Add a basic implementation of the single-thread Lua

build.gradle

@@ -42,6 +42,7 @@ minecraft {
 }
 
 repositories {
+    mavenLocal()
     maven {
         name = "JEI"
         url  = "http://dvs1.progwml6.com/files/maven"
@@ -66,7 +67,7 @@ dependencies {
 
     runtime "mezz.jei:jei_1.12.2:4.8.5.159"
 
-    shade 'org.squiddev:Cobalt:0.3.2'
+    shade 'org.squiddev:Cobalt:0.3.2-nothread'
 
     testCompile 'junit:junit:4.11'
 

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

@@ -13,24 +13,28 @@ import dan200.computercraft.api.lua.LuaException;
 import dan200.computercraft.core.computer.Computer;
 import dan200.computercraft.core.computer.ITask;
 import dan200.computercraft.core.computer.MainThread;
+import org.squiddev.cobalt.LuaError;
 import org.squiddev.cobalt.LuaState;
 import org.squiddev.cobalt.LuaThread;
-import org.squiddev.cobalt.OrphanedThread;
-import org.squiddev.cobalt.Varargs;
 
 import javax.annotation.Nonnull;
+import java.lang.ref.WeakReference;
 
 class CobaltLuaContext implements ILuaContext
 {
-    private CobaltLuaMachine machine;
     private final Computer computer;
-    private final LuaState state;
 
-    public CobaltLuaContext( CobaltLuaMachine machine, Computer computer, LuaState state )
+    boolean done = false;
+    Object[] values;
+    LuaError exception;
+    final Semaphore yield = new Semaphore();
+    final Semaphore resume = new Semaphore();
+    private WeakReference<LuaThread> thread;
+
+    public CobaltLuaContext( Computer computer, LuaState state )
     {
-        this.machine = machine;
         this.computer = computer;
-        this.state = state;
+        this.thread = state.getCurrentThread().getReference();
     }
 
     @Nonnull
@@ -56,19 +60,19 @@ class CobaltLuaContext implements ILuaContext
     @Override
     public Object[] yield( Object[] yieldArgs ) throws InterruptedException
     {
-        try
+        if( done ) throw new IllegalStateException( "Cannot yield when complete" );
+
+        values = yieldArgs;
+        yield.signal();
+
+        // Every 30 seconds check to see if the coroutine has been GCed
+        // if so then abort this task.
+        while( !resume.await( 30000 ) )
         {
-            Varargs results = LuaThread.yield( state, machine.toValues( yieldArgs ) );
-            return CobaltLuaMachine.toObjects( results, 1 );
-        }
-        catch( OrphanedThread e )
-        {
-            throw new InterruptedException();
-        }
-        catch( Throwable e )
-        {
-            throw new RuntimeException( e );
+            if( thread.get() == null ) throw new InterruptedException( "Orphaned async task" );
         }
+
+        return values;
     }
 
     @Override
@@ -167,6 +171,5 @@ class CobaltLuaContext implements ILuaContext
                 }
             }
         }
-
     }
 }

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

@@ -70,7 +70,7 @@ public class CobaltLuaMachine implements ILuaMachine
                 int count = ++this.count;
                 if( count > 100000 )
                 {
-                    if( m_hardAbortMessage != null ) LuaThread.yield( state, NONE );
+                    if( m_hardAbortMessage != null ) throw new LuaError( m_hardAbortMessage );
                     this.count = 0;
                 }
                 else
@@ -84,7 +84,7 @@ public class CobaltLuaMachine implements ILuaMachine
             @Override
             public void poll() throws LuaError
             {
-                if( m_hardAbortMessage != null ) LuaThread.yield( state, NONE );
+                if( m_hardAbortMessage != null ) throw new LuaError( m_hardAbortMessage );
                 handleSoftAbort();
             }
 
@@ -119,7 +119,7 @@ public class CobaltLuaMachine implements ILuaMachine
         if( ComputerCraft.debug_enable ) m_globals.load( state, new DebugLib() );
 
