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Diffstat (limited to 'ev.html')
| -rw-r--r-- | ev.html | 31 |
1 files changed, 29 insertions, 2 deletions
@@ -6,7 +6,7 @@ <meta name="description" content="Pod documentation for libev" /> <meta name="inputfile" content="<standard input>" /> <meta name="outputfile" content="<standard output>" /> - <meta name="created" content="Sun Dec 9 20:47:27 2007" /> + <meta name="created" content="Wed Dec 12 05:53:55 2007" /> <meta name="generator" content="Pod::Xhtml 1.57" /> <link rel="stylesheet" href="http://res.tst.eu/pod.css"/></head> <body> @@ -29,7 +29,10 @@ </ul> </li> <li><a href="#WATCHER_TYPES">WATCHER TYPES</a> -<ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</a></li> +<ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</a> +<ul><li><a href="#The_special_problem_of_disappearing_">The special problem of disappearing file descriptors</a></li> +</ul> +</li> <li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</a></li> <li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</a></li> <li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</a></li> @@ -943,6 +946,30 @@ play around with an Xlib connection), then you have to seperately re-test 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).</p> + +</div> +<h3 id="The_special_problem_of_disappearing_">The special problem of disappearing file descriptors</h3> +<div id="The_special_problem_of_disappearing_-2"> +<p>Some backends (e.g kqueue, epoll) need to be told about closing a file +descriptor (either by calling <code>close</code> explicitly or by any other means, +such as <code>dup</code>). 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.</p> +<p>To avoid having to explicitly tell libev about such cases, libev follows +the following policy: Each time <code>ev_io_set</code> 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</i> to call <code>ev_io_set</code> (or <code>ev_io_init</code>) when you change the +descriptor even if the file descriptor number itself did not change.</p> +<p>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.</p> + + + + <dl> <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> <dt>ev_io_set (ev_io *, int fd, int events)</dt> |