11 files changed, 293 insertions, 51 deletions

diff --git a/src/ChunkDef.h b/src/ChunkDef.h
index 260aace58..8f1d416ad 100644
--- a/src/ChunkDef.h
+++ b/src/ChunkDef.h
@@ -410,7 +410,7 @@ typedef std::list<cChunkCoordsWithBool> cChunkCoordsWithBoolList;
 
 
 
-/// Interface class used as a callback for operations that involve chunk coords
+/** Interface class used as a callback for operations that involve chunk coords */
 class cChunkCoordCallback
 {
 public:
@@ -424,6 +424,27 @@ public:
 
 
 
+/** Provides storage for a set of chunk coords together with a callback.
+Used for chunk queues that notify about processed items. */
+class cChunkCoordsWithCallback
+{
+public:
+	cChunkCoordsWithCallback(int a_ChunkX, int a_ChunkZ, cChunkCoordCallback * a_Callback):
+		m_ChunkX(a_ChunkX),
+		m_ChunkZ(a_ChunkZ),
+		m_Callback(a_Callback)
+	{
+	}
+
+	int m_ChunkX;
+	int m_ChunkZ;
+	cChunkCoordCallback * m_Callback;
+};
+
+
+
+
+
 /** Generic template that can store any kind of data together with a triplet of 3 coords*/
 template <typename X> class cCoordWithData
 {
diff --git a/src/ChunkMap.cpp b/src/ChunkMap.cpp
index 8a8f17a1b..222a756b1 100644
--- a/src/ChunkMap.cpp
+++ b/src/ChunkMap.cpp
@@ -2349,6 +2349,103 @@ void cChunkMap::TouchChunk(int a_ChunkX, int a_ChunkZ)
 
 
 
+void cChunkMap::PrepareChunk(int a_ChunkX, int a_ChunkZ, cChunkCoordCallback * a_Callback)
+{
+	cCSLock Lock(m_CSLayers);
+	cChunkPtr Chunk = GetChunkNoLoad(a_ChunkX, a_ChunkZ);
+
+	// If the chunk is not prepared, queue it in the lighting thread, that will do all the needed processing:
+	if ((Chunk == nullptr) || !Chunk->IsValid() || !Chunk->IsLightValid())
+	{
+		m_World->GetLightingThread().QueueChunk(a_ChunkX, a_ChunkZ, a_Callback);
+		return;
+	}
+
+	// The chunk is present and lit, just call the callback:
+	if (a_Callback != nullptr)
+	{
+		a_Callback->Call(a_ChunkX, a_ChunkZ);
+	}
+}
+
+
+
+
+
+bool cChunkMap::GenerateChunk(int a_ChunkX, int a_ChunkZ, cChunkCoordCallback * a_Callback)
+{
+	cCSLock Lock(m_CSLayers);
+	cChunkPtr Chunk = GetChunkNoLoad(a_ChunkX, a_ChunkZ);
+	if (Chunk == nullptr)
+	{
+		// Generic error while getting the chunk - out of memory?
+		return false;
+	}
+
+	// Try loading the chunk:
+	if ((Chunk == nullptr) || (!Chunk->IsValid()))
+	{
+		class cPrepareLoadCallback: public cChunkCoordCallback
+		{
+		public:
+			cPrepareLoadCallback(cWorld & a_World, cChunkMap & a_ChunkMap, cChunkCoordCallback * a_Callback):
+				m_World(a_World),
+				m_ChunkMap(a_ChunkMap),
+				m_Callback(a_Callback)
+			{
+			}
+
+			// cChunkCoordCallback override:
+			virtual void Call(int a_CBChunkX, int a_CBChunkZ) override
+			{
+				// The chunk has been loaded or an error occurred, check if it's valid now:
+				cChunkPtr CBChunk = m_ChunkMap.GetChunkNoLoad(a_CBChunkX, a_CBChunkZ);
+
+				if (CBChunk == nullptr)
+				{
+					// An error occurred, but we promised to call the callback, so call it even when there's no real chunk data:
+					if (m_Callback != nullptr)
+					{
+						m_Callback->Call(a_CBChunkX, a_CBChunkZ);
+					}
+					return;
+				}
+
+				// If the chunk is not valid, queue it in the generator:
+				if (!CBChunk->IsValid())
+				{
+					m_World.GetGenerator().QueueGenerateChunk(a_CBChunkX, a_CBChunkZ, false, m_Callback);
+					return;
+				}
+
+				// The chunk was loaded, call the callback:
+				if (m_Callback != nullptr)
+				{
+					m_Callback->Call(a_CBChunkX, a_CBChunkZ);
+				}
+			}
+
+		protected:
+			cWorld & m_World;
+			cChunkMap & m_ChunkMap;
+			cChunkCoordCallback * m_Callback;
+		};
+		m_World->GetStorage().QueueLoadChunk(a_ChunkX, a_ChunkZ, new cPrepareLoadCallback(*m_World, *this, a_Callback));
+		return true;
+	}
+
+	// The chunk is valid, just call the callback:
+	if (a_Callback != nullptr)
+	{
+		a_Callback->Call(a_ChunkX, a_ChunkZ);
+	}
+	return true;
+}
+
+
+
+
+
 void cChunkMap::ChunkLoadFailed(int a_ChunkX, int a_ChunkZ)
 {
 	cCSLock Lock(m_CSLayers);
diff --git a/src/ChunkMap.h b/src/ChunkMap.h
index 51be5cb3d..6a858b06d 100644
--- a/src/ChunkMap.h
+++ b/src/ChunkMap.h
@@ -280,6 +280,20 @@ public:
 
