A couple of minor cleanups on the last commit

- Remove a redundant logger
 - Provide a getter for the ComputerCraft thread group. This allows us
   to monitor child threads within prometheus.
 - Replace a deprecated call with a fastutils alternative.

.gitignore

@@ -1,12 +1,12 @@
-build
-out
-run
-deploy
+/build
+/out
+/run
 *.ipr
 *.iws
 *.iml
 .idea
 .gradle
-luaj-2.0.3/lib
-luaj-2.0.3/*.jar
+/luaj-2.0.3/lib
+/luaj-2.0.3/*.jar
 *.DS_Store
+/test-files

build.gradle

@@ -23,7 +23,7 @@ apply plugin: 'org.ajoberstar.grgit'
 apply plugin: 'maven-publish'
 apply plugin: 'maven'
 
-version = "1.80pr1.9"
+version = "1.80pr1.11"
 group = "org.squiddev"
 archivesBaseName = "cc-tweaked"
 
@@ -66,7 +66,7 @@ dependencies {
 
     runtime "mezz.jei:jei_1.12.2:4.8.5.159"
 
-    shade 'org.squiddev:Cobalt:0.3.2'
+    shade 'org.squiddev:Cobalt:0.4.0'
 
     testCompile 'junit:junit:4.11'
 

build_luaj.sh

@@ -1,12 +0,0 @@
-#!/bin/sh
-cd luaj-2.0.3
-echo "Building LuaJ..."
-ant clean
-ant
-
-echo "Copying output to libs..."
-rm ../libs/luaj-jse-2.0.3.jar
-cp luaj-jse-2.0.3.jar ../libs
-
-echo "Done."
-cd ..

codesize.sh

@@ -1,10 +0,0 @@
-#!/bin/sh
-echo "Java code:"
-cat `find src | grep \\.java$` | wc
-
-echo "Lua code:"
-cat `find src/main/resources/assets/computercraft/lua | grep \\.lua$` | wc
-
-echo "JSON:"
-cat `find src/main/resources/assets/computercraft | grep \\.json$` | wc
-

deploy.sh

@@ -1,21 +0,0 @@
-#!/bin/sh
-
-echo "Building with gradle..."
-rm -rf build/libs
-rm -rf build/resources
-rm -rf build/classes
-chmod -R +rw src/main/resources
-chmod +x gradlew
-./gradlew build
-
-echo "Deleting old deployment..."
-rm -rf deploy
-mkdir deploy
-
-echo "Making new deployment..."
-INPUTJAR=`ls -1 build/libs | grep -v sources`
-OUTPUTJAR=`ls -1 build/libs | grep -v sources | sed s/\-//g`
-FRIENDLYNAME=`ls -1 build/libs | grep -v sources | sed s/\-/\ /g | sed s/\.jar//g`
-cp build/libs/$INPUTJAR deploy/$OUTPUTJAR
-
-echo "Done."

setup.bat

@@ -1,7 +0,0 @@
-echo "Setting up IntelliJ development environment with gradle..."
-rmdir /s /q .\build
-call gradlew.bat --stacktrace setupDecompWorkspace --refresh-dependencies
-call gradlew.bat --stacktrace cleanIdea idea
-
-echo "Done."
-pause

setup.sh

@@ -1,14 +0,0 @@
-#!/bin/sh
-
-echo "Setting permissions..."
-chmod +x codesize.sh
-chmod +x build_luaj.sh
-chmod +x deploy.sh
-chmod +x gradlew
-
-echo "Setting up IntelliJ development environment with gradle..."
-rm -rf build
-./gradlew --stacktrace setupDecompWorkspace --refresh-dependencies
-./gradlew --stacktrace cleanIdea idea
-
-echo "Done."

src/main/java/dan200/computercraft/ComputerCraft.java

@@ -29,8 +29,6 @@ import dan200.computercraft.core.filesystem.FileMount;
 import dan200.computercraft.core.filesystem.FileSystemMount;
 import dan200.computercraft.core.terminal.Terminal;
 import dan200.computercraft.core.tracking.Tracking;
-import dan200.computercraft.shared.command.CommandComputer;
-import dan200.computercraft.shared.command.CommandComputerCraft;
 import dan200.computercraft.shared.common.DefaultBundledRedstoneProvider;
 import dan200.computercraft.shared.computer.blocks.BlockCommandComputer;
 import dan200.computercraft.shared.computer.blocks.BlockComputer;
@@ -60,7 +58,10 @@ import dan200.computercraft.shared.proxy.IComputerCraftProxy;
 import dan200.computercraft.shared.turtle.blocks.BlockTurtle;
 import dan200.computercraft.shared.turtle.blocks.TileTurtle;
 import dan200.computercraft.shared.turtle.upgrades.*;
-import dan200.computercraft.shared.util.*;
+import dan200.computercraft.shared.util.CreativeTabMain;
+import dan200.computercraft.shared.util.IDAssigner;
+import dan200.computercraft.shared.util.InventoryUtil;
+import dan200.computercraft.shared.util.WorldUtil;
 import dan200.computercraft.shared.wired.CapabilityWiredElement;
 import dan200.computercraft.shared.wired.WiredNode;
 import io.netty.buffer.Unpooled;
@@ -99,7 +100,6 @@ import java.net.URISyntaxException;
 import java.net.URL;
 import java.nio.file.FileSystem;
 import java.nio.file.FileSystems;
-import java.nio.file.ProviderNotFoundException;
 import java.util.*;
 import java.util.function.Function;
 import java.util.zip.ZipEntry;
@@ -111,12 +111,12 @@ import java.util.zip.ZipFile;
 
 @Mod(
     modid = ComputerCraft.MOD_ID, name = "CC: Tweaked", version = "${version}",
-    guiFactory = "dan200.computercraft.client.gui.GuiConfigCC$Factory"
+    guiFactory = "dan200.computercraft.client.gui.GuiConfigCC$Factory",
+    dependencies = "required:forge@[14.23.4.2746,)"
 )
 public class ComputerCraft
 {
     public static final String MOD_ID = "computercraft";
-    public static final String LOWER_ID = "computercraft";
 
     // GUI IDs
     public static final int diskDriveGUIID = 100;
@@ -570,7 +570,7 @@ public class ComputerCraft
             width = terminal.getWidth();
             height = terminal.getHeight();
         }
-        
+
         // Pack useful terminal information into the various coordinate bits.
         // These are extracted in ComputerCraftProxyCommon.getClientGuiElement
         player.openGui( ComputerCraft.instance, ComputerCraft.viewComputerGUIID, player.getEntityWorld(),
@@ -928,7 +928,7 @@ public class ComputerCraft
                 FileSystem fs = FileSystems.newFileSystem( modJar.toPath(), ComputerCraft.class.getClassLoader() );
                 mounts.add( new FileSystemMount( fs, subPath ) );
             }
-            catch( IOException | ProviderNotFoundException | ServiceConfigurationError e )
+            catch( IOException | RuntimeException | ServiceConfigurationError e )
             {
                 ComputerCraft.log.error( "Could not load mount from mod jar", e );
                 // Ignore
@@ -940,16 +940,16 @@ public class ComputerCraft
         if( resourcePackDir.exists() && resourcePackDir.isDirectory() )
         {
             String[] resourcePacks = resourcePackDir.list();
-            for( String resourcePack1 : resourcePacks )
+            for( String resourcePackName : resourcePacks )
             {
                 try
                 {
-                    File resourcePack = new File( resourcePackDir, resourcePack1 );
+                    File resourcePack = new File( resourcePackDir, resourcePackName );
                     if( !resourcePack.isDirectory() )
                     {
                         // Mount a resource pack from a jar
-                        IMount resourcePackMount = new FileSystemMount( FileSystems.getFileSystem( resourcePack.toURI() ), subPath );
-                        mounts.add( resourcePackMount );
+                        FileSystem fs = FileSystems.newFileSystem( resourcePack.toPath(), ComputerCraft.class.getClassLoader() );
+                        mounts.add( new FileSystemMount( fs, subPath ) );
                     }
                     else
                     {
@@ -962,9 +962,9 @@ public class ComputerCraft
                         }
                     }
                 }
-                catch( IOException e )
+                catch( IOException | RuntimeException | ServiceConfigurationError e )
                 {
-                    ComputerCraft.log.error( "Could not load resource pack '" + resourcePack1 + "'", e );
+                    ComputerCraft.log.error( "Could not load resource pack '" + resourcePackName + "'", e );
                 }
             }
         }
@@ -1113,7 +1113,7 @@ public class ComputerCraft
     {
         return turtleProxy.getTurtleUpgrade( id );
     }
-    
+
     public static ITurtleUpgrade getTurtleUpgrade( int legacyID )
     {
         return turtleProxy.getTurtleUpgrade( legacyID );

src/main/java/dan200/computercraft/client/proxy/ComputerCraftProxyClient.java

@@ -8,11 +8,7 @@ package dan200.computercraft.client.proxy;
 
 import dan200.computercraft.ComputerCraft;
 import dan200.computercraft.client.gui.*;
-import dan200.computercraft.client.render.ItemPocketRenderer;
-import dan200.computercraft.client.render.ItemPrintoutRenderer;
-import dan200.computercraft.client.render.RenderOverlayCable;
-import dan200.computercraft.client.render.TileEntityCableRenderer;
-import dan200.computercraft.client.render.TileEntityMonitorRenderer;
+import dan200.computercraft.client.render.*;
 import dan200.computercraft.shared.command.ContainerViewComputer;
 import dan200.computercraft.shared.computer.blocks.ComputerState;
 import dan200.computercraft.shared.computer.blocks.TileComputer;
@@ -35,7 +31,7 @@ import dan200.computercraft.shared.proxy.ComputerCraftProxyCommon;
 import dan200.computercraft.shared.turtle.blocks.TileTurtle;
 import dan200.computercraft.shared.turtle.entity.TurtleVisionCamera;
 import dan200.computercraft.shared.util.Colour;
-import gnu.trove.map.hash.TIntIntHashMap;
+import it.unimi.dsi.fastutil.ints.Int2IntOpenHashMap;
 import net.minecraft.block.Block;
 import net.minecraft.client.Minecraft;
 import net.minecraft.client.gui.GuiNewChat;
@@ -75,7 +71,7 @@ import java.util.List;
 
 public class ComputerCraftProxyClient extends ComputerCraftProxyCommon
 {
-    private static TIntIntHashMap lastCounts = new TIntIntHashMap();
+    private static Int2IntOpenHashMap lastCounts = new Int2IntOpenHashMap();
 
     private long m_tick;
     private long m_renderFrame;

src/main/java/dan200/computercraft/client/render/TurtleSmartItemModel.java

@@ -18,12 +18,14 @@ import net.minecraft.client.Minecraft;
 import net.minecraft.client.renderer.block.model.*;
 import net.minecraft.client.renderer.texture.TextureAtlasSprite;
 import net.minecraft.client.resources.IResourceManager;
-import net.minecraft.client.resources.IResourceManagerReloadListener;
 import net.minecraft.entity.EntityLivingBase;
 import net.minecraft.item.ItemStack;
 import net.minecraft.util.EnumFacing;
 import net.minecraft.util.ResourceLocation;
 import net.minecraft.world.World;
+import net.minecraftforge.client.resource.IResourceType;
+import net.minecraftforge.client.resource.ISelectiveResourceReloadListener;
+import net.minecraftforge.client.resource.VanillaResourceType;
 import org.apache.commons.lang3.tuple.Pair;
 
 import javax.annotation.Nonnull;
@@ -32,8 +34,9 @@ import javax.vecmath.Matrix4f;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
+import java.util.function.Predicate;
 
