Method reserve

src/rpc/blockchain.cpp:2644–2652

    explicit CoinsViewScanReserver() : m_could_reserve(false) {}

    bool reserve() {
        CHECK_NONFATAL(!m_could_reserve);
        if (g_scan_in_progress.exchange(true)) {
            return false;
        }
        CHECK_NONFATAL(g_scan_progress == 0);
        m_could_reserve = true;
        return true;
    }

    ~CoinsViewScanReserver() {
        if (m_could_reserve) {