1 | .\" Automatically generated by Pod::Man v1.37, Pod::Parser v1.35 |
1 | .\" Automatically generated by Pod::Man 2.16 (Pod::Simple 3.05) |
2 | .\" |
2 | .\" |
3 | .\" Standard preamble: |
3 | .\" Standard preamble: |
4 | .\" ======================================================================== |
4 | .\" ======================================================================== |
5 | .de Sh \" Subsection heading |
5 | .de Sh \" Subsection heading |
6 | .br |
6 | .br |
… | |
… | |
23 | .ft R |
23 | .ft R |
24 | .fi |
24 | .fi |
25 | .. |
25 | .. |
26 | .\" Set up some character translations and predefined strings. \*(-- will |
26 | .\" Set up some character translations and predefined strings. \*(-- will |
27 | .\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left |
27 | .\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left |
28 | .\" double quote, and \*(R" will give a right double quote. | will give a |
28 | .\" double quote, and \*(R" will give a right double quote. \*(C+ will |
29 | .\" real vertical bar. \*(C+ will give a nicer C++. Capital omega is used to |
29 | .\" give a nicer C++. Capital omega is used to do unbreakable dashes and |
30 | .\" do unbreakable dashes and therefore won't be available. \*(C` and \*(C' |
30 | .\" therefore won't be available. \*(C` and \*(C' expand to `' in nroff, |
31 | .\" expand to `' in nroff, nothing in troff, for use with C<>. |
31 | .\" nothing in troff, for use with C<>. |
32 | .tr \(*W-|\(bv\*(Tr |
32 | .tr \(*W- |
33 | .ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p' |
33 | .ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p' |
34 | .ie n \{\ |
34 | .ie n \{\ |
35 | . ds -- \(*W- |
35 | . ds -- \(*W- |
36 | . ds PI pi |
36 | . ds PI pi |
37 | . if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch |
37 | . if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch |
… | |
… | |
46 | . ds PI \(*p |
46 | . ds PI \(*p |
47 | . ds L" `` |
47 | . ds L" `` |
48 | . ds R" '' |
48 | . ds R" '' |
49 | 'br\} |
49 | 'br\} |
50 | .\" |
50 | .\" |
|
|
51 | .\" Escape single quotes in literal strings from groff's Unicode transform. |
|
|
52 | .ie \n(.g .ds Aq \(aq |
|
|
53 | .el .ds Aq ' |
|
|
54 | .\" |
51 | .\" If the F register is turned on, we'll generate index entries on stderr for |
55 | .\" If the F register is turned on, we'll generate index entries on stderr for |
52 | .\" titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and index |
56 | .\" titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and index |
53 | .\" entries marked with X<> in POD. Of course, you'll have to process the |
57 | .\" entries marked with X<> in POD. Of course, you'll have to process the |
54 | .\" output yourself in some meaningful fashion. |
58 | .\" output yourself in some meaningful fashion. |
55 | .if \nF \{\ |
59 | .ie \nF \{\ |
56 | . de IX |
60 | . de IX |
57 | . tm Index:\\$1\t\\n%\t"\\$2" |
61 | . tm Index:\\$1\t\\n%\t"\\$2" |
58 | .. |
62 | .. |
59 | . nr % 0 |
63 | . nr % 0 |
60 | . rr F |
64 | . rr F |
61 | .\} |
65 | .\} |
62 | .\" |
66 | .el \{\ |
63 | .\" For nroff, turn off justification. Always turn off hyphenation; it makes |
67 | . de IX |
64 | .\" way too many mistakes in technical documents. |
68 | .. |
65 | .hy 0 |
69 | .\} |
66 | .if n .na |
|
|
67 | .\" |
70 | .\" |
68 | .\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2). |
71 | .\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2). |
69 | .\" Fear. Run. Save yourself. No user-serviceable parts. |
72 | .\" Fear. Run. Save yourself. No user-serviceable parts. |
70 | . \" fudge factors for nroff and troff |
73 | . \" fudge factors for nroff and troff |
71 | .if n \{\ |
74 | .if n \{\ |
… | |
… | |
126 | . ds Ae AE |
129 | . ds Ae AE |
127 | .\} |
130 | .\} |
128 | .rm #[ #] #H #V #F C |
131 | .rm #[ #] #H #V #F C |
129 | .\" ======================================================================== |
132 | .\" ======================================================================== |
130 | .\" |
133 | .\" |
131 | .IX Title ""<STANDARD INPUT>" 1" |
134 | .IX Title "EV 1" |
132 | .TH "<STANDARD INPUT>" 1 "2007-11-23" "perl v5.8.8" "User Contributed Perl Documentation" |
135 | .TH EV 1 "2008-03-13" "perl v5.10.0" "User Contributed Perl Documentation" |
|
|
136 | .\" For nroff, turn off justification. Always turn off hyphenation; it makes |
|
|
137 | .\" way too many mistakes in technical documents. |
|
|
138 | .if n .ad l |
|
|
139 | .nh |
133 | .SH "NAME" |
140 | .SH "NAME" |
134 | libev \- a high performance full\-featured event loop written in C |
141 | libev \- a high performance full\-featured event loop written in C |
135 | .SH "SYNOPSIS" |
142 | .SH "SYNOPSIS" |
136 | .IX Header "SYNOPSIS" |
143 | .IX Header "SYNOPSIS" |
137 | .Vb 1 |
144 | .Vb 1 |
138 | \& #include <ev.h> |
145 | \& #include <ev.h> |
139 | .Ve |
146 | .Ve |
|
|
147 | .Sh "\s-1EXAMPLE\s0 \s-1PROGRAM\s0" |
|
|
148 | .IX Subsection "EXAMPLE PROGRAM" |
|
|
149 | .Vb 2 |
|
|
150 | \& // a single header file is required |
|
|
151 | \& #include <ev.h> |
|
|
152 | \& |
|
|
153 | \& // every watcher type has its own typedef\*(Aqd struct |
|
|
154 | \& // with the name ev_<type> |
|
|
155 | \& ev_io stdin_watcher; |
|
|
156 | \& ev_timer timeout_watcher; |
|
|
157 | \& |
|
|
158 | \& // all watcher callbacks have a similar signature |
|
|
159 | \& // this callback is called when data is readable on stdin |
|
|
160 | \& static void |
|
|
161 | \& stdin_cb (EV_P_ struct ev_io *w, int revents) |
|
|
162 | \& { |
|
|
163 | \& puts ("stdin ready"); |
|
|
164 | \& // for one\-shot events, one must manually stop the watcher |
|
|
165 | \& // with its corresponding stop function. |
|
|
166 | \& ev_io_stop (EV_A_ w); |
|
|
167 | \& |
|
|
168 | \& // this causes all nested ev_loop\*(Aqs to stop iterating |
|
|
169 | \& ev_unloop (EV_A_ EVUNLOOP_ALL); |
|
|
170 | \& } |
|
|
171 | \& |
|
|
172 | \& // another callback, this time for a time\-out |
|
|
173 | \& static void |
|
|
174 | \& timeout_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
175 | \& { |
|
|
176 | \& puts ("timeout"); |
|
|
177 | \& // this causes the innermost ev_loop to stop iterating |
|
|
178 | \& ev_unloop (EV_A_ EVUNLOOP_ONE); |
|
|
179 | \& } |
|
|
180 | \& |
|
|
181 | \& int |
|
|
182 | \& main (void) |
|
|
183 | \& { |
|
|
184 | \& // use the default event loop unless you have special needs |
|
|
185 | \& struct ev_loop *loop = ev_default_loop (0); |
|
|
186 | \& |
|
|
187 | \& // initialise an io watcher, then start it |
|
|
188 | \& // this one will watch for stdin to become readable |
|
|
189 | \& ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
|
|
190 | \& ev_io_start (loop, &stdin_watcher); |
|
|
191 | \& |
|
|
192 | \& // initialise a timer watcher, then start it |
|
|
193 | \& // simple non\-repeating 5.5 second timeout |
|
|
194 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
|
|
195 | \& ev_timer_start (loop, &timeout_watcher); |
|
|
196 | \& |
|
|
197 | \& // now wait for events to arrive |
|
|
198 | \& ev_loop (loop, 0); |
|
|
199 | \& |
|
|
200 | \& // unloop was called, so exit |
|
|
201 | \& return 0; |
|
|
202 | \& } |
|
|
203 | .Ve |
140 | .SH "DESCRIPTION" |
204 | .SH "DESCRIPTION" |
141 | .IX Header "DESCRIPTION" |
205 | .IX Header "DESCRIPTION" |
|
|
206 | The newest version of this document is also available as an html-formatted |
|
|
207 | web page you might find easier to navigate when reading it for the first |
|
|
208 | time: <http://cvs.schmorp.de/libev/ev.html>. |
|
|
209 | .PP |
142 | Libev is an event loop: you register interest in certain events (such as a |
210 | Libev is an event loop: you register interest in certain events (such as a |
143 | file descriptor being readable or a timeout occuring), and it will manage |
211 | file descriptor being readable or a timeout occurring), and it will manage |
144 | these event sources and provide your program with events. |
212 | these event sources and provide your program with events. |
145 | .PP |
213 | .PP |
146 | To do this, it must take more or less complete control over your process |
214 | To do this, it must take more or less complete control over your process |
147 | (or thread) by executing the \fIevent loop\fR handler, and will then |
215 | (or thread) by executing the \fIevent loop\fR handler, and will then |
148 | communicate events via a callback mechanism. |
216 | communicate events via a callback mechanism. |
149 | .PP |
217 | .PP |
150 | You register interest in certain events by registering so-called \fIevent |
218 | You register interest in certain events by registering so-called \fIevent |
151 | watchers\fR, which are relatively small C structures you initialise with the |
219 | watchers\fR, which are relatively small C structures you initialise with the |
152 | details of the event, and then hand it over to libev by \fIstarting\fR the |
220 | details of the event, and then hand it over to libev by \fIstarting\fR the |
153 | watcher. |
221 | watcher. |
154 | .SH "FEATURES" |
222 | .Sh "\s-1FEATURES\s0" |
155 | .IX Header "FEATURES" |
223 | .IX Subsection "FEATURES" |
156 | Libev supports select, poll, the linux-specific epoll and the bsd-specific |
224 | Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific \f(CW\*(C`epoll\*(C'\fR, the |
157 | kqueue mechanisms for file descriptor events, relative timers, absolute |
225 | BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms |
158 | timers with customised rescheduling, signal events, process status change |
226 | for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface |
159 | events (related to \s-1SIGCHLD\s0), and event watchers dealing with the event |
227 | (for \f(CW\*(C`ev_stat\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers |
160 | loop mechanism itself (idle, prepare and check watchers). It also is quite |
228 | with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals |
161 | fast (see this benchmark comparing |
229 | (\f(CW\*(C`ev_signal\*(C'\fR), process status change events (\f(CW\*(C`ev_child\*(C'\fR), and event |
162 | it to libevent for example). |
230 | watchers dealing with the event loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR, |
|
|
231 | \&\f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR watchers) as well as |
|
|
232 | file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events |
|
|
233 | (\f(CW\*(C`ev_fork\*(C'\fR). |
|
|
234 | .PP |
|
|
235 | It also is quite fast (see this |
|
|
236 | benchmark comparing it to libevent |
|
|
237 | for example). |
163 | .SH "CONVENTIONS" |
238 | .Sh "\s-1CONVENTIONS\s0" |
164 | .IX Header "CONVENTIONS" |
239 | .IX Subsection "CONVENTIONS" |
165 | Libev is very configurable. In this manual the default configuration |
240 | Libev is very configurable. In this manual the default (and most common) |
166 | will be described, which supports multiple event loops. For more info |
241 | configuration will be described, which supports multiple event loops. For |
167 | about various configuration options please have a look at the file |
242 | more info about various configuration options please have a look at |
168 | \&\fI\s-1README\s0.embed\fR in the libev distribution. If libev was configured without |
243 | \&\fB\s-1EMBED\s0\fR section in this manual. If libev was configured without support |
169 | support for multiple event loops, then all functions taking an initial |
244 | for multiple event loops, then all functions taking an initial argument of |
170 | argument of name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) |
245 | name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) will not have |
171 | will not have this argument. |
246 | this argument. |
172 | .SH "TIME REPRESENTATION" |
247 | .Sh "\s-1TIME\s0 \s-1REPRESENTATION\s0" |
173 | .IX Header "TIME REPRESENTATION" |
248 | .IX Subsection "TIME REPRESENTATION" |
174 | Libev represents time as a single floating point number, representing the |
249 | Libev represents time as a single floating point number, representing the |
175 | (fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near |
250 | (fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near |
176 | the beginning of 1970, details are complicated, don't ask). This type is |
251 | the beginning of 1970, details are complicated, don't ask). This type is |
177 | called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually aliases |
252 | called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually aliases |
178 | to the double type in C. |
253 | to the \f(CW\*(C`double\*(C'\fR type in C, and when you need to do any calculations on |
|
|
254 | it, you should treat it as some floatingpoint value. Unlike the name |
|
|
255 | component \f(CW\*(C`stamp\*(C'\fR might indicate, it is also used for time differences |
|
|
256 | throughout libev. |
179 | .SH "GLOBAL FUNCTIONS" |
257 | .SH "GLOBAL FUNCTIONS" |
180 | .IX Header "GLOBAL FUNCTIONS" |
258 | .IX Header "GLOBAL FUNCTIONS" |
181 | These functions can be called anytime, even before initialising the |
259 | These functions can be called anytime, even before initialising the |
182 | library in any way. |
260 | library in any way. |
183 | .IP "ev_tstamp ev_time ()" 4 |
261 | .IP "ev_tstamp ev_time ()" 4 |
184 | .IX Item "ev_tstamp ev_time ()" |
262 | .IX Item "ev_tstamp ev_time ()" |
185 | Returns the current time as libev would use it. Please note that the |
263 | Returns the current time as libev would use it. Please note that the |
186 | \&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp |
264 | \&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp |
187 | you actually want to know. |
265 | you actually want to know. |
|
|
266 | .IP "ev_sleep (ev_tstamp interval)" 4 |
|
|
267 | .IX Item "ev_sleep (ev_tstamp interval)" |
|
|
268 | Sleep for the given interval: The current thread will be blocked until |
|
|
269 | either it is interrupted or the given time interval has passed. Basically |
|
|
270 | this is a subsecond-resolution \f(CW\*(C`sleep ()\*(C'\fR. |
188 | .IP "int ev_version_major ()" 4 |
271 | .IP "int ev_version_major ()" 4 |
189 | .IX Item "int ev_version_major ()" |
272 | .IX Item "int ev_version_major ()" |
190 | .PD 0 |
273 | .PD 0 |
191 | .IP "int ev_version_minor ()" 4 |
274 | .IP "int ev_version_minor ()" 4 |
192 | .IX Item "int ev_version_minor ()" |
275 | .IX Item "int ev_version_minor ()" |
193 | .PD |
276 | .PD |
194 | You can find out the major and minor version numbers of the library |
277 | You can find out the major and minor \s-1ABI\s0 version numbers of the library |
195 | you linked against by calling the functions \f(CW\*(C`ev_version_major\*(C'\fR and |
278 | you linked against by calling the functions \f(CW\*(C`ev_version_major\*(C'\fR and |
196 | \&\f(CW\*(C`ev_version_minor\*(C'\fR. If you want, you can compare against the global |
279 | \&\f(CW\*(C`ev_version_minor\*(C'\fR. If you want, you can compare against the global |
197 | symbols \f(CW\*(C`EV_VERSION_MAJOR\*(C'\fR and \f(CW\*(C`EV_VERSION_MINOR\*(C'\fR, which specify the |
280 | symbols \f(CW\*(C`EV_VERSION_MAJOR\*(C'\fR and \f(CW\*(C`EV_VERSION_MINOR\*(C'\fR, which specify the |
198 | version of the library your program was compiled against. |
281 | version of the library your program was compiled against. |
199 | .Sp |
282 | .Sp |
|
|
283 | These version numbers refer to the \s-1ABI\s0 version of the library, not the |
|
|
284 | release version. |
|
|
285 | .Sp |
200 | Usually, it's a good idea to terminate if the major versions mismatch, |
286 | Usually, it's a good idea to terminate if the major versions mismatch, |
201 | as this indicates an incompatible change. Minor versions are usually |
287 | as this indicates an incompatible change. Minor versions are usually |
202 | compatible to older versions, so a larger minor version alone is usually |
288 | compatible to older versions, so a larger minor version alone is usually |
203 | not a problem. |
289 | not a problem. |
|
|
290 | .Sp |
|
|
291 | Example: Make sure we haven't accidentally been linked against the wrong |
|
|
292 | version. |
|
|
293 | .Sp |
|
|
294 | .Vb 3 |
|
|
295 | \& assert (("libev version mismatch", |
|
|
296 | \& ev_version_major () == EV_VERSION_MAJOR |
|
|
297 | \& && ev_version_minor () >= EV_VERSION_MINOR)); |
|
|
298 | .Ve |
204 | .IP "unsigned int ev_supported_backends ()" 4 |
299 | .IP "unsigned int ev_supported_backends ()" 4 |
205 | .IX Item "unsigned int ev_supported_backends ()" |
300 | .IX Item "unsigned int ev_supported_backends ()" |
206 | Return the set of all backends (i.e. their corresponding \f(CW\*(C`EV_BACKEND_*\*(C'\fR |
301 | Return the set of all backends (i.e. their corresponding \f(CW\*(C`EV_BACKEND_*\*(C'\fR |
207 | value) compiled into this binary of libev (independent of their |
302 | value) compiled into this binary of libev (independent of their |
208 | availability on the system you are running on). See \f(CW\*(C`ev_default_loop\*(C'\fR for |
303 | availability on the system you are running on). See \f(CW\*(C`ev_default_loop\*(C'\fR for |
209 | a description of the set values. |
304 | a description of the set values. |
|
|
305 | .Sp |
|
|
306 | Example: make sure we have the epoll method, because yeah this is cool and |
|
|
307 | a must have and can we have a torrent of it please!!!11 |
|
|
308 | .Sp |
|
|
309 | .Vb 2 |
|
|
310 | \& assert (("sorry, no epoll, no sex", |
|
|
311 | \& ev_supported_backends () & EVBACKEND_EPOLL)); |
|
|
312 | .Ve |
210 | .IP "unsigned int ev_recommended_backends ()" 4 |
313 | .IP "unsigned int ev_recommended_backends ()" 4 |
211 | .IX Item "unsigned int ev_recommended_backends ()" |
314 | .IX Item "unsigned int ev_recommended_backends ()" |
212 | Return the set of all backends compiled into this binary of libev and also |
315 | Return the set of all backends compiled into this binary of libev and also |
213 | recommended for this platform. This set is often smaller than the one |
316 | recommended for this platform. This set is often smaller than the one |
214 | returned by \f(CW\*(C`ev_supported_backends\*(C'\fR, as for example kqueue is broken on |
317 | returned by \f(CW\*(C`ev_supported_backends\*(C'\fR, as for example kqueue is broken on |
215 | most BSDs and will not be autodetected unless you explicitly request it |
318 | most BSDs and will not be autodetected unless you explicitly request it |
216 | (assuming you know what you are doing). This is the set of backends that |
319 | (assuming you know what you are doing). This is the set of backends that |
217 | \&\f(CW\*(C`EVFLAG_AUTO\*(C'\fR will probe for. |
320 | libev will probe for if you specify no backends explicitly. |
|
|
321 | .IP "unsigned int ev_embeddable_backends ()" 4 |
|
|
322 | .IX Item "unsigned int ev_embeddable_backends ()" |
|
|
323 | Returns the set of backends that are embeddable in other event loops. This |
|
|
324 | is the theoretical, all-platform, value. To find which backends |
|
|
325 | might be supported on the current system, you would need to look at |
|
|
326 | \&\f(CW\*(C`ev_embeddable_backends () & ev_supported_backends ()\*(C'\fR, likewise for |
|
|
327 | recommended ones. |
|
|
328 | .Sp |
|
|
329 | See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
218 | .IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4 |
330 | .IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4 |
219 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))" |
331 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))" |
220 | Sets the allocation function to use (the prototype is similar to the |
332 | Sets the allocation function to use (the prototype is similar \- the |
221 | realloc C function, the semantics are identical). It is used to allocate |
333 | semantics is identical \- to the realloc C function). It is used to |
222 | and free memory (no surprises here). If it returns zero when memory |
334 | allocate and free memory (no surprises here). If it returns zero when |
223 | needs to be allocated, the library might abort or take some potentially |
335 | memory needs to be allocated, the library might abort or take some |
224 | destructive action. The default is your system realloc function. |
336 | potentially destructive action. The default is your system realloc |
|
|
337 | function. |
225 | .Sp |
338 | .Sp |
226 | You could override this function in high-availability programs to, say, |
339 | You could override this function in high-availability programs to, say, |
227 | free some memory if it cannot allocate memory, to use a special allocator, |
340 | free some memory if it cannot allocate memory, to use a special allocator, |
228 | or even to sleep a while and retry until some memory is available. |
341 | or even to sleep a while and retry until some memory is available. |
|
|
342 | .Sp |
|
|
343 | Example: Replace the libev allocator with one that waits a bit and then |
|
|
344 | retries). |
|
|
345 | .Sp |
|
|
346 | .Vb 6 |
|
|
347 | \& static void * |
|
|
348 | \& persistent_realloc (void *ptr, size_t size) |
|
|
349 | \& { |
|
|
350 | \& for (;;) |
|
|
351 | \& { |
|
|
352 | \& void *newptr = realloc (ptr, size); |
|
|
353 | \& |
|
|
354 | \& if (newptr) |
|
|
355 | \& return newptr; |
|
|
356 | \& |
|
|
357 | \& sleep (60); |
|
|
358 | \& } |
|
|
359 | \& } |
|
|
360 | \& |
|
|
361 | \& ... |
|
|
362 | \& ev_set_allocator (persistent_realloc); |
|
|
363 | .Ve |
229 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg));" 4 |
364 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg));" 4 |
230 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg));" |
365 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg));" |
231 | Set the callback function to call on a retryable syscall error (such |
366 | Set the callback function to call on a retryable syscall error (such |
232 | as failed select, poll, epoll_wait). The message is a printable string |
367 | as failed select, poll, epoll_wait). The message is a printable string |
233 | indicating the system call or subsystem causing the problem. If this |
368 | indicating the system call or subsystem causing the problem. If this |
234 | callback is set, then libev will expect it to remedy the sitution, no |
369 | callback is set, then libev will expect it to remedy the sitution, no |
235 | matter what, when it returns. That is, libev will generally retry the |
370 | matter what, when it returns. That is, libev will generally retry the |
236 | requested operation, or, if the condition doesn't go away, do bad stuff |
371 | requested operation, or, if the condition doesn't go away, do bad stuff |
237 | (such as abort). |
372 | (such as abort). |
|
|
373 | .Sp |
|
|
374 | Example: This is basically the same thing that libev does internally, too. |
|
|
375 | .Sp |
|
|
376 | .Vb 6 |
|
|
377 | \& static void |
|
|
378 | \& fatal_error (const char *msg) |
|
|
379 | \& { |
|
|
380 | \& perror (msg); |
|
|
381 | \& abort (); |
|
|
382 | \& } |
|
|
383 | \& |
|
|
384 | \& ... |
|
|
385 | \& ev_set_syserr_cb (fatal_error); |
|
|
386 | .Ve |
238 | .SH "FUNCTIONS CONTROLLING THE EVENT LOOP" |
387 | .SH "FUNCTIONS CONTROLLING THE EVENT LOOP" |
239 | .IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP" |
388 | .IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP" |
240 | An event loop is described by a \f(CW\*(C`struct ev_loop *\*(C'\fR. The library knows two |
389 | An event loop is described by a \f(CW\*(C`struct ev_loop *\*(C'\fR. The library knows two |
241 | types of such loops, the \fIdefault\fR loop, which supports signals and child |
390 | types of such loops, the \fIdefault\fR loop, which supports signals and child |
242 | events, and dynamically created loops which do not. |
391 | events, and dynamically created loops which do not. |
… | |
… | |
255 | flags. If that is troubling you, check \f(CW\*(C`ev_backend ()\*(C'\fR afterwards). |
404 | flags. If that is troubling you, check \f(CW\*(C`ev_backend ()\*(C'\fR afterwards). |
256 | .Sp |
405 | .Sp |
257 | If you don't know what event loop to use, use the one returned from this |
406 | If you don't know what event loop to use, use the one returned from this |
258 | function. |
407 | function. |
259 | .Sp |
408 | .Sp |
|
|
409 | The default loop is the only loop that can handle \f(CW\*(C`ev_signal\*(C'\fR and |
|
|
410 | \&\f(CW\*(C`ev_child\*(C'\fR watchers, and to do this, it always registers a handler |
|
|
411 | for \f(CW\*(C`SIGCHLD\*(C'\fR. If this is a problem for your app you can either |
|
|
412 | create a dynamic loop with \f(CW\*(C`ev_loop_new\*(C'\fR that doesn't do that, or you |
|
|
413 | can simply overwrite the \f(CW\*(C`SIGCHLD\*(C'\fR signal handler \fIafter\fR calling |
|
|
414 | \&\f(CW\*(C`ev_default_init\*(C'\fR. |
|
|
415 | .Sp |
260 | The flags argument can be used to specify special behaviour or specific |
416 | The flags argument can be used to specify special behaviour or specific |
261 | backends to use, and is usually specified as \f(CW0\fR (or \s-1EVFLAG_AUTO\s0). |
417 | backends to use, and is usually specified as \f(CW0\fR (or \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). |
262 | .Sp |
418 | .Sp |
263 | It supports the following flags: |
419 | The following flags are supported: |
264 | .RS 4 |
420 | .RS 4 |
265 | .ie n .IP """EVFLAG_AUTO""" 4 |
421 | .ie n .IP """EVFLAG_AUTO""" 4 |
266 | .el .IP "\f(CWEVFLAG_AUTO\fR" 4 |
422 | .el .IP "\f(CWEVFLAG_AUTO\fR" 4 |
267 | .IX Item "EVFLAG_AUTO" |
423 | .IX Item "EVFLAG_AUTO" |
268 | The default flags value. Use this if you have no clue (it's the right |
424 | The default flags value. Use this if you have no clue (it's the right |
… | |
… | |
274 | or setgid) then libev will \fInot\fR look at the environment variable |
430 | or setgid) then libev will \fInot\fR look at the environment variable |
275 | \&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will |
