issue #351). Like the version tests, this
-// parses the Dockerfile; that a stalled download really is cut off and
-// retried was checked by hand.
-func TestDockerfileBoundsEveryModuleDownload(t *testing.T) {
-	t.Parallel()
-
-	var downloads []string
-
-	for _, instruction := range instructions(t, productDockerfile) {
-		if strings.Contains(instruction, "go mod download") {
-			downloads = append(downloads, instruction)
-		}
-	}
-
-	require.NotEmpty(t, downloads, "%s must download modules",
-		productDockerfile)
-
-	for _, download := range downloads {
-		assert.Contains(t, download, "timeout 180 go mod download",
-			"%s: a module download must have a time limit: %s",
-			productDockerfile, download)
-		assert.Contains(t, download, "for attempt in 1 2 3",
-			"%s: a module download must be retried: %s",
-			productDockerfile, download)
-		assert.Contains(t, download, "module download failed",
-			"%s: a module download that never succeeds must say so: %s",
-			productDockerfile, download)
-		assert.True(t, strings.HasSuffix(download, "exit 1"),
-			"%s: a module download that never succeeds must fail the"+
-				" build: %s", productDockerfile, download)
-	}
-}

docs/DATAMODEL.md

@@ -119,6 +119,7 @@ Tracks backup snapshots.
 - `completed_at` (INTEGER) - Completion timestamp (NULL if in progress)
 - `file_count` (INTEGER) - Number of files in snapshot
 - `chunk_count` (INTEGER) - Number of chunks this snapshot stored that were not stored before
+- `new_chunk_size` (INTEGER) - Total size of those chunks before compression; `snapshot list` shows it as NEW CHUNK SIZE
 - `blob_count` (INTEGER) - Number of blobs this snapshot created
 - `total_size` (INTEGER) - Total size of all files
 - `blob_size` (INTEGER) - Total compressed size of all referenced blobs

internal/cli/config.go

@@ -251,12 +251,6 @@ func NewConfigCommand() *cobra.Command {
 		Use:   "config",
 		Short: "Manage the configuration file",
 		Long:  "Commands for creating, editing, and querying the vaultik config file.",
-		// cobra checks Args only on a command that has a Run: without
-		// one, a mistyped subcommand printed help and exited 0.
-		Args: cobra.NoArgs,
-		Run: func(cmd *cobra.Command, _ []string) {
-			_ = cmd.Help()
-		},
 	}
 
 	cmd.AddCommand(newConfigInitCommand())

internal/cli/database.go

@@ -15,12 +15,6 @@ func NewDatabaseCommand() *cobra.Command {
 		Use:   "database",
 		Short: "Manage the local state database",
 		Long:  `Commands for managing the local SQLite state database.`,
-		// cobra checks Args only on a command that has a Run: without
-		// one, a mistyped subcommand printed help and exited 0.
-		Args: cobra.NoArgs,
-		Run: func(cmd *cobra.Command, _ []string) {
-			_ = cmd.Help()
-		},
 	}
 
 	cmd.AddCommand(

internal/cli/entry_unknown_subcommand_test.go

@@ -1,43 +0,0 @@
-package cli //nolint:testpackage // shares runEntry and the command-word constants
-
-import (
-	"testing"
-
-	"github.com/stretchr/testify/assert"
-)
-
-// TestEntryGroupRejectsUnknownSubcommand runs each group command with a
-// mistyped subcommand, as a crontab line might carry one. It must fail
-// with exit 1 and name the word, as `vaultik bogus` does at the top
-// level, instead of printing the group's help and exiting 0 having done
-// nothing. The group name alone still prints its help.
-//
-//nolint:paralleltest // replaces os.Args, os.Stdout and os.Stderr
-func TestEntryGroupRejectsUnknownSubcommand(t *testing.T) {
-	for _, testCase := range []struct {
-		group    string
-		mistyped string
-	}{
-		{group: cmdSnapshot, mistyped: "craete"},
-		{group: "config", mistyped: "inti"},
-		{group: cmdRemote, mistyped: "ifno"},
-		{group: "database", mistyped: "delte"},
-		{group: "completion", mistyped: "nosuchshell"},
-	} {
-		t.Run(testCase.group, func(t *testing.T) {
-			code, stdout, stderr := runEntry(t,
-				testCase.group, testCase.mistyped)
-
-			assert.Equal(t, 1, code)
-			assert.Empty(t, stdout)
-			assert.Contains(t, stderr,
-				`unknown command "`+testCase.mistyped+`"`)
-
-			code, stdout, _ = runEntry(t, testCase.group)
-
-			assert.Equal(t, 0, code)
-			assert.Contains(t, stdout,
-				programName+" "+testCase.group+" [command]")
-		})
-	}
-}

