server.cpp

/*
Minetest-c55
Copyright (C) 2010-2011 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 <queue>
#include "clientserver.h"
#include "map.h"
#include "jmutexautolock.h"
#include "main.h"
#include "constants.h"
#include "voxel.h"
#include "materials.h"
#include "mineral.h"
#include "config.h"
#include "servercommand.h"
#include "filesys.h"
#include "content_mapnode.h"
#include "content_craft.h"
#include "content_nodemeta.h"
#include "mapblock.h"
#include "serverobject.h"
#include "settings.h"
#include "profiler.h"
#include "log.h"
#include "script.h"
#include "scriptapi.h"
#include "nodedef.h"
#include "tooldef.h"
#include "craftdef.h"
#include "mapgen.h"

#define PP(x) "("<<(x).X<<","<<(x).Y<<","<<(x).Z<<")"

#define BLOCK_EMERGE_FLAG_FROMDISK (1<<0)

class MapEditEventIgnorer
{
public:
	MapEditEventIgnorer(bool *flag):
		m_flag(flag)
	{
		if(*m_flag == false)
			*m_flag = true;
		else
			m_flag = NULL;
	}

	~MapEditEventIgnorer()
	{
		if(m_flag)
		{
			assert(*m_flag);
			*m_flag = false;
		}
	}
	
private:
	bool *m_flag;
};

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

	log_register_thread("ServerThread");

	DSTACK(__FUNCTION_NAME);

	BEGIN_DEBUG_EXCEPTION_HANDLER

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

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

	return NULL;
}

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

	log_register_thread("EmergeThread");

	DSTACK(__FUNCTION_NAME);

	BEGIN_DEBUG_EXCEPTION_HANDLER

	bool enable_mapgen_debug_info = g_settings->getBool("enable_mapgen_debug_info");
	
	/*
		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;
		v2s16 p2d(p.X,p.Z);

		/*
			Do not generate over-limit
		*/
		if(blockpos_over_limit(p))
			continue;
			
		//infostream<<"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 only_from_disk = 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)
					only_from_disk = false;
				
			}
		}
		
		if(enable_mapgen_debug_info)
			infostream<<"EmergeThread: p="
					<<"("<<p.X<<","<<p.Y<<","<<p.Z<<") "
					<<"only_from_disk="<<only_from_disk<<std::endl;
		
		ServerMap &map = ((ServerMap&)m_server->m_env->getMap());
			
		MapBlock *block = NULL;
		bool got_block = true;
		core::map<v3s16, MapBlock*> modified_blocks;

		/*
			Try to fetch block from memory or disk.
			If not found and asked to generate, initialize generator.
		*/
		
		bool started_generate = false;
		mapgen::BlockMakeData data;

		{
			JMutexAutoLock envlock(m_server->m_env_mutex);
			
			// Load sector if it isn't loaded
			if(map.getSectorNoGenerateNoEx(p2d) == NULL)
				map.loadSectorMeta(p2d);
			
			// Attempt to load block
			block = map.getBlockNoCreateNoEx(p);
			if(!block || block->isDummy() || !block->isGenerated())
			{
				if(enable_mapgen_debug_info)
					infostream<<"EmergeThread: not in memory, "
							<<"attempting to load from disk"<<std::endl;

				block = map.loadBlock(p);
			}
			
			// If could not load and allowed to generate, start generation
			// inside this same envlock
			if(only_from_disk == false &&
					(block == NULL || block->isGenerated() == false)){
				if(enable_mapgen_debug_info)
					infostream<<"EmergeThread: generating"<<std::endl;
				started_generate = true;

				map.initBlockMake(&data, p);
			}
		}

		/*
			If generator was initialized, generate now when envlock is free.
		*/
		if(started_generate)
		{
			{
				ScopeProfiler sp(g_profiler, "EmergeThread: mapgen::make_block",
						SPT_AVG);
				TimeTaker t("mapgen::make_block()");

				mapgen::make_block(&data);

				if(enable_mapgen_debug_info == false)
					t.stop(true); // Hide output
			}
			
			{
				// Lock environment again to access the map
				JMutexAutoLock envlock(m_server->m_env_mutex);
				
