… | |
… | |
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="Sat Nov 24 17:31:33 2007" /> |
9 | <meta name="created" content="Tue Nov 27 09:11:42 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 --> |
… | |
… | |
31 | <ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</a></li> |
31 | <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 | <li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</a></li> |
32 | <li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</a></li> |
33 | <li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</a></li> |
33 | <li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</a></li> |
34 | <li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</a></li> |
34 | <li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</a></li> |
35 | <li><a href="#code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</a></li> |
35 | <li><a href="#code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</a></li> |
|
|
36 | <li><a href="#code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</a></li> |
36 | <li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</a></li> |
37 | <li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</a></li> |
37 | <li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</a></li> |
38 | <li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</a></li> |
38 | <li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</a></li> |
39 | <li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</a></li> |
39 | </ul> |
40 | </ul> |
40 | </li> |
41 | </li> |
… | |
… | |
50 | </li> |
51 | </li> |
51 | <li><a href="#PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</a></li> |
52 | <li><a href="#PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</a></li> |
52 | <li><a href="#EXAMPLES">EXAMPLES</a></li> |
53 | <li><a href="#EXAMPLES">EXAMPLES</a></li> |
53 | </ul> |
54 | </ul> |
54 | </li> |
55 | </li> |
|
|
56 | <li><a href="#COMPLEXITIES">COMPLEXITIES</a></li> |
55 | <li><a href="#AUTHOR">AUTHOR</a> |
57 | <li><a href="#AUTHOR">AUTHOR</a> |
56 | </li> |
58 | </li> |
57 | </ul><hr /> |
59 | </ul><hr /> |
58 | <!-- INDEX END --> |
60 | <!-- INDEX END --> |
59 | |
61 | |
… | |
… | |
585 | </dd> |
587 | </dd> |
586 | <dt><code>EV_CHILD</code></dt> |
588 | <dt><code>EV_CHILD</code></dt> |
587 | <dd> |
589 | <dd> |
588 | <p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p> |
590 | <p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p> |
589 | </dd> |
591 | </dd> |
|
|
592 | <dt><code>EV_STAT</code></dt> |
|
|
593 | <dd> |
|
|
594 | <p>The path specified in the <code>ev_stat</code> watcher changed its attributes somehow.</p> |
|
|
595 | </dd> |
590 | <dt><code>EV_IDLE</code></dt> |
596 | <dt><code>EV_IDLE</code></dt> |
591 | <dd> |
597 | <dd> |
592 | <p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p> |
598 | <p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p> |
593 | </dd> |
599 | </dd> |
594 | <dt><code>EV_PREPARE</code></dt> |
600 | <dt><code>EV_PREPARE</code></dt> |
… | |
… | |
731 | |
737 | |
732 | </div> |
738 | </div> |
733 | <h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p> |
739 | <h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p> |
734 | <div id="WATCHER_TYPES_CONTENT"> |
740 | <div id="WATCHER_TYPES_CONTENT"> |
735 | <p>This section describes each watcher in detail, but will not repeat |
741 | <p>This section describes each watcher in detail, but will not repeat |
736 | information given in the last section.</p> |
742 | information given in the last section. Any initialisation/set macros, |
|
|
743 | functions and members specific to the watcher type are explained.</p> |
|
|
744 | <p>Members are additionally marked with either <i>[read-only]</i>, meaning that, |
|
|
745 | while the watcher is active, you can look at the member and expect some |
|
|
746 | sensible content, but you must not modify it (you can modify it while the |
|
|
747 | watcher is stopped to your hearts content), or <i>[read-write]</i>, which |
|
|
748 | means you can expect it to have some sensible content while the watcher |
|
|
749 | is active, but you can also modify it. Modifying it may not do something |
|
|
750 | sensible or take immediate effect (or do anything at all), but libev will |
|
|
751 | not crash or malfunction in any way.</p> |
737 | |
752 | |
738 | |
