Codechange: use std::deque of std::unique_ptr to queue packets

src/network/core/packet.cpp

@@ -28,7 +28,7 @@
  *                          loose some the data of the packet, so there you pass the maximum
  *                          size for the packet you expect from the network.
  */
-Packet::Packet(NetworkSocketHandler *cs, size_t limit, size_t initial_read_size) : next(nullptr), pos(0), limit(limit)
+Packet::Packet(NetworkSocketHandler *cs, size_t limit, size_t initial_read_size) : pos(0), limit(limit)
 {
 	assert(cs != nullptr);
 
@@ -44,45 +44,20 @@ Packet::Packet(NetworkSocketHandler *cs, size_t limit, size_t initial_read_size)
  *              the limit as it might break things if the other side is not expecting
  *              much larger packets than what they support.
  */
-Packet::Packet(PacketType type, size_t limit) : next(nullptr), pos(0), limit(limit), cs(nullptr)
+Packet::Packet(PacketType type, size_t limit) : pos(0), limit(limit), cs(nullptr)
 {
 	/* Allocate space for the the size so we can write that in just before sending the packet. */
 	this->Send_uint16(0);
 	this->Send_uint8(type);
 }
 
-/**
- * Add the given Packet to the end of the queue of packets.
- * @param queue  The pointer to the begin of the queue.
- * @param packet The packet to append to the queue.
- */
-/* static */ void Packet::AddToQueue(Packet **queue, Packet *packet)
-{
-	while (*queue != nullptr) queue = &(*queue)->next;
-	*queue = packet;
-}
-
-/**
- * Pop the packet from the begin of the queue and set the
- * begin of the queue to the second element in the queue.
- * @param queue  The pointer to the begin of the queue.
- * @return The Packet that used to be a the begin of the queue.
- */
-/* static */ Packet *Packet::PopFromQueue(Packet **queue)
-{
-	Packet *p = *queue;
-	*queue = p->next;
-	p->next = nullptr;
-	return p;
-}
-
 
 /**
  * Writes the packet size from the raw packet from packet->size
  */
 void Packet::PrepareToSend()
 {
-	assert(this->cs == nullptr && this->next == nullptr);
+	assert(this->cs == nullptr);
 
 	this->buffer[0] = GB(this->Size(), 0, 8);
 	this->buffer[1] = GB(this->Size(), 8, 8);
@@ -268,7 +243,7 @@ size_t Packet::Size() const
  */
 bool Packet::ParsePacketSize()
 {
-	assert(this->cs != nullptr && this->next == nullptr);
+	assert(this->cs != nullptr);
 	size_t size = (size_t)this->buffer[0];
 	size       += (size_t)this->buffer[1] << 8;
 

src/network/core/packet.h

@@ -41,8 +41,6 @@ typedef uint8_t  PacketType; ///< Identifier for the packet
  */
 struct Packet {
 private:
-	/** The next packet. Used for queueing packets before sending. */
-	Packet *next;
 	/** The current read/write position in the packet */
 	PacketSize pos;
 	/** The buffer of this packet. */
@@ -57,9 +55,6 @@ public:
 	Packet(NetworkSocketHandler *cs, size_t limit, size_t initial_read_size = sizeof(PacketSize));
 	Packet(PacketType type, size_t limit = COMPAT_MTU);
 
-	static void AddToQueue(Packet **queue, Packet *packet);
-	static Packet *PopFromQueue(Packet **queue);
-
 	/* Sending/writing of packets */
 	void PrepareToSend();
 

src/network/core/tcp.cpp

@@ -22,28 +22,15 @@
  */
 NetworkTCPSocketHandler::NetworkTCPSocketHandler(SOCKET s) :
 		NetworkSocketHandler(),
-		packet_queue(nullptr), packet_recv(nullptr),
 		sock(s), writable(false)
 {
 }
 
 NetworkTCPSocketHandler::~NetworkTCPSocketHandler()
 {
-	this->EmptyPacketQueue();
 	this->CloseSocket();
 }
 
-/**
- * Free all pending and partially received packets.
- */
-void NetworkTCPSocketHandler::EmptyPacketQueue()
-{
-	while (this->packet_queue != nullptr) {
-		delete Packet::PopFromQueue(&this->packet_queue);
-	}
-	this->packet_recv = nullptr;
-}
-
 /**
  * Close the actual socket of the connection.
  * Please make sure CloseConnection is called before CloseSocket, as
@@ -66,7 +53,8 @@ NetworkRecvStatus NetworkTCPSocketHandler::CloseConnection([[maybe_unused]] bool
 	this->MarkClosed();
 	this->writable = false;
 