-public class TurtleSmartItemModel implements IBakedModel, IResourceManagerReloadListener
+public class TurtleSmartItemModel implements IBakedModel, ISelectiveResourceReloadListener
 {
     private static final Matrix4f s_identity, s_flip;
 
@@ -155,9 +158,9 @@ public class TurtleSmartItemModel implements IBakedModel, IResourceManagerReload
     }
 
     @Override
-    public void onResourceManagerReload( @Nonnull IResourceManager resourceManager )
+    public void onResourceManagerReload( @Nonnull IResourceManager resourceManager, @Nonnull Predicate<IResourceType> resourcePredicate )
     {
-        m_cachedModels.clear();
+        if( resourcePredicate.test( VanillaResourceType.MODELS ) ) m_cachedModels.clear();
     }
 
     private IBakedModel buildModel( TurtleModelCombination combo )

src/main/java/dan200/computercraft/core/apis/handles/BinaryReadableHandle.java

@@ -33,7 +33,7 @@ public class BinaryReadableHandle extends HandleGeneric
     {
         super( closeable );
         this.m_reader = channel;
-        this.m_seekable = channel instanceof SeekableByteChannel ? (SeekableByteChannel) channel : null;
+        this.m_seekable = asSeekable( channel );
     }
 
     public BinaryReadableHandle( ReadableByteChannel channel )
@@ -118,7 +118,7 @@ public class BinaryReadableHandle extends HandleGeneric
                     {
                         single.clear();
                         int b = m_reader.read( single );
-                        return b == -1 ? null : new Object[] { single.get( 0 ) };
+                        return b == -1 ? null : new Object[] { single.get( 0 ) & 0xFF };
                     }
                 }
                 catch( IOException e )

src/main/java/dan200/computercraft/core/apis/handles/BinaryWritableHandle.java

@@ -27,7 +27,7 @@ public class BinaryWritableHandle extends HandleGeneric
     {
         super( closeable );
         this.m_writer = channel;
-        this.m_seekable = channel instanceof SeekableByteChannel ? (SeekableByteChannel) channel : null;
+        this.m_seekable = asSeekable( channel );
     }
 
     public BinaryWritableHandle( WritableByteChannel channel )

src/main/java/dan200/computercraft/core/apis/handles/EncodedReadableHandle.java

@@ -10,6 +10,8 @@ import java.io.IOException;
 import java.nio.channels.Channels;
 import java.nio.channels.ReadableByteChannel;
 import java.nio.charset.Charset;
+import java.nio.charset.CharsetDecoder;
+import java.nio.charset.CodingErrorAction;
 import java.nio.charset.StandardCharsets;
 
 import static dan200.computercraft.core.apis.ArgumentHelper.optBoolean;
@@ -35,7 +37,7 @@ public class EncodedReadableHandle extends HandleGeneric
     @Nonnull
     @Override
     public String[] getMethodNames()
-    {
+    {   
         return new String[] {
             "readLine",
             "readAll",
@@ -160,6 +162,11 @@ public class EncodedReadableHandle extends HandleGeneric
 
     public static BufferedReader open( ReadableByteChannel channel, Charset charset )
     {
-        return new BufferedReader( Channels.newReader( channel, charset.newDecoder(), -1 ) );
+        // Create a charset decoder with the same properties as StreamDecoder does for 
+        // InputStreams: namely, replace everything instead of erroring.
+        CharsetDecoder decoder = charset.newDecoder()
+            .onMalformedInput( CodingErrorAction.REPLACE )
+            .onUnmappableCharacter( CodingErrorAction.REPLACE );
+        return new BufferedReader( Channels.newReader( channel, decoder, -1 ) );
     }
 }

src/main/java/dan200/computercraft/core/apis/handles/EncodedWritableHandle.java

@@ -10,6 +10,8 @@ import java.io.IOException;
 import java.nio.channels.Channels;
 import java.nio.channels.WritableByteChannel;
 import java.nio.charset.Charset;
+import java.nio.charset.CharsetEncoder;
+import java.nio.charset.CodingErrorAction;
 import java.nio.charset.StandardCharsets;
 
 public class EncodedWritableHandle extends HandleGeneric
@@ -120,6 +122,11 @@ public class EncodedWritableHandle extends HandleGeneric
 
     public static BufferedWriter open( WritableByteChannel channel, Charset charset )
     {
-        return new BufferedWriter( Channels.newWriter( channel, charset.newEncoder(), -1 ) );
+        // Create a charset encoder with the same properties as StreamEncoder does for 
+        // OutputStreams: namely, replace everything instead of erroring.
+        CharsetEncoder encoder = charset.newEncoder()
+            .onMalformedInput( CodingErrorAction.REPLACE)
+            .onUnmappableCharacter(CodingErrorAction.REPLACE);
+        return new BufferedWriter( Channels.newWriter( channel, encoder, -1 ) );
     }
 }

src/main/java/dan200/computercraft/core/apis/handles/HandleGeneric.java

@@ -6,6 +6,7 @@ import dan200.computercraft.api.lua.LuaException;
 import javax.annotation.Nonnull;
 import java.io.Closeable;
 import java.io.IOException;
+import java.nio.channels.Channel;
 import java.nio.channels.SeekableByteChannel;
 
 import static dan200.computercraft.core.apis.ArgumentHelper.optInt;
@@ -69,15 +70,31 @@ public abstract class HandleGeneric implements ILuaObject
                     throw new LuaException( "bad argument #1 to 'seek' (invalid option '" + whence + "'" );
             }
 
-            return new Object[] { channel.position() };
+            return new Object[]{ channel.position() };
         }
         catch( IllegalArgumentException e )
         {
-            return new Object[] { false, "Position is negative" };
+            return new Object[]{ false, "Position is negative" };
         }
         catch( IOException e )
         {
             return null;
         }
     }
+
+    protected static SeekableByteChannel asSeekable( Channel channel )
+    {
+        if( !(channel instanceof SeekableByteChannel) ) return null;
+
+        SeekableByteChannel seekable = (SeekableByteChannel) channel;
+        try
+        {
+            seekable.position( seekable.position() );
+            return seekable;
+        }
+        catch( IOException | UnsupportedOperationException e )
+        {
+            return null;
+        }
+    }
 }

src/main/java/dan200/computercraft/core/apis/http/HTTPExecutor.java

@@ -8,7 +8,7 @@ package dan200.computercraft.core.apis.http;
 
 import com.google.common.util.concurrent.ListeningExecutorService;
 import com.google.common.util.concurrent.MoreExecutors;
-import com.google.common.util.concurrent.ThreadFactoryBuilder;
+import dan200.computercraft.shared.util.ThreadUtils;
 import io.netty.channel.EventLoopGroup;
 import io.netty.channel.nio.NioEventLoopGroup;
 
@@ -24,18 +24,14 @@ public final class HTTPExecutor
     public static final ListeningExecutorService EXECUTOR = MoreExecutors.listeningDecorator( new ThreadPoolExecutor(
         4, Integer.MAX_VALUE,
         60L, TimeUnit.SECONDS,
-        new SynchronousQueue<Runnable>(),
-        new ThreadFactoryBuilder()
-            .setDaemon( true )
+        new SynchronousQueue<>(),
+        ThreadUtils.builder( "HTTP" )
             .setPriority( Thread.MIN_PRIORITY + (Thread.NORM_PRIORITY - Thread.MIN_PRIORITY) / 2 )
-            .setNameFormat( "ComputerCraft-HTTP-%d" )
             .build()
     ) );
 
-    public static final EventLoopGroup LOOP_GROUP = new NioEventLoopGroup( 4, new ThreadFactoryBuilder()
-        .setDaemon( true )
+    public static final EventLoopGroup LOOP_GROUP = new NioEventLoopGroup( 4, ThreadUtils.builder( "Netty" )
         .setPriority( Thread.MIN_PRIORITY + (Thread.NORM_PRIORITY - Thread.MIN_PRIORITY) / 2 )
-        .setNameFormat( "ComputerCraft-Netty-%d" )
         .build()
     );
 

src/main/java/dan200/computercraft/core/computer/ComputerThread.java

@@ -8,13 +8,14 @@ package dan200.computercraft.core.computer;
 
 import dan200.computercraft.ComputerCraft;
 import dan200.computercraft.core.tracking.Tracking;
+import dan200.computercraft.shared.util.ThreadUtils;
 
 import java.util.HashSet;
 import java.util.Set;
 import java.util.WeakHashMap;
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.LinkedBlockingQueue;
-import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.ThreadFactory;
 
 public class ComputerThread
 {
@@ -56,8 +57,8 @@ public class ComputerThread
      */
     private static Thread[] s_threads = null;
 
-    private static final AtomicInteger s_ManagerCounter = new AtomicInteger( 1 );
-    private static final AtomicInteger s_DelegateCounter = new AtomicInteger( 1 );
+    private static final ThreadFactory s_ManagerFactory = ThreadUtils.factory( "Computer-Manager" );
+    private static final ThreadFactory s_RunnerFactory = ThreadUtils.factory( "Computer-Runner" );
 
     /**
      * Start the computer thread
@@ -72,16 +73,12 @@ public class ComputerThread
                 s_threads = new Thread[ComputerCraft.computer_threads];
             }
 
-            SecurityManager manager = System.getSecurityManager();
-            final ThreadGroup group = manager == null ? Thread.currentThread().getThreadGroup() : manager.getThreadGroup();
             for( int i = 0; i < s_threads.length; i++ )
             {
                 Thread thread = s_threads[i];
                 if( thread == null || !thread.isAlive() )
                 {
-                    thread = s_threads[i] = new Thread( group, new TaskExecutor(), "ComputerCraft-Computer-Manager-" + s_ManagerCounter.getAndIncrement() );
-                    thread.setDaemon( true );
-                    thread.start();
+                    (s_threads[i] = s_ManagerFactory.newThread( new TaskExecutor() )).start();
                 }
             }
         }
@@ -188,12 +185,7 @@ public class ComputerThread
             if( thread == null || !thread.isAlive() )
             {
                 runner = new TaskRunner();
-
-                SecurityManager manager = System.getSecurityManager();
-                final ThreadGroup group = manager == null ? Thread.currentThread().getThreadGroup() : manager.getThreadGroup();
-                Thread thread = this.thread = new Thread( group, runner, "ComputerCraft-Computer-Runner" + s_DelegateCounter.getAndIncrement() );
-                thread.setDaemon( true );
-                thread.start();
+                (thread = s_RunnerFactory.newThread( runner )).start();
             }
 
             long start = System.nanoTime();

src/main/java/dan200/computercraft/core/filesystem/FileMount.java

@@ -6,6 +6,7 @@
 
 package dan200.computercraft.core.filesystem;
 
