Remove unnecessary copies (#2026)

nano/nano_node/entry.cpp

@@ -242,15 +242,15 @@ int main (int argc, char * const * argv)
 			nano::uint128_t total;
 			for (auto i (node.node->store.representation_begin (transaction)), n (node.node->store.representation_end ()); i != n; ++i)
 			{
-				nano::account account (i->first);
+				nano::account const & account (i->first);
 				auto amount (node.node->store.representation_get (transaction, account));
 				total += amount;
 				std::cout << boost::str (boost::format ("%1% %2% %3%\n") % account.to_account () % amount.convert_to<std::string> () % total.convert_to<std::string> ());
 			}
 			std::map<nano::account, nano::uint128_t> calculated;
 			for (auto i (node.node->store.latest_begin (transaction)), n (node.node->store.latest_end ()); i != n; ++i)
 			{
-				nano::account_info info (i->second);
+				nano::account_info const & info (i->second);
 				nano::block_hash rep_block (node.node->ledger.representative_calculated (transaction, info.head));
 				auto block (node.node->store.block_get (transaction, rep_block));
 				calculated[block->representative ()] += info.balance.number ();
@@ -783,8 +783,8 @@ int main (int argc, char * const * argv)
 				{
 					std::cout << boost::str (boost::format ("%1% accounts validated\n") % count);
 				}
-				nano::account_info info (i->second);
-				nano::account account (i->first);
+				nano::account_info const & info (i->second);
+				nano::account const & account (i->first);
 
 				if (info.confirmation_height > info.block_count)
 				{
@@ -885,8 +885,8 @@ int main (int argc, char * const * argv)
 				{
 					std::cout << boost::str (boost::format ("%1% pending blocks validated\n") % count);
 				}
-				nano::pending_key key (i->first);
-				nano::pending_info info (i->second);
+				nano::pending_key const & key (i->first);
+				nano::pending_info const & info (i->second);
 				// Check block existance
 				auto block (node.node->store.block_get (transaction, key.hash));
 				if (block == nullptr)
@@ -947,8 +947,8 @@ int main (int argc, char * const * argv)
 				std::cout << boost::str (boost::format ("Performing bootstrap emulation, %1% blocks in ledger...") % block_count) << std::endl;
 				for (auto i (node.node->store.latest_begin (transaction)), n (node.node->store.latest_end ()); i != n; ++i)
 				{
-					nano::account account (i->first);
-					nano::account_info info (i->second);
+					nano::account const & account (i->first);
+					nano::account_info const & info (i->second);
 					auto hash (info.head);
 					while (!hash.is_zero ())
 					{
@@ -1006,7 +1006,7 @@ int main (int argc, char * const * argv)
 			uint64_t sum = 0;
 			for (auto i (node.node->store.latest_begin (transaction)), n (node.node->store.latest_end ()); i != n; ++i)
 			{
-				nano::account_info info (i->second);
+				nano::account_info const & info (i->second);
 				sum += info.confirmation_height;
 			}
 			std::cout << "Total cemented block count: " << sum << std::endl;

nano/node/active_transactions.cpp

@@ -44,7 +44,7 @@ void nano::active_transactions::confirm_frontiers (nano::transaction const & tra
 		size_t elections_count (0);
 		for (auto i (node.store.latest_begin (transaction_a, next_frontier_account)), n (node.store.latest_end ()); i != n && !stopped && elections_count < max_elections; ++i)
 		{
-			nano::account_info info (i->second);
+			nano::account_info const & info (i->second);
 			if (info.block_count != info.confirmation_height)
 			{
 				auto block (node.store.block_get (transaction_a, info.head));

nano/node/blockprocessor.cpp

@@ -137,12 +137,12 @@ void nano::block_processor::verify_state_blocks (nano::transaction const & trans
 	std::deque<nano::unchecked_info> items;
 	for (auto i (0); i < max_count && !state_blocks.empty (); i++)
 	{
-		auto item (state_blocks.front ());
-		state_blocks.pop_front ();
+		auto & item (state_blocks.front ());
 		if (!node.ledger.store.block_exists (transaction_a, item.block->type (), item.block->hash ()))
 		{
-			items.push_back (item);
+			items.push_back (std::move (item));
 		}
+		state_blocks.pop_front ();
 	}
 	lock_a.unlock ();
 	if (!items.empty ())
@@ -166,7 +166,7 @@ void nano::block_processor::verify_state_blocks (nano::transaction const & trans
 		verifications.resize (size, 0);
 		for (auto i (0); i < size; ++i)
 		{
-			auto item (items[i]);
+			auto & item (items[i]);
 			hashes.push_back (item.block->hash ());
 			messages.push_back (hashes.back ().bytes.data ());
 			lengths.push_back (sizeof (decltype (hashes)::value_type));
@@ -190,27 +190,27 @@ void nano::block_processor::verify_state_blocks (nano::transaction const & trans
 		for (auto i (0); i < size; ++i)
 		{
 			assert (verifications[i] == 1 || verifications[i] == 0);
-			auto item (items.front ());
+			auto & item (items.front ());
 			if (!item.block->link ().is_zero () && node.ledger.is_epoch_link (item.block->link ()))
 			{
 				// Epoch blocks
 				if (verifications[i] == 1)
 				{
 					item.verified = nano::signature_verification::valid_epoch;
-					blocks.push_back (item);
+					blocks.push_back (std::move (item));
 				}
 				else
 				{
 					// Possible regular state blocks with epoch link (send subtype)
 					item.verified = nano::signature_verification::unknown;
-					blocks.push_back (item);
+					blocks.push_back (std::move (item));
 				}
 			}
 			else if (verifications[i] == 1)
 			{
 				// Non epoch blocks
 				item.verified = nano::signature_verification::valid;
-				blocks.push_back (item);
+				blocks.push_back (std::move (item));
 			}
 			items.pop_front ();
 		}

