minetest/src/map.cpp

/*
Minetest
Copyright (C) 2010-2013 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 Lesser General Public License as published by
the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.

You should have received a copy of the GNU Lesser 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 "map.h"
#include "mapsector.h"
#include "mapblock.h"
#include "filesys.h"
#include "voxel.h"
#include "voxelalgorithms.h"
#include "porting.h"
#include "serialization.h"
#include "nodemetadata.h"
#include "settings.h"
#include "log.h"
#include "profiler.h"
#include "nodedef.h"
#include "gamedef.h"
#include "util/directiontables.h"
#include "util/basic_macros.h"
#include "rollback_interface.h"
#include "environment.h"
#include "reflowscan.h"
#include "emerge.h"
#include "mapgen/mapgen_v6.h"
#include "mapgen/mg_biome.h"
#include "config.h"
#include "server.h"
#include "database/database.h"
#include "database/database-dummy.h"
#include "database/database-sqlite3.h"
#include "script/scripting_server.h"
#include <deque>
#include <queue>
#if USE_LEVELDB
#include "database/database-leveldb.h"
#endif
#if USE_REDIS
#include "database/database-redis.h"
#endif
#if USE_POSTGRESQL
#include "database/database-postgresql.h"
#endif


/*
	Map
*/

Map::Map(IGameDef *gamedef):
	m_gamedef(gamedef),
	m_nodedef(gamedef->ndef())
{
}

Map::~Map()
{
	/*
		Free all MapSectors
	*/
	for (auto &sector : m_sectors) {
		delete sector.second;
	}
}

void Map::addEventReceiver(MapEventReceiver *event_receiver)
{
	m_event_receivers.insert(event_receiver);
}

void Map::removeEventReceiver(MapEventReceiver *event_receiver)
{
	m_event_receivers.erase(event_receiver);
}

void Map::dispatchEvent(const MapEditEvent &event)
{
	for (MapEventReceiver *event_receiver : m_event_receivers) {
		event_receiver->onMapEditEvent(event);
	}
}

MapSector * Map::getSectorNoGenerateNoLock(v2s16 p)
{
	if(m_sector_cache != NULL && p == m_sector_cache_p){
		MapSector * sector = m_sector_cache;
		return sector;
	}

	std::map<v2s16, MapSector*>::iterator n = m_sectors.find(p);

	if (n == m_sectors.end())
		return NULL;

	MapSector *sector = n->second;

	// Cache the last result
	m_sector_cache_p = p;
	m_sector_cache = sector;

	return sector;
}

MapSector * Map::getSectorNoGenerate(v2s16 p)
{
	return getSectorNoGenerateNoLock(p);
}

MapBlock * Map::getBlockNoCreateNoEx(v3s16 p3d)
{
	v2s16 p2d(p3d.X, p3d.Z);
	MapSector * sector = getSectorNoGenerate(p2d);
	if(sector == NULL)
		return NULL;
	MapBlock *block = sector->getBlockNoCreateNoEx(p3d.Y);
	return block;
}

MapBlock * Map::getBlockNoCreate(v3s16 p3d)
{
	MapBlock *block = getBlockNoCreateNoEx(p3d);
	if(block == NULL)
		throw InvalidPositionException();
	return block;
}

bool Map::isValidPosition(v3s16 p)
{
	v3s16 blockpos = getNodeBlockPos(p);
	MapBlock *block = getBlockNoCreateNoEx(blockpos);
	return (block != NULL);
}

// Returns a CONTENT_IGNORE node if not found
MapNode Map::getNode(v3s16 p, bool *is_valid_position)
{
	v3s16 blockpos = getNodeBlockPos(p);
	MapBlock *block = getBlockNoCreateNoEx(blockpos);
	if (block == NULL) {
		if (is_valid_position != NULL)
			*is_valid_position = false;
		return {CONTENT_IGNORE};
	}

	v3s16 relpos = p - blockpos*MAP_BLOCKSIZE;
	bool is_valid_p;
	MapNode node = block->getNodeNoCheck(relpos, &is_valid_p);
	if (is_valid_position != NULL)
		*is_valid_position = is_valid_p;
	return node;
}

// throws InvalidPositionException if not found
void Map::setNode(v3s16 p, MapNode & n)
{
	v3s16 blockpos = getNodeBlockPos(p);
	MapBlock *block = getBlockNoCreate(blockpos);
	v3s16 relpos = p - blockpos*MAP_BLOCKSIZE;
	// Never allow placing CONTENT_IGNORE, it causes problems
	if(n.getContent() == CONTENT_IGNORE){
		bool temp_bool;
		errorstream<<"Map::setNode(): Not allowing to place CONTENT_IGNORE"
				<<" while trying to replace \""
				<<m_nodedef->get(block->getNodeNoCheck(relpos, &temp_bool)).name
				<<"\" at "<<PP(p)<<" (block "<<PP(blockpos)<<")"<<std::endl;
		return;
	}
	block->setNodeNoCheck(relpos, n);
}

void Map::addNodeAndUpdate(v3s16 p, MapNode n,
		std::map<v3s16, MapBlock*> &modified_blocks,
		bool remove_metadata)
{
	// Collect old node for rollback
	RollbackNode rollback_oldnode(this, p, m_gamedef);

	// This is needed for updating the lighting
	MapNode oldnode = getNode(p);

	// Remove node metadata
	if (remove_metadata) {
		removeNodeMetadata(p);
	}

	// Set the node on the map
	// Ignore light (because calling voxalgo::update_lighting_nodes)
	n.setLight(LIGHTBANK_DAY, 0, m_nodedef);
	n.setLight(LIGHTBANK_NIGHT, 0, m_nodedef);
	setNode(p, n);

	// Update lighting
	std::vector<std::pair<v3s16, MapNode> > oldnodes;
	oldnodes.emplace_back(p, oldnode);
	voxalgo::update_lighting_nodes(this, oldnodes, modified_blocks);

	for (auto &modified_block : modified_blocks) {
		modified_block.second->expireDayNightDiff();
	}

	// Report for rollback
	if(m_gamedef->rollback())
	{
		RollbackNode rollback_newnode(this, p, m_gamedef);
		RollbackAction action;
		action.setSetNode(p, rollback_oldnode, rollback_newnode);
		m_gamedef->rollback()->reportAction(action);
	}

	/*
		Add neighboring liquid nodes and this node to transform queue.
		(it's vital for the node itself to get updated last, if it was removed.)
	 */

	for (const v3s16 &dir : g_7dirs) {
		v3s16 p2 = p + dir;

		bool is_valid_position;
		MapNode n2 = getNode(p2, &is_valid_position);
		if(is_valid_position &&
				(m_nodedef->get(n2).isLiquid() ||
				n2.getContent() == CONTENT_AIR))
			m_transforming_liquid.push_back(p2);
	}
}

void Map::removeNodeAndUpdate(v3s16 p,
		std::map<v3s16, MapBlock*> &modified_blocks)
{
	addNodeAndUpdate(p, MapNode(CONTENT_AIR), modified_blocks, true);
}

bool Map::addNodeWithEvent(v3s16 p, MapNode n, bool remove_metadata)
{
	MapEditEvent event;
	event.type = remove_metadata ? MEET_ADDNODE : MEET_SWAPNODE;
	event.p = p;
	event.n = n;

	bool succeeded = true;
	try{
		std::map<v3s16, MapBlock*> modified_blocks;
		addNodeAndUpdate(p, n, modified_blocks, remove_metadata);

		// Copy modified_blocks to event
		for (auto &modified_block : modified_blocks) {
			event.modified_blocks.insert(modified_block.first);
		}
	}
	catch(InvalidPositionException &e){
		succeeded = false;
	}

	dispatchEvent(event);

	return succeeded;
}

bool Map::removeNodeWithEvent(v3s16 p)
{
	MapEditEvent event;
	event.type = MEET_REMOVENODE;
	event.p = p;

	bool succeeded = true;
	try{
		std::map<v3s16, MapBlock*> modified_blocks;
		removeNodeAndUpdate(p, modified_blocks);

