15 files changed, 251 insertions, 330 deletions

diff --git a/src/BlockEntities/BlockEntity.h b/src/BlockEntities/BlockEntity.h
index 7b5b6920f..785ee978a 100644
--- a/src/BlockEntities/BlockEntity.h
+++ b/src/BlockEntities/BlockEntity.h
@@ -85,6 +85,7 @@ public:
 	// tolua_begin
 	
 	// Position, in absolute block coordinates:
+	Vector3i GetPos(void) const { return Vector3i{m_PosX, m_PosY, m_PosZ}; }
 	int GetPosX(void) const { return m_PosX; }
 	int GetPosY(void) const { return m_PosY; }
 	int GetPosZ(void) const { return m_PosZ; }
diff --git a/src/Chunk.cpp b/src/Chunk.cpp
index 9dc453079..b6ec39294 100644
--- a/src/Chunk.cpp
+++ b/src/Chunk.cpp
@@ -2858,22 +2858,6 @@ void cChunk::BroadcastBlockEntity(int a_BlockX, int a_BlockY, int a_BlockZ, cons
 
 
 
-void cChunk::BroadcastChunkData(cChunkDataSerializer & a_Serializer, const cClientHandle * a_Exclude)
-{
-	for (cClientHandleList::iterator itr = m_LoadedByClient.begin(); itr != m_LoadedByClient.end(); ++itr)
-	{
-		if (*itr == a_Exclude)
-		{
-			continue;
-		}
-		(*itr)->SendChunkData(m_PosX, m_PosZ, a_Serializer);
-	}  // for itr - LoadedByClient[]
-}
-
-
-
-
-
 void cChunk::BroadcastCollectEntity(const cEntity & a_Entity, const cPlayer & a_Player, const cClientHandle * a_Exclude)
 {
 	for (cClientHandleList::iterator itr = m_LoadedByClient.begin(); itr != m_LoadedByClient.end(); ++itr)
diff --git a/src/Chunk.h b/src/Chunk.h
index f57769107..fd9ea0b0c 100644
--- a/src/Chunk.h
+++ b/src/Chunk.h
@@ -319,7 +319,6 @@ public:
 	void BroadcastBlockAction        (int a_BlockX, int a_BlockY, int a_BlockZ, char a_Byte1, char a_Byte2, BLOCKTYPE a_BlockType, const cClientHandle * a_Exclude = nullptr);
 	void BroadcastBlockBreakAnimation(UInt32 a_EntityID, int a_BlockX, int a_BlockY, int a_BlockZ, char a_Stage, const cClientHandle * a_Exclude = nullptr);
 	void BroadcastBlockEntity        (int a_BlockX, int a_BlockY, int a_BlockZ, const cClientHandle * a_Exclude = nullptr);
-	void BroadcastChunkData          (cChunkDataSerializer & a_Serializer, const cClientHandle * a_Exclude = nullptr);
 	void BroadcastCollectEntity      (const cEntity & a_Entity, const cPlayer & a_Player, const cClientHandle * a_Exclude = nullptr);
 	void BroadcastDestroyEntity      (const cEntity & a_Entity, const cClientHandle * a_Exclude = nullptr);
 	void BroadcastEntityEffect       (const cEntity & a_Entity, int a_EffectID, int a_Amplifier, short a_Duration, const cClientHandle * a_Exclude = nullptr);
diff --git a/src/ChunkMap.cpp b/src/ChunkMap.cpp
index 2f38e4cd6..4db73971c 100644
--- a/src/ChunkMap.cpp
+++ b/src/ChunkMap.cpp
@@ -409,22 +409,6 @@ void cChunkMap::BroadcastBlockEntity(int a_BlockX, int a_BlockY, int a_BlockZ, c
 
 
 
-void cChunkMap::BroadcastChunkData(int a_ChunkX, int a_ChunkZ, cChunkDataSerializer & a_Serializer, const cClientHandle * a_Exclude)
-{
-	cCSLock Lock(m_CSLayers);
-	cChunkPtr Chunk = GetChunkNoGen(a_ChunkX, a_ChunkZ);
-	if (Chunk == nullptr)
-	{
-		return;
-	}
-	// It's perfectly legal to broadcast packets even to invalid chunks!
-	Chunk->BroadcastChunkData(a_Serializer, a_Exclude);
-}
-
-
-
-
-
 void cChunkMap::BroadcastCollectEntity(const cEntity & a_Entity, const cPlayer & a_Player, const cClientHandle * a_Exclude)
 {
 	cCSLock Lock(m_CSLayers);
diff --git a/src/ChunkMap.h b/src/ChunkMap.h
index 964188bbe..916a3433d 100644
--- a/src/ChunkMap.h
+++ b/src/ChunkMap.h
@@ -73,7 +73,6 @@ public:
 	void BroadcastBlockAction(int a_BlockX, int a_BlockY, int a_BlockZ, char a_Byte1, char a_Byte2, BLOCKTYPE a_BlockType, const cClientHandle * a_Exclude = nullptr);
 	void BroadcastBlockBreakAnimation(UInt32 a_EntityID, int a_BlockX, int a_BlockY, int a_BlockZ, char a_Stage, const cClientHandle * a_Exclude = nullptr);
 	void BroadcastBlockEntity(int a_BlockX, int a_BlockY, int a_BlockZ, const cClientHandle * a_Exclude);
-	void BroadcastChunkData(int a_ChunkX, int a_ChunkZ, cChunkDataSerializer & a_Serializer, const cClientHandle * a_Exclude = nullptr);
 	void BroadcastCollectEntity(const cEntity & a_Entity, const cPlayer & a_Player, const cClientHandle * a_Exclude = nullptr);
 	void BroadcastCollectPickup(const cPickup & a_Pickup, const cPlayer & a_Player, const cClientHandle * a_Exclude = nullptr);
 	void BroadcastDestroyEntity(const cEntity & a_Entity, const cClientHandle * a_Exclude = nullptr);
diff --git a/src/ChunkSender.cpp b/src/ChunkSender.cpp
index 2f18ea75c..de886b497 100644
--- a/src/ChunkSender.cpp
+++ b/src/ChunkSender.cpp
@@ -13,6 +13,7 @@
 #include "BlockEntities/BlockEntity.h"
 #include "Protocol/ChunkDataSerializer.h"
 #include "ClientHandle.h"
+#include "Chunk.h"
 