431 | \&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will |
276 | override the flags completely if it is found in the environment. This is |
432 | override the flags completely if it is found in the environment. This is |
277 | useful to try out specific backends to test their performance, or to work |
433 | useful to try out specific backends to test their performance, or to work |
278 | around bugs. |
434 | around bugs. |
|
|
435 | .ie n .IP """EVFLAG_FORKCHECK""" 4 |
|
|
436 | .el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4 |
|
|
437 | .IX Item "EVFLAG_FORKCHECK" |
|
|
438 | Instead of calling \f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR manually after |
|
|
439 | a fork, you can also make libev check for a fork in each iteration by |
|
|
440 | enabling this flag. |
|
|
441 | .Sp |
|
|
442 | This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, |
|
|
443 | and thus this might slow down your event loop if you do a lot of loop |
|
|
444 | iterations and little real work, but is usually not noticeable (on my |
|
|
445 | GNU/Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence |
|
|
446 | without a syscall and thus \fIvery\fR fast, but my GNU/Linux system also has |
|
|
447 | \&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster). |
|
|
448 | .Sp |
|
|
449 | The big advantage of this flag is that you can forget about fork (and |
|
|
450 | forget about forgetting to tell libev about forking) when you use this |
|
|
451 | flag. |
|
|
452 | .Sp |
|
|
453 | This flag setting cannot be overriden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR |
|
|
454 | environment variable. |
279 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
455 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
280 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
456 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
281 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
457 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
282 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
458 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
283 | libev tries to roll its own fd_set with no limits on the number of fds, |
459 | libev tries to roll its own fd_set with no limits on the number of fds, |
284 | but if that fails, expect a fairly low limit on the number of fds when |
460 | but if that fails, expect a fairly low limit on the number of fds when |
285 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
461 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
286 | the fastest backend for a low number of fds. |
462 | usually the fastest backend for a low number of (low-numbered :) fds. |
|
|
463 | .Sp |
|
|
464 | To get good performance out of this backend you need a high amount of |
|
|
465 | parallelity (most of the file descriptors should be busy). If you are |
|
|
466 | writing a server, you should \f(CW\*(C`accept ()\*(C'\fR in a loop to accept as many |
|
|
467 | connections as possible during one iteration. You might also want to have |
|
|
468 | a look at \f(CW\*(C`ev_set_io_collect_interval ()\*(C'\fR to increase the amount of |
|
|
469 | readyness notifications you get per iteration. |
287 | .ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 |
470 | .ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 |
288 | .el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4 |
471 | .el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4 |
289 | .IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)" |
472 | .IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)" |
290 | And this is your standard \fIpoll\fR\|(2) backend. It's more complicated than |
473 | And this is your standard \fIpoll\fR\|(2) backend. It's more complicated |
291 | select, but handles sparse fds better and has no artificial limit on the |
474 | than select, but handles sparse fds better and has no artificial |
292 | number of fds you can use (except it will slow down considerably with a |
475 | limit on the number of fds you can use (except it will slow down |
293 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
476 | considerably with a lot of inactive fds). It scales similarly to select, |
|
|
477 | i.e. O(total_fds). See the entry for \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR, above, for |
|
|
478 | performance tips. |
294 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
479 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
295 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
480 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
296 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
481 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
297 | For few fds, this backend is a bit little slower than poll and select, |
482 | For few fds, this backend is a bit little slower than poll and select, |
298 | but it scales phenomenally better. While poll and select usually scale like |
483 | but it scales phenomenally better. While poll and select usually scale |
299 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
484 | like O(total_fds) where n is the total number of fds (or the highest fd), |
300 | either O(1) or O(active_fds). |
485 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
|
|
486 | of shortcomings, such as silently dropping events in some hard-to-detect |
|
|
487 | cases and rewiring a syscall per fd change, no fork support and bad |
|
|
488 | support for dup. |
301 | .Sp |
489 | .Sp |
302 | While stopping and starting an I/O watcher in the same iteration will |
490 | While stopping, setting and starting an I/O watcher in the same iteration |
303 | result in some caching, there is still a syscall per such incident |
491 | will result in some caching, there is still a syscall per such incident |
304 | (because the fd could point to a different file description now), so its |
492 | (because the fd could point to a different file description now), so its |
305 | best to avoid that. Also, \fIdup()\fRed file descriptors might not work very |
493 | best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors might not work |
306 | well if you register events for both fds. |
494 | very well if you register events for both fds. |
307 | .Sp |
495 | .Sp |
308 | Please note that epoll sometimes generates spurious notifications, so you |
496 | Please note that epoll sometimes generates spurious notifications, so you |
309 | need to use non-blocking I/O or other means to avoid blocking when no data |
497 | need to use non-blocking I/O or other means to avoid blocking when no data |
310 | (or space) is available. |
498 | (or space) is available. |
|
|
499 | .Sp |
|
|
500 | Best performance from this backend is achieved by not unregistering all |
|
|
501 | watchers for a file descriptor until it has been closed, if possible, i.e. |
|
|
502 | keep at least one watcher active per fd at all times. |
|
|
503 | .Sp |
|
|
504 | While nominally embeddeble in other event loops, this feature is broken in |
|
|
505 | all kernel versions tested so far. |
311 | .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 |
506 | .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 |
312 | .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 |
507 | .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 |
313 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
508 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
314 | Kqueue deserves special mention, as at the time of this writing, it |
509 | Kqueue deserves special mention, as at the time of this writing, it |
315 | was broken on all BSDs except NetBSD (usually it doesn't work with |
510 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
316 | anything but sockets and pipes, except on Darwin, where of course its |
511 | with anything but sockets and pipes, except on Darwin, where of course |
317 | completely useless). For this reason its not being \*(L"autodetected\*(R" unless |
512 | it's completely useless). For this reason it's not being \*(L"autodetected\*(R" |
318 | you explicitly specify the flags (i.e. you don't use \s-1EVFLAG_AUTO\s0). |
513 | unless you explicitly specify it explicitly in the flags (i.e. using |
|
|
514 | \&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR) or libev was compiled on a known-to-be-good (\-enough) |
|
|
515 | system like NetBSD. |
|
|
516 | .Sp |
|
|
517 | You still can embed kqueue into a normal poll or select backend and use it |
|
|
518 | only for sockets (after having made sure that sockets work with kqueue on |
|
|
519 | the target platform). See \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
319 | .Sp |
520 | .Sp |
320 | It scales in the same way as the epoll backend, but the interface to the |
521 | It scales in the same way as the epoll backend, but the interface to the |
321 | kernel is more efficient (which says nothing about its actual speed, of |
522 | kernel is more efficient (which says nothing about its actual speed, of |
322 | course). While starting and stopping an I/O watcher does not cause an |
523 | course). While stopping, setting and starting an I/O watcher does never |
323 | extra syscall as with epoll, it still adds up to four event changes per |
524 | cause an extra syscall as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to |
324 | incident, so its best to avoid that. |
525 | two event changes per incident, support for \f(CW\*(C`fork ()\*(C'\fR is very bad and it |
|
|
526 | drops fds silently in similarly hard-to-detect cases. |
|
|
527 | .Sp |
|
|
528 | This backend usually performs well under most conditions. |
|
|
529 | .Sp |
|
|
530 | While nominally embeddable in other event loops, this doesn't work |
|
|
531 | everywhere, so you might need to test for this. And since it is broken |
|
|
532 | almost everywhere, you should only use it when you have a lot of sockets |
|
|
533 | (for which it usually works), by embedding it into another event loop |
|
|
534 | (e.g. \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR) and using it only for |
|
|
535 | sockets. |
325 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
536 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
326 | .el .IP "\f(CWEVBACKEND_DEVPOLL\fR (value 16, Solaris 8)" 4 |
537 | .el .IP "\f(CWEVBACKEND_DEVPOLL\fR (value 16, Solaris 8)" 4 |
327 | .IX Item "EVBACKEND_DEVPOLL (value 16, Solaris 8)" |
538 | .IX Item "EVBACKEND_DEVPOLL (value 16, Solaris 8)" |
328 | This is not implemented yet (and might never be). |
539 | This is not implemented yet (and might never be, unless you send me an |
|
|
540 | implementation). According to reports, \f(CW\*(C`/dev/poll\*(C'\fR only supports sockets |
|
|
541 | and is not embeddable, which would limit the usefulness of this backend |
|
|
542 | immensely. |
329 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
543 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
330 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
544 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
331 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
545 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
332 | This uses the Solaris 10 port mechanism. As with everything on Solaris, |
546 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
333 | it's really slow, but it still scales very well (O(active_fds)). |
547 | it's really slow, but it still scales very well (O(active_fds)). |
334 | .Sp |
548 | .Sp |
335 | Please note that solaris ports can result in a lot of spurious |
549 | Please note that solaris event ports can deliver a lot of spurious |
336 | notifications, so you need to use non-blocking I/O or other means to avoid |
550 | notifications, so you need to use non-blocking I/O or other means to avoid |
337 | blocking when no data (or space) is available. |
551 | blocking when no data (or space) is available. |
|
|
552 | .Sp |
|
|
553 | While this backend scales well, it requires one system call per active |
|
|
554 | file descriptor per loop iteration. For small and medium numbers of file |
|
|
555 | descriptors a \*(L"slow\*(R" \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR backend |
|
|
556 | might perform better. |
|
|
557 | .Sp |
|
|
558 | On the positive side, ignoring the spurious readyness notifications, this |
|
|
559 | backend actually performed to specification in all tests and is fully |
|
|
560 | embeddable, which is a rare feat among the OS-specific backends. |
338 | .ie n .IP """EVBACKEND_ALL""" 4 |
561 | .ie n .IP """EVBACKEND_ALL""" 4 |
339 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
562 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
340 | .IX Item "EVBACKEND_ALL" |
563 | .IX Item "EVBACKEND_ALL" |
341 | Try all backends (even potentially broken ones that wouldn't be tried |
564 | Try all backends (even potentially broken ones that wouldn't be tried |
342 | with \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). Since this is a mask, you can do stuff such as |
565 | with \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). Since this is a mask, you can do stuff such as |
343 | \&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR. |
566 | \&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR. |
|
|
567 | .Sp |
|
|
568 | It is definitely not recommended to use this flag. |
344 | .RE |
569 | .RE |
345 | .RS 4 |
570 | .RS 4 |
346 | .Sp |
571 | .Sp |
347 | If one or more of these are ored into the flags value, then only these |
572 | If one or more of these are ored into the flags value, then only these |
348 | backends will be tried (in the reverse order as given here). If none are |
573 | backends will be tried (in the reverse order as listed here). If none are |
349 | specified, most compiled-in backend will be tried, usually in reverse |
574 | specified, all backends in \f(CW\*(C`ev_recommended_backends ()\*(C'\fR will be tried. |
350 | order of their flag values :) |
575 | .Sp |
|
|
576 | The most typical usage is like this: |
|
|
577 | .Sp |
|
|
578 | .Vb 2 |
|
|
579 | \& if (!ev_default_loop (0)) |
|
|
580 | \& fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
|
|
581 | .Ve |
|
|
582 | .Sp |
|
|
583 | Restrict libev to the select and poll backends, and do not allow |
|
|
584 | environment settings to be taken into account: |
|
|
585 | .Sp |
|
|
586 | .Vb 1 |
|
|
587 | \& ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
|
|
588 | .Ve |
|
|
589 | .Sp |
|
|
590 | Use whatever libev has to offer, but make sure that kqueue is used if |
|
|
591 | available (warning, breaks stuff, best use only with your own private |
|
|
592 | event loop and only if you know the \s-1OS\s0 supports your types of fds): |
|
|
593 | .Sp |
|
|
594 | .Vb 1 |
|
|
595 | \& ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
596 | .Ve |
351 | .RE |
597 | .RE |
352 | .IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4 |
598 | .IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4 |
353 | .IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" |
599 | .IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" |
354 | Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is |
600 | Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is |
355 | always distinct from the default loop. Unlike the default loop, it cannot |
601 | always distinct from the default loop. Unlike the default loop, it cannot |
356 | handle signal and child watchers, and attempts to do so will be greeted by |
602 | handle signal and child watchers, and attempts to do so will be greeted by |
357 | undefined behaviour (or a failed assertion if assertions are enabled). |
603 | undefined behaviour (or a failed assertion if assertions are enabled). |
|
|
604 | .Sp |
|
|
605 | Example: Try to create a event loop that uses epoll and nothing else. |
|
|
606 | .Sp |
|
|
607 | .Vb 3 |
|
|
608 | \& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
|
|
609 | \& if (!epoller) |
|
|
610 | \& fatal ("no epoll found here, maybe it hides under your chair"); |
|
|
611 | .Ve |
358 | .IP "ev_default_destroy ()" 4 |
612 | .IP "ev_default_destroy ()" 4 |
359 | .IX Item "ev_default_destroy ()" |
613 | .IX Item "ev_default_destroy ()" |
360 | Destroys the default loop again (frees all memory and kernel state |
614 | Destroys the default loop again (frees all memory and kernel state |
361 | etc.). This stops all registered event watchers (by not touching them in |
615 | etc.). None of the active event watchers will be stopped in the normal |
362 | any way whatsoever, although you cannot rely on this :). |
616 | sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your |
|
|
617 | responsibility to either stop all watchers cleanly yoursef \fIbefore\fR |
|
|
618 | calling this function, or cope with the fact afterwards (which is usually |
|
|
619 | the easiest thing, you can just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them |
|
|
620 | for example). |
|
|
621 | .Sp |
|
|
622 | Note that certain global state, such as signal state, will not be freed by |
|
|
623 | this function, and related watchers (such as signal and child watchers) |
|
|
624 | would need to be stopped manually. |
|
|
625 | .Sp |
|
|
626 | In general it is not advisable to call this function except in the |
|
|
627 | rare occasion where you really need to free e.g. the signal handling |
|
|
628 | pipe fds. If you need dynamically allocated loops it is better to use |
|
|
629 | \&\f(CW\*(C`ev_loop_new\*(C'\fR and \f(CW\*(C`ev_loop_destroy\*(C'\fR). |
363 | .IP "ev_loop_destroy (loop)" 4 |
630 | .IP "ev_loop_destroy (loop)" 4 |
364 | .IX Item "ev_loop_destroy (loop)" |
631 | .IX Item "ev_loop_destroy (loop)" |
365 | Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an |
632 | Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an |
366 | earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. |
633 | earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. |
367 | .IP "ev_default_fork ()" 4 |
634 | .IP "ev_default_fork ()" 4 |
368 | .IX Item "ev_default_fork ()" |
635 | .IX Item "ev_default_fork ()" |
|
|
636 | This function sets a flag that causes subsequent \f(CW\*(C`ev_loop\*(C'\fR iterations |
369 | This function reinitialises the kernel state for backends that have |
637 | to reinitialise the kernel state for backends that have one. Despite the |
370 | one. Despite the name, you can call it anytime, but it makes most sense |
638 | name, you can call it anytime, but it makes most sense after forking, in |
371 | after forking, in either the parent or child process (or both, but that |
639 | the child process (or both child and parent, but that again makes little |
372 | again makes little sense). |
640 | sense). You \fImust\fR call it in the child before using any of the libev |
|
|
641 | functions, and it will only take effect at the next \f(CW\*(C`ev_loop\*(C'\fR iteration. |
373 | .Sp |
642 | .Sp |
374 | You \fImust\fR call this function in the child process after forking if and |
643 | On the other hand, you only need to call this function in the child |
375 | only if you want to use the event library in both processes. If you just |
644 | process if and only if you want to use the event library in the child. If |
376 | fork+exec, you don't have to call it. |
645 | you just fork+exec, you don't have to call it at all. |
377 | .Sp |
646 | .Sp |
378 | The function itself is quite fast and it's usually not a problem to call |
647 | The function itself is quite fast and it's usually not a problem to call |
379 | it just in case after a fork. To make this easy, the function will fit in |
648 | it just in case after a fork. To make this easy, the function will fit in |
380 | quite nicely into a call to \f(CW\*(C`pthread_atfork\*(C'\fR: |
649 | quite nicely into a call to \f(CW\*(C`pthread_atfork\*(C'\fR: |
381 | .Sp |
650 | .Sp |
382 | .Vb 1 |
651 | .Vb 1 |
383 | \& pthread_atfork (0, 0, ev_default_fork); |
652 | \& pthread_atfork (0, 0, ev_default_fork); |
384 | .Ve |
653 | .Ve |
385 | .Sp |
|
|
386 | At the moment, \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and \f(CW\*(C`EVBACKEND_POLL\*(C'\fR are safe to use |
|
|
387 | without calling this function, so if you force one of those backends you |
|
|
388 | do not need to care. |
|
|
389 | .IP "ev_loop_fork (loop)" 4 |
654 | .IP "ev_loop_fork (loop)" 4 |
390 | .IX Item "ev_loop_fork (loop)" |
655 | .IX Item "ev_loop_fork (loop)" |
391 | Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by |
656 | Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by |
392 | \&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop |
657 | \&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop |
393 | after fork, and how you do this is entirely your own problem. |
658 | after fork, and how you do this is entirely your own problem. |
|
|
659 | .IP "int ev_is_default_loop (loop)" 4 |
|
|
660 | .IX Item "int ev_is_default_loop (loop)" |
|
|
661 | Returns true when the given loop actually is the default loop, false otherwise. |
|
|
662 | .IP "unsigned int ev_loop_count (loop)" 4 |
|
|
663 | .IX Item "unsigned int ev_loop_count (loop)" |
|
|
664 | Returns the count of loop iterations for the loop, which is identical to |
|
|
665 | the number of times libev did poll for new events. It starts at \f(CW0\fR and |
|
|
666 | happily wraps around with enough iterations. |
|
|
667 | .Sp |
|
|
668 | This value can sometimes be useful as a generation counter of sorts (it |
|
|
669 | \&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with |
|
|
670 | \&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls. |
394 | .IP "unsigned int ev_backend (loop)" 4 |
671 | .IP "unsigned int ev_backend (loop)" 4 |
395 | .IX Item "unsigned int ev_backend (loop)" |
672 | .IX Item "unsigned int ev_backend (loop)" |
396 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
673 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
397 | use. |
674 | use. |
398 | .IP "ev_tstamp ev_now (loop)" 4 |
675 | .IP "ev_tstamp ev_now (loop)" 4 |
399 | .IX Item "ev_tstamp ev_now (loop)" |
676 | .IX Item "ev_tstamp ev_now (loop)" |
400 | Returns the current \*(L"event loop time\*(R", which is the time the event loop |
677 | Returns the current \*(L"event loop time\*(R", which is the time the event loop |
401 | got events and started processing them. This timestamp does not change |
678 | received events and started processing them. This timestamp does not |
402 | as long as callbacks are being processed, and this is also the base time |
679 | change as long as callbacks are being processed, and this is also the base |
403 | used for relative timers. You can treat it as the timestamp of the event |
680 | time used for relative timers. You can treat it as the timestamp of the |
404 | occuring (or more correctly, the mainloop finding out about it). |
681 | event occurring (or more correctly, libev finding out about it). |
405 | .IP "ev_loop (loop, int flags)" 4 |
682 | .IP "ev_loop (loop, int flags)" 4 |
406 | .IX Item "ev_loop (loop, int flags)" |
683 | .IX Item "ev_loop (loop, int flags)" |
407 | Finally, this is it, the event handler. This function usually is called |
684 | Finally, this is it, the event handler. This function usually is called |
408 | after you initialised all your watchers and you want to start handling |
685 | after you initialised all your watchers and you want to start handling |
409 | events. |
686 | events. |
410 | .Sp |
687 | .Sp |
411 | If the flags argument is specified as 0, it will not return until either |
688 | If the flags argument is specified as \f(CW0\fR, it will not return until |
412 | no event watchers are active anymore or \f(CW\*(C`ev_unloop\*(C'\fR was called. |
689 | either no event watchers are active anymore or \f(CW\*(C`ev_unloop\*(C'\fR was called. |
|
|
690 | .Sp |
|
|
691 | Please note that an explicit \f(CW\*(C`ev_unloop\*(C'\fR is usually better than |
|
|
692 | relying on all watchers to be stopped when deciding when a program has |
|
|
693 | finished (especially in interactive programs), but having a program that |
|
|
694 | automatically loops as long as it has to and no longer by virtue of |
|
|
695 | relying on its watchers stopping correctly is a thing of beauty. |
413 | .Sp |
696 | .Sp |
414 | A flags value of \f(CW\*(C`EVLOOP_NONBLOCK\*(C'\fR will look for new events, will handle |
697 | A flags value of \f(CW\*(C`EVLOOP_NONBLOCK\*(C'\fR will look for new events, will handle |
415 | those events and any outstanding ones, but will not block your process in |
698 | those events and any outstanding ones, but will not block your process in |
416 | case there are no events and will return after one iteration of the loop. |
699 | case there are no events and will return after one iteration of the loop. |
417 | .Sp |
700 | .Sp |
418 | A flags value of \f(CW\*(C`EVLOOP_ONESHOT\*(C'\fR will look for new events (waiting if |
701 | A flags value of \f(CW\*(C`EVLOOP_ONESHOT\*(C'\fR will look for new events (waiting if |
419 | neccessary) and will handle those and any outstanding ones. It will block |
702 | neccessary) and will handle those and any outstanding ones. It will block |
420 | your process until at least one new event arrives, and will return after |
703 | your process until at least one new event arrives, and will return after |
421 | one iteration of the loop. |
704 | one iteration of the loop. This is useful if you are waiting for some |
|
|
705 | external event in conjunction with something not expressible using other |
|
|
706 | libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is |
|
|
707 | usually a better approach for this kind of thing. |
422 | .Sp |
708 | .Sp |
423 | This flags value could be used to implement alternative looping |
|
|
424 | constructs, but the \f(CW\*(C`prepare\*(C'\fR and \f(CW\*(C`check\*(C'\fR watchers provide a better and |
|
|
425 | more generic mechanism. |
|
|
426 | .Sp |
|
|
427 | Here are the gory details of what ev_loop does: |
