cmd/minstrel/main.go

@@ -363,10 +363,11 @@ func run() error {
 
 	// Duplicate resolver (M498, M502): classifies the sweep's groups and, with
 	// the operator's auto-resolve on, merges the copies that are safe to merge.
-	// Started after SetNotifier so its summaries reach admins. See
+	// Started after SetNotifier so its summaries reach admins. It asks the
-	// internal/library/duplicate_resolve.go.
+	// catalogue for the track list of an album whose wrong slot it must
+	// decide, a few a pass. See internal/library/duplicate_resolve.go.
 	go library.NewDuplicateResolveWorker(pool, logger.With("component", "duplicate_resolve"),
-		cfg.Storage.DataDir, fpSettings).Run(ctx)
+		cfg.Storage.DataDir, fpSettings, cat.RefreshReleaseGroup).Run(ctx)
 
 	// Missing-file re-acquisition (milestone #290, M502 #5520). Wants back
 	// albums whose files have been gone longer than the grace window; the

internal/library/duplicate_resolve.go

@@ -112,10 +112,24 @@ func mergePlan(g *resolveGroup) (ok bool, survivor int) {
 	return false, -1
 }
 
+// TrackListFetcher reads a release group's releases and track lists from
+// MusicBrainz into the catalogue (catalogue.Service.RefreshReleaseGroup).
+type TrackListFetcher func(ctx context.Context, releaseGroupMBID string) error
+
 // ResolveDuplicates runs one pass. act is the operator's auto-resolve setting;
-// with it off, the pass only classifies.
+// with it off, the pass only classifies. It reads only track lists already in
+// the catalogue; ResolveDuplicatesFetching may also fetch missing ones.
 func ResolveDuplicates(
 	ctx context.Context, pool *pgxpool.Pool, logger *slog.Logger, dataDir string, act bool,
+) (DuplicateResolveResult, error) {
+	return ResolveDuplicatesFetching(ctx, pool, logger, dataDir, act, nil)
+}
+
+// ResolveDuplicatesFetching is ResolveDuplicates that asks MusicBrainz, through
+// fetch, for the track list of an album whose wrong slot it must decide and
+// the catalogue has never read: a few per pass (trackListFetchesPerPass).
+func ResolveDuplicatesFetching(
+	ctx context.Context, pool *pgxpool.Pool, logger *slog.Logger, dataDir string, act bool, fetch TrackListFetcher,
 ) (DuplicateResolveResult, error) {
 	if logger == nil {
 		logger = slog.Default()
@@ -182,7 +196,7 @@ func ResolveDuplicates(
 	}
 
 	res.Dismissed = dismissDistinct(ctx, pool, logger, groups, merged)
-	wrong, names := settleWrongSlots(ctx, pool, logger, groups, merged)
+	wrong, names := settleWrongSlots(ctx, pool, logger, groups, merged, fetch)
 	res.WrongFiles = wrong
 	mergedNames = append(mergedNames, names...)
 
@@ -375,14 +389,18 @@ type DuplicateResolveWorker struct {
 	logger   *slog.Logger
 	dataDir  string
 	settings *FingerprintSettingsService
+	fetch    TrackListFetcher
 	tick     time.Duration
 }
 
-// NewDuplicateResolveWorker builds a worker with the production cadence.
+// NewDuplicateResolveWorker builds a worker with the production cadence. fetch
+// reads a missing track list from MusicBrainz; nil reads only what is held.
 func NewDuplicateResolveWorker(
-	pool *pgxpool.Pool, logger *slog.Logger, dataDir string, settings *FingerprintSettingsService,
+	pool *pgxpool.Pool, logger *slog.Logger, dataDir string, settings *FingerprintSettingsService, fetch TrackListFetcher,
 ) *DuplicateResolveWorker {
-	return &DuplicateResolveWorker{pool: pool, logger: logger, dataDir: dataDir, settings: settings, tick: duplicateResolveTick}
+	return &DuplicateResolveWorker{
+		pool: pool, logger: logger, dataDir: dataDir, settings: settings, fetch: fetch, tick: duplicateResolveTick,
+	}
 }
 
 // Run blocks until ctx is cancelled, running a pass at start and then each tick.
@@ -418,7 +436,7 @@ func (w *DuplicateResolveWorker) tickOnce(ctx context.Context) {
 		}
 		return
 	}
-	res, err := ResolveDuplicates(ctx, w.pool, w.logger, w.dataDir, w.settings.Get().AutoResolve)
+	res, err := ResolveDuplicatesFetching(ctx, w.pool, w.logger, w.dataDir, w.settings.Get().AutoResolve, w.fetch)
 	if err != nil && ctx.Err() == nil {
 		w.logger.Warn("duplicate resolve: pass failed", "err", err)
 	}

internal/library/duplicate_resolve_test.go

@@ -405,6 +405,33 @@ func TestResolveDuplicates_RemovesACopyFromAnotherSongsSlot_Integration(t *testi
 	}
 }
 
