Merge pull request #183 from SquidDev-CC/feature/thread-safe-inventories

src/main/java/dan200/computercraft/api/turtle/ITurtleAccess.java

@@ -145,7 +145,9 @@ public interface ITurtleAccess
     GameProfile getOwningPlayer();
 
     /**
-     * Get the inventory of this turtle
+     * Get the inventory of this turtle.
+     *
+     * Note: this inventory should only be accessed and modified on the server thread.
      *
      * @return This turtle's inventory
      * @see #getItemHandler()
@@ -156,6 +158,8 @@ public interface ITurtleAccess
     /**
      * Get the inventory of this turtle as an {@link IItemHandlerModifiable}.
      *
+     * Note: this inventory should only be accessed and modified on the server thread.
+     *
      * @return This turtle's inventory
      * @see #getInventory()
      * @see IItemHandlerModifiable

src/main/java/dan200/computercraft/shared/peripheral/diskdrive/DiskDrivePeripheral.java

@@ -11,6 +11,7 @@ import dan200.computercraft.api.lua.LuaException;
 import dan200.computercraft.api.media.IMedia;
 import dan200.computercraft.api.peripheral.IComputerAccess;
 import dan200.computercraft.api.peripheral.IPeripheral;
+import dan200.computercraft.shared.MediaProviders;
 import dan200.computercraft.shared.media.items.ItemDiskLegacy;
 import dan200.computercraft.shared.util.StringUtil;
 import net.minecraft.item.Item;
@@ -20,11 +21,11 @@ import javax.annotation.Nonnull;
 
 import static dan200.computercraft.core.apis.ArgumentHelper.optString;
 
-public class DiskDrivePeripheral implements IPeripheral
+class DiskDrivePeripheral implements IPeripheral
 {
     private final TileDiskDrive m_diskDrive;
 
-    public DiskDrivePeripheral( TileDiskDrive diskDrive )
+    DiskDrivePeripheral( TileDiskDrive diskDrive )
     {
         m_diskDrive = diskDrive;
     }
@@ -56,7 +57,7 @@ public class DiskDrivePeripheral implements IPeripheral
     }
 
     @Override
-    public Object[] callMethod( @Nonnull IComputerAccess computer, @Nonnull ILuaContext context, int method, @Nonnull Object[] arguments ) throws LuaException
+    public Object[] callMethod( @Nonnull IComputerAccess computer, @Nonnull ILuaContext context, int method, @Nonnull Object[] arguments ) throws LuaException, InterruptedException
     {
         switch( method )
         {
@@ -64,21 +65,26 @@ public class DiskDrivePeripheral implements IPeripheral
                 return new Object[] { !m_diskDrive.getDiskStack().isEmpty() };
             case 1: // getDiskLabel
             {
-                IMedia media = m_diskDrive.getDiskMedia();
-                return media == null ? null : new Object[] { media.getLabel( m_diskDrive.getDiskStack() ) };
+                ItemStack stack = m_diskDrive.getDiskStack();
+                IMedia media = MediaProviders.get( stack );
+                return media == null ? null : new Object[] { media.getLabel( stack ) };
             }
             case 2: // setDiskLabel
             {
                 String label = optString( arguments, 0, null );
 
-                IMedia media = m_diskDrive.getDiskMedia();
+                return context.executeMainThreadTask( () -> {
+                    ItemStack stack = m_diskDrive.getDiskStack();
+                    IMedia media = MediaProviders.get( stack );
                     if( media == null ) return null;
 
