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4 | <head> |
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5 | <title>libev</title> |
5 | <title>libev</title> |
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14 | <!-- INDEX START --> |
14 | <!-- INDEX START --> |
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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> |
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33 | <ul><li><a href="#The_special_problem_of_disappearing_">The special problem of disappearing file descriptors</a></li> |
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34 | </ul> |
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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> |
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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"> |
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127 | <p>The newest version of this document is also available as a html-formatted |
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128 | web page you might find easier to navigate when reading it for the first |
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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 |
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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> |
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198 | <p>These version numbers refer to the ABI version of the library, not the |
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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", |
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526 | 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 |
527 | external event in conjunction with something not expressible using other |
535 | external event in conjunction with something not expressible using other |
528 | 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 |
529 | usually a better approach for this kind of thing.</p> |
537 | usually a better approach for this kind of thing.</p> |
530 | <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> |
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539 | <pre> - Before the first iteration, call any pending watchers. |
531 | <pre> * If there are no active watchers (reference count is zero), return. |
540 | * If there are no active watchers (reference count is zero), return. |
532 | - Queue prepare watchers and then call all outstanding watchers. |
541 | - Queue all prepare watchers and then call all outstanding watchers. |
533 | - If we have been forked, recreate the kernel state. |
542 | - If we have been forked, recreate the kernel state. |
534 | - Update the kernel state with all outstanding changes. |
543 | - Update the kernel state with all outstanding changes. |
535 | - Update the "event loop time". |
544 | - Update the "event loop time". |
536 | - Calculate for how long to block. |
545 | - Calculate for how long to block. |
537 | - Block the process, waiting for any events. |
546 | - Block the process, waiting for any events. |
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766 | <dt>bool ev_is_pending (ev_TYPE *watcher)</dt> |
775 | <dt>bool ev_is_pending (ev_TYPE *watcher)</dt> |
767 | <dd> |
776 | <dd> |
768 | <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 |
769 | 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 |
770 | 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 |
771 | <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 |
772 | 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> |
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782 | it).</p> |
773 | </dd> |
783 | </dd> |
774 | <dt>callback ev_cb (ev_TYPE *watcher)</dt> |
784 | <dt>callback ev_cb (ev_TYPE *watcher)</dt> |
775 | <dd> |
785 | <dd> |
776 | <p>Returns the callback currently set on the watcher.</p> |
786 | <p>Returns the callback currently set on the watcher.</p> |
777 | </dd> |
787 | </dd> |
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792 | invocation after new events have been received. This is useful, for |
802 | invocation after new events have been received. This is useful, for |
793 | example, to reduce latency after idling, or more often, to bind two |
803 | example, to reduce latency after idling, or more often, to bind two |
794 | watchers on the same event and make sure one is called first.</p> |
804 | watchers on the same event and make sure one is called first.</p> |
795 | <p>If you need to suppress invocation when higher priority events are pending |
805 | <p>If you need to suppress invocation when higher priority events are pending |
796 | you need to look at <code>ev_idle</code> watchers, which provide this functionality.</p> |
806 | you need to look at <code>ev_idle</code> watchers, which provide this functionality.</p> |
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807 | <p>You <i>must not</i> change the priority of a watcher as long as it is active or |
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808 | pending.</p> |
797 | <p>The default priority used by watchers when no priority has been set is |
809 | <p>The default priority used by watchers when no priority has been set is |
