server.cpp

/*
Minetest-c55
Copyright (C) 2010 celeron55, Perttu Ahola <celeron55@gmail.com>

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/

#include "server.h"
#include "utility.h"
#include <iostream>
#include "clientserver.h"
#include "map.h"
#include "jmutexautolock.h"
#include "main.h"
#include "constants.h"
#include "voxel.h"
#include "materials.h"
#include "mineral.h"

#define BLOCK_EMERGE_FLAG_FROMDISK (1<<0)

void * ServerThread::Thread()
{
	ThreadStarted();

	DSTACK(__FUNCTION_NAME);

	BEGIN_DEBUG_EXCEPTION_HANDLER

	while(getRun())
	{
		try{
			//TimeTaker timer("AsyncRunStep() + Receive()");

			{
				//TimeTaker timer("AsyncRunStep()");
				m_server->AsyncRunStep();
			}
		
			//dout_server<<"Running m_server->Receive()"<<std::endl;
			m_server->Receive();
		}
		catch(con::NoIncomingDataException &e)
		{
		}
		catch(con::PeerNotFoundException &e)
		{
			dout_server<<"Server: PeerNotFoundException"<<std::endl;
		}
	}
	
	END_DEBUG_EXCEPTION_HANDLER

	return NULL;
}

void * EmergeThread::Thread()
{
	ThreadStarted();

	DSTACK(__FUNCTION_NAME);

	bool debug=false;
	
	BEGIN_DEBUG_EXCEPTION_HANDLER

	/*
		Get block info from queue, emerge them and send them
		to clients.

		After queue is empty, exit.
	*/
	while(getRun())
	{
		QueuedBlockEmerge *qptr = m_server->m_emerge_queue.pop();
		if(qptr == NULL)
			break;
		
		SharedPtr<QueuedBlockEmerge> q(qptr);

		v3s16 &p = q->pos;
		
		//derr_server<<"EmergeThread::Thread(): running"<<std::endl;

		//TimeTaker timer("block emerge");
		
		/*
			Try to emerge it from somewhere.

			If it is only wanted as optional, only loading from disk
			will be allowed.
		*/
		
		/*
			Check if any peer wants it as non-optional. In that case it
			will be generated.

			Also decrement the emerge queue count in clients.
		*/

		bool optional = true;

		{
			core::map<u16, u8>::Iterator i;
			for(i=q->peer_ids.getIterator(); i.atEnd()==false; i++)
			{
				//u16 peer_id = i.getNode()->getKey();

				// Check flags
				u8 flags = i.getNode()->getValue();
				if((flags & BLOCK_EMERGE_FLAG_FROMDISK) == false)
					optional = false;
				
			}
		}

		/*dstream<<"EmergeThread: p="
				<<"("<<p.X<<","<<p.Y<<","<<p.Z<<") "
				<<"optional="<<optional<<std::endl;*/
		
		ServerMap &map = ((ServerMap&)m_server->m_env.getMap());
			
		core::map<v3s16, MapBlock*> changed_blocks;
		core::map<v3s16, MapBlock*> lighting_invalidated_blocks;

		MapBlock *block = NULL;
		bool got_block = true;
		core::map<v3s16, MapBlock*> modified_blocks;
		
		{//envlock

		//TimeTaker envlockwaittimer("block emerge envlock wait time");
		
		// 0-50ms
		JMutexAutoLock envlock(m_server->m_env_mutex);

		//envlockwaittimer.stop();

		//TimeTaker timer("block emerge (while env locked)");
			
		try{
			bool only_from_disk = false;
			
			if(optional)
				only_from_disk = true;
			
			// First check if the block already exists
			//block = map.getBlockNoCreate(p);

			if(block == NULL)
			{
				//dstream<<"Calling emergeBlock"<<std::endl;
				block = map.emergeBlock(
						p,
						only_from_disk,
						changed_blocks,
						lighting_invalidated_blocks);
			}

			// If it is a dummy, block was not found on disk
			if(block->isDummy())
			{
				//dstream<<"EmergeThread: Got a dummy block"<<std::endl;
				got_block = false;

				if(only_from_disk == false)
				{
					dstream<<"EmergeThread: wanted to generate a block but got a dummy"<<std::endl;
					assert(0);
				}
			}
		}
		catch(InvalidPositionException &e)
		{
			// Block not found.
			// This happens when position is over limit.
			got_block = false;
		}
		
		if(got_block)
		{
			if(debug && changed_blocks.size() > 0)
			{
				dout_server<<DTIME<<"Got changed_blocks: ";
				for(core::map<v3s16, MapBlock*>::Iterator i = changed_blocks.getIterator();
						i.atEnd() == false; i++)
				{
					MapBlock *block = i.getNode()->getValue();
					v3s16 p = block->getPos();
					dout_server<<"("<<p.X<<","<<p.Y<<","<<p.Z<<") ";
				}
				dout_server<<std::endl;
			}

