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4 | <head> |
4 | <head> |
5 | <title>libev</title> |
5 | <title>libev</title> |
6 | <meta name="description" content="Pod documentation for libev" /> |
6 | <meta name="description" content="Pod documentation for libev" /> |
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13 | <div class="pod"> |
13 | <div class="pod"> |
14 | <!-- INDEX START --> |
14 | <!-- INDEX START --> |
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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 | <li><a href="#Watcher_Specific_Functions">Watcher-Specific Functions</a></li> |
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35 | </ul> |
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36 | </li> |
33 | <li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</a></li> |
37 | <li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</a> |
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38 | <ul><li><a href="#Watcher_Specific_Functions_and_Data_">Watcher-Specific Functions and Data Members</a></li> |
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39 | </ul> |
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40 | </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> |
41 | <li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</a> |
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42 | <ul><li><a href="#Watcher_Specific_Functions_and_Data_-3">Watcher-Specific Functions and Data Members</a></li> |
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43 | </ul> |
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44 | </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> |
45 | <li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</a> |
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46 | <ul><li><a href="#Watcher_Specific_Functions_and_Data_-4">Watcher-Specific Functions and Data Members</a></li> |
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47 | </ul> |
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48 | </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> |
49 | <li><a href="#code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</a> |
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50 | <ul><li><a href="#Watcher_Specific_Functions_and_Data_-5">Watcher-Specific Functions and Data Members</a></li> |
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51 | </ul> |
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52 | </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> |
53 | <li><a href="#code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</a> |
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54 | <ul><li><a href="#Watcher_Specific_Functions_and_Data_-6">Watcher-Specific Functions and Data Members</a></li> |
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55 | </ul> |
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56 | </li> |
38 | <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> |
57 | <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> |
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58 | <ul><li><a href="#Watcher_Specific_Functions_and_Data_-7">Watcher-Specific Functions and Data Members</a></li> |
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59 | </ul> |
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60 | </li> |
39 | <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> |
61 | <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> |
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62 | <ul><li><a href="#Watcher_Specific_Functions_and_Data_-8">Watcher-Specific Functions and Data Members</a></li> |
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63 | </ul> |
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64 | </li> |
40 | <li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</a></li> |
65 | <li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</a> |
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66 | <ul><li><a href="#Watcher_Specific_Functions_and_Data_-9">Watcher-Specific Functions and Data Members</a></li> |
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67 | </ul> |
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68 | </li> |
41 | <li><a href="#code_ev_fork_code_the_audacity_to_re"><code>ev_fork</code> - the audacity to resume the event loop after a fork</a></li> |
69 | <li><a href="#code_ev_fork_code_the_audacity_to_re"><code>ev_fork</code> - the audacity to resume the event loop after a fork</a></li> |
42 | </ul> |
70 | </ul> |
43 | </li> |
71 | </li> |
44 | <li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> |
72 | <li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> |
45 | <li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li> |
73 | <li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li> |
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119 | </pre> |
147 | </pre> |
120 | |
148 | |
121 | </div> |
149 | </div> |
122 | <h1 id="DESCRIPTION">DESCRIPTION</h1> |
150 | <h1 id="DESCRIPTION">DESCRIPTION</h1> |
123 | <div id="DESCRIPTION_CONTENT"> |
151 | <div id="DESCRIPTION_CONTENT"> |
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152 | <p>The newest version of this document is also available as a html-formatted |
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153 | web page you might find easier to navigate when reading it for the first |
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154 | 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 |
155 | <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 |
156 | file descriptor being readable or a timeout occuring), and it will manage |
126 | these event sources and provide your program with events.</p> |
157 | 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 |
158 | <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 |
159 | (or thread) by executing the <i>event loop</i> handler, and will then |
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182 | you actually want to know.</p> |
213 | you actually want to know.</p> |
183 | </dd> |
214 | </dd> |
184 | <dt>int ev_version_major ()</dt> |
215 | <dt>int ev_version_major ()</dt> |
185 | <dt>int ev_version_minor ()</dt> |
216 | <dt>int ev_version_minor ()</dt> |
186 | <dd> |
217 | <dd> |
187 | <p>You can find out the major and minor version numbers of the library |
218 | <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 |
219 | 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 |
220 | <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 |
221 | 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> |