		// Copy modified_blocks to event
		for (auto &modified_block : modified_blocks) {
			event.modified_blocks.insert(modified_block.first);
		}
	}
	catch(InvalidPositionException &e){
		succeeded = false;
	}

	dispatchEvent(event);

	return succeeded;
}

struct TimeOrderedMapBlock {
	MapSector *sect;
	MapBlock *block;

	TimeOrderedMapBlock(MapSector *sect, MapBlock *block) :
		sect(sect),
		block(block)
	{}

	bool operator<(const TimeOrderedMapBlock &b) const
	{
		return block->getUsageTimer() < b.block->getUsageTimer();
	};
};

/*
	Updates usage timers
*/
void Map::timerUpdate(float dtime, float unload_timeout, u32 max_loaded_blocks,
		std::vector<v3s16> *unloaded_blocks)
{
	bool save_before_unloading = (mapType() == MAPTYPE_SERVER);

	// Profile modified reasons
	Profiler modprofiler;

	std::vector<v2s16> sector_deletion_queue;
	u32 deleted_blocks_count = 0;
	u32 saved_blocks_count = 0;
	u32 block_count_all = 0;

	beginSave();

	// If there is no practical limit, we spare creation of mapblock_queue
	if (max_loaded_blocks == U32_MAX) {
		for (auto &sector_it : m_sectors) {
			MapSector *sector = sector_it.second;

			bool all_blocks_deleted = true;

			MapBlockVect blocks;
			sector->getBlocks(blocks);

			for (MapBlock *block : blocks) {
				block->incrementUsageTimer(dtime);

				if (block->refGet() == 0
						&& block->getUsageTimer() > unload_timeout) {
					v3s16 p = block->getPos();

					// Save if modified
					if (block->getModified() != MOD_STATE_CLEAN
							&& save_before_unloading) {
						modprofiler.add(block->getModifiedReasonString(), 1);
						if (!saveBlock(block))
							continue;
						saved_blocks_count++;
					}

					// Delete from memory
					sector->deleteBlock(block);

					if (unloaded_blocks)
						unloaded_blocks->push_back(p);

					deleted_blocks_count++;
				} else {
					all_blocks_deleted = false;
					block_count_all++;
				}
			}

			if (all_blocks_deleted) {
				sector_deletion_queue.push_back(sector_it.first);
			}
		}
	} else {
		std::priority_queue<TimeOrderedMapBlock> mapblock_queue;
		for (auto &sector_it : m_sectors) {
			MapSector *sector = sector_it.second;

			MapBlockVect blocks;
			sector->getBlocks(blocks);

			for (MapBlock *block : blocks) {
				block->incrementUsageTimer(dtime);
				mapblock_queue.push(TimeOrderedMapBlock(sector, block));
			}
		}
		block_count_all = mapblock_queue.size();
		// Delete old blocks, and blocks over the limit from the memory
		while (!mapblock_queue.empty() && (mapblock_queue.size() > max_loaded_blocks
				|| mapblock_queue.top().block->getUsageTimer() > unload_timeout)) {
			TimeOrderedMapBlock b = mapblock_queue.top();
			mapblock_queue.pop();

			MapBlock *block = b.block;

			if (block->refGet() != 0)
				continue;

			v3s16 p = block->getPos();

			// Save if modified
			if (block->getModified() != MOD_STATE_CLEAN && save_before_unloading) {
				modprofiler.add(block->getModifiedReasonString(), 1);
				if (!saveBlock(block))
					continue;
				saved_blocks_count++;
			}

			// Delete from memory
			b.sect->deleteBlock(block);

			if (unloaded_blocks)
				unloaded_blocks->push_back(p);

			deleted_blocks_count++;
			block_count_all--;
		}
		// Delete empty sectors
		for (auto &sector_it : m_sectors) {
			if (sector_it.second->empty()) {
				sector_deletion_queue.push_back(sector_it.first);
			}
		}
	}
	endSave();

	// Finally delete the empty sectors
	deleteSectors(sector_deletion_queue);

	if(deleted_blocks_count != 0)
	{
		PrintInfo(infostream); // ServerMap/ClientMap:
		infostream<<"Unloaded "<<deleted_blocks_count
				<<" blocks from memory";
		if(save_before_unloading)
			infostream<<", of which "<<saved_blocks_count<<" were written";
		infostream<<", "<<block_count_all<<" blocks in memory";
		infostream<<"."<<std::endl;
		if(saved_blocks_count != 0){
			PrintInfo(infostream); // ServerMap/ClientMap:
			infostream<<"Blocks modified by: "<<std::endl;
			modprofiler.print(infostream);
		}
	}
}

void Map::unloadUnreferencedBlocks(std::vector<v3s16> *unloaded_blocks)
{
	timerUpdate(0.0, -1.0, 0, unloaded_blocks);
}

void Map::deleteSectors(std::vector<v2s16> &sectorList)
{
	for (v2s16 j : sectorList) {
		MapSector *sector = m_sectors[j];
		// If sector is in sector cache, remove it from there
		if(m_sector_cache == sector)
			m_sector_cache = NULL;
		// Remove from map and delete
		m_sectors.erase(j);
		delete sector;
	}
}

void Map::PrintInfo(std::ostream &out)
{
	out<<"Map: ";
}

#define WATER_DROP_BOOST 4

const static v3s16 liquid_6dirs[6] = {
	// order: upper before same level before lower
	v3s16( 0, 1, 0),
	v3s16( 0, 0, 1),
	v3s16( 1, 0, 0),
	v3s16( 0, 0,-1),
	v3s16(-1, 0, 0),
	v3s16( 0,-1, 0)
};

enum NeighborType : u8 {
	NEIGHBOR_UPPER,
	NEIGHBOR_SAME_LEVEL,
	NEIGHBOR_LOWER
};

struct NodeNeighbor {
	MapNode n;
	NeighborType t;
	v3s16 p;

	NodeNeighbor()
		: n(CONTENT_AIR), t(NEIGHBOR_SAME_LEVEL)
	{ }

	NodeNeighbor(const MapNode &node, NeighborType n_type, const v3s16 &pos)
		: n(node),
		  t(n_type),
		  p(pos)
	{ }
};

void Map::transforming_liquid_add(v3s16 p) {
        m_transforming_liquid.push_back(p);
}

void Map::transformLiquids(std::map<v3s16, MapBlock*> &modified_blocks,
		ServerEnvironment *env)
{
	u32 loopcount = 0;
	u32 initial_size = m_transforming_liquid.size();

	/*if(initial_size != 0)
		infostream<<"transformLiquids(): initial_size="<<initial_size<<std::endl;*/

	// list of nodes that due to viscosity have not reached their max level height
	std::deque<v3s16> must_reflow;

	std::vector<std::pair<v3s16, MapNode> > changed_nodes;

	u32 liquid_loop_max = g_settings->getS32("liquid_loop_max");
	u32 loop_max = liquid_loop_max;

	while (m_transforming_liquid.size() != 0)
	{
		// This should be done here so that it is done when continue is used
		if (loopcount >= initial_size || loopcount >= loop_max)
			break;
		loopcount++;

		/*
			Get a queued transforming liquid node
		*/
		v3s16 p0 = m_transforming_liquid.front();
		m_transforming_liquid.pop_front();

		MapNode n0 = getNode(p0);

		/*
			Collect information about current node
		 */
		s8 liquid_level = -1;
		// The liquid node which will be placed there if
		// the liquid flows into this node.
		content_t liquid_kind = CONTENT_IGNORE;
		// The node which will be placed there if liquid
		// can't flow into this node.
		content_t floodable_node = CONTENT_AIR;
		const ContentFeatures &cf = m_nodedef->get(n0);
		LiquidType liquid_type = cf.liquid_type;
		switch (liquid_type) {
			case LIQUID_SOURCE:
				liquid_level = LIQUID_LEVEL_SOURCE;
				liquid_kind = cf.liquid_alternative_flowing_id;
				break;
			case LIQUID_FLOWING:
				liquid_level = (n0.param2 & LIQUID_LEVEL_MASK);
				liquid_kind = n0.getContent();
				break;
			case LIQUID_NONE:
				// if this node is 'floodable', it *could* be transformed
				// into a liquid, otherwise, continue with the next node.
				if (!cf.floodable)
					continue;
				floodable_node = n0.getContent();
				liquid_kind = CONTENT_AIR;
				break;
		}

