events handling is disabled now when potentially triggered from the scarpet script preventing from recursive callbacks.

src/main/java/carpet/script/CarpetEventServer.java

@@ -6,6 +6,7 @@ import carpet.helpers.TickSpeed;
 import carpet.script.exception.IntegrityException;
 import carpet.script.exception.InternalExpressionException;
 import carpet.script.exception.InvalidCallbackException;
+import carpet.script.utils.GlocalFlag;
 import carpet.script.value.BlockValue;
 import carpet.script.value.BooleanValue;
 import carpet.script.value.EntityValue;
@@ -73,8 +74,7 @@ public class CarpetEventServer
     public final CarpetScriptServer scriptServer;
     private static final List<Value> NOARGS = Collections.emptyList();
     public final Map<String, Event> customEvents = new HashMap<>();
-
-
+    public GlocalFlag handleEvents = new GlocalFlag(true);
 
     public enum CallbackResult
     {
@@ -194,31 +194,33 @@ public class CarpetEventServer
          */
         public void call(Supplier<List<Value>> argumentSupplier, Supplier<ServerCommandSource> cmdSourceSupplier)
         {
-            if (callList.size() > 0)
+            if (callList.size() > 0 && CarpetServer.scriptServer != null)
             {
-                CarpetProfiler.ProfilerToken currentSection = CarpetProfiler.start_section(null, "Scarpet events", CarpetProfiler.TYPE.GENERAL);
-                List<Value> argv = argumentSupplier.get(); // empty for onTickDone
-                ServerCommandSource source;
-                try
-                {
-                     source = cmdSourceSupplier.get();
-                }
-                catch (NullPointerException noReference) // todo figure out what happens when closing.
-                {
-                    return;
-                }
-                String nameCheck = perPlayerDistribution?source.getName():null;
-                assert argv.size() == reqArgs;
-                List<Callback> fails = new ArrayList<>();
-                for (Callback call: callList)
-                {
-                    // supressing calls where target player hosts simply don't match
-                    // handling global hosts with player targets is left to when the host is resolved (few calls deeper).
-                    if (nameCheck != null && call.optionalTarget != null && !nameCheck.equals(call.optionalTarget)) continue;
-                    if (call.execute(source, argv) == CallbackResult.FAIL) fails.add(call);
-                }
-                for (Callback call : fails) callList.remove(call);
-                CarpetProfiler.end_current_section(currentSection);
+                CarpetServer.scriptServer.events.handleEvents.runIfEnabled( () -> {
+                    CarpetProfiler.ProfilerToken currentSection = CarpetProfiler.start_section(null, "Scarpet events", CarpetProfiler.TYPE.GENERAL);
+                    List<Value> argv = argumentSupplier.get(); // empty for onTickDone
+                    ServerCommandSource source;
+                    try
+                    {
+                        source = cmdSourceSupplier.get();
+                    }
+                    catch (NullPointerException noReference) // todo figure out what happens when closing.
+                    {
+                        return;
+                    }
+                    String nameCheck = perPlayerDistribution ? source.getName() : null;
+                    assert argv.size() == reqArgs;
+                    List<Callback> fails = new ArrayList<>();
+                    for (Callback call : callList)
+                    {
+                        // supressing calls where target player hosts simply don't match
+                        // handling global hosts with player targets is left to when the host is resolved (few calls deeper).
+                        if (nameCheck != null && call.optionalTarget != null && !nameCheck.equals(call.optionalTarget)) continue;
+                        if (call.execute(source, argv) == CallbackResult.FAIL) fails.add(call);
+                    }
+                    for (Callback call : fails) callList.remove(call);
+                    CarpetProfiler.end_current_section(currentSection);
+                });
             }
         }
 

src/main/java/carpet/script/CarpetExpression.java

@@ -72,7 +72,7 @@ public class CarpetExpression
                 Value playerValue = new EntityValue(e).bindTo("p");
                 context.with("p", (cc, tt) -> playerValue);
             }
-            return this.expr.eval(context).getBoolean();
+            return CarpetServer.scriptServer.events.handleEvents.getWhileDisabled(()-> this.expr.eval(context).getBoolean());
         }
         catch (ExpressionException e)
         {
@@ -109,7 +109,7 @@ public class CarpetExpression
                 Value playerValue = new EntityValue(e).bindTo("p");
                 context.with("p", (cc, tt) -> playerValue);
             }
-            return this.expr.eval(context);
+            return CarpetServer.scriptServer.events.handleEvents.getWhileDisabled(()-> this.expr.eval(context));
         }
         catch (ExpressionException e)
         {

