Add better control over expression timeouts. (#451)

Add better control over expression timeouts.
* //timeout command can be used to change player's current timeout.
* Config now also has a max timeout, can be bypassed with permission
* Timeout of < 0 will let expressions run indefinitely.
* Said expressions won't run on a separate thread, slightly reducing the
  overhead from context switching. For large //gen commands, for example,
  this can actually increase speed.

worldedit-core/src/main/java/com/sk89q/worldedit/EditSession.java

@@ -81,6 +81,7 @@ import com.sk89q.worldedit.history.changeset.BlockOptimizedHistory;
 import com.sk89q.worldedit.history.changeset.ChangeSet;
 import com.sk89q.worldedit.internal.expression.Expression;
 import com.sk89q.worldedit.internal.expression.ExpressionException;
+import com.sk89q.worldedit.internal.expression.runtime.ExpressionTimeoutException;
 import com.sk89q.worldedit.internal.expression.runtime.RValue;
 import com.sk89q.worldedit.math.BlockVector2;
 import com.sk89q.worldedit.math.BlockVector3;
@@ -1879,7 +1880,42 @@ public class EditSession implements Extent, AutoCloseable {
         return count.getDistribution();
     }
 
-    public int makeShape(final Region region, final Vector3 zero, final Vector3 unit, final Pattern pattern, final String expressionString, final boolean hollow) throws ExpressionException, MaxChangedBlocksException {
+    /**
+     * Generate a shape for the given expression.
+     *
+     * @param region the region to generate the shape in
+     * @param zero the coordinate origin for x/y/z variables
+     * @param unit the scale of the x/y/z/ variables
+     * @param pattern the default material to make the shape from
+     * @param expressionString the expression defining the shape
+     * @param hollow whether the shape should be hollow
+     * @return number of blocks changed
+     * @throws ExpressionException
+     * @throws MaxChangedBlocksException
+     */
+    public int makeShape(final Region region, final Vector3 zero, final Vector3 unit,
+                         final Pattern pattern, final String expressionString, final boolean hollow)
+            throws ExpressionException, MaxChangedBlocksException {
+        return makeShape(region, zero, unit, pattern, expressionString, hollow, WorldEdit.getInstance().getConfiguration().calculationTimeout);
+    }
+
+    /**
+     * Generate a shape for the given expression.
+     *
+     * @param region the region to generate the shape in
+     * @param zero the coordinate origin for x/y/z variables
+     * @param unit the scale of the x/y/z/ variables
+     * @param pattern the default material to make the shape from
+     * @param expressionString the expression defining the shape
+     * @param hollow whether the shape should be hollow
+     * @param timeout the time, in milliseconds, to wait for each expression evaluation before halting it. -1 to disable
+     * @return number of blocks changed
+     * @throws ExpressionException
+     * @throws MaxChangedBlocksException
+     */
+    public int makeShape(final Region region, final Vector3 zero, final Vector3 unit,
+                        final Pattern pattern, final String expressionString, final boolean hollow, final int timeout)
+            throws ExpressionException, MaxChangedBlocksException {
         final Expression expression = Expression.compile(expressionString, "x", "y", "z", "type", "data");
         expression.optimize();
 
@@ -1889,6 +1925,7 @@ public class EditSession implements Extent, AutoCloseable {
         final WorldEditExpressionEnvironment environment = new WorldEditExpressionEnvironment(this, unit, zero);
         expression.setEnvironment(environment);
 
+        final int[] timedOut = {0};
         final ArbitraryShape shape = new ArbitraryShape(region) {
             @Override
             protected BaseBlock getMaterial(int x, int y, int z, BaseBlock defaultMaterial) {
@@ -1906,27 +1943,42 @@ public class EditSession implements Extent, AutoCloseable {
                             dataVar = legacy[1];
                         }
                     }
-                    if (expression.evaluate(scaled.getX(), scaled.getY(), scaled.getZ(), typeVar, dataVar) <= 0) {
+                    if (expression.evaluate(new double[]{scaled.getX(), scaled.getY(), scaled.getZ(), typeVar, dataVar}, timeout) <= 0) {
                         return null;
                     }
                     int newType = (int) typeVariable.getValue();
                     int newData = (int) dataVariable.getValue();
                     if (newType != typeVar || newData != dataVar) {
-                        return LegacyMapper.getInstance().getBlockFromLegacy((int) typeVariable.getValue(), (int) dataVariable.getValue()).toBaseBlock();
+                        BlockState state = LegacyMapper.getInstance().getBlockFromLegacy(newType, newData);
+                        return state == null ? defaultMaterial : state.toBaseBlock();
                     } else {
                         return defaultMaterial;
                     }
+                } catch (ExpressionTimeoutException e) {
+                    timedOut[0] = timedOut[0] + 1;
+                    return null;
                 } catch (Exception e) {
                     log.log(Level.WARNING, "Failed to create shape", e);
                     return null;
                 }
             }
         };
-
+        int changed = shape.generate(this, pattern, hollow);
-        return shape.generate(this, pattern, hollow);
+        if (timedOut[0] > 0) {
+            throw new ExpressionTimeoutException(
+                    String.format("%d blocks changed. %d blocks took too long to evaluate (increase with //timeout).",
+                            changed, timedOut[0]));
+        }
+        return changed;
     }
 