internal/cli/remote.go

@@ -18,12 +18,6 @@ func NewRemoteCommand() *cobra.Command {
 		Use:   "remote",
 		Short: "Remote storage management commands",
 		Long:  "Commands for inspecting and managing remote storage",
-		// cobra checks Args only on a command that has a Run: without
-		// one, a mistyped subcommand printed help and exited 0.
-		Args: cobra.NoArgs,
-		Run: func(cmd *cobra.Command, _ []string) {
-			_ = cmd.Help()
-		},
 	}
 
 	// Add subcommands

internal/cli/root.go

@@ -74,21 +74,6 @@ on the source system.`,
 		NewDatabaseCommand(),
 	)
 
-	// cobra adds the completion command only when Execute runs, and with
-	// no Run, so it skipped its own cobra.NoArgs and a mistyped shell name
-	// printed help and exited 0. Adding it here lets it have a Run. Its
-	// scripts go to os.Stdout as it is now: a later SetOut does not
-	// redirect them.
-	cmd.InitDefaultCompletionCmd()
-
-	for _, sub := range cmd.Commands() {
-		if sub.Name() == "completion" {
-			sub.Run = func(completion *cobra.Command, _ []string) {
-				_ = completion.Help()
-			}
-		}
-	}
-
 	return cmd
 }
 

internal/cli/snapshot.go

@@ -41,12 +41,6 @@ func NewSnapshotCommand() *cobra.Command {
 		Use:   "snapshot",
 		Short: "Snapshot management commands",
 		Long:  "Commands for creating, listing, and managing snapshots",
-		// cobra checks Args only on a command that has a Run: without
-		// one, a mistyped subcommand printed help and exited 0.
-		Args: cobra.NoArgs,
-		Run: func(cmd *cobra.Command, _ []string) {
-			_ = cmd.Help()
-		},
 	}
 
 	// Add subcommands

internal/database/schema/001.sql

@@ -86,6 +86,7 @@ CREATE TABLE IF NOT EXISTS snapshots (
     completed_at INTEGER,
     file_count INTEGER NOT NULL DEFAULT 0,
     chunk_count INTEGER NOT NULL DEFAULT 0,
+    new_chunk_size INTEGER NOT NULL DEFAULT 0,
     blob_count INTEGER NOT NULL DEFAULT 0,
     total_size INTEGER NOT NULL DEFAULT 0,
     blob_size INTEGER NOT NULL DEFAULT 0,

internal/database/snapshots.go

@@ -129,6 +129,7 @@ func (r *SnapshotRepository) UpdateExtendedStats(
 	compressionLevel int,
 	uploadBytes int64,
 	uploadDurationMs int64,
+	newChunkSize int64,
 ) error {
 	compressionRatio, err := r.extendedCompressionRatio(
 		ctx, tx, snapshotID, blobUncompressedSize,
@@ -143,18 +144,19 @@ func (r *SnapshotRepository) UpdateExtendedStats(
 		    compression_ratio = ?,
 		    compression_level = ?,
 		    upload_bytes = ?,
-		    upload_duration_ms = ?
+		    upload_duration_ms = ?,
+		    new_chunk_size = ?
 		WHERE id = ?
 	`
 