 	/** Touches the chunk, causing it to be loaded or generated */
 	void TouchChunk(int a_ChunkX, int a_ChunkZ);
+
+	/** Queues the chunk for preparing - making sure that it's generated and lit.
+	The specified chunk is queued to be loaded or generated, and lit if needed.
+	The specified callback is called after the chunk has been prepared. If there's no preparation to do, only the callback is called.
+	It is legal to call without the callback. */
+	void PrepareChunk(int a_ChunkX, int a_ChunkZ, cChunkCoordCallback * a_CallAfter = nullptr);  // Lua-accessible
+
+	/** Queues the chunk for generating.
+	First attempts to load the chunk from the storage. If that fails, queues the chunk for generating.
+	The specified callback is called after the chunk has been loaded / generated.
+	It is legal to call without the callback.
+	Returns true if successful, false if not (possibly an out-of-memory error).
+	If the return value is true, the callback was / will be called. */
+	bool GenerateChunk(int a_ChunkX, int a_ChunkZ, cChunkCoordCallback * a_CallAfter = nullptr);  // Lua-accessible
 	
 	/** Marks the chunk as failed-to-load */
 	void ChunkLoadFailed(int a_ChunkX, int a_ChunkZ);
diff --git a/src/Generating/ChunkGenerator.cpp b/src/Generating/ChunkGenerator.cpp
index d2e7b47b4..854aac60d 100644
--- a/src/Generating/ChunkGenerator.cpp
+++ b/src/Generating/ChunkGenerator.cpp
@@ -110,29 +110,19 @@ void cChunkGenerator::Stop(void)
 
 
 
-void cChunkGenerator::QueueGenerateChunk(int a_ChunkX, int a_ChunkZ, bool a_ForceGenerate)
+void cChunkGenerator::QueueGenerateChunk(int a_ChunkX, int a_ChunkZ, bool a_ForceGenerate, cChunkCoordCallback * a_Callback)
 {
 	ASSERT(m_ChunkSink->IsChunkQueued(a_ChunkX, a_ChunkZ));
 
 	{
 		cCSLock Lock(m_CS);
 