222 | version of the library your program was compiled against.</p> |
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223 | <p>These version numbers refer to the ABI version of the library, not the |
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224 | release version.</p> |
192 | <p>Usually, it's a good idea to terminate if the major versions mismatch, |
225 | <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 |
226 | as this indicates an incompatible change. Minor versions are usually |
194 | compatible to older versions, so a larger minor version alone is usually |
227 | compatible to older versions, so a larger minor version alone is usually |
195 | not a problem.</p> |
228 | not a problem.</p> |
196 | <p>Example: Make sure we haven't accidentally been linked against the wrong |
229 | <p>Example: Make sure we haven't accidentally been linked against the wrong |
197 | version.</p> |
230 | version.</p> |
198 | <pre> assert (("libev version mismatch", |
231 | <pre> assert (("libev version mismatch", |
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526 | one iteration of the loop. This is useful if you are waiting for some |
559 | 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 |
560 | 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 |
561 | 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> |
562 | 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> |
563 | <p>Here are the gory details of what <code>ev_loop</code> does:</p> |
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564 | <pre> - Before the first iteration, call any pending watchers. |
531 | <pre> * If there are no active watchers (reference count is zero), return. |
565 | * If there are no active watchers (reference count is zero), return. |
532 | - Queue prepare watchers and then call all outstanding watchers. |
566 | - Queue all prepare watchers and then call all outstanding watchers. |
533 | - If we have been forked, recreate the kernel state. |
567 | - If we have been forked, recreate the kernel state. |
534 | - Update the kernel state with all outstanding changes. |
568 | - Update the kernel state with all outstanding changes. |
535 | - Update the "event loop time". |
569 | - Update the "event loop time". |
536 | - Calculate for how long to block. |
570 | - Calculate for how long to block. |
537 | - Block the process, waiting for any events. |
571 | - Block the process, waiting for any events. |
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766 | <dt>bool ev_is_pending (ev_TYPE *watcher)</dt> |
800 | <dt>bool ev_is_pending (ev_TYPE *watcher)</dt> |
767 | <dd> |
801 | <dd> |
768 | <p>Returns a true value iff the watcher is pending, (i.e. it has outstanding |
802 | <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 |
803 | 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 |
804 | 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 |
805 | <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> |
806 | make sure the watcher is available to libev (e.g. you cannot <code>free ()</code> |
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807 | it).</p> |
773 | </dd> |
808 | </dd> |
774 | <dt>callback ev_cb (ev_TYPE *watcher)</dt> |
809 | <dt>callback ev_cb (ev_TYPE *watcher)</dt> |
775 | <dd> |
810 | <dd> |
776 | <p>Returns the callback currently set on the watcher.</p> |
811 | <p>Returns the callback currently set on the watcher.</p> |
777 | </dd> |
812 | </dd> |
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792 | invocation after new events have been received. This is useful, for |
827 | invocation after new events have been received. This is useful, for |
793 | example, to reduce latency after idling, or more often, to bind two |
828 | 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> |
829 | 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 |
830 | <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> |
831 | you need to look at <code>ev_idle</code> watchers, which provide this functionality.</p> |
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832 | <p>You <i>must not</i> change the priority of a watcher as long as it is active or |
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833 | pending.</p> |
797 | <p>The default priority used by watchers when no priority has been set is |
834 | <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> |
835 | 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 |
836 | <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 |
837 | 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> |
838 | or might not have been adjusted to be within valid range.</p> |
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839 | </dd> |
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840 | <dt>ev_invoke (loop, ev_TYPE *watcher, int revents)</dt> |
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841 | <dd> |
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842 | <p>Invoke the <code>watcher</code> with the given <code>loop</code> and <code>revents</code>. Neither |
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843 | <code>loop</code> nor <code>revents</code> need to be valid as long as the watcher callback |
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844 | can deal with that fact.</p> |
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845 | </dd> |
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846 | <dt>int ev_clear_pending (loop, ev_TYPE *watcher)</dt> |
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847 | <dd> |
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848 | <p>If the watcher is pending, this function returns clears its pending status |
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849 | and returns its <code>revents</code> bitset (as if its callback was invoked). If the |
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850 | watcher isn't pending it does nothing and returns <code>0</code>.</p> |
802 | </dd> |
851 | </dd> |
803 | </dl> |
852 | </dl> |
804 | |
853 | |
805 | |
854 | |
806 | |
855 | |
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920 | <p>If you cannot run the fd in non-blocking mode (for example you should not |
969 | <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 |
970 | 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 |
971 | 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 |
972 | such as poll (fortunately in our Xlib example, Xlib already does this on |
924 | its own, so its quite safe to use).</p> |
973 | its own, so its quite safe to use).</p> |
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974 | |
