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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 11:15:15 2007" /> 9 <meta name="created" content="Mon Nov 26 11:20:35 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>
… …
50</li> 50</li>
51<li><a href="#PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</a></li> 51<li><a href="#PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</a></li>
52<li><a href="#EXAMPLES">EXAMPLES</a></li> 52<li><a href="#EXAMPLES">EXAMPLES</a></li>
53</ul> 53</ul>
54</li> 54</li>
55<li><a href="#COMPLEXITIES">COMPLEXITIES</a></li>
55<li><a href="#AUTHOR">AUTHOR</a> 56<li><a href="#AUTHOR">AUTHOR</a>
56</li> 57</li>
57</ul><hr /> 58</ul><hr />
58<!-- INDEX END --> 59<!-- INDEX END -->
59 60
… …
513 514
514</pre> 515</pre>
515 </dd> 516 </dd>
516</dl> 517</dl>
517 518
519
520
521
522
518</div> 523</div>
519<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p> 524<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p>
520<div id="ANATOMY_OF_A_WATCHER_CONTENT"> 525<div id="ANATOMY_OF_A_WATCHER_CONTENT">
521<p>A watcher is a structure that you create and register to record your 526<p>A watcher is a structure that you create and register to record your
522interest in some event. For instance, if you want to wait for STDIN to 527interest in some event. For instance, if you want to wait for STDIN to
… …
612programs, though, so beware.</p> 617programs, though, so beware.</p>
613 </dd> 618 </dd>
614</dl> 619</dl>
615 620
616</div> 621</div>
617<h2 id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS">SUMMARY OF GENERIC WATCHER FUNCTIONS</h2> 622<h2 id="GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</h2>
618<div id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS-2"> 623<div id="GENERIC_WATCHER_FUNCTIONS_CONTENT">
619<p>In the following description, <code>TYPE</code> stands for the watcher type, 624<p>In the following description, <code>TYPE</code> stands for the watcher type,
620e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p> 625e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p>
621<dl> 626<dl>
622 <dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt> 627 <dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt>
623 <dd> 628 <dd>
… …
627the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the 632the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the
628type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro 633type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro
629which rolls both calls into one.</p> 634which rolls both calls into one.</p>
630 <p>You can reinitialise a watcher at any time as long as it has been stopped 635 <p>You can reinitialise a watcher at any time as long as it has been stopped
631(or never started) and there are no pending events outstanding.</p> 636(or never started) and there are no pending events outstanding.</p>
632 <p>The callbakc is always of type <code>void (*)(ev_loop *loop, ev_TYPE *watcher, 637 <p>The callback is always of type <code>void (*)(ev_loop *loop, ev_TYPE *watcher,
633int revents)</code>.</p> 638int revents)</code>.</p>
634 </dd> 639 </dd>
635 <dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt> 640 <dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt>
636 <dd> 641 <dd>
637 <p>This macro initialises the type-specific parts of a watcher. You need to 642 <p>This macro initialises the type-specific parts of a watcher. You need to
… …
734 739
735 740
736 741
737 742
738</div> 743</div>
739<h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</h2> 744<h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</h2>
740<div id="code_ev_io_code_is_this_file_descrip-2"> 745<div id="code_ev_io_code_is_this_file_descrip-2">
741<p>I/O watchers check whether a file descriptor is readable or writable 746<p>I/O watchers check whether a file descriptor is readable or writable
742in each iteration of the event loop (This behaviour is called 747in each iteration of the event loop, or, more precisely, when reading
743level-triggering because you keep receiving events as long as the 748would not block the process and writing would at least be able to write
744condition persists. Remember you can stop the watcher if you don't want to 749some data. This behaviour is called level-triggering because you keep
745act on the event and neither want to receive future events).</p> 750receiving events as long as the condition persists. Remember you can stop