-		// Check if it is already in the queue:
-		for (cChunkCoordsWithBoolList::iterator itr = m_Queue.begin(); itr != m_Queue.end(); ++itr)
-		{
-			if ((itr->m_ChunkX == a_ChunkX) && (itr->m_ChunkZ == a_ChunkZ))
-			{
-				// Already in the queue, bail out
-				return;
-			}
-		}  // for itr - m_Queue[]
-
 		// Add to queue, issue a warning if too many:
 		if (m_Queue.size() >= QUEUE_WARNING_LIMIT)
 		{
 			LOGWARN("WARNING: Adding chunk [%i, %i] to generation queue; Queue is too big! (" SIZE_T_FMT ")", a_ChunkX, a_ChunkZ, m_Queue.size());
 		}
-		m_Queue.push_back(cChunkCoordsWithBool(a_ChunkX, a_ChunkZ, a_ForceGenerate));
+		m_Queue.push_back(cQueueItem{a_ChunkX, a_ChunkZ, a_ForceGenerate, a_Callback});
 	}
 
 	m_Event.Set();
@@ -242,9 +232,9 @@ void cChunkGenerator::Execute(void)
 			continue;
 		}
 
-		cChunkCoordsWithBool coords = m_Queue.front();  // Get next coord from queue
+		cQueueItem item = m_Queue.front();  // Get next chunk from the queue
 		bool SkipEnabled = (m_Queue.size() > QUEUE_SKIP_LIMIT);
-		m_Queue.erase(m_Queue.begin());  // Remove coordinate from queue
+		m_Queue.erase(m_Queue.begin());  // Remove the item from the queue
 		Lock.Unlock();  // Unlock ASAP
 		m_evtRemoved.Set();
 
@@ -258,22 +248,35 @@ void cChunkGenerator::Execute(void)
 			LastReportTick = clock();
 		}
 
-		if (!coords.m_ForceGenerate && m_ChunkSink->IsChunkValid(coords.m_ChunkX, coords.m_ChunkZ))
+		// Skip the chunk if it's already generated and regeneration is not forced:
+		if (!item.m_ForceGenerate && m_ChunkSink->IsChunkValid(item.m_ChunkX, item.m_ChunkZ))
 		{
-			LOGD("Chunk [%d, %d] already generated, skipping generation", coords.m_ChunkX, coords.m_ChunkZ);
-			// Already generated, ignore request
+			LOGD("Chunk [%d, %d] already generated, skipping generation", item.m_ChunkX, item.m_ChunkZ);
+			if (item.m_Callback != nullptr)
+			{
+				item.m_Callback->Call(item.m_ChunkX, item.m_ChunkZ);
+			}
 			continue;
 		}
 
-		if (SkipEnabled && !m_ChunkSink->HasChunkAnyClients(coords.m_ChunkX, coords.m_ChunkZ))
+		// Skip the chunk if the generator is overloaded:
+		if (SkipEnabled && !m_ChunkSink->HasChunkAnyClients(item.m_ChunkX, item.m_ChunkZ))
 		{
-			LOGWARNING("Chunk generator overloaded, skipping chunk [%d, %d]", coords.m_ChunkX, coords.m_ChunkZ);
+			LOGWARNING("Chunk generator overloaded, skipping chunk [%d, %d]", item.m_ChunkX, item.m_ChunkZ);
+			if (item.m_Callback != nullptr)
+			{
+				item.m_Callback->Call(item.m_ChunkX, item.m_ChunkZ);
+			}
 			continue;
 		}
 
