Rene Nochebuena
d64fd5403d
Introduces code.nochebuena.dev/einherjar/db-mysql — the MySQL database starter for the Einherjar framework. Absorbs the mysql package from micro-lib using the go-sql-driver/mysql driver, replacing fmt.Errorf wrapping with core/xerrors. Interfaces (CT-6: one TypeSpec per file): - Executor — ExecContext, QueryContext, QueryRowContext (database/sql types) - Tx — Executor + Commit(), Rollback() — no ctx; honest database/sql contract - Provider — GetExecutor, Begin, BeginTx, Ping, HandleError - Component — lifecycle.Component + observability.Checkable + Provider + Stats() - UnitOfWork — Do(ctx, fn) Implementation: - New(logger, cfg) Component — pool not created until OnInit - OnInit: sql.Open + SetMaxOpenConns/SetMaxIdleConns/SetConnMaxLifetime/SetConnMaxIdleTime - OnStart: Ping with 5s timeout; logs "mysql: connected" - OnStop: db.Close(); logs "mysql: closing pool" - GetExecutor: returns active Tx from context (ctxTxKey) or *sql.DB; explicit nil return when db uninitialized to avoid typed-nil interface pitfall - Begin/BeginTx: wraps db.BeginTx(*sql.TxOptions); wrapped in xerrors on error - HealthCheck: delegates to Ping; Priority LevelCritical - Stats() sql.DBStats — zero value when pool uninitialized - NewUnitOfWork(logger, provider) UnitOfWork — Begin+inject+commit/rollback; no write mutex (MySQL is a server DB with internal concurrency control) - HandleError: 1062→ErrAlreadyExists, 1216/1217/1451/1452→ErrInvalidInput, sql.ErrNoRows→ErrNotFound, all others→ErrInternal - Driver imported as mysqldrv alias in errors.go to avoid package-name collision; registered via blank import in new.go Config (EINHERJAR_MYSQL_* env vars): Host, Port(3306), User, Password, Name, MaxConns(5), MinConns(2), MaxConnLifetime(1h), MaxConnIdleTime(30m), Charset(utf8mb4), Loc(UTC), ParseTime(true) - Component interface embeds observability.Identifiable; identifiable.go implements ModulePath and ModuleVersion via runtime/debug.ReadBuildInfo() — prints in launcher banner
58 lines
2.0 KiB
Go
58 lines
2.0 KiB
Go
// Package mysql provides a database/sql-backed MySQL client with lifecycle
|
|
// management, health checks, and unit-of-work transaction support for
|
|
// Einherjar applications.
|
|
//
|
|
// # Overview
|
|
//
|
|
// [New] returns a [Component] that manages a *sql.DB connection pool,
|
|
// satisfies the [lifecycle.Component] lifecycle hooks (OnInit, OnStart, OnStop),
|
|
// and implements [observability.Checkable] with critical priority.
|
|
//
|
|
// [NewUnitOfWork] wraps multiple repository operations in a single transaction
|
|
// via context injection — no transaction object is passed between functions.
|
|
//
|
|
// # Lifecycle Registration
|
|
//
|
|
// db := mysql.New(logger, cfg)
|
|
// launcher.Register(db)
|
|
// health.Register(db)
|
|
//
|
|
// # Querying
|
|
//
|
|
// Repository code receives a [Provider] or [Executor] and calls [Provider.GetExecutor]
|
|
// to obtain the active transaction (if inside a [UnitOfWork]) or the pool:
|
|
//
|
|
// exec := db.GetExecutor(ctx)
|
|
// row := exec.QueryRowContext(ctx, "SELECT id FROM users WHERE email = ?", email)
|
|
// if err := row.Scan(&id); err != nil {
|
|
// return db.HandleError(err)
|
|
// }
|
|
//
|
|
// # Unit of Work
|
|
//
|
|
// [NewUnitOfWork] wraps operations in a single transaction. The transaction is
|
|
// injected into the context; [Provider.GetExecutor] returns it automatically.
|
|
//
|
|
// uow := mysql.NewUnitOfWork(logger, db)
|
|
// err := uow.Do(ctx, func(ctx context.Context) error {
|
|
// exec := db.GetExecutor(ctx) // returns active Tx
|
|
// _, err := exec.ExecContext(ctx, "INSERT INTO orders ...")
|
|
// return err
|
|
// })
|
|
//
|
|
// # Error Handling
|
|
//
|
|
// [HandleError] translates MySQL driver errors into typed [xerrors] values.
|
|
// Call it at every point where a driver error is first observed:
|
|
//
|
|
// if err := row.Scan(&out); err != nil {
|
|
// return db.HandleError(err)
|
|
// }
|
|
//
|
|
// Mapped codes:
|
|
// - 1062 (ER_DUP_ENTRY) → ErrAlreadyExists
|
|
// - 1216, 1217, 1451, 1452 (FK errors) → ErrInvalidInput
|
|
// - sql.ErrNoRows → ErrNotFound
|
|
// - all others → ErrInternal
|
|
package mysql
|