X-Git-Url: https://git.llucax.com/software/libev.git/blobdiff_plain/759051fdbf8b3370705e05dac2e2d7525d882e4c..3360a3869a421bc12a57dcd0a9450ef5ee8a11ec:/ev.pod

diff --git a/ev.pod b/ev.pod
index 063c01d..ee162ca 100644
--- a/ev.pod
+++ b/ev.pod
@@ -913,6 +913,30 @@ whether a file descriptor is really ready with a known-to-be good interface
 such as poll (fortunately in our Xlib example, Xlib already does this on
 its own, so its quite safe to use).
 
+=head3 The special problem of disappearing file descriptors
+
+Some backends (e.g kqueue, epoll) need to be told about closing a file
+descriptor (either by calling C<close> explicitly or by any other means,
+such as C<dup>). The reason is that you register interest in some file
+descriptor, but when it goes away, the operating system will silently drop
+this interest. If another file descriptor with the same number then is
+registered with libev, there is no efficient way to see that this is, in
+fact, a different file descriptor.
+
+To avoid having to explicitly tell libev about such cases, libev follows
+the following policy:  Each time C<ev_io_set> is being called, libev
+will assume that this is potentially a new file descriptor, otherwise
+it is assumed that the file descriptor stays the same. That means that
+you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the
+descriptor even if the file descriptor number itself did not change.
+
+This is how one would do it normally anyway, the important point is that
+the libev application should not optimise around libev but should leave
+optimisations to libev.
+
+
+=head3 Watcher-Specific Functions
+
 =over 4
 
 =item ev_io_init (ev_io *, callback, int fd, int events)
@@ -975,6 +999,8 @@ The callback is guarenteed to be invoked only when its timeout has passed,
 but if multiple timers become ready during the same loop iteration then
 order of execution is undefined.
 
+=head3 Watcher-Specific Functions and Data Members
+
 =over 4
 
 =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
@@ -1089,6 +1115,8 @@ As with timers, the callback is guarenteed to be invoked only when the
 time (C<at>) has been passed, but if multiple periodic timers become ready
 during the same loop iteration then order of execution is undefined.
 
+=head3 Watcher-Specific Functions and Data Members
+
 =over 4
 
 =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)
@@ -1244,6 +1272,8 @@ as you don't register any with libev). Similarly, when the last signal
 watcher for a signal is stopped libev will reset the signal handler to
 SIG_DFL (regardless of what it was set to before).
 
+=head3 Watcher-Specific Functions and Data Members
+
 =over 4
 
 =item ev_signal_init (ev_signal *, callback, int signum)
@@ -1265,6 +1295,8 @@ The signal the watcher watches out for.
 Child watchers trigger when your process receives a SIGCHLD in response to
 some child status changes (most typically when a child of yours dies).
 
+=head3 Watcher-Specific Functions and Data Members
+
 =over 4
 
 =item ev_child_init (ev_child *, callback, int pid)
@@ -1342,6 +1374,8 @@ to fall back to regular polling again even with inotify, but changes are
 usually detected immediately, and if the file exists there will be no
 polling.
 
+=head3 Watcher-Specific Functions and Data Members
+
 =over 4
 
 =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)
@@ -1433,6 +1467,8 @@ effect on its own sometimes), idle watchers are a good place to do
 "pseudo-background processing", or delay processing stuff to after the
 event loop has handled all outstanding events.
 
+=head3 Watcher-Specific Functions and Data Members
+
 =over 4
 
 =item ev_idle_init (ev_signal *, callback)
@@ -1509,6 +1545,8 @@ loops those other event loops might be in an unusable state until their
 C<ev_check> watcher ran (always remind yourself to coexist peacefully with
 others).
 
+=head3 Watcher-Specific Functions and Data Members
+
 =over 4
 
 =item ev_prepare_init (ev_prepare *, callback)
@@ -1719,6 +1757,8 @@ create it, and if that fails, use the normal loop for everything:
   else
     loop_lo = loop_hi;
 
+=head3 Watcher-Specific Functions and Data Members
+
 =over 4
 
 =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)