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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" /> |
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="Mon Nov 12 09:32:51 2007" /> |
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12 | <body> |
12 | <body> |
13 | <div class="pod"> |
13 | <div class="pod"> |
14 | <!-- INDEX START --> |
14 | <!-- INDEX START --> |
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24 | <li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a> |
24 | <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> |
25 | <ul><li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li> |
26 | </ul> |
26 | </ul> |
27 | </li> |
27 | </li> |
28 | <li><a href="#WATCHER_TYPES">WATCHER TYPES</a> |
28 | <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> |
29 | <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> |
30 | <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> |
31 | <li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron it</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> |
32 | <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> |
33 | <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> |
34 | <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> |
35 | <li><a href="#prepare_and_check_your_hooks_into_th">prepare and check - your hooks into the event loop</a></li> |
36 | </ul> |
36 | </ul> |
37 | </li> |
37 | </li> |
38 | <li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> |
38 | <li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> |
39 | <li><a href="#AUTHOR">AUTHOR</a> |
39 | <li><a href="#AUTHOR">AUTHOR</a> |
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107 | <p>You can find out the major and minor version numbers of the library |
107 | <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 |
108 | 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 |
109 | <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 |
110 | 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> |
111 | version of the library your program was compiled against.</p> |
112 | <p>Usually, its a good idea to terminate if the major versions mismatch, |
112 | <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 |
113 | as this indicates an incompatible change. Minor versions are usually |
114 | compatible to older versions, so a larger minor version alone is usually |
114 | compatible to older versions, so a larger minor version alone is usually |
115 | not a problem.</p> |
115 | not a problem.</p> |
116 | </dd> |
116 | </dd> |
117 | <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> |
117 | <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> |
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146 | <p>If you use threads, a common model is to run the default event loop |
146 | <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 |
147 | in your main thread (or in a separate thrad) and for each thread you |
148 | create, you also create another event loop. Libev itself does no locking |
148 | 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 |
149 | 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 |
150 | threads, make sure you lock (this is usually a bad idea, though, even if |
151 | done correctly, because its hideous and inefficient).</p> |
151 | done correctly, because it's hideous and inefficient).</p> |
152 | <dl> |
152 | <dl> |
153 | <dt>struct ev_loop *ev_default_loop (unsigned int flags)</dt> |
153 | <dt>struct ev_loop *ev_default_loop (unsigned int flags)</dt> |
154 | <dd> |
154 | <dd> |
155 | <p>This will initialise the default event loop if it hasn't been initialised |
155 | <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 |
156 | yet and return it. If the default loop could not be initialised, returns |
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161 | <p>The flags argument can be used to specify special behaviour or specific |
161 | <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> |
162 | backends to use, and is usually specified as 0 (or EVFLAG_AUTO).</p> |
163 | <p>It supports the following flags:</p> |
163 | <p>It supports the following flags:</p> |
164 | <p> |
164 | <p> |
165 | <dl> |
165 | <dl> |
166 | <dt>EVFLAG_AUTO</dt> |
166 | <dt><code>EVFLAG_AUTO</code></dt> |
167 | <dd> |
167 | <dd> |
168 | <p>The default flags value. Use this if you have no clue (its the right |
168 | <p>The default flags value. Use this if you have no clue (it's the right |
169 | thing, believe me).</p> |
169 | thing, believe me).</p> |
170 | </dd> |
170 | </dd> |
171 | <dt>EVFLAG_NOENV</dt> |
171 | <dt><code>EVFLAG_NOENV</code></dt> |
172 | <dd> |
172 | <dd> |
173 | <p>If this flag bit is ored into the flag value (or the program runs setuid |
173 | <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 |
174 | 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 |
175 | <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 |
176 | 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 |