src/main/java/carpet/script/CarpetScriptHost.java

@@ -710,7 +710,7 @@ public class CarpetScriptHost extends ScriptHost
     {
         try
         {
-            return call(source, function, args);
+            return scriptServer.events.handleEvents.getWhileDisabled(() -> call(source, function, args));
         }
         catch (CarpetExpressionException exc)
         {
@@ -815,11 +815,11 @@ public class CarpetScriptHost extends ScriptHost
             // TODO: this is just for now - invoke would be able to invoke other hosts scripts
             assertAppIntegrity(function.getModule());
             Context context = new CarpetContext(this, source, BlockPos.ORIGIN);
-            return function.getExpression().evalValue(
+            return scriptServer.events.handleEvents.getWhileDisabled(() -> function.getExpression().evalValue(
                     () -> function.lazyEval(context, Context.VOID, function.getExpression(), function.getToken(), argv),
                     context,
                     Context.VOID
-            );
+            ));
         }
         catch (ExpressionException e)
         {
@@ -891,6 +891,7 @@ public class CarpetScriptHost extends ScriptHost
     {
         ServerPlayerEntity player = (user==null)?null:scriptServer.server.getPlayerManager().getPlayer(user);
         ServerCommandSource source = (player != null)?player.getCommandSource():scriptServer.server.getCommandSource();
+        return scriptServer.events.handleEvents.getWhileDisabled(()->{
         try
         {
             return callUDF(BlockPos.ORIGIN, source, fun, arguments);
@@ -899,6 +900,7 @@ public class CarpetScriptHost extends ScriptHost
         {
             return Value.NULL;
         }
+        });
     }
 
 

src/main/java/carpet/script/CarpetScriptServer.java

@@ -375,7 +375,7 @@ public class CarpetScriptServer
     {
         CarpetProfiler.ProfilerToken token;
         token = CarpetProfiler.start_section(null, "Scarpet schedule", CarpetProfiler.TYPE.GENERAL);
-        events.tick();
+        events.handleEvents.getWhileDisabled( () -> {events.tick(); return null;});
         CarpetProfiler.end_current_section(token);
         token = CarpetProfiler.start_section(null, "Scarpet app data", CarpetProfiler.TYPE.GENERAL);
         for (CarpetScriptHost host : modules.values())

src/main/java/carpet/script/utils/GlocalFlag.java

@@ -0,0 +1,68 @@
+package carpet.script.utils;
+
+import java.util.function.Supplier;
+
+public class GlocalFlag extends ThreadLocal<Boolean>
+{
+    private final boolean initial;
+
+    public GlocalFlag(boolean initial)
+    {
+        this.initial = initial;
+    }
+
+    @Override
+    public Boolean initialValue()
+    {
+        return initial;
+    }
+
+    /**
+     * Allows to thread-safely wrap a call while disabling a global flag and setting it back up right after.
+     * @param action - callback to invoke when the wrapping is all setup
+     * @param <T> - returned value of that action, whatever that might be
+     * @return result of the action
+     */
+    public <T> T getWhileDisabled(Supplier<T> action)
+    {
+        return whileValueReturn(!initial, action);
+    }
+
+    private <T> T whileValueReturn(boolean what, Supplier<T> action)
+    {
+        T result;
+        boolean previous;
+        synchronized (this)
+        {
+            previous = get();
+            set(what);
+        }
+        try
+        {
+            result = action.get();
+        }
+        finally
+        {
+            set(previous);
+        }
+        return result;
+    }
+
+    public boolean runIfEnabled(Runnable action)
+    {
+        synchronized (this)
+        {
+            if (get() != initial) return false;
+            set(!initial);
+        }
+        try
+        {
+            action.run();
+        }
+        finally
+        {
+            set(initial);
+        }
+        return true;
+    }
+}