753 | |
739 | |
754 | |
740 | |
755 | |
741 | |
756 | |
… | |
… | |
780 | <dd> |
795 | <dd> |
781 | <p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to |
796 | <p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to |
782 | rceeive events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or |
797 | rceeive events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or |
783 | <code>EV_READ | EV_WRITE</code> to receive the given events.</p> |
798 | <code>EV_READ | EV_WRITE</code> to receive the given events.</p> |
784 | </dd> |
799 | </dd> |
|
|
800 | <dt>int fd [read-only]</dt> |
|
|
801 | <dd> |
|
|
802 | <p>The file descriptor being watched.</p> |
|
|
803 | </dd> |
|
|
804 | <dt>int events [read-only]</dt> |
|
|
805 | <dd> |
|
|
806 | <p>The events being watched.</p> |
|
|
807 | </dd> |
785 | </dl> |
808 | </dl> |
786 | <p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well |
809 | <p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well |
787 | readable, but only once. Since it is likely line-buffered, you could |
810 | readable, but only once. Since it is likely line-buffered, you could |
788 | attempt to read a whole line in the callback:</p> |
811 | attempt to read a whole line in the callback:</p> |
789 | <pre> static void |
812 | <pre> static void |
… | |
… | |
846 | repeating. The exact semantics are:</p> |
869 | repeating. The exact semantics are:</p> |
847 | <p>If the timer is started but nonrepeating, stop it.</p> |
870 | <p>If the timer is started but nonrepeating, stop it.</p> |
848 | <p>If the timer is repeating, either start it if necessary (with the repeat |
871 | <p>If the timer is repeating, either start it if necessary (with the repeat |
849 | value), or reset the running timer to the repeat value.</p> |
872 | value), or reset the running timer to the repeat value.</p> |
850 | <p>This sounds a bit complicated, but here is a useful and typical |
873 | <p>This sounds a bit complicated, but here is a useful and typical |
851 | example: Imagine you have a tcp connection and you want a so-called idle |
874 | example: Imagine you have a tcp connection and you want a so-called |
852 | timeout, that is, you want to be called when there have been, say, 60 |
875 | idle timeout, that is, you want to be called when there have been, |
853 | seconds of inactivity on the socket. The easiest way to do this is to |
876 | say, 60 seconds of inactivity on the socket. The easiest way to do |
854 | configure an <code>ev_timer</code> with after=repeat=60 and calling ev_timer_again each |
877 | this is to configure an <code>ev_timer</code> with <code>after</code>=<code>repeat</code>=<code>60</code> and calling |
855 | time you successfully read or write some data. If you go into an idle |
878 | <code>ev_timer_again</code> each time you successfully read or write some data. If |
856 | state where you do not expect data to travel on the socket, you can stop |
879 | you go into an idle state where you do not expect data to travel on the |
857 | the timer, and again will automatically restart it if need be.</p> |
880 | socket, you can stop the timer, and again will automatically restart it if |
|
|
881 | need be.</p> |
|
|
882 | <p>You can also ignore the <code>after</code> value and <code>ev_timer_start</code> altogether |
|
|
883 | and only ever use the <code>repeat</code> value:</p> |
|
|
884 | <pre> ev_timer_init (timer, callback, 0., 5.); |
|
|
885 | ev_timer_again (loop, timer); |
|
|
886 | ... |
|
|
887 | timer->again = 17.; |
|
|
888 | ev_timer_again (loop, timer); |
|
|
889 | ... |
|
|
890 | timer->again = 10.; |
|
|
891 | ev_timer_again (loop, timer); |
|
|
892 | |
|
|
893 | </pre> |
|
|
894 | <p>This is more efficient then stopping/starting the timer eahc time you want |
|
|
895 | to modify its timeout value.</p> |
|
|
896 | </dd> |
|
|
897 | <dt>ev_tstamp repeat [read-write]</dt> |
|
|
898 | <dd> |
|
|
899 | <p>The current <code>repeat</code> value. Will be used each time the watcher times out |
|
|
900 | or <code>ev_timer_again</code> is called and determines the next timeout (if any), |
|
|
901 | which is also when any modifications are taken into account.</p> |
858 | </dd> |
902 | </dd> |
859 | </dl> |
903 | </dl> |
860 | <p>Example: create a timer that fires after 60 seconds.</p> |
904 | <p>Example: create a timer that fires after 60 seconds.</p> |
