Merge pull request 'next into main' (#110) from next into main

Reviewed-on: #110

cancel_test.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"context"
-	"crypto/sha256"
 	"database/sql"
 	"errors"
 	"fmt"
@@ -169,8 +168,8 @@ func assertRecordsIntact(t *testing.T, db *sql.DB, before []string) {
 
 // TestSyncScanCancelledMidWalkKeepsRecords is the regression net under
 // the post-walk guard. The scan is cancelled part-way through the
-// walk, so it reaches the guard having walked a genuinely partial tree
-// and holding a still-populated index of records the walk never got to.
+// walk, so it reaches the guard holding a genuinely partial size
+// census and a still-populated index of records the walk never got to.
 // Every one of those records would look vanished to the update phase.
 // The guard is what stops the scan there, and this test is what
 // notices if it stops doing so: deleting the guard, or making it
@@ -209,10 +208,10 @@ func TestSyncScanCancelledMidWalkKeepsRecords(t *testing.T) {
 }
 
 // assertWalkGuardAborted checks that the scan stopped at the post-walk
-// guard: with a walk that reached some files (it really ran) but not
-// all of them (it really was cut short), and with no record counted for
-// removal. A removal count means the partial walk was carried past
-// the guard into the update phase, which is the failure this test
+// guard: with a census that is neither empty (the walk really ran)
+// nor complete (it really was cut short), and with no record counted
+// for removal. A removal count means the partial census was carried
+// past the guard into the update phase, which is the failure this test
 // exists to catch.
 func assertWalkGuardAborted(t *testing.T, st scanStats, err error) {
 	t.Helper()
@@ -223,30 +222,30 @@ func assertWalkGuardAborted(t *testing.T, st scanStats, err error) {
 	}
 
 	if st.unchanged == 0 {
-		t.Fatalf("stats = %+v: the walk reached no file, so it never "+
+		t.Fatalf("stats = %+v: the census is empty, so the walk never "+
 			"ran and the guard was reached for the wrong reason", st)
 	}
 
 	if st.unchanged >= walkCancelFiles {
-		t.Fatalf("stats = %+v: the walk reached the whole tree, so it "+
-			"was not cut short", st)
+		t.Fatalf("stats = %+v: the census covers the whole tree, so the "+
+			"walk was not cut short", st)
 	}
 
 	// The workers drop every directory still queued once the scan is
 	// cancelled, so only the files in the directories already in flight
-	// can still be reached after the fact. A walk beyond that bound
+	// can add to the census after the fact. A census beyond that bound
 	// would mean the cancellation was not observed where it should have
 	// been.
 	limit := walkCancelAtDone + walkCancelInFlightFiles
 	if st.unchanged > limit {
-		t.Errorf("the walk reached %d files, want at most %d: it kept "+
+		t.Errorf("census covers %d files, want at most %d: the walk kept "+
 			"taking directories off the queue after cancellation",
 			st.unchanged, limit)
 	}
 
 	if st.removed != 0 {
 		t.Errorf("stats = %+v: the scan counted records for removal from "+
-			"a partial walk", st)
+			"a partial census", st)
 	}
 }
 
@@ -763,9 +762,7 @@ func TestHashWorkerDropsQueuedRuns(t *testing.T) {
 
 	var hashed atomic.Bool
 
-	hash := func(path string, size int64) (
-		[sha256.Size]byte, [sha256.Size]byte, [sha256.Size]byte, error,
-	) {
+	hash := func(path string, size int64) (string, string, string, error) {
 		hashed.Store(true)
 
 		return hashSignature(path, size)
@@ -805,9 +802,7 @@ func TestHashWorkerAbandonsBlockedSend(t *testing.T) {
 
 	// The scan is cancelled while the worker hashes, so the worker has
 	// already passed the check that drops queued runs.
-	hash := func(path string, size int64) (
-		[sha256.Size]byte, [sha256.Size]byte, [sha256.Size]byte, error,
-	) {
+	hash := func(path string, size int64) (string, string, string, error) {
 		cancel()
 
 		return hashSignature(path, size)

db.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"context"
-	"crypto/sha256"
 	"database/sql"
 	"errors"
 	"fmt"
@@ -47,20 +46,18 @@ const dbFilePerm = 0o644
 const lockFilePerm = 0o600
 
 // createTableSQL is the schema applied to a fresh database. Paths are
-// BLOBs because Unix paths are raw bytes, not guaranteed UTF-8.
-// disk_size holds the bytes the file takes on disk. mtime holds whole
-// Unix seconds and mtime_nsec the nanoseconds within that second. head,
-// tail and content each hold the raw 32 bytes of a SHA-256.
+// BLOBs because Unix paths are raw bytes, not guaranteed UTF-8. mtime
+// holds whole Unix seconds and mtime_nsec the nanoseconds within that
+// second.
 const createTableSQL = `
 CREATE TABLE files (
     path       BLOB PRIMARY KEY,
     size       INTEGER NOT NULL,
-    disk_size  INTEGER NOT NULL,
     mtime      INTEGER NOT NULL,
     mtime_nsec INTEGER NOT NULL,
-    head       BLOB NOT NULL,
-    tail       BLOB NOT NULL,
-    content    BLOB NOT NULL
+    head       TEXT NOT NULL,
+    tail       TEXT NOT NULL,
+    content    TEXT NOT NULL
 ) WITHOUT ROWID
 `
 
@@ -70,59 +67,14 @@ const createIndexSQL = `
 CREATE INDEX files_signature ON files (size, head, tail, content)
 `
 
-// createTotalsSQL creates the totals table, which holds one row: the
-// number of records and the sizes of all records added up. Counting
-// them over files would read every record. The three triggers below
-// keep the row current, in the transaction of each change to files.
-const createTotalsSQL = `
-CREATE TABLE totals (
-    records INTEGER NOT NULL,
-    size    INTEGER NOT NULL
-)
-`
-
-// insertTotalsSQL adds the one row of totals, for an empty files table.
-const insertTotalsSQL = `
-INSERT INTO totals (records, size) VALUES (0, 0)
-`
-
-// totalsAfterInsertSQL counts each inserted record into totals.
-const totalsAfterInsertSQL = `
-CREATE TRIGGER totals_after_insert AFTER INSERT ON files BEGIN
-    UPDATE totals SET records = records + 1, size = size + NEW.size;
-END
-`
-
-// totalsAfterDeleteSQL takes each deleted record out of totals.
-const totalsAfterDeleteSQL = `
-CREATE TRIGGER totals_after_delete AFTER DELETE ON files BEGIN
-    UPDATE totals SET records = records - 1, size = size - OLD.size;
-END
-`
-
-// totalsAfterUpdateSQL replaces a record's old size in totals with its
-// new one. scan's upsert of an existing record is such an update.
-const totalsAfterUpdateSQL = `
-CREATE TRIGGER totals_after_update AFTER UPDATE OF size ON files BEGIN
-    UPDATE totals SET size = size + NEW.size - OLD.size;
-END
-`
-
-// recordCountSQL reads the number of records from totals.
-const recordCountSQL = `
-SELECT records FROM totals
-`
-
 // upsertSQL inserts one file record, replacing any existing record for
 // the same path.
 const upsertSQL = `
-INSERT INTO files (
-    path, size, disk_size, mtime, mtime_nsec, head, tail, content
-)
-VALUES (?, ?, ?, ?, ?, ?, ?, ?)
+INSERT INTO files (path, size, mtime, mtime_nsec, head, tail, content)
+VALUES (?, ?, ?, ?, ?, ?, ?)
 ON CONFLICT (path) DO UPDATE SET
-    size = excluded.size, disk_size = excluded.disk_size,
-    mtime = excluded.mtime, mtime_nsec = excluded.mtime_nsec,
+    size = excluded.size, mtime = excluded.mtime,
+    mtime_nsec = excluded.mtime_nsec,
     head = excluded.head, tail = excluded.tail,
     content = excluded.content
 `
@@ -140,10 +92,6 @@ var errSchemaVersion = errors.New("unsupported database schema version")
 // database.
 var errScanRunning = errors.New("another scan is running")
 
-// errHashSize reports a record whose head, tail or content is not the
-// 32 bytes of a SHA-256.
-var errHashSize = errors.New("hash is not 32 bytes")
-
 // databasePath resolves the database location: SFDUPES_DATABASE when
 // set and non-empty, the compiled-in default otherwise. It returns the
 // path, with the working directory, its symlinks resolved, put in front
@@ -196,14 +144,9 @@ func createDatabaseDirectory(path string) error {
 // scanParams are the connection parameters for scan: read-write, with
 // WAL journaling and a busy timeout, so a report can run while a cron
 // scan is in progress. closeScanDatabase leaves WAL mode again.
-//
-// Each write to files fires a trigger, so SQLite keeps a statement
-// journal for it. temp_store(MEMORY) keeps that journal in memory,
-// which costs far less than a temporary file.
 const scanParams = "_pragma=busy_timeout(10000)" +
 	"&_pragma=journal_mode(WAL)" +
-	"&_pragma=synchronous(NORMAL)" +
-	"&_pragma=temp_store(MEMORY)"
+	"&_pragma=synchronous(NORMAL)"
 
 // reportParams are the connection parameters for report, trees and
 // info: read-only, with the same busy timeout. They set no journal
@@ -477,14 +420,14 @@ func createSchema(ctx context.Context, db *sql.DB) error {
 
 	defer func() { _ = tx.Rollback() }()
 
-	for _, stmt := range []string{
-		createTableSQL, createIndexSQL, createTotalsSQL, insertTotalsSQL,
-		totalsAfterInsertSQL, totalsAfterDeleteSQL, totalsAfterUpdateSQL,
-	} {
-		_, err = tx.ExecContext(ctx, stmt)
-		if err != nil {
-			return fmt.Errorf("create schema: %w", err)
-		}
+	_, err = tx.ExecContext(ctx, createTableSQL)
+	if err != nil {
+		return fmt.Errorf("create schema: %w", err)
+	}
+
+	_, err = tx.ExecContext(ctx, createIndexSQL)
+	if err != nil {
+		return fmt.Errorf("create schema: %w", err)
 	}
 
 	_, err = tx.ExecContext(ctx,
@@ -531,7 +474,7 @@ func loadFileRows(ctx context.Context, db *sql.DB, total func(n int64),
 
 	var n int64
 
-	err = tx.QueryRowContext(ctx, recordCountSQL).Scan(&n)
+	err = tx.QueryRowContext(ctx, "SELECT COUNT(*) FROM files").Scan(&n)
 	if err != nil {
 		return fmt.Errorf("count records: %w", err)
 	}
@@ -539,8 +482,8 @@ func loadFileRows(ctx context.Context, db *sql.DB, total func(n int64),
 	total(n)
 
 	rows, err := tx.QueryContext(ctx,
-		"SELECT path, size, disk_size, mtime, mtime_nsec, head, tail, "+
-			"content FROM files ORDER BY path")
+		"SELECT path, size, mtime, mtime_nsec, head, tail, content "+
+			"FROM files ORDER BY path")
 	if err != nil {
 		return fmt.Errorf("read records: %w", err)
 	}
@@ -549,25 +492,19 @@ func loadFileRows(ctx context.Context, db *sql.DB, total func(n int64),
 
 	for rows.Next() {
 		var (
-			path, head, tail, content []byte
-			sec, nsec                 int64
-			r                         scanRec
+			path      []byte
+			sec, nsec int64
+			r         scanRec
 		)
 
-		err = rows.Scan(&path, &r.size, &r.diskSize, &sec, &nsec,
-			&head, &tail, &content)
+		err = rows.Scan(&path, &r.size, &sec, &nsec, &r.head, &r.tail,
+			&r.content)
 		if err != nil {
 			return fmt.Errorf("read record: %w", err)
 		}
 
 		r.path = string(path)
 		r.mtime = time.Unix(sec, nsec)
-
-		err = r.setHashes(head, tail, content)
-		if err != nil {
-			return fmt.Errorf("read record %s: %w", escapePath(r.path), err)
-		}
-
 		fn(r)
 	}
 
@@ -590,11 +527,10 @@ ORDER BY size DESC, head DESC, tail DESC, content DESC
 `
 
 // loadSignatureRows gives total the number of records, then streams
-// every record's signature and path to fn, without its mtime or its
-// disk_size, in the order of signatureRowsSQL. The count and the
-// records are read in one transaction, so they agree while a scan is
-// committing. An error from fn stops the reading and is returned as it
-// is.
+// every record's signature and path to fn, without its mtime, in the
+// order of signatureRowsSQL. The count and the records are read in one
+// transaction, so they agree while a scan is committing. An error from
+// fn stops the reading and is returned as it is.
 func loadSignatureRows(ctx context.Context, db *sql.DB,
 	total func(n int64), fn func(r scanRec) error,
 ) error {
@@ -609,7 +545,7 @@ func loadSignatureRows(ctx context.Context, db *sql.DB,
 
 	var n int64
 
-	err = tx.QueryRowContext(ctx, recordCountSQL).Scan(&n)
+	err = tx.QueryRowContext(ctx, "SELECT COUNT(*) FROM files").Scan(&n)
 	if err != nil {
 		return fmt.Errorf("count records: %w", err)
 	}
@@ -625,22 +561,17 @@ func loadSignatureRows(ctx context.Context, db *sql.DB,
 
 	for rows.Next() {
 		var (
-			path, head, tail, content []byte
-			r                         scanRec
+			path []byte
+			r    scanRec
 		)
 
-		err = rows.Scan(&r.size, &head, &tail, &content, &path)
+		err = rows.Scan(&r.size, &r.head, &r.tail, &r.content, &path)
 		if err != nil {
 			return fmt.Errorf("read record: %w", err)
 		}
 
 		r.path = string(path)
 
-		err = r.setHashes(head, tail, content)
-		if err != nil {
-			return fmt.Errorf("read record %s: %w", escapePath(r.path), err)
-		}
-
 		err = fn(r)
 		if err != nil {
 			return err
@@ -655,27 +586,11 @@ func loadSignatureRows(ctx context.Context, db *sql.DB,
 	return nil
 }
 
-// setHashes sets r's head, tail and content to the values read from
-// those columns. Each must be the raw 32 bytes of a SHA-256.
-func (r *scanRec) setHashes(head, tail, content []byte) error {
-	for _, b := range [][]byte{head, tail, content} {
-		if len(b) != sha256.Size {
-			return fmt.Errorf("%w: found %d bytes", errHashSize, len(b))
-		}
-	}
-
-	r.head = [sha256.Size]byte(head)
-	r.tail = [sha256.Size]byte(tail)
-	r.content = [sha256.Size]byte(content)
-
-	return nil
-}
-
 // countRecords returns the number of records in the database.
 func countRecords(ctx context.Context, db *sql.DB) (int64, error) {
 	var n int64
 
-	err := db.QueryRowContext(ctx, recordCountSQL).Scan(&n)
+	err := db.QueryRowContext(ctx, "SELECT COUNT(*) FROM files").Scan(&n)
 	if err != nil {
 		return 0, fmt.Errorf("count records: %w", err)
 	}
@@ -683,10 +598,16 @@ func countRecords(ctx context.Context, db *sql.DB) (int64, error) {
 	return n, nil
 }
 
-// databaseCountsSQL reads the number of records and the sizes of all
-// records added up from totals.
+// databaseCountsSQL counts the records, those with head and tail
+// hashes and those with a content hash, and adds up their sizes, in one
+// pass over the table. A SUM over no rows is NULL, so on an empty table
+// each SUM falls back to 0.
 const databaseCountsSQL = `
-SELECT records, size FROM totals
+SELECT COUNT(*),
+       COALESCE(SUM(head <> '' AND tail <> ''), 0),
+       COALESCE(SUM(content <> ''), 0),
+       COALESCE(SUM(size), 0)
+FROM files
 `
 
 // databaseCounts is what info reads from the database: its schema
@@ -694,6 +615,8 @@ SELECT records, size FROM totals
 type databaseCounts struct {
 	schemaVersion int
 	records       int64 // every record
+	headTail      int64 // records with head and tail hashes
+	content       int64 // records with a content hash
 	size          int64 // the sizes of all records added up
 }
 
@@ -721,7 +644,7 @@ func readDatabaseCounts(ctx context.Context,
 	}
 
 	err = tx.QueryRowContext(ctx, databaseCountsSQL).
-		Scan(&c.records, &c.size)
+		Scan(&c.records, &c.headTail, &c.content, &c.size)
 	if err != nil {
 		return c, fmt.Errorf("count records: %w", err)
 	}
@@ -729,15 +652,90 @@ func readDatabaseCounts(ctx context.Context,
 	return c, nil
 }
 