709 | Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does: |
428 | .Sp |
710 | .Sp |
429 | .Vb 15 |
711 | .Vb 10 |
430 | \& 1. If there are no active watchers (reference count is zero), return. |
712 | \& \- Before the first iteration, call any pending watchers. |
|
|
713 | \& * If EVFLAG_FORKCHECK was used, check for a fork. |
|
|
714 | \& \- If a fork was detected, queue and call all fork watchers. |
431 | \& 2. Queue and immediately call all prepare watchers. |
715 | \& \- Queue and call all prepare watchers. |
432 | \& 3. If we have been forked, recreate the kernel state. |
716 | \& \- If we have been forked, recreate the kernel state. |
433 | \& 4. Update the kernel state with all outstanding changes. |
717 | \& \- Update the kernel state with all outstanding changes. |
434 | \& 5. Update the "event loop time". |
718 | \& \- Update the "event loop time". |
435 | \& 6. Calculate for how long to block. |
719 | \& \- Calculate for how long to sleep or block, if at all |
|
|
720 | \& (active idle watchers, EVLOOP_NONBLOCK or not having |
|
|
721 | \& any active watchers at all will result in not sleeping). |
|
|
722 | \& \- Sleep if the I/O and timer collect interval say so. |
436 | \& 7. Block the process, waiting for events. |
723 | \& \- Block the process, waiting for any events. |
|
|
724 | \& \- Queue all outstanding I/O (fd) events. |
437 | \& 8. Update the "event loop time" and do time jump handling. |
725 | \& \- Update the "event loop time" and do time jump handling. |
438 | \& 9. Queue all outstanding timers. |
726 | \& \- Queue all outstanding timers. |
439 | \& 10. Queue all outstanding periodics. |
727 | \& \- Queue all outstanding periodics. |
440 | \& 11. If no events are pending now, queue all idle watchers. |
728 | \& \- If no events are pending now, queue all idle watchers. |
441 | \& 12. Queue all check watchers. |
729 | \& \- Queue all check watchers. |
442 | \& 13. Call all queued watchers in reverse order (i.e. check watchers first). |
730 | \& \- Call all queued watchers in reverse order (i.e. check watchers first). |
|
|
731 | \& Signals and child watchers are implemented as I/O watchers, and will |
|
|
732 | \& be handled here by queueing them when their watcher gets executed. |
443 | \& 14. If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
733 | \& \- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
444 | \& was used, return, otherwise continue with step #1. |
734 | \& were used, or there are no active watchers, return, otherwise |
|
|
735 | \& continue with step *. |
|
|
736 | .Ve |
|
|
737 | .Sp |
|
|
738 | Example: Queue some jobs and then loop until no events are outstanding |
|
|
739 | anymore. |
|
|
740 | .Sp |
|
|
741 | .Vb 4 |
|
|
742 | \& ... queue jobs here, make sure they register event watchers as long |
|
|
743 | \& ... as they still have work to do (even an idle watcher will do..) |
|
|
744 | \& ev_loop (my_loop, 0); |
|
|
745 | \& ... jobs done. yeah! |
445 | .Ve |
746 | .Ve |
446 | .IP "ev_unloop (loop, how)" 4 |
747 | .IP "ev_unloop (loop, how)" 4 |
447 | .IX Item "ev_unloop (loop, how)" |
748 | .IX Item "ev_unloop (loop, how)" |
448 | Can be used to make a call to \f(CW\*(C`ev_loop\*(C'\fR return early (but only after it |
749 | Can be used to make a call to \f(CW\*(C`ev_loop\*(C'\fR return early (but only after it |
449 | has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either |
750 | has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either |
450 | \&\f(CW\*(C`EVUNLOOP_ONE\*(C'\fR, which will make the innermost \f(CW\*(C`ev_loop\*(C'\fR call return, or |
751 | \&\f(CW\*(C`EVUNLOOP_ONE\*(C'\fR, which will make the innermost \f(CW\*(C`ev_loop\*(C'\fR call return, or |
451 | \&\f(CW\*(C`EVUNLOOP_ALL\*(C'\fR, which will make all nested \f(CW\*(C`ev_loop\*(C'\fR calls return. |
752 | \&\f(CW\*(C`EVUNLOOP_ALL\*(C'\fR, which will make all nested \f(CW\*(C`ev_loop\*(C'\fR calls return. |
|
|
753 | .Sp |
|
|
754 | This \*(L"unloop state\*(R" will be cleared when entering \f(CW\*(C`ev_loop\*(C'\fR again. |
452 | .IP "ev_ref (loop)" 4 |
755 | .IP "ev_ref (loop)" 4 |
453 | .IX Item "ev_ref (loop)" |
756 | .IX Item "ev_ref (loop)" |
454 | .PD 0 |
757 | .PD 0 |
455 | .IP "ev_unref (loop)" 4 |
758 | .IP "ev_unref (loop)" 4 |
456 | .IX Item "ev_unref (loop)" |
759 | .IX Item "ev_unref (loop)" |
… | |
… | |
462 | returning, \fIev_unref()\fR after starting, and \fIev_ref()\fR before stopping it. For |
765 | returning, \fIev_unref()\fR after starting, and \fIev_ref()\fR before stopping it. For |
463 | example, libev itself uses this for its internal signal pipe: It is not |
766 | example, libev itself uses this for its internal signal pipe: It is not |
464 | visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting if |
767 | visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting if |
465 | no event watchers registered by it are active. It is also an excellent |
768 | no event watchers registered by it are active. It is also an excellent |
466 | way to do this for generic recurring timers or from within third-party |
769 | way to do this for generic recurring timers or from within third-party |
467 | libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR. |
770 | libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR |
|
|
771 | (but only if the watcher wasn't active before, or was active before, |
|
|
772 | respectively). |
|
|
773 | .Sp |
|
|
774 | Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR |
|
|
775 | running when nothing else is active. |
|
|
776 | .Sp |
|
|
777 | .Vb 4 |
|
|
778 | \& struct ev_signal exitsig; |
|
|
779 | \& ev_signal_init (&exitsig, sig_cb, SIGINT); |
|
|
780 | \& ev_signal_start (loop, &exitsig); |
|
|
781 | \& evf_unref (loop); |
|
|
782 | .Ve |
|
|
783 | .Sp |
|
|
784 | Example: For some weird reason, unregister the above signal handler again. |
|
|
785 | .Sp |
|
|
786 | .Vb 2 |
|
|
787 | \& ev_ref (loop); |
|
|
788 | \& ev_signal_stop (loop, &exitsig); |
|
|
789 | .Ve |
|
|
790 | .IP "ev_set_io_collect_interval (loop, ev_tstamp interval)" 4 |
|
|
791 | .IX Item "ev_set_io_collect_interval (loop, ev_tstamp interval)" |
|
|
792 | .PD 0 |
|
|
793 | .IP "ev_set_timeout_collect_interval (loop, ev_tstamp interval)" 4 |
|
|
794 | .IX Item "ev_set_timeout_collect_interval (loop, ev_tstamp interval)" |
|
|
795 | .PD |
|
|
796 | These advanced functions influence the time that libev will spend waiting |
|
|
797 | for events. Both are by default \f(CW0\fR, meaning that libev will try to |
|
|
798 | invoke timer/periodic callbacks and I/O callbacks with minimum latency. |
|
|
799 | .Sp |
|
|
800 | Setting these to a higher value (the \f(CW\*(C`interval\*(C'\fR \fImust\fR be >= \f(CW0\fR) |
|
|
801 | allows libev to delay invocation of I/O and timer/periodic callbacks to |
|
|
802 | increase efficiency of loop iterations. |
|
|
803 | .Sp |
|
|
804 | The background is that sometimes your program runs just fast enough to |
|
|
805 | handle one (or very few) event(s) per loop iteration. While this makes |
|
|
806 | the program responsive, it also wastes a lot of \s-1CPU\s0 time to poll for new |
|
|
807 | events, especially with backends like \f(CW\*(C`select ()\*(C'\fR which have a high |
|
|
808 | overhead for the actual polling but can deliver many events at once. |
|
|
809 | .Sp |
|
|
810 | By setting a higher \fIio collect interval\fR you allow libev to spend more |
|
|
811 | time collecting I/O events, so you can handle more events per iteration, |
|
|
812 | at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and |
|
|
813 | \&\f(CW\*(C`ev_timer\*(C'\fR) will be not affected. Setting this to a non-null value will |
|
|
814 | introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. |
|
|
815 | .Sp |
|
|
816 | Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
|
|
817 | to spend more time collecting timeouts, at the expense of increased |
|
|
818 | latency (the watcher callback will be called later). \f(CW\*(C`ev_io\*(C'\fR watchers |
|
|
819 | will not be affected. Setting this to a non-null value will not introduce |
|
|
820 | any overhead in libev. |
|
|
821 | .Sp |
|
|
822 | Many (busy) programs can usually benefit by setting the io collect |
|
|
823 | interval to a value near \f(CW0.1\fR or so, which is often enough for |
|
|
824 | interactive servers (of course not for games), likewise for timeouts. It |
|
|
825 | usually doesn't make much sense to set it to a lower value than \f(CW0.01\fR, |
|
|
826 | as this approsaches the timing granularity of most systems. |
468 | .SH "ANATOMY OF A WATCHER" |
827 | .SH "ANATOMY OF A WATCHER" |
469 | .IX Header "ANATOMY OF A WATCHER" |
828 | .IX Header "ANATOMY OF A WATCHER" |
470 | A watcher is a structure that you create and register to record your |
829 | A watcher is a structure that you create and register to record your |
471 | interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to |
830 | interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to |
472 | become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that: |
831 | become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that: |
… | |
… | |
475 | \& static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
834 | \& static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
476 | \& { |
835 | \& { |
477 | \& ev_io_stop (w); |
836 | \& ev_io_stop (w); |
478 | \& ev_unloop (loop, EVUNLOOP_ALL); |
837 | \& ev_unloop (loop, EVUNLOOP_ALL); |
479 | \& } |
838 | \& } |
480 | .Ve |
839 | \& |
481 | .PP |
|
|
482 | .Vb 6 |
|
|
483 | \& struct ev_loop *loop = ev_default_loop (0); |
840 | \& struct ev_loop *loop = ev_default_loop (0); |
484 | \& struct ev_io stdin_watcher; |
841 | \& struct ev_io stdin_watcher; |
485 | \& ev_init (&stdin_watcher, my_cb); |
842 | \& ev_init (&stdin_watcher, my_cb); |
486 | \& ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
843 | \& ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
487 | \& ev_io_start (loop, &stdin_watcher); |
844 | \& ev_io_start (loop, &stdin_watcher); |
… | |
… | |
508 | *)\*(C'\fR), and you can stop watching for events at any time by calling the |
865 | *)\*(C'\fR), and you can stop watching for events at any time by calling the |
509 | corresponding stop function (\f(CW\*(C`ev_<type>_stop (loop, watcher *)\*(C'\fR. |
866 | corresponding stop function (\f(CW\*(C`ev_<type>_stop (loop, watcher *)\*(C'\fR. |
510 | .PP |
867 | .PP |
511 | As long as your watcher is active (has been started but not stopped) you |
868 | As long as your watcher is active (has been started but not stopped) you |
512 | must not touch the values stored in it. Most specifically you must never |
869 | must not touch the values stored in it. Most specifically you must never |
513 | reinitialise it or call its set macro. |
870 | reinitialise it or call its \f(CW\*(C`set\*(C'\fR macro. |
514 | .PP |
|
|
515 | You can check whether an event is active by calling the \f(CW\*(C`ev_is_active |
|
|
516 | (watcher *)\*(C'\fR macro. To see whether an event is outstanding (but the |
|
|
517 | callback for it has not been called yet) you can use the \f(CW\*(C`ev_is_pending |
|
|
518 | (watcher *)\*(C'\fR macro. |
|
|
519 | .PP |
871 | .PP |
520 | Each and every callback receives the event loop pointer as first, the |
872 | Each and every callback receives the event loop pointer as first, the |
521 | registered watcher structure as second, and a bitset of received events as |
873 | registered watcher structure as second, and a bitset of received events as |
522 | third argument. |
874 | third argument. |
523 | .PP |
875 | .PP |
… | |
… | |
548 | The signal specified in the \f(CW\*(C`ev_signal\*(C'\fR watcher has been received by a thread. |
900 | The signal specified in the \f(CW\*(C`ev_signal\*(C'\fR watcher has been received by a thread. |
549 | .ie n .IP """EV_CHILD""" 4 |
901 | .ie n .IP """EV_CHILD""" 4 |
550 | .el .IP "\f(CWEV_CHILD\fR" 4 |
902 | .el .IP "\f(CWEV_CHILD\fR" 4 |
551 | .IX Item "EV_CHILD" |
903 | .IX Item "EV_CHILD" |
552 | The pid specified in the \f(CW\*(C`ev_child\*(C'\fR watcher has received a status change. |
904 | The pid specified in the \f(CW\*(C`ev_child\*(C'\fR watcher has received a status change. |
|
|
905 | .ie n .IP """EV_STAT""" 4 |
|
|
906 | .el .IP "\f(CWEV_STAT\fR" 4 |
|
|
907 | .IX Item "EV_STAT" |
|
|
908 | The path specified in the \f(CW\*(C`ev_stat\*(C'\fR watcher changed its attributes somehow. |
553 | .ie n .IP """EV_IDLE""" 4 |
909 | .ie n .IP """EV_IDLE""" 4 |
554 | .el .IP "\f(CWEV_IDLE\fR" 4 |
910 | .el .IP "\f(CWEV_IDLE\fR" 4 |
555 | .IX Item "EV_IDLE" |
911 | .IX Item "EV_IDLE" |
556 | The \f(CW\*(C`ev_idle\*(C'\fR watcher has determined that you have nothing better to do. |
912 | The \f(CW\*(C`ev_idle\*(C'\fR watcher has determined that you have nothing better to do. |
557 | .ie n .IP """EV_PREPARE""" 4 |
913 | .ie n .IP """EV_PREPARE""" 4 |
… | |
… | |
567 | \&\f(CW\*(C`ev_loop\*(C'\fR has gathered them, but before it invokes any callbacks for any |
923 | \&\f(CW\*(C`ev_loop\*(C'\fR has gathered them, but before it invokes any callbacks for any |
568 | received events. Callbacks of both watcher types can start and stop as |
924 | received events. Callbacks of both watcher types can start and stop as |
569 | many watchers as they want, and all of them will be taken into account |
925 | many watchers as they want, and all of them will be taken into account |
570 | (for example, a \f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep |
926 | (for example, a \f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep |
571 | \&\f(CW\*(C`ev_loop\*(C'\fR from blocking). |
927 | \&\f(CW\*(C`ev_loop\*(C'\fR from blocking). |
|
|
928 | .ie n .IP """EV_EMBED""" 4 |
|
|
929 | .el .IP "\f(CWEV_EMBED\fR" 4 |
|
|
930 | .IX Item "EV_EMBED" |
|
|
931 | The embedded event loop specified in the \f(CW\*(C`ev_embed\*(C'\fR watcher needs attention. |
|
|
932 | .ie n .IP """EV_FORK""" 4 |
|
|
933 | .el .IP "\f(CWEV_FORK\fR" 4 |
|
|
934 | .IX Item "EV_FORK" |
|
|
935 | The event loop has been resumed in the child process after fork (see |
|
|
936 | \&\f(CW\*(C`ev_fork\*(C'\fR). |
|
|
937 | .ie n .IP """EV_ASYNC""" 4 |
|
|
938 | .el .IP "\f(CWEV_ASYNC\fR" 4 |
|
|
939 | .IX Item "EV_ASYNC" |
|
|
940 | The given async watcher has been asynchronously notified (see \f(CW\*(C`ev_async\*(C'\fR). |
572 | .ie n .IP """EV_ERROR""" 4 |
941 | .ie n .IP """EV_ERROR""" 4 |
573 | .el .IP "\f(CWEV_ERROR\fR" 4 |
942 | .el .IP "\f(CWEV_ERROR\fR" 4 |
574 | .IX Item "EV_ERROR" |
943 | .IX Item "EV_ERROR" |
575 | An unspecified error has occured, the watcher has been stopped. This might |
944 | An unspecified error has occured, the watcher has been stopped. This might |
576 | happen because the watcher could not be properly started because libev |
945 | happen because the watcher could not be properly started because libev |
… | |
… | |
581 | Libev will usually signal a few \*(L"dummy\*(R" events together with an error, |
950 | Libev will usually signal a few \*(L"dummy\*(R" events together with an error, |
582 | for example it might indicate that a fd is readable or writable, and if |
951 | for example it might indicate that a fd is readable or writable, and if |
583 | your callbacks is well-written it can just attempt the operation and cope |
952 | your callbacks is well-written it can just attempt the operation and cope |
584 | with the error from \fIread()\fR or \fIwrite()\fR. This will not work in multithreaded |
953 | with the error from \fIread()\fR or \fIwrite()\fR. This will not work in multithreaded |
585 | programs, though, so beware. |
954 | programs, though, so beware. |
|
|
955 | .Sh "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" |
|
|
956 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
|
|
957 | In the following description, \f(CW\*(C`TYPE\*(C'\fR stands for the watcher type, |
|
|
958 | e.g. \f(CW\*(C`timer\*(C'\fR for \f(CW\*(C`ev_timer\*(C'\fR watchers and \f(CW\*(C`io\*(C'\fR for \f(CW\*(C`ev_io\*(C'\fR watchers. |
|
|
959 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
|
|
960 | .el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 |
|
|
961 | .IX Item "ev_init (ev_TYPE *watcher, callback)" |
|
|
962 | This macro initialises the generic portion of a watcher. The contents |
|
|
963 | of the watcher object can be arbitrary (so \f(CW\*(C`malloc\*(C'\fR will do). Only |
|
|
964 | the generic parts of the watcher are initialised, you \fIneed\fR to call |
|
|
965 | the type-specific \f(CW\*(C`ev_TYPE_set\*(C'\fR macro afterwards to initialise the |
|
|
966 | type-specific parts. For each type there is also a \f(CW\*(C`ev_TYPE_init\*(C'\fR macro |
|
|
967 | which rolls both calls into one. |
|
|
968 | .Sp |
|
|
969 | You can reinitialise a watcher at any time as long as it has been stopped |
|
|
970 | (or never started) and there are no pending events outstanding. |
|
|
971 | .Sp |
|
|
972 | The callback is always of type \f(CW\*(C`void (*)(ev_loop *loop, ev_TYPE *watcher, |
|
|
973 | int revents)\*(C'\fR. |
|
|
974 | .ie n .IP """ev_TYPE_set"" (ev_TYPE *, [args])" 4 |
|
|
975 | .el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *, [args])" 4 |
|
|
976 | .IX Item "ev_TYPE_set (ev_TYPE *, [args])" |
|
|
977 | This macro initialises the type-specific parts of a watcher. You need to |
|
|
978 | call \f(CW\*(C`ev_init\*(C'\fR at least once before you call this macro, but you can |
|
|
979 | call \f(CW\*(C`ev_TYPE_set\*(C'\fR any number of times. You must not, however, call this |
|
|
980 | macro on a watcher that is active (it can be pending, however, which is a |
|
|
981 | difference to the \f(CW\*(C`ev_init\*(C'\fR macro). |
|
|
982 | .Sp |
|
|
983 | Although some watcher types do not have type-specific arguments |
|
|
984 | (e.g. \f(CW\*(C`ev_prepare\*(C'\fR) you still need to call its \f(CW\*(C`set\*(C'\fR macro. |
|
|
985 | .ie n .IP """ev_TYPE_init"" (ev_TYPE *watcher, callback, [args])" 4 |
|
|
986 | .el .IP "\f(CWev_TYPE_init\fR (ev_TYPE *watcher, callback, [args])" 4 |
|
|
987 | .IX Item "ev_TYPE_init (ev_TYPE *watcher, callback, [args])" |
|
|
988 | This convinience macro rolls both \f(CW\*(C`ev_init\*(C'\fR and \f(CW\*(C`ev_TYPE_set\*(C'\fR macro |
|
|
989 | calls into a single call. This is the most convinient method to initialise |
|
|
990 | a watcher. The same limitations apply, of course. |
|
|
991 | .ie n .IP """ev_TYPE_start"" (loop *, ev_TYPE *watcher)" 4 |
|
|
992 | .el .IP "\f(CWev_TYPE_start\fR (loop *, ev_TYPE *watcher)" 4 |
|
|
993 | .IX Item "ev_TYPE_start (loop *, ev_TYPE *watcher)" |
|
|
994 | Starts (activates) the given watcher. Only active watchers will receive |
|
|
995 | events. If the watcher is already active nothing will happen. |
|
|
996 | .ie n .IP """ev_TYPE_stop"" (loop *, ev_TYPE *watcher)" 4 |
|
|
997 | .el .IP "\f(CWev_TYPE_stop\fR (loop *, ev_TYPE *watcher)" 4 |
|
|
998 | .IX Item "ev_TYPE_stop (loop *, ev_TYPE *watcher)" |
|
|
999 | Stops the given watcher again (if active) and clears the pending |
|
|
1000 | status. It is possible that stopped watchers are pending (for example, |
|
|
1001 | non-repeating timers are being stopped when they become pending), but |
|
|
1002 | \&\f(CW\*(C`ev_TYPE_stop\*(C'\fR ensures that the watcher is neither active nor pending. If |
|
|
1003 | you want to free or reuse the memory used by the watcher it is therefore a |
|
|
1004 | good idea to always call its \f(CW\*(C`ev_TYPE_stop\*(C'\fR function. |
|
|
1005 | .IP "bool ev_is_active (ev_TYPE *watcher)" 4 |
|
|
1006 | .IX Item "bool ev_is_active (ev_TYPE *watcher)" |
|
|
1007 | Returns a true value iff the watcher is active (i.e. it has been started |
|
|
1008 | and not yet been stopped). As long as a watcher is active you must not modify |
|
|
1009 | it. |
|
|
1010 | .IP "bool ev_is_pending (ev_TYPE *watcher)" 4 |
|
|
1011 | .IX Item "bool ev_is_pending (ev_TYPE *watcher)" |
|
|
1012 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
|
|
1013 | events but its callback has not yet been invoked). As long as a watcher |
|
|
1014 | is pending (but not active) you must not call an init function on it (but |
|
|
1015 | \&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe), you must not change its priority, and you must |
|
|
1016 | make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR |
|
|
1017 | it). |
|
|
1018 | .IP "callback ev_cb (ev_TYPE *watcher)" 4 |
|
|
1019 | .IX Item "callback ev_cb (ev_TYPE *watcher)" |
|
|
1020 | Returns the callback currently set on the watcher. |
|
|
1021 | .IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 |
|
|
1022 | .IX Item "ev_cb_set (ev_TYPE *watcher, callback)" |
|
|
1023 | Change the callback. You can change the callback at virtually any time |
|
|
1024 | (modulo threads). |
|
|
1025 | .IP "ev_set_priority (ev_TYPE *watcher, priority)" 4 |
|
|
1026 | .IX Item "ev_set_priority (ev_TYPE *watcher, priority)" |
|
|
1027 | .PD 0 |
|
|
1028 | .IP "int ev_priority (ev_TYPE *watcher)" 4 |
|
|
1029 | .IX Item "int ev_priority (ev_TYPE *watcher)" |
|
|
1030 | .PD |
|
|
1031 | Set and query the priority of the watcher. The priority is a small |
|
|
1032 | integer between \f(CW\*(C`EV_MAXPRI\*(C'\fR (default: \f(CW2\fR) and \f(CW\*(C`EV_MINPRI\*(C'\fR |
|
|
1033 | (default: \f(CW\*(C`\-2\*(C'\fR). Pending watchers with higher priority will be invoked |
|
|
1034 | before watchers with lower priority, but priority will not keep watchers |
|
|
1035 | from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers). |
|
|
1036 | .Sp |
|
|
1037 | This means that priorities are \fIonly\fR used for ordering callback |
|
|
1038 | invocation after new events have been received. This is useful, for |
|
|
1039 | example, to reduce latency after idling, or more often, to bind two |
|
|
1040 | watchers on the same event and make sure one is called first. |
|
|
1041 | .Sp |
|
|
1042 | If you need to suppress invocation when higher priority events are pending |
|
|
1043 | you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality. |
|
|
1044 | .Sp |
|
|
1045 | You \fImust not\fR change the priority of a watcher as long as it is active or |
|
|
1046 | pending. |
|
|
1047 | .Sp |
|
|
1048 | The default priority used by watchers when no priority has been set is |
|
|
1049 | always \f(CW0\fR, which is supposed to not be too high and not be too low :). |
|
|
1050 | .Sp |
|
|
1051 | Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is |
|
|
1052 | fine, as long as you do not mind that the priority value you query might |
|
|
1053 | or might not have been adjusted to be within valid range. |
|
|
1054 | .IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 |
|
|
1055 | .IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" |
|
|
1056 | Invoke the \f(CW\*(C`watcher\*(C'\fR with the given \f(CW\*(C`loop\*(C'\fR and \f(CW\*(C`revents\*(C'\fR. Neither |
|
|
1057 | \&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback |
|
|
1058 | can deal with that fact. |
|
|
1059 | .IP "int ev_clear_pending (loop, ev_TYPE *watcher)" 4 |
|
|
1060 | .IX Item "int ev_clear_pending (loop, ev_TYPE *watcher)" |
|
|
1061 | If the watcher is pending, this function returns clears its pending status |
|
|
1062 | and returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the |
|
|
1063 | watcher isn't pending it does nothing and returns \f(CW0\fR. |
586 | .Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
1064 | .Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
587 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
1065 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
588 | Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change |
1066 | Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change |
589 | and read at any time, libev will completely ignore it. This can be used |
1067 | and read at any time, libev will completely ignore it. This can be used |
590 | to associate arbitrary data with your watcher. If you need more data and |
1068 | to associate arbitrary data with your watcher. If you need more data and |
… | |
… | |
611 | \& struct my_io *w = (struct my_io *)w_; |
1089 | \& struct my_io *w = (struct my_io *)w_; |
612 | \& ... |
1090 | \& ... |
613 | \& } |
1091 | \& } |
614 | .Ve |
1092 | .Ve |
615 | .PP |
1093 | .PP |
616 | More interesting and less C\-conformant ways of catsing your callback type |
1094 | More interesting and less C\-conformant ways of casting your callback type |
617 | have been omitted.... |
1095 | instead have been omitted. |
|
|
1096 | .PP |
|
|
1097 | Another common scenario is having some data structure with multiple |
|
|
1098 | watchers: |
|
|
1099 | .PP |
|
|
1100 | .Vb 6 |
|
|
1101 | \& struct my_biggy |
|
|
1102 | \& { |
|
|
1103 | \& int some_data; |
|
|
1104 | \& ev_timer t1; |
|
|
1105 | \& ev_timer t2; |
|
|
1106 | \& } |
|
|
1107 | .Ve |
|
|
1108 | .PP |
|
|
1109 | In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more complicated, |
|
|
1110 | you need to use \f(CW\*(C`offsetof\*(C'\fR: |
|
|
1111 | .PP |
|
|
1112 | .Vb 1 |
|
|
1113 | \& #include <stddef.h> |
|
|
1114 | \& |
|
|
1115 | \& static void |
|
|
1116 | \& t1_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
1117 | \& { |
|
|
1118 | \& struct my_biggy big = (struct my_biggy * |
|
|
1119 | \& (((char *)w) \- offsetof (struct my_biggy, t1)); |
|
|
1120 | \& } |
|
|
1121 | \& |
|
|
1122 | \& static void |
|
|
1123 | \& t2_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
1124 | \& { |
|
|
1125 | \& struct my_biggy big = (struct my_biggy * |
|
|
1126 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
|
|
1127 | \& } |
|
|
1128 | .Ve |
618 | .SH "WATCHER TYPES" |
1129 | .SH "WATCHER TYPES" |
619 | .IX Header "WATCHER TYPES" |
1130 | .IX Header "WATCHER TYPES" |
620 | This section describes each watcher in detail, but will not repeat |
1131 | This section describes each watcher in detail, but will not repeat |