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975 | </div> |
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976 | <h3 id="The_special_problem_of_disappearing_">The special problem of disappearing file descriptors</h3> |
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977 | <div id="The_special_problem_of_disappearing_-2"> |
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978 | <p>Some backends (e.g kqueue, epoll) need to be told about closing a file |
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979 | descriptor (either by calling <code>close</code> explicitly or by any other means, |
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980 | such as <code>dup</code>). The reason is that you register interest in some file |
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981 | descriptor, but when it goes away, the operating system will silently drop |
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982 | this interest. If another file descriptor with the same number then is |
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983 | registered with libev, there is no efficient way to see that this is, in |
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984 | fact, a different file descriptor.</p> |
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985 | <p>To avoid having to explicitly tell libev about such cases, libev follows |
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986 | the following policy: Each time <code>ev_io_set</code> is being called, libev |
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987 | will assume that this is potentially a new file descriptor, otherwise |
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988 | it is assumed that the file descriptor stays the same. That means that |
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989 | 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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990 | descriptor even if the file descriptor number itself did not change.</p> |
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991 | <p>This is how one would do it normally anyway, the important point is that |
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992 | the libev application should not optimise around libev but should leave |
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993 | optimisations to libev.</p> |
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994 | |
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995 | |
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996 | |
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997 | |
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998 | |
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999 | </div> |
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1000 | <h3 id="Watcher_Specific_Functions">Watcher-Specific Functions</h3> |
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1001 | <div id="Watcher_Specific_Functions_CONTENT"> |
925 | <dl> |
1002 | <dl> |
926 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
1003 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
927 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
1004 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
928 | <dd> |
1005 | <dd> |
929 | <p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to |
1006 | <p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to |
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980 | |
1057 | |
981 | </pre> |
1058 | </pre> |
982 | <p>The callback is guarenteed to be invoked only when its timeout has passed, |
1059 | <p>The callback is guarenteed to be invoked only when its timeout has passed, |
983 | but if multiple timers become ready during the same loop iteration then |
1060 | but if multiple timers become ready during the same loop iteration then |
984 | order of execution is undefined.</p> |
1061 | order of execution is undefined.</p> |
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1062 | |
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1063 | </div> |
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1064 | <h3 id="Watcher_Specific_Functions_and_Data_">Watcher-Specific Functions and Data Members</h3> |
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1065 | <div id="Watcher_Specific_Functions_and_Data_-2"> |
985 | <dl> |
1066 | <dl> |
986 | <dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt> |
1067 | <dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt> |
987 | <dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt> |
1068 | <dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt> |
988 | <dd> |
1069 | <dd> |
989 | <p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is |
1070 | <p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is |
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1078 | but on wallclock time (absolute time). You can tell a periodic watcher |
1159 | 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 |
1160 | 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 () |
1161 | 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 |
1162 | + 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 |
1163 | 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 |
1164 | 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 |
1165 | <p>They can also be used to implement vastly more complex timers, such as |
1086 | triggering an event on eahc midnight, local time.</p> |
1166 | triggering an event on each midnight, local time or other, complicated, |
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1167 | rules.</p> |
1087 | <p>As with timers, the callback is guarenteed to be invoked only when the |
1168 | <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 |
1169 | 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> |
1170 | during the same loop iteration then order of execution is undefined.</p> |
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1171 | |
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1172 | </div> |
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1173 | <h3 id="Watcher_Specific_Functions_and_Data_-3">Watcher-Specific Functions and Data Members</h3> |
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1174 | <div id="Watcher_Specific_Functions_and_Data_-2"> |
1090 | <dl> |
1175 | <dl> |
1091 | <dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt> |
1176 | <dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt> |
1092 | <dt>ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)</dt> |
1177 | <dt>ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)</dt> |