-                ItemStack disk = m_diskDrive.getDiskStack();
-                label = StringUtil.normaliseLabel( label );
-                if( !media.setLabel( disk, label ) ) throw new LuaException( "Disk label cannot be changed" );
-                m_diskDrive.setDiskStack( disk );
+                    if( !media.setLabel( stack, StringUtil.normaliseLabel( label ) ) )
+                    {
+                        throw new LuaException( "Disk label cannot be changed" );
+                    }
+                    m_diskDrive.setDiskStack( stack );
                     return null;
+                } );
             }
             case 3: // hasData
                 return new Object[] { m_diskDrive.getDiskMountPath( computer ) != null };
@@ -87,14 +93,16 @@ public class DiskDrivePeripheral implements IPeripheral
             case 5:
             {
                 // hasAudio
-                IMedia media = m_diskDrive.getDiskMedia();
-                return new Object[] { media != null && media.getAudio( m_diskDrive.getDiskStack() ) != null };
+                ItemStack stack = m_diskDrive.getDiskStack();
+                IMedia media = MediaProviders.get( stack );
+                return new Object[] { media != null && media.getAudio( stack ) != null };
             }
             case 6:
             {
                 // getAudioTitle
-                IMedia media = m_diskDrive.getDiskMedia();
-                return new Object[] { media != null ? media.getAudioTitle( m_diskDrive.getDiskStack() ) : false };
+                ItemStack stack = m_diskDrive.getDiskStack();
+                IMedia media = MediaProviders.get( stack );
+                return new Object[] { media != null ? media.getAudioTitle( stack ) : false };
             }
             case 7: // playAudio
                 m_diskDrive.playDiskAudio();
@@ -131,8 +139,7 @@ public class DiskDrivePeripheral implements IPeripheral
     @Override
     public boolean equals( IPeripheral other )
     {
-        if( this == other ) return true;
-        return other instanceof DiskDrivePeripheral && ((DiskDrivePeripheral) other).m_diskDrive == m_diskDrive;
+        return this == other || other instanceof DiskDrivePeripheral && ((DiskDrivePeripheral) other).m_diskDrive == m_diskDrive;
     }
 
     @Nonnull

src/main/java/dan200/computercraft/shared/peripheral/diskdrive/TileDiskDrive.java

@@ -318,35 +318,31 @@ public class TileDiskDrive extends TilePeripheralBase implements DefaultInventor
     }
 
     @Nonnull
-    public ItemStack getDiskStack()
+    ItemStack getDiskStack()
     {
         return getStackInSlot( 0 );
     }
 
-    public void setDiskStack( @Nonnull ItemStack stack )
+    void setDiskStack( @Nonnull ItemStack stack )
     {
         setInventorySlotContents( 0, stack );
     }
 
-    public IMedia getDiskMedia()
+    private IMedia getDiskMedia()
     {
         return MediaProviders.get( getDiskStack() );
     }
 
-    public String getDiskMountPath( IComputerAccess computer )
+    String getDiskMountPath( IComputerAccess computer )
     {
         synchronized( this )
-        {
-            if( m_computers.containsKey( computer ) )
         {
             MountInfo info = m_computers.get( computer );
-                return info.mountPath;
+            return info != null ? info.mountPath : null;
         }
     }
-        return null;
-    }
 
-    public void mount( IComputerAccess computer )
+    void mount( IComputerAccess computer )
     {
         synchronized( this )
         {
@@ -355,7 +351,7 @@ public class TileDiskDrive extends TilePeripheralBase implements DefaultInventor
         }
     }
 
-    public void unmount( IComputerAccess computer )
+    void unmount( IComputerAccess computer )
     {
         synchronized( this )
         {
@@ -364,7 +360,7 @@ public class TileDiskDrive extends TilePeripheralBase implements DefaultInventor
         }
     }
 
-    public void playDiskAudio()
+    void playDiskAudio()
     {
         synchronized( this )
         {
@@ -377,7 +373,7 @@ public class TileDiskDrive extends TilePeripheralBase implements DefaultInventor
         }
     }
 
-    public void stopDiskAudio()
+    void stopDiskAudio()
     {
         synchronized( this )
         {
@@ -386,7 +382,7 @@ public class TileDiskDrive extends TilePeripheralBase implements DefaultInventor
         }
     }
 
-    public void ejectDisk()
+    void ejectDisk()
     {
         synchronized( this )
         {

src/main/java/dan200/computercraft/shared/peripheral/printer/PrinterPeripheral.java

