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134 | .IX Title "LIBEV 3" |
126 | .IX Title "LIBEV 3" |
135 | .TH LIBEV 3 "2008-10-30" "libev-3.48" "libev - high performance full featured event loop" |
127 | .TH LIBEV 3 "2009-07-15" "libev-3.7" "libev - high performance full featured event loop" |
136 | .\" For nroff, turn off justification. Always turn off hyphenation; it makes |
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138 | .if n .ad l |
130 | .if n .ad l |
139 | .nh |
131 | .nh |
140 | .SH "NAME" |
132 | .SH "NAME" |
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142 | .SH "SYNOPSIS" |
134 | .SH "SYNOPSIS" |
143 | .IX Header "SYNOPSIS" |
135 | .IX Header "SYNOPSIS" |
144 | .Vb 1 |
136 | .Vb 1 |
145 | \& #include <ev.h> |
137 | \& #include <ev.h> |
146 | .Ve |
138 | .Ve |
147 | .Sh "\s-1EXAMPLE\s0 \s-1PROGRAM\s0" |
139 | .SS "\s-1EXAMPLE\s0 \s-1PROGRAM\s0" |
148 | .IX Subsection "EXAMPLE PROGRAM" |
140 | .IX Subsection "EXAMPLE PROGRAM" |
149 | .Vb 2 |
141 | .Vb 2 |
150 | \& // a single header file is required |
142 | \& // a single header file is required |
151 | \& #include <ev.h> |
143 | \& #include <ev.h> |
152 | \& |
144 | \& |
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145 | \& #include <stdio.h> // for puts |
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146 | \& |
153 | \& // every watcher type has its own typedef\*(Aqd struct |
147 | \& // every watcher type has its own typedef\*(Aqd struct |
154 | \& // with the name ev_TYPE |
148 | \& // with the name ev_TYPE |
155 | \& ev_io stdin_watcher; |
149 | \& ev_io stdin_watcher; |
156 | \& ev_timer timeout_watcher; |
150 | \& ev_timer timeout_watcher; |
157 | \& |
151 | \& |
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180 | \& |
174 | \& |
181 | \& int |
175 | \& int |
182 | \& main (void) |
176 | \& main (void) |
183 | \& { |
177 | \& { |
184 | \& // use the default event loop unless you have special needs |
178 | \& // use the default event loop unless you have special needs |
185 | \& ev_loop *loop = ev_default_loop (0); |
179 | \& struct ev_loop *loop = ev_default_loop (0); |
186 | \& |
180 | \& |
187 | \& // initialise an io watcher, then start it |
181 | \& // initialise an io watcher, then start it |
188 | \& // this one will watch for stdin to become readable |
182 | \& // this one will watch for stdin to become readable |
189 | \& ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
183 | \& ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
190 | \& ev_io_start (loop, &stdin_watcher); |
184 | \& ev_io_start (loop, &stdin_watcher); |
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199 | \& |
193 | \& |
200 | \& // unloop was called, so exit |
194 | \& // unloop was called, so exit |
201 | \& return 0; |
195 | \& return 0; |
202 | \& } |
196 | \& } |
203 | .Ve |
197 | .Ve |
204 | .SH "DESCRIPTION" |
198 | .SH "ABOUT THIS DOCUMENT" |
205 | .IX Header "DESCRIPTION" |
199 | .IX Header "ABOUT THIS DOCUMENT" |
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200 | This document documents the libev software package. |
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201 | .PP |
206 | The newest version of this document is also available as an html-formatted |
202 | 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 |
203 | web page you might find easier to navigate when reading it for the first |
208 | time: <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>. |
204 | time: <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>. |
209 | .PP |
205 | .PP |
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206 | While this document tries to be as complete as possible in documenting |
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207 | libev, its usage and the rationale behind its design, it is not a tutorial |
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208 | on event-based programming, nor will it introduce event-based programming |
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209 | with libev. |
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210 | .PP |
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211 | Familarity with event based programming techniques in general is assumed |
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212 | throughout this document. |
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213 | .SH "ABOUT LIBEV" |
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214 | .IX Header "ABOUT LIBEV" |
210 | Libev is an event loop: you register interest in certain events (such as a |
