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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="&lt;standard input&gt;" /> 7 <meta name="inputfile" content="&lt;standard input&gt;" />
8 <meta name="outputfile" content="&lt;standard output&gt;" /> 8 <meta name="outputfile" content="&lt;standard output&gt;" />
9 <meta name="created" content="Fri Nov 23 17:17:04 2007" /> 9 <meta name="created" content="Sat Nov 24 17:57:37 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 -->
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21<li><a href="#CONVENTIONS">CONVENTIONS</a></li> 21<li><a href="#CONVENTIONS">CONVENTIONS</a></li>
22<li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li> 22<li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li>
23<li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li> 23<li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li>
24<li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li> 24<li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li>
25<li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a> 25<li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a>
26<ul><li><a href="#GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</a></li>
26<ul><li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li> 27<li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li>
27</ul> 28</ul>
28</li> 29</li>
29<li><a href="#WATCHER_TYPES">WATCHER TYPES</a> 30<li><a href="#WATCHER_TYPES">WATCHER TYPES</a>
30<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> 31<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>
31<li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</a></li> 32<li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</a></li>
32<li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</a></li> 33<li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</a></li>
33<li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</a></li> 34<li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</a></li>
34<li><a href="#code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</a></li> 35<li><a href="#code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</a></li>
35<li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</a></li> 36<li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</a></li>
36<li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</a></li> 37<li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</a></li>
38<li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</a></li>
37</ul> 39</ul>
38</li> 40</li>
39<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> 41<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>
40<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li> 42<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>
41<li><a href="#C_SUPPORT">C++ SUPPORT</a></li> 43<li><a href="#C_SUPPORT">C++ SUPPORT</a></li>
44<li><a href="#EMBEDDING">EMBEDDING</a>
45<ul><li><a href="#FILESETS">FILESETS</a>
46<ul><li><a href="#CORE_EVENT_LOOP">CORE EVENT LOOP</a></li>
47<li><a href="#LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</a></li>
48<li><a href="#AUTOCONF_SUPPORT">AUTOCONF SUPPORT</a></li>
49</ul>
50</li>
51<li><a href="#PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</a></li>
52<li><a href="#EXAMPLES">EXAMPLES</a></li>
53</ul>
54</li>
42<li><a href="#AUTHOR">AUTHOR</a> 55<li><a href="#AUTHOR">AUTHOR</a>
43</li> 56</li>
44</ul><hr /> 57</ul><hr />
45<!-- INDEX END --> 58<!-- INDEX END -->
46 59
… …
156recommended for this platform. This set is often smaller than the one 169recommended for this platform. This set is often smaller than the one
157returned by <code>ev_supported_backends</code>, as for example kqueue is broken on 170returned by <code>ev_supported_backends</code>, as for example kqueue is broken on
158most BSDs and will not be autodetected unless you explicitly request it 171most BSDs and will not be autodetected unless you explicitly request it
159(assuming you know what you are doing). This is the set of backends that 172(assuming you know what you are doing). This is the set of backends that
160libev will probe for if you specify no backends explicitly.</p> 173libev will probe for if you specify no backends explicitly.</p>
174 </dd>
175 <dt>unsigned int ev_embeddable_backends ()</dt>
176 <dd>
177 <p>Returns the set of backends that are embeddable in other event loops. This
178is the theoretical, all-platform, value. To find which backends
179might be supported on the current system, you would need to look at
180<code>ev_embeddable_backends () &amp; ev_supported_backends ()</code>, likewise for
181recommended ones.</p>
182 <p>See the description of <code>ev_embed</code> watchers for more info.</p>
161 </dd> 183 </dd>
162 <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> 184 <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt>
163 <dd> 185 <dd>
164 <p>Sets the allocation function to use (the prototype is similar to the 186 <p>Sets the allocation function to use (the prototype is similar to the
165realloc C function, the semantics are identical). It is used to allocate 187realloc C function, the semantics are identical). It is used to allocate
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353</pre> 375</pre>
354 </dd> 376 </dd>
355 <dt>ev_default_destroy ()</dt> 377 <dt>ev_default_destroy ()</dt>
356 <dd> 378 <dd>
357 <p>Destroys the default loop again (frees all memory and kernel state 379 <p>Destroys the default loop again (frees all memory and kernel state
358etc.). This stops all registered event watchers (by not touching them in 380etc.). None of the active event watchers will be stopped in the normal
359any way whatsoever, although you cannot rely on this :).</p> 381sense, so e.g. <code>ev_is_active</code> might still return true. It is your
382responsibility to either stop all watchers cleanly yoursef <i>before</i>
383calling this function, or cope with the fact afterwards (which is usually
384the easiest thing, youc na just ignore the watchers and/or <code>free ()</code> them
385for example).</p>
360 </dd> 386 </dd>
361 <dt>ev_loop_destroy (loop)</dt> 387 <dt>ev_loop_destroy (loop)</dt>
362 <dd> 388 <dd>
363 <p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an 389 <p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an
364earlier call to <code>ev_loop_new</code>.</p> 390earlier call to <code>ev_loop_new</code>.</p>
… …
487 513
488</pre> 514</pre>
489 </dd> 515 </dd>
490</dl> 516</dl>
491 517
518
519
520
521
492</div> 522</div>
493<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p> 523<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p>
494<div id="ANATOMY_OF_A_WATCHER_CONTENT"> 524<div id="ANATOMY_OF_A_WATCHER_CONTENT">
495<p>A watcher is a structure that you create and register to record your 525<p>A watcher is a structure that you create and register to record your