621 | information given in the last section. |
1132 | information given in the last section. Any initialisation/set macros, |
|
|
1133 | functions and members specific to the watcher type are explained. |
|
|
1134 | .PP |
|
|
1135 | Members are additionally marked with either \fI[read\-only]\fR, meaning that, |
|
|
1136 | while the watcher is active, you can look at the member and expect some |
|
|
1137 | sensible content, but you must not modify it (you can modify it while the |
|
|
1138 | watcher is stopped to your hearts content), or \fI[read\-write]\fR, which |
|
|
1139 | means you can expect it to have some sensible content while the watcher |
|
|
1140 | is active, but you can also modify it. Modifying it may not do something |
|
|
1141 | sensible or take immediate effect (or do anything at all), but libev will |
|
|
1142 | not crash or malfunction in any way. |
622 | .ie n .Sh """ev_io"" \- is this file descriptor readable or writable" |
1143 | .ie n .Sh """ev_io"" \- is this file descriptor readable or writable?" |
623 | .el .Sh "\f(CWev_io\fP \- is this file descriptor readable or writable" |
1144 | .el .Sh "\f(CWev_io\fP \- is this file descriptor readable or writable?" |
624 | .IX Subsection "ev_io - is this file descriptor readable or writable" |
1145 | .IX Subsection "ev_io - is this file descriptor readable or writable?" |
625 | I/O watchers check whether a file descriptor is readable or writable |
1146 | I/O watchers check whether a file descriptor is readable or writable |
626 | in each iteration of the event loop (This behaviour is called |
1147 | in each iteration of the event loop, or, more precisely, when reading |
627 | level-triggering because you keep receiving events as long as the |
1148 | would not block the process and writing would at least be able to write |
628 | condition persists. Remember you can stop the watcher if you don't want to |
1149 | some data. This behaviour is called level-triggering because you keep |
629 | act on the event and neither want to receive future events). |
1150 | receiving events as long as the condition persists. Remember you can stop |
|
|
1151 | the watcher if you don't want to act on the event and neither want to |
|
|
1152 | receive future events. |
630 | .PP |
1153 | .PP |
631 | In general you can register as many read and/or write event watchers per |
1154 | In general you can register as many read and/or write event watchers per |
632 | fd as you want (as long as you don't confuse yourself). Setting all file |
1155 | fd as you want (as long as you don't confuse yourself). Setting all file |
633 | descriptors to non-blocking mode is also usually a good idea (but not |
1156 | descriptors to non-blocking mode is also usually a good idea (but not |
634 | required if you know what you are doing). |
1157 | required if you know what you are doing). |
635 | .PP |
1158 | .PP |
636 | You have to be careful with dup'ed file descriptors, though. Some backends |
|
|
637 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
|
|
638 | descriptors correctly if you register interest in two or more fds pointing |
|
|
639 | to the same underlying file/socket etc. description (that is, they share |
|
|
640 | the same underlying \*(L"file open\*(R"). |
|
|
641 | .PP |
|
|
642 | If you must do this, then force the use of a known-to-be-good backend |
1159 | If you must do this, then force the use of a known-to-be-good backend |
643 | (at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and |
1160 | (at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and |
644 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR). |
1161 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR). |
|
|
1162 | .PP |
|
|
1163 | Another thing you have to watch out for is that it is quite easy to |
|
|
1164 | receive \*(L"spurious\*(R" readyness notifications, that is your callback might |
|
|
1165 | be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block |
|
|
1166 | because there is no data. Not only are some backends known to create a |
|
|
1167 | lot of those (for example solaris ports), it is very easy to get into |
|
|
1168 | this situation even with a relatively standard program structure. Thus |
|
|
1169 | it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning |
|
|
1170 | \&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives. |
|
|
1171 | .PP |
|
|
1172 | If you cannot run the fd in non-blocking mode (for example you should not |
|
|
1173 | play around with an Xlib connection), then you have to seperately re-test |
|
|
1174 | whether a file descriptor is really ready with a known-to-be good interface |
|
|
1175 | such as poll (fortunately in our Xlib example, Xlib already does this on |
|
|
1176 | its own, so its quite safe to use). |
|
|
1177 | .PP |
|
|
1178 | \fIThe special problem of disappearing file descriptors\fR |
|
|
1179 | .IX Subsection "The special problem of disappearing file descriptors" |
|
|
1180 | .PP |
|
|
1181 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
|
|
1182 | descriptor (either by calling \f(CW\*(C`close\*(C'\fR explicitly or by any other means, |
|
|
1183 | such as \f(CW\*(C`dup\*(C'\fR). The reason is that you register interest in some file |
|
|
1184 | descriptor, but when it goes away, the operating system will silently drop |
|
|
1185 | this interest. If another file descriptor with the same number then is |
|
|
1186 | registered with libev, there is no efficient way to see that this is, in |
|
|
1187 | fact, a different file descriptor. |
|
|
1188 | .PP |
|
|
1189 | To avoid having to explicitly tell libev about such cases, libev follows |
|
|
1190 | the following policy: Each time \f(CW\*(C`ev_io_set\*(C'\fR is being called, libev |
|
|
1191 | will assume that this is potentially a new file descriptor, otherwise |
|
|
1192 | it is assumed that the file descriptor stays the same. That means that |
|
|
1193 | you \fIhave\fR to call \f(CW\*(C`ev_io_set\*(C'\fR (or \f(CW\*(C`ev_io_init\*(C'\fR) when you change the |
|
|
1194 | descriptor even if the file descriptor number itself did not change. |
|
|
1195 | .PP |
|
|
1196 | This is how one would do it normally anyway, the important point is that |
|
|
1197 | the libev application should not optimise around libev but should leave |
|
|
1198 | optimisations to libev. |
|
|
1199 | .PP |
|
|
1200 | \fIThe special problem of dup'ed file descriptors\fR |
|
|
1201 | .IX Subsection "The special problem of dup'ed file descriptors" |
|
|
1202 | .PP |
|
|
1203 | Some backends (e.g. epoll), cannot register events for file descriptors, |
|
|
1204 | but only events for the underlying file descriptions. That means when you |
|
|
1205 | have \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors or weirder constellations, and register |
|
|
1206 | events for them, only one file descriptor might actually receive events. |
|
|
1207 | .PP |
|
|
1208 | There is no workaround possible except not registering events |
|
|
1209 | for potentially \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors, or to resort to |
|
|
1210 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
|
|
1211 | .PP |
|
|
1212 | \fIThe special problem of fork\fR |
|
|
1213 | .IX Subsection "The special problem of fork" |
|
|
1214 | .PP |
|
|
1215 | Some backends (epoll, kqueue) do not support \f(CW\*(C`fork ()\*(C'\fR at all or exhibit |
|
|
1216 | useless behaviour. Libev fully supports fork, but needs to be told about |
|
|
1217 | it in the child. |
|
|
1218 | .PP |
|
|
1219 | To support fork in your programs, you either have to call |
|
|
1220 | \&\f(CW\*(C`ev_default_fork ()\*(C'\fR or \f(CW\*(C`ev_loop_fork ()\*(C'\fR after a fork in the child, |
|
|
1221 | enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or |
|
|
1222 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
|
|
1223 | .PP |
|
|
1224 | \fIWatcher-Specific Functions\fR |
|
|
1225 | .IX Subsection "Watcher-Specific Functions" |
645 | .IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 |
1226 | .IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 |
646 | .IX Item "ev_io_init (ev_io *, callback, int fd, int events)" |
1227 | .IX Item "ev_io_init (ev_io *, callback, int fd, int events)" |
647 | .PD 0 |
1228 | .PD 0 |
648 | .IP "ev_io_set (ev_io *, int fd, int events)" 4 |
1229 | .IP "ev_io_set (ev_io *, int fd, int events)" 4 |
649 | .IX Item "ev_io_set (ev_io *, int fd, int events)" |
1230 | .IX Item "ev_io_set (ev_io *, int fd, int events)" |
650 | .PD |
1231 | .PD |
651 | Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The fd is the file descriptor to rceeive |
1232 | Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The \f(CW\*(C`fd\*(C'\fR is the file descriptor to |
652 | events for and events is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or \f(CW\*(C`EV_READ | |
1233 | rceeive events for and events is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or |
653 | EV_WRITE\*(C'\fR to receive the given events. |
1234 | \&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR to receive the given events. |
654 | .Sp |
1235 | .IP "int fd [read\-only]" 4 |
655 | Please note that most of the more scalable backend mechanisms (for example |
1236 | .IX Item "int fd [read-only]" |
656 | epoll and solaris ports) can result in spurious readyness notifications |
1237 | The file descriptor being watched. |
657 | for file descriptors, so you practically need to use non-blocking I/O (and |
1238 | .IP "int events [read\-only]" 4 |
658 | treat callback invocation as hint only), or retest separately with a safe |
1239 | .IX Item "int events [read-only]" |
659 | interface before doing I/O (XLib can do this), or force the use of either |
1240 | The events being watched. |
660 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR, which don't suffer from this |
1241 | .PP |
661 | problem. Also note that it is quite easy to have your callback invoked |
1242 | \fIExamples\fR |
662 | when the readyness condition is no longer valid even when employing |
1243 | .IX Subsection "Examples" |
663 | typical ways of handling events, so its a good idea to use non-blocking |
1244 | .PP |
664 | I/O unconditionally. |
1245 | Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well |
|
|
1246 | readable, but only once. Since it is likely line-buffered, you could |
|
|
1247 | attempt to read a whole line in the callback. |
|
|
1248 | .PP |
|
|
1249 | .Vb 6 |
|
|
1250 | \& static void |
|
|
1251 | \& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
|
|
1252 | \& { |
|
|
1253 | \& ev_io_stop (loop, w); |
|
|
1254 | \& .. read from stdin here (or from w\->fd) and haqndle any I/O errors |
|
|
1255 | \& } |
|
|
1256 | \& |
|
|
1257 | \& ... |
|
|
1258 | \& struct ev_loop *loop = ev_default_init (0); |
|
|
1259 | \& struct ev_io stdin_readable; |
|
|
1260 | \& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
|
|
1261 | \& ev_io_start (loop, &stdin_readable); |
|
|
1262 | \& ev_loop (loop, 0); |
|
|
1263 | .Ve |
665 | .ie n .Sh """ev_timer"" \- relative and optionally recurring timeouts" |
1264 | .ie n .Sh """ev_timer"" \- relative and optionally repeating timeouts" |
666 | .el .Sh "\f(CWev_timer\fP \- relative and optionally recurring timeouts" |
1265 | .el .Sh "\f(CWev_timer\fP \- relative and optionally repeating timeouts" |
667 | .IX Subsection "ev_timer - relative and optionally recurring timeouts" |
1266 | .IX Subsection "ev_timer - relative and optionally repeating timeouts" |
668 | Timer watchers are simple relative timers that generate an event after a |
1267 | Timer watchers are simple relative timers that generate an event after a |
669 | given time, and optionally repeating in regular intervals after that. |
1268 | given time, and optionally repeating in regular intervals after that. |
670 | .PP |
1269 | .PP |
671 | The timers are based on real time, that is, if you register an event that |
1270 | The timers are based on real time, that is, if you register an event that |
672 | times out after an hour and you reset your system clock to last years |
1271 | times out after an hour and you reset your system clock to last years |
… | |
… | |
679 | of the event triggering whatever timeout you are modifying/starting. If |
1278 | of the event triggering whatever timeout you are modifying/starting. If |
680 | you suspect event processing to be delayed and you \fIneed\fR to base the timeout |
1279 | you suspect event processing to be delayed and you \fIneed\fR to base the timeout |
681 | on the current time, use something like this to adjust for this: |
1280 | on the current time, use something like this to adjust for this: |
682 | .PP |
1281 | .PP |
683 | .Vb 1 |
1282 | .Vb 1 |
684 | \& ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
1283 | \& ev_timer_set (&timer, after + ev_now () \- ev_time (), 0.); |
685 | .Ve |
1284 | .Ve |
686 | .PP |
1285 | .PP |
687 | The callback is guarenteed to be invoked only when its timeout has passed, |
1286 | The callback is guarenteed to be invoked only when its timeout has passed, |
688 | but if multiple timers become ready during the same loop iteration then |
1287 | but if multiple timers become ready during the same loop iteration then |
689 | order of execution is undefined. |
1288 | order of execution is undefined. |
|
|
1289 | .PP |
|
|
1290 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
1291 | .IX Subsection "Watcher-Specific Functions and Data Members" |
690 | .IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 |
1292 | .IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 |
691 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
1293 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
692 | .PD 0 |
1294 | .PD 0 |
693 | .IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 |
1295 | .IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 |
694 | .IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" |
1296 | .IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" |
… | |
… | |
701 | The timer itself will do a best-effort at avoiding drift, that is, if you |
1303 | The timer itself will do a best-effort at avoiding drift, that is, if you |
702 | configure a timer to trigger every 10 seconds, then it will trigger at |
1304 | configure a timer to trigger every 10 seconds, then it will trigger at |
703 | exactly 10 second intervals. If, however, your program cannot keep up with |
1305 | exactly 10 second intervals. If, however, your program cannot keep up with |
704 | the timer (because it takes longer than those 10 seconds to do stuff) the |
1306 | the timer (because it takes longer than those 10 seconds to do stuff) the |
705 | timer will not fire more than once per event loop iteration. |
1307 | timer will not fire more than once per event loop iteration. |
706 | .IP "ev_timer_again (loop)" 4 |
1308 | .IP "ev_timer_again (loop, ev_timer *)" 4 |
707 | .IX Item "ev_timer_again (loop)" |
1309 | .IX Item "ev_timer_again (loop, ev_timer *)" |
708 | This will act as if the timer timed out and restart it again if it is |
1310 | This will act as if the timer timed out and restart it again if it is |
709 | repeating. The exact semantics are: |
1311 | repeating. The exact semantics are: |
710 | .Sp |
1312 | .Sp |
|
|
1313 | If the timer is pending, its pending status is cleared. |
|
|
1314 | .Sp |
711 | If the timer is started but nonrepeating, stop it. |
1315 | If the timer is started but nonrepeating, stop it (as if it timed out). |
712 | .Sp |
1316 | .Sp |
713 | If the timer is repeating, either start it if necessary (with the repeat |
1317 | If the timer is repeating, either start it if necessary (with the |
714 | value), or reset the running timer to the repeat value. |
1318 | \&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value. |
715 | .Sp |
1319 | .Sp |
716 | This sounds a bit complicated, but here is a useful and typical |
1320 | This sounds a bit complicated, but here is a useful and typical |
717 | example: Imagine you have a tcp connection and you want a so-called idle |
1321 | example: Imagine you have a tcp connection and you want a so-called idle |
718 | timeout, that is, you want to be called when there have been, say, 60 |
1322 | timeout, that is, you want to be called when there have been, say, 60 |
719 | seconds of inactivity on the socket. The easiest way to do this is to |
1323 | seconds of inactivity on the socket. The easiest way to do this is to |
720 | configure an \f(CW\*(C`ev_timer\*(C'\fR with after=repeat=60 and calling ev_timer_again each |
1324 | configure an \f(CW\*(C`ev_timer\*(C'\fR with a \f(CW\*(C`repeat\*(C'\fR value of \f(CW60\fR and then call |
721 | time you successfully read or write some data. If you go into an idle |
1325 | \&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If |
722 | state where you do not expect data to travel on the socket, you can stop |
1326 | you go into an idle state where you do not expect data to travel on the |
723 | the timer, and again will automatically restart it if need be. |
1327 | socket, you can \f(CW\*(C`ev_timer_stop\*(C'\fR the timer, and \f(CW\*(C`ev_timer_again\*(C'\fR will |
|
|
1328 | automatically restart it if need be. |
|
|
1329 | .Sp |
|
|
1330 | That means you can ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR |
|
|
1331 | altogether and only ever use the \f(CW\*(C`repeat\*(C'\fR value and \f(CW\*(C`ev_timer_again\*(C'\fR: |
|
|
1332 | .Sp |
|
|
1333 | .Vb 8 |
|
|
1334 | \& ev_timer_init (timer, callback, 0., 5.); |
|
|
1335 | \& ev_timer_again (loop, timer); |
|
|
1336 | \& ... |
|
|
1337 | \& timer\->again = 17.; |
|
|
1338 | \& ev_timer_again (loop, timer); |
|
|
1339 | \& ... |
|
|
1340 | \& timer\->again = 10.; |
|
|
1341 | \& ev_timer_again (loop, timer); |
|
|
1342 | .Ve |
|
|
1343 | .Sp |
|
|
1344 | This is more slightly efficient then stopping/starting the timer each time |
|
|
1345 | you want to modify its timeout value. |
|
|
1346 | .IP "ev_tstamp repeat [read\-write]" 4 |
|
|
1347 | .IX Item "ev_tstamp repeat [read-write]" |
|
|
1348 | The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out |
|
|
1349 | or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any), |
|
|
1350 | which is also when any modifications are taken into account. |
|
|
1351 | .PP |
|
|
1352 | \fIExamples\fR |
|
|
1353 | .IX Subsection "Examples" |
|
|
1354 | .PP |
|
|
1355 | Example: Create a timer that fires after 60 seconds. |
|
|
1356 | .PP |
|
|
1357 | .Vb 5 |
|
|
1358 | \& static void |
|
|
1359 | \& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
|
|
1360 | \& { |
|
|
1361 | \& .. one minute over, w is actually stopped right here |
|
|
1362 | \& } |
|
|
1363 | \& |
|
|
1364 | \& struct ev_timer mytimer; |
|
|
1365 | \& ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
|
|
1366 | \& ev_timer_start (loop, &mytimer); |
|
|
1367 | .Ve |
|
|
1368 | .PP |
|
|
1369 | Example: Create a timeout timer that times out after 10 seconds of |
|
|
1370 | inactivity. |
|
|
1371 | .PP |
|
|
1372 | .Vb 5 |
|
|
1373 | \& static void |
|
|
1374 | \& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
|
|
1375 | \& { |
|
|
1376 | \& .. ten seconds without any activity |
|
|
1377 | \& } |
|
|
1378 | \& |
|
|
1379 | \& struct ev_timer mytimer; |
|
|
1380 | \& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
|
|
1381 | \& ev_timer_again (&mytimer); /* start timer */ |
|
|
1382 | \& ev_loop (loop, 0); |
|
|
1383 | \& |
|
|
1384 | \& // and in some piece of code that gets executed on any "activity": |
|
|
1385 | \& // reset the timeout to start ticking again at 10 seconds |
|
|
1386 | \& ev_timer_again (&mytimer); |
|
|
1387 | .Ve |
724 | .ie n .Sh """ev_periodic"" \- to cron or not to cron" |
1388 | .ie n .Sh """ev_periodic"" \- to cron or not to cron?" |
725 | .el .Sh "\f(CWev_periodic\fP \- to cron or not to cron" |
1389 | .el .Sh "\f(CWev_periodic\fP \- to cron or not to cron?" |
726 | .IX Subsection "ev_periodic - to cron or not to cron" |
1390 | .IX Subsection "ev_periodic - to cron or not to cron?" |
727 | Periodic watchers are also timers of a kind, but they are very versatile |
1391 | Periodic watchers are also timers of a kind, but they are very versatile |
728 | (and unfortunately a bit complex). |
1392 | (and unfortunately a bit complex). |
729 | .PP |
1393 | .PP |
730 | Unlike \f(CW\*(C`ev_timer\*(C'\fR's, they are not based on real time (or relative time) |
1394 | Unlike \f(CW\*(C`ev_timer\*(C'\fR's, they are not based on real time (or relative time) |
731 | but on wallclock time (absolute time). You can tell a periodic watcher |
1395 | but on wallclock time (absolute time). You can tell a periodic watcher |
732 | to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a |
1396 | to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a |
733 | periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now () |
1397 | periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now () |
734 | + 10.>) and then reset your system clock to the last year, then it will |
1398 | + 10.\*(C'\fR) and then reset your system clock to the last year, then it will |
735 | take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger |
1399 | take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger |
736 | roughly 10 seconds later and of course not if you reset your system time |
1400 | roughly 10 seconds later). |
737 | again). |
|
|
738 | .PP |
1401 | .PP |
739 | They can also be used to implement vastly more complex timers, such as |
1402 | They can also be used to implement vastly more complex timers, such as |
740 | triggering an event on eahc midnight, local time. |
1403 | triggering an event on each midnight, local time or other, complicated, |
|
|
1404 | rules. |
741 | .PP |
1405 | .PP |
742 | As with timers, the callback is guarenteed to be invoked only when the |
1406 | As with timers, the callback is guarenteed to be invoked only when the |
743 | time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready |
1407 | time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready |
744 | during the same loop iteration then order of execution is undefined. |
1408 | during the same loop iteration then order of execution is undefined. |
|
|
1409 | .PP |
|
|
1410 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
1411 | .IX Subsection "Watcher-Specific Functions and Data Members" |
745 | .IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4 |
1412 | .IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4 |
746 | .IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" |
1413 | .IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" |
747 | .PD 0 |
1414 | .PD 0 |
748 | .IP "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 4 |
1415 | .IP "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 4 |
749 | .IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" |
1416 | .IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" |
750 | .PD |
1417 | .PD |
751 | Lots of arguments, lets sort it out... There are basically three modes of |
1418 | Lots of arguments, lets sort it out... There are basically three modes of |
752 | operation, and we will explain them from simplest to complex: |
1419 | operation, and we will explain them from simplest to complex: |
753 | .RS 4 |
1420 | .RS 4 |
|
|
1421 | .IP "\(bu" 4 |
754 | .IP "* absolute timer (interval = reschedule_cb = 0)" 4 |
1422 | absolute timer (at = time, interval = reschedule_cb = 0) |
755 | .IX Item "absolute timer (interval = reschedule_cb = 0)" |
1423 | .Sp |
756 | In this configuration the watcher triggers an event at the wallclock time |
1424 | In this configuration the watcher triggers an event at the wallclock time |
757 | \&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs, |
1425 | \&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs, |
758 | that is, if it is to be run at January 1st 2011 then it will run when the |
1426 | that is, if it is to be run at January 1st 2011 then it will run when the |
759 | system time reaches or surpasses this time. |
1427 | system time reaches or surpasses this time. |
|
|
1428 | .IP "\(bu" 4 |
760 | .IP "* non-repeating interval timer (interval > 0, reschedule_cb = 0)" 4 |
1429 | repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
761 | .IX Item "non-repeating interval timer (interval > 0, reschedule_cb = 0)" |
1430 | .Sp |
762 | In this mode the watcher will always be scheduled to time out at the next |
1431 | In this mode the watcher will always be scheduled to time out at the next |
763 | \&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N) and then repeat, regardless |
1432 | \&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N, which can also be negative) |
764 | of any time jumps. |
1433 | and then repeat, regardless of any time jumps. |
765 | .Sp |
1434 | .Sp |
766 | This can be used to create timers that do not drift with respect to system |
1435 | This can be used to create timers that do not drift with respect to system |
767 | time: |
1436 | time: |
768 | .Sp |
1437 | .Sp |
769 | .Vb 1 |
1438 | .Vb 1 |
… | |
… | |
776 | by 3600. |
1445 | by 3600. |
777 | .Sp |
1446 | .Sp |
778 | Another way to think about it (for the mathematically inclined) is that |
1447 | Another way to think about it (for the mathematically inclined) is that |
779 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
1448 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
780 | time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps. |
1449 | time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps. |
781 | .IP "* manual reschedule mode (reschedule_cb = callback)" 4 |
1450 | .Sp |
782 | .IX Item "manual reschedule mode (reschedule_cb = callback)" |
1451 | For numerical stability it is preferable that the \f(CW\*(C`at\*(C'\fR value is near |
|
|
1452 | \&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for |
|
|
1453 | this value. |
|
|
1454 | .IP "\(bu" 4 |
|
|