215 | Libev is an event loop: you register interest in certain events (such as a |
211 | file descriptor being readable or a timeout occurring), and it will manage |
216 | file descriptor being readable or a timeout occurring), and it will manage |
212 | these event sources and provide your program with events. |
217 | these event sources and provide your program with events. |
213 | .PP |
218 | .PP |
214 | To do this, it must take more or less complete control over your process |
219 | To do this, it must take more or less complete control over your process |
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217 | .PP |
222 | .PP |
218 | You register interest in certain events by registering so-called \fIevent |
223 | You register interest in certain events by registering so-called \fIevent |
219 | watchers\fR, which are relatively small C structures you initialise with the |
224 | watchers\fR, which are relatively small C structures you initialise with the |
220 | details of the event, and then hand it over to libev by \fIstarting\fR the |
225 | details of the event, and then hand it over to libev by \fIstarting\fR the |
221 | watcher. |
226 | watcher. |
222 | .Sh "\s-1FEATURES\s0" |
227 | .SS "\s-1FEATURES\s0" |
223 | .IX Subsection "FEATURES" |
228 | .IX Subsection "FEATURES" |
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 |
229 | Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific \f(CW\*(C`epoll\*(C'\fR, the |
225 | BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms |
230 | BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms |
226 | for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface |
231 | for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface |
227 | (for \f(CW\*(C`ev_stat\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers |
232 | (for \f(CW\*(C`ev_stat\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers |
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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 |
236 | \&\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 |
237 | file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events |
233 | (\f(CW\*(C`ev_fork\*(C'\fR). |
238 | (\f(CW\*(C`ev_fork\*(C'\fR). |
234 | .PP |
239 | .PP |
235 | It also is quite fast (see this |
240 | It also is quite fast (see this |
236 | benchmark comparing it to libevent |
241 | <benchmark> comparing it to libevent |
237 | for example). |
242 | for example). |
238 | .Sh "\s-1CONVENTIONS\s0" |
243 | .SS "\s-1CONVENTIONS\s0" |
239 | .IX Subsection "CONVENTIONS" |
244 | .IX Subsection "CONVENTIONS" |
240 | Libev is very configurable. In this manual the default (and most common) |
245 | Libev is very configurable. In this manual the default (and most common) |
241 | configuration will be described, which supports multiple event loops. For |
246 | configuration will be described, which supports multiple event loops. For |
242 | more info about various configuration options please have a look at |
247 | more info about various configuration options please have a look at |
243 | \&\fB\s-1EMBED\s0\fR section in this manual. If libev was configured without support |
248 | \&\fB\s-1EMBED\s0\fR section in this manual. If libev was configured without support |
244 | for multiple event loops, then all functions taking an initial argument of |
249 | for multiple event loops, then all functions taking an initial argument of |
245 | name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`ev_loop *\*(C'\fR) will not have |
250 | name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`ev_loop *\*(C'\fR) will not have |
246 | this argument. |
251 | this argument. |
247 | .Sh "\s-1TIME\s0 \s-1REPRESENTATION\s0" |
252 | .SS "\s-1TIME\s0 \s-1REPRESENTATION\s0" |
248 | .IX Subsection "TIME REPRESENTATION" |
253 | .IX Subsection "TIME REPRESENTATION" |
249 | Libev represents time as a single floating point number, representing the |
254 | Libev represents time as a single floating point number, representing |
250 | (fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near |
255 | the (fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere |
251 | the beginning of 1970, details are complicated, don't ask). This type is |
256 | near the beginning of 1970, details are complicated, don't ask). This |
252 | called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually aliases |
257 | type is called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually |
253 | to the \f(CW\*(C`double\*(C'\fR type in C, and when you need to do any calculations on |
