expose some C-APIs for ractor

expose some C-APIs to try to make ractor utilities on external gems.

* add
  * rb_ractor_local_storage_value_lookup() to check availability
* expose
  * rb_ractor_make_shareable()
  * rb_ractor_make_shareable_copy()
  * rb_proc_isolate() (not public)
  * rb_proc_isolate_bang() (not public)
  * rb_proc_ractor_make_shareable() (not public)

include/ruby/ractor.h

@@ -32,6 +32,7 @@ void rb_ractor_stderr_set(VALUE);
 
 rb_ractor_local_key_t rb_ractor_local_storage_value_newkey(void);
 VALUE rb_ractor_local_storage_value(rb_ractor_local_key_t key);
+bool rb_ractor_local_storage_value_lookup(rb_ractor_local_key_t key, VALUE *val);
 void  rb_ractor_local_storage_value_set(rb_ractor_local_key_t key, VALUE val);
 
 RUBY_EXTERN const struct rb_ractor_local_storage_type rb_ractor_local_storage_type_free;
@@ -41,6 +42,9 @@ rb_ractor_local_key_t rb_ractor_local_storage_ptr_newkey(const struct rb_ractor_
 void *rb_ractor_local_storage_ptr(rb_ractor_local_key_t key);
 void  rb_ractor_local_storage_ptr_set(rb_ractor_local_key_t key, void *ptr);
 
+VALUE rb_ractor_make_shareable(VALUE obj);
+VALUE rb_ractor_make_shareable_copy(VALUE obj);
+
 RUBY_SYMBOL_EXPORT_END
 
 #define RB_OBJ_SHAREABLE_P(obj) FL_TEST_RAW((obj), RUBY_FL_SHAREABLE)
@@ -61,7 +65,4 @@ rb_ractor_shareable_p(VALUE obj)
     }
 }
 
-VALUE rb_ractor_make_shareable(VALUE obj);
-VALUE rb_ractor_make_shareable_copy(VALUE obj);
-
 #endif /* RUBY_RACTOR_H */

ractor.c

@@ -3128,6 +3128,17 @@ rb_ractor_local_storage_value(rb_ractor_local_key_t key)
     }
 }
 
+bool
+rb_ractor_local_storage_value_lookup(rb_ractor_local_key_t key, VALUE *val)
+{
+    if (ractor_local_ref(key, (void **)val)) {
+        return true;
+    }
+    else {
+        return false;
+    }
+}
+
 void
 rb_ractor_local_storage_value_set(rb_ractor_local_key_t key, VALUE val)
 {

vm_core.h

@@ -1085,9 +1085,11 @@ typedef struct {
     unsigned int is_isolated: 1;        /* bool */
 } rb_proc_t;
 
+RUBY_SYMBOL_EXPORT_BEGIN
 VALUE rb_proc_isolate(VALUE self);
 VALUE rb_proc_isolate_bang(VALUE self);
 VALUE rb_proc_ractor_make_shareable(VALUE self);
+RUBY_SYMBOL_EXPORT_END
 
 typedef struct {
     VALUE flags; /* imemo header */