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, 2 insertions, 1 deletions

diff --git a/bignum.c b/bignum.c
index ee3b49fd04..5285e5979e 100644
--- a/bignum.c
+++ b/bignum.c
@@ -2572,6 +2572,7 @@ bigdivrem1(void *ptr)
     return 0;
 }
 
+/* async-signal-safe */
 static void
 rb_big_stop(void *ptr)
 {
@@ -2636,7 +2637,7 @@ bigdivrem_restoring(BDIGIT *zds, size_t zn, BDIGIT *yds, size_t yn)
     if (bds.zn > 10000 || bds.yn > 10000) {
       retry:
 	bds.stop = Qfalse;
-	rb_thread_call_without_gvl(bigdivrem1, &bds, rb_big_stop, &bds);
+	rb_nogvl(bigdivrem1, &bds, rb_big_stop, &bds, RB_NOGVL_UBF_ASYNC_SAFE);
 
 	if (bds.stop == Qtrue) {
 	    /* execute trap handler, but exception was not raised. */