… | |
… | |
4 | <head> |
4 | <head> |
5 | <title>libev</title> |
5 | <title>libev</title> |
6 | <meta name="description" content="Pod documentation for libev" /> |
6 | <meta name="description" content="Pod documentation for libev" /> |
7 | <meta name="inputfile" content="<standard input>" /> |
7 | <meta name="inputfile" content="<standard input>" /> |
8 | <meta name="outputfile" content="<standard output>" /> |
8 | <meta name="outputfile" content="<standard output>" /> |
9 | <meta name="created" content="Wed Nov 28 19:29:25 2007" /> |
9 | <meta name="created" content="Wed Dec 12 05:53:55 2007" /> |
10 | <meta name="generator" content="Pod::Xhtml 1.57" /> |
10 | <meta name="generator" content="Pod::Xhtml 1.57" /> |
11 | <link rel="stylesheet" href="http://res.tst.eu/pod.css"/></head> |
11 | <link rel="stylesheet" href="http://res.tst.eu/pod.css"/></head> |
12 | <body> |
12 | <body> |
13 | <div class="pod"> |
13 | <div class="pod"> |
14 | <!-- INDEX START --> |
14 | <!-- INDEX START --> |
… | |
… | |
27 | <ul><li><a href="#GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</a></li> |
27 | <ul><li><a href="#GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</a></li> |
28 | <li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li> |
28 | <li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li> |
29 | </ul> |
29 | </ul> |
30 | </li> |
30 | </li> |
31 | <li><a href="#WATCHER_TYPES">WATCHER TYPES</a> |
31 | <li><a href="#WATCHER_TYPES">WATCHER TYPES</a> |
32 | <ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</a></li> |
32 | <ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</a> |
|
|
33 | <ul><li><a href="#The_special_problem_of_disappearing_">The special problem of disappearing file descriptors</a></li> |
|
|
34 | </ul> |
|
|
35 | </li> |
33 | <li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</a></li> |
36 | <li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</a></li> |
34 | <li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</a></li> |
37 | <li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</a></li> |
35 | <li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</a></li> |
38 | <li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</a></li> |
36 | <li><a href="#code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</a></li> |
39 | <li><a href="#code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</a></li> |
37 | <li><a href="#code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</a></li> |
40 | <li><a href="#code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</a></li> |
… | |
… | |
119 | </pre> |
122 | </pre> |
120 | |
123 | |
121 | </div> |
124 | </div> |
122 | <h1 id="DESCRIPTION">DESCRIPTION</h1> |
125 | <h1 id="DESCRIPTION">DESCRIPTION</h1> |
123 | <div id="DESCRIPTION_CONTENT"> |
126 | <div id="DESCRIPTION_CONTENT"> |
|
|
127 | <p>The newest version of this document is also available as a html-formatted |
|
|
128 | web page you might find easier to navigate when reading it for the first |
|
|
129 | time: <a href="http://cvs.schmorp.de/libev/ev.html">http://cvs.schmorp.de/libev/ev.html</a>.</p> |
124 | <p>Libev is an event loop: you register interest in certain events (such as a |
130 | <p>Libev is an event loop: you register interest in certain events (such as a |
125 | file descriptor being readable or a timeout occuring), and it will manage |
131 | file descriptor being readable or a timeout occuring), and it will manage |
126 | these event sources and provide your program with events.</p> |
132 | these event sources and provide your program with events.</p> |
127 | <p>To do this, it must take more or less complete control over your process |
133 | <p>To do this, it must take more or less complete control over your process |
128 | (or thread) by executing the <i>event loop</i> handler, and will then |
134 | (or thread) by executing the <i>event loop</i> handler, and will then |
… | |
… | |
182 | you actually want to know.</p> |
188 | you actually want to know.</p> |
183 | </dd> |
189 | </dd> |
184 | <dt>int ev_version_major ()</dt> |
190 | <dt>int ev_version_major ()</dt> |
185 | <dt>int ev_version_minor ()</dt> |
191 | <dt>int ev_version_minor ()</dt> |
186 | <dd> |
192 | <dd> |
187 | <p>You can find out the major and minor version numbers of the library |
193 | <p>You can find out the major and minor ABI version numbers of the library |
188 | you linked against by calling the functions <code>ev_version_major</code> and |
194 | you linked against by calling the functions <code>ev_version_major</code> and |
189 | <code>ev_version_minor</code>. If you want, you can compare against the global |
195 | <code>ev_version_minor</code>. If you want, you can compare against the global |
190 | symbols <code>EV_VERSION_MAJOR</code> and <code>EV_VERSION_MINOR</code>, which specify the |
196 | symbols <code>EV_VERSION_MAJOR</code> and <code>EV_VERSION_MINOR</code>, which specify the |
191 | version of the library your program was compiled against.</p> |
197 | version of the library your program was compiled against.</p> |
|
|
198 | <p>These version numbers refer to the ABI version of the library, not the |
|
|
199 | release version.</p> |
192 | <p>Usually, it's a good idea to terminate if the major versions mismatch, |
200 | <p>Usually, it's a good idea to terminate if the major versions mismatch, |
193 | as this indicates an incompatible change. Minor versions are usually |
201 | as this indicates an incompatible change. Minor versions are usually |
194 | compatible to older versions, so a larger minor version alone is usually |
202 | compatible to older versions, so a larger minor version alone is usually |
195 | not a problem.</p> |
203 | not a problem.</p> |
196 | <p>Example: Make sure we haven't accidentally been linked against the wrong |
204 | <p>Example: Make sure we haven't accidentally been linked against the wrong |
197 | version.</p> |
205 | version.</p> |
198 | <pre> assert (("libev version mismatch", |
206 | <pre> assert (("libev version mismatch", |
… | |
… | |
326 | <code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will |
334 | <code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will |
327 | override the flags completely if it is found in the environment. This is |
335 | override the flags completely if it is found in the environment. This is |
328 | useful to try out specific backends to test their performance, or to work |
336 | useful to try out specific backends to test their performance, or to work |
329 | around bugs.</p> |
337 | around bugs.</p> |
330 | </dd> |
338 | </dd> |
|
|
339 | <dt><code>EVFLAG_FORKCHECK</code></dt> |
|
|
340 | <dd> |
|
|
341 | <p>Instead of calling <code>ev_default_fork</code> or <code>ev_loop_fork</code> manually after |
|
|
342 | a fork, you can also make libev check for a fork in each iteration by |
|
|
343 | enabling this flag.</p> |
|
|
344 | <p>This works by calling <code>getpid ()</code> on every iteration of the loop, |
|
|
345 | and thus this might slow down your event loop if you do a lot of loop |
|
|
346 | iterations and little real work, but is usually not noticeable (on my |
|
|
347 | Linux system for example, <code>getpid</code> is actually a simple 5-insn sequence |
|
|
348 | without a syscall and thus <i>very</i> fast, but my Linux system also has |
|
|
349 | <code>pthread_atfork</code> which is even faster).</p> |
|
|
350 | <p>The big advantage of this flag is that you can forget about fork (and |
|
|
351 | forget about forgetting to tell libev about forking) when you use this |
|
|
352 | flag.</p> |
|
|
353 | <p>This flag setting cannot be overriden or specified in the <code>LIBEV_FLAGS</code> |
|
|
354 | environment variable.</p> |
|
|
355 | </dd> |
331 | <dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt> |
356 | <dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt> |
332 | <dd> |
357 | <dd> |
333 | <p>This is your standard select(2) backend. Not <i>completely</i> standard, as |