-// loadFileMeta streams every record's path, size, disk_size and mtime
-// to fn. Scan change detection needs no hash values, and skipping the
-// hash columns keeps the scan's in-memory index small on
-// multi-million-file databases.
+// loadFileMeta streams every record's path, size, mtime, and whether
+// it carries hashes to fn. Scan change detection needs no hash
+// values, and skipping the hash columns keeps the scan's in-memory
+// index small on multi-million-file databases.
 func loadFileMeta(ctx context.Context, db *sql.DB,
-	fn func(path string, m fileMeta),
+	fn func(path string, size int64, mtime time.Time, hashed bool),
 ) error {
 	rows, err := db.QueryContext(ctx,
-		"SELECT path, size, disk_size, mtime, mtime_nsec FROM files")
+		"SELECT path, size, mtime, mtime_nsec, head <> '' FROM files")
+	if err != nil {
+		return fmt.Errorf("read records: %w", err)
+	}
+
+	defer func() { _ = rows.Close() }()
+
+	for rows.Next() {
+		var (
+			path            []byte
+			size, sec, nsec int64
+			hashed          int64
+		)
+
+		err = rows.Scan(&path, &size, &sec, &nsec, &hashed)
+		if err != nil {
+			return fmt.Errorf("read record: %w", err)
+		}
+
+		fn(string(path), size, time.Unix(sec, nsec), hashed != 0)
+	}
+
+	err = rows.Err()
+	if err != nil {
+		return fmt.Errorf("read records: %w", err)
+	}
+
+	return nil
+}
+
+// contentGroupsSQL selects each group (the records sharing a size,
+// head, and tail) of records of at least headTailMin bytes that has more
+// than one record and at least one record without a content hash, with
+// the number of its records.
+const contentGroupsSQL = `
+SELECT size, head, tail, COUNT(*) AS records
+FROM files
+WHERE size >= ? AND head <> ''
+GROUP BY size, head, tail
+HAVING COUNT(*) > 1 AND SUM(content = '') > 0
+`
+
+// contentCandidatesSQL selects every record of the groups
+// contentGroupsSQL selects, with whether each record has a content
+// hash. SQLite does the grouping, so no other record's hashes are
+// loaded into memory; the rows come ordered by size, head, and tail, so
+// each group's rows arrive together.
+const contentCandidatesSQL = `
+SELECT f.path, f.size, f.mtime, f.mtime_nsec, f.head, f.tail, f.content <> ''
+FROM files AS f
+JOIN (` + contentGroupsSQL + `) AS g USING (size, head, tail)
+ORDER BY size, head, tail
+`
+
+// countContentCandidates returns the number of rows of
+// contentCandidatesSQL, adding up the records of the groups
+// contentGroupsSQL selects, so it neither joins nor sorts.
+func countContentCandidates(ctx context.Context, db *sql.DB) (int64, error) {
+	var n int64
+
+	err := db.QueryRowContext(ctx,
+		"SELECT COALESCE(SUM(records), 0) FROM ("+contentGroupsSQL+")",
+		headTailMin).Scan(&n)
+	if err != nil {
+		return 0, fmt.Errorf("count content candidates: %w", err)
+	}
+
+	return n, nil
+}
+
+// loadContentCandidates streams the rows of contentCandidatesSQL to fn:
+// each record, without its content hash, and whether it has one.
+func loadContentCandidates(ctx context.Context, db *sql.DB,
+	fn func(r scanRec, hashed bool),
+) error {
+	rows, err := db.QueryContext(ctx, contentCandidatesSQL, headTailMin)
 	if err != nil {
 		return fmt.Errorf("read records: %w", err)
 	}
@@ -747,18 +745,20 @@ func loadFileMeta(ctx context.Context, db *sql.DB,
 	for rows.Next() {
 		var (
 			path      []byte
-			m         fileMeta
 			sec, nsec int64
+			r         scanRec
+			hashed    int64
 		)
 
-		err = rows.Scan(&path, &m.size, &m.diskSize, &sec, &nsec)
+		err = rows.Scan(&path, &r.size, &sec, &nsec, &r.head, &r.tail,
+			&hashed)
 		if err != nil {
 			return fmt.Errorf("read record: %w", err)
 		}
 
-		m.mtime = time.Unix(sec, nsec)
-
-		fn(string(path), m)
+		r.path = string(path)
+		r.mtime = time.Unix(sec, nsec)
+		fn(r, hashed != 0)
 	}
 
 	err = rows.Err()
@@ -776,21 +776,21 @@ func loadFileMeta(ctx context.Context, db *sql.DB,
 // WAL small and let concurrent reports observe progress.
 const updateBatchSize = 10000
 
-// applyChanges writes upserts for new and changed files and deletes for
-// vanished ones, in batched transactions. Progress is rendered on prog
-// (one increment per change).
+// applyChanges writes one scan's database changes — upserts for new and
+// changed files, deletes for vanished ones — in batched transactions.
+// Progress is rendered on prog (one increment per change).
 func applyChanges(ctx context.Context, db *sql.DB, upserts []scanRec,
 	deletes []string, prog *progress,
 ) error {
 	for batch := range slices.Chunk(upserts, updateBatchSize) {
-		err := applyBatch(ctx, db, batch, nil, nil, prog)
+		err := applyBatch(ctx, db, batch, nil, prog)
 		if err != nil {
 			return err
 		}
 	}
 
 	for batch := range slices.Chunk(deletes, updateBatchSize) {
-		err := applyBatch(ctx, db, nil, nil, batch, prog)
+		err := applyBatch(ctx, db, nil, batch, prog)
 		if err != nil {
 			return err
 		}
@@ -799,26 +799,10 @@ func applyChanges(ctx context.Context, db *sql.DB, upserts []scanRec,
 	return nil
 }
 
-// applyDiskSizes writes the disk_size of each of recs into its record,
-// in batched transactions, and leaves the rest of the record alone.
-// Progress is rendered on prog (one increment per record).
-func applyDiskSizes(ctx context.Context, db *sql.DB, recs []fileRec,
-	prog *progress,
-) error {
-	for batch := range slices.Chunk(recs, updateBatchSize) {
-		err := applyBatch(ctx, db, nil, batch, nil, prog)
-		if err != nil {
-			return err
-		}
-	}
-
-	return nil
-}
-
-// applyBatch commits one batch of upserts, disk_size updates and
-// deletes in a single transaction.
+// applyBatch commits one batch of upserts and deletes in a single
+// transaction.
 func applyBatch(ctx context.Context, db *sql.DB, upserts []scanRec,
-	diskSizes []fileRec, deletes []string, prog *progress,
+	deletes []string, prog *progress,
 ) error {
 	tx, err := db.BeginTx(ctx, nil)
 	if err != nil {
@@ -832,11 +816,6 @@ func applyBatch(ctx context.Context, db *sql.DB, upserts []scanRec,
 		return err
 	}
 
-	err = execDiskSizes(ctx, tx, diskSizes, prog)
-	if err != nil {
-		return err
-	}
-
 	err = execDeletes(ctx, tx, deletes, prog)
 	if err != nil {
 		return err
@@ -862,9 +841,8 @@ func execUpserts(ctx context.Context, tx *sql.Tx, upserts []scanRec,
 	defer func() { _ = st.Close() }()
 
 	for _, r := range upserts {
-		_, err = st.ExecContext(ctx, []byte(r.path), r.size, r.diskSize,
-			r.mtime.Unix(), r.mtime.Nanosecond(),
-			r.head[:], r.tail[:], r.content[:])
+		_, err = st.ExecContext(ctx, []byte(r.path), r.size,
+			r.mtime.Unix(), r.mtime.Nanosecond(), r.head, r.tail, r.content)
 		if err != nil {
 			return fmt.Errorf("upsert %s: %w", r.path, err)
 		}
@@ -875,31 +853,6 @@ func execUpserts(ctx context.Context, tx *sql.Tx, upserts []scanRec,
 	return nil
 }
 
-// execDiskSizes sets the disk_size of the record of each of recs. It
-// does not touch size, so the totals triggers do not fire.
-func execDiskSizes(ctx context.Context, tx *sql.Tx, recs []fileRec,
-	prog *progress,
-) error {
-	st, err := tx.PrepareContext(ctx,
-		"UPDATE files SET disk_size = ? WHERE path = ?")
-	if err != nil {
-		return fmt.Errorf("prepare disk_size update: %w", err)
-	}
-
-	defer func() { _ = st.Close() }()
-
-	for _, r := range recs {
-		_, err = st.ExecContext(ctx, r.diskSize, []byte(r.path))
-		if err != nil {
-			return fmt.Errorf("update disk_size of %s: %w", r.path, err)
-		}
-
-		prog.increment()
-	}
-
-	return nil
-}
-
 // execDeletes removes the records for paths no longer present.
 func execDeletes(ctx context.Context, tx *sql.Tx, deletes []string,
 	prog *progress,

db_test.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"context"
-	"crypto/sha256"
 	"database/sql"
 	"errors"
 	"fmt"
@@ -474,73 +473,17 @@ func TestLoadRowsCountAgreeDuringScan(t *testing.T) {
 	}
 }
 
-// TestLoadRowsRefuseWrongSizeHash stores a record whose head, tail or
-// content is not the 32 bytes of a SHA-256: either one byte, or the 64
-// bytes of a SHA-256 written as hex text. loadFileRows and
-// loadSignatureRows must each fail on it with an error naming its path.
-func TestLoadRowsRefuseWrongSizeHash(t *testing.T) {
+// TestSignatureRowsNeedNoSort checks that SQLite reads signatureRowsSQL
+// from the files_signature index alone, with nothing to sort: the
+// first record comes at once, so report's read phase counts each
+// record as it comes rather than waiting on SQLite for all of them.
+func TestSignatureRowsNeedNoSort(t *testing.T) {
 	t.Parallel()
 
-	hexText := strings.Repeat("ab", sha256.Size)
+	db := openTestDB(t)
 
-	cases := []struct {
-		name   string
-		update string
-		value  any
-	}{
-		{"one-byte head", "UPDATE files SET head = ?", []byte{0}},
-		{"hex-text head", "UPDATE files SET head = ?", hexText},
-		{"one-byte tail", "UPDATE files SET tail = ?", []byte{0}},
-		{"hex-text tail", "UPDATE files SET tail = ?", hexText},
-		{"one-byte content", "UPDATE files SET content = ?", []byte{0}},
-		{"hex-text content", "UPDATE files SET content = ?", hexText},
-	}
-	for _, c := range cases {
-		t.Run(c.name, func(t *testing.T) {
-			t.Parallel()
-
-			db := openTestDB(t)
-
-			err := applyChanges(t.Context(), db,
-				[]scanRec{{path: "/a/f"}}, nil, nil)
-			if err != nil {
-				t.Fatal(err)
-			}
-
-			_, err = db.ExecContext(t.Context(), c.update, c.value)
-			if err != nil {
-				t.Fatal(err)
-			}
-
-			loads := map[string]func() error{
-				"loadFileRows": func() error {
-					return loadFileRows(t.Context(), db, func(int64) {},
-						func(scanRec) {})
-				},
-				"loadSignatureRows": func() error {
-					return loadSignatureRows(t.Context(), db, func(int64) {},
-						func(scanRec) error { return nil })
-				},
-			}
-
-			for name, load := range loads {
-				err := load()
-				if !errors.Is(err, errHashSize) ||
-					!strings.Contains(err.Error(), "/a/f") {
-					t.Errorf("%s: err = %v, want %v naming /a/f",
-						name, err, errHashSize)
-				}
-			}
-		})
-	}
-}
-
-// queryPlan returns the detail of each line of SQLite's EXPLAIN QUERY
-// PLAN for query.
-func queryPlan(t *testing.T, db *sql.DB, query string) []string {
-	t.Helper()
-
-	rows, err := db.QueryContext(t.Context(), "EXPLAIN QUERY PLAN "+query)
+	rows, err := db.QueryContext(t.Context(),
+		"EXPLAIN QUERY PLAN "+signatureRowsSQL)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -568,164 +511,12 @@ func queryPlan(t *testing.T, db *sql.DB, query string) []string {
 		t.Fatal(err)
 	}
 
-	return plan
-}
-
-// TestSignatureRowsNeedNoSort checks that SQLite reads signatureRowsSQL
-// from the files_signature index alone, with nothing to sort: the
-// first record comes at once, so report's read phase counts each
-// record as it comes rather than waiting on SQLite for all of them.
-func TestSignatureRowsNeedNoSort(t *testing.T) {
-	t.Parallel()
-
-	db := openTestDB(t)
-
-	plan := queryPlan(t, db, signatureRowsSQL)
-
 	want := []string{"SCAN files USING COVERING INDEX files_signature"}
 	if !slices.Equal(plan, want) {
 		t.Errorf("query plan = %q, want %q", plan, want)
 	}
 }
 
-// TestCountsReadOnlyTotals checks that SQLite answers the queries for
-// the number of records and their total size from the one row of
-// totals. A plan that reads files or its index reads every record.
-func TestCountsReadOnlyTotals(t *testing.T) {
-	t.Parallel()
-
-	db := openTestDB(t)
-
-	for _, query := range []string{recordCountSQL, databaseCountsSQL} {
-		plan := queryPlan(t, db, query)
-
-		want := []string{"SCAN totals"}
-		if !slices.Equal(plan, want) {
-			t.Errorf("query plan of %q = %q, want %q", query, plan, want)
-		}
-	}
-}
-
-// TestCountsComeFromTotals sets the row of totals to numbers that files
-// does not hold, then checks that scan's load phase, the read phases of
-// trees and report, and info each report the numbers from totals.
-func TestCountsComeFromTotals(t *testing.T) {
-	t.Parallel()
-
-	// files is empty, so a count over files gives 0 records of 0 bytes.
-	const records, size = 7, 9000
-
-	db := openTestDB(t)
-
-	_, err := db.ExecContext(t.Context(),
-		"UPDATE totals SET records = ?, size = ?", records, size)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	scanTotal, err := countRecords(t.Context(), db)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	var treesTotal, reportTotal int64
-
-	err = loadFileRows(t.Context(), db,
-		func(n int64) { treesTotal = n }, func(scanRec) {})
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	err = loadSignatureRows(t.Context(), db,
-		func(n int64) { reportTotal = n },
-		func(scanRec) error { return nil })
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	info, err := readDatabaseCounts(t.Context(), db)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	for name, got := range map[string]int64{
-		"scan's load":   scanTotal,
-		"trees' read":   treesTotal,
-		"report's read": reportTotal,
-		"info":          info.records,
-	} {
-		if got != records {
-			t.Errorf("%s: %d records, want %d from totals",
-				name, got, records)
-		}
-	}
-
-	if info.size != size {
-		t.Errorf("info: size %d, want %d from totals", info.size, size)
-	}
-}
-
-// assertTotalsMatchFiles fails unless the row of totals holds the
-// number of records and the sizes of all records added up, as counted
-// over files.
-func assertTotalsMatchFiles(t *testing.T, db *sql.DB) {
-	t.Helper()
-
-	got, err := readDatabaseCounts(t.Context(), db)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	var records, size int64
-
-	err = db.QueryRowContext(t.Context(),
-		"SELECT COUNT(*), COALESCE(SUM(size), 0) FROM files").
-		Scan(&records, &size)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	if got.records != records || got.size != size {
-		t.Errorf("totals = %d records of %d bytes, files holds %d of %d",
-			got.records, got.size, records, size)
-	}
-}
-
-// TestTotalsMatchFiles scans the smoke tree, rescans it after two files
-// change size, and rescans it after two files are removed. After each
-// scan the row of totals must agree with files.
-func TestTotalsMatchFiles(t *testing.T) {
-	t.Parallel()
-
-	dir := buildSmokeTree(t)
-	db := openTestDB(t)
-
-	syncTree(t, db, dir)
-	assertTotalsMatchFiles(t, db)
-
-	writeFile(t, dir, "a/one.bin", pattern(10, 2500))
-	writeFile(t, dir, "t1/f1", pattern(30, 1000))
-
-	if st := syncTree(t, db, dir); st.updated != 2 {
-		t.Fatalf("rescan stats = %+v, want 2 updated", st)
-	}
-
-	assertTotalsMatchFiles(t, db)
-
-	for _, name := range []string{"a/unique.bin", "t2/sub/f2"} {
-		err := os.Remove(filepath.Join(dir, name))
-		if err != nil {
-			t.Fatal(err)
-		}
-	}
-
-	if st := syncTree(t, db, dir); st.removed != 2 {
-		t.Fatalf("rescan stats = %+v, want 2 removed", st)
-	}
-
-	assertTotalsMatchFiles(t, db)
-}
-
 func TestApplyChangesRoundTrip(t *testing.T) {
 	t.Parallel()
 
@@ -736,13 +527,12 @@ func TestApplyChangesRoundTrip(t *testing.T) {
 	// written.
 	recs := []scanRec{
 		{
-			size: 2, mtime: time.Unix(20, 999_999_999), head: testHash("h2"),
-			tail: testHash("t2"), content: testHash("c2"),
-			path: "/a/tab\tnew\nline",
+			size: 2, mtime: time.Unix(20, 999_999_999), head: "h2", tail: "t2",
+			content: "c2", path: "/a/tab\tnew\nline",
 		},
 		{
-			size: 1, mtime: time.Unix(10, 0), head: testHash("h1"),
-			tail: testHash("t1"), content: testHash("c1"), path: "/a/x",
+			size: 1, mtime: time.Unix(10, 0), head: "h1", tail: "t1",
+			content: "c1", path: "/a/x",
 		},
 	}
 