1455 | manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
|
|
1456 | .Sp |
783 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being |
1457 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being |
784 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1458 | ignored. Instead, each time the periodic watcher gets scheduled, the |
785 | reschedule callback will be called with the watcher as first, and the |
1459 | reschedule callback will be called with the watcher as first, and the |
786 | current time as second argument. |
1460 | current time as second argument. |
787 | .Sp |
1461 | .Sp |
788 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, |
1462 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, |
789 | ever, or make any event loop modifications\fR. If you need to stop it, |
1463 | ever, or make any event loop modifications\fR. If you need to stop it, |
790 | return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by |
1464 | return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by |
791 | starting a prepare watcher). |
1465 | starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is legal). |
792 | .Sp |
1466 | .Sp |
793 | Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1467 | Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
794 | ev_tstamp now)\*(C'\fR, e.g.: |
1468 | ev_tstamp now)\*(C'\fR, e.g.: |
795 | .Sp |
1469 | .Sp |
796 | .Vb 4 |
1470 | .Vb 4 |
… | |
… | |
820 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
1494 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
821 | Simply stops and restarts the periodic watcher again. This is only useful |
1495 | Simply stops and restarts the periodic watcher again. This is only useful |
822 | when you changed some parameters or the reschedule callback would return |
1496 | when you changed some parameters or the reschedule callback would return |
823 | a different time than the last time it was called (e.g. in a crond like |
1497 | a different time than the last time it was called (e.g. in a crond like |
824 | program when the crontabs have changed). |
1498 | program when the crontabs have changed). |
|
|
1499 | .IP "ev_tstamp offset [read\-write]" 4 |
|
|
1500 | .IX Item "ev_tstamp offset [read-write]" |
|
|
1501 | When repeating, this contains the offset value, otherwise this is the |
|
|
1502 | absolute point in time (the \f(CW\*(C`at\*(C'\fR value passed to \f(CW\*(C`ev_periodic_set\*(C'\fR). |
|
|
1503 | .Sp |
|
|
1504 | Can be modified any time, but changes only take effect when the periodic |
|
|
1505 | timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
|
|
1506 | .IP "ev_tstamp interval [read\-write]" 4 |
|
|
1507 | .IX Item "ev_tstamp interval [read-write]" |
|
|
1508 | The current interval value. Can be modified any time, but changes only |
|
|
1509 | take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being |
|
|
1510 | called. |
|
|
1511 | .IP "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read\-write]" 4 |
|
|
1512 | .IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]" |
|
|
1513 | The current reschedule callback, or \f(CW0\fR, if this functionality is |
|
|
1514 | switched off. Can be changed any time, but changes only take effect when |
|
|
1515 | the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
|
|
1516 | .IP "ev_tstamp at [read\-only]" 4 |
|
|
1517 | .IX Item "ev_tstamp at [read-only]" |
|
|
1518 | When active, contains the absolute time that the watcher is supposed to |
|
|
1519 | trigger next. |
|
|
1520 | .PP |
|
|
1521 | \fIExamples\fR |
|
|
1522 | .IX Subsection "Examples" |
|
|
1523 | .PP |
|
|
1524 | Example: Call a callback every hour, or, more precisely, whenever the |
|
|
1525 | system clock is divisible by 3600. The callback invocation times have |
|
|
1526 | potentially a lot of jittering, but good long-term stability. |
|
|
1527 | .PP |
|
|
1528 | .Vb 5 |
|
|
1529 | \& static void |
|
|
1530 | \& clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
|
|
1531 | \& { |
|
|
1532 | \& ... its now a full hour (UTC, or TAI or whatever your clock follows) |
|
|
1533 | \& } |
|
|
1534 | \& |
|
|
1535 | \& struct ev_periodic hourly_tick; |
|
|
1536 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
|
|
1537 | \& ev_periodic_start (loop, &hourly_tick); |
|
|
1538 | .Ve |
|
|
1539 | .PP |
|
|
1540 | Example: The same as above, but use a reschedule callback to do it: |
|
|
1541 | .PP |
|
|
1542 | .Vb 1 |
|
|
1543 | \& #include <math.h> |
|
|
1544 | \& |
|
|
1545 | \& static ev_tstamp |
|
|
1546 | \& my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
|
|
1547 | \& { |
|
|
1548 | \& return fmod (now, 3600.) + 3600.; |
|
|
1549 | \& } |
|
|
1550 | \& |
|
|
1551 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
|
|
1552 | .Ve |
|
|
1553 | .PP |
|
|
1554 | Example: Call a callback every hour, starting now: |
|
|
1555 | .PP |
|
|
1556 | .Vb 4 |
|
|
1557 | \& struct ev_periodic hourly_tick; |
|
|
1558 | \& ev_periodic_init (&hourly_tick, clock_cb, |
|
|
1559 | \& fmod (ev_now (loop), 3600.), 3600., 0); |
|
|
1560 | \& ev_periodic_start (loop, &hourly_tick); |
|
|
1561 | .Ve |
825 | .ie n .Sh """ev_signal"" \- signal me when a signal gets signalled" |
1562 | .ie n .Sh """ev_signal"" \- signal me when a signal gets signalled!" |
826 | .el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled" |
1563 | .el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled!" |
827 | .IX Subsection "ev_signal - signal me when a signal gets signalled" |
1564 | .IX Subsection "ev_signal - signal me when a signal gets signalled!" |
828 | Signal watchers will trigger an event when the process receives a specific |
1565 | Signal watchers will trigger an event when the process receives a specific |
829 | signal one or more times. Even though signals are very asynchronous, libev |
1566 | signal one or more times. Even though signals are very asynchronous, libev |
830 | will try it's best to deliver signals synchronously, i.e. as part of the |
1567 | will try it's best to deliver signals synchronously, i.e. as part of the |
831 | normal event processing, like any other event. |
1568 | normal event processing, like any other event. |
832 | .PP |
1569 | .PP |
… | |
… | |
834 | first watcher gets started will libev actually register a signal watcher |
1571 | first watcher gets started will libev actually register a signal watcher |
835 | with the kernel (thus it coexists with your own signal handlers as long |
1572 | with the kernel (thus it coexists with your own signal handlers as long |
836 | as you don't register any with libev). Similarly, when the last signal |
1573 | as you don't register any with libev). Similarly, when the last signal |
837 | watcher for a signal is stopped libev will reset the signal handler to |
1574 | watcher for a signal is stopped libev will reset the signal handler to |
838 | \&\s-1SIG_DFL\s0 (regardless of what it was set to before). |
1575 | \&\s-1SIG_DFL\s0 (regardless of what it was set to before). |
|
|
1576 | .PP |
|
|
1577 | If possible and supported, libev will install its handlers with |
|
|
1578 | \&\f(CW\*(C`SA_RESTART\*(C'\fR behaviour enabled, so syscalls should not be unduly |
|
|
1579 | interrupted. If you have a problem with syscalls getting interrupted by |
|
|
1580 | signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher and unblock |
|
|
1581 | them in an \f(CW\*(C`ev_prepare\*(C'\fR watcher. |
|
|
1582 | .PP |
|
|
1583 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
1584 | .IX Subsection "Watcher-Specific Functions and Data Members" |
839 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
1585 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
840 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
1586 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
841 | .PD 0 |
1587 | .PD 0 |
842 | .IP "ev_signal_set (ev_signal *, int signum)" 4 |
1588 | .IP "ev_signal_set (ev_signal *, int signum)" 4 |
843 | .IX Item "ev_signal_set (ev_signal *, int signum)" |
1589 | .IX Item "ev_signal_set (ev_signal *, int signum)" |
844 | .PD |
1590 | .PD |
845 | Configures the watcher to trigger on the given signal number (usually one |
1591 | Configures the watcher to trigger on the given signal number (usually one |
846 | of the \f(CW\*(C`SIGxxx\*(C'\fR constants). |
1592 | of the \f(CW\*(C`SIGxxx\*(C'\fR constants). |
|
|
1593 | .IP "int signum [read\-only]" 4 |
|
|
1594 | .IX Item "int signum [read-only]" |
|
|
1595 | The signal the watcher watches out for. |
|
|
1596 | .PP |
|
|
1597 | \fIExamples\fR |
|
|
1598 | .IX Subsection "Examples" |
|
|
1599 | .PP |
|
|
1600 | Example: Try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0. |
|
|
1601 | .PP |
|
|
1602 | .Vb 5 |
|
|
1603 | \& static void |
|
|
1604 | \& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
|
|
1605 | \& { |
|
|
1606 | \& ev_unloop (loop, EVUNLOOP_ALL); |
|
|
1607 | \& } |
|
|
1608 | \& |
|
|
1609 | \& struct ev_signal signal_watcher; |
|
|
1610 | \& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
|
|
1611 | \& ev_signal_start (loop, &sigint_cb); |
|
|
1612 | .Ve |
847 | .ie n .Sh """ev_child"" \- wait for pid status changes" |
1613 | .ie n .Sh """ev_child"" \- watch out for process status changes" |
848 | .el .Sh "\f(CWev_child\fP \- wait for pid status changes" |
1614 | .el .Sh "\f(CWev_child\fP \- watch out for process status changes" |
849 | .IX Subsection "ev_child - wait for pid status changes" |
1615 | .IX Subsection "ev_child - watch out for process status changes" |
850 | Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to |
1616 | Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to |
851 | some child status changes (most typically when a child of yours dies). |
1617 | some child status changes (most typically when a child of yours dies). It |
|
|
1618 | is permissible to install a child watcher \fIafter\fR the child has been |
|
|
1619 | forked (which implies it might have already exited), as long as the event |
|
|
1620 | loop isn't entered (or is continued from a watcher). |
|
|
1621 | .PP |
|
|
1622 | Only the default event loop is capable of handling signals, and therefore |
|
|
1623 | you can only rgeister child watchers in the default event loop. |
|
|
1624 | .PP |
|
|
1625 | \fIProcess Interaction\fR |
|
|
1626 | .IX Subsection "Process Interaction" |
|
|
1627 | .PP |
|
|
1628 | Libev grabs \f(CW\*(C`SIGCHLD\*(C'\fR as soon as the default event loop is |
|
|
1629 | initialised. This is necessary to guarantee proper behaviour even if |
|
|
1630 | the first child watcher is started after the child exits. The occurance |
|
|
1631 | of \f(CW\*(C`SIGCHLD\*(C'\fR is recorded asynchronously, but child reaping is done |
|
|
1632 | synchronously as part of the event loop processing. Libev always reaps all |
|
|
1633 | children, even ones not watched. |
|
|
1634 | .PP |
|
|
1635 | \fIOverriding the Built-In Processing\fR |
|
|
1636 | .IX Subsection "Overriding the Built-In Processing" |
|
|
1637 | .PP |
|
|
1638 | Libev offers no special support for overriding the built-in child |
|
|
1639 | processing, but if your application collides with libev's default child |
|
|
1640 | handler, you can override it easily by installing your own handler for |
|
|
1641 | \&\f(CW\*(C`SIGCHLD\*(C'\fR after initialising the default loop, and making sure the |
|
|
1642 | default loop never gets destroyed. You are encouraged, however, to use an |
|
|
1643 | event-based approach to child reaping and thus use libev's support for |
|
|
1644 | that, so other libev users can use \f(CW\*(C`ev_child\*(C'\fR watchers freely. |
|
|
1645 | .PP |
|
|
1646 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
1647 | .IX Subsection "Watcher-Specific Functions and Data Members" |
852 | .IP "ev_child_init (ev_child *, callback, int pid)" 4 |
1648 | .IP "ev_child_init (ev_child *, callback, int pid, int trace)" 4 |
853 | .IX Item "ev_child_init (ev_child *, callback, int pid)" |
1649 | .IX Item "ev_child_init (ev_child *, callback, int pid, int trace)" |
854 | .PD 0 |
1650 | .PD 0 |
855 | .IP "ev_child_set (ev_child *, int pid)" 4 |
1651 | .IP "ev_child_set (ev_child *, int pid, int trace)" 4 |
856 | .IX Item "ev_child_set (ev_child *, int pid)" |
1652 | .IX Item "ev_child_set (ev_child *, int pid, int trace)" |
857 | .PD |
1653 | .PD |
858 | Configures the watcher to wait for status changes of process \f(CW\*(C`pid\*(C'\fR (or |
1654 | Configures the watcher to wait for status changes of process \f(CW\*(C`pid\*(C'\fR (or |
859 | \&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look |
1655 | \&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look |
860 | at the \f(CW\*(C`rstatus\*(C'\fR member of the \f(CW\*(C`ev_child\*(C'\fR watcher structure to see |
1656 | at the \f(CW\*(C`rstatus\*(C'\fR member of the \f(CW\*(C`ev_child\*(C'\fR watcher structure to see |
861 | the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems |
1657 | the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems |
862 | \&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the |
1658 | \&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the |
863 | process causing the status change. |
1659 | process causing the status change. \f(CW\*(C`trace\*(C'\fR must be either \f(CW0\fR (only |
|
|
1660 | activate the watcher when the process terminates) or \f(CW1\fR (additionally |
|
|
1661 | activate the watcher when the process is stopped or continued). |
|
|
1662 | .IP "int pid [read\-only]" 4 |
|
|
1663 | .IX Item "int pid [read-only]" |
|
|
1664 | The process id this watcher watches out for, or \f(CW0\fR, meaning any process id. |
|
|
1665 | .IP "int rpid [read\-write]" 4 |
|
|
1666 | .IX Item "int rpid [read-write]" |
|
|
1667 | The process id that detected a status change. |
|
|
1668 | .IP "int rstatus [read\-write]" 4 |
|
|
1669 | .IX Item "int rstatus [read-write]" |
|
|
1670 | The process exit/trace status caused by \f(CW\*(C`rpid\*(C'\fR (see your systems |
|
|
1671 | \&\f(CW\*(C`waitpid\*(C'\fR and \f(CW\*(C`sys/wait.h\*(C'\fR documentation for details). |
|
|
1672 | .PP |
|
|
1673 | \fIExamples\fR |
|
|
1674 | .IX Subsection "Examples" |
|
|
1675 | .PP |
|
|
1676 | Example: \f(CW\*(C`fork()\*(C'\fR a new process and install a child handler to wait for |
|
|
1677 | its completion. |
|
|
1678 | .PP |
|
|
1679 | .Vb 1 |
|
|
1680 | \& ev_child cw; |
|
|
1681 | \& |
|
|
1682 | \& static void |
|
|
1683 | \& child_cb (EV_P_ struct ev_child *w, int revents) |
|
|
1684 | \& { |
|
|
1685 | \& ev_child_stop (EV_A_ w); |
|
|
1686 | \& printf ("process %d exited with status %x\en", w\->rpid, w\->rstatus); |
|
|
1687 | \& } |
|
|
1688 | \& |
|
|
1689 | \& pid_t pid = fork (); |
|
|
1690 | \& |
|
|
1691 | \& if (pid < 0) |
|
|
1692 | \& // error |
|
|
1693 | \& else if (pid == 0) |
|
|
1694 | \& { |
|
|
1695 | \& // the forked child executes here |
|
|
1696 | \& exit (1); |
|
|
1697 | \& } |
|
|
1698 | \& else |
|
|
1699 | \& { |
|
|
1700 | \& ev_child_init (&cw, child_cb, pid, 0); |
|
|
1701 | \& ev_child_start (EV_DEFAULT_ &cw); |
|
|
1702 | \& } |
|
|
1703 | .Ve |
|
|
1704 | .ie n .Sh """ev_stat"" \- did the file attributes just change?" |
|
|
1705 | .el .Sh "\f(CWev_stat\fP \- did the file attributes just change?" |
|
|
1706 | .IX Subsection "ev_stat - did the file attributes just change?" |
|
|
1707 | This watches a filesystem path for attribute changes. That is, it calls |
|
|
1708 | \&\f(CW\*(C`stat\*(C'\fR regularly (or when the \s-1OS\s0 says it changed) and sees if it changed |
|
|
1709 | compared to the last time, invoking the callback if it did. |
|
|
1710 | .PP |
|
|
1711 | The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does |
|
|
1712 | not exist\*(R" is a status change like any other. The condition \*(L"path does |
|
|
1713 | not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is |
|
|
1714 | otherwise always forced to be at least one) and all the other fields of |
|
|
1715 | the stat buffer having unspecified contents. |
|
|
1716 | .PP |
|
|
1717 | The path \fIshould\fR be absolute and \fImust not\fR end in a slash. If it is |
|
|
1718 | relative and your working directory changes, the behaviour is undefined. |
|
|
1719 | .PP |
|
|
1720 | Since there is no standard to do this, the portable implementation simply |
|
|
1721 | calls \f(CW\*(C`stat (2)\*(C'\fR regularly on the path to see if it changed somehow. You |
|
|
1722 | can specify a recommended polling interval for this case. If you specify |
|
|
1723 | a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable, |
|
|
1724 | unspecified default\fR value will be used (which you can expect to be around |
|
|
1725 | five seconds, although this might change dynamically). Libev will also |
|
|
1726 | impose a minimum interval which is currently around \f(CW0.1\fR, but thats |
|
|
1727 | usually overkill. |
|
|
1728 | .PP |
|
|
1729 | This watcher type is not meant for massive numbers of stat watchers, |
|
|
1730 | as even with OS-supported change notifications, this can be |
|
|
1731 | resource-intensive. |
|
|
1732 | .PP |
|
|
1733 | At the time of this writing, only the Linux inotify interface is |
|
|
1734 | implemented (implementing kqueue support is left as an exercise for the |
|
|
1735 | reader). Inotify will be used to give hints only and should not change the |
|
|
1736 | semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers, which means that libev sometimes needs |
|
|
1737 | to fall back to regular polling again even with inotify, but changes are |
|
|
1738 | usually detected immediately, and if the file exists there will be no |
|
|
1739 | polling. |
|
|
1740 | .PP |
|
|
1741 | \fIInotify\fR |
|
|
1742 | .IX Subsection "Inotify" |
|
|
1743 | .PP |
|
|
1744 | When \f(CW\*(C`inotify (7)\*(C'\fR support has been compiled into libev (generally only |
|
|
1745 | available on Linux) and present at runtime, it will be used to speed up |
|
|
1746 | change detection where possible. The inotify descriptor will be created lazily |
|
|
1747 | when the first \f(CW\*(C`ev_stat\*(C'\fR watcher is being started. |
|
|
1748 | .PP |
|
|
1749 | Inotify presense does not change the semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers |
|
|
1750 | except that changes might be detected earlier, and in some cases, to avoid |
|
|
1751 | making regular \f(CW\*(C`stat\*(C'\fR calls. Even in the presense of inotify support |
|
|
1752 | there are many cases where libev has to resort to regular \f(CW\*(C`stat\*(C'\fR polling. |
|
|
1753 | .PP |
|
|
1754 | (There is no support for kqueue, as apparently it cannot be used to |
|
|
1755 | implement this functionality, due to the requirement of having a file |
|
|
1756 | descriptor open on the object at all times). |
|
|
1757 | .PP |
|
|
1758 | \fIThe special problem of stat time resolution\fR |
|
|
1759 | .IX Subsection "The special problem of stat time resolution" |
|
|
1760 | .PP |
|
|
1761 | The \f(CW\*(C`stat ()\*(C'\fR syscall only supports full-second resolution portably, and |
|
|
1762 | even on systems where the resolution is higher, many filesystems still |
|
|
1763 | only support whole seconds. |
|
|
1764 | .PP |
|
|
1765 | That means that, if the time is the only thing that changes, you might |
|
|
1766 | miss updates: on the first update, \f(CW\*(C`ev_stat\*(C'\fR detects a change and calls |
|
|
1767 | your callback, which does something. When there is another update within |
|
|
1768 | the same second, \f(CW\*(C`ev_stat\*(C'\fR will be unable to detect it. |
|
|
1769 | .PP |
|
|
1770 | The solution to this is to delay acting on a change for a second (or till |
|
|
1771 | the next second boundary), using a roughly one-second delay \f(CW\*(C`ev_timer\*(C'\fR |
|
|
1772 | (\f(CW\*(C`ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)\*(C'\fR). The \f(CW.01\fR |
|
|
1773 | is added to work around small timing inconsistencies of some operating |
|
|
1774 | systems. |
|
|
1775 | .PP |
|
|
1776 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
1777 | .IX Subsection "Watcher-Specific Functions and Data Members" |
|
|
1778 | .IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4 |
|
|
1779 | .IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" |
|
|
1780 | .PD 0 |
|
|
1781 | .IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4 |
|
|
1782 | .IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" |
|
|
1783 | .PD |
|
|
1784 | Configures the watcher to wait for status changes of the given |
|
|
1785 | \&\f(CW\*(C`path\*(C'\fR. The \f(CW\*(C`interval\*(C'\fR is a hint on how quickly a change is expected to |
|
|
1786 | be detected and should normally be specified as \f(CW0\fR to let libev choose |
|
|
1787 | a suitable value. The memory pointed to by \f(CW\*(C`path\*(C'\fR must point to the same |
|
|
1788 | path for as long as the watcher is active. |
|
|
1789 | .Sp |
|
|
1790 | The callback will be receive \f(CW\*(C`EV_STAT\*(C'\fR when a change was detected, |
|
|
1791 | relative to the attributes at the time the watcher was started (or the |
|
|
1792 | last change was detected). |
|
|
1793 | .IP "ev_stat_stat (loop, ev_stat *)" 4 |
|
|
1794 | .IX Item "ev_stat_stat (loop, ev_stat *)" |
|
|
1795 | Updates the stat buffer immediately with new values. If you change the |
|
|
1796 | watched path in your callback, you could call this fucntion to avoid |
|
|
1797 | detecting this change (while introducing a race condition). Can also be |
|
|
1798 | useful simply to find out the new values. |
|
|
1799 | .IP "ev_statdata attr [read\-only]" 4 |
|
|
1800 | .IX Item "ev_statdata attr [read-only]" |
|
|
1801 | The most-recently detected attributes of the file. Although the type is of |
|
|
1802 | \&\f(CW\*(C`ev_statdata\*(C'\fR, this is usually the (or one of the) \f(CW\*(C`struct stat\*(C'\fR types |
|
|
1803 | suitable for your system. If the \f(CW\*(C`st_nlink\*(C'\fR member is \f(CW0\fR, then there |
|
|
1804 | was some error while \f(CW\*(C`stat\*(C'\fRing the file. |
|
|
1805 | .IP "ev_statdata prev [read\-only]" 4 |
|
|
1806 | .IX Item "ev_statdata prev [read-only]" |
|
|
1807 | The previous attributes of the file. The callback gets invoked whenever |
|
|
1808 | \&\f(CW\*(C`prev\*(C'\fR != \f(CW\*(C`attr\*(C'\fR. |
|
|
1809 | .IP "ev_tstamp interval [read\-only]" 4 |
|
|
1810 | .IX Item "ev_tstamp interval [read-only]" |
|
|
1811 | The specified interval. |
|
|
1812 | .IP "const char *path [read\-only]" 4 |
|
|
1813 | .IX Item "const char *path [read-only]" |
|
|
1814 | The filesystem path that is being watched. |
|
|
1815 | .PP |
|
|
1816 | \fIExamples\fR |
|
|
1817 | .IX Subsection "Examples" |
|
|
1818 | .PP |
|
|
1819 | Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes. |
|
|
1820 | .PP |
|
|
1821 | .Vb 10 |
|
|
1822 | \& static void |
|
|
1823 | \& passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
|
|
1824 | \& { |
|
|
1825 | \& /* /etc/passwd changed in some way */ |
|
|
1826 | \& if (w\->attr.st_nlink) |
|
|
1827 | \& { |
|
|
1828 | \& printf ("passwd current size %ld\en", (long)w\->attr.st_size); |
|
|
1829 | \& printf ("passwd current atime %ld\en", (long)w\->attr.st_mtime); |
|
|
1830 | \& printf ("passwd current mtime %ld\en", (long)w\->attr.st_mtime); |
|
|
1831 | \& } |
|
|
1832 | \& else |
|
|
1833 | \& /* you shalt not abuse printf for puts */ |
|
|
1834 | \& puts ("wow, /etc/passwd is not there, expect problems. " |
|
|
1835 | \& "if this is windows, they already arrived\en"); |
|
|
1836 | \& } |
|
|
1837 | \& |
|
|
1838 | \& ... |
|
|
1839 | \& ev_stat passwd; |
|
|
1840 | \& |
|
|
1841 | \& ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.); |
|
|
1842 | \& ev_stat_start (loop, &passwd); |
|
|
1843 | .Ve |
|
|
1844 | .PP |
|
|
1845 | Example: Like above, but additionally use a one-second delay so we do not |
|
|
1846 | miss updates (however, frequent updates will delay processing, too, so |
|
|
1847 | one might do the work both on \f(CW\*(C`ev_stat\*(C'\fR callback invocation \fIand\fR on |
|
|
1848 | \&\f(CW\*(C`ev_timer\*(C'\fR callback invocation). |
|
|
1849 | .PP |
|
|
1850 | .Vb 2 |
|
|
1851 | \& static ev_stat passwd; |
|
|
1852 | \& static ev_timer timer; |
|
|
1853 | \& |
|
|
1854 | \& static void |
|
|
1855 | \& timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1856 | \& { |
|
|
1857 | \& ev_timer_stop (EV_A_ w); |
|
|
1858 | \& |
|
|
1859 | \& /* now it\*(Aqs one second after the most recent passwd change */ |
|
|
1860 | \& } |
|
|
1861 | \& |
|
|
1862 | \& static void |
|
|
1863 | \& stat_cb (EV_P_ ev_stat *w, int revents) |
|
|
1864 | \& { |
|
|
1865 | \& /* reset the one\-second timer */ |
|
|
1866 | \& ev_timer_again (EV_A_ &timer); |
|
|
1867 | \& } |
|
|
1868 | \& |
|
|
1869 | \& ... |
|
|
1870 | \& ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
|
|
1871 | \& ev_stat_start (loop, &passwd); |
|
|
1872 | \& ev_timer_init (&timer, timer_cb, 0., 1.01); |
|
|
1873 | .Ve |
864 | .ie n .Sh """ev_idle"" \- when you've got nothing better to do" |
1874 | .ie n .Sh """ev_idle"" \- when you've got nothing better to do..." |
865 | .el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do" |
1875 | .el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..." |
866 | .IX Subsection "ev_idle - when you've got nothing better to do" |
1876 | .IX Subsection "ev_idle - when you've got nothing better to do..." |
867 | Idle watchers trigger events when there are no other events are pending |
1877 | Idle watchers trigger events when no other events of the same or higher |
868 | (prepare, check and other idle watchers do not count). That is, as long |
1878 | priority are pending (prepare, check and other idle watchers do not |
869 | as your process is busy handling sockets or timeouts (or even signals, |
1879 | count). |
870 | imagine) it will not be triggered. But when your process is idle all idle |
1880 | .PP |
871 | watchers are being called again and again, once per event loop iteration \- |