496interest in some event. For instance, if you want to wait for STDIN to 526interest in some event. For instance, if you want to wait for STDIN to
… …
525with a watcher-specific start function (<code>ev_&lt;type&gt;_start (loop, watcher 555with a watcher-specific start function (<code>ev_&lt;type&gt;_start (loop, watcher
526*)</code>), and you can stop watching for events at any time by calling the 556*)</code>), and you can stop watching for events at any time by calling the
527corresponding stop function (<code>ev_&lt;type&gt;_stop (loop, watcher *)</code>.</p> 557corresponding stop function (<code>ev_&lt;type&gt;_stop (loop, watcher *)</code>.</p>
528<p>As long as your watcher is active (has been started but not stopped) you 558<p>As long as your watcher is active (has been started but not stopped) you
529must not touch the values stored in it. Most specifically you must never 559must not touch the values stored in it. Most specifically you must never
530reinitialise it or call its set macro.</p> 560reinitialise it or call its <code>set</code> macro.</p>
531<p>You can check whether an event is active by calling the <code>ev_is_active
532(watcher *)</code> macro. To see whether an event is outstanding (but the
533callback for it has not been called yet) you can use the <code>ev_is_pending
534(watcher *)</code> macro.</p>
535<p>Each and every callback receives the event loop pointer as first, the 561<p>Each and every callback receives the event loop pointer as first, the
536registered watcher structure as second, and a bitset of received events as 562registered watcher structure as second, and a bitset of received events as
537third argument.</p> 563third argument.</p>
538<p>The received events usually include a single bit per event type received 564<p>The received events usually include a single bit per event type received
539(you can receive multiple events at the same time). The possible bit masks 565(you can receive multiple events at the same time). The possible bit masks
… …
588your callbacks is well-written it can just attempt the operation and cope 614your callbacks is well-written it can just attempt the operation and cope
589with the error from read() or write(). This will not work in multithreaded 615with the error from read() or write(). This will not work in multithreaded
590programs, though, so beware.</p> 616programs, though, so beware.</p>
591 </dd> 617 </dd>
592</dl> 618</dl>
619
620</div>
621<h2 id="GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</h2>
622<div id="GENERIC_WATCHER_FUNCTIONS_CONTENT">
623<p>In the following description, <code>TYPE</code> stands for the watcher type,
624e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p>
625<dl>
626 <dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt>
627 <dd>
628 <p>This macro initialises the generic portion of a watcher. The contents
629of the watcher object can be arbitrary (so <code>malloc</code> will do). Only
630the generic parts of the watcher are initialised, you <i>need</i> to call
631the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the
632type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro
633which rolls both calls into one.</p>
634 <p>You can reinitialise a watcher at any time as long as it has been stopped
635(or never started) and there are no pending events outstanding.</p>
636 <p>The callback is always of type <code>void (*)(ev_loop *loop, ev_TYPE *watcher,
637int revents)</code>.</p>
638 </dd>
639 <dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt>
640 <dd>
641 <p>This macro initialises the type-specific parts of a watcher. You need to
642call <code>ev_init</code> at least once before you call this macro, but you can
643call <code>ev_TYPE_set</code> any number of times. You must not, however, call this
644macro on a watcher that is active (it can be pending, however, which is a
645difference to the <code>ev_init</code> macro).</p>
646 <p>Although some watcher types do not have type-specific arguments
647(e.g. <code>ev_prepare</code>) you still need to call its <code>set</code> macro.</p>
648 </dd>
649 <dt><code>ev_TYPE_init</code> (ev_TYPE *watcher, callback, [args])</dt>
650 <dd>
651 <p>This convinience macro rolls both <code>ev_init</code> and <code>ev_TYPE_set</code> macro
652calls into a single call. This is the most convinient method to initialise
653a watcher. The same limitations apply, of course.</p>
654 </dd>
655 <dt><code>ev_TYPE_start</code> (loop *, ev_TYPE *watcher)</dt>
656 <dd>
657 <p>Starts (activates) the given watcher. Only active watchers will receive
658events. If the watcher is already active nothing will happen.</p>
659 </dd>
660 <dt><code>ev_TYPE_stop</code> (loop *, ev_TYPE *watcher)</dt>
661 <dd>
662 <p>Stops the given watcher again (if active) and clears the pending
663status. It is possible that stopped watchers are pending (for example,
664non-repeating timers are being stopped when they become pending), but
665<code>ev_TYPE_stop</code> ensures that the watcher is neither active nor pending. If
666you want to free or reuse the memory used by the watcher it is therefore a
667good idea to always call its <code>ev_TYPE_stop</code> function.</p>
668 </dd>
669 <dt>bool ev_is_active (ev_TYPE *watcher)</dt>
670 <dd>
671 <p>Returns a true value iff the watcher is active (i.e. it has been started
672and not yet been stopped). As long as a watcher is active you must not modify
673it.</p>
674 </dd>
675 <dt>bool ev_is_pending (ev_TYPE *watcher)</dt>
676 <dd>
677 <p>Returns a true value iff the watcher is pending, (i.e. it has outstanding
678events but its callback has not yet been invoked). As long as a watcher
679is pending (but not active) you must not call an init function on it (but
680<code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to
681libev (e.g. you cnanot <code>free ()</code> it).</p>
682 </dd>
683 <dt>callback = ev_cb (ev_TYPE *watcher)</dt>
684 <dd>
685 <p>Returns the callback currently set on the watcher.</p>
686 </dd>
687 <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt>
688 <dd>
689 <p>Change the callback. You can change the callback at virtually any time
690(modulo threads).</p>
691 </dd>
692</dl>
693
694
695
696
593 697
594</div> 698</div>
595<h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2> 699<h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2>
596<div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2"> 700<div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2">
597<p>Each watcher has, by default, a member <code>void *data</code> that you can change 701<p>Each watcher has, by default, a member <code>void *data</code> that you can change
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634 738
635 739
636 740
637 741
638</div> 742</div>
639<h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</h2> 743<h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</h2>
640<div id="code_ev_io_code_is_this_file_descrip-2"> 744<div id="code_ev_io_code_is_this_file_descrip-2">