				ScopeProfiler sp(g_profiler, "EmergeThread: after "
						"mapgen::make_block (envlock)", SPT_AVG);

				// Blit data back on map, update lighting, add mobs and
				// whatever this does
				map.finishBlockMake(&data, modified_blocks);

				// Get central block
				block = map.getBlockNoCreateNoEx(p);

				/*
					Do some post-generate stuff
				*/
				
				v3s16 minp = block->getPos()*MAP_BLOCKSIZE;
				v3s16 maxp = minp + v3s16(1,1,1)*(MAP_BLOCKSIZE-1);
				scriptapi_environment_on_generated(m_server->m_lua,
						minp, maxp);
				
				if(enable_mapgen_debug_info)
					infostream<<"EmergeThread: ended up with: "
							<<analyze_block(block)<<std::endl;

				/*
					Ignore map edit events, they will not need to be
					sent to anybody because the block hasn't been sent
					to anybody
				*/
				MapEditEventIgnorer ign(&m_server->m_ignore_map_edit_events);
				
				// Activate objects and stuff
				m_server->m_env->activateBlock(block, 3600);
			}
		}

		if(block == NULL)
			got_block = false;
			
		/*
			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(errorstream)

	log_deregister_thread();

	return NULL;
}

void RemoteClient::GetNextBlocks(Server *server, float dtime,
		core::array<PrioritySortedBlockTransfer> &dest)
{
	DSTACK(__FUNCTION_NAME);
	
	/*u32 timer_result;
	TimeTaker timer("RemoteClient::GetNextBlocks", &timer_result);*/
	
	// Increment timers
	m_nothing_to_send_pause_timer -= dtime;
	m_nearest_unsent_reset_timer += dtime;
	
	if(m_nothing_to_send_pause_timer >= 0)
	{
		return;
	}

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

	//TimeTaker timer("RemoteClient::GetNextBlocks");
	
	Player *player = server->m_env->getPlayer(peer_id);

	assert(player != NULL);

	v3f playerpos = player->getPosition();
	v3f playerspeed = player->getSpeed();
	v3f playerspeeddir(0,0,0);
	if(playerspeed.getLength() > 1.0*BS)
		playerspeeddir = playerspeed / playerspeed.getLength();
	// Predict to next block
	v3f playerpos_predicted = playerpos + playerspeeddir*MAP_BLOCKSIZE*BS;

	v3s16 center_nodepos = floatToInt(playerpos_predicted, BS);

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

	/*infostream<<"camera_dir=("<<camera_dir.X<<","<<camera_dir.Y<<","
			<<camera_dir.Z<<")"<<std::endl;*/

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

	/*infostream<<"m_nearest_unsent_reset_timer="
			<<m_nearest_unsent_reset_timer<<std::endl;*/
			
	// Reset periodically to workaround for some bugs or stuff
	if(m_nearest_unsent_reset_timer > 20.0)
	{
		m_nearest_unsent_reset_timer = 0;
		m_nearest_unsent_d = 0;
		//infostream<<"Resetting m_nearest_unsent_d for "
		//		<<server->getPlayerName(peer_id)<<std::endl;
	}

	//s16 last_nearest_unsent_d = m_nearest_unsent_d;
	s16 d_start = m_nearest_unsent_d;

	//infostream<<"d_start="<<d_start<<std::endl;

	u16 max_simul_sends_setting = g_settings->getU16
			("max_simultaneous_block_sends_per_client");
	u16 max_simul_sends_usually = max_simul_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"))
	{
		max_simul_sends_usually
			= LIMITED_MAX_SIMULTANEOUS_BLOCK_SENDS;
	}
	
	/*
		Number of blocks sending + number of blocks selected for sending
	*/
	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");
	
	// Don't loop very much at a time
	s16 max_d_increment_at_time = 2;
	if(d_max > d_start + max_d_increment_at_time)
		d_max = d_start + max_d_increment_at_time;
	/*if(d_max_gen > d_start+2)
		d_max_gen = d_start+2;*/
	