 
 
@@ -28,26 +29,29 @@ class cNotifyChunkSender :
 {
 	virtual void Call(int a_ChunkX, int a_ChunkZ) override
 	{
-		m_ChunkSender->ChunkReady(a_ChunkX, a_ChunkZ);
+		cChunkSender & ChunkSender = m_ChunkSender;
+		m_World.DoWithChunk(
+			a_ChunkX, a_ChunkZ,
+			[&ChunkSender] (cChunk & a_Chunk) -> bool
+			{
+				ChunkSender.QueueSendChunkTo(a_Chunk.GetPosX(), a_Chunk.GetPosZ(), cChunkSender::E_CHUNK_PRIORITY_MIDHIGH, a_Chunk.GetAllClients());
+				return true;
+			}
+		);
 	}
 
-	cChunkSender * m_ChunkSender;
-public:
-	cNotifyChunkSender(cChunkSender * a_ChunkSender) : m_ChunkSender(a_ChunkSender) {}
-};
-
-
-
+	cChunkSender & m_ChunkSender;
 
+	cWorld & m_World;
+public:
+	cNotifyChunkSender(cChunkSender & a_ChunkSender, cWorld & a_World) : m_ChunkSender(a_ChunkSender), m_World(a_World) {}
 
 
-////////////////////////////////////////////////////////////////////////////////
-// cChunkSender:
+};
 
-cChunkSender::cChunkSender(void) :
+cChunkSender::cChunkSender(cWorld & a_World) :
 	super("ChunkSender"),
-	m_World(nullptr),
-	m_RemoveCount(0)
+	m_World(a_World)
 {
 }
 
@@ -64,10 +68,9 @@ cChunkSender::~cChunkSender()
 
 
 
-bool cChunkSender::Start(cWorld * a_World)
+bool cChunkSender::Start()
 {
 	m_ShouldTerminate = false;
-	m_World = a_World;
 	return super::Start();
 }
 
@@ -86,12 +89,30 @@ void cChunkSender::Stop(void)
 
 
 
-void cChunkSender::ChunkReady(int a_ChunkX, int a_ChunkZ)
+void cChunkSender::QueueSendChunkTo(int a_ChunkX, int a_ChunkZ, eChunkPriority a_Priority, cClientHandle * a_Client)
 {
-	// This is probably never gonna be called twice for the same chunk, and if it is, we don't mind, so we don't check
+	ASSERT(a_Client != nullptr);
 	{
+		cChunkCoords Chunk{a_ChunkX, a_ChunkZ};
 		cCSLock Lock(m_CS);
-		m_ChunksReady.push_back(cChunkCoords(a_ChunkX, a_ChunkZ));
+		auto iter = m_ChunkInfo.find(Chunk);
+		if (iter != m_ChunkInfo.end())
+		{
+			auto & info = iter->second;
+			if (info.m_Priority > a_Priority)
+			{
+				m_SendChunks.push(sChunkQueue{a_Priority, Chunk});
+				info.m_Priority = a_Priority;
+			}
+			info.m_Clients.insert(a_Client);
+		}
+		else
+		{
+			m_SendChunks.push(sChunkQueue{a_Priority, Chunk});
+			auto info = sSendChunk{Chunk, a_Priority};
+			info.m_Clients.insert(a_Client);
+			m_ChunkInfo.emplace(Chunk, info);
+		}
 	}
 	m_evtQueue.Set();
 }
@@ -100,40 +121,29 @@ void cChunkSender::ChunkReady(int a_ChunkX, int a_ChunkZ)
 
 
 
