… | |
… | |
25 | |
25 | |
26 | Libev supports select, poll, the linux-specific epoll and the bsd-specific |
26 | Libev supports select, poll, the linux-specific epoll and the bsd-specific |
27 | kqueue mechanisms for file descriptor events, relative timers, absolute |
27 | kqueue mechanisms for file descriptor events, relative timers, absolute |
28 | timers with customised rescheduling, signal events, process status change |
28 | timers with customised rescheduling, signal events, process status change |
29 | events (related to SIGCHLD), and event watchers dealing with the event |
29 | events (related to SIGCHLD), and event watchers dealing with the event |
30 | loop mechanism itself (idle, prepare and check watchers). |
30 | loop mechanism itself (idle, prepare and check watchers). It also is quite |
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31 | fast (see this L<benchmark|http://libev.schmorp.de/bench.html> comparing |
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32 | it to libevent for example). |
31 | |
33 | |
32 | =head1 CONVENTIONS |
34 | =head1 CONVENTIONS |
33 | |
35 | |
34 | Libev is very configurable. In this manual the default configuration |
36 | Libev is very configurable. In this manual the default configuration |
35 | will be described, which supports multiple event loops. For more info |
37 | will be described, which supports multiple event loops. For more info |
36 | about various configuraiton options please have a look at the file |
38 | about various configuration options please have a look at the file |
37 | F<README.embed> in the libev distribution. If libev was configured without |
39 | F<README.embed> in the libev distribution. If libev was configured without |
38 | support for multiple event loops, then all functions taking an initial |
40 | support for multiple event loops, then all functions taking an initial |
39 | argument of name C<loop> (which is always of type C<struct ev_loop *>) |
41 | argument of name C<loop> (which is always of type C<struct ev_loop *>) |
40 | will not have this argument. |
42 | will not have this argument. |
41 | |
43 | |
42 | =head1 TIME AND OTHER GLOBAL FUNCTIONS |
44 | =head1 TIME REPRESENTATION |
43 | |
45 | |
44 | Libev represents time as a single floating point number, representing the |
46 | Libev represents time as a single floating point number, representing the |
45 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
47 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
46 | the beginning of 1970, details are complicated, don't ask). This type is |
48 | the beginning of 1970, details are complicated, don't ask). This type is |
47 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
49 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
48 | to the double type in C. |
50 | to the double type in C. |
49 | |
51 | |
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52 | =head1 GLOBAL FUNCTIONS |
|
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53 | |
|
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54 | These functions can be called anytime, even before initialising the |
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55 | library in any way. |
|
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56 | |
50 | =over 4 |
57 | =over 4 |
51 | |
58 | |
52 | =item ev_tstamp ev_time () |
59 | =item ev_tstamp ev_time () |
53 | |
60 | |
54 | Returns the current time as libev would use it. |
61 | Returns the current time as libev would use it. |
… | |
… | |
61 | you linked against by calling the functions C<ev_version_major> and |
68 | you linked against by calling the functions C<ev_version_major> and |
62 | C<ev_version_minor>. If you want, you can compare against the global |
69 | C<ev_version_minor>. If you want, you can compare against the global |
63 | symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the |
70 | symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the |
64 | version of the library your program was compiled against. |
71 | version of the library your program was compiled against. |
65 | |
72 | |
66 | Usually, its a good idea to terminate if the major versions mismatch, |
73 | Usually, it's a good idea to terminate if the major versions mismatch, |
67 | as this indicates an incompatible change. Minor versions are usually |
74 | as this indicates an incompatible change. Minor versions are usually |
68 | compatible to older versions, so a larger minor version alone is usually |
75 | compatible to older versions, so a larger minor version alone is usually |
69 | not a problem. |
76 | not a problem. |
70 | |
77 | |
71 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
78 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
72 | |
79 | |
73 | Sets the allocation function to use (the prototype is similar to the |
80 | Sets the allocation function to use (the prototype is similar to the |
74 | realloc function). It is used to allocate and free memory (no surprises |
81 | realloc C function, the semantics are identical). It is used to allocate |
75 | here). If it returns zero when memory needs to be allocated, the library |
82 | and free memory (no surprises here). If it returns zero when memory |
76 | might abort or take some potentially destructive action. The default is |
83 | needs to be allocated, the library might abort or take some potentially |
77 | your system realloc function. |
84 | destructive action. The default is your system realloc function. |
78 | |
85 | |
79 | You could override this function in high-availability programs to, say, |
86 | You could override this function in high-availability programs to, say, |
80 | free some memory if it cannot allocate memory, to use a special allocator, |
87 | free some memory if it cannot allocate memory, to use a special allocator, |
81 | or even to sleep a while and retry until some memory is available. |
88 | or even to sleep a while and retry until some memory is available. |
82 | |
89 | |
… | |
… | |
84 | |
91 | |
85 | Set the callback function to call on a retryable syscall error (such |
92 | Set the callback function to call on a retryable syscall error (such |
86 | as failed select, poll, epoll_wait). The message is a printable string |
93 | as failed select, poll, epoll_wait). The message is a printable string |
87 | indicating the system call or subsystem causing the problem. If this |
94 | indicating the system call or subsystem causing the problem. If this |
88 | callback is set, then libev will expect it to remedy the sitution, no |
95 | callback is set, then libev will expect it to remedy the sitution, no |