			/*
				Collect a list of blocks that have been modified in
				addition to the fetched one.
			*/

			// Add all the "changed blocks" to modified_blocks
			for(core::map<v3s16, MapBlock*>::Iterator i = changed_blocks.getIterator();
					i.atEnd() == false; i++)
			{
				MapBlock *block = i.getNode()->getValue();
				modified_blocks.insert(block->getPos(), block);
			}
			
			/*dstream<<"lighting "<<lighting_invalidated_blocks.size()
					<<" blocks"<<std::endl;*/
			
			//TimeTaker timer("** updateLighting");
			
			// Update lighting without locking the environment mutex,
			// add modified blocks to changed blocks
			map.updateLighting(lighting_invalidated_blocks, modified_blocks);
		}
		// If we got no block, there should be no invalidated blocks
		else
		{
			assert(lighting_invalidated_blocks.size() == 0);
		}

		}//envlock

		/*
			Set sent status of modified blocks on clients
		*/
	
		// NOTE: Server's clients are also behind the connection mutex
		JMutexAutoLock lock(m_server->m_con_mutex);

		/*
			Add the originally fetched block to the modified list
		*/
		if(got_block)
		{
			modified_blocks.insert(p, block);
		}
		
		/*
			Set the modified blocks unsent for all the clients
		*/
		
		for(core::map<u16, RemoteClient*>::Iterator
				i = m_server->m_clients.getIterator();
				i.atEnd() == false; i++)
		{
			RemoteClient *client = i.getNode()->getValue();
			
			if(modified_blocks.size() > 0)
			{
				// Remove block from sent history
				client->SetBlocksNotSent(modified_blocks);
			}
		}
		
	}

	END_DEBUG_EXCEPTION_HANDLER

	return NULL;
}

void RemoteClient::GetNextBlocks(Server *server, float dtime,
		core::array<PrioritySortedBlockTransfer> &dest)
{
	DSTACK(__FUNCTION_NAME);
	
	// Increment timers
	m_nearest_unsent_reset_timer += dtime;

	// Won't send anything if already sending
	if(m_blocks_sending.size() >= g_settings.getU16
			("max_simultaneous_block_sends_per_client"))
	{
		//dstream<<"Not sending any blocks, Queue full."<<std::endl;
		return;
	}

	Player *player = server->m_env.getPlayer(peer_id);

	assert(player != NULL);

	v3f playerpos = player->getPosition();
	v3f playerspeed = player->getSpeed();

	v3s16 center_nodepos = floatToInt(playerpos, BS);

	v3s16 center = getNodeBlockPos(center_nodepos);
	
	// Camera position and direction
	v3f camera_pos =
			playerpos + v3f(0, BS+BS/2, 0);
	v3f camera_dir = v3f(0,0,1);
	camera_dir.rotateYZBy(player->getPitch());
	camera_dir.rotateXZBy(player->getYaw());

	/*
		Get the starting value of the block finder radius.
	*/
	s16 last_nearest_unsent_d;
	s16 d_start;
		
	if(m_last_center != center)
	{
		m_nearest_unsent_d = 0;
		m_last_center = center;
	}

	/*dstream<<"m_nearest_unsent_reset_timer="
			<<m_nearest_unsent_reset_timer<<std::endl;*/
	if(m_nearest_unsent_reset_timer > 5.0)
	{
		m_nearest_unsent_reset_timer = 0;
		m_nearest_unsent_d = 0;
		//dstream<<"Resetting m_nearest_unsent_d"<<std::endl;
	}

	last_nearest_unsent_d = m_nearest_unsent_d;
	
	d_start = m_nearest_unsent_d;

	u16 maximum_simultaneous_block_sends_setting = g_settings.getU16
			("max_simultaneous_block_sends_per_client");
	u16 maximum_simultaneous_block_sends = 
			maximum_simultaneous_block_sends_setting;

	/*
		Check the time from last addNode/removeNode.
		
