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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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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> |
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26 | <ul><li><a href="#GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</a></li> |
26 | <ul><li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li> |
27 | <li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li> |
27 | </ul> |
28 | </ul> |
28 | </li> |
29 | </li> |
29 | <li><a href="#WATCHER_TYPES">WATCHER TYPES</a> |
30 | <li><a href="#WATCHER_TYPES">WATCHER TYPES</a> |
30 | <ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</a></li> |
31 | <ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</a></li> |
31 | <li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</a></li> |
32 | <li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</a></li> |
32 | <li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</a></li> |
33 | <li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</a></li> |
33 | <li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</a></li> |
34 | <li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</a></li> |
34 | <li><a href="#code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</a></li> |
35 | <li><a href="#code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</a></li> |
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36 | <li><a href="#code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</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> |
37 | <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> |
38 | <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_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough</a></li> |
39 | <li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</a></li> |
38 | </ul> |
40 | </ul> |
39 | </li> |
41 | </li> |
40 | <li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> |
42 | <li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> |
41 | <li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li> |
43 | <li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li> |
42 | <li><a href="#C_SUPPORT">C++ SUPPORT</a></li> |
44 | <li><a href="#C_SUPPORT">C++ SUPPORT</a></li> |
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45 | <li><a href="#EMBEDDING">EMBEDDING</a> |
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46 | <ul><li><a href="#FILESETS">FILESETS</a> |
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47 | <ul><li><a href="#CORE_EVENT_LOOP">CORE EVENT LOOP</a></li> |
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48 | <li><a href="#LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</a></li> |
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49 | <li><a href="#AUTOCONF_SUPPORT">AUTOCONF SUPPORT</a></li> |
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50 | </ul> |
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51 | </li> |
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52 | <li><a href="#PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</a></li> |
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53 | <li><a href="#EXAMPLES">EXAMPLES</a></li> |
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54 | </ul> |
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55 | </li> |
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56 | <li><a href="#COMPLEXITIES">COMPLEXITIES</a></li> |
43 | <li><a href="#AUTHOR">AUTHOR</a> |
57 | <li><a href="#AUTHOR">AUTHOR</a> |
44 | </li> |
58 | </li> |
45 | </ul><hr /> |
59 | </ul><hr /> |
46 | <!-- INDEX END --> |
60 | <!-- INDEX END --> |
47 | |
61 | |
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363 | </pre> |
377 | </pre> |
364 | </dd> |
378 | </dd> |
365 | <dt>ev_default_destroy ()</dt> |
379 | <dt>ev_default_destroy ()</dt> |
366 | <dd> |
380 | <dd> |
367 | <p>Destroys the default loop again (frees all memory and kernel state |
381 | <p>Destroys the default loop again (frees all memory and kernel state |
368 | etc.). This stops all registered event watchers (by not touching them in |
382 | etc.). None of the active event watchers will be stopped in the normal |
369 | any way whatsoever, although you cannot rely on this :).</p> |
383 | sense, so e.g. <code>ev_is_active</code> might still return true. It is your |
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384 | responsibility to either stop all watchers cleanly yoursef <i>before</i> |
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385 | calling this function, or cope with the fact afterwards (which is usually |
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386 | the easiest thing, youc na just ignore the watchers and/or <code>free ()</code> them |
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387 | for example).</p> |
370 | </dd> |
388 | </dd> |
371 | <dt>ev_loop_destroy (loop)</dt> |
389 | <dt>ev_loop_destroy (loop)</dt> |
372 | <dd> |
390 | <dd> |
373 | <p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an |
391 | <p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an |
374 | earlier call to <code>ev_loop_new</code>.</p> |
392 | earlier call to <code>ev_loop_new</code>.</p> |
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497 | |
515 | |
498 | </pre> |
516 | </pre> |
499 | </dd> |
517 | </dd> |
500 | </dl> |
518 | </dl> |
501 | |
519 | |
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520 | |
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521 | |
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522 | |
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523 | |
502 | </div> |
524 | </div> |
503 | <h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p> |
525 | <h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p> |
504 | <div id="ANATOMY_OF_A_WATCHER_CONTENT"> |
526 | <div id="ANATOMY_OF_A_WATCHER_CONTENT"> |
505 | <p>A watcher is a structure that you create and register to record your |
527 | <p>A watcher is a structure that you create and register to record your |
506 | interest in some event. For instance, if you want to wait for STDIN to |
528 | interest in some event. For instance, if you want to wait for STDIN to |
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535 | with a watcher-specific start function (<code>ev_<type>_start (loop, watcher |
557 | with a watcher-specific start function (<code>ev_<type>_start (loop, watcher |
536 | *)</code>), and you can stop watching for events at any time by calling the |
558 | *)</code>), and you can stop watching for events at any time by calling the |
537 | corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p> |
559 | corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p> |
538 | <p>As long as your watcher is active (has been started but not stopped) you |
560 | <p>As long as your watcher is active (has been started but not stopped) you |
539 | must not touch the values stored in it. Most specifically you must never |
561 | must not touch the values stored in it. Most specifically you must never |
540 | reinitialise it or call its set macro.</p> |
562 | reinitialise it or call its <code>set</code> macro.</p> |
541 | <p>You can check whether an event is active by calling the <code>ev_is_active |
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542 | (watcher *)</code> macro. To see whether an event is outstanding (but the |
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543 | callback for it has not been called yet) you can use the <code>ev_is_pending |
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544 | (watcher *)</code> macro.</p> |
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545 | <p>Each and every callback receives the event loop pointer as first, the |
563 | <p>Each and every callback receives the event loop pointer as first, the |
546 | registered watcher structure as second, and a bitset of received events as |
564 | registered watcher structure as second, and a bitset of received events as |
547 | third argument.</p> |
565 | third argument.</p> |
548 | <p>The received events usually include a single bit per event type received |
566 | <p>The received events usually include a single bit per event type received |
549 | (you can receive multiple events at the same time). The possible bit masks |
567 | (you can receive multiple events at the same time). The possible bit masks |
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568 | <p>The signal specified in the <code>ev_signal</code> watcher has been received by a thread.</p> |
586 | <p>The signal specified in the <code>ev_signal</code> watcher has been received by a thread.</p> |
569 | </dd> |
587 | </dd> |
570 | <dt><code>EV_CHILD</code></dt> |
588 | <dt><code>EV_CHILD</code></dt> |
571 | <dd> |
589 | <dd> |
572 | <p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p> |
590 | <p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p> |
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591 | </dd> |
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592 | <dt><code>EV_STAT</code></dt> |
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593 | <dd> |
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594 | <p>The path specified in the <code>ev_stat</code> watcher changed its attributes somehow.</p> |
573 | </dd> |
595 | </dd> |
574 | <dt><code>EV_IDLE</code></dt> |
596 | <dt><code>EV_IDLE</code></dt> |
575 | <dd> |
597 | <dd> |
576 | <p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p> |
598 | <p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p> |
577 | </dd> |
599 | </dd> |
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598 | your callbacks is well-written it can just attempt the operation and cope |
620 | your callbacks is well-written it can just attempt the operation and cope |
599 | with the error from read() or write(). This will not work in multithreaded |
621 | with the error from read() or write(). This will not work in multithreaded |
600 | programs, though, so beware.</p> |
622 | programs, though, so beware.</p> |
601 | </dd> |
623 | </dd> |
602 | </dl> |