751the watcher if you don't want to act on the event and neither want to
752receive future events.</p>
746<p>In general you can register as many read and/or write event watchers per 753<p>In general you can register as many read and/or write event watchers per
747fd as you want (as long as you don't confuse yourself). Setting all file 754fd as you want (as long as you don't confuse yourself). Setting all file
748descriptors to non-blocking mode is also usually a good idea (but not 755descriptors to non-blocking mode is also usually a good idea (but not
749required if you know what you are doing).</p> 756required if you know what you are doing).</p>
750<p>You have to be careful with dup'ed file descriptors, though. Some backends 757<p>You have to be careful with dup'ed file descriptors, though. Some backends
751(the linux epoll backend is a notable example) cannot handle dup'ed file 758(the linux epoll backend is a notable example) cannot handle dup'ed file
752descriptors correctly if you register interest in two or more fds pointing 759descriptors correctly if you register interest in two or more fds pointing
753to the same underlying file/socket etc. description (that is, they share 760to the same underlying file/socket/etc. description (that is, they share
754the same underlying &quot;file open&quot;).</p> 761the same underlying &quot;file open&quot;).</p>
755<p>If you must do this, then force the use of a known-to-be-good backend 762<p>If you must do this, then force the use of a known-to-be-good backend
756(at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and 763(at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and
757<code>EVBACKEND_POLL</code>).</p> 764<code>EVBACKEND_POLL</code>).</p>
765<p>Another thing you have to watch out for is that it is quite easy to
766receive &quot;spurious&quot; readyness notifications, that is your callback might
767be called with <code>EV_READ</code> but a subsequent <code>read</code>(2) will actually block
768because there is no data. Not only are some backends known to create a
769lot of those (for example solaris ports), it is very easy to get into
770this situation even with a relatively standard program structure. Thus
771it is best to always use non-blocking I/O: An extra <code>read</code>(2) returning
772<code>EAGAIN</code> is far preferable to a program hanging until some data arrives.</p>
773<p>If you cannot run the fd in non-blocking mode (for example you should not
774play around with an Xlib connection), then you have to seperately re-test
775wether a file descriptor is really ready with a known-to-be good interface
776such as poll (fortunately in our Xlib example, Xlib already does this on
777its own, so its quite safe to use).</p>
758<dl> 778<dl>
759 <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> 779 <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt>
760 <dt>ev_io_set (ev_io *, int fd, int events)</dt> 780 <dt>ev_io_set (ev_io *, int fd, int events)</dt>
761 <dd> 781 <dd>
762 <p>Configures an <code>ev_io</code> watcher. The fd is the file descriptor to rceeive 782 <p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to
763events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_READ | 783rceeive events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or
764EV_WRITE</code> to receive the given events.</p> 784<code>EV_READ | EV_WRITE</code> to receive the given events.</p>
765 <p>Please note that most of the more scalable backend mechanisms (for example
766epoll and solaris ports) can result in spurious readyness notifications
767for file descriptors, so you practically need to use non-blocking I/O (and
768treat callback invocation as hint only), or retest separately with a safe
769interface before doing I/O (XLib can do this), or force the use of either
770<code>EVBACKEND_SELECT</code> or <code>EVBACKEND_POLL</code>, which don't suffer from this
771problem. Also note that it is quite easy to have your callback invoked
772when the readyness condition is no longer valid even when employing
773typical ways of handling events, so its a good idea to use non-blocking
774I/O unconditionally.</p>
775 </dd> 785 </dd>
776</dl> 786</dl>
777<p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well 787<p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well
778readable, but only once. Since it is likely line-buffered, you could 788readable, but only once. Since it is likely line-buffered, you could
