Introduce Ractor mechanism for parallel execution

This commit introduces Ractor mechanism to run Ruby program in
parallel. See doc/ractor.md for more details about Ractor.
See ticket [Feature #17100] to see the implementation details
and discussions.

[Feature #17100]

This commit does not complete the implementation. You can find
many bugs on using Ractor. Also the specification will be changed
so that this feature is experimental. You will see a warning when
you make the first Ractor with `Ractor.new`.

I hope this feature can help programmers from thread-safety issues.

1 files changed, 33 insertions, 0 deletions

diff --git a/ractor_pub.h b/ractor_pub.h
new file mode 100644
index 0000000000..5062782b5a
--- /dev/null
+++ b/ractor_pub.h
@@ -0,0 +1,33 @@
+
+int rb_ractor_main_p(void);
+
+bool rb_ractor_shareable_p_continue(VALUE obj);
+
+#define RB_OBJ_SHAREABLE_P(obj) FL_TEST_RAW((obj), RUBY_FL_SHAREABLE)
+
+// TODO: deep frozen
+
+static inline bool
+rb_ractor_shareable_p(VALUE obj)
+{
+    if (SPECIAL_CONST_P(obj)) {
+        return true;
+    }
+    else if (RB_OBJ_SHAREABLE_P(obj)) {
+        return true;
+    }
+    else {
+        return rb_ractor_shareable_p_continue(obj);
+    }
+}
+
+RUBY_SYMBOL_EXPORT_BEGIN
+
+VALUE rb_ractor_stdin(void);
+VALUE rb_ractor_stdout(void);
+VALUE rb_ractor_stderr(void);
+void rb_ractor_stdin_set(VALUE);
+void rb_ractor_stdout_set(VALUE);
+void rb_ractor_stderr_set(VALUE);
+
+RUBY_SYMBOL_EXPORT_END