		Decrease send rate if player is building stuff.
	*/
	m_time_from_building += dtime;
	if(m_time_from_building < g_settings.getFloat(
				"full_block_send_enable_min_time_from_building"))
	{
		maximum_simultaneous_block_sends
			= LIMITED_MAX_SIMULTANEOUS_BLOCK_SENDS;
	}
	
	u32 num_blocks_selected = m_blocks_sending.size();
	
	/*
		next time d will be continued from the d from which the nearest
		unsent block was found this time.

		This is because not necessarily any of the blocks found this
		time are actually sent.
	*/
	s32 new_nearest_unsent_d = -1;

	s16 d_max = g_settings.getS16("max_block_send_distance");
	s16 d_max_gen = g_settings.getS16("max_block_generate_distance");
	
	//dstream<<"Starting from "<<d_start<<std::endl;

	for(s16 d = d_start; d <= d_max; d++)
	{
		//dstream<<"RemoteClient::SendBlocks(): d="<<d<<std::endl;
		
		/*
			If m_nearest_unsent_d was changed by the EmergeThread
			(it can change it to 0 through SetBlockNotSent),
			update our d to it.
			Else update m_nearest_unsent_d
		*/
		if(m_nearest_unsent_d != last_nearest_unsent_d)
		{
			d = m_nearest_unsent_d;
			last_nearest_unsent_d = m_nearest_unsent_d;
		}

		/*
			Get the border/face dot coordinates of a "d-radiused"
			box
		*/
		core::list<v3s16> list;
		getFacePositions(list, d);
		
		core::list<v3s16>::Iterator li;
		for(li=list.begin(); li!=list.end(); li++)
		{
			v3s16 p = *li + center;
			
			/*
				Send throttling
				- Don't allow too many simultaneous transfers
				- EXCEPT when the blocks are very close

				Also, don't send blocks that are already flying.
			*/
			
			u16 maximum_simultaneous_block_sends_now =
					maximum_simultaneous_block_sends;
			
			if(d <= BLOCK_SEND_DISABLE_LIMITS_MAX_D)
			{
				maximum_simultaneous_block_sends_now =
						maximum_simultaneous_block_sends_setting;
			}

			// Limit is dynamically lowered when building
			if(num_blocks_selected
					>= maximum_simultaneous_block_sends_now)
			{
				/*dstream<<"Not sending more blocks. Queue full. "
						<<m_blocks_sending.size()
						<<std::endl;*/
				goto queue_full;
			}

			if(m_blocks_sending.find(p) != NULL)
				continue;
		
			/*
				Do not go over-limit
			*/
			if(p.X < -MAP_GENERATION_LIMIT / MAP_BLOCKSIZE
			|| p.X > MAP_GENERATION_LIMIT / MAP_BLOCKSIZE
			|| p.Y < -MAP_GENERATION_LIMIT / MAP_BLOCKSIZE
			|| p.Y > MAP_GENERATION_LIMIT / MAP_BLOCKSIZE
			|| p.Z < -MAP_GENERATION_LIMIT / MAP_BLOCKSIZE
			|| p.Z > MAP_GENERATION_LIMIT / MAP_BLOCKSIZE)
				continue;
		
			// If this is true, inexistent block will be made from scratch
			bool generate = d <= d_max_gen;
			
			{
				/*// Limit the generating area vertically to 2/3
				if(abs(p.Y - center.Y) > d_max_gen - d_max_gen / 3)
					generate = false;*/

				// Limit the send area vertically to 2/3
				if(abs(p.Y - center.Y) > d_max_gen - d_max_gen / 3)
					continue;
			}

#if 0
			/*
				If block is far away, don't generate it unless it is
				near ground level

				NOTE: We can't know the ground level this way with the
				new generator.
			*/
			if(d > 4)
			{
				v2s16 p2d(p.X, p.Z);
				MapSector *sector = NULL;
				try
				{
					sector = server->m_env.getMap().getSectorNoGenerate(p2d);
				}
				catch(InvalidPositionException &e)
				{
				}

				if(sector != NULL)
				{
					// Get center ground height in nodes
					f32 gh = sector->getGroundHeight(
							v2s16(MAP_BLOCKSIZE/2, MAP_BLOCKSIZE/2));
					// Block center y in nodes
					f32 y = (f32)(p.Y * MAP_BLOCKSIZE + MAP_BLOCKSIZE/2);
					// If differs a lot, don't generate
					if(fabs(gh - y) > MAP_BLOCKSIZE*2)
						generate = false;
				}
			}
#endif