624 | </dl> |
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625 | |
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626 | </div> |
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627 | <h2 id="GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</h2> |
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628 | <div id="GENERIC_WATCHER_FUNCTIONS_CONTENT"> |
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629 | <p>In the following description, <code>TYPE</code> stands for the watcher type, |
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630 | e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p> |
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631 | <dl> |
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632 | <dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt> |
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633 | <dd> |
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634 | <p>This macro initialises the generic portion of a watcher. The contents |
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635 | of the watcher object can be arbitrary (so <code>malloc</code> will do). Only |
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636 | the generic parts of the watcher are initialised, you <i>need</i> to call |
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637 | the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the |
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638 | type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro |
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639 | which rolls both calls into one.</p> |
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640 | <p>You can reinitialise a watcher at any time as long as it has been stopped |
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641 | (or never started) and there are no pending events outstanding.</p> |
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642 | <p>The callback is always of type <code>void (*)(ev_loop *loop, ev_TYPE *watcher, |
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643 | int revents)</code>.</p> |
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644 | </dd> |
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645 | <dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt> |
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646 | <dd> |
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647 | <p>This macro initialises the type-specific parts of a watcher. You need to |
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648 | call <code>ev_init</code> at least once before you call this macro, but you can |
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649 | call <code>ev_TYPE_set</code> any number of times. You must not, however, call this |
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650 | macro on a watcher that is active (it can be pending, however, which is a |
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651 | difference to the <code>ev_init</code> macro).</p> |
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652 | <p>Although some watcher types do not have type-specific arguments |
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653 | (e.g. <code>ev_prepare</code>) you still need to call its <code>set</code> macro.</p> |
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654 | </dd> |
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655 | <dt><code>ev_TYPE_init</code> (ev_TYPE *watcher, callback, [args])</dt> |
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656 | <dd> |
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657 | <p>This convinience macro rolls both <code>ev_init</code> and <code>ev_TYPE_set</code> macro |
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658 | calls into a single call. This is the most convinient method to initialise |
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659 | a watcher. The same limitations apply, of course.</p> |
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660 | </dd> |
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661 | <dt><code>ev_TYPE_start</code> (loop *, ev_TYPE *watcher)</dt> |
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662 | <dd> |
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663 | <p>Starts (activates) the given watcher. Only active watchers will receive |
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664 | events. If the watcher is already active nothing will happen.</p> |
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665 | </dd> |
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666 | <dt><code>ev_TYPE_stop</code> (loop *, ev_TYPE *watcher)</dt> |
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667 | <dd> |
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668 | <p>Stops the given watcher again (if active) and clears the pending |
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669 | status. It is possible that stopped watchers are pending (for example, |
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670 | non-repeating timers are being stopped when they become pending), but |
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671 | <code>ev_TYPE_stop</code> ensures that the watcher is neither active nor pending. If |
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672 | you want to free or reuse the memory used by the watcher it is therefore a |
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673 | good idea to always call its <code>ev_TYPE_stop</code> function.</p> |
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674 | </dd> |
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675 | <dt>bool ev_is_active (ev_TYPE *watcher)</dt> |
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676 | <dd> |
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677 | <p>Returns a true value iff the watcher is active (i.e. it has been started |
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678 | and not yet been stopped). As long as a watcher is active you must not modify |
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679 | it.</p> |
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680 | </dd> |
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681 | <dt>bool ev_is_pending (ev_TYPE *watcher)</dt> |
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682 | <dd> |
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683 | <p>Returns a true value iff the watcher is pending, (i.e. it has outstanding |
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684 | events but its callback has not yet been invoked). As long as a watcher |
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685 | is pending (but not active) you must not call an init function on it (but |
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686 | <code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to |
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687 | libev (e.g. you cnanot <code>free ()</code> it).</p> |
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688 | </dd> |
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689 | <dt>callback = ev_cb (ev_TYPE *watcher)</dt> |
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690 | <dd> |
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691 | <p>Returns the callback currently set on the watcher.</p> |
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692 | </dd> |
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693 | <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt> |
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694 | <dd> |
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695 | <p>Change the callback. You can change the callback at virtually any time |
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696 | (modulo threads).</p> |
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697 | </dd> |
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698 | </dl> |
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699 | |
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700 | |
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701 | |
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702 | |
603 | |
703 | |
604 | </div> |
704 | </div> |
605 | <h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2> |
705 | <h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2> |
606 | <div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2"> |
706 | <div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2"> |
607 | <p>Each watcher has, by default, a member <code>void *data</code> that you can change |
707 | <p>Each watcher has, by default, a member <code>void *data</code> that you can change |
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637 | |
737 | |
638 | </div> |
738 | </div> |
639 | <h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p> |
739 | <h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p> |
640 | <div id="WATCHER_TYPES_CONTENT"> |
740 | <div id="WATCHER_TYPES_CONTENT"> |
641 | <p>This section describes each watcher in detail, but will not repeat |
741 | <p>This section describes each watcher in detail, but will not repeat |
642 | information given in the last section.</p> |
742 | information given in the last section. Any initialisation/set macros, |
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743 | functions and members specific to the watcher type are explained.</p> |
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744 | <p>Members are additionally marked with either <i>[read-only]</i>, meaning that, |
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745 | while the watcher is active, you can look at the member and expect some |
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746 | sensible content, but you must not modify it (you can modify it while the |
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747 | watcher is stopped to your hearts content), or <i>[read-write]</i>, which |
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748 | means you can expect it to have some sensible content while the watcher |