+import com.google.common.collect.Sets;
 import dan200.computercraft.api.filesystem.IWritableMount;
 
 import javax.annotation.Nonnull;
@@ -13,12 +14,18 @@ import java.io.*;
 import java.nio.ByteBuffer;
 import java.nio.channels.*;
 import java.nio.file.Files;
+import java.nio.file.OpenOption;
 import java.nio.file.StandardOpenOption;
+import java.util.Collections;
 import java.util.List;
+import java.util.Set;
 
 public class FileMount implements IWritableMount
 {
     private static final int MINIMUM_FILE_SIZE = 500;
+    private static final Set<OpenOption> READ_OPTIONS = Collections.singleton( StandardOpenOption.READ );
+    private static final Set<OpenOption> WRITE_OPTIONS = Sets.newHashSet( StandardOpenOption.WRITE, StandardOpenOption.CREATE, StandardOpenOption.TRUNCATE_EXISTING );
+    private static final Set<OpenOption> APPEND_OPTIONS = Sets.newHashSet( StandardOpenOption.WRITE, StandardOpenOption.CREATE, StandardOpenOption.APPEND );
 
     private class WritableCountingChannel implements WritableByteChannel
     {
@@ -252,7 +259,7 @@ public class FileMount implements IWritableMount
             File file = getRealPath( path );
             if( file.exists() && !file.isDirectory() )
             {
-                return FileChannel.open( file.toPath(), StandardOpenOption.READ );
+                return FileChannel.open( file.toPath(), READ_OPTIONS );
             }
         }
         throw new IOException( "/" + path + ": No such file" );
@@ -386,8 +393,7 @@ public class FileMount implements IWritableMount
                 m_usedSpace -= Math.max( file.length(), MINIMUM_FILE_SIZE );
                 m_usedSpace += MINIMUM_FILE_SIZE;
             }
-            return new SeekableCountingChannel( Files.newByteChannel( file.toPath(), StandardOpenOption.WRITE, StandardOpenOption.CREATE ),
-                MINIMUM_FILE_SIZE );
+            return new SeekableCountingChannel( Files.newByteChannel( file.toPath(), WRITE_OPTIONS ), MINIMUM_FILE_SIZE );
         }
     }
 
@@ -409,8 +415,10 @@ public class FileMount implements IWritableMount
             else
             {
                 // Allowing seeking when appending is not recommended, so we use a separate channel.
-                return new WritableCountingChannel( Files.newByteChannel( file.toPath(), StandardOpenOption.WRITE, StandardOpenOption.CREATE, StandardOpenOption.APPEND ),
-                    Math.max( MINIMUM_FILE_SIZE - file.length(), 0 ) );
+                return new WritableCountingChannel(
+                    Files.newByteChannel( file.toPath(), APPEND_OPTIONS ),
+                    Math.max( MINIMUM_FILE_SIZE - file.length(), 0 )
+                );
             }
         }
         else

src/main/java/dan200/computercraft/core/filesystem/JarMount.java

@@ -0,0 +1,250 @@
+/*
+ * This file is part of ComputerCraft - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2017. Do not distribute without permission.
+ * Send enquiries to dratcliffe@gmail.com
+ */
+
+package dan200.computercraft.core.filesystem;
+
+import dan200.computercraft.api.filesystem.IMount;
+
+import javax.annotation.Nonnull;
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.Enumeration;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipFile;
+
+@Deprecated
+public class JarMount implements IMount
+{
+    private static class FileInZip
+    {
+        private String m_path;
+        private boolean m_directory;
+        private long m_size;
+        private Map<String, FileInZip> m_children;
+
+        public FileInZip( String path, boolean directory, long size )
+        {
+            m_path = path;
+            m_directory = directory;
+            m_size = m_directory ? 0 : size;
+            m_children = new LinkedHashMap<>();
+        }
+
+        public String getPath()
+        {
+            return m_path;
+        }
+
+        public boolean isDirectory()
+        {
+            return m_directory;
+        }
+
+        public long getSize()
+        {
+            return m_size;
+        }
+
+        public void list( List<String> contents )
+        {
+            contents.addAll( m_children.keySet() );
+        }
+
+        public void insertChild( FileInZip child )
+        {
+            String localPath = FileSystem.toLocal( child.getPath(), m_path );
+            m_children.put( localPath, child );
+        }
+
+        public FileInZip getFile( String path )
+        {
+            // If we've reached the target, return this
+            if( path.equals( m_path ) )
+            {
+                return this;
+            }
+
+            // Otherwise, get the next component of the path
+            String localPath = FileSystem.toLocal( path, m_path );
+            int slash = localPath.indexOf( "/" );
+            if( slash >= 0 )
+            {
+                localPath = localPath.substring( 0, slash );
+            }
+
+            // And recurse down using it
+            FileInZip subFile = m_children.get( localPath );
+            if( subFile != null )
+            {
+                return subFile.getFile( path );
+            }
+
+            return null;
+        }
+
+        public FileInZip getParent( String path )
+        {
+            if( path.length() == 0 )
+            {
+                return null;
+            }
+
+            FileInZip file = getFile( FileSystem.getDirectory( path ) );
+            if( file.isDirectory() )
+            {
+                return file;
+            }
+            return null;
+        }
+    }
+
+    private ZipFile m_zipFile;
+    private FileInZip m_root;
+    private String m_rootPath;
+
+    @Deprecated
+    public JarMount( File jarFile, String subPath ) throws IOException
+    {
+        if( !jarFile.exists() || jarFile.isDirectory() )
+        {
+            throw new FileNotFoundException();
+        }
+
+        // Open the zip file
+        try
+        {
+            m_zipFile = new ZipFile( jarFile );
+        }
+        catch( Exception e )
+        {
+            throw new IOException( "Error loading zip file" );
+        }
+
+        if( m_zipFile.getEntry( subPath ) == null )
+        {
+            m_zipFile.close();
+            throw new IOException( "Zip does not contain path" );
+        }
+
+        // Read in all the entries
+        Enumeration<? extends ZipEntry> zipEntries = m_zipFile.entries();
+        while( zipEntries.hasMoreElements() )
+        {
+            ZipEntry entry = zipEntries.nextElement();
+            String entryName = entry.getName();
+            if( entryName.startsWith( subPath ) )
+            {
+                entryName = FileSystem.toLocal( entryName, subPath );
+                if( m_root == null )
+                {
+                    if( entryName.equals( "" ) )
+                    {
+                        m_root = new FileInZip( entryName, entry.isDirectory(), entry.getSize() );
+                        m_rootPath = subPath;
+                        if( !m_root.isDirectory() )
+                        {
+                            break;
+                        }
+                    }
+                    else
+                    {
+                        // TODO: handle this case. The code currently assumes we find the root before anything else
+                    }
+                }
+                else
+                {
+                    FileInZip parent = m_root.getParent( entryName );
+                    if( parent != null )
+                    {
+                        parent.insertChild( new FileInZip( entryName, entry.isDirectory(), entry.getSize() ) );
+                    }
+                    else
+                    {
+                        // TODO: handle this case. The code currently assumes we find folders before their contents
+                    }
+                }
+            }
+        }
+    }
+
+    // IMount implementation
+
+    @Override
+    public boolean exists( @Nonnull String path )
+    {
+        FileInZip file = m_root.getFile( path );
+        return file != null;
+    }
+
+    @Override
+    public boolean isDirectory( @Nonnull String path )
+    {
+        FileInZip file = m_root.getFile( path );
+        if( file != null )
+        {
+            return file.isDirectory();
+        }
+        return false;
+    }
+
+    @Override
+    public void list( @Nonnull String path, @Nonnull List<String> contents ) throws IOException
+    {
+        FileInZip file = m_root.getFile( path );
+        if( file != null && file.isDirectory() )
+        {
+            file.list( contents );
+        }
+        else
+        {
+            throw new IOException( "/" + path + ": Not a directory" );
+        }
+    }
+
+    @Override
+    public long getSize( @Nonnull String path ) throws IOException
+    {
+        FileInZip file = m_root.getFile( path );
+        if( file != null )
+        {
+            return file.getSize();
+        }
+        throw new IOException( "/" + path + ": No such file" );
+    }
+
+    @Nonnull
+    @Override
+    public InputStream openForRead( @Nonnull String path ) throws IOException
+    {
+        FileInZip file = m_root.getFile( path );
+        if( file != null && !file.isDirectory() )
+        {
+            try
+            {
+                String fullPath = m_rootPath;
+                if( path.length() > 0 )
+                {
+                    fullPath = fullPath + "/" + path;
+                }
+                ZipEntry entry = m_zipFile.getEntry( fullPath );
+                if( entry != null )
+                {
+                    return m_zipFile.getInputStream( entry );
+                }
+            }
+            catch( Exception e )
+            {
+                // treat errors as non-existance of file
+            }
+        }
+        throw new IOException( "/" + path + ": No such file" );
+    }
+}

src/main/java/dan200/computercraft/core/lua/CobaltLuaMachine.java

@@ -7,14 +7,13 @@
 package dan200.computercraft.core.lua;
 
 import dan200.computercraft.ComputerCraft;
-import dan200.computercraft.api.lua.ILuaContext;
-import dan200.computercraft.api.lua.ILuaObject;
-import dan200.computercraft.api.lua.ILuaTask;
-import dan200.computercraft.api.lua.LuaException;
-import dan200.computercraft.api.lua.ILuaAPI;
+import dan200.computercraft.api.lua.*;
 import dan200.computercraft.core.computer.Computer;
 import dan200.computercraft.core.computer.ITask;
 import dan200.computercraft.core.computer.MainThread;
+import dan200.computercraft.core.tracking.Tracking;
+import dan200.computercraft.core.tracking.TrackingField;
+import dan200.computercraft.shared.util.ThreadUtils;
 import org.squiddev.cobalt.*;
 import org.squiddev.cobalt.compiler.CompileException;
 import org.squiddev.cobalt.compiler.LoadState;
@@ -25,7 +24,7 @@ import org.squiddev.cobalt.function.LibFunction;
 import org.squiddev.cobalt.function.LuaFunction;
 import org.squiddev.cobalt.function.VarArgFunction;
 import org.squiddev.cobalt.lib.*;
-import org.squiddev.cobalt.lib.platform.AbstractResourceManipulator;
+import org.squiddev.cobalt.lib.platform.VoidResourceManipulator;
 
 import javax.annotation.Nonnull;
 import java.io.IOException;
@@ -35,6 +34,9 @@ import java.util.Arrays;
 import java.util.HashMap;
 import java.util.IdentityHashMap;
 import java.util.Map;
+import java.util.concurrent.SynchronousQueue;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
 
 import static org.squiddev.cobalt.Constants.NONE;
 import static org.squiddev.cobalt.ValueFactory.valueOf;
@@ -42,12 +44,19 @@ import static org.squiddev.cobalt.ValueFactory.varargsOf;
 
 public class CobaltLuaMachine implements ILuaMachine
 {
+    private static final ThreadPoolExecutor coroutines = new ThreadPoolExecutor(
+        0, Integer.MAX_VALUE,
+        60L, TimeUnit.SECONDS,
+        new SynchronousQueue<>(),
+        ThreadUtils.factory( "Coroutine" )
+    );
+
     private final Computer m_computer;
 
-    private final LuaState m_state;
-    private final LuaTable m_globals;
-
+    private LuaState m_state;
+    private LuaTable m_globals;
     private LuaThread m_mainRoutine;
+
     private String m_eventFilter;
     private String m_softAbortMessage;
     private String m_hardAbortMessage;
@@ -57,60 +66,71 @@ public class CobaltLuaMachine implements ILuaMachine
         m_computer = computer;
 
         // Create an environment to run in
-        final LuaState state = this.m_state = new LuaState( new AbstractResourceManipulator()
-        {
-            @Override
-            public InputStream findResource( String filename )
+        LuaState state = this.m_state = LuaState.builder()
+            .resourceManipulator( new VoidResourceManipulator() )
+            .debug( new DebugHandler()
             {
-                return null;
-            }
-        } );
-        state.debug = new DebugHandler( state )
-        {
-            private int count = 0;
-            private boolean hasSoftAbort;
+                private int count = 0;
+                private boolean hasSoftAbort;
 