			/*
				Don't generate or send if not in sight
			*/

			if(isBlockInSight(p, camera_pos, camera_dir, 10000*BS) == false)
			{
				continue;
			}
			
			/*
				Don't send already sent blocks
			*/
			{
				if(m_blocks_sent.find(p) != NULL)
					continue;
			}

			/*
				Check if map has this block
			*/
			MapBlock *block = server->m_env.getMap().getBlockNoCreateNoEx(p);
			
			bool surely_not_found_on_disk = false;
			bool block_is_invalid = false;
			if(block != NULL)
			{
				if(block->isDummy())
				{
					surely_not_found_on_disk = true;
				}

				if(block->isValid() == false)
				{
					block_is_invalid = true;
				}
				
				v2s16 p2d(p.X, p.Z);
				ServerMap *map = (ServerMap*)(&server->m_env.getMap());
				v2s16 chunkpos = map->sector_to_chunk(p2d);
				if(map->chunkNonVolatile(chunkpos) == false)
					block_is_invalid = true;
			}

			/*
				If block has been marked to not exist on disk (dummy)
				and generating new ones is not wanted, skip block.
			*/
			if(generate == false && surely_not_found_on_disk == true)
			{
				// get next one.
				continue;
			}

			/*
				Record the lowest d from which a a block has been
				found being not sent and possibly to exist
			*/
			if(new_nearest_unsent_d == -1 || d < new_nearest_unsent_d)
			{
				new_nearest_unsent_d = d;
			}
					
			/*
				Add inexistent block to emerge queue.
			*/
			if(block == NULL || surely_not_found_on_disk || block_is_invalid)
			{
				//TODO: Get value from somewhere
				// Allow only one block in emerge queue
				if(server->m_emerge_queue.peerItemCount(peer_id) < 1)
				{
					//dstream<<"Adding block to emerge queue"<<std::endl;
					
					// Add it to the emerge queue and trigger the thread
					
					u8 flags = 0;
					if(generate == false)
						flags |= BLOCK_EMERGE_FLAG_FROMDISK;
					
					server->m_emerge_queue.addBlock(peer_id, p, flags);
					server->m_emergethread.trigger();
				}
				
				// get next one.
				continue;
			}

			/*
				Add block to send queue
			*/

			PrioritySortedBlockTransfer q((float)d, p, peer_id);

			dest.push_back(q);

			num_blocks_selected += 1;
		}
	}
queue_full:

	if(new_nearest_unsent_d != -1)
	{
		m_nearest_unsent_d = new_nearest_unsent_d;
	}
}

void RemoteClient::SendObjectData(
		Server *server,
		float dtime,
		core::map<v3s16, bool> &stepped_blocks
	)
{
	DSTACK(__FUNCTION_NAME);

	// Can't send anything without knowing version
	if(serialization_version == SER_FMT_VER_INVALID)
	{
		dstream<<"RemoteClient::SendObjectData(): Not sending, no version."
				<<std::endl;
		return;
	}

	/*
		Send a TOCLIENT_OBJECTDATA packet.
		Sent as unreliable.

		u16 command
		u16 number of player positions
		for each player:
			v3s32 position*100
			v3s32 speed*100
			s32 pitch*100
			s32 yaw*100
		u16 count of blocks
		for each block:
			block objects
	*/

	std::ostringstream os(std::ios_base::binary);
	u8 buf[12];
	
	// Write command
	writeU16(buf, TOCLIENT_OBJECTDATA);
	os.write((char*)buf, 2);
	
	/*
		Get and write player data
	*/
	
	// Get connected players
	core::list<Player*> players = server->m_env.getPlayers(true);

	// Write player count
	u16 playercount = players.size();
	writeU16(buf, playercount);
	os.write((char*)buf, 2);

	core::list<Player*>::Iterator i;
	for(i = players.begin();
			i != players.end(); i++)
	{
		Player *player = *i;

		v3f pf = player->getPosition();
		v3f sf = player->getSpeed();

		v3s32 position_i(pf.X*100, pf.Y*100, pf.Z*100);
		v3s32 speed_i   (sf.X*100, sf.Y*100, sf.Z*100);
		s32   pitch_i   (player->getPitch() * 100);
		s32   yaw_i     (player->getYaw() * 100);
		
		writeU16(buf, player->peer_id);
		os.write((char*)buf, 2);
		writeV3S32(buf, position_i);
		os.write((char*)buf, 12);
		writeV3S32(buf, speed_i);
		os.write((char*)buf, 12);
		writeS32(buf, pitch_i);
		os.write((char*)buf, 4);
		writeS32(buf, yaw_i);
		os.write((char*)buf, 4);
	}
	
	/*
		Get and write object data
	*/

	/*
		Get nearby blocks.
		