	//infostream<<"Starting from "<<d_start<<std::endl;

	s32 nearest_emerged_d = -1;
	s32 nearest_emergefull_d = -1;
	s32 nearest_sent_d = -1;
	bool queue_is_full = false;
	
	s16 d;
	for(d = d_start; d <= d_max; d++)
	{
		/*errorstream<<"checking d="<<d<<" for "
				<<server->getPlayerName(peer_id)<<std::endl;*/
		//infostream<<"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.
			*/
			
			// Start with the usual maximum
			u16 max_simul_dynamic = max_simul_sends_usually;
			
			// If block is very close, allow full maximum
			if(d <= BLOCK_SEND_DISABLE_LIMITS_MAX_D)
				max_simul_dynamic = max_simul_sends_setting;

			// Don't select too many blocks for sending
			if(num_blocks_selected >= max_simul_dynamic)
			{
				queue_is_full = true;
				goto queue_full_break;
			}
			
			// Don't send blocks that are currently being transferred
			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 1/2
				if(abs(p.Y - center.Y) > d_max / 2)
					continue;
			}

#if 0
			/*
				If block is far away, don't generate it unless it is
				near ground level.
			*/
			if(d >= 4)
			{
	#if 1
				// Block center y in nodes
				f32 y = (f32)(p.Y * MAP_BLOCKSIZE + MAP_BLOCKSIZE/2);
				// Don't generate if it's very high or very low
				if(y < -64 || y > 64)
					generate = false;
	#endif
	#if 0
				v2s16 p2d_nodes_center(
					MAP_BLOCKSIZE*p.X,
					MAP_BLOCKSIZE*p.Z);
				
				// Get ground height in nodes
				s16 gh = server->m_env->getServerMap().findGroundLevel(
						p2d_nodes_center);

				// If differs a lot, don't generate
				if(fabs(gh - y) > MAP_BLOCKSIZE*2)
					generate = false;
					// Actually, don't even send it
					//continue;
	#endif
			}
#endif

			//infostream<<"d="<<d<<std::endl;
#if 1
			/*
				Don't generate or send if not in sight
				FIXME This only works if the client uses a small enough
				FOV setting. The default of 72 degrees is fine.
			*/

			float camera_fov = (72.0*PI/180) * 4./3.;
			if(isBlockInSight(p, camera_pos, camera_dir, camera_fov, 10000*BS) == false)
			{
				continue;
			}
#endif
			/*
				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)
			{
				// Reset usage timer, this block will be of use in the future.
				block->resetUsageTimer();

				// Block is dummy if data doesn't exist.
				// It means it has been not found from disk and not generated
				if(block->isDummy())
				{
					surely_not_found_on_disk = true;
				}
				
				// Block is valid if lighting is up-to-date and data exists
				if(block->isValid() == false)
				{
					block_is_invalid = true;
				}
				
				/*if(block->isFullyGenerated() == false)
				{
					block_is_invalid = true;
				}*/

#if 0
				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;
#endif
				if(block->isGenerated() == false)
					block_is_invalid = true;
#if 1
				/*
					If block is not close, don't send it unless it is near
					ground level.

					Block is near ground level if night-time mesh
					differs from day-time mesh.
				*/
				if(d >= 4)
				{
					if(block->dayNightDiffed() == false)
						continue;
				}
#endif
			}

			/*
				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;
			}

			/*
				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)
				// Allow two blocks in queue per client
				//if(server->m_emerge_queue.peerItemCount(peer_id) < 2)
				u32 max_emerge = 25;
				// Make it more responsive when needing to generate stuff
				if(surely_not_found_on_disk)
					max_emerge = 5;
				if(server->m_emerge_queue.peerItemCount(peer_id) < max_emerge)
				{
					//infostream<<"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();

					if(nearest_emerged_d == -1)
						nearest_emerged_d = d;
				} else {
					if(nearest_emergefull_d == -1)
						nearest_emergefull_d = d;
				}
				
