`rb_thread_lock_native_thread()`

Introduce `rb_thread_lock_native_thread()` to allocate dedicated
native thread to the current Ruby thread for M:N threads.
This C API is similar to Go's `runtime.LockOSThread()`.

Accepted at https://github.com/ruby/dev-meeting-log/blob/master/2023/DevMeeting-2023-08-24.md
(and missed to implement on Ruby 3.3.0)

1 files changed, 13 insertions, 0 deletions

diff --git a/include/ruby/thread.h b/include/ruby/thread.h
index f01d276a29..337f477fd0 100644
--- a/include/ruby/thread.h
+++ b/include/ruby/thread.h
@@ -191,6 +191,19 @@ void *rb_nogvl(void *(*func)(void *), void *data1,
 #define RUBY_CALL_WO_GVL_FLAG_SKIP_CHECK_INTS_
 
 /**
+ * Declare the current Ruby thread should acquire a dedicated
+ * native thread on M:N thread scheduler.
+ *
+ * If a C extension (or a library which the extension relies on) should
+ * keep to run on a native thread (e.g. using thread-local-storage),
+ * this function allocates a dedicated native thread for the thread.
+ *
+ * @return `false` if the thread already running on a dedicated native
+ *         thread. Otherwise `true`.
+ */
+bool rb_thread_lock_native_thread(void);
+
+/**
  * Triggered when a new thread is started.
  *
  * @note       The callback will be called *without* the GVL held.