641<p>I/O watchers check whether a file descriptor is readable or writable 745<p>I/O watchers check whether a file descriptor is readable or writable
642in each iteration of the event loop (This behaviour is called 746in each iteration of the event loop, or, more precisely, when reading
643level-triggering because you keep receiving events as long as the 747would not block the process and writing would at least be able to write
644condition persists. Remember you can stop the watcher if you don't want to 748some data. This behaviour is called level-triggering because you keep
645act on the event and neither want to receive future events).</p> 749receiving events as long as the condition persists. Remember you can stop
750the watcher if you don't want to act on the event and neither want to
751receive future events.</p>
646<p>In general you can register as many read and/or write event watchers per 752<p>In general you can register as many read and/or write event watchers per
647fd as you want (as long as you don't confuse yourself). Setting all file 753fd as you want (as long as you don't confuse yourself). Setting all file
648descriptors to non-blocking mode is also usually a good idea (but not 754descriptors to non-blocking mode is also usually a good idea (but not
649required if you know what you are doing).</p> 755required if you know what you are doing).</p>
650<p>You have to be careful with dup'ed file descriptors, though. Some backends 756<p>You have to be careful with dup'ed file descriptors, though. Some backends
651(the linux epoll backend is a notable example) cannot handle dup'ed file 757(the linux epoll backend is a notable example) cannot handle dup'ed file
652descriptors correctly if you register interest in two or more fds pointing 758descriptors correctly if you register interest in two or more fds pointing
653to the same underlying file/socket etc. description (that is, they share 759to the same underlying file/socket/etc. description (that is, they share
654the same underlying &quot;file open&quot;).</p> 760the same underlying &quot;file open&quot;).</p>
655<p>If you must do this, then force the use of a known-to-be-good backend 761<p>If you must do this, then force the use of a known-to-be-good backend
656(at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and 762(at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and
657<code>EVBACKEND_POLL</code>).</p> 763<code>EVBACKEND_POLL</code>).</p>
764<p>Another thing you have to watch out for is that it is quite easy to
765receive &quot;spurious&quot; readyness notifications, that is your callback might
766be called with <code>EV_READ</code> but a subsequent <code>read</code>(2) will actually block
767because there is no data. Not only are some backends known to create a
768lot of those (for example solaris ports), it is very easy to get into
769this situation even with a relatively standard program structure. Thus
770it is best to always use non-blocking I/O: An extra <code>read</code>(2) returning
771<code>EAGAIN</code> is far preferable to a program hanging until some data arrives.</p>
772<p>If you cannot run the fd in non-blocking mode (for example you should not
773play around with an Xlib connection), then you have to seperately re-test
774wether a file descriptor is really ready with a known-to-be good interface
775such as poll (fortunately in our Xlib example, Xlib already does this on
776its own, so its quite safe to use).</p>
658<dl> 777<dl>
659 <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> 778 <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt>
660 <dt>ev_io_set (ev_io *, int fd, int events)</dt> 779 <dt>ev_io_set (ev_io *, int fd, int events)</dt>
661 <dd> 780 <dd>
662 <p>Configures an <code>ev_io</code> watcher. The fd is the file descriptor to rceeive 781 <p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to
663events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_READ | 782rceeive events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or
664EV_WRITE</code> to receive the given events.</p> 783<code>EV_READ | EV_WRITE</code> to receive the given events.</p>
665 <p>Please note that most of the more scalable backend mechanisms (for example
666epoll and solaris ports) can result in spurious readyness notifications
667for file descriptors, so you practically need to use non-blocking I/O (and
668treat callback invocation as hint only), or retest separately with a safe
669interface before doing I/O (XLib can do this), or force the use of either
670<code>EVBACKEND_SELECT</code> or <code>EVBACKEND_POLL</code>, which don't suffer from this
671problem. Also note that it is quite easy to have your callback invoked
672when the readyness condition is no longer valid even when employing
673typical ways of handling events, so its a good idea to use non-blocking
674I/O unconditionally.</p>
675 </dd> 784 </dd>
676</dl> 785</dl>
677<p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well 786<p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well
678readable, but only once. Since it is likely line-buffered, you could 787readable, but only once. Since it is likely line-buffered, you could
679attempt to read a whole line in the callback:</p> 788attempt to read a whole line in the callback:</p>
… …
695 804
696 805
697</pre> 806</pre>
698 807
699</div> 808</div>
700<h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</h2> 809<h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</h2>
701<div id="code_ev_timer_code_relative_and_opti-2"> 810<div id="code_ev_timer_code_relative_and_opti-2">
702<p>Timer watchers are simple relative timers that generate an event after a 811<p>Timer watchers are simple relative timers that generate an event after a
703given time, and optionally repeating in regular intervals after that.</p> 812given time, and optionally repeating in regular intervals after that.</p>
704<p>The timers are based on real time, that is, if you register an event that 813<p>The timers are based on real time, that is, if you register an event that
705times out after an hour and you reset your system clock to last years 814times out after an hour and you reset your system clock to last years
… …
781 890
782 891
783</pre> 892</pre>
784 893
785</div> 894</div>
786<h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</h2> 895<h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</h2>
787<div id="code_ev_periodic_code_to_cron_or_not-2"> 896<div id="code_ev_periodic_code_to_cron_or_not-2">
788<p>Periodic watchers are also timers of a kind, but they are very versatile 897<p>Periodic watchers are also timers of a kind, but they are very versatile
789(and unfortunately a bit complex).</p> 898(and unfortunately a bit complex).</p>
790<p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time) 899<p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time)