-		LOGD("Generating chunk [%d, %d]", coords.m_ChunkX, coords.m_ChunkZ);
-		DoGenerate(coords.m_ChunkX, coords.m_ChunkZ);
-
+		// Generate the chunk:
+		LOGD("Generating chunk [%d, %d]", item.m_ChunkX, item.m_ChunkZ);
+		DoGenerate(item.m_ChunkX, item.m_ChunkZ);
+		if (item.m_Callback != nullptr)
+		{
+			item.m_Callback->Call(item.m_ChunkX, item.m_ChunkZ);
+		}
 		NumChunksGenerated++;
 	}  // while (!bStop)
 }
diff --git a/src/Generating/ChunkGenerator.h b/src/Generating/ChunkGenerator.h
index 190d9e616..4af486ae1 100644
--- a/src/Generating/ChunkGenerator.h
+++ b/src/Generating/ChunkGenerator.h
@@ -119,8 +119,12 @@ public:
 	bool Start(cPluginInterface & a_PluginInterface, cChunkSink & a_ChunkSink, cIniFile & a_IniFile);
 	void Stop(void);
 
-	/// Queues the chunk for generation; removes duplicate requests
-	void QueueGenerateChunk(int a_ChunkX, int a_ChunkZ, bool a_ForceGenerate);
+	/** Queues the chunk for generation
+	If a-ForceGenerate is set, the chunk is regenerated even if the data is already present in the chunksink.
+	a_Callback is called after the chunk is generated. If the chunk was already present, the callback is still called, even if not regenerating.
+	It is legal to set the callback to nullptr, no callback is called then.
+	If the generator becomes overloaded and skips this chunk, the callback is still called. */
+	void QueueGenerateChunk(int a_ChunkX, int a_ChunkZ, bool a_ForceGenerate, cChunkCoordCallback * a_Callback = nullptr);
 	
 	/// Generates the biomes for the specified chunk (directly, not in a separate thread). Used by the world loader if biomes failed loading.
 	void GenerateBiomes(int a_ChunkX, int a_ChunkZ, cChunkDef::BiomeMap & a_BiomeMap);
@@ -131,22 +135,46 @@ public:
 	
 	int GetSeed(void) const { return m_Seed; }
 	
-	/// Returns the biome at the specified coords. Used by ChunkMap if an invalid chunk is queried for biome
+	/** Returns the biome at the specified coords. Used by ChunkMap if an invalid chunk is queried for biome */
 	EMCSBiome GetBiomeAt(int a_BlockX, int a_BlockZ);
 
-	/// Reads a block type from the ini file; returns the blocktype on success, emits a warning and returns a_Default's representation on failure.
+	/** Reads a block type from the ini file; returns the blocktype on success, emits a warning and returns a_Default's representation on failure. */
 	static BLOCKTYPE GetIniBlock(cIniFile & a_IniFile, const AString & a_SectionName, const AString & a_ValueName, const AString & a_Default);
 	
 private:
 
+	struct cQueueItem
+	{
+		/** The chunk coords */
+		int m_ChunkX, m_ChunkZ;
+
+		/** Force the regeneration of an already existing chunk */
+		bool m_ForceGenerate;
+
+		/** Callback to call after generating.*/
+		cChunkCoordCallback * m_Callback;
+	};
+
+	typedef std::list<cQueueItem> cGenQueue;
+
+
+	/** Seed used for the generator. */
 	int m_Seed;
 
-	cCriticalSection         m_CS;
-	cChunkCoordsWithBoolList m_Queue;
-	cEvent                   m_Event;       ///< Set when an item is added to the queue or the thread should terminate
-	cEvent                   m_evtRemoved;  ///< Set when an item is removed from the queue
+	/** CS protecting access to the queue. */
+	cCriticalSection m_CS;
+
+	/** Queue of the chunks to be generated. Protected against multithreaded access by m_CS. */
+	cGenQueue m_Queue;
+
+	/** Set when an item is added to the queue or the thread should terminate. */
+	cEvent m_Event;
+
+	/** Set when an item is removed from the queue. */
+	cEvent m_evtRemoved;
 	
-	cGenerator * m_Generator;  ///< The actual generator engine used to generate chunks
+	/** The actual generator engine used to generate chunks. */
+	cGenerator * m_Generator;
 	