-	this->EmptyPacketQueue();
+	this->packet_queue.clear();
+	this->packet_recv = nullptr;
 
 	return NETWORK_RECV_STATUS_OKAY;
 }
@@ -82,7 +70,7 @@ void NetworkTCPSocketHandler::SendPacket(Packet *packet)
 	assert(packet != nullptr);
 
 	packet->PrepareToSend();
-	Packet::AddToQueue(&this->packet_queue, packet);
+	this->packet_queue.push_back(std::unique_ptr<Packet>(packet));
 }
 
 /**
@@ -97,15 +85,13 @@ void NetworkTCPSocketHandler::SendPacket(Packet *packet)
  */
 SendPacketsState NetworkTCPSocketHandler::SendPackets(bool closing_down)
 {
-	ssize_t res;
-	Packet *p;
-
 	/* We can not write to this socket!! */
 	if (!this->writable) return SPS_NONE_SENT;
 	if (!this->IsConnected()) return SPS_CLOSED;
 
-	while ((p = this->packet_queue) != nullptr) {
-		res = p->TransferOut<int>(send, this->sock, 0);
+	while (!this->packet_queue.empty()) {
+		Packet *p = this->packet_queue.front().get();
+		ssize_t res = p->TransferOut<int>(send, this->sock, 0);
 		if (res == -1) {
 			NetworkError err = NetworkError::GetLast();
 			if (!err.WouldBlock()) {
@@ -127,7 +113,7 @@ SendPacketsState NetworkTCPSocketHandler::SendPackets(bool closing_down)
 		/* Is this packet sent? */
 		if (p->RemainingBytesToTransfer() == 0) {
 			/* Go to the next packet */
-			delete Packet::PopFromQueue(&this->packet_queue);
+			this->packet_queue.pop_front();
 		} else {
 			return SPS_PARTLY_SENT;
 		}

src/network/core/tcp.h

@@ -30,7 +30,7 @@ enum SendPacketsState {
 /** Base socket handler for all TCP sockets */
 class NetworkTCPSocketHandler : public NetworkSocketHandler {
 private:
-	Packet *packet_queue;     ///< Packets that are awaiting delivery
+	std::deque<std::unique_ptr<Packet>> packet_queue; ///< Packets that are awaiting delivery. Cannot be std::queue as that does not have a clear() function.
 	std::unique_ptr<Packet> packet_recv; ///< Partially received packet
 
 	void EmptyPacketQueue();
@@ -58,7 +58,7 @@ public:
 	 * Whether there is something pending in the send queue.
 	 * @return true when something is pending in the send queue.
 	 */
-	bool HasSendQueue() { return this->packet_queue != nullptr; }
+	bool HasSendQueue() { return !this->packet_queue.empty(); }
 
 	NetworkTCPSocketHandler(SOCKET s = INVALID_SOCKET);
 	~NetworkTCPSocketHandler();

src/network/network_server.cpp

@@ -61,9 +61,9 @@ template SocketList TCPListenHandler<ServerNetworkGameSocketHandler, PACKET_SERV
 /** Writing a savegame directly to a number of packets. */
 struct PacketWriter : SaveFilter {
 	ServerNetworkGameSocketHandler *cs; ///< Socket we are associated with.
-	Packet *current;                    ///< The packet we're currently writing to.
+	std::unique_ptr<Packet> current; ///< The packet we're currently writing to.
 	size_t total_size;                  ///< Total size of the compressed savegame.
-	Packet *packets;                    ///< Packet queue of the savegame; send these "slowly" to the client.
+	std::deque<std::unique_ptr<Packet>> packets; ///< Packet queue of the savegame; send these "slowly" to the client. Cannot be a std::queue as we want to push the map size packet in front of the data packets.
 	std::mutex mutex;                   ///< Mutex for making threaded saving safe.
 	std::condition_variable exit_sig;   ///< Signal for threaded destruction of this packet writer.
 