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749 | is active, but you can also modify it. Modifying it may not do something |
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750 | sensible or take immediate effect (or do anything at all), but libev will |
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751 | not crash or malfunction in any way.</p> |
643 | |
752 | |
644 | |
753 | |
645 | |
754 | |
646 | |
755 | |
647 | |
756 | |
648 | </div> |
757 | </div> |
649 | <h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</h2> |
758 | <h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</h2> |
650 | <div id="code_ev_io_code_is_this_file_descrip-2"> |
759 | <div id="code_ev_io_code_is_this_file_descrip-2"> |
651 | <p>I/O watchers check whether a file descriptor is readable or writable |
760 | <p>I/O watchers check whether a file descriptor is readable or writable |
652 | in each iteration of the event loop (This behaviour is called |
761 | in each iteration of the event loop, or, more precisely, when reading |
653 | level-triggering because you keep receiving events as long as the |
762 | would not block the process and writing would at least be able to write |
654 | condition persists. Remember you can stop the watcher if you don't want to |
763 | some data. This behaviour is called level-triggering because you keep |
655 | act on the event and neither want to receive future events).</p> |
764 | receiving events as long as the condition persists. Remember you can stop |
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765 | the watcher if you don't want to act on the event and neither want to |
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766 | receive future events.</p> |
656 | <p>In general you can register as many read and/or write event watchers per |
767 | <p>In general you can register as many read and/or write event watchers per |
657 | fd as you want (as long as you don't confuse yourself). Setting all file |
768 | fd as you want (as long as you don't confuse yourself). Setting all file |
658 | descriptors to non-blocking mode is also usually a good idea (but not |
769 | descriptors to non-blocking mode is also usually a good idea (but not |
659 | required if you know what you are doing).</p> |
770 | required if you know what you are doing).</p> |
660 | <p>You have to be careful with dup'ed file descriptors, though. Some backends |
771 | <p>You have to be careful with dup'ed file descriptors, though. Some backends |
661 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
772 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
662 | descriptors correctly if you register interest in two or more fds pointing |
773 | descriptors correctly if you register interest in two or more fds pointing |
663 | to the same underlying file/socket etc. description (that is, they share |
774 | to the same underlying file/socket/etc. description (that is, they share |
664 | the same underlying "file open").</p> |
775 | the same underlying "file open").</p> |
665 | <p>If you must do this, then force the use of a known-to-be-good backend |
776 | <p>If you must do this, then force the use of a known-to-be-good backend |
666 | (at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and |
777 | (at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and |
667 | <code>EVBACKEND_POLL</code>).</p> |
778 | <code>EVBACKEND_POLL</code>).</p> |
|
|
779 | <p>Another thing you have to watch out for is that it is quite easy to |
|
|
780 | receive "spurious" readyness notifications, that is your callback might |
|
|
781 | be called with <code>EV_READ</code> but a subsequent <code>read</code>(2) will actually block |
|
|
782 | because there is no data. Not only are some backends known to create a |
|
|
783 | lot of those (for example solaris ports), it is very easy to get into |
|
|
784 | this situation even with a relatively standard program structure. Thus |
|
|
785 | it is best to always use non-blocking I/O: An extra <code>read</code>(2) returning |
|
|
786 | <code>EAGAIN</code> is far preferable to a program hanging until some data arrives.</p> |
|
|
787 | <p>If you cannot run the fd in non-blocking mode (for example you should not |
|
|
788 | play around with an Xlib connection), then you have to seperately re-test |
|
|
789 | wether a file descriptor is really ready with a known-to-be good interface |
|
|
790 | such as poll (fortunately in our Xlib example, Xlib already does this on |
|
|
791 | its own, so its quite safe to use).</p> |
668 | <dl> |
792 | <dl> |
669 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
793 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
670 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
794 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
671 | <dd> |
795 | <dd> |
672 | <p>Configures an <code>ev_io</code> watcher. The fd is the file descriptor to rceeive |
796 | <p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to |
673 | events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_READ | |
797 | rceeive events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or |
674 | EV_WRITE</code> to receive the given events.</p> |
798 | <code>EV_READ | EV_WRITE</code> to receive the given events.</p> |
675 | <p>Please note that most of the more scalable backend mechanisms (for example |
799 | </dd> |
676 | epoll and solaris ports) can result in spurious readyness notifications |
800 | <dt>int fd [read-only]</dt> |
677 | for file descriptors, so you practically need to use non-blocking I/O (and |
801 | <dd> |
678 | treat callback invocation as hint only), or retest separately with a safe |
802 | <p>The file descriptor being watched.</p> |
679 | interface before doing I/O (XLib can do this), or force the use of either |
803 | </dd> |
680 | <code>EVBACKEND_SELECT</code> or <code>EVBACKEND_POLL</code>, which don't suffer from this |
804 | <dt>int events [read-only]</dt> |
681 | problem. Also note that it is quite easy to have your callback invoked |
805 | <dd> |
682 | when the readyness condition is no longer valid even when employing |
806 | <p>The events being watched.</p> |
683 | typical ways of handling events, so its a good idea to use non-blocking |
|
|
684 | I/O unconditionally.</p> |
|
|
685 | </dd> |
807 | </dd> |
686 | </dl> |
808 | </dl> |
687 | <p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well |
809 | <p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well |
688 | readable, but only once. Since it is likely line-buffered, you could |
810 | readable, but only once. Since it is likely line-buffered, you could |
689 | attempt to read a whole line in the callback:</p> |
811 | attempt to read a whole line in the callback:</p> |
… | |
… | |
705 | |
827 | |
706 | |
828 | |
707 | </pre> |
829 | </pre> |
708 | |
830 | |
709 | </div> |
831 | </div> |
710 | <h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</h2> |
832 | <h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</h2> |
711 | <div id="code_ev_timer_code_relative_and_opti-2"> |
833 | <div id="code_ev_timer_code_relative_and_opti-2"> |
712 | <p>Timer watchers are simple relative timers that generate an event after a |
834 | <p>Timer watchers are simple relative timers that generate an event after a |
713 | given time, and optionally repeating in regular intervals after that.</p> |
835 | given time, and optionally repeating in regular intervals after that.</p> |
714 | <p>The timers are based on real time, that is, if you register an event that |
836 | <p>The timers are based on real time, that is, if you register an event that |
715 | times out after an hour and you reset your system clock to last years |
837 | times out after an hour and you reset your system clock to last years |
… | |
… | |
747 | repeating. The exact semantics are:</p> |
869 | repeating. The exact semantics are:</p> |
748 | <p>If the timer is started but nonrepeating, stop it.</p> |
870 | <p>If the timer is started but nonrepeating, stop it.</p> |
749 | <p>If the timer is repeating, either start it if necessary (with the repeat |
871 | <p>If the timer is repeating, either start it if necessary (with the repeat |
750 | value), or reset the running timer to the repeat value.</p> |
872 | value), or reset the running timer to the repeat value.</p> |
751 | <p>This sounds a bit complicated, but here is a useful and typical |
873 | <p>This sounds a bit complicated, but here is a useful and typical |
752 | example: Imagine you have a tcp connection and you want a so-called idle |
874 | example: Imagine you have a tcp connection and you want a so-called |
753 | timeout, that is, you want to be called when there have been, say, 60 |
875 | idle timeout, that is, you want to be called when there have been, |
754 | seconds of inactivity on the socket. The easiest way to do this is to |
876 | say, 60 seconds of inactivity on the socket. The easiest way to do |
755 | configure an <code>ev_timer</code> with after=repeat=60 and calling ev_timer_again each |
877 | this is to configure an <code>ev_timer</code> with <code>after</code>=<code>repeat</code>=<code>60</code> and calling |
756 | time you successfully read or write some data. If you go into an idle |
878 | <code>ev_timer_again</code> each time you successfully read or write some data. If |
757 | state where you do not expect data to travel on the socket, you can stop |
879 | you go into an idle state where you do not expect data to travel on the |
758 | the timer, and again will automatically restart it if need be.</p> |
880 | socket, you can stop the timer, and again will automatically restart it if |
|
|
881 | need be.</p> |
|
|
882 | <p>You can also ignore the <code>after</code> value and <code>ev_timer_start</code> altogether |
|
|
883 | and only ever use the <code>repeat</code> value:</p> |
|
|
884 | <pre> ev_timer_init (timer, callback, 0., 5.); |
|
|
885 | ev_timer_again (loop, timer); |
|
|
886 | ... |
|
|
887 | timer->again = 17.; |
|
|
888 | ev_timer_again (loop, timer); |
|
|
889 | ... |
|
|
890 | timer->again = 10.; |
|
|