@@ -51,8 +51,13 @@ public class PrinterPeripheral implements IPeripheral
     }
 
     @Override
-    public Object[] callMethod( @Nonnull IComputerAccess computer, @Nonnull ILuaContext context, int method, @Nonnull Object[] args ) throws LuaException
+    public Object[] callMethod( @Nonnull IComputerAccess computer, @Nonnull ILuaContext context, int method, @Nonnull Object[] args ) throws LuaException, InterruptedException
     {
+        // FIXME: There's a theoretical race condition here between getCurrentPage and then using the page. Ideally
+        //  we'd lock on the page, consume it, and unlock.
+
+        // FIXME: None of our page modification functions actually mark the tile as dirty, so the page may not be
+        //  persisted correctly.
         switch( method )
         {
             case 0: // write
@@ -89,10 +94,13 @@ public class PrinterPeripheral implements IPeripheral
                 return new Object[] { width, height };
             }
             case 4: // newPage
-                return new Object[] { m_printer.startNewPage() };
+                return context.executeMainThreadTask( () -> new Object[] { m_printer.startNewPage() } );
             case 5: // endPage
+                getCurrentPage();
+                return context.executeMainThreadTask( () -> {
                     getCurrentPage();
                     return new Object[] { m_printer.endCurrentPage() };
+                } );
             case 6: // getInkLevel
                 return new Object[] { m_printer.getInkLevel() };
             case 7:
@@ -123,13 +131,11 @@ public class PrinterPeripheral implements IPeripheral
         return m_printer;
     }
 
+    @Nonnull
     private Terminal getCurrentPage() throws LuaException
     {
         Terminal currentPage = m_printer.getCurrentPage();
-        if( currentPage == null )
-        {
-            throw new LuaException( "Page not started" );
-        }
+        if( currentPage == null ) throw new LuaException( "Page not started" );
         return currentPage;
     }
 }

src/main/java/dan200/computercraft/shared/peripheral/printer/TilePrinter.java

@@ -45,9 +45,9 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
 {
     // Statics
 
-    private static final int[] bottomSlots = new int[] { 7, 8, 9, 10, 11, 12 };
-    private static final int[] topSlots = new int[] { 1, 2, 3, 4, 5, 6 };
-    private static final int[] sideSlots = new int[] { 0 };
+    private static final int[] BOTTOM_SLOTS = new int[] { 7, 8, 9, 10, 11, 12 };
+    private static final int[] TOP_SLOTS = new int[] { 1, 2, 3, 4, 5, 6 };
+    private static final int[] SIDE_SLOTS = new int[] { 0 };
 
     // Members
 
@@ -88,18 +88,12 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
         }
 
         // Read inventory
-        synchronized( m_inventory )
+        NBTTagList itemList = nbt.getTagList( "Items", Constants.NBT.TAG_COMPOUND );
+        for( int i = 0; i < itemList.tagCount(); i++ )
         {
-            NBTTagList nbttaglist = nbt.getTagList( "Items", Constants.NBT.TAG_COMPOUND );
-            for( int i = 0; i < nbttaglist.tagCount(); i++ )
-            {
-                NBTTagCompound itemTag = nbttaglist.getCompoundTagAt( i );
-                int j = itemTag.getByte( "Slot" ) & 0xff;
-                if( j < m_inventory.size() )
-                {
-                    m_inventory.set( j, new ItemStack( itemTag ) );
-                }
-            }
+            NBTTagCompound itemTag = itemList.getCompoundTagAt( i );
+            int slot = itemTag.getByte( "Slot" ) & 0xff;
+            if( slot < m_inventory.size() ) m_inventory.set( slot, new ItemStack( itemTag ) );
         }
     }
 
@@ -116,21 +110,18 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
         }
 
         // Write inventory
-        synchronized( m_inventory )
-        {
-            NBTTagList nbttaglist = new NBTTagList();
+        NBTTagList itemList = new NBTTagList();
         for( int i = 0; i < m_inventory.size(); i++ )
         {
-                if( !m_inventory.get( i ).isEmpty() )
-                {
+            ItemStack stack = m_inventory.get( i );
+            if( stack.isEmpty() ) continue;
+
             NBTTagCompound tag = new NBTTagCompound();
             tag.setByte( "Slot", (byte) i );
-                    m_inventory.get( i ).writeToNBT( tag );
-                    nbttaglist.appendTag( tag );
-                }
-            }
-            nbt.setTag( "Items", nbttaglist );
+            stack.writeToNBT( tag );
+            itemList.appendTag( tag );
         }
+        nbt.setTag( "Items", itemList );
 
         return super.writeToNBT( nbt );
     }
@@ -148,7 +139,7 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
         return super.shouldRefresh( world, pos, oldState, newState ) || BlockPeripheral.getPeripheralType( newState ) != PeripheralType.Printer;
     }
 