177 | useful to try out specific backends to test their performance, or to work |
178 | around bugs.</p> |
178 | around bugs.</p> |
179 | </dd> |
179 | </dd> |
180 | <dt>EVMETHOD_SELECT portable select backend</dt> |
180 | <dt><code>EVMETHOD_SELECT</code> (portable select backend)</dt> |
181 | <dt>EVMETHOD_POLL poll backend (everywhere except windows)</dt> |
181 | <dt><code>EVMETHOD_POLL</code> (poll backend, available everywhere except on windows)</dt> |
182 | <dt>EVMETHOD_EPOLL linux only</dt> |
182 | <dt><code>EVMETHOD_EPOLL</code> (linux only)</dt> |
183 | <dt>EVMETHOD_KQUEUE some bsds only</dt> |
183 | <dt><code>EVMETHOD_KQUEUE</code> (some bsds only)</dt> |
184 | <dt>EVMETHOD_DEVPOLL solaris 8 only</dt> |
184 | <dt><code>EVMETHOD_DEVPOLL</code> (solaris 8 only)</dt> |
185 | <dt>EVMETHOD_PORT solaris 10 only</dt> |
185 | <dt><code>EVMETHOD_PORT</code> (solaris 10 only)</dt> |
186 | <dd> |
186 | <dd> |
187 | <p>If one or more of these are ored into the flags value, then only these |
187 | <p>If one or more of these are ored into the flags value, then only these |
188 | backends will be tried (in the reverse order as given here). If one are |
188 | backends will be tried (in the reverse order as given here). If one are |
189 | specified, any backend will do.</p> |
189 | specified, any backend will do.</p> |
190 | </dd> |
190 | </dd> |
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200 | </dd> |
200 | </dd> |
201 | <dt>ev_default_destroy ()</dt> |
201 | <dt>ev_default_destroy ()</dt> |
202 | <dd> |
202 | <dd> |
203 | <p>Destroys the default loop again (frees all memory and kernel state |
203 | <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 |
204 | etc.). This stops all registered event watchers (by not touching them in |
205 | any way whatsoever, although you cnanot rely on this :).</p> |
205 | any way whatsoever, although you cannot rely on this :).</p> |
206 | </dd> |
206 | </dd> |
207 | <dt>ev_loop_destroy (loop)</dt> |
207 | <dt>ev_loop_destroy (loop)</dt> |
208 | <dd> |
208 | <dd> |
209 | <p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an |
209 | <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> |
210 | earlier call to <code>ev_loop_new</code>.</p> |
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216 | after forking, in either the parent or child process (or both, but that |
216 | after forking, in either the parent or child process (or both, but that |
217 | again makes little sense).</p> |
217 | again makes little sense).</p> |
218 | <p>You <i>must</i> call this function after forking if and only if you want to |
218 | <p>You <i>must</i> call this function after forking if and only if you want to |
219 | use the event library in both processes. If you just fork+exec, you don't |
219 | use the event library in both processes. If you just fork+exec, you don't |
220 | have to call it.</p> |
220 | have to call it.</p> |
221 | <p>The function itself is quite fast and its usually not a problem to call |
221 | <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 |
222 | 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> |
223 | quite nicely into a call to <code>pthread_atfork</code>:</p> |
224 | <pre> pthread_atfork (0, 0, ev_default_fork); |
224 | <pre> pthread_atfork (0, 0, ev_default_fork); |
225 | |
225 | |
226 | </pre> |
226 | </pre> |
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234 | <dt>unsigned int ev_method (loop)</dt> |
234 | <dt>unsigned int ev_method (loop)</dt> |
235 | <dd> |
235 | <dd> |
236 | <p>Returns one of the <code>EVMETHOD_*</code> flags indicating the event backend in |
236 | <p>Returns one of the <code>EVMETHOD_*</code> flags indicating the event backend in |
237 | use.</p> |
237 | use.</p> |
238 | </dd> |
238 | </dd> |
239 | <dt>ev_tstamp = ev_now (loop)</dt> |
239 | <dt>ev_tstamp ev_now (loop)</dt> |
240 | <dd> |
240 | <dd> |
241 | <p>Returns the current "event loop time", which is the time the event loop |
241 | <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 |
242 | 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 |
243 | 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 |
244 | used for relative timers. You can treat it as the timestamp of the event |
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251 | events.</p> |
251 | events.</p> |
252 | <p>If the flags argument is specified as 0, it will not return until either |
252 | <p>If the flags argument is specified as 0, it will not return until either |
253 | no event watchers are active anymore or <code>ev_unloop</code> was called.</p> |
253 | 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 |
254 | <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 |
255 | those events and any outstanding ones, but will not block your process in |
256 | case there are no events.</p> |
256 | 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 |
257 | <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 |
258 | neccessary) and will handle those and any outstanding ones. It will block |
259 | your process until at least one new event arrives.</p> |