-void cChunkSender::QueueSendChunkTo(int a_ChunkX, int a_ChunkZ, eChunkPriority a_Priority, cClientHandle * a_Client)
+
+void cChunkSender::QueueSendChunkTo(int a_ChunkX, int a_ChunkZ, eChunkPriority a_Priority, std::list<cClientHandle *> a_Clients)
 {
-	ASSERT(a_Client != nullptr);
 	{
-		sSendChunk Chunk(a_ChunkX, a_ChunkZ, a_Client);
-
+		cChunkCoords Chunk{a_ChunkX, a_ChunkZ};
 		cCSLock Lock(m_CS);
-		if (
-			std::find(m_SendChunksLowPriority.begin(), m_SendChunksLowPriority.end(), Chunk) != m_SendChunksLowPriority.end() ||
-			std::find(m_SendChunksMediumPriority.begin(), m_SendChunksMediumPriority.end(), Chunk) != m_SendChunksMediumPriority.end() ||
-			std::find(m_SendChunksHighPriority.begin(), m_SendChunksHighPriority.end(), Chunk) != m_SendChunksHighPriority.end()
-		)
-		{
-			// Already queued, bail out
-			return;
-		}
-
-		switch (a_Priority)
+		auto iter = m_ChunkInfo.find(Chunk);
+		if (iter != m_ChunkInfo.end())
 		{
-			case E_CHUNK_PRIORITY_LOW:
+			auto & info = iter->second;
+			if (info.m_Priority > a_Priority)
 			{
-				m_SendChunksLowPriority.push_back(Chunk);
-				break;
-			}
-			case E_CHUNK_PRIORITY_MEDIUM:
-			{
-				m_SendChunksMediumPriority.push_back(Chunk);
-				break;
-			}
-			case E_CHUNK_PRIORITY_HIGH:
-			{
-				m_SendChunksHighPriority.push_back(Chunk);
-				break;
+				m_SendChunks.push(sChunkQueue{a_Priority, Chunk});
+				info.m_Priority = a_Priority;
 			}
+			info.m_Clients.insert(a_Clients.begin(), a_Clients.end());
+		}
+		else
+		{
+			m_SendChunks.push(sChunkQueue{a_Priority, Chunk});
+			auto info = sSendChunk{Chunk, a_Priority};
+			info.m_Clients.insert(a_Clients.begin(), a_Clients.end());
+			m_ChunkInfo.emplace(Chunk, info);
 		}
 	}
 	m_evtQueue.Set();
@@ -147,37 +157,14 @@ void cChunkSender::RemoveClient(cClientHandle * a_Client)
 {
 	{
 		cCSLock Lock(m_CS);
-		for (sSendChunkList::iterator itr = m_SendChunksLowPriority.begin(); itr != m_SendChunksLowPriority.end();)
+		for (auto && pair : m_ChunkInfo)
 		{
-			if (itr->m_Client == a_Client)
-			{
-				itr = m_SendChunksLowPriority.erase(itr);
-				continue;
-			}
-			++itr;
-		}  // for itr - m_SendChunksLowPriority[]
-		for (sSendChunkList::iterator itr = m_SendChunksMediumPriority.begin(); itr != m_SendChunksMediumPriority.end();)
-		{
-			if (itr->m_Client == a_Client)
-			{
-				itr = m_SendChunksMediumPriority.erase(itr);
-				continue;
-			}
-			++itr;
-		}  // for itr - m_SendChunksMediumPriority[]
-		for (sSendChunkList::iterator itr = m_SendChunksHighPriority.begin(); itr != m_SendChunksHighPriority.end();)
-		{
-			if (itr->m_Client == a_Client)
-			{
-				itr = m_SendChunksHighPriority.erase(itr);
-				continue;
-			}
-			++itr;
-		}  // for itr - m_SendChunksHighPriority[]
-		m_RemoveCount++;
+			auto && clients = pair.second.m_Clients;
+			clients.erase(a_Client);  // nop for sets that do not contain a_Client
+		}
 	}
 	m_evtQueue.Set();
-	m_evtRemoved.Wait();  // Wait for removal confirmation
+	m_evtRemoved.Wait();  // Wait for all remaining instances of a_Client to be processed (Execute() makes a copy of m_ChunkInfo)
 }
 
 
@@ -188,132 +175,91 @@ void cChunkSender::Execute(void)
 {
 	while (!m_ShouldTerminate)
 	{
-		cCSLock Lock(m_CS);
-		while (m_ChunksReady.empty() && m_SendChunksLowPriority.empty() && m_SendChunksMediumPriority.empty() && m_SendChunksHighPriority.empty())
+		m_evtQueue.Wait();
+
 		{
-			int RemoveCount = m_RemoveCount;
-			m_RemoveCount = 0;
-			cCSUnlock Unlock(Lock);
-			for (int i = 0; i < RemoveCount; i++)
-			{
-				m_evtRemoved.Set();  // Notify that the removed clients are safe to be deleted
-			}
-			m_evtQueue.Wait();
-			if (m_ShouldTerminate)
+			cCSLock Lock(m_CS);
+			while (!m_SendChunks.empty())
 			{
-				return;
+				// Take one from the queue:
+				auto Chunk = m_SendChunks.top().m_Chunk;
+				m_SendChunks.pop();
+				auto itr = m_ChunkInfo.find(Chunk);
+				if (itr == m_ChunkInfo.end())
+				{
+					continue;
+				}
+
+				std::unordered_set<cClientHandle *> clients;
+				std::swap(itr->second.m_Clients, clients);
+				m_ChunkInfo.erase(itr);
+
+				cCSUnlock Unlock(Lock);
+				SendChunk(Chunk.m_ChunkX, Chunk.m_ChunkZ, clients);
 			}
-		}  // while (empty)
-
-		if (!m_SendChunksHighPriority.empty())
-		{
-			// Take one from the queue:
-			sSendChunk Chunk(m_SendChunksHighPriority.front());
-			m_SendChunksHighPriority.pop_front();
-			Lock.Unlock();
-
-			SendChunk(Chunk.m_ChunkX, Chunk.m_ChunkZ, Chunk.m_Client);
-		}
-		else if (!m_ChunksReady.empty())
-		{
-			// Take one from the queue:
-			cChunkCoords Coords(m_ChunksReady.front());
-			m_ChunksReady.pop_front();
-			Lock.Unlock();
-			
-			SendChunk(Coords.m_ChunkX, Coords.m_ChunkZ, nullptr);
 		}
-		else if (!m_SendChunksMediumPriority.empty())
-		{
-			// Take one from the queue:
-			sSendChunk Chunk(m_SendChunksMediumPriority.front());
-			m_SendChunksMediumPriority.pop_front();
-			Lock.Unlock();
 
-			SendChunk(Chunk.m_ChunkX, Chunk.m_ChunkZ, Chunk.m_Client);
-		}
-		else
-		{
-			// Take one from the queue:
-			sSendChunk Chunk(m_SendChunksLowPriority.front());
-			m_SendChunksLowPriority.pop_front();
-			Lock.Unlock();
-
-			SendChunk(Chunk.m_ChunkX, Chunk.m_ChunkZ, Chunk.m_Client);
-		}
-		Lock.Lock();
-		int RemoveCount = m_RemoveCount;
-		m_RemoveCount = 0;
-		Lock.Unlock();
-		for (int i = 0; i < RemoveCount; i++)
-		{
-			m_evtRemoved.Set();  // Notify that the removed clients are safe to be deleted
-		}
-	}  // while (!mShouldTerminate)
+		m_evtRemoved.SetAll();  // Notify all waiting threads that all clients are processed and thus safe to destroy
+	}  // while (!m_ShouldTerminate)
 }
 
 
 
 
 