         // Register custom load/loadstring provider which automatically adds prefixes.
-        LibFunction.bind( state, m_globals, PrefixLoader.class, new String[]{ "load", "loadstring" } );
+        LibFunction.bind( m_globals, PrefixLoader.class, new String[]{ "load", "loadstring" } );
 
         // Remove globals we don't want to expose
         m_globals.rawset( "collectgarbage", Constants.NIL );
@@ -210,18 +210,13 @@ public class CobaltLuaMachine implements ILuaMachine
                 resumeArgs = varargsOf( valueOf( eventName ), toValues( arguments ) );
             }
 
-            Varargs results = m_mainRoutine.resume( resumeArgs );
+            LuaValue filter = LuaThread.run( m_mainRoutine, resumeArgs ).first();
             if( m_hardAbortMessage != null )
             {
                 throw new LuaError( m_hardAbortMessage );
             }
-            else if( !results.first().checkBoolean() )
-            {
-                throw new LuaError( results.arg( 2 ).checkString() );
-            }
             else
             {
-                LuaValue filter = results.arg( 2 );
                 if( filter.isString() )
                 {
                     m_eventFilter = filter.toString();
@@ -530,13 +525,23 @@ public class CobaltLuaMachine implements ILuaMachine
             if( remaining <= 0 )
             {
                 LuaValue s;
+                state.getCurrentThread().disableYield();
                 try
                 {
                     s = OperationHelper.call( state, func );
-                } catch (LuaError e)
+                }
+                catch( UnwindThrowable e )
+                {
+                    throw new IOException( "Impossible yield within load" );
+                }
+                catch( LuaError e )
                 {
                     throw new IOException( e );
                 }
+                finally
+                {
+                    state.getCurrentThread().enableYield();
+                }
 
                 if( s.isNil() )
                 {

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

@@ -10,14 +10,32 @@ import dan200.computercraft.ComputerCraft;
 import dan200.computercraft.api.lua.ILuaObject;
 import dan200.computercraft.api.lua.LuaException;
 import dan200.computercraft.core.computer.Computer;
-import org.squiddev.cobalt.LuaError;
-import org.squiddev.cobalt.LuaState;
-import org.squiddev.cobalt.OrphanedThread;
-import org.squiddev.cobalt.Varargs;
+import org.squiddev.cobalt.*;
+import org.squiddev.cobalt.debug.DebugFrame;
+import org.squiddev.cobalt.debug.DebugHandler;
+import org.squiddev.cobalt.debug.DebugState;
 import org.squiddev.cobalt.function.VarArgFunction;
 
-class CobaltWrapperFunction extends VarArgFunction
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.SynchronousQueue;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicInteger;
+
+class CobaltWrapperFunction extends VarArgFunction implements Resumable<CobaltLuaContext>
 {
+    private static final ThreadGroup group = new ThreadGroup( "ComputerCraft-Lua" );
+    private static final AtomicInteger threadCounter = new AtomicInteger();
+    private static final ExecutorService threads = new ThreadPoolExecutor(
+        4, Integer.MAX_VALUE, 60L, TimeUnit.SECONDS, new SynchronousQueue<>(),
+        task -> {
+            Thread thread = new Thread( group, task, group.getName() + "-" + threadCounter.incrementAndGet() );
+            if( !thread.isDaemon() ) thread.setDaemon( true );
+            if( thread.getPriority() != Thread.NORM_PRIORITY ) thread.setPriority( Thread.NORM_PRIORITY );
+            return thread;
+        }
+    );
+
     private final CobaltLuaMachine machine;
     private final Computer computer;
 
@@ -25,7 +43,7 @@ class CobaltWrapperFunction extends VarArgFunction
     private final int method;
     private final String methodName;
 
-    public CobaltWrapperFunction( CobaltLuaMachine machine, Computer computer, ILuaObject delegate, int method, String methodName )
+    CobaltWrapperFunction( CobaltLuaMachine machine, Computer computer, ILuaObject delegate, int method, String methodName )
     {
         this.machine = machine;
         this.computer = computer;
@@ -35,30 +53,96 @@ class CobaltWrapperFunction extends VarArgFunction
     }
 