1093 | <dd> |
1178 | <dd> |
1094 | <p>Lots of arguments, lets sort it out... There are basically three modes of |
1179 | <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> |
1180 | operation, and we will explain them from simplest to complex:</p> |
1096 | <p> |
1181 | <p> |
1097 | <dl> |
1182 | <dl> |
1098 | <dt>* absolute timer (interval = reschedule_cb = 0)</dt> |
1183 | <dt>* absolute timer (at = time, interval = reschedule_cb = 0)</dt> |
1099 | <dd> |
1184 | <dd> |
1100 | <p>In this configuration the watcher triggers an event at the wallclock time |
1185 | <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, |
1186 | <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 |
1187 | 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> |
1188 | system time reaches or surpasses this time.</p> |
1104 | </dd> |
1189 | </dd> |
1105 | <dt>* non-repeating interval timer (interval > 0, reschedule_cb = 0)</dt> |
1190 | <dt>* non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)</dt> |
1106 | <dd> |
1191 | <dd> |
1107 | <p>In this mode the watcher will always be scheduled to time out at the next |
1192 | <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 |
1193 | <code>at + N * interval</code> time (for some integer N, which can also be negative) |
1109 | of any time jumps.</p> |
1194 | 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 |
1195 | <p>This can be used to create timers that do not drift with respect to system |
1111 | time:</p> |
1196 | time:</p> |
1112 | <pre> ev_periodic_set (&periodic, 0., 3600., 0); |
1197 | <pre> ev_periodic_set (&periodic, 0., 3600., 0); |
1113 | |
1198 | |
1114 | </pre> |
1199 | </pre> |
… | |
… | |
1117 | full hour (UTC), or more correctly, when the system time is evenly divisible |
1202 | full hour (UTC), or more correctly, when the system time is evenly divisible |
1118 | by 3600.</p> |
1203 | by 3600.</p> |
1119 | <p>Another way to think about it (for the mathematically inclined) is that |
1204 | <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 |
1205 | <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> |
1206 | time where <code>time = at (mod interval)</code>, regardless of any time jumps.</p> |
|
|
1207 | <p>For numerical stability it is preferable that the <code>at</code> value is near |
|
|
1208 | <code>ev_now ()</code> (the current time), but there is no range requirement for |
|
|
1209 | this value.</p> |
1122 | </dd> |
1210 | </dd> |
1123 | <dt>* manual reschedule mode (reschedule_cb = callback)</dt> |
1211 | <dt>* manual reschedule mode (at and interval ignored, reschedule_cb = callback)</dt> |
1124 | <dd> |
1212 | <dd> |
1125 | <p>In this mode the values for <code>interval</code> and <code>at</code> are both being |
1213 | <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 |
1214 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1127 | reschedule callback will be called with the watcher as first, and the |
1215 | reschedule callback will be called with the watcher as first, and the |
1128 | current time as second argument.</p> |
1216 | current time as second argument.</p> |
1129 | <p>NOTE: <i>This callback MUST NOT stop or destroy any periodic watcher, |
1217 | <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, |
1218 | 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 |
1219 | return <code>now + 1e30</code> (or so, fudge fudge) and stop it afterwards (e.g. by |
1132 | starting a prepare watcher).</p> |
1220 | 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, |
1221 | <p>Its prototype is <code>ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1134 | ev_tstamp now)</code>, e.g.:</p> |
1222 | ev_tstamp now)</code>, e.g.:</p> |
1135 | <pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1223 | <pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1136 | { |
1224 | { |
1137 | return now + 60.; |
1225 | return now + 60.; |
… | |
… | |
1157 | <dd> |
1245 | <dd> |
1158 | <p>Simply stops and restarts the periodic watcher again. This is only useful |
1246 | <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 |
1247 | 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 |
1248 | a different time than the last time it was called (e.g. in a crond like |
1161 | program when the crontabs have changed).</p> |
1249 | program when the crontabs have changed).</p> |
|
|
1250 | </dd> |
|
|
1251 | <dt>ev_tstamp offset [read-write]</dt> |
|
|
1252 | <dd> |
|
|
1253 | <p>When repeating, this contains the offset value, otherwise this is the |
|
|
1254 | absolute point in time (the <code>at</code> value passed to <code>ev_periodic_set</code>).</p> |
|
|
1255 | <p>Can be modified any time, but changes only take effect when the periodic |
|
|
1256 | timer fires or <code>ev_periodic_again</code> is being called.</p> |
1162 | </dd> |
1257 | </dd> |
1163 | <dt>ev_tstamp interval [read-write]</dt> |
1258 | <dt>ev_tstamp interval [read-write]</dt> |
1164 | <dd> |
1259 | <dd> |
1165 | <p>The current interval value. Can be modified any time, but changes only |
1260 | <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 |
1261 | take effect when the periodic timer fires or <code>ev_periodic_again</code> is being |
… | |
… | |
1221 | first watcher gets started will libev actually register a signal watcher |
1316 | first watcher gets started will libev actually register a signal watcher |
1222 | with the kernel (thus it coexists with your own signal handlers as long |
1317 | with the kernel (thus it coexists with your own signal handlers as long |
1223 | as you don't register any with libev). Similarly, when the last signal |
1318 | as you don't register any with libev). Similarly, when the last signal |
1224 | watcher for a signal is stopped libev will reset the signal handler to |
1319 | watcher for a signal is stopped libev will reset the signal handler to |
1225 | SIG_DFL (regardless of what it was set to before).</p> |
1320 | SIG_DFL (regardless of what it was set to before).</p> |
|
|
1321 | |
|
|
1322 | </div> |
|
|
1323 | <h3 id="Watcher_Specific_Functions_and_Data_-4">Watcher-Specific Functions and Data Members</h3> |
|
|
1324 | <div id="Watcher_Specific_Functions_and_Data_-2-2"> |
1226 | <dl> |
1325 | <dl> |
1227 | <dt>ev_signal_init (ev_signal *, callback, int signum)</dt> |
1326 | <dt>ev_signal_init (ev_signal *, callback, int signum)</dt> |
1228 | <dt>ev_signal_set (ev_signal *, int signum)</dt> |
1327 | <dt>ev_signal_set (ev_signal *, int signum)</dt> |
1229 | <dd> |
1328 | <dd> |
1230 | <p>Configures the watcher to trigger on the given signal number (usually one |
