Dump Cobalt's internal state on timeouts

Closes #1180

build.gradle

@@ -141,7 +141,7 @@ accessTransformer file('src/testMod/resources/META-INF/accesstransformer.cfg')
     extraModsCompileOnly fg.deobf("com.blamejared.crafttweaker:CraftTweaker-1.16.5:7.1.0.313")
     extraModsCompileOnly fg.deobf("commoble.morered:morered-1.16.5:2.1.1.0")
 
-    shade 'org.squiddev:Cobalt:0.5.5'
+    shade 'org.squiddev:Cobalt:0.5.7'
 
     testImplementation 'org.junit.jupiter:junit-jupiter-api:5.7.0'
     testImplementation 'org.junit.jupiter:junit-jupiter-params:5.7.0'

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

@@ -625,6 +625,15 @@ else if( event != null )
         }
     }
 
+    void printState( StringBuilder out )
+    {
+        out.append( "Enqueued command: " ).append( command ).append( '\n' );
+        out.append( "Enqueued events: " ).append( eventQueue.size() ).append( '\n' );
+
+        ILuaMachine machine = this.machine;
+        if( machine != null ) machine.printExecutionState( out );
+    }
+
     private void displayFailure( String message, String extra )
     {
         Terminal terminal = computer.getTerminal();

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

@@ -575,18 +575,22 @@ private void reportTimeout( ComputerExecutor executor, long time )
             StringBuilder builder = new StringBuilder()
                 .append( "Terminating computer #" ).append( executor.getComputer().getID() )
                 .append( " due to timeout (running for " ).append( time * 1e-9 )
-                .append( " seconds). This is NOT a bug, but may mean a computer is misbehaving. " )
+                .append( " seconds). This is NOT a bug, but may mean a computer is misbehaving.\n" )
+                .append( "Thread " )
                 .append( owner.getName() )
                 .append( " is currently " )
-                .append( owner.getState() );
+                .append( owner.getState() )
+                .append( '\n' );
             Object blocking = LockSupport.getBlocker( owner );
-            if( blocking != null ) builder.append( "\n  on " ).append( blocking );
+            if( blocking != null ) builder.append( "  on " ).append( blocking ).append( '\n' );
 
             for( StackTraceElement element : owner.getStackTrace() )
             {
-                builder.append( "\n  at " ).append( element );
+                builder.append( "  at " ).append( element ).append( '\n' );
             }
 
+            executor.printState( builder );
+
             ComputerCraft.log.warn( builder.toString() );
         }
     }

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

@@ -214,6 +214,20 @@ public MachineResult handleEvent( String eventName, Object[] arguments )
         }
     }
 
+    @Override
+    public void printExecutionState( StringBuilder out )
+    {
+        LuaState state = this.state;
+        if( state == null )
+        {
+            out.append( "CobaltLuaMachine is terminated\n" );
+        }
+        else
+        {
+            state.printExecutionState( out );
+        }
+    }
+
     @Override
     public void close()
     {

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

@@ -61,6 +61,15 @@ public interface ILuaMachine
      */
     MachineResult handleEvent( @Nullable String eventName, @Nullable Object[] arguments );
 
+    /**
+     * Print some information about the internal execution state.
+     * <p>
+     * This function is purely intended for debugging, its output should not be relied on in any way.
+     *
+     * @param out The buffer to write to.
+     */
+    void printExecutionState( StringBuilder out );
+
     /**
      * Close the Lua machine, aborting any running functions and deleting the internal state.
      */

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

@@ -211,6 +211,11 @@ public MachineResult handleEvent( @Nullable String eventName, @Nullable Object[]
             }
         }
 
+        @Override
+        public void printExecutionState( StringBuilder out )
+        {
+        }
+
         @Override
         public void close()
         {