Bug in kqueue poller fixed (issue 261)

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>

src/kqueue.cpp

@@ -33,6 +33,7 @@
 #include "err.hpp"
 #include "config.hpp"
 #include "i_poll_events.hpp"
+#include "likely.hpp"
 
 //  NetBSD defines (struct kevent).udata as intptr_t, everyone else
 //  as void *.
@@ -106,29 +107,37 @@ void zmq::kqueue_t::rm_fd (handle_t handle_)
 void zmq::kqueue_t::set_pollin (handle_t handle_)
 {
     poll_entry_t *pe = (poll_entry_t*) handle_;
-    pe->flag_pollin = true;
-    kevent_add (pe->fd, EVFILT_READ, pe);
+    if (likely (!pe->flag_pollin)) {
+        pe->flag_pollin = true;
+        kevent_add (pe->fd, EVFILT_READ, pe);
+    }
 }
 
 void zmq::kqueue_t::reset_pollin (handle_t handle_)
 {
     poll_entry_t *pe = (poll_entry_t*) handle_;
-    pe->flag_pollin = false;
-    kevent_delete (pe->fd, EVFILT_READ);
+    if (likely (pe->flag_pollin)) {
+        pe->flag_pollin = false;
+        kevent_delete (pe->fd, EVFILT_READ);
+    }
 }
 
 void zmq::kqueue_t::set_pollout (handle_t handle_)
 {
     poll_entry_t *pe = (poll_entry_t*) handle_;
-    pe->flag_pollout = true;
-    kevent_add (pe->fd, EVFILT_WRITE, pe);
+    if (likely (!pe->flag_pollout)) {
+        pe->flag_pollout = true;
+        kevent_add (pe->fd, EVFILT_WRITE, pe);
+    }
 }
 
 void zmq::kqueue_t::reset_pollout (handle_t handle_)
 {
     poll_entry_t *pe = (poll_entry_t*) handle_;
-    pe->flag_pollout = false;
-    kevent_delete (pe->fd, EVFILT_WRITE);
+    if (likely (pe->flag_pollout)) {
+        pe->flag_pollout = false;
+        kevent_delete (pe->fd, EVFILT_WRITE);
+   }
 }
 
 void zmq::kqueue_t::start ()