1329 | <p>Configures the watcher to trigger on the given signal number (usually one |
… | |
… | |
1243 | </div> |
1342 | </div> |
1244 | <h2 id="code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</h2> |
1343 | <h2 id="code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</h2> |
1245 | <div id="code_ev_child_code_watch_out_for_pro-2"> |
1344 | <div id="code_ev_child_code_watch_out_for_pro-2"> |
1246 | <p>Child watchers trigger when your process receives a SIGCHLD in response to |
1345 | <p>Child watchers trigger when your process receives a SIGCHLD in response to |
1247 | some child status changes (most typically when a child of yours dies).</p> |
1346 | some child status changes (most typically when a child of yours dies).</p> |
|
|
1347 | |
|
|
1348 | </div> |
|
|
1349 | <h3 id="Watcher_Specific_Functions_and_Data_-5">Watcher-Specific Functions and Data Members</h3> |
|
|
1350 | <div id="Watcher_Specific_Functions_and_Data_-2-3"> |
1248 | <dl> |
1351 | <dl> |
1249 | <dt>ev_child_init (ev_child *, callback, int pid)</dt> |
1352 | <dt>ev_child_init (ev_child *, callback, int pid)</dt> |
1250 | <dt>ev_child_set (ev_child *, int pid)</dt> |
1353 | <dt>ev_child_set (ev_child *, int pid)</dt> |
1251 | <dd> |
1354 | <dd> |
1252 | <p>Configures the watcher to wait for status changes of process <code>pid</code> (or |
1355 | <p>Configures the watcher to wait for status changes of process <code>pid</code> (or |
… | |
… | |
1315 | reader). Inotify will be used to give hints only and should not change the |
1418 | reader). Inotify will be used to give hints only and should not change the |
1316 | semantics of <code>ev_stat</code> watchers, which means that libev sometimes needs |
1419 | semantics of <code>ev_stat</code> watchers, which means that libev sometimes needs |
1317 | to fall back to regular polling again even with inotify, but changes are |
1420 | to fall back to regular polling again even with inotify, but changes are |
1318 | usually detected immediately, and if the file exists there will be no |
1421 | usually detected immediately, and if the file exists there will be no |
1319 | polling.</p> |
1422 | polling.</p> |
|
|
1423 | |
|
|
1424 | </div> |
|
|
1425 | <h3 id="Watcher_Specific_Functions_and_Data_-6">Watcher-Specific Functions and Data Members</h3> |
|
|
1426 | <div id="Watcher_Specific_Functions_and_Data_-2-4"> |
1320 | <dl> |
1427 | <dl> |
1321 | <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt> |
1428 | <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt> |
1322 | <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt> |
1429 | <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt> |
1323 | <dd> |
1430 | <dd> |
1324 | <p>Configures the watcher to wait for status changes of the given |
1431 | <p>Configures the watcher to wait for status changes of the given |
… | |
… | |
1402 | active, the process will not block when waiting for new events.</p> |
1509 | active, the process will not block when waiting for new events.</p> |
1403 | <p>Apart from keeping your process non-blocking (which is a useful |
1510 | <p>Apart from keeping your process non-blocking (which is a useful |
1404 | effect on its own sometimes), idle watchers are a good place to do |
1511 | effect on its own sometimes), idle watchers are a good place to do |
1405 | "pseudo-background processing", or delay processing stuff to after the |
1512 | "pseudo-background processing", or delay processing stuff to after the |
1406 | event loop has handled all outstanding events.</p> |
1513 | event loop has handled all outstanding events.</p> |
|
|
1514 | |
|
|
1515 | </div> |
|
|
1516 | <h3 id="Watcher_Specific_Functions_and_Data_-7">Watcher-Specific Functions and Data Members</h3> |
|
|
1517 | <div id="Watcher_Specific_Functions_and_Data_-2-5"> |
1407 | <dl> |
1518 | <dl> |
1408 | <dt>ev_idle_init (ev_signal *, callback)</dt> |
1519 | <dt>ev_idle_init (ev_signal *, callback)</dt> |
1409 | <dd> |
1520 | <dd> |
1410 | <p>Initialises and configures the idle watcher - it has no parameters of any |
1521 | <p>Initialises and configures the idle watcher - it has no parameters of any |
1411 | kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless, |
1522 | kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless, |
… | |
… | |
1465 | are ready to run (it's actually more complicated: it only runs coroutines |
1576 | 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 |
1577 | 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 |
1578 | 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 |
1579 | loop from blocking if lower-priority coroutines are active, thus mapping |
1469 | low-priority coroutines to idle/background tasks).</p> |
1580 | low-priority coroutines to idle/background tasks).</p> |
|
|
1581 | <p>It is recommended to give <code>ev_check</code> watchers highest (<code>EV_MAXPRI</code>) |
|
|
1582 | priority, to ensure that they are being run before any other watchers |
|
|
1583 | after the poll. Also, <code>ev_check</code> watchers (and <code>ev_prepare</code> watchers, |
|
|
1584 | too) should not activate ("feed") events into libev. While libev fully |
|
|
1585 | supports this, they will be called before other <code>ev_check</code> watchers did |
|
|
1586 | their job. As <code>ev_check</code> watchers are often used to embed other event |
|
|
1587 | loops those other event loops might be in an unusable state until their |
|
|
1588 | <code>ev_check</code> watcher ran (always remind yourself to coexist peacefully with |
|
|
1589 | others).</p> |
|
|
1590 | |
|
|
1591 | </div> |
|
|
1592 | <h3 id="Watcher_Specific_Functions_and_Data_-8">Watcher-Specific Functions and Data Members</h3> |
|
|
1593 | <div id="Watcher_Specific_Functions_and_Data_-2-6"> |
1470 | <dl> |
1594 | <dl> |
1471 | <dt>ev_prepare_init (ev_prepare *, callback)</dt> |
1595 | <dt>ev_prepare_init (ev_prepare *, callback)</dt> |
1472 | <dt>ev_check_init (ev_check *, callback)</dt> |
1596 | <dt>ev_check_init (ev_check *, callback)</dt> |
1473 | <dd> |
1597 | <dd> |
1474 | <p>Initialises and configures the prepare or check watcher - they have no |
1598 | <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> |
1599 | 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> |
1600 | macros, but using them is utterly, utterly and completely pointless.</p> |
1477 | </dd> |
1601 | </dd> |
1478 | </dl> |
1602 | </dl> |
1479 | <p>Example: To include a library such as adns, you would add IO watchers |
1603 | <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 |
1604 | into libev. Here are some ideas on how to include libadns into libev |