		For making players to be able to build to their nearby
		environment (building is not possible on blocks that are not
		in memory):
		- Set blocks changed
		- Add blocks to emerge queue if they are not found

		SUGGESTION: These could be ignored from the backside of the player
	*/

	Player *player = server->m_env.getPlayer(peer_id);

	assert(player);

	v3f playerpos = player->getPosition();
	v3f playerspeed = player->getSpeed();

	v3s16 center_nodepos = floatToInt(playerpos, BS);
	v3s16 center = getNodeBlockPos(center_nodepos);

	s16 d_max = g_settings.getS16("active_object_range");
	
	// Number of blocks whose objects were written to bos
	u16 blockcount = 0;

	std::ostringstream bos(std::ios_base::binary);

	for(s16 d = 0; d <= d_max; d++)
	{
		core::list<v3s16> list;
		getFacePositions(list, d);
		
		core::list<v3s16>::Iterator li;
		for(li=list.begin(); li!=list.end(); li++)
		{
			v3s16 p = *li + center;

			/*
				Ignore blocks that haven't been sent to the client
			*/
			{
				if(m_blocks_sent.find(p) == NULL)
					continue;
			}
			
			// Try stepping block and add it to a send queue
			try
			{

			// Get block
			MapBlock *block = server->m_env.getMap().getBlockNoCreate(p);

			/*
				Step block if not in stepped_blocks and add to stepped_blocks.
			*/
			if(stepped_blocks.find(p) == NULL)
			{
				block->stepObjects(dtime, true, server->getDayNightRatio());
				stepped_blocks.insert(p, true);
				block->setChangedFlag();
			}

			// Skip block if there are no objects
			if(block->getObjectCount() == 0)
				continue;
			
			/*
				Write objects
			*/

			// Write blockpos
			writeV3S16(buf, p);
			bos.write((char*)buf, 6);

			// Write objects
			block->serializeObjects(bos, serialization_version);

			blockcount++;

			/*
				Stop collecting objects if data is already too big
			*/
			// Sum of player and object data sizes
			s32 sum = (s32)os.tellp() + 2 + (s32)bos.tellp();
			// break out if data too big
			if(sum > MAX_OBJECTDATA_SIZE)
			{
				goto skip_subsequent;
			}
			
			} //try
			catch(InvalidPositionException &e)
			{
				// Not in memory
				// Add it to the emerge queue and trigger the thread.
				// Fetch the block only if it is on disk.
				
				// Grab and increment counter
				/*SharedPtr<JMutexAutoLock> lock
						(m_num_blocks_in_emerge_queue.getLock());
				m_num_blocks_in_emerge_queue.m_value++;*/
				
				// Add to queue as an anonymous fetch from disk
				u8 flags = BLOCK_EMERGE_FLAG_FROMDISK;
				server->m_emerge_queue.addBlock(0, p, flags);
				server->m_emergethread.trigger();
			}
		}
	}

skip_subsequent:

	// Write block count
	writeU16(buf, blockcount);
	os.write((char*)buf, 2);

	// Write block objects
	os<<bos.str();

	/*
		Send data
	*/
	
	//dstream<<"Server: Sending object data to "<<peer_id<<std::endl;

	// Make data buffer
	std::string s = os.str();
	SharedBuffer<u8> data((u8*)s.c_str(), s.size());
	// Send as unreliable
	server->m_con.Send(peer_id, 0, data, false);
}

void RemoteClient::GotBlock(v3s16 p)
{
	if(m_blocks_sending.find(p) != NULL)
		m_blocks_sending.remove(p);
	else
	{
		/*dstream<<"RemoteClient::GotBlock(): Didn't find in"
				" m_blocks_sending"<<std::endl;*/
		m_excess_gotblocks++;
	}
	m_blocks_sent.insert(p, true);
}

void RemoteClient::SentBlock(v3s16 p)
{
	if(m_blocks_sending.find(p) == NULL)
		m_blocks_sending.insert(p, 0.0);
	else
		dstream<<"RemoteClient::SentBlock(): Sent block"
				" already in m_blocks_sending"<<std::endl;
}

void RemoteClient::SetBlockNotSent(v3s16 p)
{
	m_nearest_unsent_d = 0;
	