-    public boolean isPrinting()
+    boolean isPrinting()
     {
         return m_printing;
     }
@@ -173,74 +164,60 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
 
     @Nonnull
     @Override
-    public ItemStack getStackInSlot( int i )
+    public ItemStack getStackInSlot( int slot )
     {
-        return m_inventory.get( i );
+        return m_inventory.get( slot );
     }
 
     @Nonnull
     @Override
-    public ItemStack removeStackFromSlot( int i )
+    public ItemStack removeStackFromSlot( int slot )
     {
-        synchronized( m_inventory )
-        {
-            ItemStack result = m_inventory.get( i );
-            m_inventory.set( i, ItemStack.EMPTY );
+        ItemStack result = m_inventory.get( slot );
+        m_inventory.set( slot, ItemStack.EMPTY );
         markDirty();
         updateAnim();
         return result;
     }
-    }
 
     @Nonnull
     @Override
-    public ItemStack decrStackSize( int i, int j )
+    public ItemStack decrStackSize( int slot, int count )
     {
-        synchronized( m_inventory )
-        {
-            if( m_inventory.get( i ).isEmpty() ) return ItemStack.EMPTY;
+        ItemStack stack = m_inventory.get( slot );
+        if( stack.isEmpty() ) return ItemStack.EMPTY;
 
-            if( m_inventory.get( i ).getCount() <= j )
+        if( stack.getCount() <= count )
         {
-                ItemStack itemstack = m_inventory.get( i );
-                m_inventory.set( i, ItemStack.EMPTY );
-                markDirty();
-                updateAnim();
-                return itemstack;
+            setInventorySlotContents( slot, ItemStack.EMPTY );
+            return stack;
         }
 
-            ItemStack part = m_inventory.get( i ).splitStack( j );
-            if( m_inventory.get( i ).isEmpty() )
+        ItemStack part = stack.splitStack( count );
+        if( m_inventory.get( slot ).isEmpty() )
         {
-                m_inventory.set( i, ItemStack.EMPTY );
+            m_inventory.set( slot, ItemStack.EMPTY );
             updateAnim();
         }
         markDirty();
         return part;
     }
-    }
 
     @Override
-    public void setInventorySlotContents( int i, @Nonnull ItemStack stack )
+    public void setInventorySlotContents( int slot, @Nonnull ItemStack stack )
     {
-        synchronized( m_inventory )
-        {
-            m_inventory.set( i, stack );
+        m_inventory.set( slot, stack );
         markDirty();
         updateAnim();
     }
-    }
 
     @Override
     public void clear()
-    {
-        synchronized( m_inventory )
     {
         for( int i = 0; i < m_inventory.size(); i++ ) m_inventory.set( i, ItemStack.EMPTY );
         markDirty();
         updateAnim();
     }
-    }
 
     @Override
     public boolean isItemValidForSlot( int slot, @Nonnull ItemStack stack )
@@ -249,7 +226,7 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
         {
             return isInk( stack );
         }
-        else if( slot >= topSlots[0] && slot <= topSlots[topSlots.length - 1] )
+        else if( slot >= TOP_SLOTS[0] && slot <= TOP_SLOTS[TOP_SLOTS.length - 1] )
         {
             return isPaper( stack );
         }
@@ -295,11 +272,11 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
         switch( side )
         {
             case DOWN: // Bottom (Out tray)
-                return bottomSlots;
+                return BOTTOM_SLOTS;
             case UP: // Top (In tray)
-                return topSlots;
+                return TOP_SLOTS;
             default: // Sides (Ink)
-                return sideSlots;
+                return SIDE_SLOTS;
         }
     }
 
@@ -311,14 +288,18 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
         return new PrinterPeripheral( this );
     }
 
-    public Terminal getCurrentPage()
+    @Nullable
+    Terminal getCurrentPage()
+    {
+        synchronized( m_page )
         {
             return m_printing ? m_page : null;
         }
+    }
 
-    public boolean startNewPage()
+    boolean startNewPage()
     {
-        synchronized( m_inventory )
+        synchronized( m_page )
         {
             if( !canInputPage() ) return false;
             if( m_printing && !outputPage() ) return false;
@@ -326,49 +307,36 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
         }
     }
 