861 | <pre> static void |
905 | <pre> static void |
862 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
906 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
… | |
… | |
980 | <p>Simply stops and restarts the periodic watcher again. This is only useful |
1024 | <p>Simply stops and restarts the periodic watcher again. This is only useful |
981 | when you changed some parameters or the reschedule callback would return |
1025 | when you changed some parameters or the reschedule callback would return |
982 | a different time than the last time it was called (e.g. in a crond like |
1026 | a different time than the last time it was called (e.g. in a crond like |
983 | program when the crontabs have changed).</p> |
1027 | program when the crontabs have changed).</p> |
984 | </dd> |
1028 | </dd> |
|
|
1029 | <dt>ev_tstamp interval [read-write]</dt> |
|
|
1030 | <dd> |
|
|
1031 | <p>The current interval value. Can be modified any time, but changes only |
|
|
1032 | take effect when the periodic timer fires or <code>ev_periodic_again</code> is being |
|
|
1033 | called.</p> |
|
|
1034 | </dd> |
|
|
1035 | <dt>ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]</dt> |
|
|
1036 | <dd> |
|
|
1037 | <p>The current reschedule callback, or <code>0</code>, if this functionality is |
|
|
1038 | switched off. Can be changed any time, but changes only take effect when |
|
|
1039 | the periodic timer fires or <code>ev_periodic_again</code> is being called.</p> |
|
|
1040 | </dd> |
985 | </dl> |
1041 | </dl> |
986 | <p>Example: call a callback every hour, or, more precisely, whenever the |
1042 | <p>Example: call a callback every hour, or, more precisely, whenever the |
987 | system clock is divisible by 3600. The callback invocation times have |
1043 | system clock is divisible by 3600. The callback invocation times have |
988 | potentially a lot of jittering, but good long-term stability.</p> |
1044 | potentially a lot of jittering, but good long-term stability.</p> |
989 | <pre> static void |
1045 | <pre> static void |
… | |
… | |
1038 | <dt>ev_signal_set (ev_signal *, int signum)</dt> |
1094 | <dt>ev_signal_set (ev_signal *, int signum)</dt> |
1039 | <dd> |
1095 | <dd> |
1040 | <p>Configures the watcher to trigger on the given signal number (usually one |
1096 | <p>Configures the watcher to trigger on the given signal number (usually one |
1041 | of the <code>SIGxxx</code> constants).</p> |
1097 | of the <code>SIGxxx</code> constants).</p> |
1042 | </dd> |
1098 | </dd> |
|
|
1099 | <dt>int signum [read-only]</dt> |
|
|
1100 | <dd> |
|
|
1101 | <p>The signal the watcher watches out for.</p> |
|
|
1102 | </dd> |
1043 | </dl> |
1103 | </dl> |
1044 | |
1104 | |
1045 | |
1105 | |
1046 | |
1106 | |
1047 | |
1107 | |
… | |
… | |
1060 | at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see |
1120 | at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see |
1061 | the status word (use the macros from <code>sys/wait.h</code> and see your systems |
1121 | the status word (use the macros from <code>sys/wait.h</code> and see your systems |
1062 | <code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the |
1122 | <code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the |
1063 | process causing the status change.</p> |
1123 | process causing the status change.</p> |
1064 | </dd> |
1124 | </dd> |
|
|
1125 | <dt>int pid [read-only]</dt> |
|
|
1126 | <dd> |
|
|
1127 | <p>The process id this watcher watches out for, or <code>0</code>, meaning any process id.</p> |
|
|
1128 | </dd> |
|
|
1129 | <dt>int rpid [read-write]</dt> |
|
|
1130 | <dd> |
|
|
1131 | <p>The process id that detected a status change.</p> |
|
|
1132 | </dd> |
|
|
1133 | <dt>int rstatus [read-write]</dt> |
|
|
1134 | <dd> |
|
|
1135 | <p>The process exit/trace status caused by <code>rpid</code> (see your systems |
|
|
1136 | <code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p> |
|
|
1137 | </dd> |
1065 | </dl> |
1138 | </dl> |
1066 | <p>Example: try to exit cleanly on SIGINT and SIGTERM.</p> |
1139 | <p>Example: try to exit cleanly on SIGINT and SIGTERM.</p> |
1067 | <pre> static void |
1140 | <pre> static void |
1068 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1141 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1069 | { |
1142 | { |
