… | |
… | |
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="Mon Nov 12 09:20:02 2007" /> |
9 | <meta name="created" content="Fri Nov 23 16:26:06 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 --> |
… | |
… | |
17 | <ul><li><a href="#NAME">NAME</a></li> |
17 | <ul><li><a href="#NAME">NAME</a></li> |
18 | <li><a href="#SYNOPSIS">SYNOPSIS</a></li> |
18 | <li><a href="#SYNOPSIS">SYNOPSIS</a></li> |
19 | <li><a href="#DESCRIPTION">DESCRIPTION</a></li> |
19 | <li><a href="#DESCRIPTION">DESCRIPTION</a></li> |
20 | <li><a href="#FEATURES">FEATURES</a></li> |
20 | <li><a href="#FEATURES">FEATURES</a></li> |
21 | <li><a href="#CONVENTIONS">CONVENTIONS</a></li> |
21 | <li><a href="#CONVENTIONS">CONVENTIONS</a></li> |
|
|
22 | <li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li> |
22 | <li><a href="#TIME_AND_OTHER_GLOBAL_FUNCTIONS">TIME AND OTHER GLOBAL FUNCTIONS</a></li> |
23 | <li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li> |
23 | <li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li> |
24 | <li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li> |
24 | <li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a> |
25 | <li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a> |
25 | <ul><li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li> |
26 | <ul><li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li> |
26 | </ul> |
27 | </ul> |
27 | </li> |
28 | </li> |
28 | <li><a href="#WATCHER_TYPES">WATCHER TYPES</a> |
29 | <li><a href="#WATCHER_TYPES">WATCHER TYPES</a> |
29 | <ul><li><a href="#struct_ev_io_is_my_file_descriptor_r">struct ev_io - is my file descriptor readable or writable</a></li> |
30 | <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> |
30 | <li><a href="#struct_ev_timer_relative_and_optiona">struct ev_timer - relative and optionally recurring timeouts</a></li> |
31 | <li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</a></li> |
31 | <li><a href="#ev_periodic_to_cron_or_not_to_cron_i">ev_periodic - to cron or not to cron it</a></li> |
32 | <li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</a></li> |
32 | <li><a href="#ev_signal_signal_me_when_a_signal_ge">ev_signal - signal me when a signal gets signalled</a></li> |
33 | <li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</a></li> |
33 | <li><a href="#ev_child_wait_for_pid_status_changes">ev_child - wait for pid status changes</a></li> |
34 | <li><a href="#code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</a></li> |
34 | <li><a href="#ev_idle_when_you_ve_got_nothing_bett">ev_idle - when you've got nothing better to do</a></li> |
35 | <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> |
35 | <li><a href="#prepare_and_check_your_hooks_into_th">prepare and check - your hooks into the event loop</a></li> |
36 | <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> |
36 | </ul> |
37 | </ul> |
37 | </li> |
38 | </li> |
38 | <li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> |
39 | <li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> |
|
|
40 | <li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li> |
|
|
41 | <li><a href="#C_SUPPORT">C++ SUPPORT</a></li> |
39 | <li><a href="#AUTHOR">AUTHOR</a> |
42 | <li><a href="#AUTHOR">AUTHOR</a> |
40 | </li> |
43 | </li> |
41 | </ul><hr /> |
44 | </ul><hr /> |
42 | <!-- INDEX END --> |
45 | <!-- INDEX END --> |
43 | |
46 | |
… | |
… | |
87 | support for multiple event loops, then all functions taking an initial |
90 | support for multiple event loops, then all functions taking an initial |
88 | argument of name <code>loop</code> (which is always of type <code>struct ev_loop *</code>) |
91 | argument of name <code>loop</code> (which is always of type <code>struct ev_loop *</code>) |
89 | will not have this argument.</p> |
92 | will not have this argument.</p> |
90 | |
93 | |
91 | </div> |
94 | </div> |
92 | <h1 id="TIME_AND_OTHER_GLOBAL_FUNCTIONS">TIME AND OTHER GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
95 | <h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
93 | <div id="TIME_AND_OTHER_GLOBAL_FUNCTIONS_CONT"> |
96 | <div id="TIME_REPRESENTATION_CONTENT"> |
94 | <p>Libev represents time as a single floating point number, representing the |
97 | <p>Libev represents time as a single floating point number, representing the |
95 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
98 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
96 | the beginning of 1970, details are complicated, don't ask). This type is |
99 | the beginning of 1970, details are complicated, don't ask). This type is |
97 | called <code>ev_tstamp</code>, which is what you should use too. It usually aliases |
100 | called <code>ev_tstamp</code>, which is what you should use too. It usually aliases |
98 | to the double type in C.</p> |
101 | to the double type in C.</p> |
|
|
102 | |
|
|
103 | </div> |
|
|
104 | <h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
|
|
105 | <div id="GLOBAL_FUNCTIONS_CONTENT"> |
|
|
106 | <p>These functions can be called anytime, even before initialising the |
|
|
107 | library in any way.</p> |
99 | <dl> |
108 | <dl> |
100 | <dt>ev_tstamp ev_time ()</dt> |
109 | <dt>ev_tstamp ev_time ()</dt> |
101 | <dd> |
110 | <dd> |
102 | <p>Returns the current time as libev would use it.</p> |
111 | <p>Returns the current time as libev would use it. Please note that the |
|
|
112 | <code>ev_now</code> function is usually faster and also often returns the timestamp |
|
|
113 | you actually want to know.</p> |
103 | </dd> |
114 | </dd> |
104 | <dt>int ev_version_major ()</dt> |
115 | <dt>int ev_version_major ()</dt> |
105 | <dt>int ev_version_minor ()</dt> |
116 | <dt>int ev_version_minor ()</dt> |
106 | <dd> |
117 | <dd> |
107 | <p>You can find out the major and minor version numbers of the library |
118 | <p>You can find out the major and minor version numbers of the library |
108 | you linked against by calling the functions <code>ev_version_major</code> and |
119 | you linked against by calling the functions <code>ev_version_major</code> and |
109 | <code>ev_version_minor</code>. If you want, you can compare against the global |
120 | <code>ev_version_minor</code>. If you want, you can compare against the global |
110 | symbols <code>EV_VERSION_MAJOR</code> and <code>EV_VERSION_MINOR</code>, which specify the |
121 | symbols <code>EV_VERSION_MAJOR</code> and <code>EV_VERSION_MINOR</code>, which specify the |
111 | version of the library your program was compiled against.</p> |
122 | version of the library your program was compiled against.</p> |
112 | <p>Usually, its a good idea to terminate if the major versions mismatch, |
123 | <p>Usually, it's a good idea to terminate if the major versions mismatch, |
113 | as this indicates an incompatible change. Minor versions are usually |
124 | as this indicates an incompatible change. Minor versions are usually |
114 | compatible to older versions, so a larger minor version alone is usually |
125 | compatible to older versions, so a larger minor version alone is usually |
115 | not a problem.</p> |
126 | not a problem.</p> |
|
|
127 | </dd> |
|
|
128 | <dt>unsigned int ev_supported_backends ()</dt> |
|
|
129 | <dd> |
|
|
130 | <p>Return the set of all backends (i.e. their corresponding <code>EV_BACKEND_*</code> |
|
|
131 | value) compiled into this binary of libev (independent of their |
|
|
132 | availability on the system you are running on). See <code>ev_default_loop</code> for |
|
|
133 | a description of the set values.</p> |
|
|
134 | </dd> |
|
|
135 | <dt>unsigned int ev_recommended_backends ()</dt> |
|
|
136 | <dd> |
|
|
137 | <p>Return the set of all backends compiled into this binary of libev and also |
|
|
138 | recommended for this platform. This set is often smaller than the one |
|
|
139 | returned by <code>ev_supported_backends</code>, as for example kqueue is broken on |
|
|
140 | most BSDs and will not be autodetected unless you explicitly request it |
|
|
141 | (assuming you know what you are doing). This is the set of backends that |
|
|
142 | libev will probe for if you specify no backends explicitly.</p> |
116 | </dd> |
143 | </dd> |
117 | <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> |
144 | <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> |
118 | <dd> |
145 | <dd> |
119 | <p>Sets the allocation function to use (the prototype is similar to the |
146 | <p>Sets the allocation function to use (the prototype is similar to the |
120 | realloc C function, the semantics are identical). It is used to allocate |
147 | realloc C function, the semantics are identical). It is used to allocate |
… | |
… | |
142 | <div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2"> |
169 | <div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2"> |
143 | <p>An event loop is described by a <code>struct ev_loop *</code>. The library knows two |
170 | <p>An event loop is described by a <code>struct ev_loop *</code>. The library knows two |
144 | types of such loops, the <i>default</i> loop, which supports signals and child |
171 | types of such loops, the <i>default</i> loop, which supports signals and child |
145 | events, and dynamically created loops which do not.</p> |