-    public boolean endCurrentPage()
+    boolean endCurrentPage()
     {
-        synchronized( m_inventory )
+        synchronized( m_page )
         {
-            if( m_printing && outputPage() )
-            {
-                return true;
+            return m_printing && outputPage();
         }
     }
-        return false;
-    }
 
-    public int getInkLevel()
-    {
-        synchronized( m_inventory )
+    int getInkLevel()
     {
         ItemStack inkStack = m_inventory.get( 0 );
         return isInk( inkStack ) ? inkStack.getCount() : 0;
     }
-    }
 
-    public int getPaperLevel()
+    int getPaperLevel()
     {
         int count = 0;
-        synchronized( m_inventory )
-        {
         for( int i = 1; i < 7; i++ )
         {
             ItemStack paperStack = m_inventory.get( i );
-                if( !paperStack.isEmpty() && isPaper( paperStack ) )
-                {
-                    count += paperStack.getCount();
-                }
-            }
+            if( isPaper( paperStack ) ) count += paperStack.getCount();
         }
         return count;
     }
 
-    public void setPageTitle( String title )
+    void setPageTitle( String title )
     {
-        if( m_printing )
+        synchronized( m_page )
         {
-            m_pageTitle = title;
+            if( m_printing ) m_pageTitle = title;
         }
     }
 
@@ -384,17 +352,12 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
     }
 
     private boolean canInputPage()
-    {
-        synchronized( m_inventory )
     {
         ItemStack inkStack = m_inventory.get( 0 );
         return !inkStack.isEmpty() && isInk( inkStack ) && getPaperLevel() > 0;
     }
-    }
 
     private boolean inputPage()
-    {
-        synchronized( m_inventory )
     {
         ItemStack inkStack = m_inventory.get( 0 );
         if( !isInk( inkStack ) ) return false;
@@ -402,8 +365,8 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
         for( int i = 1; i < 7; i++ )
         {
             ItemStack paperStack = m_inventory.get( i );
-                if( !paperStack.isEmpty() && isPaper( paperStack ) )
-                {
+            if( paperStack.isEmpty() || !isPaper( paperStack ) ) continue;
+
             // Setup the new page
             int colour = inkStack.getItemDamage();
             m_page.setTextColour( colour >= 0 && colour < 16 ? 15 - colour : 15 );
@@ -441,14 +404,10 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
             m_printing = true;
             return true;
         }
-            }
         return false;
     }
-    }
 
     private boolean outputPage()
-    {
-        synchronized( m_page )
     {
         int height = m_page.getHeight();
         String[] lines = new String[height];
@@ -460,9 +419,7 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
         }
 
         ItemStack stack = ItemPrintout.createSingleFromTitleAndText( m_pageTitle, lines, colours );
-            synchronized( m_inventory )
-            {
-                for( int slot : bottomSlots )
+        for( int slot : BOTTOM_SLOTS )
         {
             if( m_inventory.get( slot ).isEmpty() )
             {
@@ -471,14 +428,10 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
                 return true;
             }
         }
-            }
         return false;
     }
-    }
 
     private void ejectContents()
-    {
-        synchronized( m_inventory )
     {
         for( int i = 0; i < 13; i++ )
         {
@@ -497,11 +450,8 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
             }
         }
     }
-    }
 
     private void updateAnim()
-    {
-        synchronized( m_inventory )
     {
         int anim = 0;
         for( int i = 1; i < 7; i++ )
@@ -524,7 +474,6 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
         }
         setAnim( anim );
     }
-    }
 
     @Override
     public boolean hasCapability( @Nonnull Capability<?> capability, @Nullable EnumFacing facing )

src/main/java/dan200/computercraft/shared/turtle/apis/TurtleAPI.java

@@ -334,9 +334,11 @@ public class TurtleAPI implements ILuaAPI
                 return tryCommand( context, new TurtleInspectCommand( InteractDirection.Up ) );
             case 40: // inspectDown
                 return tryCommand( context, new TurtleInspectCommand( InteractDirection.Down ) );
-            case 41:
+            case 41: // getItemDetail
             {
-                // getItemDetail
+                // FIXME: There's a race condition here if the stack is being modified (mutating NBT, etc...)
+                //  on another thread. The obvious solution is to move this into a command, but some programs rely
+                //  on this having a 0-tick delay.
                 int slot = parseOptionalSlotNumber( args, 0, m_turtle.getSelectedSlot() );
                 ItemStack stack = m_turtle.getInventory().getStackInSlot( slot );
                 if( stack.isEmpty() ) return new Object[] { null };

src/main/java/dan200/computercraft/shared/turtle/blocks/TileTurtle.java

@@ -43,19 +43,16 @@ import net.minecraftforge.items.wrapper.InvWrapper;
 
