mutableboost::shared_mutexm_lock;///< General lock.
std::set<h256>m_readySet;///< All blocks ready for chain-import.
std::set<h256>m_drainingSet;///< All blocks being imported.
std::vector<bytes>m_ready;///< List of blocks, in correct order, ready for chain-import.
std::set<h256>m_futureSet;///< Set of all blocks whose parents are not ready/in-chain.
std::multimap<h256,std::pair<h256,bytes>>m_future;///< For transactions that have an unknown parent; we map their parent hash to the block stuff, and insert once the block appears.