+// An album whose track list the catalogue never read: the resolver asks for
+// it, once, and decides with what comes back.
+func TestResolveDuplicates_FetchesAMissingTrackList_Integration(t *testing.T) {
+	f := newOneAlbumFixture(t, "acoustic", "Void", "Reach")
+	rg := "rg-" + syncpkg.FormatUUID(f.album.ID)
+	if _, err := f.pool.Exec(context.Background(),
+		`UPDATE albums SET release_group_mbid = $2 WHERE id = $1`, f.album.ID, rg); err != nil {
+		t.Fatal(err)
+	}
+	calls := 0
+	fetch := func(_ context.Context, asked string) error {
+		calls++
+		if asked != rg {
+			t.Errorf("asked for %s, want %s", asked, rg)
+		}
+		seedTrackList(t, f.pool, f.album, map[string]int{"Void": 220500, "Reach": 281000})
+		return nil
+	}
+	res, err := ResolveDuplicatesFetching(context.Background(), f.pool, nil, "", true, fetch)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if calls != 1 || res.WrongFiles != 1 || exists(f.bPath) {
+		t.Fatalf("fetches %d, result %+v; want one fetch and Reach's copy removed", calls, res)
+	}
+}
+
 // Without a track list that decides, nothing is removed.
 func TestResolveDuplicates_LeavesAnUndecidedSlotForTheOperator_Integration(t *testing.T) {
 	f := newOneAlbumFixture(t, "acoustic", "Void", "Reach")

internal/library/duplicate_settle.go

@@ -13,6 +13,7 @@ import (
 
 	"git.fabledsword.com/bvandeusen/minstrel/internal/audit"
 	"git.fabledsword.com/bvandeusen/minstrel/internal/db/dbq"
+	"git.fabledsword.com/bvandeusen/minstrel/internal/musicbrainz"
 	"git.fabledsword.com/bvandeusen/minstrel/internal/notifications"
 	syncpkg "git.fabledsword.com/bvandeusen/minstrel/internal/sync"
 )
@@ -33,6 +34,10 @@ import (
 //     Anything less certain stays with the operator.
 
 const (
+	// trackListFetchesPerPass is how many albums' track lists a pass may ask
+	// MusicBrainz for, when the catalogue has never read them. The resolver
+	// runs hourly, so a backlog drains over a few hours without a burst.
+	trackListFetchesPerPass = 5
 	// slotFit is how close a file must be to a slot's MusicBrainz length to be
 	// that slot's song, and slotOther how far away every length of a slot's
 	// title must be for the file to be another song's.
@@ -143,9 +148,14 @@ func dismissDistinct(
 // to settled.
 func settleWrongSlots(
 	ctx context.Context, pool *pgxpool.Pool, logger *slog.Logger, groups []*resolveGroup, settled map[pgtype.UUID]bool,
+	fetch TrackListFetcher,
 ) (int, []string) {
 	q := dbq.New(pool)
 	tracksByGroup := map[string][]dbq.MbReleaseTrack{}
+	fetches := trackListFetchesPerPass
+	if fetch == nil {
+		fetches = 0
+	}
 	removed := 0
 	var names []string
 	for _, g := range groups {
@@ -163,6 +173,18 @@ func settleWrongSlots(
 				logger.Warn("duplicate resolve: reading the album's track list failed", "release_group", rg, "err", err)
 				continue
 			}
+			if len(tracks) == 0 && fetches > 0 && neverRead(ctx, q, rg) {
+				fetches--
+				if err := fetch(ctx, rg); err != nil {
+					logger.Info("duplicate resolve: fetching the album's track list failed", "release_group", rg, "err", err)
+					if errors.Is(err, musicbrainz.ErrUnreachable) {
+						fetches = 0
+					}
+				} else if tracks, err = q.ListMBReleaseTracksForGroup(ctx, rg); err != nil {
+					logger.Warn("duplicate resolve: reading the album's track list failed", "release_group", rg, "err", err)
+					continue
+				}
+			}
 			tracksByGroup[rg] = tracks
 		}
 		copies := make([]slotCopy, len(g.members))
@@ -187,6 +209,14 @@ func settleWrongSlots(
 	return removed, names
 }
 
+// neverRead reports whether the catalogue has never read a release group's
+// releases. A group read and found empty is not asked about again: the
+// catalogue's own refresh revisits it.
+func neverRead(ctx context.Context, q *dbq.Queries, rg string) bool {
+	g, err := q.GetMBReleaseGroup(ctx, rg)
+	return errors.Is(err, pgx.ErrNoRows) || (err == nil && !g.ReleasesRefreshedAt.Valid)
+}
+
 // removeWrongSlots deletes each loser's file, then marks its track missing in
 // the same transaction that closes the group. The row is kept, with its likes
 // and plays: it is the slot, and a good copy fetched again takes it over. A