798 | always <code>0</code>, which is supposed to not be too high and not be too low :).</p> |
810 | always <code>0</code>, which is supposed to not be too high and not be too low :).</p> |
799 | <p>Setting a priority outside the range of <code>EV_MINPRI</code> to <code>EV_MAXPRI</code> is |
811 | <p>Setting a priority outside the range of <code>EV_MINPRI</code> to <code>EV_MAXPRI</code> is |
800 | fine, as long as you do not mind that the priority value you query might |
812 | fine, as long as you do not mind that the priority value you query might |
801 | or might not have been adjusted to be within valid range.</p> |
813 | or might not have been adjusted to be within valid range.</p> |
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814 | </dd> |
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815 | <dt>ev_invoke (loop, ev_TYPE *watcher, int revents)</dt> |
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816 | <dd> |
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817 | <p>Invoke the <code>watcher</code> with the given <code>loop</code> and <code>revents</code>. Neither |
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818 | <code>loop</code> nor <code>revents</code> need to be valid as long as the watcher callback |
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819 | can deal with that fact.</p> |
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820 | </dd> |
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821 | <dt>int ev_clear_pending (loop, ev_TYPE *watcher)</dt> |
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822 | <dd> |
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823 | <p>If the watcher is pending, this function returns clears its pending status |
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824 | and returns its <code>revents</code> bitset (as if its callback was invoked). If the |
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825 | watcher isn't pending it does nothing and returns <code>0</code>.</p> |
802 | </dd> |
826 | </dd> |
803 | </dl> |
827 | </dl> |
804 | |
828 | |
805 | |
829 | |
806 | |
830 | |
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920 | <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 |
921 | 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 |
922 | whether 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 |
923 | 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 |
924 | its own, so its quite safe to use).</p> |
948 | its own, so its quite safe to use).</p> |
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949 | |
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950 | </div> |
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951 | <h3 id="The_special_problem_of_disappearing_">The special problem of disappearing file descriptors</h3> |
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952 | <div id="The_special_problem_of_disappearing_-2"> |
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953 | <p>Some backends (e.g kqueue, epoll) need to be told about closing a file |
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954 | descriptor (either by calling <code>close</code> explicitly or by any other means, |
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955 | such as <code>dup</code>). The reason is that you register interest in some file |
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956 | descriptor, but when it goes away, the operating system will silently drop |
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957 | this interest. If another file descriptor with the same number then is |
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958 | registered with libev, there is no efficient way to see that this is, in |
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959 | fact, a different file descriptor.</p> |
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960 | <p>To avoid having to explicitly tell libev about such cases, libev follows |
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961 | the following policy: Each time <code>ev_io_set</code> is being called, libev |
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962 | will assume that this is potentially a new file descriptor, otherwise |
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963 | it is assumed that the file descriptor stays the same. That means that |
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964 | you <i>have</i> to call <code>ev_io_set</code> (or <code>ev_io_init</code>) when you change the |
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965 | descriptor even if the file descriptor number itself did not change.</p> |
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966 | <p>This is how one would do it normally anyway, the important point is that |
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967 | the libev application should not optimise around libev but should leave |
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968 | optimisations to libev.</p> |
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969 | |
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970 | |
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971 | |
