Make Mapgen (mostly) work multithreaded again

builtin/settingtypes.txt

@@ -2110,9 +2110,6 @@ emergequeue_limit_diskonly (Limit of emerge queues on disk) int 64
 emergequeue_limit_generate (Limit of emerge queues to generate) int 64
 
 #    Number of emerge threads to use.
-#    WARNING: Currently there are multiple bugs that may cause crashes when
-#    'num_emerge_threads' is larger than 1. Until this warning is removed it is
-#    strongly recommended this value is set to the default '1'.
 #    Value 0:
 #    -    Automatic selection. The number of emerge threads will be
 #    -    'number of processors - 2', with a lower limit of 1.

minetest.conf.example

@@ -3261,9 +3261,6 @@
 # emergequeue_limit_generate = 64
 
 #    Number of emerge threads to use.
-#    WARNING: Currently there are multiple bugs that may cause crashes when
-#    'num_emerge_threads' is larger than 1. Until this warning is removed it is
-#    strongly recommended this value is set to the default '1'.
 #    Value 0:
 #    -    Automatic selection. The number of emerge threads will be
 #    -    'number of processors - 2', with a lower limit of 1.

src/emerge.cpp

@@ -110,6 +110,28 @@ class MapEditEventAreaIgnorer
 	VoxelArea *m_ignorevariable;
 };
 
+EmergeParams::~EmergeParams()
+{
+	infostream << "EmergeParams: destroying " << this << std::endl;
+	// Delete everything that was cloned on creation of EmergeParams
+	delete biomemgr;
+	delete oremgr;
+	delete decomgr;
+	delete schemmgr;
+}
+
+EmergeParams::EmergeParams(EmergeManager *parent, const BiomeManager *biomemgr,
+	const OreManager *oremgr, const DecorationManager *decomgr,
+	const SchematicManager *schemmgr) :
+	ndef(parent->ndef),
+	enable_mapgen_debug_info(parent->enable_mapgen_debug_info),
+	gen_notify_on(parent->gen_notify_on),
+	gen_notify_on_deco_ids(&parent->gen_notify_on_deco_ids),
+	biomemgr(biomemgr->clone()), oremgr(oremgr->clone()),
+	decomgr(decomgr->clone()), schemmgr(schemmgr->clone())
+{
+}
+
 ////
 //// EmergeManager
 ////
@@ -183,14 +205,48 @@ EmergeManager::~EmergeManager()
 }
 
 
+BiomeManager *EmergeManager::getWritableBiomeManager()
+{
+	FATAL_ERROR_IF(!m_mapgens.empty(),
+		"Writable managers can only be returned before mapgen init");
+	return biomemgr;
+}
+
+OreManager *EmergeManager::getWritableOreManager()
+{
+	FATAL_ERROR_IF(!m_mapgens.empty(),
+		"Writable managers can only be returned before mapgen init");
+	return oremgr;
+}
+
+DecorationManager *EmergeManager::getWritableDecorationManager()
+{
+	FATAL_ERROR_IF(!m_mapgens.empty(),
+		"Writable managers can only be returned before mapgen init");
+	return decomgr;
+}
+
+SchematicManager *EmergeManager::getWritableSchematicManager()
+{
+	FATAL_ERROR_IF(!m_mapgens.empty(),
+		"Writable managers can only be returned before mapgen init");
+	return schemmgr;
+}
+
+
 void EmergeManager::initMapgens(MapgenParams *params)
 {
 	FATAL_ERROR_IF(!m_mapgens.empty(), "Mapgen already initialised.");
 
 	mgparams = params;
 
-	for (u32 i = 0; i != m_threads.size(); i++)
-		m_mapgens.push_back(Mapgen::createMapgen(params->mgtype, params, this));
+	for (u32 i = 0; i != m_threads.size(); i++) {
+		EmergeParams *p = new EmergeParams(
+			this, biomemgr, oremgr, decomgr, schemmgr);
+		infostream << "EmergeManager: Created params " << p
+			<< " for thread " << i << std::endl;
+		m_mapgens.push_back(Mapgen::createMapgen(params->mgtype, params, p));
+	}
 }
 
 

src/emerge.h

@@ -44,6 +44,7 @@ class OreManager;
 class DecorationManager;
 class SchematicManager;
 class Server;
+class ModApiMapgen;
 