172 | events, and dynamically created loops which do not.</p> |
146 | <p>If you use threads, a common model is to run the default event loop |
173 | <p>If you use threads, a common model is to run the default event loop |
147 | in your main thread (or in a separate thrad) and for each thread you |
174 | in your main thread (or in a separate thread) and for each thread you |
148 | create, you also create another event loop. Libev itself does no locking |
175 | create, you also create another event loop. Libev itself does no locking |
149 | whatsoever, so if you mix calls to the same event loop in different |
176 | whatsoever, so if you mix calls to the same event loop in different |
150 | threads, make sure you lock (this is usually a bad idea, though, even if |
177 | threads, make sure you lock (this is usually a bad idea, though, even if |
151 | done correctly, because its hideous and inefficient).</p> |
178 | done correctly, because it's hideous and inefficient).</p> |
152 | <dl> |
179 | <dl> |
153 | <dt>struct ev_loop *ev_default_loop (unsigned int flags)</dt> |
180 | <dt>struct ev_loop *ev_default_loop (unsigned int flags)</dt> |
154 | <dd> |
181 | <dd> |
155 | <p>This will initialise the default event loop if it hasn't been initialised |
182 | <p>This will initialise the default event loop if it hasn't been initialised |
156 | yet and return it. If the default loop could not be initialised, returns |
183 | yet and return it. If the default loop could not be initialised, returns |
157 | false. If it already was initialised it simply returns it (and ignores the |
184 | false. If it already was initialised it simply returns it (and ignores the |
158 | flags).</p> |
185 | flags. If that is troubling you, check <code>ev_backend ()</code> afterwards).</p> |
159 | <p>If you don't know what event loop to use, use the one returned from this |
186 | <p>If you don't know what event loop to use, use the one returned from this |
160 | function.</p> |
187 | function.</p> |
161 | <p>The flags argument can be used to specify special behaviour or specific |
188 | <p>The flags argument can be used to specify special behaviour or specific |
162 | backends to use, and is usually specified as 0 (or EVFLAG_AUTO).</p> |
189 | backends to use, and is usually specified as <code>0</code> (or <code>EVFLAG_AUTO</code>).</p> |
163 | <p>It supports the following flags:</p> |
190 | <p>The following flags are supported:</p> |
164 | <p> |
191 | <p> |
165 | <dl> |
192 | <dl> |
166 | <dt>EVFLAG_AUTO</dt> |
193 | <dt><code>EVFLAG_AUTO</code></dt> |
167 | <dd> |
194 | <dd> |
168 | <p>The default flags value. Use this if you have no clue (its the right |
195 | <p>The default flags value. Use this if you have no clue (it's the right |
169 | thing, believe me).</p> |
196 | thing, believe me).</p> |
170 | </dd> |
197 | </dd> |
171 | <dt>EVFLAG_NOENV</dt> |
198 | <dt><code>EVFLAG_NOENV</code></dt> |
172 | <dd> |
199 | <dd> |
173 | <p>If this flag bit is ored into the flag value (or the program runs setuid |
200 | <p>If this flag bit is ored into the flag value (or the program runs setuid |
174 | or setgid) then libev will <i>not</i> look at the environment variable |
201 | or setgid) then libev will <i>not</i> look at the environment variable |
175 | <code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will |
202 | <code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will |
176 | override the flags completely if it is found in the environment. This is |
203 | override the flags completely if it is found in the environment. This is |
177 | useful to try out specific backends to test their performance, or to work |
204 | useful to try out specific backends to test their performance, or to work |
178 | around bugs.</p> |
205 | around bugs.</p> |
179 | </dd> |
206 | </dd> |
180 | <dt>EVMETHOD_SELECT portable select backend</dt> |
207 | <dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt> |
181 | <dt>EVMETHOD_POLL poll backend (everywhere except windows)</dt> |
208 | <dd> |
182 | <dt>EVMETHOD_EPOLL linux only</dt> |
209 | <p>This is your standard select(2) backend. Not <i>completely</i> standard, as |
183 | <dt>EVMETHOD_KQUEUE some bsds only</dt> |
210 | libev tries to roll its own fd_set with no limits on the number of fds, |
184 | <dt>EVMETHOD_DEVPOLL solaris 8 only</dt> |
211 | but if that fails, expect a fairly low limit on the number of fds when |
185 | <dt>EVMETHOD_PORT solaris 10 only</dt> |
212 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
|
|
213 | the fastest backend for a low number of fds.</p> |
186 | <dd> |
214 | </dd> |
187 | <p>If one or more of these are ored into the flags value, then only these |
215 | <dt><code>EVBACKEND_POLL</code> (value 2, poll backend, available everywhere except on windows)</dt> |
188 | backends will be tried (in the reverse order as given here). If one are |
216 | <dd> |
189 | specified, any backend will do.</p> |
217 | <p>And this is your standard poll(2) backend. It's more complicated than |
|
|
218 | select, but handles sparse fds better and has no artificial limit on the |
|
|
219 | number of fds you can use (except it will slow down considerably with a |
|
|
220 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds).</p> |
|
|
221 | </dd> |
|
|
222 | <dt><code>EVBACKEND_EPOLL</code> (value 4, Linux)</dt> |
|
|
223 | <dd> |
|
|
224 | <p>For few fds, this backend is a bit little slower than poll and select, |
|
|
225 | but it scales phenomenally better. While poll and select usually scale like |
|
|
226 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
|
|
227 | either O(1) or O(active_fds).</p> |
|
|
228 | <p>While stopping and starting an I/O watcher in the same iteration will |
|
|
229 | result in some caching, there is still a syscall per such incident |
|
|
230 | (because the fd could point to a different file description now), so its |
|
|
231 | best to avoid that. Also, dup()ed file descriptors might not work very |
|
|
232 | well if you register events for both fds.</p> |
|
|
233 | <p>Please note that epoll sometimes generates spurious notifications, so you |
|
|
234 | need to use non-blocking I/O or other means to avoid blocking when no data |
|
|
235 | (or space) is available.</p> |
|
|
236 | </dd> |
|
|
237 | <dt><code>EVBACKEND_KQUEUE</code> (value 8, most BSD clones)</dt> |
|
|
238 | <dd> |
|
|
239 | <p>Kqueue deserves special mention, as at the time of this writing, it |
|
|
240 | was broken on all BSDs except NetBSD (usually it doesn't work with |
|
|
241 | anything but sockets and pipes, except on Darwin, where of course its |
|
|
242 | completely useless). For this reason its not being "autodetected" |
|
|
243 | unless you explicitly specify it explicitly in the flags (i.e. using |
|
|
244 | <code>EVBACKEND_KQUEUE</code>).</p> |
|
|
245 | <p>It scales in the same way as the epoll backend, but the interface to the |
|
|
246 | kernel is more efficient (which says nothing about its actual speed, of |
|
|
247 | course). While starting and stopping an I/O watcher does not cause an |
|
|
248 | extra syscall as with epoll, it still adds up to four event changes per |
|
|
249 | incident, so its best to avoid that.</p> |
|
|
250 | </dd> |
|
|
251 | <dt><code>EVBACKEND_DEVPOLL</code> (value 16, Solaris 8)</dt> |
|
|
252 | <dd> |
|
|
253 | <p>This is not implemented yet (and might never be).</p> |
|
|
254 | </dd> |
|
|
255 | <dt><code>EVBACKEND_PORT</code> (value 32, Solaris 10)</dt> |
|
|
256 | <dd> |
|
|
257 | <p>This uses the Solaris 10 port mechanism. As with everything on Solaris, |
|
|
258 | it's really slow, but it still scales very well (O(active_fds)).</p> |
|
|
259 | <p>Please note that solaris ports can result in a lot of spurious |
|
|
260 | notifications, so you need to use non-blocking I/O or other means to avoid |
|
|
261 | blocking when no data (or space) is available.</p> |
|
|
262 | </dd> |
|
|
263 | <dt><code>EVBACKEND_ALL</code></dt> |
|
|
264 | <dd> |
|
|
265 | <p>Try all backends (even potentially broken ones that wouldn't be tried |
|
|
266 | with <code>EVFLAG_AUTO</code>). Since this is a mask, you can do stuff such as |
|
|
267 | <code>EVBACKEND_ALL & ~EVBACKEND_KQUEUE</code>.</p> |
190 | </dd> |
268 | </dd> |
191 | </dl> |
269 | </dl> |
192 | </p> |
270 | </p> |
|
|
271 | <p>If one or more of these are ored into the flags value, then only these |
|
|
272 | backends will be tried (in the reverse order as given here). If none are |
|
|
273 | specified, most compiled-in backend will be tried, usually in reverse |
|
|
274 | order of their flag values :)</p> |
|
|
275 | <p>The most typical usage is like this:</p> |
|
|
276 | <pre> if (!ev_default_loop (0)) |
|
|
277 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
|
|
278 | |
|
|
279 | </pre> |
|
|
280 | <p>Restrict libev to the select and poll backends, and do not allow |
|
|
281 | environment settings to be taken into account:</p> |
|
|
282 | <pre> ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
|
|
283 | |
|
|
284 | </pre> |
|
|
285 | <p>Use whatever libev has to offer, but make sure that kqueue is used if |
|
|
286 | available (warning, breaks stuff, best use only with your own private |