89 | matter what, when it returns. That is, libev will geenrally retry the |
96 | matter what, when it returns. That is, libev will generally retry the |
90 | requested operation, or, if the condition doesn't go away, do bad stuff |
97 | requested operation, or, if the condition doesn't go away, do bad stuff |
91 | (such as abort). |
98 | (such as abort). |
92 | |
99 | |
93 | =back |
100 | =back |
94 | |
101 | |
… | |
… | |
97 | An event loop is described by a C<struct ev_loop *>. The library knows two |
104 | An event loop is described by a C<struct ev_loop *>. The library knows two |
98 | types of such loops, the I<default> loop, which supports signals and child |
105 | types of such loops, the I<default> loop, which supports signals and child |
99 | events, and dynamically created loops which do not. |
106 | events, and dynamically created loops which do not. |
100 | |
107 | |
101 | If you use threads, a common model is to run the default event loop |
108 | If you use threads, a common model is to run the default event loop |
102 | in your main thread (or in a separate thrad) and for each thread you |
109 | in your main thread (or in a separate thread) and for each thread you |
103 | create, you also create another event loop. Libev itself does no lockign |
110 | create, you also create another event loop. Libev itself does no locking |
104 | whatsoever, so if you mix calls to different event loops, make sure you |
111 | whatsoever, so if you mix calls to the same event loop in different |
105 | lock (this is usually a bad idea, though, even if done right). |
112 | threads, make sure you lock (this is usually a bad idea, though, even if |
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113 | done correctly, because it's hideous and inefficient). |
106 | |
114 | |
107 | =over 4 |
115 | =over 4 |
108 | |
116 | |
109 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
117 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
110 | |
118 | |
… | |
… | |
115 | |
123 | |
116 | If you don't know what event loop to use, use the one returned from this |
124 | If you don't know what event loop to use, use the one returned from this |
117 | function. |
125 | function. |
118 | |
126 | |
119 | The flags argument can be used to specify special behaviour or specific |
127 | The flags argument can be used to specify special behaviour or specific |
120 | backends to use, and is usually specified as 0 (or EVFLAG_AUTO) |
128 | backends to use, and is usually specified as 0 (or EVFLAG_AUTO). |
121 | |
129 | |
122 | It supports the following flags: |
130 | It supports the following flags: |
123 | |
131 | |
124 | =over 4 |
132 | =over 4 |
125 | |
133 | |
126 | =item EVFLAG_AUTO |
134 | =item C<EVFLAG_AUTO> |
127 | |
135 | |
128 | The default flags value. Use this if you have no clue (its the right |
136 | The default flags value. Use this if you have no clue (it's the right |
129 | thing, believe me). |
137 | thing, believe me). |
130 | |
138 | |
131 | =item EVFLAG_NOENV |
139 | =item C<EVFLAG_NOENV> |
132 | |
140 | |
133 | If this flag bit is ored into the flag value then libev will I<not> look |
141 | If this flag bit is ored into the flag value (or the program runs setuid |
134 | at the environment variable C<LIBEV_FLAGS>. Otherwise (the default), this |
142 | or setgid) then libev will I<not> look at the environment variable |
135 | environment variable will override the flags completely. This is useful |
143 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
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144 | override the flags completely if it is found in the environment. This is |
136 | to try out specific backends to tets their performance, or to work around |
145 | useful to try out specific backends to test their performance, or to work |
137 | bugs. |
146 | around bugs. |
138 | |
147 | |
139 | =item EVMETHOD_SELECT portable select backend |
148 | =item C<EVMETHOD_SELECT> (portable select backend) |
140 | |
149 | |
141 | =item EVMETHOD_POLL poll backend (everywhere except windows) |
150 | =item C<EVMETHOD_POLL> (poll backend, available everywhere except on windows) |
142 | |
151 | |
143 | =item EVMETHOD_EPOLL linux only |
152 | =item C<EVMETHOD_EPOLL> (linux only) |
144 | |
153 | |
145 | =item EVMETHOD_KQUEUE some bsds only |
154 | =item C<EVMETHOD_KQUEUE> (some bsds only) |
146 | |
155 | |
147 | =item EVMETHOD_DEVPOLL solaris 8 only |
156 | =item C<EVMETHOD_DEVPOLL> (solaris 8 only) |
148 | |
157 | |
149 | =item EVMETHOD_PORT solaris 10 only |
158 | =item C<EVMETHOD_PORT> (solaris 10 only) |
150 | |
159 | |
151 | If one or more of these are ored into the flags value, then only these |
160 | If one or more of these are ored into the flags value, then only these |
152 | backends will be tried (in the reverse order as given here). If one are |
161 | backends will be tried (in the reverse order as given here). If one are |
153 | specified, any backend will do. |
162 | specified, any backend will do. |
154 | |
163 | |
… | |
… | |
163 | |
172 | |
164 | =item ev_default_destroy () |
173 | =item ev_default_destroy () |
165 | |
174 | |
166 | Destroys the default loop again (frees all memory and kernel state |
175 | Destroys the default loop again (frees all memory and kernel state |
167 | etc.). This stops all registered event watchers (by not touching them in |
176 | etc.). This stops all registered event watchers (by not touching them in |
168 | any way whatsoever, although you cnanot rely on this :). |
177 | any way whatsoever, although you cannot rely on this :). |
169 | |
178 | |
170 | =item ev_loop_destroy (loop) |
179 | =item ev_loop_destroy (loop) |
171 | |
180 | |
172 | Like C<ev_default_destroy>, but destroys an event loop created by an |
181 | Like C<ev_default_destroy>, but destroys an event loop created by an |
173 | earlier call to C<ev_loop_new>. |
182 | earlier call to C<ev_loop_new>. |
… | |
… | |
181 | |
190 | |
182 | You I<must> call this function after forking if and only if you want to |
191 | You I<must> call this function after forking if and only if you want to |
183 | use the event library in both processes. If you just fork+exec, you don't |
192 | use the event library in both processes. If you just fork+exec, you don't |
184 | have to call it. |
193 | have to call it. |
185 | |
194 | |
186 | The function itself is quite fast and its usually not a problem to call |
195 | The function itself is quite fast and it's usually not a problem to call |
187 | it just in case after a fork. To make this easy, the function will fit in |
196 | it just in case after a fork. To make this easy, the function will fit in |