… | |
… | |
1071 | } |
1144 | } |
1072 | |
1145 | |
1073 | struct ev_signal signal_watcher; |
1146 | struct ev_signal signal_watcher; |
1074 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1147 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1075 | ev_signal_start (loop, &sigint_cb); |
1148 | ev_signal_start (loop, &sigint_cb); |
|
|
1149 | |
|
|
1150 | |
|
|
1151 | |
|
|
1152 | |
|
|
1153 | </pre> |
|
|
1154 | |
|
|
1155 | </div> |
|
|
1156 | <h2 id="code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</h2> |
|
|
1157 | <div id="code_ev_stat_code_did_the_file_attri-2"> |
|
|
1158 | <p>This watches a filesystem path for attribute changes. That is, it calls |
|
|
1159 | <code>stat</code> regularly (or when the OS says it changed) and sees if it changed |
|
|
1160 | compared to the last time, invoking the callback if it did.</p> |
|
|
1161 | <p>The path does not need to exist: changing from "path exists" to "path does |
|
|
1162 | not exist" is a status change like any other. The condition "path does |
|
|
1163 | not exist" is signified by the <code>st_nlink</code> field being zero (which is |
|
|
1164 | otherwise always forced to be at least one) and all the other fields of |
|
|
1165 | the stat buffer having unspecified contents.</p> |
|
|
1166 | <p>Since there is no standard to do this, the portable implementation simply |
|
|
1167 | calls <code>stat (2)</code> regulalry on the path to see if it changed somehow. You |
|
|
1168 | can specify a recommended polling interval for this case. If you specify |
|
|
1169 | a polling interval of <code>0</code> (highly recommended!) then a <i>suitable, |
|
|
1170 | unspecified default</i> value will be used (which you can expect to be around |
|
|
1171 | five seconds, although this might change dynamically). Libev will also |
|
|
1172 | impose a minimum interval which is currently around <code>0.1</code>, but thats |
|
|
1173 | usually overkill.</p> |
|
|
1174 | <p>This watcher type is not meant for massive numbers of stat watchers, |
|
|
1175 | as even with OS-supported change notifications, this can be |
|
|
1176 | resource-intensive.</p> |
|
|
1177 | <p>At the time of this writing, no specific OS backends are implemented, but |
|
|
1178 | if demand increases, at least a kqueue and inotify backend will be added.</p> |
|
|
1179 | <dl> |
|
|
1180 | <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt> |
|
|
1181 | <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt> |
|
|
1182 | <dd> |
|
|
1183 | <p>Configures the watcher to wait for status changes of the given |
|
|
1184 | <code>path</code>. The <code>interval</code> is a hint on how quickly a change is expected to |
|
|
1185 | be detected and should normally be specified as <code>0</code> to let libev choose |
|
|
1186 | a suitable value. The memory pointed to by <code>path</code> must point to the same |
|
|
1187 | path for as long as the watcher is active.</p> |
|
|
1188 | <p>The callback will be receive <code>EV_STAT</code> when a change was detected, |
|
|
1189 | relative to the attributes at the time the watcher was started (or the |
|
|
1190 | last change was detected).</p> |
|
|
1191 | </dd> |
|
|
1192 | <dt>ev_stat_stat (ev_stat *)</dt> |
|
|
1193 | <dd> |
|
|
1194 | <p>Updates the stat buffer immediately with new values. If you change the |
|
|
1195 | watched path in your callback, you could call this fucntion to avoid |
|
|
1196 | detecting this change (while introducing a race condition). Can also be |
|
|
1197 | useful simply to find out the new values.</p> |
|
|
1198 | </dd> |
|
|
1199 | <dt>ev_statdata attr [read-only]</dt> |
|
|
1200 | <dd> |
|
|
1201 | <p>The most-recently detected attributes of the file. Although the type is of |
|
|
1202 | <code>ev_statdata</code>, this is usually the (or one of the) <code>struct stat</code> types |
|
|
1203 | suitable for your system. If the <code>st_nlink</code> member is <code>0</code>, then there |
|
|
1204 | was some error while <code>stat</code>ing the file.</p> |
|
|
1205 | </dd> |
|
|
1206 | <dt>ev_statdata prev [read-only]</dt> |
|
|
1207 | <dd> |
|
|
1208 | <p>The previous attributes of the file. The callback gets invoked whenever |
|
|
1209 | <code>prev</code> != <code>attr</code>.</p> |
|
|
1210 | </dd> |
|
|
1211 | <dt>ev_tstamp interval [read-only]</dt> |
|
|