|
|
287 | event loop and only if you know the OS supports your types of fds):</p> |
|
|
288 | <pre> ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
289 | |
|
|
290 | </pre> |
193 | </dd> |
291 | </dd> |
194 | <dt>struct ev_loop *ev_loop_new (unsigned int flags)</dt> |
292 | <dt>struct ev_loop *ev_loop_new (unsigned int flags)</dt> |
195 | <dd> |
293 | <dd> |
196 | <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is |
294 | <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is |
197 | always distinct from the default loop. Unlike the default loop, it cannot |
295 | always distinct from the default loop. Unlike the default loop, it cannot |
… | |
… | |
200 | </dd> |
298 | </dd> |
201 | <dt>ev_default_destroy ()</dt> |
299 | <dt>ev_default_destroy ()</dt> |
202 | <dd> |
300 | <dd> |
203 | <p>Destroys the default loop again (frees all memory and kernel state |
301 | <p>Destroys the default loop again (frees all memory and kernel state |
204 | etc.). This stops all registered event watchers (by not touching them in |
302 | etc.). This stops all registered event watchers (by not touching them in |
205 | any way whatsoever, although you cnanot rely on this :).</p> |
303 | any way whatsoever, although you cannot rely on this :).</p> |
206 | </dd> |
304 | </dd> |
207 | <dt>ev_loop_destroy (loop)</dt> |
305 | <dt>ev_loop_destroy (loop)</dt> |
208 | <dd> |
306 | <dd> |
209 | <p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an |
307 | <p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an |
210 | earlier call to <code>ev_loop_new</code>.</p> |
308 | earlier call to <code>ev_loop_new</code>.</p> |
… | |
… | |
213 | <dd> |
311 | <dd> |
214 | <p>This function reinitialises the kernel state for backends that have |
312 | <p>This function reinitialises the kernel state for backends that have |
215 | one. Despite the name, you can call it anytime, but it makes most sense |
313 | one. Despite the name, you can call it anytime, but it makes most sense |
216 | after forking, in either the parent or child process (or both, but that |
314 | after forking, in either the parent or child process (or both, but that |
217 | again makes little sense).</p> |
315 | again makes little sense).</p> |
218 | <p>You <i>must</i> call this function after forking if and only if you want to |
316 | <p>You <i>must</i> call this function in the child process after forking if and |
219 | use the event library in both processes. If you just fork+exec, you don't |
317 | only if you want to use the event library in both processes. If you just |
220 | have to call it.</p> |
318 | fork+exec, you don't have to call it.</p> |
221 | <p>The function itself is quite fast and its usually not a problem to call |
319 | <p>The function itself is quite fast and it's usually not a problem to call |
222 | it just in case after a fork. To make this easy, the function will fit in |
320 | it just in case after a fork. To make this easy, the function will fit in |
223 | quite nicely into a call to <code>pthread_atfork</code>:</p> |
321 | quite nicely into a call to <code>pthread_atfork</code>:</p> |
224 | <pre> pthread_atfork (0, 0, ev_default_fork); |
322 | <pre> pthread_atfork (0, 0, ev_default_fork); |
225 | |
323 | |
226 | </pre> |
324 | </pre> |
|
|
325 | <p>At the moment, <code>EVBACKEND_SELECT</code> and <code>EVBACKEND_POLL</code> are safe to use |
|
|
326 | without calling this function, so if you force one of those backends you |
|
|
327 | do not need to care.</p> |
227 | </dd> |
328 | </dd> |
228 | <dt>ev_loop_fork (loop)</dt> |
329 | <dt>ev_loop_fork (loop)</dt> |
229 | <dd> |
330 | <dd> |
230 | <p>Like <code>ev_default_fork</code>, but acts on an event loop created by |
331 | <p>Like <code>ev_default_fork</code>, but acts on an event loop created by |
231 | <code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop |
332 | <code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop |
232 | after fork, and how you do this is entirely your own problem.</p> |
333 | after fork, and how you do this is entirely your own problem.</p> |
233 | </dd> |
334 | </dd> |
234 | <dt>unsigned int ev_method (loop)</dt> |
335 | <dt>unsigned int ev_backend (loop)</dt> |
235 | <dd> |
336 | <dd> |
236 | <p>Returns one of the <code>EVMETHOD_*</code> flags indicating the event backend in |
337 | <p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in |
237 | use.</p> |
338 | use.</p> |
238 | </dd> |
339 | </dd> |
239 | <dt>ev_tstamp = ev_now (loop)</dt> |
340 | <dt>ev_tstamp ev_now (loop)</dt> |
240 | <dd> |
341 | <dd> |
241 | <p>Returns the current "event loop time", which is the time the event loop |
342 | <p>Returns the current "event loop time", which is the time the event loop |
242 | got events and started processing them. This timestamp does not change |
343 | got events and started processing them. This timestamp does not change |
243 | as long as callbacks are being processed, and this is also the base time |
344 | as long as callbacks are being processed, and this is also the base time |
244 | used for relative timers. You can treat it as the timestamp of the event |
345 | used for relative timers. You can treat it as the timestamp of the event |
… | |
… | |
247 | <dt>ev_loop (loop, int flags)</dt> |
348 | <dt>ev_loop (loop, int flags)</dt> |
248 | <dd> |
349 | <dd> |
249 | <p>Finally, this is it, the event handler. This function usually is called |
350 | <p>Finally, this is it, the event handler. This function usually is called |
250 | after you initialised all your watchers and you want to start handling |
351 | after you initialised all your watchers and you want to start handling |
251 | events.</p> |
352 | events.</p> |
252 | <p>If the flags argument is specified as 0, it will not return until either |
353 | <p>If the flags argument is specified as <code>0</code>, it will not return until |
253 | no event watchers are active anymore or <code>ev_unloop</code> was called.</p> |
354 | either no event watchers are active anymore or <code>ev_unloop</code> was called.</p> |
254 | <p>A flags value of <code>EVLOOP_NONBLOCK</code> will look for new events, will handle |
355 | <p>A flags value of <code>EVLOOP_NONBLOCK</code> will look for new events, will handle |
255 | those events and any outstanding ones, but will not block your process in |
356 | those events and any outstanding ones, but will not block your process in |
256 | case there are no events.</p> |
357 | case there are no events and will return after one iteration of the loop.</p> |
257 | <p>A flags value of <code>EVLOOP_ONESHOT</code> will look for new events (waiting if |
358 | <p>A flags value of <code>EVLOOP_ONESHOT</code> will look for new events (waiting if |
258 | neccessary) and will handle those and any outstanding ones. It will block |
359 | neccessary) and will handle those and any outstanding ones. It will block |
259 | your process until at least one new event arrives.</p> |
360 | your process until at least one new event arrives, and will return after |
260 | <p>This flags value could be used to implement alternative looping |
361 | one iteration of the loop. This is useful if you are waiting for some |
261 | constructs, but the <code>prepare</code> and <code>check</code> watchers provide a better and |
362 | external event in conjunction with something not expressible using other |
262 | more generic mechanism.</p> |
363 | libev watchers. However, a pair of <code>ev_prepare</code>/<code>ev_check</code> watchers is |
|
|
364 | usually a better approach for this kind of thing.</p> |
|
|
365 | <p>Here are the gory details of what <code>ev_loop</code> does:</p> |
|
|
366 | <pre> * If there are no active watchers (reference count is zero), return. |
|
|
367 | - Queue prepare watchers and then call all outstanding watchers. |
|
|
368 | - If we have been forked, recreate the kernel state. |
|
|
369 | - Update the kernel state with all outstanding changes. |
|
|
370 | - Update the "event loop time". |
|
|
371 | - Calculate for how long to block. |
|
|
372 | - Block the process, waiting for any events. |
|
|
373 | - Queue all outstanding I/O (fd) events. |
|
|
374 | - Update the "event loop time" and do time jump handling. |
|
|
375 | - Queue all outstanding timers. |
|
|
376 | - Queue all outstanding periodics. |
|
|
377 | - If no events are pending now, queue all idle watchers. |
|
|
378 | - Queue all check watchers. |
|
|
379 | - Call all queued watchers in reverse order (i.e. check watchers first). |
|
|
380 | Signals and child watchers are implemented as I/O watchers, and will |
|
|
381 | be handled here by queueing them when their watcher gets executed. |
|
|
382 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
|
|
383 | were used, return, otherwise continue with step *. |
|
|
384 | |
|
|
385 | </pre> |
263 | </dd> |
386 | </dd> |
264 | <dt>ev_unloop (loop, how)</dt> |
387 | <dt>ev_unloop (loop, how)</dt> |
265 | <dd> |
388 | <dd> |
266 | <p>Can be used to make a call to <code>ev_loop</code> return early. The <code>how</code> argument |
389 | <p>Can be used to make a call to <code>ev_loop</code> return early (but only after it |
|
|
