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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" /> |
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9 | <meta name="created" content="Mon Nov 12 09:46:59 2007" /> |
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12 | <body> |
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13 | <div class="pod"> |
13 | <div class="pod"> |
14 | <!-- INDEX START --> |
14 | <!-- INDEX START --> |
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17 | <ul><li><a href="#NAME">NAME</a></li> |
17 | <ul><li><a href="#NAME">NAME</a></li> |
18 | <li><a href="#SYNOPSIS">SYNOPSIS</a></li> |
18 | <li><a href="#SYNOPSIS">SYNOPSIS</a></li> |
19 | <li><a href="#DESCRIPTION">DESCRIPTION</a></li> |
19 | <li><a href="#DESCRIPTION">DESCRIPTION</a></li> |
20 | <li><a href="#FEATURES">FEATURES</a></li> |
20 | <li><a href="#FEATURES">FEATURES</a></li> |
21 | <li><a href="#CONVENTIONS">CONVENTIONS</a></li> |
21 | <li><a href="#CONVENTIONS">CONVENTIONS</a></li> |
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22 | <li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li> |
22 | <li><a href="#TIME_AND_OTHER_GLOBAL_FUNCTIONS">TIME AND OTHER GLOBAL FUNCTIONS</a></li> |
23 | <li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li> |
23 | <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> |
24 | <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> |
25 | <ul><li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li> |
26 | <ul><li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li> |
26 | </ul> |
27 | </ul> |
27 | </li> |
28 | </li> |
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30 | <li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</a></li> |
31 | <li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</a></li> |
31 | <li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</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> |
32 | <li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</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> |
33 | <li><a href="#code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</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> |
34 | <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> |
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> |
35 | <li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - your hooks into the event loop</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> |
36 | </ul> |
37 | </ul> |
37 | </li> |
38 | </li> |
38 | <li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> |
39 | <li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> |
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40 | <li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li> |
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41 | <li><a href="#C_SUPPORT">C++ SUPPORT</a></li> |
39 | <li><a href="#AUTHOR">AUTHOR</a> |
42 | <li><a href="#AUTHOR">AUTHOR</a> |
40 | </li> |
43 | </li> |
41 | </ul><hr /> |
44 | </ul><hr /> |
42 | <!-- INDEX END --> |
45 | <!-- INDEX END --> |
43 | |
46 | |
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87 | support for multiple event loops, then all functions taking an initial |
90 | support for multiple event loops, then all functions taking an initial |
88 | argument of name <code>loop</code> (which is always of type <code>struct ev_loop *</code>) |
91 | argument of name <code>loop</code> (which is always of type <code>struct ev_loop *</code>) |
89 | will not have this argument.</p> |
92 | will not have this argument.</p> |
90 | |
93 | |
91 | </div> |
94 | </div> |
92 | <h1 id="TIME_AND_OTHER_GLOBAL_FUNCTIONS">TIME AND OTHER GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
95 | <h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
93 | <div id="TIME_AND_OTHER_GLOBAL_FUNCTIONS_CONT"> |
96 | <div id="TIME_REPRESENTATION_CONTENT"> |
94 | <p>Libev represents time as a single floating point number, representing the |
97 | <p>Libev represents time as a single floating point number, representing the |
95 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
98 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
96 | the beginning of 1970, details are complicated, don't ask). This type is |
99 | the beginning of 1970, details are complicated, don't ask). This type is |
97 | called <code>ev_tstamp</code>, which is what you should use too. It usually aliases |
100 | called <code>ev_tstamp</code>, which is what you should use too. It usually aliases |
98 | to the double type in C.</p> |
101 | to the double type in C.</p> |
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102 | |
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103 | </div> |
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104 | <h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
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105 | <div id="GLOBAL_FUNCTIONS_CONTENT"> |
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106 | <p>These functions can be called anytime, even before initialising the |
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107 | library in any way.</p> |
99 | <dl> |
108 | <dl> |
100 | <dt>ev_tstamp ev_time ()</dt> |
109 | <dt>ev_tstamp ev_time ()</dt> |
101 | <dd> |
110 | <dd> |
102 | <p>Returns the current time as libev would use it.</p> |
111 | <p>Returns the current time as libev would use it.</p> |
103 | </dd> |
112 | </dd> |
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142 | <div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2"> |
