feat: Optimize ServerWaypointManager when locator bar is disabled

The waypoint system  iterates over each player for running waypoint calculations. This, most notably, is done on setPosRaw which is executed twice for each player (one for non players).
This results in every time a player moves, it iterates over each player twice.

So instead, we cache the game rule and instead use this to prevent iterating over all the players and avoid the redundant connection logic checks.

This performance issue is most noticeable with many players on the same level.

Author: Owen1212055

paper-server/patches/sources/net/minecraft/server/MinecraftServer.java.patch

@@ -1533,7 +1533,7 @@
                  player.connection.send(new ClientboundEntityEventPacket(player, event));
              }
          } else if (rule == GameRules.LIMITED_CRAFTING || rule == GameRules.IMMEDIATE_RESPAWN) {
-@@ -2131,19 +_,20 @@
+@@ -2131,19 +_,21 @@
                  ? ClientboundGameEventPacket.LIMITED_CRAFTING
                  : ClientboundGameEventPacket.IMMEDIATE_RESPAWN;
              ClientboundGameEventPacket packet = new ClientboundGameEventPacket(eventType, (Boolean)value ? 1.0F : 0.0F);
@@ -1543,6 +1543,7 @@
 -            this.getAllLevels().forEach(level -> {
 +            // this.getAllLevels().forEach(level -> { // Paper - per-world game rules
                  ServerWaypointManager waypointManager = level.getWaypointManager();
++                waypointManager.locatorBarEnabled = (Boolean) value; // Paper - optimize ServerWaypointManager with locator bar disabled
                  if ((Boolean)value) {
                      level.players().forEach(waypointManager::updatePlayer);
                  } else {

paper-server/patches/sources/net/minecraft/server/level/ServerLevel.java.patch

@@ -241,8 +241,12 @@
              generator,
              this.chunkSource.randomState(),
              this,
-@@ -303,7 +_,15 @@
-         this.waypointManager = new ServerWaypointManager();
+@@ -300,10 +_,18 @@
+ 
+         this.sleepStatus = new SleepStatus();
+         this.gameEventDispatcher = new GameEventDispatcher(this);
+-        this.waypointManager = new ServerWaypointManager();
++        this.waypointManager = new ServerWaypointManager(this);
          this.environmentAttributes = EnvironmentAttributeSystem.builder().addDefaultLayers(this).build();
          this.updateSkyBrightness();
 -    }

paper-server/patches/sources/net/minecraft/server/waypoints/ServerWaypointManager.java.patch

@@ -0,0 +1,72 @@
+--- a/net/minecraft/server/waypoints/ServerWaypointManager.java
++++ b/net/minecraft/server/waypoints/ServerWaypointManager.java
+@@ -19,11 +_,19 @@
+     private final Set<WaypointTransmitter> waypoints = new HashSet<>();
+     private final Set<ServerPlayer> players = new HashSet<>();
+     private final Table<ServerPlayer, WaypointTransmitter, WaypointTransmitter.Connection> connections = HashBasedTable.create();
++    // Paper start - optimize ServerWaypointManager with locator bar disabled
++    public boolean locatorBarEnabled; // Avoid a gamerule lookup for each player
++
++    public ServerWaypointManager(net.minecraft.server.level.ServerLevel serverLevel) {
++        this.locatorBarEnabled = serverLevel.getGameRules().get(GameRules.LOCATOR_BAR);
++    }
++    // Paper end - optimize ServerWaypointManager with locator bar disabled
+ 
+     @Override
+     public void trackWaypoint(final WaypointTransmitter waypoint) {
+         this.waypoints.add(waypoint);
+ 
++        if (!this.locatorBarEnabled) return; // Paper - optimize ServerWaypointManager with locator bar disabled
+         for (ServerPlayer player : this.players) {
+             this.createConnection(player, waypoint);
+         }
+@@ -31,6 +_,7 @@
+ 
+     @Override
+     public void updateWaypoint(final WaypointTransmitter waypoint) {
++        if (!this.locatorBarEnabled) return; // Paper - optimize ServerWaypointManager with locator bar disabled
+         if (this.waypoints.contains(waypoint)) {
+             Map<ServerPlayer, WaypointTransmitter.Connection> playerConnection = Tables.transpose(this.connections).row(waypoint);
+             SetView<ServerPlayer> potentialPlayers = Sets.difference(this.players, playerConnection.keySet());
+@@ -55,9 +_,11 @@
+     public void addPlayer(final ServerPlayer player) {
+         this.players.add(player);
+ 
++        if (this.locatorBarEnabled) { // Paper - optimize ServerWaypointManager with locator bar disabled
+         for (WaypointTransmitter waypoint : this.waypoints) {
+             this.createConnection(player, waypoint);
+         }
++        } // Paper - optimize ServerWaypointManager with locator bar disabled
+ 
+         if (player.isTransmittingWaypoint()) {
+             this.trackWaypoint((WaypointTransmitter)player);
+@@ -65,6 +_,7 @@
+     }
+ 
+     public void updatePlayer(final ServerPlayer player) {
++        if (!this.locatorBarEnabled) return; // Paper - optimize ServerWaypointManager with locator bar disabled
+         Map<WaypointTransmitter, WaypointTransmitter.Connection> waypointConnections = this.connections.row(player);
+         SetView<WaypointTransmitter> potentialWaypoints = Sets.difference(this.waypoints, waypointConnections.keySet());
+ 
+@@ -92,6 +_,7 @@
+     }
+ 
+     public void remakeConnections(final WaypointTransmitter waypoint) {
++        if (!this.locatorBarEnabled) return; // Paper - optimize ServerWaypointManager with locator bar disabled
+         for (ServerPlayer player : this.players) {
+             this.createConnection(player, waypoint);
+         }
+@@ -101,8 +_,11 @@
+         return this.waypoints;
+     }
+ 
+-    private static boolean isLocatorBarEnabledFor(final ServerPlayer player) {
+-        return player.level().getGameRules().get(GameRules.LOCATOR_BAR);
++    // Paper start - optimize ServerWaypointManager with locator bar disabled
++    // Avoid a gamerule lookup for each player
++    private boolean isLocatorBarEnabledFor(final ServerPlayer player) {
++        return locatorBarEnabled;
++    // Paper end - optimize ServerWaypointManager with locator bar disabled
+     }
+ 
+     private void createConnection(final ServerPlayer player, final WaypointTransmitter waypoint) {