358 | <p>This is your standard select(2) backend. Not <i>completely</i> standard, as |
334 | libev tries to roll its own fd_set with no limits on the number of fds, |
359 | libev tries to roll its own fd_set with no limits on the number of fds, |
335 | but if that fails, expect a fairly low limit on the number of fds when |
360 | but if that fails, expect a fairly low limit on the number of fds when |
… | |
… | |
463 | <dt>ev_loop_fork (loop)</dt> |
488 | <dt>ev_loop_fork (loop)</dt> |
464 | <dd> |
489 | <dd> |
465 | <p>Like <code>ev_default_fork</code>, but acts on an event loop created by |
490 | <p>Like <code>ev_default_fork</code>, but acts on an event loop created by |
466 | <code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop |
491 | <code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop |
467 | after fork, and how you do this is entirely your own problem.</p> |
492 | after fork, and how you do this is entirely your own problem.</p> |
|
|
493 | </dd> |
|
|
494 | <dt>unsigned int ev_loop_count (loop)</dt> |
|
|
495 | <dd> |
|
|
496 | <p>Returns the count of loop iterations for the loop, which is identical to |
|
|
497 | the number of times libev did poll for new events. It starts at <code>0</code> and |
|
|
498 | happily wraps around with enough iterations.</p> |
|
|
499 | <p>This value can sometimes be useful as a generation counter of sorts (it |
|
|
500 | "ticks" the number of loop iterations), as it roughly corresponds with |
|
|
501 | <code>ev_prepare</code> and <code>ev_check</code> calls.</p> |
468 | </dd> |
502 | </dd> |
469 | <dt>unsigned int ev_backend (loop)</dt> |
503 | <dt>unsigned int ev_backend (loop)</dt> |
470 | <dd> |
504 | <dd> |
471 | <p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in |
505 | <p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in |
472 | use.</p> |
506 | use.</p> |
… | |
… | |
500 | one iteration of the loop. This is useful if you are waiting for some |
534 | one iteration of the loop. This is useful if you are waiting for some |
501 | external event in conjunction with something not expressible using other |
535 | external event in conjunction with something not expressible using other |
502 | libev watchers. However, a pair of <code>ev_prepare</code>/<code>ev_check</code> watchers is |
536 | libev watchers. However, a pair of <code>ev_prepare</code>/<code>ev_check</code> watchers is |
503 | usually a better approach for this kind of thing.</p> |
537 | usually a better approach for this kind of thing.</p> |
504 | <p>Here are the gory details of what <code>ev_loop</code> does:</p> |
538 | <p>Here are the gory details of what <code>ev_loop</code> does:</p> |
|
|
539 | <pre> - Before the first iteration, call any pending watchers. |
505 | <pre> * If there are no active watchers (reference count is zero), return. |
540 | * If there are no active watchers (reference count is zero), return. |
506 | - Queue prepare watchers and then call all outstanding watchers. |
541 | - Queue all prepare watchers and then call all outstanding watchers. |
507 | - If we have been forked, recreate the kernel state. |
542 | - If we have been forked, recreate the kernel state. |
508 | - Update the kernel state with all outstanding changes. |
543 | - Update the kernel state with all outstanding changes. |
509 | - Update the "event loop time". |
544 | - Update the "event loop time". |
510 | - Calculate for how long to block. |
545 | - Calculate for how long to block. |
511 | - Block the process, waiting for any events. |
546 | - Block the process, waiting for any events. |
… | |
… | |
740 | <dt>bool ev_is_pending (ev_TYPE *watcher)</dt> |
775 | <dt>bool ev_is_pending (ev_TYPE *watcher)</dt> |
741 | <dd> |
776 | <dd> |
742 | <p>Returns a true value iff the watcher is pending, (i.e. it has outstanding |
777 | <p>Returns a true value iff the watcher is pending, (i.e. it has outstanding |
743 | events but its callback has not yet been invoked). As long as a watcher |
778 | events but its callback has not yet been invoked). As long as a watcher |
744 | is pending (but not active) you must not call an init function on it (but |
779 | is pending (but not active) you must not call an init function on it (but |
745 | <code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to |
780 | <code>ev_TYPE_set</code> is safe), you must not change its priority, and you must |
746 | libev (e.g. you cnanot <code>free ()</code> it).</p> |
781 | make sure the watcher is available to libev (e.g. you cannot <code>free ()</code> |
|
|
782 | it).</p> |
747 | </dd> |
783 | </dd> |
748 | <dt>callback ev_cb (ev_TYPE *watcher)</dt> |
784 | <dt>callback ev_cb (ev_TYPE *watcher)</dt> |
749 | <dd> |
785 | <dd> |
750 | <p>Returns the callback currently set on the watcher.</p> |
786 | <p>Returns the callback currently set on the watcher.</p> |
751 | </dd> |
787 | </dd> |
752 | <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt> |
788 | <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt> |
753 | <dd> |
789 | <dd> |
754 | <p>Change the callback. You can change the callback at virtually any time |
790 | <p>Change the callback. You can change the callback at virtually any time |
755 | (modulo threads).</p> |
791 | (modulo threads).</p> |
|
|
792 | </dd> |
|
|
793 | <dt>ev_set_priority (ev_TYPE *watcher, priority)</dt> |
|
|
794 | <dt>int ev_priority (ev_TYPE *watcher)</dt> |
|
|
795 | <dd> |
|
|
796 | <p>Set and query the priority of the watcher. The priority is a small |
|
|
797 | integer between <code>EV_MAXPRI</code> (default: <code>2</code>) and <code>EV_MINPRI</code> |
|
|
798 | (default: <code>-2</code>). Pending watchers with higher priority will be invoked |
|
|
799 | before watchers with lower priority, but priority will not keep watchers |
|
|
800 | from being executed (except for <code>ev_idle</code> watchers).</p> |
|
|
801 | <p>This means that priorities are <i>only</i> used for ordering callback |
|
|
802 | invocation after new events have been received. This is useful, for |
|
|
803 | example, to reduce latency after idling, or more often, to bind two |
|
|
804 | watchers on the same event and make sure one is called first.</p> |
|
|
805 | <p>If you need to suppress invocation when higher priority events are pending |
|
|
806 | you need to look at <code>ev_idle</code> watchers, which provide this functionality.</p> |
|
|
807 | <p>You <i>must not</i> change the priority of a watcher as long as it is active or |
|
|
808 | pending.</p> |
|
|
809 | <p>The default priority used by watchers when no priority has been set is |
|
|
810 | always <code>0</code>, which is supposed to not be too high and not be too low :).</p> |
|
|
811 | <p>Setting a priority outside the range of <code>EV_MINPRI</code> to <code>EV_MAXPRI</code> is |
|
|
812 | fine, as long as you do not mind that the priority value you query might |
|
|
813 | or might not have been adjusted to be within valid range.</p> |
|
|
814 | </dd> |
|
|
815 | <dt>ev_invoke (loop, ev_TYPE *watcher, int revents)</dt> |
|
|
816 | <dd> |
|
|
817 | <p>Invoke the <code>watcher</code> with the given <code>loop</code> and <code>revents</code>. Neither |
|
|
818 | <code>loop</code> nor <code>revents</code> need to be valid as long as the watcher callback |
|
|
819 | can deal with that fact.</p> |
|
|
820 | </dd> |
|
|
821 | <dt>int ev_clear_pending (loop, ev_TYPE *watcher)</dt> |
|
|
822 | <dd> |
|
|
823 | <p>If the watcher is pending, this function returns clears its pending status |
|
|
824 | and returns its <code>revents</code> bitset (as if its callback was invoked). If the |
|
|
825 | watcher isn't pending it does nothing and returns <code>0</code>.</p> |
756 | </dd> |
826 | </dd> |
757 | </dl> |
827 | </dl> |
758 | |
828 | |
759 | |
829 | |
760 | |
830 | |
… | |
… | |
871 | this situation even with a relatively standard program structure. Thus |
941 | this situation even with a relatively standard program structure. Thus |