390 | has processed all outstanding events). The <code>how</code> argument must be either |
267 | must be either <code>EVUNLOOP_ONCE</code>, which will make the innermost <code>ev_loop</code> |
391 | <code>EVUNLOOP_ONE</code>, which will make the innermost <code>ev_loop</code> call return, or |
268 | call return, or <code>EVUNLOOP_ALL</code>, which will make all nested <code>ev_loop</code> |
392 | <code>EVUNLOOP_ALL</code>, which will make all nested <code>ev_loop</code> calls return.</p> |
269 | calls return.</p> |
|
|
270 | </dd> |
393 | </dd> |
271 | <dt>ev_ref (loop)</dt> |
394 | <dt>ev_ref (loop)</dt> |
272 | <dt>ev_unref (loop)</dt> |
395 | <dt>ev_unref (loop)</dt> |
273 | <dd> |
396 | <dd> |
274 | <p>Ref/unref can be used to add or remove a refcount on the event loop: Every |
397 | <p>Ref/unref can be used to add or remove a reference count on the event |
275 | watcher keeps one reference. If you have a long-runing watcher you never |
398 | loop: Every watcher keeps one reference, and as long as the reference |
276 | unregister that should not keep ev_loop from running, ev_unref() after |
399 | count is nonzero, <code>ev_loop</code> will not return on its own. If you have |
277 | starting, and ev_ref() before stopping it. Libev itself uses this for |
400 | a watcher you never unregister that should not keep <code>ev_loop</code> from |
278 | example for its internal signal pipe: It is not visible to you as a user |
401 | returning, ev_unref() after starting, and ev_ref() before stopping it. For |
279 | and should not keep <code>ev_loop</code> from exiting if the work is done. It is |
402 | example, libev itself uses this for its internal signal pipe: It is not |
280 | also an excellent way to do this for generic recurring timers or from |
403 | visible to the libev user and should not keep <code>ev_loop</code> from exiting if |
281 | within third-party libraries. Just remember to unref after start and ref |
404 | no event watchers registered by it are active. It is also an excellent |
282 | before stop.</p> |
405 | way to do this for generic recurring timers or from within third-party |
|
|
406 | libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p> |
283 | </dd> |
407 | </dd> |
284 | </dl> |
408 | </dl> |
285 | |
409 | |
286 | </div> |
410 | </div> |
287 | <h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p> |
411 | <h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p> |
288 | <div id="ANATOMY_OF_A_WATCHER_CONTENT"> |
412 | <div id="ANATOMY_OF_A_WATCHER_CONTENT"> |
289 | <p>A watcher is a structure that you create and register to record your |
413 | <p>A watcher is a structure that you create and register to record your |
290 | interest in some event. For instance, if you want to wait for STDIN to |
414 | interest in some event. For instance, if you want to wait for STDIN to |
291 | become readable, you would create an ev_io watcher for that:</p> |
415 | become readable, you would create an <code>ev_io</code> watcher for that:</p> |
292 | <pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
416 | <pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
293 | { |
417 | { |
294 | ev_io_stop (w); |
418 | ev_io_stop (w); |
295 | ev_unloop (loop, EVUNLOOP_ALL); |
419 | ev_unloop (loop, EVUNLOOP_ALL); |
296 | } |
420 | } |
… | |
… | |
319 | with a watcher-specific start function (<code>ev_<type>_start (loop, watcher |
443 | with a watcher-specific start function (<code>ev_<type>_start (loop, watcher |
320 | *)</code>), and you can stop watching for events at any time by calling the |
444 | *)</code>), and you can stop watching for events at any time by calling the |
321 | corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p> |
445 | corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p> |
322 | <p>As long as your watcher is active (has been started but not stopped) you |
446 | <p>As long as your watcher is active (has been started but not stopped) you |
323 | must not touch the values stored in it. Most specifically you must never |
447 | must not touch the values stored in it. Most specifically you must never |
324 | reinitialise it or call its set method.</p> |
448 | reinitialise it or call its set macro.</p> |
325 | <p>You cna check whether an event is active by calling the <code>ev_is_active |
449 | <p>You can check whether an event is active by calling the <code>ev_is_active |
326 | (watcher *)</code> macro. To see whether an event is outstanding (but the |
450 | (watcher *)</code> macro. To see whether an event is outstanding (but the |
327 | callback for it has not been called yet) you cna use the <code>ev_is_pending |
451 | callback for it has not been called yet) you can use the <code>ev_is_pending |
328 | (watcher *)</code> macro.</p> |
452 | (watcher *)</code> macro.</p> |
329 | <p>Each and every callback receives the event loop pointer as first, the |
453 | <p>Each and every callback receives the event loop pointer as first, the |
330 | registered watcher structure as second, and a bitset of received events as |
454 | registered watcher structure as second, and a bitset of received events as |
331 | third argument.</p> |
455 | third argument.</p> |
332 | <p>The rceeived events usually include a single bit per event type received |
456 | <p>The received events usually include a single bit per event type received |
333 | (you can receive multiple events at the same time). The possible bit masks |
457 | (you can receive multiple events at the same time). The possible bit masks |
334 | are:</p> |
458 | are:</p> |
335 | <dl> |
459 | <dl> |
336 | <dt>EV_READ</dt> |
460 | <dt><code>EV_READ</code></dt> |
337 | <dt>EV_WRITE</dt> |
461 | <dt><code>EV_WRITE</code></dt> |
338 | <dd> |
462 | <dd> |
339 | <p>The file descriptor in the ev_io watcher has become readable and/or |
463 | <p>The file descriptor in the <code>ev_io</code> watcher has become readable and/or |
340 | writable.</p> |
464 | writable.</p> |
341 | </dd> |
465 | </dd> |
342 | <dt>EV_TIMEOUT</dt> |
466 | <dt><code>EV_TIMEOUT</code></dt> |
343 | <dd> |
|
|
344 | <p>The ev_timer watcher has timed out.</p> |
|
|
345 | </dd> |
467 | <dd> |
346 | <dt>EV_PERIODIC</dt> |
468 | <p>The <code>ev_timer</code> watcher has timed out.</p> |
347 | <dd> |
469 | </dd> |
348 | <p>The ev_periodic watcher has timed out.</p> |
470 | <dt><code>EV_PERIODIC</code></dt> |
349 | </dd> |
471 | <dd> |
350 | <dt>EV_SIGNAL</dt> |
472 | <p>The <code>ev_periodic</code> watcher has timed out.</p> |
351 | <dd> |
473 | </dd> |
|
|
474 | <dt><code>EV_SIGNAL</code></dt> |
|
|
475 | <dd> |
352 | <p>The signal specified in the ev_signal watcher has been received by a thread.</p> |
476 | <p>The signal specified in the <code>ev_signal</code> watcher has been received by a thread.</p> |
353 | </dd> |
|
|
354 | <dt>EV_CHILD</dt> |
|
|
355 | <dd> |
477 | </dd> |
|
|
478 | <dt><code>EV_CHILD</code></dt> |
|
|
479 | <dd> |
356 | <p>The pid specified in the ev_child watcher has received a status change.</p> |
480 | <p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p> |
357 | </dd> |
|
|
358 | <dt>EV_IDLE</dt> |
|
|
359 | <dd> |
481 | </dd> |
|
|
482 | <dt><code>EV_IDLE</code></dt> |
|
|
483 | <dd> |
360 | <p>The ev_idle watcher has determined that you have nothing better to do.</p> |
484 | <p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p> |
361 | </dd> |
|
|
362 | <dt>EV_PREPARE</dt> |
|
|
363 | <dt>EV_CHECK</dt> |
|
|
364 | <dd> |
485 | </dd> |
|
|
486 | <dt><code>EV_PREPARE</code></dt> |
|
|
487 | <dt><code>EV_CHECK</code></dt> |
|
|
488 | <dd> |
365 | <p>All ev_prepare watchers are invoked just <i>before</i> <code>ev_loop</code> starts |
489 | <p>All <code>ev_prepare</code> watchers are invoked just <i>before</i> <code>ev_loop</code> starts |
366 | to gather new events, and all ev_check watchers are invoked just after |
490 | to gather new events, and all <code>ev_check</code> watchers are invoked just after |
367 | <code>ev_loop</code> has gathered them, but before it invokes any callbacks for any |
491 | <code>ev_loop</code> has gathered them, but before it invokes any callbacks for any |
368 | received events. Callbacks of both watcher types can start and stop as |
492 | received events. Callbacks of both watcher types can start and stop as |
369 | many watchers as they want, and all of them will be taken into account |
493 | many watchers as they want, and all of them will be taken into account |
370 | (for example, a ev_prepare watcher might start an idle watcher to keep |
494 | (for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep |
371 | <code>ev_loop</code> from blocking).</p> |
495 | <code>ev_loop</code> from blocking).</p> |
372 | </dd> |
496 | </dd> |
373 | <dt>EV_ERROR</dt> |
497 | <dt><code>EV_ERROR</code></dt> |
374 | <dd> |
498 | <dd> |
375 | <p>An unspecified error has occured, the watcher has been stopped. This might |
499 | <p>An unspecified error has occured, the watcher has been stopped. This might |
376 | happen because the watcher could not be properly started because libev |
500 | happen because the watcher could not be properly started because libev |
377 | ran out of memory, a file descriptor was found to be closed or any other |