188 | quite nicely into a call to C<pthread_atfork>: |
197 | quite nicely into a call to C<pthread_atfork>: |
189 | |
198 | |
190 | pthread_atfork (0, 0, ev_default_fork); |
199 | pthread_atfork (0, 0, ev_default_fork); |
191 | |
200 | |
… | |
… | |
198 | =item unsigned int ev_method (loop) |
207 | =item unsigned int ev_method (loop) |
199 | |
208 | |
200 | Returns one of the C<EVMETHOD_*> flags indicating the event backend in |
209 | Returns one of the C<EVMETHOD_*> flags indicating the event backend in |
201 | use. |
210 | use. |
202 | |
211 | |
203 | =item ev_tstamp = ev_now (loop) |
212 | =item ev_tstamp ev_now (loop) |
204 | |
213 | |
205 | Returns the current "event loop time", which is the time the event loop |
214 | Returns the current "event loop time", which is the time the event loop |
206 | got events and started processing them. This timestamp does not change |
215 | got events and started processing them. This timestamp does not change |
207 | as long as callbacks are being processed, and this is also the base time |
216 | as long as callbacks are being processed, and this is also the base time |
208 | used for relative timers. You can treat it as the timestamp of the event |
217 | used for relative timers. You can treat it as the timestamp of the event |
… | |
… | |
217 | If the flags argument is specified as 0, it will not return until either |
226 | If the flags argument is specified as 0, it will not return until either |
218 | no event watchers are active anymore or C<ev_unloop> was called. |
227 | no event watchers are active anymore or C<ev_unloop> was called. |
219 | |
228 | |
220 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
229 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
221 | those events and any outstanding ones, but will not block your process in |
230 | those events and any outstanding ones, but will not block your process in |
222 | case there are no events. |
231 | case there are no events and will return after one iteration of the loop. |
223 | |
232 | |
224 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
233 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
225 | neccessary) and will handle those and any outstanding ones. It will block |
234 | neccessary) and will handle those and any outstanding ones. It will block |
226 | your process until at least one new event arrives. |
235 | your process until at least one new event arrives, and will return after |
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236 | one iteration of the loop. |
227 | |
237 | |
228 | This flags value could be used to implement alternative looping |
238 | This flags value could be used to implement alternative looping |
229 | constructs, but the C<prepare> and C<check> watchers provide a better and |
239 | constructs, but the C<prepare> and C<check> watchers provide a better and |
230 | more generic mechanism. |
240 | more generic mechanism. |
231 | |
241 | |
232 | =item ev_unloop (loop, how) |
242 | =item ev_unloop (loop, how) |
233 | |
243 | |
234 | Can be used to make a call to C<ev_loop> return early. The C<how> argument |
244 | Can be used to make a call to C<ev_loop> return early (but only after it |
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245 | has processed all outstanding events). The C<how> argument must be either |
235 | must be either C<EVUNLOOP_ONCE>, which will make the innermost C<ev_loop> |
246 | C<EVUNLOOP_ONCE>, which will make the innermost C<ev_loop> call return, or |
236 | call return, or C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> |
247 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
237 | calls return. |
|
|
238 | |
248 | |
239 | =item ev_ref (loop) |
249 | =item ev_ref (loop) |
240 | |
250 | |
241 | =item ev_unref (loop) |
251 | =item ev_unref (loop) |
242 | |
252 | |
243 | Ref/unref can be used to add or remove a refcount on the event loop: Every |
253 | Ref/unref can be used to add or remove a reference count on the event |
244 | watcher keeps one reference. If you have a long-runing watcher you never |
254 | loop: Every watcher keeps one reference, and as long as the reference |
245 | unregister that should not keep ev_loop from running, ev_unref() after |
255 | count is nonzero, C<ev_loop> will not return on its own. If you have |
246 | starting, and ev_ref() before stopping it. Libev itself uses this for |
256 | a watcher you never unregister that should not keep C<ev_loop> from |
247 | example for its internal signal pipe: It is not visible to you as a user |
257 | returning, ev_unref() after starting, and ev_ref() before stopping it. For |
248 | and should not keep C<ev_loop> from exiting if the work is done. It is |
258 | example, libev itself uses this for its internal signal pipe: It is not |
249 | also an excellent way to do this for generic recurring timers or from |
259 | visible to the libev user and should not keep C<ev_loop> from exiting if |
250 | within third-party libraries. Just remember to unref after start and ref |
260 | no event watchers registered by it are active. It is also an excellent |
251 | before stop. |
261 | way to do this for generic recurring timers or from within third-party |
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262 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
252 | |
263 | |
253 | =back |
264 | =back |
254 | |
265 | |
255 | =head1 ANATOMY OF A WATCHER |
266 | =head1 ANATOMY OF A WATCHER |
256 | |
267 | |
257 | A watcher is a structure that you create and register to record your |
268 | A watcher is a structure that you create and register to record your |
258 | interest in some event. For instance, if you want to wait for STDIN to |
269 | interest in some event. For instance, if you want to wait for STDIN to |
259 | become readable, you would create an ev_io watcher for that: |
270 | become readable, you would create an C<ev_io> watcher for that: |
260 | |
271 | |
261 | static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
272 | static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
262 | { |
273 | { |
263 | ev_io_stop (w); |
274 | ev_io_stop (w); |
264 | ev_unloop (loop, EVUNLOOP_ALL); |
275 | ev_unloop (loop, EVUNLOOP_ALL); |
… | |
… | |
293 | |
304 | |
294 | As long as your watcher is active (has been started but not stopped) you |
305 | As long as your watcher is active (has been started but not stopped) you |
295 | must not touch the values stored in it. Most specifically you must never |
306 | must not touch the values stored in it. Most specifically you must never |
296 | reinitialise it or call its set method. |