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
+import java.util.Collections;
 
 import static net.minecraftforge.items.CapabilityItemHandler.ITEM_HANDLER_CAPABILITY;
 
 public class TileTurtle extends TileComputerBase implements ITurtleTile, DefaultInventory
 {
-    // Statics
-
     public static final int INVENTORY_SIZE = 16;
     public static final int INVENTORY_WIDTH = 4;
     public static final int INVENTORY_HEIGHT = 4;
 
-    // Members
-
     enum MoveState
     {
         NOT_MOVED,
@@ -63,12 +60,12 @@ public class TileTurtle extends TileComputerBase implements ITurtleTile, Default
         MOVED
     }
 
-    private NonNullList<ItemStack> m_inventory;
-    private NonNullList<ItemStack> m_previousInventory;
+    private final NonNullList<ItemStack> m_inventory = NonNullList.withSize( INVENTORY_SIZE, ItemStack.EMPTY );
+    private final NonNullList<ItemStack> m_previousInventory = NonNullList.withSize( INVENTORY_SIZE, ItemStack.EMPTY );
     private final IItemHandlerModifiable m_itemHandler = new InvWrapper( this );
-    private boolean m_inventoryChanged;
-    private TurtleBrain m_brain;
-    private MoveState m_moveState;
+    private boolean m_inventoryChanged = false;
+    private TurtleBrain m_brain = new TurtleBrain( this );
+    private MoveState m_moveState = MoveState.NOT_MOVED;
     private ComputerFamily m_family;
 
     public TileTurtle()
@@ -78,15 +75,10 @@ public class TileTurtle extends TileComputerBase implements ITurtleTile, Default
 
     public TileTurtle( ComputerFamily family )
     {
-        m_inventory = NonNullList.withSize( INVENTORY_SIZE, ItemStack.EMPTY );
-        m_previousInventory = NonNullList.withSize( INVENTORY_SIZE, ItemStack.EMPTY );
-        m_inventoryChanged = false;
-        m_brain = new TurtleBrain( this );
-        m_moveState = MoveState.NOT_MOVED;
         m_family = family;
     }
 
-    public boolean hasMoved()
+    private boolean hasMoved()
     {
         return m_moveState == MoveState.MOVED;
     }
@@ -224,8 +216,6 @@ public class TileTurtle extends TileComputerBase implements ITurtleTile, Default
     {
         super.update();
         m_brain.update();
-        synchronized( m_inventory )
-        {
         if( !getWorld().isRemote && m_inventoryChanged )
         {
             ServerComputer computer = getServerComputer();
@@ -238,7 +228,6 @@ public class TileTurtle extends TileComputerBase implements ITurtleTile, Default
             }
         }
     }
-    }
 
     @Override
     public void onNeighbourChange( @Nonnull BlockPos neighbour )
@@ -270,8 +259,8 @@ public class TileTurtle extends TileComputerBase implements ITurtleTile, Default
 
         // Read inventory
         NBTTagList nbttaglist = nbt.getTagList( "Items", Constants.NBT.TAG_COMPOUND );
-        m_inventory = NonNullList.withSize( INVENTORY_SIZE, ItemStack.EMPTY );
-        m_previousInventory = NonNullList.withSize( INVENTORY_SIZE, ItemStack.EMPTY );
+        m_inventory.clear();
+        m_previousInventory.clear();
         for( int i = 0; i < nbttaglist.tagCount(); i++ )
         {
             NBTTagCompound tag = nbttaglist.getCompoundTagAt( i );
@@ -382,7 +371,7 @@ public class TileTurtle extends TileComputerBase implements ITurtleTile, Default
         return m_family;
     }
 
