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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="Sat Nov 24 08:13:46 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="#SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS">SUMMARY OF GENERIC WATCHER FUNCTIONS</a></li> 26<ul><li><a href="#GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</a></li>
27<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>
28</ul> 28</ul>
29</li> 29</li>
30<li><a href="#WATCHER_TYPES">WATCHER TYPES</a> 30<li><a href="#WATCHER_TYPES">WATCHER TYPES</a>
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<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>
32<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>
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_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</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_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</a></li>
35<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>
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_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</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> 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> 38<li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</a></li>
39</ul> 39</ul>
40</li> 40</li>
41<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> 41<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>
42<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li> 42<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>
43<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>
44<li><a href="#AUTHOR">AUTHOR</a> 55<li><a href="#AUTHOR">AUTHOR</a>
45</li> 56</li>
46</ul><hr /> 57</ul><hr />
47<!-- INDEX END --> 58<!-- INDEX END -->
48 59
… …
364</pre> 375</pre>
365 </dd> 376 </dd>
366 <dt>ev_default_destroy ()</dt> 377 <dt>ev_default_destroy ()</dt>
367 <dd> 378 <dd>
368 <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
369etc.). This stops all registered event watchers (by not touching them in 380etc.). None of the active event watchers will be stopped in the normal
370any 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>
371 </dd> 386 </dd>
372 <dt>ev_loop_destroy (loop)</dt> 387 <dt>ev_loop_destroy (loop)</dt>
373 <dd> 388 <dd>
374 <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
375earlier call to <code>ev_loop_new</code>.</p> 390earlier call to <code>ev_loop_new</code>.</p>
… …
498 513
499</pre> 514</pre>
500 </dd> 515 </dd>
501</dl> 516</dl>
502 517
518
519
520
521
503</div> 522</div>
504<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>
505<div id="ANATOMY_OF_A_WATCHER_CONTENT"> 524<div id="ANATOMY_OF_A_WATCHER_CONTENT">
506<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
507interest 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
… …
597programs, though, so beware.</p> 616programs, though, so beware.</p>
598 </dd> 617 </dd>
599</dl> 618</dl>
600 619
601</div> 620</div>
602<h2 id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS">SUMMARY OF GENERIC WATCHER FUNCTIONS</h2> 621<h2 id="GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</h2>
603<div id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS-2"> 622<div id="GENERIC_WATCHER_FUNCTIONS_CONTENT">
604<p>In the following description, <code>TYPE</code> stands for the watcher type, 623<p>In the following description, <code>TYPE</code> stands for the watcher type,
605e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p> 624e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p>
606<dl> 625<dl>
607 <dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt> 626 <dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt>
608 <dd> 627 <dd>
… …
612the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the 631the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the
613type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro 632type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro
614which rolls both calls into one.</p> 633which rolls both calls into one.</p>
615 <p>You can reinitialise a watcher at any time as long as it has been stopped 634 <p>You can reinitialise a watcher at any time as long as it has been stopped
616(or never started) and there are no pending events outstanding.</p> 635(or never started) and there are no pending events outstanding.</p>
617 <p>The callbakc is always of type <code>void (*)(ev_loop *loop, ev_TYPE *watcher, 636 <p>The callback is always of type <code>void (*)(ev_loop *loop, ev_TYPE *watcher,
618int revents)</code>.</p> 637int revents)</code>.</p>
619 </dd> 638 </dd>
620 <dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt> 639 <dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt>
621 <dd> 640 <dd>
622 <p>This macro initialises the type-specific parts of a watcher. You need to 641 <p>This macro initialises the type-specific parts of a watcher. You need to
… …
719 738
720 739
721 740
722 741
723</div> 742</div>
724<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>
725<div id="code_ev_io_code_is_this_file_descrip-2"> 744<div id="code_ev_io_code_is_this_file_descrip-2">
726<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
727in each iteration of the event loop (This behaviour is called 746in each iteration of the event loop, or, more precisely, when reading
728level-triggering because you keep receiving events as long as the 747would not block the process and writing would at least be able to write
729condition persists. Remember you can stop the watcher if you don't want to 748some data. This behaviour is called level-triggering because you keep
730act 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>
731<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
732fd 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
733descriptors 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
734required if you know what you are doing).</p> 755required if you know what you are doing).</p>
735<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
736(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
737descriptors correctly if you register interest in two or more fds pointing 758descriptors correctly if you register interest in two or more fds pointing
738to the same underlying file/socket etc. description (that is, they share 759to the same underlying file/socket/etc. description (that is, they share
739the same underlying &quot;file open&quot;).</p> 760the same underlying &quot;file open&quot;).</p>
740<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
741(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
742<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>
743<dl> 777<dl>
744 <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>
745 <dt>ev_io_set (ev_io *, int fd, int events)</dt> 779 <dt>ev_io_set (ev_io *, int fd, int events)</dt>
746 <dd> 780 <dd>
747 <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