791but on wallclock time (absolute time). You can tell a periodic watcher 900but on wallclock time (absolute time). You can tell a periodic watcher
792to trigger &quot;at&quot; some specific point in time. For example, if you tell a 901to trigger &quot;at&quot; some specific point in time. For example, if you tell a
793periodic watcher to trigger in 10 seconds (by specifiying e.g. c&lt;ev_now () 902periodic watcher to trigger in 10 seconds (by specifiying e.g. <code>ev_now ()
794+ 10.&gt;) and then reset your system clock to the last year, then it will 903+ 10.</code>) and then reset your system clock to the last year, then it will
795take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger 904take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger
796roughly 10 seconds later and of course not if you reset your system time 905roughly 10 seconds later and of course not if you reset your system time
797again).</p> 906again).</p>
798<p>They can also be used to implement vastly more complex timers, such as 907<p>They can also be used to implement vastly more complex timers, such as
799triggering an event on eahc midnight, local time.</p> 908triggering an event on eahc midnight, local time.</p>
… …
910 1019
911 1020
912</pre> 1021</pre>
913 1022
914</div> 1023</div>
915<h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</h2> 1024<h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</h2>
916<div id="code_ev_signal_code_signal_me_when_a-2"> 1025<div id="code_ev_signal_code_signal_me_when_a-2">
917<p>Signal watchers will trigger an event when the process receives a specific 1026<p>Signal watchers will trigger an event when the process receives a specific
918signal one or more times. Even though signals are very asynchronous, libev 1027signal one or more times. Even though signals are very asynchronous, libev
919will try it's best to deliver signals synchronously, i.e. as part of the 1028will try it's best to deliver signals synchronously, i.e. as part of the
920normal event processing, like any other event.</p> 1029normal event processing, like any other event.</p>
… …
931 <p>Configures the watcher to trigger on the given signal number (usually one 1040 <p>Configures the watcher to trigger on the given signal number (usually one
932of the <code>SIGxxx</code> constants).</p> 1041of the <code>SIGxxx</code> constants).</p>
933 </dd> 1042 </dd>
934</dl> 1043</dl>
935 1044
1045
1046
1047
1048
936</div> 1049</div>
937<h2 id="code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</h2> 1050<h2 id="code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</h2>
938<div id="code_ev_child_code_wait_for_pid_stat-2"> 1051<div id="code_ev_child_code_watch_out_for_pro-2">
939<p>Child watchers trigger when your process receives a SIGCHLD in response to 1052<p>Child watchers trigger when your process receives a SIGCHLD in response to
940some child status changes (most typically when a child of yours dies).</p> 1053some child status changes (most typically when a child of yours dies).</p>
941<dl> 1054<dl>
942 <dt>ev_child_init (ev_child *, callback, int pid)</dt> 1055 <dt>ev_child_init (ev_child *, callback, int pid)</dt>
943 <dt>ev_child_set (ev_child *, int pid)</dt> 1056 <dt>ev_child_set (ev_child *, int pid)</dt>
… …
965 1078
966 1079
967</pre> 1080</pre>
968 1081
969</div> 1082</div>
970<h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</h2> 1083<h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2>
971<div id="code_ev_idle_code_when_you_ve_got_no-2"> 1084<div id="code_ev_idle_code_when_you_ve_got_no-2">
972<p>Idle watchers trigger events when there are no other events are pending 1085<p>Idle watchers trigger events when there are no other events are pending
973(prepare, check and other idle watchers do not count). That is, as long 1086(prepare, check and other idle watchers do not count). That is, as long
974as your process is busy handling sockets or timeouts (or even signals, 1087as your process is busy handling sockets or timeouts (or even signals,
975imagine) it will not be triggered. But when your process is idle all idle 1088imagine) it will not be triggered. But when your process is idle all idle
… …
1008 1121
1009 1122
1010</pre> 1123</pre>
1011 1124
1012</div> 1125</div>
1013<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</h2> 1126<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</h2>
1014<div id="code_ev_prepare_code_and_code_ev_che-2"> 1127<div id="code_ev_prepare_code_and_code_ev_che-2">
1015<p>Prepare and check watchers are usually (but not always) used in tandem: 1128<p>Prepare and check watchers are usually (but not always) used in tandem:
1016prepare watchers get invoked before the process blocks and check watchers 1129prepare watchers get invoked before the process blocks and check watchers
1017afterwards.</p> 1130afterwards.</p>
1018<p>Their main purpose is to integrate other event mechanisms into libev. This 1131<p>Their main purpose is to integrate other event mechanisms into libev and
1019could be used, for example, to track variable changes, implement your own 1132their use is somewhat advanced. This could be used, for example, to track
1020watchers, integrate net-snmp or a coroutine library and lots more.</p> 1133variable changes, implement your own watchers, integrate net-snmp or a
1134coroutine library and lots more.</p>
1021<p>This is done by examining in each prepare call which file descriptors need 1135<p>This is done by examining in each prepare call which file descriptors need
1022to be watched by the other library, registering <code>ev_io</code> watchers for 1136to be watched by the other library, registering <code>ev_io</code> watchers for
1023them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries 1137them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries
1024provide just this functionality). Then, in the check watcher you check for 1138provide just this functionality). Then, in the check watcher you check for
1025any events that occured (by checking the pending status of all watchers 1139any events that occured (by checking the pending status of all watchers
… …
1042parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code> 1156parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code>
1043macros, but using them is utterly, utterly and completely pointless.</p> 1157macros, but using them is utterly, utterly and completely pointless.</p>
1044 </dd> 1158 </dd>
1045</dl> 1159</dl>
1046<p>Example: *TODO*.</p> 1160<p>Example: *TODO*.</p>
1161
1162
1163
1164
1165
1166</div>
1167<h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</h2>
1168<div id="code_ev_embed_code_when_one_backend_-2">
1169<p>This is a rather advanced watcher type that lets you embed one event loop
1170into another (currently only <code>ev_io</code> events are supported in the embedded
1171loop, other types of watchers might be handled in a delayed or incorrect