872 | it is best to always use non-blocking I/O: An extra <code>read</code>(2) returning |
942 | it is best to always use non-blocking I/O: An extra <code>read</code>(2) returning |
873 | <code>EAGAIN</code> is far preferable to a program hanging until some data arrives.</p> |
943 | <code>EAGAIN</code> is far preferable to a program hanging until some data arrives.</p> |
874 | <p>If you cannot run the fd in non-blocking mode (for example you should not |
944 | <p>If you cannot run the fd in non-blocking mode (for example you should not |
875 | play around with an Xlib connection), then you have to seperately re-test |
945 | play around with an Xlib connection), then you have to seperately re-test |
876 | wether a file descriptor is really ready with a known-to-be good interface |
946 | whether a file descriptor is really ready with a known-to-be good interface |
877 | such as poll (fortunately in our Xlib example, Xlib already does this on |
947 | such as poll (fortunately in our Xlib example, Xlib already does this on |
878 | its own, so its quite safe to use).</p> |
948 | its own, so its quite safe to use).</p> |
|
|
949 | |
|
|
950 | </div> |
|
|
951 | <h3 id="The_special_problem_of_disappearing_">The special problem of disappearing file descriptors</h3> |
|
|
952 | <div id="The_special_problem_of_disappearing_-2"> |
|
|
953 | <p>Some backends (e.g kqueue, epoll) need to be told about closing a file |
|
|
954 | descriptor (either by calling <code>close</code> explicitly or by any other means, |
|
|
955 | such as <code>dup</code>). The reason is that you register interest in some file |
|
|
956 | descriptor, but when it goes away, the operating system will silently drop |
|
|
957 | this interest. If another file descriptor with the same number then is |
|
|
958 | registered with libev, there is no efficient way to see that this is, in |
|
|
959 | fact, a different file descriptor.</p> |
|
|
960 | <p>To avoid having to explicitly tell libev about such cases, libev follows |
|
|
961 | the following policy: Each time <code>ev_io_set</code> is being called, libev |
|
|
962 | will assume that this is potentially a new file descriptor, otherwise |
|
|
963 | it is assumed that the file descriptor stays the same. That means that |
|
|
964 | you <i>have</i> to call <code>ev_io_set</code> (or <code>ev_io_init</code>) when you change the |
|
|
965 | descriptor even if the file descriptor number itself did not change.</p> |
|
|
966 | <p>This is how one would do it normally anyway, the important point is that |
|
|
967 | the libev application should not optimise around libev but should leave |
|
|
968 | optimisations to libev.</p> |
|
|
969 | |
|
|
970 | |
|
|
971 | |
|
|
972 | |
879 | <dl> |
973 | <dl> |
880 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
974 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
881 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
975 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
882 | <dd> |
976 | <dd> |
883 | <p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to |
977 | <p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to |
… | |
… | |
952 | </dd> |
1046 | </dd> |
953 | <dt>ev_timer_again (loop)</dt> |
1047 | <dt>ev_timer_again (loop)</dt> |
954 | <dd> |
1048 | <dd> |
955 | <p>This will act as if the timer timed out and restart it again if it is |
1049 | <p>This will act as if the timer timed out and restart it again if it is |
956 | repeating. The exact semantics are:</p> |
1050 | repeating. The exact semantics are:</p> |
|
|
1051 | <p>If the timer is pending, its pending status is cleared.</p> |
957 | <p>If the timer is started but nonrepeating, stop it.</p> |
1052 | <p>If the timer is started but nonrepeating, stop it (as if it timed out).</p> |
958 | <p>If the timer is repeating, either start it if necessary (with the repeat |
1053 | <p>If the timer is repeating, either start it if necessary (with the |
959 | value), or reset the running timer to the repeat value.</p> |
1054 | <code>repeat</code> value), or reset the running timer to the <code>repeat</code> value.</p> |
960 | <p>This sounds a bit complicated, but here is a useful and typical |
1055 | <p>This sounds a bit complicated, but here is a useful and typical |
961 | example: Imagine you have a tcp connection and you want a so-called |
1056 | example: Imagine you have a tcp connection and you want a so-called idle |
962 | idle timeout, that is, you want to be called when there have been, |
1057 | timeout, that is, you want to be called when there have been, say, 60 |
963 | say, 60 seconds of inactivity on the socket. The easiest way to do |
1058 | seconds of inactivity on the socket. The easiest way to do this is to |
964 | this is to configure an <code>ev_timer</code> with <code>after</code>=<code>repeat</code>=<code>60</code> and calling |
1059 | configure an <code>ev_timer</code> with a <code>repeat</code> value of <code>60</code> and then call |
965 | <code>ev_timer_again</code> each time you successfully read or write some data. If |
1060 | <code>ev_timer_again</code> each time you successfully read or write some data. If |
966 | you go into an idle state where you do not expect data to travel on the |
1061 | you go into an idle state where you do not expect data to travel on the |
967 | socket, you can stop the timer, and again will automatically restart it if |
1062 | socket, you can <code>ev_timer_stop</code> the timer, and <code>ev_timer_again</code> will |
968 | need be.</p> |
1063 | automatically restart it if need be.</p> |
969 | <p>You can also ignore the <code>after</code> value and <code>ev_timer_start</code> altogether |
1064 | <p>That means you can ignore the <code>after</code> value and <code>ev_timer_start</code> |
970 | and only ever use the <code>repeat</code> value:</p> |
1065 | altogether and only ever use the <code>repeat</code> value and <code>ev_timer_again</code>:</p> |
971 | <pre> ev_timer_init (timer, callback, 0., 5.); |
1066 | <pre> ev_timer_init (timer, callback, 0., 5.); |
972 | ev_timer_again (loop, timer); |
1067 | ev_timer_again (loop, timer); |
973 | ... |
1068 | ... |
974 | timer->again = 17.; |
1069 | timer->again = 17.; |
975 | ev_timer_again (loop, timer); |
1070 | ev_timer_again (loop, timer); |
976 | ... |
1071 | ... |
977 | timer->again = 10.; |
1072 | timer->again = 10.; |
978 | ev_timer_again (loop, timer); |
1073 | ev_timer_again (loop, timer); |
979 | |
1074 | |
980 | </pre> |
1075 | </pre> |
981 | <p>This is more efficient then stopping/starting the timer eahc time you want |
1076 | <p>This is more slightly efficient then stopping/starting the timer each time |
982 | to modify its timeout value.</p> |
1077 | you want to modify its timeout value.</p> |
983 | </dd> |
1078 | </dd> |
984 | <dt>ev_tstamp repeat [read-write]</dt> |
1079 | <dt>ev_tstamp repeat [read-write]</dt> |
985 | <dd> |
1080 | <dd> |
986 | <p>The current <code>repeat</code> value. Will be used each time the watcher times out |
1081 | <p>The current <code>repeat</code> value. Will be used each time the watcher times out |
987 | or <code>ev_timer_again</code> is called and determines the next timeout (if any), |
1082 | or <code>ev_timer_again</code> is called and determines the next timeout (if any), |
… | |
… | |
1031 | but on wallclock time (absolute time). You can tell a periodic watcher |
1126 | but on wallclock time (absolute time). You can tell a periodic watcher |
1032 | to trigger "at" some specific point in time. For example, if you tell a |
1127 | to trigger "at" some specific point in time. For example, if you tell a |
1033 | periodic watcher to trigger in 10 seconds (by specifiying e.g. <code>ev_now () |
1128 | periodic watcher to trigger in 10 seconds (by specifiying e.g. <code>ev_now () |
1034 | + 10.</code>) and then reset your system clock to the last year, then it will |
1129 | + 10.</code>) and then reset your system clock to the last year, then it will |