@@ -763,8 +553,8 @@ func TestApplyChangesRoundTrip(t *testing.T) {
 	// An upsert for an existing path updates in place; a delete
 	// removes exactly its path.
 	upd := scanRec{
-		size: 3, mtime: time.Unix(30, 0), head: testHash("h3"),
-		tail: testHash("t3"), content: testHash("c3"), path: "/a/x",
+		size: 3, mtime: time.Unix(30, 0), head: "h3", tail: "t3", content: "c3",
+		path: "/a/x",
 	}
 
 	err = applyChanges(t.Context(), db, []scanRec{upd},
@@ -791,8 +581,8 @@ func TestApplyChangesBatching(t *testing.T) {
 	recs := make([]scanRec, 0, n)
 	for i := range n {
 		recs = append(recs, scanRec{
-			size: int64(i), mtime: time.Unix(1, 0), head: testHash("h"),
-			tail: testHash("t"), path: fmt.Sprintf("/batch/%07d", i),
+			size: int64(i), mtime: time.Unix(1, 0), head: "h", tail: "t",
+			path: fmt.Sprintf("/batch/%07d", i),
 		})
 	}
 
@@ -822,3 +612,62 @@ func TestApplyChangesBatching(t *testing.T) {
 		t.Fatalf("records = %d, want 0", len(got))
 	}
 }
+
+// TestCountContentCandidates checks that countContentCandidates counts
+// the records the content phase's search returns: those of each group
+// of two or more records of headTailMin or more with a head, where at
+// least one has no content hash.
+func TestCountContentCandidates(t *testing.T) {
+	t.Parallel()
+
+	db := openTestDB(t)
+
+	// Each group's records: size, head, and content, one per record.
+	groups := []struct {
+		size     int64
+		head     string
+		contents []string
+	}{
+		{headTailMin, "h", []string{"", "c", "c"}}, // returned
+		{headTailMin + 1, "h", []string{"", ""}},   // returned
+		{headTailMin + 2, "h", []string{"c", "c"}}, // all hashed
+		{headTailMin + 3, "h", []string{""}},       // one record
+		{headTailMin - 1, "h", []string{"", ""}},   // too small
+		{headTailMin + 4, "", []string{"", ""}},    // no head
+	}
+
+	var recs []scanRec
+
+	for _, g := range groups {
+		for _, content := range g.contents {
+			recs = append(recs, scanRec{
+				size: g.size, mtime: time.Unix(1, 0), head: g.head,
+				tail: "t", content: content,
+				path: fmt.Sprintf("/r/%d", len(recs)),
+			})
+		}
+	}
+
+	err := applyChanges(t.Context(), db, recs, nil, nil)
+	if err != nil {
+		t.Fatalf("applyChanges: %v", err)
+	}
+
+	got, err := countContentCandidates(t.Context(), db)
+	if err != nil {
+		t.Fatalf("countContentCandidates: %v", err)
+	}
+
+	var returned int64
+
+	err = loadContentCandidates(t.Context(), db,
+		func(scanRec, bool) { returned++ })
+	if err != nil {
+		t.Fatalf("loadContentCandidates: %v", err)
+	}
+
+	if got != 5 || returned != 5 {
+		t.Errorf("count = %d, records returned = %d, want 5 and 5",
+			got, returned)
+	}
+}

exclude_test.go

@@ -17,9 +17,7 @@ import (
 func TestDefaultExcludes(t *testing.T) {
 	t.Parallel()
 
-	// README "Rules for the walk": the Linux and macOS lists, and none
-	// on any other system. The Windows list exists in the code only: the
-	// binary does not build for Windows, so the README leaves it out.
+	// README "Rules for the walk": each system's list.
 	cases := map[string][]string{
 		goosLinux: {"/proc", "/sys", "/dev", "/run", "/tmp", "/var/tmp"},
 		goosDarwin: {
@@ -166,8 +164,9 @@ func TestDefaultExcludesHelp(t *testing.T) {
 // TestScanDoesNotEnterDefaultExclude checks that the walk does not
 // enter a default exclude below an operand. It says so on a line of its
 // own and does not count it as skipped. The records below it count as
-// outside the operands: the record of a file gone from it is kept,
-// while a file added to it is not recorded.
+// outside the operands: the record of a file gone from it is kept, and
+// its size joins the size census, while a file added to it is not
+// recorded.
 //
 //nolint:paralleltest // captureStderr replaces the process-wide os.Stderr
 func TestScanDoesNotEnterDefaultExclude(t *testing.T) {
@@ -187,6 +186,10 @@ func TestScanDoesNotEnterDefaultExclude(t *testing.T) {
 
 	unseen := writeFile(t, excluded, "new", pattern(2, 10))
 
+	// The same size as gone, so it is hashed only if the census holds the
+	// size of gone's record.
+	added := writeFile(t, dir, "added", pattern(3, 100))
+
 	st, err := syncScan(t.Context(), db, []string{dir}, 1, false,
 		walkRules{excludes: []string{excluded}})
 	if err != nil {
@@ -200,6 +203,11 @@ func TestScanDoesNotEnterDefaultExclude(t *testing.T) {
 	recs := dbRecords(t, db)
 	recordByPath(t, recs, gone)
 
+	if recordByPath(t, recs, added).head == "" {
+		t.Errorf("%s not hashed: the census lacks the size of %s",
+			added, gone)
+	}
+
 	if slices.Contains(recordPaths(recs), unseen) {
 		t.Errorf("%s recorded: the walk entered %s", unseen, excluded)
 	}
@@ -383,8 +391,9 @@ func TestRunScanSkipsNonPersistentOperand(t *testing.T) {
 // TestScanKeepsRecordsOnNonPersistent scans a directory on a filesystem
 // that is not persistent beside one on the tests' temporary directory.
 // The records an earlier scan left in it count as outside the operands:
-// the record of a file gone from it is kept, while a file added to it
-// is not recorded.
+// the record of a file gone from it is kept, and its size joins the size
+// census, while a file added to it is not recorded, and its size does
+// not join the census.
 //
 //nolint:paralleltest // captureStderr replaces the process-wide os.Stderr
 func TestScanKeepsRecordsOnNonPersistent(t *testing.T) {
@@ -404,6 +413,11 @@ func TestScanKeepsRecordsOnNonPersistent(t *testing.T) {
 
 	unseen := writeFile(t, shm, "new", pattern(2, 10))
 
+	// added has the size of gone, and lonely that of unseen: each is
+	// hashed only if the census holds that size.
+	added := writeFile(t, dir, "added", pattern(3, 100))
+	lonely := writeFile(t, dir, "lonely", pattern(4, 10))
+
 	st, err := syncScan(t.Context(), db, []string{shm, dir}, 1, false, rules)
 	if err != nil {
 		t.Fatal(err)
@@ -416,6 +430,15 @@ func TestScanKeepsRecordsOnNonPersistent(t *testing.T) {
 	recs := dbRecords(t, db)
 	recordByPath(t, recs, gone)
 
+	if recordByPath(t, recs, added).head == "" {
+		t.Errorf("%s not hashed: the census lacks the size of %s",
+			added, gone)
+	}
+
+	if recordByPath(t, recs, lonely).head != "" {
+		t.Errorf("%s hashed: the census holds the size of %s", lonely, unseen)
+	}
+
 	if slices.Contains(recordPaths(recs), unseen) {
 		t.Errorf("%s recorded", unseen)
 	}
@@ -427,6 +450,51 @@ func TestScanKeepsRecordsOnNonPersistent(t *testing.T) {
 	}
 }
 
+// TestScanContentSkipsNonPersistent checks that the content phase does
+// not read a file on a filesystem that is not persistent, though an
+// earlier scan left a record for it: it is treated as a changed file,
+// so its record is left as it is and its identical copy in another
+// tree, having no other match, is not read either.
+func TestScanContentSkipsNonPersistent(t *testing.T) {
+	t.Parallel()
+
+	shm, _, rules := shmTempDir(t)
+	db := openTestDB(t)
+
+	// A scan that, without the list of filesystems, records a with a
+	// head and tail but no content hash.
+	a := sparseFileWithoutMatch(t, shm, "a", headTailMin)
+
+	syncTree(t, db, shm)
+
+	before := recordByPath(t, dbRecords(t, db), a)
+	if before.head == "" || before.content != "" {
+		t.Fatalf("after scanning %s: %+v, want head and tail only", shm, before)
+	}
+
+	b := sparseFile(t, t.TempDir(), "b", headTailMin)
+
+	st, err := syncScan(t.Context(), db, []string{filepath.Dir(b)}, 1, false,
+		rules)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if st.skipped != 0 {
+		t.Errorf("skipped = %d, want 0", st.skipped)
+	}
+
+	recs := dbRecords(t, db)
+	if r := recordByPath(t, recs, a); r != before {
+		t.Errorf("record = %+v, want it left as %+v", r, before)
+	}
+
+	if r := recordByPath(t, recs, b); r.content != "" {
+		t.Errorf("%s: content = %q, want none: its only match is on %s",
+			b, r.content, shm)
+	}
+}
+
 // TestWalkLeavesOutNonPersistent starts the walk itself in a directory
 // on a filesystem that is not persistent, which a scan never does: it
 // drops such an operand first. Below a directory on a persistent

info.go

@@ -26,11 +26,11 @@ func infoPhase(name string) string {
 // it. Any database problem, including a missing database, is fatal.
 //
 // The work runs in two phases, each under a progress display of its
-// own on stderr: open (open the database) and count (read the number of
-// records and their total size from the totals table). Each display
-// ends before the next phase starts, and before an error is returned
-// to be printed. The details are written once the last display has
-// ended, so no display is drawn while they are written.
+// own on stderr: open (open the database) and count (count the records,
+// with one query). Each display ends before the next phase starts, and
+// before an error is returned to be printed. The details are written
+// once the last display has ended, so no display is drawn while they
+// are written.
 func runInfo(ctx context.Context, stdout io.Writer) error {
 	dbPath, source, err := databasePath()
 	if err != nil {
@@ -56,7 +56,7 @@ func runInfo(ctx context.Context, stdout io.Writer) error {
 
 	defer func() { _ = db.Close() }()
 
-	// One row holds both counts, so the phase never has a total.
+	// One query counts everything, so the phase never has a total.
 	prog = newProgress(progressParams{
 		label: infoPhase("count"), total: -1,
 		waitingFor: countingRecords,
@@ -113,6 +113,9 @@ func writeInfo(stdout io.Writer, dbPath, source string,
 		dbFile.ModTime().UTC().Format(time.RFC3339))
 	fmt.Fprintf(&b, "schema version\t%d\n", counts.schemaVersion)
 	fmt.Fprintf(&b, "records\t%d\n", counts.records)
+	fmt.Fprintf(&b, "records with head and tail hashes\t%d\n",
+		counts.headTail)
+	fmt.Fprintf(&b, "records with content hash\t%d\n", counts.content)
 	fmt.Fprintf(&b, "size of recorded files\t%d (%s)\n",
 		counts.size, humanBytes(counts.size))
 

info_test.go

@@ -12,25 +12,23 @@ import (
 // infoOpenLine is the plain line of info's open phase when it opens the
 // database at once; it prints it as the phase starts and as it ends.
 const infoOpenLine = "[1/2] open: opening the database, elapsed 0s, " +
-	"remain unknown"
+	"eta unknown"
 
 // infoCountLine is the plain line of info's count phase when the count
 // takes under a second; it prints it as the phase starts and as it
 // ends.
 const infoCountLine = "[2/2] count: counting the records, elapsed 0s, " +
-	"remain unknown"
+	"eta unknown"
 
-// infoRecs are four records: a duplicate pair, a file of 20 MiB and
-// another small file.
+// infoRecs are four records: a duplicate pair with every hash, a file
+// of 20 MiB with head and tail hashes but no content hash yet, and a
+// file never hashed.
 func infoRecs() []scanRec {
-	h, tl, c, u := testHash("h"), testHash("t"), testHash("c"), testHash("u")
-	bigH, bigT, bigC := testHash("bh"), testHash("bt"), testHash("bc")
-
 	return []scanRec{
-		{size: 5, head: h, tail: tl, content: c, path: "/d/a"},
-		{size: 5, head: h, tail: tl, content: c, path: "/d/b"},
-		{size: 20 << 20, head: bigH, tail: bigT, content: bigC, path: "/d/big"},
-		{size: 7, head: u, tail: u, content: u, path: "/d/unique"},
+		{size: 5, head: "h", tail: "t", content: "c", path: "/d/a"},
+		{size: 5, head: "h", tail: "t", content: "c", path: "/d/b"},
+		{size: 20 << 20, head: "bh", tail: "bt", path: "/d/big"},
+		{size: 7, path: "/d/unique"},
 	}
 }
 
@@ -47,12 +45,16 @@ func TestRunInfo(t *testing.T) {
 		"empty": {
 			want: "schema version\t1\n" +
 				"records\t0\n" +
+				"records with head and tail hashes\t0\n" +
+				"records with content hash\t0\n" +
 				"size of recorded files\t0 (0 B)\n",
 		},
 		"filled": {
 			recs: infoRecs(),
 			want: "schema version\t1\n" +
 				"records\t4\n" +
+				"records with head and tail hashes\t3\n" +
+				"records with content hash\t2\n" +
 				"size of recorded files\t20971537 (20.0 MiB)\n",
 		},
 	}

main.go

@@ -1,12 +1,14 @@
 // Command sfdupes quickly identifies candidate duplicate files across
 // very large filesystems without reading every byte of every file.
 // Files are considered duplicates when their sizes are equal and they
-// agree on three SHA-256 hashes: of the first 64 KiB, of the last 64
-// KiB, and of the content. The content hash covers the whole file under
-// 100 MiB, and 1 MiB at each gigabyte at 100 MiB or more, so a large
-// file is never read in full. scan maintains a persistent SQLite
-// database of file signatures (SFDUPES_DATABASE, default
-// /var/lib/sfdupes/db.sqlite) that the other subcommands read.
+// agree on a short ladder of SHA-256 hashes. A file under 10 MiB is
+// hashed in full. A larger file is compared on the hashes of its first
+// and last 64 KiB, and only when those match another file's is its
+// content hash computed and compared: of the whole file when it is
+// under 50 MiB, or of gigabyte-spaced 1 MiB samples when it is 50 MiB
+// or larger. scan maintains a persistent SQLite database of file
+// signatures (SFDUPES_DATABASE, default /var/lib/sfdupes/db.sqlite)
+// that the other subcommands read.
 //
 // Usage:
 //
@@ -236,7 +238,7 @@ func newScanCommand() *cobra.Command {
 		}),
 	}
 	scanCmd.Flags().IntVar(&scanWorkers, "workers", runtime.NumCPU(),
-		"concurrent workers for the walk and hash phases")
+		"concurrent workers for the walk, hash, and content phases")
 	scanCmd.Flags().BoolVarP(&scanOneFS, "one-file-system", "x", false,
 		"do not cross filesystem boundaries")
 	scanCmd.Flags().BoolVar(&scanNoDefaultExcludes, "no-default-excludes",

main_test.go

@@ -180,9 +180,9 @@ func capture(t *testing.T, std **os.File) func() string {
 }
 
 // brokenDatabase writes a database that opens cleanly and passes the
-// schema-version check but has no tables, so the first query fails
-// with the database already open: a fatal error on a path that owns an
-// open database. It closes the database the way scan does.
+// schema-version check but has no files table, so the first query
+// fails with the database already open: a fatal error on a path that
+// owns an open database. It closes the database the way scan does.
 func brokenDatabase(t *testing.T) string {
 	t.Helper()
 
@@ -265,9 +265,8 @@ func TestRunFatalAfterOpenClosesDatabase(t *testing.T) {
 			assertFatalOutput(t, stderr.String(), stdout())
 
 			// Proof that the failure happened after the open: only a
-			// query against the opened database can report this. Each
-			// subcommand's first query reads totals.
-			if !strings.Contains(stderr.String(), "no such table: totals") {
+			// query against the opened database can report this.
+			if !strings.Contains(stderr.String(), "no such table: files") {
 				t.Errorf("stderr = %q, want the failure to come from a "+
 					"query on the open database", stderr.String())
 			}
@@ -394,7 +393,7 @@ func TestRunNamesRelativeDatabase(t *testing.T) {
 }
 
 func TestRunUsesDatabaseThroughSymlinkedDirectory(t *testing.T) {
-	// README §Settings: the path names the file exactly. With link a
+	// README §Database: the path names the file exactly. With link a
 	// symlink to the directory real/sub, link/../db.sqlite names
 	// real/db.sqlite, not db.sqlite beside link. Every subcommand must
 	// use that file, relative or absolute, and its first line must name
@@ -649,7 +648,7 @@ func TestRunUsageErrors(t *testing.T) {
 }
 
 func TestRunScanRejectsWorkersBelowOne(t *testing.T) {
-	// README §Settings: --workers below 1 is a usage error reported in
+	// README §scan mode: --workers below 1 is a usage error reported in
 	// one line on stderr, before the scan opens the database.
 	for _, workers := range []string{"0", "-1"} {
 		t.Run(workers, func(t *testing.T) {
@@ -687,8 +686,8 @@ func TestRunScanRejectsWorkersBelowOne(t *testing.T) {
 func TestRunHelp(t *testing.T) {
 	t.Parallel()
 
-	// README §Settings: help goes to stderr, exits 0, and leaves stdout
-	// empty.
+	// README §Subcommands: help goes to stderr, exits 0, and leaves
+	// stdout empty.
 	cases := [][]string{{"--help"}, {"-h"}, {cmdScan, "--help"}}
 
 	for _, args := range cases {
@@ -714,8 +713,8 @@ func TestRunHelp(t *testing.T) {
 func TestRunVersion(t *testing.T) {
 	t.Parallel()
 