-    public void setOwningPlayer( GameProfile player )
+    void setOwningPlayer( GameProfile player )
     {
         m_brain.setOwningPlayer( player );
         markDirty();
@@ -410,44 +399,26 @@ public class TileTurtle extends TileComputerBase implements ITurtleTile, Default
     @Override
     public ItemStack getStackInSlot( int slot )
     {
-        if( slot >= 0 && slot < INVENTORY_SIZE )
-        {
-            synchronized( m_inventory )
-            {
-                return m_inventory.get( slot );
-            }
-        }
-        return ItemStack.EMPTY;
+        return slot >= 0 && slot < INVENTORY_SIZE ? m_inventory.get( slot ) : ItemStack.EMPTY;
     }
 
     @Nonnull
     @Override
     public ItemStack removeStackFromSlot( int slot )
-    {
-        synchronized( m_inventory )
     {
         ItemStack result = getStackInSlot( slot );
         setInventorySlotContents( slot, ItemStack.EMPTY );
         return result;
     }
-    }
 
     @Nonnull
     @Override
     public ItemStack decrStackSize( int slot, int count )
     {
-        if( count == 0 )
-        {
-            return ItemStack.EMPTY;
-        }
+        if( count == 0 ) return ItemStack.EMPTY;
 
-        synchronized( m_inventory )
-        {
         ItemStack stack = getStackInSlot( slot );
-            if( stack.isEmpty() )
-            {
-                return ItemStack.EMPTY;
-            }
+        if( stack.isEmpty() ) return ItemStack.EMPTY;
 
         if( stack.getCount() <= count )
         {
@@ -459,28 +430,19 @@ public class TileTurtle extends TileComputerBase implements ITurtleTile, Default
         onInventoryDefinitelyChanged();
         return part;
     }
-    }
 
     @Override
     public void setInventorySlotContents( int i, @Nonnull ItemStack stack )
     {
-        if( i >= 0 && i < INVENTORY_SIZE )
-        {
-            synchronized( m_inventory )
-            {
-                if( !InventoryUtil.areItemsEqual( stack, m_inventory.get( i ) ) )
+        if( i >= 0 && i < INVENTORY_SIZE && !InventoryUtil.areItemsEqual( stack, m_inventory.get( i ) ) )
         {
             m_inventory.set( i, stack );
             onInventoryDefinitelyChanged();
         }
     }
-        }
-    }
 
     @Override
     public void clear()
-    {
-        synchronized( m_inventory )
     {
         boolean changed = false;
         for( int i = 0; i < INVENTORY_SIZE; i++ )
@@ -491,19 +453,14 @@ public class TileTurtle extends TileComputerBase implements ITurtleTile, Default
                 changed = true;
             }
         }
-            if( changed )
-            {
-                onInventoryDefinitelyChanged();
-            }
-        }
+
+        if( changed ) onInventoryDefinitelyChanged();
     }
 
     @Override
     public void markDirty()
     {
         super.markDirty();
-        synchronized( m_inventory )
-        {
         if( !m_inventoryChanged )
         {
             for( int n = 0; n < getSizeInventory(); n++ )
@@ -516,7 +473,6 @@ public class TileTurtle extends TileComputerBase implements ITurtleTile, Default
             }
         }
     }
-    }
 
     @Override
     public boolean isUsableByPlayer( @Nonnull EntityPlayer player )
@@ -574,8 +530,8 @@ public class TileTurtle extends TileComputerBase implements ITurtleTile, Default
     public void transferStateFrom( TileTurtle copy )
     {
         super.transferStateFrom( copy );
-        m_inventory = copy.m_inventory;
-        m_previousInventory = copy.m_previousInventory;
+        Collections.copy( m_inventory, copy.m_inventory );
+        Collections.copy( m_previousInventory, copy.m_previousInventory );
         m_inventoryChanged = copy.m_inventoryChanged;
         m_brain = copy.m_brain;
         m_brain.setOwner( this );

src/main/resources/assets/computercraft/lua/rom/programs/edit.lua

@@ -342,7 +342,6 @@ local tMenuFuncs = {
                 redrawMenu()
                 term.redirect( printerTerminal )
 
-                local timer = os.startTimer(0.5)
                 sleep(0.5)
             end