1035 | take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger |
1130 | take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger |
1036 | roughly 10 seconds later and of course not if you reset your system time |
1131 | roughly 10 seconds later).</p> |
1037 | again).</p> |
|
|
1038 | <p>They can also be used to implement vastly more complex timers, such as |
1132 | <p>They can also be used to implement vastly more complex timers, such as |
1039 | triggering an event on eahc midnight, local time.</p> |
1133 | triggering an event on each midnight, local time or other, complicated, |
|
|
1134 | rules.</p> |
1040 | <p>As with timers, the callback is guarenteed to be invoked only when the |
1135 | <p>As with timers, the callback is guarenteed to be invoked only when the |
1041 | time (<code>at</code>) has been passed, but if multiple periodic timers become ready |
1136 | time (<code>at</code>) has been passed, but if multiple periodic timers become ready |
1042 | during the same loop iteration then order of execution is undefined.</p> |
1137 | during the same loop iteration then order of execution is undefined.</p> |
1043 | <dl> |
1138 | <dl> |
1044 | <dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt> |
1139 | <dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt> |
… | |
… | |
1046 | <dd> |
1141 | <dd> |
1047 | <p>Lots of arguments, lets sort it out... There are basically three modes of |
1142 | <p>Lots of arguments, lets sort it out... There are basically three modes of |
1048 | operation, and we will explain them from simplest to complex:</p> |
1143 | operation, and we will explain them from simplest to complex:</p> |
1049 | <p> |
1144 | <p> |
1050 | <dl> |
1145 | <dl> |
1051 | <dt>* absolute timer (interval = reschedule_cb = 0)</dt> |
1146 | <dt>* absolute timer (at = time, interval = reschedule_cb = 0)</dt> |
1052 | <dd> |
1147 | <dd> |
1053 | <p>In this configuration the watcher triggers an event at the wallclock time |
1148 | <p>In this configuration the watcher triggers an event at the wallclock time |
1054 | <code>at</code> and doesn't repeat. It will not adjust when a time jump occurs, |
1149 | <code>at</code> and doesn't repeat. It will not adjust when a time jump occurs, |
1055 | that is, if it is to be run at January 1st 2011 then it will run when the |
1150 | that is, if it is to be run at January 1st 2011 then it will run when the |
1056 | system time reaches or surpasses this time.</p> |
1151 | system time reaches or surpasses this time.</p> |
1057 | </dd> |
1152 | </dd> |
1058 | <dt>* non-repeating interval timer (interval > 0, reschedule_cb = 0)</dt> |
1153 | <dt>* non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)</dt> |
1059 | <dd> |
1154 | <dd> |
1060 | <p>In this mode the watcher will always be scheduled to time out at the next |
1155 | <p>In this mode the watcher will always be scheduled to time out at the next |
1061 | <code>at + N * interval</code> time (for some integer N) and then repeat, regardless |
1156 | <code>at + N * interval</code> time (for some integer N, which can also be negative) |
1062 | of any time jumps.</p> |
1157 | and then repeat, regardless of any time jumps.</p> |
1063 | <p>This can be used to create timers that do not drift with respect to system |
1158 | <p>This can be used to create timers that do not drift with respect to system |
1064 | time:</p> |
1159 | time:</p> |
1065 | <pre> ev_periodic_set (&periodic, 0., 3600., 0); |
1160 | <pre> ev_periodic_set (&periodic, 0., 3600., 0); |
1066 | |
1161 | |
1067 | </pre> |
1162 | </pre> |
… | |
… | |
1070 | full hour (UTC), or more correctly, when the system time is evenly divisible |
1165 | full hour (UTC), or more correctly, when the system time is evenly divisible |
1071 | by 3600.</p> |
1166 | by 3600.</p> |
1072 | <p>Another way to think about it (for the mathematically inclined) is that |
1167 | <p>Another way to think about it (for the mathematically inclined) is that |
1073 | <code>ev_periodic</code> will try to run the callback in this mode at the next possible |
1168 | <code>ev_periodic</code> will try to run the callback in this mode at the next possible |
1074 | time where <code>time = at (mod interval)</code>, regardless of any time jumps.</p> |
1169 | time where <code>time = at (mod interval)</code>, regardless of any time jumps.</p> |
|
|
1170 | <p>For numerical stability it is preferable that the <code>at</code> value is near |
|
|
1171 | <code>ev_now ()</code> (the current time), but there is no range requirement for |
|
|
1172 | this value.</p> |
1075 | </dd> |
1173 | </dd> |
1076 | <dt>* manual reschedule mode (reschedule_cb = callback)</dt> |
1174 | <dt>* manual reschedule mode (at and interval ignored, reschedule_cb = callback)</dt> |
1077 | <dd> |
1175 | <dd> |
1078 | <p>In this mode the values for <code>interval</code> and <code>at</code> are both being |
1176 | <p>In this mode the values for <code>interval</code> and <code>at</code> are both being |
1079 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1177 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1080 | reschedule callback will be called with the watcher as first, and the |
1178 | reschedule callback will be called with the watcher as first, and the |
1081 | current time as second argument.</p> |
1179 | current time as second argument.</p> |
1082 | <p>NOTE: <i>This callback MUST NOT stop or destroy any periodic watcher, |
1180 | <p>NOTE: <i>This callback MUST NOT stop or destroy any periodic watcher, |
1083 | ever, or make any event loop modifications</i>. If you need to stop it, |
1181 | ever, or make any event loop modifications</i>. If you need to stop it, |
1084 | return <code>now + 1e30</code> (or so, fudge fudge) and stop it afterwards (e.g. by |
1182 | return <code>now + 1e30</code> (or so, fudge fudge) and stop it afterwards (e.g. by |
1085 | starting a prepare watcher).</p> |
1183 | starting an <code>ev_prepare</code> watcher, which is legal).</p> |
1086 | <p>Its prototype is <code>ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1184 | <p>Its prototype is <code>ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1087 | ev_tstamp now)</code>, e.g.:</p> |
1185 | ev_tstamp now)</code>, e.g.:</p> |
1088 | <pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1186 | <pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1089 | { |
1187 | { |
1090 | return now + 60.; |
1188 | return now + 60.; |
… | |
… | |
1110 | <dd> |
1208 | <dd> |
1111 | <p>Simply stops and restarts the periodic watcher again. This is only useful |
1209 | <p>Simply stops and restarts the periodic watcher again. This is only useful |
1112 | when you changed some parameters or the reschedule callback would return |
1210 | when you changed some parameters or the reschedule callback would return |
1113 | a different time than the last time it was called (e.g. in a crond like |
1211 | a different time than the last time it was called (e.g. in a crond like |
1114 | program when the crontabs have changed).</p> |
1212 | program when the crontabs have changed).</p> |
|
|
1213 | </dd> |
|
|
1214 | <dt>ev_tstamp offset [read-write]</dt> |
|
|
1215 | <dd> |
|
|
1216 | <p>When repeating, this contains the offset value, otherwise this is the |
|
|
1217 | absolute point in time (the <code>at</code> value passed to <code>ev_periodic_set</code>).</p> |
|
|
1218 | <p>Can be modified any time, but changes only take effect when the periodic |
|
|
1219 | timer fires or <code>ev_periodic_again</code> is being called.</p> |
1115 | </dd> |
1220 | </dd> |
1116 | <dt>ev_tstamp interval [read-write]</dt> |
1221 | <dt>ev_tstamp interval [read-write]</dt> |
1117 | <dd> |
1222 | <dd> |
1118 | <p>The current interval value. Can be modified any time, but changes only |
1223 | <p>The current interval value. Can be modified any time, but changes only |
1119 | take effect when the periodic timer fires or <code>ev_periodic_again</code> is being |