501 | ran out of memory, a file descriptor was found to be closed or any other |
378 | problem. You best act on it by reporting the problem and somehow coping |
502 | problem. You best act on it by reporting the problem and somehow coping |
… | |
… | |
387 | |
511 | |
388 | </div> |
512 | </div> |
389 | <h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2> |
513 | <h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2> |
390 | <div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2"> |
514 | <div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2"> |
391 | <p>Each watcher has, by default, a member <code>void *data</code> that you can change |
515 | <p>Each watcher has, by default, a member <code>void *data</code> that you can change |
392 | and read at any time, libev will completely ignore it. This cna be used |
516 | and read at any time, libev will completely ignore it. This can be used |
393 | to associate arbitrary data with your watcher. If you need more data and |
517 | to associate arbitrary data with your watcher. If you need more data and |
394 | don't want to allocate memory and store a pointer to it in that data |
518 | don't want to allocate memory and store a pointer to it in that data |
395 | member, you can also "subclass" the watcher type and provide your own |
519 | member, you can also "subclass" the watcher type and provide your own |
396 | data:</p> |
520 | data:</p> |
397 | <pre> struct my_io |
521 | <pre> struct my_io |
… | |
… | |
424 | <div id="WATCHER_TYPES_CONTENT"> |
548 | <div id="WATCHER_TYPES_CONTENT"> |
425 | <p>This section describes each watcher in detail, but will not repeat |
549 | <p>This section describes each watcher in detail, but will not repeat |
426 | information given in the last section.</p> |
550 | information given in the last section.</p> |
427 | |
551 | |
428 | </div> |
552 | </div> |
429 | <h2 id="struct_ev_io_is_my_file_descriptor_r">struct ev_io - is my file descriptor readable or writable</h2> |
553 | <h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</h2> |
430 | <div id="struct_ev_io_is_my_file_descriptor_r-2"> |
554 | <div id="code_ev_io_code_is_this_file_descrip-2"> |
431 | <p>I/O watchers check whether a file descriptor is readable or writable |
555 | <p>I/O watchers check whether a file descriptor is readable or writable |
432 | in each iteration of the event loop (This behaviour is called |
556 | in each iteration of the event loop (This behaviour is called |
433 | level-triggering because you keep receiving events as long as the |
557 | level-triggering because you keep receiving events as long as the |
434 | condition persists. Remember you cna stop the watcher if you don't want to |
558 | condition persists. Remember you can stop the watcher if you don't want to |
435 | act on the event and neither want to receive future events).</p> |
559 | act on the event and neither want to receive future events).</p> |
436 | <p>In general you can register as many read and/or write event watchers oer |
560 | <p>In general you can register as many read and/or write event watchers per |
437 | fd as you want (as long as you don't confuse yourself). Setting all file |
561 | fd as you want (as long as you don't confuse yourself). Setting all file |
438 | descriptors to non-blocking mode is also usually a good idea (but not |
562 | descriptors to non-blocking mode is also usually a good idea (but not |
439 | required if you know what you are doing).</p> |
563 | required if you know what you are doing).</p> |
440 | <p>You have to be careful with dup'ed file descriptors, though. Some backends |
564 | <p>You have to be careful with dup'ed file descriptors, though. Some backends |
441 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
565 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
442 | descriptors correctly if you register interest in two or more fds pointing |
566 | descriptors correctly if you register interest in two or more fds pointing |
443 | to the same file/socket etc. description.</p> |
567 | to the same underlying file/socket etc. description (that is, they share |
|
|
568 | the same underlying "file open").</p> |
444 | <p>If you must do this, then force the use of a known-to-be-good backend |
569 | <p>If you must do this, then force the use of a known-to-be-good backend |
445 | (at the time of this writing, this includes only EVMETHOD_SELECT and |
570 | (at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and |
446 | EVMETHOD_POLL).</p> |
571 | <code>EVBACKEND_POLL</code>).</p> |
447 | <dl> |
572 | <dl> |
448 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
573 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
449 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
574 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
450 | <dd> |
575 | <dd> |
451 | <p>Configures an ev_io watcher. The fd is the file descriptor to rceeive |
576 | <p>Configures an <code>ev_io</code> watcher. The fd is the file descriptor to rceeive |
452 | events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_READ | |
577 | events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_READ | |
453 | EV_WRITE</code> to receive the given events.</p> |
578 | EV_WRITE</code> to receive the given events.</p> |
|
|
579 | <p>Please note that most of the more scalable backend mechanisms (for example |
|
|
580 | epoll and solaris ports) can result in spurious readyness notifications |
|
|
581 | for file descriptors, so you practically need to use non-blocking I/O (and |
|
|
582 | treat callback invocation as hint only), or retest separately with a safe |
|
|
583 | interface before doing I/O (XLib can do this), or force the use of either |
|
|
584 | <code>EVBACKEND_SELECT</code> or <code>EVBACKEND_POLL</code>, which don't suffer from this |
|
|
585 | problem. Also note that it is quite easy to have your callback invoked |
|
|
586 | when the readyness condition is no longer valid even when employing |
|
|
587 | typical ways of handling events, so its a good idea to use non-blocking |
|
|
588 | I/O unconditionally.</p> |
454 | </dd> |
589 | </dd> |
455 | </dl> |
590 | </dl> |
456 | |
591 | |
457 | </div> |
592 | </div> |
458 | <h2 id="struct_ev_timer_relative_and_optiona">struct ev_timer - relative and optionally recurring timeouts</h2> |
593 | <h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</h2> |
459 | <div id="struct_ev_timer_relative_and_optiona-2"> |
594 | <div id="code_ev_timer_code_relative_and_opti-2"> |
460 | <p>Timer watchers are simple relative timers that generate an event after a |
595 | <p>Timer watchers are simple relative timers that generate an event after a |
461 | given time, and optionally repeating in regular intervals after that.</p> |
596 | given time, and optionally repeating in regular intervals after that.</p> |
462 | <p>The timers are based on real time, that is, if you register an event that |
597 | <p>The timers are based on real time, that is, if you register an event that |
463 | times out after an hour and youreset your system clock to last years |
598 | times out after an hour and you reset your system clock to last years |
464 | time, it will still time out after (roughly) and hour. "Roughly" because |
599 | time, it will still time out after (roughly) and hour. "Roughly" because |
465 | detecting time jumps is hard, and soem inaccuracies are unavoidable (the |
600 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
466 | monotonic clock option helps a lot here).</p> |
601 | monotonic clock option helps a lot here).</p> |
|
|
602 | <p>The relative timeouts are calculated relative to the <code>ev_now ()</code> |
|
|
603 | time. This is usually the right thing as this timestamp refers to the time |
|
|
604 | of the event triggering whatever timeout you are modifying/starting. If |
|
|
605 | you suspect event processing to be delayed and you <i>need</i> to base the timeout |
|
|
606 | on the current time, use something like this to adjust for this:</p> |
|
|
607 | <pre> ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
|
|
608 | |
|
|
609 | </pre> |
|
|
610 | <p>The callback is guarenteed to be invoked only when its timeout has passed, |
|
|
611 | but if multiple timers become ready during the same loop iteration then |
|
|
612 | order of execution is undefined.</p> |
467 | <dl> |
613 | <dl> |
468 | <dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt> |
614 | <dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt> |
469 | <dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt> |
615 | <dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt> |
470 | <dd> |
616 | <dd> |
471 | <p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is |
617 | <p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is |
… | |
… | |
473 | timer will automatically be configured to trigger again <code>repeat</code> seconds |
619 | timer will automatically be configured to trigger again <code>repeat</code> seconds |
474 | later, again, and again, until stopped manually.</p> |
620 | later, again, and again, until stopped manually.</p> |
475 | <p>The timer itself will do a best-effort at avoiding drift, that is, if you |
