[ViewVC] Diff of: cvs/libev/ev.html

Comparing libev/ev.html (file contents):
Revision 1.71 by root, Sat Dec 8 14:31:45 2007 UTC vs.
Revision 1.72 by root, Sat Dec 8 15:30:29 2007 UTC

…		…
4	<head>	4	<head>
5	<title>libev</title>	5	<title>libev</title>
6	<meta name="description" content="Pod documentation for libev" />	6	<meta name="description" content="Pod documentation for libev" />
7	<meta name="inputfile" content="<standard input>" />	7	<meta name="inputfile" content="<standard input>" />
8	<meta name="outputfile" content="<standard output>" />	8	<meta name="outputfile" content="<standard output>" />
9	<meta name="created" content="Sat Dec 8 15:31:35 2007" />	9	<meta name="created" content="Sat Dec 8 16:30:24 2007" />
10	<meta name="generator" content="Pod::Xhtml 1.57" />	10	<meta name="generator" content="Pod::Xhtml 1.57" />
11	<link rel="stylesheet" href="http://res.tst.eu/pod.css"/></head>	11	<link rel="stylesheet" href="http://res.tst.eu/pod.css"/></head>
12	<body>	12	<body>
13	<div class="pod">	13	<div class="pod">
14	<!-- INDEX START -->	14	<!-- INDEX START -->
…		…
1492	<p>Initialises and configures the prepare or check watcher - they have no	1492	<p>Initialises and configures the prepare or check watcher - they have no
1493	parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code>	1493	parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code>
1494	macros, but using them is utterly, utterly and completely pointless.</p>	1494	macros, but using them is utterly, utterly and completely pointless.</p>
1495	</dd>	1495	</dd>
1496	</dl>	1496	</dl>
1497	<p>Example: To include a library such as adns, you would add IO watchers	1497	<p>There are a number of principal ways to embed other event loops or modules
1498	and a timeout watcher in a prepare handler, as required by libadns, and	1498	into libev. Here are some ideas on how to include libadns into libev
		1499	(there is a Perl module named <code>EV::ADNS</code> that does this, which you could
		1500	use for an actually working example. Another Perl module named <code>EV::Glib</code>
		1501	embeds a Glib main context into libev, and finally, <code>Glib::EV</code> embeds EV
		1502	into the Glib event loop).</p>
		1503	<p>Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1499	in a check watcher, destroy them and call into libadns. What follows is	1504	and in a check watcher, destroy them and call into libadns. What follows
1500	pseudo-code only of course:</p>	1505	is pseudo-code only of course. This requires you to either use a low
		1506	priority for the check watcher or use <code>ev_clear_pending</code> explicitly, as
		1507	the callbacks for the IO/timeout watchers might not have been called yet.</p>
1501	<pre> static ev_io iow [nfd];	1508	<pre> static ev_io iow [nfd];
1502	static ev_timer tw;	1509	static ev_timer tw;
1503		1510
1504	static void	1511	static void
1505	io_cb (ev_loop loop, ev_io w, int revents)	1512	io_cb (ev_loop loop, ev_io w, int revents)
1506	{	1513	{
1507	// set the relevant poll flags
1508	// could also call adns_processreadable etc. here
1509	struct pollfd fd = (struct pollfd )w->data;
1510	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
1511	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
1512	}	1514	}
1513		1515
1514	// create io watchers for each fd and a timer before blocking	1516	// create io watchers for each fd and a timer before blocking
1515	static void	1517	static void
1516	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)	1518	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
…		…
1522		1524
1523	/* the callback is illegal, but won't be called as we stop during check */	1525	/* the callback is illegal, but won't be called as we stop during check */
1524	ev_timer_init (&tw, 0, timeout * 1e-3);	1526	ev_timer_init (&tw, 0, timeout * 1e-3);
1525	ev_timer_start (loop, &tw);	1527	ev_timer_start (loop, &tw);
1526		1528