 	if tx != nil {
 		_, err = tx.ExecContext(ctx, query,
 			blobUncompressedSize, compressionRatio, compressionLevel,
-			uploadBytes, uploadDurationMs, snapshotID)
+			uploadBytes, uploadDurationMs, newChunkSize, snapshotID)
 	} else {
 		_, err = r.db.ExecWithLog(ctx, query,
 			blobUncompressedSize, compressionRatio, compressionLevel,
-			uploadBytes, uploadDurationMs, snapshotID)
+			uploadBytes, uploadDurationMs, newChunkSize, snapshotID)
 	}
 
 	if err != nil {
@@ -594,45 +596,24 @@ func (r *SnapshotRepository) GetSnapshotUncompressedChunkSize(
 	return totalSize, nil
 }
 
-// GetSnapshotNewChunkSize returns the sum of plaintext sizes of chunks that are
-// referenced by this snapshot but not by any earlier completed snapshot known to
-// the local database. The result is the marginal uncompressed data this snapshot
-// added to the dedup pool — i.e., the delta from prior snapshots.
+// GetSnapshotNewChunkSize returns the total plaintext size of the chunks the
+// snapshot's backup stored that were not stored before, as the backup
+// recorded it. It is not derived from the snapshot's files: a file's row is
+// shared by every snapshot that lists it and is rewritten when the file
+// changes, so it shows only the file's latest chunks.
 func (r *SnapshotRepository) GetSnapshotNewChunkSize(
 	ctx context.Context, snapshotID string,
 ) (int64, error) {
-	query := `
-		WITH this_snap_chunks AS (
-			SELECT DISTINCT fc.chunk_hash
-			FROM snapshot_files sf
-			JOIN file_chunks fc ON sf.file_id = fc.file_id
-			WHERE sf.snapshot_id = ?
-		),
-		prior_chunks AS (
-			SELECT DISTINCT fc.chunk_hash
-			FROM snapshots s
-			JOIN snapshot_files sf ON sf.snapshot_id = s.id
-			JOIN file_chunks fc ON fc.file_id = sf.file_id
-			WHERE s.completed_at IS NOT NULL
-			  AND s.id != ?
-			  AND s.started_at < (SELECT started_at FROM snapshots WHERE id = ?)
-		)
-		SELECT COALESCE(SUM(c.size), 0)
-		FROM chunks c
-		JOIN this_snap_chunks t ON c.chunk_hash = t.chunk_hash
-		WHERE c.chunk_hash NOT IN (SELECT chunk_hash FROM prior_chunks)
-	`
+	query := `SELECT new_chunk_size FROM snapshots WHERE id = ?`
 
-	var totalSize int64
+	var newChunkSize int64
 
-	err := r.db.conn.QueryRowContext(
-		ctx, query, snapshotID, snapshotID, snapshotID,
-	).Scan(&totalSize)
+	err := r.db.conn.QueryRowContext(ctx, query, snapshotID).Scan(&newChunkSize)
 	if err != nil {
 		return 0, fmt.Errorf("querying new chunk size: %w", err)
 	}
 
-	return totalSize, nil
+	return newChunkSize, nil
 }
 
 // GetIncompleteSnapshots returns all snapshots that haven't been completed

internal/snapshot/scanner.go

@@ -135,7 +135,9 @@ type ScannerConfig struct {
 // are counted per file: BytesScanned is the size of the new and changed
 // files, BytesSkipped that of the unchanged ones. FilesFailed counts the
 // new and changed files that phase 2 could not store; FilesScanned
-// includes them and BytesScanned does not.
+// includes them and BytesScanned does not. ChunksCreated counts the
+// chunks that were not already stored, and NewChunkSize is their total
+// size.
 type ScanResult struct {
 	FilesScanned   int
 	FilesSkipped   int
@@ -145,6 +147,7 @@ type ScanResult struct {
 	BytesSkipped   int64
 	BytesDeleted   int64
 	ChunksCreated  int
+	NewChunkSize   int64
 	BlobsCreated   int
 	BlobsUploaded  int
 	BytesUploaded  int64
@@ -1866,11 +1869,12 @@ func (s *Scanner) processFileStreaming(
 	return nil
 }
 