307 | reinitialise it or call its set method. |
297 | |
308 | |
298 | You cna check whether an event is active by calling the C<ev_is_active |
309 | You can check whether an event is active by calling the C<ev_is_active |
299 | (watcher *)> macro. To see whether an event is outstanding (but the |
310 | (watcher *)> macro. To see whether an event is outstanding (but the |
300 | callback for it has not been called yet) you cna use the C<ev_is_pending |
311 | callback for it has not been called yet) you can use the C<ev_is_pending |
301 | (watcher *)> macro. |
312 | (watcher *)> macro. |
302 | |
313 | |
303 | Each and every callback receives the event loop pointer as first, the |
314 | Each and every callback receives the event loop pointer as first, the |
304 | registered watcher structure as second, and a bitset of received events as |
315 | registered watcher structure as second, and a bitset of received events as |
305 | third argument. |
316 | third argument. |
306 | |
317 | |
307 | The rceeived events usually include a single bit per event type received |
318 | The received events usually include a single bit per event type received |
308 | (you can receive multiple events at the same time). The possible bit masks |
319 | (you can receive multiple events at the same time). The possible bit masks |
309 | are: |
320 | are: |
310 | |
321 | |
311 | =over 4 |
322 | =over 4 |
312 | |
323 | |
313 | =item EV_READ |
324 | =item C<EV_READ> |
314 | |
325 | |
315 | =item EV_WRITE |
326 | =item C<EV_WRITE> |
316 | |
327 | |
317 | The file descriptor in the ev_io watcher has become readable and/or |
328 | The file descriptor in the C<ev_io> watcher has become readable and/or |
318 | writable. |
329 | writable. |
319 | |
330 | |
320 | =item EV_TIMEOUT |
331 | =item C<EV_TIMEOUT> |
321 | |
332 | |
322 | The ev_timer watcher has timed out. |
333 | The C<ev_timer> watcher has timed out. |
323 | |
334 | |
324 | =item EV_PERIODIC |
335 | =item C<EV_PERIODIC> |
325 | |
336 | |
326 | The ev_periodic watcher has timed out. |
337 | The C<ev_periodic> watcher has timed out. |
327 | |
338 | |
328 | =item EV_SIGNAL |
339 | =item C<EV_SIGNAL> |
329 | |
340 | |
330 | The signal specified in the ev_signal watcher has been received by a thread. |
341 | The signal specified in the C<ev_signal> watcher has been received by a thread. |
331 | |
342 | |
332 | =item EV_CHILD |
343 | =item C<EV_CHILD> |
333 | |
344 | |
334 | The pid specified in the ev_child watcher has received a status change. |
345 | The pid specified in the C<ev_child> watcher has received a status change. |
335 | |
346 | |
336 | =item EV_IDLE |
347 | =item C<EV_IDLE> |
337 | |
348 | |
338 | The ev_idle watcher has determined that you have nothing better to do. |
349 | The C<ev_idle> watcher has determined that you have nothing better to do. |
339 | |
350 | |
340 | =item EV_PREPARE |
351 | =item C<EV_PREPARE> |
341 | |
352 | |
342 | =item EV_CHECK |
353 | =item C<EV_CHECK> |
343 | |
354 | |
344 | All ev_prepare watchers are invoked just I<before> C<ev_loop> starts |
355 | All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts |
345 | to gather new events, and all ev_check watchers are invoked just after |
356 | to gather new events, and all C<ev_check> watchers are invoked just after |
346 | C<ev_loop> has gathered them, but before it invokes any callbacks for any |
357 | C<ev_loop> has gathered them, but before it invokes any callbacks for any |
347 | received events. Callbacks of both watcher types can start and stop as |
358 | received events. Callbacks of both watcher types can start and stop as |
348 | many watchers as they want, and all of them will be taken into account |
359 | many watchers as they want, and all of them will be taken into account |
349 | (for example, a ev_prepare watcher might start an idle watcher to keep |
360 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
350 | C<ev_loop> from blocking). |
361 | C<ev_loop> from blocking). |
351 | |
362 | |
352 | =item EV_ERROR |
363 | =item C<EV_ERROR> |
353 | |
364 | |
354 | An unspecified error has occured, the watcher has been stopped. This might |
365 | An unspecified error has occured, the watcher has been stopped. This might |
355 | happen because the watcher could not be properly started because libev |
366 | happen because the watcher could not be properly started because libev |
356 | ran out of memory, a file descriptor was found to be closed or any other |
367 | ran out of memory, a file descriptor was found to be closed or any other |
357 | problem. You best act on it by reporting the problem and somehow coping |
368 | problem. You best act on it by reporting the problem and somehow coping |
… | |
… | |
366 | =back |
377 | =back |
367 | |
378 | |
368 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
379 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
369 | |
380 | |
370 | Each watcher has, by default, a member C<void *data> that you can change |
381 | Each watcher has, by default, a member C<void *data> that you can change |
371 | and read at any time, libev will completely ignore it. This cna be used |
382 | and read at any time, libev will completely ignore it. This can be used |
372 | to associate arbitrary data with your watcher. If you need more data and |
383 | to associate arbitrary data with your watcher. If you need more data and |
373 | don't want to allocate memory and store a pointer to it in that data |
384 | don't want to allocate memory and store a pointer to it in that data |
374 | member, you can also "subclass" the watcher type and provide your own |
385 | member, you can also "subclass" the watcher type and provide your own |
375 | data: |
386 | data: |
376 | |
387 | |
… | |
… | |
398 | =head1 WATCHER TYPES |
409 | =head1 WATCHER TYPES |
399 | |
410 | |
400 | This section describes each watcher in detail, but will not repeat |
411 | This section describes each watcher in detail, but will not repeat |
401 | information given in the last section. |
412 | information given in the last section. |
402 | |
413 | |
403 | =head2 struct ev_io - is my file descriptor readable or writable |
414 | =head2 C<ev_io> - is this file descriptor readable or writable |
404 | |
415 | |
405 | I/O watchers check whether a file descriptor is readable or writable |
416 | I/O watchers check whether a file descriptor is readable or writable |
406 | in each iteration of the event loop (This behaviour is called |
417 | in each iteration of the event loop (This behaviour is called |
407 | level-triggering because you keep receiving events as long as the |