1212 | <dd> |
|
|
1213 | <p>The specified interval.</p> |
|
|
1214 | </dd> |
|
|
1215 | <dt>const char *path [read-only]</dt> |
|
|
1216 | <dd> |
|
|
1217 | <p>The filesystem path that is being watched.</p> |
|
|
1218 | </dd> |
|
|
1219 | </dl> |
|
|
1220 | <p>Example: Watch <code>/etc/passwd</code> for attribute changes.</p> |
|
|
1221 | <pre> static void |
|
|
1222 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
|
|
1223 | { |
|
|
1224 | /* /etc/passwd changed in some way */ |
|
|
1225 | if (w->attr.st_nlink) |
|
|
1226 | { |
|
|
1227 | printf ("passwd current size %ld\n", (long)w->attr.st_size); |
|
|
1228 | printf ("passwd current atime %ld\n", (long)w->attr.st_mtime); |
|
|
1229 | printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime); |
|
|
1230 | } |
|
|
1231 | else |
|
|
1232 | /* you shalt not abuse printf for puts */ |
|
|
1233 | puts ("wow, /etc/passwd is not there, expect problems. " |
|
|
1234 | "if this is windows, they already arrived\n"); |
|
|
1235 | } |
|
|
1236 | |
|
|
1237 | ... |
|
|
1238 | ev_stat passwd; |
|
|
1239 | |
|
|
1240 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
|
|
1241 | ev_stat_start (loop, &passwd); |
1076 | |
1242 | |
1077 | |
1243 | |
1078 | |
1244 | |
1079 | |
1245 | |
1080 | </pre> |
1246 | </pre> |
… | |
… | |
1126 | <h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</h2> |
1292 | <h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</h2> |
1127 | <div id="code_ev_prepare_code_and_code_ev_che-2"> |
1293 | <div id="code_ev_prepare_code_and_code_ev_che-2"> |
1128 | <p>Prepare and check watchers are usually (but not always) used in tandem: |
1294 | <p>Prepare and check watchers are usually (but not always) used in tandem: |
1129 | prepare watchers get invoked before the process blocks and check watchers |
1295 | prepare watchers get invoked before the process blocks and check watchers |
1130 | afterwards.</p> |
1296 | afterwards.</p> |
|
|
1297 | <p>You <i>must not</i> call <code>ev_loop</code> or similar functions that enter |
|
|
1298 | the current event loop from either <code>ev_prepare</code> or <code>ev_check</code> |
|
|
1299 | watchers. Other loops than the current one are fine, however. The |
|
|
1300 | rationale behind this is that you do not need to check for recursion in |
|
|
1301 | those watchers, i.e. the sequence will always be <code>ev_prepare</code>, blocking, |
|
|
1302 | <code>ev_check</code> so if you have one watcher of each kind they will always be |
|
|
1303 | called in pairs bracketing the blocking call.</p> |
1131 | <p>Their main purpose is to integrate other event mechanisms into libev and |
1304 | <p>Their main purpose is to integrate other event mechanisms into libev and |
1132 | their use is somewhat advanced. This could be used, for example, to track |
1305 | their use is somewhat advanced. This could be used, for example, to track |
1133 | variable changes, implement your own watchers, integrate net-snmp or a |
1306 | variable changes, implement your own watchers, integrate net-snmp or a |
1134 | coroutine library and lots more.</p> |
1307 | coroutine library and lots more. They are also occasionally useful if |
|
|
1308 | you cache some data and want to flush it before blocking (for example, |
|
|
1309 | in X programs you might want to do an <code>XFlush ()</code> in an <code>ev_prepare</code> |
|
|
1310 | watcher).</p> |
1135 | <p>This is done by examining in each prepare call which file descriptors need |
1311 | <p>This is done by examining in each prepare call which file descriptors need |
1136 | to be watched by the other library, registering <code>ev_io</code> watchers for |
1312 | to be watched by the other library, registering <code>ev_io</code> watchers for |
1137 | them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries |
1313 | them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries |
1138 | provide just this functionality). Then, in the check watcher you check for |
1314 | provide just this functionality). Then, in the check watcher you check for |
1139 | any events that occured (by checking the pending status of all watchers |
1315 | any events that occured (by checking the pending status of all watchers |
… | |
… | |
1155 | <p>Initialises and configures the prepare or check watcher - they have no |