-	// README §Settings: the version is one line on stdout, with nothing
-	// on stderr, and exits 0.
+	// README §Subcommands: the version is one line on stdout, with
+	// nothing on stderr, and exits 0.
 	info, _ := debug.ReadBuildInfo()
 
 	for _, arg := range []string{"--version", "-v"} {
@@ -774,8 +773,8 @@ func TestBuildVersion(t *testing.T) {
 func TestRunVersionWriteFailureIsFatal(t *testing.T) {
 	t.Parallel()
 
-	// README §Error handling: a failed write to stdout is a fatal error,
-	// exit 1, reported on stderr starting with "sfdupes:".
+	// README §Error handling: a stdout write failure exits 1, reported
+	// in one line on stderr.
 	var stderr bytes.Buffer
 
 	code := run([]string{"--version"}, failingWriter{}, &stderr)
@@ -818,23 +817,6 @@ func scanFixture(t *testing.T) []string {
 	return dupes
 }
 
-// storedDiskSize returns the disk_size of the record for path in the
-// database at dbPath. A test of a trees run compares with this rather
-// than with a new lstat, which on ZFS can differ from the scan's (see
-// diskSizeOf).
-func storedDiskSize(t *testing.T, dbPath, path string) int64 {
-	t.Helper()
-
-	db, err := openReportDatabase(t.Context(), dbPath)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	defer func() { _ = db.Close() }()
-
-	return recordByPath(t, dbRecords(t, db), path).diskSize
-}
-
 // scanOK runs scan over operands, fails the test unless it exits 0 with
 // nothing on stdout, and returns everything it printed to stderr.
 func scanOK(t *testing.T, operands ...string) string {
@@ -946,21 +928,24 @@ func TestRunScanWalksOperandUnderSymlinkOperand(t *testing.T) {
 }
 
 func TestRunScanSkipsZFSOperand(t *testing.T) {
-	zfs := filepath.Join(t.TempDir(), ".zfs")
-	f := writeFile(t, zfs, "snapshot/hourly/f", pattern(1, 10))
-
-	// No scan records a file inside a .zfs directory, so the record
-	// beneath the operand is written straight into the database.
-	path := seedDatabase(t, []scanRec{{size: 10, path: f}})
+	path := testDBPath(t)
 	t.Setenv(databaseEnv, path)
 
+	zfs := filepath.Join(t.TempDir(), ".zfs")
+	snapshot := filepath.Join(zfs, "snapshot", "hourly")
+	f := writeFile(t, snapshot, "f", pattern(1, 10))
+
+	// An operand beneath a .zfs directory is walked, because it is not
+	// itself named .zfs.
+	scanOK(t, snapshot)
+
 	assertOperandSkipped(t, path, zfs, ".zfs directory", f)
 }
 
 // assertOperandSkipped scans operand alone and checks that it is skipped
 // as kind: a warning naming it, one skip in the summary, exit 0, and the
-// record for kept, stored beneath operand before this scan, still in the
-// database at dbPath.
+// record for kept, which an earlier scan stored beneath operand, still
+// in the database at dbPath.
 func assertOperandSkipped(t *testing.T, dbPath, operand, kind,
 	kept string,
 ) {
@@ -989,121 +974,6 @@ func assertOperandSkipped(t *testing.T, dbPath, operand, kind,
 	recordByPath(t, dbRecords(t, db), kept)
 }
 
-// TestRunScanSkipsOperandInsideZFS scans a directory inside a .zfs
-// directory, first alone and then under another operand. Each time it
-// is warned about and counted as skipped, and nothing in it is walked.
-// The other operand is scanned as usual.
-func TestRunScanSkipsOperandInsideZFS(t *testing.T) {
-	path := testDBPath(t)
-	t.Setenv(databaseEnv, path)
-
-	dir := t.TempDir()
-	hourly := filepath.Join(dir, ".zfs", "snapshot", "hourly")
-	writeFile(t, hourly, "f", pattern(1, 10))
-	f := writeFile(t, dir, "f", pattern(2, 10))
-
-	warning := "walk " + hourly + ": skipping operand inside a .zfs directory\n"
-
-	for _, tc := range []struct {
-		operands []string
-		summary  string
-	}{
-		{
-			[]string{hourly},
-			"scan: 0 files seen (0 added, 0 updated, 0 removed, " +
-				"0 unchanged), 1 skipped\n",
-		},
-		{
-			[]string{dir, hourly},
-			"scan: 1 files seen (1 added, 0 updated, 0 removed, " +
-				"0 unchanged), 1 skipped\n",
-		},
-	} {
-		stderr := scanOK(t, tc.operands...)
-		if !strings.Contains(stderr, warning) ||
-			!strings.Contains(stderr, tc.summary) {
-			t.Errorf("scan %q: stderr = %q, want %q and %q", tc.operands,
-				stderr, warning, tc.summary)
-		}
-	}
-
-	db, err := openDB(path, reportParams)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	t.Cleanup(func() { _ = db.Close() })
-
-	if got := recordPaths(dbRecords(t, db)); !slices.Equal(got, []string{f}) {
-		t.Errorf("records = %q, want %q", got, []string{f})
-	}
-}
-
-// TestRunScanSkipsOperandThroughSymlinkIntoZFS scans snaps/daily, where
-// snaps is a symlink to pool/.zfs/snapshot. The operand is warned about
-// by the path given, counted as skipped, and not walked.
-func TestRunScanSkipsOperandThroughSymlinkIntoZFS(t *testing.T) {
-	t.Setenv(databaseEnv, testDBPath(t))
-
-	dir := t.TempDir()
-	writeFile(t, dir, "pool/.zfs/snapshot/daily/f", pattern(1, 10))
-
-	snaps := filepath.Join(dir, "snaps")
-
-	err := os.Symlink(filepath.Join(dir, "pool", ".zfs", "snapshot"), snaps)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	daily := filepath.Join(snaps, "daily")
-	stderr := scanOK(t, daily)
-
-	warning := "walk " + daily + ": skipping operand inside a .zfs directory\n"
-	summary := "scan: 0 files seen (0 added, 0 updated, 0 removed, " +
-		"0 unchanged), 1 skipped\n"
-
-	if !strings.Contains(stderr, warning) ||
-		!strings.Contains(stderr, summary) {
-		t.Errorf("stderr = %q, want %q and %q", stderr, warning, summary)
-	}
-}
-
-// TestRunScanWalksOperandThroughSymlink scans data/daily, where data is
-// a symlink to a directory outside any .zfs directory. The operand is
-// scanned as usual, and its file is recorded by the path given.
-func TestRunScanWalksOperandThroughSymlink(t *testing.T) {
-	path := testDBPath(t)
-	t.Setenv(databaseEnv, path)
-
-	dir := t.TempDir()
-	writeFile(t, dir, "pool/data/daily/f", pattern(1, 10))
-
-	data := filepath.Join(dir, "data")
-
-	err := os.Symlink(filepath.Join(dir, "pool", "data"), data)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	daily := filepath.Join(data, "daily")
-	stderr := scanOK(t, daily)
-
-	summary := "scan: 1 files seen (1 added, 0 updated, 0 removed, " +
-		"0 unchanged), 0 skipped\n"
-	if !strings.Contains(stderr, summary) {
-		t.Errorf("stderr = %q, want %q", stderr, summary)
-	}
-
-	db, err := openDB(path, reportParams)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	t.Cleanup(func() { _ = db.Close() })
-
-	recordByPath(t, dbRecords(t, db), filepath.Join(daily, "f"))
-}
-
 func TestRunReportSucceeds(t *testing.T) {
 	path := testDBPath(t)
 	t.Setenv(databaseEnv, path)
@@ -1158,9 +1028,8 @@ func TestRunTreesSucceeds(t *testing.T) {
 
 	// The two directories holding the duplicate pair are duplicate
 	// trees of each other.
-	want := "first\tdupe\tfiles\tsize\tdisk_size\n" +
-		filepath.Dir(dupes[0]) + "\t" + filepath.Dir(dupes[1]) + "\t1\t300\t" +
-		strconv.FormatInt(storedDiskSize(t, path, dupes[1]), 10) + "\n"
+	want := "first\tdupe\tfiles\tsize\n" +
+		filepath.Dir(dupes[0]) + "\t" + filepath.Dir(dupes[1]) + "\t1\t300\n"
 	if got := stdout.String(); got != want {
 		t.Errorf("stdout = %q, want %q", got, want)
 	}
@@ -1194,10 +1063,9 @@ func TestRunReportsNeedOnlyReadAccess(t *testing.T) {
 	cases := map[string]string{
 		cmdReport: "first\tdupe\tsize\n" +
 			dupes[0] + "\t" + dupes[1] + "\t300\n",
-		cmdTrees: "first\tdupe\tfiles\tsize\tdisk_size\n" +
+		cmdTrees: "first\tdupe\tfiles\tsize\n" +
 			filepath.Dir(dupes[0]) + "\t" + filepath.Dir(dupes[1]) +
-			"\t1\t300\t" +
-			strconv.FormatInt(storedDiskSize(t, path, dupes[1]), 10) + "\n",
+			"\t1\t300\n",
 	}
 
 	for name, want := range cases {
@@ -1232,11 +1100,8 @@ func assertRunsUseDatabase(t *testing.T, dir, name string) {
 		t.Errorf("report stdout = %q, want %q", got, want)
 	}
 
-	diskSize := storedDiskSize(t, filepath.Join(dir, name), dupes[1])
-
-	want = "first\tdupe\tfiles\tsize\tdisk_size\n" +
-		filepath.Dir(dupes[0]) + "\t" + filepath.Dir(dupes[1]) + "\t1\t300\t" +
-		strconv.FormatInt(diskSize, 10) + "\n"
+	want = "first\tdupe\tfiles\tsize\n" +
+		filepath.Dir(dupes[0]) + "\t" + filepath.Dir(dupes[1]) + "\t1\t300\n"
 	if got := runStdout(t, cmdTrees); got != want {
 		t.Errorf("trees stdout = %q, want %q", got, want)
 	}
@@ -1257,7 +1122,7 @@ func assertRunsUseDatabase(t *testing.T, dir, name string) {
 }
 
 func TestRunDatabasePathUsedAsGiven(t *testing.T) {
-	// README §Settings: the path names the database file exactly. In
+	// README §Database: the path names the database file exactly. In
 	// SQLite's connection string an unescaped ? or # would end the file
 	// name and % would start an escape, and a path starting with //
 	// could be read as a host name. %25 is a valid escape, so unescaped
@@ -1302,8 +1167,9 @@ func holdScanLock(t *testing.T, path string) {
 }
 
 func TestRunSecondScanFails(t *testing.T) {
-	// README §Database: a second scan that finds the lock held fails
-	// at once, naming the lock file, without opening the database.
+	// README §Database: while one scan holds the lock, a second scan
+	// fails at once, naming the lock file, without opening the
+	// database.
 	path := testDBPath(t)
 	t.Setenv(databaseEnv, path)
 
@@ -1362,7 +1228,7 @@ func assertSecondScanFails(t *testing.T, path string) {
 }
 
 func TestRunSecondScanThroughSymlinkFails(t *testing.T) {
-	// README §Database: a path through a symlink names the same lock
+	// README §Database: every path to one database names the same lock
 	// file, so while a scan holds it through one path, a scan through
 	// another fails, naming the lock file beside the database's real
 	// path.
@@ -1467,8 +1333,8 @@ func TestRunReportsDuringScan(t *testing.T) {
 }
 
 func TestRunStdoutClosedIsFatal(t *testing.T) {
-	// README §Error handling: a failed write to stdout is a fatal error,
-	// exit 1, reported on stderr starting with "sfdupes:".
+	// README §Error handling: a stdout write failure exits 1, reported
+	// in one line on stderr.
 	for _, name := range []string{cmdReport, cmdTrees, cmdInfo} {
 		t.Run(name, func(t *testing.T) {
 			t.Setenv(databaseEnv, testDBPath(t))

progress.go

@@ -9,7 +9,6 @@ import (
 	"strings"
 	"sync"
 	"time"
-	"unicode/utf8"
 
 	"github.com/schollz/progressbar/v3"
 	"golang.org/x/term"
@@ -35,17 +34,10 @@ const stallTime = 10 * time.Second
 // spinnerType selects the progressbar library's spinner style.
 const spinnerType = 14
 
-// barWidth is the width of a phase's bar between its two ends, as in
-// the example line in README "Progress".
+// barWidth is the width of the progressbar library's bar between its
+// two ends, as in the example line in README "Progress".
 const barWidth = 10
 
-// barCell is one column of the filled part of a bar.
-const barCell = "█"
-
-// barColumns is the width of what percentBar returns: the percent in
-// four columns and its sign, a space, and the bar with its two ends.
-const barColumns = barWidth + 8
-
 // percentScale converts a fraction to a percentage.
 const percentScale = 100
 
@@ -53,14 +45,19 @@ const percentScale = 100
 // read, as the progressbar library takes it.
 const fallbackWidth = 80
 
-// spinnerMargin is the columns of a line besides its text: the spinner
-// and the three spaces the library draws around the text, and the
-// terminal's last column, which every line stays clear of so that no
-// terminal wraps it.
+// spinnerMargin is the columns of a spinner's line besides its text:
+// the spinner and the three spaces the library draws around the text,
+// and the terminal's last column, which every line stays clear of so
+// that no terminal wraps it.
 const spinnerMargin = 5
 
+// barMargin is the columns of a bar's line besides its text: the
+// percent and the bar the library draws after the text, the spaces
+// around them, and the terminal's last column.
+const barMargin = barWidth + 11
+
 // countingRecords is what the display of a phase that reads the records
-// says until it has the number of records, its total.
+// says while it counts them, before it has its total.
 const countingRecords = "counting the records"
 
 // openPhase is the name of the phase in which report, trees and info
@@ -88,7 +85,7 @@ func terminalWidth() int {
 	return width
 }
 
-// phaseLabel names phase with its place among phases, as "[2/4] walk".
+// phaseLabel names phase with its place among phases, as "[2/5] walk".
 func phaseLabel(phases []string, phase string) string {
 	return fmt.Sprintf("[%d/%d] %s",
 		slices.Index(phases, phase)+1, len(phases), phase)
@@ -112,13 +109,13 @@ type drawnCount struct {
 }
 
 // progress renders one phase's progress on stderr. On a TTY the
-// progressbar library draws its spinner and then line, fitted to the
-// terminal's width. A phase with an exact total ends the line with its
-// percent and bar, at the terminal's right edge, when the terminal has
-// room for them. It is drawn again every redrawInterval, so its elapsed
-// time keeps moving while the phase waits for its next item. When
-// stderr is not a TTY it emits no ANSI redraws: it prints line as the
-// phase starts, every plainInterval while it runs, and as it ends.
+// progressbar library draws line, fitted to the terminal's width: after
+// the library's spinner, or, for a phase with an exact total, before the
+// library's bar when the terminal has room for the bar beside it. It is
+// drawn again every redrawInterval, so its elapsed time keeps moving
+// while the phase waits for its next item. When stderr is not a TTY it
+// emits no ANSI redraws: it prints line as the phase starts, every
+// plainInterval while it runs, and as it ends.
 //
 // The draws come from a goroutine of their own, so mu guards the fields
 // below it. Every method must be called from the main goroutine. A nil
@@ -134,6 +131,7 @@ type progress struct {
 
 	mu         sync.Mutex
 	bar        *progressbar.ProgressBar // what the library draws; nil until then
+	withBar    bool                     // bar is the library's bar, not its spinner
 	widest     int                      // the widest line bar has drawn, in columns
 	label      string
 	unit       string
@@ -143,7 +141,7 @@ type progress struct {
 	stalledOn  string
 	count      int64
 	start      time.Time // when the phase started, for the elapsed time
-	rateStart  time.Time // when the count started, for the time remaining
+	rateStart  time.Time // when the count started, for the ETA
 	lastItem   time.Time // when the last item was completed, or the count started
 	// drawn holds the count at each draw over the last rateWindow, oldest
 	// first; the rate counts from the first. It keeps the draw before the
@@ -217,34 +215,55 @@ func (p *progress) draw() {
 	}
 
 	if p.width == nil {
-		fmt.Fprintln(os.Stderr, p.line(now, math.MaxInt, false))
+		fmt.Fprintln(os.Stderr, p.line(now, math.MaxInt, true))
 
 		return
 	}
 
 	width := p.width()
-	text := p.line(now, width-spinnerMargin, true)
 
-	// Before each draw the library erases its line with as many spaces as
-	// the widest line it has drawn. A display gets a new one when the
-	// terminal has been made too narrow for that erase, which would wrap
-	// and leave a line behind at every draw.
-	if p.bar == nil || p.widest >= width {
-		p.newBar(width)
+	// A phase with an exact total gets the library's bar when its whole
+	// line, without the percent the bar shows, fits beside the bar: the
+	// bar gives way before any part of the line. A total of 0 leaves the
+	// bar nothing to fill.
+	text, withBar := "", false
+	if p.total > 0 && !p.estimate {
+		text = p.line(now, math.MaxInt, false)
+		withBar = len(text) <= width-barMargin
+	}
+
+	margin := barMargin
+	if !withBar {
+		margin = spinnerMargin
+		text = p.line(now, width-margin, true)
+	}
+
+	// The library makes a bar or a spinner, and before each draw erases
+	// its line with as many spaces as the widest line it has drawn. A
+	// display gets a new one when it turns from one to the other, as its
+	// line grows or the terminal is resized, and when the terminal has
+	// been made too narrow for that erase, which would wrap and leave a
+	// line behind at every draw.
+	if p.bar == nil || p.withBar != withBar || p.widest >= width {
+		p.newBar(withBar, width)
+	}
+
+	if withBar {
+		_ = p.bar.Set64(p.count)
 	}
 
 	p.bar.Describe(text)
 