@@ -71,7 +71,7 @@ struct PacketWriter : SaveFilter {
 	 * Create the packet writer.
 	 * @param cs The socket handler we're making the packets for.
 	 */
-	PacketWriter(ServerNetworkGameSocketHandler *cs) : SaveFilter(nullptr), cs(cs), current(nullptr), total_size(0), packets(nullptr)
+	PacketWriter(ServerNetworkGameSocketHandler *cs) : SaveFilter(nullptr), cs(cs), total_size(0)
 	{
 	}
 
@@ -84,11 +84,9 @@ struct PacketWriter : SaveFilter {
 
 		/* This must all wait until the Destroy function is called. */
 
-		while (this->packets != nullptr) {
-			delete Packet::PopFromQueue(&this->packets);
-		}
-
-		delete this->current;
+		Debug(net, 0, "Destruct!");
+		this->packets.clear();
+		this->current = nullptr;
 	}
 
 	/**
@@ -125,14 +123,14 @@ struct PacketWriter : SaveFilter {
 	bool TransferToNetworkQueue(ServerNetworkGameSocketHandler *socket)
 	{
 		/* Unsafe check for the queue being empty or not. */
-		if (this->packets == nullptr) return false;
+		if (this->packets.empty()) return false;
 
 		std::lock_guard<std::mutex> lock(this->mutex);
 
-		while (this->packets != nullptr) {
-			Packet *p = Packet::PopFromQueue(&this->packets);
-			bool last_packet = p->GetPacketType() == PACKET_SERVER_MAP_DONE;
-			socket->SendPacket(p);
+		while (!this->packets.empty()) {
+			bool last_packet = this->packets.front()->GetPacketType() == PACKET_SERVER_MAP_DONE;
+			socket->SendPacket(this->packets.front().release());
+			this->packets.pop_front();
 
 			if (last_packet) return true;
 		}
@@ -140,32 +138,12 @@ struct PacketWriter : SaveFilter {
 		return false;
 	}
 
-	/** Append the current packet to the queue. */
-	void AppendQueue()
-	{
-		if (this->current == nullptr) return;
-
-		Packet::AddToQueue(&this->packets, this->current);
-		this->current = nullptr;
-	}
-
-	/** Prepend the current packet to the queue. */
-	void PrependQueue()
-	{
-		if (this->current == nullptr) return;
-
-		/* Reversed from AppendQueue so the queue gets added to the current one. */
-		Packet::AddToQueue(&this->current, this->packets);
-		this->packets = this->current;
-		this->current = nullptr;
-	}
-
 	void Write(byte *buf, size_t size) override
 	{
 		/* We want to abort the saving when the socket is closed. */
 		if (this->cs == nullptr) SlError(STR_NETWORK_ERROR_LOSTCONNECTION);
 
-		if (this->current == nullptr) this->current = new Packet(PACKET_SERVER_MAP_DATA, TCP_MTU);
+		if (this->current == nullptr) this->current = std::make_unique<Packet>(PACKET_SERVER_MAP_DATA, TCP_MTU);
 
 		std::lock_guard<std::mutex> lock(this->mutex);
 
@@ -175,8 +153,8 @@ struct PacketWriter : SaveFilter {
 			buf += written;
 
 			if (!this->current->CanWriteToPacket(1)) {
-				this->AppendQueue();
-				if (buf != bufe) this->current = new Packet(PACKET_SERVER_MAP_DATA, TCP_MTU);
+				this->packets.push_back(std::move(this->current));
+				if (buf != bufe) this->current = std::make_unique<Packet>(PACKET_SERVER_MAP_DATA, TCP_MTU);
 			}
 		}
 
@@ -191,16 +169,15 @@ struct PacketWriter : SaveFilter {
 		std::lock_guard<std::mutex> lock(this->mutex);
 
 		/* Make sure the last packet is flushed. */
-		this->AppendQueue();
+		if (this->current != nullptr) this->packets.push_back(std::move(this->current));
 
 		/* Add a packet stating that this is the end to the queue. */
-		this->current = new Packet(PACKET_SERVER_MAP_DONE);
-		this->AppendQueue();
+		this->packets.push_back(std::make_unique<Packet>(PACKET_SERVER_MAP_DONE));
 
 		/* Fast-track the size to the client. */
-		this->current = new Packet(PACKET_SERVER_MAP_SIZE);
-		this->current->Send_uint32((uint32_t)this->total_size);
-		this->PrependQueue();
+		auto p = std::make_unique<Packet>(PACKET_SERVER_MAP_SIZE);
+		p->Send_uint32((uint32_t)this->total_size);
+		this->packets.push_front(std::move(p));
 	}
 };