259 | your process until at least one new event arrives, and will return after |
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260 | one iteration of the loop.</p> |
260 | <p>This flags value could be used to implement alternative looping |
261 | <p>This flags value could be used to implement alternative looping |
261 | constructs, but the <code>prepare</code> and <code>check</code> watchers provide a better and |
262 | constructs, but the <code>prepare</code> and <code>check</code> watchers provide a better and |
262 | more generic mechanism.</p> |
263 | more generic mechanism.</p> |
263 | </dd> |
264 | </dd> |
264 | <dt>ev_unloop (loop, how)</dt> |
265 | <dt>ev_unloop (loop, how)</dt> |
265 | <dd> |
266 | <dd> |
266 | <p>Can be used to make a call to <code>ev_loop</code> return early. The <code>how</code> argument |
267 | <p>Can be used to make a call to <code>ev_loop</code> return early (but only after it |
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268 | 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> |
269 | <code>EVUNLOOP_ONCE</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> |
270 | <code>EVUNLOOP_ALL</code>, which will make all nested <code>ev_loop</code> calls return.</p> |
269 | calls return.</p> |
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270 | </dd> |
271 | </dd> |
271 | <dt>ev_ref (loop)</dt> |
272 | <dt>ev_ref (loop)</dt> |
272 | <dt>ev_unref (loop)</dt> |
273 | <dt>ev_unref (loop)</dt> |
273 | <dd> |
274 | <dd> |
274 | <p>Ref/unref can be used to add or remove a refcount on the event loop: Every |
275 | <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 |
276 | 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 |
277 | 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 |
278 | 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 |
279 | 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 |
280 | 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 |
281 | 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 |
282 | no event watchers registered by it are active. It is also an excellent |
282 | before stop.</p> |
283 | way to do this for generic recurring timers or from within third-party |
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284 | libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p> |
283 | </dd> |
285 | </dd> |
284 | </dl> |
286 | </dl> |
285 | |
287 | |
286 | </div> |
288 | </div> |
287 | <h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p> |
289 | <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"> |
290 | <div id="ANATOMY_OF_A_WATCHER_CONTENT"> |
289 | <p>A watcher is a structure that you create and register to record your |
291 | <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 |
292 | 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> |
293 | 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) |
294 | <pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
293 | { |
295 | { |
294 | ev_io_stop (w); |
296 | ev_io_stop (w); |
295 | ev_unloop (loop, EVUNLOOP_ALL); |
297 | ev_unloop (loop, EVUNLOOP_ALL); |
296 | } |
298 | } |
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331 | third argument.</p> |
333 | third argument.</p> |
332 | <p>The rceeived events usually include a single bit per event type received |
334 | <p>The rceeived events usually include a single bit per event type received |
333 | (you can receive multiple events at the same time). The possible bit masks |
335 | (you can receive multiple events at the same time). The possible bit masks |
334 | are:</p> |
336 | are:</p> |
335 | <dl> |
337 | <dl> |
336 | <dt>EV_READ</dt> |
338 | <dt><code>EV_READ</code></dt> |
337 | <dt>EV_WRITE</dt> |
339 | <dt><code>EV_WRITE</code></dt> |
338 | <dd> |
340 | <dd> |
339 | <p>The file descriptor in the ev_io watcher has become readable and/or |
341 | <p>The file descriptor in the <code>ev_io</code> watcher has become readable and/or |
340 | writable.</p> |
342 | writable.</p> |
341 | </dd> |
343 | </dd> |
342 | <dt>EV_TIMEOUT</dt> |
344 | <dt><code>EV_TIMEOUT</code></dt> |
343 | <dd> |
|
|
344 | <p>The ev_timer watcher has timed out.</p> |
|
|
345 | </dd> |
345 | <dd> |
346 | <dt>EV_PERIODIC</dt> |
346 | <p>The <code>ev_timer</code> watcher has timed out.</p> |
347 | <dd> |
347 | </dd> |
348 | <p>The ev_periodic watcher has timed out.</p> |
348 | <dt><code>EV_PERIODIC</code></dt> |
349 | </dd> |
349 | <dd> |
350 | <dt>EV_SIGNAL</dt> |
350 | <p>The <code>ev_periodic</code> watcher has timed out.</p> |
351 | <dd> |
351 | </dd> |
|
|
352 | <dt><code>EV_SIGNAL</code></dt> |
|
|
353 | <dd> |
352 | <p>The signal specified in the ev_signal watcher has been received by a thread.</p> |
354 | <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> |
355 | </dd> |
|
|
356 | <dt><code>EV_CHILD</code></dt> |
|
|
357 | <dd> |
356 | <p>The pid specified in the ev_child watcher has received a status change.</p> |
358 | <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> |
359 | </dd> |
|
|
360 | <dt><code>EV_IDLE</code></dt> |