-void cChunkSender::SendChunk(int a_ChunkX, int a_ChunkZ, cClientHandle * a_Client)
+void cChunkSender::SendChunk(int a_ChunkX, int a_ChunkZ, std::unordered_set<cClientHandle *> a_Clients)
 {
-	ASSERT(m_World != nullptr);
-	
 	// Ask the client if it still wants the chunk:
-	if ((a_Client != nullptr) && !a_Client->WantsSendChunk(a_ChunkX, a_ChunkZ))
+	for (auto itr = a_Clients.begin(); itr != a_Clients.end();)
 	{
-		return;
+		if (!(*itr)->WantsSendChunk(a_ChunkX, a_ChunkZ))
+		{
+			itr = a_Clients.erase(itr);
+		}
+		else
+		{
+			itr++;
+		}
 	}
 
 	// If the chunk has no clients, no need to packetize it:
-	if (!m_World->HasChunkAnyClients(a_ChunkX, a_ChunkZ))
+	if (!m_World.HasChunkAnyClients(a_ChunkX, a_ChunkZ))
 	{
 		return;
 	}
 
 	// If the chunk is not valid, do nothing - whoever needs it has queued it for loading / generating
-	if (!m_World->IsChunkValid(a_ChunkX, a_ChunkZ))
+	if (!m_World.IsChunkValid(a_ChunkX, a_ChunkZ))
 	{
 		return;
 	}
 
 	// If the chunk is not lighted, queue it for relighting and get notified when it's ready:
-	if (!m_World->IsChunkLighted(a_ChunkX, a_ChunkZ))
+	if (!m_World.IsChunkLighted(a_ChunkX, a_ChunkZ))
 	{
-		m_World->QueueLightChunk(a_ChunkX, a_ChunkZ, cpp14::make_unique<cNotifyChunkSender>(this));
+		m_World.QueueLightChunk(a_ChunkX, a_ChunkZ, cpp14::make_unique<cNotifyChunkSender>(*this, m_World));
 		return;
 	}
 
 	// Query and prepare chunk data:
-	if (!m_World->GetChunkData(a_ChunkX, a_ChunkZ, *this))
+	if (!m_World.GetChunkData(a_ChunkX, a_ChunkZ, *this))
 	{
 		return;
 	}
 	cChunkDataSerializer Data(m_BlockTypes, m_BlockMetas, m_BlockLight, m_BlockSkyLight, m_BiomeMap);
 
-	// Send:
-	if (a_Client == nullptr)
-	{
-		m_World->BroadcastChunkData(a_ChunkX, a_ChunkZ, Data);
-	}
-	else
+	for (const auto client : a_Clients)
 	{
-		a_Client->SendChunkData(a_ChunkX, a_ChunkZ, Data);
-	}
+		// Send:
+		client->SendChunkData(a_ChunkX, a_ChunkZ, Data);
 
-	// Send block-entity packets:
-	for (sBlockCoords::iterator itr = m_BlockEntities.begin(); itr != m_BlockEntities.end(); ++itr)
-	{
-		if (a_Client == nullptr)
+		// Send block-entity packets:
+		for (const auto & Pos : m_BlockEntities)
 		{
-			m_World->BroadcastBlockEntity(itr->m_BlockX, itr->m_BlockY, itr->m_BlockZ);
-		}
-		else
-		{
-			m_World->SendBlockEntity(itr->m_BlockX, itr->m_BlockY, itr->m_BlockZ, *a_Client);
-		}
-	}  // for itr - m_Packets[]
+			m_World.SendBlockEntity(Pos.x, Pos.y, Pos.z, *client);
+		}  // for itr - m_Packets[]
+
+	}
 	m_BlockEntities.clear();
 
 	// TODO: Send entity spawn packets
@@ -325,7 +271,7 @@ void cChunkSender::SendChunk(int a_ChunkX, int a_ChunkZ, cClientHandle * a_Clien
 
 void cChunkSender::BlockEntity(cBlockEntity * a_Entity)
 {
-	m_BlockEntities.push_back(sBlockCoord(a_Entity->GetPosX(), a_Entity->GetPosY(), a_Entity->GetPosZ()));
+	m_BlockEntities.push_back(a_Entity->GetPos());
 }
 
 
diff --git a/src/ChunkSender.h b/src/ChunkSender.h
index 1376baeb3..fd9275794 100644
--- a/src/ChunkSender.h
+++ b/src/ChunkSender.h
@@ -1,4 +1,4 @@
-
+
 // ChunkSender.h
 
 // Interfaces to the cChunkSender class representing the thread that waits for chunks becoming ready (loaded / generated) and sends them to clients
@@ -29,6 +29,9 @@ Note that it may be called by world's BroadcastToChunk() if the client is still
 #include "ChunkDef.h"
 #include "ChunkDataCallback.h"
 
+#include <unordered_set>
+#include <unordered_map>
+
 
 
 
@@ -53,87 +56,73 @@ class cChunkSender:
 {
 	typedef cIsThread super;
 public:
-	cChunkSender(void);
+	cChunkSender(cWorld & a_World);
 	~cChunkSender();
 
 	enum eChunkPriority
 	{
-		E_CHUNK_PRIORITY_HIGH   = 0,
-		E_CHUNK_PRIORITY_MEDIUM = 1,
-		E_CHUNK_PRIORITY_LOW    = 2,
+		E_CHUNK_PRIORITY_HIGH = 0,
+		E_CHUNK_PRIORITY_MIDHIGH,
+		E_CHUNK_PRIORITY_MEDIUM,
+		E_CHUNK_PRIORITY_LOW,
+		
 	};
 	
-	bool Start(cWorld * a_World);
+	bool Start();
 	
 	void Stop(void);
 	