-            @Override
-            public void onInstruction( DebugState ds, DebugFrame di, int pc, Varargs extras, int top ) throws LuaError
-            {
-                int count = ++this.count;
-                if( count > 100000 )
+                @Override
+                public void onInstruction( DebugState ds, DebugFrame di, int pc, Varargs extras, int top ) throws LuaError
                 {
-                    if( m_hardAbortMessage != null ) LuaThread.yield( state, NONE );
-                    this.count = 0;
+                    int count = ++this.count;
+                    if( count > 100000 )
+                    {
+                        if( m_hardAbortMessage != null ) LuaThread.yield( m_state, NONE );
+                        this.count = 0;
+                    }
+                    else
+                    {
+                        handleSoftAbort();
+                    }
+
+                    super.onInstruction( ds, di, pc, extras, top );
                 }
-                else
+
+                @Override
+                public void poll() throws LuaError
                 {
+                    if( m_hardAbortMessage != null ) LuaThread.yield( m_state, NONE );
                     handleSoftAbort();
                 }
 
-                super.onInstruction( ds, di, pc, extras, top );
-            }
+                private void handleSoftAbort() throws LuaError
+                {
+                    // If the soft abort has been cleared then we can reset our flags and continue.
+                    String message = m_softAbortMessage;
+                    if( message == null )
+                    {
+                        hasSoftAbort = false;
+                        return;
+                    }
 
-            @Override
-            public void poll() throws LuaError
-            {
-                if( m_hardAbortMessage != null ) LuaThread.yield( state, NONE );
-                handleSoftAbort();
-            }
+                    if( hasSoftAbort && m_hardAbortMessage == null )
+                    {
+                        // If we have fired our soft abort, but we haven't been hard aborted then everything is OK.
+                        return;
+                    }
 
-            private void handleSoftAbort() throws LuaError {
-                // If the soft abort has been cleared then we can reset our flags and continue.
-                String message = m_softAbortMessage;
-                if (message == null) {
-                    hasSoftAbort = false;
-                    return;
+                    hasSoftAbort = true;
+                    throw new LuaError( message );
                 }
-
-                if (hasSoftAbort && m_hardAbortMessage == null) {
-                    // If we have fired our soft abort, but we haven't been hard aborted then everything is OK.
-                    return;
-                }
-
-                hasSoftAbort = true;
-                throw new LuaError(message);
-            }
-        };
+            } )
+            .coroutineFactory( command -> {
+                Tracking.addValue( m_computer, TrackingField.COROUTINES_CREATED, 1 );
+                coroutines.execute( () -> {
+                    try
+                    {
+                        command.run();
+                    }
+                    finally
+                    {
+                        Tracking.addValue( m_computer, TrackingField.COROUTINES_DISPOSED, 1 );
+                    }
+                } );
+            } )
+            .build();
 
         m_globals = new LuaTable();
         state.setupThread( m_globals );
@@ -166,10 +186,7 @@ public class CobaltLuaMachine implements ILuaMachine
     public void loadBios( InputStream bios )
     {
         // Begin executing a file (ie, the bios)
-        if( m_mainRoutine != null )
-        {
-            return;
-        }
+        if( m_mainRoutine != null ) return;
 
         try
         {
@@ -178,30 +195,19 @@ public class CobaltLuaMachine implements ILuaMachine
         }
         catch( CompileException e )
         {
-            if( m_mainRoutine != null )
-            {
-                m_mainRoutine.abandon();
-                m_mainRoutine = null;
-            }
+            unload();
         }
         catch( IOException e )
         {
             ComputerCraft.log.warn( "Could not load bios.lua ", e );
-            if( m_mainRoutine != null )
-            {
-                m_mainRoutine.abandon();
-                m_mainRoutine = null;
-            }
+            unload();
         }
     }
 
     @Override
     public void handleEvent( String eventName, Object[] arguments )
     {
-        if( m_mainRoutine == null )
-        {
-            return;
-        }
+        if( m_mainRoutine == null ) return;
 
         if( m_eventFilter != null && eventName != null && !eventName.equals( m_eventFilter ) && !eventName.equals( "terminate" ) )
         {
@@ -228,26 +234,14 @@ public class CobaltLuaMachine implements ILuaMachine
             else
             {
                 LuaValue filter = results.arg( 2 );
-                if( filter.isString() )
-                {
-                    m_eventFilter = filter.toString();
-                }
-                else
-                {
-                    m_eventFilter = null;
-                }
+                m_eventFilter = filter.isString() ? filter.toString() : null;
             }
 
-            LuaThread mainThread = m_mainRoutine;
-            if( mainThread.getStatus().equals( "dead" ) )
-            {
-                m_mainRoutine = null;
-            }
+            if( m_mainRoutine.getStatus().equals( "dead" ) ) unload();
         }
         catch( LuaError e )
         {
-            m_mainRoutine.abandon();
-            m_mainRoutine = null;
+            unload();
         }
         finally
         {
@@ -284,18 +278,18 @@ public class CobaltLuaMachine implements ILuaMachine
     @Override
     public boolean isFinished()
     {
-        return (m_mainRoutine == null);
+        return m_mainRoutine == null;
     }
 
     @Override
     public void unload()
     {
-        if( m_mainRoutine != null )
-        {
-            LuaThread mainThread = m_mainRoutine;
-            mainThread.abandon();
-            m_mainRoutine = null;
-        }
+        if( m_state == null ) return;
+
+        m_state.abandon();
+        m_mainRoutine = null;
+        m_state = null;
+        m_globals = null;
     }
 
     private LuaTable wrapLuaObject( ILuaObject object )
@@ -691,7 +685,7 @@ public class CobaltLuaMachine implements ILuaMachine
         private byte[] bytes;
         private int offset, remaining = 0;
 
-        public StringInputStream( LuaState state, LuaValue func )
+        StringInputStream( LuaState state, LuaValue func )
         {
             this.state = state;
             this.func = func;

src/main/java/dan200/computercraft/core/tracking/ComputerTracker.java

@@ -1,7 +1,7 @@
 package dan200.computercraft.core.tracking;
 
 import dan200.computercraft.core.computer.Computer;
-import gnu.trove.map.hash.TObjectLongHashMap;
+import it.unimi.dsi.fastutil.objects.Object2LongOpenHashMap;
 
 import javax.annotation.Nullable;
 import java.lang.ref.WeakReference;
@@ -18,13 +18,13 @@ public class ComputerTracker
     private long serverCount;
     private long serverTime;
 
-    private final TObjectLongHashMap<TrackingField> fields;
+    private final Object2LongOpenHashMap<TrackingField> fields;
 
     public ComputerTracker( Computer computer )
     {
         this.computer = new WeakReference<>( computer );
         this.computerId = computer.getID();
-        this.fields = new TObjectLongHashMap<>();
+        this.fields = new Object2LongOpenHashMap<>();
     }
 
     ComputerTracker( ComputerTracker timings )
@@ -39,7 +39,7 @@ public class ComputerTracker
         this.serverCount = timings.serverCount;
         this.serverTime = timings.serverTime;
 
-        this.fields = new TObjectLongHashMap<>( timings.fields );
+        this.fields = new Object2LongOpenHashMap<>( timings.fields );
     }
 
     @Nullable
@@ -90,7 +90,7 @@ public class ComputerTracker
     {
         synchronized( fields )
         {
-            fields.adjustOrPutValue( field, change, change );
+            fields.addTo( field, change );
         }
     }
 
@@ -106,7 +106,7 @@ public class ComputerTracker
 
         synchronized( fields )
         {
-            return fields.get( field );
+            return fields.getLong( field );
         }
     }
 

src/main/java/dan200/computercraft/core/tracking/TrackingField.java

@@ -28,6 +28,9 @@ public class TrackingField
     public static final TrackingField WEBSOCKET_INCOMING = TrackingField.of( "websocket_incoming", "Websocket incoming", TrackingField::formatBytes );
     public static final TrackingField WEBSOCKET_OUTGOING = TrackingField.of( "websocket_outgoing", "Websocket outgoing", TrackingField::formatBytes );
 
+    public static final TrackingField COROUTINES_CREATED = TrackingField.of( "coroutines_created", "Coroutines created", x -> String.format( "%4d", x ) );
+    public static final TrackingField COROUTINES_DISPOSED = TrackingField.of( "coroutines_dead", "Coroutines disposed", x -> String.format( "%4d", x ) );
+
     private final String id;
     private final String displayName;
     private final LongFunction<String> format;

src/main/java/dan200/computercraft/shared/datafix/Fixes.java

@@ -0,0 +1,23 @@
+/*
+ * This file is part of ComputerCraft - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2018. Do not distribute without permission.
+ * Send enquiries to dratcliffe@gmail.com
+ */
+
+package dan200.computercraft.shared.datafix;
+
+import dan200.computercraft.ComputerCraft;
+import net.minecraft.util.datafix.FixTypes;
+import net.minecraftforge.common.util.CompoundDataFixer;
+import net.minecraftforge.common.util.ModFixs;
+
+public class Fixes
+{
+    public static final int VERSION = 1;
+
+    public static void register( CompoundDataFixer fixer )
+    {
+        ModFixs fixes = fixer.init( ComputerCraft.MOD_ID, VERSION );
+        fixes.registerFix( FixTypes.BLOCK_ENTITY, new TileEntityDataFixer() );
+    }
+}

src/main/java/dan200/computercraft/shared/datafix/TileEntityDataFixer.java

@@ -0,0 +1,39 @@
+/*
+ * This file is part of ComputerCraft - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2018. Do not distribute without permission.
+ * Send enquiries to dratcliffe@gmail.com
+ */
+
+package dan200.computercraft.shared.datafix;
+
+import net.minecraft.nbt.NBTTagCompound;
+import net.minecraft.util.datafix.IFixableData;
+
+import javax.annotation.Nonnull;
+
+import static dan200.computercraft.ComputerCraft.MOD_ID;
+import static dan200.computercraft.shared.datafix.Fixes.VERSION;
+
+/**
+ * Fixes up the botched tile entity IDs from the 1.11 port.
+ */
+public class TileEntityDataFixer implements IFixableData
+{
+    @Override
+    public int getFixVersion()
+    {
+        return VERSION;
+    }
+
+    @Nonnull
+    @Override
+    public NBTTagCompound fixTagCompound( @Nonnull NBTTagCompound tag )
+    {
+        String id = tag.getString( "id" );
+        if( id.startsWith( MOD_ID + " : " ) )
+        {
+            tag.setString( "id", id.replaceFirst( MOD_ID + " : ", MOD_ID + ":" ) );
+        }
+        return tag;
+    }
+}

src/main/java/dan200/computercraft/shared/integration/charset/BundledCapabilityProvider.java

@@ -69,7 +69,6 @@ final class BundledCapabilityProvider implements ICapabilityProvider
                     emitter = emitters[index] = () -> toBytes( tile.getBundledRedstoneOutput( side ) );
                 }
             }
-            ;
 
             return CAPABILITY_EMITTER.cast( emitter );
         }

src/main/java/dan200/computercraft/shared/peripheral/modem/ModemPeripheral.java

@@ -14,53 +14,43 @@ import dan200.computercraft.api.network.IPacketSender;
 import dan200.computercraft.api.network.Packet;
 import dan200.computercraft.api.peripheral.IComputerAccess;
 import dan200.computercraft.api.peripheral.IPeripheral;
-import gnu.trove.set.TIntSet;
-import gnu.trove.set.hash.TIntHashSet;
 import net.minecraft.util.math.Vec3d;
 import net.minecraft.world.World;
 
 import javax.annotation.Nonnull;
+import java.util.HashSet;
+import java.util.Set;
 
 import static dan200.computercraft.core.apis.ArgumentHelper.getInt;
 
-public abstract class ModemPeripheral
-    implements IPeripheral, IPacketSender, IPacketReceiver
+public abstract class ModemPeripheral implements IPeripheral, IPacketSender, IPacketReceiver
 {
     private IPacketNetwork m_network;
-    private IComputerAccess m_computer;
-    private final TIntSet m_channels;
+    private final Set<IComputerAccess> m_computers = new HashSet<>( 1 );
+    private final ModemState m_state;
 