nano/node/bootstrap.cpp

@@ -256,21 +256,22 @@ void nano::frontier_req_client::next (nano::transaction const & transaction_a)
 		size_t max_size (128);
 		for (auto i (connection->node->store.latest_begin (transaction_a, current.number () + 1)), n (connection->node->store.latest_end ()); i != n && accounts.size () != max_size; ++i)
 		{
-			nano::account_info info (i->second);
-			accounts.push_back (std::make_pair (nano::account (i->first), info.head));
+			nano::account_info const & info (i->second);
+			nano::account const & account (i->first);
+			accounts.emplace_back (account, info.head);
 		}
 		/* If loop breaks before max_size, then latest_end () is reached
 		Add empty record to finish frontier_req_server */
 		if (accounts.size () != max_size)
 		{
-			accounts.push_back (std::make_pair (nano::account (0), nano::block_hash (0)));
+			accounts.emplace_back (nano::account (0), nano::block_hash (0));
 		}
 	}
 	// Retrieving accounts from deque
-	auto account_pair (accounts.front ());
-	accounts.pop_front ();
+	auto const & account_pair (accounts.front ());
 	current = account_pair.first;
 	frontier = account_pair.second;
+	accounts.pop_front ();
 }
 
 nano::bulk_pull_client::bulk_pull_client (std::shared_ptr<nano::bootstrap_client> connection_a, nano::pull_info const & pull_a) :
@@ -3234,24 +3235,25 @@ void nano::frontier_req_server::next ()
 		auto transaction (connection->node->store.tx_begin_read ());
 		for (auto i (connection->node->store.latest_begin (transaction, current.number () + 1)), n (connection->node->store.latest_end ()); i != n && accounts.size () != max_size; ++i)
 		{
-			nano::account_info info (i->second);
+			nano::account_info const & info (i->second);
 			if (!skip_old || (now - info.modified) <= request->age)
 			{
-				accounts.push_back (std::make_pair (nano::account (i->first), info.head));
+				nano::account const & account (i->first);
+				accounts.emplace_back (account, info.head);
 			}
 		}
 		/* If loop breaks before max_size, then latest_end () is reached
 		Add empty record to finish frontier_req_server */
 		if (accounts.size () != max_size)
 		{
-			accounts.push_back (std::make_pair (nano::account (0), nano::block_hash (0)));
+			accounts.emplace_back (nano::account (0), nano::block_hash (0));
 		}
 	}
 	// Retrieving accounts from deque
-	auto account_pair (accounts.front ());
-	accounts.pop_front ();
+	auto const & account_pair (accounts.front ());
 	current = account_pair.first;
 	frontier = account_pair.second;
+	accounts.pop_front ();
 }
 
 void nano::pulls_cache::add (nano::pull_info const & pull_a)

nano/node/cli.cpp

@@ -603,7 +603,7 @@ std::error_code nano::handle_node_options (boost::program_options::variables_map
 						std::cout << boost::str (boost::format ("Seed: %1%\n") % seed.data.to_string ());
 						for (auto i (existing->second->store.begin (transaction)), m (existing->second->store.end ()); i != m; ++i)
 						{
-							nano::account account (i->first);
+							nano::account const & account (i->first);
 							nano::raw_key key;
 							auto error (existing->second->store.fetch (transaction, account, key));
 							assert (!error);
@@ -930,7 +930,7 @@ std::error_code nano::handle_node_options (boost::program_options::variables_map
 		auto transaction (node.node->store.tx_begin_read ());
 		for (auto i (node.node->store.vote_begin (transaction)), n (node.node->store.vote_end ()); i != n; ++i)
 		{
-			auto vote (i->second);
+			auto const & vote (i->second);
 			std::cerr << boost::str (boost::format ("%1%\n") % vote->to_json ());
 		}
 	}

nano/node/election.cpp

@@ -63,7 +63,7 @@ bool nano::election::have_quorum (nano::tally_t const & tally_a, nano::uint128_t
 	if (tally_sum >= node.config.online_weight_minimum.number ())
 	{
 		auto i (tally_a.begin ());
-		auto first (i->first);
+		auto const & first (i->first);
 		++i;
 		auto second (i != tally_a.end () ? i->first : 0);
 		auto delta_l (node.delta ());