621 | <p>The timer itself will do a best-effort at avoiding drift, that is, if you |
476 | configure a timer to trigger every 10 seconds, then it will trigger at |
622 | configure a timer to trigger every 10 seconds, then it will trigger at |
477 | exactly 10 second intervals. If, however, your program cannot keep up with |
623 | exactly 10 second intervals. If, however, your program cannot keep up with |
478 | the timer (ecause it takes longer than those 10 seconds to do stuff) the |
624 | the timer (because it takes longer than those 10 seconds to do stuff) the |
479 | timer will not fire more than once per event loop iteration.</p> |
625 | timer will not fire more than once per event loop iteration.</p> |
480 | </dd> |
626 | </dd> |
481 | <dt>ev_timer_again (loop)</dt> |
627 | <dt>ev_timer_again (loop)</dt> |
482 | <dd> |
628 | <dd> |
483 | <p>This will act as if the timer timed out and restart it again if it is |
629 | <p>This will act as if the timer timed out and restart it again if it is |
… | |
… | |
487 | value), or reset the running timer to the repeat value.</p> |
633 | value), or reset the running timer to the repeat value.</p> |
488 | <p>This sounds a bit complicated, but here is a useful and typical |
634 | <p>This sounds a bit complicated, but here is a useful and typical |
489 | example: Imagine you have a tcp connection and you want a so-called idle |
635 | example: Imagine you have a tcp connection and you want a so-called idle |
490 | timeout, that is, you want to be called when there have been, say, 60 |
636 | timeout, that is, you want to be called when there have been, say, 60 |
491 | seconds of inactivity on the socket. The easiest way to do this is to |
637 | seconds of inactivity on the socket. The easiest way to do this is to |
492 | configure an ev_timer with after=repeat=60 and calling ev_timer_again each |
638 | configure an <code>ev_timer</code> with after=repeat=60 and calling ev_timer_again each |
493 | time you successfully read or write some data. If you go into an idle |
639 | time you successfully read or write some data. If you go into an idle |
494 | state where you do not expect data to travel on the socket, you can stop |
640 | state where you do not expect data to travel on the socket, you can stop |
495 | the timer, and again will automatically restart it if need be.</p> |
641 | the timer, and again will automatically restart it if need be.</p> |
496 | </dd> |
642 | </dd> |
497 | </dl> |
643 | </dl> |
498 | |
644 | |
499 | </div> |
645 | </div> |
500 | <h2 id="ev_periodic_to_cron_or_not_to_cron_i">ev_periodic - to cron or not to cron it</h2> |
646 | <h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</h2> |
501 | <div id="ev_periodic_to_cron_or_not_to_cron_i-2"> |
647 | <div id="code_ev_periodic_code_to_cron_or_not-2"> |
502 | <p>Periodic watchers are also timers of a kind, but they are very versatile |
648 | <p>Periodic watchers are also timers of a kind, but they are very versatile |
503 | (and unfortunately a bit complex).</p> |
649 | (and unfortunately a bit complex).</p> |
504 | <p>Unlike ev_timer's, they are not based on real time (or relative time) |
650 | <p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time) |
505 | but on wallclock time (absolute time). You can tell a periodic watcher |
651 | but on wallclock time (absolute time). You can tell a periodic watcher |
506 | to trigger "at" some specific point in time. For example, if you tell a |
652 | to trigger "at" some specific point in time. For example, if you tell a |
507 | periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now () |
653 | periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now () |
508 | + 10.>) and then reset your system clock to the last year, then it will |
654 | + 10.>) and then reset your system clock to the last year, then it will |
509 | take a year to trigger the event (unlike an ev_timer, which would trigger |
655 | take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger |
510 | roughly 10 seconds later and of course not if you reset your system time |
656 | roughly 10 seconds later and of course not if you reset your system time |
511 | again).</p> |
657 | again).</p> |
512 | <p>They can also be used to implement vastly more complex timers, such as |
658 | <p>They can also be used to implement vastly more complex timers, such as |
513 | triggering an event on eahc midnight, local time.</p> |
659 | triggering an event on eahc midnight, local time.</p> |
|
|
660 | <p>As with timers, the callback is guarenteed to be invoked only when the |
|
|
661 | time (<code>at</code>) has been passed, but if multiple periodic timers become ready |
|
|
662 | during the same loop iteration then order of execution is undefined.</p> |
514 | <dl> |
663 | <dl> |
515 | <dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt> |
664 | <dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt> |
516 | <dt>ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)</dt> |
665 | <dt>ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)</dt> |
517 | <dd> |
666 | <dd> |
518 | <p>Lots of arguments, lets sort it out... There are basically three modes of |
667 | <p>Lots of arguments, lets sort it out... There are basically three modes of |
519 | operation, and we will explain them from simplest to complex:</p> |
668 | operation, and we will explain them from simplest to complex:</p> |
520 | |
|
|
521 | |
|
|
522 | |
|
|
523 | |
|
|
524 | <p> |
669 | <p> |
525 | <dl> |
670 | <dl> |
526 | <dt>* absolute timer (interval = reschedule_cb = 0)</dt> |
671 | <dt>* absolute timer (interval = reschedule_cb = 0)</dt> |
527 | <dd> |
672 | <dd> |
528 | <p>In this configuration the watcher triggers an event at the wallclock time |
673 | <p>In this configuration the watcher triggers an event at the wallclock time |
… | |
… | |
540 | <pre> ev_periodic_set (&periodic, 0., 3600., 0); |
685 | <pre> ev_periodic_set (&periodic, 0., 3600., 0); |
541 | |
686 | |
542 | </pre> |
687 | </pre> |
543 | <p>This doesn't mean there will always be 3600 seconds in between triggers, |
688 | <p>This doesn't mean there will always be 3600 seconds in between triggers, |
544 | but only that the the callback will be called when the system time shows a |
689 | but only that the the callback will be called when the system time shows a |
545 | full hour (UTC), or more correct, when the system time is evenly divisible |
690 | full hour (UTC), or more correctly, when the system time is evenly divisible |
546 | by 3600.</p> |
691 | by 3600.</p> |
547 | <p>Another way to think about it (for the mathematically inclined) is that |
692 | <p>Another way to think about it (for the mathematically inclined) is that |
548 | ev_periodic will try to run the callback in this mode at the next possible |
693 | <code>ev_periodic</code> will try to run the callback in this mode at the next possible |
549 | time where <code>time = at (mod interval)</code>, regardless of any time jumps.</p> |
694 | time where <code>time = at (mod interval)</code>, regardless of any time jumps.</p> |
550 | </dd> |
695 | </dd> |
551 | <dt>* manual reschedule mode (reschedule_cb = callback)</dt> |
696 | <dt>* manual reschedule mode (reschedule_cb = callback)</dt> |
552 | <dd> |
697 | <dd> |
553 | <p>In this mode the values for <code>interval</code> and <code>at</code> are both being |
698 | <p>In this mode the values for <code>interval</code> and <code>at</code> are both being |
554 | ignored. Instead, each time the periodic watcher gets scheduled, the |
699 | ignored. Instead, each time the periodic watcher gets scheduled, the |
555 | reschedule callback will be called with the watcher as first, and the |
700 | reschedule callback will be called with the watcher as first, and the |
556 | current time as second argument.</p> |
701 | current time as second argument.</p> |
557 | <p>NOTE: <i>This callback MUST NOT stop or destroy the periodic or any other |
702 | <p>NOTE: <i>This callback MUST NOT stop or destroy any periodic watcher, |
558 | periodic watcher, ever, or make any event loop modificstions</i>. If you need |
703 | ever, or make any event loop modifications</i>. If you need to stop it, |
559 | to stop it, return 1e30 (or so, fudge fudge) and stop it afterwards.</p> |
704 | return <code>now + 1e30</code> (or so, fudge fudge) and stop it afterwards (e.g. by |
|
|
705 | starting a prepare watcher).</p> |
560 | <p>Its prototype is c<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
706 | <p>Its prototype is <code>ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
561 | ev_tstamp now)>, e.g.:</p> |
707 | ev_tstamp now)</code>, e.g.:</p> |
562 | <pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
708 | <pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
563 | { |
709 | { |
564 | return now + 60.; |
710 | return now + 60.; |
565 | } |
711 | } |
566 | |
712 | |
567 | </pre> |
713 | </pre> |
568 | <p>It must return the next time to trigger, based on the passed time value |
714 | <p>It must return the next time to trigger, based on the passed time value |
569 | (that is, the lowest time value larger than to the second argument). It |
715 | (that is, the lowest time value larger than to the second argument). It |