-    public int deformRegion(final Region region, final Vector3 zero, final Vector3 unit, final String expressionString) throws ExpressionException, MaxChangedBlocksException {
+    public int deformRegion(final Region region, final Vector3 zero, final Vector3 unit, final String expressionString)
+            throws ExpressionException, MaxChangedBlocksException {
+        return deformRegion(region, zero, unit, expressionString, WorldEdit.getInstance().getConfiguration().calculationTimeout);
+    }
+
+    public int deformRegion(final Region region, final Vector3 zero, final Vector3 unit, final String expressionString,
+                            final int timeout) throws ExpressionException, MaxChangedBlocksException {
         final Expression expression = Expression.compile(expressionString, "x", "y", "z");
         expression.optimize();
 
@@ -1944,7 +1996,7 @@ public class EditSession implements Extent, AutoCloseable {
             final Vector3 scaled = position.toVector3().subtract(zero).divide(unit);
 
             // transform
-            expression.evaluate(scaled.getX(), scaled.getY(), scaled.getZ());
+            expression.evaluate(new double[]{scaled.getX(), scaled.getY(), scaled.getZ()}, timeout);
 
             final BlockVector3 sourcePosition = environment.toWorld(x.getValue(), y.getValue(), z.getValue());
 
@@ -2131,7 +2183,8 @@ public class EditSession implements Extent, AutoCloseable {
      * @return number of blocks affected
      * @throws MaxChangedBlocksException thrown if too many blocks are changed
      */
-    public int drawSpline(Pattern pattern, List<BlockVector3> nodevectors, double tension, double bias, double continuity, double quality, double radius, boolean filled)
+    public int drawSpline(Pattern pattern, List<BlockVector3> nodevectors, double tension, double bias,
+                          double continuity, double quality, double radius, boolean filled)
             throws MaxChangedBlocksException {
 
         Set<BlockVector3> vset = new HashSet<>();
@@ -2231,7 +2284,15 @@ public class EditSession implements Extent, AutoCloseable {
         }
     }
 
-    public int makeBiomeShape(final Region region, final Vector3 zero, final Vector3 unit, final BiomeType biomeType, final String expressionString, final boolean hollow) throws ExpressionException, MaxChangedBlocksException {
+    public int makeBiomeShape(final Region region, final Vector3 zero, final Vector3 unit, final BiomeType biomeType,
+                              final String expressionString, final boolean hollow)
+            throws ExpressionException, MaxChangedBlocksException {
+        return makeBiomeShape(region, zero, unit, biomeType, expressionString, hollow, WorldEdit.getInstance().getConfiguration().calculationTimeout);
+    }
+
+    public int makeBiomeShape(final Region region, final Vector3 zero, final Vector3 unit, final BiomeType biomeType,
+                              final String expressionString, final boolean hollow, final int timeout)
+            throws ExpressionException, MaxChangedBlocksException {
         final Vector2 zero2D = zero.toVector2();
         final Vector2 unit2D = unit.toVector2();
 
@@ -2242,6 +2303,7 @@ public class EditSession implements Extent, AutoCloseable {
         final WorldEditExpressionEnvironment environment = new WorldEditExpressionEnvironment(editSession, unit, zero);
         expression.setEnvironment(environment);
 
+        final int[] timedOut = {0};
         final ArbitraryBiomeShape shape = new ArbitraryBiomeShape(region) {
             @Override
             protected BiomeType getBiome(int x, int z, BiomeType defaultBiomeType) {
@@ -2250,20 +2312,28 @@ public class EditSession implements Extent, AutoCloseable {
                 final Vector2 scaled = current.subtract(zero2D).divide(unit2D);
 
                 try {
-                    if (expression.evaluate(scaled.getX(), scaled.getZ()) <= 0) {
+                    if (expression.evaluate(new double[]{scaled.getX(), scaled.getZ()}, timeout) <= 0) {
                         return null;
                     }
 
