Avoid generating the same chunk more than once with multiple emerge threads.

src/emerge.h

@@ -52,7 +52,6 @@ struct BlockMakeData {
 	u64 seed = 0;
 	v3s16 blockpos_min;
 	v3s16 blockpos_max;
-	v3s16 blockpos_requested;
 	UniqueQueue<v3s16> transforming_liquid;
 	const NodeDefManager *nodedef = nullptr;
 

src/map.cpp

@@ -1345,6 +1345,9 @@ bool ServerMap::initBlockMake(v3s16 blockpos, BlockMakeData *data)
 	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));
 
@@ -1360,7 +1363,6 @@ bool ServerMap::initBlockMake(v3s16 blockpos, BlockMakeData *data)
 	data->seed = getSeed();
 	data->blockpos_min = bpmin;
 	data->blockpos_max = bpmax;
-	data->blockpos_requested = blockpos;
 	data->nodedef = m_nodedef;
 
 	/*
@@ -1482,6 +1484,7 @@ void ServerMap::finishBlockMake(BlockMakeData *data,
 		NOTE: Will be saved later.
 	*/
 	//save(MOD_STATE_WRITE_AT_UNLOAD);
+	m_chunks_in_progress.erase(bpmin);
 }
 
 MapSector *ServerMap::createSector(v2s16 p2d)

src/map.h

@@ -423,6 +423,7 @@ private:
 	// Chunks
 	core::map<v2s16, MapChunk*> m_chunks;
 #endif
+	std::set<v3s16> m_chunks_in_progress;
 
 	/*
 		Metadata is re-written on disk only if this is true.

src/mapgen/mapgen_carpathian.cpp

@@ -260,12 +260,6 @@ void MapgenCarpathian::makeChunk(BlockMakeData *data)
 	// Pre-conditions
 	assert(data->vmanip);
 	assert(data->nodedef);
-	assert(data->blockpos_requested.X >= data->blockpos_min.X &&
-			data->blockpos_requested.Y >= data->blockpos_min.Y &&
-			data->blockpos_requested.Z >= data->blockpos_min.Z);
-	assert(data->blockpos_requested.X <= data->blockpos_max.X &&
-			data->blockpos_requested.Y <= data->blockpos_max.Y &&
-			data->blockpos_requested.Z <= data->blockpos_max.Z);
 
 	this->generating = true;
 	this->vm = data->vmanip;

src/mapgen/mapgen_flat.cpp

@@ -209,12 +209,6 @@ void MapgenFlat::makeChunk(BlockMakeData *data)
 	// Pre-conditions
 	assert(data->vmanip);
 	assert(data->nodedef);
-	assert(data->blockpos_requested.X >= data->blockpos_min.X &&
-		data->blockpos_requested.Y >= data->blockpos_min.Y &&
-		data->blockpos_requested.Z >= data->blockpos_min.Z);
-	assert(data->blockpos_requested.X <= data->blockpos_max.X &&
-		data->blockpos_requested.Y <= data->blockpos_max.Y &&
-		data->blockpos_requested.Z <= data->blockpos_max.Z);
 
 	this->generating = true;
 	this->vm   = data->vmanip;

src/mapgen/mapgen_fractal.cpp

@@ -209,12 +209,6 @@ void MapgenFractal::makeChunk(BlockMakeData *data)
 	// Pre-conditions
 	assert(data->vmanip);
 	assert(data->nodedef);
-	assert(data->blockpos_requested.X >= data->blockpos_min.X &&
-		data->blockpos_requested.Y >= data->blockpos_min.Y &&
-		data->blockpos_requested.Z >= data->blockpos_min.Z);
-	assert(data->blockpos_requested.X <= data->blockpos_max.X &&
-		data->blockpos_requested.Y <= data->blockpos_max.Y &&
-		data->blockpos_requested.Z <= data->blockpos_max.Z);
 
 	//TimeTaker t("makeChunk");
 

src/mapgen/mapgen_singlenode.cpp

@@ -50,12 +50,6 @@ void MapgenSinglenode::makeChunk(BlockMakeData *data)
 	// Pre-conditions
 	assert(data->vmanip);
 	assert(data->nodedef);
-	assert(data->blockpos_requested.X >= data->blockpos_min.X &&
-		data->blockpos_requested.Y >= data->blockpos_min.Y &&
-		data->blockpos_requested.Z >= data->blockpos_min.Z);
-	assert(data->blockpos_requested.X <= data->blockpos_max.X &&
-		data->blockpos_requested.Y <= data->blockpos_max.Y &&
-		data->blockpos_requested.Z <= data->blockpos_max.Z);
 
 	this->generating = true;
 	this->vm   = data->vmanip;

src/mapgen/mapgen_v5.cpp

@@ -201,12 +201,6 @@ void MapgenV5::makeChunk(BlockMakeData *data)
 	// Pre-conditions
 	assert(data->vmanip);
 	assert(data->nodedef);
-	assert(data->blockpos_requested.X >= data->blockpos_min.X &&
-		data->blockpos_requested.Y >= data->blockpos_min.Y &&
-		data->blockpos_requested.Z >= data->blockpos_min.Z);
-	assert(data->blockpos_requested.X <= data->blockpos_max.X &&
-		data->blockpos_requested.Y <= data->blockpos_max.Y &&
-		data->blockpos_requested.Z <= data->blockpos_max.Z);
 
 	this->generating = true;
 	this->vm   = data->vmanip;

src/mapgen/mapgen_v6.cpp

@@ -512,12 +512,6 @@ void MapgenV6::makeChunk(BlockMakeData *data)
 	// Pre-conditions
 	assert(data->vmanip);
 	assert(data->nodedef);
-	assert(data->blockpos_requested.X >= data->blockpos_min.X &&
-		data->blockpos_requested.Y >= data->blockpos_min.Y &&
-		data->blockpos_requested.Z >= data->blockpos_min.Z);
-	assert(data->blockpos_requested.X <= data->blockpos_max.X &&
-		data->blockpos_requested.Y <= data->blockpos_max.Y &&
-		data->blockpos_requested.Z <= data->blockpos_max.Z);
 
 	this->generating = true;
 	this->vm   = data->vmanip;

src/mapgen/mapgen_v7.cpp

@@ -317,12 +317,6 @@ void MapgenV7::makeChunk(BlockMakeData *data)
 	// Pre-conditions
 	assert(data->vmanip);
 	assert(data->nodedef);
-	assert(data->blockpos_requested.X >= data->blockpos_min.X &&
-		data->blockpos_requested.Y >= data->blockpos_min.Y &&
-		data->blockpos_requested.Z >= data->blockpos_min.Z);
-	assert(data->blockpos_requested.X <= data->blockpos_max.X &&
-		data->blockpos_requested.Y <= data->blockpos_max.Y &&
-		data->blockpos_requested.Z <= data->blockpos_max.Z);
 
 	//TimeTaker t("makeChunk");
 

src/mapgen/mapgen_valleys.cpp

@@ -210,12 +210,6 @@ void MapgenValleys::makeChunk(BlockMakeData *data)
 	// Pre-conditions
 	assert(data->vmanip);
 	assert(data->nodedef);
-	assert(data->blockpos_requested.X >= data->blockpos_min.X &&
-		data->blockpos_requested.Y >= data->blockpos_min.Y &&
-		data->blockpos_requested.Z >= data->blockpos_min.Z);
-	assert(data->blockpos_requested.X <= data->blockpos_max.X &&
-		data->blockpos_requested.Y <= data->blockpos_max.Y &&
-		data->blockpos_requested.Z <= data->blockpos_max.Z);
 
 	//TimeTaker t("makeChunk");