|
|
361 | <dd> |
360 | <p>The ev_idle watcher has determined that you have nothing better to do.</p> |
362 | <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> |
363 | </dd> |
|
|
364 | <dt><code>EV_PREPARE</code></dt> |
|
|
365 | <dt><code>EV_CHECK</code></dt> |
|
|
366 | <dd> |
365 | <p>All ev_prepare watchers are invoked just <i>before</i> <code>ev_loop</code> starts |
367 | <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 |
368 | 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 |
369 | <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 |
370 | 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 |
371 | 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 |
372 | (for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep |
371 | <code>ev_loop</code> from blocking).</p> |
373 | <code>ev_loop</code> from blocking).</p> |
372 | </dd> |
374 | </dd> |
373 | <dt>EV_ERROR</dt> |
375 | <dt><code>EV_ERROR</code></dt> |
374 | <dd> |
376 | <dd> |
375 | <p>An unspecified error has occured, the watcher has been stopped. This might |
377 | <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 |
378 | 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 |
379 | 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 |
380 | problem. You best act on it by reporting the problem and somehow coping |
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424 | <div id="WATCHER_TYPES_CONTENT"> |
426 | <div id="WATCHER_TYPES_CONTENT"> |
425 | <p>This section describes each watcher in detail, but will not repeat |
427 | <p>This section describes each watcher in detail, but will not repeat |
426 | information given in the last section.</p> |
428 | information given in the last section.</p> |
427 | |
429 | |
428 | </div> |
430 | </div> |
429 | <h2 id="struct_ev_io_is_my_file_descriptor_r">struct ev_io - is my file descriptor readable or writable</h2> |
431 | <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"> |
432 | <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 |
433 | <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 |
434 | in each iteration of the event loop (This behaviour is called |
433 | level-triggering because you keep receiving events as long as the |
435 | 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 |
436 | condition persists. Remember you cna stop the watcher if you don't want to |
435 | act on the event and neither want to receive future events).</p> |
437 | act on the event and neither want to receive future events).</p> |
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… | |
446 | EVMETHOD_POLL).</p> |
448 | EVMETHOD_POLL).</p> |
447 | <dl> |
449 | <dl> |
448 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
450 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
449 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
451 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
450 | <dd> |
452 | <dd> |
451 | <p>Configures an ev_io watcher. The fd is the file descriptor to rceeive |
453 | <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 | |
454 | 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> |
455 | EV_WRITE</code> to receive the given events.</p> |
454 | </dd> |
456 | </dd> |
455 | </dl> |
457 | </dl> |
456 | |
458 | |
457 | </div> |
459 | </div> |
458 | <h2 id="struct_ev_timer_relative_and_optiona">struct ev_timer - relative and optionally recurring timeouts</h2> |
460 | <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"> |
461 | <div id="code_ev_timer_code_relative_and_opti-2"> |
460 | <p>Timer watchers are simple relative timers that generate an event after a |
462 | <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> |
463 | 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 |
464 | <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 |
465 | times out after an hour and youreset your system clock to last years |
464 | time, it will still time out after (roughly) and hour. "Roughly" because |
466 | time, it will still time out after (roughly) and hour. "Roughly" because |
465 | detecting time jumps is hard, and soem inaccuracies are unavoidable (the |
467 | detecting time jumps is hard, and soem inaccuracies are unavoidable (the |
466 | monotonic clock option helps a lot here).</p> |
468 | monotonic clock option helps a lot here).</p> |
|
|
469 | <p>The relative timeouts are calculated relative to the <code>ev_now ()</code> |
|
|
470 | time. This is usually the right thing as this timestamp refers to the time |
|
|
471 | of the event triggering whatever timeout you are modifying/starting. If |
|
|
472 | you suspect event processing to be delayed and you *need* to base the timeout |
|
|
473 | ion the current time, use something like this to adjust for this:</p> |
|
|
474 | <pre> ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
|
|
475 | |
|
|
476 | </pre> |
467 | <dl> |
477 | <dl> |
468 | <dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt> |
478 | <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> |