418 | level-triggering because you keep receiving events as long as the |
408 | condition persists. Remember you cna stop the watcher if you don't want to |
419 | condition persists. Remember you can stop the watcher if you don't want to |
409 | act on the event and neither want to receive future events). |
420 | act on the event and neither want to receive future events). |
410 | |
421 | |
|
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422 | In general you can register as many read and/or write event watchers oer |
|
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423 | fd as you want (as long as you don't confuse yourself). Setting all file |
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424 | descriptors to non-blocking mode is also usually a good idea (but not |
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425 | required if you know what you are doing). |
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426 | |
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427 | You have to be careful with dup'ed file descriptors, though. Some backends |
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428 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
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429 | descriptors correctly if you register interest in two or more fds pointing |
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430 | to the same file/socket etc. description. |
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431 | |
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432 | If you must do this, then force the use of a known-to-be-good backend |
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433 | (at the time of this writing, this includes only EVMETHOD_SELECT and |
|
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434 | EVMETHOD_POLL). |
|
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435 | |
411 | =over 4 |
436 | =over 4 |
412 | |
437 | |
413 | =item ev_io_init (ev_io *, callback, int fd, int events) |
438 | =item ev_io_init (ev_io *, callback, int fd, int events) |
414 | |
439 | |
415 | =item ev_io_set (ev_io *, int fd, int events) |
440 | =item ev_io_set (ev_io *, int fd, int events) |
416 | |
441 | |
417 | Configures an ev_io watcher. The fd is the file descriptor to rceeive |
442 | Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive |
418 | events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ | |
443 | events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ | |
419 | EV_WRITE> to receive the given events. |
444 | EV_WRITE> to receive the given events. |
420 | |
445 | |
421 | =back |
446 | =back |
422 | |
447 | |
423 | =head2 struct ev_timer - relative and optionally recurring timeouts |
448 | =head2 C<ev_timer> - relative and optionally recurring timeouts |
424 | |
449 | |
425 | Timer watchers are simple relative timers that generate an event after a |
450 | Timer watchers are simple relative timers that generate an event after a |
426 | given time, and optionally repeating in regular intervals after that. |
451 | given time, and optionally repeating in regular intervals after that. |
427 | |
452 | |
428 | The timers are based on real time, that is, if you register an event that |
453 | The timers are based on real time, that is, if you register an event that |
429 | times out after an hour and youreset your system clock to last years |
454 | times out after an hour and youreset your system clock to last years |
430 | time, it will still time out after (roughly) and hour. "Roughly" because |
455 | time, it will still time out after (roughly) and hour. "Roughly" because |
431 | detecting time jumps is hard, and soem inaccuracies are unavoidable (the |
456 | detecting time jumps is hard, and soem inaccuracies are unavoidable (the |
432 | monotonic clock option helps a lot here). |
457 | monotonic clock option helps a lot here). |
433 | |
458 | |
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|
459 | The relative timeouts are calculated relative to the C<ev_now ()> |
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460 | time. This is usually the right thing as this timestamp refers to the time |
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|
461 | of the event triggering whatever timeout you are modifying/starting. If |
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462 | you suspect event processing to be delayed and you *need* to base the timeout |
|
|
463 | ion the current time, use something like this to adjust for this: |
|
|
464 | |
|
|
465 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
|
|
466 | |
434 | =over 4 |
467 | =over 4 |
435 | |
468 | |
436 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
469 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
437 | |
470 | |
438 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
471 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
… | |
… | |
460 | |
493 | |
461 | This sounds a bit complicated, but here is a useful and typical |
494 | This sounds a bit complicated, but here is a useful and typical |
462 | example: Imagine you have a tcp connection and you want a so-called idle |
495 | example: Imagine you have a tcp connection and you want a so-called idle |
463 | timeout, that is, you want to be called when there have been, say, 60 |
496 | timeout, that is, you want to be called when there have been, say, 60 |
464 | seconds of inactivity on the socket. The easiest way to do this is to |
497 | seconds of inactivity on the socket. The easiest way to do this is to |
465 | configure an ev_timer with after=repeat=60 and calling ev_timer_again each |
498 | configure an C<ev_timer> with after=repeat=60 and calling ev_timer_again each |
466 | time you successfully read or write some data. If you go into an idle |
499 | time you successfully read or write some data. If you go into an idle |
467 | state where you do not expect data to travel on the socket, you can stop |
500 | state where you do not expect data to travel on the socket, you can stop |
468 | the timer, and again will automatically restart it if need be. |
501 | the timer, and again will automatically restart it if need be. |
469 | |
502 | |
470 | =back |
503 | =back |
471 | |
504 | |
472 | =head2 ev_periodic - to cron or not to cron it |
505 | =head2 C<ev_periodic> - to cron or not to cron |
473 | |
506 | |
474 | Periodic watchers are also timers of a kind, but they are very versatile |
507 | Periodic watchers are also timers of a kind, but they are very versatile |
475 | (and unfortunately a bit complex). |
508 | (and unfortunately a bit complex). |
476 | |
509 | |