                     // TODO: Allow biome setting via a script variable (needs BiomeType<->int mapping)
                     return defaultBiomeType;
+                } catch (ExpressionTimeoutException e) {
+                    timedOut[0] = timedOut[0] + 1;
+                    return null;
                 } catch (Exception e) {
                     log.log(Level.WARNING, "Failed to create shape", e);
                     return null;
                 }
             }
         };
-
+        int changed = shape.generate(this, biomeType, hollow);
-        return shape.generate(this, biomeType, hollow);
+        if (timedOut[0] > 0) {
+            throw new ExpressionTimeoutException(
+                    String.format("%d blocks changed. %d blocks took too long to evaluate (increase time with //timeout)",
+                            changed, timedOut[0]));
+        }
+        return changed;
     }
 
     private static final BlockVector3[] recurseDirections = {

worldedit-core/src/main/java/com/sk89q/worldedit/LocalConfiguration.java

@@ -67,6 +67,7 @@ public abstract class LocalConfiguration {
     public int navigationWandMaxDistance = 50;
     public int scriptTimeout = 3000;
     public int calculationTimeout = 100;
+    public int maxCalculationTimeout = 300;
     public Set<String> allowedDataCycleBlocks = new HashSet<>();
     public String saveDir = "schematics";
     public String scriptsDir = "craftscripts";

worldedit-core/src/main/java/com/sk89q/worldedit/LocalSession.java

@@ -85,6 +85,7 @@ public class LocalSession {
     private transient BlockTool pickaxeMode = new SinglePickaxe();
     private transient Map<ItemType, Tool> tools = new HashMap<>();
     private transient int maxBlocksChanged = -1;
+    private transient int maxTimeoutTime;
     private transient boolean useInventory;
     private transient Snapshot snapshot;
     private transient boolean hasCUISupport = false;
@@ -415,6 +416,24 @@ public class LocalSession {
         this.maxBlocksChanged = maxBlocksChanged;
     }
 
+    /**
+     * Get the maximum time allowed for certain executions to run before cancelling them, such as expressions.
+     *
+     * @return timeout time, in milliseconds
+     */
+    public int getTimeout() {
+        return maxTimeoutTime;
+    }
+
+    /**
+     * Set the maximum number of blocks that can be changed.
+     *
+     * @param timeout the time, in milliseconds, to limit certain executions to, or -1 to disable
+     */
+    public void setTimeout(int timeout) {
+        this.maxTimeoutTime = timeout;
+    }
+
     /**
      * Checks whether the super pick axe is enabled.
      *

worldedit-core/src/main/java/com/sk89q/worldedit/command/GeneralCommands.java

@@ -57,9 +57,9 @@ public class GeneralCommands {
 
     @Command(
         aliases = { "/limit" },
-        usage = "<limit>",
+        usage = "[limit]",
         desc = "Modify block change limit",
-        min = 1,
+        min = 0,
         max = 1
     )
     @CommandPermissions("worldedit.limit")
@@ -68,7 +68,7 @@ public class GeneralCommands {
         LocalConfiguration config = worldEdit.getConfiguration();
         boolean mayDisable = player.hasPermission("worldedit.limit.unrestricted");
 
-        int limit = Math.max(-1, args.getInteger(0));
+        int limit = args.argsLength() == 0 ? config.defaultChangeLimit : Math.max(-1, args.getInteger(0));
         if (!mayDisable && config.maxChangeLimit > -1) {
             if (limit > config.maxChangeLimit) {
                 player.printError("Your maximum allowable limit is " + config.maxChangeLimit + ".");
@@ -78,13 +78,43 @@ public class GeneralCommands {
 
         session.setBlockChangeLimit(limit);
 
-        if (limit != -1) {
+        if (limit != config.defaultChangeLimit) {
-            player.print("Block change limit set to " + limit + ". (Use //limit -1 to go back to the default.)");
+            player.print("Block change limit set to " + limit + ". (Use //limit to go back to the default.)");
         } else {
             player.print("Block change limit set to " + limit + ".");
         }
     }
 
+    @Command(
+            aliases = { "/timeout" },
+            usage = "[time]",
+            desc = "Modify evaluation timeout time.",
+            min = 0,
+            max = 1
+    )
+    @CommandPermissions("worldedit.timeout")
+    public void timeout(Player player, LocalSession session, EditSession editSession, CommandContext args) throws WorldEditException {
+
+        LocalConfiguration config = worldEdit.getConfiguration();
+        boolean mayDisable = player.hasPermission("worldedit.timeout.unrestricted");
+
+        int limit = args.argsLength() == 0 ? config.calculationTimeout : Math.max(-1, args.getInteger(0));
+        if (!mayDisable && config.maxCalculationTimeout > -1) {
+            if (limit > config.maxCalculationTimeout) {
+                player.printError("Your maximum allowable timeout is " + config.maxCalculationTimeout + " ms.");
+                return;
+            }
+        }
+
+        session.setTimeout(limit);
+
+        if (limit != config.calculationTimeout) {
+            player.print("Timeout time set to " + limit + " ms. (Use //timeout to go back to the default.)");
+        } else {
+            player.print("Timeout time set to " + limit + " ms.");
+        }
+    }
+
     @Command(
         aliases = { "/fast" },
         usage = "[on|off]",