-	/// Notifies that a chunk has become ready and it should be sent to all its clients
-	void ChunkReady(int a_ChunkX, int a_ChunkZ);
-	
 	/// Queues a chunk to be sent to a specific client
 	void QueueSendChunkTo(int a_ChunkX, int a_ChunkZ, eChunkPriority a_Priority, cClientHandle * a_Client);
+	void QueueSendChunkTo(int a_ChunkX, int a_ChunkZ, eChunkPriority a_Priority, std::list<cClientHandle *> a_Client);
 	
 	/// Removes the a_Client from all waiting chunk send operations
 	void RemoveClient(cClientHandle * a_Client);
 	
 protected:
-
-	/// Used for sending chunks to specific clients
-	struct sSendChunk
+	
+	struct sChunkQueue
 	{
-		int m_ChunkX;
-		int m_ChunkZ;
-		cClientHandle * m_Client;
-		
-		sSendChunk(int a_ChunkX, int a_ChunkZ, cClientHandle * a_Client) :
-			m_ChunkX(a_ChunkX),
-			m_ChunkZ(a_ChunkZ),
-			m_Client(a_Client)
-		{
-		}
-		
-		bool operator ==(const sSendChunk & a_Other)
+		eChunkPriority m_Priority;
+		cChunkCoords m_Chunk;
+
+		bool operator <(const sChunkQueue & a_Other) const
 		{
-			return (
-				(a_Other.m_ChunkX == m_ChunkX) &&
-				(a_Other.m_ChunkZ == m_ChunkZ) &&
-				(a_Other.m_Client == m_Client)
-			);
+			/* The Standard Priority Queue sorts from biggest to smallest
+			return true here means you are smaller than the other object, and you get pushed down.
+
+			The priorities go from HIGH (0) to LOW (2), so a smaller priority should mean further up the list
+			therefore, return true (affirm we're "smaller", and get pushed down) only if our priority is bigger than theirs (they're more urgent)
+			*/
+			return this->m_Priority > a_Other.m_Priority;
 		}
-	} ;
-	typedef std::list<sSendChunk> sSendChunkList;
+	};
 
-	struct sBlockCoord
+	/// Used for sending chunks to specific clients
+	struct sSendChunk
 	{
-		int m_BlockX;
-		int m_BlockY;
-		int m_BlockZ;
-		
-		sBlockCoord(int a_BlockX, int a_BlockY, int a_BlockZ) :
-			m_BlockX(a_BlockX),
-			m_BlockY(a_BlockY),
-			m_BlockZ(a_BlockZ)
+		cChunkCoords m_Chunk;
+		std::unordered_set<cClientHandle *> m_Clients;
+		eChunkPriority m_Priority;
+		sSendChunk(cChunkCoords a_Chunk, eChunkPriority a_Priority) :
+			m_Chunk(a_Chunk),
+			m_Priority(a_Priority)
 		{
 		}
-	} ;
-
-	typedef std::vector<sBlockCoord> sBlockCoords;
+	};
 	
-	cWorld * m_World;
+	cWorld & m_World;
 	
 	cCriticalSection  m_CS;
-	cChunkCoordsList  m_ChunksReady;
-	sSendChunkList    m_SendChunksLowPriority;
-	sSendChunkList    m_SendChunksMediumPriority;
-	sSendChunkList    m_SendChunksHighPriority;
-	cEvent            m_evtQueue;  // Set when anything is added to m_ChunksReady
-	cEvent            m_evtRemoved;  // Set when removed clients are safe to be deleted
-	int               m_RemoveCount;  // Number of threads waiting for a client removal (m_evtRemoved needs to be set this many times)
-	
+	std::priority_queue<sChunkQueue> m_SendChunks;
+	std::unordered_map<cChunkCoords, sSendChunk, cChunkCoordsHash> m_ChunkInfo;
+	cEvent m_evtQueue;  // Set when anything is added to m_ChunksReady
+	cEvent m_evtRemoved;  // Set when removed clients are safe to be deleted
+
 	// Data about the chunk that is being sent:
 	// NOTE that m_BlockData[] is inherited from the cChunkDataCollector
 	unsigned char m_BiomeMap[cChunkDef::Width * cChunkDef::Width];
-	sBlockCoords  m_BlockEntities;  // Coords of the block entities to send
+	std::vector<Vector3i> m_BlockEntities;  // Coords of the block entities to send
 	// TODO: sEntityIDs    m_Entities;       // Entity-IDs of the entities to send
 	
 	// cIsThread override:
@@ -146,9 +135,8 @@ protected:
 	virtual void BlockEntity  (cBlockEntity * a_Entity) override;
 
 	/// Sends the specified chunk to a_Client, or to all chunk clients if a_Client == nullptr
-	void SendChunk(int a_ChunkX, int a_ChunkZ, cClientHandle * a_Client);
+	void SendChunk(int a_ChunkX, int a_ChunkZ, std::unordered_set<cClientHandle *> a_Clients);
 } ;
 
 
 
-
diff --git a/src/ClientHandle.cpp b/src/ClientHandle.cpp
index d89f7ab77..9ed89e0a3 100644
--- a/src/ClientHandle.cpp
+++ b/src/ClientHandle.cpp
@@ -456,7 +456,7 @@ bool cClientHandle::StreamNextChunk(void)
 
 				// If the chunk already loading / loaded -> skip
 				if (
-					(std::find(m_ChunksToSend.begin(), m_ChunksToSend.end(), Coords) != m_ChunksToSend.end()) ||
+					(m_ChunksToSend.find(Coords) != m_ChunksToSend.end()) ||
 					(std::find(m_LoadedChunks.begin(), m_LoadedChunks.end(), Coords) != m_LoadedChunks.end())
 				)
 				{
@@ -494,7 +494,7 @@ bool cClientHandle::StreamNextChunk(void)
 