779attempt to read a whole line in the callback:</p> 789attempt to read a whole line in the callback:</p>
… …
795 805
796 806
797</pre> 807</pre>
798 808
799</div> 809</div>
800<h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</h2> 810<h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</h2>
801<div id="code_ev_timer_code_relative_and_opti-2"> 811<div id="code_ev_timer_code_relative_and_opti-2">
802<p>Timer watchers are simple relative timers that generate an event after a 812<p>Timer watchers are simple relative timers that generate an event after a
803given time, and optionally repeating in regular intervals after that.</p> 813given time, and optionally repeating in regular intervals after that.</p>
804<p>The timers are based on real time, that is, if you register an event that 814<p>The timers are based on real time, that is, if you register an event that
805times out after an hour and you reset your system clock to last years 815times out after an hour and you reset your system clock to last years
… …
881 891
882 892
883</pre> 893</pre>
884 894
885</div> 895</div>
886<h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</h2> 896<h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</h2>
887<div id="code_ev_periodic_code_to_cron_or_not-2"> 897<div id="code_ev_periodic_code_to_cron_or_not-2">
888<p>Periodic watchers are also timers of a kind, but they are very versatile 898<p>Periodic watchers are also timers of a kind, but they are very versatile
889(and unfortunately a bit complex).</p> 899(and unfortunately a bit complex).</p>
890<p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time) 900<p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time)
891but on wallclock time (absolute time). You can tell a periodic watcher 901but on wallclock time (absolute time). You can tell a periodic watcher
… …
1010 1020
1011 1021
1012</pre> 1022</pre>
1013 1023
1014</div> 1024</div>
1015<h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</h2> 1025<h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</h2>
1016<div id="code_ev_signal_code_signal_me_when_a-2"> 1026<div id="code_ev_signal_code_signal_me_when_a-2">
1017<p>Signal watchers will trigger an event when the process receives a specific 1027<p>Signal watchers will trigger an event when the process receives a specific
1018signal one or more times. Even though signals are very asynchronous, libev 1028signal one or more times. Even though signals are very asynchronous, libev
1019will try it's best to deliver signals synchronously, i.e. as part of the 1029will try it's best to deliver signals synchronously, i.e. as part of the
1020normal event processing, like any other event.</p> 1030normal event processing, like any other event.</p>
… …
1036 1046
1037 1047
1038 1048
1039 1049
1040</div> 1050</div>
1041<h2 id="code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</h2> 1051<h2 id="code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</h2>
1042<div id="code_ev_child_code_wait_for_pid_stat-2"> 1052<div id="code_ev_child_code_watch_out_for_pro-2">
1043<p>Child watchers trigger when your process receives a SIGCHLD in response to 1053<p>Child watchers trigger when your process receives a SIGCHLD in response to
1044some child status changes (most typically when a child of yours dies).</p> 1054some child status changes (most typically when a child of yours dies).</p>
1045<dl> 1055<dl>
1046 <dt>ev_child_init (ev_child *, callback, int pid)</dt> 1056 <dt>ev_child_init (ev_child *, callback, int pid)</dt>
1047 <dt>ev_child_set (ev_child *, int pid)</dt> 1057 <dt>ev_child_set (ev_child *, int pid)</dt>
… …
1069 1079
1070 1080
1071</pre> 1081</pre>
1072 1082
1073</div> 1083</div>
1074<h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</h2> 1084<h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2>
1075<div id="code_ev_idle_code_when_you_ve_got_no-2"> 1085<div id="code_ev_idle_code_when_you_ve_got_no-2">
1076<p>Idle watchers trigger events when there are no other events are pending 1086<p>Idle watchers trigger events when there are no other events are pending
1077(prepare, check and other idle watchers do not count). That is, as long 1087(prepare, check and other idle watchers do not count). That is, as long
1078as your process is busy handling sockets or timeouts (or even signals, 1088as your process is busy handling sockets or timeouts (or even signals,
1079imagine) it will not be triggered. But when your process is idle all idle 1089imagine) it will not be triggered. But when your process is idle all idle