891 | ev_timer_again (loop, timer); |
|
|
892 | |
|
|
893 | </pre> |
|
|
894 | <p>This is more efficient then stopping/starting the timer eahc time you want |
|
|
895 | to modify its timeout value.</p> |
|
|
896 | </dd> |
|
|
897 | <dt>ev_tstamp repeat [read-write]</dt> |
|
|
898 | <dd> |
|
|
899 | <p>The current <code>repeat</code> value. Will be used each time the watcher times out |
|
|
900 | or <code>ev_timer_again</code> is called and determines the next timeout (if any), |
|
|
901 | which is also when any modifications are taken into account.</p> |
759 | </dd> |
902 | </dd> |
760 | </dl> |
903 | </dl> |
761 | <p>Example: create a timer that fires after 60 seconds.</p> |
904 | <p>Example: create a timer that fires after 60 seconds.</p> |
762 | <pre> static void |
905 | <pre> static void |
763 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
906 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
… | |
… | |
791 | |
934 | |
792 | |
935 | |
793 | </pre> |
936 | </pre> |
794 | |
937 | |
795 | </div> |
938 | </div> |
796 | <h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</h2> |
939 | <h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</h2> |
797 | <div id="code_ev_periodic_code_to_cron_or_not-2"> |
940 | <div id="code_ev_periodic_code_to_cron_or_not-2"> |
798 | <p>Periodic watchers are also timers of a kind, but they are very versatile |
941 | <p>Periodic watchers are also timers of a kind, but they are very versatile |
799 | (and unfortunately a bit complex).</p> |
942 | (and unfortunately a bit complex).</p> |
800 | <p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time) |
943 | <p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time) |
801 | but on wallclock time (absolute time). You can tell a periodic watcher |
944 | but on wallclock time (absolute time). You can tell a periodic watcher |
802 | to trigger "at" some specific point in time. For example, if you tell a |
945 | to trigger "at" some specific point in time. For example, if you tell a |
803 | periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now () |
946 | periodic watcher to trigger in 10 seconds (by specifiying e.g. <code>ev_now () |
804 | + 10.>) and then reset your system clock to the last year, then it will |
947 | + 10.</code>) and then reset your system clock to the last year, then it will |
805 | take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger |
948 | take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger |
806 | roughly 10 seconds later and of course not if you reset your system time |
949 | roughly 10 seconds later and of course not if you reset your system time |
807 | again).</p> |
950 | again).</p> |
808 | <p>They can also be used to implement vastly more complex timers, such as |
951 | <p>They can also be used to implement vastly more complex timers, such as |
809 | triggering an event on eahc midnight, local time.</p> |
952 | triggering an event on eahc midnight, local time.</p> |
… | |
… | |
881 | <p>Simply stops and restarts the periodic watcher again. This is only useful |
1024 | <p>Simply stops and restarts the periodic watcher again. This is only useful |
882 | when you changed some parameters or the reschedule callback would return |
1025 | when you changed some parameters or the reschedule callback would return |
883 | a different time than the last time it was called (e.g. in a crond like |
1026 | a different time than the last time it was called (e.g. in a crond like |
884 | program when the crontabs have changed).</p> |
1027 | program when the crontabs have changed).</p> |
885 | </dd> |
1028 | </dd> |
|
|
1029 | <dt>ev_tstamp interval [read-write]</dt> |
|
|
1030 | <dd> |
|
|
1031 | <p>The current interval value. Can be modified any time, but changes only |
|
|
1032 | take effect when the periodic timer fires or <code>ev_periodic_again</code> is being |
|
|
1033 | called.</p> |
|
|
1034 | </dd> |
|
|
1035 | <dt>ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]</dt> |
|
|
1036 | <dd> |
|
|
1037 | <p>The current reschedule callback, or <code>0</code>, if this functionality is |
|
|
1038 | switched off. Can be changed any time, but changes only take effect when |
|
|
1039 | the periodic timer fires or <code>ev_periodic_again</code> is being called.</p> |
|
|
1040 | </dd> |
886 | </dl> |
1041 | </dl> |
887 | <p>Example: call a callback every hour, or, more precisely, whenever the |
1042 | <p>Example: call a callback every hour, or, more precisely, whenever the |
888 | system clock is divisible by 3600. The callback invocation times have |
1043 | system clock is divisible by 3600. The callback invocation times have |
889 | potentially a lot of jittering, but good long-term stability.</p> |
1044 | potentially a lot of jittering, but good long-term stability.</p> |
890 | <pre> static void |
1045 | <pre> static void |
… | |
… | |
920 | |
1075 | |
921 | |
1076 | |
922 | </pre> |
1077 | </pre> |
923 | |
1078 | |
924 | </div> |
1079 | </div> |
925 | <h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</h2> |
1080 | <h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</h2> |
926 | <div id="code_ev_signal_code_signal_me_when_a-2"> |
1081 | <div id="code_ev_signal_code_signal_me_when_a-2"> |
927 | <p>Signal watchers will trigger an event when the process receives a specific |
1082 | <p>Signal watchers will trigger an event when the process receives a specific |
928 | signal one or more times. Even though signals are very asynchronous, libev |
1083 | signal one or more times. Even though signals are very asynchronous, libev |
929 | will try it's best to deliver signals synchronously, i.e. as part of the |
1084 | will try it's best to deliver signals synchronously, i.e. as part of the |
930 | normal event processing, like any other event.</p> |
1085 | normal event processing, like any other event.</p> |
… | |
… | |
939 | <dt>ev_signal_set (ev_signal *, int signum)</dt> |
1094 | <dt>ev_signal_set (ev_signal *, int signum)</dt> |
940 | <dd> |
1095 | <dd> |
941 | <p>Configures the watcher to trigger on the given signal number (usually one |
1096 | <p>Configures the watcher to trigger on the given signal number (usually one |
942 | of the <code>SIGxxx</code> constants).</p> |
1097 | of the <code>SIGxxx</code> constants).</p> |
943 | </dd> |
1098 | </dd> |
|
|
1099 | <dt>int signum [read-only]</dt> |
|
|
1100 | <dd> |
|
|
1101 | <p>The signal the watcher watches out for.</p> |
|
|
1102 | </dd> |
944 | </dl> |
1103 | </dl> |
945 | |
1104 | |
946 | |
1105 | |
947 | |
1106 | |
948 | |
1107 | |
949 | |
1108 | |
950 | </div> |
1109 | </div> |
951 | <h2 id="code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</h2> |
1110 | <h2 id="code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</h2> |
952 | <div id="code_ev_child_code_wait_for_pid_stat-2"> |
1111 | <div id="code_ev_child_code_watch_out_for_pro-2"> |
953 | <p>Child watchers trigger when your process receives a SIGCHLD in response to |
1112 | <p>Child watchers trigger when your process receives a SIGCHLD in response to |
954 | some child status changes (most typically when a child of yours dies).</p> |
1113 | some child status changes (most typically when a child of yours dies).</p> |
955 | <dl> |
1114 | <dl> |
956 | <dt>ev_child_init (ev_child *, callback, int pid)</dt> |
1115 | <dt>ev_child_init (ev_child *, callback, int pid)</dt> |
957 | <dt>ev_child_set (ev_child *, int pid)</dt> |
1116 | <dt>ev_child_set (ev_child *, int pid)</dt> |
… | |
… | |
960 | <i>any</i> process if <code>pid</code> is specified as <code>0</code>). The callback can look |
1119 | <i>any</i> process if <code>pid</code> is specified as <code>0</code>). The callback can look |
961 | at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see |
1120 | at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see |
962 | the status word (use the macros from <code>sys/wait.h</code> and see your systems |
1121 | the status word (use the macros from <code>sys/wait.h</code> and see your systems |
963 | <code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the |
1122 | <code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the |
964 | process causing the status change.</p> |
1123 | process causing the status change.</p> |
|
|
1124 | </dd> |
|
|
1125 | <dt>int pid [read-only]</dt> |
|
|
1126 | <dd> |
|
|
1127 | <p>The process id this watcher watches out for, or <code>0</code>, meaning any process id.</p> |
|
|
1128 | </dd> |
|
|
1129 | <dt>int rpid [read-write]</dt> |
|
|
1130 | <dd> |
|
|
1131 | <p>The process id that detected a status change.</p> |
|
|
1132 | </dd> |
|
|
1133 | <dt>int rstatus [read-write]</dt> |
|
|
1134 | <dd> |
|
|
1135 | <p>The process exit/trace status caused by <code>rpid</code> (see your systems |
|
|
1136 | <code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p> |
965 | </dd> |
1137 | </dd> |
966 | </dl> |
1138 | </dl> |
967 | <p>Example: try to exit cleanly on SIGINT and SIGTERM.</p> |
1139 | <p>Example: try to exit cleanly on SIGINT and SIGTERM.</p> |
968 | <pre> static void |
1140 | <pre> static void |
969 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1141 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
… | |
… | |
979 | |
1151 | |
980 | |
1152 | |
981 | </pre> |
1153 | </pre> |
982 | |
1154 | |
983 | </div> |
1155 | </div> |
|
|
1156 | <h2 id="code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</h2> |
|
|
1157 | <div id="code_ev_stat_code_did_the_file_attri-2"> |
|
|
1158 | <p>This watches a filesystem path for attribute changes. That is, it calls |
|
|
1159 | <code>stat</code> regularly (or when the OS says it changed) and sees if it changed |
|
|
1160 | compared to the last time, invoking the callback if it did.</p> |
|
|
1161 | <p>The path does not need to exist: changing from "path exists" to "path does |
|
|
1162 | not exist" is a status change like any other. The condition "path does |
|
|
1163 | not exist" is signified by the <code>st_nlink</code> field being zero (which is |
|
|
1164 | otherwise always forced to be at least one) and all the other fields of |
|
|
1165 | the stat buffer having unspecified contents.</p> |
|
|