		/*
			Collect information about the environment
		 */
		NodeNeighbor sources[6]; // surrounding sources
		int num_sources = 0;
		NodeNeighbor flows[6]; // surrounding flowing liquid nodes
		int num_flows = 0;
		NodeNeighbor airs[6]; // surrounding air
		int num_airs = 0;
		NodeNeighbor neutrals[6]; // nodes that are solid or another kind of liquid
		int num_neutrals = 0;
		bool flowing_down = false;
		bool ignored_sources = false;
		for (u16 i = 0; i < 6; i++) {
			NeighborType nt = NEIGHBOR_SAME_LEVEL;
			switch (i) {
				case 0:
					nt = NEIGHBOR_UPPER;
					break;
				case 5:
					nt = NEIGHBOR_LOWER;
					break;
				default:
					break;
			}
			v3s16 npos = p0 + liquid_6dirs[i];
			NodeNeighbor nb(getNode(npos), nt, npos);
			const ContentFeatures &cfnb = m_nodedef->get(nb.n);
			switch (m_nodedef->get(nb.n.getContent()).liquid_type) {
				case LIQUID_NONE:
					if (cfnb.floodable) {
						airs[num_airs++] = nb;
						// if the current node is a water source the neighbor
						// should be enqueded for transformation regardless of whether the
						// current node changes or not.
						if (nb.t != NEIGHBOR_UPPER && liquid_type != LIQUID_NONE)
							m_transforming_liquid.push_back(npos);
						// if the current node happens to be a flowing node, it will start to flow down here.
						if (nb.t == NEIGHBOR_LOWER)
							flowing_down = true;
					} else {
						neutrals[num_neutrals++] = nb;
						if (nb.n.getContent() == CONTENT_IGNORE) {
							// If node below is ignore prevent water from
							// spreading outwards and otherwise prevent from
							// flowing away as ignore node might be the source
							if (nb.t == NEIGHBOR_LOWER)
								flowing_down = true;
							else
								ignored_sources = true;
						}
					}
					break;
				case LIQUID_SOURCE:
					// if this node is not (yet) of a liquid type, choose the first liquid type we encounter
					if (liquid_kind == CONTENT_AIR)
						liquid_kind = cfnb.liquid_alternative_flowing_id;
					if (cfnb.liquid_alternative_flowing_id != liquid_kind) {
						neutrals[num_neutrals++] = nb;
					} else {
						// Do not count bottom source, it will screw things up
						if(nt != NEIGHBOR_LOWER)
							sources[num_sources++] = nb;
					}
					break;
				case LIQUID_FLOWING:
					if (nb.t != NEIGHBOR_SAME_LEVEL ||
						(nb.n.param2 & LIQUID_FLOW_DOWN_MASK) != LIQUID_FLOW_DOWN_MASK) {
						// if this node is not (yet) of a liquid type, choose the first liquid type we encounter
						// but exclude falling liquids on the same level, they cannot flow here anyway
						if (liquid_kind == CONTENT_AIR)
							liquid_kind = cfnb.liquid_alternative_flowing_id;
					}
					if (cfnb.liquid_alternative_flowing_id != liquid_kind) {
						neutrals[num_neutrals++] = nb;
					} else {
						flows[num_flows++] = nb;
						if (nb.t == NEIGHBOR_LOWER)
							flowing_down = true;
					}
					break;
			}
		}

		/*
			decide on the type (and possibly level) of the current node
		 */
		content_t new_node_content;
		s8 new_node_level = -1;
		s8 max_node_level = -1;

		u8 range = m_nodedef->get(liquid_kind).liquid_range;
		if (range > LIQUID_LEVEL_MAX + 1)
			range = LIQUID_LEVEL_MAX + 1;

		if ((num_sources >= 2 && m_nodedef->get(liquid_kind).liquid_renewable) || liquid_type == LIQUID_SOURCE) {
			// liquid_kind will be set to either the flowing alternative of the node (if it's a liquid)
			// or the flowing alternative of the first of the surrounding sources (if it's air), so
			// it's perfectly safe to use liquid_kind here to determine the new node content.
			new_node_content = m_nodedef->get(liquid_kind).liquid_alternative_source_id;
		} else if (num_sources >= 1 && sources[0].t != NEIGHBOR_LOWER) {
			// liquid_kind is set properly, see above
			max_node_level = new_node_level = LIQUID_LEVEL_MAX;
			if (new_node_level >= (LIQUID_LEVEL_MAX + 1 - range))
				new_node_content = liquid_kind;
			else
				new_node_content = floodable_node;
		} else if (ignored_sources && liquid_level >= 0) {
			// Maybe there are neighbouring sources that aren't loaded yet
			// so prevent flowing away.
			new_node_level = liquid_level;
			new_node_content = liquid_kind;
		} else {
			// no surrounding sources, so get the maximum level that can flow into this node
			for (u16 i = 0; i < num_flows; i++) {
				u8 nb_liquid_level = (flows[i].n.param2 & LIQUID_LEVEL_MASK);
				switch (flows[i].t) {
					case NEIGHBOR_UPPER:
						if (nb_liquid_level + WATER_DROP_BOOST > max_node_level) {
							max_node_level = LIQUID_LEVEL_MAX;
							if (nb_liquid_level + WATER_DROP_BOOST < LIQUID_LEVEL_MAX)
								max_node_level = nb_liquid_level + WATER_DROP_BOOST;
						} else if (nb_liquid_level > max_node_level) {
							max_node_level = nb_liquid_level;
						}
						break;
					case NEIGHBOR_LOWER:
						break;
					case NEIGHBOR_SAME_LEVEL:
						if ((flows[i].n.param2 & LIQUID_FLOW_DOWN_MASK) != LIQUID_FLOW_DOWN_MASK &&
								nb_liquid_level > 0 && nb_liquid_level - 1 > max_node_level)
							max_node_level = nb_liquid_level - 1;
						break;
				}
			}

			u8 viscosity = m_nodedef->get(liquid_kind).liquid_viscosity;
			if (viscosity > 1 && max_node_level != liquid_level) {
				// amount to gain, limited by viscosity
				// must be at least 1 in absolute value
				s8 level_inc = max_node_level - liquid_level;
				if (level_inc < -viscosity || level_inc > viscosity)
					new_node_level = liquid_level + level_inc/viscosity;
				else if (level_inc < 0)
					new_node_level = liquid_level - 1;
				else if (level_inc > 0)
					new_node_level = liquid_level + 1;
				if (new_node_level != max_node_level)
					must_reflow.push_back(p0);
			} else {
				new_node_level = max_node_level;
			}

			if (max_node_level >= (LIQUID_LEVEL_MAX + 1 - range))
				new_node_content = liquid_kind;
			else
				new_node_content = floodable_node;

		}

		/*
			check if anything has changed. if not, just continue with the next node.
		 */
		if (new_node_content == n0.getContent() &&
				(m_nodedef->get(n0.getContent()).liquid_type != LIQUID_FLOWING ||
				((n0.param2 & LIQUID_LEVEL_MASK) == (u8)new_node_level &&
				((n0.param2 & LIQUID_FLOW_DOWN_MASK) == LIQUID_FLOW_DOWN_MASK)
				== flowing_down)))
			continue;


		/*
			update the current node
		 */
		MapNode n00 = n0;
		//bool flow_down_enabled = (flowing_down && ((n0.param2 & LIQUID_FLOW_DOWN_MASK) != LIQUID_FLOW_DOWN_MASK));
		if (m_nodedef->get(new_node_content).liquid_type == LIQUID_FLOWING) {
			// set level to last 3 bits, flowing down bit to 4th bit
			n0.param2 = (flowing_down ? LIQUID_FLOW_DOWN_MASK : 0x00) | (new_node_level & LIQUID_LEVEL_MASK);
		} else {
			// set the liquid level and flow bits to 0
			n0.param2 &= ~(LIQUID_LEVEL_MASK | LIQUID_FLOW_DOWN_MASK);
		}