… …
1112 1122
1113 1123
1114</pre> 1124</pre>
1115 1125
1116</div> 1126</div>
1117<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</h2> 1127<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</h2>
1118<div id="code_ev_prepare_code_and_code_ev_che-2"> 1128<div id="code_ev_prepare_code_and_code_ev_che-2">
1119<p>Prepare and check watchers are usually (but not always) used in tandem: 1129<p>Prepare and check watchers are usually (but not always) used in tandem:
1120prepare watchers get invoked before the process blocks and check watchers 1130prepare watchers get invoked before the process blocks and check watchers
1121afterwards.</p> 1131afterwards.</p>
1132<p>You <i>must not</i> call <code>ev_loop</code> or similar functions that enter
1133the current event loop from either <code>ev_prepare</code> or <code>ev_check</code>
1134watchers. Other loops than the current one are fine, however. The
1135rationale behind this is that you do not need to check for recursion in
1136those watchers, i.e. the sequence will always be <code>ev_prepare</code>, blocking,
1137<code>ev_check</code> so if you have one watcher of each kind they will always be
1138called in pairs bracketing the blocking call.</p>
1122<p>Their main purpose is to integrate other event mechanisms into libev and 1139<p>Their main purpose is to integrate other event mechanisms into libev and
1123their use is somewhat advanced. This could be used, for example, to track 1140their use is somewhat advanced. This could be used, for example, to track
1124variable changes, implement your own watchers, integrate net-snmp or a 1141variable changes, implement your own watchers, integrate net-snmp or a
1125coroutine library and lots more.</p> 1142coroutine library and lots more. They are also occasionally useful if
1143you cache some data and want to flush it before blocking (for example,
1144in X programs you might want to do an <code>XFlush ()</code> in an <code>ev_prepare</code>
1145watcher).</p>
1126<p>This is done by examining in each prepare call which file descriptors need 1146<p>This is done by examining in each prepare call which file descriptors need
1127to be watched by the other library, registering <code>ev_io</code> watchers for 1147to be watched by the other library, registering <code>ev_io</code> watchers for
1128them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries 1148them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries
1129provide just this functionality). Then, in the check watcher you check for 1149provide just this functionality). Then, in the check watcher you check for
1130any events that occured (by checking the pending status of all watchers 1150any events that occured (by checking the pending status of all watchers
… …
1146 <p>Initialises and configures the prepare or check watcher - they have no 1166 <p>Initialises and configures the prepare or check watcher - they have no
1147parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code> 1167parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code>
1148macros, but using them is utterly, utterly and completely pointless.</p> 1168macros, but using them is utterly, utterly and completely pointless.</p>
1149 </dd> 1169 </dd>
1150</dl> 1170</dl>
1151<p>Example: *TODO*.</p> 1171<p>Example: To include a library such as adns, you would add IO watchers
1172and a timeout watcher in a prepare handler, as required by libadns, and
1173in a check watcher, destroy them and call into libadns. What follows is
1174pseudo-code only of course:</p>
1175<pre> static ev_io iow [nfd];
1176 static ev_timer tw;
1152 1177
1178 static void
1179 io_cb (ev_loop *loop, ev_io *w, int revents)
1180 {
1181 // set the relevant poll flags
1182 // could also call adns_processreadable etc. here
1183 struct pollfd *fd = (struct pollfd *)w-&gt;data;
1184 if (revents &amp; EV_READ ) fd-&gt;revents |= fd-&gt;events &amp; POLLIN;
1185 if (revents &amp; EV_WRITE) fd-&gt;revents |= fd-&gt;events &amp; POLLOUT;
1186 }
1153 1187
1188 // create io watchers for each fd and a timer before blocking
1189 static void
1190 adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1191 {
1192 int timeout = 3600000;truct pollfd fds [nfd];
1193 // actual code will need to loop here and realloc etc.
1194 adns_beforepoll (ads, fds, &amp;nfd, &amp;timeout, timeval_from (ev_time ()));
1154 1195
1196 /* the callback is illegal, but won't be called as we stop during check */