1331 | <p>Initialises and configures the prepare or check watcher - they have no |
1156 | parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code> |
1332 | parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code> |
1157 | macros, but using them is utterly, utterly and completely pointless.</p> |
1333 | macros, but using them is utterly, utterly and completely pointless.</p> |
1158 | </dd> |
1334 | </dd> |
1159 | </dl> |
1335 | </dl> |
1160 | <p>Example: *TODO*.</p> |
1336 | <p>Example: To include a library such as adns, you would add IO watchers |
|
|
1337 | and a timeout watcher in a prepare handler, as required by libadns, and |
|
|
1338 | in a check watcher, destroy them and call into libadns. What follows is |
|
|
1339 | pseudo-code only of course:</p> |
|
|
1340 | <pre> static ev_io iow [nfd]; |
|
|
1341 | static ev_timer tw; |
1161 | |
1342 | |
|
|
1343 | static void |
|
|
1344 | io_cb (ev_loop *loop, ev_io *w, int revents) |
|
|
1345 | { |
|
|
1346 | // set the relevant poll flags |
|
|
1347 | // could also call adns_processreadable etc. here |
|
|
1348 | struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1349 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1350 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1351 | } |
1162 | |
1352 | |
|
|
1353 | // create io watchers for each fd and a timer before blocking |
|
|
1354 | static void |
|
|
1355 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
|
|
1356 | { |
|
|
1357 | int timeout = 3600000;truct pollfd fds [nfd]; |
|
|
1358 | // actual code will need to loop here and realloc etc. |
|
|
1359 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1163 | |
1360 | |
|
|
1361 | /* the callback is illegal, but won't be called as we stop during check */ |
|
|
1362 | ev_timer_init (&tw, 0, timeout * 1e-3); |
|
|
1363 | ev_timer_start (loop, &tw); |
1164 | |
1364 | |
|
|
1365 | // create on ev_io per pollfd |
|
|
1366 | for (int i = 0; i < nfd; ++i) |
|
|
1367 | { |
|
|
1368 | ev_io_init (iow + i, io_cb, fds [i].fd, |
|
|
1369 | ((fds [i].events & POLLIN ? EV_READ : 0) |
|
|
1370 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
|
|
1371 | |
|
|
1372 | fds [i].revents = 0; |
|
|
1373 | iow [i].data = fds + i; |
|
|
1374 | ev_io_start (loop, iow + i); |
|
|
1375 | } |
|
|
1376 | } |
|
|
1377 | |
|
|
1378 | // stop all watchers after blocking |
|
|
1379 | static void |
|
|
1380 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
|
|
1381 | { |
|
|
1382 | ev_timer_stop (loop, &tw); |
|
|
1383 | |
|
|
1384 | for (int i = 0; i < nfd; ++i) |
|
|
1385 | ev_io_stop (loop, iow + i); |
|
|
1386 | |
|
|
1387 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1388 | } |
|
|
1389 | |
|
|
1390 | |
|
|
1391 | |
|
|
1392 | |
|
|
1393 | </pre> |
1165 | |
1394 | |
1166 | </div> |
1395 | </div> |
1167 | <h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</h2> |
1396 | <h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</h2> |
1168 | <div id="code_ev_embed_code_when_one_backend_-2"> |
1397 | <div id="code_ev_embed_code_when_one_backend_-2"> |
1169 | <p>This is a rather advanced watcher type that lets you embed one event loop |
1398 | <p>This is a rather advanced watcher type that lets you embed one event loop |
… | |
… | |
1239 | <dt>ev_embed_sweep (loop, ev_embed *)</dt> |
1468 | <dt>ev_embed_sweep (loop, ev_embed *)</dt> |
1240 | <dd> |
1469 | <dd> |
1241 | <p>Make a single, non-blocking sweep over the embedded loop. This works |
1470 | <p>Make a single, non-blocking sweep over the embedded loop. This works |
1242 | similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most |
1471 | similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most |
1243 | apropriate way for embedded loops.</p> |
1472 | apropriate way for embedded loops.</p> |
|
|
1473 | </dd> |
|
|
1474 | <dt>struct ev_loop *loop [read-only]</dt> |
|
|
1475 | <dd> |
|
|
1476 | <p>The embedded event loop.</p> |
1244 | </dd> |
1477 | </dd> |
1245 | </dl> |
1478 | </dl> |
1246 | |
1479 | |
1247 | |
1480 | |
1248 | |
1481 | |
… | |
… | |
1469 | ev_vars.h |
1702 | ev_vars.h |
1470 | ev_wrap.h |
1703 | ev_wrap.h |
1471 | |
1704 | |
1472 | ev_win32.c required on win32 platforms only |
1705 | ev_win32.c required on win32 platforms only |
1473 | |
1706 | |
1474 | ev_select.c only when select backend is enabled (which is is by default) |
