WIP

Author: byroot

inits.c

@@ -77,6 +77,7 @@ rb_call_inits(void)
     CALL(Prism);
     CALL(unicode_version);
     CALL(Set);
+    CALL(ractor_debug);
 
     // enable builtin loading
     CALL(builtin);

ractor.c

@@ -2256,6 +2256,13 @@ bool
 rb_ractor_main_p_(void)
 {
     VM_ASSERT(rb_multi_ractor_p());
+
+#if RUBY_DEBUG
+    if (ractor_debug_mode) {
+        return false;
+    }
+#endif
+
     rb_execution_context_t *ec = GET_EC();
     return rb_ec_ractor_ptr(ec) == rb_ec_vm_ptr(ec)->ractor.main_ractor;
 }
@@ -4176,4 +4183,30 @@ rb_ractor_autoload_load(VALUE module, ID name)
     }
 }
 
+#if RUBY_DEBUG
+static VALUE
+rb_ractor_debug_multi_ractor_mode(VALUE module)
+{
+    struct rb_ractor_struct *previous_single_main_ractor = ruby_single_main_ractor;
+    bool previous_ractor_debug_mode = ractor_debug_mode;
+
+    ractor_debug_mode = true;
+    // ruby_single_main_ractor = NULL;
+
+    VALUE result = rb_yield(Qundef);
+
+    ruby_single_main_ractor = previous_single_main_ractor;
+    ractor_debug_mode = previous_ractor_debug_mode;
+    return RB_GC_GUARD(result);
+}
+#endif
+
+void
+Init_ractor_debug(void)
+{
+#if RUBY_DEBUG
+    rb_define_singleton_method(rb_cRactor, "debug_multi_ractor_mode", rb_ractor_debug_multi_ractor_mode, 0);
+#endif
+}
+
 #include "ractor.rbinc"

ractor.rb

@@ -885,7 +885,7 @@ def self.main
   # return true if the current ractor is main ractor
   def self.main?
     __builtin_cexpr! %q{
-      RBOOL(GET_VM()->ractor.main_ractor == rb_ec_ractor_ptr(ec))
+      RBOOL(rb_ractor_main_p())
     }
   end
 

ractor_core.h

@@ -242,6 +242,12 @@ RUBY_SYMBOL_EXPORT_END
 static inline bool
 rb_ractor_main_p(void)
 {
+#if RUBY_DEBUG
+    if (ractor_debug_mode) {
+        return false;
+    }
+#endif
+
     if (ruby_single_main_ractor) {
         return true;
     }

vm.c

@@ -555,6 +555,10 @@ VALUE rb_block_param_proxy;
 VALUE ruby_vm_const_missing_count = 0;
 rb_vm_t *ruby_current_vm_ptr = NULL;
 rb_ractor_t *ruby_single_main_ractor;
+#if RUBY_DEBUG
+bool ractor_debug_mode = false;
+#endif
+
 bool ruby_vm_keep_script_lines;
 
 #ifdef RB_THREAD_LOCAL_SPECIFIER

vm_core.h

@@ -1922,6 +1922,10 @@ rb_execution_context_t *rb_vm_main_ractor_ec(rb_vm_t *vm); // ractor.c
 #if RUBY_VM_THREAD_MODEL == 2
 
 RUBY_EXTERN struct rb_ractor_struct *ruby_single_main_ractor; // ractor.c
+#if RUBY_DEBUG
+RUBY_EXTERN bool ractor_debug_mode;
+#endif
+
 RUBY_EXTERN rb_vm_t *ruby_current_vm_ptr;
 RUBY_EXTERN rb_event_flag_t ruby_vm_event_flags;
 RUBY_EXTERN rb_event_flag_t ruby_vm_event_enabled_global_flags;

vm_insnhelper.c

@@ -1101,6 +1101,7 @@ vm_get_ev_const(rb_execution_context_t *ec, VALUE orig_klass, ID id, bool allow_
                             return 1;
                         }
                         else {
+                            fprintf(stderr, "here rb_ractor_main_p() = %d\n", rb_ractor_main_p());
                             if (UNLIKELY(!rb_ractor_main_p())) {
                                 if (!rb_ractor_shareable_p(val)) {
                                     rb_raise(rb_eRactorIsolationError,