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972 | |
925 | <dl> |
973 | <dl> |
926 | <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> |
927 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
975 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
928 | <dd> |
976 | <dd> |
929 | <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 |
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1078 | 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 |
1079 | 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 |
1080 | 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 () |
1081 | + 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 |
1082 | 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 |
1083 | roughly 10 seconds later and of course not if you reset your system time |
1131 | roughly 10 seconds later).</p> |
1084 | again).</p> |
|
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1085 | <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 |
1086 | triggering an event on eahc midnight, local time.</p> |
1133 | triggering an event on each midnight, local time or other, complicated, |
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1134 | rules.</p> |
1087 | <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 |
1088 | 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 |
1089 | 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> |
1090 | <dl> |
1138 | <dl> |
1091 | <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> |
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1093 | <dd> |
1141 | <dd> |
1094 | <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 |
1095 | operation, and we will explain them from simplest to complex:</p> |
1143 | operation, and we will explain them from simplest to complex:</p> |
1096 | <p> |
1144 | <p> |
1097 | <dl> |
1145 | <dl> |
1098 | <dt>* absolute timer (interval = reschedule_cb = 0)</dt> |
1146 | <dt>* absolute timer (at = time, interval = reschedule_cb = 0)</dt> |
1099 | <dd> |
1147 | <dd> |
1100 | <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 |
1101 | <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, |
1102 | 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 |
1103 | system time reaches or surpasses this time.</p> |
1151 | system time reaches or surpasses this time.</p> |
1104 | </dd> |
1152 | </dd> |
1105 | <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> |
1106 | <dd> |
1154 | <dd> |
1107 | <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 |
1108 | <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) |
1109 | of any time jumps.</p> |
1157 | and then repeat, regardless of any time jumps.</p> |
1110 | <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 |
1111 | time:</p> |
1159 | time:</p> |
1112 | <pre> ev_periodic_set (&periodic, 0., 3600., 0); |
1160 | <pre> ev_periodic_set (&periodic, 0., 3600., 0); |
1113 | |
1161 | |
1114 | </pre> |
1162 | </pre> |
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1117 | 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 |
1118 | by 3600.</p> |
1166 | by 3600.</p> |
1119 | <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 |
1120 | <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 |
1121 | 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 |
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|
1171 | <code>ev_now ()</code> (the current time), but there is no range requirement for |
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1172 | this value.</p> |
1122 | </dd> |
1173 | </dd> |
1123 | <dt>* manual reschedule mode (reschedule_cb = callback)</dt> |
1174 | <dt>* manual reschedule mode (at and interval ignored, reschedule_cb = callback)</dt> |
1124 | <dd> |
1175 | <dd> |
1125 | <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 |
1126 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1177 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1127 | 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 |
1128 | current time as second argument.</p> |
1179 | current time as second argument.</p> |
1129 | <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, |
1130 | 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, |
1131 | 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 |
1132 | starting a prepare watcher).</p> |
1183 | starting an <code>ev_prepare</code> watcher, which is legal).</p> |
1133 | <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, |
1134 | ev_tstamp now)</code>, e.g.:</p> |
1185 | ev_tstamp now)</code>, e.g.:</p> |
1135 | <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) |
1136 | { |
1187 | { |
1137 | return now + 60.; |
1188 | return now + 60.; |
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1157 | <dd> |
1208 | <dd> |
1158 | <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 |
1159 | when you changed some parameters or the reschedule callback would return |
1210 | when you changed some parameters or the reschedule callback would return |
1160 | 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 |
1161 | 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> |
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|
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> |
