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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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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="Tue Nov 27 21:29:04 2007" /> |
9 | <meta name="created" content="Wed Nov 28 12:27:27 2007" /> |
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12 | <body> |
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13 | <div class="pod"> |
13 | <div class="pod"> |
14 | <!-- INDEX START --> |
14 | <!-- INDEX START --> |
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741 | events but its callback has not yet been invoked). As long as a watcher |
741 | events but its callback has not yet been invoked). As long as a watcher |
742 | is pending (but not active) you must not call an init function on it (but |
742 | is pending (but not active) you must not call an init function on it (but |
743 | <code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to |
743 | <code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to |
744 | libev (e.g. you cnanot <code>free ()</code> it).</p> |
744 | libev (e.g. you cnanot <code>free ()</code> it).</p> |
745 | </dd> |
745 | </dd> |
746 | <dt>callback = ev_cb (ev_TYPE *watcher)</dt> |
746 | <dt>callback ev_cb (ev_TYPE *watcher)</dt> |
747 | <dd> |
747 | <dd> |
748 | <p>Returns the callback currently set on the watcher.</p> |
748 | <p>Returns the callback currently set on the watcher.</p> |
749 | </dd> |
749 | </dd> |
750 | <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt> |
750 | <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt> |
751 | <dd> |
751 | <dd> |
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783 | struct my_io *w = (struct my_io *)w_; |
783 | struct my_io *w = (struct my_io *)w_; |
784 | ... |
784 | ... |
785 | } |
785 | } |
786 | |
786 | |
787 | </pre> |
787 | </pre> |
788 | <p>More interesting and less C-conformant ways of catsing your callback type |
788 | <p>More interesting and less C-conformant ways of casting your callback type |
789 | have been omitted....</p> |
789 | instead have been omitted.</p> |
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790 | <p>Another common scenario is having some data structure with multiple |
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791 | watchers:</p> |
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792 | <pre> struct my_biggy |
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793 | { |
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794 | int some_data; |
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795 | ev_timer t1; |
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796 | ev_timer t2; |
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797 | } |
790 | |
798 | |
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799 | </pre> |
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800 | <p>In this case getting the pointer to <code>my_biggy</code> is a bit more complicated, |
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801 | you need to use <code>offsetof</code>:</p> |
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802 | <pre> #include <stddef.h> |
791 | |
803 | |
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804 | static void |
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805 | t1_cb (EV_P_ struct ev_timer *w, int revents) |
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806 | { |
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807 | struct my_biggy big = (struct my_biggy * |
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808 | (((char *)w) - offsetof (struct my_biggy, t1)); |
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809 | } |
792 | |
810 | |
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811 | static void |
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812 | t2_cb (EV_P_ struct ev_timer *w, int revents) |
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813 | { |
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814 | struct my_biggy big = (struct my_biggy * |
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815 | (((char *)w) - offsetof (struct my_biggy, t2)); |
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816 | } |
793 | |
817 | |
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818 | |
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819 | |
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820 | |
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821 | </pre> |
794 | |
822 | |
795 | </div> |
823 | </div> |
796 | <h1 id="WATCHER_TYPES">WATCHER TYPES</h1> |
824 | <h1 id="WATCHER_TYPES">WATCHER TYPES</h1> |
797 | <div id="WATCHER_TYPES_CONTENT"> |
825 | <div id="WATCHER_TYPES_CONTENT"> |
798 | <p>This section describes each watcher in detail, but will not repeat |
826 | <p>This section describes each watcher in detail, but will not repeat |
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1219 | not exist" is a status change like any other. The condition "path does |
1247 | not exist" is a status change like any other. The condition "path does |
1220 | not exist" is signified by the <code>st_nlink</code> field being zero (which is |
1248 | not exist" is signified by the <code>st_nlink</code> field being zero (which is |
1221 | otherwise always forced to be at least one) and all the other fields of |
1249 | otherwise always forced to be at least one) and all the other fields of |
1222 | the stat buffer having unspecified contents.</p> |
1250 | the stat buffer having unspecified contents.</p> |
1223 | <p>Since there is no standard to do this, the portable implementation simply |
1251 | <p>Since there is no standard to do this, the portable implementation simply |
1224 | calls <code>stat (2)</code> regulalry on the path to see if it changed somehow. You |
1252 | calls <code>stat (2)</code> regularly on the path to see if it changed somehow. You |
1225 | can specify a recommended polling interval for this case. If you specify |
1253 | can specify a recommended polling interval for this case. If you specify |
1226 | a polling interval of <code>0</code> (highly recommended!) then a <i>suitable, |
1254 | a polling interval of <code>0</code> (highly recommended!) then a <i>suitable, |
1227 | unspecified default</i> value will be used (which you can expect to be around |
1255 | unspecified default</i> value will be used (which you can expect to be around |
1228 | five seconds, although this might change dynamically). Libev will also |
1256 | five seconds, although this might change dynamically). Libev will also |
1229 | impose a minimum interval which is currently around <code>0.1</code>, but thats |
1257 | impose a minimum interval which is currently around <code>0.1</code>, but thats |
