kqueue: use EVFILT_USER if available

---------

Signed-off-by: Andy Pan <[email protected]>

src/unix/async.c

@@ -130,14 +130,15 @@ void uv__async_close(uv_async_t* handle) {
 
 
 static void uv__async_io(uv_loop_t* loop, uv__io_t* w, unsigned int events) {
- char buf[1024];
- ssize_t r;
+ assert(w == &loop->async_io_watcher);
+
  struct uv__queue queue;
  struct uv__queue* q;
  uv_async_t* h;
  _Atomic int *pending;
-
- assert(w == &loop->async_io_watcher);
+#if !UV__KQUEUE_EVFILT_USER
+ char buf[1024];
+ ssize_t r;
 
  for (;;) {
  r = read(w->fd, buf, sizeof(buf));
@@ -156,6 +157,7 @@ static void uv__async_io(uv_loop_t* loop, uv__io_t* w, unsigned int events) {
 
  abort();
  }
+#endif
 
  uv__queue_move(&loop->async_handles, &queue);
  while (!uv__queue_empty(&queue)) {
@@ -179,6 +181,14 @@ static void uv__async_io(uv_loop_t* loop, uv__io_t* w, unsigned int events) {
 
 
 static void uv__async_send(uv_loop_t* loop) {
+#if UV__KQUEUE_EVFILT_USER
+ struct kevent ev;
+
+ EV_SET(&ev, loop->async_io_watcher.fd, EVFILT_USER, 0, NOTE_TRIGGER, 0, 0);
+ int err = kevent(loop->backend_fd, &ev, 1, NULL, 0, NULL);
+ if (err == 0)
+ return;
+#else
  const void* buf;
  ssize_t len;
  int fd;
@@ -207,6 +217,7 @@ static void uv__async_send(uv_loop_t* loop) {
  if (r == -1)
  if (errno == EAGAIN || errno == EWOULDBLOCK)
  return;
+#endif
 
  abort();
 }
@@ -224,6 +235,14 @@ static int uv__async_start(uv_loop_t* loop) {
  if (err < 0)
  return UV__ERR(errno);
 
+ pipefd[0] = err;
+ pipefd[1] = -1;
+#elif UV__KQUEUE_EVFILT_USER
+ /* This fd will not be actually used, it's only used as a placeholder. */
+ err = uv__open_cloexec("/dev/null", O_RDONLY);
+ if (err < 0)
+ return err;
+
  pipefd[0] = err;
  pipefd[1] = -1;
 #else

src/unix/core.c

@@ -927,6 +927,22 @@ void uv__io_start(uv_loop_t* loop, uv__io_t* w, unsigned int events) {
  loop->watchers[w->fd] = w;
  loop->nfds++;
  }
+
+#if UV__KQUEUE_EVFILT_USER
+ /* When using EVFILT_USER event to wake up the kqueue, this event must be
+ * registered beforehand. Otherwise, calling kevent() to issue an unregistered
+ * EVFILT_USER event will get an ENOENT.
+ * Since uv__async_send() may happen before uv__io_poll() with multi-threads,
+ * we can't defer this registration of EVFILT_USER event as we did for other
+ * events, but must perform it right away. */
+ if (w == &loop->async_io_watcher) {
+ struct kevent ev;
+ EV_SET(&ev, loop->async_io_watcher.fd, EVFILT_USER, EV_ADD | EV_CLEAR, 0, 0, 0);
+ if (kevent(loop->backend_fd, &ev, 1, NULL, 0, NULL))
+ abort();
+ w->events = w->pevents; 
+ }
+#endif
 }
 
 
@@ -1677,7 +1693,7 @@ int uv_thread_setpriority(uv_thread_t tid, int priority) {
  param.sched_priority = prio;
  r = pthread_setschedparam(tid, policy, &param);
  if (r != 0)
- return UV__ERR(errno); 
+ return UV__ERR(errno);
  }
 
  return 0;

src/unix/internal.h

@@ -35,6 +35,10 @@
 #include <sys/socket.h>
 #include <sys/stat.h>
 #include <sys/types.h>
+#if defined(__APPLE__) || defined(__DragonFly__) || \
+ defined(__FreeBSD__) || defined(__NetBSD__)
+#include <sys/event.h>
+#endif
 
 #define uv__msan_unpoison(p, n) \
  do { \
@@ -483,3 +487,12 @@ int uv__get_constrained_cpu(uv__cpu_constraint* constraint);
 #endif
 
 #endif /* UV_UNIX_INTERNAL_H_ */
+
+/* EVFILT_USER is available since OS X 10.6, DragonFlyBSD 4.0 FreeBSD 8.1
+ * and NetBSD 10.0.
+ */
+#if defined(EVFILT_USER) && defined(NOTE_TRIGGER)
+#define UV__KQUEUE_EVFILT_USER 1
+#else
+#define UV__KQUEUE_EVFILT_USER 0
+#endif

src/unix/kqueue.c

@@ -345,7 +345,11 @@ void uv__io_poll(uv_loop_t* loop, int timeout) {
 
  revents = 0;
 
+#if UV__KQUEUE_EVFILT_USER
+ if (ev->filter == EVFILT_READ || ev->filter == EVFILT_USER) {
+#else
  if (ev->filter == EVFILT_READ) {
+#endif
  if (w->pevents & POLLIN)
  revents |= POLLIN;
  else