 	/** The plugin interface that may modify the generated chunks */
 	cPluginInterface * m_PluginInterface;
@@ -158,6 +186,7 @@ private:
 	// cIsThread override:
 	virtual void Execute(void) override;
 
+	/** Generates the specified chunk and sets it into the chunksink. */
 	void DoGenerate(int a_ChunkX, int a_ChunkZ);
 };
 
diff --git a/src/LightingThread.cpp b/src/LightingThread.cpp
index ae5e746e7..01ba24105 100644
--- a/src/LightingThread.cpp
+++ b/src/LightingThread.cpp
@@ -236,6 +236,16 @@ void cLightingThread::Execute(void)
 
 void cLightingThread::LightChunk(cLightingChunkStay & a_Item)
 {
+	// If the chunk is already lit, skip it:
+	if (m_World->IsChunkLighted(a_Item.m_ChunkX, a_Item.m_ChunkZ))
+	{
+		if (a_Item.m_CallbackAfter != nullptr)
+		{
+			a_Item.m_CallbackAfter->Call(a_Item.m_ChunkX, a_Item.m_ChunkZ);
+		}
+		return;
+	}
+
 	cChunkDef::BlockNibbles BlockLight, SkyLight;
 	
 	ReadChunks(a_Item.m_ChunkX, a_Item.m_ChunkZ);
diff --git a/src/OSSupport/Queue.h b/src/OSSupport/Queue.h
index 8d096fe29..82f221453 100644
--- a/src/OSSupport/Queue.h
+++ b/src/OSSupport/Queue.h
@@ -163,6 +163,29 @@ public:
 		return false;
 	}
 
+
+	/** Removes all items for which the predicate returns true. */
+	template <class Predicate>
+	void RemoveIf(Predicate a_Predicate)
+	{
+		cCSLock Lock(m_CS);
+		for (auto itr = m_Contents.begin(); itr != m_Contents.end();)
+		{
+			if (a_Predicate(*itr))
+			{
+				auto itr2 = itr;
+				++itr2;
+				m_Contents.erase(itr);
+				m_evtRemoved.Set();
+				itr = itr2;
+			}
+			else
+			{
+				++itr;
+			}
+		}  // for itr - m_Contents[]
+	}
+
 private:
 	/// The contents of the queue
 	QueueType m_Contents;
diff --git a/src/World.cpp b/src/World.cpp
index db19649f3..1bee6e344 100644
--- a/src/World.cpp
+++ b/src/World.cpp
@@ -115,7 +115,7 @@ public:
 		{
 			int chunkX, chunkZ;
 			DecodeChunkCoords(i, chunkX, chunkZ);
-			m_World.GetLightingThread().QueueChunk(chunkX, chunkZ, this);
+			m_World.PrepareChunk(chunkX, chunkZ, this);
 		}  // for i
 
 		// Wait for the lighting thread to prepare everything. Event is set in the Call() callback:
@@ -2907,6 +2907,15 @@ void cWorld::TouchChunk(int a_ChunkX, int a_ChunkZ)
 
 
 
+void cWorld::PrepareChunk(int a_ChunkX, int a_ChunkZ, cChunkCoordCallback * a_CallAfter)
+{
+	m_ChunkMap->PrepareChunk(a_ChunkX, a_ChunkZ, a_CallAfter);
+}
+
+
+
+
+
 void cWorld::ChunkLoadFailed(int a_ChunkX, int a_ChunkZ)
 {
 	m_ChunkMap->ChunkLoadFailed(a_ChunkX, a_ChunkZ);
@@ -3017,7 +3026,7 @@ void cWorld::RegenerateChunk(int a_ChunkX, int a_ChunkZ)
 
 void cWorld::GenerateChunk(int a_ChunkX, int a_ChunkZ)
 {
-	m_ChunkMap->TouchChunk(a_ChunkX, a_ChunkZ);
+	m_ChunkMap->GenerateChunk(a_ChunkX, a_ChunkZ);
 }
 
 
diff --git a/src/World.h b/src/World.h
index 2f51d60a1..6f28ba534 100644
--- a/src/World.h
+++ b/src/World.h
@@ -375,6 +375,12 @@ public:
 	