worldedit-core/src/main/java/com/sk89q/worldedit/command/GenerationCommands.java

@@ -306,7 +306,7 @@ public class GenerationCommands {
         }
 
         try {
-            final int affected = editSession.makeShape(region, zero, unit, pattern, expression, hollow);
+            final int affected = editSession.makeShape(region, zero, unit, pattern, expression, hollow, session.getTimeout());
             player.findFreePosition();
             player.print(affected + " block(s) have been created.");
         } catch (ExpressionException e) {
@@ -333,7 +333,7 @@ public class GenerationCommands {
         min = 2,
         max = -1
     )
-    @CommandPermissions({"worldedit.generation.shape", "worldedit.biome.set"})
+    @CommandPermissions("worldedit.generation.shape.biome")
     @Logging(ALL)
     public void generateBiome(Player player, LocalSession session, EditSession editSession,
                               @Selection Region region,
@@ -371,7 +371,7 @@ public class GenerationCommands {
         }
 
         try {
-            final int affected = editSession.makeBiomeShape(region, zero, unit, target, expression, hollow);
+            final int affected = editSession.makeBiomeShape(region, zero, unit, target, expression, hollow, session.getTimeout());
             player.findFreePosition();
             player.print("" + affected + " columns affected.");
         } catch (ExpressionException e) {

worldedit-core/src/main/java/com/sk89q/worldedit/command/RegionCommands.java

@@ -404,7 +404,7 @@ public class RegionCommands {
         }
 
         try {
-            final int affected = editSession.deformRegion(region, zero, unit, expression);
+            final int affected = editSession.deformRegion(region, zero, unit, expression, session.getTimeout());
             player.findFreePosition();
             player.print(affected + " block(s) have been deformed.");
         } catch (ExpressionException e) {

worldedit-core/src/main/java/com/sk89q/worldedit/command/UtilityCommands.java

@@ -52,6 +52,7 @@ import com.sk89q.worldedit.math.BlockVector3;
 import com.sk89q.worldedit.regions.CuboidRegion;
 import com.sk89q.worldedit.regions.CylinderRegion;
 import com.sk89q.worldedit.regions.Region;
+import com.sk89q.worldedit.session.SessionOwner;
 import com.sk89q.worldedit.util.command.CommandCallable;
 import com.sk89q.worldedit.util.command.CommandMapping;
 import com.sk89q.worldedit.util.command.Dispatcher;
@@ -541,13 +542,18 @@ public class UtilityCommands {
     public void calc(Actor actor, @Text String input) throws CommandException {
         try {
             Expression expression = Expression.compile(input);
+            if (actor instanceof SessionOwner) {
+                actor.print("= " + expression.evaluate(
+                        new double[]{}, WorldEdit.getInstance().getSessionManager().get((SessionOwner) actor).getTimeout()));
+            } else {
                 actor.print("= " + expression.evaluate());
+            }
         } catch (EvaluationException e) {
             actor.printError(String.format(
-                    "'%s' could not be parsed as a valid expression", input));
+                    "'%s' could not be evaluated (error: %s)", input, e.getMessage()));
         } catch (ExpressionException e) {
             actor.printError(String.format(
-                    "'%s' could not be evaluated (error: %s)", input, e.getMessage()));
+                    "'%s' could not be parsed as a valid expression", input));
         }
     }
 

worldedit-core/src/main/java/com/sk89q/worldedit/command/composition/SelectionCommand.java

@@ -79,6 +79,7 @@ public class SelectionCommand extends SimpleCommand<Operation> {
                 EditContext editContext = new EditContext();
                 editContext.setDestination(locals.get(EditSession.class));
                 editContext.setRegion(selection);
+                editContext.setSession(session);
 
                 Operation operation = operationFactory.createFromContext(editContext);
                 Operations.completeBlindly(operation);

worldedit-core/src/main/java/com/sk89q/worldedit/command/composition/ShapedBrushCommand.java

@@ -75,7 +75,7 @@ public class ShapedBrushCommand extends SimpleCommand<Object> {
             BrushTool tool = session.getBrushTool(player.getItemInHand(HandSide.MAIN_HAND).getType());
             tool.setSize(radius);
             tool.setFill(null);
-            tool.setBrush(new OperationFactoryBrush(factory, regionFactory), permission);
+            tool.setBrush(new OperationFactoryBrush(factory, regionFactory, session), permission);
         } catch (MaxBrushRadiusException | InvalidToolBindException e) {
             WorldEdit.getInstance().getPlatformManager().getCommandManager().getExceptionConverter().convert(e);
         }

worldedit-core/src/main/java/com/sk89q/worldedit/command/tool/brush/OperationFactoryBrush.java