-// updateChunkStats counts a chunk that was not already stored. The scan
-// result's file counts, BytesScanned and BytesSkipped are not touched
-// here: the scan phase counts each file once.
+// updateChunkStats counts a chunk that was not already stored, and its
+// size. The scan result's file counts, BytesScanned and BytesSkipped are
+// not touched here: the scan phase counts each file once.
 func (s *Scanner) updateChunkStats(chunkSize int64, result *ScanResult) {
 	result.ChunksCreated++
+	result.NewChunkSize += chunkSize
 
 	if s.progress != nil {
 		s.progress.GetStats().ChunksCreated.Add(1)

internal/snapshot/snapshot.go

@@ -199,6 +199,7 @@ func (sm *SnapshotManager) UpdateSnapshotStatsExtended(
 			stats.CompressionLevel,
 			stats.BytesUploaded,
 			stats.UploadDurationMs,
+			stats.NewChunkSize,
 		)
 	})
 }
@@ -906,6 +907,7 @@ type ExtendedBackupStats struct {
 	BlobUncompressedSize int64 // Total uncompressed size of all referenced blobs
 	CompressionLevel     int   // Compression level used for this snapshot
 	UploadDurationMs     int64 // Total milliseconds spent uploading to S3
+	NewChunkSize         int64 // Total size of the chunks counted in ChunksCreated
 }
 
 // deleteOtherSnapshots deletes all snapshots except the current one

internal/vaultik/new_chunk_size_test.go

@@ -0,0 +1,133 @@
+package vaultik_test
+
+import (
+	"bytes"
+	"context"
+	"maps"
+	"path/filepath"
+	"testing"
+
+	"github.com/spf13/afero"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/chunker"
+	"sneak.berlin/go/vaultik/internal/database"
+	"sneak.berlin/go/vaultik/internal/log"
+	"sneak.berlin/go/vaultik/internal/storage"
+	"sneak.berlin/go/vaultik/internal/vaultik"
+)
+
+// TestNewChunkSizeOfChangedFileStaysFixed covers
+// https://git.eeqj.de/sneak/vaultik/issues/311. A backup whose only change
+// is a modified file lists the size of the chunks that change added as its
+// NEW CHUNK SIZE, and a later backup that changes the file again leaves
+// every earlier snapshot's figure as it was. The file's row in the local
+// index is shared by all three snapshots and rewritten by each backup.
+func TestNewChunkSizeOfChangedFileStaysFixed(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	fs := afero.NewOsFs()
+	tempDir := t.TempDir()
+	dataDir := filepath.Join(tempDir, "src")
+	dbPath := filepath.Join(tempDir, "index.sqlite")
+	changedPath := filepath.Join(dataDir, "changed.bin")
+
+	ctx := context.Background()
+	files := writeFaultSourceTree(t, fs, dataDir)
+	cfg := changedFileConfig(dataDir, dbPath)
+
+	appendRandomBytes(t, fs, files, changedPath, appendedFileSize)
+
+	store, err := storage.NewFileStorer(filepath.Join(tempDir, "remote"))
+	require.NoError(t, err)
+
+	db, err := database.New(ctx, dbPath)
+	require.NoError(t, err)
+	t.Cleanup(func() { _ = db.Close() })
+
+	repos := database.NewRepositories(db)
+	v := newBackupVaultik(ctx, cfg, store, repos, db, fs)
+
+	require.NoError(t, backUp(v, "first"))
+
+	firstFiles := maps.Clone(files)
+	firstID := localSnapshotID(ctx, t, repos, "first")
+
+	appendRandomBytes(t, fs, files, changedPath, faultChunkSize)
+	require.NoError(t, backUp(v, "second"))
+
+	secondID := localSnapshotID(ctx, t, repos, "second")
+	secondAdded := sizeOfNewChunks(t, files, firstFiles)
+	require.Positive(t, secondAdded)
+	assert.Equal(t, secondAdded, listedNewChunkSizes(t, v)[secondID],
+		"the second snapshot must count the chunks the change added")
+
+	appendRandomBytes(t, fs, files, changedPath, faultChunkSize)
+	require.NoError(t, backUp(v, "third"))
+
+	sizes := listedNewChunkSizes(t, v)
+	assert.Equal(t, sizeOfNewChunks(t, firstFiles, nil), sizes[firstID],
+		"a later backup must not change the first snapshot's figure")
+	assert.Equal(t, secondAdded, sizes[secondID],
+		"a later backup must not change the second snapshot's figure")
+}
+
+// sizeOfNewChunks returns the total size of the distinct chunks of the
+// files in after that no file in before has, cut the way the backup cuts
+// them.
+func sizeOfNewChunks(t *testing.T, after, before map[string][]byte) int64 {
+	t.Helper()
+
+	known := make(map[string]bool)
+	for _, chunk := range chunksOf(t, before) {
+		known[chunk.Hash] = true
+	}
+
+	var total int64
+
+	for _, chunk := range chunksOf(t, after) {
+		if !known[chunk.Hash] {
+			known[chunk.Hash] = true
+			total += chunk.Size
+		}
+	}
+
+	return total
+}
+
+// chunksOf returns the chunks of every file in files.
+func chunksOf(t *testing.T, files map[string][]byte) []chunker.Chunk {
+	t.Helper()
+
+	c := chunker.NewChunker(faultChunkSize)
+
+	var all []chunker.Chunk
+
+	for _, content := range files {
+		chunks, err := c.ChunkReader(bytes.NewReader(content))
+		require.NoError(t, err)
+
+		all = append(all, chunks...)
+	}
+
+	return all
+}
+
+// listedNewChunkSizes runs `snapshot list --json` and returns each listed
+// snapshot's new_chunk_size by snapshot ID.
+func listedNewChunkSizes(t *testing.T, v *vaultik.Vaultik) map[string]int64 {
+	t.Helper()
+
+	var out bytes.Buffer
+
+	v.Stdout = &out
+	require.NoError(t, v.ListSnapshots(true))
+
+	sizes := make(map[string]int64)
+	for _, row := range decodeListJSON(t, out.String()) {
+		sizes[row.ID] = row.NewChunkSize
+	}
+
+	return sizes
+}