570 | will usually be called just before the callback will be triggered, but |
716 | will usually be called just before the callback will be triggered, but |
571 | might be called at other times, too.</p> |
717 | might be called at other times, too.</p> |
|
|
718 | <p>NOTE: <i>This callback must always return a time that is later than the |
|
|
719 | passed <code>now</code> value</i>. Not even <code>now</code> itself will do, it <i>must</i> be larger.</p> |
572 | <p>This can be used to create very complex timers, such as a timer that |
720 | <p>This can be used to create very complex timers, such as a timer that |
573 | triggers on each midnight, local time. To do this, you would calculate the |
721 | triggers on each midnight, local time. To do this, you would calculate the |
574 | next midnight after <code>now</code> and return the timestamp value for this. How you do this |
722 | next midnight after <code>now</code> and return the timestamp value for this. How |
575 | is, again, up to you (but it is not trivial).</p> |
723 | you do this is, again, up to you (but it is not trivial, which is the main |
|
|
724 | reason I omitted it as an example).</p> |
576 | </dd> |
725 | </dd> |
577 | </dl> |
726 | </dl> |
578 | </p> |
727 | </p> |
579 | </dd> |
728 | </dd> |
580 | <dt>ev_periodic_again (loop, ev_periodic *)</dt> |
729 | <dt>ev_periodic_again (loop, ev_periodic *)</dt> |
… | |
… | |
585 | program when the crontabs have changed).</p> |
734 | program when the crontabs have changed).</p> |
586 | </dd> |
735 | </dd> |
587 | </dl> |
736 | </dl> |
588 | |
737 | |
589 | </div> |
738 | </div> |
590 | <h2 id="ev_signal_signal_me_when_a_signal_ge">ev_signal - signal me when a signal gets signalled</h2> |
739 | <h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</h2> |
591 | <div id="ev_signal_signal_me_when_a_signal_ge-2"> |
740 | <div id="code_ev_signal_code_signal_me_when_a-2"> |
592 | <p>Signal watchers will trigger an event when the process receives a specific |
741 | <p>Signal watchers will trigger an event when the process receives a specific |
593 | signal one or more times. Even though signals are very asynchronous, libev |
742 | signal one or more times. Even though signals are very asynchronous, libev |
594 | will try its best to deliver signals synchronously, i.e. as part of the |
743 | will try it's best to deliver signals synchronously, i.e. as part of the |
595 | normal event processing, like any other event.</p> |
744 | normal event processing, like any other event.</p> |
596 | <p>You cna configure as many watchers as you like per signal. Only when the |
745 | <p>You can configure as many watchers as you like per signal. Only when the |
597 | first watcher gets started will libev actually register a signal watcher |
746 | first watcher gets started will libev actually register a signal watcher |
598 | with the kernel (thus it coexists with your own signal handlers as long |
747 | with the kernel (thus it coexists with your own signal handlers as long |
599 | as you don't register any with libev). Similarly, when the last signal |
748 | as you don't register any with libev). Similarly, when the last signal |
600 | watcher for a signal is stopped libev will reset the signal handler to |
749 | watcher for a signal is stopped libev will reset the signal handler to |
601 | SIG_DFL (regardless of what it was set to before).</p> |
750 | SIG_DFL (regardless of what it was set to before).</p> |
… | |
… | |
607 | of the <code>SIGxxx</code> constants).</p> |
756 | of the <code>SIGxxx</code> constants).</p> |
608 | </dd> |
757 | </dd> |
609 | </dl> |
758 | </dl> |
610 | |
759 | |
611 | </div> |
760 | </div> |
612 | <h2 id="ev_child_wait_for_pid_status_changes">ev_child - wait for pid status changes</h2> |
761 | <h2 id="code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</h2> |
613 | <div id="ev_child_wait_for_pid_status_changes-2"> |
762 | <div id="code_ev_child_code_wait_for_pid_stat-2"> |
614 | <p>Child watchers trigger when your process receives a SIGCHLD in response to |
763 | <p>Child watchers trigger when your process receives a SIGCHLD in response to |
615 | some child status changes (most typically when a child of yours dies).</p> |
764 | some child status changes (most typically when a child of yours dies).</p> |
616 | <dl> |
765 | <dl> |
617 | <dt>ev_child_init (ev_child *, callback, int pid)</dt> |
766 | <dt>ev_child_init (ev_child *, callback, int pid)</dt> |
618 | <dt>ev_child_set (ev_child *, int pid)</dt> |
767 | <dt>ev_child_set (ev_child *, int pid)</dt> |
619 | <dd> |
768 | <dd> |
620 | <p>Configures the watcher to wait for status changes of process <code>pid</code> (or |
769 | <p>Configures the watcher to wait for status changes of process <code>pid</code> (or |
621 | <i>any</i> process if <code>pid</code> is specified as <code>0</code>). The callback can look |
770 | <i>any</i> process if <code>pid</code> is specified as <code>0</code>). The callback can look |
622 | at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see |
771 | at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see |
623 | the status word (use the macros from <code>sys/wait.h</code>). The <code>rpid</code> member |
772 | the status word (use the macros from <code>sys/wait.h</code> and see your systems |
|
|
773 | <code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the |
624 | contains the pid of the process causing the status change.</p> |
774 | process causing the status change.</p> |
625 | </dd> |
775 | </dd> |
626 | </dl> |
776 | </dl> |
627 | |
777 | |
628 | </div> |
778 | </div> |
629 | <h2 id="ev_idle_when_you_ve_got_nothing_bett">ev_idle - when you've got nothing better to do</h2> |
779 | <h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</h2> |
630 | <div id="ev_idle_when_you_ve_got_nothing_bett-2"> |
780 | <div id="code_ev_idle_code_when_you_ve_got_no-2"> |
631 | <p>Idle watchers trigger events when there are no other I/O or timer (or |
781 | <p>Idle watchers trigger events when there are no other events are pending |
632 | periodic) events pending. That is, as long as your process is busy |
782 | (prepare, check and other idle watchers do not count). That is, as long |
633 | handling sockets or timeouts it will not be called. But when your process |
783 | as your process is busy handling sockets or timeouts (or even signals, |
634 | is idle all idle watchers are being called again and again - until |
784 | imagine) it will not be triggered. But when your process is idle all idle |
|
|
785 | watchers are being called again and again, once per event loop iteration - |
635 | stopped, that is, or your process receives more events.</p> |
786 | until stopped, that is, or your process receives more events and becomes |
|
|
787 | busy.</p> |
636 | <p>The most noteworthy effect is that as long as any idle watchers are |
788 | <p>The most noteworthy effect is that as long as any idle watchers are |
637 | active, the process will not block when waiting for new events.</p> |
789 | active, the process will not block when waiting for new events.</p> |
638 | <p>Apart from keeping your process non-blocking (which is a useful |
790 | <p>Apart from keeping your process non-blocking (which is a useful |
639 | effect on its own sometimes), idle watchers are a good place to do |
791 | effect on its own sometimes), idle watchers are a good place to do |
640 | "pseudo-background processing", or delay processing stuff to after the |
792 | "pseudo-background processing", or delay processing stuff to after the |
… | |
… | |
647 | believe me.</p> |
799 | believe me.</p> |
648 | </dd> |
800 | </dd> |
649 | </dl> |
801 | </dl> |
650 | |
802 | |
651 | </div> |
803 | </div> |
652 | <h2 id="prepare_and_check_your_hooks_into_th">prepare and check - your hooks into the event loop</h2> |
804 | <h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</h2> |
653 | <div id="prepare_and_check_your_hooks_into_th-2"> |
805 | <div id="code_ev_prepare_code_and_code_ev_che-2"> |
654 | <p>Prepare and check watchers usually (but not always) are used in |
806 | <p>Prepare and check watchers are usually (but not always) used in tandem: |
655 | tandom. Prepare watchers get invoked before the process blocks and check |
807 | prepare watchers get invoked before the process blocks and check watchers |
656 | watchers afterwards.</p> |
808 | afterwards.</p> |
657 | <p>Their main purpose is to integrate other event mechanisms into libev. This |
809 | <p>Their main purpose is to integrate other event mechanisms into libev. This |
658 | could be used, for example, to track variable changes, implement your own |
810 | could be used, for example, to track variable changes, implement your own |
659 | watchers, integrate net-snmp or a coroutine library and lots more.</p> |
811 | watchers, integrate net-snmp or a coroutine library and lots more.</p> |
660 | <p>This is done by examining in each prepare call which file descriptors need |
812 | <p>This is done by examining in each prepare call which file descriptors need |
661 | to be watched by the other library, registering ev_io watchers for them |