1162 | </dd> |
1220 | </dd> |
1163 | <dt>ev_tstamp interval [read-write]</dt> |
1221 | <dt>ev_tstamp interval [read-write]</dt> |
1164 | <dd> |
1222 | <dd> |
1165 | <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 |
1166 | 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 |
… | |
… | |
1465 | 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 |
1466 | 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 |
1467 | 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 |
1468 | loop from blocking if lower-priority coroutines are active, thus mapping |
1526 | loop from blocking if lower-priority coroutines are active, thus mapping |
1469 | 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> |
1470 | <dl> |
1537 | <dl> |
1471 | <dt>ev_prepare_init (ev_prepare *, callback)</dt> |
1538 | <dt>ev_prepare_init (ev_prepare *, callback)</dt> |
1472 | <dt>ev_check_init (ev_check *, callback)</dt> |
1539 | <dt>ev_check_init (ev_check *, callback)</dt> |
1473 | <dd> |
1540 | <dd> |
1474 | <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 |
1475 | 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> |
1476 | macros, but using them is utterly, utterly and completely pointless.</p> |
1543 | macros, but using them is utterly, utterly and completely pointless.</p> |
1477 | </dd> |
1544 | </dd> |
1478 | </dl> |
1545 | </dl> |
1479 | <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 |
1480 | 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, |
1481 | 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 |
1482 | 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> |
1483 | <pre> static ev_io iow [nfd]; |
1557 | <pre> static ev_io iow [nfd]; |
1484 | static ev_timer tw; |
1558 | static ev_timer tw; |
1485 | |
1559 | |
1486 | static void |
1560 | static void |
1487 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1561 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1488 | { |
1562 | { |
1489 | // set the relevant poll flags |
|
|
1490 | // could also call adns_processreadable etc. here |
|
|
1491 | struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1492 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1493 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1494 | } |
1563 | } |
1495 | |
1564 | |
1496 | // create io watchers for each fd and a timer before blocking |
1565 | // create io watchers for each fd and a timer before blocking |
1497 | static void |
1566 | static void |
1498 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1567 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
… | |
… | |
1504 | |
1573 | |
1505 | /* 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 */ |
1506 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1575 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1507 | ev_timer_start (loop, &tw); |
1576 | ev_timer_start (loop, &tw); |
1508 | |
1577 | |
1509 | // create on ev_io per pollfd |
1578 | // create one ev_io per pollfd |
1510 | for (int i = 0; i < nfd; ++i) |
1579 | for (int i = 0; i < nfd; ++i) |
1511 | { |
1580 | { |
1512 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1581 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1513 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1582 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1514 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1583 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1515 | |
1584 | |
1516 | fds [i].revents = 0; |
1585 | fds [i].revents = 0; |
1517 | iow [i].data = fds + i; |
|
|
1518 | ev_io_start (loop, iow + i); |
1586 | ev_io_start (loop, iow + i); |
1519 | } |
1587 | } |
1520 | } |
1588 | } |
1521 | |
1589 | |
1522 | // stop all watchers after blocking |
1590 | // stop all watchers after blocking |
… | |
… | |
1524 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1592 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1525 | { |
1593 | { |
1526 | ev_timer_stop (loop, &tw); |
1594 | ev_timer_stop (loop, &tw); |
1527 | |
1595 | |
1528 | 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 |
1529 | ev_io_stop (loop, iow + i); |
1606 | ev_io_stop (loop, iow + i); |
|
|
1607 | } |
1530 | |
1608 | |
1531 | 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; |
1532 | } |
1668 | } |
1533 | |
1669 | |
1534 | |
1670 | |
1535 | |
1671 | |
1536 | |
1672 | |
… | |
… | |
1733 | 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> |
1734 | <p>To use it,</p> |
1870 | <p>To use it,</p> |
1735 | <pre> #include <ev++.h> |
1871 | <pre> #include <ev++.h> |
1736 | |
1872 | |
1737 | </pre> |
1873 | </pre> |
1738 | <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 |
1739 | 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 |
1740 | 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 |
1741 | <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> |
1742 | <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> |
1743 | <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> |
1744 | <dl> |
1888 | <dl> |
1745 | <dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt> |
1889 | <dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt> |
1746 | <dd> |
1890 | <dd> |
1747 | <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. |
… | |
… | |