479 | <dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt> |
470 | <dd> |
480 | <dd> |
471 | <p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is |
481 | <p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is |
… | |
… | |
487 | value), or reset the running timer to the repeat value.</p> |
497 | 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 |
498 | <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 |
499 | 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 |
500 | 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 |
501 | 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 |
502 | 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 |
503 | 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 |
504 | 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> |
505 | the timer, and again will automatically restart it if need be.</p> |
496 | </dd> |
506 | </dd> |
497 | </dl> |
507 | </dl> |
498 | |
508 | |
499 | </div> |
509 | </div> |
500 | <h2 id="ev_periodic_to_cron_or_not_to_cron_i">ev_periodic - to cron or not to cron it</h2> |
510 | <h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron it</h2> |
501 | <div id="ev_periodic_to_cron_or_not_to_cron_i-2"> |
511 | <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 |
512 | <p>Periodic watchers are also timers of a kind, but they are very versatile |
503 | (and unfortunately a bit complex).</p> |
513 | (and unfortunately a bit complex).</p> |
504 | <p>Unlike ev_timer's, they are not based on real time (or relative time) |
514 | <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 |
515 | 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 |
516 | 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 () |
517 | 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 |
518 | + 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 |
519 | 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 |
520 | roughly 10 seconds later and of course not if you reset your system time |
511 | again).</p> |
521 | again).</p> |
512 | <p>They can also be used to implement vastly more complex timers, such as |
522 | <p>They can also be used to implement vastly more complex timers, such as |
513 | triggering an event on eahc midnight, local time.</p> |
523 | triggering an event on eahc midnight, local time.</p> |
514 | <dl> |
524 | <dl> |
… | |
… | |
543 | <p>This doesn't mean there will always be 3600 seconds in between triggers, |
553 | <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 |
554 | 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 |
555 | full hour (UTC), or more correct, when the system time is evenly divisible |
546 | by 3600.</p> |
556 | by 3600.</p> |
547 | <p>Another way to think about it (for the mathematically inclined) is that |
557 | <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 |
558 | <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> |
559 | time where <code>time = at (mod interval)</code>, regardless of any time jumps.</p> |
550 | </dd> |
560 | </dd> |
551 | <dt>* manual reschedule mode (reschedule_cb = callback)</dt> |
561 | <dt>* manual reschedule mode (reschedule_cb = callback)</dt> |
552 | <dd> |
562 | <dd> |
553 | <p>In this mode the values for <code>interval</code> and <code>at</code> are both being |
563 | <p>In this mode the values for <code>interval</code> and <code>at</code> are both being |
… | |
… | |
585 | program when the crontabs have changed).</p> |
595 | program when the crontabs have changed).</p> |
586 | </dd> |
596 | </dd> |
587 | </dl> |
597 | </dl> |
588 | |
598 | |
589 | </div> |
599 | </div> |
590 | <h2 id="ev_signal_signal_me_when_a_signal_ge">ev_signal - signal me when a signal gets signalled</h2> |
600 | <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"> |
601 | <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 |
602 | <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 |
603 | 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 |
604 | will try it's best to deliver signals synchronously, i.e. as part of the |
595 | normal event processing, like any other event.</p> |
605 | normal event processing, like any other event.</p> |
596 | <p>You cna configure as many watchers as you like per signal. Only when the |
606 | <p>You cna configure as many watchers as you like per signal. Only when the |
597 | first watcher gets started will libev actually register a signal watcher |
607 | 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 |
608 | 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 |
609 | as you don't register any with libev). Similarly, when the last signal |
… | |
… | |
607 | of the <code>SIGxxx</code> constants).</p> |
617 | of the <code>SIGxxx</code> constants).</p> |
608 | </dd> |
618 | </dd> |
609 | </dl> |
619 | </dl> |
610 | |
620 | |
611 | </div> |
621 | </div> |
612 | <h2 id="ev_child_wait_for_pid_status_changes">ev_child - wait for pid status changes</h2> |
622 | <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"> |
623 | <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 |
