Fix: Performance issues and sqlite locking (#74)

* fix: performance issues and sqlite locking

* fix: dashboard release stats was reversed

* refactor: open and migrate db

* chore: cleanup

internal/database/sqlite.go

@@ -0,0 +1,81 @@
+package database
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+	"sync"
+
+	_ "github.com/mattn/go-sqlite3"
+	"github.com/rs/zerolog/log"
+)
+
+type SqliteDB struct {
+	lock    sync.RWMutex
+	handler *sql.DB
+	ctx     context.Context
+	cancel  func()
+
+	DSN string
+}
+
+func NewSqliteDB(source string) *SqliteDB {
+	db := &SqliteDB{
+		DSN: dataSourceName(source, "autobrr.db"),
+	}
+
+	db.ctx, db.cancel = context.WithCancel(context.Background())
+
+	return db
+}
+
+func (db *SqliteDB) Open() error {
+	if db.DSN == "" {
+		return fmt.Errorf("DSN required")
+	}
+
+	var err error
+
+	// open database connection
+	if db.handler, err = sql.Open("sqlite3", db.DSN); err != nil {
+		log.Fatal().Err(err).Msg("could not open db connection")
+		return err
+	}
+
+	// Set busy timeout
+	if _, err = db.handler.Exec(`PRAGMA busy_timeout = 5000;`); err != nil {
+		return fmt.Errorf("busy timeout pragma")
+	}
+
+	// Enable WAL. SQLite performs better with the WAL  because it allows
+	// multiple readers to operate while data is being written.
+	if _, err = db.handler.Exec(`PRAGMA journal_mode = wal;`); err != nil {
+		return fmt.Errorf("enable wal: %w", err)
+	}
+
+	// Enable foreign key checks. For historical reasons, SQLite does not check
+	// foreign key constraints by default. There's some overhead on inserts to
+	// verify foreign key integrity, but it's definitely worth it.
+	if _, err = db.handler.Exec(`PRAGMA foreign_keys = ON;`); err != nil {
+		return fmt.Errorf("foreign keys pragma: %w", err)
+	}
+
+	// migrate db
+	if err = db.migrate(); err != nil {
+		log.Fatal().Err(err).Msg("could not migrate db")
+		return err
+	}
+
+	return nil
+}
+
+func (db *SqliteDB) Close() error {
+	// cancel background context
+	db.cancel()
+
+	// close database
+	if db.handler != nil {
+		return db.handler.Close()
+	}
+	return nil
+}