-	// The library drew the spinner, the text and the spaces around it,
-	// less the terminal's last column, which spinnerMargin keeps clear. A
-	// bar's cells take one column each but more than one byte.
-	p.widest = max(p.widest, utf8.RuneCountInString(text)+spinnerMargin-1)
+	// The library drew the text and its margin, less the terminal's last
+	// column, which the margin keeps clear.
+	p.widest = max(p.widest, len(text)+margin-1)
 }
 
-// newBar has the library make what draw draws: its spinner, followed by
-// the text draw gives it and nothing of the library's own. p.mu must be
-// held.
-func (p *progress) newBar(width int) {
+// newBar has the library make what draw draws: a bar for the phase's
+// total when withBar is set, and a spinner when not. Either shows the
+// text draw gives it, and nothing of its own besides the spinner, or
+// the bar and its percent. p.mu must be held.
+func (p *progress) newBar(withBar bool, width int) {
 	if p.bar != nil {
 		// Erase what was drawn before, short of the last column of a
 		// terminal that may have been made narrower since: the library's
@@ -253,36 +272,29 @@ func (p *progress) newBar(width int) {
 		fmt.Fprint(os.Stderr, "\r"+blank+"\r")
 	}
 
-	// A total of -1 gives the library's spinner.
-	p.bar = progressbar.NewOptions64(-1,
+	total := int64(-1) // the library's spinner
+	if withBar {
+		total = p.total
+	}
+
+	p.bar = progressbar.NewOptions64(total,
 		progressbar.OptionSetWriter(os.Stderr),
+		progressbar.OptionSetWidth(barWidth),
 		progressbar.OptionSpinnerType(spinnerType),
 		// The spinner turns at each draw, not on a timer of the
 		// library's own.
 		progressbar.OptionSetSpinnerChangeInterval(0),
-		// The text carries the elapsed time and the time remaining.
+		// The text carries the elapsed time and the ETA.
 		progressbar.OptionSetElapsedTime(false),
 		progressbar.OptionSetPredictTime(false),
 	)
-	p.widest = 0
-}
-
-// percentBar returns the percent and the bar that end the text of a
-// phase with an exact total, as "  25% |██        |": the bar's
-// barWidth columns fill in proportion to the items done. A count past
-// the total, as when a scan adds records while trees reads them, shows
-// as 100%. p.mu must be held.
-func (p *progress) percentBar() string {
-	done := min(float64(p.count)/float64(p.total), 1)
-	filled := strings.Repeat(barCell, int(done*barWidth))
-
-	return fmt.Sprintf("%4.0f%% |%-*s|", done*percentScale, barWidth, filled)
+	p.withBar, p.widest = withBar, 0
 }
 
 // setTotal gives a phase that started without a total its total, once
-// it is known. The rate, the time remaining and the time with no item
-// completed count from then on: the time spent waiting for the total
-// says nothing about how fast items go.
+// it is known. The rate, the ETA and the time with no item completed
+// count from then on: the time spent waiting for the total says nothing
+// about how fast items go.
 func (p *progress) setTotal(total int64) {
 	if p == nil {
 		return
@@ -426,26 +438,22 @@ func (p *progress) finish() {
 // line formats the phase's progress as of now in at most room columns,
 // as
 //
-//	[3/4] hash: [1234/5000] 25%, 300 files/s, elapsed 4s, remain 13s
+//	[3/5] hash: [1234/5000] 25%, 300 files/s, elapsed 4s, eta 13s
 //
-// where "files" is the phase's unit. A phase with no total shows the
-// items done instead, or what it waits for. The rate is that since the
-// first draw in drawn, and the time remaining comes from the rate since
-// the count started. Once no item has been completed for stallTime, the
-// rate, which would read 0, gives way to the word "stalled" and where
-// the phase waits, as "stalled disk/db".
+// where "files" is the phase's unit, without the percent when percent
+// is false, as before the library's bar, which shows its own. A phase
+// with no total shows the items done instead, or what it waits for. The
+// rate is that since the first draw in drawn, and the ETA comes from
+// the rate since the count started. Once no item has been completed for
+// stallTime, the rate, which would read 0, gives way to the word
+// "stalled" and where the phase waits, as "stalled disk/db".
 //
-// When bar is true, as on a terminal, a phase with an exact total ends
-// the line with its percent and bar, in place of the percent after its
-// count. A total of 0 leaves the bar nothing to fill.
-//
-// The phase and its place, the progress, the elapsed time and the time
-// remaining are kept whole. A line wider than room first leaves out the
-// rate, the words of a stalled phase, or what the phase waits for. Next
-// it leaves out the bar. Only if it is still wider is it cut at room.
-// Every part but the bar is ASCII, so its length is its width in
-// columns. p.mu must be held.
-func (p *progress) line(now time.Time, room int, bar bool) string {
+// The phase and its place, the progress, the elapsed time and the ETA
+// are kept whole. A line wider than room leaves out the rate, the words
+// of a stalled phase, or what the phase waits for; only if it is still
+// wider is it cut at room. Every part is ASCII, so its length is its
+// width in columns. p.mu must be held.
+func (p *progress) line(now time.Time, room int, percent bool) string {
 	elapsed := now.Sub(p.start).Round(time.Second)
 
 	// head and tail hold the parts kept whole; extra, between them, is
@@ -454,41 +462,21 @@ func (p *progress) line(now time.Time, room int, bar bool) string {
 
 	if p.total < 0 && p.waitingFor != "" {
 		head, extra = p.label+": ", p.waitingFor+", "
-		tail = fmt.Sprintf("elapsed %s, remain unknown", elapsed)
+		tail = fmt.Sprintf("elapsed %s, eta unknown", elapsed)
 	} else {
 		since := p.drawn[0]
 		rate := perSecond(p.count-since.count, now.Sub(since.at))
 		average := perSecond(p.count, now.Sub(p.rateStart))
 
-		head = p.label + ": " + p.itemsDone(true) + ", "
+		head = p.label + ": " + p.itemsDone(percent) + ", "
 		extra = fmt.Sprintf("%.0f %s/s, ", rate, p.unit)
-		tail = fmt.Sprintf("elapsed %s, remain %s", elapsed, p.remain(average))
+		tail = fmt.Sprintf("elapsed %s, eta %s", elapsed, p.eta(average))
 
 		if now.Sub(p.lastItem) >= stallTime {
 			extra = "stalled " + p.stalledOn + ", "
 		}
 	}
 
-	if bar && p.total > 0 && !p.estimate {
-		// Beside the bar, which shows the percent, the count shows none.
-		// The line is padded to the room the bar leaves it, so the bar
-		// stays at room's right edge however long the line is.
-		beside := room - barColumns
-		barHead := p.label + ": " + p.itemsDone(false) + ", "
-
-		switch {
-		case len(barHead+extra+tail) <= beside:
-			return fmt.Sprintf("%-*s%s", beside, barHead+extra+tail,
-				p.percentBar())
-		case len(barHead+tail) <= beside:
-			return fmt.Sprintf("%-*s%s", beside, barHead+tail, p.percentBar())
-		}
-
-		// The bar gives way. The rate, or the words of a stalled phase,
-		// gave way before it and stay out.
-		extra = ""
-	}
-
 	full, kept := head+extra+tail, head+tail
 
 	switch {
@@ -538,10 +526,10 @@ func (p *progress) itemsDone(percent bool) string {
 	return fmt.Sprintf("%s %.0f%%", done, pct)
 }
 
-// remain returns the time the phase has left at rate items a second, or
+// eta returns the time the phase has left at rate items a second, or
 // "unknown": with no total, before the first item, and once the count
 // passes an estimate. p.mu must be held.
-func (p *progress) remain(rate float64) string {
+func (p *progress) eta(rate float64) string {
 	switch {
 	case p.total < 0, p.estimate && p.count > p.total:
 		return "unknown"
@@ -551,8 +539,8 @@ func (p *progress) remain(rate float64) string {
 		return "unknown"
 	}
 
-	left := time.Duration(
+	remaining := time.Duration(
 		float64(p.total-p.count) / rate * float64(time.Second))
 
-	return left.Round(time.Second).String()
+	return remaining.Round(time.Second).String()
 }

progress_test.go

@@ -23,7 +23,7 @@ const testRedraw = time.Millisecond
 const testDeadline = 5 * time.Second
 
 // hashStalledOn is where the hash phase says it waits once it has
-// stalled, as hashPhase gives it.
+// stalled, as readRuns gives it.
 const hashStalledOn = "disk/db"
 
 // testClock is a clock a test moves by hand, for a display that reads
@@ -117,38 +117,38 @@ func TestProgressLine(t *testing.T) {
 			label: scanPhase("load"), total: -1,
 			waitingFor: countingRecords,
 		},
-		want: "[1/4] load: counting the records, elapsed 10s, remain unknown",
+		want: "[1/5] load: counting the records, elapsed 10s, eta unknown",
 	}, {
 		p: &progress{
 			label: scanPhase("hash"), unit: scanUnit, total: 100, count: 20,
 		},
-		want: "[3/4] hash: [20/100] 20%, 2 files/s, elapsed 10s, remain 40s",
+		want: "[3/5] hash: [20/100] 20%, 2 files/s, elapsed 10s, eta 40s",
 	}, {
 		p:    &progress{label: scanPhase("hash"), unit: scanUnit, total: 100},
-		want: "[3/4] hash: [0/100] 0%, 0 files/s, elapsed 10s, remain unknown",
+		want: "[3/5] hash: [0/100] 0%, 0 files/s, elapsed 10s, eta unknown",
 	}, {
 		p:    &progress{label: scanPhase("update"), unit: scanUnit, total: 0},
-		want: "[4/4] update: [0/0] 100%, 0 files/s, elapsed 10s, remain 0s",
+		want: "[4/5] update: [0/0] 100%, 0 files/s, elapsed 10s, eta 0s",
 	}, {
 		p: &progress{
 			label: scanPhase("walk"), unit: scanUnit, total: 100,
 			estimate: true, count: 20,
 		},
-		want: "[2/4] walk: [20/~100] 20%, 2 files/s, elapsed 10s, remain 40s",
+		want: "[2/5] walk: [20/~100] 20%, 2 files/s, elapsed 10s, eta 40s",
 	}, {
 		// Past the estimate the walk cannot tell how long it has left.
 		p: &progress{
 			label: scanPhase("walk"), unit: scanUnit, total: 100,
 			estimate: true, count: 120,
 		},
-		want: "[2/4] walk: [120/~100] 120%, 12 files/s, elapsed 10s, " +
-			"remain unknown",
+		want: "[2/5] walk: [120/~100] 120%, 12 files/s, elapsed 10s, " +
+			"eta unknown",
 	}, {
 		// A first scan's walk has no estimate.
 		p: &progress{
 			label: scanPhase("walk"), unit: scanUnit, total: -1, count: 20,
 		},
-		want: "[2/4] walk: 20 files, 2 files/s, elapsed 10s, remain unknown",
+		want: "[2/5] walk: 20 files, 2 files/s, elapsed 10s, eta unknown",
 	}, {
 		// The rate is in what the phase counts.
 		p: &progress{
@@ -156,14 +156,14 @@ func TestProgressLine(t *testing.T) {
 			count: 20,
 		},
 		want: "[3/4] group: [20/100] 20%, 2 directories/s, elapsed 10s, " +
-			"remain 40s",
+			"eta 40s",
 	}}
 
 	for _, tc := range cases {
 		tc.p.start, tc.p.rateStart, tc.p.lastItem = ago, ago, now
 		tc.p.drawn = []drawnCount{{at: ago}}
 
-		if got := tc.p.line(now, math.MaxInt, false); got != tc.want {
+		if got := tc.p.line(now, math.MaxInt, true); got != tc.want {
 			t.Errorf("line = %q, want %q", got, tc.want)
 		}
 	}
@@ -184,9 +184,9 @@ func TestLineFitsRoom(t *testing.T) {
 		start: ago, rateStart: ago, lastItem: now,
 		drawn: []drawnCount{{at: ago}},
 	}
-	load := &progress{
-		label: scanPhase("load"), total: -1,
-		waitingFor: countingRecords, start: ago, rateStart: ago,
+	content := &progress{
+		label: scanPhase("content"), total: -1,
+		waitingFor: "searching the database", start: ago, rateStart: ago,
 	}
 
 	started := now.Add(-50 * time.Second)
@@ -198,49 +198,48 @@ func TestLineFitsRoom(t *testing.T) {
 	}
 
 	cases := []struct {
-		p    *progress
-		room int
-		bar  bool
-		want string
+		p       *progress
+		room    int
+		percent bool
+		want    string
 	}{{
-		p: hash, room: 60,
-		want: "[3/4] hash: [20/100] 20%, 2 files/s, elapsed 10s, remain 40s",
+		p: hash, room: 57, percent: true,
+		want: "[3/5] hash: [20/100] 20%, 2 files/s, elapsed 10s, eta 40s",
 	}, {
-		p: hash, room: 59,
-		want: "[3/4] hash: [20/100] 20%, elapsed 10s, remain 40s",
+		p: hash, room: 56, percent: true,
+		want: "[3/5] hash: [20/100] 20%, elapsed 10s, eta 40s",
 	}, {
-		p: hash, room: 48,
-		want: "[3/4] hash: [20/100] 20%, elapsed 10s, remain 40",
+		p: hash, room: 45, percent: true,
+		want: "[3/5] hash: [20/100] 20%, elapsed 10s, eta 40",
 	}, {
-		// The bar shows the percent.
-		p: hash, room: 74, bar: true,
-		want: "[3/4] hash: [20/100], 2 files/s, elapsed 10s, remain 40s" +
-			"  20% |██        |",
+		// Before the library's bar, which shows the percent.
+		p: hash, room: 57, percent: false,
+		want: "[3/5] hash: [20/100], 2 files/s, elapsed 10s, eta 40s",
 	}, {
-		p: load, room: 43,
-		want: "[1/4] load: elapsed 10s, remain unknown",
+		p: content, room: 40, percent: true,
+		want: "[5/5] content: elapsed 10s, eta unknown",
 	}, {
-		p: stalled, room: 68,
-		want: "[3/4] hash: [20/100] 20%, stalled disk/db, elapsed 50s, " +
-			"remain 3m20s",
+		p: stalled, room: 65, percent: true,
+		want: "[3/5] hash: [20/100] 20%, stalled disk/db, elapsed 50s, " +
+			"eta 3m20s",
 	}, {
-		p: stalled, room: 67,
-		want: "[3/4] hash: [20/100] 20%, elapsed 50s, remain 3m20s",
+		p: stalled, room: 64, percent: true,
+		want: "[3/5] hash: [20/100] 20%, elapsed 50s, eta 3m20s",
 	}}
 
 	for _, tc := range cases {
-		if got := tc.p.line(now, tc.room, tc.bar); got != tc.want {
-			t.Errorf("line(%d, %t) = %q, want %q", tc.room, tc.bar, got,
-				tc.want)
+		if got := tc.p.line(now, tc.room, tc.percent); got != tc.want {
+			t.Errorf("line(%d, %t) = %q, want %q",
+				tc.room, tc.percent, got, tc.want)
 		}
 	}
 }
 
 // TestSetTotalStartsRate checks that setTotal starts a phase's rate,
-// its time remaining and its time with no record read from when the
-// total becomes known, not from when the phase started waiting for it:
-// after 20 seconds of waiting for the total, the phase has not stalled 5
-// seconds after it, and has 10 seconds after it with no record read.
+// its ETA and its time with no record read from when the total becomes
+// known, not from when the phase started waiting for it: after 20
+// seconds of waiting for the total, the phase has not stalled 5 seconds
+// after it, and has 10 seconds after it with no record read.
 func TestSetTotalStartsRate(t *testing.T) {
 	t.Parallel()
 
@@ -256,15 +255,15 @@ func TestSetTotalStartsRate(t *testing.T) {
 
 	clock.Add(5 * time.Second)
 
-	want := "[1/4] load: [0/100] 0%, 0 files/s, elapsed 25s, remain unknown"
-	if got := p.line(clock.Now(), math.MaxInt, false); got != want {
+	want := "[1/5] load: [0/100] 0%, 0 files/s, elapsed 25s, eta unknown"
+	if got := p.line(clock.Now(), math.MaxInt, true); got != want {
 		t.Errorf("line = %q, want %q", got, want)
 	}
 
 	clock.Add(5 * time.Second)
 
-	want = "[1/4] load: [0/100] 0%, stalled db, elapsed 30s, remain unknown"
-	if got := p.line(clock.Now(), math.MaxInt, false); got != want {
+	want = "[1/5] load: [0/100] 0%, stalled db, elapsed 30s, eta unknown"
+	if got := p.line(clock.Now(), math.MaxInt, true); got != want {
 		t.Errorf("line = %q, want %q", got, want)
 	}
 