258 | aliases to the \f(CW\*(C`double\*(C'\fR type in C. When you need to do any calculations |
254 | it, you should treat it as some floating point value. Unlike the name |
259 | on it, you should treat it as some floating point value. Unlike the name |
255 | component \f(CW\*(C`stamp\*(C'\fR might indicate, it is also used for time differences |
260 | component \f(CW\*(C`stamp\*(C'\fR might indicate, it is also used for time differences |
256 | throughout libev. |
261 | throughout libev. |
257 | .SH "ERROR HANDLING" |
262 | .SH "ERROR HANDLING" |
258 | .IX Header "ERROR HANDLING" |
263 | .IX Header "ERROR HANDLING" |
259 | Libev knows three classes of errors: operating system errors, usage errors |
264 | Libev knows three classes of errors: operating system errors, usage errors |
… | |
… | |
544 | starting a watcher (without re-setting it) also usually doesn't cause |
549 | starting a watcher (without re-setting it) also usually doesn't cause |
545 | extra overhead. A fork can both result in spurious notifications as well |
550 | extra overhead. A fork can both result in spurious notifications as well |
546 | as in libev having to destroy and recreate the epoll object, which can |
551 | as in libev having to destroy and recreate the epoll object, which can |
547 | take considerable time and thus should be avoided. |
552 | take considerable time and thus should be avoided. |
548 | .Sp |
553 | .Sp |
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554 | All this means that, in practice, \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR can be as fast or |
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555 | faster than epoll for maybe up to a hundred file descriptors, depending on |
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556 | the usage. So sad. |
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557 | .Sp |
549 | While nominally embeddable in other event loops, this feature is broken in |
558 | While nominally embeddable in other event loops, this feature is broken in |
550 | all kernel versions tested so far. |
559 | all kernel versions tested so far. |
551 | .Sp |
560 | .Sp |
552 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
561 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
553 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
562 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
… | |
… | |
580 | .Sp |
589 | .Sp |
581 | While nominally embeddable in other event loops, this doesn't work |
590 | While nominally embeddable in other event loops, this doesn't work |
582 | everywhere, so you might need to test for this. And since it is broken |
591 | everywhere, so you might need to test for this. And since it is broken |
583 | almost everywhere, you should only use it when you have a lot of sockets |
592 | almost everywhere, you should only use it when you have a lot of sockets |
584 | (for which it usually works), by embedding it into another event loop |
593 | (for which it usually works), by embedding it into another event loop |
585 | (e.g. \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR) and, did I mention it, |
594 | (e.g. \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR (but \f(CW\*(C`poll\*(C'\fR is of course |
586 | using it only for sockets. |
595 | also broken on \s-1OS\s0 X)) and, did I mention it, using it only for sockets. |
587 | .Sp |
596 | .Sp |
588 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR into an \f(CW\*(C`EVFILT_READ\*(C'\fR kevent with |
597 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR into an \f(CW\*(C`EVFILT_READ\*(C'\fR kevent with |
589 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR, and \f(CW\*(C`EV_WRITE\*(C'\fR into an \f(CW\*(C`EVFILT_WRITE\*(C'\fR kevent with |
598 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR, and \f(CW\*(C`EV_WRITE\*(C'\fR into an \f(CW\*(C`EVFILT_WRITE\*(C'\fR kevent with |
590 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR. |
599 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR. |
591 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
600 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
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732 | happily wraps around with enough iterations. |
741 | happily wraps around with enough iterations. |
733 | .Sp |
742 | .Sp |
734 | This value can sometimes be useful as a generation counter of sorts (it |
743 | This value can sometimes be useful as a generation counter of sorts (it |
735 | \&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with |
744 | \&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with |