1166 | <p>Since there is no standard to do this, the portable implementation simply |
|
|
1167 | calls <code>stat (2)</code> regulalry on the path to see if it changed somehow. You |
|
|
1168 | can specify a recommended polling interval for this case. If you specify |
|
|
1169 | a polling interval of <code>0</code> (highly recommended!) then a <i>suitable, |
|
|
1170 | unspecified default</i> value will be used (which you can expect to be around |
|
|
1171 | five seconds, although this might change dynamically). Libev will also |
|
|
1172 | impose a minimum interval which is currently around <code>0.1</code>, but thats |
|
|
1173 | usually overkill.</p> |
|
|
1174 | <p>This watcher type is not meant for massive numbers of stat watchers, |
|
|
1175 | as even with OS-supported change notifications, this can be |
|
|
1176 | resource-intensive.</p> |
|
|
1177 | <p>At the time of this writing, no specific OS backends are implemented, but |
|
|
1178 | if demand increases, at least a kqueue and inotify backend will be added.</p> |
|
|
1179 | <dl> |
|
|
1180 | <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt> |
|
|
1181 | <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt> |
|
|
1182 | <dd> |
|
|
1183 | <p>Configures the watcher to wait for status changes of the given |
|
|
1184 | <code>path</code>. The <code>interval</code> is a hint on how quickly a change is expected to |
|
|
1185 | be detected and should normally be specified as <code>0</code> to let libev choose |
|
|
1186 | a suitable value. The memory pointed to by <code>path</code> must point to the same |
|
|
1187 | path for as long as the watcher is active.</p> |
|
|
1188 | <p>The callback will be receive <code>EV_STAT</code> when a change was detected, |
|
|
1189 | relative to the attributes at the time the watcher was started (or the |
|
|
1190 | last change was detected).</p> |
|
|
1191 | </dd> |
|
|
1192 | <dt>ev_stat_stat (ev_stat *)</dt> |
|
|
1193 | <dd> |
|
|
1194 | <p>Updates the stat buffer immediately with new values. If you change the |
|
|
1195 | watched path in your callback, you could call this fucntion to avoid |
|
|
1196 | detecting this change (while introducing a race condition). Can also be |
|
|
1197 | useful simply to find out the new values.</p> |
|
|
1198 | </dd> |
|
|
1199 | <dt>ev_statdata attr [read-only]</dt> |
|
|
1200 | <dd> |
|
|
1201 | <p>The most-recently detected attributes of the file. Although the type is of |
|
|
1202 | <code>ev_statdata</code>, this is usually the (or one of the) <code>struct stat</code> types |
|
|
1203 | suitable for your system. If the <code>st_nlink</code> member is <code>0</code>, then there |
|
|
1204 | was some error while <code>stat</code>ing the file.</p> |
|
|
1205 | </dd> |
|
|
1206 | <dt>ev_statdata prev [read-only]</dt> |
|
|
1207 | <dd> |
|
|
1208 | <p>The previous attributes of the file. The callback gets invoked whenever |
|
|
1209 | <code>prev</code> != <code>attr</code>.</p> |
|
|
1210 | </dd> |
|
|
1211 | <dt>ev_tstamp interval [read-only]</dt> |
|
|
1212 | <dd> |
|
|
1213 | <p>The specified interval.</p> |
|
|
1214 | </dd> |
|
|
1215 | <dt>const char *path [read-only]</dt> |
|
|
1216 | <dd> |
|
|
1217 | <p>The filesystem path that is being watched.</p> |
|
|
1218 | </dd> |
|
|
1219 | </dl> |
|
|
1220 | <p>Example: Watch <code>/etc/passwd</code> for attribute changes.</p> |
|
|
1221 | <pre> static void |
|
|
1222 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
|
|
1223 | { |
|
|
1224 | /* /etc/passwd changed in some way */ |
|
|
1225 | if (w->attr.st_nlink) |
|
|
1226 | { |
|
|
1227 | printf ("passwd current size %ld\n", (long)w->attr.st_size); |
|
|
1228 | printf ("passwd current atime %ld\n", (long)w->attr.st_mtime); |
|
|
1229 | printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime); |
|
|
1230 | } |
|
|
1231 | else |
|
|
1232 | /* you shalt not abuse printf for puts */ |
|
|
1233 | puts ("wow, /etc/passwd is not there, expect problems. " |
|
|
1234 | "if this is windows, they already arrived\n"); |
|
|
1235 | } |
|
|
1236 | |
|
|
1237 | ... |
|
|
1238 | ev_stat passwd; |
|
|
1239 | |
|
|
1240 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
|
|
1241 | ev_stat_start (loop, &passwd); |
|
|
1242 | |
|
|
1243 | |
|
|
1244 | |
|
|
1245 | |
|
|
1246 | </pre> |
|
|
1247 | |
|
|
1248 | </div> |
984 | <h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</h2> |
1249 | <h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2> |
985 | <div id="code_ev_idle_code_when_you_ve_got_no-2"> |
1250 | <div id="code_ev_idle_code_when_you_ve_got_no-2"> |
986 | <p>Idle watchers trigger events when there are no other events are pending |
1251 | <p>Idle watchers trigger events when there are no other events are pending |
987 | (prepare, check and other idle watchers do not count). That is, as long |
1252 | (prepare, check and other idle watchers do not count). That is, as long |
988 | as your process is busy handling sockets or timeouts (or even signals, |
1253 | as your process is busy handling sockets or timeouts (or even signals, |
989 | imagine) it will not be triggered. But when your process is idle all idle |
1254 | imagine) it will not be triggered. But when your process is idle all idle |
… | |
… | |
1022 | |
1287 | |
1023 | |
1288 | |
1024 | </pre> |
1289 | </pre> |
1025 | |
1290 | |
1026 | </div> |
1291 | </div> |
1027 | <h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</h2> |
1292 | <h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</h2> |
1028 | <div id="code_ev_prepare_code_and_code_ev_che-2"> |
1293 | <div id="code_ev_prepare_code_and_code_ev_che-2"> |
1029 | <p>Prepare and check watchers are usually (but not always) used in tandem: |
1294 | <p>Prepare and check watchers are usually (but not always) used in tandem: |
1030 | prepare watchers get invoked before the process blocks and check watchers |
1295 | prepare watchers get invoked before the process blocks and check watchers |
1031 | afterwards.</p> |
1296 | afterwards.</p> |
|
|
1297 | <p>You <i>must not</i> call <code>ev_loop</code> or similar functions that enter |
|
|
1298 | the current event loop from either <code>ev_prepare</code> or <code>ev_check</code> |
|
|
1299 | watchers. Other loops than the current one are fine, however. The |
|
|
1300 | rationale behind this is that you do not need to check for recursion in |
|
|
1301 | those watchers, i.e. the sequence will always be <code>ev_prepare</code>, blocking, |
|
|
1302 | <code>ev_check</code> so if you have one watcher of each kind they will always be |
|
|
1303 | called in pairs bracketing the blocking call.</p> |
1032 | <p>Their main purpose is to integrate other event mechanisms into libev and |
1304 | <p>Their main purpose is to integrate other event mechanisms into libev and |
1033 | their use is somewhat advanced. This could be used, for example, to track |
1305 | their use is somewhat advanced. This could be used, for example, to track |
1034 | variable changes, implement your own watchers, integrate net-snmp or a |
1306 | variable changes, implement your own watchers, integrate net-snmp or a |
1035 | coroutine library and lots more.</p> |
1307 | coroutine library and lots more. They are also occasionally useful if |
|
|
1308 | you cache some data and want to flush it before blocking (for example, |
|
|
1309 | in X programs you might want to do an <code>XFlush ()</code> in an <code>ev_prepare</code> |
|
|
1310 | watcher).</p> |
1036 | <p>This is done by examining in each prepare call which file descriptors need |
1311 | <p>This is done by examining in each prepare call which file descriptors need |
1037 | to be watched by the other library, registering <code>ev_io</code> watchers for |
1312 | to be watched by the other library, registering <code>ev_io</code> watchers for |
1038 | them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries |
1313 | them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries |
1039 | provide just this functionality). Then, in the check watcher you check for |
1314 | provide just this functionality). Then, in the check watcher you check for |
1040 | any events that occured (by checking the pending status of all watchers |
1315 | any events that occured (by checking the pending status of all watchers |
… | |
… | |
1056 | <p>Initialises and configures the prepare or check watcher - they have no |
1331 | <p>Initialises and configures the prepare or check watcher - they have no |
1057 | parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code> |
1332 | parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code> |
1058 | macros, but using them is utterly, utterly and completely pointless.</p> |
1333 | macros, but using them is utterly, utterly and completely pointless.</p> |
1059 | </dd> |
1334 | </dd> |
1060 | </dl> |
1335 | </dl> |
1061 | <p>Example: *TODO*.</p> |
1336 | <p>Example: To include a library such as adns, you would add IO watchers |
|
|
1337 | and a timeout watcher in a prepare handler, as required by libadns, and |
|
|
1338 | in a check watcher, destroy them and call into libadns. What follows is |
|
|
1339 | pseudo-code only of course:</p> |
|
|
1340 | <pre> static ev_io iow [nfd]; |
|
|
1341 | static ev_timer tw; |
1062 | |
1342 | |
|
|
1343 | static void |
|
|
1344 | io_cb (ev_loop *loop, ev_io *w, int revents) |
|
|
1345 | { |
|
|
1346 | // set the relevant poll flags |
|
|
1347 | // could also call adns_processreadable etc. here |
|
|
1348 | struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1349 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1350 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1351 | } |
1063 | |
1352 | |
|
|
1353 | // create io watchers for each fd and a timer before blocking |
|
|
1354 | static void |
|
|
1355 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
|
|
1356 | { |
|
|
1357 | int timeout = 3600000;truct pollfd fds [nfd]; |
|
|
1358 | // actual code will need to loop here and realloc etc. |
|
|
1359 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1064 | |
1360 | |
|
|
1361 | /* the callback is illegal, but won't be called as we stop during check */ |