 			// If the chunk already loading / loaded -> skip
 			if (
-				(std::find(m_ChunksToSend.begin(), m_ChunksToSend.end(), Coords) != m_ChunksToSend.end()) ||
+				(m_ChunksToSend.find(Coords) != m_ChunksToSend.end()) ||
 				(std::find(m_LoadedChunks.begin(), m_LoadedChunks.end(), Coords) != m_LoadedChunks.end())
 			)
 			{
@@ -541,7 +541,7 @@ void cClientHandle::UnloadOutOfRangeChunks(void)
 			}
 		}
 
-		for (cChunkCoordsList::iterator itr = m_ChunksToSend.begin(); itr != m_ChunksToSend.end();)
+		for (auto itr = m_ChunksToSend.begin(); itr != m_ChunksToSend.end();)
 		{
 			int DiffX = Diff((*itr).m_ChunkX, ChunkPosX);
 			int DiffZ = Diff((*itr).m_ChunkZ, ChunkPosZ);
@@ -583,7 +583,7 @@ void cClientHandle::StreamChunk(int a_ChunkX, int a_ChunkZ, cChunkSender::eChunk
 		{
 			cCSLock Lock(m_CSChunkLists);
 			m_LoadedChunks.push_back(cChunkCoords(a_ChunkX, a_ChunkZ));
-			m_ChunksToSend.push_back(cChunkCoords(a_ChunkX, a_ChunkZ));
+			m_ChunksToSend.emplace(a_ChunkX, a_ChunkZ);
 		}
 		World->SendChunkTo(a_ChunkX, a_ChunkZ, a_Priority, this);
 	}
@@ -2179,15 +2179,12 @@ void cClientHandle::SendChunkData(int a_ChunkX, int a_ChunkZ, cChunkDataSerializ
 	bool Found = false;
 	{
 		cCSLock Lock(m_CSChunkLists);
-		for (cChunkCoordsList::iterator itr = m_ChunksToSend.begin(); itr != m_ChunksToSend.end(); ++itr)
+		auto itr = m_ChunksToSend.find(cChunkCoords{a_ChunkX, a_ChunkZ});
+		if (itr != m_ChunksToSend.end())
 		{
-			if ((itr->m_ChunkX == a_ChunkX) && (itr->m_ChunkZ == a_ChunkZ))
-			{
-				m_ChunksToSend.erase(itr);
-				Found = true;
-				break;
-			}
-		}  // for itr - m_ChunksToSend[]
+			m_ChunksToSend.erase(itr);
+			Found = true;
+		}
 	}
 	if (!Found)
 	{
@@ -2950,7 +2947,7 @@ bool cClientHandle::WantsSendChunk(int a_ChunkX, int a_ChunkZ)
 	}
 	
 	cCSLock Lock(m_CSChunkLists);
-	return (std::find(m_ChunksToSend.begin(), m_ChunksToSend.end(), cChunkCoords(a_ChunkX, a_ChunkZ)) != m_ChunksToSend.end());
+	return m_ChunksToSend.find(cChunkCoords(a_ChunkX, a_ChunkZ)) != m_ChunksToSend.end();
 }
 
 
@@ -2966,9 +2963,9 @@ void cClientHandle::AddWantedChunk(int a_ChunkX, int a_ChunkZ)
 	
 	LOGD("Adding chunk [%d, %d] to wanted chunks for client %p", a_ChunkX, a_ChunkZ, this);
 	cCSLock Lock(m_CSChunkLists);
-	if (std::find(m_ChunksToSend.begin(), m_ChunksToSend.end(), cChunkCoords(a_ChunkX, a_ChunkZ)) == m_ChunksToSend.end())
+	if (m_ChunksToSend.find(cChunkCoords(a_ChunkX, a_ChunkZ)) == m_ChunksToSend.end())
 	{
-		m_ChunksToSend.push_back(cChunkCoords(a_ChunkX, a_ChunkZ));
+		m_ChunksToSend.emplace(a_ChunkX, a_ChunkZ);
 	}
 }
 
diff --git a/src/ClientHandle.h b/src/ClientHandle.h
index dc448fc11..302de5a77 100644
--- a/src/ClientHandle.h
+++ b/src/ClientHandle.h
@@ -377,10 +377,10 @@ private:
 	AString m_Password;
 	Json::Value m_Properties;
 
-	cCriticalSection m_CSChunkLists;
-	cChunkCoordsList m_LoadedChunks;  // Chunks that the player belongs to
-	cChunkCoordsList m_ChunksToSend;  // Chunks that need to be sent to the player (queued because they weren't generated yet or there's not enough time to send them)
-	cChunkCoordsList m_SentChunks;    // Chunks that are currently sent to the client
+	cCriticalSection                                   m_CSChunkLists;
+	cChunkCoordsList                                   m_LoadedChunks;  // Chunks that the player belongs to
+	std::unordered_set<cChunkCoords, cChunkCoordsHash> m_ChunksToSend;  // Chunks that need to be sent to the player (queued because they weren't generated yet or there's not enough time to send them)
+	cChunkCoordsList                                   m_SentChunks;    // Chunks that are currently sent to the client
 
 	cProtocol * m_Protocol;
 
diff --git a/src/OSSupport/Event.cpp b/src/OSSupport/Event.cpp
index 38144ead3..4c2adea3c 100644
--- a/src/OSSupport/Event.cpp
+++ b/src/OSSupport/Event.cpp
@@ -13,7 +13,7 @@
 
 
 cEvent::cEvent(void) :
-	m_ShouldWait(true)
+	m_ShouldContinue(false)
 {
 }
 
@@ -23,12 +23,11 @@ cEvent::cEvent(void) :
 
 void cEvent::Wait(void)
 {
-	std::unique_lock<std::mutex> Lock(m_Mutex);
-	while (m_ShouldWait)
 	{
-		m_CondVar.wait(Lock);
+		std::unique_lock<std::mutex> Lock(m_Mutex);
+		m_CondVar.wait(Lock, [this](){ return m_ShouldContinue.load(); });
 	}
-	m_ShouldWait = true;
+	m_ShouldContinue = false;
 }
 