-    private boolean m_open;
-    private boolean m_changed;
-
-    public ModemPeripheral()
+    protected ModemPeripheral( ModemState state )
     {
-        m_network = null;
-        m_computer = null;
-        m_channels = new TIntHashSet();
-        m_open = false;
-        m_changed = true;
+        this.m_state = state;
+    }
+
+    public ModemState getModemState()
+    {
+        return m_state;
     }
 
     private synchronized void setNetwork( IPacketNetwork network )
     {
-        if( m_network != network )
-        {
-            // Leave old network
-            if( m_network != null )
-            {
-                m_network.removeReceiver( this );
-            }
+        if( m_network == network ) return;
 
-            // Set new network
-            m_network = network;
+        // Leave old network
+        if( m_network != null ) m_network.removeReceiver( this );
 
-            // Join new network
-            if( m_network != null )
-            {
-                m_network.addReceiver( this );
-            }
-        }
+        // Set new network
+        m_network = network;
+
+        // Join new network
+        if( m_network != null ) m_network.addReceiver( this );
     }
 
     protected void switchNetwork()
@@ -68,39 +58,22 @@ public abstract class ModemPeripheral
         setNetwork( getNetwork() );
     }
 
-    public synchronized void destroy()
+    public void destroy()
     {
         setNetwork( null );
-        m_channels.clear();
-        m_open = false;
-    }
-    
-    public boolean pollChanged()
-    {
-        if( m_changed )
-        {
-            m_changed = false;
-            return true;
-        }
-        return false;
-    }
-
-    public boolean isActive()
-    {
-        return m_computer != null && m_open;
     }
 
     @Override
     public void receiveSameDimension( @Nonnull Packet packet, double distance )
     {
-        if( packet.getSender() == this ) return;
+        if( packet.getSender() == this || !m_state.isOpen( packet.getChannel() ) ) return;
 
-        synchronized (m_channels)
+        synchronized( m_computers )
         {
-            if( m_computer != null && m_channels.contains( packet.getChannel() ) )
+            for( IComputerAccess computer : m_computers )
             {
-                m_computer.queueEvent( "modem_message", new Object[] {
-                    m_computer.getAttachmentName(), packet.getChannel(), packet.getReplyChannel(), packet.getPayload(), distance
+                computer.queueEvent( "modem_message", new Object[]{
+                    computer.getAttachmentName(), packet.getChannel(), packet.getReplyChannel(), packet.getPayload(), distance
                 } );
             }
         }
@@ -109,21 +82,21 @@ public abstract class ModemPeripheral
     @Override
     public void receiveDifferentDimension( @Nonnull Packet packet )
     {
-        if( packet.getSender() == this ) return;
+        if( packet.getSender() == this || !m_state.isOpen( packet.getChannel() ) ) return;
 
-        synchronized (m_channels)
+        synchronized( m_computers )
         {
-            if( m_computer != null && m_channels.contains( packet.getChannel() ) )
+            for( IComputerAccess computer : m_computers )
             {
-                m_computer.queueEvent( "modem_message", new Object[] {
-                    m_computer.getAttachmentName(), packet.getChannel(), packet.getReplyChannel(), packet.getPayload()
+                computer.queueEvent( "modem_message", new Object[]{
+                    computer.getAttachmentName(), packet.getChannel(), packet.getReplyChannel(), packet.getPayload()
                 } );
             }
         }
     }
 
     protected abstract IPacketNetwork getNetwork();
-    
+
     // IPeripheral implementation
 
     @Nonnull
@@ -132,12 +105,12 @@ public abstract class ModemPeripheral
     {
         return "modem";
     }
-       
+
     @Nonnull
     @Override
     public String[] getMethodNames()
     {
-        return new String[] {
+        return new String[]{
             "open",
             "isOpen",
             "close",
@@ -146,7 +119,7 @@ public abstract class ModemPeripheral
             "isWireless",
         };
     }
-    
+
     private static int parseChannel( Object[] arguments, int index ) throws LuaException
     {
         int channel = getInt( arguments, index );
@@ -156,7 +129,7 @@ public abstract class ModemPeripheral
         }
         return channel;
     }
-    
+
     @Override
     public Object[] callMethod( @Nonnull IComputerAccess computer, @Nonnull ILuaContext context, int method, @Nonnull Object[] arguments ) throws LuaException, InterruptedException
     {
@@ -166,68 +139,26 @@ public abstract class ModemPeripheral
             {
                 // open
                 int channel = parseChannel( arguments, 0 );
-                synchronized( this )
-                {
-                    if( !m_channels.contains( channel ) )
-                    {
-                        if( m_channels.size() >= 128 )
-                        {
-                            throw new LuaException( "Too many open channels" );
-                        }
-
-                        m_channels.add( channel );
-                        if( !m_open )
-                        {
-                            m_open = true;
-                            m_changed = true;
-                        }
-                    }
-                }
+                m_state.open( channel );
                 return null;
             }
             case 1:
             {
                 // isOpen
                 int channel = parseChannel( arguments, 0 );
-                synchronized( this )
-                {
-                    boolean open = m_channels.contains( channel );
-                    return new Object[] { open };
-                }
+                return new Object[]{ m_state.isOpen( channel ) };
             }
             case 2:
             {
                 // close
                 int channel = parseChannel( arguments, 0 );
-                synchronized( this )
-                {
-                    if( m_channels.remove( channel ) )
-                    {
-                        if( m_channels.size() == 0 )
-                        {
-                            m_open = false;
-                            m_changed = true;
-                        }
-                    }
-                }
+                m_state.close( channel );
                 return null;
             }
             case 3:
             {
                 // closeAll
-                synchronized( this )
-                {
-                    if( m_channels.size() > 0 )
-                    {
-                        m_channels.clear();
-                        
-                        if( m_open )
-                        {
-                            m_open = false;
-                            m_changed = true;
-                        }
-                    }
-                }
+                m_state.closeAll();
                 return null;
             }
             case 4:
@@ -235,12 +166,12 @@ public abstract class ModemPeripheral
                 // transmit
                 int channel = parseChannel( arguments, 0 );
                 int replyChannel = parseChannel( arguments, 1 );
-                Object payload = (arguments.length >= 3) ? arguments[2] : null;
+                Object payload = arguments.length > 2 ? arguments[2] : null;
                 synchronized( this )
                 {
                     World world = getWorld();
                     Vec3d position = getPosition();
-                    if( world != null && position != null && m_network != null)
+                    if( world != null && position != null && m_network != null )
                     {
                         Packet packet = new Packet( channel, replyChannel, payload, this );
                         if( isInterdimensional() )
@@ -258,14 +189,8 @@ public abstract class ModemPeripheral
             case 5:
             {
                 // isWireless
-                synchronized( this )
-                {
-                    if( m_network != null )
-                    {
-                        return new Object[] { m_network.isWireless() };
-                    }
-                }
-                return new Object[] { false };
+                IPacketNetwork network = m_network;
+                return new Object[]{ network != null && network.isWireless() };
             }
             default:
             {
@@ -273,50 +198,46 @@ public abstract class ModemPeripheral
             }
         }
     }
-    
+
     @Override
     public synchronized void attach( @Nonnull IComputerAccess computer )
     {
-        m_computer = computer;
+        synchronized( m_computers )
+        {
+            m_computers.add( computer );
+        }
+
         setNetwork( getNetwork() );
-        m_open = !m_channels.isEmpty();
     }
-    
+
     @Override
     public synchronized void detach( @Nonnull IComputerAccess computer )
     {
-        if( m_network != null )
+        boolean empty;
+        synchronized( m_computers )
         {
-            m_network.removeReceiver( this );
-            m_channels.clear();
-            m_network = null;
+            m_computers.remove( computer );
+            empty = m_computers.isEmpty();
         }
 
-        m_computer = null;
-            
-        if( m_open )
-        {
-            m_open = false;        
-            m_changed = true;
-        }
-    }
-
-    public IComputerAccess getComputer()
-    {
-        return m_computer;
+        if( empty ) setNetwork( null );
     }
 
     @Nonnull
     @Override
     public String getSenderID()
     {
-        if( m_computer == null )
+        synchronized( m_computers )
         {
-            return "unknown";
-        }
-        else
-        {
-            return m_computer.getID() + "_" + m_computer.getAttachmentName();
+            if( m_computers.size() != 1 )
+            {
+                return "unknown";
+            }
+            else
+            {
+                IComputerAccess computer = m_computers.iterator().next();
+                return computer.getID() + "_" + computer.getAttachmentName();
+            }
         }
     }
 }

src/main/java/dan200/computercraft/shared/peripheral/modem/ModemState.java

@@ -0,0 +1,77 @@
+/*
+ * This file is part of ComputerCraft - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2018. Do not distribute without permission.
+ * Send enquiries to dratcliffe@gmail.com
+ */
+
+package dan200.computercraft.shared.peripheral.modem;
+
+import dan200.computercraft.api.lua.LuaException;
+import it.unimi.dsi.fastutil.ints.IntOpenHashSet;
+import it.unimi.dsi.fastutil.ints.IntSet;
+
+import java.util.concurrent.atomic.AtomicBoolean;
+
+public class ModemState
+{
+    private boolean open = false;
+    private AtomicBoolean changed = new AtomicBoolean( true );
+
+    private final IntSet channels = new IntOpenHashSet();
+
+    private void setOpen( boolean open )
+    {
+        if( this.open == open ) return;
+        this.open = open;
+        this.changed.set( true );
+    }
+
+    public boolean pollChanged()
+    {
+        return changed.getAndSet( false );
+    }
+
+    public boolean isOpen()
+    {
+        return open;
+    }
+
+    public boolean isOpen( int channel )
+    {
+        synchronized( channels )
+        {
+            return channels.contains( channel );
+        }
+    }
+
+    public void open( int channel ) throws LuaException
+    {
+        synchronized( channels )
+        {
+            if( !channels.contains( channel ) )
+            {
+                if( channels.size() >= 128 ) throw new LuaException( "Too many open channels" );
+                channels.add( channel );
+                setOpen( true );
+            }
+        }
+    }
+
+    public void close( int channel )
+    {
+        synchronized( channels )
+        {
+            channels.remove( channel );
+            if( channels.isEmpty() ) setOpen( false );
+        }
+    }
+
+    public void closeAll()
+    {
+        synchronized( channels )
+        {
+            channels.clear();
+            setOpen( false );
+        }
+    }
+}

src/main/java/dan200/computercraft/shared/peripheral/modem/TileAdvancedModem.java

@@ -25,7 +25,7 @@ public class TileAdvancedModem extends TileModemBase
 
         public Peripheral( TileModemBase entity )
         {
-            super( true );
+            super( new ModemState(), true );
             m_entity = entity;
         }
 

src/main/java/dan200/computercraft/shared/peripheral/modem/TileCable.java

@@ -97,7 +97,7 @@ public class TileCable extends TileModemBase
 
     private boolean m_hasDirection = false;
     private boolean m_connectionsFormed = false;
-
+    
     private WiredModemElement m_cable;
     private IWiredNode m_node;
 