				// get next one.
				continue;
			}

			if(nearest_sent_d == -1)
				nearest_sent_d = d;

			/*
				Add block to send queue
			*/

			/*errorstream<<"sending from d="<<d<<" to "
					<<server->getPlayerName(peer_id)<<std::endl;*/

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

			dest.push_back(q);

			num_blocks_selected += 1;
		}
	}
queue_full_break:

	//infostream<<"Stopped at "<<d<<std::endl;
	
	// If nothing was found for sending and nothing was queued for
	// emerging, continue next time browsing from here
	if(nearest_emerged_d != -1){
		new_nearest_unsent_d = nearest_emerged_d;
	} else if(nearest_emergefull_d != -1){
		new_nearest_unsent_d = nearest_emergefull_d;
	} else {
		if(d > g_settings->getS16("max_block_send_distance")){
			new_nearest_unsent_d = 0;
			m_nothing_to_send_pause_timer = 2.0;
			/*infostream<<"GetNextBlocks(): d wrapped around for "
					<<server->getPlayerName(peer_id)
					<<"; setting to 0 and pausing"<<std::endl;*/
		} else {
			if(nearest_sent_d != -1)
				new_nearest_unsent_d = nearest_sent_d;
			else
				new_nearest_unsent_d = d;
		}
	}

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

	/*timer_result = timer.stop(true);
	if(timer_result != 0)
		infostream<<"GetNextBlocks duration: "<<timer_result<<" (!=0)"<<std::endl;*/
}

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)
	{
		infostream<<"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:
			u16 peer_id
			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 (dummy, for compatibility)
	*/

	// Write block count
	writeU16(buf, 0);
	os.write((char*)buf, 2);

	/*
		Send data
	*/
	
	//infostream<<"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
	{
		/*infostream<<"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
		infostream<<"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;
	avg_rtt = 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;
}

/*
	Mods
*/

struct ModSpec
{
	std::string name;
	std::string path;
	std::set<std::string> depends;
	std::set<std::string> unsatisfied_depends;

	ModSpec(const std::string &name_="", const std::string path_="",
			const std::set<std::string> &depends_=std::set<std::string>()):
		name(name_),
		path(path_),
		depends(depends_),
		unsatisfied_depends(depends_)
	{}
};

// Get a dependency-sorted list of ModSpecs
static core::list<ModSpec> getMods(core::list<std::string> &modspaths)
{
	std::queue<ModSpec> mods_satisfied;
	core::list<ModSpec> mods_unsorted;
	core::list<ModSpec> mods_sorted;
	for(core::list<std::string>::Iterator i = modspaths.begin();
			i != modspaths.end(); i++){
		std::string modspath = *i;
		std::vector<fs::DirListNode> dirlist = fs::GetDirListing(modspath);
		for(u32 j=0; j<dirlist.size(); j++){
			if(!dirlist[j].dir)
				continue;
			std::string modname = dirlist[j].name;
			std::string modpath = modspath + DIR_DELIM + modname;
			std::set<std::string> depends;
			std::ifstream is((modpath+DIR_DELIM+"depends.txt").c_str(),
					std::ios_base::binary);
			while(is.good()){
				std::string dep;
				std::getline(is, dep);
				dep = trim(dep);
				if(dep != "")
					depends.insert(dep);
			}
			ModSpec spec(modname, modpath, depends);
			mods_unsorted.push_back(spec);
			if(depends.empty())
				mods_satisfied.push(spec);
		}
	}
	// Sort by depencencies
	while(!mods_satisfied.empty()){
		ModSpec mod = mods_satisfied.front();
		mods_satisfied.pop();
		mods_sorted.push_back(mod);
		for(core::list<ModSpec>::Iterator i = mods_unsorted.begin();
				i != mods_unsorted.end(); i++){
			ModSpec &mod2 = *i;
			if(mod2.unsatisfied_depends.empty())
				continue;
			mod2.unsatisfied_depends.erase(mod.name);
			if(!mod2.unsatisfied_depends.empty())
				continue;
			mods_satisfied.push(mod2);
		}
	}
	// Check unsatisfied dependencies