     @Override
-    public Varargs invoke( final LuaState state, Varargs _args ) throws LuaError
+    public Varargs invoke( final LuaState state, Varargs args ) throws LuaError, UnwindThrowable
     {
-        Object[] arguments = CobaltLuaMachine.toObjects( _args, 1 );
-        Object[] results;
+        Object[] arguments = CobaltLuaMachine.toObjects( args, 1 );
+        CobaltLuaContext context = new CobaltLuaContext( computer, state );
+
+        DebugHandler handler = state.debug;
+        DebugState ds = handler.getDebugState();
+        DebugFrame di = handler.onCall( ds, this );
+        di.state = context;
+
+        threads.submit( () -> {
+            try
+            {
+                context.values = delegate.callMethod( context, method, arguments );
+            }
+            catch( LuaException e )
+            {
+                context.exception = new LuaError( e );
+            }
+            catch( InterruptedException e )
+            {
+                if( ComputerCraft.logPeripheralErrors )
+                {
+                    ComputerCraft.log.error( "Error calling " + methodName + " on " + delegate, e );
+                }
+                context.exception = new LuaError( "Java Exception Thrown: " + e.toString(), 0 );
+            }
+            finally
+            {
+                context.done = true;
+                context.yield.signal();
+            }
+        } );
+
         try
         {
-            results = delegate.callMethod( new CobaltLuaContext( machine, computer, state ), method, arguments );
+            return handleResult( state, context );
         }
         catch( InterruptedException e )
         {
-            throw new OrphanedThread();
+            throw new LuaError( e );
         }
-        catch( LuaException e )
+    }
+
+    @Override
+    public Varargs resume( LuaState state, CobaltLuaContext context, Varargs value ) throws LuaError, UnwindThrowable
+    {
+        context.values = CobaltLuaMachine.toObjects( value, 0 );
+        context.resume.signal();
+        try
         {
-            throw new LuaError( e.getMessage(), e.getLevel() );
+            return handleResult( state, context );
         }
-        catch( Throwable t )
+        catch( InterruptedException e )
         {
-            if( ComputerCraft.logPeripheralErrors )
+            throw new LuaError( e );
+        }
+    }
+
+    @Override
+    public Varargs resumeError( LuaState state, CobaltLuaContext context, LuaError error ) throws LuaError
+    {
+        DebugHandler handler = state.debug;
+        handler.onReturn( handler.getDebugState() );
+        throw error;
+    }
+
+    private Varargs handleResult( LuaState state, CobaltLuaContext context ) throws InterruptedException, LuaError, UnwindThrowable
+    {
+        // We may be done if we yield when handling errors
+        if( !context.done ) context.yield.await();
+
+        if( context.done )
+        {
+            if( context.exception != null )
             {
-                ComputerCraft.log.error( "Error calling " + methodName + " on " + delegate, t );
+                context.exception.fillTraceback( state );
+                state.debug.onReturn();
+                throw context.exception;
+            }
+            else
+            {
+                state.debug.onReturn();
+                return machine.toValues( context.values );
             }
-            throw new LuaError( "Java Exception Thrown: " + t.toString(), 0 );
         }
-        return machine.toValues( results );
+        else
+        {
+            LuaThread.yield( state, machine.toValues( context.values ) );
+            throw new AssertionError( "Unreachable code" );
+        }
     }
 }

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

@@ -0,0 +1,38 @@
+/*
+ * 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.lua;
+
+/**
+ * A trivial way of signalling
+ */
+public final class Semaphore
+{
+    private volatile boolean state = false;
+
+    public synchronized void signal()
+    {
+        state = true;
+        notify();
+    }
+
+    public synchronized void await() throws InterruptedException
+    {
+        while( !state ) wait();
+        state = false;
+    }
+
+    public synchronized boolean await( long timeout ) throws InterruptedException
+    {
+        if( !state )
+        {
+            wait( timeout );
+            if( !state ) return false;
+        }
+        state = false;
+        return true;
+    }
+}