|
|
1605 | (there is a Perl module named <code>EV::ADNS</code> that does this, which you could |
|
|
1606 | use for an actually working example. Another Perl module named <code>EV::Glib</code> |
|
|
1607 | embeds a Glib main context into libev, and finally, <code>Glib::EV</code> embeds EV |
|
|
1608 | into the Glib event loop).</p> |
|
|
1609 | <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 |
1610 | and in a check watcher, destroy them and call into libadns. What follows |
1482 | pseudo-code only of course:</p> |
1611 | is pseudo-code only of course. This requires you to either use a low |
|
|
1612 | priority for the check watcher or use <code>ev_clear_pending</code> explicitly, as |
|
|
1613 | the callbacks for the IO/timeout watchers might not have been called yet.</p> |
1483 | <pre> static ev_io iow [nfd]; |
1614 | <pre> static ev_io iow [nfd]; |
1484 | static ev_timer tw; |
1615 | static ev_timer tw; |
1485 | |
1616 | |
1486 | static void |
1617 | static void |
1487 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1618 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1488 | { |
1619 | { |
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 | } |
1620 | } |
1495 | |
1621 | |
1496 | // create io watchers for each fd and a timer before blocking |
1622 | // create io watchers for each fd and a timer before blocking |
1497 | static void |
1623 | static void |
1498 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1624 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
… | |
… | |
1504 | |
1630 | |
1505 | /* the callback is illegal, but won't be called as we stop during check */ |
1631 | /* the callback is illegal, but won't be called as we stop during check */ |
1506 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1632 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1507 | ev_timer_start (loop, &tw); |
1633 | ev_timer_start (loop, &tw); |
1508 | |
1634 | |
1509 | // create on ev_io per pollfd |
1635 | // create one ev_io per pollfd |
1510 | for (int i = 0; i < nfd; ++i) |
1636 | for (int i = 0; i < nfd; ++i) |
1511 | { |
1637 | { |
1512 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1638 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1513 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1639 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1514 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1640 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1515 | |
1641 | |
1516 | fds [i].revents = 0; |
1642 | fds [i].revents = 0; |
1517 | iow [i].data = fds + i; |
|
|
1518 | ev_io_start (loop, iow + i); |
1643 | ev_io_start (loop, iow + i); |
1519 | } |
1644 | } |
1520 | } |
1645 | } |
1521 | |
1646 | |
1522 | // stop all watchers after blocking |
1647 | // stop all watchers after blocking |
… | |
… | |
1524 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1649 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1525 | { |
1650 | { |
1526 | ev_timer_stop (loop, &tw); |
1651 | ev_timer_stop (loop, &tw); |
1527 | |
1652 | |
1528 | for (int i = 0; i < nfd; ++i) |
1653 | for (int i = 0; i < nfd; ++i) |
|
|
1654 | { |
|
|
1655 | // set the relevant poll flags |
|
|
1656 | // could also call adns_processreadable etc. here |
|
|
1657 | struct pollfd *fd = fds + i; |
|
|
1658 | int revents = ev_clear_pending (iow + i); |
|
|
1659 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1660 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1661 | |
|
|
1662 | // now stop the watcher |
1529 | ev_io_stop (loop, iow + i); |
1663 | ev_io_stop (loop, iow + i); |
|
|
1664 | } |
1530 | |
1665 | |
1531 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
1666 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1667 | } |
|
|
1668 | |
|
|
1669 | </pre> |
|
|
1670 | <p>Method 2: This would be just like method 1, but you run <code>adns_afterpoll</code> |
|
|
1671 | in the prepare watcher and would dispose of the check watcher.</p> |
|
|
1672 | <p>Method 3: If the module to be embedded supports explicit event |
|
|
1673 | notification (adns does), you can also make use of the actual watcher |
|
|
1674 | callbacks, and only destroy/create the watchers in the prepare watcher.</p> |
|
|
1675 | <pre> static void |
|
|
1676 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1677 | { |
|
|
1678 | adns_state ads = (adns_state)w->data; |
|
|
1679 | update_now (EV_A); |
|
|
1680 | |
|
|
1681 | adns_processtimeouts (ads, &tv_now); |
|
|
1682 | } |
|
|
1683 | |
|
|
1684 | static void |
|
|
1685 | io_cb (EV_P_ ev_io *w, int revents) |
|
|
1686 | { |
|
|
1687 | adns_state ads = (adns_state)w->data; |
|
|
1688 | update_now (EV_A); |
|
|
1689 | |
|
|
1690 | if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now); |
|
|
1691 | if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now); |
|
|
1692 | } |
|
|
1693 | |
|
|
1694 | // do not ever call adns_afterpoll |
|
|
1695 | |
|
|
1696 | </pre> |
|
|
1697 | <p>Method 4: Do not use a prepare or check watcher because the module you |
|
|
1698 | want to embed is too inflexible to support it. Instead, youc na override |
|
|
1699 | their poll function. The drawback with this solution is that the main |
|
|
1700 | loop is now no longer controllable by EV. The <code>Glib::EV</code> module does |
|
|
1701 | this.</p> |
|
|
1702 | <pre> static gint |
|
|
1703 | event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
|
|
1704 | { |
|
|
1705 | int got_events = 0; |
|
|
1706 | |
|
|
1707 | for (n = 0; n < nfds; ++n) |
|
|
1708 | // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
|
|
1709 | |
|
|
1710 | if (timeout >= 0) |
|
|
1711 | // create/start timer |
|
|
1712 | |
|
|
1713 | // poll |
|
|
1714 | ev_loop (EV_A_ 0); |
|
|
1715 | |
|
|
1716 | // stop timer again |
|
|
1717 | if (timeout >= 0) |
|
|
1718 | ev_timer_stop (EV_A_ &to); |
|
|
1719 | |
|
|
1720 | // stop io watchers again - their callbacks should have set |
|
|
1721 | for (n = 0; n < nfds; ++n) |
|
|
1722 | ev_io_stop (EV_A_ iow [n]); |
|
|
1723 | |
|
|
1724 | return got_events; |
1532 | } |
1725 | } |
1533 | |
1726 | |
1534 | |
1727 | |
1535 | |
1728 | |
1536 | |
1729 | |
… | |
… | |
1597 | } |
1790 | } |
1598 | else |
1791 | else |
1599 | loop_lo = loop_hi; |
1792 | loop_lo = loop_hi; |
1600 | |
1793 | |
1601 | </pre> |
1794 | </pre> |
|
|
1795 | |
|
|
1796 | </div> |
|
|
1797 | <h3 id="Watcher_Specific_Functions_and_Data_-9">Watcher-Specific Functions and Data Members</h3> |
|
|
1798 | <div id="Watcher_Specific_Functions_and_Data_-2-7"> |
1602 | <dl> |
1799 | <dl> |
1603 | <dt>ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)</dt> |