 
@@ -38,33 +37,13 @@ void cEvent::Wait(void)
 bool cEvent::Wait(unsigned a_TimeoutMSec)
 {
 	auto dst = std::chrono::system_clock::now() + std::chrono::milliseconds(a_TimeoutMSec);
-	std::unique_lock<std::mutex> Lock(m_Mutex);  // We assume that this lock is acquired without much delay - we are the only user of the mutex
-	while (m_ShouldWait && (std::chrono::system_clock::now() <= dst))
+	bool Result;
 	{
-		switch (m_CondVar.wait_until(Lock, dst))
-		{
-			case std::cv_status::no_timeout:
-			{
-				// The wait was successful, check for spurious wakeup:
-				if (!m_ShouldWait)
-				{
-					m_ShouldWait = true;
-					return true;
-				}
-				// This was a spurious wakeup, wait again:
-				continue;
-			}
-			
-			case std::cv_status::timeout:
-			{
-				// The wait timed out, return failure:
-				return false;
-			}
-		}  // switch (wait_until())
-	}  // while (m_ShouldWait && not timeout)
-
-	// The wait timed out in the while condition:
-	return false;
+		std::unique_lock<std::mutex> Lock(m_Mutex);  // We assume that this lock is acquired without much delay - we are the only user of the mutex
+		Result = m_CondVar.wait_until(Lock, dst, [this](){ return m_ShouldContinue.load(); });
+	}
+	m_ShouldContinue = false;
+	return Result;
 }
 
 
@@ -73,13 +52,20 @@ bool cEvent::Wait(unsigned a_TimeoutMSec)
 
 void cEvent::Set(void)
 {
-	{
-		std::unique_lock<std::mutex> Lock(m_Mutex);
-		m_ShouldWait = false;
-	}
+	m_ShouldContinue = true;
 	m_CondVar.notify_one();
 }
 
 
 
 
+void cEvent::SetAll(void)
+{
+	m_ShouldContinue = true;
+	m_CondVar.notify_all();
+}
+
+
+
+
+
diff --git a/src/OSSupport/Event.h b/src/OSSupport/Event.h
index 572388a3f..2c58ba485 100644
--- a/src/OSSupport/Event.h
+++ b/src/OSSupport/Event.h
@@ -12,6 +12,7 @@
 
 #include <mutex>
 #include <condition_variable>
+#include <atomic>
 
 
 
@@ -28,7 +29,11 @@ public:
 
 	/** Sets the event - releases one thread that has been waiting in Wait().
 	If there was no thread waiting, the next call to Wait() will not block. */
-	void Set (void);
+	void Set(void);
+
+	/** Sets the event - releases all threads that have been waiting in Wait().
+	If there was no thread waiting, the next call to Wait() will not block. */
+	void SetAll(void);
 
 	/** Waits for the event until either it is signalled, or the (relative) timeout is passed.
 	Returns true if the event was signalled, false if the timeout was hit or there was an error. */
@@ -37,9 +42,9 @@ public:
 private:
 
 	/** Used for checking for spurious wakeups. */
-	bool m_ShouldWait;
+	std::atomic<bool> m_ShouldContinue;
 
-	/** Mutex protecting m_ShouldWait from multithreaded access. */
+	/** Mutex protecting m_ShouldContinue from multithreaded access. */
 	std::mutex m_Mutex;
 
 	/** The condition variable used as the Event. */
diff --git a/src/OSSupport/IsThread.cpp b/src/OSSupport/IsThread.cpp
index 55e96b622..e295d5f25 100644
--- a/src/OSSupport/IsThread.cpp
+++ b/src/OSSupport/IsThread.cpp
@@ -134,9 +134,9 @@ bool cIsThread::Wait(void)
 			m_Thread.join();
 			return true;
 		}
-		catch (std::system_error & a_Exception)
+		catch (const std::system_error & a_Exception)
 		{
-			LOGERROR("cIsThread::Wait error %i: could not join thread %s; %s", a_Exception.code().value(), m_ThreadName.c_str(), a_Exception.code().message().c_str());
+			LOGERROR("%s error %i: could not join thread %s; %s", __FUNCTION__, a_Exception.code().value(), m_ThreadName.c_str(), a_Exception.code().message().c_str());
 			return false;
 		}
 	}
diff --git a/src/OSSupport/IsThread.h b/src/OSSupport/IsThread.h
index f642c8724..fa6813cd7 100644
--- a/src/OSSupport/IsThread.h
+++ b/src/OSSupport/IsThread.h
@@ -32,10 +32,6 @@ protected:
 	/** The overriden Execute() method should check this value periodically and terminate if this is true. */
 	volatile bool m_ShouldTerminate;
 
-private:
-	/** Wrapper for Execute() that waits for the initialization event, to prevent race conditions in thread initialization. */
-	void DoExecute(void);
-
 public:
 	cIsThread(const AString & a_ThreadName);
 	virtual ~cIsThread();
@@ -51,14 +47,21 @@ public:
 
 	/** Returns true if the thread calling this function is the thread contained within this object. */
 	bool IsCurrentThread(void) const { return std::this_thread::get_id() == m_Thread.get_id(); }
+	
+private:
 
-protected:
+	/** The name of the thread, used to aid debugging in IDEs which support named threads */
 	AString m_ThreadName;
+
+	/** The thread object which holds the created thread for later manipulation */
 	std::thread m_Thread;
 