@@ -273,8 +272,8 @@ func TestSetTotalStartsRate(t *testing.T) {
 		p.increment()
 	}
 
-	want = "[1/4] load: [20/100] 20%, 2 files/s, elapsed 30s, remain 40s"
-	if got := p.line(clock.Now(), math.MaxInt, false); got != want {
+	want = "[1/5] load: [20/100] 20%, 2 files/s, elapsed 30s, eta 40s"
+	if got := p.line(clock.Now(), math.MaxInt, true); got != want {
 		t.Errorf("line = %q, want %q", got, want)
 	}
 }
@@ -317,9 +316,9 @@ func TestPlainProgressPrintsAtStartAndEnd(t *testing.T) {
 
 	lines := strings.Split(strings.TrimSuffix(stderr(), "\n"), "\n")
 
-	want := "[3/4] hash: [0/1000] 0%, 0 files/s, elapsed 0s, remain unknown"
+	want := "[3/5] hash: [0/1000] 0%, 0 files/s, elapsed 0s, eta unknown"
 	if len(lines) != 2 || lines[0] != want ||
-		!strings.HasPrefix(lines[1], "[3/4] hash: [1000/1000] 100%, ") {
+		!strings.HasPrefix(lines[1], "[3/5] hash: [1000/1000] 100%, ") {
 		t.Errorf("stderr lines = %q, want %q, then the line at 1000",
 			lines, want)
 	}
@@ -337,7 +336,7 @@ func TestPlainProgressPrintsWhileWaiting(t *testing.T) {
 	}, nil, testRedraw, time.Now)
 
 	awaitOutput(t, stderr,
-		"[1/4] load: counting the records, elapsed 0s, remain unknown\n", 3)
+		"[1/5] load: counting the records, elapsed 0s, eta unknown\n", 3)
 	p.finish()
 }
 
@@ -367,23 +366,23 @@ func TestPlainProgressStalledProducer(t *testing.T) {
 
 	clock.Add(5 * time.Second)
 	awaitOutput(t, stderr,
-		"[3/4] hash: [20/100] 20%, 4 files/s, elapsed 5s, remain 20s\n", 3)
+		"[3/5] hash: [20/100] 20%, 4 files/s, elapsed 5s, eta 20s\n", 3)
 
 	clock.Add(time.Second)
 	awaitOutput(t, stderr,
-		"[3/4] hash: [20/100] 20%, 0 files/s, elapsed 6s, remain 24s\n", 3)
+		"[3/5] hash: [20/100] 20%, 0 files/s, elapsed 6s, eta 24s\n", 3)
 
 	clock.Add(4 * time.Second)
 	awaitOutput(t, stderr,
-		"[3/4] hash: [20/100] 20%, stalled disk/db, elapsed 10s, remain 40s\n",
+		"[3/5] hash: [20/100] 20%, stalled disk/db, elapsed 10s, eta 40s\n",
 		3)
 }
 
 // TestPlainProgressRateAfterStall draws a phase's plain line by hand, a
 // little over plainInterval after the line before, as a late tick
 // does, through a stall and a burst of files after it: the rate covers
-// the files read since the line before, while the time remaining comes
-// from the phase's average.
+// the files read since the line before, while the ETA comes from the
+// phase's average.
 //
 //nolint:paralleltest // captureStderr replaces the process-wide os.Stderr
 func TestPlainProgressRateAfterStall(t *testing.T) {
@@ -411,10 +410,10 @@ func TestPlainProgressRateAfterStall(t *testing.T) {
 	p.finish()
 
 	want := []string{
-		"[3/4] hash: [0/1000] 0%, 0 files/s, elapsed 0s, remain unknown",
-		"[3/4] hash: [0/1000] 0%, 0 files/s, elapsed 5s, remain unknown",
-		"[3/4] hash: [0/1000] 0%, stalled disk/db, elapsed 10s, remain unknown",
-		"[3/4] hash: [100/1000] 10%, 20 files/s, elapsed 15s, remain 2m15s",
+		"[3/5] hash: [0/1000] 0%, 0 files/s, elapsed 0s, eta unknown",
+		"[3/5] hash: [0/1000] 0%, 0 files/s, elapsed 5s, eta unknown",
+		"[3/5] hash: [0/1000] 0%, stalled disk/db, elapsed 10s, eta unknown",
+		"[3/5] hash: [100/1000] 10%, 20 files/s, elapsed 15s, eta 2m15s",
 	}
 
 	lines := strings.Split(strings.TrimSuffix(stderr(), "\n"), "\n")
@@ -427,8 +426,8 @@ func TestPlainProgressRateAfterStall(t *testing.T) {
 // redrawInterval, as a terminal does, through a stall of stallTime and
 // a burst of files after it: the rate covers the files read over the
 // last rateWindow, and falls to 0 once the burst is older than that,
-// while the time remaining comes from the phase's average. Plain lines
-// show each draw.
+// while the ETA comes from the phase's average. Plain lines show each
+// draw.
 //
 //nolint:paralleltest // captureStderr replaces the process-wide os.Stderr
 func TestProgressRateAfterStallRedrawn(t *testing.T) {
@@ -458,8 +457,8 @@ func TestProgressRateAfterStallRedrawn(t *testing.T) {
 	redraw(rateWindow + redrawInterval)
 	p.finish()
 
-	want := "[3/4] hash: [50/1000] 5%, 10 files/s, elapsed 15s, remain 4m45s\n" +
-		"[3/4] hash: [50/1000] 5%, 0 files/s, elapsed 15s, remain 4m47s\n"
+	want := "[3/5] hash: [50/1000] 5%, 10 files/s, elapsed 15s, eta 4m45s\n" +
+		"[3/5] hash: [50/1000] 5%, 0 files/s, elapsed 15s, eta 4m47s\n"
 	if !strings.Contains(stderr(), want) {
 		t.Errorf("stderr = %q, want the lines %q", stderr(), want)
 	}
@@ -481,10 +480,10 @@ func lastFrame(out string) string {
 }
 
 // TestTerminalRedrawsWhileWaiting checks that the terminal display of a
-// phase, with a bar or without, keeps being drawn while the phase waits
-// for its next item, with the elapsed time as of now, and shows every
-// item completed before the wait. The terminal is 120 columns wide, so
-// the hash phase's display has room for its bar.
+// phase, spinner or bar, keeps being drawn while the phase waits for its
+// next item, with the elapsed time as of now, and shows every item
+// completed before the wait. stderr is not a terminal here, so the
+// displays take it to be fallbackWidth wide.
 //
 //nolint:paralleltest // captureStderr replaces the process-wide os.Stderr
 func TestTerminalRedrawsWhileWaiting(t *testing.T) {
@@ -507,8 +506,7 @@ func TestTerminalRedrawsWhileWaiting(t *testing.T) {
 	for _, tc := range cases {
 		before := len(stderr())
 		since := func() string { return stderr()[before:] }
-		p := startProgress(tc.params, func() int { return 120 }, testRedraw,
-			time.Now)
+		p := startProgress(tc.params, terminalWidth, testRedraw, time.Now)
 
 		for range 50 {
 			p.increment()
@@ -554,13 +552,13 @@ func drawLate(stderr func() string, params progressParams, width int,
 	return stderr()[before:]
 }
 
-// TestTerminalLinesKeepTimeRemaining checks the line each display shows
-// on an 80-column terminal at a large scan's counts and times, and the
-// line of trees' read phase at the same counts: the rate is left out,
-// so that the elapsed time and the time remaining stay whole.
+// TestTerminalLinesKeepETA checks the line each display shows on an
+// 80-column terminal at a large scan's counts and times, and the line
+// of trees' read phase at the same counts: the rate is left out, so
+// that the elapsed time and the ETA stay whole.
 //
 //nolint:paralleltest // captureStderr replaces the process-wide os.Stderr
-func TestTerminalLinesKeepTimeRemaining(t *testing.T) {
+func TestTerminalLinesKeepETA(t *testing.T) {
 	stderr := captureStderr(t)
 
 	cases := []struct {
@@ -572,20 +570,26 @@ func TestTerminalLinesKeepTimeRemaining(t *testing.T) {
 			label: scanPhase("walk"), unit: scanUnit, total: 1200000,
 			estimate: true,
 		},
-		want: "[2/4] walk: [1234567/~1200000] 103%, elapsed 2h30m0s, " +
-			"remain unknown",
+		want: "[2/5] walk: [1234567/~1200000] 103%, elapsed 2h30m0s, " +
+			"eta unknown",
 	}, {
 		params: progressParams{
 			label: scanPhase("hash"), unit: scanUnit, total: 9876543,
 		},
-		want: "[3/4] hash: [1234567/9876543] 12%, elapsed 2h30m0s, " +
-			"remain 17h30m0s",
+		want: "[3/5] hash: [1234567/9876543] 12%, elapsed 2h30m0s, " +
+			"eta 17h30m0s",
+	}, {
+		params: progressParams{
+			label: scanPhase("content"), unit: scanUnit, total: 9876543,
+		},
+		want: "[5/5] content: [1234567/9876543] 12%, elapsed 2h30m0s, " +
+			"eta 17h30m0s",
 	}, {
 		params: progressParams{
 			label: treesPhase("read"), unit: "records", total: 9876543,
 		},
 		want: "[2/4] read: [1234567/9876543] 12%, elapsed 2h30m0s, " +
-			"remain 17h30m0s",
+			"eta 17h30m0s",
 	}}
 
 	for _, tc := range cases {
@@ -596,32 +600,30 @@ func TestTerminalLinesKeepTimeRemaining(t *testing.T) {
 	}
 }
 
-// TestTerminalStalledLines draws every phase's line once the phase has
-// stalled, its last item done 42 seconds before. At an ordinary scan's
-// counts and times, 12345 of 45678 items done four and a half minutes
-// in, on a terminal 100 columns wide, the line shows where the phase
-// waits whole, beside the phase, progress, elapsed time and time
-// remaining. At a large scan's, 1234567 of 9876543 two and a half hours
-// in, on an 80-column terminal, those four still show whole, as the
-// words give way first where they do not fit.
+// TestTerminalStalledLines draws every phase's line on an 80-column
+// terminal once the phase has stalled, its last item done 42 seconds
+// before. At an ordinary scan's counts and times, 12345 of 45678 items
+// done four and a half minutes in, the line shows where the phase waits
+// whole, beside the phase, progress, elapsed time and ETA. At a large
+// scan's, 1234567 of 9876543 two and a half hours in, those four still
+// show whole, as the words give way first where they do not fit.
 //
 //nolint:paralleltest // captureStderr replaces the process-wide os.Stderr
 func TestTerminalStalledLines(t *testing.T) {
 	stderr := captureStderr(t)
 
-	// drawStalled draws the display params describes on a terminal width
-	// columns wide as it starts and once more as it ends, with count of
-	// total items done elapsed into the phase, and returns what the
-	// terminal shows.
-	drawStalled := func(params progressParams, width int, total,
-		count int64, elapsed time.Duration,
+	// drawStalled draws the display params describes as it starts and
+	// once more as it ends, with count of total items done elapsed into
+	// the phase, and returns what the terminal shows.
+	drawStalled := func(params progressParams, total, count int64,
+		elapsed time.Duration,
 	) string {
 		before := len(stderr())
 		clock := &testClock{now: time.Now()}
 		params.total = total
 
 		// No timed draws come between the two.
-		p := startProgress(params, func() int { return width }, time.Hour,
+		p := startProgress(params, func() int { return 80 }, time.Hour,
 			clock.Now)
 
 		clock.Add(elapsed - 42*time.Second)
@@ -641,6 +643,9 @@ func TestTerminalStalledLines(t *testing.T) {
 		{label: scanPhase("walk"), estimate: true, stalledOn: "disk"},
 		{label: scanPhase("hash"), stalledOn: hashStalledOn},
 		{label: scanPhase("update"), stalledOn: "db"},
+		// The content phase's checks and reads, then its last write.
+		{label: scanPhase("content"), stalledOn: "disk/db"},
+		{label: scanPhase("content"), stalledOn: "db"},
 		{label: treesPhase("read"), stalledOn: "db"},
 		{label: treesPhase("group"), stalledOn: "cpu"},
 		{label: treesPhase("write"), stalledOn: "out"},
@@ -653,22 +658,19 @@ func TestTerminalStalledLines(t *testing.T) {
 			approx = "~"
 		}
 
-		// The percent is in the line, or beside the bar.
-		shown := drawStalled(params, 100, 45678, 12345,
+		shown := drawStalled(params, 45678, 12345,
 			4*time.Minute+30*time.Second)
-		for _, want := range []string{
-			params.label + ": [12345/" + approx + "45678]",
-			", stalled " + params.stalledOn + ", elapsed 4m30s, remain 12m9s",
-		} {
-			if !strings.Contains(shown, want) {
-				t.Errorf("terminal shows %q, want %q", shown, want)
-			}
+		want := params.label + ": [12345/" + approx + "45678] 27%, stalled " +
+			params.stalledOn + ", elapsed 4m30s, eta 12m9s"
+
+		if !strings.Contains(shown, want) {
+			t.Errorf("terminal shows %q, want %q", shown, want)
 		}
 
-		shown = drawStalled(params, 80, 9876543, 1234567, 150*time.Minute)
+		shown = drawStalled(params, 9876543, 1234567, 150*time.Minute)
 		for _, want := range []string{
 			params.label + ": [1234567/" + approx + "9876543] 12%, ",
-			", elapsed 2h30m0s, remain 17h30m0s",
+			", elapsed 2h30m0s, eta 17h30m0s",
 		} {
 			if !strings.Contains(shown, want) {
 				t.Errorf("terminal shows %q, want %q", shown, want)
@@ -691,7 +693,7 @@ func TestTerminalLinesFitWidth(t *testing.T) {
 	for _, width := range []int{120, 100, 80, 72, 60, 50, 40} {
 		for _, total := range []int64{9876543, 20000} {
 			params := progressParams{
-				label: scanPhase("update"), unit: scanUnit, total: total,
+				label: scanPhase("content"), unit: scanUnit, total: total,
 			}
 			out := drawLate(stderr, params, width, total/8)
 