477 | Unlike ev_timer's, they are not based on real time (or relative time) |
510 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
478 | but on wallclock time (absolute time). You can tell a periodic watcher |
511 | but on wallclock time (absolute time). You can tell a periodic watcher |
479 | to trigger "at" some specific point in time. For example, if you tell a |
512 | to trigger "at" some specific point in time. For example, if you tell a |
480 | periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now () |
513 | periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now () |
481 | + 10.>) and then reset your system clock to the last year, then it will |
514 | + 10.>) and then reset your system clock to the last year, then it will |
482 | take a year to trigger the event (unlike an ev_timer, which would trigger |
515 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
483 | roughly 10 seconds later and of course not if you reset your system time |
516 | roughly 10 seconds later and of course not if you reset your system time |
484 | again). |
517 | again). |
485 | |
518 | |
486 | They can also be used to implement vastly more complex timers, such as |
519 | They can also be used to implement vastly more complex timers, such as |
487 | triggering an event on eahc midnight, local time. |
520 | triggering an event on eahc midnight, local time. |
… | |
… | |
516 | |
549 | |
517 | ev_periodic_set (&periodic, 0., 3600., 0); |
550 | ev_periodic_set (&periodic, 0., 3600., 0); |
518 | |
551 | |
519 | This doesn't mean there will always be 3600 seconds in between triggers, |
552 | This doesn't mean there will always be 3600 seconds in between triggers, |
520 | but only that the the callback will be called when the system time shows a |
553 | but only that the the callback will be called when the system time shows a |
521 | full hour (UTC), or more correct, when the system time is evenly divisible |
554 | full hour (UTC), or more correctly, when the system time is evenly divisible |
522 | by 3600. |
555 | by 3600. |
523 | |
556 | |
524 | Another way to think about it (for the mathematically inclined) is that |
557 | Another way to think about it (for the mathematically inclined) is that |
525 | ev_periodic will try to run the callback in this mode at the next possible |
558 | C<ev_periodic> will try to run the callback in this mode at the next possible |
526 | time where C<time = at (mod interval)>, regardless of any time jumps. |
559 | time where C<time = at (mod interval)>, regardless of any time jumps. |
527 | |
560 | |
528 | =item * manual reschedule mode (reschedule_cb = callback) |
561 | =item * manual reschedule mode (reschedule_cb = callback) |
529 | |
562 | |
530 | In this mode the values for C<interval> and C<at> are both being |
563 | In this mode the values for C<interval> and C<at> are both being |
531 | ignored. Instead, each time the periodic watcher gets scheduled, the |
564 | ignored. Instead, each time the periodic watcher gets scheduled, the |
532 | reschedule callback will be called with the watcher as first, and the |
565 | reschedule callback will be called with the watcher as first, and the |
533 | current time as second argument. |
566 | current time as second argument. |
534 | |
567 | |
535 | NOTE: I<This callback MUST NOT stop or destroy the periodic or any other |
568 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
536 | periodic watcher, ever, or make any event loop modificstions>. If you need |
569 | ever, or make any event loop modifications>. If you need to stop it, |
537 | to stop it, return 1e30 (or so, fudge fudge) and stop it afterwards. |
570 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
|
|
571 | starting a prepare watcher). |
538 | |
572 | |
539 | Its prototype is c<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
573 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
540 | ev_tstamp now)>, e.g.: |
574 | ev_tstamp now)>, e.g.: |
541 | |
575 | |
542 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
576 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
543 | { |
577 | { |
544 | return now + 60.; |
578 | return now + 60.; |
… | |
… | |
547 | It must return the next time to trigger, based on the passed time value |
581 | It must return the next time to trigger, based on the passed time value |
548 | (that is, the lowest time value larger than to the second argument). It |
582 | (that is, the lowest time value larger than to the second argument). It |
549 | will usually be called just before the callback will be triggered, but |
583 | will usually be called just before the callback will be triggered, but |
550 | might be called at other times, too. |
584 | might be called at other times, too. |
551 | |
585 | |
|
|
586 | NOTE: I<< This callback must always return a time that is later than the |
|
|
587 | passed C<now> value >>. Not even C<now> itself will do, it I<must> be larger. |
|
|
588 | |
552 | This can be used to create very complex timers, such as a timer that |
589 | This can be used to create very complex timers, such as a timer that |
553 | triggers on each midnight, local time. To do this, you would calculate the |
590 | triggers on each midnight, local time. To do this, you would calculate the |
554 | next midnight after C<now> and return the timestamp value for this. How you do this |
591 | next midnight after C<now> and return the timestamp value for this. How |
555 | is, again, up to you (but it is not trivial). |
592 | you do this is, again, up to you (but it is not trivial, which is the main |
|
|
593 | reason I omitted it as an example). |
556 | |
594 | |
557 | =back |
595 | =back |
558 | |
596 | |
559 | =item ev_periodic_again (loop, ev_periodic *) |
597 | =item ev_periodic_again (loop, ev_periodic *) |
560 | |
598 | |
… | |
… | |
563 | a different time than the last time it was called (e.g. in a crond like |
601 | a different time than the last time it was called (e.g. in a crond like |
564 | program when the crontabs have changed). |
602 | program when the crontabs have changed). |
565 | |
603 | |
566 | =back |
604 | =back |
567 | |
605 | |
568 | =head2 ev_signal - signal me when a signal gets signalled |
606 | =head2 C<ev_signal> - signal me when a signal gets signalled |
569 | |
607 | |
570 | Signal watchers will trigger an event when the process receives a specific |
608 | Signal watchers will trigger an event when the process receives a specific |
571 | signal one or more times. Even though signals are very asynchronous, libev |
609 | signal one or more times. Even though signals are very asynchronous, libev |