 	/** The event that is used to wait with the thread's execution until the thread object is fully initialized.
-	This prevents the IsCurrentThread() call to fail because of a race-condition. */
+	This prevents the IsCurrentThread() call to fail because of a race-condition where the thread starts before m_Thread has been fully assigned. */
 	cEvent m_evtStart;
+
+	/** Wrapper for Execute() that waits for the initialization event, to prevent race conditions in thread initialization. */
+	void DoExecute(void);
 } ;
 
 
diff --git a/src/World.cpp b/src/World.cpp
index 71f4aeae3..a1e392fd1 100644
--- a/src/World.cpp
+++ b/src/World.cpp
@@ -186,6 +186,7 @@ cWorld::cWorld(const AString & a_WorldName, eDimension a_Dimension, const AStrin
 	m_Scoreboard(this),
 	m_MapManager(this),
 	m_GeneratorCallbacks(*this),
+	m_ChunkSender(*this),
 	m_TickThread(*this)
 {
 	LOGD("cWorld::cWorld(\"%s\")", a_WorldName.c_str());
@@ -513,7 +514,7 @@ void cWorld::Start(void)
 	m_Lighting.Start(this);
 	m_Storage.Start(this, m_StorageSchema, m_StorageCompressionFactor);
 	m_Generator.Start(m_GeneratorCallbacks, m_GeneratorCallbacks, IniFile);
-	m_ChunkSender.Start(this);
+	m_ChunkSender.Start();
 	m_TickThread.Start();
 
 	// Init of the spawn monster time (as they are supposed to have different spawn rate)
@@ -1330,6 +1331,30 @@ bool cWorld::DoWithChunk(int a_ChunkX, int a_ChunkZ, cChunkCallback & a_Callback
 
 
 
+bool cWorld::DoWithChunk(int a_ChunkX, int a_ChunkZ, std::function<bool(cChunk &)>  a_Callback)
+{
+	struct cCallBackWrapper : cChunkCallback
+	{
+		cCallBackWrapper(std::function<bool(cChunk &)> a_InnerCallback) :
+			m_Callback(a_InnerCallback)
+		{
+		}
+		
+		virtual bool Item(cChunk * a_Chunk)
+		{
+			return m_Callback(*a_Chunk);
+		}
+
+	private:
+		std::function<bool(cChunk &)> m_Callback;
+	} callback(a_Callback);
+	return m_ChunkMap->DoWithChunk(a_ChunkX, a_ChunkZ, callback);
+}
+
+
+
+
+
 bool cWorld::DoWithChunkAt(Vector3i a_BlockPos, std::function<bool(cChunk &)>  a_Callback)
 {
 	return m_ChunkMap->DoWithChunkAt(a_BlockPos, a_Callback);
@@ -2005,15 +2030,6 @@ void cWorld::BroadcastChat(const cCompositeChat & a_Message, const cClientHandle
 
 
 
-void cWorld::BroadcastChunkData(int a_ChunkX, int a_ChunkZ, cChunkDataSerializer & a_Serializer, const cClientHandle * a_Exclude)
-{
-	m_ChunkMap->BroadcastChunkData(a_ChunkX, a_ChunkZ, a_Serializer, a_Exclude);
-}
-
-
-
-
-
 void cWorld::BroadcastCollectEntity(const cEntity & a_Entity, const cPlayer & a_Player, const cClientHandle * a_Exclude)
 {
 	m_ChunkMap->BroadcastCollectEntity(a_Entity, a_Player, a_Exclude);
@@ -2465,10 +2481,23 @@ void cWorld::SetChunkData(cSetChunkData & a_SetChunkData)
 	// If a client is requesting this chunk, send it to them:
 	int ChunkX = a_SetChunkData.GetChunkX();
 	int ChunkZ = a_SetChunkData.GetChunkZ();
-	if (m_ChunkMap->HasChunkAnyClients(ChunkX, ChunkZ))
-	{
-		m_ChunkSender.ChunkReady(ChunkX, ChunkZ);
-	}
+	cChunkSender & ChunkSender = m_ChunkSender;
+	DoWithChunk(
+		ChunkX, ChunkZ,
+		[&ChunkSender] (cChunk & a_Chunk) -> bool
+		{
+			if (a_Chunk.HasAnyClients())
+			{
+				ChunkSender.QueueSendChunkTo(
+					a_Chunk.GetPosX(),
+					a_Chunk.GetPosZ(),
+					cChunkSender::E_CHUNK_PRIORITY_MEDIUM,
+					a_Chunk.GetAllClients()
+				);
+			}
+			return true;
+		}
+	);
 
 	// Save the chunk right after generating, so that we don't have to generate it again on next run
 	if (a_SetChunkData.ShouldMarkDirty())
diff --git a/src/World.h b/src/World.h
index 99570369b..aeab7bfa5 100644
--- a/src/World.h
+++ b/src/World.h
@@ -250,7 +250,6 @@ public:
 	void BroadcastChat       (const cCompositeChat & a_Message, const cClientHandle * a_Exclude = nullptr);
 	// tolua_end
 
-	void BroadcastChunkData                  (int a_ChunkX, int a_ChunkZ, cChunkDataSerializer & a_Serializer, const cClientHandle * a_Exclude = nullptr);
 	void BroadcastCollectEntity              (const cEntity & a_Pickup, const cPlayer & a_Player, const cClientHandle * a_Exclude = nullptr);
 	void BroadcastDestroyEntity              (const cEntity & a_Entity, const cClientHandle * a_Exclude = nullptr);
 	void BroadcastEntityEffect               (const cEntity & a_Entity, int a_EffectID, int a_Amplifier, short a_Duration, const cClientHandle * a_Exclude = nullptr);
@@ -628,6 +627,7 @@ public:
 	
 	/** Calls the callback for the chunk specified, with ChunkMapCS locked; returns false if the chunk doesn't exist, otherwise returns the same value as the callback */
 	bool DoWithChunk(int a_ChunkX, int a_ChunkZ, cChunkCallback & a_Callback);
+	bool DoWithChunk(int a_ChunkX, int a_ChunkZ, std::function<bool(cChunk &)> a_Callback);
 
 	/** Calls the callback for the chunk at the block position specified, with ChunkMapCS locked; returns false if the chunk doesn't exist, otherwise returns the same value as the callback **/
 	bool DoWithChunkAt(Vector3i a_BlockPos, std::function<bool(cChunk &)> a_Callback);