uloop: improve edge trigger reliability on mac os x

Sometimes after re-arming a fd, an initial event for reads is not generated,
even though there is data pending. Work around this by making the trigger
level-triggered first, then switching to edge trigger after processing the first
event.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

diff --git a/uloop.c b/uloop.c
index bf1721951917c0ae5688f3074a98e1de11a96a9c..2d7b2c93406a498b359d28042ca1408dbe039271 100644 (file)
--- a/uloop.c
+++ b/uloop.c
@@ -90,7 +90,7 @@ static uint16_t get_flags(unsigned int flags, unsigned int mask)
 
 static struct kevent events[ULOOP_MAX_EVENTS];
 
-static int register_poll(struct uloop_fd *fd, unsigned int flags)
+static int register_kevent(struct uloop_fd *fd, unsigned int flags)
 {
        struct timespec timeout = { 0, 0 };
        struct kevent ev[2];
@@ -98,6 +98,9 @@ static int register_poll(struct uloop_fd *fd, unsigned int flags)
        unsigned int fl = 0;
        uint16_t kflags;
 
+       if (flags & ULOOP_EDGE_DEFER)
+               flags &= ~ULOOP_EDGE_TRIGGER;
+
        kflags = get_flags(flags, ULOOP_READ);
        EV_SET(&ev[nev++], fd->fd, EVFILT_READ, kflags, 0, 0, fd);
 
@@ -107,12 +110,23 @@ static int register_poll(struct uloop_fd *fd, unsigned int flags)
        if (!flags)
                fl |= EV_DELETE;
 
-       if (nev && (kevent(poll_fd, ev, nev, NULL, fl, &timeout) == -1))
+       if (kevent(poll_fd, ev, nev, NULL, fl, &timeout) == -1)
                return -1;
 
        return 0;
 }
 
+static int register_poll(struct uloop_fd *fd, unsigned int flags)
+{
+       if (flags & ULOOP_EDGE_TRIGGER)
+               flags |= ULOOP_EDGE_DEFER;
+       else
+               flags &= ~ULOOP_EDGE_DEFER;
+
+       fd->flags = flags;
+       return register_kevent(fd, flags);
+}
+
 int uloop_fd_delete(struct uloop_fd *sock)
 {
        int i;
@@ -166,6 +180,10 @@ static void uloop_run_events(int timeout)
                        cur_fd = n;
                        cur_nfds = nfds;
                        u->cb(u, ev);
+                       if (u->flags & ULOOP_EDGE_DEFER) {
+                               u->flags &= ~ULOOP_EDGE_DEFER;
+                               register_kevent(u, u->flags);
+                       }
                }
        }
        cur_nfds = 0;

diff --git a/uloop.h b/uloop.h
index 4be2913e3e35129de712643e9e99b811580c7601..b5cd0d4ddf9575c1eaf5eb4d1d621d6cffd6ed0a 100644 (file)
--- a/uloop.h
+++ b/uloop.h
@@ -46,6 +46,9 @@ typedef void (*uloop_process_handler)(struct uloop_process *c, int ret);
 #define ULOOP_WRITE            (1 << 1)
 #define ULOOP_EDGE_TRIGGER     (1 << 2)
 #define ULOOP_BLOCKING         (1 << 3)
+#ifdef USE_KQUEUE
+#define ULOOP_EDGE_DEFER       (1 << 4)
+#endif
 
 struct uloop_fd
 {
@@ -54,6 +57,9 @@ struct uloop_fd
        bool eof;
        bool error;
        bool registered;
+#ifdef USE_KQUEUE
+       bool flags;
+#endif
 };
 
 struct uloop_timeout