add prepare watcher

README

@@ -54,6 +54,8 @@ to be faster and more correct, and also more featureful. Examples:
   (in libevent, backends have to deal with watchers, thus the problems)
   (epoll backend in libevent: 366 lines, libev: 90 lines, and more features)
 
+- libev handles EBADF gracefully by removing the offending fds.
+
 whats missing?
 
 - evdns, evhttp, bufferevent are missing, libev is only an even library at

ev.c

@@ -326,6 +326,9 @@ siginit (void)
 static struct ev_idle **idles;
 static int idlemax, idlecnt;
 
+static struct ev_prepare **prepares;
+static int preparemax, preparecnt;
+
 static struct ev_check **checks;
 static int checkmax, checkcnt;
 
@@ -555,14 +558,15 @@ void ev_loop (int flags)
   double block;
   ev_loop_done = flags & EVLOOP_ONESHOT ? 1 : 0;
 
-  if (checkcnt)
-    {
-      queue_events ((W *)checks, checkcnt, EV_CHECK);
-      call_pending ();
-    }
-
   do
     {
+      /* queue check watchers (and execute them) */
+      if (checkcnt)
+        {
+          queue_events ((W *)prepares, preparecnt, EV_PREPARE);
+          call_pending ();
+        }
+
       /* update fd-related kernel structures */
       fd_reify ();
 
@@ -598,15 +602,16 @@ void ev_loop (int flags)
       time_update ();
 
       /* queue pending timers and reschedule them */
-      periodics_reify (); /* absolute timers first */
-      timers_reify (); /* relative timers second */
+      timers_reify (); /* relative timers called last */
+      periodics_reify (); /* absolute timers called first */
 
       /* queue idle watchers unless io or timers are pending */
       if (!pendingcnt)
         queue_events ((W *)idles, idlecnt, EV_IDLE);
 
-      /* queue check and possibly idle watchers */
-      queue_events ((W *)checks, checkcnt, EV_CHECK);
+      /* queue check watchers, to be executed first */
+      if (checkcnt)
+        queue_events ((W *)checks, checkcnt, EV_CHECK);
 
       call_pending ();
     }
@@ -835,6 +840,26 @@ void evidle_stop (struct ev_idle *w)
   ev_stop ((W)w);
 }
 
+void evprepare_start (struct ev_prepare *w)
+{
+  if (ev_is_active (w))
+    return;
+
+  ev_start ((W)w, ++preparecnt);
+  array_needsize (prepares, preparemax, preparecnt, );
+  prepares [preparecnt - 1] = w;
+}
+
+void evprepare_stop (struct ev_prepare *w)
+{
+  ev_clear ((W)w);
+  if (ev_is_active (w))
+    return;
+
+  prepares [w->active - 1] = prepares [--preparecnt];
+  ev_stop ((W)w);
+}
+
 void evcheck_start (struct ev_check *w)
 {
   if (ev_is_active (w))

ev.h

@@ -41,7 +41,8 @@ typedef double ev_tstamp;
 #define EV_SIGNAL  0x08
 #define EV_IDLE    0x10
 #define EV_CHECK   0x20
-#define EV_ERROR   (0x3f|0x80)
+#define EV_PREPARE 0x40
+#define EV_ERROR   (0x7f|0x80)
 
 /* can be used to add custom fields to all watchers */
 #ifndef EV_COMMON
@@ -127,7 +128,14 @@ struct ev_idle
   EV_WATCHER (ev_idle);
 };
 
-/* invoked for each run of the mainloop, just before the next blocking vall is initiated */
+/* invoked for each run of the mainloop, just before the blocking call */
+/* you can still change events in any way you like */
+struct ev_prepare
+{
+  EV_WATCHER (ev_prepare);
+};
+
+/* invoked for each run of the mainloop, just after the blocking call */
 struct ev_check
 {
   EV_WATCHER (ev_check);
@@ -168,15 +176,17 @@ void ev_once (int fd, int events, ev_tstamp timeout, void (*cb)(int revents, voi
 #define evtimer_set(ev,after_,repeat_)     do { (ev)->at = (after_); (ev)->repeat = (repeat_); } while (0)
 #define evperiodic_set(ev,at_,interval_)   do { (ev)->at = (at_); (ev)->interval = (interval_); } while (0)
 #define evsignal_set(ev,signum_)           do { (ev)->signum = (signum_); } while (0)
-#define evcheck_set(ev)                    /* nop, yes, this is a serious in-joke */
 #define evidle_set(ev)                     /* nop, yes, this is a serious in-joke */
+#define evprepare_set(ev)                  /* nop, yes, this is a serious in-joke */
+#define evcheck_set(ev)                    /* nop, yes, this is a serious in-joke */
 
 #define evio_init(ev,cb,fd,events)         do { evw_init ((ev), (cb)); evio_set ((ev),(fd),(events)); } while (0)
 #define evtimer_init(ev,cb,after,repeat)   do { evw_init ((ev), (cb)); evtimer_set ((ev),(after),(repeat)); } while (0)
 #define evperiodic_init(ev,cb,at,interval) do { evw_init ((ev), (cb)); evperiodic_set ((ev),(at),(interval)); } while (0)
 #define evsignal_init(ev,cb,signum)        do { evw_init ((ev), (cb)); evsignal_set ((ev), (signum)); } while (0)
-#define evcheck_init(ev,cb)                do { evw_init ((ev), (cb)); evcheck_set ((ev)); } while (0)
 #define evidle_init(ev,cb)                 do { evw_init ((ev), (cb)); evidle_set ((ev)); } while (0)
+#define evprepare_init(ev,cb)              do { evw_init ((ev), (cb)); evprepare_set ((ev)); } while (0)
+#define evcheck_init(ev,cb)                do { evw_init ((ev), (cb)); evcheck_set ((ev)); } while (0)
 
 #define ev_is_active(ev) (0 + (ev)->active) /* true when the watcher has been started */
 
@@ -199,6 +209,9 @@ void evsignal_stop    (struct ev_signal *w);
 void evidle_start     (struct ev_idle *w);
 void evidle_stop      (struct ev_idle *w);
 
+void evprepare_start  (struct ev_prepare *w);
+void evprepare_stop   (struct ev_prepare *w);
+
 void evcheck_start    (struct ev_check *w);
 void evcheck_stop     (struct ev_check *w);
 #endif