		// change the node.
		n0.setContent(new_node_content);

		// on_flood() the node
		if (floodable_node != CONTENT_AIR) {
			if (env->getScriptIface()->node_on_flood(p0, n00, n0))
				continue;
		}

		// Ignore light (because calling voxalgo::update_lighting_nodes)
		n0.setLight(LIGHTBANK_DAY, 0, m_nodedef);
		n0.setLight(LIGHTBANK_NIGHT, 0, m_nodedef);

		// Find out whether there is a suspect for this action
		std::string suspect;
		if (m_gamedef->rollback())
			suspect = m_gamedef->rollback()->getSuspect(p0, 83, 1);

		if (m_gamedef->rollback() && !suspect.empty()) {
			// Blame suspect
			RollbackScopeActor rollback_scope(m_gamedef->rollback(), suspect, true);
			// Get old node for rollback
			RollbackNode rollback_oldnode(this, p0, m_gamedef);
			// Set node
			setNode(p0, n0);
			// Report
			RollbackNode rollback_newnode(this, p0, m_gamedef);
			RollbackAction action;
			action.setSetNode(p0, rollback_oldnode, rollback_newnode);
			m_gamedef->rollback()->reportAction(action);
		} else {
			// Set node
			setNode(p0, n0);
		}

		v3s16 blockpos = getNodeBlockPos(p0);
		MapBlock *block = getBlockNoCreateNoEx(blockpos);
		if (block != NULL) {
			modified_blocks[blockpos] =  block;
			changed_nodes.emplace_back(p0, n00);
		}

		/*
			enqueue neighbors for update if neccessary
		 */
		switch (m_nodedef->get(n0.getContent()).liquid_type) {
			case LIQUID_SOURCE:
			case LIQUID_FLOWING:
				// make sure source flows into all neighboring nodes
				for (u16 i = 0; i < num_flows; i++)
					if (flows[i].t != NEIGHBOR_UPPER)
						m_transforming_liquid.push_back(flows[i].p);
				for (u16 i = 0; i < num_airs; i++)
					if (airs[i].t != NEIGHBOR_UPPER)
						m_transforming_liquid.push_back(airs[i].p);
				break;
			case LIQUID_NONE:
				// this flow has turned to air; neighboring flows might need to do the same
				for (u16 i = 0; i < num_flows; i++)
					m_transforming_liquid.push_back(flows[i].p);
				break;
		}
	}
	//infostream<<"Map::transformLiquids(): loopcount="<<loopcount<<std::endl;

	for (auto &iter : must_reflow)
		m_transforming_liquid.push_back(iter);

	voxalgo::update_lighting_nodes(this, changed_nodes, modified_blocks);
	env->getScriptIface()->on_liquid_transformed(changed_nodes);

	/* ----------------------------------------------------------------------
	 * Manage the queue so that it does not grow indefinately
	 */
	u16 time_until_purge = g_settings->getU16("liquid_queue_purge_time");

	if (time_until_purge == 0)
		return; // Feature disabled

	time_until_purge *= 1000;	// seconds -> milliseconds

	u64 curr_time = porting::getTimeMs();
	u32 prev_unprocessed = m_unprocessed_count;
	m_unprocessed_count = m_transforming_liquid.size();

	// if unprocessed block count is decreasing or stable
	if (m_unprocessed_count <= prev_unprocessed) {
		m_queue_size_timer_started = false;
	} else {
		if (!m_queue_size_timer_started)
			m_inc_trending_up_start_time = curr_time;
		m_queue_size_timer_started = true;
	}

	// Account for curr_time overflowing
	if (m_queue_size_timer_started && m_inc_trending_up_start_time > curr_time)
		m_queue_size_timer_started = false;

	/* If the queue has been growing for more than liquid_queue_purge_time seconds
	 * and the number of unprocessed blocks is still > liquid_loop_max then we
	 * cannot keep up; dump the oldest blocks from the queue so that the queue
	 * has liquid_loop_max items in it
	 */
	if (m_queue_size_timer_started
			&& curr_time - m_inc_trending_up_start_time > time_until_purge
			&& m_unprocessed_count > liquid_loop_max) {

		size_t dump_qty = m_unprocessed_count - liquid_loop_max;

		infostream << "transformLiquids(): DUMPING " << dump_qty
		           << " blocks from the queue" << std::endl;

		while (dump_qty--)
			m_transforming_liquid.pop_front();

		m_queue_size_timer_started = false; // optimistically assume we can keep up now
		m_unprocessed_count = m_transforming_liquid.size();
	}
}

std::vector<v3s16> Map::findNodesWithMetadata(v3s16 p1, v3s16 p2)
{
	std::vector<v3s16> positions_with_meta;

	sortBoxVerticies(p1, p2);
	v3s16 bpmin = getNodeBlockPos(p1);
	v3s16 bpmax = getNodeBlockPos(p2);

	VoxelArea area(p1, p2);

	for (s16 z = bpmin.Z; z <= bpmax.Z; z++)
	for (s16 y = bpmin.Y; y <= bpmax.Y; y++)
	for (s16 x = bpmin.X; x <= bpmax.X; x++) {
		v3s16 blockpos(x, y, z);

		MapBlock *block = getBlockNoCreateNoEx(blockpos);
		if (!block) {
			verbosestream << "Map::getNodeMetadata(): Need to emerge "
				<< PP(blockpos) << std::endl;
			block = emergeBlock(blockpos, false);
		}
		if (!block) {
			infostream << "WARNING: Map::getNodeMetadata(): Block not found"
				<< std::endl;
			continue;
		}

		v3s16 p_base = blockpos * MAP_BLOCKSIZE;
		std::vector<v3s16> keys = block->m_node_metadata.getAllKeys();
		for (size_t i = 0; i != keys.size(); i++) {
			v3s16 p(keys[i] + p_base);
			if (!area.contains(p))
				continue;

			positions_with_meta.push_back(p);
		}
	}

	return positions_with_meta;
}

NodeMetadata *Map::getNodeMetadata(v3s16 p)
{
	v3s16 blockpos = getNodeBlockPos(p);
	v3s16 p_rel = p - blockpos*MAP_BLOCKSIZE;
	MapBlock *block = getBlockNoCreateNoEx(blockpos);
	if(!block){
		infostream<<"Map::getNodeMetadata(): Need to emerge "
				<<PP(blockpos)<<std::endl;
		block = emergeBlock(blockpos, false);
	}
	if(!block){
		warningstream<<"Map::getNodeMetadata(): Block not found"
				<<std::endl;
		return NULL;
	}
	NodeMetadata *meta = block->m_node_metadata.get(p_rel);
	return meta;
}

bool Map::setNodeMetadata(v3s16 p, NodeMetadata *meta)
{
	v3s16 blockpos = getNodeBlockPos(p);
	v3s16 p_rel = p - blockpos*MAP_BLOCKSIZE;
	MapBlock *block = getBlockNoCreateNoEx(blockpos);
	if(!block){
		infostream<<"Map::setNodeMetadata(): Need to emerge "
				<<PP(blockpos)<<std::endl;
		block = emergeBlock(blockpos, false);
	}
	if(!block){
		warningstream<<"Map::setNodeMetadata(): Block not found"
				<<std::endl;
		return false;
	}
	block->m_node_metadata.set(p_rel, meta);
	return true;
}

void Map::removeNodeMetadata(v3s16 p)
{
	v3s16 blockpos = getNodeBlockPos(p);
	v3s16 p_rel = p - blockpos*MAP_BLOCKSIZE;
	MapBlock *block = getBlockNoCreateNoEx(blockpos);
	if(block == NULL)
	{
		warningstream<<"Map::removeNodeMetadata(): Block not found"
				<<std::endl;
		return;
	}
	block->m_node_metadata.remove(p_rel);
}