624 | <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> |
625 | some child status changes (most typically when a child of yours dies).</p> |
616 | <dl> |
626 | <dl> |
617 | <dt>ev_child_init (ev_child *, callback, int pid)</dt> |
627 | <dt>ev_child_init (ev_child *, callback, int pid)</dt> |
618 | <dt>ev_child_set (ev_child *, int pid)</dt> |
628 | <dt>ev_child_set (ev_child *, int pid)</dt> |
… | |
… | |
624 | contains the pid of the process causing the status change.</p> |
634 | contains the pid of the process causing the status change.</p> |
625 | </dd> |
635 | </dd> |
626 | </dl> |
636 | </dl> |
627 | |
637 | |
628 | </div> |
638 | </div> |
629 | <h2 id="ev_idle_when_you_ve_got_nothing_bett">ev_idle - when you've got nothing better to do</h2> |
639 | <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"> |
640 | <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 |
641 | <p>Idle watchers trigger events when there are no other I/O or timer (or |
632 | periodic) events pending. That is, as long as your process is busy |
642 | periodic) events pending. That is, as long as your process is busy |
633 | handling sockets or timeouts it will not be called. But when your process |
643 | handling sockets or timeouts it will not be called. But when your process |
634 | is idle all idle watchers are being called again and again - until |
644 | is idle all idle watchers are being called again and again - until |
635 | stopped, that is, or your process receives more events.</p> |
645 | stopped, that is, or your process receives more events.</p> |
… | |
… | |
656 | watchers afterwards.</p> |
666 | watchers afterwards.</p> |
657 | <p>Their main purpose is to integrate other event mechanisms into libev. This |
667 | <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 |
668 | 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> |
669 | 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 |
670 | <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 |
671 | to be watched by the other library, registering <code>ev_io</code> watchers for them |
662 | and starting an ev_timer watcher for any timeouts (many libraries provide |
672 | and starting an <code>ev_timer</code> watcher for any timeouts (many libraries provide |
663 | just this functionality). Then, in the check watcher you check for any |
673 | just this functionality). Then, in the check watcher you check for any |
664 | events that occured (by making your callbacks set soem flags for example) |
674 | events that occured (by making your callbacks set soem flags for example) |
665 | and call back into the library.</p> |
675 | and call back into the library.</p> |
666 | <p>As another example, the perl Coro module uses these hooks to integrate |
676 | <p>As another example, the perl Coro module uses these hooks to integrate |
667 | coroutines into libev programs, by yielding to other active coroutines |
677 | coroutines into libev programs, by yielding to other active coroutines |
… | |
… | |
688 | callback on whichever event happens first and automatically stop both |
698 | 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 |
699 | 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 |
700 | or timeout without havign to allocate/configure/start/stop/free one or |
691 | more watchers yourself.</p> |
701 | 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 |
702 | <p>If <code>fd</code> is less than 0, then no I/O watcher will be started and events is |
693 | ignored. Otherwise, an ev_io watcher for the given <code>fd</code> and <code>events</code> set |
703 | ignored. Otherwise, an <code>ev_io</code> watcher for the given <code>fd</code> and <code>events</code> set |
694 | will be craeted and started.</p> |
704 | will be craeted and started.</p> |
695 | <p>If <code>timeout</code> is less than 0, then no timeout watcher will be |
705 | <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 |
706 | started. Otherwise an <code>ev_timer</code> watcher with after = <code>timeout</code> (and repeat |
697 | = 0) will be started.</p> |
707 | = 0) will be started.</p> |
698 | <p>The callback has the type <code>void (*cb)(int revents, void *arg)</code> and |
708 | <p>The callback has the type <code>void (*cb)(int revents, void *arg)</code> and |
699 | gets passed an events set (normally a combination of EV_ERROR, EV_READ, |
709 | gets passed an events set (normally a combination of <code>EV_ERROR</code>, <code>EV_READ</code>, |
700 | EV_WRITE or EV_TIMEOUT) and the <code>arg</code> value passed to <code>ev_once</code>:</p> |
710 | <code>EV_WRITE</code> or <code>EV_TIMEOUT</code>) and the <code>arg</code> value passed to <code>ev_once</code>:</p> |
701 | <pre> static void stdin_ready (int revents, void *arg) |
711 | <pre> static void stdin_ready (int revents, void *arg) |
702 | { |
712 | { |
703 | if (revents & EV_TIMEOUT) |
713 | if (revents & EV_TIMEOUT) |
704 | /* doh, nothing entered */ |
714 | /* doh, nothing entered */ |
705 | else if (revents & EV_READ) |
715 | else if (revents & EV_READ) |