… | |
… | |
8 | |
8 | |
9 | =head1 DESCRIPTION |
9 | =head1 DESCRIPTION |
10 | |
10 | |
11 | Libev is an event loop: you register interest in certain events (such as a |
11 | Libev is an event loop: you register interest in certain events (such as a |
12 | file descriptor being readable or a timeout occuring), and it will manage |
12 | file descriptor being readable or a timeout occuring), and it will manage |
13 | these event sources and provide your program events. |
13 | these event sources and provide your program with events. |
14 | |
14 | |
15 | To do this, it must take more or less complete control over your process |
15 | To do this, it must take more or less complete control over your process |
16 | (or thread) by executing the I<event loop> handler, and will then |
16 | (or thread) by executing the I<event loop> handler, and will then |
17 | communicate events via a callback mechanism. |
17 | communicate events via a callback mechanism. |
18 | |
18 | |
… | |
… | |
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 AND OTHER GLOBAL FUNCTIONS |
43 | |
45 | |
44 | Libev represents time as a single floating point number. This type is |
46 | Libev represents time as a single floating point number, representing the |
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47 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
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48 | the beginning of 1970, details are complicated, don't ask). This type is |
45 | 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 |
46 | to the double type in C. |
50 | to the double type in C. |
47 | |
51 | |
48 | =over 4 |
52 | =over 4 |
49 | |
53 | |
… | |
… | |
59 | you linked against by calling the functions C<ev_version_major> and |
63 | you linked against by calling the functions C<ev_version_major> and |
60 | C<ev_version_minor>. If you want, you can compare against the global |
64 | C<ev_version_minor>. If you want, you can compare against the global |
61 | symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the |
65 | symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the |
62 | version of the library your program was compiled against. |
66 | version of the library your program was compiled against. |
63 | |
67 | |
64 | Usually, its a good idea to terminate if the major versions mismatch, |
68 | Usually, it's a good idea to terminate if the major versions mismatch, |
65 | as this indicates an incompatible change. Minor versions are usually |
69 | as this indicates an incompatible change. Minor versions are usually |
66 | compatible to older versions, so a larger minor version alone is usually |
70 | compatible to older versions, so a larger minor version alone is usually |
67 | not a problem. |
71 | not a problem. |
68 | |
72 | |
69 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
73 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
70 | |
74 | |
71 | Sets the allocation function to use (the prototype is similar to the |
75 | Sets the allocation function to use (the prototype is similar to the |
72 | realloc function). It is used to allocate and free memory (no surprises |
76 | realloc C function, the semantics are identical). It is used to allocate |
73 | here). If it returns zero when memory needs to be allocated, the library |
77 | and free memory (no surprises here). If it returns zero when memory |
74 | might abort or take some potentially destructive action. The default is |
78 | needs to be allocated, the library might abort or take some potentially |
75 | your system realloc function. |
79 | destructive action. The default is your system realloc function. |
76 | |
80 | |
77 | You could override this function in high-availability programs to, say, |
81 | You could override this function in high-availability programs to, say, |
78 | free some memory if it cannot allocate memory, to use a special allocator, |
82 | free some memory if it cannot allocate memory, to use a special allocator, |
79 | or even to sleep a while and retry until some memory is available. |
83 | or even to sleep a while and retry until some memory is available. |
80 | |
84 | |
… | |
… | |
82 | |
86 | |
83 | Set the callback function to call on a retryable syscall error (such |
87 | Set the callback function to call on a retryable syscall error (such |
84 | as failed select, poll, epoll_wait). The message is a printable string |
88 | as failed select, poll, epoll_wait). The message is a printable string |
85 | indicating the system call or subsystem causing the problem. If this |
89 | indicating the system call or subsystem causing the problem. If this |
86 | callback is set, then libev will expect it to remedy the sitution, no |
90 | callback is set, then libev will expect it to remedy the sitution, no |
87 | matter what, when it returns. That is, libev will geenrally retry the |
91 | matter what, when it returns. That is, libev will generally retry the |
88 | requested operation, or, if the condition doesn't go away, do bad stuff |
92 | requested operation, or, if the condition doesn't go away, do bad stuff |
89 | (such as abort). |
93 | (such as abort). |
90 | |
94 | |
91 | =back |
95 | =back |
92 | |
