query_history(async_service& service, blockchain_ptr chain, transaction_pool_ptr txpool, memory_buffer_ptr membuf) : strand_(service.get_service()), chain_(chain), txpool_(txpool), membuf_(membuf), stopped_(false) { }
poller::poller(async_service& service, blockchain& chain) : strand_(service.get_service()), chain_(chain), last_hash_end_(null_hash), last_block_hash_(null_hash) { }