736 | \&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls. |
745 | \&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls. |
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746 | .IP "unsigned int ev_loop_depth (loop)" 4 |
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747 | .IX Item "unsigned int ev_loop_depth (loop)" |
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748 | Returns the number of times \f(CW\*(C`ev_loop\*(C'\fR was entered minus the number of |
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749 | times \f(CW\*(C`ev_loop\*(C'\fR was exited, in other words, the recursion depth. |
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750 | .Sp |
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751 | Outside \f(CW\*(C`ev_loop\*(C'\fR, this number is zero. In a callback, this number is |
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752 | \&\f(CW1\fR, unless \f(CW\*(C`ev_loop\*(C'\fR was invoked recursively (or from another thread), |
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753 | in which case it is higher. |
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754 | .Sp |
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755 | Leaving \f(CW\*(C`ev_loop\*(C'\fR abnormally (setjmp/longjmp, cancelling the thread |
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756 | etc.), doesn't count as exit. |
737 | .IP "unsigned int ev_backend (loop)" 4 |
757 | .IP "unsigned int ev_backend (loop)" 4 |
738 | .IX Item "unsigned int ev_backend (loop)" |
758 | .IX Item "unsigned int ev_backend (loop)" |
739 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
759 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
740 | use. |
760 | use. |
741 | .IP "ev_tstamp ev_now (loop)" 4 |
761 | .IP "ev_tstamp ev_now (loop)" 4 |
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754 | This function is rarely useful, but when some event callback runs for a |
774 | This function is rarely useful, but when some event callback runs for a |
755 | very long time without entering the event loop, updating libev's idea of |
775 | very long time without entering the event loop, updating libev's idea of |
756 | the current time is a good idea. |
776 | the current time is a good idea. |
757 | .Sp |
777 | .Sp |
758 | See also \*(L"The special problem of time updates\*(R" in the \f(CW\*(C`ev_timer\*(C'\fR section. |
778 | See also \*(L"The special problem of time updates\*(R" in the \f(CW\*(C`ev_timer\*(C'\fR section. |
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779 | .IP "ev_suspend (loop)" 4 |
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780 | .IX Item "ev_suspend (loop)" |
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781 | .PD 0 |
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782 | .IP "ev_resume (loop)" 4 |
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783 | .IX Item "ev_resume (loop)" |
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784 | .PD |
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785 | These two functions suspend and resume a loop, for use when the loop is |
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786 | not used for a while and timeouts should not be processed. |
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787 | .Sp |
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788 | A typical use case would be an interactive program such as a game: When |
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789 | the user presses \f(CW\*(C`^Z\*(C'\fR to suspend the game and resumes it an hour later it |
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790 | would be best to handle timeouts as if no time had actually passed while |
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791 | the program was suspended. This can be achieved by calling \f(CW\*(C`ev_suspend\*(C'\fR |
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792 | in your \f(CW\*(C`SIGTSTP\*(C'\fR handler, sending yourself a \f(CW\*(C`SIGSTOP\*(C'\fR and calling |
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793 | \&\f(CW\*(C`ev_resume\*(C'\fR directly afterwards to resume timer processing. |
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794 | .Sp |
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795 | Effectively, all \f(CW\*(C`ev_timer\*(C'\fR watchers will be delayed by the time spend |
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796 | between \f(CW\*(C`ev_suspend\*(C'\fR and \f(CW\*(C`ev_resume\*(C'\fR, and all \f(CW\*(C`ev_periodic\*(C'\fR watchers |
