| 1 | package storage |
| 2 | |
| 3 | import ( |
| 4 | "context" |
| 5 | "database/sql" |
| 6 | "errors" |
| 7 | "fmt" |
| 8 | "net/url" |
| 9 | "os" |
| 10 | "path/filepath" |
| 11 | "sync" |
| 12 | "time" |
| 13 | |
| 14 | _ "modernc.org/sqlite" |
| 15 | ) |
| 16 | |
| 17 | // Rejection is a stable Save error that callers can match with errors.Is. |
| 18 | type Rejection string |
| 19 | |
| 20 | func (e Rejection) Error() string { return string(e) } |
| 21 | |
| 22 | const ( |
| 23 | ErrDuplicate Rejection = "duplicate: already have this event" |
| 24 | ErrReplaced Rejection = "duplicate: a newer version exists" |
| 25 | ErrDeleted Rejection = "blocked: event was previously deleted by its author" |
| 26 | ErrVanished Rejection = "blocked: this pubkey asked for its events to be deleted" |
| 27 | ) |
| 28 | |
| 29 | // Observer receives operation name, outcome and duration for instrumented |
| 30 | // Store operations. |
| 31 | type Observer interface { |
| 32 | ObserveStorage(operation, outcome string, duration time.Duration) |
| 33 | } |
| 34 | |
| 35 | // Store is a tenant's SQLite database. A Store must be closed when its owner |
| 36 | // is done with it. |
| 37 | type Store struct { |
| 38 | db *sql.DB |
| 39 | path string |
| 40 | observerMu sync.RWMutex |
| 41 | observer Observer |
| 42 | } |
| 43 | |
| 44 | // Open creates or opens path, initializes the tenant schema and returns a |
| 45 | // Store. The parent directory is created with mode 0700 and the database file |
| 46 | // with mode 0600. |
| 47 | func Open(ctx context.Context, path string) (*Store, error) { |
| 48 | if err := os.MkdirAll(filepath.Dir(path), 0700); err != nil { |
| 49 | return nil, fmt.Errorf("create database directory: %w" , err) |
| 50 | } |
| 51 | f, err := os.OpenFile(path, os.O_CREATE|os.O_RDWR, 0600) |
| 52 | if err != nil { |
| 53 | return nil, fmt.Errorf("create database: %w" , err) |
| 54 | } |
| 55 | if err := f.Close(); err != nil { |
| 56 | return nil, fmt.Errorf("close database file: %w" , err) |
| 57 | } |
| 58 | u := url.URL{Scheme: "file" , Path: path} |
| 59 | q := u.Query() |
| 60 | for _, pragma := range []string{"journal_mode(WAL)" , "synchronous(FULL)" , "foreign_keys(ON)" , "busy_timeout(5000)" } { |
| 61 | q.Add("_pragma" , pragma) |
| 62 | } |
| 63 | u.RawQuery = q.Encode() |
| 64 | db, err := sql.Open("sqlite" , u.String()) |
| 65 | if err != nil { |
| 66 | return nil, fmt.Errorf("open database: %w" , err) |
| 67 | } |
| 68 | // One connection serializes tenant database operations. Transaction hooks |
| 69 | // use their supplied transaction while it holds this connection. |
| 70 | db.SetMaxOpenConns(1) |
| 71 | db.SetMaxIdleConns(1) |
| 72 | s := &Store{db: db, path: path} |
| 73 | if _, err := db.ExecContext(ctx, schema); err != nil { |
| 74 | return nil, errors.Join(fmt.Errorf("initialize tenant schema: %w" , err), db.Close()) |
| 75 | } |
| 76 | return s, nil |
| 77 | } |
| 78 | |
| 79 | // DB returns the database used by tenant services for their schemas, queries |
| 80 | // and transactions. Event persistence uses Save or SaveTx to apply storage's |
| 81 | // replacement, deletion and indexing rules. |
| 82 | func (s *Store) DB() *sql.DB { return s.db } |
| 83 | |
| 84 | // Path returns the database file path supplied to Open. |
| 85 | func (s *Store) Path() string { return s.path } |
| 86 | |
| 87 | // Close releases the database connection. |
| 88 | func (s *Store) Close() error { return s.db.Close() } |
| 89 | |
| 90 | // SetObserver replaces the observer used for operation timing and outcomes. |
| 91 | func (s *Store) SetObserver(o Observer) { |
| 92 | s.observerMu.Lock() |
| 93 | defer s.observerMu.Unlock() |
| 94 | s.observer = o |
| 95 | } |
| 96 | |
| 97 | func (s *Store) observe(operation string, started time.Time, err error) { |
| 98 | s.observerMu.RLock() |
| 99 | defer s.observerMu.RUnlock() |
| 100 | if s.observer == nil { |
| 101 | return |
| 102 | } |
| 103 | outcome := "ok" |
| 104 | if err != nil { |
| 105 | outcome = "error" |
| 106 | } |
| 107 | s.observer.ObserveStorage(operation, outcome, time.Since(started)) |
| 108 | } |
| 109 | |
| 110 | // WithTx opens a transaction, calls fn and commits after fn succeeds. It rolls |
| 111 | // back on failure. The callback uses the supplied transaction for database |
| 112 | // work because it holds the store's sole connection until completion. |
| 113 | func (s *Store) WithTx(ctx context.Context, fn func(*sql.Tx) error) (err error) { |
| 114 | started := time.Now() |
| 115 | defer func() { s.observe("commit" , started, err) }() |
| 116 | tx, err := s.db.BeginTx(ctx, nil) |
| 117 | if err != nil { |
| 118 | return fmt.Errorf("begin tenant transaction: %w" , err) |
| 119 | } |
| 120 | defer func() { |
| 121 | rollbackErr := tx.Rollback() |
| 122 | if rollbackErr != nil && !errors.Is(rollbackErr, sql.ErrTxDone) { |
| 123 | err = errors.Join(err, rollbackErr) |
| 124 | } |
| 125 | }() |
| 126 | if err := fn(tx); err != nil { |
| 127 | return err |
| 128 | } |
| 129 | if err := tx.Commit(); err != nil { |
| 130 | return fmt.Errorf("commit tenant transaction: %w" , err) |
| 131 | } |
| 132 | return nil |
| 133 | } |
| 134 | |
| 135 | func exists(ctx context.Context, tx *sql.Tx, query string, args ...any) (bool, error) { |
| 136 | var value int |
| 137 | err := tx.QueryRowContext(ctx, query, args...).Scan(&value) |
| 138 | if errors.Is(err, sql.ErrNoRows) { |
| 139 | return false, nil |
| 140 | } |
| 141 | return err == nil, err |
| 142 | } |