1800 | <dt>ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)</dt> |
1604 | <dt>ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)</dt> |
1801 | <dt>ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)</dt> |
1605 | <dd> |
1802 | <dd> |
1606 | <p>Configures the watcher to embed the given loop, which must be |
1803 | <p>Configures the watcher to embed the given loop, which must be |
… | |
… | |
1733 | the callback model to a model using method callbacks on objects.</p> |
1930 | the callback model to a model using method callbacks on objects.</p> |
1734 | <p>To use it,</p> |
1931 | <p>To use it,</p> |
1735 | <pre> #include <ev++.h> |
1932 | <pre> #include <ev++.h> |
1736 | |
1933 | |
1737 | </pre> |
1934 | </pre> |
1738 | <p>(it is not installed by default). This automatically includes <cite>ev.h</cite> |
1935 | <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 |
1936 | 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> |
1937 | 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 |
1938 | options as <cite>ev.h</cite>, most notably <code>EV_MULTIPLICITY</code>.</p> |
1742 | <code>EV_MULTIPLICITY</code>.</p> |
1939 | <p>Care has been taken to keep the overhead low. The only data member the C++ |
|
|
1940 | classes add (compared to plain C-style watchers) is the event loop pointer |
|
|
1941 | that the watcher is associated with (or no additional members at all if |
|
|
1942 | you disable <code>EV_MULTIPLICITY</code> when embedding libev).</p> |
|
|
1943 | <p>Currently, functions, and static and non-static member functions can be |
|
|
1944 | used as callbacks. Other types should be easy to add as long as they only |
|
|
1945 | need one additional pointer for context. If you need support for other |
|
|
1946 | types of functors please contact the author (preferably after implementing |
|
|
1947 | it).</p> |
1743 | <p>Here is a list of things available in the <code>ev</code> namespace:</p> |
1948 | <p>Here is a list of things available in the <code>ev</code> namespace:</p> |
1744 | <dl> |
1949 | <dl> |
1745 | <dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt> |
1950 | <dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt> |
1746 | <dd> |
1951 | <dd> |
1747 | <p>These are just enum values with the same values as the <code>EV_READ</code> etc. |
1952 | <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 |
1963 | which is called <code>ev::sig</code> to avoid clashes with the <code>signal</code> macro |
1759 | defines by many implementations.</p> |
1964 | defines by many implementations.</p> |
1760 | <p>All of those classes have these methods:</p> |
1965 | <p>All of those classes have these methods:</p> |
1761 | <p> |
1966 | <p> |
1762 | <dl> |
1967 | <dl> |
1763 | <dt>ev::TYPE::TYPE (object *, object::method *)</dt> |
1968 | <dt>ev::TYPE::TYPE ()</dt> |
1764 | <dt>ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)</dt> |
1969 | <dt>ev::TYPE::TYPE (struct ev_loop *)</dt> |
1765 | <dt>ev::TYPE::~TYPE</dt> |
1970 | <dt>ev::TYPE::~TYPE</dt> |
1766 | <dd> |
1971 | <dd> |
1767 | <p>The constructor takes a pointer to an object and a method pointer to |
1972 | <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 |
1973 | 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 |
1974 | <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 |
1975 | <code>set</code> method before starting it.</p> |
1771 | automatically associates the default loop with this watcher.</p> |
1976 | <p>It will not set a callback, however: You have to call the templated <code>set</code> |
|
|
1977 | method to set a callback before you can start the watcher.</p> |
|
|
1978 | <p>(The reason why you have to use a method is a limitation in C++ which does |
|
|
1979 | not allow explicit template arguments for constructors).</p> |
1772 | <p>The destructor automatically stops the watcher if it is active.</p> |
1980 | <p>The destructor automatically stops the watcher if it is active.</p> |
|
|
1981 | </dd> |
|
|
1982 | <dt>w->set<class, &class::method> (object *)</dt> |
|
|
1983 | <dd> |
|
|
1984 | <p>This method sets the callback method to call. The method has to have a |
|
|
1985 | signature of <code>void (*)(ev_TYPE &, int)</code>, it receives the watcher as |
|
|
1986 | first argument and the <code>revents</code> as second. The object must be given as |
|
|
1987 | parameter and is stored in the <code>data</code> member of the watcher.</p> |
|
|
1988 | <p>This method synthesizes efficient thunking code to call your method from |
|
|
1989 | the C callback that libev requires. If your compiler can inline your |
|
|
1990 | callback (i.e. it is visible to it at the place of the <code>set</code> call and |
|
|
1991 | your compiler is good :), then the method will be fully inlined into the |
|
|
1992 | thunking function, making it as fast as a direct C callback.</p> |
|
|
1993 | <p>Example: simple class declaration and watcher initialisation</p> |
|
|
1994 | <pre> struct myclass |
|
|
1995 | { |
|
|
1996 | void io_cb (ev::io &w, int revents) { } |
|
|
1997 | } |
|
|
1998 | |
|
|
1999 | myclass obj; |
|
|
2000 | ev::io iow; |
|
|
2001 | iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
2002 | |
|
|
2003 | </pre> |
|
|
2004 | </dd> |
|
|
2005 | <dt>w->set<function> (void *data = 0)</dt> |
|
|
2006 | <dd> |
|
|
2007 | <p>Also sets a callback, but uses a static method or plain function as |
|
|
2008 | callback. The optional <code>data</code> argument will be stored in the watcher's |
|
|
2009 | <code>data</code> member and is free for you to use.</p> |
|
|
2010 | <p>The prototype of the <code>function</code> must be <code>void (*)(ev::TYPE &w, int)</code>.</p> |
|
|
2011 | <p>See the method-<code>set</code> above for more details.</p> |
|
|
2012 | <p>Example:</p> |
|
|
2013 | <pre> static void io_cb (ev::io &w, int revents) { } |
|
|
2014 | iow.set <io_cb> (); |
|
|
2015 | |
|
|
2016 | </pre> |
1773 | </dd> |
2017 | </dd> |
1774 | <dt>w->set (struct ev_loop *)</dt> |
2018 | <dt>w->set (struct ev_loop *)</dt> |
1775 | <dd> |
2019 | <dd> |
1776 | <p>Associates a different <code>struct ev_loop</code> with this watcher. You can only |
2020 | <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> |
2021 | do this when the watcher is inactive (and not pending either).</p> |
1778 | </dd> |
2022 | </dd> |
1779 | <dt>w->set ([args])</dt> |
2023 | <dt>w->set ([args])</dt> |
1780 | <dd> |
2024 | <dd> |
1781 | <p>Basically the same as <code>ev_TYPE_set</code>, with the same args. Must be |
2025 | <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 |
2026 | called at least once. Unlike the C counterpart, an active watcher gets |