@@ -20,6 +20,7 @@
 package com.sk89q.worldedit.command.tool.brush;
 
 import com.sk89q.worldedit.EditSession;
+import com.sk89q.worldedit.LocalSession;
 import com.sk89q.worldedit.MaxChangedBlocksException;
 import com.sk89q.worldedit.function.Contextual;
 import com.sk89q.worldedit.function.EditContext;
@@ -33,10 +34,16 @@ public class OperationFactoryBrush implements Brush {
 
     private final Contextual<? extends Operation> operationFactory;
     private final RegionFactory regionFactory;
+    private final LocalSession session;
 
     public OperationFactoryBrush(Contextual<? extends Operation> operationFactory, RegionFactory regionFactory) {
+        this(operationFactory, regionFactory, null);
+    }
+
+    public OperationFactoryBrush(Contextual<? extends Operation> operationFactory, RegionFactory regionFactory, LocalSession session) {
         this.operationFactory = operationFactory;
         this.regionFactory = regionFactory;
+        this.session = session;
     }
 
     @Override
@@ -45,6 +52,7 @@ public class OperationFactoryBrush implements Brush {
         context.setDestination(editSession);
         context.setRegion(regionFactory.createCenteredAt(position, size));
         context.setFill(pattern);
+        context.setSession(session);
         Operation operation = operationFactory.createFromContext(context);
         Operations.completeLegacy(operation);
     }

worldedit-core/src/main/java/com/sk89q/worldedit/extension/factory/parser/mask/ExpressionMaskParser.java

@@ -29,8 +29,11 @@ import com.sk89q.worldedit.internal.expression.ExpressionException;
 import com.sk89q.worldedit.internal.registry.InputParser;
 import com.sk89q.worldedit.math.Vector3;
 import com.sk89q.worldedit.regions.shape.WorldEditExpressionEnvironment;
+import com.sk89q.worldedit.session.SessionOwner;
 import com.sk89q.worldedit.session.request.Request;
 
+import java.util.function.IntSupplier;
+
 public class ExpressionMaskParser extends InputParser<Mask> {
 
     public ExpressionMaskParser(WorldEdit worldEdit) {
@@ -48,6 +51,11 @@ public class ExpressionMaskParser extends InputParser<Mask> {
             WorldEditExpressionEnvironment env = new WorldEditExpressionEnvironment(
                     Request.request().getEditSession(), Vector3.ONE, Vector3.ZERO);
             exp.setEnvironment(env);
+            if (context.getActor() instanceof SessionOwner) {
+                SessionOwner owner = (SessionOwner) context.getActor();
+                IntSupplier timeout = () -> WorldEdit.getInstance().getSessionManager().get(owner).getTimeout();
+                return new ExpressionMask(exp, timeout);
+            }
             return new ExpressionMask(exp);
         } catch (ExpressionException e) {
             throw new InputParseException("Invalid expression: " + e.getMessage());

worldedit-core/src/main/java/com/sk89q/worldedit/function/EditContext.java

@@ -21,6 +21,7 @@ package com.sk89q.worldedit.function;
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
+import com.sk89q.worldedit.LocalSession;
 import com.sk89q.worldedit.extent.Extent;
 import com.sk89q.worldedit.function.pattern.Pattern;
 import com.sk89q.worldedit.regions.Region;
@@ -32,6 +33,7 @@ public class EditContext {
     private Extent destination;
     @Nullable private Region region;
     @Nullable private Pattern fill;
+    @Nullable private LocalSession session;
 
     public Extent getDestination() {
         return destination;
@@ -60,4 +62,12 @@ public class EditContext {
         this.fill = fill;
     }
 
+    @Nullable
+    public LocalSession getSession() {
+        return session;
+    }
+
+    public void setSession(@Nullable LocalSession session) {
+        this.session = session;
+    }
 }

worldedit-core/src/main/java/com/sk89q/worldedit/function/factory/Deform.java

@@ -23,6 +23,8 @@ import static com.google.common.base.Preconditions.checkNotNull;
 import static com.sk89q.worldedit.util.GuavaUtil.firstNonNull;
 
 import com.sk89q.worldedit.EditSession;
+import com.sk89q.worldedit.LocalSession;
+import com.sk89q.worldedit.WorldEdit;
 import com.sk89q.worldedit.WorldEditException;
 import com.sk89q.worldedit.extent.Extent;
 import com.sk89q.worldedit.extent.NullExtent;
@@ -147,7 +149,9 @@ public class Deform implements Contextual<Operation> {
                 unit = Vector3.ONE;
         }
 
-        return new DeformOperation(context.getDestination(), region, zero, unit, expression);
+        LocalSession session = context.getSession();
+        return new DeformOperation(context.getDestination(), region, zero, unit, expression,
+                session == null ? WorldEdit.getInstance().getConfiguration().calculationTimeout : session.getTimeout());
     }
 
     private static final class DeformOperation implements Operation {
@@ -156,20 +160,22 @@ public class Deform implements Contextual<Operation> {
         private final Vector3 zero;
         private final Vector3 unit;
         private final String expression;
+        private final int timeout;
 
-        private DeformOperation(Extent destination, Region region, Vector3 zero, Vector3 unit, String expression) {
+        private DeformOperation(Extent destination, Region region, Vector3 zero, Vector3 unit, String expression, int timeout) {
             this.destination = destination;
             this.region = region;
             this.zero = zero;
             this.unit = unit;
             this.expression = expression;
+            this.timeout = timeout;
         }
 