@@ -106,7 +106,7 @@ public class TileCable extends TileModemBase
     {
         m_cable = new CableElement( this );
         m_node = m_cable.getNode();
-        return new WiredModemPeripheral( m_cable )
+        return new WiredModemPeripheral( new ModemState(), m_cable )
         {
             @Nonnull
             @Override
@@ -453,14 +453,8 @@ public class TileCable extends TileModemBase
     protected void updateAnim()
     {
         int anim = 0;
-        if( m_modem.isActive() )
-        {
-            anim += 1;
-        }
-        if( m_peripheralAccessAllowed )
-        {
-            anim += 2;
-        }
+        if( m_modem.getModemState().isOpen() ) anim |= 1;
+        if( m_peripheralAccessAllowed ) anim |= 2;
         setAnim( anim );
     }
 

src/main/java/dan200/computercraft/shared/peripheral/modem/TileModemBase.java

@@ -56,10 +56,7 @@ public abstract class TileModemBase extends TilePeripheralBase
     public void onNeighbourChange()
     {
         EnumFacing dir = getDirection();
-        if( !getWorld().isSideSolid(
-            getPos().offset( dir ),
-            dir.getOpposite()
-        ) )
+        if( !getWorld().isSideSolid( getPos().offset( dir ), dir.getOpposite() ) )
         {
             // Drop everything and remove block
             ((BlockGeneric)getBlockType()).dropAllItems( getWorld(), getPos(), false );
@@ -79,22 +76,15 @@ public abstract class TileModemBase extends TilePeripheralBase
     public void update()
     {
         super.update();
-        if( !getWorld().isRemote && m_modem.pollChanged() )
+        if( !getWorld().isRemote && m_modem.getModemState().pollChanged() )
         {
             updateAnim();
         }
     }
-    
+
     protected void updateAnim()
     {
-        if( m_modem.isActive() )
-        {
-            setAnim(1);
-        }
-        else
-        {
-            setAnim(0);
-        }
+        setAnim( m_modem.getModemState().isOpen() ? 1 : 0 );
     }
 
     @Override
@@ -109,15 +99,6 @@ public abstract class TileModemBase extends TilePeripheralBase
     @Override
     public IPeripheral getPeripheral( EnumFacing side )
     {
-        if( side == getDirection() )
-        {
-            return m_modem;
-        }
-        return null;
-    }
-
-    protected boolean isAttached()
-    {
-        return (m_modem != null) && (m_modem.getComputer() != null);
+        return side == getDirection() ? m_modem : null;
     }
 }

src/main/java/dan200/computercraft/shared/peripheral/modem/TileWiredModemFull.java

@@ -83,6 +83,7 @@ public class TileWiredModemFull extends TilePeripheralBase
     private boolean m_destroyed = false;
     private boolean m_connectionsFormed = false;
 
+    private final ModemState m_modemState = new ModemState();
     private final WiredModemElement m_element = new FullElement( this );
     private final IWiredNode m_node = m_element.getNode();
 
@@ -236,19 +237,8 @@ public class TileWiredModemFull extends TilePeripheralBase
     protected void updateAnim()
     {
         int anim = 0;
-        for( WiredModemPeripheral modem : m_modems )
-        {
-            if( modem != null && modem.isActive() )
-            {
-                anim += 1;
-                break;
-            }
-        }
-
-        if( m_peripheralAccessAllowed )
-        {
-            anim += 2;
-        }
+        if( m_modemState.isOpen() ) anim |= 1;
+        if( m_peripheralAccessAllowed ) anim |= 2;
         setAnim( anim );
     }
 
@@ -264,12 +254,7 @@ public class TileWiredModemFull extends TilePeripheralBase
     {
         if( !getWorld().isRemote )
         {
-            boolean changed = false;
-            for( WiredModemPeripheral peripheral : m_modems )
-            {
-                if( peripheral != null && peripheral.pollChanged() ) changed = true;
-            }
-            if( changed ) updateAnim();
+            if( m_modemState.pollChanged() ) updateAnim();
 
             if( !m_connectionsFormed )
             {
@@ -402,7 +387,7 @@ public class TileWiredModemFull extends TilePeripheralBase
         if( peripheral == null )
         {
             WiredModemLocalPeripheral localPeripheral = m_peripherals[side.ordinal()];
-            peripheral = m_modems[side.ordinal()] = new WiredModemPeripheral( m_element )
+            peripheral = m_modems[side.ordinal()] = new WiredModemPeripheral( m_modemState, m_element )
             {
                 @Nonnull
                 @Override

src/main/java/dan200/computercraft/shared/peripheral/modem/TileWirelessModem.java

@@ -29,7 +29,7 @@ public class TileWirelessModem extends TileModemBase
 
         public Peripheral( TileModemBase entity )
         {
-            super( false );
+            super( new ModemState(), false );
             m_entity = entity;
         }
 

src/main/java/dan200/computercraft/shared/peripheral/modem/WiredModemPeripheral.java

@@ -18,6 +18,8 @@ import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
 
 import static dan200.computercraft.core.apis.ArgumentHelper.getString;
 
@@ -25,10 +27,11 @@ public abstract class WiredModemPeripheral extends ModemPeripheral implements IW
 {
     private final WiredModemElement modem;
 
-    private final Map<String, RemotePeripheralWrapper> peripheralWrappers = new HashMap<>();
+    private final Map<IComputerAccess, ConcurrentMap<String, RemotePeripheralWrapper>> peripheralWrappers = new HashMap<>( 1 );
 
-    public WiredModemPeripheral( WiredModemElement modem )
+    public WiredModemPeripheral( ModemState state, WiredModemElement modem )
     {
+        super( state );
         this.modem = modem;
     }
 
@@ -88,56 +91,54 @@ public abstract class WiredModemPeripheral extends ModemPeripheral implements IW
             case 0:
             {
                 // getNamesRemote
-                synchronized( peripheralWrappers )
+                Map<String, RemotePeripheralWrapper> wrappers = getWrappers( computer );
+                Map<Object, Object> table = new HashMap<>();
+                if( wrappers != null )
                 {
                     int idx = 1;
-                    Map<Object, Object> table = new HashMap<>();
-                    for( String name : peripheralWrappers.keySet() )
-                    {
-                        table.put( idx++, name );
-                    }
-                    return new Object[]{ table };
+                    for( String name : wrappers.keySet() ) table.put( idx++, name );
                 }
+                return new Object[]{ table };
             }
             case 1:
             {
                 // isPresentRemote
-                String type = getTypeRemote( getString( arguments, 0 ) );
-                return new Object[]{ type != null };
+                String name = getString( arguments, 0 );
+                return new Object[]{ getWrapper( computer, name ) != null };
             }
             case 2:
             {
                 // getTypeRemote
-                String type = getTypeRemote( getString( arguments, 0 ) );
-                if( type != null )
-                {
-                    return new Object[]{ type };
-                }
-                return null;
+                String name = getString( arguments, 0 );
+                RemotePeripheralWrapper wrapper = getWrapper( computer, name );
+                return wrapper != null ? new Object[]{ wrapper.getType() } : null;
             }
             case 3:
             {
                 // getMethodsRemote
-                String[] methodNames = getMethodNamesRemote( getString( arguments, 0 ) );
-                if( methodNames != null )
+                String name = getString( arguments, 0 );
+                RemotePeripheralWrapper wrapper = getWrapper( computer, name );
+                if( wrapper == null ) return null;
+
+                String[] methodNames = wrapper.getMethodNames();
+                Map<Object, Object> table = new HashMap<>();
+                for( int i = 0; i < methodNames.length; ++i )
                 {
-                    Map<Object, Object> table = new HashMap<>();
-                    for( int i = 0; i < methodNames.length; ++i )
-                    {
-                        table.put( i + 1, methodNames[i] );
-                    }
-                    return new Object[]{ table };
+                    table.put( i + 1, methodNames[i] );
                 }
-                return null;
+                return new Object[]{ table };
             }
             case 4:
             {
                 // callRemote
                 String remoteName = getString( arguments, 0 );
                 String methodName = getString( arguments, 1 );
+                RemotePeripheralWrapper wrapper = getWrapper( computer, remoteName );
+                if( wrapper == null ) throw new LuaException( "No peripheral: " + remoteName );
+
                 Object[] methodArgs = new Object[arguments.length - 2];
                 System.arraycopy( arguments, 2, methodArgs, 0, arguments.length - 2 );
-                return callMethodRemote( remoteName, context, methodName, methodArgs );
+                return wrapper.callMethod( context, methodName, methodArgs );
             }
             case 5:
             {
@@ -157,29 +158,37 @@ public abstract class WiredModemPeripheral extends ModemPeripheral implements IW
     public void attach( @Nonnull IComputerAccess computer )
     {
         super.attach( computer );
+
+        ConcurrentMap<String, RemotePeripheralWrapper> wrappers;
+        synchronized( peripheralWrappers )
+        {
+            wrappers = peripheralWrappers.get( computer );
+            if( wrappers == null ) peripheralWrappers.put( computer, wrappers = new ConcurrentHashMap<>() ); 
+        }
+        
         synchronized( modem.getRemotePeripherals() )
         {
-            synchronized( peripheralWrappers )
+            for( Map.Entry<String, IPeripheral> entry : modem.getRemotePeripherals().entrySet() )
             {
-                for( Map.Entry<String, IPeripheral> entry : modem.getRemotePeripherals().entrySet() )
-                {
-                    attachPeripheralImpl( entry.getKey(), entry.getValue() );
-                }
+                attachPeripheralImpl( computer, wrappers, entry.getKey(), entry.getValue() );
             }
         }
     }
 
     @Override
-    public synchronized void detach( @Nonnull IComputerAccess computer )
+    public void detach( @Nonnull IComputerAccess computer )
     {
+        Map<String, RemotePeripheralWrapper> wrappers;
         synchronized( peripheralWrappers )
         {
-            for( RemotePeripheralWrapper wrapper : peripheralWrappers.values() )
-            {
-                wrapper.detach();
-            }
-            peripheralWrappers.clear();
+            wrappers = peripheralWrappers.remove( computer );
         }
+        if( wrappers != null )
+        {
+            for( RemotePeripheralWrapper wrapper : wrappers.values() ) wrapper.detach();
+            wrappers.clear();
+        }
+
         super.detach( computer );
     }
 
@@ -204,11 +213,12 @@ public abstract class WiredModemPeripheral extends ModemPeripheral implements IW
 
     public void attachPeripheral( String name, IPeripheral peripheral )
     {
-        if( getComputer() == null ) return;
-
         synchronized( peripheralWrappers )
         {
-            attachPeripheralImpl( name, peripheral );
+            for( Map.Entry<IComputerAccess, ConcurrentMap<String, RemotePeripheralWrapper>> entry : peripheralWrappers.entrySet() )
+            {
+                attachPeripheralImpl( entry.getKey(), entry.getValue(), name, peripheral );
+            }
         }
     }
 
@@ -216,63 +226,35 @@ public abstract class WiredModemPeripheral extends ModemPeripheral implements IW
     {
         synchronized( peripheralWrappers )
         {
-            RemotePeripheralWrapper wrapper = peripheralWrappers.get( name );
-            if( wrapper != null )
-            {
-                peripheralWrappers.remove( name );
-                wrapper.detach();
+            for(ConcurrentMap<String, RemotePeripheralWrapper> wrappers : peripheralWrappers.values()) {
+                RemotePeripheralWrapper wrapper = wrappers.remove( name );
+                if( wrapper != null ) wrapper.detach();
             }
+            
         }
     }
 