|
|
1362 | ev_timer_init (&tw, 0, timeout * 1e-3); |
|
|
1363 | ev_timer_start (loop, &tw); |
1065 | |
1364 | |
|
|
1365 | // create on ev_io per pollfd |
|
|
1366 | for (int i = 0; i < nfd; ++i) |
|
|
1367 | { |
|
|
1368 | ev_io_init (iow + i, io_cb, fds [i].fd, |
|
|
1369 | ((fds [i].events & POLLIN ? EV_READ : 0) |
|
|
1370 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1066 | |
1371 | |
|
|
1372 | fds [i].revents = 0; |
|
|
1373 | iow [i].data = fds + i; |
|
|
1374 | ev_io_start (loop, iow + i); |
|
|
1375 | } |
|
|
1376 | } |
|
|
1377 | |
|
|
1378 | // stop all watchers after blocking |
|
|
1379 | static void |
|
|
1380 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
|
|
1381 | { |
|
|
1382 | ev_timer_stop (loop, &tw); |
|
|
1383 | |
|
|
1384 | for (int i = 0; i < nfd; ++i) |
|
|
1385 | ev_io_stop (loop, iow + i); |
|
|
1386 | |
|
|
1387 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1388 | } |
|
|
1389 | |
|
|
1390 | |
|
|
1391 | |
|
|
1392 | |
|
|
1393 | </pre> |
|
|
1394 | |
1067 | </div> |
1395 | </div> |
1068 | <h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough</h2> |
1396 | <h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</h2> |
1069 | <div id="code_ev_embed_code_when_one_backend_-2"> |
1397 | <div id="code_ev_embed_code_when_one_backend_-2"> |
1070 | <p>This is a rather advanced watcher type that lets you embed one event loop |
1398 | <p>This is a rather advanced watcher type that lets you embed one event loop |
1071 | into another.</p> |
1399 | into another (currently only <code>ev_io</code> events are supported in the embedded |
|
|
1400 | loop, other types of watchers might be handled in a delayed or incorrect |
|
|
1401 | fashion and must not be used).</p> |
1072 | <p>There are primarily two reasons you would want that: work around bugs and |
1402 | <p>There are primarily two reasons you would want that: work around bugs and |
1073 | prioritise I/O.</p> |
1403 | prioritise I/O.</p> |
1074 | <p>As an example for a bug workaround, the kqueue backend might only support |
1404 | <p>As an example for a bug workaround, the kqueue backend might only support |
1075 | sockets on some platform, so it is unusable as generic backend, but you |
1405 | sockets on some platform, so it is unusable as generic backend, but you |
1076 | still want to make use of it because you have many sockets and it scales |
1406 | still want to make use of it because you have many sockets and it scales |
… | |
… | |
1081 | <p>As for prioritising I/O: rarely you have the case where some fds have |
1411 | <p>As for prioritising I/O: rarely you have the case where some fds have |
1082 | to be watched and handled very quickly (with low latency), and even |
1412 | to be watched and handled very quickly (with low latency), and even |
1083 | priorities and idle watchers might have too much overhead. In this case |
1413 | priorities and idle watchers might have too much overhead. In this case |
1084 | you would put all the high priority stuff in one loop and all the rest in |
1414 | you would put all the high priority stuff in one loop and all the rest in |
1085 | a second one, and embed the second one in the first.</p> |
1415 | a second one, and embed the second one in the first.</p> |
|
|
1416 | <p>As long as the watcher is active, the callback will be invoked every time |
|
|
1417 | there might be events pending in the embedded loop. The callback must then |
|
|
1418 | call <code>ev_embed_sweep (mainloop, watcher)</code> to make a single sweep and invoke |
|
|
1419 | their callbacks (you could also start an idle watcher to give the embedded |
|
|
1420 | loop strictly lower priority for example). You can also set the callback |
|
|
1421 | to <code>0</code>, in which case the embed watcher will automatically execute the |
|
|
1422 | embedded loop sweep.</p> |
1086 | <p>As long as the watcher is started it will automatically handle events. The |
1423 | <p>As long as the watcher is started it will automatically handle events. The |
1087 | callback will be invoked whenever some events have been handled. You can |
1424 | callback will be invoked whenever some events have been handled. You can |
1088 | set the callback to <code>0</code> to avoid having to specify one if you are not |
1425 | set the callback to <code>0</code> to avoid having to specify one if you are not |
1089 | interested in that.</p> |
1426 | interested in that.</p> |
1090 | <p>Also, there have not currently been made special provisions for forking: |
1427 | <p>Also, there have not currently been made special provisions for forking: |
… | |
… | |
1117 | else |
1454 | else |
1118 | loop_lo = loop_hi; |
1455 | loop_lo = loop_hi; |
1119 | |
1456 | |
1120 | </pre> |
1457 | </pre> |
1121 | <dl> |
1458 | <dl> |
1122 | <dt>ev_embed_init (ev_embed *, callback, struct ev_loop *loop)</dt> |
1459 | <dt>ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)</dt> |
1123 | <dt>ev_embed_set (ev_embed *, callback, struct ev_loop *loop)</dt> |
1460 | <dt>ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)</dt> |
|
|
1461 | <dd> |
|
|
1462 | <p>Configures the watcher to embed the given loop, which must be |
|
|
1463 | embeddable. If the callback is <code>0</code>, then <code>ev_embed_sweep</code> will be |
|
|
1464 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1465 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1466 | if you do not want thta, you need to temporarily stop the embed watcher).</p> |
1124 | <dd> |
1467 | </dd> |
1125 | <p>Configures the watcher to embed the given loop, which must be embeddable.</p> |
1468 | <dt>ev_embed_sweep (loop, ev_embed *)</dt> |
|
|
1469 | <dd> |
|
|
1470 | <p>Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1471 | similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most |
|
|
1472 | apropriate way for embedded loops.</p> |
|
|
1473 | </dd> |
|
|
1474 | <dt>struct ev_loop *loop [read-only]</dt> |
|
|
1475 | <dd> |
|
|
1476 | <p>The embedded event loop.</p> |
1126 | </dd> |
1477 | </dd> |
1127 | </dl> |
1478 | </dl> |
1128 | |
1479 | |
1129 | |
1480 | |
1130 | |
1481 | |
… | |
… | |
1163 | |
1514 | |
1164 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
1515 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
1165 | |
1516 | |
1166 | </pre> |
1517 | </pre> |
1167 | </dd> |
1518 | </dd> |
1168 | <dt>ev_feed_event (loop, watcher, int events)</dt> |
1519 | <dt>ev_feed_event (ev_loop *, watcher *, int revents)</dt> |
1169 | <dd> |
1520 | <dd> |
1170 | <p>Feeds the given event set into the event loop, as if the specified event |
1521 | <p>Feeds the given event set into the event loop, as if the specified event |
1171 | had happened for the specified watcher (which must be a pointer to an |
1522 | had happened for the specified watcher (which must be a pointer to an |
1172 | initialised but not necessarily started event watcher).</p> |
1523 | initialised but not necessarily started event watcher).</p> |
1173 | </dd> |
1524 | </dd> |
1174 | <dt>ev_feed_fd_event (loop, int fd, int revents)</dt> |
1525 | <dt>ev_feed_fd_event (ev_loop *, int fd, int revents)</dt> |
1175 | <dd> |
1526 | <dd> |
1176 | <p>Feed an event on the given fd, as if a file descriptor backend detected |
1527 | <p>Feed an event on the given fd, as if a file descriptor backend detected |
1177 | the given events it.</p> |
1528 | the given events it.</p> |
1178 | </dd> |
1529 | </dd> |
1179 | <dt>ev_feed_signal_event (loop, int signum)</dt> |
1530 | <dt>ev_feed_signal_event (ev_loop *loop, int signum)</dt> |
1180 | <dd> |
1531 | <dd> |
1181 | <p>Feed an event as if the given signal occured (loop must be the default loop!).</p> |
1532 | <p>Feed an event as if the given signal occured (<code>loop</code> must be the default |
|
|
1533 | loop!).</p> |
1182 | </dd> |
1534 | </dd> |
1183 | </dl> |
1535 | </dl> |
1184 | |
1536 | |
1185 | |
1537 | |
1186 | |
1538 | |
… | |
… | |
1207 | </dl> |
1559 | </dl> |
1208 | |
1560 | |
1209 | </div> |
1561 | </div> |
1210 | <h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1562 | <h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1211 | <div id="C_SUPPORT_CONTENT"> |
1563 | <div id="C_SUPPORT_CONTENT"> |
1212 | <p>TBD.</p> |
1564 | <p>Libev comes with some simplistic wrapper classes for C++ that mainly allow |
|
|
1565 | you to use some convinience methods to start/stop watchers and also change |
|
|
1566 | the callback model to a model using method callbacks on objects.</p> |
|
|
1567 | <p>To use it,</p> |
|
|
1568 | <pre> #include <ev++.h> |
|
|
1569 | |
|
|
1570 | </pre> |
|
|
1571 | <p>(it is not installed by default). This automatically includes <cite>ev.h</cite> |
|
|
1572 | and puts all of its definitions (many of them macros) into the global |
|
|
1573 | namespace. All C++ specific things are put into the <code>ev</code> namespace.</p> |
|
|
1574 | <p>It should support all the same embedding options as <cite>ev.h</cite>, most notably |
|
|
1575 | <code>EV_MULTIPLICITY</code>.</p> |
|
|
1576 | <p>Here is a list of things available in the <code>ev</code> namespace:</p> |
|
|
1577 | <dl> |
|
|
1578 | <dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt> |
|
|
1579 | <dd> |
|
|
1580 | <p>These are just enum values with the same values as the <code>EV_READ</code> etc. |
|
|
1581 | macros from <cite>ev.h</cite>.</p> |
|
|
1582 | </dd> |
|
|
1583 | <dt><code>ev::tstamp</code>, <code>ev::now</code></dt> |
|
|
1584 | <dd> |
|
|
1585 | <p>Aliases to the same types/functions as with the <code>ev_</code> prefix.</p> |
|
|
1586 | </dd> |
|
|
1587 | <dt><code>ev::io</code>, <code>ev::timer</code>, <code>ev::periodic</code>, <code>ev::idle</code>, <code>ev::sig</code> etc.</dt> |
|
|
1588 | <dd> |
|
|
1589 | <p>For each <code>ev_TYPE</code> watcher in <cite>ev.h</cite> there is a corresponding class of |
|
|
1590 | the same name in the <code>ev</code> namespace, with the exception of <code>ev_signal</code> |
|
|
1591 | which is called <code>ev::sig</code> to avoid clashes with the <code>signal</code> macro |
|
|
1592 | defines by many implementations.</p> |
|
|
1593 | <p>All of those classes have these methods:</p> |