         @Override
         public Operation resume(RunContext run) throws WorldEditException {
             try {
                 // TODO: Move deformation code
-                ((EditSession) destination).deformRegion(region, zero, unit, expression);
+                ((EditSession) destination).deformRegion(region, zero, unit, expression, timeout);
                 return null;
             } catch (ExpressionException e) {
                 throw new RuntimeException("Failed to execute expression", e); // TODO: Better exception to throw here?

worldedit-core/src/main/java/com/sk89q/worldedit/function/mask/ExpressionMask.java

@@ -21,6 +21,7 @@ package com.sk89q.worldedit.function.mask;
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
+import com.sk89q.worldedit.WorldEdit;
 import com.sk89q.worldedit.internal.expression.Expression;
 import com.sk89q.worldedit.internal.expression.ExpressionException;
 import com.sk89q.worldedit.internal.expression.runtime.EvaluationException;
@@ -28,6 +29,7 @@ import com.sk89q.worldedit.math.BlockVector3;
 import com.sk89q.worldedit.regions.shape.WorldEditExpressionEnvironment;
 
 import javax.annotation.Nullable;
+import java.util.function.IntSupplier;
 
 /**
  * A mask that evaluates an expression.
@@ -38,6 +40,7 @@ import javax.annotation.Nullable;
 public class ExpressionMask extends AbstractMask {
 
     private final Expression expression;
+    private final IntSupplier timeout;
 
     /**
      * Create a new instance.
@@ -46,8 +49,7 @@ public class ExpressionMask extends AbstractMask {
      * @throws ExpressionException thrown if there is an error with the expression
      */
     public ExpressionMask(String expression) throws ExpressionException {
-        checkNotNull(expression);
+        this(Expression.compile(checkNotNull(expression), "x", "y", "z"));
-        this.expression = Expression.compile(expression, "x", "y", "z");
     }
 
     /**
@@ -56,8 +58,13 @@ public class ExpressionMask extends AbstractMask {
      * @param expression the expression
      */
     public ExpressionMask(Expression expression) {
+        this(expression, null);
+    }
+
+    public ExpressionMask(Expression expression, @Nullable IntSupplier timeout) {
         checkNotNull(expression);
         this.expression = expression;
+        this.timeout = timeout;
     }
 
     @Override
@@ -66,7 +73,12 @@ public class ExpressionMask extends AbstractMask {
             if (expression.getEnvironment() instanceof WorldEditExpressionEnvironment) {
                 ((WorldEditExpressionEnvironment) expression.getEnvironment()).setCurrentBlock(vector.toVector3());
             }
+            if (timeout == null) {
                 return expression.evaluate(vector.getX(), vector.getY(), vector.getZ()) > 0;
+            } else {
+                return expression.evaluate(new double[]{vector.getX(), vector.getY(), vector.getZ()},
+                        timeout.getAsInt()) > 0;
+            }
         } catch (EvaluationException e) {
             return false;
         }
@@ -75,7 +87,7 @@ public class ExpressionMask extends AbstractMask {
     @Nullable
     @Override
     public Mask2D toMask2D() {
-        return new ExpressionMask2D(expression);
+        return new ExpressionMask2D(expression, timeout);
     }
 
 }

worldedit-core/src/main/java/com/sk89q/worldedit/function/mask/ExpressionMask2D.java

@@ -21,14 +21,19 @@ package com.sk89q.worldedit.function.mask;
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
+import com.sk89q.worldedit.WorldEdit;
 import com.sk89q.worldedit.internal.expression.Expression;
 import com.sk89q.worldedit.internal.expression.ExpressionException;
 import com.sk89q.worldedit.internal.expression.runtime.EvaluationException;
 import com.sk89q.worldedit.math.BlockVector2;
 
+import javax.annotation.Nullable;
+import java.util.function.IntSupplier;
+
 public class ExpressionMask2D extends AbstractMask2D {
 
     private final Expression expression;
+    private final IntSupplier timeout;
 
     /**
      * Create a new instance.
@@ -37,8 +42,7 @@ public class ExpressionMask2D extends AbstractMask2D {
      * @throws ExpressionException thrown if there is an error with the expression
      */
     public ExpressionMask2D(String expression) throws ExpressionException {
-        checkNotNull(expression);
+        this(Expression.compile(checkNotNull(expression), "x", "z"));
-        this.expression = Expression.compile(expression, "x", "z");
     }
 
     /**
@@ -47,14 +51,23 @@ public class ExpressionMask2D extends AbstractMask2D {
      * @param expression the expression
      */
     public ExpressionMask2D(Expression expression) {
+        this(expression, null);
+    }
+
+    public ExpressionMask2D(Expression expression, @Nullable IntSupplier timeout) {
         checkNotNull(expression);
         this.expression = expression;
+        this.timeout = timeout;
     }
 
