introduce rb_nogvl C-API to mark ubf as async-signal-safe

zlib and bignum both contain unblocking functions which are
async-signal-safe and do not require spawning additional
threads.

We can execute those functions directly in signal handlers
without incurring overhead of extra threads, so provide C-API
users the ability to deal with that.  Other C-API users may
have similar need.

This flexible API can supercede existing uses of
rb_thread_call_without_gvl and rb_thread_call_without_gvl2 by
introducing a flags argument to control behavior.

Note: this API is NOT finalized.  It needs approval from other
committers.  I prefer shorter name than previous
rb_thread_call_without_gvl* functions because my eyes requires
big fonts.

[Bug #15499]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66712 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 5 insertions, 0 deletions

diff --git a/thread_pthread.c b/thread_pthread.c
index d8d3184c62..499da0b9ca 100644
--- a/thread_pthread.c
+++ b/thread_pthread.c
@@ -1542,6 +1542,11 @@ rb_thread_wakeup_timer_thread(int sig)
             if (ec) {
                 RUBY_VM_SET_TRAP_INTERRUPT(ec);
                 ubf_timer_arm(current);
+
+                /* some ubfs can interrupt single-threaded process directly */
+                if (vm->ubf_async_safe && mth->unblock.func) {
+                    (mth->unblock.func)(mth->unblock.arg);
+                }
             }
         }
     }