572 | will try its best to deliver signals synchronously, i.e. as part of the |
610 | will try it's best to deliver signals synchronously, i.e. as part of the |
573 | normal event processing, like any other event. |
611 | normal event processing, like any other event. |
574 | |
612 | |
575 | You cna configure as many watchers as you like per signal. Only when the |
613 | You can configure as many watchers as you like per signal. Only when the |
576 | first watcher gets started will libev actually register a signal watcher |
614 | first watcher gets started will libev actually register a signal watcher |
577 | with the kernel (thus it coexists with your own signal handlers as long |
615 | with the kernel (thus it coexists with your own signal handlers as long |
578 | as you don't register any with libev). Similarly, when the last signal |
616 | as you don't register any with libev). Similarly, when the last signal |
579 | watcher for a signal is stopped libev will reset the signal handler to |
617 | watcher for a signal is stopped libev will reset the signal handler to |
580 | SIG_DFL (regardless of what it was set to before). |
618 | SIG_DFL (regardless of what it was set to before). |
… | |
… | |
588 | Configures the watcher to trigger on the given signal number (usually one |
626 | Configures the watcher to trigger on the given signal number (usually one |
589 | of the C<SIGxxx> constants). |
627 | of the C<SIGxxx> constants). |
590 | |
628 | |
591 | =back |
629 | =back |
592 | |
630 | |
593 | =head2 ev_child - wait for pid status changes |
631 | =head2 C<ev_child> - wait for pid status changes |
594 | |
632 | |
595 | Child watchers trigger when your process receives a SIGCHLD in response to |
633 | Child watchers trigger when your process receives a SIGCHLD in response to |
596 | some child status changes (most typically when a child of yours dies). |
634 | some child status changes (most typically when a child of yours dies). |
597 | |
635 | |
598 | =over 4 |
636 | =over 4 |
… | |
… | |
602 | =item ev_child_set (ev_child *, int pid) |
640 | =item ev_child_set (ev_child *, int pid) |
603 | |
641 | |
604 | Configures the watcher to wait for status changes of process C<pid> (or |
642 | Configures the watcher to wait for status changes of process C<pid> (or |
605 | I<any> process if C<pid> is specified as C<0>). The callback can look |
643 | I<any> process if C<pid> is specified as C<0>). The callback can look |
606 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
644 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
607 | the status word (use the macros from C<sys/wait.h>). The C<rpid> member |
645 | the status word (use the macros from C<sys/wait.h> and see your systems |
608 | contains the pid of the process causing the status change. |
646 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
|
|
647 | process causing the status change. |
609 | |
648 | |
610 | =back |
649 | =back |
611 | |
650 | |
612 | =head2 ev_idle - when you've got nothing better to do |
651 | =head2 C<ev_idle> - when you've got nothing better to do |
613 | |
652 | |
614 | Idle watchers trigger events when there are no other I/O or timer (or |
653 | Idle watchers trigger events when there are no other events are pending |
615 | periodic) events pending. That is, as long as your process is busy |
654 | (prepare, check and other idle watchers do not count). That is, as long |
616 | handling sockets or timeouts it will not be called. But when your process |
655 | as your process is busy handling sockets or timeouts (or even signals, |
617 | is idle all idle watchers are being called again and again - until |
656 | imagine) it will not be triggered. But when your process is idle all idle |
|
|
657 | watchers are being called again and again, once per event loop iteration - |
618 | stopped, that is, or your process receives more events. |
658 | until stopped, that is, or your process receives more events and becomes |
|
|
659 | busy. |
619 | |
660 | |
620 | The most noteworthy effect is that as long as any idle watchers are |
661 | The most noteworthy effect is that as long as any idle watchers are |
621 | active, the process will not block when waiting for new events. |
662 | active, the process will not block when waiting for new events. |
622 | |
663 | |
623 | Apart from keeping your process non-blocking (which is a useful |
664 | Apart from keeping your process non-blocking (which is a useful |
… | |
… | |
633 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
674 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
634 | believe me. |
675 | believe me. |
635 | |
676 | |
636 | =back |
677 | =back |
637 | |
678 | |
638 | =head2 prepare and check - your hooks into the event loop |
679 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop |
639 | |
680 | |
640 | Prepare and check watchers usually (but not always) are used in |
681 | Prepare and check watchers are usually (but not always) used in tandem: |
641 | tandom. Prepare watchers get invoked before the process blocks and check |
682 | prepare watchers get invoked before the process blocks and check watchers |
642 | watchers afterwards. |
683 | afterwards. |
643 | |
684 | |
644 | Their main purpose is to integrate other event mechanisms into libev. This |
685 | Their main purpose is to integrate other event mechanisms into libev. This |
645 | could be used, for example, to track variable changes, implement your own |
686 | could be used, for example, to track variable changes, implement your own |
646 | watchers, integrate net-snmp or a coroutine library and lots more. |
687 | watchers, integrate net-snmp or a coroutine library and lots more. |
647 | |
688 | |
648 | This is done by examining in each prepare call which file descriptors need |
689 | This is done by examining in each prepare call which file descriptors need |
649 | to be watched by the other library, registering ev_io watchers for them |
690 | to be watched by the other library, registering C<ev_io> watchers for |
650 | and starting an ev_timer watcher for any timeouts (many libraries provide |
691 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
651 | just this functionality). Then, in the check watcher you check for any |
692 | provide just this functionality). Then, in the check watcher you check for |
652 | events that occured (by making your callbacks set soem flags for example) |
693 | any events that occured (by checking the pending status of all watchers |
653 | and call back into the library. |
694 | and stopping them) and call back into the library. The I/O and timer |
|
|