NodeTimer Map::getNodeTimer(v3s16 p)
{
	v3s16 blockpos = getNodeBlockPos(p);
	v3s16 p_rel = p - blockpos*MAP_BLOCKSIZE;
	MapBlock *block = getBlockNoCreateNoEx(blockpos);
	if(!block){
		infostream<<"Map::getNodeTimer(): Need to emerge "
				<<PP(blockpos)<<std::endl;
		block = emergeBlock(blockpos, false);
	}
	if(!block){
		warningstream<<"Map::getNodeTimer(): Block not found"
				<<std::endl;
		return NodeTimer();
	}
	NodeTimer t = block->m_node_timers.get(p_rel);
	NodeTimer nt(t.timeout, t.elapsed, p);
	return nt;
}

void Map::setNodeTimer(const NodeTimer &t)
{
	v3s16 p = t.position;
	v3s16 blockpos = getNodeBlockPos(p);
	v3s16 p_rel = p - blockpos*MAP_BLOCKSIZE;
	MapBlock *block = getBlockNoCreateNoEx(blockpos);
	if(!block){
		infostream<<"Map::setNodeTimer(): Need to emerge "
				<<PP(blockpos)<<std::endl;
		block = emergeBlock(blockpos, false);
	}
	if(!block){
		warningstream<<"Map::setNodeTimer(): Block not found"
				<<std::endl;
		return;
	}
	NodeTimer nt(t.timeout, t.elapsed, p_rel);
	block->m_node_timers.set(nt);
}

void Map::removeNodeTimer(v3s16 p)
{
	v3s16 blockpos = getNodeBlockPos(p);
	v3s16 p_rel = p - blockpos*MAP_BLOCKSIZE;
	MapBlock *block = getBlockNoCreateNoEx(blockpos);
	if(block == NULL)
	{
		warningstream<<"Map::removeNodeTimer(): Block not found"
				<<std::endl;
		return;
	}
	block->m_node_timers.remove(p_rel);
}

bool Map::determineAdditionalOcclusionCheck(const v3s16 &pos_camera,
	const core::aabbox3d<s16> &block_bounds, v3s16 &check)
{
	/*
		This functions determines the node inside the target block that is
		closest to the camera position. This increases the occlusion culling
		accuracy in straight and diagonal corridors.
		The returned position will be occlusion checked first in addition to the
		others (8 corners + center).
		No position is returned if
		- the closest node is a corner, corners are checked anyway.
		- the camera is inside the target block, it will never be occluded.
	*/
#define CLOSEST_EDGE(pos, bounds, axis) \
	((pos).axis <= (bounds).MinEdge.axis) ? (bounds).MinEdge.axis : \
	(bounds).MaxEdge.axis

	bool x_inside = (block_bounds.MinEdge.X <= pos_camera.X) &&
			(pos_camera.X <= block_bounds.MaxEdge.X);
	bool y_inside = (block_bounds.MinEdge.Y <= pos_camera.Y) &&
			(pos_camera.Y <= block_bounds.MaxEdge.Y);
	bool z_inside = (block_bounds.MinEdge.Z <= pos_camera.Z) &&
			(pos_camera.Z <= block_bounds.MaxEdge.Z);

	if (x_inside && y_inside && z_inside)
		return false; // Camera inside target mapblock

	// straight
	if (x_inside && y_inside) {
		check = v3s16(pos_camera.X, pos_camera.Y, 0);
		check.Z = CLOSEST_EDGE(pos_camera, block_bounds, Z);
		return true;
	} else if (y_inside && z_inside) {
		check = v3s16(0, pos_camera.Y, pos_camera.Z);
		check.X = CLOSEST_EDGE(pos_camera, block_bounds, X);
		return true;
	} else if (x_inside && z_inside) {
		check = v3s16(pos_camera.X, 0, pos_camera.Z);
		check.Y = CLOSEST_EDGE(pos_camera, block_bounds, Y);
		return true;
	}

	// diagonal
	if (x_inside) {
		check = v3s16(pos_camera.X, 0, 0);
		check.Y = CLOSEST_EDGE(pos_camera, block_bounds, Y);
		check.Z = CLOSEST_EDGE(pos_camera, block_bounds, Z);
		return true;
	} else if (y_inside) {
		check = v3s16(0, pos_camera.Y, 0);
		check.X = CLOSEST_EDGE(pos_camera, block_bounds, X);
		check.Z = CLOSEST_EDGE(pos_camera, block_bounds, Z);
		return true;
	} else if (z_inside) {
		check = v3s16(0, 0, pos_camera.Z);
		check.X = CLOSEST_EDGE(pos_camera, block_bounds, X);
		check.Y = CLOSEST_EDGE(pos_camera, block_bounds, Y);
		return true;
	}

	// Closest node would be a corner, none returned
	return false;
}

bool Map::isOccluded(const v3s16 &pos_camera, const v3s16 &pos_target,
	float step, float stepfac, float offset, float end_offset, u32 needed_count)
{
	v3f direction = intToFloat(pos_target - pos_camera, BS);
	float distance = direction.getLength();

	// Normalize direction vector
	if (distance > 0.0f)
		direction /= distance;

	v3f pos_origin_f = intToFloat(pos_camera, BS);
	u32 count = 0;
	bool is_valid_position;

	for (; offset < distance + end_offset; offset += step) {
		v3f pos_node_f = pos_origin_f + direction * offset;
		v3s16 pos_node = floatToInt(pos_node_f, BS);

		MapNode node = getNode(pos_node, &is_valid_position);

		if (is_valid_position &&
				!m_nodedef->get(node).light_propagates) {
			// Cannot see through light-blocking nodes --> occluded
			count++;
			if (count >= needed_count)
				return true;
		}
		step *= stepfac;
	}
	return false;
}

bool Map::isBlockOccluded(MapBlock *block, v3s16 cam_pos_nodes)
{
	// Check occlusion for center and all 8 corners of the mapblock
	// Overshoot a little for less flickering
	static const s16 bs2 = MAP_BLOCKSIZE / 2 + 1;
	static const v3s16 dir9[9] = {
		v3s16( 0,  0,  0),
		v3s16( 1,  1,  1) * bs2,
		v3s16( 1,  1, -1) * bs2,
		v3s16( 1, -1,  1) * bs2,
		v3s16( 1, -1, -1) * bs2,
		v3s16(-1,  1,  1) * bs2,
		v3s16(-1,  1, -1) * bs2,
		v3s16(-1, -1,  1) * bs2,
		v3s16(-1, -1, -1) * bs2,
	};

	v3s16 pos_blockcenter = block->getPosRelative() + (MAP_BLOCKSIZE / 2);

	// Starting step size, value between 1m and sqrt(3)m
	float step = BS * 1.2f;
	// Multiply step by each iteraction by 'stepfac' to reduce checks in distance
	float stepfac = 1.05f;

	float start_offset = BS * 1.0f;

	// The occlusion search of 'isOccluded()' must stop short of the target
	// point by distance 'end_offset' to not enter the target mapblock.
	// For the 8 mapblock corners 'end_offset' must therefore be the maximum
	// diagonal of a mapblock, because we must consider all view angles.
	// sqrt(1^2 + 1^2 + 1^2) = 1.732
	float end_offset = -BS * MAP_BLOCKSIZE * 1.732f;

	// to reduce the likelihood of falsely occluded blocks
	// require at least two solid blocks
	// this is a HACK, we should think of a more precise algorithm
	u32 needed_count = 2;

	// Additional occlusion check, see comments in that function
	v3s16 check;
	if (determineAdditionalOcclusionCheck(cam_pos_nodes, block->getBox(), check)) {
		// node is always on a side facing the camera, end_offset can be lower
		if (!isOccluded(cam_pos_nodes, check, step, stepfac, start_offset,
				-1.0f, needed_count))
			return false;
	}

	for (const v3s16 &dir : dir9) {
		if (!isOccluded(cam_pos_nodes, pos_blockcenter + dir, step, stepfac,
				start_offset, end_offset, needed_count))
			return false;
	}
	return true;
}

/*
	ServerMap
*/
ServerMap::ServerMap(const std::string &savedir, IGameDef *gamedef,
		EmergeManager *emerge, MetricsBackend *mb):
	Map(gamedef),
	settings_mgr(savedir + DIR_DELIM + "map_meta.txt"),
	m_emerge(emerge)
{
	verbosestream<<FUNCTION_NAME<<std::endl;