1172fashion and must not be used).</p>
1173<p>There are primarily two reasons you would want that: work around bugs and
1174prioritise I/O.</p>
1175<p>As an example for a bug workaround, the kqueue backend might only support
1176sockets on some platform, so it is unusable as generic backend, but you
1177still want to make use of it because you have many sockets and it scales
1178so nicely. In this case, you would create a kqueue-based loop and embed it
1179into your default loop (which might use e.g. poll). Overall operation will
1180be a bit slower because first libev has to poll and then call kevent, but
1181at least you can use both at what they are best.</p>
1182<p>As for prioritising I/O: rarely you have the case where some fds have
1183to be watched and handled very quickly (with low latency), and even
1184priorities and idle watchers might have too much overhead. In this case
1185you would put all the high priority stuff in one loop and all the rest in
1186a second one, and embed the second one in the first.</p>
1187<p>As long as the watcher is active, the callback will be invoked every time
1188there might be events pending in the embedded loop. The callback must then
1189call <code>ev_embed_sweep (mainloop, watcher)</code> to make a single sweep and invoke
1190their callbacks (you could also start an idle watcher to give the embedded
1191loop strictly lower priority for example). You can also set the callback
1192to <code>0</code>, in which case the embed watcher will automatically execute the
1193embedded loop sweep.</p>
1194<p>As long as the watcher is started it will automatically handle events. The
1195callback will be invoked whenever some events have been handled. You can
1196set the callback to <code>0</code> to avoid having to specify one if you are not
1197interested in that.</p>
1198<p>Also, there have not currently been made special provisions for forking:
1199when you fork, you not only have to call <code>ev_loop_fork</code> on both loops,
1200but you will also have to stop and restart any <code>ev_embed</code> watchers
1201yourself.</p>
1202<p>Unfortunately, not all backends are embeddable, only the ones returned by
1203<code>ev_embeddable_backends</code> are, which, unfortunately, does not include any
1204portable one.</p>
1205<p>So when you want to use this feature you will always have to be prepared
1206that you cannot get an embeddable loop. The recommended way to get around
1207this is to have a separate variables for your embeddable loop, try to
1208create it, and if that fails, use the normal loop for everything:</p>
1209<pre> struct ev_loop *loop_hi = ev_default_init (0);
1210 struct ev_loop *loop_lo = 0;
1211 struct ev_embed embed;
1212
1213 // see if there is a chance of getting one that works
1214 // (remember that a flags value of 0 means autodetection)
1215 loop_lo = ev_embeddable_backends () &amp; ev_recommended_backends ()
1216 ? ev_loop_new (ev_embeddable_backends () &amp; ev_recommended_backends ())
1217 : 0;
1218
1219 // if we got one, then embed it, otherwise default to loop_hi
1220 if (loop_lo)
1221 {
1222 ev_embed_init (&amp;embed, 0, loop_lo);
1223 ev_embed_start (loop_hi, &amp;embed);
1224 }
1225 else
1226 loop_lo = loop_hi;
1227
1228</pre>
1229<dl>
1230 <dt>ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)</dt>
1231 <dt>ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)</dt>
1232 <dd>
1233 <p>Configures the watcher to embed the given loop, which must be
1234embeddable. If the callback is <code>0</code>, then <code>ev_embed_sweep</code> will be
1235invoked automatically, otherwise it is the responsibility of the callback
1236to invoke it (it will continue to be called until the sweep has been done,
1237if you do not want thta, you need to temporarily stop the embed watcher).</p>
1238 </dd>
1239 <dt>ev_embed_sweep (loop, ev_embed *)</dt>
1240 <dd>
1241 <p>Make a single, non-blocking sweep over the embedded loop. This works
1242similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most
1243apropriate way for embedded loops.</p>
1244 </dd>
1245</dl>
1047 1246
1048 1247
1049 1248
1050 1249
1051 1250
… …
1082 1281
1083 ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); 1282 ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
1084 1283
1085</pre> 1284</pre>
1086 </dd> 1285 </dd>
1087 <dt>ev_feed_event (loop, watcher, int events)</dt> 1286 <dt>ev_feed_event (ev_loop *, watcher *, int revents)</dt>
1088 <dd> 1287 <dd>
1089 <p>Feeds the given event set into the event loop, as if the specified event 1288 <p>Feeds the given event set into the event loop, as if the specified event
1090had happened for the specified watcher (which must be a pointer to an 1289had happened for the specified watcher (which must be a pointer to an
1091initialised but not necessarily started event watcher).</p> 1290initialised but not necessarily started event watcher).</p>
1092 </dd> 1291 </dd>
1093 <dt>ev_feed_fd_event (loop, int fd, int revents)</dt> 1292 <dt>ev_feed_fd_event (ev_loop *, int fd, int revents)</dt>
1094 <dd> 1293 <dd>
1095 <p>Feed an event on the given fd, as if a file descriptor backend detected 1294 <p>Feed an event on the given fd, as if a file descriptor backend detected
1096the given events it.</p> 1295the given events it.</p>
1097 </dd> 1296 </dd>
1098 <dt>ev_feed_signal_event (loop, int signum)</dt> 1297 <dt>ev_feed_signal_event (ev_loop *loop, int signum)</dt>
1099 <dd> 1298 <dd>
1100 <p>Feed an event as if the given signal occured (loop must be the default loop!).</p> 1299 <p>Feed an event as if the given signal occured (<code>loop</code> must be the default
1300loop!).</p>
1101 </dd> 1301 </dd>
1102</dl> 1302</dl>
1103 1303
1104 1304
1105 1305
… …
1126</dl> 1326</dl>
1127 1327
1128</div> 1328</div>
1129<h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> 1329<h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p>
1130<div id="C_SUPPORT_CONTENT"> 1330<div id="C_SUPPORT_CONTENT">
1131<p>TBD.</p> 1331<p>Libev comes with some simplistic wrapper classes for C++ that mainly allow
1332you to use some convinience methods to start/stop watchers and also change
1333the callback model to a model using method callbacks on objects.</p>
1334<p>To use it,</p>
1335<pre> #include &lt;ev++.h&gt;
1336
1337</pre>
1338<p>(it is not installed by default). This automatically includes <cite>ev.h</cite>
1339and puts all of its definitions (many of them macros) into the global
1340namespace. All C++ specific things are put into the <code>ev</code> namespace.</p>
1341<p>It should support all the same embedding options as <cite>ev.h</cite>, most notably
1342<code>EV_MULTIPLICITY</code>.</p>
1343<p>Here is a list of things available in the <code>ev</code> namespace:</p>
1344<dl>
1345 <dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt>
1346 <dd>
1347 <p>These are just enum values with the same values as the <code>EV_READ</code> etc.