1230 | usually overkill.</p> |
1258 | usually overkill.</p> |
1231 | <p>This watcher type is not meant for massive numbers of stat watchers, |
1259 | <p>This watcher type is not meant for massive numbers of stat watchers, |
1232 | as even with OS-supported change notifications, this can be |
1260 | as even with OS-supported change notifications, this can be |
1233 | resource-intensive.</p> |
1261 | resource-intensive.</p> |
1234 | <p>At the time of this writing, no specific OS backends are implemented, but |
1262 | <p>At the time of this writing, only the Linux inotify interface is |
1235 | if demand increases, at least a kqueue and inotify backend will be added.</p> |
1263 | implemented (implementing kqueue support is left as an exercise for the |
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1264 | reader). Inotify will be used to give hints only and should not change the |
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1265 | semantics of <code>ev_stat</code> watchers, which means that libev sometimes needs |
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1266 | to fall back to regular polling again even with inotify, but changes are |
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1267 | usually detected immediately, and if the file exists there will be no |
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1268 | polling.</p> |
1236 | <dl> |
1269 | <dl> |
1237 | <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt> |
1270 | <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt> |
1238 | <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt> |
1271 | <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt> |
1239 | <dd> |
1272 | <dd> |
1240 | <p>Configures the watcher to wait for status changes of the given |
1273 | <p>Configures the watcher to wait for status changes of the given |
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1987 | </dd> |
2020 | </dd> |
1988 | <dt>EV_USE_DEVPOLL</dt> |
2021 | <dt>EV_USE_DEVPOLL</dt> |
1989 | <dd> |
2022 | <dd> |
1990 | <p>reserved for future expansion, works like the USE symbols above.</p> |
2023 | <p>reserved for future expansion, works like the USE symbols above.</p> |
1991 | </dd> |
2024 | </dd> |
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2025 | <dt>EV_USE_INOTIFY</dt> |
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2026 | <dd> |
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2027 | <p>If defined to be <code>1</code>, libev will compile in support for the Linux inotify |
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2028 | interface to speed up <code>ev_stat</code> watchers. Its actual availability will |
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2029 | be detected at runtime.</p> |
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2030 | </dd> |
1992 | <dt>EV_H</dt> |
2031 | <dt>EV_H</dt> |
1993 | <dd> |
2032 | <dd> |
1994 | <p>The name of the <cite>ev.h</cite> header file used to include it. The default if |
2033 | <p>The name of the <cite>ev.h</cite> header file used to include it. The default if |
1995 | undefined is <code><ev.h></code> in <cite>event.h</cite> and <code>"ev.h"</code> in <cite>ev.c</cite>. This |
2034 | undefined is <code><ev.h></code> in <cite>event.h</cite> and <code>"ev.h"</code> in <cite>ev.c</cite>. This |
1996 | can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p> |
2035 | can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p> |
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2051 | <dt>EV_PID_HASHSIZE</dt> |
2090 | <dt>EV_PID_HASHSIZE</dt> |
2052 | <dd> |
2091 | <dd> |
2053 | <p><code>ev_child</code> watchers use a small hash table to distribute workload by |
2092 | <p><code>ev_child</code> watchers use a small hash table to distribute workload by |
2054 | pid. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), usually more |
2093 | pid. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), usually more |
2055 | than enough. If you need to manage thousands of children you might want to |
2094 | than enough. If you need to manage thousands of children you might want to |
2056 | increase this value.</p> |
2095 | increase this value (<i>must</i> be a power of two).</p> |
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2096 | </dd> |
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2097 | <dt>EV_INOTIFY_HASHSIZE</dt> |
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2098 | <dd> |
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2099 | <p><code>ev_staz</code> watchers use a small hash table to distribute workload by |
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2100 | inotify watch id. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), |
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2101 | usually more than enough. If you need to manage thousands of <code>ev_stat</code> |
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2102 | watchers you might want to increase this value (<i>must</i> be a power of |
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2103 | two).</p> |
2057 | </dd> |
2104 | </dd> |
2058 | <dt>EV_COMMON</dt> |
2105 | <dt>EV_COMMON</dt> |
2059 | <dd> |
2106 | <dd> |
2060 | <p>By default, all watchers have a <code>void *data</code> member. By redefining |
2107 | <p>By default, all watchers have a <code>void *data</code> member. By redefining |
2061 | this macro to a something else you can include more and other types of |
2108 | this macro to a something else you can include more and other types of |
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2118 | <dl> |
2165 | <dl> |
2119 | <dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt> |
2166 | <dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt> |
2120 | <dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt> |
2167 | <dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt> |
2121 | <dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt> |
2168 | <dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt> |
2122 | <dt>Stopping check/prepare/idle watchers: O(1)</dt> |
2169 | <dt>Stopping check/prepare/idle watchers: O(1)</dt> |
2123 | <dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))</dt> |
2170 | <dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))</dt> |
2124 | <dt>Finding the next timer per loop iteration: O(1)</dt> |
2171 | <dt>Finding the next timer per loop iteration: O(1)</dt> |
2125 | <dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt> |
2172 | <dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt> |
2126 | <dt>Activating one watcher: O(1)</dt> |
2173 | <dt>Activating one watcher: O(1)</dt> |
2127 | </dl> |
2174 | </dl> |
2128 | </p> |
2175 | </p> |