	// Tell the EmergeManager about our MapSettingsManager
	emerge->map_settings_mgr = &settings_mgr;

	/*
		Try to load map; if not found, create a new one.
	*/

	// Determine which database backend to use
	std::string conf_path = savedir + DIR_DELIM + "world.mt";
	Settings conf;
	bool succeeded = conf.readConfigFile(conf_path.c_str());
	if (!succeeded || !conf.exists("backend")) {
		// fall back to sqlite3
		conf.set("backend", "sqlite3");
	}
	std::string backend = conf.get("backend");
	dbase = createDatabase(backend, savedir, conf);
	if (conf.exists("readonly_backend")) {
		std::string readonly_dir = savedir + DIR_DELIM + "readonly";
		dbase_ro = createDatabase(conf.get("readonly_backend"), readonly_dir, conf);
	}
	if (!conf.updateConfigFile(conf_path.c_str()))
		errorstream << "ServerMap::ServerMap(): Failed to update world.mt!" << std::endl;

	m_savedir = savedir;
	m_map_saving_enabled = false;

	m_save_time_counter = mb->addCounter("minetest_core_map_save_time", "Map save time (in nanoseconds)");

	m_map_compression_level = rangelim(g_settings->getS16("map_compression_level_disk"), -1, 9);

	try {
		// If directory exists, check contents and load if possible
		if (fs::PathExists(m_savedir)) {
			// If directory is empty, it is safe to save into it.
			if (fs::GetDirListing(m_savedir).empty()) {
				infostream<<"ServerMap: Empty save directory is valid."
						<<std::endl;
				m_map_saving_enabled = true;
			}
			else
			{

				if (settings_mgr.loadMapMeta()) {
					infostream << "ServerMap: Metadata loaded from "
						<< savedir << std::endl;
				} else {
					infostream << "ServerMap: Metadata could not be loaded "
						"from " << savedir << ", assuming valid save "
						"directory." << std::endl;
				}

				m_map_saving_enabled = true;
				// Map loaded, not creating new one
				return;
			}
		}
		// If directory doesn't exist, it is safe to save to it
		else{
			m_map_saving_enabled = true;
		}
	}
	catch(std::exception &e)
	{
		warningstream<<"ServerMap: Failed to load map from "<<savedir
				<<", exception: "<<e.what()<<std::endl;
		infostream<<"Please remove the map or fix it."<<std::endl;
		warningstream<<"Map saving will be disabled."<<std::endl;
	}
}

ServerMap::~ServerMap()
{
	verbosestream<<FUNCTION_NAME<<std::endl;

	try
	{
		if (m_map_saving_enabled) {
			// Save only changed parts
			save(MOD_STATE_WRITE_AT_UNLOAD);
			infostream << "ServerMap: Saved map to " << m_savedir << std::endl;
		} else {
			infostream << "ServerMap: Map not saved" << std::endl;
		}
	}
	catch(std::exception &e)
	{
		infostream<<"ServerMap: Failed to save map to "<<m_savedir
				<<", exception: "<<e.what()<<std::endl;
	}

	/*
		Close database if it was opened
	*/
	delete dbase;
	delete dbase_ro;
}

MapgenParams *ServerMap::getMapgenParams()
{
	// getMapgenParams() should only ever be called after Server is initialized
	assert(settings_mgr.mapgen_params != NULL);
	return settings_mgr.mapgen_params;
}

u64 ServerMap::getSeed()
{
	return getMapgenParams()->seed;
}

bool ServerMap::blockpos_over_mapgen_limit(v3s16 p)
{
	const s16 mapgen_limit_bp = rangelim(
		getMapgenParams()->mapgen_limit, 0, MAX_MAP_GENERATION_LIMIT) /
		MAP_BLOCKSIZE;
	return p.X < -mapgen_limit_bp ||
		p.X >  mapgen_limit_bp ||
		p.Y < -mapgen_limit_bp ||
		p.Y >  mapgen_limit_bp ||
		p.Z < -mapgen_limit_bp ||
		p.Z >  mapgen_limit_bp;
}

bool ServerMap::initBlockMake(v3s16 blockpos, BlockMakeData *data)
{
	s16 csize = getMapgenParams()->chunksize;
	v3s16 bpmin = EmergeManager::getContainingChunk(blockpos, csize);
	v3s16 bpmax = bpmin + v3s16(1, 1, 1) * (csize - 1);

	if (!m_chunks_in_progress.insert(bpmin).second)
		return false;

	bool enable_mapgen_debug_info = m_emerge->enable_mapgen_debug_info;
	EMERGE_DBG_OUT("initBlockMake(): " PP(bpmin) " - " PP(bpmax));

	v3s16 extra_borders(1, 1, 1);
	v3s16 full_bpmin = bpmin - extra_borders;
	v3s16 full_bpmax = bpmax + extra_borders;

	// Do nothing if not inside mapgen limits (+-1 because of neighbors)
	if (blockpos_over_mapgen_limit(full_bpmin) ||
			blockpos_over_mapgen_limit(full_bpmax))
		return false;

	data->seed = getSeed();
	data->blockpos_min = bpmin;
	data->blockpos_max = bpmax;
	data->nodedef = m_nodedef;

	/*
		Create the whole area of this and the neighboring blocks
	*/
	for (s16 x = full_bpmin.X; x <= full_bpmax.X; x++)
	for (s16 z = full_bpmin.Z; z <= full_bpmax.Z; z++) {
		v2s16 sectorpos(x, z);
		// Sector metadata is loaded from disk if not already loaded.
		MapSector *sector = createSector(sectorpos);
		FATAL_ERROR_IF(sector == NULL, "createSector() failed");

		for (s16 y = full_bpmin.Y; y <= full_bpmax.Y; y++) {
			v3s16 p(x, y, z);

			MapBlock *block = emergeBlock(p, false);
			if (block == NULL) {
				block = createBlock(p);

				// Block gets sunlight if this is true.
				// Refer to the map generator heuristics.
				bool ug = m_emerge->isBlockUnderground(p);
				block->setIsUnderground(ug);
			}
		}
	}

	/*
		Now we have a big empty area.

		Make a ManualMapVoxelManipulator that contains this and the
		neighboring blocks
	*/

	data->vmanip = new MMVManip(this);
	data->vmanip->initialEmerge(full_bpmin, full_bpmax);

	// Data is ready now.
	return true;
}

void ServerMap::finishBlockMake(BlockMakeData *data,
	std::map<v3s16, MapBlock*> *changed_blocks)
{
	v3s16 bpmin = data->blockpos_min;
	v3s16 bpmax = data->blockpos_max;

	bool enable_mapgen_debug_info = m_emerge->enable_mapgen_debug_info;
	EMERGE_DBG_OUT("finishBlockMake(): " PP(bpmin) " - " PP(bpmax));

	/*
		Blit generated stuff to map
		NOTE: blitBackAll adds nearly everything to changed_blocks
	*/
	data->vmanip->blitBackAll(changed_blocks);

	EMERGE_DBG_OUT("finishBlockMake: changed_blocks.size()="
		<< changed_blocks->size());

	/*
		Copy transforming liquid information
	*/
	while (data->transforming_liquid.size()) {
		m_transforming_liquid.push_back(data->transforming_liquid.front());
		data->transforming_liquid.pop_front();
	}

	for (auto &changed_block : *changed_blocks) {
		MapBlock *block = changed_block.second;
		if (!block)
			continue;
		/*
			Update day/night difference cache of the MapBlocks
		*/
		block->expireDayNightDiff();
		/*
			Set block as modified
		*/
		block->raiseModified(MOD_STATE_WRITE_NEEDED,
			MOD_REASON_EXPIRE_DAYNIGHTDIFF);
	}