1348macros from <cite>ev.h</cite>.</p>
1349 </dd>
1350 <dt><code>ev::tstamp</code>, <code>ev::now</code></dt>
1351 <dd>
1352 <p>Aliases to the same types/functions as with the <code>ev_</code> prefix.</p>
1353 </dd>
1354 <dt><code>ev::io</code>, <code>ev::timer</code>, <code>ev::periodic</code>, <code>ev::idle</code>, <code>ev::sig</code> etc.</dt>
1355 <dd>
1356 <p>For each <code>ev_TYPE</code> watcher in <cite>ev.h</cite> there is a corresponding class of
1357the same name in the <code>ev</code> namespace, with the exception of <code>ev_signal</code>
1358which is called <code>ev::sig</code> to avoid clashes with the <code>signal</code> macro
1359defines by many implementations.</p>
1360 <p>All of those classes have these methods:</p>
1361 <p>
1362 <dl>
1363 <dt>ev::TYPE::TYPE (object *, object::method *)</dt>
1364 <dt>ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)</dt>
1365 <dt>ev::TYPE::~TYPE</dt>
1366 <dd>
1367 <p>The constructor takes a pointer to an object and a method pointer to
1368the event handler callback to call in this class. The constructor calls
1369<code>ev_init</code> for you, which means you have to call the <code>set</code> method
1370before starting it. If you do not specify a loop then the constructor
1371automatically associates the default loop with this watcher.</p>
1372 <p>The destructor automatically stops the watcher if it is active.</p>
1373 </dd>
1374 <dt>w-&gt;set (struct ev_loop *)</dt>
1375 <dd>
1376 <p>Associates a different <code>struct ev_loop</code> with this watcher. You can only
1377do this when the watcher is inactive (and not pending either).</p>
1378 </dd>
1379 <dt>w-&gt;set ([args])</dt>
1380 <dd>
1381 <p>Basically the same as <code>ev_TYPE_set</code>, with the same args. Must be
1382called at least once. Unlike the C counterpart, an active watcher gets
1383automatically stopped and restarted.</p>
1384 </dd>
1385 <dt>w-&gt;start ()</dt>
1386 <dd>
1387 <p>Starts the watcher. Note that there is no <code>loop</code> argument as the
1388constructor already takes the loop.</p>
1389 </dd>
1390 <dt>w-&gt;stop ()</dt>
1391 <dd>
1392 <p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p>
1393 </dd>
1394 <dt>w-&gt;again () <code>ev::timer</code>, <code>ev::periodic</code> only</dt>
1395 <dd>
1396 <p>For <code>ev::timer</code> and <code>ev::periodic</code>, this invokes the corresponding
1397<code>ev_TYPE_again</code> function.</p>
1398 </dd>
1399 <dt>w-&gt;sweep () <code>ev::embed</code> only</dt>
1400 <dd>
1401 <p>Invokes <code>ev_embed_sweep</code>.</p>
1402 </dd>
1403 </dl>
1404 </p>
1405 </dd>
1406</dl>
1407<p>Example: Define a class with an IO and idle watcher, start one of them in
1408the constructor.</p>
1409<pre> class myclass
1410 {
1411 ev_io io; void io_cb (ev::io &amp;w, int revents);
1412 ev_idle idle void idle_cb (ev::idle &amp;w, int revents);
1413
1414 myclass ();
1415 }
1416
1417 myclass::myclass (int fd)
1418 : io (this, &amp;myclass::io_cb),
1419 idle (this, &amp;myclass::idle_cb)
1420 {
1421 io.start (fd, ev::READ);
1422 }
1423
1424</pre>
1425
1426</div>
1427<h1 id="EMBEDDING">EMBEDDING</h1><p><a href="#TOP" class="toplink">Top</a></p>
1428<div id="EMBEDDING_CONTENT">
1429<p>Libev can (and often is) directly embedded into host
1430applications. Examples of applications that embed it include the Deliantra
1431Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
1432and rxvt-unicode.</p>
1433<p>The goal is to enable you to just copy the neecssary files into your
1434source directory without having to change even a single line in them, so
1435you can easily upgrade by simply copying (or having a checked-out copy of
1436libev somewhere in your source tree).</p>
1437
1438</div>
1439<h2 id="FILESETS">FILESETS</h2>
1440<div id="FILESETS_CONTENT">
1441<p>Depending on what features you need you need to include one or more sets of files
1442in your app.</p>
1443
1444</div>
1445<h3 id="CORE_EVENT_LOOP">CORE EVENT LOOP</h3>
1446<div id="CORE_EVENT_LOOP_CONTENT">
1447<p>To include only the libev core (all the <code>ev_*</code> functions), with manual
1448configuration (no autoconf):</p>
1449<pre> #define EV_STANDALONE 1
1450 #include &quot;ev.c&quot;
1451
1452</pre>
1453<p>This will automatically include <cite>ev.h</cite>, too, and should be done in a
1454single C source file only to provide the function implementations. To use
1455it, do the same for <cite>ev.h</cite> in all files wishing to use this API (best
1456done by writing a wrapper around <cite>ev.h</cite> that you can include instead and
1457where you can put other configuration options):</p>
1458<pre> #define EV_STANDALONE 1
1459 #include &quot;ev.h&quot;
1460
1461</pre>
1462<p>Both header files and implementation files can be compiled with a C++
1463compiler (at least, thats a stated goal, and breakage will be treated
1464as a bug).</p>
1465<p>You need the following files in your source tree, or in a directory
1466in your include path (e.g. in libev/ when using -Ilibev):</p>
1467<pre> ev.h
1468 ev.c
1469 ev_vars.h
1470 ev_wrap.h
1471
1472 ev_win32.c required on win32 platforms only
1473
1474 ev_select.c only when select backend is enabled (which is by default)
1475 ev_poll.c only when poll backend is enabled (disabled by default)
1476 ev_epoll.c only when the epoll backend is enabled (disabled by default)
1477 ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1478 ev_port.c only when the solaris port backend is enabled (disabled by default)
