109 lines
3.7 KiB
Go
109 lines
3.7 KiB
Go
// Package store is the durable state of a book project: schema migrations,
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// the spend ledger (reserve/settle), chunk checkpoints and the request_log —
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// one SQLite file per project (modernc.org/sqlite, CGO-free, no native
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// extensions — Р3/Р6).
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//
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// Семантика денег и миграций портирована из vojo store.go; сам код написан
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// заново под SQLite (advisory-локов здесь нет — сериализацию даёт write-пул
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// из одного соединения + BEGIN IMMEDIATE; 03-implementation-notes §2 п.5).
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//
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// Рецепт конкурентности (§3.6): на файл БД два пула — write (MaxOpenConns=1,
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// транзакции immediate) и read (N соединений); прагмы на каждое соединение
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// через DSN: WAL, busy_timeout, foreign_keys, synchronous(NORMAL — переживает
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// kill -9; отключение питания вне модели угроз MVP).
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package store
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import (
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"context"
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"database/sql"
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"fmt"
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"net/url"
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"time"
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_ "modernc.org/sqlite"
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)
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// opTimeout bounds every store operation: SQLite is a local file and
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// effectively never blocks; the cap keeps a wedged filesystem from hanging a
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// pipeline goroutine forever.
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const opTimeout = 10 * time.Second
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// Store is one project database.
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type Store struct {
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w *sql.DB // single-connection write pool; all mutations go through it
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r *sql.DB // read pool
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}
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// Open opens (or creates) the project database at path, applies pending
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// migrations and recovers stale reservations from a crashed run.
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func Open(path string) (*Store, error) {
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dsn := func(txlock string) string {
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v := url.Values{}
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v.Add("_pragma", "journal_mode(WAL)")
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v.Add("_pragma", "busy_timeout(5000)")
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v.Add("_pragma", "foreign_keys(1)")
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v.Add("_pragma", "synchronous(NORMAL)")
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if txlock != "" {
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v.Set("_txlock", txlock)
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}
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return "file:" + path + "?" + v.Encode()
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}
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w, err := sql.Open("sqlite", dsn("immediate"))
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if err != nil {
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return nil, fmt.Errorf("store: open write pool: %w", err)
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}
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// One writer connection: SQLite has a single writer per file anyway;
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// serializing in Go turns SQLITE_BUSY storms into a plain queue.
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w.SetMaxOpenConns(1)
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r, err := sql.Open("sqlite", dsn(""))
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if err != nil {
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w.Close()
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return nil, fmt.Errorf("store: open read pool: %w", err)
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}
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r.SetMaxOpenConns(4)
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s := &Store{w: w, r: r}
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ctx, cancel := context.WithTimeout(context.Background(), opTimeout)
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defer cancel()
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if err := s.migrate(ctx); err != nil {
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s.Close()
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return nil, err
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}
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if err := s.recoverReservations(ctx); err != nil {
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s.Close()
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return nil, err
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}
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return s, nil
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}
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func (s *Store) Close() error {
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err1 := s.w.Close()
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err2 := s.r.Close()
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if err1 != nil {
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return err1
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}
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return err2
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}
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func opContext() (context.Context, context.CancelFunc) {
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return context.WithTimeout(context.Background(), opTimeout)
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}
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// recoverReservations zeroes reserved_usd left over by a crashed process. The
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// project file is owned by ONE process at a time (CLI), so any reservation
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// present at open belongs to a run that never settled — the recovery pass из
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// implementation-notes §3.3.
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func (s *Store) recoverReservations(ctx context.Context) error {
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res, err := s.w.ExecContext(ctx, `UPDATE spend SET reserved_usd = 0 WHERE reserved_usd > 0`)
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if err != nil {
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return fmt.Errorf("store: recover reservations: %w", err)
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}
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if n, _ := res.RowsAffected(); n > 0 {
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// The caller's logger isn't wired here; surface via the request_log-less
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// path is overkill — a plain stderr note keeps it visible.
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fmt.Printf("store: recovered %d stale reservation row(s) from a previous run\n", n)
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}
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return nil
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}
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