1758 | 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 |
1759 | defines by many implementations.</p> |
1903 | defines by many implementations.</p> |
1760 | <p>All of those classes have these methods:</p> |
1904 | <p>All of those classes have these methods:</p> |
1761 | <p> |
1905 | <p> |
1762 | <dl> |
1906 | <dl> |
1763 | <dt>ev::TYPE::TYPE (object *, object::method *)</dt> |
1907 | <dt>ev::TYPE::TYPE ()</dt> |
1764 | <dt>ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)</dt> |
1908 | <dt>ev::TYPE::TYPE (struct ev_loop *)</dt> |
1765 | <dt>ev::TYPE::~TYPE</dt> |
1909 | <dt>ev::TYPE::~TYPE</dt> |
1766 | <dd> |
1910 | <dd> |
1767 | <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 |
1768 | 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> |
1769 | <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 |
1770 | before starting it. If you do not specify a loop then the constructor |
1914 | <code>set</code> method before starting it.</p> |
1771 | 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> |
1772 | <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> |
1773 | </dd> |
1956 | </dd> |
1774 | <dt>w->set (struct ev_loop *)</dt> |
1957 | <dt>w->set (struct ev_loop *)</dt> |
1775 | <dd> |
1958 | <dd> |
1776 | <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 |
1777 | 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> |
1778 | </dd> |
1961 | </dd> |
1779 | <dt>w->set ([args])</dt> |
1962 | <dt>w->set ([args])</dt> |
1780 | <dd> |
1963 | <dd> |
1781 | <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 |
1782 | 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 |
1783 | automatically stopped and restarted.</p> |
1966 | automatically stopped and restarted when reconfiguring it with this |
|
|
1967 | method.</p> |
1784 | </dd> |
1968 | </dd> |
1785 | <dt>w->start ()</dt> |
1969 | <dt>w->start ()</dt> |
1786 | <dd> |
1970 | <dd> |
1787 | <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 |
1788 | constructor already takes the loop.</p> |
1972 | constructor already stores the event loop.</p> |
1789 | </dd> |
1973 | </dd> |
1790 | <dt>w->stop ()</dt> |
1974 | <dt>w->stop ()</dt> |
1791 | <dd> |
1975 | <dd> |
1792 | <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> |
1793 | </dd> |
1977 | </dd> |
… | |
… | |
1817 | |
2001 | |
1818 | myclass (); |
2002 | myclass (); |
1819 | } |
2003 | } |
1820 | |
2004 | |
1821 | myclass::myclass (int fd) |
2005 | myclass::myclass (int fd) |
1822 | : io (this, &myclass::io_cb), |
|
|
1823 | idle (this, &myclass::idle_cb) |
|
|
1824 | { |
2006 | { |
|
|
2007 | io .set <myclass, &myclass::io_cb > (this); |
|
|
2008 | idle.set <myclass, &myclass::idle_cb> (this); |
|
|
2009 | |
1825 | io.start (fd, ev::READ); |
2010 | io.start (fd, ev::READ); |
1826 | } |
2011 | } |
1827 | |
2012 | |
1828 | |
2013 | |
1829 | |
2014 | |
… | |
… | |
2109 | <p>If undefined or defined to <code>1</code>, then all event-loop-specific functions |
2294 | <p>If undefined or defined to <code>1</code>, then all event-loop-specific functions |
2110 | 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 |
2111 | additional independent event loops. Otherwise there will be no support |
2296 | additional independent event loops. Otherwise there will be no support |
2112 | 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 |
2113 | argument. Instead, all functions act on the single default loop.</p> |
2298 | argument. Instead, all functions act on the single default loop.</p> |
|
|
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> |
2114 | </dd> |
2313 | </dd> |
2115 | <dt>EV_PERIODIC_ENABLE</dt> |
2314 | <dt>EV_PERIODIC_ENABLE</dt> |
2116 | <dd> |
2315 | <dd> |
2117 | <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 |
2118 | defined to be <code>0</code>, then they are not. Disabling them saves a few kB of |
2317 | defined to be <code>0</code>, then they are not. Disabling them saves a few kB of |
… | |
… | |
2222 | <h1 id="COMPLEXITIES">COMPLEXITIES</h1> |
2421 | <h1 id="COMPLEXITIES">COMPLEXITIES</h1> |
2223 | <div id="COMPLEXITIES_CONTENT"> |
2422 | <div id="COMPLEXITIES_CONTENT"> |
2224 | <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 |
2225 | libev will be explained. For complexity discussions about backends see the |
2424 | libev will be explained. For complexity discussions about backends see the |
2226 | 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> |
2227 | <p> |
2431 | <p> |
2228 | <dl> |
2432 | <dl> |
2229 | <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> |
2230 | <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> |
2231 | <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. |
2232 | <dt>Stopping check/prepare/idle watchers: O(1)</dt> |
2447 | =item Stopping check/prepare/idle watchers: O(1)</p> |
|
|
2448 | </dd> |
2233 | <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> |
2234 | <dt>Finding the next timer per loop iteration: O(1)</dt> |
2455 | <dt>Finding the next timer per loop iteration: O(1)</dt> |
2235 | <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> |
2236 | <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> |
2237 | </dl> |
2468 | </dl> |
2238 | </p> |
2469 | </p> |
2239 | |
2470 | |
2240 | |
2471 | |
2241 | |
2472 | |