Require computers to have a fixed ID

Moves ID assigning out of the Computer class and into wherever we
construct the ServerComputer (so in computer blocks and pocket computer
items).

This is definitely not perfect - it'd be nice to make ServerComputers
more responsible for managing the lifecycle of computers (so assigning
ids, handling auto-starting, etc...), but I've not found a good way to
handle this yet!

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

@@ -32,7 +32,7 @@ public class Computer
     private static final int START_DELAY = 50;
 
     // Various properties of the computer
-    private int id;
+    private final int id;
     private String label = null;
 
     // Read-only fields about the computer
@@ -51,6 +51,7 @@ public class Computer
 
     public Computer( IComputerEnvironment environment, Terminal terminal, int id )
     {
+        if( id < 0 ) throw new IllegalStateException( "Id has not been assigned" );
         this.id = id;
         this.environment = environment;
         this.terminal = terminal;
@@ -135,20 +136,6 @@ public class Computer
         return id;
     }
 
-    public int assignID()
-    {
-        if( id < 0 )
-        {
-            id = environment.assignNewID();
-        }
-        return id;
-    }
-
-    public void setID( int id )
-    {
-        this.id = id;
-    }
-
     public String getLabel()
     {
         return label;

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

@@ -345,13 +345,7 @@ final class ComputerExecutor
 
     private IWritableMount getRootMount()
     {
-        if( rootMount == null )
+        if( rootMount == null ) rootMount = computer.getComputerEnvironment().createRootMount();
-        {
-            rootMount = computer.getComputerEnvironment().createSaveDirMount(
-                "computer/" + computer.assignID(),
-                computer.getComputerEnvironment().getComputerSpaceLimit()
-            );
-        }
         return rootMount;
     }
 

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

@@ -68,7 +68,7 @@ public final class Environment implements IAPIEnvironment
     @Override
     public int getComputerID()
     {
-        return computer.assignID();
+        return computer.getID();
     }
 
     @Nonnull

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

@@ -18,18 +18,14 @@ public interface IComputerEnvironment
 
     double getTimeOfDay();
 
-    long getComputerSpaceLimit();
-
     @Nonnull
     String getHostString();
 
     @Nonnull
     String getUserAgent();
 
-    int assignNewID();
-
     @Nullable
-    IWritableMount createSaveDirMount( String subPath, long capacity );
+    IWritableMount createRootMount();
 
     @Nullable
     IMount createResourceMount( String domain, String subPath );

src/main/java/dan200/computercraft/shared/computer/blocks/ComputerPeripheral.java

@@ -74,7 +74,7 @@ public class ComputerPeripheral implements IPeripheral
     @LuaFunction
     public final int getID()
     {
-        return computer.assignID();
+        return computer.getID();
     }
 
     /**

src/main/java/dan200/computercraft/shared/computer/blocks/ComputerProxy.java

@@ -68,7 +68,7 @@ public final class ComputerProxy
         }
     }
 
-    public int assignID()
+    public int getID()
     {
         TileComputerBase tile = getTile();
         ServerComputer computer = tile.getServerComputer();

src/main/java/dan200/computercraft/shared/computer/blocks/TileComputerBase.java

@@ -5,6 +5,7 @@
  */
 package dan200.computercraft.shared.computer.blocks;
 
+import dan200.computercraft.api.ComputerCraftAPI;
 import dan200.computercraft.api.peripheral.IPeripheral;
 import dan200.computercraft.core.computer.ComputerSide;
 import dan200.computercraft.shared.BundledRedstone;
@@ -16,6 +17,7 @@ import dan200.computercraft.shared.computer.core.ServerComputer;
 import dan200.computercraft.shared.computer.core.ServerComputerRegistry;
 import dan200.computercraft.shared.network.container.ComputerContainerData;
 import dan200.computercraft.shared.util.DirectionUtil;
+import dan200.computercraft.shared.util.IDAssigner;
 import dan200.computercraft.shared.util.RedstoneUtil;
 import joptsimple.internal.Strings;
 import net.minecraft.block.BlockState;
@@ -167,6 +169,7 @@ public abstract class TileComputerBase extends TileGeneric implements IComputerT
     public void tick()
     {
         if( getLevel().isClientSide ) return;
+        if( computerID < 0 && !startOn ) return; // Don't tick if we don't need a computer!
 