96 | |
… | |
… | |
96 | types of such loops, the I<default> loop, which supports signals and child |
100 | types of such loops, the I<default> loop, which supports signals and child |
97 | events, and dynamically created loops which do not. |
101 | events, and dynamically created loops which do not. |
98 | |
102 | |
99 | If you use threads, a common model is to run the default event loop |
103 | If you use threads, a common model is to run the default event loop |
100 | in your main thread (or in a separate thrad) and for each thread you |
104 | in your main thread (or in a separate thrad) and for each thread you |
101 | create, you also create another event loop. Libev itself does no lockign |
105 | create, you also create another event loop. Libev itself does no locking |
102 | whatsoever, so if you mix calls to different event loops, make sure you |
106 | whatsoever, so if you mix calls to the same event loop in different |
103 | lock (this is usually a bad idea, though, even if done right). |
107 | threads, make sure you lock (this is usually a bad idea, though, even if |
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108 | done correctly, because it's hideous and inefficient). |
104 | |
109 | |
105 | =over 4 |
110 | =over 4 |
106 | |
111 | |
107 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
112 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
108 | |
113 | |
… | |
… | |
113 | |
118 | |
114 | If you don't know what event loop to use, use the one returned from this |
119 | If you don't know what event loop to use, use the one returned from this |
115 | function. |
120 | function. |
116 | |
121 | |
117 | The flags argument can be used to specify special behaviour or specific |
122 | The flags argument can be used to specify special behaviour or specific |
118 | backends to use, and is usually specified as 0 (or EVFLAG_AUTO) |
123 | backends to use, and is usually specified as 0 (or EVFLAG_AUTO). |
119 | |
124 | |
120 | It supports the following flags: |
125 | It supports the following flags: |
121 | |
126 | |
122 | =over 4 |
127 | =over 4 |
123 | |
128 | |
124 | =item EVFLAG_AUTO |
129 | =item C<EVFLAG_AUTO> |
125 | |
130 | |
126 | The default flags value. Use this if you have no clue (its the right |
131 | The default flags value. Use this if you have no clue (it's the right |
127 | thing, believe me). |
132 | thing, believe me). |
128 | |
133 | |
129 | =item EVFLAG_NOENV |
134 | =item C<EVFLAG_NOENV> |
130 | |
135 | |
131 | If this flag bit is ored into the flag value then libev will I<not> look |
136 | If this flag bit is ored into the flag value (or the program runs setuid |
132 | at the environment variable C<LIBEV_FLAGS>. Otherwise (the default), this |
137 | or setgid) then libev will I<not> look at the environment variable |
133 | environment variable will override the flags completely. This is useful |
138 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
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139 | override the flags completely if it is found in the environment. This is |
134 | to try out specific backends to tets their performance, or to work around |
140 | useful to try out specific backends to test their performance, or to work |
135 | bugs. |
141 | around bugs. |
136 | |
142 | |
137 | =item EVMETHOD_SELECT portable select backend |
143 | =item C<EVMETHOD_SELECT> (portable select backend) |
138 | |
144 | |
139 | =item EVMETHOD_POLL poll backend (everywhere except windows) |
145 | =item C<EVMETHOD_POLL> (poll backend, available everywhere except on windows) |
140 | |
146 | |
141 | =item EVMETHOD_EPOLL linux only |
147 | =item C<EVMETHOD_EPOLL> (linux only) |
142 | |
148 | |
143 | =item EVMETHOD_KQUEUE some bsds only |
149 | =item C<EVMETHOD_KQUEUE> (some bsds only) |
144 | |
150 | |
145 | =item EVMETHOD_DEVPOLL solaris 8 only |
151 | =item C<EVMETHOD_DEVPOLL> (solaris 8 only) |
146 | |
152 | |
147 | =item EVMETHOD_PORT solaris 10 only |
153 | =item C<EVMETHOD_PORT> (solaris 10 only) |
148 | |
154 | |
149 | If one or more of these are ored into the flags value, then only these |
155 | If one or more of these are ored into the flags value, then only these |
150 | backends will be tried (in the reverse order as given here). If one are |
156 | backends will be tried (in the reverse order as given here). If one are |
151 | specified, any backend will do. |
157 | specified, any backend will do. |
152 | |
158 | |
… | |
… | |
161 | |
167 | |
162 | =item ev_default_destroy () |
168 | =item ev_default_destroy () |
163 | |
169 | |
164 | Destroys the default loop again (frees all memory and kernel state |
170 | Destroys the default loop again (frees all memory and kernel state |
165 | etc.). This stops all registered event watchers (by not touching them in |
171 | etc.). This stops all registered event watchers (by not touching them in |
166 | any way whatsoever, although you cnanot rely on this :). |
172 | any way whatsoever, although you cannot rely on this :). |
167 | |
173 | |
168 | =item ev_loop_destroy (loop) |
174 | =item ev_loop_destroy (loop) |
169 | |
175 | |
170 | Like C<ev_default_destroy>, but destroys an event loop created by an |