1224 | take effect when the periodic timer fires or <code>ev_periodic_again</code> is being |
… | |
… | |
1340 | </pre> |
1445 | </pre> |
1341 | |
1446 | |
1342 | </div> |
1447 | </div> |
1343 | <h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2> |
1448 | <h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2> |
1344 | <div id="code_ev_idle_code_when_you_ve_got_no-2"> |
1449 | <div id="code_ev_idle_code_when_you_ve_got_no-2"> |
1345 | <p>Idle watchers trigger events when there are no other events are pending |
1450 | <p>Idle watchers trigger events when no other events of the same or higher |
1346 | (prepare, check and other idle watchers do not count). That is, as long |
1451 | priority are pending (prepare, check and other idle watchers do not |
1347 | as your process is busy handling sockets or timeouts (or even signals, |
1452 | count).</p> |
1348 | imagine) it will not be triggered. But when your process is idle all idle |
1453 | <p>That is, as long as your process is busy handling sockets or timeouts |
1349 | watchers are being called again and again, once per event loop iteration - |
1454 | (or even signals, imagine) of the same or higher priority it will not be |
|
|
1455 | triggered. But when your process is idle (or only lower-priority watchers |
|
|
1456 | are pending), the idle watchers are being called once per event loop |
1350 | until stopped, that is, or your process receives more events and becomes |
1457 | iteration - until stopped, that is, or your process receives more events |
1351 | busy.</p> |
1458 | and becomes busy again with higher priority stuff.</p> |
1352 | <p>The most noteworthy effect is that as long as any idle watchers are |
1459 | <p>The most noteworthy effect is that as long as any idle watchers are |
1353 | active, the process will not block when waiting for new events.</p> |
1460 | active, the process will not block when waiting for new events.</p> |
1354 | <p>Apart from keeping your process non-blocking (which is a useful |
1461 | <p>Apart from keeping your process non-blocking (which is a useful |
1355 | effect on its own sometimes), idle watchers are a good place to do |
1462 | effect on its own sometimes), idle watchers are a good place to do |
1356 | "pseudo-background processing", or delay processing stuff to after the |
1463 | "pseudo-background processing", or delay processing stuff to after the |
… | |
… | |
1416 | are ready to run (it's actually more complicated: it only runs coroutines |
1523 | are ready to run (it's actually more complicated: it only runs coroutines |
1417 | with priority higher than or equal to the event loop and one coroutine |
1524 | with priority higher than or equal to the event loop and one coroutine |
1418 | of lower priority, but only once, using idle watchers to keep the event |
1525 | of lower priority, but only once, using idle watchers to keep the event |
1419 | loop from blocking if lower-priority coroutines are active, thus mapping |
1526 | loop from blocking if lower-priority coroutines are active, thus mapping |
1420 | low-priority coroutines to idle/background tasks).</p> |
1527 | low-priority coroutines to idle/background tasks).</p> |
|
|
1528 | <p>It is recommended to give <code>ev_check</code> watchers highest (<code>EV_MAXPRI</code>) |
|
|
1529 | priority, to ensure that they are being run before any other watchers |
|
|
1530 | after the poll. Also, <code>ev_check</code> watchers (and <code>ev_prepare</code> watchers, |
|
|
1531 | too) should not activate ("feed") events into libev. While libev fully |
|
|
1532 | supports this, they will be called before other <code>ev_check</code> watchers did |
|
|
1533 | their job. As <code>ev_check</code> watchers are often used to embed other event |
|
|
1534 | loops those other event loops might be in an unusable state until their |
|
|
1535 | <code>ev_check</code> watcher ran (always remind yourself to coexist peacefully with |
|
|
1536 | others).</p> |
1421 | <dl> |
1537 | <dl> |
1422 | <dt>ev_prepare_init (ev_prepare *, callback)</dt> |
1538 | <dt>ev_prepare_init (ev_prepare *, callback)</dt> |
1423 | <dt>ev_check_init (ev_check *, callback)</dt> |
1539 | <dt>ev_check_init (ev_check *, callback)</dt> |
1424 | <dd> |
1540 | <dd> |
1425 | <p>Initialises and configures the prepare or check watcher - they have no |
1541 | <p>Initialises and configures the prepare or check watcher - they have no |
1426 | parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code> |
1542 | parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code> |
1427 | macros, but using them is utterly, utterly and completely pointless.</p> |
1543 | macros, but using them is utterly, utterly and completely pointless.</p> |
1428 | </dd> |
1544 | </dd> |
1429 | </dl> |
1545 | </dl> |
1430 | <p>Example: To include a library such as adns, you would add IO watchers |
1546 | <p>There are a number of principal ways to embed other event loops or modules |
1431 | and a timeout watcher in a prepare handler, as required by libadns, and |
1547 | into libev. Here are some ideas on how to include libadns into libev |
|
|
1548 | (there is a Perl module named <code>EV::ADNS</code> that does this, which you could |
|
|
1549 | use for an actually working example. Another Perl module named <code>EV::Glib</code> |
|
|
1550 | embeds a Glib main context into libev, and finally, <code>Glib::EV</code> embeds EV |
|
|
1551 | into the Glib event loop).</p> |
|
|
1552 | <p>Method 1: Add IO watchers and a timeout watcher in a prepare handler, |
1432 | in a check watcher, destroy them and call into libadns. What follows is |
1553 | and in a check watcher, destroy them and call into libadns. What follows |
1433 | pseudo-code only of course:</p> |
1554 | is pseudo-code only of course. This requires you to either use a low |
|
|
1555 | priority for the check watcher or use <code>ev_clear_pending</code> explicitly, as |
|
|
1556 | the callbacks for the IO/timeout watchers might not have been called yet.</p> |
1434 | <pre> static ev_io iow [nfd]; |
1557 | <pre> static ev_io iow [nfd]; |
1435 | static ev_timer tw; |
1558 | static ev_timer tw; |
1436 | |
1559 | |
1437 | static void |
1560 | static void |
1438 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1561 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1439 | { |
1562 | { |
1440 | // set the relevant poll flags |
|
|
1441 | // could also call adns_processreadable etc. here |
|
|
1442 | struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1443 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1444 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1445 | } |
1563 | } |
1446 | |
1564 | |
1447 | // create io watchers for each fd and a timer before blocking |
1565 | // create io watchers for each fd and a timer before blocking |
1448 | static void |
1566 | static void |
1449 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1567 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1450 | { |
1568 | { |
1451 | int timeout = 3600000;truct pollfd fds [nfd]; |
1569 | int timeout = 3600000; |
|
|
1570 | struct pollfd fds [nfd]; |
1452 | // actual code will need to loop here and realloc etc. |
1571 | // actual code will need to loop here and realloc etc. |
1453 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1572 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1454 | |
1573 | |
1455 | /* the callback is illegal, but won't be called as we stop during check */ |
1574 | /* the callback is illegal, but won't be called as we stop during check */ |
1456 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1575 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1457 | ev_timer_start (loop, &tw); |
1576 | ev_timer_start (loop, &tw); |
1458 | |
1577 | |
1459 | // create on ev_io per pollfd |
1578 | // create one ev_io per pollfd |
1460 | for (int i = 0; i < nfd; ++i) |
1579 | for (int i = 0; i < nfd; ++i) |
1461 | { |
1580 | { |
