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db-mysql/component.go

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feat(db-mysql): initial implementation — database/sql MySQL with lifecycle and UnitOfWork (v1.0.0) 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
2026-05-29 15:51:53 +00:00
package mysql
import (
"database/sql"
"code.nochebuena.dev/einherjar/contracts/lifecycle"
"code.nochebuena.dev/einherjar/contracts/observability"
)
// Component bundles the full MySQL capability: lifecycle management,
// health reporting, and the database [Provider] interface.
// Register with launcher and health before starting.
type Component interface {
lifecycle.Component
observability.Checkable
observability.Identifiable
Provider
// Stats returns connection pool statistics. Returns a zero-value stat
// when the pool has not been initialized yet.
Stats() sql.DBStats
}