internal/vaultik/snapshot.go

@@ -209,6 +209,7 @@ type snapshotStats struct {
 	totalFiles         int
 	totalBytes         int64
 	totalChunks        int
+	newChunkSize       int64
 	totalBlobs         int
 	totalBytesSkipped  int64
 	totalFilesSkipped  int
@@ -341,6 +342,7 @@ func (v *Vaultik) scanAllDirectories(
 		stats.totalFiles += result.FilesScanned
 		stats.totalBytes += result.BytesScanned
 		stats.totalChunks += result.ChunksCreated
+		stats.newChunkSize += result.NewChunkSize
 		stats.totalBlobs += result.BlobsCreated
 		stats.totalFilesSkipped += result.FilesSkipped
 		stats.totalFilesFailed += result.FilesFailed
@@ -403,6 +405,7 @@ func (v *Vaultik) finalizeSnapshotMetadata(
 		BlobUncompressedSize: stats.blobUncompressedSize,
 		CompressionLevel:     v.Config.CompressionLevel,
 		UploadDurationMs:     stats.uploadDuration.Milliseconds(),
+		NewChunkSize:         stats.newChunkSize,
 	}
 
 	err = v.SnapshotManager.UpdateSnapshotStatsExtended(v.ctx, snapshotID, extStats)

internal/vaultik/snapshot_list_test.go

@@ -445,6 +445,7 @@ type listJSONRow struct {
 	RemoteKey      string `json:"remote_key"`
 	Timestamp      string `json:"timestamp"`
 	CompressedSize int64  `json:"compressed_size"`
+	NewChunkSize   int64  `json:"new_chunk_size"`
 	LocallyTracked bool   `json:"locally_tracked"`
 	RemotePresent  *bool  `json:"remote_present"`
 }