         ServerComputer computer = createServerComputer();
 
@@ -348,8 +351,6 @@ public abstract class TileComputerBase extends TileGeneric implements IComputerT
         if( getLevel().isClientSide || computerID == id ) return;
 
         computerID = id;
-        ServerComputer computer = getServerComputer();
-        if( computer != null ) computer.setID( computerID );
         setChanged();
     }
 
@@ -371,7 +372,7 @@ public abstract class TileComputerBase extends TileGeneric implements IComputerT
     }
 
     @Nonnull
-    public ServerComputer createServerComputer()
+    public final ServerComputer createServerComputer()
     {
         if( getLevel().isClientSide ) throw new IllegalStateException( "Cannot access server computer on the client." );
 
@@ -380,6 +381,12 @@ public abstract class TileComputerBase extends TileGeneric implements IComputerT
         ServerComputer computer = ServerComputerRegistry.INSTANCE.get( instanceID );
         if( computer == null )
         {
+            if( computerID < 0 )
+            {
+                computerID = ComputerCraftAPI.createUniqueNumberedSaveDir( level, IDAssigner.COMPUTER );
+                updateBlock();
+            }
+
             computer = createComputer( computerID );
             instanceID = computer.register();
             fresh = true;

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

@@ -172,11 +172,6 @@ public class ServerComputer implements InputHandler, IComputerEnvironment
     {
     }
 
-    public void setID( int id )
-    {
-        computer.setID( id );
-    }
-
     public int getInstanceID()
     {
         return instanceID;
@@ -286,9 +281,9 @@ public class ServerComputer implements InputHandler, IComputerEnvironment
     }
 
     @Override
-    public IWritableMount createSaveDirMount( String subPath, long capacity )
+    public IWritableMount createRootMount()
     {
-        return ComputerCraftAPI.createSaveDirMount( world, subPath, capacity );
+        return ComputerCraftAPI.createSaveDirMount( world, "computer/" + computer.getID(), ComputerCraft.computerSpaceLimit );
     }
 
     @Override
@@ -303,12 +298,6 @@ public class ServerComputer implements InputHandler, IComputerEnvironment
         return ComputerCraftAPIImpl.getResourceFile( domain, subPath );
     }
 
-    @Override
-    public long getComputerSpaceLimit()
-    {
-        return ComputerCraft.computerSpaceLimit;
-    }
-
     @Nonnull
     @Override
     public String getHostString()
@@ -322,10 +311,4 @@ public class ServerComputer implements InputHandler, IComputerEnvironment
     {
         return ComputerCraft.MOD_ID + "/" + ComputerCraftAPI.getInstalledVersion();
     }
-
-    @Override
-    public int assignNewID()
-    {
-        return ComputerCraftAPI.createUniqueNumberedSaveDir( world, "computer" );
-    }
 }

src/main/java/dan200/computercraft/shared/pocket/items/ItemPocketComputer.java

@@ -21,6 +21,7 @@ import dan200.computercraft.shared.network.container.ComputerContainerData;
 import dan200.computercraft.shared.pocket.apis.PocketAPI;
 import dan200.computercraft.shared.pocket.core.PocketServerComputer;
 import dan200.computercraft.shared.pocket.inventory.PocketComputerMenuProvider;
+import dan200.computercraft.shared.util.IDAssigner;
 import net.minecraft.client.util.ITooltipFlag;
 import net.minecraft.entity.Entity;
 import net.minecraft.entity.item.ItemEntity;
@@ -233,7 +234,7 @@ public class ItemPocketComputer extends Item implements IComputerItem, IMedia, I
             int computerID = getComputerID( stack );
             if( computerID < 0 )
             {
-                computerID = ComputerCraftAPI.createUniqueNumberedSaveDir( world, "computer" );
+                computerID = ComputerCraftAPI.createUniqueNumberedSaveDir( world, IDAssigner.COMPUTER );
                 setComputerID( stack, computerID );
             }
 

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

@@ -26,6 +26,8 @@ import java.util.Map;
 
 public final class IDAssigner
 {
+    public static final String COMPUTER = "computer";
+
     private static final FolderName FOLDER = new FolderName( ComputerCraft.MOD_ID );
     private static final Gson GSON = new GsonBuilder().setPrettyPrinting().create();
     private static final Type ID_TOKEN = new TypeToken<Map<String, Integer>>()

src/test/java/dan200/computercraft/core/computer/BasicEnvironment.java

@@ -39,13 +39,7 @@ public class BasicEnvironment implements IComputerEnvironment
     }
 
     @Override
-    public int assignNewID()
+    public IWritableMount createRootMount()
-    {
-        return 0;
-    }
-
-    @Override
-    public IWritableMount createSaveDirMount( String path, long space )
     {
         return mount;
     }
@@ -62,12 +56,6 @@ public class BasicEnvironment implements IComputerEnvironment
         return 0;
     }
 
-    @Override
-    public long getComputerSpaceLimit()
-    {
-        return ComputerCraft.computerSpaceLimit;
-    }
-
     @Nonnull
     @Override
     public String getHostString()