176 | Like C<ev_default_destroy>, but destroys an event loop created by an |
171 | earlier call to C<ev_loop_new>. |
177 | earlier call to C<ev_loop_new>. |
… | |
… | |
179 | |
185 | |
180 | You I<must> call this function after forking if and only if you want to |
186 | You I<must> call this function after forking if and only if you want to |
181 | use the event library in both processes. If you just fork+exec, you don't |
187 | use the event library in both processes. If you just fork+exec, you don't |
182 | have to call it. |
188 | have to call it. |
183 | |
189 | |
184 | The function itself is quite fast and its usually not a problem to call |
190 | The function itself is quite fast and it's usually not a problem to call |
185 | it just in case after a fork. To make this easy, the function will fit in |
191 | it just in case after a fork. To make this easy, the function will fit in |
186 | quite nicely into a call to C<pthread_atfork>: |
192 | quite nicely into a call to C<pthread_atfork>: |
187 | |
193 | |
188 | pthread_atfork (0, 0, ev_default_fork); |
194 | pthread_atfork (0, 0, ev_default_fork); |
189 | |
195 | |
… | |
… | |
196 | =item unsigned int ev_method (loop) |
202 | =item unsigned int ev_method (loop) |
197 | |
203 | |
198 | Returns one of the C<EVMETHOD_*> flags indicating the event backend in |
204 | Returns one of the C<EVMETHOD_*> flags indicating the event backend in |
199 | use. |
205 | use. |
200 | |
206 | |
201 | =item ev_tstamp = ev_now (loop) |
207 | =item ev_tstamp ev_now (loop) |
202 | |
208 | |
203 | Returns the current "event loop time", which is the time the event loop |
209 | Returns the current "event loop time", which is the time the event loop |
204 | got events and started processing them. This timestamp does not change |
210 | got events and started processing them. This timestamp does not change |
205 | as long as callbacks are being processed, and this is also the base time |
211 | as long as callbacks are being processed, and this is also the base time |
206 | used for relative timers. You can treat it as the timestamp of the event |
212 | used for relative timers. You can treat it as the timestamp of the event |
… | |
… | |
215 | If the flags argument is specified as 0, it will not return until either |
221 | If the flags argument is specified as 0, it will not return until either |
216 | no event watchers are active anymore or C<ev_unloop> was called. |
222 | no event watchers are active anymore or C<ev_unloop> was called. |
217 | |
223 | |
218 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
224 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
219 | those events and any outstanding ones, but will not block your process in |
225 | those events and any outstanding ones, but will not block your process in |
220 | case there are no events. |
226 | case there are no events and will return after one iteration of the loop. |
221 | |
227 | |
222 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
228 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
223 | neccessary) and will handle those and any outstanding ones. It will block |
229 | neccessary) and will handle those and any outstanding ones. It will block |
224 | your process until at least one new event arrives. |
230 | your process until at least one new event arrives, and will return after |
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231 | one iteration of the loop. |
225 | |
232 | |
226 | This flags value could be used to implement alternative looping |
233 | This flags value could be used to implement alternative looping |
227 | constructs, but the C<prepare> and C<check> watchers provide a better and |
234 | constructs, but the C<prepare> and C<check> watchers provide a better and |
228 | more generic mechanism. |
235 | more generic mechanism. |
229 | |
236 | |
230 | =item ev_unloop (loop, how) |
237 | =item ev_unloop (loop, how) |
231 | |
238 | |
232 | Can be used to make a call to C<ev_loop> return early. The C<how> argument |
239 | Can be used to make a call to C<ev_loop> return early (but only after it |
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240 | has processed all outstanding events). The C<how> argument must be either |
233 | must be either C<EVUNLOOP_ONCE>, which will make the innermost C<ev_loop> |
241 | C<EVUNLOOP_ONCE>, which will make the innermost C<ev_loop> call return, or |
234 | call return, or C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> |
242 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
235 | calls return. |
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236 | |
243 | |
237 | =item ev_ref (loop) |
244 | =item ev_ref (loop) |
238 | |
245 | |
239 | =item ev_unref (loop) |
246 | =item ev_unref (loop) |
240 | |
247 | |
241 | Ref/unref can be used to add or remove a refcount on the event loop: Every |
248 | Ref/unref can be used to add or remove a reference count on the event |
242 | watcher keeps one reference. If you have a long-runing watcher you never |
249 | loop: Every watcher keeps one reference, and as long as the reference |
243 | unregister that should not keep ev_loop from running, ev_unref() after |
