refactor: split modules and harden scraping workflows

internal/database/sqlite_runtime.go

@@ -0,0 +1,104 @@
+package database
+
+import (
+	"context"
+	"fmt"
+	"path/filepath"
+
+	"gorm.io/gorm"
+
+	"github.com/ShukeBta/MediaStationGo/internal/config"
+)
+
+func installSQLiteWriteGate(db *gorm.DB) {
+	if db == nil {
+		return
+	}
+	const lockedKey = "mediastation:sqlite_write_locked"
+	gate := newSQLiteWriteGate()
+	lock := func(tx *gorm.DB) {
+		ctx := context.Background()
+		if tx.Statement != nil && tx.Statement.Context != nil {
+			ctx = tx.Statement.Context
+		}
+		if err := gate.Lock(ctx); err != nil {
+			_ = tx.AddError(err)
+			return
+		}
+		tx.InstanceSet(lockedKey, struct{}{})
+	}
+	unlock := func(tx *gorm.DB) {
+		if _, ok := tx.InstanceGet(lockedKey); ok {
+			gate.Unlock()
+		}
+	}
+	_ = db.Callback().Create().Before("gorm:create").Register("mediastation:sqlite_write_lock", lock)
+	_ = db.Callback().Create().After("gorm:create").Register("mediastation:sqlite_write_unlock", unlock)
+	_ = db.Callback().Update().Before("gorm:update").Register("mediastation:sqlite_write_lock", lock)
+	_ = db.Callback().Update().After("gorm:update").Register("mediastation:sqlite_write_unlock", unlock)
+	_ = db.Callback().Delete().Before("gorm:delete").Register("mediastation:sqlite_write_lock", lock)
+	_ = db.Callback().Delete().After("gorm:delete").Register("mediastation:sqlite_write_unlock", unlock)
+	_ = db.Callback().Raw().Before("gorm:raw").Register("mediastation:sqlite_write_lock", lock)
+	_ = db.Callback().Raw().After("gorm:raw").Register("mediastation:sqlite_write_unlock", unlock)
+}
+
+// sqliteWriteGate serializes in-process SQLite writes while respecting the
+// statement context, so request cancellation can break out of a queued write.
+type sqliteWriteGate struct {
+	ch chan struct{}
+}
+
+func newSQLiteWriteGate() *sqliteWriteGate {
+	return &sqliteWriteGate{ch: make(chan struct{}, 1)}
+}
+
+func (g *sqliteWriteGate) Lock(ctx context.Context) error {
+	select {
+	case g.ch <- struct{}{}:
+		return nil
+	default:
+	}
+	if ctx == nil {
+		ctx = context.Background()
+	}
+	select {
+	case g.ch <- struct{}{}:
+		return nil
+	case <-ctx.Done():
+		return ctx.Err()
+	}
+}
+
+func (g *sqliteWriteGate) Unlock() {
+	select {
+	case <-g.ch:
+	default:
+	}
+}
+
+func buildSQLiteDSN(cfg *config.Config) string {
+	dbPath := cfg.Database.DBPath
+	if !filepath.IsAbs(dbPath) {
+		// keep as-is to respect user-provided relative paths.
+		dbPath = filepath.Clean(dbPath)
+	}
+	dsn := dbPath + "?_pragma=foreign_keys(1)"
+	if cfg.Database.WALMode {
+		dsn += "&_pragma=journal_mode(WAL)"
+	}
+	if cfg.Database.BusyTimeout > 0 {
+		dsn += fmt.Sprintf("&_pragma=busy_timeout(%d)", cfg.Database.BusyTimeout)
+	}
+	if cfg.Database.CacheSize != 0 {
+		dsn += fmt.Sprintf("&_pragma=cache_size(%d)", cfg.Database.CacheSize)
+	}
+	return dsn
+}
+
+func isSQLite(db *gorm.DB) bool {
+	return db != nil && db.Dialector != nil && db.Dialector.Name() == "sqlite"
+}
+
+func isPostgres(db *gorm.DB) bool {
+	return db != nil && db.Dialector != nil && db.Dialector.Name() == "postgres"
+}