 	/** Touches the chunk, causing it to be loaded or generated */
 	void TouchChunk(int a_ChunkX, int a_ChunkZ);
+
+	/** Queues the chunk for preparing - making sure that it's generated and lit.
+	The specified chunk is queued to be loaded or generated, and lit if needed.
+	The specified callback is called after the chunk has been prepared. If there's no preparation to do, only the callback is called.
+	It is legal to call with no callback. */
+	void PrepareChunk(int a_ChunkX, int a_ChunkZ, cChunkCoordCallback * a_CallAfter = nullptr);
 	
 	/** Marks the chunk as failed-to-load: */
 	void ChunkLoadFailed(int a_ChunkX, int a_ChunkZ);
diff --git a/src/WorldStorage/WorldStorage.cpp b/src/WorldStorage/WorldStorage.cpp
index 31318ee67..c7a295175 100644
--- a/src/WorldStorage/WorldStorage.cpp
+++ b/src/WorldStorage/WorldStorage.cpp
@@ -140,11 +140,11 @@ size_t cWorldStorage::GetSaveQueueLength(void)
 
 
 
-void cWorldStorage::QueueLoadChunk(int a_ChunkX, int a_ChunkZ)
+void cWorldStorage::QueueLoadChunk(int a_ChunkX, int a_ChunkZ, cChunkCoordCallback * a_Callback)
 {
 	ASSERT(m_World->IsChunkQueued(a_ChunkX, a_ChunkZ));
 
-	m_LoadQueue.EnqueueItem(cChunkCoords(a_ChunkX, a_ChunkZ));
+	m_LoadQueue.EnqueueItem(cChunkCoordsWithCallback(a_ChunkX, a_ChunkZ, a_Callback));
 	m_Event.Set();
 }
 
@@ -152,11 +152,11 @@ void cWorldStorage::QueueLoadChunk(int a_ChunkX, int a_ChunkZ)
 
 
 
-void cWorldStorage::QueueSaveChunk(int a_ChunkX, int a_ChunkZ)
+void cWorldStorage::QueueSaveChunk(int a_ChunkX, int a_ChunkZ, cChunkCoordCallback * a_Callback)
 {
 	ASSERT(m_World->IsChunkValid(a_ChunkX, a_ChunkZ));
 
-	m_SaveQueue.EnqueueItemIfNotPresent(cChunkCoords(a_ChunkX, a_ChunkZ));
+	m_SaveQueue.EnqueueItem(cChunkCoordsWithCallback(a_ChunkX, a_ChunkZ, a_Callback));
 	m_Event.Set();
 }
 
@@ -166,7 +166,11 @@ void cWorldStorage::QueueSaveChunk(int a_ChunkX, int a_ChunkZ)
 
 void cWorldStorage::UnqueueLoad(int a_ChunkX, int a_ChunkZ)
 {
-	m_LoadQueue.Remove(cChunkCoords(a_ChunkX, a_ChunkZ));
+	m_LoadQueue.RemoveIf([=](cChunkCoordsWithCallback & a_Item)
+		{
+			return (a_Item.m_ChunkX == a_ChunkX) && (a_Item.m_ChunkZ == a_ChunkZ);
+		}
+	);
 }
 
 
@@ -175,7 +179,11 @@ void cWorldStorage::UnqueueLoad(int a_ChunkX, int a_ChunkZ)
 
 void cWorldStorage::UnqueueSave(const cChunkCoords & a_Chunk)
 {
-	m_SaveQueue.Remove(a_Chunk);
+	m_SaveQueue.RemoveIf([=](cChunkCoordsWithCallback & a_Item)
+		{
+			return (a_Item.m_ChunkX == a_Chunk.m_ChunkX) && (a_Item.m_ChunkZ == a_Chunk.m_ChunkZ);
+		}
+	);
 }
 
