Method Pos

db.go:559–590

Pos returns the current replication position of the database. The result is cached and invalidated when L0 LTX files change.

()

// Pos returns the current replication position of the database.
// The result is cached and invalidated when L0 LTX files change.
func (db *DB) Pos() (ltx.Pos, error) {
	db.pos.Lock()
	defer db.pos.Unlock()

	if db.pos.value != nil {
		return *db.pos.value, nil
	}

	minTXID, maxTXID, err := db.MaxLTX()
	if err != nil {
		return ltx.Pos{}, err
	} else if minTXID == 0 {
		return ltx.Pos{}, nil // no replication yet
	}

	ltxPath := db.LTXPath(0, minTXID, maxTXID)
	f, err := os.Open(ltxPath)
	if err != nil {
		return ltx.Pos{}, NewLTXError("open", ltxPath, 0, uint64(minTXID), uint64(maxTXID), err)
	}
	defer func() { _ = f.Close() }()

	dec := ltx.NewDecoder(f)
	if err := dec.Verify(); err != nil {
		return ltx.Pos{}, NewLTXError("verify", ltxPath, 0, uint64(minTXID), uint64(maxTXID), fmt.Errorf("%w: %w", ErrLTXCorrupted, err))
	}

	pos := dec.PostApplyPos()
	db.pos.value = &pos

	return pos, nil
}

// invalidatePosCache clears the cached position so the next call to Pos()
// recomputes it from disk. Call this when L0 LTX files are deleted or