Server: Calculate maximal total block sends dynamically (minetest#6393)

The block sends per client is 1/2 when reaching the maximal player count.

builtin/settingtypes.txt

@@ -865,11 +865,10 @@ ipv6_server (IPv6 server) bool false
 [**Advanced]
 
 #    Maximum number of blocks that are simultaneously sent per client.
+#    The maximum total count is calculated dynamically:
+#    max_total = ceil((#clients + max_users) * per_client / 4)
 max_simultaneous_block_sends_per_client (Maximum simultaneous block sends per client) int 10
 
-#   Maximum number of blocks that are simultaneously sent in total.
-max_simultaneous_block_sends_server_total (Maximum simultaneous block sends total) int 40
-
 #    To reduce lag, block transfers are slowed down when a player is building something.
 #    This determines how long they are slowed down after placing or removing a node.
 full_block_send_enable_min_time_from_building (Delay in sending blocks after building) float 2.0

minetest.conf.example

@@ -1049,13 +1049,11 @@
 ### Advanced
 
 #    Maximum number of blocks that are simultaneously sent per client.
+#    The maximum total count is calculated dynamically:
+#    max_total = ceil((#clients + max_users) * per_client / 4)
 #    type: int
 # max_simultaneous_block_sends_per_client = 10
 
-#    Maximum number of blocks that are simultaneously sent in total.
-#    type: int
-# max_simultaneous_block_sends_server_total = 40
-
 #    To reduce lag, block transfers are slowed down when a player is building something.
 #    This determines how long they are slowed down after placing or removing a node.
 #    type: float

src/clientiface.h

@@ -272,10 +272,7 @@ class RemoteClient
 	 */
 	void ResendBlockIfOnWire(v3s16 p);
 
-	s32 SendingCount()
-	{
-		return m_blocks_sending.size();
-	}
+	u32 getSendingCount() const { return m_blocks_sending.size(); }
 
 	// Increments timeouts and removes timed-out blocks from list
 	// NOTE: This doesn't fix the server-not-sending-block bug

src/defaultsettings.cpp

@@ -298,7 +298,6 @@ void set_default_settings(Settings *settings)
 	settings->setDefault("strict_protocol_version_checking", "false");
 	settings->setDefault("player_transfer_distance", "0");
 	settings->setDefault("max_simultaneous_block_sends_per_client", "10");
-	settings->setDefault("max_simultaneous_block_sends_server_total", "40");
 	settings->setDefault("time_send_interval", "5");
 
 	settings->setDefault("default_game", "minetest");

src/server.cpp

@@ -2181,7 +2181,7 @@ void Server::SendBlocks(float dtime)
 
 	std::vector<PrioritySortedBlockTransfer> queue;
 
-	s32 total_sending = 0;
+	u32 total_sending = 0;
 
 	{
 		ScopeProfiler sp2(g_profiler, "Server: selecting blocks for sending");
@@ -2195,7 +2195,7 @@ void Server::SendBlocks(float dtime)
 			if (!client)
 				continue;
 
-			total_sending += client->SendingCount();
+			total_sending += client->getSendingCount();
 			client->GetNextBlocks(m_env,m_emerge, dtime, queue);
 		}
 		m_clients.unlock();
@@ -2207,11 +2207,13 @@ void Server::SendBlocks(float dtime)
 	std::sort(queue.begin(), queue.end());
 
 	m_clients.lock();
-	s32 max_blocks_to_send =
-			g_settings->getS32("max_simultaneous_block_sends_server_total");
+
+	// Maximal total count calculation
+	// The per-client block sends is halved with the maximal online users
+	u32 max_blocks_to_send = (m_env->getPlayerCount() + g_settings->getU32("max_users")) *
+		g_settings->getU32("max_simultaneous_block_sends_per_client") / 4 + 1;
 
 	for (const PrioritySortedBlockTransfer &block_to_send : queue) {
-		//TODO: Calculate limit dynamically
 		if (total_sending >= max_blocks_to_send)
 			break;
 

src/serverenvironment.h

@@ -342,6 +342,7 @@ class ServerEnvironment : public Environment
 
 	RemotePlayer *getPlayer(const u16 peer_id);
 	RemotePlayer *getPlayer(const char* name);
+	u32 getPlayerCount() const { return m_players.size(); }
 
 	static bool migratePlayersDatabase(const GameParams &game_params,
 			const Settings &cmd_args);