	/*
		Set central blocks as generated
	*/
	for (s16 x = bpmin.X; x <= bpmax.X; x++)
	for (s16 z = bpmin.Z; z <= bpmax.Z; z++)
	for (s16 y = bpmin.Y; y <= bpmax.Y; y++) {
		MapBlock *block = getBlockNoCreateNoEx(v3s16(x, y, z));
		if (!block)
			continue;

		block->setGenerated(true);
	}

	/*
		Save changed parts of map
		NOTE: Will be saved later.
	*/
	//save(MOD_STATE_WRITE_AT_UNLOAD);
	m_chunks_in_progress.erase(bpmin);
}

MapSector *ServerMap::createSector(v2s16 p2d)
{
	/*
		Check if it exists already in memory
	*/
	MapSector *sector = getSectorNoGenerate(p2d);
	if (sector)
		return sector;

	/*
		Do not create over max mapgen limit
	*/
	const s16 max_limit_bp = MAX_MAP_GENERATION_LIMIT / MAP_BLOCKSIZE;
	if (p2d.X < -max_limit_bp ||
			p2d.X >  max_limit_bp ||
			p2d.Y < -max_limit_bp ||
			p2d.Y >  max_limit_bp)
		throw InvalidPositionException("createSector(): pos. over max mapgen limit");

	/*
		Generate blank sector
	*/

	sector = new MapSector(this, p2d, m_gamedef);

	// Sector position on map in nodes
	//v2s16 nodepos2d = p2d * MAP_BLOCKSIZE;

	/*
		Insert to container
	*/
	m_sectors[p2d] = sector;

	return sector;
}

MapBlock * ServerMap::createBlock(v3s16 p)
{
	/*
		Do not create over max mapgen limit
	*/
	if (blockpos_over_max_limit(p))
		throw InvalidPositionException("createBlock(): pos. over max mapgen limit");

	v2s16 p2d(p.X, p.Z);
	s16 block_y = p.Y;
	/*
		This will create or load a sector if not found in memory.
		If block exists on disk, it will be loaded.

		NOTE: On old save formats, this will be slow, as it generates
		      lighting on blocks for them.
	*/
	MapSector *sector;
	try {
		sector = createSector(p2d);
	} catch (InvalidPositionException &e) {
		infostream<<"createBlock: createSector() failed"<<std::endl;
		throw e;
	}

	/*
		Try to get a block from the sector
	*/

	MapBlock *block = sector->getBlockNoCreateNoEx(block_y);
	if (block) {
		if(block->isDummy())
			block->unDummify();
		return block;
	}
	// Create blank
	block = sector->createBlankBlock(block_y);

	return block;
}

MapBlock * ServerMap::emergeBlock(v3s16 p, bool create_blank)
{
	{
		MapBlock *block = getBlockNoCreateNoEx(p);
		if (block && !block->isDummy())
			return block;
	}

	{
		MapBlock *block = loadBlock(p);
		if(block)
			return block;
	}

	if (create_blank) {
		MapSector *sector = createSector(v2s16(p.X, p.Z));
		MapBlock *block = sector->createBlankBlock(p.Y);

		return block;
	}

	return NULL;
}

MapBlock *ServerMap::getBlockOrEmerge(v3s16 p3d)
{
	MapBlock *block = getBlockNoCreateNoEx(p3d);
	if (block == NULL)
		m_emerge->enqueueBlockEmerge(PEER_ID_INEXISTENT, p3d, false);

	return block;
}

bool ServerMap::isBlockInQueue(v3s16 pos)
{
	return m_emerge && m_emerge->isBlockInQueue(pos);
}

// N.B.  This requires no synchronization, since data will not be modified unless
// the VoxelManipulator being updated belongs to the same thread.
void ServerMap::updateVManip(v3s16 pos)
{
	Mapgen *mg = m_emerge->getCurrentMapgen();
	if (!mg)
		return;

	MMVManip *vm = mg->vm;
	if (!vm)
		return;

	if (!vm->m_area.contains(pos))
		return;

	s32 idx = vm->m_area.index(pos);
	vm->m_data[idx] = getNode(pos);
	vm->m_flags[idx] &= ~VOXELFLAG_NO_DATA;

	vm->m_is_dirty = true;
}

void ServerMap::save(ModifiedState save_level)
{
	if (!m_map_saving_enabled) {
		warningstream<<"Not saving map, saving disabled."<<std::endl;
		return;
	}

	u64 start_time = porting::getTimeNs();

	if(save_level == MOD_STATE_CLEAN)
		infostream<<"ServerMap: Saving whole map, this can take time."
				<<std::endl;

	if (m_map_metadata_changed || save_level == MOD_STATE_CLEAN) {
		if (settings_mgr.saveMapMeta())
			m_map_metadata_changed = false;
	}

	// Profile modified reasons
	Profiler modprofiler;

	u32 block_count = 0;
	u32 block_count_all = 0; // Number of blocks in memory

	// Don't do anything with sqlite unless something is really saved
	bool save_started = false;

	for (auto &sector_it : m_sectors) {
		MapSector *sector = sector_it.second;

		MapBlockVect blocks;
		sector->getBlocks(blocks);

		for (MapBlock *block : blocks) {
			block_count_all++;

			if(block->getModified() >= (u32)save_level) {
				// Lazy beginSave()
				if(!save_started) {
					beginSave();
					save_started = true;
				}

				modprofiler.add(block->getModifiedReasonString(), 1);

				saveBlock(block);
				block_count++;
			}
		}
	}

	if(save_started)
		endSave();

	/*
		Only print if something happened or saved whole map
	*/
	if(save_level == MOD_STATE_CLEAN
			|| block_count != 0) {
		infostream << "ServerMap: Written: "
				<< block_count << " blocks"
				<< ", " << block_count_all << " blocks in memory."
				<< std::endl;
		PrintInfo(infostream); // ServerMap/ClientMap:
		infostream<<"Blocks modified by: "<<std::endl;
		modprofiler.print(infostream);
	}

	auto end_time = porting::getTimeNs();
	m_save_time_counter->increment(end_time - start_time);
}

void ServerMap::listAllLoadableBlocks(std::vector<v3s16> &dst)
{
	dbase->listAllLoadableBlocks(dst);
	if (dbase_ro)
		dbase_ro->listAllLoadableBlocks(dst);
}

void ServerMap::listAllLoadedBlocks(std::vector<v3s16> &dst)
{
	for (auto &sector_it : m_sectors) {
		MapSector *sector = sector_it.second;

		MapBlockVect blocks;
		sector->getBlocks(blocks);

		for (MapBlock *block : blocks) {
			v3s16 p = block->getPos();
			dst.push_back(p);
		}
	}
}

MapDatabase *ServerMap::createDatabase(
	const std::string &name,
	const std::string &savedir,
	Settings &conf)
{
	if (name == "sqlite3")
		return new MapDatabaseSQLite3(savedir);
	if (name == "dummy")
		return new Database_Dummy();
	#if USE_LEVELDB
	if (name == "leveldb")
		return new Database_LevelDB(savedir);
	#endif
	#if USE_REDIS
	if (name == "redis")
		return new Database_Redis(conf);
	#endif
	#if USE_POSTGRESQL
	if (name == "postgresql") {
		std::string connect_string;
		conf.getNoEx("pgsql_connection", connect_string);
		return new MapDatabasePostgreSQL(connect_string);
	}
	#endif

	throw BaseException(std::string("Database backend ") + name + " not supported.");
}

void ServerMap::beginSave()
{
	dbase->beginSave();
}

void ServerMap::endSave()
{
	dbase->endSave();
}

bool ServerMap::saveBlock(MapBlock *block)
{
	return saveBlock(block, dbase, m_map_compression_level);
}

bool ServerMap::saveBlock(MapBlock *block, MapDatabase *db, int compression_level)
{
	v3s16 p3d = block->getPos();

	// Dummy blocks are not written
	if (block->isDummy()) {
		warningstream << "saveBlock: Not writing dummy block "
			<< PP(p3d) << std::endl;
		return true;
	}

	// Format used for writing
	u8 version = SER_FMT_VER_HIGHEST_WRITE;