|
|
1594 | <p> |
|
|
1595 | <dl> |
|
|
1596 | <dt>ev::TYPE::TYPE (object *, object::method *)</dt> |
|
|
1597 | <dt>ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)</dt> |
|
|
1598 | <dt>ev::TYPE::~TYPE</dt> |
|
|
1599 | <dd> |
|
|
1600 | <p>The constructor takes a pointer to an object and a method pointer to |
|
|
1601 | the event handler callback to call in this class. The constructor calls |
|
|
1602 | <code>ev_init</code> for you, which means you have to call the <code>set</code> method |
|
|
1603 | before starting it. If you do not specify a loop then the constructor |
|
|
1604 | automatically associates the default loop with this watcher.</p> |
|
|
1605 | <p>The destructor automatically stops the watcher if it is active.</p> |
|
|
1606 | </dd> |
|
|
1607 | <dt>w->set (struct ev_loop *)</dt> |
|
|
1608 | <dd> |
|
|
1609 | <p>Associates a different <code>struct ev_loop</code> with this watcher. You can only |
|
|
1610 | do this when the watcher is inactive (and not pending either).</p> |
|
|
1611 | </dd> |
|
|
1612 | <dt>w->set ([args])</dt> |
|
|
1613 | <dd> |
|
|
1614 | <p>Basically the same as <code>ev_TYPE_set</code>, with the same args. Must be |
|
|
1615 | called at least once. Unlike the C counterpart, an active watcher gets |
|
|
1616 | automatically stopped and restarted.</p> |
|
|
1617 | </dd> |
|
|
1618 | <dt>w->start ()</dt> |
|
|
1619 | <dd> |
|
|
1620 | <p>Starts the watcher. Note that there is no <code>loop</code> argument as the |
|
|
1621 | constructor already takes the loop.</p> |
|
|
1622 | </dd> |
|
|
1623 | <dt>w->stop ()</dt> |
|
|
1624 | <dd> |
|
|
1625 | <p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p> |
|
|
1626 | </dd> |
|
|
1627 | <dt>w->again () <code>ev::timer</code>, <code>ev::periodic</code> only</dt> |
|
|
1628 | <dd> |
|
|
1629 | <p>For <code>ev::timer</code> and <code>ev::periodic</code>, this invokes the corresponding |
|
|
1630 | <code>ev_TYPE_again</code> function.</p> |
|
|
1631 | </dd> |
|
|
1632 | <dt>w->sweep () <code>ev::embed</code> only</dt> |
|
|
1633 | <dd> |
|
|
1634 | <p>Invokes <code>ev_embed_sweep</code>.</p> |
|
|
1635 | </dd> |
|
|
1636 | </dl> |
|
|
1637 | </p> |
|
|
1638 | </dd> |
|
|
1639 | </dl> |
|
|
1640 | <p>Example: Define a class with an IO and idle watcher, start one of them in |
|
|
1641 | the constructor.</p> |
|
|
1642 | <pre> class myclass |
|
|
1643 | { |
|
|
1644 | ev_io io; void io_cb (ev::io &w, int revents); |
|
|
1645 | ev_idle idle void idle_cb (ev::idle &w, int revents); |
|
|
1646 | |
|
|
1647 | myclass (); |
|
|
1648 | } |
|
|
1649 | |
|
|
1650 | myclass::myclass (int fd) |
|
|
1651 | : io (this, &myclass::io_cb), |
|
|
1652 | idle (this, &myclass::idle_cb) |
|
|
1653 | { |
|
|
1654 | io.start (fd, ev::READ); |
|
|
1655 | } |
|
|
1656 | |
|
|
1657 | </pre> |
|
|
1658 | |
|
|
1659 | </div> |
|
|
1660 | <h1 id="EMBEDDING">EMBEDDING</h1><p><a href="#TOP" class="toplink">Top</a></p> |
|
|
1661 | <div id="EMBEDDING_CONTENT"> |
|
|
1662 | <p>Libev can (and often is) directly embedded into host |
|
|
1663 | applications. Examples of applications that embed it include the Deliantra |
|
|
1664 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
|
|
1665 | and rxvt-unicode.</p> |
|
|
1666 | <p>The goal is to enable you to just copy the neecssary files into your |
|
|
1667 | source directory without having to change even a single line in them, so |
|
|
1668 | you can easily upgrade by simply copying (or having a checked-out copy of |
|
|
1669 | libev somewhere in your source tree).</p> |
|
|
1670 | |
|
|
1671 | </div> |
|
|
1672 | <h2 id="FILESETS">FILESETS</h2> |
|
|
1673 | <div id="FILESETS_CONTENT"> |
|
|
1674 | <p>Depending on what features you need you need to include one or more sets of files |
|
|
1675 | in your app.</p> |
|
|
1676 | |
|
|
1677 | </div> |
|
|
1678 | <h3 id="CORE_EVENT_LOOP">CORE EVENT LOOP</h3> |
|
|
1679 | <div id="CORE_EVENT_LOOP_CONTENT"> |
|
|
1680 | <p>To include only the libev core (all the <code>ev_*</code> functions), with manual |
|
|
1681 | configuration (no autoconf):</p> |
|
|
1682 | <pre> #define EV_STANDALONE 1 |
|
|
1683 | #include "ev.c" |
|
|
1684 | |
|
|
1685 | </pre> |
|
|
1686 | <p>This will automatically include <cite>ev.h</cite>, too, and should be done in a |
|
|
1687 | single C source file only to provide the function implementations. To use |
|
|
1688 | it, do the same for <cite>ev.h</cite> in all files wishing to use this API (best |
|
|
1689 | done by writing a wrapper around <cite>ev.h</cite> that you can include instead and |
|
|
1690 | where you can put other configuration options):</p> |
|
|
1691 | <pre> #define EV_STANDALONE 1 |
|
|
1692 | #include "ev.h" |
|
|
1693 | |
|
|
1694 | </pre> |
|
|
1695 | <p>Both header files and implementation files can be compiled with a C++ |
|
|
1696 | compiler (at least, thats a stated goal, and breakage will be treated |
|
|
1697 | as a bug).</p> |
|
|
1698 | <p>You need the following files in your source tree, or in a directory |
|
|
1699 | in your include path (e.g. in libev/ when using -Ilibev):</p> |
|
|
1700 | <pre> ev.h |
|
|
1701 | ev.c |
|
|
1702 | ev_vars.h |
|
|
1703 | ev_wrap.h |
|
|
1704 | |
|
|
1705 | ev_win32.c required on win32 platforms only |
|
|
1706 | |
|
|
1707 | ev_select.c only when select backend is enabled (which is by default) |
|
|
1708 | ev_poll.c only when poll backend is enabled (disabled by default) |
|
|
1709 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
|
|
1710 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
|
|
1711 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
|
|
1712 | |
|
|
1713 | </pre> |
|
|
1714 | <p><cite>ev.c</cite> includes the backend files directly when enabled, so you only need |
|
|
1715 | to compile this single file.</p> |
|
|
1716 | |
|
|
1717 | </div> |
|
|
1718 | <h3 id="LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</h3> |
|
|
1719 | <div id="LIBEVENT_COMPATIBILITY_API_CONTENT"> |
|
|
1720 | <p>To include the libevent compatibility API, also include:</p> |
|
|
1721 | <pre> #include "event.c" |
|
|
1722 | |
|
|
1723 | </pre> |
|
|
1724 | <p>in the file including <cite>ev.c</cite>, and:</p> |
|
|
1725 | <pre> #include "event.h" |
|
|
1726 | |
|
|
1727 | </pre> |
|
|
1728 | <p>in the files that want to use the libevent API. This also includes <cite>ev.h</cite>.</p> |
|
|
1729 | <p>You need the following additional files for this:</p> |
|
|
1730 | <pre> event.h |
|
|
1731 | event.c |
|
|
1732 | |
|
|
1733 | </pre> |
|
|
1734 | |
|
|
1735 | </div> |
|
|
1736 | <h3 id="AUTOCONF_SUPPORT">AUTOCONF SUPPORT</h3> |
|
|
1737 | <div id="AUTOCONF_SUPPORT_CONTENT"> |
|
|
1738 | <p>Instead of using <code>EV_STANDALONE=1</code> and providing your config in |
|
|
1739 | whatever way you want, you can also <code>m4_include([libev.m4])</code> in your |
|
|
1740 | <cite>configure.ac</cite> and leave <code>EV_STANDALONE</code> undefined. <cite>ev.c</cite> will then |
|
|
1741 | include <cite>config.h</cite> and configure itself accordingly.</p> |
|
|
1742 | <p>For this of course you need the m4 file:</p> |
|
|
1743 | <pre> libev.m4 |
|
|
1744 | |
|
|
1745 | </pre> |
|
|
1746 | |
|
|
1747 | </div> |
|
|
1748 | <h2 id="PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</h2> |
|
|
1749 | <div id="PREPROCESSOR_SYMBOLS_MACROS_CONTENT"> |
|
|
1750 | <p>Libev can be configured via a variety of preprocessor symbols you have to define |
|
|
1751 | before including any of its files. The default is not to build for multiplicity |
|
|
1752 | and only include the select backend.</p> |
|
|
1753 | <dl> |
|
|
1754 | <dt>EV_STANDALONE</dt> |
|
|
1755 | <dd> |
|
|
1756 | <p>Must always be <code>1</code> if you do not use autoconf configuration, which |
|
|
1757 | keeps libev from including <cite>config.h</cite>, and it also defines dummy |
|
|
1758 | implementations for some libevent functions (such as logging, which is not |
|
|
1759 | supported). It will also not define any of the structs usually found in |
|
|
1760 | <cite>event.h</cite> that are not directly supported by the libev core alone.</p> |
|
|
1761 | </dd> |
|
|
1762 | <dt>EV_USE_MONOTONIC</dt> |
|
|
1763 | <dd> |
|
|
1764 | <p>If defined to be <code>1</code>, libev will try to detect the availability of the |
|
|
1765 | monotonic clock option at both compiletime and runtime. Otherwise no use |
|
|
1766 | of the monotonic clock option will be attempted. If you enable this, you |
|
|
1767 | usually have to link against librt or something similar. Enabling it when |
|
|
1768 | the functionality isn't available is safe, though, althoguh you have |
|
|
1769 | to make sure you link against any libraries where the <code>clock_gettime</code> |
|
|
1770 | function is hiding in (often <cite>-lrt</cite>).</p> |
|
|
1771 | </dd> |
|
|
1772 | <dt>EV_USE_REALTIME</dt> |
|
|
1773 | <dd> |
|
|
1774 | <p>If defined to be <code>1</code>, libev will try to detect the availability of the |
|
|
1775 | realtime clock option at compiletime (and assume its availability at |
|
|
1776 | runtime if successful). Otherwise no use of the realtime clock option will |
|
|
1777 | be attempted. This effectively replaces <code>gettimeofday</code> by <code>clock_get |
|
|
1778 | (CLOCK_REALTIME, ...)</code> and will not normally affect correctness. See tzhe note about libraries |
|
|
1779 | in the description of <code>EV_USE_MONOTONIC</code>, though.</p> |
|
|
1780 | </dd> |
|
|
1781 | <dt>EV_USE_SELECT</dt> |
|
|
1782 | <dd> |
|
|
1783 | <p>If undefined or defined to be <code>1</code>, libev will compile in support for the |
|
|
1784 | <code>select</code>(2) backend. No attempt at autodetection will be done: if no |
|
|
1785 | other method takes over, select will be it. Otherwise the select backend |
|
|
1786 | will not be compiled in.</p> |
|
|
1787 | </dd> |
|
|
1788 | <dt>EV_SELECT_USE_FD_SET</dt> |
|
|
1789 | <dd> |
|
|
1790 | <p>If defined to <code>1</code>, then the select backend will use the system <code>fd_set</code> |
|
|
1791 | structure. This is useful if libev doesn't compile due to a missing |
|
|
1792 | <code>NFDBITS</code> or <code>fd_mask</code> definition or it misguesses the bitset layout on |