-    private void attachPeripheralImpl( String periphName, IPeripheral peripheral )
+    private void attachPeripheralImpl( IComputerAccess computer, ConcurrentMap<String, RemotePeripheralWrapper> peripherals, String periphName, IPeripheral peripheral )
     {
-        if( !peripheralWrappers.containsKey( periphName ) && !periphName.equals( getLocalPeripheral().getConnectedName() ) )
+        if( !peripherals.containsKey( periphName ) && !periphName.equals( getLocalPeripheral().getConnectedName() ) )
         {
-            RemotePeripheralWrapper wrapper = new RemotePeripheralWrapper( modem, peripheral, getComputer(), periphName );
-            peripheralWrappers.put( periphName, wrapper );
+            RemotePeripheralWrapper wrapper = new RemotePeripheralWrapper( modem, peripheral, computer, periphName );
+            peripherals.put( periphName, wrapper );
             wrapper.attach();
         }
     }
-
-    private String getTypeRemote( String remoteName )
-    {
+    
+    private ConcurrentMap<String, RemotePeripheralWrapper> getWrappers( IComputerAccess computer ) {
         synchronized( peripheralWrappers )
         {
-            RemotePeripheralWrapper wrapper = peripheralWrappers.get( remoteName );
-            if( wrapper != null )
-            {
-                return wrapper.getType();
-            }
+            return peripheralWrappers.get( computer );
         }
-        return null;
     }
 
-    private String[] getMethodNamesRemote( String remoteName )
+    private RemotePeripheralWrapper getWrapper( IComputerAccess computer, String remoteName )
     {
-        synchronized( peripheralWrappers )
-        {
-            RemotePeripheralWrapper wrapper = peripheralWrappers.get( remoteName );
-            if( wrapper != null )
-            {
-                return wrapper.getMethodNames();
-            }
-        }
-        return null;
-    }
-
-    private Object[] callMethodRemote( String remoteName, ILuaContext context, String method, Object[] arguments ) throws LuaException, InterruptedException
-    {
-        RemotePeripheralWrapper wrapper;
-        synchronized( peripheralWrappers )
-        {
-            wrapper = peripheralWrappers.get( remoteName );
-        }
-        if( wrapper != null )
-        {
-            return wrapper.callMethod( context, method, arguments );
-        }
-        throw new LuaException( "No peripheral: " + remoteName );
+        ConcurrentMap<String, RemotePeripheralWrapper> wrappers = getWrappers( computer );
+        return wrappers == null ? null : wrappers.get( remoteName );
     }
 
     private static class RemotePeripheralWrapper implements IComputerAccess, IComputerOwned

src/main/java/dan200/computercraft/shared/peripheral/modem/WirelessModemPeripheral.java

@@ -15,9 +15,16 @@ public abstract class WirelessModemPeripheral extends ModemPeripheral
 {
     private boolean m_advanced;
 
+    public WirelessModemPeripheral( ModemState state, boolean advanced )
+    {
+        super( state );
+        m_advanced = advanced;
+    }
+
+    @Deprecated
     public WirelessModemPeripheral( boolean advanced )
     {
-        m_advanced = advanced;
+        this( new ModemState(), advanced );
     }
 
     @Override

src/main/java/dan200/computercraft/shared/peripheral/modem/WirelessNetwork.java

@@ -13,8 +13,9 @@ import dan200.computercraft.api.network.IPacketSender;
 import dan200.computercraft.api.network.Packet;
 
 import javax.annotation.Nonnull;
-import java.util.HashSet;
+import java.util.Collections;
 import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
 
 public class WirelessNetwork implements IPacketNetwork
 {
@@ -34,45 +35,34 @@ public class WirelessNetwork implements IPacketNetwork
         s_universalNetwork = null;
     }
 
-    private final Set<IPacketReceiver> m_receivers;
-
-    private WirelessNetwork()
-    {
-        m_receivers = new HashSet<>();
-    }
+    private final Set<IPacketReceiver> m_receivers = Collections.newSetFromMap( new ConcurrentHashMap<>() );
 
     @Override
-    public synchronized void addReceiver( @Nonnull IPacketReceiver receiver )
+    public void addReceiver( @Nonnull IPacketReceiver receiver )
     {
         Preconditions.checkNotNull( receiver, "device cannot be null" );
         m_receivers.add( receiver );
     }
 
     @Override
-    public synchronized void removeReceiver( @Nonnull IPacketReceiver receiver )
+    public void removeReceiver( @Nonnull IPacketReceiver receiver )
     {
         Preconditions.checkNotNull( receiver, "device cannot be null" );
         m_receivers.remove( receiver );
     }
 
     @Override
-    public synchronized void transmitSameDimension( @Nonnull Packet packet, double range )
+    public void transmitSameDimension( @Nonnull Packet packet, double range )
     {
         Preconditions.checkNotNull( packet, "packet cannot be null" );
-        for( IPacketReceiver device : m_receivers )
-        {
-            tryTransmit( device, packet, range, false );
-        }
+        for( IPacketReceiver device : m_receivers ) tryTransmit( device, packet, range, false );
     }
 
     @Override
-    public synchronized void transmitInterdimensional( @Nonnull Packet packet )
+    public void transmitInterdimensional( @Nonnull Packet packet )
     {
         Preconditions.checkNotNull( packet, "packet cannot be null" );
-        for (IPacketReceiver device : m_receivers)
-        {
-            tryTransmit( device, packet, 0, true );
-        }
+        for( IPacketReceiver device : m_receivers ) tryTransmit( device, packet, 0, true );
     }
 
     private void tryTransmit( IPacketReceiver receiver, Packet packet, double range, boolean interdimensional )

src/main/java/dan200/computercraft/shared/pocket/peripherals/PocketModem.java

@@ -5,6 +5,7 @@ import dan200.computercraft.api.pocket.IPocketAccess;
 import dan200.computercraft.api.pocket.IPocketUpgrade;
 import dan200.computercraft.shared.peripheral.PeripheralType;
 import dan200.computercraft.shared.peripheral.common.PeripheralItemFactory;
+import dan200.computercraft.shared.peripheral.modem.ModemState;
 import net.minecraft.entity.Entity;
 import net.minecraft.entity.EntityLivingBase;
 import net.minecraft.item.ItemStack;
@@ -75,7 +76,8 @@ public class PocketModem implements IPocketUpgrade
                 modem.setLocation( entity.getEntityWorld(), entity.posX, entity.posY, entity.posZ );
             }
 
-            access.setLight( modem.isActive() ? 0xBA0000 : -1 );
+            ModemState state = modem.getModemState();
+            if( state.pollChanged() ) access.setLight( state.isOpen() ? 0xBA0000 : -1 );
         }
     }
 }

src/main/java/dan200/computercraft/shared/pocket/peripherals/PocketModemPeripheral.java

@@ -6,6 +6,7 @@
 package dan200.computercraft.shared.pocket.peripherals;
 
 import dan200.computercraft.api.peripheral.IPeripheral;
+import dan200.computercraft.shared.peripheral.modem.ModemState;
 import dan200.computercraft.shared.peripheral.modem.WirelessModemPeripheral;
 import net.minecraft.util.math.Vec3d;
 import net.minecraft.world.World;
@@ -19,7 +20,7 @@ public class PocketModemPeripheral extends WirelessModemPeripheral
 
     public PocketModemPeripheral( boolean advanced )
     {
-        super( advanced );
+        super( new ModemState(), advanced );
         m_world = null;
         m_position = new Vec3d( 0.0, 0.0, 0.0 );
     }

src/main/java/dan200/computercraft/shared/proxy/CCTurtleProxyCommon.java

@@ -469,9 +469,9 @@ public abstract class CCTurtleProxyCommon implements ICCTurtleProxy
     private void registerTileEntities()
     {
         // TileEntities
-        GameRegistry.registerTileEntity( TileTurtle.class, ComputerCraft.LOWER_ID + " : " + "turtle" );
-        GameRegistry.registerTileEntity( TileTurtleExpanded.class, ComputerCraft.LOWER_ID + " : " + "turtleex" );
-        GameRegistry.registerTileEntity( TileTurtleAdvanced.class, ComputerCraft.LOWER_ID + " : " + "turtleadv" );
+        GameRegistry.registerTileEntity( TileTurtle.class, new ResourceLocation( ComputerCraft.MOD_ID, "turtle" ) );
+        GameRegistry.registerTileEntity( TileTurtleExpanded.class, new ResourceLocation( ComputerCraft.MOD_ID, "turtleex" ) );
+        GameRegistry.registerTileEntity( TileTurtleAdvanced.class, new ResourceLocation( ComputerCraft.MOD_ID, "turtleadv" ) );
     }
 
     private void registerForgeHandlers()

src/main/java/dan200/computercraft/shared/proxy/ComputerCraftProxyCommon.java

@@ -24,6 +24,7 @@ import dan200.computercraft.shared.computer.core.*;
 import dan200.computercraft.shared.computer.inventory.ContainerComputer;
 import dan200.computercraft.shared.computer.items.ItemCommandComputer;
 import dan200.computercraft.shared.computer.items.ItemComputer;
+import dan200.computercraft.shared.datafix.Fixes;
 import dan200.computercraft.shared.integration.charset.IntegrationCharset;
 import dan200.computercraft.shared.media.common.DefaultMediaProvider;
 import dan200.computercraft.shared.media.inventory.ContainerHeldItem;
@@ -77,6 +78,7 @@ import net.minecraftforge.event.RegistryEvent;
 import net.minecraftforge.event.entity.player.PlayerContainerEvent;
 import net.minecraftforge.event.world.WorldEvent;
 import net.minecraftforge.fml.client.event.ConfigChangedEvent;
+import net.minecraftforge.fml.common.FMLCommonHandler;
 import net.minecraftforge.fml.common.Loader;
 import net.minecraftforge.fml.common.eventhandler.SubscribeEvent;
 import net.minecraftforge.fml.common.gameevent.TickEvent;
@@ -121,6 +123,7 @@ public abstract class ComputerCraftProxyCommon implements IComputerCraftProxy
         registerTileEntities();
         registerForgeHandlers();
 
+        Fixes.register( FMLCommonHandler.instance().getDataFixer() );
         if( Loader.isModLoaded( ModCharset.MODID ) ) IntegrationCharset.register();
     }
 
@@ -478,16 +481,16 @@ public abstract class ComputerCraftProxyCommon implements IComputerCraftProxy
     private void registerTileEntities()
     {
         // Tile Entities
-        GameRegistry.registerTileEntity( TileComputer.class, ComputerCraft.LOWER_ID + " : " + "computer" );
-        GameRegistry.registerTileEntity( TileDiskDrive.class, ComputerCraft.LOWER_ID + " : " + "diskdrive" );
-        GameRegistry.registerTileEntity( TileWirelessModem.class, ComputerCraft.LOWER_ID + " : " + "wirelessmodem" );
-        GameRegistry.registerTileEntity( TileMonitor.class, ComputerCraft.LOWER_ID + " : " + "monitor" );
-        GameRegistry.registerTileEntity( TilePrinter.class, ComputerCraft.LOWER_ID + " : " + "ccprinter" );
-        GameRegistry.registerTileEntity( TileCable.class, ComputerCraft.LOWER_ID + " : " + "wiredmodem" );
-        GameRegistry.registerTileEntity( TileCommandComputer.class, ComputerCraft.LOWER_ID + " : " + "command_computer" );
-        GameRegistry.registerTileEntity( TileAdvancedModem.class, ComputerCraft.LOWER_ID + " : " + "advanced_modem" );
-        GameRegistry.registerTileEntity( TileSpeaker.class, ComputerCraft.LOWER_ID + " : " + "speaker" );
-        GameRegistry.registerTileEntity( TileWiredModemFull.class, ComputerCraft.LOWER_ID + " : " + "wired_modem_full" );
+        GameRegistry.registerTileEntity( TileComputer.class, new ResourceLocation( ComputerCraft.MOD_ID, "computer" ) );
+        GameRegistry.registerTileEntity( TileDiskDrive.class, new ResourceLocation( ComputerCraft.MOD_ID, "diskdrive" ) );
+        GameRegistry.registerTileEntity( TileWirelessModem.class, new ResourceLocation( ComputerCraft.MOD_ID, "wirelessmodem" ) );
+        GameRegistry.registerTileEntity( TileMonitor.class, new ResourceLocation( ComputerCraft.MOD_ID, "monitor" ) );
+        GameRegistry.registerTileEntity( TilePrinter.class, new ResourceLocation( ComputerCraft.MOD_ID, "ccprinter" ) );
+        GameRegistry.registerTileEntity( TileCable.class, new ResourceLocation( ComputerCraft.MOD_ID, "wiredmodem" ) );
+        GameRegistry.registerTileEntity( TileCommandComputer.class, new ResourceLocation( ComputerCraft.MOD_ID, "command_computer" ) );
+        GameRegistry.registerTileEntity( TileAdvancedModem.class, new ResourceLocation( ComputerCraft.MOD_ID, "advanced_modem" ) );
+        GameRegistry.registerTileEntity( TileSpeaker.class, new ResourceLocation( ComputerCraft.MOD_ID, "speaker" ) );
+        GameRegistry.registerTileEntity( TileWiredModemFull.class, new ResourceLocation( ComputerCraft.MOD_ID, "wired_modem_full" ) );
 