1479
1480</pre>
1481<p><cite>ev.c</cite> includes the backend files directly when enabled, so you only need
1482to compile this single file.</p>
1483
1484</div>
1485<h3 id="LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</h3>
1486<div id="LIBEVENT_COMPATIBILITY_API_CONTENT">
1487<p>To include the libevent compatibility API, also include:</p>
1488<pre> #include &quot;event.c&quot;
1489
1490</pre>
1491<p>in the file including <cite>ev.c</cite>, and:</p>
1492<pre> #include &quot;event.h&quot;
1493
1494</pre>
1495<p>in the files that want to use the libevent API. This also includes <cite>ev.h</cite>.</p>
1496<p>You need the following additional files for this:</p>
1497<pre> event.h
1498 event.c
1499
1500</pre>
1501
1502</div>
1503<h3 id="AUTOCONF_SUPPORT">AUTOCONF SUPPORT</h3>
1504<div id="AUTOCONF_SUPPORT_CONTENT">
1505<p>Instead of using <code>EV_STANDALONE=1</code> and providing your config in
1506whatever way you want, you can also <code>m4_include([libev.m4])</code> in your
1507<cite>configure.ac</cite> and leave <code>EV_STANDALONE</code> undefined. <cite>ev.c</cite> will then
1508include <cite>config.h</cite> and configure itself accordingly.</p>
1509<p>For this of course you need the m4 file:</p>
1510<pre> libev.m4
1511
1512</pre>
1513
1514</div>
1515<h2 id="PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</h2>
1516<div id="PREPROCESSOR_SYMBOLS_MACROS_CONTENT">
1517<p>Libev can be configured via a variety of preprocessor symbols you have to define
1518before including any of its files. The default is not to build for multiplicity
1519and only include the select backend.</p>
1520<dl>
1521 <dt>EV_STANDALONE</dt>
1522 <dd>
1523 <p>Must always be <code>1</code> if you do not use autoconf configuration, which
1524keeps libev from including <cite>config.h</cite>, and it also defines dummy
1525implementations for some libevent functions (such as logging, which is not
1526supported). It will also not define any of the structs usually found in
1527<cite>event.h</cite> that are not directly supported by the libev core alone.</p>
1528 </dd>
1529 <dt>EV_USE_MONOTONIC</dt>
1530 <dd>
1531 <p>If defined to be <code>1</code>, libev will try to detect the availability of the
1532monotonic clock option at both compiletime and runtime. Otherwise no use
1533of the monotonic clock option will be attempted. If you enable this, you
1534usually have to link against librt or something similar. Enabling it when
1535the functionality isn't available is safe, though, althoguh you have
1536to make sure you link against any libraries where the <code>clock_gettime</code>
1537function is hiding in (often <cite>-lrt</cite>).</p>
1538 </dd>
1539 <dt>EV_USE_REALTIME</dt>
1540 <dd>
1541 <p>If defined to be <code>1</code>, libev will try to detect the availability of the
1542realtime clock option at compiletime (and assume its availability at
1543runtime if successful). Otherwise no use of the realtime clock option will
1544be attempted. This effectively replaces <code>gettimeofday</code> by <code>clock_get
1545(CLOCK_REALTIME, ...)</code> and will not normally affect correctness. See tzhe note about libraries
1546in the description of <code>EV_USE_MONOTONIC</code>, though.</p>
1547 </dd>
1548 <dt>EV_USE_SELECT</dt>
1549 <dd>
1550 <p>If undefined or defined to be <code>1</code>, libev will compile in support for the
1551<code>select</code>(2) backend. No attempt at autodetection will be done: if no
1552other method takes over, select will be it. Otherwise the select backend
1553will not be compiled in.</p>
1554 </dd>
1555 <dt>EV_SELECT_USE_FD_SET</dt>
1556 <dd>
1557 <p>If defined to <code>1</code>, then the select backend will use the system <code>fd_set</code>
1558structure. This is useful if libev doesn't compile due to a missing
1559<code>NFDBITS</code> or <code>fd_mask</code> definition or it misguesses the bitset layout on
1560exotic systems. This usually limits the range of file descriptors to some
1561low limit such as 1024 or might have other limitations (winsocket only
1562allows 64 sockets). The <code>FD_SETSIZE</code> macro, set before compilation, might
1563influence the size of the <code>fd_set</code> used.</p>
1564 </dd>
1565 <dt>EV_SELECT_IS_WINSOCKET</dt>
1566 <dd>
1567 <p>When defined to <code>1</code>, the select backend will assume that
1568select/socket/connect etc. don't understand file descriptors but
1569wants osf handles on win32 (this is the case when the select to
1570be used is the winsock select). This means that it will call
1571<code>_get_osfhandle</code> on the fd to convert it to an OS handle. Otherwise,
1572it is assumed that all these functions actually work on fds, even
1573on win32. Should not be defined on non-win32 platforms.</p>
1574 </dd>
1575 <dt>EV_USE_POLL</dt>
1576 <dd>
1577 <p>If defined to be <code>1</code>, libev will compile in support for the <code>poll</code>(2)
1578backend. Otherwise it will be enabled on non-win32 platforms. It
1579takes precedence over select.</p>
1580 </dd>
1581 <dt>EV_USE_EPOLL</dt>
1582 <dd>
1583 <p>If defined to be <code>1</code>, libev will compile in support for the Linux
1584<code>epoll</code>(7) backend. Its availability will be detected at runtime,
1585otherwise another method will be used as fallback. This is the
1586preferred backend for GNU/Linux systems.</p>
1587 </dd>
1588 <dt>EV_USE_KQUEUE</dt>
1589 <dd>
1590 <p>If defined to be <code>1</code>, libev will compile in support for the BSD style