	/*
		[0] u8 serialization version
		[1] data
	*/
	std::ostringstream o(std::ios_base::binary);
	o.write((char*) &version, 1);
	block->serialize(o, version, true, compression_level);

	bool ret = db->saveBlock(p3d, o.str());
	if (ret) {
		// We just wrote it to the disk so clear modified flag
		block->resetModified();
	}
	return ret;
}

void ServerMap::loadBlock(std::string *blob, v3s16 p3d, MapSector *sector, bool save_after_load)
{
	try {
		std::istringstream is(*blob, std::ios_base::binary);

		u8 version = SER_FMT_VER_INVALID;
		is.read((char*)&version, 1);

		if(is.fail())
			throw SerializationError("ServerMap::loadBlock(): Failed"
					" to read MapBlock version");

		MapBlock *block = NULL;
		bool created_new = false;
		block = sector->getBlockNoCreateNoEx(p3d.Y);
		if(block == NULL)
		{
			block = sector->createBlankBlockNoInsert(p3d.Y);
			created_new = true;
		}

		// Read basic data
		block->deSerialize(is, version, true);

		// If it's a new block, insert it to the map
		if (created_new) {
			sector->insertBlock(block);
			ReflowScan scanner(this, m_emerge->ndef);
			scanner.scan(block, &m_transforming_liquid);
		}

		/*
			Save blocks loaded in old format in new format
		*/

		//if(version < SER_FMT_VER_HIGHEST_READ || save_after_load)
		// Only save if asked to; no need to update version
		if(save_after_load)
			saveBlock(block);

		// We just loaded it from, so it's up-to-date.
		block->resetModified();
	}
	catch(SerializationError &e)
	{
		errorstream<<"Invalid block data in database"
				<<" ("<<p3d.X<<","<<p3d.Y<<","<<p3d.Z<<")"
				<<" (SerializationError): "<<e.what()<<std::endl;

		// TODO: Block should be marked as invalid in memory so that it is
		// not touched but the game can run

		if(g_settings->getBool("ignore_world_load_errors")){
			errorstream<<"Ignoring block load error. Duck and cover! "
					<<"(ignore_world_load_errors)"<<std::endl;
		} else {
			throw SerializationError("Invalid block data in database");
		}
	}
}

MapBlock* ServerMap::loadBlock(v3s16 blockpos)
{
	bool created_new = (getBlockNoCreateNoEx(blockpos) == NULL);

	v2s16 p2d(blockpos.X, blockpos.Z);

	std::string ret;
	dbase->loadBlock(blockpos, &ret);
	if (!ret.empty()) {
		loadBlock(&ret, blockpos, createSector(p2d), false);
	} else if (dbase_ro) {
		dbase_ro->loadBlock(blockpos, &ret);
		if (!ret.empty()) {
			loadBlock(&ret, blockpos, createSector(p2d), false);
		}
	} else {
		return NULL;
	}

	MapBlock *block = getBlockNoCreateNoEx(blockpos);
	if (created_new && (block != NULL)) {
		std::map<v3s16, MapBlock*> modified_blocks;
		// Fix lighting if necessary
		voxalgo::update_block_border_lighting(this, block, modified_blocks);
		if (!modified_blocks.empty()) {
			//Modified lighting, send event
			MapEditEvent event;
			event.type = MEET_OTHER;
			std::map<v3s16, MapBlock *>::iterator it;
			for (it = modified_blocks.begin();
					it != modified_blocks.end(); ++it)
				event.modified_blocks.insert(it->first);
			dispatchEvent(event);
		}
	}
	return block;
}

bool ServerMap::deleteBlock(v3s16 blockpos)
{
	if (!dbase->deleteBlock(blockpos))
		return false;

	MapBlock *block = getBlockNoCreateNoEx(blockpos);
	if (block) {
		v2s16 p2d(blockpos.X, blockpos.Z);
		MapSector *sector = getSectorNoGenerate(p2d);
		if (!sector)
			return false;
		sector->deleteBlock(block);
	}

	return true;
}

void ServerMap::PrintInfo(std::ostream &out)
{
	out<<"ServerMap: ";
}

bool ServerMap::repairBlockLight(v3s16 blockpos,
	std::map<v3s16, MapBlock *> *modified_blocks)
{
	MapBlock *block = emergeBlock(blockpos, false);
	if (!block || !block->isGenerated())
		return false;
	voxalgo::repair_block_light(this, block, modified_blocks);
	return true;
}

MMVManip::MMVManip(Map *map):
		VoxelManipulator(),
		m_map(map)
{
}

void MMVManip::initialEmerge(v3s16 blockpos_min, v3s16 blockpos_max,
	bool load_if_inexistent)
{
	TimeTaker timer1("initialEmerge", &emerge_time);

	// Units of these are MapBlocks
	v3s16 p_min = blockpos_min;
	v3s16 p_max = blockpos_max;

	VoxelArea block_area_nodes
			(p_min*MAP_BLOCKSIZE, (p_max+1)*MAP_BLOCKSIZE-v3s16(1,1,1));

	u32 size_MB = block_area_nodes.getVolume()*4/1000000;
	if(size_MB >= 1)
	{
		infostream<<"initialEmerge: area: ";
		block_area_nodes.print(infostream);
		infostream<<" ("<<size_MB<<"MB)";
		infostream<<std::endl;
	}

	addArea(block_area_nodes);

	for(s32 z=p_min.Z; z<=p_max.Z; z++)
	for(s32 y=p_min.Y; y<=p_max.Y; y++)
	for(s32 x=p_min.X; x<=p_max.X; x++)
	{
		u8 flags = 0;
		MapBlock *block;
		v3s16 p(x,y,z);
		std::map<v3s16, u8>::iterator n;
		n = m_loaded_blocks.find(p);
		if(n != m_loaded_blocks.end())
			continue;

		bool block_data_inexistent = false;
		{
			TimeTaker timer2("emerge load", &emerge_load_time);

			block = m_map->getBlockNoCreateNoEx(p);
			if (!block || block->isDummy())
				block_data_inexistent = true;
			else
				block->copyTo(*this);
		}

		if(block_data_inexistent)
		{

			if (load_if_inexistent && !blockpos_over_max_limit(p)) {
				ServerMap *svrmap = (ServerMap *)m_map;
				block = svrmap->emergeBlock(p, false);
				if (block == NULL)
					block = svrmap->createBlock(p);
				block->copyTo(*this);
			} else {
				flags |= VMANIP_BLOCK_DATA_INEXIST;

				/*
					Mark area inexistent
				*/
				VoxelArea a(p*MAP_BLOCKSIZE, (p+1)*MAP_BLOCKSIZE-v3s16(1,1,1));
				// Fill with VOXELFLAG_NO_DATA
				for(s32 z=a.MinEdge.Z; z<=a.MaxEdge.Z; z++)
				for(s32 y=a.MinEdge.Y; y<=a.MaxEdge.Y; y++)
				{
					s32 i = m_area.index(a.MinEdge.X,y,z);
					memset(&m_flags[i], VOXELFLAG_NO_DATA, MAP_BLOCKSIZE);
				}
			}
		}
		/*else if (block->getNode(0, 0, 0).getContent() == CONTENT_IGNORE)
		{
			// Mark that block was loaded as blank
			flags |= VMANIP_BLOCK_CONTAINS_CIGNORE;
		}*/

		m_loaded_blocks[p] = flags;
	}

	m_is_dirty = false;
}

void MMVManip::blitBackAll(std::map<v3s16, MapBlock*> *modified_blocks,
	bool overwrite_generated)
{
	if(m_area.getExtent() == v3s16(0,0,0))
		return;

	/*
		Copy data of all blocks
	*/
	for (auto &loaded_block : m_loaded_blocks) {
		v3s16 p = loaded_block.first;
		MapBlock *block = m_map->getBlockNoCreateNoEx(p);
		bool existed = !(loaded_block.second & VMANIP_BLOCK_DATA_INEXIST);
		if (!existed || (block == NULL) ||
			(!overwrite_generated && block->isGenerated()))
			continue;

		block->copyFrom(*this);
		block->raiseModified(MOD_STATE_WRITE_NEEDED, MOD_REASON_VMANIP);

		if(modified_blocks)
			(*modified_blocks)[p] = block;
	}
}

//END