Only send terminal state to interacting players

This splits the computer state (blinking, label, etc...) and terminal
state into two separate packets. When a computer changes, the computer
state is sent to all players and the terminal state is sent to players
who are curerntly using the computer.

This reduces network usage by a substantial amount.

src/main/java/dan200/computercraft/shared/computer/core/ClientComputer.java

@@ -153,11 +153,8 @@ public class ClientComputer extends ClientTerminal
         ComputerCraft.sendToServer( packet );
     }
 
-    @Override
-    public void readDescription( NBTTagCompound nbttagcompound )
+    private void readComputerDescription( NBTTagCompound nbttagcompound )
     {
-        super.readDescription( nbttagcompound );
-
         int oldID = m_computerID;
         String oldLabel = m_label;
         boolean oldOn = m_on;
@@ -189,10 +186,11 @@ public class ClientComputer extends ClientTerminal
         switch( packet.m_packetType )
         {
             case ComputerCraftPacket.ComputerChanged:
-            {
+                readComputerDescription( packet.m_dataNBT );
+                break;
+            case ComputerCraftPacket.ComputerTerminalChanged:
                 readDescription( packet.m_dataNBT );
                 break;
-            }
         }
     }
 }

src/main/java/dan200/computercraft/shared/computer/core/ServerComputer.java

@@ -20,10 +20,13 @@ import dan200.computercraft.shared.network.ComputerCraftPacket;
 import dan200.computercraft.shared.network.INetworkedThing;
 import dan200.computercraft.shared.util.NBTUtil;
 import net.minecraft.entity.player.EntityPlayer;
+import net.minecraft.entity.player.EntityPlayerMP;
 import net.minecraft.inventory.Container;
 import net.minecraft.nbt.NBTTagCompound;
+import net.minecraft.server.MinecraftServer;
 import net.minecraft.util.math.BlockPos;
 import net.minecraft.world.World;
+import net.minecraftforge.fml.common.FMLCommonHandler;
 import net.minecraftforge.fml.common.Loader;
 
 import java.io.InputStream;
@@ -131,27 +134,62 @@ public class ServerComputer extends ServerTerminal
     {
         m_changed = true;
     }
-
-    public void broadcastState()
-    {
-        // Send state to client
+    
+    private ComputerCraftPacket createComputerPacket() {
         ComputerCraftPacket packet = new ComputerCraftPacket();
         packet.m_packetType = ComputerCraftPacket.ComputerChanged;
         packet.m_dataInt = new int[] { getInstanceID() };
         packet.m_dataNBT = new NBTTagCompound();
-        writeDescription( packet.m_dataNBT );
-        ComputerCraft.sendToAllPlayers( packet );
+        writeComputerDescription( packet.m_dataNBT );
+        return packet;
     }
 
-    public void sendState( EntityPlayer player )
-    {
-        // Send state to client
+    private ComputerCraftPacket createTerminalPacket() {
         ComputerCraftPacket packet = new ComputerCraftPacket();
-        packet.m_packetType = ComputerCraftPacket.ComputerChanged;
+        packet.m_packetType = ComputerCraftPacket.ComputerTerminalChanged;
         packet.m_dataInt = new int[] { getInstanceID() };
         packet.m_dataNBT = new NBTTagCompound();
         writeDescription( packet.m_dataNBT );
-        ComputerCraft.sendToPlayer( player, packet );
+        return packet;
+    }
+
+    public void broadcastState(boolean force)
+    {
+        if(hasOutputChanged() || force)
+        {
+            // Send computer state to all clients
+            ComputerCraft.sendToAllPlayers( createComputerPacket() );
+        }
+
+        if( hasTerminalChanged() || force )
+        {
+            // Send terminal state to clients who are currently interacting with the computer.
+            FMLCommonHandler handler = FMLCommonHandler.instance();
+            if( handler != null )
+            {
+                ComputerCraftPacket packet = createTerminalPacket();
+                MinecraftServer server = handler.getMinecraftServerInstance();
+                for( EntityPlayerMP player : server.getPlayerList().getPlayers() )
+                {
+                    if( isInteracting( player ) )
+                    {
+                        ComputerCraft.sendToPlayer( player, packet );
+                    }
+                }
+            }
+        }
+    }
+
+    public void sendComputerState( EntityPlayer player )
+    {
+        // Send state to client
+        ComputerCraft.sendToPlayer( player, createComputerPacket() );
+    }
+
+    public void sendTerminalState( EntityPlayer player )
+    {
+        // Send terminal state to client
+        ComputerCraft.sendToPlayer( player, createTerminalPacket() );
     }
 
     public void broadcastDelete()
@@ -336,12 +374,8 @@ public class ServerComputer extends ServerTerminal
     }
 
     // Networking stuff
-
-    @Override
-    public void writeDescription( NBTTagCompound nbttagcompound )
+    public void writeComputerDescription( NBTTagCompound nbttagcompound )
     {
-        super.writeDescription( nbttagcompound );
-
         nbttagcompound.setInteger( "id", m_computer.getID() );
         String label = m_computer.getLabel();
         if( label != null )
@@ -362,14 +396,9 @@ public class ServerComputer extends ServerTerminal
     public void handlePacket( ComputerCraftPacket packet, EntityPlayer sender )
     {
         // Allow Computer/Tile updates as they may happen at any time.
-        if (packet.requiresContainer()) {
-            if (sender == null) return;
-
-            Container container = sender.openContainer;
-            if (!(container instanceof IContainerComputer)) return;
-
-            IComputer computer = ((IContainerComputer) container).getComputer();
-            if (computer != this) return;
+        if( packet.requiresContainer() && !isInteracting( sender ) )
+        {
+            return;
         }
 
         // Receive packets sent from the client to the server
@@ -415,9 +444,20 @@ public class ServerComputer extends ServerTerminal
             case ComputerCraftPacket.RequestComputerUpdate:
             {
                 // A player asked for an update on the state of the terminal
-                sendState( sender );
+                sendComputerState( sender );
                 break;
             }
         }
     }
+
+    private boolean isInteracting( EntityPlayer player )
+    {
+        if( player == null ) return false;
+
+        Container container = player.openContainer;
+        if( !(container instanceof IContainerComputer) ) return false;
+
+        IComputer computer = ((IContainerComputer) container).getComputer();
+        return computer == this;
+    }
 }

src/main/java/dan200/computercraft/shared/computer/core/ServerComputerRegistry.java

@@ -33,7 +33,7 @@ public class ServerComputerRegistry extends ComputerRegistry<ServerComputer>
                 computer.update();
                 if( computer.hasTerminalChanged() || computer.hasOutputChanged() )
                 {
-                    computer.broadcastState();
+                    computer.broadcastState(false);
                 }
             }
         }
@@ -44,7 +44,7 @@ public class ServerComputerRegistry extends ComputerRegistry<ServerComputer>
     {
         //System.out.println( "ADD SERVER COMPUTER " + instanceID );
         super.add( instanceID, computer );
-        computer.broadcastState();
+        computer.broadcastState(true);
         //System.out.println( getComputers().size() + " SERVER COMPUTERS" );
     }