250 | count is nonzero, C<ev_loop> will not return on its own. If you have |
244 | starting, and ev_ref() before stopping it. Libev itself uses this for |
251 | a watcher you never unregister that should not keep C<ev_loop> from |
245 | example for its internal signal pipe: It is not visible to you as a user |
252 | returning, ev_unref() after starting, and ev_ref() before stopping it. For |
246 | and should not keep C<ev_loop> from exiting if the work is done. It is |
253 | example, libev itself uses this for its internal signal pipe: It is not |
247 | also an excellent way to do this for generic recurring timers or from |
254 | visible to the libev user and should not keep C<ev_loop> from exiting if |
248 | within third-party libraries. Just remember to unref after start and ref |
255 | no event watchers registered by it are active. It is also an excellent |
249 | before stop. |
256 | way to do this for generic recurring timers or from within third-party |
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257 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
250 | |
258 | |
251 | =back |
259 | =back |
252 | |
260 | |
253 | =head1 ANATOMY OF A WATCHER |
261 | =head1 ANATOMY OF A WATCHER |
254 | |
262 | |
255 | A watcher is a structure that you create and register to record your |
263 | A watcher is a structure that you create and register to record your |
256 | interest in some event. For instance, if you want to wait for STDIN to |
264 | interest in some event. For instance, if you want to wait for STDIN to |
257 | become readable, you would create an ev_io watcher for that: |
265 | become readable, you would create an C<ev_io> watcher for that: |
258 | |
266 | |
259 | static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
267 | static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
260 | { |
268 | { |
261 | ev_io_stop (w); |
269 | ev_io_stop (w); |
262 | ev_unloop (loop, EVUNLOOP_ALL); |
270 | ev_unloop (loop, EVUNLOOP_ALL); |
… | |
… | |
291 | |
299 | |
292 | As long as your watcher is active (has been started but not stopped) you |
300 | As long as your watcher is active (has been started but not stopped) you |
293 | must not touch the values stored in it. Most specifically you must never |
301 | must not touch the values stored in it. Most specifically you must never |
294 | reinitialise it or call its set method. |
302 | reinitialise it or call its set method. |
295 | |
303 | |
296 | You cna check wether an event is active by calling the C<ev_is_active |
304 | You cna check whether an event is active by calling the C<ev_is_active |
297 | (watcher *)> macro. To see wether an event is outstanding (but the |
305 | (watcher *)> macro. To see whether an event is outstanding (but the |
298 | callback for it has not been called yet) you cna use the C<ev_is_pending |
306 | callback for it has not been called yet) you cna use the C<ev_is_pending |
299 | (watcher *)> macro. |
307 | (watcher *)> macro. |
300 | |
308 | |
301 | Each and every callback receives the event loop pointer as first, the |
309 | Each and every callback receives the event loop pointer as first, the |
302 | registered watcher structure as second, and a bitset of received events as |
310 | registered watcher structure as second, and a bitset of received events as |
… | |
… | |
306 | (you can receive multiple events at the same time). The possible bit masks |
314 | (you can receive multiple events at the same time). The possible bit masks |
307 | are: |
315 | are: |
308 | |
316 | |
309 | =over 4 |
317 | =over 4 |
310 | |
318 | |
311 | =item EV_READ |
319 | =item C<EV_READ> |
312 | |
320 | |
313 | =item EV_WRITE |
321 | =item C<EV_WRITE> |
314 | |
322 | |
315 | The file descriptor in the ev_io watcher has become readable and/or |
323 | The file descriptor in the C<ev_io> watcher has become readable and/or |
316 | writable. |
324 | writable. |
317 | |
325 | |
318 | =item EV_TIMEOUT |
326 | =item C<EV_TIMEOUT> |
319 | |
327 | |
320 | The ev_timer watcher has timed out. |
328 | The C<ev_timer> watcher has timed out. |
321 | |
329 | |
322 | =item EV_PERIODIC |
330 | =item C<EV_PERIODIC> |
323 | |
331 | |
324 | The ev_periodic watcher has timed out. |
332 | The C<ev_periodic> watcher has timed out. |
325 | |
333 | |
326 | =item EV_SIGNAL |
334 | =item C<EV_SIGNAL> |
327 | |
335 | |
328 | The signal specified in the ev_signal watcher has been received by a thread. |
336 | The signal specified in the C<ev_signal> watcher has been received by a thread. |
329 | |
337 | |
330 | =item EV_CHILD |
338 | =item C<EV_CHILD> |
331 | |
339 | |
332 | The pid specified in the ev_child watcher has received a status change. |
340 | The pid specified in the C<ev_child> watcher has received a status change. |
333 | |
341 | |
334 | =item EV_IDLE |
342 | =item C<EV_IDLE> |
335 | |
343 | |
336 | The ev_idle watcher has determined that you have nothing better to do. |
344 | The C<ev_idle> watcher has determined that you have nothing better to do. |
337 | |
345 | |
338 | =item EV_PREPARE |
346 | =item C<EV_PREPARE> |
339 | |
347 | |
340 | =item EV_CHECK |
348 | =item C<EV_CHECK> |
341 | |
349 | |
342 | All ev_prepare watchers are invoked just I<before> C<ev_loop> starts |