1707 | ev_select.c only when select backend is enabled (which is by default) |
1475 | ev_poll.c only when poll backend is enabled (disabled by default) |
1708 | ev_poll.c only when poll backend is enabled (disabled by default) |
1476 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1709 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1477 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1710 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1478 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
1711 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
1479 | |
1712 | |
1480 | </pre> |
1713 | </pre> |
1481 | <p><cite>ev.c</cite> includes the backend files directly when enabled, so you only need |
1714 | <p><cite>ev.c</cite> includes the backend files directly when enabled, so you only need |
1482 | to compile a single file.</p> |
1715 | to compile this single file.</p> |
1483 | |
1716 | |
1484 | </div> |
1717 | </div> |
1485 | <h3 id="LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</h3> |
1718 | <h3 id="LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</h3> |
1486 | <div id="LIBEVENT_COMPATIBILITY_API_CONTENT"> |
1719 | <div id="LIBEVENT_COMPATIBILITY_API_CONTENT"> |
1487 | <p>To include the libevent compatibility API, also include:</p> |
1720 | <p>To include the libevent compatibility API, also include:</p> |
… | |
… | |
1502 | </div> |
1735 | </div> |
1503 | <h3 id="AUTOCONF_SUPPORT">AUTOCONF SUPPORT</h3> |
1736 | <h3 id="AUTOCONF_SUPPORT">AUTOCONF SUPPORT</h3> |
1504 | <div id="AUTOCONF_SUPPORT_CONTENT"> |
1737 | <div id="AUTOCONF_SUPPORT_CONTENT"> |
1505 | <p>Instead of using <code>EV_STANDALONE=1</code> and providing your config in |
1738 | <p>Instead of using <code>EV_STANDALONE=1</code> and providing your config in |
1506 | whatever way you want, you can also <code>m4_include([libev.m4])</code> in your |
1739 | whatever way you want, you can also <code>m4_include([libev.m4])</code> in your |
1507 | <cite>configure.ac</cite> and leave <code>EV_STANDALONE</code> off. <cite>ev.c</cite> will then include |
1740 | <cite>configure.ac</cite> and leave <code>EV_STANDALONE</code> undefined. <cite>ev.c</cite> will then |
1508 | <cite>config.h</cite> and configure itself accordingly.</p> |
1741 | include <cite>config.h</cite> and configure itself accordingly.</p> |
1509 | <p>For this of course you need the m4 file:</p> |
1742 | <p>For this of course you need the m4 file:</p> |
1510 | <pre> libev.m4 |
1743 | <pre> libev.m4 |
1511 | |
1744 | |
1512 | </pre> |
1745 | </pre> |
1513 | |
1746 | |
… | |
… | |
1638 | will have the <code>struct ev_loop *</code> as first argument, and you can create |
1871 | will have the <code>struct ev_loop *</code> as first argument, and you can create |
1639 | additional independent event loops. Otherwise there will be no support |
1872 | additional independent event loops. Otherwise there will be no support |
1640 | for multiple event loops and there is no first event loop pointer |
1873 | for multiple event loops and there is no first event loop pointer |
1641 | argument. Instead, all functions act on the single default loop.</p> |
1874 | argument. Instead, all functions act on the single default loop.</p> |
1642 | </dd> |
1875 | </dd> |
1643 | <dt>EV_PERIODICS</dt> |
1876 | <dt>EV_PERIODIC_ENABLE</dt> |
1644 | <dd> |
1877 | <dd> |
1645 | <p>If undefined or defined to be <code>1</code>, then periodic timers are supported, |
1878 | <p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If |
1646 | otherwise not. This saves a few kb of code.</p> |
1879 | defined to be <code>0</code>, then they are not. Disabling them saves a few kB of |
|
|
1880 | code.</p> |
|
|
1881 | </dd> |
|
|
1882 | <dt>EV_EMBED_ENABLE</dt> |
|
|
1883 | <dd> |
|
|
1884 | <p>If undefined or defined to be <code>1</code>, then embed watchers are supported. If |
|
|
1885 | defined to be <code>0</code>, then they are not.</p> |
|
|
1886 | </dd> |
|
|
1887 | <dt>EV_STAT_ENABLE</dt> |
|
|
1888 | <dd> |
|
|
1889 | <p>If undefined or defined to be <code>1</code>, then stat watchers are supported. If |
|
|
1890 | defined to be <code>0</code>, then they are not.</p> |
|
|
1891 | </dd> |
|
|
1892 | <dt>EV_MINIMAL</dt> |
|
|
1893 | <dd> |
|
|
1894 | <p>If you need to shave off some kilobytes of code at the expense of some |
|
|