1462 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1581 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1463 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1582 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1464 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1583 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1465 | |
1584 | |
1466 | fds [i].revents = 0; |
1585 | fds [i].revents = 0; |
1467 | iow [i].data = fds + i; |
|
|
1468 | ev_io_start (loop, iow + i); |
1586 | ev_io_start (loop, iow + i); |
1469 | } |
1587 | } |
1470 | } |
1588 | } |
1471 | |
1589 | |
1472 | // stop all watchers after blocking |
1590 | // stop all watchers after blocking |
… | |
… | |
1474 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1592 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1475 | { |
1593 | { |
1476 | ev_timer_stop (loop, &tw); |
1594 | ev_timer_stop (loop, &tw); |
1477 | |
1595 | |
1478 | for (int i = 0; i < nfd; ++i) |
1596 | for (int i = 0; i < nfd; ++i) |
|
|
1597 | { |
|
|
1598 | // set the relevant poll flags |
|
|
1599 | // could also call adns_processreadable etc. here |
|
|
1600 | struct pollfd *fd = fds + i; |
|
|
1601 | int revents = ev_clear_pending (iow + i); |
|
|
1602 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1603 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1604 | |
|
|
1605 | // now stop the watcher |
1479 | ev_io_stop (loop, iow + i); |
1606 | ev_io_stop (loop, iow + i); |
|
|
1607 | } |
1480 | |
1608 | |
1481 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
1609 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1610 | } |
|
|
1611 | |
|
|
1612 | </pre> |
|
|
1613 | <p>Method 2: This would be just like method 1, but you run <code>adns_afterpoll</code> |
|
|
1614 | in the prepare watcher and would dispose of the check watcher.</p> |
|
|
1615 | <p>Method 3: If the module to be embedded supports explicit event |
|
|
1616 | notification (adns does), you can also make use of the actual watcher |
|
|
1617 | callbacks, and only destroy/create the watchers in the prepare watcher.</p> |
|
|
1618 | <pre> static void |
|
|
1619 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1620 | { |
|
|
1621 | adns_state ads = (adns_state)w->data; |
|
|
1622 | update_now (EV_A); |
|
|
1623 | |
|
|
1624 | adns_processtimeouts (ads, &tv_now); |
|
|
1625 | } |
|
|
1626 | |
|
|
1627 | static void |
|
|
1628 | io_cb (EV_P_ ev_io *w, int revents) |
|
|
1629 | { |
|
|
1630 | adns_state ads = (adns_state)w->data; |
|
|
1631 | update_now (EV_A); |
|
|
1632 | |
|
|
1633 | if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now); |
|
|
1634 | if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now); |
|
|
1635 | } |
|
|
1636 | |
|
|
1637 | // do not ever call adns_afterpoll |
|
|
1638 | |
|
|
1639 | </pre> |
|
|
1640 | <p>Method 4: Do not use a prepare or check watcher because the module you |
|
|
1641 | want to embed is too inflexible to support it. Instead, youc na override |
|
|
1642 | their poll function. The drawback with this solution is that the main |
|
|
1643 | loop is now no longer controllable by EV. The <code>Glib::EV</code> module does |
|
|
1644 | this.</p> |
|
|
1645 | <pre> static gint |
|
|
1646 | event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
|
|
1647 | { |
|
|
1648 | int got_events = 0; |
|
|
1649 | |
|
|
1650 | for (n = 0; n < nfds; ++n) |
|
|
1651 | // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
|
|
1652 | |
|
|
1653 | if (timeout >= 0) |
|
|
1654 | // create/start timer |
|
|
1655 | |
|
|
1656 | // poll |
|
|
1657 | ev_loop (EV_A_ 0); |
|
|
1658 | |
|
|
1659 | // stop timer again |
|
|
1660 | if (timeout >= 0) |
|
|
1661 | ev_timer_stop (EV_A_ &to); |
|
|
1662 | |
|
|
1663 | // stop io watchers again - their callbacks should have set |
|
|
1664 | for (n = 0; n < nfds; ++n) |
|
|
1665 | ev_io_stop (EV_A_ iow [n]); |
|
|
1666 | |
|
|
1667 | return got_events; |
1482 | } |
1668 | } |
1483 | |
1669 | |
1484 | |
1670 | |
1485 | |
1671 | |
1486 | |
1672 | |
… | |
… | |
1683 | the callback model to a model using method callbacks on objects.</p> |
1869 | the callback model to a model using method callbacks on objects.</p> |
1684 | <p>To use it,</p> |
1870 | <p>To use it,</p> |
1685 | <pre> #include <ev++.h> |
1871 | <pre> #include <ev++.h> |
1686 | |
1872 | |
1687 | </pre> |
1873 | </pre> |
1688 | <p>(it is not installed by default). This automatically includes <cite>ev.h</cite> |
1874 | <p>This automatically includes <cite>ev.h</cite> and puts all of its definitions (many |
1689 | and puts all of its definitions (many of them macros) into the global |
1875 | of them macros) into the global namespace. All C++ specific things are |
1690 | namespace. All C++ specific things are put into the <code>ev</code> namespace.</p> |
1876 | put into the <code>ev</code> namespace. It should support all the same embedding |
1691 | <p>It should support all the same embedding options as <cite>ev.h</cite>, most notably |
1877 | options as <cite>ev.h</cite>, most notably <code>EV_MULTIPLICITY</code>.</p> |
1692 | <code>EV_MULTIPLICITY</code>.</p> |
1878 | <p>Care has been taken to keep the overhead low. The only data member the C++ |
|
|
1879 | classes add (compared to plain C-style watchers) is the event loop pointer |
|
|
1880 | that the watcher is associated with (or no additional members at all if |
|
|
1881 | you disable <code>EV_MULTIPLICITY</code> when embedding libev).</p> |
|
|
1882 | <p>Currently, functions, and static and non-static member functions can be |
|
|
1883 | used as callbacks. Other types should be easy to add as long as they only |
|
|
1884 | need one additional pointer for context. If you need support for other |
|
|
1885 | types of functors please contact the author (preferably after implementing |
|
|
1886 | it).</p> |
1693 | <p>Here is a list of things available in the <code>ev</code> namespace:</p> |
1887 | <p>Here is a list of things available in the <code>ev</code> namespace:</p> |
1694 | <dl> |
1888 | <dl> |
1695 | <dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt> |
1889 | <dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt> |
1696 | <dd> |
1890 | <dd> |
1697 | <p>These are just enum values with the same values as the <code>EV_READ</code> etc. |
1891 | <p>These are just enum values with the same values as the <code>EV_READ</code> etc. |
… | |
… | |
1708 | which is called <code>ev::sig</code> to avoid clashes with the <code>signal</code> macro |
1902 | which is called <code>ev::sig</code> to avoid clashes with the <code>signal</code> macro |
1709 | defines by many implementations.</p> |
1903 | defines by many implementations.</p> |
1710 | <p>All of those classes have these methods:</p> |
1904 | <p>All of those classes have these methods:</p> |
1711 | <p> |
1905 | <p> |
1712 | <dl> |
1906 | <dl> |
1713 | <dt>ev::TYPE::TYPE (object *, object::method *)</dt> |
1907 | <dt>ev::TYPE::TYPE ()</dt> |
1714 | <dt>ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)</dt> |
1908 | <dt>ev::TYPE::TYPE (struct ev_loop *)</dt> |
1715 | <dt>ev::TYPE::~TYPE</dt> |
1909 | <dt>ev::TYPE::~TYPE</dt> |
1716 | <dd> |
1910 | <dd> |
1717 | <p>The constructor takes a pointer to an object and a method pointer to |
1911 | <p>The constructor (optionally) takes an event loop to associate the watcher |
1718 | the event handler callback to call in this class. The constructor calls |
1912 | with. If it is omitted, it will use <code>EV_DEFAULT</code>.</p> |
1719 | <code>ev_init</code> for you, which means you have to call the <code>set</code> method |
1913 | <p>The constructor calls <code>ev_init</code> for you, which means you have to call the |
1720 | before starting it. If you do not specify a loop then the constructor |
1914 | <code>set</code> method before starting it.</p> |
1721 | automatically associates the default loop with this watcher.</p> |
1915 | <p>It will not set a callback, however: You have to call the templated <code>set</code> |