 // Structure containing inputs/outputs for chunk generation
 struct BlockMakeData {
@@ -86,7 +87,36 @@ struct BlockEmergeData {
 	EmergeCallbackList callbacks;
 };
 
+class EmergeParams {
+	friend class EmergeManager;
+public:
+	EmergeParams() = delete;
+	~EmergeParams();
+	DISABLE_CLASS_COPY(EmergeParams);
+
+	const NodeDefManager *ndef; // shared
+	bool enable_mapgen_debug_info;
+
+	u32 gen_notify_on;
+	const std::set<u32> *gen_notify_on_deco_ids; // shared
+
+	BiomeManager *biomemgr;
+	OreManager *oremgr;
+	DecorationManager *decomgr;
+	SchematicManager *schemmgr;
+
+private:
+	EmergeParams(EmergeManager *parent, const BiomeManager *biomemgr,
+		const OreManager *oremgr, const DecorationManager *decomgr,
+		const SchematicManager *schemmgr);
+};
+
 class EmergeManager {
+	/* The mod API needs unchecked access to allow:
+	 * - using decomgr or oremgr to place decos/ores
+	 * - using schemmgr to load and place schematics
+	 */
+	friend class ModApiMapgen;
 public:
 	const NodeDefManager *ndef;
 	bool enable_mapgen_debug_info;
@@ -106,17 +136,22 @@ class EmergeManager {
 	// Environment is not created until after script initialization.
 	MapSettingsManager *map_settings_mgr;
 
-	// Managers of various map generation-related components
-	BiomeManager *biomemgr;
-	OreManager *oremgr;
-	DecorationManager *decomgr;
-	SchematicManager *schemmgr;
-
 	// Methods
 	EmergeManager(Server *server);
 	~EmergeManager();
 	DISABLE_CLASS_COPY(EmergeManager);
 
+	// no usage restrictions
+	const BiomeManager *getBiomeManager() const { return biomemgr; }
+	const OreManager *getOreManager() const { return oremgr; }
+	const DecorationManager *getDecorationManager() const { return decomgr; }
+	const SchematicManager *getSchematicManager() const { return schemmgr; }
+	// only usable before mapgen init
+	BiomeManager *getWritableBiomeManager();
+	OreManager *getWritableOreManager();
+	DecorationManager *getWritableDecorationManager();
+	SchematicManager *getWritableSchematicManager();
+
 	void initMapgens(MapgenParams *mgparams);
 
 	void startThreads();
@@ -160,6 +195,13 @@ class EmergeManager {
 	u16 m_qlimit_diskonly;
 	u16 m_qlimit_generate;
 
+	// Managers of various map generation-related components
+	// Note that each Mapgen gets a copy(!) of these to work with
+	BiomeManager *biomemgr;
+	OreManager *oremgr;
+	DecorationManager *decomgr;
+	SchematicManager *schemmgr;
+
 	// Requires m_queue_mutex held
 	EmergeThread *getOptimalThread();
 

src/mapgen/mapgen.cpp

@@ -107,8 +107,8 @@ STATIC_ASSERT(
 //// Mapgen
 ////
 
-Mapgen::Mapgen(int mapgenid, MapgenParams *params, EmergeManager *emerge) :
-	gennotify(emerge->gen_notify_on, &emerge->gen_notify_on_deco_ids)
+Mapgen::Mapgen(int mapgenid, MapgenParams *params, EmergeParams *emerge) :
+	gennotify(emerge->gen_notify_on, emerge->gen_notify_on_deco_ids)
 {
 	id           = mapgenid;
 	water_level  = params->water_level;
@@ -157,7 +157,7 @@ const char *Mapgen::getMapgenName(MapgenType mgtype)
 
 
 Mapgen *Mapgen::createMapgen(MapgenType mgtype, MapgenParams *params,
-	EmergeManager *emerge)
+	EmergeParams *emerge)
 {
 	switch (mgtype) {
 	case MAPGEN_CARPATHIAN:
@@ -586,7 +586,7 @@ void Mapgen::spreadLight(const v3s16 &nmin, const v3s16 &nmax)
 //// MapgenBasic
 ////
 
-MapgenBasic::MapgenBasic(int mapgenid, MapgenParams *params, EmergeManager *emerge)
+MapgenBasic::MapgenBasic(int mapgenid, MapgenParams *params, EmergeParams *emerge)
 	: Mapgen(mapgenid, params, emerge)
 {
 	this->m_emerge = emerge;
@@ -636,6 +636,8 @@ MapgenBasic::~MapgenBasic()
 {
 	delete biomegen;
 	delete []heightmap;
+
+	delete m_emerge; // destroying EmergeParams is our responsibility
 }
 