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797 | will be rescheduled (that is, they will lose any events that would have |
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798 | occured while suspended). |
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799 | .Sp |
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800 | After calling \f(CW\*(C`ev_suspend\*(C'\fR you \fBmust not\fR call \fIany\fR function on the |
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801 | given loop other than \f(CW\*(C`ev_resume\*(C'\fR, and you \fBmust not\fR call \f(CW\*(C`ev_resume\*(C'\fR |
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802 | without a previous call to \f(CW\*(C`ev_suspend\*(C'\fR. |
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803 | .Sp |
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804 | Calling \f(CW\*(C`ev_suspend\*(C'\fR/\f(CW\*(C`ev_resume\*(C'\fR has the side effect of updating the |
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805 | event loop time (see \f(CW\*(C`ev_now_update\*(C'\fR). |
759 | .IP "ev_loop (loop, int flags)" 4 |
806 | .IP "ev_loop (loop, int flags)" 4 |
760 | .IX Item "ev_loop (loop, int flags)" |
807 | .IX Item "ev_loop (loop, int flags)" |
761 | Finally, this is it, the event handler. This function usually is called |
808 | Finally, this is it, the event handler. This function usually is called |
762 | after you initialised all your watchers and you want to start handling |
809 | after you initialised all your watchers and you want to start handling |
763 | events. |
810 | events. |
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850 | .Sp |
897 | .Sp |
851 | If you have a watcher you never unregister that should not keep \f(CW\*(C`ev_loop\*(C'\fR |
898 | If you have a watcher you never unregister that should not keep \f(CW\*(C`ev_loop\*(C'\fR |
852 | from returning, call \fIev_unref()\fR after starting, and \fIev_ref()\fR before |
899 | from returning, call \fIev_unref()\fR after starting, and \fIev_ref()\fR before |
853 | stopping it. |
900 | stopping it. |
854 | .Sp |
901 | .Sp |
855 | As an example, libev itself uses this for its internal signal pipe: It is |
902 | As an example, libev itself uses this for its internal signal pipe: It |
856 | not visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting |
903 | is not visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from |
857 | if no event watchers registered by it are active. It is also an excellent |
904 | exiting if no event watchers registered by it are active. It is also an |
858 | way to do this for generic recurring timers or from within third-party |
905 | excellent way to do this for generic recurring timers or from within |
859 | libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR |
906 | third-party libraries. Just remember to \fIunref after start\fR and \fIref |
860 | (but only if the watcher wasn't active before, or was active before, |
907 | before stop\fR (but only if the watcher wasn't active before, or was active |
861 | respectively). |
908 | before, respectively. Note also that libev might stop watchers itself |
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909 | (e.g. non-repeating timers) in which case you have to \f(CW\*(C`ev_ref\*(C'\fR |
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|
910 | in the callback). |
862 | .Sp |
911 | .Sp |
863 | Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR |
912 | Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR |
864 | running when nothing else is active. |
913 | running when nothing else is active. |
865 | .Sp |
914 | .Sp |
866 | .Vb 4 |
915 | .Vb 4 |
… | |
… | |
900 | .Sp |
949 | .Sp |
901 | By setting a higher \fIio collect interval\fR you allow libev to spend more |
950 | By setting a higher \fIio collect interval\fR you allow libev to spend more |
902 | time collecting I/O events, so you can handle more events per iteration, |
951 | time collecting I/O events, so you can handle more events per iteration, |
903 | at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and |
952 | at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and |
904 | \&\f(CW\*(C`ev_timer\*(C'\fR) will be not affected. Setting this to a non-null value will |
953 | \&\f(CW\*(C`ev_timer\*(C'\fR) will be not affected. Setting this to a non-null value will |
905 | introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. |
954 | introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. The |
|
|
955 | sleep time ensures that libev will not poll for I/O events more often then |
|
|
956 | once per this interval, on average. |
