Method doDiscover

src/cpp-ethereum/libp2p/NodeTable.cpp:155–215

}

void NodeTable::doDiscover(NodeID _node, unsigned _round, shared_ptr<set<shared_ptr<NodeEntry>>> _tried)
{
	// NOTE: ONLY called by doDiscovery!
	
	if (!m_socketPointer->isOpen())
		return;
	
	if (_round == s_maxSteps)
	{
		clog(NodeTableEvent) << "Terminating discover after " << _round << " rounds.";
		doDiscovery();
		return;
	}
	else if (!_round && !_tried)
		// initialized _tried on first round
		_tried = make_shared<set<shared_ptr<NodeEntry>>>();
	
	auto nearest = nearestNodeEntries(_node);
	list<shared_ptr<NodeEntry>> tried;
	for (unsigned i = 0; i < nearest.size() && tried.size() < s_alpha; i++)
		if (!_tried->count(nearest[i]))
		{
			auto r = nearest[i];
			tried.push_back(r);
			FindNode p(r->endpoint, _node);
			p.sign(m_secret);
			DEV_GUARDED(x_findNodeTimeout)
				m_findNodeTimeout.push_back(make_pair(r->id, chrono::steady_clock::now()));
			m_socketPointer->send(p);
		}
	
	if (tried.empty())
	{
		clog(NodeTableEvent) << "Terminating discover after " << _round << " rounds.";
		doDiscovery();
		return;
	}
		
	while (!tried.empty())
	{
		_tried->insert(tried.front());
		tried.pop_front();
	}

	m_timers.schedule(c_reqTimeout.count() * 2, [this, _node, _round, _tried](boost::system::error_code const& _ec)
	{
		if (_ec)
			clog(NodeTableMessageDetail) << "Discovery timer was probably cancelled: " << _ec.value() << _ec.message();

		if (_ec.value() == boost::asio::error::operation_aborted || m_timers.isStopped())
			return;

		// error::operation_aborted means that the timer was probably aborted. 
		// It usually happens when "this" object is deallocated, in which case 
		// subsequent call to doDiscover() would cause a crash. We can not rely on 
		// m_timers.isStopped(), because "this" pointer was captured by the lambda,
		// and therefore, in case of deallocation m_timers object no longer exists.