1591<code>kqueue</code>(2) backend. Its actual availability will be detected at runtime,
1592otherwise another method will be used as fallback. This is the preferred
1593backend for BSD and BSD-like systems, although on most BSDs kqueue only
1594supports some types of fds correctly (the only platform we found that
1595supports ptys for example was NetBSD), so kqueue might be compiled in, but
1596not be used unless explicitly requested. The best way to use it is to find
1597out whether kqueue supports your type of fd properly and use an embedded
1598kqueue loop.</p>
1599 </dd>
1600 <dt>EV_USE_PORT</dt>
1601 <dd>
1602 <p>If defined to be <code>1</code>, libev will compile in support for the Solaris
160310 port style backend. Its availability will be detected at runtime,
1604otherwise another method will be used as fallback. This is the preferred
1605backend for Solaris 10 systems.</p>
1606 </dd>
1607 <dt>EV_USE_DEVPOLL</dt>
1608 <dd>
1609 <p>reserved for future expansion, works like the USE symbols above.</p>
1610 </dd>
1611 <dt>EV_H</dt>
1612 <dd>
1613 <p>The name of the <cite>ev.h</cite> header file used to include it. The default if
1614undefined is <code>&lt;ev.h&gt;</code> in <cite>event.h</cite> and <code>&quot;ev.h&quot;</code> in <cite>ev.c</cite>. This
1615can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p>
1616 </dd>
1617 <dt>EV_CONFIG_H</dt>
1618 <dd>
1619 <p>If <code>EV_STANDALONE</code> isn't <code>1</code>, this variable can be used to override
1620<cite>ev.c</cite>'s idea of where to find the <cite>config.h</cite> file, similarly to
1621<code>EV_H</code>, above.</p>
1622 </dd>
1623 <dt>EV_EVENT_H</dt>
1624 <dd>
1625 <p>Similarly to <code>EV_H</code>, this macro can be used to override <cite>event.c</cite>'s idea
1626of how the <cite>event.h</cite> header can be found.</p>
1627 </dd>
1628 <dt>EV_PROTOTYPES</dt>
1629 <dd>
1630 <p>If defined to be <code>0</code>, then <cite>ev.h</cite> will not define any function
1631prototypes, but still define all the structs and other symbols. This is
1632occasionally useful if you want to provide your own wrapper functions
1633around libev functions.</p>
1634 </dd>
1635 <dt>EV_MULTIPLICITY</dt>
1636 <dd>
1637 <p>If undefined or defined to <code>1</code>, then all event-loop-specific functions
1638will have the <code>struct ev_loop *</code> as first argument, and you can create
1639additional independent event loops. Otherwise there will be no support
1640for multiple event loops and there is no first event loop pointer
1641argument. Instead, all functions act on the single default loop.</p>
1642 </dd>
1643 <dt>EV_PERIODICS</dt>
1644 <dd>
1645 <p>If undefined or defined to be <code>1</code>, then periodic timers are supported,
1646otherwise not. This saves a few kb of code.</p>
1647 </dd>
1648 <dt>EV_COMMON</dt>
1649 <dd>
1650 <p>By default, all watchers have a <code>void *data</code> member. By redefining
1651this macro to a something else you can include more and other types of
1652members. You have to define it each time you include one of the files,
1653though, and it must be identical each time.</p>
1654 <p>For example, the perl EV module uses something like this:</p>
1655<pre> #define EV_COMMON \
1656 SV *self; /* contains this struct */ \
1657 SV *cb_sv, *fh /* note no trailing &quot;;&quot; */
1658
1659</pre>
1660 </dd>
1661 <dt>EV_CB_DECLARE (type)</dt>
1662 <dt>EV_CB_INVOKE (watcher, revents)</dt>
1663 <dt>ev_set_cb (ev, cb)</dt>
1664 <dd>
1665 <p>Can be used to change the callback member declaration in each watcher,
1666and the way callbacks are invoked and set. Must expand to a struct member
1667definition and a statement, respectively. See the <cite>ev.v</cite> header file for
1668their default definitions. One possible use for overriding these is to
1669avoid the <code>struct ev_loop *</code> as first argument in all cases, or to use
1670method calls instead of plain function calls in C++.</p>
1671
1672</div>
1673<h2 id="EXAMPLES">EXAMPLES</h2>
1674<div id="EXAMPLES_CONTENT">
1675 <p>For a real-world example of a program the includes libev
1676verbatim, you can have a look at the EV perl module
1677(<a href="http://software.schmorp.de/pkg/EV.html">http://software.schmorp.de/pkg/EV.html</a>). It has the libev files in
1678the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public
1679interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file
1680will be compiled. It is pretty complex because it provides its own header
1681file.</p>
1682 <p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file
1683that everybody includes and which overrides some autoconf choices:</p>
1684<pre> #define EV_USE_POLL 0
1685 #define EV_MULTIPLICITY 0
1686 #define EV_PERIODICS 0
1687 #define EV_CONFIG_H &lt;config.h&gt;
1688
1689 #include &quot;ev++.h&quot;
1690
1691</pre>
1692 <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p>
1693<pre> #include &quot;ev_cpp.h&quot;
1694 #include &quot;ev.c&quot;
1695
1696</pre>
1132 1697
1133</div> 1698</div>
1134<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> 1699<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p>
1135<div id="AUTHOR_CONTENT"> 1700<div id="AUTHOR_CONTENT">
1136<p>Marc Lehmann &lt;libev@schmorp.de&gt;.</p> 1701 <p>Marc Lehmann &lt;libev@schmorp.de&gt;.</p>
1137 1702
1138</div> 1703</div>
1139</div></body> 1704</div></body>
1140</html> 1705</html>

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