 
@@ -968,7 +970,7 @@ void MapgenBasic::generateDungeons(s16 max_stone_y)
 ////
 
 GenerateNotifier::GenerateNotifier(u32 notify_on,
-	std::set<u32> *notify_on_deco_ids)
+	const std::set<u32> *notify_on_deco_ids)
 {
 	m_notify_on = notify_on;
 	m_notify_on_deco_ids = notify_on_deco_ids;
@@ -981,7 +983,8 @@ void GenerateNotifier::setNotifyOn(u32 notify_on)
 }
 
 
-void GenerateNotifier::setNotifyOnDecoIds(std::set<u32> *notify_on_deco_ids)
+void GenerateNotifier::setNotifyOnDecoIds(
+	const std::set<u32> *notify_on_deco_ids)
 {
 	m_notify_on_deco_ids = notify_on_deco_ids;
 }
@@ -993,7 +996,7 @@ bool GenerateNotifier::addEvent(GenNotifyType type, v3s16 pos, u32 id)
 		return false;
 
 	if (type == GENNOTIFY_DECORATION &&
-		m_notify_on_deco_ids->find(id) == m_notify_on_deco_ids->end())
+		m_notify_on_deco_ids->find(id) == m_notify_on_deco_ids->cend())
 		return false;
 
 	GenNotifyEvent gne;

src/mapgen/mapgen.h

@@ -51,6 +51,7 @@ class Biome;
 class BiomeGen;
 struct BiomeParams;
 class BiomeManager;
+class EmergeParams;
 class EmergeManager;
 class MapBlock;
 class VoxelManipulator;
@@ -87,18 +88,18 @@ struct GenNotifyEvent {
 class GenerateNotifier {
 public:
 	GenerateNotifier() = default;
-	GenerateNotifier(u32 notify_on, std::set<u32> *notify_on_deco_ids);
+	GenerateNotifier(u32 notify_on, const std::set<u32> *notify_on_deco_ids);
 
 	void setNotifyOn(u32 notify_on);
-	void setNotifyOnDecoIds(std::set<u32> *notify_on_deco_ids);
+	void setNotifyOnDecoIds(const std::set<u32> *notify_on_deco_ids);
 
 	bool addEvent(GenNotifyType type, v3s16 pos, u32 id=0);
 	void getEvents(std::map<std::string, std::vector<v3s16> > &event_map);
 	void clearEvents();
 
 private:
 	u32 m_notify_on = 0;
-	std::set<u32> *m_notify_on_deco_ids;
+	const std::set<u32> *m_notify_on_deco_ids;
 	std::list<GenNotifyEvent> m_notify_events;
 };
 
@@ -176,7 +177,7 @@ class Mapgen {
 	GenerateNotifier gennotify;
 
 	Mapgen() = default;
-	Mapgen(int mapgenid, MapgenParams *params, EmergeManager *emerge);
+	Mapgen(int mapgenid, MapgenParams *params, EmergeParams *emerge);
 	virtual ~Mapgen() = default;
 	DISABLE_CLASS_COPY(Mapgen);
 
@@ -215,7 +216,7 @@ class Mapgen {
 	static MapgenType getMapgenType(const std::string &mgname);
 	static const char *getMapgenName(MapgenType mgtype);
 	static Mapgen *createMapgen(MapgenType mgtype, MapgenParams *params,
-		EmergeManager *emerge);
+		EmergeParams *emerge);
 	static MapgenParams *createMapgenParams(MapgenType mgtype);
 	static void getMapgenNames(std::vector<const char *> *mgnames, bool include_hidden);
 	static void setDefaultSettings(Settings *settings);
@@ -243,7 +244,7 @@ class Mapgen {
 */
 class MapgenBasic : public Mapgen {
 public:
-	MapgenBasic(int mapgenid, MapgenParams *params, EmergeManager *emerge);
+	MapgenBasic(int mapgenid, MapgenParams *params, EmergeParams *emerge);
 	virtual ~MapgenBasic();
 
 	virtual void generateBiomes();
@@ -254,7 +255,7 @@ class MapgenBasic : public Mapgen {
 	virtual void generateDungeons(s16 max_stone_y);
 
 protected:
-	EmergeManager *m_emerge;
+	EmergeParams *m_emerge;
 	BiomeManager *m_bmgr;
 