350 | All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts |
343 | to gather new events, and all ev_check watchers are invoked just after |
351 | to gather new events, and all C<ev_check> watchers are invoked just after |
344 | C<ev_loop> has gathered them, but before it invokes any callbacks for any |
352 | C<ev_loop> has gathered them, but before it invokes any callbacks for any |
345 | received events. Callbacks of both watcher types can start and stop as |
353 | received events. Callbacks of both watcher types can start and stop as |
346 | many watchers as they want, and all of them will be taken into account |
354 | many watchers as they want, and all of them will be taken into account |
347 | (for example, a ev_prepare watcher might start an idle watcher to keep |
355 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
348 | C<ev_loop> from blocking). |
356 | C<ev_loop> from blocking). |
349 | |
357 | |
350 | =item EV_ERROR |
358 | =item C<EV_ERROR> |
351 | |
359 | |
352 | An unspecified error has occured, the watcher has been stopped. This might |
360 | An unspecified error has occured, the watcher has been stopped. This might |
353 | happen because the watcher could not be properly started because libev |
361 | happen because the watcher could not be properly started because libev |
354 | ran out of memory, a file descriptor was found to be closed or any other |
362 | ran out of memory, a file descriptor was found to be closed or any other |
355 | problem. You best act on it by reporting the problem and somehow coping |
363 | problem. You best act on it by reporting the problem and somehow coping |
… | |
… | |
396 | =head1 WATCHER TYPES |
404 | =head1 WATCHER TYPES |
397 | |
405 | |
398 | This section describes each watcher in detail, but will not repeat |
406 | This section describes each watcher in detail, but will not repeat |
399 | information given in the last section. |
407 | information given in the last section. |
400 | |
408 | |
401 | =head2 struct ev_io - is my file descriptor readable or writable |
409 | =head2 C<ev_io> - is this file descriptor readable or writable |
402 | |
410 | |
403 | I/O watchers check wether a file descriptor is readable or writable |
411 | I/O watchers check whether a file descriptor is readable or writable |
404 | in each iteration of the event loop (This behaviour is called |
412 | in each iteration of the event loop (This behaviour is called |
405 | level-triggering because you keep receiving events as long as the |
413 | level-triggering because you keep receiving events as long as the |
406 | condition persists. Remember you cna stop the watcher if you don't want to |
414 | condition persists. Remember you cna stop the watcher if you don't want to |
407 | act on the event and neither want to receive future events). |
415 | act on the event and neither want to receive future events). |
408 | |
416 | |
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417 | In general you can register as many read and/or write event watchers oer |
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418 | fd as you want (as long as you don't confuse yourself). Setting all file |
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419 | descriptors to non-blocking mode is also usually a good idea (but not |
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420 | required if you know what you are doing). |
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421 | |
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422 | You have to be careful with dup'ed file descriptors, though. Some backends |
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423 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
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424 | descriptors correctly if you register interest in two or more fds pointing |
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425 | to the same file/socket etc. description. |
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426 | |
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427 | If you must do this, then force the use of a known-to-be-good backend |
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428 | (at the time of this writing, this includes only EVMETHOD_SELECT and |
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429 | EVMETHOD_POLL). |
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430 | |
409 | =over 4 |
431 | =over 4 |
410 | |
432 | |
411 | =item ev_io_init (ev_io *, callback, int fd, int events) |
433 | =item ev_io_init (ev_io *, callback, int fd, int events) |
412 | |
434 | |
413 | =item ev_io_set (ev_io *, int fd, int events) |
435 | =item ev_io_set (ev_io *, int fd, int events) |
414 | |
436 | |
415 | Configures an ev_io watcher. The fd is the file descriptor to rceeive |
437 | Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive |
416 | events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ | |
438 | events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ | |
417 | EV_WRITE> to receive the given events. |
439 | EV_WRITE> to receive the given events. |
418 | |
440 | |
419 | =back |
441 | =back |
420 | |
442 | |