1895 | speed, define this symbol to <code>1</code>. Currently only used for gcc to override |
|
|
1896 | some inlining decisions, saves roughly 30% codesize of amd64.</p> |
1647 | </dd> |
1897 | </dd> |
1648 | <dt>EV_COMMON</dt> |
1898 | <dt>EV_COMMON</dt> |
1649 | <dd> |
1899 | <dd> |
1650 | <p>By default, all watchers have a <code>void *data</code> member. By redefining |
1900 | <p>By default, all watchers have a <code>void *data</code> member. By redefining |
1651 | this macro to a something else you can include more and other types of |
1901 | this macro to a something else you can include more and other types of |
… | |
… | |
1656 | SV *self; /* contains this struct */ \ |
1906 | SV *self; /* contains this struct */ \ |
1657 | SV *cb_sv, *fh /* note no trailing ";" */ |
1907 | SV *cb_sv, *fh /* note no trailing ";" */ |
1658 | |
1908 | |
1659 | </pre> |
1909 | </pre> |
1660 | </dd> |
1910 | </dd> |
1661 | <dt>EV_CB_DECLARE(type)</dt> |
1911 | <dt>EV_CB_DECLARE (type)</dt> |
1662 | <dt>EV_CB_INVOKE(watcher,revents)</dt> |
1912 | <dt>EV_CB_INVOKE (watcher, revents)</dt> |
1663 | <dt>ev_set_cb(ev,cb)</dt> |
1913 | <dt>ev_set_cb (ev, cb)</dt> |
1664 | <dd> |
1914 | <dd> |
1665 | <p>Can be used to change the callback member declaration in each watcher, |
1915 | <p>Can be used to change the callback member declaration in each watcher, |
1666 | and the way callbacks are invoked and set. Must expand to a struct member |
1916 | and the way callbacks are invoked and set. Must expand to a struct member |
1667 | definition and a statement, respectively. See the <cite>ev.v</cite> header file for |
1917 | definition and a statement, respectively. See the <cite>ev.v</cite> header file for |
1668 | their default definitions. One possible use for overriding these is to |
1918 | their default definitions. One possible use for overriding these is to |
1669 | avoid the ev_loop pointer as first argument in all cases, or to use method |
1919 | avoid the <code>struct ev_loop *</code> as first argument in all cases, or to use |
1670 | calls instead of plain function calls in C++.</p> |
1920 | method calls instead of plain function calls in C++.</p> |
1671 | |
1921 | |
1672 | </div> |
1922 | </div> |
1673 | <h2 id="EXAMPLES">EXAMPLES</h2> |
1923 | <h2 id="EXAMPLES">EXAMPLES</h2> |
1674 | <div id="EXAMPLES_CONTENT"> |
1924 | <div id="EXAMPLES_CONTENT"> |
1675 | <p>For a real-world example of a program the includes libev |
1925 | <p>For a real-world example of a program the includes libev |
… | |
… | |
1691 | </pre> |
1941 | </pre> |
1692 | <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p> |
1942 | <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p> |
1693 | <pre> #include "ev_cpp.h" |
1943 | <pre> #include "ev_cpp.h" |
1694 | #include "ev.c" |
1944 | #include "ev.c" |
1695 | |
1945 | |
|
|
1946 | |
|
|
1947 | |
|
|
1948 | |
1696 | </pre> |
1949 | </pre> |
|
|
1950 | |
|
|
1951 | </div> |
|
|
1952 | <h1 id="COMPLEXITIES">COMPLEXITIES</h1><p><a href="#TOP" class="toplink">Top</a></p> |
|
|
1953 | <div id="COMPLEXITIES_CONTENT"> |
|
|
1954 | <p>In this section the complexities of (many of) the algorithms used inside |
|
|
1955 | libev will be explained. For complexity discussions about backends see the |
|
|
1956 | documentation for <code>ev_default_init</code>.</p> |
|
|
1957 | <p> |
|
|
1958 | <dl> |
|
|
1959 | <dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt> |
|
|
1960 | <dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt> |
|
|
1961 | <dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt> |
|
|
1962 | <dt>Stopping check/prepare/idle watchers: O(1)</dt> |
|
|
1963 | <dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))</dt> |
|
|
1964 | <dt>Finding the next timer per loop iteration: O(1)</dt> |
|
|
1965 | <dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt> |
|
|
1966 | <dt>Activating one watcher: O(1)</dt> |
|
|
1967 | </dl> |
|
|
1968 | </p> |
|
|
1969 | |
|
|
1970 | |
|
|
1971 | |
|
|
1972 | |
1697 | |
1973 | |
1698 | </div> |
1974 | </div> |
1699 | <h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1975 | <h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1700 | <div id="AUTHOR_CONTENT"> |
1976 | <div id="AUTHOR_CONTENT"> |
1701 | <p>Marc Lehmann <libev@schmorp.de>.</p> |
1977 | <p>Marc Lehmann <libev@schmorp.de>.</p> |