|
|
1793 | exotic systems. This usually limits the range of file descriptors to some |
|
|
1794 | low limit such as 1024 or might have other limitations (winsocket only |
|
|
1795 | allows 64 sockets). The <code>FD_SETSIZE</code> macro, set before compilation, might |
|
|
1796 | influence the size of the <code>fd_set</code> used.</p> |
|
|
1797 | </dd> |
|
|
1798 | <dt>EV_SELECT_IS_WINSOCKET</dt> |
|
|
1799 | <dd> |
|
|
1800 | <p>When defined to <code>1</code>, the select backend will assume that |
|
|
1801 | select/socket/connect etc. don't understand file descriptors but |
|
|
1802 | wants osf handles on win32 (this is the case when the select to |
|
|
1803 | be used is the winsock select). This means that it will call |
|
|
1804 | <code>_get_osfhandle</code> on the fd to convert it to an OS handle. Otherwise, |
|
|
1805 | it is assumed that all these functions actually work on fds, even |
|
|
1806 | on win32. Should not be defined on non-win32 platforms.</p> |
|
|
1807 | </dd> |
|
|
1808 | <dt>EV_USE_POLL</dt> |
|
|
1809 | <dd> |
|
|
1810 | <p>If defined to be <code>1</code>, libev will compile in support for the <code>poll</code>(2) |
|
|
1811 | backend. Otherwise it will be enabled on non-win32 platforms. It |
|
|
1812 | takes precedence over select.</p> |
|
|
1813 | </dd> |
|
|
1814 | <dt>EV_USE_EPOLL</dt> |
|
|
1815 | <dd> |
|
|
1816 | <p>If defined to be <code>1</code>, libev will compile in support for the Linux |
|
|
1817 | <code>epoll</code>(7) backend. Its availability will be detected at runtime, |
|
|
1818 | otherwise another method will be used as fallback. This is the |
|
|
1819 | preferred backend for GNU/Linux systems.</p> |
|
|
1820 | </dd> |
|
|
1821 | <dt>EV_USE_KQUEUE</dt> |
|
|
1822 | <dd> |
|
|
1823 | <p>If defined to be <code>1</code>, libev will compile in support for the BSD style |
|
|
1824 | <code>kqueue</code>(2) backend. Its actual availability will be detected at runtime, |
|
|
1825 | otherwise another method will be used as fallback. This is the preferred |
|
|
1826 | backend for BSD and BSD-like systems, although on most BSDs kqueue only |
|
|
1827 | supports some types of fds correctly (the only platform we found that |
|
|
1828 | supports ptys for example was NetBSD), so kqueue might be compiled in, but |
|
|
1829 | not be used unless explicitly requested. The best way to use it is to find |
|
|
1830 | out whether kqueue supports your type of fd properly and use an embedded |
|
|
1831 | kqueue loop.</p> |
|
|
1832 | </dd> |
|
|
1833 | <dt>EV_USE_PORT</dt> |
|
|
1834 | <dd> |
|
|
1835 | <p>If defined to be <code>1</code>, libev will compile in support for the Solaris |
|
|
1836 | 10 port style backend. Its availability will be detected at runtime, |
|
|
1837 | otherwise another method will be used as fallback. This is the preferred |
|
|
1838 | backend for Solaris 10 systems.</p> |
|
|
1839 | </dd> |
|
|
1840 | <dt>EV_USE_DEVPOLL</dt> |
|
|
1841 | <dd> |
|
|
1842 | <p>reserved for future expansion, works like the USE symbols above.</p> |
|
|
1843 | </dd> |
|
|
1844 | <dt>EV_H</dt> |
|
|
1845 | <dd> |
|
|
1846 | <p>The name of the <cite>ev.h</cite> header file used to include it. The default if |
|
|
1847 | undefined is <code><ev.h></code> in <cite>event.h</cite> and <code>"ev.h"</code> in <cite>ev.c</cite>. This |
|
|
1848 | can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p> |
|
|
1849 | </dd> |
|
|
1850 | <dt>EV_CONFIG_H</dt> |
|
|
1851 | <dd> |
|
|
1852 | <p>If <code>EV_STANDALONE</code> isn't <code>1</code>, this variable can be used to override |
|
|
1853 | <cite>ev.c</cite>'s idea of where to find the <cite>config.h</cite> file, similarly to |
|
|
1854 | <code>EV_H</code>, above.</p> |
|
|
1855 | </dd> |
|
|
1856 | <dt>EV_EVENT_H</dt> |
|
|
1857 | <dd> |
|
|
1858 | <p>Similarly to <code>EV_H</code>, this macro can be used to override <cite>event.c</cite>'s idea |
|
|
1859 | of how the <cite>event.h</cite> header can be found.</p> |
|
|
1860 | </dd> |
|
|
1861 | <dt>EV_PROTOTYPES</dt> |
|
|
1862 | <dd> |
|
|
1863 | <p>If defined to be <code>0</code>, then <cite>ev.h</cite> will not define any function |
|
|
1864 | prototypes, but still define all the structs and other symbols. This is |
|
|
1865 | occasionally useful if you want to provide your own wrapper functions |
|
|
1866 | around libev functions.</p> |
|
|
1867 | </dd> |
|
|
1868 | <dt>EV_MULTIPLICITY</dt> |
|
|
1869 | <dd> |
|
|
1870 | <p>If undefined or defined to <code>1</code>, then all event-loop-specific functions |
|
|
1871 | will have the <code>struct ev_loop *</code> as first argument, and you can create |
|
|
1872 | additional independent event loops. Otherwise there will be no support |
|
|
1873 | for multiple event loops and there is no first event loop pointer |
|
|
1874 | argument. Instead, all functions act on the single default loop.</p> |
|
|
1875 | </dd> |
|
|
1876 | <dt>EV_PERIODIC_ENABLE</dt> |
|
|
1877 | <dd> |
|
|
1878 | <p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If |
|
|
1879 | defined to be <code>0</code>, then they are not. Disabling them saves a few kB of |
|
|
1880 | code.</p> |
|
|
1881 | </dd> |
|
|
1882 | <dt>EV_EMBED_ENABLE</dt> |
|
|
1883 | <dd> |
|
|
1884 | <p>If undefined or defined to be <code>1</code>, then embed watchers are supported. If |
|
|
1885 | defined to be <code>0</code>, then they are not.</p> |
|
|
1886 | </dd> |
|
|
1887 | <dt>EV_STAT_ENABLE</dt> |
|
|
1888 | <dd> |
|
|
1889 | <p>If undefined or defined to be <code>1</code>, then stat watchers are supported. If |
|
|
1890 | defined to be <code>0</code>, then they are not.</p> |
|
|
1891 | </dd> |
|
|
1892 | <dt>EV_MINIMAL</dt> |
|
|
1893 | <dd> |
|
|
1894 | <p>If you need to shave off some kilobytes of code at the expense of some |
|
|
1895 | speed, define this symbol to <code>1</code>. Currently only used for gcc to override |
|
|
1896 | some inlining decisions, saves roughly 30% codesize of amd64.</p> |
|
|
1897 | </dd> |
|
|
1898 | <dt>EV_COMMON</dt> |
|
|
1899 | <dd> |
|
|
1900 | <p>By default, all watchers have a <code>void *data</code> member. By redefining |
|
|
1901 | this macro to a something else you can include more and other types of |
|
|
1902 | members. You have to define it each time you include one of the files, |
|
|
1903 | though, and it must be identical each time.</p> |
|
|
1904 | <p>For example, the perl EV module uses something like this:</p> |
|
|
1905 | <pre> #define EV_COMMON \ |
|
|
1906 | SV *self; /* contains this struct */ \ |
|
|
1907 | SV *cb_sv, *fh /* note no trailing ";" */ |
|
|
1908 | |
|
|
1909 | </pre> |
|
|
1910 | </dd> |
|
|
1911 | <dt>EV_CB_DECLARE (type)</dt> |
|
|
1912 | <dt>EV_CB_INVOKE (watcher, revents)</dt> |
|
|
1913 | <dt>ev_set_cb (ev, cb)</dt> |
|
|
1914 | <dd> |
|
|
1915 | <p>Can be used to change the callback member declaration in each watcher, |
|
|
1916 | and the way callbacks are invoked and set. Must expand to a struct member |
|
|
1917 | definition and a statement, respectively. See the <cite>ev.v</cite> header file for |
|
|
1918 | their default definitions. One possible use for overriding these is to |
|
|
1919 | avoid the <code>struct ev_loop *</code> as first argument in all cases, or to use |
|
|
1920 | method calls instead of plain function calls in C++.</p> |
|
|
1921 | |
|
|
1922 | </div> |
|
|
1923 | <h2 id="EXAMPLES">EXAMPLES</h2> |
|
|
1924 | <div id="EXAMPLES_CONTENT"> |
|
|
1925 | <p>For a real-world example of a program the includes libev |
|
|
1926 | verbatim, you can have a look at the EV perl module |
|
|
1927 | (<a href="http://software.schmorp.de/pkg/EV.html">http://software.schmorp.de/pkg/EV.html</a>). It has the libev files in |
|
|
1928 | the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public |
|
|
1929 | interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file |
|
|
1930 | will be compiled. It is pretty complex because it provides its own header |
|
|
1931 | file.</p> |
|
|
1932 | <p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file |
|
|
1933 | that everybody includes and which overrides some autoconf choices:</p> |
|
|
1934 | <pre> #define EV_USE_POLL 0 |
|
|
1935 | #define EV_MULTIPLICITY 0 |
|
|
1936 | #define EV_PERIODICS 0 |
|
|
1937 | #define EV_CONFIG_H <config.h> |
|
|
1938 | |
|
|
1939 | #include "ev++.h" |
|
|
1940 | |
|
|
1941 | </pre> |
|
|
1942 | <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p> |
|
|
1943 | <pre> #include "ev_cpp.h" |
|
|
1944 | #include "ev.c" |
|
|
1945 | |
|
|
1946 | |
|
|
1947 | |
|
|
1948 | |
|
|
1949 | </pre> |
|
|
1950 | |
|
|
1951 | </div> |
|
|
1952 | <h1 id="COMPLEXITIES">COMPLEXITIES</h1><p><a href="#TOP" class="toplink">Top</a></p> |
|
|
1953 | <div id="COMPLEXITIES_CONTENT"> |
|
|
1954 | <p>In this section the complexities of (many of) the algorithms used inside |
|
|
1955 | libev will be explained. For complexity discussions about backends see the |
|
|
1956 | documentation for <code>ev_default_init</code>.</p> |
|
|
1957 | <p> |
|
|
1958 | <dl> |
|
|
1959 | <dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt> |
|
|
1960 | <dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt> |
|
|
1961 | <dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt> |
|
|
1962 | <dt>Stopping check/prepare/idle watchers: O(1)</dt> |
|
|
1963 | <dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))</dt> |
|
|
1964 | <dt>Finding the next timer per loop iteration: O(1)</dt> |
|
|
1965 | <dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt> |
|
|
1966 | <dt>Activating one watcher: O(1)</dt> |
|
|
1967 | </dl> |
|
|
1968 | </p> |
|
|
1969 | |
|
|
1970 | |
|
|
1971 | |
|
|
1972 | |
1213 | |
1973 | |
1214 | </div> |
1974 | </div> |
1215 | <h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1975 | <h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1216 | <div id="AUTHOR_CONTENT"> |
1976 | <div id="AUTHOR_CONTENT"> |
1217 | <p>Marc Lehmann <libev@schmorp.de>.</p> |
1977 | <p>Marc Lehmann <libev@schmorp.de>.</p> |
1218 | |
1978 | |
1219 | </div> |
1979 | </div> |
1220 | </div></body> |
1980 | </div></body> |
1221 | </html> |
1981 | </html> |