813 | to be watched by the other library, registering <code>ev_io</code> watchers for |
662 | and starting an ev_timer watcher for any timeouts (many libraries provide |
814 | them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries |
663 | just this functionality). Then, in the check watcher you check for any |
815 | provide just this functionality). Then, in the check watcher you check for |
664 | events that occured (by making your callbacks set soem flags for example) |
816 | any events that occured (by checking the pending status of all watchers |
665 | and call back into the library.</p> |
817 | and stopping them) and call back into the library. The I/O and timer |
|
|
818 | callbacks will never actually be called (but must be valid nevertheless, |
|
|
819 | because you never know, you know?).</p> |
666 | <p>As another example, the perl Coro module uses these hooks to integrate |
820 | <p>As another example, the Perl Coro module uses these hooks to integrate |
667 | coroutines into libev programs, by yielding to other active coroutines |
821 | coroutines into libev programs, by yielding to other active coroutines |
668 | during each prepare and only letting the process block if no coroutines |
822 | during each prepare and only letting the process block if no coroutines |
669 | are ready to run.</p> |
823 | are ready to run (it's actually more complicated: it only runs coroutines |
|
|
824 | with priority higher than or equal to the event loop and one coroutine |
|
|
825 | of lower priority, but only once, using idle watchers to keep the event |
|
|
826 | loop from blocking if lower-priority coroutines are active, thus mapping |
|
|
827 | low-priority coroutines to idle/background tasks).</p> |
670 | <dl> |
828 | <dl> |
671 | <dt>ev_prepare_init (ev_prepare *, callback)</dt> |
829 | <dt>ev_prepare_init (ev_prepare *, callback)</dt> |
672 | <dt>ev_check_init (ev_check *, callback)</dt> |
830 | <dt>ev_check_init (ev_check *, callback)</dt> |
673 | <dd> |
831 | <dd> |
674 | <p>Initialises and configures the prepare or check watcher - they have no |
832 | <p>Initialises and configures the prepare or check watcher - they have no |
675 | parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code> |
833 | parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code> |
676 | macros, but using them is utterly, utterly pointless.</p> |
834 | macros, but using them is utterly, utterly and completely pointless.</p> |
677 | </dd> |
835 | </dd> |
678 | </dl> |
836 | </dl> |
679 | |
837 | |
680 | </div> |
838 | </div> |
681 | <h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
839 | <h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
682 | <div id="OTHER_FUNCTIONS_CONTENT"> |
840 | <div id="OTHER_FUNCTIONS_CONTENT"> |
683 | <p>There are some other fucntions of possible interest. Described. Here. Now.</p> |
841 | <p>There are some other functions of possible interest. Described. Here. Now.</p> |
684 | <dl> |
842 | <dl> |
685 | <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> |
843 | <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> |
686 | <dd> |
844 | <dd> |
687 | <p>This function combines a simple timer and an I/O watcher, calls your |
845 | <p>This function combines a simple timer and an I/O watcher, calls your |
688 | callback on whichever event happens first and automatically stop both |
846 | callback on whichever event happens first and automatically stop both |
689 | watchers. This is useful if you want to wait for a single event on an fd |
847 | watchers. This is useful if you want to wait for a single event on an fd |
690 | or timeout without havign to allocate/configure/start/stop/free one or |
848 | or timeout without having to allocate/configure/start/stop/free one or |
691 | more watchers yourself.</p> |
849 | more watchers yourself.</p> |
692 | <p>If <code>fd</code> is less than 0, then no I/O watcher will be started and events is |
850 | <p>If <code>fd</code> is less than 0, then no I/O watcher will be started and events |
693 | ignored. Otherwise, an ev_io watcher for the given <code>fd</code> and <code>events</code> set |
851 | is being ignored. Otherwise, an <code>ev_io</code> watcher for the given <code>fd</code> and |
694 | will be craeted and started.</p> |
852 | <code>events</code> set will be craeted and started.</p> |
695 | <p>If <code>timeout</code> is less than 0, then no timeout watcher will be |
853 | <p>If <code>timeout</code> is less than 0, then no timeout watcher will be |
696 | started. Otherwise an ev_timer watcher with after = <code>timeout</code> (and repeat |
854 | started. Otherwise an <code>ev_timer</code> watcher with after = <code>timeout</code> (and |
697 | = 0) will be started.</p> |
855 | repeat = 0) will be started. While <code>0</code> is a valid timeout, it is of |
|
|
856 | dubious value.</p> |
698 | <p>The callback has the type <code>void (*cb)(int revents, void *arg)</code> and |
857 | <p>The callback has the type <code>void (*cb)(int revents, void *arg)</code> and gets |
699 | gets passed an events set (normally a combination of EV_ERROR, EV_READ, |
858 | passed an <code>revents</code> set like normal event callbacks (a combination of |
700 | EV_WRITE or EV_TIMEOUT) and the <code>arg</code> value passed to <code>ev_once</code>:</p> |
859 | <code>EV_ERROR</code>, <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_TIMEOUT</code>) and the <code>arg</code> |
|
|
860 | value passed to <code>ev_once</code>:</p> |
701 | <pre> static void stdin_ready (int revents, void *arg) |
861 | <pre> static void stdin_ready (int revents, void *arg) |
702 | { |
862 | { |
703 | if (revents & EV_TIMEOUT) |
863 | if (revents & EV_TIMEOUT) |
704 | /* doh, nothing entered */ |
864 | /* doh, nothing entered */; |
705 | else if (revents & EV_READ) |
865 | else if (revents & EV_READ) |
706 | /* stdin might have data for us, joy! */ |
866 | /* stdin might have data for us, joy! */; |
707 | } |
867 | } |
708 | |
868 | |
709 | ev_once (STDIN_FILENO, EV_READm 10., stdin_ready, 0); |
869 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
710 | |
870 | |
711 | </pre> |
871 | </pre> |
712 | </dd> |
872 | </dd> |
713 | <dt>ev_feed_event (loop, watcher, int events)</dt> |
873 | <dt>ev_feed_event (loop, watcher, int events)</dt> |
714 | <dd> |
874 | <dd> |
715 | <p>Feeds the given event set into the event loop, as if the specified event |
875 | <p>Feeds the given event set into the event loop, as if the specified event |
716 | has happened for the specified watcher (which must be a pointer to an |
876 | had happened for the specified watcher (which must be a pointer to an |
717 | initialised but not necessarily active event watcher).</p> |
877 | initialised but not necessarily started event watcher).</p> |
718 | </dd> |
878 | </dd> |
719 | <dt>ev_feed_fd_event (loop, int fd, int revents)</dt> |
879 | <dt>ev_feed_fd_event (loop, int fd, int revents)</dt> |
720 | <dd> |
880 | <dd> |
721 | <p>Feed an event on the given fd, as if a file descriptor backend detected it.</p> |
881 | <p>Feed an event on the given fd, as if a file descriptor backend detected |
|
|
882 | the given events it.</p> |
722 | </dd> |
883 | </dd> |
723 | <dt>ev_feed_signal_event (loop, int signum)</dt> |
884 | <dt>ev_feed_signal_event (loop, int signum)</dt> |
724 | <dd> |
885 | <dd> |
725 | <p>Feed an event as if the given signal occured (loop must be the default loop!).</p> |
886 | <p>Feed an event as if the given signal occured (loop must be the default loop!).</p> |
726 | </dd> |
887 | </dd> |
727 | </dl> |
888 | </dl> |
|
|
889 | |
|
|
890 | </div> |
|
|
891 | <h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
|
|
892 | <div id="LIBEVENT_EMULATION_CONTENT"> |
|
|
893 | <p>Libev offers a compatibility emulation layer for libevent. It cannot |
|
|
894 | emulate the internals of libevent, so here are some usage hints:</p> |
|
|
895 | <dl> |
|
|
896 | <dt>* Use it by including <event.h>, as usual.</dt> |
|
|
897 | <dt>* The following members are fully supported: ev_base, ev_callback, |
|
|
898 | ev_arg, ev_fd, ev_res, ev_events.</dt> |
|
|
899 | <dt>* Avoid using ev_flags and the EVLIST_*-macros, while it is |
|
|
900 | maintained by libev, it does not work exactly the same way as in libevent (consider |
|
|
901 | it a private API).</dt> |
|
|
902 | <dt>* Priorities are not currently supported. Initialising priorities |
|
|
903 | will fail and all watchers will have the same priority, even though there |
|
|
904 | is an ev_pri field.</dt> |
|
|
905 | <dt>* Other members are not supported.</dt> |
|
|
906 | <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need |
|
|
907 | to use the libev header file and library.</dt> |
|
|
908 | </dl> |
|
|
909 | |
|
|
910 | </div> |
|
|
911 | <h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> |
|
|
912 | <div id="C_SUPPORT_CONTENT"> |
|
|
913 | <p>TBD.</p> |
728 | |
914 | |
729 | </div> |
915 | </div> |
730 | <h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> |
916 | <h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> |
731 | <div id="AUTHOR_CONTENT"> |
917 | <div id="AUTHOR_CONTENT"> |
732 | <p>Marc Lehmann <libev@schmorp.de>.</p> |
918 | <p>Marc Lehmann <libev@schmorp.de>.</p> |