thread.c: enable ppoll for FreeBSD 11.0 and later

FreeBSD 11.0+ supports ppoll, so we may use it after accounting
for portability differences in how it treats POLLOUT vs POLLHUP
events as mutually exclusive (as documented in the FreeBSD
poll(2) manpage).

For waiting on high-numbered single FDs, this should put
FreeBSD on equal footing with Linux and should allow cheaper
FD readiness checking with sleepy GC in the future.

* thread.c (USE_POLL, POLLERR_SET): define for FreeBSD 11.0+
  (rb_wait_for_single_fd): return all requested events on POLLERR_SET
  io.c (USE_POLL): define for FreeBSD 11.0+

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63427 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 12 insertions, 5 deletions

diff --git a/io.c b/io.c
index 4c724e6166..4c01726c4c 100644
--- a/io.c
+++ b/io.c
@@ -10643,15 +10643,21 @@ maygvl_copy_stream_continue_p(int has_gvl, struct copy_stream_struct *stp)
 }
 
 /* non-Linux poll may not work on all FDs */
-#if defined(HAVE_POLL) && defined(__linux__)
-#  define USE_POLL 1
-#  define IOWAIT_SYSCALL "poll"
-#else
-#  define IOWAIT_SYSCALL "select"
+#if defined(HAVE_POLL)
+#  if defined(__linux__)
+#    define USE_POLL 1
+#  endif
+#  if defined(__FreeBSD_version) && __FreeBSD_version >= 1100000
+#    define USE_POLL 1
+#  endif
+#endif
+
+#ifndef USE_POLL
 #  define USE_POLL 0
 #endif
 
 #if USE_POLL
+#  define IOWAIT_SYSCALL "poll"
 STATIC_ASSERT(pollin_expected, POLLIN == RB_WAITFD_IN);
 STATIC_ASSERT(pollout_expected, POLLOUT == RB_WAITFD_OUT);
 static int
@@ -10665,6 +10671,7 @@ nogvl_wait_for_single_fd(int fd, short events)
     return poll(&fds, 1, -1);
 }
 #else /* !USE_POLL */
+#  define IOWAIT_SYSCALL "select"
 static int
 nogvl_wait_for_single_fd(int fd, short events)
 {