@@ -713,164 +715,13 @@ func TestTerminalLinesFitWidth(t *testing.T) {
 	}
 }
 
-// TestTerminalLinesStartWithSpinner draws a display with no total and
-// one with a bar, two and a half hours into the phase, on a terminal 120
-// columns wide. Each line must start with the library's spinner in the
-// first column, then a space and the phase's label.
-//
-//nolint:paralleltest // captureStderr replaces the process-wide os.Stderr
-func TestTerminalLinesStartWithSpinner(t *testing.T) {
-	stderr := captureStderr(t)
-
-	for _, params := range []progressParams{
-		{label: scanPhase("walk"), unit: scanUnit, total: -1},
-		{label: scanPhase("hash"), unit: scanUnit, total: 9876543},
-	} {
-		shown := lastFrame(drawLate(stderr, params, 120, 1234567))
-		spinner, rest, _ := strings.Cut(shown, " ")
-
-		if utf8.RuneCountInString(spinner) != 1 ||
-			!strings.HasPrefix(rest, params.label+": ") {
-			t.Errorf("terminal shows %q, want the spinner, a space and %q",
-				shown, params.label)
-		}
-
-		if params.total > 0 && !strings.Contains(shown, "% |") {
-			t.Errorf("terminal shows %q, want a bar", shown)
-		}
-	}
-}
-
-// TestTerminalBarStaysAtRightEdge draws the hash phase's display two
-// and a half hours in, at two counts whose lines differ in length, on
-// terminals 110 and 120 columns wide. The bar is partly filled at the
-// first count and full at the second. It must start the same number of
-// columns from the terminal's right edge each time, and end the same
-// number of columns from it: a line that grows or shrinks, as its time
-// remaining does, never moves the bar, and nor do the bar's filled
-// cells.
-//
-//nolint:paralleltest // captureStderr replaces the process-wide os.Stderr
-func TestTerminalBarStaysAtRightEdge(t *testing.T) {
-	stderr := captureStderr(t)
-	params := progressParams{
-		label: scanPhase("hash"), unit: scanUnit, total: 9876543,
-	}
-
-	widths := []int{110, 120}
-	counts := []int64{1234567, 9876543}
-	startFromEdge := make([]int, 0, len(widths)*len(counts))
-	endFromEdge := make([]int, 0, len(widths)*len(counts))
-
-	for _, width := range widths {
-		for _, count := range counts {
-			shown := lastFrame(drawLate(stderr, params, width, count))
-
-			beforeBar, _, found := strings.Cut(shown, "% |")
-			if !found {
-				t.Fatalf("terminal %d wide shows %q, want a bar", width, shown)
-			}
-
-			// The bar ends with the last "|".
-			throughBar := shown[:strings.LastIndex(shown, "|")+1]
-
-			startFromEdge = append(startFromEdge,
-				width-utf8.RuneCountInString(beforeBar))
-			endFromEdge = append(endFromEdge,
-				width-utf8.RuneCountInString(throughBar))
-		}
-	}
-
-	if slices.Min(startFromEdge) != slices.Max(startFromEdge) {
-		t.Errorf("bar starts %v columns from the right edge, want the same "+
-			"every time", startFromEdge)
-	}
-
-	if slices.Min(endFromEdge) != slices.Max(endFromEdge) {
-		t.Errorf("bar ends %v columns from the right edge, want the same "+
-			"every time", endFromEdge)
-	}
-}
-
-// TestTerminalRateGivesWayBeforeBar draws the hash phase's display two
-// and a half hours in. On a terminal 90 columns wide the line fits
-// beside the bar without its rate, but not with it: the bar is drawn
-// and the rate is not. On a terminal 85 columns wide the line does not
-// fit beside the bar even without its rate: neither is drawn, though
-// the rate would fit where the bar was.
-//
-//nolint:paralleltest // captureStderr replaces the process-wide os.Stderr
-func TestTerminalRateGivesWayBeforeBar(t *testing.T) {
-	stderr := captureStderr(t)
-	params := progressParams{
-		label: scanPhase("hash"), unit: scanUnit, total: 9876543,
-	}
-
-	shown := lastFrame(drawLate(stderr, params, 90, 1234567))
-	if !strings.Contains(shown, "% |") || strings.Contains(shown, "files/s") {
-		t.Errorf("terminal 90 wide shows %q, want the bar and no rate", shown)
-	}
-
-	shown = lastFrame(drawLate(stderr, params, 85, 1234567))
-	if strings.Contains(shown, "% |") || strings.Contains(shown, "files/s") {
-		t.Errorf("terminal 85 wide shows %q, want neither bar nor rate", shown)
-	}
-}
-
-// TestTerminalSpinnerTurnsBesideBar draws the hash phase's display, its
-// bar partly filled, several times on a terminal 120 columns wide. The
-// spinner must turn at every draw. A filled cell of the bar takes one
-// column but three bytes. A line measured in bytes would seem too wide
-// for the terminal, and every draw would start the display over, its
-// spinner included.
-//
-//nolint:paralleltest // captureStderr replaces the process-wide os.Stderr
-func TestTerminalSpinnerTurnsBesideBar(t *testing.T) {
-	stderr := captureStderr(t)
-	params := progressParams{
-		label: scanPhase("hash"), unit: scanUnit, total: 9876543,
-	}
-
-	// No timed draws: the test draws.
-	p := startProgress(params, func() int { return 120 }, time.Hour,
-		time.Now)
-
-	p.mu.Lock()
-	p.count = 1234567
-	p.mu.Unlock()
-
-	const draws = 4
-
-	spinners := make([]string, 0, draws)
-
-	for range draws {
-		before := len(stderr())
-
-		p.draw()
-
-		spinner, _, _ := strings.Cut(lastFrame(stderr()[before:]), " ")
-		spinners = append(spinners, spinner)
-	}
-
-	p.finish()
-
-	for i := 1; i < len(spinners); i++ {
-		if spinners[i] == spinners[i-1] {
-			t.Errorf("spinners at successive draws are %q, want each to "+
-				"differ from the one before", spinners)
-
-			break
-		}
-	}
-}
-
 // TestTerminalNarrowedRedrawsInPlace draws a large scan's display, two
 // and a half hours into the phase, on a terminal 120 columns wide, then
 // makes the terminal narrower than that line and draws it again a few
 // times. Nothing written after that, the erase before each redraw
 // included, may reach the narrower terminal's last column: it would
-// wrap, and every redraw would leave a line behind. At the narrower
-// width the hash phase's bar gives way.
+// wrap, and every redraw would leave a line behind. At these widths the
+// spinner stays a spinner and the bar gives way to the spinner.
 //
 //nolint:paralleltest // captureStderr replaces the process-wide os.Stderr
 func TestTerminalNarrowedRedrawsInPlace(t *testing.T) {
@@ -888,7 +739,7 @@ func TestTerminalNarrowedRedrawsInPlace(t *testing.T) {
 			progressParams{
 				label: scanPhase("hash"), unit: scanUnit, total: 9876543,
 			},
-			80,
+			90,
 		},
 	}
 
@@ -928,10 +779,10 @@ func TestTerminalNarrowedRedrawsInPlace(t *testing.T) {
 	}
 }
 
-// TestProgressWarningsOnOwnLines drives the terminal displays, with a
-// bar and without, through a run of warnings with no items between
-// them, as when the walk meets many unreadable paths, for many redraws:
-// every warning must land on a line of its own, never inside a redraw.
+// TestProgressWarningsOnOwnLines drives the terminal displays, spinner
+// and bar, through a run of warnings with no items between them, as when
+// the walk meets many unreadable paths, for many redraws: every warning
+// must land on a line of its own, never inside a redraw.
 //
 //nolint:paralleltest // captureStderr replaces the process-wide os.Stderr
 func TestProgressWarningsOnOwnLines(t *testing.T) {
@@ -977,12 +828,11 @@ func TestProgressWarningsOnOwnLines(t *testing.T) {
 	}
 }
 
-// TestProgressWriterRowsOnOwnLines drives the terminal displays, with a
-// bar and without, through a run of rows written through the display's
+// TestProgressWriterRowsOnOwnLines drives the terminal displays,
+// spinner and bar, through a run of rows written through the display's
 // writer to the same terminal, as stdout is in a plain "sfdupes trees",
 // each written out at once, for many redraws: the terminal must show
-// every row whole, in order, on a line of its own. The terminal is 120
-// columns wide, so the write phase's display has room for its bar.
+// every row whole, in order, on a line of its own.
 //
 //nolint:paralleltest // captureStderr replaces the process-wide os.Stderr
 func TestProgressWriterRowsOnOwnLines(t *testing.T) {
@@ -999,8 +849,7 @@ func TestProgressWriterRowsOnOwnLines(t *testing.T) {
 	var want []string
 
 	for _, params := range cases {
-		p := startProgress(params, func() int { return 120 }, testRedraw,
-			time.Now)
+		p := startProgress(params, terminalWidth, testRedraw, time.Now)
 		out := p.writer(os.Stderr)
 
 		// No pause between rows: one is garbled only if a redraw lands

report.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"context"
-	"crypto/sha256"
 	"database/sql"
 	"fmt"
 	"io"
@@ -21,16 +20,14 @@ const minGroupSize = 2
 
 // scanRec is one file record from the database. The signature (size,
 // head, tail, content) is the duplicate key; mtime is informational
-// only and used by scan for change detection. diskSize is the bytes the
-// file takes on disk, which trees adds up.
+// only and used by scan for change detection.
 type scanRec struct {
-	size     int64
-	diskSize int64
-	mtime    time.Time
-	head     [sha256.Size]byte
-	tail     [sha256.Size]byte
-	content  [sha256.Size]byte
-	path     string
+	size    int64
+	mtime   time.Time
+	head    string
+	tail    string
+	content string
+	path    string
 }
 
 // reportPhase names one phase of report with its place among all of
@@ -47,11 +44,11 @@ func reportPhase(name string) string {
 // problem, including a missing database, is fatal.
 //
 // The work runs in two phases, each under a progress display of its
-// own on stderr: open (open the database) and read (read the number of
-// records from the totals table, then read the records in signature
-// order, writing each size's duplicate groups to stdout once that size
-// is read; see readReport). Each display ends before the next phase
-// starts, and before an error is returned to be printed.
+// own on stderr: open (open the database) and read (count the records,
+// then read them in signature order, writing each size's duplicate
+// groups to stdout once that size is read; see readReport). Each
+// display ends before the next phase starts, and before an error is
+// returned to be printed.
 func runReport(ctx context.Context, stdout io.Writer) error {
 	dbPath, source, err := databasePath()
 	if err != nil {
@@ -172,6 +169,12 @@ type reportWriter struct {
 func (w *reportWriter) add(r scanRec) error {
 	w.records++
 
+	// A record without a content hash has unknown content (README
+	// "Database"), so it is never a duplicate.
+	if r.content == "" {
+		return nil
+	}
+
 	if r.size == w.sig.size && r.head == w.sig.head &&
 		r.tail == w.sig.tail && r.content == w.sig.content {
 		w.paths = append(w.paths, r.path)

report_test.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"bytes"
-	"crypto/sha256"
 	"database/sql"
 	"errors"
 	"fmt"
@@ -19,27 +18,14 @@ import (
 // awkwardDir is a directory name holding every byte the reports escape.
 const awkwardDir = "/d/\tone\ntwo\rthree\\four"
 
-// testHash returns a stand-in hash for a test record: the bytes of s,
-// then zeros. Stand-ins sort as their strings do, so a test can choose
-// the order in which report reads its records.
-func testHash(s string) [sha256.Size]byte {
-	var h [sha256.Size]byte
-
-	copy(h[:], s)
-
-	return h
-}
-
 // awkwardPairRecs is a duplicate pair in sibling directories /d/A and
 // awkwardDir. A raw tab sorts before "A" but its escaped form `\t`
 // sorts after it, so awkwardDir coming first shows that sorting uses
 // the raw path.
 func awkwardPairRecs() []scanRec {
-	h, tl, c := testHash("h"), testHash("t"), testHash("c")
-
 	return []scanRec{
-		{size: 5, diskSize: 4096, head: h, tail: tl, content: c, path: "/d/A/f"},
-		{size: 5, diskSize: 4096, head: h, tail: tl, content: c, path: awkwardDir + "/f"},
+		{size: 5, head: "h", tail: "t", content: "c", path: "/d/A/f"},
+		{size: 5, head: "h", tail: "t", content: "c", path: awkwardDir + "/f"},
 	}
 }
 
@@ -157,8 +143,8 @@ func TestReportStdoutFailsWhileReading(t *testing.T) {
 	recs := make([]scanRec, 2*ioBufSize/len(dir))
 	for i := range recs {
 		recs[i] = scanRec{
-			size: int64(i/2) + 1, head: testHash("h"), tail: testHash("t"),
-			content: testHash("c"), path: fmt.Sprintf("%s/%d", dir, i),
+			size: int64(i/2) + 1, head: "h", tail: "t", content: "c",
+			path: fmt.Sprintf("%s/%d", dir, i),
 		}
 	}
 
@@ -187,7 +173,7 @@ func TestReportStdoutFailsWhileReading(t *testing.T) {
 // reportOpenLine is the plain line of report's open phase when it opens
 // the database at once; it prints it as the phase starts and as it ends.
 const reportOpenLine = "[1/2] open: opening the database, elapsed 0s, " +
-	"remain unknown"
+	"eta unknown"
 
 // smokeReport is report's stdout for the smoke-test records.
 const smokeReport = "first\tdupe\tsize\n" +
@@ -225,7 +211,7 @@ func TestRunReportProgressNamesEachPhase(t *testing.T) {
 		"report: database " + path + " (from " + databaseEnv + ")",
 		reportOpenLine,
 		reportOpenLine,
-		"[2/2] read: counting the records, elapsed 0s, remain unknown",
+		"[2/2] read: counting the records, elapsed 0s, eta unknown",
 		"[2/2] read: [6/6] 100%, ",
 		"report: 6 records read, 2 duplicate groups, 4 dupe files, " +
 			"6.1 KiB reclaimable",
@@ -291,14 +277,13 @@ func TestReadReportOnTerminal(t *testing.T) {
 func TestRunReportsIgnoreInsertionOrder(t *testing.T) {
 	// README §Constraints: identical database contents give identical
 	// output, whatever order the records were inserted in.
-	a, b := testHash("a"), testHash("b")
-
 	recs := append(smokeTreeRecs(), awkwardPairRecs()...)
 	recs = append(recs,
-		scanRec{size: 50, head: b, tail: b, content: b, path: "/y/2"},
-		scanRec{size: 50, head: b, tail: b, content: b, path: "/y/1"},
-		scanRec{size: 50, head: a, tail: a, content: a, path: "/x/2"},
-		scanRec{size: 50, head: a, tail: a, content: a, path: "/x/1"},
+		scanRec{size: 50, head: "b", tail: "b", content: "b", path: "/y/2"},
+		scanRec{size: 50, head: "b", tail: "b", content: "b", path: "/y/1"},
+		scanRec{size: 50, head: "a", tail: "a", content: "a", path: "/x/2"},
+		scanRec{size: 50, head: "a", tail: "a", content: "a", path: "/x/1"},
+		scanRec{size: 50, path: "/x/unhashed"},
 	)
 
 	reversed := slices.Clone(recs)
@@ -401,19 +386,16 @@ func TestWarnfEscapes(t *testing.T) {
 func TestDupeGroups(t *testing.T) {
 	t.Parallel()
 
-	h, tl, c := testHash("h"), testHash("t"), testHash("c")
-	bigH, bigT, bigC := testHash("H"), testHash("T"), testHash("C")
-	u := testHash("u")
 	recs := []scanRec{
-		{size: 100, head: h, tail: tl, content: c, path: "/z/b"},
-		{size: 100, head: h, tail: tl, content: c, path: "/z/a"},
-		{size: 100, head: h, tail: tl, content: c, path: "/z/c"},
-		{size: 4000, head: bigH, tail: bigT, content: bigC, path: "/big/2"},
-		{size: 4000, head: bigH, tail: bigT, content: bigC, path: "/big/1"},
+		{size: 100, head: "h", tail: "t", content: "c", path: "/z/b"},
+		{size: 100, head: "h", tail: "t", content: "c", path: "/z/a"},
+		{size: 100, head: "h", tail: "t", content: "c", path: "/z/c"},
+		{size: 4000, head: "H", tail: "T", content: "C", path: "/big/2"},
+		{size: 4000, head: "H", tail: "T", content: "C", path: "/big/1"},
 		// Same size as the /z group but a different head hash.
-		{size: 100, head: testHash("other"), tail: tl, content: c, path: "/z/d"},
+		{size: 100, head: "other", tail: "t", content: "c", path: "/z/d"},
 		// A singleton signature must not form a group.
-		{size: 7, head: u, tail: u, content: u, path: "/lonely"},
+		{size: 7, head: "u", tail: "u", content: "u", path: "/lonely"},
 	}
 
 	groups := dupeGroupsOf(t, recs)
@@ -437,13 +419,16 @@ func TestDupeGroups(t *testing.T) {
 func TestDupeGroupsContentSeparates(t *testing.T) {
 	t.Parallel()
 
-	// Same size, head, and tail: /b differs from the others only in its
-	// content hash, so it joins no group, while /a and /c group.
-	h, tl := testHash("h"), testHash("t")
+	// Same size, head, and tail, but different content hashes: the final
+	// rung keeps them apart, so no group forms. Matching content groups.
+	// Records without a content hash never group, not even with each
+	// other.
 	recs := []scanRec{
-		{size: 100, head: h, tail: tl, content: testHash("c1"), path: "/a"},
-		{size: 100, head: h, tail: tl, content: testHash("c2"), path: "/b"},
-		{size: 100, head: h, tail: tl, content: testHash("c1"), path: "/c"},
+		{size: 100, head: "h", tail: "t", content: "c1", path: "/a"},
+		{size: 100, head: "h", tail: "t", content: "c2", path: "/b"},
+		{size: 100, head: "h", tail: "t", content: "c1", path: "/c"},
+		{size: 100, head: "h", tail: "t", path: "/d"},
+		{size: 100, head: "h", tail: "t", path: "/e"},
 	}
 
 	groups := dupeGroupsOf(t, recs)
@@ -462,15 +447,14 @@ func TestDupeGroupsMtimeExcluded(t *testing.T) {
 
 	// mtime is informational only; records differing only in mtime
 	// still group together.
-	h, tl, c := testHash("h"), testHash("t"), testHash("c")
 	recs := []scanRec{
 		{
-			size: 9, mtime: time.Unix(100, 0), head: h, tail: tl,
-			content: c, path: "/m/1",
+			size: 9, mtime: time.Unix(100, 0), head: "h", tail: "t",
+			content: "c", path: "/m/1",
 		},
 		{
-			size: 9, mtime: time.Unix(200, 0), head: h, tail: tl,
-			content: c, path: "/m/2",
+			size: 9, mtime: time.Unix(200, 0), head: "h", tail: "t",
+			content: "c", path: "/m/2",
 		},
 	}
 
@@ -485,12 +469,11 @@ func TestDupeGroupsTieBreak(t *testing.T) {
 
 	// The hashes sort opposite to the first paths, so ordering the
 	// groups by hash instead of by first path fails this test.
-	a, b := testHash("a"), testHash("b")
 	recs := []scanRec{
-		{size: 50, head: a, tail: a, content: a, path: "/beta/2"},
-		{size: 50, head: a, tail: a, content: a, path: "/beta/1"},
-		{size: 50, head: b, tail: b, content: b, path: "/alpha/2"},
-		{size: 50, head: b, tail: b, content: b, path: "/alpha/1"},
+		{size: 50, head: "a", tail: "a", content: "a", path: "/beta/2"},
+		{size: 50, head: "a", tail: "a", content: "a", path: "/beta/1"},
+		{size: 50, head: "b", tail: "b", content: "b", path: "/alpha/2"},
+		{size: 50, head: "b", tail: "b", content: "b", path: "/alpha/1"},
 	}
 
 	groups := dupeGroupsOf(t, recs)
@@ -512,16 +495,15 @@ func TestDupeGroupsOrderedByFirstPath(t *testing.T) {
 	// /z, /k, which is neither the order of their first paths nor its
 	// reverse, and must write them ordered by first path. The group of
 	// size 7 comes after them all, though its first path sorts first.
-	a, b, c, d := testHash("a"), testHash("b"), testHash("c"), testHash("d")
 	recs := []scanRec{
-		{size: 50, head: a, tail: a, content: a, path: "/k/2"},
-		{size: 50, head: a, tail: a, content: a, path: "/k/1"},
-		{size: 50, head: b, tail: b, content: b, path: "/z/1"},
-		{size: 50, head: b, tail: b, content: b, path: "/z/2"},
-		{size: 50, head: c, tail: c, content: c, path: "/a/2"},
-		{size: 50, head: c, tail: c, content: c, path: "/a/1"},
-		{size: 7, head: d, tail: d, content: d, path: "/0/2"},
-		{size: 7, head: d, tail: d, content: d, path: "/0/1"},
+		{size: 50, head: "a", tail: "a", content: "a", path: "/k/2"},
+		{size: 50, head: "a", tail: "a", content: "a", path: "/k/1"},
+		{size: 50, head: "b", tail: "b", content: "b", path: "/z/1"},
+		{size: 50, head: "b", tail: "b", content: "b", path: "/z/2"},
+		{size: 50, head: "c", tail: "c", content: "c", path: "/a/2"},
+		{size: 50, head: "c", tail: "c", content: "c", path: "/a/1"},
+		{size: 7, head: "d", tail: "d", content: "d", path: "/0/2"},
+		{size: 7, head: "d", tail: "d", content: "d", path: "/0/1"},
 	}
 
 	groups := dupeGroupsOf(t, recs)
@@ -540,12 +522,11 @@ func TestDupeGroupsOrderedByFirstPath(t *testing.T) {
 func TestDupeGroupsDeterministic(t *testing.T) {
 	t.Parallel()
 