421 | =head2 struct ev_timer - relative and optionally recurring timeouts |
443 | =head2 C<ev_timer> - relative and optionally recurring timeouts |
422 | |
444 | |
423 | Timer watchers are simple relative timers that generate an event after a |
445 | Timer watchers are simple relative timers that generate an event after a |
424 | given time, and optionally repeating in regular intervals after that. |
446 | given time, and optionally repeating in regular intervals after that. |
425 | |
447 | |
426 | The timers are based on real time, that is, if you register an event that |
448 | The timers are based on real time, that is, if you register an event that |
427 | times out after an hour and youreset your system clock to last years |
449 | times out after an hour and youreset your system clock to last years |
428 | time, it will still time out after (roughly) and hour. "Roughly" because |
450 | time, it will still time out after (roughly) and hour. "Roughly" because |
429 | detecting time jumps is hard, and soem inaccuracies are unavoidable (the |
451 | detecting time jumps is hard, and soem inaccuracies are unavoidable (the |
430 | monotonic clock option helps a lot here). |
452 | monotonic clock option helps a lot here). |
431 | |
453 | |
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454 | The relative timeouts are calculated relative to the C<ev_now ()> |
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455 | time. This is usually the right thing as this timestamp refers to the time |
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456 | of the event triggering whatever timeout you are modifying/starting. If |
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457 | you suspect event processing to be delayed and you *need* to base the timeout |
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458 | ion the current time, use something like this to adjust for this: |
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459 | |
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460 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
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461 | |
432 | =over 4 |
462 | =over 4 |
433 | |
463 | |
434 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
464 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
435 | |
465 | |
436 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
466 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
… | |
… | |
458 | |
488 | |
459 | This sounds a bit complicated, but here is a useful and typical |
489 | This sounds a bit complicated, but here is a useful and typical |
460 | example: Imagine you have a tcp connection and you want a so-called idle |
490 | example: Imagine you have a tcp connection and you want a so-called idle |
461 | timeout, that is, you want to be called when there have been, say, 60 |
491 | timeout, that is, you want to be called when there have been, say, 60 |
462 | seconds of inactivity on the socket. The easiest way to do this is to |
492 | seconds of inactivity on the socket. The easiest way to do this is to |
463 | configure an ev_timer with after=repeat=60 and calling ev_timer_again each |
493 | configure an C<ev_timer> with after=repeat=60 and calling ev_timer_again each |
464 | time you successfully read or write some data. If you go into an idle |
494 | time you successfully read or write some data. If you go into an idle |
465 | state where you do not expect data to travel on the socket, you can stop |
495 | state where you do not expect data to travel on the socket, you can stop |
466 | the timer, and again will automatically restart it if need be. |
496 | the timer, and again will automatically restart it if need be. |
467 | |
497 | |
468 | =back |
498 | =back |
469 | |
499 | |
470 | =head2 ev_periodic |
500 | =head2 C<ev_periodic> - to cron or not to cron it |
471 | |
501 | |
472 | Periodic watchers are also timers of a kind, but they are very versatile |
502 | Periodic watchers are also timers of a kind, but they are very versatile |
473 | (and unfortunately a bit complex). |
503 | (and unfortunately a bit complex). |
474 | |
504 | |
475 | Unlike ev_timer's, they are not based on real time (or relative time) |
505 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
476 | but on wallclock time (absolute time). You can tell a periodic watcher |
506 | but on wallclock time (absolute time). You can tell a periodic watcher |
477 | to trigger "at" some specific point in time. For example, if you tell a |
507 | to trigger "at" some specific point in time. For example, if you tell a |
478 | periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now () |
508 | periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now () |
479 | + 10.>) and then reset your system clock to the last year, then it will |
509 | + 10.>) and then reset your system clock to the last year, then it will |
480 | take a year to trigger the event (unlike an ev_timer, which would trigger |
510 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
481 | roughly 10 seconds later and of course not if you reset your system time |
511 | roughly 10 seconds later and of course not if you reset your system time |
482 | again). |
512 | again). |