 
@@ -244,14 +252,23 @@ void cWorldStorage::Execute(void)
 
 bool cWorldStorage::LoadOneChunk(void)
 {
-	cChunkCoords ToLoad(0, 0);
+	// Dequeue an item, bail out if there's none left:
+	cChunkCoordsWithCallback ToLoad(0, 0, nullptr);
 	bool ShouldLoad = m_LoadQueue.TryDequeueItem(ToLoad);
+	if (!ShouldLoad)
+	{
+		return false;
+	}
 
-	if (ShouldLoad)
+	// Load the chunk:
+	bool res = LoadChunk(ToLoad.m_ChunkX, ToLoad.m_ChunkZ);
+
+	// Call the callback, if specified:
+	if (ToLoad.m_Callback != nullptr)
 	{
-		return LoadChunk(ToLoad.m_ChunkX, ToLoad.m_ChunkZ);
+		ToLoad.m_Callback->Call(ToLoad.m_ChunkX, ToLoad.m_ChunkZ);
 	}
-	return false;
+	return res;
 }
 
 
@@ -260,17 +277,30 @@ bool cWorldStorage::LoadOneChunk(void)
 
 bool cWorldStorage::SaveOneChunk(void)
 {
-	cChunkCoords ToSave(0, 0);
+	// Dequeue one chunk to save:
+	cChunkCoordsWithCallback ToSave(0, 0, nullptr);
 	bool ShouldSave = m_SaveQueue.TryDequeueItem(ToSave);
-	if (ShouldSave && m_World->IsChunkValid(ToSave.m_ChunkX, ToSave.m_ChunkZ))
+	if (!ShouldSave)
+	{
+		return false;
+	}
+	
+	// Save the chunk, if it's valid:
+	if (m_World->IsChunkValid(ToSave.m_ChunkX, ToSave.m_ChunkZ))
 	{
 		m_World->MarkChunkSaving(ToSave.m_ChunkX, ToSave.m_ChunkZ);
-		if (m_SaveSchema->SaveChunk(ToSave))
+		if (m_SaveSchema->SaveChunk(cChunkCoords(ToSave.m_ChunkX, ToSave.m_ChunkZ)))
 		{
 			m_World->MarkChunkSaved(ToSave.m_ChunkX, ToSave.m_ChunkZ);
 		}
 	}
-	return ShouldSave;
+
+	// Call the callback, if specified:
+	if (ToSave.m_Callback != nullptr)
+	{
+		ToSave.m_Callback->Call(ToSave.m_ChunkX, ToSave.m_ChunkZ);
+	}
+	return true;
 }
 
 
diff --git a/src/WorldStorage/WorldStorage.h b/src/WorldStorage/WorldStorage.h
index fc7e9f84c..e9ba2a8e2 100644
--- a/src/WorldStorage/WorldStorage.h
+++ b/src/WorldStorage/WorldStorage.h
@@ -25,7 +25,7 @@
 // fwd:
 class cWorld;
 
-typedef cQueue<cChunkCoords> cChunkCoordsQueue;
+typedef cQueue<cChunkCoordsWithCallback> cChunkCoordsQueue;
 
 
 
@@ -64,8 +64,8 @@ public:
 	cWorldStorage(void);
 	~cWorldStorage();
 	
-	void QueueLoadChunk(int a_ChunkX, int a_ChunkZ);
-	void QueueSaveChunk(int a_ChunkX, int a_ChunkZ);
+	void QueueLoadChunk(int a_ChunkX, int a_ChunkZ, cChunkCoordCallback * a_Callback = nullptr);
+	void QueueSaveChunk(int a_ChunkX, int a_ChunkZ, cChunkCoordCallback * a_Callback = nullptr);
 	
 	void UnqueueLoad(int a_ChunkX, int a_ChunkZ);
 	void UnqueueSave(const cChunkCoords & a_Chunk);