|
|
1916 | method to set a callback before you can start the watcher.</p> |
|
|
1917 | <p>(The reason why you have to use a method is a limitation in C++ which does |
|
|
1918 | not allow explicit template arguments for constructors).</p> |
1722 | <p>The destructor automatically stops the watcher if it is active.</p> |
1919 | <p>The destructor automatically stops the watcher if it is active.</p> |
|
|
1920 | </dd> |
|
|
1921 | <dt>w->set<class, &class::method> (object *)</dt> |
|
|
1922 | <dd> |
|
|
1923 | <p>This method sets the callback method to call. The method has to have a |
|
|
1924 | signature of <code>void (*)(ev_TYPE &, int)</code>, it receives the watcher as |
|
|
1925 | first argument and the <code>revents</code> as second. The object must be given as |
|
|
1926 | parameter and is stored in the <code>data</code> member of the watcher.</p> |
|
|
1927 | <p>This method synthesizes efficient thunking code to call your method from |
|
|
1928 | the C callback that libev requires. If your compiler can inline your |
|
|
1929 | callback (i.e. it is visible to it at the place of the <code>set</code> call and |
|
|
1930 | your compiler is good :), then the method will be fully inlined into the |
|
|
1931 | thunking function, making it as fast as a direct C callback.</p> |
|
|
1932 | <p>Example: simple class declaration and watcher initialisation</p> |
|
|
1933 | <pre> struct myclass |
|
|
1934 | { |
|
|
1935 | void io_cb (ev::io &w, int revents) { } |
|
|
1936 | } |
|
|
1937 | |
|
|
1938 | myclass obj; |
|
|
1939 | ev::io iow; |
|
|
1940 | iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
1941 | |
|
|
1942 | </pre> |
|
|
1943 | </dd> |
|
|
1944 | <dt>w->set<function> (void *data = 0)</dt> |
|
|
1945 | <dd> |
|
|
1946 | <p>Also sets a callback, but uses a static method or plain function as |
|
|
1947 | callback. The optional <code>data</code> argument will be stored in the watcher's |
|
|
1948 | <code>data</code> member and is free for you to use.</p> |
|
|
1949 | <p>The prototype of the <code>function</code> must be <code>void (*)(ev::TYPE &w, int)</code>.</p> |
|
|
1950 | <p>See the method-<code>set</code> above for more details.</p> |
|
|
1951 | <p>Example:</p> |
|
|
1952 | <pre> static void io_cb (ev::io &w, int revents) { } |
|
|
1953 | iow.set <io_cb> (); |
|
|
1954 | |
|
|
1955 | </pre> |
1723 | </dd> |
1956 | </dd> |
1724 | <dt>w->set (struct ev_loop *)</dt> |
1957 | <dt>w->set (struct ev_loop *)</dt> |
1725 | <dd> |
1958 | <dd> |
1726 | <p>Associates a different <code>struct ev_loop</code> with this watcher. You can only |
1959 | <p>Associates a different <code>struct ev_loop</code> with this watcher. You can only |
1727 | do this when the watcher is inactive (and not pending either).</p> |
1960 | do this when the watcher is inactive (and not pending either).</p> |
1728 | </dd> |
1961 | </dd> |
1729 | <dt>w->set ([args])</dt> |
1962 | <dt>w->set ([args])</dt> |
1730 | <dd> |
1963 | <dd> |
1731 | <p>Basically the same as <code>ev_TYPE_set</code>, with the same args. Must be |
1964 | <p>Basically the same as <code>ev_TYPE_set</code>, with the same args. Must be |
1732 | called at least once. Unlike the C counterpart, an active watcher gets |
1965 | called at least once. Unlike the C counterpart, an active watcher gets |
1733 | automatically stopped and restarted.</p> |
1966 | automatically stopped and restarted when reconfiguring it with this |
|
|
1967 | method.</p> |
1734 | </dd> |
1968 | </dd> |
1735 | <dt>w->start ()</dt> |
1969 | <dt>w->start ()</dt> |
1736 | <dd> |
1970 | <dd> |
1737 | <p>Starts the watcher. Note that there is no <code>loop</code> argument as the |
1971 | <p>Starts the watcher. Note that there is no <code>loop</code> argument, as the |
1738 | constructor already takes the loop.</p> |
1972 | constructor already stores the event loop.</p> |
1739 | </dd> |
1973 | </dd> |
1740 | <dt>w->stop ()</dt> |
1974 | <dt>w->stop ()</dt> |
1741 | <dd> |
1975 | <dd> |
1742 | <p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p> |
1976 | <p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p> |
1743 | </dd> |
1977 | </dd> |
… | |
… | |
1767 | |
2001 | |
1768 | myclass (); |
2002 | myclass (); |
1769 | } |
2003 | } |
1770 | |
2004 | |
1771 | myclass::myclass (int fd) |
2005 | myclass::myclass (int fd) |
1772 | : io (this, &myclass::io_cb), |
|
|
1773 | idle (this, &myclass::idle_cb) |
|
|
1774 | { |
2006 | { |
|
|
2007 | io .set <myclass, &myclass::io_cb > (this); |
|
|
2008 | idle.set <myclass, &myclass::idle_cb> (this); |
|
|
2009 | |
1775 | io.start (fd, ev::READ); |
2010 | io.start (fd, ev::READ); |
1776 | } |
2011 | } |
1777 | |
2012 | |
1778 | |
2013 | |
1779 | |
2014 | |
… | |
… | |
1782 | |
2017 | |
1783 | </div> |
2018 | </div> |
1784 | <h1 id="MACRO_MAGIC">MACRO MAGIC</h1> |
2019 | <h1 id="MACRO_MAGIC">MACRO MAGIC</h1> |
1785 | <div id="MACRO_MAGIC_CONTENT"> |
2020 | <div id="MACRO_MAGIC_CONTENT"> |
1786 | <p>Libev can be compiled with a variety of options, the most fundemantal is |
2021 | <p>Libev can be compiled with a variety of options, the most fundemantal is |
1787 | <code>EV_MULTIPLICITY</code>. This option determines wether (most) functions and |
2022 | <code>EV_MULTIPLICITY</code>. This option determines whether (most) functions and |
1788 | callbacks have an initial <code>struct ev_loop *</code> argument.</p> |
2023 | callbacks have an initial <code>struct ev_loop *</code> argument.</p> |
1789 | <p>To make it easier to write programs that cope with either variant, the |
2024 | <p>To make it easier to write programs that cope with either variant, the |
1790 | following macros are defined:</p> |
2025 | following macros are defined:</p> |
1791 | <dl> |
2026 | <dl> |
1792 | <dt><code>EV_A</code>, <code>EV_A_</code></dt> |
2027 | <dt><code>EV_A</code>, <code>EV_A_</code></dt> |
… | |
… | |
1821 | <dd> |
2056 | <dd> |
1822 | <p>Similar to the other two macros, this gives you the value of the default |
2057 | <p>Similar to the other two macros, this gives you the value of the default |
1823 | loop, if multiple loops are supported ("ev loop default").</p> |
2058 | loop, if multiple loops are supported ("ev loop default").</p> |
1824 | </dd> |
2059 | </dd> |
1825 | </dl> |
2060 | </dl> |
1826 | <p>Example: Declare and initialise a check watcher, working regardless of |
2061 | <p>Example: Declare and initialise a check watcher, utilising the above |
1827 | wether multiple loops are supported or not.</p> |
2062 | macros so it will work regardless of whether multiple loops are supported |
|
|
2063 | or not.</p> |
1828 | <pre> static void |
2064 | <pre> static void |
1829 | check_cb (EV_P_ ev_timer *w, int revents) |
2065 | check_cb (EV_P_ ev_timer *w, int revents) |
1830 | { |
2066 | { |
1831 | ev_check_stop (EV_A_ w); |
2067 | ev_check_stop (EV_A_ w); |
1832 | } |
2068 | } |
1833 | |
2069 | |
1834 | ev_check check; |
2070 | ev_check check; |
1835 | ev_check_init (&check, check_cb); |
2071 | ev_check_init (&check, check_cb); |
1836 | ev_check_start (EV_DEFAULT_ &check); |
2072 | ev_check_start (EV_DEFAULT_ &check); |
1837 | ev_loop (EV_DEFAULT_ 0); |
2073 | ev_loop (EV_DEFAULT_ 0); |
1838 | |
|
|
1839 | |
|
|
1840 | |
|
|
1841 | |
2074 | |
1842 | </pre> |
2075 | </pre> |
1843 | |
2076 | |
1844 | </div> |
2077 | </div> |
1845 | <h1 id="EMBEDDING">EMBEDDING</h1> |
2078 | <h1 id="EMBEDDING">EMBEDDING</h1> |
… | |
… | |
1887 | ev_vars.h |
2120 | ev_vars.h |
1888 | ev_wrap.h |
2121 | ev_wrap.h |
1889 | |
2122 | |
1890 | ev_win32.c required on win32 platforms only |
2123 | ev_win32.c required on win32 platforms only |
1891 | |
2124 | |
1892 | ev_select.c only when select backend is enabled (which is by default) |
2125 | ev_select.c only when select backend is enabled (which is enabled by default) |
1893 | ev_poll.c only when poll backend is enabled (disabled by default) |
2126 | ev_poll.c only when poll backend is enabled (disabled by default) |