748events 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
749EV_WRITE</code> to receive the given events.</p> 783<code>EV_READ | EV_WRITE</code> to receive the given events.</p>
750 <p>Please note that most of the more scalable backend mechanisms (for example
751epoll and solaris ports) can result in spurious readyness notifications
752for file descriptors, so you practically need to use non-blocking I/O (and
753treat callback invocation as hint only), or retest separately with a safe
754interface before doing I/O (XLib can do this), or force the use of either
755<code>EVBACKEND_SELECT</code> or <code>EVBACKEND_POLL</code>, which don't suffer from this
756problem. Also note that it is quite easy to have your callback invoked
757when the readyness condition is no longer valid even when employing
758typical ways of handling events, so its a good idea to use non-blocking
759I/O unconditionally.</p>
760 </dd> 784 </dd>
761</dl> 785</dl>
762<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
763readable, but only once. Since it is likely line-buffered, you could 787readable, but only once. Since it is likely line-buffered, you could
764attempt to read a whole line in the callback:</p> 788attempt to read a whole line in the callback:</p>
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780 804
781 805
782</pre> 806</pre>
783 807
784</div> 808</div>
785<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>
786<div id="code_ev_timer_code_relative_and_opti-2"> 810<div id="code_ev_timer_code_relative_and_opti-2">
787<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
788given time, and optionally repeating in regular intervals after that.</p> 812given time, and optionally repeating in regular intervals after that.</p>
789<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
790times 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
… …
866 890
867 891
868</pre> 892</pre>
869 893
870</div> 894</div>
871<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>
872<div id="code_ev_periodic_code_to_cron_or_not-2"> 896<div id="code_ev_periodic_code_to_cron_or_not-2">
873<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
874(and unfortunately a bit complex).</p> 898(and unfortunately a bit complex).</p>
875<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)
876but on wallclock time (absolute time). You can tell a periodic watcher 900but on wallclock time (absolute time). You can tell a periodic watcher
877to 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
878periodic 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 ()
879+ 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
880take 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
881roughly 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
882again).</p> 906again).</p>
883<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
884triggering an event on eahc midnight, local time.</p> 908triggering an event on eahc midnight, local time.</p>
… …
995 1019
996 1020
997</pre> 1021</pre>
998 1022
999</div> 1023</div>
1000<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>
1001<div id="code_ev_signal_code_signal_me_when_a-2"> 1025<div id="code_ev_signal_code_signal_me_when_a-2">
1002<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
1003signal one or more times. Even though signals are very asynchronous, libev 1027signal one or more times. Even though signals are very asynchronous, libev
1004will 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
1005normal event processing, like any other event.</p> 1029normal event processing, like any other event.</p>
… …
1021 1045
1022 1046
1023 1047
1024 1048
1025</div> 1049</div>
1026<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>
1027<div id="code_ev_child_code_wait_for_pid_stat-2"> 1051<div id="code_ev_child_code_watch_out_for_pro-2">
1028<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
1029some 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>
1030<dl> 1054<dl>
1031 <dt>ev_child_init (ev_child *, callback, int pid)</dt> 1055 <dt>ev_child_init (ev_child *, callback, int pid)</dt>
1032 <dt>ev_child_set (ev_child *, int pid)</dt> 1056 <dt>ev_child_set (ev_child *, int pid)</dt>
… …
1054 1078
1055 1079
1056</pre> 1080</pre>
1057 1081
1058</div> 1082</div>
1059<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>
1060<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">
1061<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
1062(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
1063as your process is busy handling sockets or timeouts (or even signals, 1087as your process is busy handling sockets or timeouts (or even signals,
1064imagine) 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
… …
1097 1121
1098 1122
1099</pre> 1123</pre>
1100 1124
1101</div> 1125</div>
1102<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>
1103<div id="code_ev_prepare_code_and_code_ev_che-2"> 1127<div id="code_ev_prepare_code_and_code_ev_che-2">
1104<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:
1105prepare watchers get invoked before the process blocks and check watchers 1129prepare watchers get invoked before the process blocks and check watchers
1106afterwards.</p> 1130afterwards.</p>
1107<p>Their main purpose is to integrate other event mechanisms into libev and 1131<p>Their main purpose is to integrate other event mechanisms into libev and
… …
1138 1162
1139 1163
1140 1164
1141 1165
1142</div> 1166</div>
1143<h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough</h2> 1167<h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</h2>
1144<div id="code_ev_embed_code_when_one_backend_-2"> 1168<div id="code_ev_embed_code_when_one_backend_-2">
1145<p>This is a rather advanced watcher type that lets you embed one event loop 1169<p>This is a rather advanced watcher type that lets you embed one event loop
1146into another (currently only <code>ev_io</code> events are supported in the embedded 1170into another (currently only <code>ev_io</code> events are supported in the embedded
1147loop, other types of watchers might be handled in a delayed or incorrect 1171loop, other types of watchers might be handled in a delayed or incorrect
1148fashion and must not be used).</p> 1172fashion and must not be used).</p>
… …
1302</dl> 1326</dl>
1303 1327
1304</div> 1328</div>
1305<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>
1306<div id="C_SUPPORT_CONTENT"> 1330<div id="C_SUPPORT_CONTENT">
1307<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>
1308 1697
1309</div> 1698</div>
1310<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>
1311<div id="AUTHOR_CONTENT"> 1700<div id="AUTHOR_CONTENT">
1312<p>Marc Lehmann &lt;libev@schmorp.de&gt;.</p> 1701 <p>Marc Lehmann &lt;libev@schmorp.de&gt;.</p>
1313 1702
1314</div> 1703</div>
1315</div></body> 1704</div></body>
1316</html> 1705</html>

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