         // Register peripheral providers
         ComputerCraftAPI.registerPeripheralProvider( new DefaultPeripheralProvider() );

src/main/java/dan200/computercraft/shared/turtle/upgrades/TurtleModem.java

@@ -10,6 +10,7 @@ import dan200.computercraft.api.peripheral.IPeripheral;
 import dan200.computercraft.api.turtle.*;
 import dan200.computercraft.shared.peripheral.PeripheralType;
 import dan200.computercraft.shared.peripheral.common.PeripheralItemFactory;
+import dan200.computercraft.shared.peripheral.modem.ModemState;
 import dan200.computercraft.shared.peripheral.modem.WirelessModemPeripheral;
 import net.minecraft.client.Minecraft;
 import net.minecraft.client.renderer.block.model.IBakedModel;
@@ -17,9 +18,9 @@ import net.minecraft.client.renderer.block.model.ModelManager;
 import net.minecraft.client.renderer.block.model.ModelResourceLocation;
 import net.minecraft.item.ItemStack;
 import net.minecraft.nbt.NBTTagCompound;
-import net.minecraft.util.math.BlockPos;
 import net.minecraft.util.EnumFacing;
 import net.minecraft.util.ResourceLocation;
+import net.minecraft.util.math.BlockPos;
 import net.minecraft.util.math.Vec3d;
 import net.minecraft.world.World;
 import net.minecraftforge.fml.relauncher.Side;
@@ -37,7 +38,7 @@ public class TurtleModem implements ITurtleUpgrade
 
         public Peripheral( ITurtleAccess turtle, boolean advanced )
         {
-            super( advanced );
+            super( new ModemState(), advanced );
             m_turtle = turtle;
         }
 
@@ -221,12 +222,12 @@ public class TurtleModem implements ITurtleUpgrade
         if( !turtle.getWorld().isRemote )
         {
             IPeripheral peripheral = turtle.getPeripheral( side );
-            if( peripheral != null && peripheral instanceof Peripheral )
+            if( peripheral instanceof Peripheral )
             {
-                Peripheral modemPeripheral = (Peripheral)peripheral;
-                if( modemPeripheral.pollChanged() )
+                ModemState state = ((Peripheral) peripheral).getModemState();
+                if( state.pollChanged() )
                 {
-                    turtle.getUpgradeNBTData( side ).setBoolean( "active", modemPeripheral.isActive() );
+                    turtle.getUpgradeNBTData( side ).setBoolean( "active", state.isOpen() );
                     turtle.updateUpgradeNBTData( side );
                 }
             }

src/main/java/dan200/computercraft/shared/util/ThreadUtils.java

@@ -0,0 +1,78 @@
+/*
+ * This file is part of ComputerCraft - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2018. Do not distribute without permission.
+ * Send enquiries to dratcliffe@gmail.com
+ */
+
+package dan200.computercraft.shared.util;
+
+import com.google.common.util.concurrent.ThreadFactoryBuilder;
+
+import java.util.concurrent.ThreadFactory;
+
+/**
+ * Provides some utilities to create thread groups
+ */
+public final class ThreadUtils
+{
+    private static final ThreadGroup baseGroup = new ThreadGroup( "ComputerCraft" );
+
+    private ThreadUtils()
+    {
+    }
+
+    /**
+     * Get the base thread group, that all off-thread ComputerCraft activities are run on.
+     *
+     * @return The ComputerCraft group.
+     */
+    public static ThreadGroup group()
+    {
+        return baseGroup;
+    }
+
+    /**
+     * Construct a group under ComputerCraft's shared group
+     *
+     * @param name The group's name. This will be prefixed with "ComputerCraft-".
+     * @return The constructed thread group.
+     */
+    public static ThreadGroup group( String name )
+    {
+        return new ThreadGroup( baseGroup, baseGroup.getName() + "-" + name );
+    }
+
+    /**
+     * Create a new {@link ThreadFactoryBuilder}, which constructs threads under a group of the given {@code name}.
+     *
+     * Each thread will be of the format {@code ComputerCraft-<name>-<number>}, and belong to a group
+     * called {@code ComputerCraft-<name>} (which in turn will be a child group of the main {@code ComputerCraft} group.
+     *
+     * @param name The name for the thread group and child threads.
+     * @return The constructed thread factory builder, which may be extended with other properties.
+     * @see #factory(String)
+     */
+    public static ThreadFactoryBuilder builder( String name )
+    {
+        ThreadGroup group = group( name );
+        return new ThreadFactoryBuilder()
+            .setDaemon( true )
+            .setNameFormat( group.getName().replace( "%", "%%" ) + "-%d" )
+            .setThreadFactory( x -> new Thread( group, x ) );
+    }
+
+    /**
+     * Create a new {@link ThreadFactory}, which constructs threads under a group of the given {@code name}.
+     *
+     * Each thread will be of the format {@code ComputerCraft-<name>-<number>}, and belong to a group
+     * called {@code ComputerCraft-<name>} (which in turn will be a child group of the main {@code ComputerCraft} group.
+     *
+     * @param name The name for the thread group and child threads.
+     * @return The constructed thread factory.
+     * @see #builder(String)
+     */
+    public static ThreadFactory factory( String name )
+    {
+        return builder( name ).build();
+    }
+}

src/main/resources/assets/computercraft/lua/rom/apis/io.lua

@@ -63,7 +63,7 @@ handleMetatable = {
             if self._closed then error("attempt to use a closed file", 2) end
 
             local handle = self._handle
-            if not handle.read then return nil, "Not opened for reading" end
+            if not handle.read and not handle.readLine then return nil, "Not opened for reading" end
 
             local n = select('#', ...)
             local output = {}

src/test/java/dan200/computercraft/core/FileSystemTest.java

@@ -0,0 +1,58 @@
+/*
+ * This file is part of ComputerCraft - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2018. Do not distribute without permission.
+ * Send enquiries to dratcliffe@gmail.com
+ */
+
+package dan200.computercraft.core;
+
+import com.google.common.io.Files;
+import dan200.computercraft.api.filesystem.IWritableMount;
+import dan200.computercraft.api.lua.LuaException;
+import dan200.computercraft.core.apis.ObjectWrapper;
+import dan200.computercraft.core.apis.handles.EncodedWritableHandle;
+import dan200.computercraft.core.filesystem.FileMount;
+import dan200.computercraft.core.filesystem.FileSystem;
+import dan200.computercraft.core.filesystem.FileSystemException;
+import dan200.computercraft.core.filesystem.FileSystemWrapper;
+import org.junit.Test;
+
+import java.io.BufferedWriter;
+import java.io.File;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+
+import static org.junit.Assert.assertEquals;
+
+public class FileSystemTest
+{
+    private static final File ROOT = new File( "test-files/filesystem" );
+
+    /**
+     * Ensures writing a file truncates it.
+     */
+    @Test
+    public void testWriteTruncates() throws FileSystemException, LuaException, IOException
+    {
+        IWritableMount writableMount = new FileMount( ROOT, 1000000 );
+        FileSystem fs = new FileSystem( "hdd", writableMount );
+
+        {
+            FileSystemWrapper<BufferedWriter> writer = fs.openForWrite( "out.txt", false, EncodedWritableHandle::openUtf8 );
+            ObjectWrapper wrapper = new ObjectWrapper( new EncodedWritableHandle( writer.get(), writer ) );
+            wrapper.call( "write", "This is a long line" );
+            wrapper.call( "close" );
+        }
+
+        assertEquals( "This is a long line", Files.toString( new File( ROOT, "out.txt" ), StandardCharsets.UTF_8 ) );
+
+        {
+            FileSystemWrapper<BufferedWriter> writer = fs.openForWrite( "out.txt", false, EncodedWritableHandle::openUtf8 );
+            ObjectWrapper wrapper = new ObjectWrapper( new EncodedWritableHandle( writer.get(), writer ) );
+            wrapper.call( "write", "Tiny line" );
+            wrapper.call( "close" );
+        }
+
+        assertEquals( "Tiny line", Files.toString( new File( ROOT, "out.txt" ), StandardCharsets.UTF_8 ) );
+    }
+}

src/test/java/dan200/computercraft/core/apis/ObjectWrapper.java

@@ -0,0 +1,90 @@
+/*
+ * This file is part of ComputerCraft - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2018. Do not distribute without permission.
+ * Send enquiries to dratcliffe@gmail.com
+ */
+
+package dan200.computercraft.core.apis;
+
+import dan200.computercraft.api.lua.ILuaContext;
+import dan200.computercraft.api.lua.ILuaObject;
+import dan200.computercraft.api.lua.ILuaTask;
+import dan200.computercraft.api.lua.LuaException;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
+public class ObjectWrapper implements ILuaContext
+{
+    private final ILuaObject object;
+    private final String[] methods;
+
+    public ObjectWrapper( ILuaObject object )
+    {
+        this.object = object;
+        this.methods = object.getMethodNames();
+    }
+
+    private int findMethod( String method )
+    {
+        for( int i = 0; i < methods.length; i++ )
+        {
+            if( method.equals( methods[i] ) ) return i;
+        }
+        return -1;
+    }
+
+    public boolean hasMethod( String method )
+    {
+        return findMethod( method ) >= 0;
+    }
+
+    public Object[] call( String name, Object... args ) throws LuaException
+    {
+        int method = findMethod( name );
+        if( method < 0 ) throw new IllegalStateException( "No such method '" + name + "'" );
+
+        try
+        {
+            return object.callMethod( this, method, args );
+        }
+        catch( InterruptedException e )
+        {
+            throw new IllegalStateException( "Should never be interrupted", e );
+        }
+    }
+
+    @Nonnull
+    @Override
+    public Object[] pullEvent( @Nullable String filter )
+    {
+        throw new IllegalStateException( "Method should never yield" );
+    }
+
+    @Nonnull
+    @Override
+    public Object[] pullEventRaw( @Nullable String filter )
+    {
+        throw new IllegalStateException( "Method should never yield" );
+    }
+
+    @Nonnull
+    @Override
+    public Object[] yield( @Nullable Object[] arguments )
+    {
+        throw new IllegalStateException( "Method should never yield" );
+    }
+
+    @Nullable
+    @Override
+    public Object[] executeMainThreadTask( @Nonnull ILuaTask task )
+    {
+        throw new IllegalStateException( "Method should never yield" );
+    }
+
+    @Override
+    public long issueMainThreadTask( @Nonnull ILuaTask task )
+    {
+        throw new IllegalStateException( "Method should never queue events" );
+    }
+}