483 | |
513 | |
484 | They can also be used to implement vastly more complex timers, such as |
514 | They can also be used to implement vastly more complex timers, such as |
485 | triggering an event on eahc midnight, local time. |
515 | triggering an event on eahc midnight, local time. |
… | |
… | |
514 | |
544 | |
515 | ev_periodic_set (&periodic, 0., 3600., 0); |
545 | ev_periodic_set (&periodic, 0., 3600., 0); |
516 | |
546 | |
517 | This doesn't mean there will always be 3600 seconds in between triggers, |
547 | This doesn't mean there will always be 3600 seconds in between triggers, |
518 | but only that the the callback will be called when the system time shows a |
548 | but only that the the callback will be called when the system time shows a |
519 | full hour (UTC), or more correct, when the system time is evenly divisible |
549 | full hour (UTC), or more correctly, when the system time is evenly divisible |
520 | by 3600. |
550 | by 3600. |
521 | |
551 | |
522 | Another way to think about it (for the mathematically inclined) is that |
552 | Another way to think about it (for the mathematically inclined) is that |
523 | ev_periodic will try to run the callback in this mode at the next possible |
553 | C<ev_periodic> will try to run the callback in this mode at the next possible |
524 | time where C<time = at (mod interval)>, regardless of any time jumps. |
554 | time where C<time = at (mod interval)>, regardless of any time jumps. |
525 | |
555 | |
526 | =item * manual reschedule mode (reschedule_cb = callback) |
556 | =item * manual reschedule mode (reschedule_cb = callback) |
527 | |
557 | |
528 | In this mode the values for C<interval> and C<at> are both being |
558 | In this mode the values for C<interval> and C<at> are both being |
529 | ignored. Instead, each time the periodic watcher gets scheduled, the |
559 | ignored. Instead, each time the periodic watcher gets scheduled, the |
530 | reschedule callback will be called with the watcher as first, and the |
560 | reschedule callback will be called with the watcher as first, and the |
531 | current time as second argument. |
561 | current time as second argument. |
532 | |
562 | |
533 | NOTE: I<This callback MUST NOT stop or destroy the periodic or any other |
563 | NOTE: I<This callback MUST NOT stop or destroy the periodic or any other |
534 | periodic watcher, ever, or make any event loop modificstions>. If you need |
564 | periodic watcher, ever, or make any event loop modifications>. If you need |
535 | to stop it, return 1e30 (or so, fudge fudge) and stop it afterwards. |
565 | to stop it, return C<now + 1e30> (or so, fudge fudge) and stop it afterwards. |
536 | |
566 | |
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567 | Also, I<< this callback must always return a time that is later than the |
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568 | passed C<now> value >>. Not even C<now> itself will be ok. |
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569 | |
537 | Its prototype is c<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
570 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
538 | ev_tstamp now)>, e.g.: |
571 | ev_tstamp now)>, e.g.: |
539 | |
572 | |
540 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
573 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
541 | { |
574 | { |
542 | return now + 60.; |
575 | return now + 60.; |
… | |
… | |
561 | a different time than the last time it was called (e.g. in a crond like |
594 | a different time than the last time it was called (e.g. in a crond like |
562 | program when the crontabs have changed). |
595 | program when the crontabs have changed). |
563 | |
596 | |
564 | =back |
597 | =back |
565 | |
598 | |
566 | =head2 ev_signal - signal me when a signal gets signalled |
599 | =head2 C<ev_signal> - signal me when a signal gets signalled |
567 | |
600 | |
568 | Signal watchers will trigger an event when the process receives a specific |
601 | Signal watchers will trigger an event when the process receives a specific |
569 | signal one or more times. Even though signals are very asynchronous, libev |
602 | signal one or more times. Even though signals are very asynchronous, libev |
570 | will try its best to deliver signals synchronously, i.e. as part of the |
603 | will try it's best to deliver signals synchronously, i.e. as part of the |
571 | normal event processing, like any other event. |
604 | normal event processing, like any other event. |
572 | |
605 | |
573 | You cna configure as many watchers as you like per signal. Only when the |
606 | You cna configure as many watchers as you like per signal. Only when the |
574 | first watcher gets started will libev actually register a signal watcher |
607 | first watcher gets started will libev actually register a signal watcher |
575 | 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 |
… | |
… | |
586 | Configures the watcher to trigger on the given signal number (usually one |
619 | Configures the watcher to trigger on the given signal number (usually one |
587 | of the C<SIGxxx> constants). |
620 | of the C<SIGxxx> constants). |
588 | |
621 | |
589 | =back |
622 | =back |