     @Override
     public boolean test(BlockVector2 vector) {
         try {
+            if (timeout != null) {
                 return expression.evaluate(vector.getX(), 0, vector.getZ()) > 0;
+            } else {
+                return expression.evaluate(new double[]{vector.getX(), 0, vector.getZ()}, timeout.getAsInt()) > 0;
+            }
         } catch (EvaluationException e) {
             return false;
         }

worldedit-core/src/main/java/com/sk89q/worldedit/internal/expression/Expression.java

@@ -27,6 +27,7 @@ import com.sk89q.worldedit.internal.expression.parser.Parser;
 import com.sk89q.worldedit.internal.expression.runtime.Constant;
 import com.sk89q.worldedit.internal.expression.runtime.EvaluationException;
 import com.sk89q.worldedit.internal.expression.runtime.ExpressionEnvironment;
+import com.sk89q.worldedit.internal.expression.runtime.ExpressionTimeoutException;
 import com.sk89q.worldedit.internal.expression.runtime.Functions;
 import com.sk89q.worldedit.internal.expression.runtime.RValue;
 import com.sk89q.worldedit.internal.expression.runtime.ReturnException;
@@ -36,7 +37,6 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Stack;
-import java.util.concurrent.Callable;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
@@ -117,6 +117,10 @@ public class Expression {
     }
 
     public double evaluate(double... values) throws EvaluationException {
+        return evaluate(values, WorldEdit.getInstance().getConfiguration().calculationTimeout);
+    }
+
+    public double evaluate(double[] values, int timeout) throws EvaluationException {
         for (int i = 0; i < values.length; ++i) {
             final String variableName = variableNames[i];
             final RValue invokable = variables.get(variableName);
@@ -127,34 +131,44 @@ public class Expression {
             ((Variable) invokable).value = values[i];
         }
 
-        Future<Double> result = evalThread.submit(new Callable<Double>() {
-            @Override
-            public Double call() throws Exception {
-                pushInstance();
         try {
-                    return root.getValue();
+            if (timeout < 0) {
-                } finally {
+                return evaluateRoot();
-                    popInstance();
             }
+            return evaluateRootTimed(timeout);
+        } catch (ReturnException e) {
+            return e.getValue();
+        } // other evaluation exceptions are thrown out of this method
     }
-        });
+
+    private double evaluateRootTimed(int timeout) throws EvaluationException {
+        Future<Double> result = evalThread.submit(this::evaluateRoot);
         try {
-            return result.get(WorldEdit.getInstance().getConfiguration().calculationTimeout, TimeUnit.MILLISECONDS);
+            return result.get(timeout, TimeUnit.MILLISECONDS);
         } catch (InterruptedException e) {
             Thread.currentThread().interrupt();
             throw new RuntimeException(e);
+        } catch (TimeoutException e) {
+            result.cancel(true);
+            throw new ExpressionTimeoutException("Calculations exceeded time limit.");
         } catch (ExecutionException e) {
             Throwable cause = e.getCause();
-            if (cause instanceof ReturnException) {
+            if (cause instanceof EvaluationException) {
-                return ((ReturnException) cause).getValue();
+                throw (EvaluationException) cause;
             }
             if (cause instanceof RuntimeException) {
                 throw (RuntimeException) cause;
             }
             throw new RuntimeException(cause);
-        } catch (TimeoutException e) {
+        }
-            result.cancel(true);
+    }
-            throw new EvaluationException(-1, "Calculations exceeded time limit.");
+
+    private Double evaluateRoot() throws EvaluationException {
+        pushInstance();
+        try {
+            return root.getValue();
+        } finally {
+            popInstance();
         }
     }
 

worldedit-core/src/main/java/com/sk89q/worldedit/internal/expression/runtime/ExpressionTimeoutException.java

@@ -0,0 +1,29 @@
+/*
+ * WorldEdit, a Minecraft world manipulation toolkit
+ * Copyright (C) sk89q <http://www.sk89q.com>
+ * Copyright (C) WorldEdit team and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package com.sk89q.worldedit.internal.expression.runtime;
+
+/**
+ * Thrown when an evaluation exceeds the timeout time.
+ */
+public class ExpressionTimeoutException extends EvaluationException {
+    public ExpressionTimeoutException(String message) {
+        super(-1, message);
+    }
+}

worldedit-core/src/main/java/com/sk89q/worldedit/session/SessionManager.java

@@ -155,31 +155,20 @@ public class SessionManager {
 
             session.setConfiguration(config);
             session.setBlockChangeLimit(config.defaultChangeLimit);
+            session.setTimeout(config.calculationTimeout);
 
             // Remember the session regardless of if it's currently active or not.
             // And have the SessionTracker FLUSH inactive sessions.
             sessions.put(getKey(owner), new SessionHolder(sessionKey, session));
         }
 