-	a, b := testHash("a"), testHash("b")
 	recs := []scanRec{
-		{size: 1, head: a, tail: a, content: a, path: "/p/1"},
-		{size: 1, head: a, tail: a, content: a, path: "/p/2"},
-		{size: 2, head: b, tail: b, content: b, path: "/q/1"},
-		{size: 2, head: b, tail: b, content: b, path: "/q/2"},
+		{size: 1, head: "a", tail: "a", content: "a", path: "/p/1"},
+		{size: 1, head: "a", tail: "a", content: "a", path: "/p/2"},
+		{size: 2, head: "b", tail: "b", content: "b", path: "/q/1"},
+		{size: 2, head: "b", tail: "b", content: "b", path: "/q/2"},
 	}
 
 	forward := dupeGroupsOf(t, recs)

trees.go

@@ -22,10 +22,6 @@ type treeNode struct {
 	digest    [sha256.Size]byte
 	fileCount int64
 	totalSize int64
-	// diskSize is the bytes the directory's files take on disk. Two
-	// copies of one tree have the same totalSize, but their diskSize
-	// can differ.
-	diskSize int64
 }
 
 // treesPhase names one phase of trees with its place among all of them,
@@ -44,11 +40,11 @@ func treesPhase(name string) string {
 // database problem, including a missing database, is fatal.
 //
 // The work runs in four phases, each under a progress display of its
-// own on stderr: open (open the database), read (read the number of
-// records from the totals table, then read the records into the
-// hierarchy), group (group the directories by digest) and write (write
-// the groups to stdout). Each display ends before the next phase
-// starts, and before an error is returned to be printed.
+// own on stderr: open (open the database), read (count the records,
+// then read them into the hierarchy), group (group the directories by
+// digest) and write (write the groups to stdout). Each display ends
+// before the next phase starts, and before an error is returned to be
+// printed.
 func runTrees(ctx context.Context, stdout io.Writer) error {
 	dbPath, source, err := databasePath()
 	if err != nil {
@@ -143,16 +139,15 @@ func readTree(ctx context.Context, db *sql.DB,
 
 // writeTreeGroups writes dupes to stdout as TSV, a header line and then
 // a row for every member of each group but its first, counting each
-// group on prog once its rows are written. The disk_size column is the
-// dupe's own. stdout may be the terminal prog is drawn on, so the lines
-// go through prog's writer. It returns the number of rows (dupe trees)
-// and the bytes they could reclaim.
+// group on prog once its rows are written. stdout may be the terminal
+// prog is drawn on, so the lines go through prog's writer. It returns
+// the number of rows (dupe trees) and the bytes they could reclaim.
 func writeTreeGroups(stdout io.Writer, dupes [][]*treeNode,
 	prog *progress,
 ) (int, int64, error) {
 	out := prog.writer(stdout)
 
-	_, err := fmt.Fprintln(out, "first\tdupe\tfiles\tsize\tdisk_size")
+	_, err := fmt.Fprintln(out, "first\tdupe\tfiles\tsize")
 	if err != nil {
 		return 0, 0, fmt.Errorf("write stdout: %w", err)
 	}
@@ -164,9 +159,9 @@ func writeTreeGroups(stdout io.Writer, dupes [][]*treeNode,
 	for _, g := range dupes {
 		first := g[0]
 		for _, n := range g[1:] {
-			_, err = fmt.Fprintf(out, "%s\t%s\t%d\t%d\t%d\n",
+			_, err = fmt.Fprintf(out, "%s\t%s\t%d\t%d\n",
 				escapePath(first.path), escapePath(n.path),
-				first.fileCount, first.totalSize, n.diskSize)
+				first.fileCount, first.totalSize)
 			if err != nil {
 				return 0, 0, fmt.Errorf("write stdout: %w", err)
 			}
@@ -237,7 +232,6 @@ func (b *treeBuilder) add(r scanRec) {
 	dir.entries = append(dir.entries, fileEntry(name, r))
 	dir.fileCount++
 	dir.totalSize += r.size
-	dir.diskSize += r.diskSize
 }
 
 // openDir starts the directory called name inside the innermost open
@@ -276,7 +270,6 @@ func (b *treeBuilder) closeTo(n int) {
 			"d\x00"+name+"\x00"+string(dir.digest[:]))
 		dir.parent.fileCount += dir.fileCount
 		dir.parent.totalSize += dir.totalSize
-		dir.parent.diskSize += dir.diskSize
 		b.dirs = append(b.dirs, dir)
 	}
 }
@@ -293,9 +286,18 @@ func (b *treeBuilder) finish() (*treeNode, []*treeNode) {
 // name and its signature (size, head, tail, content); mtime is
 // excluded.
 func fileEntry(name string, r scanRec) string {
+	content := r.content
+
+	// A record without a content hash has unknown content (README
+	// "Database"): give it a signature no other file can share, so
+	// trees containing it never compare equal. Real hashes are hex, so
+	// the NUL-prefixed form cannot collide.
+	if content == "" {
+		content = "unhashed\x00" + r.path
+	}
+
 	return "f\x00" + name + "\x00" + strconv.FormatInt(r.size, 10) +
-		"\x00" + string(r.head[:]) + "\x00" + string(r.tail[:]) +
-		"\x00" + string(r.content[:])
+		"\x00" + r.head + "\x00" + r.tail + "\x00" + content
 }
 
 // collectTreeGroups groups directories by digest, counting each one on
@@ -345,8 +347,7 @@ func collectTreeGroups(allDirs []*treeNode, super *treeNode,
 // digest is the SHA-256 of its child entries — files serialized with
 // name and signature, subdirectories with name and recursive digest —
 // sorted byte-lexicographically. Filenames cannot contain NUL or "/",
-// and every hash and digest is 32 bytes, so NUL delimiters are
-// unambiguous.
+// so NUL delimiters are unambiguous.
 func (n *treeNode) computeDigest() {
 	slices.Sort(n.entries)
 

trees_test.go

@@ -10,31 +10,32 @@ import (
 	"time"
 )
 
+// Signature hashes shared by the smoke-test records.
+const (
+	f1Head    = "f1h"
+	f1Tail    = "f1t"
+	f1Content = "f1c"
+	f2Head    = "f2h"
+	f2Tail    = "f2t"
+	f2Content = "f2c"
+)
+
 // treesOpenLine is the plain line of trees' open phase when it opens
 // the database at once; it prints it as the phase starts and as it ends.
 const treesOpenLine = "[1/4] open: opening the database, elapsed 0s, " +
-	"remain unknown"
+	"eta unknown"
 
-// smokeTreeRecs mirrors the tree of the test under README "Definition
-// of done": /d/t1 and /d/t2 are identical, /d/t3 differs from them only
-// by one filename. Each file takes one 4 KiB block on disk.
+// smokeTreeRecs mirrors the README smoke-test tree layout: /d/t1 and
+// /d/t2 are identical, /d/t3 differs from them only by one filename.
 func smokeTreeRecs() []scanRec {
-	f1Head, f1Tail, f1Content := testHash("f1h"), testHash("f1t"), testHash("f1c")
-	f2Head, f2Tail, f2Content := testHash("f2h"), testHash("f2t"), testHash("f2c")
-
 	return []scanRec{
-		{size: 3000, diskSize: 4096, head: f1Head, tail: f1Tail,
-			content: f1Content, path: "/d/t1/f1"},
-		{size: 100, diskSize: 4096, head: f2Head, tail: f2Tail,
-			content: f2Content, path: "/d/t1/sub/f2"},
-		{size: 3000, diskSize: 4096, head: f1Head, tail: f1Tail,
-			content: f1Content, path: "/d/t2/f1"},
-		{size: 100, diskSize: 4096, head: f2Head, tail: f2Tail,
-			content: f2Content, path: "/d/t2/sub/f2"},
-		{size: 3000, diskSize: 4096, head: f1Head, tail: f1Tail,
-			content: f1Content, path: "/d/t3/f1"},
-		{size: 100, diskSize: 4096, head: f2Head, tail: f2Tail,
-			content: f2Content, path: "/d/t3/sub/f2renamed"},
+		{size: 3000, head: f1Head, tail: f1Tail, content: f1Content, path: "/d/t1/f1"},
+		{size: 100, head: f2Head, tail: f2Tail, content: f2Content, path: "/d/t1/sub/f2"},
+		{size: 3000, head: f1Head, tail: f1Tail, content: f1Content, path: "/d/t2/f1"},
+		{size: 100, head: f2Head, tail: f2Tail, content: f2Content, path: "/d/t2/sub/f2"},
+		{size: 3000, head: f1Head, tail: f1Tail, content: f1Content, path: "/d/t3/f1"},
+		{size: 100, head: f2Head, tail: f2Tail, content: f2Content,
+			path: "/d/t3/sub/f2renamed"},
 	}
 }
 
@@ -152,14 +153,13 @@ func TestTreeNamesSortingBeforeSlash(t *testing.T) {
 
 	for _, top := range []string{"/a", "/c"} {
 		for _, p := range []string{"/b", "/b-x/f", "/b.txt", "/b/f"} {
-			content := testHash("c")
+			content := "c"
 			if p == "/b-x/f" {
-				content = testHash("other")
+				content = "other"
 			}
 
 			recs = append(recs, scanRec{
-				size: 1, head: testHash("h"), tail: testHash("t"),
-				content: content, path: top + p,
+				size: 1, head: "h", tail: "t", content: content, path: top + p,
 			})
 		}
 	}
@@ -204,33 +204,13 @@ func TestRunTreesEscapesPaths(t *testing.T) {
 			code, exitOK, stderr.String())
 	}
 
-	want := "first\tdupe\tfiles\tsize\tdisk_size\n" +
-		`/d/\tone\ntwo\rthree\\four` + "\t/d/A\t1\t5\t4096\n"
+	want := "first\tdupe\tfiles\tsize\n" +
+		`/d/\tone\ntwo\rthree\\four` + "\t/d/A\t1\t5\n"
 	if got := stdout.String(); got != want {
 		t.Errorf("stdout = %q, want %q", got, want)
 	}
 }
 
-// TestRunTreesDiskSize runs trees on two copies of a tree whose files
-// take different space on disk. The row's disk_size is the sum over the
-// dupe copy's files, those in its subdirectory included.
-func TestRunTreesDiskSize(t *testing.T) {
-	f, g := testHash("f"), testHash("g")
-	recs := []scanRec{
-		{size: 10, diskSize: 4096, head: f, tail: f, content: f, path: "/a/f"},
-		{size: 20, diskSize: 4096, head: g, tail: g, content: g, path: "/a/sub/g"},
-		{size: 10, diskSize: 512, head: f, tail: f, content: f, path: "/b/f"},
-		{size: 20, diskSize: 1024, head: g, tail: g, content: g, path: "/b/sub/g"},
-	}
-
-	t.Setenv(databaseEnv, seedDatabase(t, recs))
-
-	want := "first\tdupe\tfiles\tsize\tdisk_size\n/a\t/b\t2\t30\t1536\n"
-	if got := runStdout(t, cmdTrees); got != want {
-		t.Errorf("stdout = %q, want %q", got, want)
-	}
-}
-
 // TestRunTreesProgressNamesEachPhase runs trees on the smoke-test
 // records with stderr not a terminal, and checks every line it prints
 // there. After the line naming the database, each phase prints a line
@@ -252,8 +232,7 @@ func TestRunTreesProgressNamesEachPhase(t *testing.T) {
 			code, exitOK, stderr())
 	}
 
-	report := "first\tdupe\tfiles\tsize\tdisk_size\n" +
-		"/d/t1\t/d/t2\t2\t3100\t8192\n"
+	report := "first\tdupe\tfiles\tsize\n/d/t1\t/d/t2\t2\t3100\n"
 	if got := stdout.String(); got != report {
 		t.Errorf("stdout = %q, want %q", got, report)
 	}
@@ -263,11 +242,11 @@ func TestRunTreesProgressNamesEachPhase(t *testing.T) {
 		"trees: database " + path + " (from " + databaseEnv + ")",
 		treesOpenLine,
 		treesOpenLine,
-		"[2/4] read: counting the records, elapsed 0s, remain unknown",
+		"[2/4] read: counting the records, elapsed 0s, eta unknown",
 		"[2/4] read: [6/6] 100%, ",
-		"[3/4] group: [0/8] 0%, 0 directories/s, elapsed 0s, remain unknown",
+		"[3/4] group: [0/8] 0%, 0 directories/s, elapsed 0s, eta unknown",
 		"[3/4] group: [8/8] 100%, ",
-		"[4/4] write: [0/1] 0%, 0 groups/s, elapsed 0s, remain unknown",
+		"[4/4] write: [0/1] 0%, 0 groups/s, elapsed 0s, eta unknown",
 		"[4/4] write: [1/1] 100%, ",
 		"trees: 6 records read, 1 duplicate tree groups, 1 dupe trees, ",
 	}
@@ -318,9 +297,7 @@ func TestWriteTreeGroupsOnTerminal(t *testing.T) {
 		shown = append(shown, line[strings.LastIndex(line, "\r")+1:])
 	}
 
-	want := []string{
-		"first\tdupe\tfiles\tsize\tdisk_size", "/d/t1\t/d/t2\t2\t3100\t8192",
-	}
+	want := []string{"first\tdupe\tfiles\tsize", "/d/t1\t/d/t2\t2\t3100"}
 	if len(shown) < len(want) || !slices.Equal(shown[:len(want)], want) {
 		t.Errorf("terminal shows lines %q, want %q first", shown, want)
 	}
@@ -355,10 +332,11 @@ func TestTreeDigests(t *testing.T) {
 func TestTreeDigestContentSensitivity(t *testing.T) {
 	t.Parallel()
 
-	same, c := testHash("same"), testHash("c")
+	const sharedTail = "same"
+
 	recs := []scanRec{
-		{size: 10, head: same, tail: same, content: c, path: "/r/a/f"},
-		{size: 10, head: testHash("DIFF"), tail: same, content: c, path: "/r/b/f"},
+		{size: 10, head: sharedTail, tail: sharedTail, content: "c", path: "/r/a/f"},
+		{size: 10, head: "DIFF", tail: sharedTail, content: "c", path: "/r/b/f"},
 	}
 
 	_, dirs := treeOf(t, recs)
@@ -419,10 +397,9 @@ func TestCollectTreeGroupsSiblings(t *testing.T) {
 
 	// Identical sibling dirs share a parent, so their group cannot be
 	// implied by a parent group and must be reported.
-	h, tl, c := testHash("h"), testHash("t"), testHash("c")
 	recs := []scanRec{
-		{size: 10, head: h, tail: tl, content: c, path: "/p/x1/f"},
-		{size: 10, head: h, tail: tl, content: c, path: "/p/x2/f"},
+		{size: 10, head: "h", tail: "t", content: "c", path: "/p/x1/f"},
+		{size: 10, head: "h", tail: "t", content: "c", path: "/p/x2/f"},
 	}
 
 	super, dirs := treeOf(t, recs)
@@ -441,11 +418,10 @@ func TestCollectTreeGroupsDifferingParents(t *testing.T) {
 	// /p/a and /q/b contain identical x subtrees, but /p/a has an
 	// extra file, so the parents' digests differ and the x group must
 	// be reported.
-	h, tl, c, e := testHash("h"), testHash("t"), testHash("c"), testHash("e")
 	recs := []scanRec{
-		{size: 10, head: h, tail: tl, content: c, path: "/p/a/x/f"},
-		{size: 99, head: e, tail: e, content: e, path: "/p/a/extra"},
-		{size: 10, head: h, tail: tl, content: c, path: "/q/b/x/f"},
+		{size: 10, head: "h", tail: "t", content: "c", path: "/p/a/x/f"},
+		{size: 99, head: "e", tail: "e", content: "e", path: "/p/a/extra"},
+		{size: 10, head: "h", tail: "t", content: "c", path: "/q/b/x/f"},
 	}
 
 	super, dirs := treeOf(t, recs)