590 | |
623 | |
591 | =head2 ev_child - wait for pid status changes |
624 | =head2 C<ev_child> - wait for pid status changes |
592 | |
625 | |
593 | Child watchers trigger when your process receives a SIGCHLD in response to |
626 | Child watchers trigger when your process receives a SIGCHLD in response to |
594 | some child status changes (most typically when a child of yours dies). |
627 | some child status changes (most typically when a child of yours dies). |
595 | |
628 | |
596 | =over 4 |
629 | =over 4 |
… | |
… | |
605 | the status word (use the macros from C<sys/wait.h>). The C<rpid> member |
638 | the status word (use the macros from C<sys/wait.h>). The C<rpid> member |
606 | contains the pid of the process causing the status change. |
639 | contains the pid of the process causing the status change. |
607 | |
640 | |
608 | =back |
641 | =back |
609 | |
642 | |
610 | =head2 ev_idle - when you've got nothing better to do |
643 | =head2 C<ev_idle> - when you've got nothing better to do |
611 | |
644 | |
612 | Idle watchers trigger events when there are no other I/O or timer (or |
645 | Idle watchers trigger events when there are no other I/O or timer (or |
613 | periodic) events pending. That is, as long as your process is busy |
646 | periodic) events pending. That is, as long as your process is busy |
614 | handling sockets or timeouts it will not be called. But when your process |
647 | handling sockets or timeouts it will not be called. But when your process |
615 | is idle all idle watchers are being called again and again - until |
648 | is idle all idle watchers are being called again and again - until |
… | |
… | |
642 | Their main purpose is to integrate other event mechanisms into libev. This |
675 | Their main purpose is to integrate other event mechanisms into libev. This |
643 | could be used, for example, to track variable changes, implement your own |
676 | could be used, for example, to track variable changes, implement your own |
644 | watchers, integrate net-snmp or a coroutine library and lots more. |
677 | watchers, integrate net-snmp or a coroutine library and lots more. |
645 | |
678 | |
646 | This is done by examining in each prepare call which file descriptors need |
679 | This is done by examining in each prepare call which file descriptors need |
647 | to be watched by the other library, registering ev_io watchers for them |
680 | to be watched by the other library, registering C<ev_io> watchers for them |
648 | and starting an ev_timer watcher for any timeouts (many libraries provide |
681 | and starting an C<ev_timer> watcher for any timeouts (many libraries provide |
649 | just this functionality). Then, in the check watcher you check for any |
682 | just this functionality). Then, in the check watcher you check for any |
650 | events that occured (by making your callbacks set soem flags for example) |
683 | events that occured (by making your callbacks set soem flags for example) |
651 | and call back into the library. |
684 | and call back into the library. |
652 | |
685 | |
653 | As another example, the perl Coro module uses these hooks to integrate |
686 | As another example, the perl Coro module uses these hooks to integrate |
… | |
… | |
680 | watchers. This is useful if you want to wait for a single event on an fd |
713 | watchers. This is useful if you want to wait for a single event on an fd |
681 | or timeout without havign to allocate/configure/start/stop/free one or |
714 | or timeout without havign to allocate/configure/start/stop/free one or |
682 | more watchers yourself. |
715 | more watchers yourself. |
683 | |
716 | |
684 | If C<fd> is less than 0, then no I/O watcher will be started and events is |
717 | If C<fd> is less than 0, then no I/O watcher will be started and events is |
685 | ignored. Otherwise, an ev_io watcher for the given C<fd> and C<events> set |
718 | ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and C<events> set |
686 | will be craeted and started. |
719 | will be craeted and started. |
687 | |
720 | |
688 | If C<timeout> is less than 0, then no timeout watcher will be |
721 | If C<timeout> is less than 0, then no timeout watcher will be |
689 | started. Otherwise an ev_timer watcher with after = C<timeout> (and repeat |
722 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and repeat |
690 | = 0) will be started. |
723 | = 0) will be started. |
691 | |
724 | |
692 | The callback has the type C<void (*cb)(int revents, void *arg)> and |
725 | The callback has the type C<void (*cb)(int revents, void *arg)> and |
693 | gets passed an events set (normally a combination of EV_ERROR, EV_READ, |
726 | gets passed an events set (normally a combination of C<EV_ERROR>, C<EV_READ>, |
694 | EV_WRITE or EV_TIMEOUT) and the C<arg> value passed to C<ev_once>: |
727 | C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> value passed to C<ev_once>: |
695 | |
728 | |
696 | static void stdin_ready (int revents, void *arg) |
729 | static void stdin_ready (int revents, void *arg) |
697 | { |
730 | { |
698 | if (revents & EV_TIMEOUT) |
731 | if (revents & EV_TIMEOUT) |
699 | /* doh, nothing entered */ |
732 | /* doh, nothing entered */ |