1197 ev_timer_init (&amp;tw, 0, timeout * 1e-3);
1198 ev_timer_start (loop, &amp;tw);
1155 1199
1200 // create on ev_io per pollfd
1201 for (int i = 0; i &lt; nfd; ++i)
1202 {
1203 ev_io_init (iow + i, io_cb, fds [i].fd,
1204 ((fds [i].events &amp; POLLIN ? EV_READ : 0)
1205 | (fds [i].events &amp; POLLOUT ? EV_WRITE : 0)));
1156 1206
1207 fds [i].revents = 0;
1208 iow [i].data = fds + i;
1209 ev_io_start (loop, iow + i);
1210 }
1211 }
1212
1213 // stop all watchers after blocking
1214 static void
1215 adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1216 {
1217 ev_timer_stop (loop, &amp;tw);
1218
1219 for (int i = 0; i &lt; nfd; ++i)
1220 ev_io_stop (loop, iow + i);
1221
1222 adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1223 }
1224
1225
1226
1227
1228</pre>
1229
1157</div> 1230</div>
1158<h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough</h2> 1231<h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</h2>
1159<div id="code_ev_embed_code_when_one_backend_-2"> 1232<div id="code_ev_embed_code_when_one_backend_-2">
1160<p>This is a rather advanced watcher type that lets you embed one event loop 1233<p>This is a rather advanced watcher type that lets you embed one event loop
1161into another (currently only <code>ev_io</code> events are supported in the embedded 1234into another (currently only <code>ev_io</code> events are supported in the embedded
1162loop, other types of watchers might be handled in a delayed or incorrect 1235loop, other types of watchers might be handled in a delayed or incorrect
1163fashion and must not be used).</p> 1236fashion and must not be used).</p>
… …
1460 ev_vars.h 1533 ev_vars.h
1461 ev_wrap.h 1534 ev_wrap.h
1462 1535
1463 ev_win32.c required on win32 platforms only 1536 ev_win32.c required on win32 platforms only
1464 1537
1465 ev_select.c only when select backend is enabled (which is is by default) 1538 ev_select.c only when select backend is enabled (which is by default)
1466 ev_poll.c only when poll backend is enabled (disabled by default) 1539 ev_poll.c only when poll backend is enabled (disabled by default)
1467 ev_epoll.c only when the epoll backend is enabled (disabled by default) 1540 ev_epoll.c only when the epoll backend is enabled (disabled by default)
1468 ev_kqueue.c only when the kqueue backend is enabled (disabled by default) 1541 ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1469 ev_port.c only when the solaris port backend is enabled (disabled by default) 1542 ev_port.c only when the solaris port backend is enabled (disabled by default)
1470 1543
1471</pre> 1544</pre>
1472<p><cite>ev.c</cite> includes the backend files directly when enabled, so you only need 1545<p><cite>ev.c</cite> includes the backend files directly when enabled, so you only need
1473to compile a single file.</p> 1546to compile this single file.</p>
1474 1547
1475</div> 1548</div>
1476<h3 id="LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</h3> 1549<h3 id="LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</h3>
1477<div id="LIBEVENT_COMPATIBILITY_API_CONTENT"> 1550<div id="LIBEVENT_COMPATIBILITY_API_CONTENT">
1478<p>To include the libevent compatibility API, also include:</p> 1551<p>To include the libevent compatibility API, also include:</p>
… …
1493</div> 1566</div>
1494<h3 id="AUTOCONF_SUPPORT">AUTOCONF SUPPORT</h3> 1567<h3 id="AUTOCONF_SUPPORT">AUTOCONF SUPPORT</h3>
1495<div id="AUTOCONF_SUPPORT_CONTENT"> 1568<div id="AUTOCONF_SUPPORT_CONTENT">
1496<p>Instead of using <code>EV_STANDALONE=1</code> and providing your config in 1569<p>Instead of using <code>EV_STANDALONE=1</code> and providing your config in
1497whatever way you want, you can also <code>m4_include([libev.m4])</code> in your 1570whatever way you want, you can also <code>m4_include([libev.m4])</code> in your
1498<cite>configure.ac</cite> and leave <code>EV_STANDALONE</code> off. <cite>ev.c</cite> will then include 1571<cite>configure.ac</cite> and leave <code>EV_STANDALONE</code> undefined. <cite>ev.c</cite> will then
1499<cite>config.h</cite> and configure itself accordingly.</p> 1572include <cite>config.h</cite> and configure itself accordingly.</p>
1500<p>For this of course you need the m4 file:</p> 1573<p>For this of course you need the m4 file:</p>
1501<pre> libev.m4 1574<pre> libev.m4
1502 1575
1503</pre> 1576</pre>
1504 1577
… …
1583otherwise another method will be used as fallback. This is the preferred 1656otherwise another method will be used as fallback. This is the preferred