1881 | That is, as long as your process is busy handling sockets or timeouts |
|
|
1882 | (or even signals, imagine) of the same or higher priority it will not be |
|
|
1883 | triggered. But when your process is idle (or only lower-priority watchers |
|
|
1884 | are pending), the idle watchers are being called once per event loop |
872 | until stopped, that is, or your process receives more events and becomes |
1885 | iteration \- until stopped, that is, or your process receives more events |
873 | busy. |
1886 | and becomes busy again with higher priority stuff. |
874 | .PP |
1887 | .PP |
875 | The most noteworthy effect is that as long as any idle watchers are |
1888 | The most noteworthy effect is that as long as any idle watchers are |
876 | active, the process will not block when waiting for new events. |
1889 | active, the process will not block when waiting for new events. |
877 | .PP |
1890 | .PP |
878 | Apart from keeping your process non-blocking (which is a useful |
1891 | Apart from keeping your process non-blocking (which is a useful |
879 | effect on its own sometimes), idle watchers are a good place to do |
1892 | effect on its own sometimes), idle watchers are a good place to do |
880 | \&\*(L"pseudo\-background processing\*(R", or delay processing stuff to after the |
1893 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
881 | event loop has handled all outstanding events. |
1894 | event loop has handled all outstanding events. |
|
|
1895 | .PP |
|
|
1896 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
1897 | .IX Subsection "Watcher-Specific Functions and Data Members" |
882 | .IP "ev_idle_init (ev_signal *, callback)" 4 |
1898 | .IP "ev_idle_init (ev_signal *, callback)" 4 |
883 | .IX Item "ev_idle_init (ev_signal *, callback)" |
1899 | .IX Item "ev_idle_init (ev_signal *, callback)" |
884 | Initialises and configures the idle watcher \- it has no parameters of any |
1900 | Initialises and configures the idle watcher \- it has no parameters of any |
885 | kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, |
1901 | kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, |
886 | believe me. |
1902 | believe me. |
|
|
1903 | .PP |
|
|
1904 | \fIExamples\fR |
|
|
1905 | .IX Subsection "Examples" |
|
|
1906 | .PP |
|
|
1907 | Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the |
|
|
1908 | callback, free it. Also, use no error checking, as usual. |
|
|
1909 | .PP |
|
|
1910 | .Vb 7 |
|
|
1911 | \& static void |
|
|
1912 | \& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
|
|
1913 | \& { |
|
|
1914 | \& free (w); |
|
|
1915 | \& // now do something you wanted to do when the program has |
|
|
1916 | \& // no longer anything immediate to do. |
|
|
1917 | \& } |
|
|
1918 | \& |
|
|
1919 | \& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
|
|
1920 | \& ev_idle_init (idle_watcher, idle_cb); |
|
|
1921 | \& ev_idle_start (loop, idle_cb); |
|
|
1922 | .Ve |
887 | .ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop" |
1923 | .ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!" |
888 | .el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop" |
1924 | .el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" |
889 | .IX Subsection "ev_prepare and ev_check - customise your event loop" |
1925 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
890 | Prepare and check watchers are usually (but not always) used in tandem: |
1926 | Prepare and check watchers are usually (but not always) used in tandem: |
891 | prepare watchers get invoked before the process blocks and check watchers |
1927 | prepare watchers get invoked before the process blocks and check watchers |
892 | afterwards. |
1928 | afterwards. |
893 | .PP |
1929 | .PP |
|
|
1930 | You \fImust not\fR call \f(CW\*(C`ev_loop\*(C'\fR or similar functions that enter |
|
|
1931 | the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR |
|
|
1932 | watchers. Other loops than the current one are fine, however. The |
|
|
1933 | rationale behind this is that you do not need to check for recursion in |
|
|
1934 | those watchers, i.e. the sequence will always be \f(CW\*(C`ev_prepare\*(C'\fR, blocking, |
|
|
1935 | \&\f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each kind they will always be |
|
|
1936 | called in pairs bracketing the blocking call. |
|
|
1937 | .PP |
894 | Their main purpose is to integrate other event mechanisms into libev. This |
1938 | Their main purpose is to integrate other event mechanisms into libev and |
895 | could be used, for example, to track variable changes, implement your own |
1939 | their use is somewhat advanced. This could be used, for example, to track |
896 | watchers, integrate net-snmp or a coroutine library and lots more. |
1940 | variable changes, implement your own watchers, integrate net-snmp or a |
|
|
1941 | coroutine library and lots more. They are also occasionally useful if |
|
|
1942 | you cache some data and want to flush it before blocking (for example, |
|
|
1943 | in X programs you might want to do an \f(CW\*(C`XFlush ()\*(C'\fR in an \f(CW\*(C`ev_prepare\*(C'\fR |
|
|
1944 | watcher). |
897 | .PP |
1945 | .PP |
898 | This is done by examining in each prepare call which file descriptors need |
1946 | This is done by examining in each prepare call which file descriptors need |
899 | to be watched by the other library, registering \f(CW\*(C`ev_io\*(C'\fR watchers for |
1947 | to be watched by the other library, registering \f(CW\*(C`ev_io\*(C'\fR watchers for |
900 | them and starting an \f(CW\*(C`ev_timer\*(C'\fR watcher for any timeouts (many libraries |
1948 | them and starting an \f(CW\*(C`ev_timer\*(C'\fR watcher for any timeouts (many libraries |
901 | provide just this functionality). Then, in the check watcher you check for |
1949 | provide just this functionality). Then, in the check watcher you check for |
… | |
… | |
910 | are ready to run (it's actually more complicated: it only runs coroutines |
1958 | are ready to run (it's actually more complicated: it only runs coroutines |
911 | with priority higher than or equal to the event loop and one coroutine |
1959 | with priority higher than or equal to the event loop and one coroutine |
912 | of lower priority, but only once, using idle watchers to keep the event |
1960 | of lower priority, but only once, using idle watchers to keep the event |
913 | loop from blocking if lower-priority coroutines are active, thus mapping |
1961 | loop from blocking if lower-priority coroutines are active, thus mapping |
914 | low-priority coroutines to idle/background tasks). |
1962 | low-priority coroutines to idle/background tasks). |
|
|
1963 | .PP |
|
|
1964 | It is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR) |
|
|
1965 | priority, to ensure that they are being run before any other watchers |
|
|
1966 | after the poll. Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers, |
|
|
1967 | too) should not activate (\*(L"feed\*(R") events into libev. While libev fully |
|
|
1968 | supports this, they will be called before other \f(CW\*(C`ev_check\*(C'\fR watchers |
|
|
1969 | did their job. As \f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other |
|
|
1970 | (non-libev) event loops those other event loops might be in an unusable |
|
|
1971 | state until their \f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to |
|
|
1972 | coexist peacefully with others). |
|
|
1973 | .PP |
|
|
1974 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
1975 | .IX Subsection "Watcher-Specific Functions and Data Members" |
915 | .IP "ev_prepare_init (ev_prepare *, callback)" 4 |
1976 | .IP "ev_prepare_init (ev_prepare *, callback)" 4 |
916 | .IX Item "ev_prepare_init (ev_prepare *, callback)" |
1977 | .IX Item "ev_prepare_init (ev_prepare *, callback)" |
917 | .PD 0 |
1978 | .PD 0 |
918 | .IP "ev_check_init (ev_check *, callback)" 4 |
1979 | .IP "ev_check_init (ev_check *, callback)" 4 |
919 | .IX Item "ev_check_init (ev_check *, callback)" |
1980 | .IX Item "ev_check_init (ev_check *, callback)" |
920 | .PD |
1981 | .PD |
921 | Initialises and configures the prepare or check watcher \- they have no |
1982 | Initialises and configures the prepare or check watcher \- they have no |
922 | parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR |
1983 | parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR |
923 | macros, but using them is utterly, utterly and completely pointless. |
1984 | macros, but using them is utterly, utterly and completely pointless. |
|
|
1985 | .PP |
|
|
1986 | \fIExamples\fR |
|
|
1987 | .IX Subsection "Examples" |
|
|
1988 | .PP |
|
|
1989 | There are a number of principal ways to embed other event loops or modules |
|
|
1990 | into libev. Here are some ideas on how to include libadns into libev |
|
|
1991 | (there is a Perl module named \f(CW\*(C`EV::ADNS\*(C'\fR that does this, which you could |
|
|
1992 | use for an actually working example. Another Perl module named \f(CW\*(C`EV::Glib\*(C'\fR |
|
|
1993 | embeds a Glib main context into libev, and finally, \f(CW\*(C`Glib::EV\*(C'\fR embeds \s-1EV\s0 |
|
|
1994 | into the Glib event loop). |
|
|
1995 | .PP |
|
|
1996 | Method 1: Add \s-1IO\s0 watchers and a timeout watcher in a prepare handler, |
|
|
1997 | and in a check watcher, destroy them and call into libadns. What follows |
|
|
1998 | is pseudo-code only of course. This requires you to either use a low |
|
|
1999 | priority for the check watcher or use \f(CW\*(C`ev_clear_pending\*(C'\fR explicitly, as |
|
|
2000 | the callbacks for the IO/timeout watchers might not have been called yet. |
|
|
2001 | .PP |
|
|
2002 | .Vb 2 |
|
|
2003 | \& static ev_io iow [nfd]; |
|
|
2004 | \& static ev_timer tw; |
|
|
2005 | \& |
|
|
2006 | \& static void |
|
|
2007 | \& io_cb (ev_loop *loop, ev_io *w, int revents) |
|
|
2008 | \& { |
|
|
2009 | \& } |
|
|
2010 | \& |
|
|
2011 | \& // create io watchers for each fd and a timer before blocking |
|
|
2012 | \& static void |
|
|
2013 | \& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
|
|
2014 | \& { |
|
|
2015 | \& int timeout = 3600000; |
|
|
2016 | \& struct pollfd fds [nfd]; |
|
|
2017 | \& // actual code will need to loop here and realloc etc. |
|
|
2018 | \& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
|
|
2019 | \& |
|
|
2020 | \& /* the callback is illegal, but won\*(Aqt be called as we stop during check */ |
|
|
2021 | \& ev_timer_init (&tw, 0, timeout * 1e\-3); |
|
|
2022 | \& ev_timer_start (loop, &tw); |
|
|
2023 | \& |
|
|
2024 | \& // create one ev_io per pollfd |
|
|
2025 | \& for (int i = 0; i < nfd; ++i) |
|
|
2026 | \& { |
|
|
2027 | \& ev_io_init (iow + i, io_cb, fds [i].fd, |
|
|
2028 | \& ((fds [i].events & POLLIN ? EV_READ : 0) |
|
|
2029 | \& | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
|
|
2030 | \& |
|
|
2031 | \& fds [i].revents = 0; |
|
|
2032 | \& ev_io_start (loop, iow + i); |
|
|
2033 | \& } |
|
|
2034 | \& } |
|
|
2035 | \& |
|
|
2036 | \& // stop all watchers after blocking |
|
|
2037 | \& static void |
|
|
2038 | \& adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
|
|
2039 | \& { |
|
|
2040 | \& ev_timer_stop (loop, &tw); |
|
|
2041 | \& |
|
|
2042 | \& for (int i = 0; i < nfd; ++i) |
|
|
2043 | \& { |
|
|
2044 | \& // set the relevant poll flags |
|
|
2045 | \& // could also call adns_processreadable etc. here |
|
|
2046 | \& struct pollfd *fd = fds + i; |
|
|
2047 | \& int revents = ev_clear_pending (iow + i); |
|
|
2048 | \& if (revents & EV_READ ) fd\->revents |= fd\->events & POLLIN; |
|
|
2049 | \& if (revents & EV_WRITE) fd\->revents |= fd\->events & POLLOUT; |
|
|
2050 | \& |
|
|
2051 | \& // now stop the watcher |
|
|
2052 | \& ev_io_stop (loop, iow + i); |
|
|
2053 | \& } |
|
|
2054 | \& |
|
|
2055 | \& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
2056 | \& } |
|
|
2057 | .Ve |
|
|
2058 | .PP |
|
|
2059 | Method 2: This would be just like method 1, but you run \f(CW\*(C`adns_afterpoll\*(C'\fR |
|
|
2060 | in the prepare watcher and would dispose of the check watcher. |
|
|
2061 | .PP |
|
|
2062 | Method 3: If the module to be embedded supports explicit event |
|
|
2063 | notification (adns does), you can also make use of the actual watcher |
|
|
2064 | callbacks, and only destroy/create the watchers in the prepare watcher. |
|
|
2065 | .PP |
|
|
2066 | .Vb 5 |
|
|
2067 | \& static void |
|
|
2068 | \& timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
2069 | \& { |
|
|
2070 | \& adns_state ads = (adns_state)w\->data; |
|
|
2071 | \& update_now (EV_A); |
|
|
2072 | \& |
|
|
2073 | \& adns_processtimeouts (ads, &tv_now); |
|
|
2074 | \& } |
|
|
2075 | \& |
|
|
2076 | \& static void |
|
|
2077 | \& io_cb (EV_P_ ev_io *w, int revents) |
|
|
2078 | \& { |
|
|
2079 | \& adns_state ads = (adns_state)w\->data; |
|
|
2080 | \& update_now (EV_A); |
|
|
2081 | \& |
|
|
2082 | \& if (revents & EV_READ ) adns_processreadable (ads, w\->fd, &tv_now); |
|
|
2083 | \& if (revents & EV_WRITE) adns_processwriteable (ads, w\->fd, &tv_now); |
|
|
2084 | \& } |
|
|
2085 | \& |
|
|
2086 | \& // do not ever call adns_afterpoll |
|
|
2087 | .Ve |
|
|
2088 | .PP |
|
|
2089 | Method 4: Do not use a prepare or check watcher because the module you |
|
|
2090 | want to embed is too inflexible to support it. Instead, youc na override |
|
|
2091 | their poll function. The drawback with this solution is that the main |
|
|
2092 | loop is now no longer controllable by \s-1EV\s0. The \f(CW\*(C`Glib::EV\*(C'\fR module does |
|
|
2093 | this. |
|
|
2094 | .PP |
|
|
2095 | .Vb 4 |
|
|
2096 | \& static gint |
|
|
2097 | \& event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
|
|
2098 | \& { |
|
|
2099 | \& int got_events = 0; |
|
|
2100 | \& |
|
|
2101 | \& for (n = 0; n < nfds; ++n) |
|
|
2102 | \& // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
|
|
2103 | \& |
|
|
2104 | \& if (timeout >= 0) |
|
|
2105 | \& // create/start timer |
|
|
2106 | \& |
|
|
2107 | \& // poll |
|
|
2108 | \& ev_loop (EV_A_ 0); |
|
|
2109 | \& |
|
|
2110 | \& // stop timer again |
|
|
2111 | \& if (timeout >= 0) |
|
|
2112 | \& ev_timer_stop (EV_A_ &to); |
|
|
2113 | \& |
|
|
2114 | \& // stop io watchers again \- their callbacks should have set |
|
|
2115 | \& for (n = 0; n < nfds; ++n) |
|
|
2116 | \& ev_io_stop (EV_A_ iow [n]); |
|
|
2117 | \& |
|
|
2118 | \& return got_events; |
|
|
2119 | \& } |
|
|
2120 | .Ve |
|
|
2121 | .ie n .Sh """ev_embed"" \- when one backend isn't enough..." |
|
|
2122 | .el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." |
|
|
2123 | .IX Subsection "ev_embed - when one backend isn't enough..." |
|
|
2124 | This is a rather advanced watcher type that lets you embed one event loop |
|
|
2125 | into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded |
|
|
2126 | loop, other types of watchers might be handled in a delayed or incorrect |
|
|
2127 | fashion and must not be used). |
|
|
2128 | .PP |
|
|
2129 | There are primarily two reasons you would want that: work around bugs and |
|
|
2130 | prioritise I/O. |
|
|
2131 | .PP |
|
|
2132 | As an example for a bug workaround, the kqueue backend might only support |
|
|
2133 | sockets on some platform, so it is unusable as generic backend, but you |
|
|
2134 | still want to make use of it because you have many sockets and it scales |
|
|
2135 | so nicely. In this case, you would create a kqueue-based loop and embed it |
|
|
2136 | into your default loop (which might use e.g. poll). Overall operation will |
|
|
2137 | be a bit slower because first libev has to poll and then call kevent, but |
|
|
2138 | at least you can use both at what they are best. |
|
|
2139 | .PP |
|
|
2140 | As for prioritising I/O: rarely you have the case where some fds have |
|
|
2141 | to be watched and handled very quickly (with low latency), and even |
|
|
2142 | priorities and idle watchers might have too much overhead. In this case |
|
|
2143 | you would put all the high priority stuff in one loop and all the rest in |
|
|
2144 | a second one, and embed the second one in the first. |
|
|
2145 | .PP |
|
|
2146 | As long as the watcher is active, the callback will be invoked every time |
|
|
2147 | there might be events pending in the embedded loop. The callback must then |
|
|
2148 | call \f(CW\*(C`ev_embed_sweep (mainloop, watcher)\*(C'\fR to make a single sweep and invoke |
|
|
2149 | their callbacks (you could also start an idle watcher to give the embedded |
|
|
2150 | loop strictly lower priority for example). You can also set the callback |
|
|
2151 | to \f(CW0\fR, in which case the embed watcher will automatically execute the |
|
|
2152 | embedded loop sweep. |
|
|
2153 | .PP |
|
|
2154 | As long as the watcher is started it will automatically handle events. The |
|
|
2155 | callback will be invoked whenever some events have been handled. You can |
|
|
2156 | set the callback to \f(CW0\fR to avoid having to specify one if you are not |
|
|
2157 | interested in that. |
|
|
2158 | .PP |
|
|
2159 | Also, there have not currently been made special provisions for forking: |
|
|
2160 | when you fork, you not only have to call \f(CW\*(C`ev_loop_fork\*(C'\fR on both loops, |
|
|
2161 | but you will also have to stop and restart any \f(CW\*(C`ev_embed\*(C'\fR watchers |
|
|
2162 | yourself. |
|
|
2163 | .PP |
|
|
2164 | Unfortunately, not all backends are embeddable, only the ones returned by |
|
|
2165 | \&\f(CW\*(C`ev_embeddable_backends\*(C'\fR are, which, unfortunately, does not include any |
|
|
2166 | portable one. |
|
|
2167 | .PP |
|
|
2168 | So when you want to use this feature you will always have to be prepared |
|
|
2169 | that you cannot get an embeddable loop. The recommended way to get around |
|
|
2170 | this is to have a separate variables for your embeddable loop, try to |
|
|
2171 | create it, and if that fails, use the normal loop for everything. |
|
|
2172 | .PP |
|
|
2173 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
2174 | .IX Subsection "Watcher-Specific Functions and Data Members" |
|
|
2175 | .IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
|
|
2176 | .IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" |
|
|
2177 | .PD 0 |
|
|
2178 | .IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
|
|
2179 | .IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" |
|
|
2180 | .PD |
|
|
2181 | Configures the watcher to embed the given loop, which must be |
|
|
2182 | embeddable. If the callback is \f(CW0\fR, then \f(CW\*(C`ev_embed_sweep\*(C'\fR will be |
|
|
2183 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
2184 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
2185 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
2186 | .IP "ev_embed_sweep (loop, ev_embed *)" 4 |
|
|
2187 | .IX Item "ev_embed_sweep (loop, ev_embed *)" |
|
|
2188 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
2189 | similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most |
|
|
2190 | apropriate way for embedded loops. |
|
|
2191 | .IP "struct ev_loop *other [read\-only]" 4 |
|
|
2192 | .IX Item "struct ev_loop *other [read-only]" |
|
|
2193 | The embedded event loop. |
|
|
2194 | .PP |
|
|
2195 | \fIExamples\fR |
|
|
2196 | .IX Subsection "Examples" |
|
|
2197 | .PP |
|
|
2198 | Example: Try to get an embeddable event loop and embed it into the default |
|
|
2199 | event loop. If that is not possible, use the default loop. The default |
|
|
2200 | loop is stored in \f(CW\*(C`loop_hi\*(C'\fR, while the mebeddable loop is stored in |
|
|
2201 | \&\f(CW\*(C`loop_lo\*(C'\fR (which is \f(CW\*(C`loop_hi\*(C'\fR in the acse no embeddable loop can be |
|
|
2202 | used). |
|
|
2203 | .PP |
|
|
2204 | .Vb 3 |
|
|
2205 | \& struct ev_loop *loop_hi = ev_default_init (0); |
|
|
2206 | \& struct ev_loop *loop_lo = 0; |
|
|
2207 | \& struct ev_embed embed; |
|
|
2208 | \& |
|
|
2209 | \& // see if there is a chance of getting one that works |
|
|
2210 | \& // (remember that a flags value of 0 means autodetection) |
|
|
2211 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
|
|
2212 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
|
|
2213 | \& : 0; |
|
|
2214 | \& |
|
|
2215 | \& // if we got one, then embed it, otherwise default to loop_hi |
|
|
2216 | \& if (loop_lo) |
|
|
2217 | \& { |
|
|
2218 | \& ev_embed_init (&embed, 0, loop_lo); |
|
|
2219 | \& ev_embed_start (loop_hi, &embed); |
|
|
2220 | \& } |
|
|
2221 | \& else |
|
|
2222 | \& loop_lo = loop_hi; |
|
|
2223 | .Ve |
|
|
2224 | .PP |
|
|
2225 | Example: Check if kqueue is available but not recommended and create |
|
|
2226 | a kqueue backend for use with sockets (which usually work with any |
|
|
2227 | kqueue implementation). Store the kqueue/socket\-only event loop in |
|
|
2228 | \&\f(CW\*(C`loop_socket\*(C'\fR. (One might optionally use \f(CW\*(C`EVFLAG_NOENV\*(C'\fR, too). |
|
|
2229 | .PP |
|
|
2230 | .Vb 3 |
|
|
2231 | \& struct ev_loop *loop = ev_default_init (0); |
|
|
2232 | \& struct ev_loop *loop_socket = 0; |
|
|
2233 | \& struct ev_embed embed; |
|
|
2234 | \& |
|
|
2235 | \& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
|
|
2236 | \& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
|
|
2237 | \& { |
|
|
2238 | \& ev_embed_init (&embed, 0, loop_socket); |
|
|
2239 | \& ev_embed_start (loop, &embed); |
|
|
2240 | \& } |
|
|
2241 | \& |
|
|
2242 | \& if (!loop_socket) |
|
|
2243 | \& loop_socket = loop; |
|
|
2244 | \& |
|
|
2245 | \& // now use loop_socket for all sockets, and loop for everything else |
|
|
2246 | .Ve |
|
|
2247 | .ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork" |
|
|
2248 | .el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
|
|
2249 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
|
|
2250 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
|
|
2251 | whoever is a good citizen cared to tell libev about it by calling |
|
|
2252 | \&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the |
|
|
2253 | event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, |
|
|
2254 | and only in the child after the fork. If whoever good citizen calling |
|
|
2255 | \&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork |
|
|
2256 | handlers will be invoked, too, of course. |
|
|
2257 | .PP |
|
|
2258 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
2259 | .IX Subsection "Watcher-Specific Functions and Data Members" |
|
|
2260 | .IP "ev_fork_init (ev_signal *, callback)" 4 |
|
|
2261 | .IX Item "ev_fork_init (ev_signal *, callback)" |
|
|
2262 | Initialises and configures the fork watcher \- it has no parameters of any |
|
|
2263 | kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, |
|
|
2264 | believe me. |
|
|
2265 | .ie n .Sh """ev_async"" \- how to wake up another event loop" |
|
|
2266 | .el .Sh "\f(CWev_async\fP \- how to wake up another event loop" |
|
|
2267 | .IX Subsection "ev_async - how to wake up another event loop" |
|
|
2268 | In general, you cannot use an \f(CW\*(C`ev_loop\*(C'\fR from multiple threads or other |
|
|
2269 | asynchronous sources such as signal handlers (as opposed to multiple event |
|
|
2270 | loops \- those are of course safe to use in different threads). |
|
|
2271 | .PP |
|
|
2272 | Sometimes, however, you need to wake up another event loop you do not |
|
|
2273 | control, for example because it belongs to another thread. This is what |
|
|
2274 | \&\f(CW\*(C`ev_async\*(C'\fR watchers do: as long as the \f(CW\*(C`ev_async\*(C'\fR watcher is active, you |
|
|
2275 | can signal it by calling \f(CW\*(C`ev_async_send\*(C'\fR, which is thread\- and signal |
|
|
2276 | safe. |
|
|
2277 | .PP |
|
|
2278 | This functionality is very similar to \f(CW\*(C`ev_signal\*(C'\fR watchers, as signals, |
|
|
2279 | too, are asynchronous in nature, and signals, too, will be compressed |
|
|
2280 | (i.e. the number of callback invocations may be less than the number of |
|
|
2281 | \&\f(CW\*(C`ev_async_sent\*(C'\fR calls). |
|
|
2282 | .PP |
|
|
2283 | Unlike \f(CW\*(C`ev_signal\*(C'\fR watchers, \f(CW\*(C`ev_async\*(C'\fR works with any event loop, not |
|
|
2284 | just the default loop. |
|
|
2285 | .PP |
|
|
2286 | \fIQueueing\fR |
|
|
2287 | .IX Subsection "Queueing" |
|
|
2288 | .PP |
|
|
2289 | \&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason |
|
|
2290 | is that the author does not know of a simple (or any) algorithm for a |
|
|
2291 | multiple-writer-single-reader queue that works in all cases and doesn't |
|
|
2292 | need elaborate support such as pthreads. |
|
|
2293 | .PP |
|
|
2294 | That means that if you want to queue data, you have to provide your own |
|
|
2295 | queue. But at least I can tell you would implement locking around your |
|
|
2296 | queue: |
|
|
2297 | .IP "queueing from a signal handler context" 4 |
|
|
2298 | .IX Item "queueing from a signal handler context" |
|
|
2299 | To implement race-free queueing, you simply add to the queue in the signal |
|
|
2300 | handler but you block the signal handler in the watcher callback. Here is an example that does that for |
|
|
2301 | some fictitiuous \s-1SIGUSR1\s0 handler: |
|
|
2302 | .Sp |
|
|
2303 | .Vb 1 |
|
|
2304 | \& static ev_async mysig; |
|
|
2305 | \& |
|
|
2306 | \& static void |
|
|
2307 | \& sigusr1_handler (void) |
|
|
2308 | \& { |
|
|
2309 | \& sometype data; |
|
|
2310 | \& |
|
|
2311 | \& // no locking etc. |
|
|
2312 | \& queue_put (data); |
|
|
2313 | \& ev_async_send (EV_DEFAULT_ &mysig); |
|
|
2314 | \& } |
|
|
2315 | \& |
|
|
2316 | \& static void |
|
|
2317 | \& mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2318 | \& { |
|
|
2319 | \& sometype data; |
|
|
2320 | \& sigset_t block, prev; |
|
|
2321 | \& |
|
|
2322 | \& sigemptyset (&block); |
|
|
2323 | \& sigaddset (&block, SIGUSR1); |
|
|
2324 | \& sigprocmask (SIG_BLOCK, &block, &prev); |
|
|
2325 | \& |
|
|
2326 | \& while (queue_get (&data)) |
|
|
2327 | \& process (data); |
|
|