1783 | automatically stopped and restarted.</p> |
2027 | automatically stopped and restarted when reconfiguring it with this |
|
|
2028 | method.</p> |
1784 | </dd> |
2029 | </dd> |
1785 | <dt>w->start ()</dt> |
2030 | <dt>w->start ()</dt> |
1786 | <dd> |
2031 | <dd> |
1787 | <p>Starts the watcher. Note that there is no <code>loop</code> argument as the |
2032 | <p>Starts the watcher. Note that there is no <code>loop</code> argument, as the |
1788 | constructor already takes the loop.</p> |
2033 | constructor already stores the event loop.</p> |
1789 | </dd> |
2034 | </dd> |
1790 | <dt>w->stop ()</dt> |
2035 | <dt>w->stop ()</dt> |
1791 | <dd> |
2036 | <dd> |
1792 | <p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p> |
2037 | <p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p> |
1793 | </dd> |
2038 | </dd> |
… | |
… | |
1817 | |
2062 | |
1818 | myclass (); |
2063 | myclass (); |
1819 | } |
2064 | } |
1820 | |
2065 | |
1821 | myclass::myclass (int fd) |
2066 | myclass::myclass (int fd) |
1822 | : io (this, &myclass::io_cb), |
|
|
1823 | idle (this, &myclass::idle_cb) |
|
|
1824 | { |
2067 | { |
|
|
2068 | io .set <myclass, &myclass::io_cb > (this); |
|
|
2069 | idle.set <myclass, &myclass::idle_cb> (this); |
|
|
2070 | |
1825 | io.start (fd, ev::READ); |
2071 | io.start (fd, ev::READ); |
1826 | } |
2072 | } |
1827 | |
2073 | |
1828 | |
2074 | |
1829 | |
2075 | |
… | |
… | |
2109 | <p>If undefined or defined to <code>1</code>, then all event-loop-specific functions |
2355 | <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 |
2356 | 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 |
2357 | additional independent event loops. Otherwise there will be no support |
2112 | for multiple event loops and there is no first event loop pointer |
2358 | for multiple event loops and there is no first event loop pointer |
2113 | argument. Instead, all functions act on the single default loop.</p> |
2359 | argument. Instead, all functions act on the single default loop.</p> |
|
|
2360 | </dd> |
|
|
2361 | <dt>EV_MINPRI</dt> |
|
|
2362 | <dt>EV_MAXPRI</dt> |
|
|
2363 | <dd> |
|
|
2364 | <p>The range of allowed priorities. <code>EV_MINPRI</code> must be smaller or equal to |
|
|
2365 | <code>EV_MAXPRI</code>, but otherwise there are no non-obvious limitations. You can |
|
|
2366 | provide for more priorities by overriding those symbols (usually defined |
|
|
2367 | to be <code>-2</code> and <code>2</code>, respectively).</p> |
|
|
2368 | <p>When doing priority-based operations, libev usually has to linearly search |
|
|
2369 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
2370 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
|
|
2371 | fine.</p> |
|
|
2372 | <p>If your embedding app does not need any priorities, defining these both to |
|
|
2373 | <code>0</code> will save some memory and cpu.</p> |
2114 | </dd> |
2374 | </dd> |
2115 | <dt>EV_PERIODIC_ENABLE</dt> |
2375 | <dt>EV_PERIODIC_ENABLE</dt> |
2116 | <dd> |
2376 | <dd> |
2117 | <p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If |
2377 | <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 |
2378 | defined to be <code>0</code>, then they are not. Disabling them saves a few kB of |
… | |
… | |
2222 | <h1 id="COMPLEXITIES">COMPLEXITIES</h1> |
2482 | <h1 id="COMPLEXITIES">COMPLEXITIES</h1> |
2223 | <div id="COMPLEXITIES_CONTENT"> |
2483 | <div id="COMPLEXITIES_CONTENT"> |
2224 | <p>In this section the complexities of (many of) the algorithms used inside |
2484 | <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 |
2485 | libev will be explained. For complexity discussions about backends see the |
2226 | documentation for <code>ev_default_init</code>.</p> |
2486 | documentation for <code>ev_default_init</code>.</p> |
|
|
2487 | <p>All of the following are about amortised time: If an array needs to be |
|
|
2488 | extended, libev needs to realloc and move the whole array, but this |
|
|
2489 | happens asymptotically never with higher number of elements, so O(1) might |
|
|
2490 | mean it might do a lengthy realloc operation in rare cases, but on average |
|
|
2491 | it is much faster and asymptotically approaches constant time.</p> |
2227 | <p> |
2492 | <p> |
2228 | <dl> |
2493 | <dl> |
2229 | <dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt> |
2494 | <dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt> |
|
|
2495 | <dd> |
|
|
2496 | <p>This means that, when you have a watcher that triggers in one hour and |
|
|
2497 | there are 100 watchers that would trigger before that then inserting will |
|
|
2498 | have to skip those 100 watchers.</p> |
|
|
2499 | </dd> |
2230 | <dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt> |
2500 | <dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt> |
|
|
2501 | <dd> |
|
|
2502 | <p>That means that for changing a timer costs less than removing/adding them |
|
|
2503 | as only the relative motion in the event queue has to be paid for.</p> |
|
|
2504 | </dd> |
2231 | <dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt> |
2505 | <dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt> |
|
|
2506 | <dd> |
|
|
2507 | <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> |
2508 | =item Stopping check/prepare/idle watchers: O(1)</p> |
|
|
2509 | </dd> |
2233 | <dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))</dt> |
2510 | <dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))</dt> |
|
|
2511 | <dd> |
|
|
2512 | <p>These watchers are stored in lists then need to be walked to find the |
|
|
2513 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
2514 | have many watchers waiting for the same fd or signal).</p> |
|
|
2515 | </dd> |
2234 | <dt>Finding the next timer per loop iteration: O(1)</dt> |
2516 | <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> |
2517 | <dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt> |
|
|
2518 | <dd> |
|
|
2519 | <p>A change means an I/O watcher gets started or stopped, which requires |
|
|
2520 | libev to recalculate its status (and possibly tell the kernel).</p> |
|
|
2521 | </dd> |
2236 | <dt>Activating one watcher: O(1)</dt> |
2522 | <dt>Activating one watcher: O(1)</dt> |
|
|
2523 | <dt>Priority handling: O(number_of_priorities)</dt> |
|
|
2524 | <dd> |
|
|
2525 | <p>Priorities are implemented by allocating some space for each |
|
|
2526 | priority. When doing priority-based operations, libev usually has to |
|
|
2527 | linearly search all the priorities.</p> |
|
|
2528 | </dd> |
2237 | </dl> |
2529 | </dl> |
2238 | </p> |
2530 | </p> |
2239 | |
2531 | |
2240 | |
2532 | |
2241 | |
2533 | |