906 | .Sp |
957 | .Sp |
907 | Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
958 | Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
908 | to spend more time collecting timeouts, at the expense of increased |
959 | to spend more time collecting timeouts, at the expense of increased |
909 | latency/jitter/inexactness (the watcher callback will be called |
960 | latency/jitter/inexactness (the watcher callback will be called |
910 | later). \f(CW\*(C`ev_io\*(C'\fR watchers will not be affected. Setting this to a non-null |
961 | later). \f(CW\*(C`ev_io\*(C'\fR watchers will not be affected. Setting this to a non-null |
… | |
… | |
912 | .Sp |
963 | .Sp |
913 | Many (busy) programs can usually benefit by setting the I/O collect |
964 | Many (busy) programs can usually benefit by setting the I/O collect |
914 | interval to a value near \f(CW0.1\fR or so, which is often enough for |
965 | interval to a value near \f(CW0.1\fR or so, which is often enough for |
915 | interactive servers (of course not for games), likewise for timeouts. It |
966 | interactive servers (of course not for games), likewise for timeouts. It |
916 | usually doesn't make much sense to set it to a lower value than \f(CW0.01\fR, |
967 | usually doesn't make much sense to set it to a lower value than \f(CW0.01\fR, |
917 | as this approaches the timing granularity of most systems. |
968 | as this approaches the timing granularity of most systems. Note that if |
|
|
969 | you do transactions with the outside world and you can't increase the |
|
|
970 | parallelity, then this setting will limit your transaction rate (if you |
|
|
971 | need to poll once per transaction and the I/O collect interval is 0.01, |
|
|
972 | then you can't do more than 100 transations per second). |
918 | .Sp |
973 | .Sp |
919 | Setting the \fItimeout collect interval\fR can improve the opportunity for |
974 | Setting the \fItimeout collect interval\fR can improve the opportunity for |
920 | saving power, as the program will \*(L"bundle\*(R" timer callback invocations that |
975 | saving power, as the program will \*(L"bundle\*(R" timer callback invocations that |
921 | are \*(L"near\*(R" in time together, by delaying some, thus reducing the number of |
976 | are \*(L"near\*(R" in time together, by delaying some, thus reducing the number of |
922 | times the process sleeps and wakes up again. Another useful technique to |
977 | times the process sleeps and wakes up again. Another useful technique to |
923 | reduce iterations/wake\-ups is to use \f(CW\*(C`ev_periodic\*(C'\fR watchers and make sure |
978 | reduce iterations/wake\-ups is to use \f(CW\*(C`ev_periodic\*(C'\fR watchers and make sure |
924 | they fire on, say, one-second boundaries only. |
979 | they fire on, say, one-second boundaries only. |
|
|
980 | .Sp |
|
|
981 | Example: we only need 0.1s timeout granularity, and we wish not to poll |
|
|
982 | more often than 100 times per second: |
|
|
983 | .Sp |
|
|
984 | .Vb 2 |
|
|
985 | \& ev_set_timeout_collect_interval (EV_DEFAULT_UC_ 0.1); |
|
|
986 | \& ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
|
|
987 | .Ve |
|
|
988 | .IP "ev_invoke_pending (loop)" 4 |
|
|
989 | .IX Item "ev_invoke_pending (loop)" |
|
|
990 | This call will simply invoke all pending watchers while resetting their |
|
|
991 | pending state. Normally, \f(CW\*(C`ev_loop\*(C'\fR does this automatically when required, |
|
|
992 | but when overriding the invoke callback this call comes handy. |
|
|
993 | .IP "int ev_pending_count (loop)" 4 |
|
|
994 | .IX Item "int ev_pending_count (loop)" |
|
|
995 | Returns the number of pending watchers \- zero indicates that no watchers |
|
|
996 | are pending. |
|
|
997 | .IP "ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(\s-1EV_P\s0))" 4 |
|
|
998 | .IX Item "ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))" |
|
|
999 | This overrides the invoke pending functionality of the loop: Instead of |
|
|
1000 | invoking all pending watchers when there are any, \f(CW\*(C`ev_loop\*(C'\fR will call |
|
|
1001 | this callback instead. This is useful, for example, when you want to |
|
|
1002 | invoke the actual watchers inside another context (another thread etc.). |
|
|
1003 | .Sp |
|
|
1004 | If you want to reset the callback, use \f(CW\*(C`ev_invoke_pending\*(C'\fR as new |
|
|
1005 | callback. |
|
|
1006 | .IP "ev_set_loop_release_cb (loop, void (*release)(\s-1EV_P\s0), void (*acquire)(\s-1EV_P\s0))" 4 |
|
|
1007 | .IX Item "ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P))" |
|
|