695 | callbacks will never actually be called (but must be valid nevertheless, |
|
|
696 | because you never know, you know?). |
654 | |
697 | |
655 | As another example, the perl Coro module uses these hooks to integrate |
698 | As another example, the Perl Coro module uses these hooks to integrate |
656 | coroutines into libev programs, by yielding to other active coroutines |
699 | coroutines into libev programs, by yielding to other active coroutines |
657 | during each prepare and only letting the process block if no coroutines |
700 | during each prepare and only letting the process block if no coroutines |
658 | are ready to run. |
701 | are ready to run (it's actually more complicated: it only runs coroutines |
|
|
702 | with priority higher than or equal to the event loop and one coroutine |
|
|
703 | of lower priority, but only once, using idle watchers to keep the event |
|
|
704 | loop from blocking if lower-priority coroutines are active, thus mapping |
|
|
705 | low-priority coroutines to idle/background tasks). |
659 | |
706 | |
660 | =over 4 |
707 | =over 4 |
661 | |
708 | |
662 | =item ev_prepare_init (ev_prepare *, callback) |
709 | =item ev_prepare_init (ev_prepare *, callback) |
663 | |
710 | |
664 | =item ev_check_init (ev_check *, callback) |
711 | =item ev_check_init (ev_check *, callback) |
665 | |
712 | |
666 | Initialises and configures the prepare or check watcher - they have no |
713 | Initialises and configures the prepare or check watcher - they have no |
667 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
714 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
668 | macros, but using them is utterly, utterly pointless. |
715 | macros, but using them is utterly, utterly and completely pointless. |
669 | |
716 | |
670 | =back |
717 | =back |
671 | |
718 | |
672 | =head1 OTHER FUNCTIONS |
719 | =head1 OTHER FUNCTIONS |
673 | |
720 | |
674 | There are some other fucntions of possible interest. Described. Here. Now. |
721 | There are some other functions of possible interest. Described. Here. Now. |
675 | |
722 | |
676 | =over 4 |
723 | =over 4 |
677 | |
724 | |
678 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback) |
725 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback) |
679 | |
726 | |
… | |
… | |
681 | callback on whichever event happens first and automatically stop both |
728 | callback on whichever event happens first and automatically stop both |
682 | watchers. This is useful if you want to wait for a single event on an fd |
729 | watchers. This is useful if you want to wait for a single event on an fd |
683 | or timeout without havign to allocate/configure/start/stop/free one or |
730 | or timeout without havign to allocate/configure/start/stop/free one or |
684 | more watchers yourself. |
731 | more watchers yourself. |
685 | |
732 | |
686 | If C<fd> is less than 0, then no I/O watcher will be started and events is |
733 | If C<fd> is less than 0, then no I/O watcher will be started and events |
687 | ignored. Otherwise, an ev_io watcher for the given C<fd> and C<events> set |
734 | is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and |
688 | will be craeted and started. |
735 | C<events> set will be craeted and started. |
689 | |
736 | |
690 | If C<timeout> is less than 0, then no timeout watcher will be |
737 | If C<timeout> is less than 0, then no timeout watcher will be |
691 | started. Otherwise an ev_timer watcher with after = C<timeout> (and repeat |
738 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
692 | = 0) will be started. |
739 | repeat = 0) will be started. While C<0> is a valid timeout, it is of |
|
|
740 | dubious value. |
693 | |
741 | |
694 | The callback has the type C<void (*cb)(int revents, void *arg)> and |
742 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
695 | gets passed an events set (normally a combination of EV_ERROR, EV_READ, |
743 | passed an C<revents> set like normal event callbacks (a combination of |
696 | EV_WRITE or EV_TIMEOUT) and the C<arg> value passed to C<ev_once>: |
744 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
|
|
745 | value passed to C<ev_once>: |
697 | |
746 | |
698 | static void stdin_ready (int revents, void *arg) |
747 | static void stdin_ready (int revents, void *arg) |
699 | { |
748 | { |
700 | if (revents & EV_TIMEOUT) |
749 | if (revents & EV_TIMEOUT) |
701 | /* doh, nothing entered */ |
750 | /* doh, nothing entered */; |
702 | else if (revents & EV_READ) |
751 | else if (revents & EV_READ) |
703 | /* stdin might have data for us, joy! */ |
752 | /* stdin might have data for us, joy! */; |
704 | } |
753 | } |
705 | |
754 | |
706 | ev_once (STDIN_FILENO, EV_READm 10., stdin_ready, 0); |
755 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
707 | |
756 | |
708 | =item ev_feed_event (loop, watcher, int events) |
757 | =item ev_feed_event (loop, watcher, int events) |
709 | |
758 | |
710 | Feeds the given event set into the event loop, as if the specified event |
759 | Feeds the given event set into the event loop, as if the specified event |
711 | has happened for the specified watcher (which must be a pointer to an |
760 | had happened for the specified watcher (which must be a pointer to an |
712 | initialised but not necessarily active event watcher). |
761 | initialised but not necessarily started event watcher). |
713 | |
762 | |
714 | =item ev_feed_fd_event (loop, int fd, int revents) |
763 | =item ev_feed_fd_event (loop, int fd, int revents) |
715 | |
764 | |
716 | Feed an event on the given fd, as if a file descriptor backend detected it. |
765 | Feed an event on the given fd, as if a file descriptor backend detected |
|
|
766 | the given events it. |
717 | |
767 | |
718 | =item ev_feed_signal_event (loop, int signum) |
768 | =item ev_feed_signal_event (loop, int signum) |
719 | |
769 | |
720 | Feed an event as if the given signal occured (loop must be the default loop!). |
770 | Feed an event as if the given signal occured (loop must be the default loop!). |
721 | |
771 | |
722 | =back |
772 | =back |
723 | |
773 | |
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|
774 | =head1 LIBEVENT EMULATION |
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|
775 | |
|
|
776 | TBD. |
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|
777 | |
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778 | =head1 C++ SUPPORT |
|
|
779 | |
|
|
780 | TBD. |
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781 | |
724 | =head1 AUTHOR |
782 | =head1 AUTHOR |
725 | |
783 | |
726 | Marc Lehmann <libev@schmorp.de>. |
784 | Marc Lehmann <libev@schmorp.de>. |
727 | |
785 | |