	if(m_blocks_sending.find(p) != NULL)
		m_blocks_sending.remove(p);
	if(m_blocks_sent.find(p) != NULL)
		m_blocks_sent.remove(p);
}

void RemoteClient::SetBlocksNotSent(core::map<v3s16, MapBlock*> &blocks)
{
	m_nearest_unsent_d = 0;
	
	for(core::map<v3s16, MapBlock*>::Iterator
			i = blocks.getIterator();
			i.atEnd()==false; i++)
	{
		v3s16 p = i.getNode()->getKey();

		if(m_blocks_sending.find(p) != NULL)
			m_blocks_sending.remove(p);
		if(m_blocks_sent.find(p) != NULL)
			m_blocks_sent.remove(p);
	}
}

/*
	PlayerInfo
*/

PlayerInfo::PlayerInfo()
{
	name[0] = 0;
}

void PlayerInfo::PrintLine(std::ostream *s)
{
	(*s)<<id<<": ";
	(*s)<<"\""<<name<<"\" ("
			<<(position.X/10)<<","<<(position.Y/10)
			<<","<<(position.Z/10)<<") ";
	address.print(s);
	(*s)<<" avg_rtt="<<avg_rtt;
	(*s)<<std::endl;
}

u32 PIChecksum(core::list<PlayerInfo> &l)
{
	core::list<PlayerInfo>::Iterator i;
	u32 checksum = 1;
	u32 a = 10;
	for(i=l.begin(); i!=l.end(); i++)
	{
		checksum += a * (i->id+1);
		checksum ^= 0x435aafcd;
		a *= 10;
	}
	return checksum;
}

/*
	Server
*/

Server::Server(
		std::string mapsavedir
	):
	m_env(new ServerMap(mapsavedir), this),
	m_con(PROTOCOL_ID, 512, CONNECTION_TIMEOUT, this),
	m_thread(this),
	m_emergethread(this),
	m_time_of_day(9000),
	m_time_counter(0),
	m_time_of_day_send_timer(0),
	m_uptime(0),
	m_mapsavedir(mapsavedir),
	m_shutdown_requested(false),
	m_ignore_map_edit_events(false),
	m_ignore_map_edit_events_peer_id(0)
{
	m_liquid_transform_timer = 0.0;
	m_print_info_timer = 0.0;
	m_objectdata_timer = 0.0;
	m_emergethread_trigger_timer = 0.0;
	m_savemap_timer = 0.0;
	
	m_env_mutex.Init();
	m_con_mutex.Init();
	m_step_dtime_mutex.Init();
	m_step_dtime = 0.0;

	m_env.getMap().addEventReceiver(this);

	// Load players
	m_env.deSerializePlayers(m_mapsavedir);
}

Server::~Server()
{
	/*
		Send shutdown message
	*/
	{
		JMutexAutoLock conlock(m_con_mutex);
		
		std::wstring line = L"*** Server shutting down";

		/*
			Send the message to clients
		*/
		for(core::map<u16, RemoteClient*>::Iterator
			i = m_clients.getIterator();
			i.atEnd() == false; i++)
		{
			// Get client and check that it is valid
			RemoteClient *client = i.getNode()->getValue();
			assert(client->peer_id == i.getNode()->getKey());
			if(client->serialization_version == SER_FMT_VER_INVALID)
				continue;

			SendChatMessage(client->peer_id, line);
		}
	}

	/*
		Save players
	*/
	m_env.serializePlayers(m_mapsavedir);
	
	/*
		Stop threads
	*/
	stop();
	
	/*
		Delete clients
	*/
	{
		JMutexAutoLock clientslock(m_con_mutex);

		for(core::map<u16, RemoteClient*>::Iterator
			i = m_clients.getIterator();
			i.atEnd() == false; i++)
		{
			/*// Delete player
			// NOTE: These are removed by env destructor
			{
				u16 peer_id = i.getNode()->getKey();
				JMutexAutoLock envlock(m_env_mutex);
				m_env.removePlayer(peer_id);
			}*/
			
			// Delete client
			delete i.getNode()->getValue();
		}
	}
}

void Server::start(unsigned short port)
{
	DSTACK(__FUNCTION_NAME);
	// Stop thread if already running
	m_thread.stop();
	
	// Initialize connection
	m_con.setTimeoutMs(30);
	m_con.Serve(port);

	// Start thread
	m_thread.setRun(true);
	m_thread.Start();