-        // Set the limit on the number of blocks that an operation can
+        if (shouldBoundLimit(owner.hasPermission("worldedit.limit.unrestricted"),
-        // change at once, or don't if the owner has an override or there
+                session.getBlockChangeLimit(), config.maxChangeLimit)) {
-        // is no limit. There is also a default limit
-        int currentChangeLimit = session.getBlockChangeLimit();
-
-        if (!owner.hasPermission("worldedit.limit.unrestricted") && config.maxChangeLimit > -1) {
-            // If the default limit is infinite but there is a maximum
-            // limit, make sure to not have it be overridden
-            if (config.defaultChangeLimit < 0) {
-                if (currentChangeLimit < 0 || currentChangeLimit > config.maxChangeLimit) {
             session.setBlockChangeLimit(config.maxChangeLimit);
         }
-            } else {
+        if (shouldBoundLimit(owner.hasPermission("worldedit.timeout.unrestricted"),
-                // Bound the change limit
+                session.getTimeout(), config.maxCalculationTimeout)) {
-                int maxChangeLimit = config.maxChangeLimit;
+            session.setTimeout(config.maxCalculationTimeout);
-                if (currentChangeLimit == -1 || currentChangeLimit > maxChangeLimit) {
-                    session.setBlockChangeLimit(maxChangeLimit);
-                }
-            }
         }
 
         // Have the session use inventory if it's enabled and the owner
@@ -192,6 +181,13 @@ public class SessionManager {
         return session;
     }
 
+    private boolean shouldBoundLimit(boolean mayBypass, int currentLimit, int maxLimit) {
+        if (!mayBypass && maxLimit > -1) { // if player can't bypass and max is finite
+            return currentLimit < 0 || currentLimit > maxLimit; // make sure current is finite and less than max
+        }
+        return false;
+    }
+
     /**
      * Save a map of sessions to disk.
      *

worldedit-core/src/main/java/com/sk89q/worldedit/util/PropertiesConfiguration.java

@@ -112,6 +112,7 @@ public class PropertiesConfiguration extends LocalConfiguration {
         navigationUseGlass = getBool("nav-use-glass", navigationUseGlass);
         scriptTimeout = getInt("scripting-timeout", scriptTimeout);
         calculationTimeout = getInt("calculation-timeout", calculationTimeout);
+        maxCalculationTimeout = getInt("max-calculation-timeout", maxCalculationTimeout);
         saveDir = getString("schematic-save-dir", saveDir);
         scriptsDir = getString("craftscript-dir", scriptsDir);
         butcherDefaultRadius = getInt("butcher-default-radius", butcherDefaultRadius);

worldedit-core/src/main/java/com/sk89q/worldedit/util/YAMLConfiguration.java

@@ -108,6 +108,7 @@ public class YAMLConfiguration extends LocalConfiguration {
         scriptsDir = config.getString("scripting.dir", scriptsDir);
 
         calculationTimeout = config.getInt("calculation.timeout", calculationTimeout);
+        maxCalculationTimeout = config.getInt("calculation.max-timeout", maxCalculationTimeout);
 
         saveDir = config.getString("saving.dir", saveDir);
 

worldedit-core/src/test/java/com/sk89q/worldedit/internal/expression/ExpressionTest.java

@@ -64,7 +64,7 @@ public class ExpressionTest {
         assertEquals(atan2(3, 4), simpleEval("atan2(3, 4)"), 0);
 
         // check variables
-        assertEquals(8, compile("foo+bar", "foo", "bar").evaluate(5, 3), 0);
+        assertEquals(8, compile("foo+bar", "foo", "bar").evaluate(5D, 3D), 0);
     }
 
     @Test
@@ -123,7 +123,7 @@ public class ExpressionTest {
     @Test
     public void testAssign() throws ExpressionException {
         Expression foo = compile("{a=x} b=y; c=z", "x", "y", "z", "a", "b", "c");
-        foo.evaluate(2, 3, 5);
+        foo.evaluate(2D, 3D, 5D);
         assertEquals(2, foo.getVariable("a", false).getValue(), 0);
         assertEquals(3, foo.getVariable("b", false).getValue(), 0);
         assertEquals(5, foo.getVariable("c", false).getValue(), 0);
@@ -136,13 +136,13 @@ public class ExpressionTest {
 
         // test 'dangling else'
         final Expression expression1 = compile("if (1) if (0) x=4; else y=5;", "x", "y");
-        expression1.evaluate(1, 2);
+        expression1.evaluate(1D, 2D);
         assertEquals(1, expression1.getVariable("x", false).getValue(), 0);
         assertEquals(5, expression1.getVariable("y", false).getValue(), 0);
 
         // test if the if construct is correctly recognized as a statement
         final Expression expression2 = compile("if (0) if (1) x=5; y=4;", "x", "y");
-        expression2.evaluate(1, 2);
+        expression2.evaluate(1D, 2D);
         assertEquals(4, expression2.getVariable("y", false).getValue(), 0);
     }