151 | <div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2"> |
143 | <p>An event loop is described by a <code>struct ev_loop *</code>. The library knows two |
152 | <p>An event loop is described by a <code>struct ev_loop *</code>. The library knows two |
144 | types of such loops, the <i>default</i> loop, which supports signals and child |
153 | types of such loops, the <i>default</i> loop, which supports signals and child |
145 | events, and dynamically created loops which do not.</p> |
154 | events, and dynamically created loops which do not.</p> |
146 | <p>If you use threads, a common model is to run the default event loop |
155 | <p>If you use threads, a common model is to run the default event loop |
147 | in your main thread (or in a separate thrad) and for each thread you |
156 | in your main thread (or in a separate thread) and for each thread you |
148 | create, you also create another event loop. Libev itself does no locking |
157 | create, you also create another event loop. Libev itself does no locking |
149 | whatsoever, so if you mix calls to the same event loop in different |
158 | whatsoever, so if you mix calls to the same event loop in different |
150 | threads, make sure you lock (this is usually a bad idea, though, even if |
159 | threads, make sure you lock (this is usually a bad idea, though, even if |
151 | done correctly, because it's hideous and inefficient).</p> |
160 | done correctly, because it's hideous and inefficient).</p> |
152 | <dl> |
161 | <dl> |
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562 | <dd> |
571 | <dd> |
563 | <p>In this mode the values for <code>interval</code> and <code>at</code> are both being |
572 | <p>In this mode the values for <code>interval</code> and <code>at</code> are both being |
564 | ignored. Instead, each time the periodic watcher gets scheduled, the |
573 | ignored. Instead, each time the periodic watcher gets scheduled, the |
565 | reschedule callback will be called with the watcher as first, and the |
574 | reschedule callback will be called with the watcher as first, and the |
566 | current time as second argument.</p> |
575 | current time as second argument.</p> |
567 | <p>NOTE: <i>This callback MUST NOT stop or destroy the periodic or any other |
576 | <p>NOTE: <i>This callback MUST NOT stop or destroy any periodic watcher, |
568 | periodic watcher, ever, or make any event loop modifications</i>. If you need |
577 | ever, or make any event loop modifications</i>. If you need to stop it, |
569 | to stop it, return <code>now + 1e30</code> (or so, fudge fudge) and stop it afterwards.</p> |
578 | return <code>now + 1e30</code> (or so, fudge fudge) and stop it afterwards (e.g. by |
570 | <p>Also, <i>this callback must always return a time that is later than the |
579 | starting a prepare watcher).</p> |
571 | passed <code>now</code> value</i>. Not even <code>now</code> itself will be ok.</p> |
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572 | <p>Its prototype is <code>ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
580 | <p>Its prototype is <code>ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
573 | ev_tstamp now)</code>, e.g.:</p> |
581 | ev_tstamp now)</code>, e.g.:</p> |
574 | <pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
582 | <pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
575 | { |
583 | { |
576 | return now + 60.; |
584 | return now + 60.; |
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579 | </pre> |
587 | </pre> |
580 | <p>It must return the next time to trigger, based on the passed time value |
588 | <p>It must return the next time to trigger, based on the passed time value |
581 | (that is, the lowest time value larger than to the second argument). It |
589 | (that is, the lowest time value larger than to the second argument). It |
582 | will usually be called just before the callback will be triggered, but |
590 | will usually be called just before the callback will be triggered, but |
583 | might be called at other times, too.</p> |
591 | might be called at other times, too.</p> |
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592 | <p>NOTE: <i>This callback must always return a time that is later than the |
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593 | passed <code>now</code> value</i>. Not even <code>now</code> itself will do, it <i>must</i> be larger.</p> |
584 | <p>This can be used to create very complex timers, such as a timer that |
594 | <p>This can be used to create very complex timers, such as a timer that |
585 | triggers on each midnight, local time. To do this, you would calculate the |
595 | triggers on each midnight, local time. To do this, you would calculate the |
586 | next midnight after <code>now</code> and return the timestamp value for this. How you do this |
596 | next midnight after <code>now</code> and return the timestamp value for this. How |
587 | is, again, up to you (but it is not trivial).</p> |
597 | you do this is, again, up to you (but it is not trivial, which is the main |
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598 | reason I omitted it as an example).</p> |
588 | </dd> |
599 | </dd> |
589 | </dl> |
600 | </dl> |
590 | </p> |
601 | </p> |
591 | </dd> |
602 | </dd> |
592 | <dt>ev_periodic_again (loop, ev_periodic *)</dt> |
603 | <dt>ev_periodic_again (loop, ev_periodic *)</dt> |
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662 | believe me.</p> |
673 | believe me.</p> |
663 | </dd> |
674 | </dd> |
664 | </dl> |
675 | </dl> |
665 | |
676 | |
666 | </div> |