2328 | \& |
|
|
2329 | \& if (sigismember (&prev, SIGUSR1) |
|
|
2330 | \& sigprocmask (SIG_UNBLOCK, &block, 0); |
|
|
2331 | \& } |
|
|
2332 | .Ve |
|
|
2333 | .Sp |
|
|
2334 | (Note: pthreads in theory requires you to use \f(CW\*(C`pthread_setmask\*(C'\fR |
|
|
2335 | instead of \f(CW\*(C`sigprocmask\*(C'\fR when you use threads, but libev doesn't do it |
|
|
2336 | either...). |
|
|
2337 | .IP "queueing from a thread context" 4 |
|
|
2338 | .IX Item "queueing from a thread context" |
|
|
2339 | The strategy for threads is different, as you cannot (easily) block |
|
|
2340 | threads but you can easily preempt them, so to queue safely you need to |
|
|
2341 | employ a traditional mutex lock, such as in this pthread example: |
|
|
2342 | .Sp |
|
|
2343 | .Vb 2 |
|
|
2344 | \& static ev_async mysig; |
|
|
2345 | \& static pthread_mutex_t mymutex = PTHREAD_MUTEX_INITIALIZER; |
|
|
2346 | \& |
|
|
2347 | \& static void |
|
|
2348 | \& otherthread (void) |
|
|
2349 | \& { |
|
|
2350 | \& // only need to lock the actual queueing operation |
|
|
2351 | \& pthread_mutex_lock (&mymutex); |
|
|
2352 | \& queue_put (data); |
|
|
2353 | \& pthread_mutex_unlock (&mymutex); |
|
|
2354 | \& |
|
|
2355 | \& ev_async_send (EV_DEFAULT_ &mysig); |
|
|
2356 | \& } |
|
|
2357 | \& |
|
|
2358 | \& static void |
|
|
2359 | \& mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2360 | \& { |
|
|
2361 | \& pthread_mutex_lock (&mymutex); |
|
|
2362 | \& |
|
|
2363 | \& while (queue_get (&data)) |
|
|
2364 | \& process (data); |
|
|
2365 | \& |
|
|
2366 | \& pthread_mutex_unlock (&mymutex); |
|
|
2367 | \& } |
|
|
2368 | .Ve |
|
|
2369 | .PP |
|
|
2370 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
2371 | .IX Subsection "Watcher-Specific Functions and Data Members" |
|
|
2372 | .IP "ev_async_init (ev_async *, callback)" 4 |
|
|
2373 | .IX Item "ev_async_init (ev_async *, callback)" |
|
|
2374 | Initialises and configures the async watcher \- it has no parameters of any |
|
|
2375 | kind. There is a \f(CW\*(C`ev_asynd_set\*(C'\fR macro, but using it is utterly pointless, |
|
|
2376 | believe me. |
|
|
2377 | .IP "ev_async_send (loop, ev_async *)" 4 |
|
|
2378 | .IX Item "ev_async_send (loop, ev_async *)" |
|
|
2379 | Sends/signals/activates the given \f(CW\*(C`ev_async\*(C'\fR watcher, that is, feeds |
|
|
2380 | an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop. Unlike |
|
|
2381 | \&\f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do in other threads, signal or |
|
|
2382 | similar contexts (see the dicusssion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the embedding |
|
|
2383 | section below on what exactly this means). |
|
|
2384 | .Sp |
|
|
2385 | This call incurs the overhead of a syscall only once per loop iteration, |
|
|
2386 | so while the overhead might be noticable, it doesn't apply to repeated |
|
|
2387 | calls to \f(CW\*(C`ev_async_send\*(C'\fR. |
924 | .SH "OTHER FUNCTIONS" |
2388 | .SH "OTHER FUNCTIONS" |
925 | .IX Header "OTHER FUNCTIONS" |
2389 | .IX Header "OTHER FUNCTIONS" |
926 | There are some other functions of possible interest. Described. Here. Now. |
2390 | There are some other functions of possible interest. Described. Here. Now. |
927 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
2391 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
928 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
2392 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
… | |
… | |
952 | \& if (revents & EV_TIMEOUT) |
2416 | \& if (revents & EV_TIMEOUT) |
953 | \& /* doh, nothing entered */; |
2417 | \& /* doh, nothing entered */; |
954 | \& else if (revents & EV_READ) |
2418 | \& else if (revents & EV_READ) |
955 | \& /* stdin might have data for us, joy! */; |
2419 | \& /* stdin might have data for us, joy! */; |
956 | \& } |
2420 | \& } |
957 | .Ve |
2421 | \& |
958 | .Sp |
|
|
959 | .Vb 1 |
|
|
960 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
2422 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
961 | .Ve |
2423 | .Ve |
962 | .IP "ev_feed_event (loop, watcher, int events)" 4 |
2424 | .IP "ev_feed_event (ev_loop *, watcher *, int revents)" 4 |
963 | .IX Item "ev_feed_event (loop, watcher, int events)" |
2425 | .IX Item "ev_feed_event (ev_loop *, watcher *, int revents)" |
964 | Feeds the given event set into the event loop, as if the specified event |
2426 | Feeds the given event set into the event loop, as if the specified event |
965 | had happened for the specified watcher (which must be a pointer to an |
2427 | had happened for the specified watcher (which must be a pointer to an |
966 | initialised but not necessarily started event watcher). |
2428 | initialised but not necessarily started event watcher). |
967 | .IP "ev_feed_fd_event (loop, int fd, int revents)" 4 |
2429 | .IP "ev_feed_fd_event (ev_loop *, int fd, int revents)" 4 |
968 | .IX Item "ev_feed_fd_event (loop, int fd, int revents)" |
2430 | .IX Item "ev_feed_fd_event (ev_loop *, int fd, int revents)" |
969 | Feed an event on the given fd, as if a file descriptor backend detected |
2431 | Feed an event on the given fd, as if a file descriptor backend detected |
970 | the given events it. |
2432 | the given events it. |
971 | .IP "ev_feed_signal_event (loop, int signum)" 4 |
2433 | .IP "ev_feed_signal_event (ev_loop *loop, int signum)" 4 |
972 | .IX Item "ev_feed_signal_event (loop, int signum)" |
2434 | .IX Item "ev_feed_signal_event (ev_loop *loop, int signum)" |
973 | Feed an event as if the given signal occured (loop must be the default loop!). |
2435 | Feed an event as if the given signal occured (\f(CW\*(C`loop\*(C'\fR must be the default |
|
|
2436 | loop!). |
974 | .SH "LIBEVENT EMULATION" |
2437 | .SH "LIBEVENT EMULATION" |
975 | .IX Header "LIBEVENT EMULATION" |
2438 | .IX Header "LIBEVENT EMULATION" |
976 | Libev offers a compatibility emulation layer for libevent. It cannot |
2439 | Libev offers a compatibility emulation layer for libevent. It cannot |
977 | emulate the internals of libevent, so here are some usage hints: |
2440 | emulate the internals of libevent, so here are some usage hints: |
|
|
2441 | .IP "\(bu" 4 |
978 | .IP "* Use it by including <event.h>, as usual." 4 |
2442 | Use it by including <event.h>, as usual. |
979 | .IX Item "Use it by including <event.h>, as usual." |
2443 | .IP "\(bu" 4 |
980 | .PD 0 |
2444 | The following members are fully supported: ev_base, ev_callback, |
981 | .IP "* The following members are fully supported: ev_base, ev_callback, ev_arg, ev_fd, ev_res, ev_events." 4 |
2445 | ev_arg, ev_fd, ev_res, ev_events. |
982 | .IX Item "The following members are fully supported: ev_base, ev_callback, ev_arg, ev_fd, ev_res, ev_events." |
2446 | .IP "\(bu" 4 |
983 | .IP "* Avoid using ev_flags and the EVLIST_*\-macros, while it is maintained by libev, it does not work exactly the same way as in libevent (consider it a private \s-1API\s0)." 4 |
2447 | Avoid using ev_flags and the EVLIST_*\-macros, while it is |
984 | .IX Item "Avoid using ev_flags and the EVLIST_*-macros, while it is maintained by libev, it does not work exactly the same way as in libevent (consider it a private API)." |
2448 | maintained by libev, it does not work exactly the same way as in libevent (consider |
985 | .IP "* Priorities are not currently supported. Initialising priorities will fail and all watchers will have the same priority, even though there is an ev_pri field." 4 |
2449 | it a private \s-1API\s0). |
986 | .IX Item "Priorities are not currently supported. Initialising priorities will fail and all watchers will have the same priority, even though there is an ev_pri field." |
2450 | .IP "\(bu" 4 |
|
|
2451 | Priorities are not currently supported. Initialising priorities |
|
|
2452 | will fail and all watchers will have the same priority, even though there |
|
|
2453 | is an ev_pri field. |
|
|
2454 | .IP "\(bu" 4 |
987 | .IP "* Other members are not supported." 4 |
2455 | Other members are not supported. |
988 | .IX Item "Other members are not supported." |
2456 | .IP "\(bu" 4 |
989 | .IP "* The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need to use the libev header file and library." 4 |
2457 | The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need |
990 | .IX Item "The libev emulation is not ABI compatible to libevent, you need to use the libev header file and library." |
2458 | to use the libev header file and library. |
991 | .PD |
|
|
992 | .SH "\*(C+ SUPPORT" |
2459 | .SH "\*(C+ SUPPORT" |
993 | .IX Header " SUPPORT" |
2460 | .IX Header " SUPPORT" |
994 | \&\s-1TBD\s0. |
2461 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
|
|
2462 | you to use some convinience methods to start/stop watchers and also change |
|
|
2463 | the callback model to a model using method callbacks on objects. |
|
|
2464 | .PP |
|
|
2465 | To use it, |
|
|
2466 | .PP |
|
|
2467 | .Vb 1 |
|
|
2468 | \& #include <ev++.h> |
|
|
2469 | .Ve |
|
|
2470 | .PP |
|
|
2471 | This automatically includes \fIev.h\fR and puts all of its definitions (many |
|
|
2472 | of them macros) into the global namespace. All \*(C+ specific things are |
|
|
2473 | put into the \f(CW\*(C`ev\*(C'\fR namespace. It should support all the same embedding |
|
|
2474 | options as \fIev.h\fR, most notably \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. |
|
|
2475 | .PP |
|
|
2476 | Care has been taken to keep the overhead low. The only data member the \*(C+ |
|
|
2477 | classes add (compared to plain C\-style watchers) is the event loop pointer |
|
|
2478 | that the watcher is associated with (or no additional members at all if |
|
|
2479 | you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev). |
|
|
2480 | .PP |
|
|
2481 | Currently, functions, and static and non-static member functions can be |
|
|
2482 | used as callbacks. Other types should be easy to add as long as they only |
|
|
2483 | need one additional pointer for context. If you need support for other |
|
|
2484 | types of functors please contact the author (preferably after implementing |
|
|
2485 | it). |
|
|
2486 | .PP |
|
|
2487 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
|
|
2488 | .ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4 |
|
|
2489 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
|
|
2490 | .IX Item "ev::READ, ev::WRITE etc." |
|
|
2491 | These are just enum values with the same values as the \f(CW\*(C`EV_READ\*(C'\fR etc. |
|
|
2492 | macros from \fIev.h\fR. |
|
|
2493 | .ie n .IP """ev::tstamp""\fR, \f(CW""ev::now""" 4 |
|
|
2494 | .el .IP "\f(CWev::tstamp\fR, \f(CWev::now\fR" 4 |
|
|
2495 | .IX Item "ev::tstamp, ev::now" |
|
|
2496 | Aliases to the same types/functions as with the \f(CW\*(C`ev_\*(C'\fR prefix. |
|
|
2497 | .ie n .IP """ev::io""\fR, \f(CW""ev::timer""\fR, \f(CW""ev::periodic""\fR, \f(CW""ev::idle""\fR, \f(CW""ev::sig"" etc." 4 |
|
|
2498 | .el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4 |
|
|
2499 | .IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc." |
|
|
2500 | For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of |
|
|
2501 | the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR |
|
|
2502 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
|
|
2503 | defines by many implementations. |
|
|
2504 | .Sp |
|
|
2505 | All of those classes have these methods: |
|
|
2506 | .RS 4 |
|
|
2507 | .IP "ev::TYPE::TYPE ()" 4 |
|
|
2508 | .IX Item "ev::TYPE::TYPE ()" |
|
|
2509 | .PD 0 |
|
|
2510 | .IP "ev::TYPE::TYPE (struct ev_loop *)" 4 |
|
|
2511 | .IX Item "ev::TYPE::TYPE (struct ev_loop *)" |
|
|
2512 | .IP "ev::TYPE::~TYPE" 4 |
|
|
2513 | .IX Item "ev::TYPE::~TYPE" |
|
|
2514 | .PD |
|
|
2515 | The constructor (optionally) takes an event loop to associate the watcher |
|
|
2516 | with. If it is omitted, it will use \f(CW\*(C`EV_DEFAULT\*(C'\fR. |
|
|
2517 | .Sp |
|
|
2518 | The constructor calls \f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the |
|
|
2519 | \&\f(CW\*(C`set\*(C'\fR method before starting it. |
|
|
2520 | .Sp |
|
|
2521 | It will not set a callback, however: You have to call the templated \f(CW\*(C`set\*(C'\fR |
|
|
2522 | method to set a callback before you can start the watcher. |
|
|
2523 | .Sp |
|
|
2524 | (The reason why you have to use a method is a limitation in \*(C+ which does |
|
|
2525 | not allow explicit template arguments for constructors). |
|
|
2526 | .Sp |
|
|
2527 | The destructor automatically stops the watcher if it is active. |
|
|
2528 | .IP "w\->set<class, &class::method> (object *)" 4 |
|
|
2529 | .IX Item "w->set<class, &class::method> (object *)" |
|
|
2530 | This method sets the callback method to call. The method has to have a |
|
|
2531 | signature of \f(CW\*(C`void (*)(ev_TYPE &, int)\*(C'\fR, it receives the watcher as |
|
|
2532 | first argument and the \f(CW\*(C`revents\*(C'\fR as second. The object must be given as |
|
|
2533 | parameter and is stored in the \f(CW\*(C`data\*(C'\fR member of the watcher. |
|
|
2534 | .Sp |
|
|
2535 | This method synthesizes efficient thunking code to call your method from |
|
|
2536 | the C callback that libev requires. If your compiler can inline your |
|
|
2537 | callback (i.e. it is visible to it at the place of the \f(CW\*(C`set\*(C'\fR call and |
|
|
2538 | your compiler is good :), then the method will be fully inlined into the |
|
|
2539 | thunking function, making it as fast as a direct C callback. |
|
|
2540 | .Sp |
|
|
2541 | Example: simple class declaration and watcher initialisation |
|
|
2542 | .Sp |
|
|
2543 | .Vb 4 |
|
|
2544 | \& struct myclass |
|
|
2545 | \& { |
|
|
2546 | \& void io_cb (ev::io &w, int revents) { } |
|
|
2547 | \& } |
|
|
2548 | \& |
|
|
2549 | \& myclass obj; |
|
|
2550 | \& ev::io iow; |
|
|
2551 | \& iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
2552 | .Ve |
|
|
2553 | .IP "w\->set<function> (void *data = 0)" 4 |
|
|
2554 | .IX Item "w->set<function> (void *data = 0)" |
|
|
2555 | Also sets a callback, but uses a static method or plain function as |
|
|
2556 | callback. The optional \f(CW\*(C`data\*(C'\fR argument will be stored in the watcher's |
|
|
2557 | \&\f(CW\*(C`data\*(C'\fR member and is free for you to use. |
|
|
2558 | .Sp |
|
|
2559 | The prototype of the \f(CW\*(C`function\*(C'\fR must be \f(CW\*(C`void (*)(ev::TYPE &w, int)\*(C'\fR. |
|
|
2560 | .Sp |
|
|
2561 | See the method\-\f(CW\*(C`set\*(C'\fR above for more details. |
|
|
2562 | .Sp |
|
|
2563 | Example: |
|
|
2564 | .Sp |
|
|
2565 | .Vb 2 |
|
|
2566 | \& static void io_cb (ev::io &w, int revents) { } |
|
|
2567 | \& iow.set <io_cb> (); |
|
|
2568 | .Ve |
|
|
2569 | .IP "w\->set (struct ev_loop *)" 4 |
|
|
2570 | .IX Item "w->set (struct ev_loop *)" |
|
|
2571 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
|
|
2572 | do this when the watcher is inactive (and not pending either). |
|
|
2573 | .IP "w\->set ([args])" 4 |
|
|
2574 | .IX Item "w->set ([args])" |
|
|
2575 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be |
|
|
2576 | called at least once. Unlike the C counterpart, an active watcher gets |
|
|
2577 | automatically stopped and restarted when reconfiguring it with this |
|
|
2578 | method. |
|
|
2579 | .IP "w\->start ()" 4 |
|
|
2580 | .IX Item "w->start ()" |
|
|
2581 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
|
|
2582 | constructor already stores the event loop. |
|
|
2583 | .IP "w\->stop ()" 4 |
|
|
2584 | .IX Item "w->stop ()" |
|
|
2585 | Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. |
|
|
2586 | .ie n .IP "w\->again () (""ev::timer""\fR, \f(CW""ev::periodic"" only)" 4 |
|
|
2587 | .el .IP "w\->again () (\f(CWev::timer\fR, \f(CWev::periodic\fR only)" 4 |
|
|
2588 | .IX Item "w->again () (ev::timer, ev::periodic only)" |
|
|
2589 | For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding |
|
|
2590 | \&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. |
|
|
2591 | .ie n .IP "w\->sweep () (""ev::embed"" only)" 4 |
|
|
2592 | .el .IP "w\->sweep () (\f(CWev::embed\fR only)" 4 |
|
|
2593 | .IX Item "w->sweep () (ev::embed only)" |
|
|
2594 | Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR. |
|
|
2595 | .ie n .IP "w\->update () (""ev::stat"" only)" 4 |
|
|
2596 | .el .IP "w\->update () (\f(CWev::stat\fR only)" 4 |
|
|
2597 | .IX Item "w->update () (ev::stat only)" |
|
|
2598 | Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR. |
|
|
2599 | .RE |
|
|
2600 | .RS 4 |
|
|
2601 | .RE |
|
|
2602 | .PP |
|
|
2603 | Example: Define a class with an \s-1IO\s0 and idle watcher, start one of them in |
|
|
2604 | the constructor. |
|
|
2605 | .PP |
|
|
2606 | .Vb 4 |
|
|
2607 | \& class myclass |
|
|
2608 | \& { |
|
|
2609 | \& ev::io io; void io_cb (ev::io &w, int revents); |
|
|
2610 | \& ev:idle idle void idle_cb (ev::idle &w, int revents); |
|
|
2611 | \& |
|
|
2612 | \& myclass (int fd) |
|
|
2613 | \& { |
|
|
2614 | \& io .set <myclass, &myclass::io_cb > (this); |
|
|
2615 | \& idle.set <myclass, &myclass::idle_cb> (this); |
|
|
2616 | \& |
|
|
2617 | \& io.start (fd, ev::READ); |
|
|
2618 | \& } |
|
|
2619 | \& }; |
|
|
2620 | .Ve |
|
|
2621 | .SH "OTHER LANGUAGE BINDINGS" |
|
|
2622 | .IX Header "OTHER LANGUAGE BINDINGS" |
|
|
2623 | Libev does not offer other language bindings itself, but bindings for a |
|
|
2624 | numbe rof languages exist in the form of third-party packages. If you know |
|
|
2625 | any interesting language binding in addition to the ones listed here, drop |
|
|
2626 | me a note. |
|
|
2627 | .IP "Perl" 4 |
|
|
2628 | .IX Item "Perl" |
|
|
2629 | The \s-1EV\s0 module implements the full libev \s-1API\s0 and is actually used to test |
|
|
2630 | libev. \s-1EV\s0 is developed together with libev. Apart from the \s-1EV\s0 core module, |
|
|
2631 | there are additional modules that implement libev-compatible interfaces |
|
|
2632 | to \f(CW\*(C`libadns\*(C'\fR (\f(CW\*(C`EV::ADNS\*(C'\fR), \f(CW\*(C`Net::SNMP\*(C'\fR (\f(CW\*(C`Net::SNMP::EV\*(C'\fR) and the |
|
|
2633 | \&\f(CW\*(C`libglib\*(C'\fR event core (\f(CW\*(C`Glib::EV\*(C'\fR and \f(CW\*(C`EV::Glib\*(C'\fR). |
|
|
2634 | .Sp |
|
|
2635 | It can be found and installed via \s-1CPAN\s0, its homepage is found at |
|
|
2636 | <http://software.schmorp.de/pkg/EV>. |
|
|
2637 | .IP "Ruby" 4 |
|
|
2638 | .IX Item "Ruby" |
|
|
2639 | Tony Arcieri has written a ruby extension that offers access to a subset |
|
|
2640 | of the libev \s-1API\s0 and adds filehandle abstractions, asynchronous \s-1DNS\s0 and |
|
|
2641 | more on top of it. It can be found via gem servers. Its homepage is at |
|
|
2642 | <http://rev.rubyforge.org/>. |
|
|
2643 | .IP "D" 4 |
|
|
2644 | .IX Item "D" |
|
|
2645 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
|
|
2646 | be found at <http://git.llucax.com.ar/?p=software/ev.d.git;a=summary>. |
|
|
2647 | .SH "MACRO MAGIC" |
|
|
2648 | .IX Header "MACRO MAGIC" |
|
|
2649 | Libev can be compiled with a variety of options, the most fundamantal |
|
|
2650 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
|
|
2651 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
|
|
2652 | .PP |
|
|
2653 | To make it easier to write programs that cope with either variant, the |
|
|
2654 | following macros are defined: |
|
|
2655 | .ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4 |
|
|
2656 | .el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4 |
|
|
2657 | .IX Item "EV_A, EV_A_" |
|
|
2658 | This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev |
|
|
2659 | loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument, |
|
|
2660 | \&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example: |
|
|
2661 | .Sp |
|
|
2662 | .Vb 3 |
|
|
2663 | \& ev_unref (EV_A); |
|
|
2664 | \& ev_timer_add (EV_A_ watcher); |
|
|
2665 | \& ev_loop (EV_A_ 0); |
|
|
2666 | .Ve |
|
|
2667 | .Sp |
|
|
2668 | It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope, |
|
|
2669 | which is often provided by the following macro. |
|
|
2670 | .ie n .IP """EV_P""\fR, \f(CW""EV_P_""" 4 |
|
|
2671 | .el .IP "\f(CWEV_P\fR, \f(CWEV_P_\fR" 4 |
|
|
2672 | .IX Item "EV_P, EV_P_" |
|
|
2673 | This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev |
|
|
2674 | loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter, |
|
|
2675 | \&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example: |
|
|
2676 | .Sp |
|
|
2677 | .Vb 2 |
|
|
2678 | \& // this is how ev_unref is being declared |
|
|
2679 | \& static void ev_unref (EV_P); |
|
|
2680 | \& |
|
|
2681 | \& // this is how you can declare your typical callback |
|
|
2682 | \& static void cb (EV_P_ ev_timer *w, int revents) |
|
|
2683 | .Ve |
|
|
2684 | .Sp |
|
|
2685 | It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite |
|
|
2686 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
|
|
2687 | .ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4 |
|
|
2688 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
|
|
2689 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
|
|
2690 | Similar to the other two macros, this gives you the value of the default |
|
|
2691 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). |
|
|
2692 | .PP |
|
|
2693 | Example: Declare and initialise a check watcher, utilising the above |
|
|
2694 | macros so it will work regardless of whether multiple loops are supported |
|
|
2695 | or not. |
|
|
2696 | .PP |
|
|
2697 | .Vb 5 |
|
|
2698 | \& static void |
|
|
2699 | \& check_cb (EV_P_ ev_timer *w, int revents) |
|
|
2700 | \& { |
|
|
2701 | \& ev_check_stop (EV_A_ w); |
|
|
2702 | \& } |
|
|
2703 | \& |
|
|
2704 | \& ev_check check; |
|
|
2705 | \& ev_check_init (&check, check_cb); |
|
|
2706 | \& ev_check_start (EV_DEFAULT_ &check); |
|
|
2707 | \& ev_loop (EV_DEFAULT_ 0); |
|
|
2708 | .Ve |
|
|
2709 | .SH "EMBEDDING" |
|
|
2710 | .IX Header "EMBEDDING" |
|
|
2711 | Libev can (and often is) directly embedded into host |
|
|
2712 | applications. Examples of applications that embed it include the Deliantra |
|
|
2713 | Game Server, the \s-1EV\s0 perl module, the \s-1GNU\s0 Virtual Private Ethernet (gvpe) |
|
|
2714 | and rxvt-unicode. |
|
|
2715 | .PP |
|
|
2716 | The goal is to enable you to just copy the necessary files into your |
|
|
2717 | source directory without having to change even a single line in them, so |
|
|
2718 | you can easily upgrade by simply copying (or having a checked-out copy of |
|
|
2719 | libev somewhere in your source tree). |
|
|
2720 | .Sh "\s-1FILESETS\s0" |
|
|
2721 | .IX Subsection "FILESETS" |
|
|
2722 | Depending on what features you need you need to include one or more sets of files |
|
|
2723 | in your app. |
|
|
2724 | .PP |
|
|
2725 | \fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR |
|
|
2726 | .IX Subsection "CORE EVENT LOOP" |
|
|
2727 | .PP |
|
|
2728 | To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual |
|
|
2729 | configuration (no autoconf): |
|
|
2730 | .PP |
|
|
2731 | .Vb 2 |
|
|
2732 | \& #define EV_STANDALONE 1 |
|
|
2733 | \& #include "ev.c" |
|
|
2734 | .Ve |
|
|
2735 | .PP |
|
|
2736 | This will automatically include \fIev.h\fR, too, and should be done in a |
|
|
2737 | single C source file only to provide the function implementations. To use |
|
|
2738 | it, do the same for \fIev.h\fR in all files wishing to use this \s-1API\s0 (best |
|
|
2739 | done by writing a wrapper around \fIev.h\fR that you can include instead and |
|
|
2740 | where you can put other configuration options): |
|
|
2741 | .PP |
|
|
2742 | .Vb 2 |
|
|
2743 | \& #define EV_STANDALONE 1 |
|
|
2744 | \& #include "ev.h" |
|
|
2745 | .Ve |
|
|
2746 | .PP |
|
|
2747 | Both header files and implementation files can be compiled with a \*(C+ |
|
|
2748 | compiler (at least, thats a stated goal, and breakage will be treated |
|
|
2749 | as a bug). |
|
|
2750 | .PP |
|
|
2751 | You need the following files in your source tree, or in a directory |
|
|
2752 | in your include path (e.g. in libev/ when using \-Ilibev): |
|
|
2753 | .PP |
|
|
2754 | .Vb 4 |
|
|
2755 | \& ev.h |
|
|
2756 | \& ev.c |
|
|
2757 | \& ev_vars.h |
|
|
2758 | \& ev_wrap.h |
|
|
2759 | \& |
|
|
2760 | \& ev_win32.c required on win32 platforms only |
|
|
2761 | \& |
|
|
2762 | \& ev_select.c only when select backend is enabled (which is enabled by default) |
|
|
2763 | \& ev_poll.c only when poll backend is enabled (disabled by default) |
|
|
2764 | \& ev_epoll.c only when the epoll backend is enabled (disabled by default) |
|
|
2765 | \& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
|
|
2766 | \& ev_port.c only when the solaris port backend is enabled (disabled by default) |
|
|
2767 | .Ve |
|
|
2768 | .PP |
|
|
2769 | \&\fIev.c\fR includes the backend files directly when enabled, so you only need |
|
|
2770 | to compile this single file. |
|
|
2771 | .PP |
|
|
2772 | \fI\s-1LIBEVENT\s0 \s-1COMPATIBILITY\s0 \s-1API\s0\fR |
|
|
2773 | .IX Subsection "LIBEVENT COMPATIBILITY API" |
|
|
2774 | .PP |
|
|
2775 | To include the libevent compatibility \s-1API\s0, also include: |
|
|
2776 | .PP |
|
|
2777 | .Vb 1 |
|
|
2778 | \& #include "event.c" |
|
|
2779 | .Ve |
|
|
2780 | .PP |
|
|
2781 | in the file including \fIev.c\fR, and: |
|
|
2782 | .PP |
|
|
2783 | .Vb 1 |
|
|
2784 | \& #include "event.h" |
|
|
2785 | .Ve |
|
|
2786 | .PP |
|
|
2787 | in the files that want to use the libevent \s-1API\s0. This also includes \fIev.h\fR. |
|
|
2788 | .PP |
|
|
2789 | You need the following additional files for this: |
|
|
2790 | .PP |
|
|
2791 | .Vb 2 |
|
|
2792 | \& event.h |
|
|
2793 | \& event.c |
|
|
2794 | .Ve |
|
|
2795 | .PP |
|
|
2796 | \fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR |
|
|
2797 | .IX Subsection "AUTOCONF SUPPORT" |
|
|
2798 | .PP |
|
|
2799 | Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your config in |
|
|
2800 | whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your |
|
|
2801 | \&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then |
|
|
2802 | include \fIconfig.h\fR and configure itself accordingly. |