1894 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
2127 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1895 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
2128 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1896 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
2129 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
1897 | |
2130 | |
… | |
… | |
2062 | will have the <code>struct ev_loop *</code> as first argument, and you can create |
2295 | will have the <code>struct ev_loop *</code> as first argument, and you can create |
2063 | additional independent event loops. Otherwise there will be no support |
2296 | additional independent event loops. Otherwise there will be no support |
2064 | for multiple event loops and there is no first event loop pointer |
2297 | for multiple event loops and there is no first event loop pointer |
2065 | argument. Instead, all functions act on the single default loop.</p> |
2298 | argument. Instead, all functions act on the single default loop.</p> |
2066 | </dd> |
2299 | </dd> |
|
|
2300 | <dt>EV_MINPRI</dt> |
|
|
2301 | <dt>EV_MAXPRI</dt> |
|
|
2302 | <dd> |
|
|
2303 | <p>The range of allowed priorities. <code>EV_MINPRI</code> must be smaller or equal to |
|
|
2304 | <code>EV_MAXPRI</code>, but otherwise there are no non-obvious limitations. You can |
|
|
2305 | provide for more priorities by overriding those symbols (usually defined |
|
|
2306 | to be <code>-2</code> and <code>2</code>, respectively).</p> |
|
|
2307 | <p>When doing priority-based operations, libev usually has to linearly search |
|
|
2308 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
2309 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
|
|
2310 | fine.</p> |
|
|
2311 | <p>If your embedding app does not need any priorities, defining these both to |
|
|
2312 | <code>0</code> will save some memory and cpu.</p> |
|
|
2313 | </dd> |
2067 | <dt>EV_PERIODIC_ENABLE</dt> |
2314 | <dt>EV_PERIODIC_ENABLE</dt> |
2068 | <dd> |
2315 | <dd> |
2069 | <p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If |
2316 | <p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If |
|
|
2317 | defined to be <code>0</code>, then they are not. Disabling them saves a few kB of |
|
|
2318 | code.</p> |
|
|
2319 | </dd> |
|
|
2320 | <dt>EV_IDLE_ENABLE</dt> |
|
|
2321 | <dd> |
|
|
2322 | <p>If undefined or defined to be <code>1</code>, then idle watchers are supported. If |
2070 | defined to be <code>0</code>, then they are not. Disabling them saves a few kB of |
2323 | defined to be <code>0</code>, then they are not. Disabling them saves a few kB of |
2071 | code.</p> |
2324 | code.</p> |
2072 | </dd> |
2325 | </dd> |
2073 | <dt>EV_EMBED_ENABLE</dt> |
2326 | <dt>EV_EMBED_ENABLE</dt> |
2074 | <dd> |
2327 | <dd> |
… | |
… | |
2139 | the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public |
2392 | the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public |
2140 | interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file |
2393 | interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file |
2141 | will be compiled. It is pretty complex because it provides its own header |
2394 | will be compiled. It is pretty complex because it provides its own header |
2142 | file.</p> |
2395 | file.</p> |
2143 | <p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file |
2396 | <p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file |
2144 | that everybody includes and which overrides some autoconf choices:</p> |
2397 | that everybody includes and which overrides some configure choices:</p> |
|
|
2398 | <pre> #define EV_MINIMAL 1 |
2145 | <pre> #define EV_USE_POLL 0 |
2399 | #define EV_USE_POLL 0 |
2146 | #define EV_MULTIPLICITY 0 |
2400 | #define EV_MULTIPLICITY 0 |
2147 | #define EV_PERIODICS 0 |
2401 | #define EV_PERIODIC_ENABLE 0 |
|
|
2402 | #define EV_STAT_ENABLE 0 |
|
|
2403 | #define EV_FORK_ENABLE 0 |
2148 | #define EV_CONFIG_H <config.h> |
2404 | #define EV_CONFIG_H <config.h> |
|
|
2405 | #define EV_MINPRI 0 |
|
|
2406 | #define EV_MAXPRI 0 |
2149 | |
2407 | |
2150 | #include "ev++.h" |
2408 | #include "ev++.h" |
2151 | |
2409 | |
2152 | </pre> |
2410 | </pre> |
2153 | <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p> |
2411 | <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p> |
… | |
… | |
2163 | <h1 id="COMPLEXITIES">COMPLEXITIES</h1> |
2421 | <h1 id="COMPLEXITIES">COMPLEXITIES</h1> |
2164 | <div id="COMPLEXITIES_CONTENT"> |
2422 | <div id="COMPLEXITIES_CONTENT"> |
2165 | <p>In this section the complexities of (many of) the algorithms used inside |
2423 | <p>In this section the complexities of (many of) the algorithms used inside |
2166 | libev will be explained. For complexity discussions about backends see the |
2424 | libev will be explained. For complexity discussions about backends see the |
2167 | documentation for <code>ev_default_init</code>.</p> |
2425 | documentation for <code>ev_default_init</code>.</p> |
|
|
2426 | <p>All of the following are about amortised time: If an array needs to be |
|
|
2427 | extended, libev needs to realloc and move the whole array, but this |
|
|
2428 | happens asymptotically never with higher number of elements, so O(1) might |
|
|
2429 | mean it might do a lengthy realloc operation in rare cases, but on average |
|
|
2430 | it is much faster and asymptotically approaches constant time.</p> |
2168 | <p> |
2431 | <p> |
2169 | <dl> |
2432 | <dl> |
2170 | <dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt> |
2433 | <dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt> |
|
|
2434 | <dd> |
|
|
2435 | <p>This means that, when you have a watcher that triggers in one hour and |
|
|
2436 | there are 100 watchers that would trigger before that then inserting will |
|
|
2437 | have to skip those 100 watchers.</p> |
|
|
2438 | </dd> |
2171 | <dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt> |
2439 | <dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt> |
|
|
2440 | <dd> |
|
|
2441 | <p>That means that for changing a timer costs less than removing/adding them |
|
|
2442 | as only the relative motion in the event queue has to be paid for.</p> |
|
|
2443 | </dd> |
2172 | <dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt> |
2444 | <dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt> |
|
|
2445 | <dd> |
|
|
2446 | <p>These just add the watcher into an array or at the head of a list. |
2173 | <dt>Stopping check/prepare/idle watchers: O(1)</dt> |
2447 | =item Stopping check/prepare/idle watchers: O(1)</p> |
|
|
2448 | </dd> |
2174 | <dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))</dt> |
2449 | <dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))</dt> |
|
|
2450 | <dd> |
|
|
2451 | <p>These watchers are stored in lists then need to be walked to find the |
|
|
2452 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
2453 | have many watchers waiting for the same fd or signal).</p> |
|
|
2454 | </dd> |
2175 | <dt>Finding the next timer per loop iteration: O(1)</dt> |
2455 | <dt>Finding the next timer per loop iteration: O(1)</dt> |
2176 | <dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt> |
2456 | <dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt> |
|
|
2457 | <dd> |
|
|
2458 | <p>A change means an I/O watcher gets started or stopped, which requires |
|
|
2459 | libev to recalculate its status (and possibly tell the kernel).</p> |
|
|
2460 | </dd> |
2177 | <dt>Activating one watcher: O(1)</dt> |
2461 | <dt>Activating one watcher: O(1)</dt> |
|
|
2462 | <dt>Priority handling: O(number_of_priorities)</dt> |
|
|
2463 | <dd> |
|
|
2464 | <p>Priorities are implemented by allocating some space for each |
|
|
2465 | priority. When doing priority-based operations, libev usually has to |
|
|
2466 | linearly search all the priorities.</p> |
|
|
2467 | </dd> |
2178 | </dl> |
2468 | </dl> |
2179 | </p> |
2469 | </p> |
2180 | |
2470 | |
2181 | |
2471 | |
2182 | |
2472 | |