KQueue support for M:N threads

* Allows macOS users to use M:N threads (and technically FreeBSD, though it has not been verified on FreeBSD)

* Include sys/event.h header check for macros, and include sys/event.h when present

* Rename epoll_fd to more generic kq_fd (Kernel event Queue) for use by both epoll and kqueue

* MAP_STACK is not available on macOS so conditionall apply it to mmap flags

* Set fd to close on exec

* Log debug messages specific to kqueue and epoll on creation

* close_invalidate raises an error for the kqueue fd on child process fork. It's unclear rn if that's a bug, or if it's kqueue specific behavior

Use kq with rb_thread_wait_for_single_fd

* Only platforms with `USE_POLL` (linux) had changes applied to take advantage of kernel event queues. It needed to be applied to the `select` so that kqueue could be properly applied

* Clean up kqueue specific code and make sure only flags that were actually set are removed (or an error is raised)

* Also handle kevent specific errnos, since most don't apply from epoll to kqueue

* Use the more platform standard close-on-exec approach of `fcntl` and `FD_CLOEXEC`. The io-event gem uses `ioctl`, but fcntl seems to be the recommended choice. It is also what Go, Bun, and Libuv use

* We're making changes in this file anyways - may as well fix a couple spelling mistakes while here

Make sure FD_CLOEXEC carries over in dup

* Otherwise the kqueue descriptor should have FD_CLOEXEC, but doesn't and fails in assert_close_on_exec

1 files changed, 32 insertions, 12 deletions

diff --git a/thread.c b/thread.c
index 30555c6f7f..7c53f958fe 100644
--- a/thread.c
+++ b/thread.c
@@ -4265,6 +4265,27 @@ rb_thread_fd_select(int max, rb_fdset_t * read, rb_fdset_t * write, rb_fdset_t *
     return (int)rb_ensure(do_select, (VALUE)&set, select_set_free, (VALUE)&set);
 }
 
+#ifdef RUBY_THREAD_PTHREAD_H
+
+static bool
+thread_sched_wait_events_timeval(int fd, int events, struct timeval *timeout)
+{
+    rb_thread_t *th = GET_THREAD();
+    rb_hrtime_t rel, *prel;
+
+    if (timeout) {
+        rel = rb_timeval2hrtime(timeout);
+        prel = &rel;
+    }
+    else {
+        prel = NULL;
+    }
+
+    return thread_sched_wait_events(TH_SCHED(th), th, fd, waitfd_to_waiting_flag(events), prel);
+}
+
+#endif
+
 #ifdef USE_POLL
 
 /* The same with linux kernel. TODO: make platform independent definition. */
@@ -4294,18 +4315,8 @@ rb_thread_wait_for_single_fd(int fd, int events, struct timeval *timeout)
     wfd.busy = NULL;
 
 #ifdef RUBY_THREAD_PTHREAD_H
-    if (!th->nt->dedicated) {
-        rb_hrtime_t rel, *prel;
-
-        if (timeout) {
-            rel = rb_timeval2hrtime(timeout);
-            prel = &rel;
-        }
-        else {
-            prel = NULL;
-        }
-
-        if (thread_sched_wait_events(TH_SCHED(th), th, fd, waitfd_to_waiting_flag(events), prel)) {
+    if (!th_has_dedicated_nt(th)) {
+        if (thread_sched_wait_events_timeval(fd, events, timeout)) {
             return 0; // timeout
         }
     }
@@ -4445,6 +4456,15 @@ rb_thread_wait_for_single_fd(int fd, int events, struct timeval *timeout)
     int r;
     VALUE ptr = (VALUE)&args;
 
+#ifdef RUBY_THREAD_PTHREAD_H
+    rb_thread_t *th = GET_THREAD();
+    if (!th_has_dedicated_nt(th)) {
+        if (thread_sched_wait_events_timeval(fd, events, timeout)) {
+            return 0; // timeout
+        }
+    }
+#endif
+
     args.as.fd = fd;
     args.read = (events & RB_WAITFD_IN) ? init_set_fd(fd, &rfds) : NULL;
     args.write = (events & RB_WAITFD_OUT) ? init_set_fd(fd, &wfds) : NULL;