1584backend for BSD and BSD-like systems, although on most BSDs kqueue only 1657backend for BSD and BSD-like systems, although on most BSDs kqueue only
1585supports some types of fds correctly (the only platform we found that 1658supports some types of fds correctly (the only platform we found that
1586supports ptys for example was NetBSD), so kqueue might be compiled in, but 1659supports ptys for example was NetBSD), so kqueue might be compiled in, but
1587not be used unless explicitly requested. The best way to use it is to find 1660not be used unless explicitly requested. The best way to use it is to find
1588out wether kqueue supports your type of fd properly and use an embedded 1661out whether kqueue supports your type of fd properly and use an embedded
1589kqueue loop.</p> 1662kqueue loop.</p>
1590 </dd> 1663 </dd>
1591 <dt>EV_USE_PORT</dt> 1664 <dt>EV_USE_PORT</dt>
1592 <dd> 1665 <dd>
1593 <p>If defined to be <code>1</code>, libev will compile in support for the Solaris 1666 <p>If defined to be <code>1</code>, libev will compile in support for the Solaris
… …
1647 SV *self; /* contains this struct */ \ 1720 SV *self; /* contains this struct */ \
1648 SV *cb_sv, *fh /* note no trailing &quot;;&quot; */ 1721 SV *cb_sv, *fh /* note no trailing &quot;;&quot; */
1649 1722
1650</pre> 1723</pre>
1651 </dd> 1724 </dd>
1652 <dt>EV_CB_DECLARE(type)</dt> 1725 <dt>EV_CB_DECLARE (type)</dt>
1653 <dt>EV_CB_INVOKE(watcher,revents)</dt> 1726 <dt>EV_CB_INVOKE (watcher, revents)</dt>
1654 <dt>ev_set_cb(ev,cb)</dt> 1727 <dt>ev_set_cb (ev, cb)</dt>
1655 <dd> 1728 <dd>
1656 <p>Can be used to change the callback member declaration in each watcher, 1729 <p>Can be used to change the callback member declaration in each watcher,
1657and the way callbacks are invoked and set. Must expand to a struct member 1730and the way callbacks are invoked and set. Must expand to a struct member
1658definition and a statement, respectively. See the <cite>ev.v</cite> header file for 1731definition and a statement, respectively. See the <cite>ev.v</cite> header file for
1659their default definitions. One possible use for overriding these is to 1732their default definitions. One possible use for overriding these is to
1660avoid the ev_loop pointer as first argument in all cases, or to use method 1733avoid the <code>struct ev_loop *</code> as first argument in all cases, or to use
1661calls instead of plain function calls in C++.</p> 1734method calls instead of plain function calls in C++.</p>
1662 1735
1663</div> 1736</div>
1664<h2 id="EXAMPLES">EXAMPLES</h2> 1737<h2 id="EXAMPLES">EXAMPLES</h2>
1665<div id="EXAMPLES_CONTENT"> 1738<div id="EXAMPLES_CONTENT">
1666 <p>For a real-world example of a program the includes libev 1739 <p>For a real-world example of a program the includes libev
… …
1682</pre> 1755</pre>
1683 <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p> 1756 <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p>
1684<pre> #include &quot;ev_cpp.h&quot; 1757<pre> #include &quot;ev_cpp.h&quot;
1685 #include &quot;ev.c&quot; 1758 #include &quot;ev.c&quot;
1686 1759
1760
1761
1762
1687</pre> 1763</pre>
1764
1765</div>
1766<h1 id="COMPLEXITIES">COMPLEXITIES</h1><p><a href="#TOP" class="toplink">Top</a></p>
1767<div id="COMPLEXITIES_CONTENT">
1768 <p>In this section the complexities of (many of) the algorithms used inside
1769libev will be explained. For complexity discussions about backends see the
1770documentation for <code>ev_default_init</code>.</p>
1771 <p>
1772 <dl>
1773 <dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt>
1774 <dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt>
1775 <dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt>
1776 <dt>Stopping check/prepare/idle watchers: O(1)</dt>
1777 <dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))</dt>
1778 <dt>Finding the next timer per loop iteration: O(1)</dt>
1779 <dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt>
1780 <dt>Activating one watcher: O(1)</dt>
1781 </dl>
1782 </p>
1783
1784
1785
1786
1688 1787
1689</div> 1788</div>
1690<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> 1789<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p>
1691<div id="AUTHOR_CONTENT"> 1790<div id="AUTHOR_CONTENT">
1692 <p>Marc Lehmann &lt;libev@schmorp.de&gt;.</p> 1791 <p>Marc Lehmann &lt;libev@schmorp.de&gt;.</p>

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