1008 | Sometimes you want to share the same loop between multiple threads. This |
|
|
1009 | can be done relatively simply by putting mutex_lock/unlock calls around |
|
|
1010 | each call to a libev function. |
|
|
1011 | .Sp |
|
|
1012 | However, \f(CW\*(C`ev_loop\*(C'\fR can run an indefinite time, so it is not feasible to |
|
|
1013 | wait for it to return. One way around this is to wake up the loop via |
|
|
1014 | \&\f(CW\*(C`ev_unloop\*(C'\fR and \f(CW\*(C`av_async_send\*(C'\fR, another way is to set these \fIrelease\fR |
|
|
1015 | and \fIacquire\fR callbacks on the loop. |
|
|
1016 | .Sp |
|
|
1017 | When set, then \f(CW\*(C`release\*(C'\fR will be called just before the thread is |
|
|
1018 | suspended waiting for new events, and \f(CW\*(C`acquire\*(C'\fR is called just |
|
|
1019 | afterwards. |
|
|
1020 | .Sp |
|
|
1021 | Ideally, \f(CW\*(C`release\*(C'\fR will just call your mutex_unlock function, and |
|
|
1022 | \&\f(CW\*(C`acquire\*(C'\fR will just call the mutex_lock function again. |
|
|
1023 | .Sp |
|
|
1024 | While event loop modifications are allowed between invocations of |
|
|
1025 | \&\f(CW\*(C`release\*(C'\fR and \f(CW\*(C`acquire\*(C'\fR (that's their only purpose after all), no |
|
|
1026 | modifications done will affect the event loop, i.e. adding watchers will |
|
|
1027 | have no effect on the set of file descriptors being watched, or the time |
|
|
1028 | waited. USe an \f(CW\*(C`ev_async\*(C'\fR watcher to wake up \f(CW\*(C`ev_loop\*(C'\fR when you want it |
|
|
1029 | to take note of any changes you made. |
|
|
1030 | .Sp |
|
|
1031 | In theory, threads executing \f(CW\*(C`ev_loop\*(C'\fR will be async-cancel safe between |
|
|
1032 | invocations of \f(CW\*(C`release\*(C'\fR and \f(CW\*(C`acquire\*(C'\fR. |
|
|
1033 | .Sp |
|
|
1034 | See also the locking example in the \f(CW\*(C`THREADS\*(C'\fR section later in this |
|
|
1035 | document. |
|
|
1036 | .IP "ev_set_userdata (loop, void *data)" 4 |
|
|
1037 | .IX Item "ev_set_userdata (loop, void *data)" |
|
|
1038 | .PD 0 |
|
|
1039 | .IP "ev_userdata (loop)" 4 |
|
|
1040 | .IX Item "ev_userdata (loop)" |
|
|
1041 | .PD |
|
|
1042 | Set and retrieve a single \f(CW\*(C`void *\*(C'\fR associated with a loop. When |
|
|
1043 | \&\f(CW\*(C`ev_set_userdata\*(C'\fR has never been called, then \f(CW\*(C`ev_userdata\*(C'\fR returns |
|
|
1044 | \&\f(CW0.\fR |
|
|
1045 | .Sp |
|
|
1046 | These two functions can be used to associate arbitrary data with a loop, |
|
|
1047 | and are intended solely for the \f(CW\*(C`invoke_pending_cb\*(C'\fR, \f(CW\*(C`release\*(C'\fR and |
|
|
1048 | \&\f(CW\*(C`acquire\*(C'\fR callbacks described above, but of course can be (ab\-)used for |
|
|
1049 | any other purpose as well. |
925 | .IP "ev_loop_verify (loop)" 4 |
1050 | .IP "ev_loop_verify (loop)" 4 |
926 | .IX Item "ev_loop_verify (loop)" |
1051 | .IX Item "ev_loop_verify (loop)" |
927 | This function only does something when \f(CW\*(C`EV_VERIFY\*(C'\fR support has been |
1052 | This function only does something when \f(CW\*(C`EV_VERIFY\*(C'\fR support has been |
928 | compiled in, which is the default for non-minimal builds. It tries to go |
1053 | compiled in, which is the default for non-minimal builds. It tries to go |
929 | through all internal structures and checks them for validity. If anything |
1054 | through all internal structures and checks them for validity. If anything |
… | |
… | |
1054 | \&\f(CW\*(C`ev_fork\*(C'\fR). |
1179 | \&\f(CW\*(C`ev_fork\*(C'\fR). |
1055 | .ie n .IP """EV_ASYNC""" 4 |
1180 | .ie n .IP """EV_ASYNC""" 4 |
1056 | .el .IP "\f(CWEV_ASYNC\fR" 4 |
1181 | .el .IP "\f(CWEV_ASYNC\fR" 4 |
1057 | .IX Item "EV_ASYNC" |
1182 | .IX Item "EV_ASYNC" |
1058 | The given async watcher has been asynchronously notified (see \f(CW\*(C`ev_async\*(C'\fR). |
1183 | The given async watcher has been asynchronously notified (see \f(CW\*(C`ev_async\*(C'\fR). |
|
|
1184 | .ie n .IP """EV_CUSTOM""" 4 |
|
|
1185 | .el .IP "\f(CWEV_CUSTOM\fR" 4 |
|
|
1186 | .IX Item "EV_CUSTOM" |
|
|
1187 | Not ever sent (or otherwise used) by libev itself, but can be freely used |
|
|
1188 | by libev users to signal watchers (e.g. via \f(CW\*(C`ev_feed_event\*(C'\fR). |
1059 | .ie n .IP """EV_ERROR""" 4 |
1189 | .ie n .IP """EV_ERROR""" 4 |
1060 | .el .IP "\f(CWEV_ERROR\fR" 4 |
1190 | .el .IP "\f(CWEV_ERROR\fR" 4 |
1061 | .IX Item "EV_ERROR" |
1191 | .IX Item "EV_ERROR" |
1062 | An unspecified error has occurred, the watcher has been stopped. This might |
1192 | An unspecified error has occurred, the watcher has been stopped. This might |
1063 | happen because the watcher could not be properly started because libev |
