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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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14 | <!-- INDEX START --> |
14 | <!-- INDEX START --> |
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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_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</a></li> |
36 | <li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</a></li> |
36 | <li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</a></li> |
37 | </ul> |
37 | </ul> |
38 | </li> |
38 | </li> |
39 | <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> |
40 | <li><a href="#AUTHOR">AUTHOR</a> |
42 | <li><a href="#AUTHOR">AUTHOR</a> |
41 | </li> |
43 | </li> |
42 | </ul><hr /> |
44 | </ul><hr /> |
43 | <!-- INDEX END --> |
45 | <!-- INDEX END --> |
44 | |
46 | |
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99 | to the double type in C.</p> |
101 | to the double type in C.</p> |
100 | |
102 | |
101 | </div> |
103 | </div> |
102 | <h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
104 | <h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
103 | <div id="GLOBAL_FUNCTIONS_CONTENT"> |
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> |
104 | <dl> |
108 | <dl> |
105 | <dt>ev_tstamp ev_time ()</dt> |
109 | <dt>ev_tstamp ev_time ()</dt> |
106 | <dd> |
110 | <dd> |
107 | <p>Returns the current time as libev would use it.</p> |
111 | <p>Returns the current time as libev would use it.</p> |
108 | </dd> |
112 | </dd> |
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567 | <dd> |
571 | <dd> |
568 | <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 |
569 | ignored. Instead, each time the periodic watcher gets scheduled, the |
573 | ignored. Instead, each time the periodic watcher gets scheduled, the |
570 | 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 |
571 | current time as second argument.</p> |
575 | current time as second argument.</p> |
572 | <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, |
573 | 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, |
574 | 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 |
575 | <p>Also, <i>this callback must always return a time that is later than the |
579 | starting a prepare watcher).</p> |
576 | passed <code>now</code> value</i>. Not even <code>now</code> itself will be ok.</p> |
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577 | <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, |
578 | ev_tstamp now)</code>, e.g.:</p> |
581 | ev_tstamp now)</code>, e.g.:</p> |
579 | <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) |
580 | { |
583 | { |
581 | return now + 60.; |
584 | return now + 60.; |
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584 | </pre> |
587 | </pre> |
585 | <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 |
586 | (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 |
587 | 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 |
588 | 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> |
589 | <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 |
590 | 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 |
591 | 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 |
592 | 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> |
593 | </dd> |
599 | </dd> |
594 | </dl> |
600 | </dl> |
595 | </p> |
601 | </p> |
596 | </dd> |
602 | </dd> |
597 | <dt>ev_periodic_again (loop, ev_periodic *)</dt> |
603 | <dt>ev_periodic_again (loop, ev_periodic *)</dt> |
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670 | |
676 | |
671 | </div> |
677 | </div> |
672 | <h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your 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> |
673 | <div id="code_ev_prepare_code_and_code_ev_che-2"> |
679 | <div id="code_ev_prepare_code_and_code_ev_che-2"> |
674 | <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: |
675 | Prepare watchers get invoked before the process blocks and check watchers |
681 | prepare watchers get invoked before the process blocks and check watchers |
676 | afterwards.</p> |
682 | afterwards.</p> |
677 | <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 |
678 | 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 |
679 | 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> |
680 | <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 |
681 | 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 |
682 | 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 |
683 | 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 |
684 | 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 |
685 | 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 |
686 | callbacks will never actually be called (but must be valid neverthelles, |
692 | callbacks will never actually be called (but must be valid nevertheless, |
687 | because you never know, you know?).</p> |
693 | because you never know, you know?).</p> |
688 | <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 |
689 | coroutines into libev programs, by yielding to other active coroutines |
695 | coroutines into libev programs, by yielding to other active coroutines |
690 | 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 |
691 | 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 |
692 | 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 |
693 | 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 |
694 | coroutines exist, thus mapping low-priority coroutines to idle/background |
700 | loop from blocking if lower-priority coroutines are active, thus mapping |
695 | tasks).</p> |
701 | low-priority coroutines to idle/background tasks).</p> |
696 | <dl> |
702 | <dl> |
697 | <dt>ev_prepare_init (ev_prepare *, callback)</dt> |
703 | <dt>ev_prepare_init (ev_prepare *, callback)</dt> |
698 | <dt>ev_check_init (ev_check *, callback)</dt> |
704 | <dt>ev_check_init (ev_check *, callback)</dt> |
699 | <dd> |
705 | <dd> |
700 | <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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754 | <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> |
755 | </dd> |
761 | </dd> |
756 | </dl> |
762 | </dl> |
757 | |
763 | |
758 | </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> |
759 | <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> |
760 | <div id="AUTHOR_CONTENT"> |
776 | <div id="AUTHOR_CONTENT"> |
761 | <p>Marc Lehmann <libev@schmorp.de>.</p> |
777 | <p>Marc Lehmann <libev@schmorp.de>.</p> |
762 | |
778 | |
763 | </div> |
779 | </div> |