677 | </div> |
667 | <h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - your hooks into the event loop</h2> |
678 | <h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</h2> |
668 | <div id="code_ev_prepare_code_and_code_ev_che-2"> |
679 | <div id="code_ev_prepare_code_and_code_ev_che-2"> |
669 | <p>Prepare and check watchers are usually (but not always) used in tandem: |
680 | <p>Prepare and check watchers are usually (but not always) used in tandem: |
670 | Prepare watchers get invoked before the process blocks and check watchers |
681 | prepare watchers get invoked before the process blocks and check watchers |
671 | afterwards.</p> |
682 | afterwards.</p> |
672 | <p>Their main purpose is to integrate other event mechanisms into libev. This |
683 | <p>Their main purpose is to integrate other event mechanisms into libev. This |
673 | could be used, for example, to track variable changes, implement your own |
684 | could be used, for example, to track variable changes, implement your own |
674 | watchers, integrate net-snmp or a coroutine library and lots more.</p> |
685 | watchers, integrate net-snmp or a coroutine library and lots more.</p> |
675 | <p>This is done by examining in each prepare call which file descriptors need |
686 | <p>This is done by examining in each prepare call which file descriptors need |
676 | to be watched by the other library, registering <code>ev_io</code> watchers for |
687 | to be watched by the other library, registering <code>ev_io</code> watchers for |
677 | them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries |
688 | them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries |
678 | provide just this functionality). Then, in the check watcher you check for |
689 | provide just this functionality). Then, in the check watcher you check for |
679 | any events that occured (by checking the pending status of all watchers |
690 | any events that occured (by checking the pending status of all watchers |
680 | and stopping them) and call back into the library. The I/O and timer |
691 | and stopping them) and call back into the library. The I/O and timer |
681 | callbacks will never actually be called (but must be valid neverthelles, |
692 | callbacks will never actually be called (but must be valid nevertheless, |
682 | because you never know, you know?).</p> |
693 | because you never know, you know?).</p> |
683 | <p>As another example, the Perl Coro module uses these hooks to integrate |
694 | <p>As another example, the Perl Coro module uses these hooks to integrate |
684 | coroutines into libev programs, by yielding to other active coroutines |
695 | coroutines into libev programs, by yielding to other active coroutines |
685 | during each prepare and only letting the process block if no coroutines |
696 | during each prepare and only letting the process block if no coroutines |
686 | are ready to run (its actually more complicated, it only runs coroutines |
697 | are ready to run (it's actually more complicated: it only runs coroutines |
687 | with priority higher than the event loop and one lower priority once, |
698 | with priority higher than or equal to the event loop and one coroutine |
688 | using idle watchers to keep the event loop from blocking if lower-priority |
699 | of lower priority, but only once, using idle watchers to keep the event |
689 | coroutines exist, thus mapping low-priority coroutines to idle/background |
700 | loop from blocking if lower-priority coroutines are active, thus mapping |
690 | tasks).</p> |
701 | low-priority coroutines to idle/background tasks).</p> |
691 | <dl> |
702 | <dl> |
692 | <dt>ev_prepare_init (ev_prepare *, callback)</dt> |
703 | <dt>ev_prepare_init (ev_prepare *, callback)</dt> |
693 | <dt>ev_check_init (ev_check *, callback)</dt> |
704 | <dt>ev_check_init (ev_check *, callback)</dt> |
694 | <dd> |
705 | <dd> |
695 | <p>Initialises and configures the prepare or check watcher - they have no |
706 | <p>Initialises and configures the prepare or check watcher - they have no |
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749 | <p>Feed an event as if the given signal occured (loop must be the default loop!).</p> |
760 | <p>Feed an event as if the given signal occured (loop must be the default loop!).</p> |
750 | </dd> |
761 | </dd> |
751 | </dl> |
762 | </dl> |
752 | |
763 | |
753 | </div> |
764 | </div> |
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765 | <h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
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766 | <div id="LIBEVENT_EMULATION_CONTENT"> |
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767 | <p>TBD.</p> |
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768 | |
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769 | </div> |
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770 | <h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> |
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771 | <div id="C_SUPPORT_CONTENT"> |
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772 | <p>TBD.</p> |
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773 | |
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774 | </div> |
754 | <h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> |
775 | <h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> |
755 | <div id="AUTHOR_CONTENT"> |
776 | <div id="AUTHOR_CONTENT"> |
756 | <p>Marc Lehmann <libev@schmorp.de>.</p> |
777 | <p>Marc Lehmann <libev@schmorp.de>.</p> |
757 | |
778 | |
758 | </div> |
779 | </div> |