|
|
2803 | .PP |
|
|
2804 | For this of course you need the m4 file: |
|
|
2805 | .PP |
|
|
2806 | .Vb 1 |
|
|
2807 | \& libev.m4 |
|
|
2808 | .Ve |
|
|
2809 | .Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
|
|
2810 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
|
|
2811 | Libev can be configured via a variety of preprocessor symbols you have to define |
|
|
2812 | before including any of its files. The default is not to build for multiplicity |
|
|
2813 | and only include the select backend. |
|
|
2814 | .IP "\s-1EV_STANDALONE\s0" 4 |
|
|
2815 | .IX Item "EV_STANDALONE" |
|
|
2816 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
|
|
2817 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
|
|
2818 | implementations for some libevent functions (such as logging, which is not |
|
|
2819 | supported). It will also not define any of the structs usually found in |
|
|
2820 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
|
|
2821 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
|
|
2822 | .IX Item "EV_USE_MONOTONIC" |
|
|
2823 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
|
|
2824 | monotonic clock option at both compiletime and runtime. Otherwise no use |
|
|
2825 | of the monotonic clock option will be attempted. If you enable this, you |
|
|
2826 | usually have to link against librt or something similar. Enabling it when |
|
|
2827 | the functionality isn't available is safe, though, although you have |
|
|
2828 | to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR |
|
|
2829 | function is hiding in (often \fI\-lrt\fR). |
|
|
2830 | .IP "\s-1EV_USE_REALTIME\s0" 4 |
|
|
2831 | .IX Item "EV_USE_REALTIME" |
|
|
2832 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
|
|
2833 | realtime clock option at compiletime (and assume its availability at |
|
|
2834 | runtime if successful). Otherwise no use of the realtime clock option will |
|
|
2835 | be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get |
|
|
2836 | (CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See the |
|
|
2837 | note about libraries in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though. |
|
|
2838 | .IP "\s-1EV_USE_NANOSLEEP\s0" 4 |
|
|
2839 | .IX Item "EV_USE_NANOSLEEP" |
|
|
2840 | If defined to be \f(CW1\fR, libev will assume that \f(CW\*(C`nanosleep ()\*(C'\fR is available |
|
|
2841 | and will use it for delays. Otherwise it will use \f(CW\*(C`select ()\*(C'\fR. |
|
|
2842 | .IP "\s-1EV_USE_SELECT\s0" 4 |
|
|
2843 | .IX Item "EV_USE_SELECT" |
|
|
2844 | If undefined or defined to be \f(CW1\fR, libev will compile in support for the |
|
|
2845 | \&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at autodetection will be done: if no |
|
|
2846 | other method takes over, select will be it. Otherwise the select backend |
|
|
2847 | will not be compiled in. |
|
|
2848 | .IP "\s-1EV_SELECT_USE_FD_SET\s0" 4 |
|
|
2849 | .IX Item "EV_SELECT_USE_FD_SET" |
|
|
2850 | If defined to \f(CW1\fR, then the select backend will use the system \f(CW\*(C`fd_set\*(C'\fR |
|
|
2851 | structure. This is useful if libev doesn't compile due to a missing |
|
|
2852 | \&\f(CW\*(C`NFDBITS\*(C'\fR or \f(CW\*(C`fd_mask\*(C'\fR definition or it misguesses the bitset layout on |
|
|
2853 | exotic systems. This usually limits the range of file descriptors to some |
|
|
2854 | low limit such as 1024 or might have other limitations (winsocket only |
|
|
2855 | allows 64 sockets). The \f(CW\*(C`FD_SETSIZE\*(C'\fR macro, set before compilation, might |
|
|
2856 | influence the size of the \f(CW\*(C`fd_set\*(C'\fR used. |
|
|
2857 | .IP "\s-1EV_SELECT_IS_WINSOCKET\s0" 4 |
|
|
2858 | .IX Item "EV_SELECT_IS_WINSOCKET" |
|
|
2859 | When defined to \f(CW1\fR, the select backend will assume that |
|
|
2860 | select/socket/connect etc. don't understand file descriptors but |
|
|
2861 | wants osf handles on win32 (this is the case when the select to |
|
|
2862 | be used is the winsock select). This means that it will call |
|
|
2863 | \&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise, |
|
|
2864 | it is assumed that all these functions actually work on fds, even |
|
|
2865 | on win32. Should not be defined on non\-win32 platforms. |
|
|
2866 | .IP "\s-1EV_FD_TO_WIN32_HANDLE\s0" 4 |
|
|
2867 | .IX Item "EV_FD_TO_WIN32_HANDLE" |
|
|
2868 | If \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR is enabled, then libev needs a way to map |
|
|
2869 | file descriptors to socket handles. When not defining this symbol (the |
|
|
2870 | default), then libev will call \f(CW\*(C`_get_osfhandle\*(C'\fR, which is usually |
|
|
2871 | correct. In some cases, programs use their own file descriptor management, |
|
|
2872 | in which case they can provide this function to map fds to socket handles. |
|
|
2873 | .IP "\s-1EV_USE_POLL\s0" 4 |
|
|
2874 | .IX Item "EV_USE_POLL" |
|
|
2875 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
|
|
2876 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
|
|
2877 | takes precedence over select. |
|
|
2878 | .IP "\s-1EV_USE_EPOLL\s0" 4 |
|
|
2879 | .IX Item "EV_USE_EPOLL" |
|
|
2880 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
|
|
2881 | \&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime, |
|
|
2882 | otherwise another method will be used as fallback. This is the |
|
|
2883 | preferred backend for GNU/Linux systems. |
|
|
2884 | .IP "\s-1EV_USE_KQUEUE\s0" 4 |
|
|
2885 | .IX Item "EV_USE_KQUEUE" |
|
|
2886 | If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style |
|
|
2887 | \&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime, |
|
|
2888 | otherwise another method will be used as fallback. This is the preferred |
|
|
2889 | backend for \s-1BSD\s0 and BSD-like systems, although on most BSDs kqueue only |
|
|
2890 | supports some types of fds correctly (the only platform we found that |
|
|
2891 | supports ptys for example was NetBSD), so kqueue might be compiled in, but |
|
|
2892 | not be used unless explicitly requested. The best way to use it is to find |
|
|
2893 | out whether kqueue supports your type of fd properly and use an embedded |
|
|
2894 | kqueue loop. |
|
|
2895 | .IP "\s-1EV_USE_PORT\s0" 4 |
|
|
2896 | .IX Item "EV_USE_PORT" |
|
|
2897 | If defined to be \f(CW1\fR, libev will compile in support for the Solaris |
|
|
2898 | 10 port style backend. Its availability will be detected at runtime, |
|
|
2899 | otherwise another method will be used as fallback. This is the preferred |
|
|
2900 | backend for Solaris 10 systems. |
|
|
2901 | .IP "\s-1EV_USE_DEVPOLL\s0" 4 |
|
|
2902 | .IX Item "EV_USE_DEVPOLL" |
|
|
2903 | reserved for future expansion, works like the \s-1USE\s0 symbols above. |
|
|
2904 | .IP "\s-1EV_USE_INOTIFY\s0" 4 |
|
|
2905 | .IX Item "EV_USE_INOTIFY" |
|
|
2906 | If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify |
|
|
2907 | interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will |
|
|
2908 | be detected at runtime. |
|
|
2909 | .IP "\s-1EV_ATOMIC_T\s0" 4 |
|
|
2910 | .IX Item "EV_ATOMIC_T" |
|
|
2911 | Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose |
|
|
2912 | access is atomic with respect to other threads or signal contexts. No such |
|
|
2913 | type is easily found in the C language, so you can provide your own type |
|
|
2914 | that you know is safe for your purposes. It is used both for signal handler \*(L"locking\*(R" |
|
|
2915 | as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR watchers. |
|
|
2916 | .Sp |
|
|
2917 | In the absense of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
|
|
2918 | (from \fIsignal.h\fR), which is usually good enough on most platforms. |
|
|
2919 | .IP "\s-1EV_H\s0" 4 |
|
|
2920 | .IX Item "EV_H" |
|
|
2921 | The name of the \fIev.h\fR header file used to include it. The default if |
|
|
2922 | undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be |
|
|
2923 | used to virtually rename the \fIev.h\fR header file in case of conflicts. |
|
|
2924 | .IP "\s-1EV_CONFIG_H\s0" 4 |
|
|
2925 | .IX Item "EV_CONFIG_H" |
|
|
2926 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
|
|
2927 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
|
|
2928 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
|
|
2929 | .IP "\s-1EV_EVENT_H\s0" 4 |
|
|
2930 | .IX Item "EV_EVENT_H" |
|
|
2931 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
|
|
2932 | of how the \fIevent.h\fR header can be found, the default is \f(CW"event.h"\fR. |
|
|
2933 | .IP "\s-1EV_PROTOTYPES\s0" 4 |
|
|
2934 | .IX Item "EV_PROTOTYPES" |
|
|
2935 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
|
|
2936 | prototypes, but still define all the structs and other symbols. This is |
|
|
2937 | occasionally useful if you want to provide your own wrapper functions |
|
|
2938 | around libev functions. |
|
|
2939 | .IP "\s-1EV_MULTIPLICITY\s0" 4 |
|
|
2940 | .IX Item "EV_MULTIPLICITY" |
|
|
2941 | If undefined or defined to \f(CW1\fR, then all event-loop-specific functions |
|
|
2942 | will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create |
|
|
2943 | additional independent event loops. Otherwise there will be no support |
|
|
2944 | for multiple event loops and there is no first event loop pointer |
|
|
2945 | argument. Instead, all functions act on the single default loop. |
|
|
2946 | .IP "\s-1EV_MINPRI\s0" 4 |
|
|
2947 | .IX Item "EV_MINPRI" |
|
|
2948 | .PD 0 |
|
|
2949 | .IP "\s-1EV_MAXPRI\s0" 4 |
|
|
2950 | .IX Item "EV_MAXPRI" |
|
|
2951 | .PD |
|
|
2952 | The range of allowed priorities. \f(CW\*(C`EV_MINPRI\*(C'\fR must be smaller or equal to |
|
|
2953 | \&\f(CW\*(C`EV_MAXPRI\*(C'\fR, but otherwise there are no non-obvious limitations. You can |
|
|
2954 | provide for more priorities by overriding those symbols (usually defined |
|
|
2955 | to be \f(CW\*(C`\-2\*(C'\fR and \f(CW2\fR, respectively). |
|
|
2956 | .Sp |
|
|
2957 | When doing priority-based operations, libev usually has to linearly search |
|
|
2958 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
2959 | and time, so using the defaults of five priorities (\-2 .. +2) is usually |
|
|
2960 | fine. |
|
|
2961 | .Sp |
|
|
2962 | If your embedding app does not need any priorities, defining these both to |
|
|
2963 | \&\f(CW0\fR will save some memory and cpu. |
|
|
2964 | .IP "\s-1EV_PERIODIC_ENABLE\s0" 4 |
|
|
2965 | .IX Item "EV_PERIODIC_ENABLE" |
|
|
2966 | If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If |
|
|
2967 | defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of |
|
|
2968 | code. |
|
|
2969 | .IP "\s-1EV_IDLE_ENABLE\s0" 4 |
|
|
2970 | .IX Item "EV_IDLE_ENABLE" |
|
|
2971 | If undefined or defined to be \f(CW1\fR, then idle watchers are supported. If |
|
|
2972 | defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of |
|
|
2973 | code. |
|
|
2974 | .IP "\s-1EV_EMBED_ENABLE\s0" 4 |
|
|
2975 | .IX Item "EV_EMBED_ENABLE" |
|
|
2976 | If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If |
|
|
2977 | defined to be \f(CW0\fR, then they are not. |
|
|
2978 | .IP "\s-1EV_STAT_ENABLE\s0" 4 |
|
|
2979 | .IX Item "EV_STAT_ENABLE" |
|
|
2980 | If undefined or defined to be \f(CW1\fR, then stat watchers are supported. If |
|
|
2981 | defined to be \f(CW0\fR, then they are not. |
|
|
2982 | .IP "\s-1EV_FORK_ENABLE\s0" 4 |
|
|
2983 | .IX Item "EV_FORK_ENABLE" |
|
|
2984 | If undefined or defined to be \f(CW1\fR, then fork watchers are supported. If |
|
|
2985 | defined to be \f(CW0\fR, then they are not. |
|
|
2986 | .IP "\s-1EV_ASYNC_ENABLE\s0" 4 |
|
|
2987 | .IX Item "EV_ASYNC_ENABLE" |
|
|
2988 | If undefined or defined to be \f(CW1\fR, then async watchers are supported. If |
|
|
2989 | defined to be \f(CW0\fR, then they are not. |
|
|
2990 | .IP "\s-1EV_MINIMAL\s0" 4 |
|
|
2991 | .IX Item "EV_MINIMAL" |
|
|
2992 | If you need to shave off some kilobytes of code at the expense of some |
|
|
2993 | speed, define this symbol to \f(CW1\fR. Currently only used for gcc to override |
|
|
2994 | some inlining decisions, saves roughly 30% codesize of amd64. |
|
|
2995 | .IP "\s-1EV_PID_HASHSIZE\s0" 4 |
|
|
2996 | .IX Item "EV_PID_HASHSIZE" |
|
|
2997 | \&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by |
|
|
2998 | pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more |
|
|
2999 | than enough. If you need to manage thousands of children you might want to |
|
|
3000 | increase this value (\fImust\fR be a power of two). |
|
|
3001 | .IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4 |
|
|
3002 | .IX Item "EV_INOTIFY_HASHSIZE" |
|
|
3003 | \&\f(CW\*(C`ev_stat\*(C'\fR watchers use a small hash table to distribute workload by |
|
|
3004 | inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), |
|
|
3005 | usually more than enough. If you need to manage thousands of \f(CW\*(C`ev_stat\*(C'\fR |
|
|
3006 | watchers you might want to increase this value (\fImust\fR be a power of |
|
|
3007 | two). |
|
|
3008 | .IP "\s-1EV_COMMON\s0" 4 |
|
|
3009 | .IX Item "EV_COMMON" |
|
|
3010 | By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining |
|
|
3011 | this macro to a something else you can include more and other types of |
|
|
3012 | members. You have to define it each time you include one of the files, |
|
|
3013 | though, and it must be identical each time. |
|
|
3014 | .Sp |
|
|
3015 | For example, the perl \s-1EV\s0 module uses something like this: |
|
|
3016 | .Sp |
|
|
3017 | .Vb 3 |
|
|
3018 | \& #define EV_COMMON \e |
|
|
3019 | \& SV *self; /* contains this struct */ \e |
|
|
3020 | \& SV *cb_sv, *fh /* note no trailing ";" */ |
|
|
3021 | .Ve |
|
|
3022 | .IP "\s-1EV_CB_DECLARE\s0 (type)" 4 |
|
|
3023 | .IX Item "EV_CB_DECLARE (type)" |
|
|
3024 | .PD 0 |
|
|
3025 | .IP "\s-1EV_CB_INVOKE\s0 (watcher, revents)" 4 |
|
|
3026 | .IX Item "EV_CB_INVOKE (watcher, revents)" |
|
|
3027 | .IP "ev_set_cb (ev, cb)" 4 |
|
|
3028 | .IX Item "ev_set_cb (ev, cb)" |
|
|
3029 | .PD |
|
|
3030 | Can be used to change the callback member declaration in each watcher, |
|
|
3031 | and the way callbacks are invoked and set. Must expand to a struct member |
|
|
3032 | definition and a statement, respectively. See the \fIev.h\fR header file for |
|
|
3033 | their default definitions. One possible use for overriding these is to |
|
|
3034 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
|
|
3035 | method calls instead of plain function calls in \*(C+. |
|
|
3036 | .Sh "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" |
|
|
3037 | .IX Subsection "EXPORTED API SYMBOLS" |
|
|
3038 | If you need to re-export the \s-1API\s0 (e.g. via a dll) and you need a list of |
|
|
3039 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
|
|
3040 | all public symbols, one per line: |
|
|
3041 | .PP |
|
|
3042 | .Vb 2 |
|
|
3043 | \& Symbols.ev for libev proper |
|
|
3044 | \& Symbols.event for the libevent emulation |
|
|
3045 | .Ve |
|
|
3046 | .PP |
|
|
3047 | This can also be used to rename all public symbols to avoid clashes with |
|
|
3048 | multiple versions of libev linked together (which is obviously bad in |
|
|
3049 | itself, but sometimes it is inconvinient to avoid this). |
|
|
3050 | .PP |
|
|
3051 | A sed command like this will create wrapper \f(CW\*(C`#define\*(C'\fR's that you need to |
|
|
3052 | include before including \fIev.h\fR: |
|
|
3053 | .PP |
|
|
3054 | .Vb 1 |
|
|
3055 | \& <Symbols.ev sed \-e "s/.*/#define & myprefix_&/" >wrap.h |
|
|
3056 | .Ve |
|
|
3057 | .PP |
|
|
3058 | This would create a file \fIwrap.h\fR which essentially looks like this: |
|
|
3059 | .PP |
|
|
3060 | .Vb 4 |
|
|
3061 | \& #define ev_backend myprefix_ev_backend |
|
|
3062 | \& #define ev_check_start myprefix_ev_check_start |
|
|
3063 | \& #define ev_check_stop myprefix_ev_check_stop |
|
|
3064 | \& ... |
|
|
3065 | .Ve |
|
|
3066 | .Sh "\s-1EXAMPLES\s0" |
|
|
3067 | .IX Subsection "EXAMPLES" |
|
|
3068 | For a real-world example of a program the includes libev |
|
|
3069 | verbatim, you can have a look at the \s-1EV\s0 perl module |
|
|
3070 | (<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
|
|
3071 | the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public |
|
|
3072 | interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file |
|
|
3073 | will be compiled. It is pretty complex because it provides its own header |
|
|
3074 | file. |
|
|
3075 | .PP |
|
|
3076 | The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file |
|
|
3077 | that everybody includes and which overrides some configure choices: |
|
|
3078 | .PP |
|
|
3079 | .Vb 9 |
|
|
3080 | \& #define EV_MINIMAL 1 |
|
|
3081 | \& #define EV_USE_POLL 0 |
|
|
3082 | \& #define EV_MULTIPLICITY 0 |
|
|
3083 | \& #define EV_PERIODIC_ENABLE 0 |
|
|
3084 | \& #define EV_STAT_ENABLE 0 |
|
|
3085 | \& #define EV_FORK_ENABLE 0 |
|
|
3086 | \& #define EV_CONFIG_H <config.h> |
|
|
3087 | \& #define EV_MINPRI 0 |
|
|
3088 | \& #define EV_MAXPRI 0 |
|
|
3089 | \& |
|
|
3090 | \& #include "ev++.h" |
|
|
3091 | .Ve |
|
|
3092 | .PP |
|
|
3093 | And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled: |
|
|
3094 | .PP |
|
|
3095 | .Vb 2 |
|
|
3096 | \& #include "ev_cpp.h" |
|
|
3097 | \& #include "ev.c" |
|
|
3098 | .Ve |
|
|
3099 | .SH "COMPLEXITIES" |
|
|
3100 | .IX Header "COMPLEXITIES" |
|
|
3101 | In this section the complexities of (many of) the algorithms used inside |
|
|
3102 | libev will be explained. For complexity discussions about backends see the |
|
|
3103 | documentation for \f(CW\*(C`ev_default_init\*(C'\fR. |
|
|
3104 | .PP |
|
|
3105 | All of the following are about amortised time: If an array needs to be |
|
|
3106 | extended, libev needs to realloc and move the whole array, but this |
|
|
3107 | happens asymptotically never with higher number of elements, so O(1) might |
|
|
3108 | mean it might do a lengthy realloc operation in rare cases, but on average |
|
|
3109 | it is much faster and asymptotically approaches constant time. |
|
|
3110 | .IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4 |
|
|
3111 | .IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" |
|
|
3112 | This means that, when you have a watcher that triggers in one hour and |
|
|
3113 | there are 100 watchers that would trigger before that then inserting will |
|
|
3114 | have to skip roughly seven (\f(CW\*(C`ld 100\*(C'\fR) of these watchers. |
|
|
3115 | .IP "Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)" 4 |
|
|
3116 | .IX Item "Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)" |
|
|
3117 | That means that changing a timer costs less than removing/adding them |
|
|
3118 | as only the relative motion in the event queue has to be paid for. |
|
|
3119 | .IP "Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1)" 4 |
|
|
3120 | .IX Item "Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1)" |
|
|
3121 | These just add the watcher into an array or at the head of a list. |
|
|
3122 | .IP "Stopping check/prepare/idle/fork/async watchers: O(1)" 4 |
|
|
3123 | .IX Item "Stopping check/prepare/idle/fork/async watchers: O(1)" |
|
|
3124 | .PD 0 |
|
|
3125 | .IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4 |
|
|
3126 | .IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))" |
|
|
3127 | .PD |
|
|
3128 | These watchers are stored in lists then need to be walked to find the |
|
|
3129 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
3130 | have many watchers waiting for the same fd or signal). |
|
|
3131 | .IP "Finding the next timer in each loop iteration: O(1)" 4 |
|
|
3132 | .IX Item "Finding the next timer in each loop iteration: O(1)" |
|
|
3133 | By virtue of using a binary heap, the next timer is always found at the |
|
|
3134 | beginning of the storage array. |
|
|
3135 | .IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4 |
|
|
3136 | .IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" |
|
|
3137 | A change means an I/O watcher gets started or stopped, which requires |
|
|
3138 | libev to recalculate its status (and possibly tell the kernel, depending |
|
|
3139 | on backend and wether \f(CW\*(C`ev_io_set\*(C'\fR was used). |
|
|
3140 | .IP "Activating one watcher (putting it into the pending state): O(1)" 4 |
|
|
3141 | .IX Item "Activating one watcher (putting it into the pending state): O(1)" |
|
|
3142 | .PD 0 |
|
|
3143 | .IP "Priority handling: O(number_of_priorities)" 4 |
|
|
3144 | .IX Item "Priority handling: O(number_of_priorities)" |
|
|
3145 | .PD |
|
|
3146 | Priorities are implemented by allocating some space for each |
|
|
3147 | priority. When doing priority-based operations, libev usually has to |
|
|
3148 | linearly search all the priorities, but starting/stopping and activating |
|
|
3149 | watchers becomes O(1) w.r.t. priority handling. |
|
|
3150 | .IP "Sending an ev_async: O(1)" 4 |
|
|
3151 | .IX Item "Sending an ev_async: O(1)" |
|
|
3152 | .PD 0 |
|
|
3153 | .IP "Processing ev_async_send: O(number_of_async_watchers)" 4 |
|
|
3154 | .IX Item "Processing ev_async_send: O(number_of_async_watchers)" |
|
|
3155 | .IP "Processing signals: O(max_signal_number)" 4 |
|
|
3156 | .IX Item "Processing signals: O(max_signal_number)" |
|
|
3157 | .PD |
|
|
3158 | Sending involves a syscall \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
|
|
3159 | calls in the current loop iteration. Checking for async and signal events |
|
|
3160 | involves iterating over all running async watchers or all signal numbers. |
|
|
3161 | .SH "Win32 platform limitations and workarounds" |
|
|
3162 | .IX Header "Win32 platform limitations and workarounds" |
|
|
3163 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
|
|
3164 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
|
|
3165 | model. Libev still offers limited functionality on this platform in |
|
|
3166 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
|
|
3167 | descriptors. This only applies when using Win32 natively, not when using |
|
|
3168 | e.g. cygwin. |
|
|
3169 | .PP |
|
|
3170 | There is no supported compilation method available on windows except |
|
|
3171 | embedding it into other applications. |
|
|
3172 | .PP |
|
|
3173 | Due to the many, low, and arbitrary limits on the win32 platform and the |
|
|
3174 | abysmal performance of winsockets, using a large number of sockets is not |
|
|
3175 | recommended (and not reasonable). If your program needs to use more than |
|
|
3176 | a hundred or so sockets, then likely it needs to use a totally different |
|
|
3177 | implementation for windows, as libev offers the \s-1POSIX\s0 model, which cannot |
|
|
3178 | be implemented efficiently on windows (microsoft monopoly games). |
|
|
3179 | .IP "The winsocket select function" 4 |
|
|
3180 | .IX Item "The winsocket select function" |
|
|
3181 | The winsocket \f(CW\*(C`select\*(C'\fR function doesn't follow \s-1POSIX\s0 in that it requires |
|
|
3182 | socket \fIhandles\fR and not socket \fIfile descriptors\fR. This makes select |
|
|
3183 | very inefficient, and also requires a mapping from file descriptors |
|
|
3184 | to socket handles. See the discussion of the \f(CW\*(C`EV_SELECT_USE_FD_SET\*(C'\fR, |
|
|
3185 | \&\f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR and \f(CW\*(C`EV_FD_TO_WIN32_HANDLE\*(C'\fR preprocessor |
|
|
3186 | symbols for more info. |
|
|
3187 | .Sp |
|
|
3188 | The configuration for a \*(L"naked\*(R" win32 using the microsoft runtime |
|
|
3189 | libraries and raw winsocket select is: |
|
|
3190 | .Sp |
|
|
3191 | .Vb 2 |
|
|
3192 | \& #define EV_USE_SELECT 1 |
|
|
3193 | \& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
|
|
3194 | .Ve |
|
|
3195 | .Sp |
|
|
3196 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
|
|
3197 | complexity in the O(nA\*^X) range when using win32. |
|
|
3198 | .IP "Limited number of file descriptors" 4 |
|
|
3199 | .IX Item "Limited number of file descriptors" |
|
|
3200 | Windows has numerous arbitrary (and low) limits on things. Early versions |
|
|
3201 | of winsocket's select only supported waiting for a max. of \f(CW64\fR handles |
|
|
3202 | (probably owning to the fact that all windows kernels can only wait for |
|
|
3203 | \&\f(CW64\fR things at the same time internally; microsoft recommends spawning a |
|
|
3204 | chain of threads and wait for 63 handles and the previous thread in each). |
|
|
3205 | .Sp |
|
|
3206 | Newer versions support more handles, but you need to define \f(CW\*(C`FD_SETSIZE\*(C'\fR |
|
|
3207 | to some high number (e.g. \f(CW2048\fR) before compiling the winsocket select |
|
|
3208 | call (which might be in libev or elsewhere, for example, perl does its own |
|
|
3209 | select emulation on windows). |
|
|
3210 | .Sp |
|
|
3211 | Another limit is the number of file descriptors in the microsoft runtime |
|
|
3212 | libraries, which by default is \f(CW64\fR (there must be a hidden \fI64\fR fetish |
|
|
3213 | or something like this inside microsoft). You can increase this by calling |
|
|
3214 | \&\f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR (another |
|
|
3215 | arbitrary limit), but is broken in many versions of the microsoft runtime |
|
|
3216 | libraries. |
|
|
3217 | .Sp |
|
|
3218 | This might get you to about \f(CW512\fR or \f(CW2048\fR sockets (depending on |
|
|
3219 | windows version and/or the phase of the moon). To get more, you need to |
|
|
3220 | wrap all I/O functions and provide your own fd management, but the cost of |
|
|
3221 | calling select (O(nA\*^X)) will likely make this unworkable. |
995 | .SH "AUTHOR" |
3222 | .SH "AUTHOR" |
996 | .IX Header "AUTHOR" |
3223 | .IX Header "AUTHOR" |
997 | Marc Lehmann <libev@schmorp.de>. |
3224 | Marc Lehmann <libev@schmorp.de>. |
|
|
3225 | .SH "POD ERRORS" |
|
|
3226 | .IX Header "POD ERRORS" |
|
|
3227 | Hey! \fBThe above document had some coding errors, which are explained below:\fR |
|
|
3228 | .IP "Around line 2951:" 4 |
|
|
3229 | .IX Item "Around line 2951:" |
|
|
3230 | You forgot a '=back' before '=head2' |