 	Noise *noise_filler_depth;

src/mapgen/mapgen_carpathian.cpp

@@ -50,7 +50,7 @@ FlagDesc flagdesc_mapgen_carpathian[] = {
 ///////////////////////////////////////////////////////////////////////////////
 
 
-MapgenCarpathian::MapgenCarpathian(MapgenCarpathianParams *params, EmergeManager *emerge)
+MapgenCarpathian::MapgenCarpathian(MapgenCarpathianParams *params, EmergeParams *emerge)
 	: MapgenBasic(MAPGEN_CARPATHIAN, params, emerge)
 {
 	base_level       = params->base_level;

src/mapgen/mapgen_carpathian.h

@@ -79,7 +79,7 @@ struct MapgenCarpathianParams : public MapgenParams
 class MapgenCarpathian : public MapgenBasic
 {
 public:
-	MapgenCarpathian(MapgenCarpathianParams *params, EmergeManager *emerge);
+	MapgenCarpathian(MapgenCarpathianParams *params, EmergeParams *emerge);
 	~MapgenCarpathian();
 
 	virtual MapgenType getType() const { return MAPGEN_CARPATHIAN; }

src/mapgen/mapgen_flat.cpp

@@ -48,7 +48,7 @@ FlagDesc flagdesc_mapgen_flat[] = {
 ///////////////////////////////////////////////////////////////////////////////////////
 
 
-MapgenFlat::MapgenFlat(MapgenFlatParams *params, EmergeManager *emerge)
+MapgenFlat::MapgenFlat(MapgenFlatParams *params, EmergeParams *emerge)
 	: MapgenBasic(MAPGEN_FLAT, params, emerge)
 {
 	spflags            = params->spflags;

src/mapgen/mapgen_flat.h

@@ -64,7 +64,7 @@ struct MapgenFlatParams : public MapgenParams
 class MapgenFlat : public MapgenBasic
 {
 public:
-	MapgenFlat(MapgenFlatParams *params, EmergeManager *emerge);
+	MapgenFlat(MapgenFlatParams *params, EmergeParams *emerge);
 	~MapgenFlat();
 
 	virtual MapgenType getType() const { return MAPGEN_FLAT; }

src/mapgen/mapgen_fractal.cpp

@@ -48,7 +48,7 @@ FlagDesc flagdesc_mapgen_fractal[] = {
 ///////////////////////////////////////////////////////////////////////////////////////
 
 
-MapgenFractal::MapgenFractal(MapgenFractalParams *params, EmergeManager *emerge)
+MapgenFractal::MapgenFractal(MapgenFractalParams *params, EmergeParams *emerge)
 	: MapgenBasic(MAPGEN_FRACTAL, params, emerge)
 {
 	spflags            = params->spflags;

src/mapgen/mapgen_fractal.h

@@ -72,7 +72,7 @@ struct MapgenFractalParams : public MapgenParams
 class MapgenFractal : public MapgenBasic
 {
 public:
-	MapgenFractal(MapgenFractalParams *params, EmergeManager *emerge);
+	MapgenFractal(MapgenFractalParams *params, EmergeParams *emerge);
 	~MapgenFractal();
 
 	virtual MapgenType getType() const { return MAPGEN_FRACTAL; }

src/mapgen/mapgen_singlenode.cpp

@@ -29,7 +29,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "emerge.h"
 
 
-MapgenSinglenode::MapgenSinglenode(MapgenParams *params, EmergeManager *emerge)
+MapgenSinglenode::MapgenSinglenode(MapgenParams *params, EmergeParams *emerge)
 	: Mapgen(MAPGEN_SINGLENODE, params, emerge)
 {
 	const NodeDefManager *ndef = emerge->ndef;

src/mapgen/mapgen_singlenode.h

@@ -38,7 +38,7 @@ class MapgenSinglenode : public Mapgen
 	content_t c_node;
 	u8 set_light;
 
-	MapgenSinglenode(MapgenParams *params, EmergeManager *emerge);
+	MapgenSinglenode(MapgenParams *params, EmergeParams *emerge);
 	~MapgenSinglenode() = default;
 
 	virtual MapgenType getType() const { return MAPGEN_SINGLENODE; }