1527	// create on ev_io per pollfd	1529	// create one ev_io per pollfd
1528	for (int i = 0; i < nfd; ++i)	1530	for (int i = 0; i < nfd; ++i)
1529	{	1531	{
1530	ev_io_init (iow + i, io_cb, fds [i].fd,	1532	ev_io_init (iow + i, io_cb, fds [i].fd,
1531	((fds [i].events & POLLIN ? EV_READ : 0)	1533	((fds [i].events & POLLIN ? EV_READ : 0)
1532	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1534	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1533		1535
1534	fds [i].revents = 0;	1536	fds [i].revents = 0;
1535	iow [i].data = fds + i;
1536	ev_io_start (loop, iow + i);	1537	ev_io_start (loop, iow + i);
1537	}	1538	}
1538	}	1539	}
1539		1540
1540	// stop all watchers after blocking	1541	// stop all watchers after blocking
…		…
1542	adns_check_cb (ev_loop loop, ev_check w, int revents)	1543	adns_check_cb (ev_loop loop, ev_check w, int revents)
1543	{	1544	{
1544	ev_timer_stop (loop, &tw);	1545	ev_timer_stop (loop, &tw);
1545		1546
1546	for (int i = 0; i < nfd; ++i)	1547	for (int i = 0; i < nfd; ++i)
		1548	{
		1549	// set the relevant poll flags
		1550	// could also call adns_processreadable etc. here
		1551	struct pollfd *fd = fds + i;
		1552	int revents = ev_clear_pending (iow + i);
		1553	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
		1554	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
		1555
		1556	// now stop the watcher
1547	ev_io_stop (loop, iow + i);	1557	ev_io_stop (loop, iow + i);
		1558	}
1548		1559
1549	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	1560	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1561	}
		1562
		1563	</pre>
		1564	<p>Method 2: This would be just like method 1, but you run <code>adns_afterpoll</code>
		1565	in the prepare watcher and would dispose of the check watcher.</p>
		1566	<p>Method 3: If the module to be embedded supports explicit event
		1567	notification (adns does), you can also make use of the actual watcher
		1568	callbacks, and only destroy/create the watchers in the prepare watcher.</p>
		1569	<pre> static void
		1570	timer_cb (EV_P_ ev_timer *w, int revents)
		1571	{
		1572	adns_state ads = (adns_state)w->data;
		1573	update_now (EV_A);
		1574
		1575	adns_processtimeouts (ads, &tv_now);
		1576	}
		1577
		1578	static void
		1579	io_cb (EV_P_ ev_io *w, int revents)
		1580	{
		1581	adns_state ads = (adns_state)w->data;
		1582	update_now (EV_A);
		1583
		1584	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
		1585	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
		1586	}
		1587
		1588	// do not ever call adns_afterpoll
		1589
		1590	</pre>
		1591	<p>Method 4: Do not use a prepare or check watcher because the module you
		1592	want to embed is too inflexible to support it. Instead, youc na override
		1593	their poll function. The drawback with this solution is that the main
		1594	loop is now no longer controllable by EV. The <code>Glib::EV</code> module does
		1595	this.</p>
		1596	<pre> static gint
		1597	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
		1598	{
		1599	int got_events = 0;
		1600
		1601	for (n = 0; n < nfds; ++n)
		1602	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
		1603
		1604	if (timeout >= 0)
		1605	// create/start timer
		1606
		1607	// poll
		1608	ev_loop (EV_A_ 0);
		1609
		1610	// stop timer again
		1611	if (timeout >= 0)
		1612	ev_timer_stop (EV_A_ &to);
		1613
		1614	// stop io watchers again - their callbacks should have set
		1615	for (n = 0; n < nfds; ++n)
		1616	ev_io_stop (EV_A_ iow [n]);
		1617
		1618	return got_events;
1550	}	1619	}
1551		1620
1552		1621
1553		1622
1554		1623

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Comparing libev/ev.html (file contents): Revision 1.71 by root, Sat Dec 8 14:31:45 2007 UTC vs. Revision 1.72 by root, Sat Dec 8 15:30:29 2007 UTC

Diff Legend

Comparing libev/ev.html (file contents):
Revision 1.71 by root, Sat Dec 8 14:31:45 2007 UTC vs.
Revision 1.72 by root, Sat Dec 8 15:30:29 2007 UTC