1193 | happen because the watcher could not be properly started because libev |
… | |
… | |
1073 | example it might indicate that a fd is readable or writable, and if your |
1203 | example it might indicate that a fd is readable or writable, and if your |
1074 | callbacks is well-written it can just attempt the operation and cope with |
1204 | callbacks is well-written it can just attempt the operation and cope with |
1075 | the error from \fIread()\fR or \fIwrite()\fR. This will not work in multi-threaded |
1205 | the error from \fIread()\fR or \fIwrite()\fR. This will not work in multi-threaded |
1076 | programs, though, as the fd could already be closed and reused for another |
1206 | programs, though, as the fd could already be closed and reused for another |
1077 | thing, so beware. |
1207 | thing, so beware. |
1078 | .Sh "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" |
1208 | .SS "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" |
1079 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1209 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1080 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
1210 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
1081 | .el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 |
1211 | .el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 |
1082 | .IX Item "ev_init (ev_TYPE *watcher, callback)" |
1212 | .IX Item "ev_init (ev_TYPE *watcher, callback)" |
1083 | This macro initialises the generic portion of a watcher. The contents |
1213 | This macro initialises the generic portion of a watcher. The contents |
… | |
… | |
1178 | integer between \f(CW\*(C`EV_MAXPRI\*(C'\fR (default: \f(CW2\fR) and \f(CW\*(C`EV_MINPRI\*(C'\fR |
1308 | integer between \f(CW\*(C`EV_MAXPRI\*(C'\fR (default: \f(CW2\fR) and \f(CW\*(C`EV_MINPRI\*(C'\fR |
1179 | (default: \f(CW\*(C`\-2\*(C'\fR). Pending watchers with higher priority will be invoked |
1309 | (default: \f(CW\*(C`\-2\*(C'\fR). Pending watchers with higher priority will be invoked |
1180 | before watchers with lower priority, but priority will not keep watchers |
1310 | before watchers with lower priority, but priority will not keep watchers |
1181 | from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers). |
1311 | from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers). |
1182 | .Sp |
1312 | .Sp |
1183 | This means that priorities are \fIonly\fR used for ordering callback |
|
|
1184 | invocation after new events have been received. This is useful, for |
|
|
1185 | example, to reduce latency after idling, or more often, to bind two |
|
|
1186 | watchers on the same event and make sure one is called first. |
|
|
1187 | .Sp |
|
|
1188 | If you need to suppress invocation when higher priority events are pending |
1313 | If you need to suppress invocation when higher priority events are pending |
1189 | you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality. |
1314 | you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality. |
1190 | .Sp |
1315 | .Sp |
1191 | You \fImust not\fR change the priority of a watcher as long as it is active or |
1316 | You \fImust not\fR change the priority of a watcher as long as it is active or |
1192 | pending. |
1317 | pending. |
1193 | .Sp |
|
|
1194 | The default priority used by watchers when no priority has been set is |
|
|
1195 | always \f(CW0\fR, which is supposed to not be too high and not be too low :). |
|
|
1196 | .Sp |
1318 | .Sp |
1197 | Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is |
1319 | Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is |
1198 | fine, as long as you do not mind that the priority value you query might |
1320 | fine, as long as you do not mind that the priority value you query might |
1199 | or might not have been clamped to the valid range. |
1321 | or might not have been clamped to the valid range. |
|
|
1322 | .Sp |
|
|
1323 | The default priority used by watchers when no priority has been set is |
|
|
1324 | always \f(CW0\fR, which is supposed to not be too high and not be too low :). |
|
|
1325 | .Sp |
|
|
1326 | See \*(L"\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0\*(R", below, for a more thorough treatment of |
|
|
1327 | priorities. |
1200 | .IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 |
1328 | .IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 |
1201 | .IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" |
1329 | .IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" |
1202 | 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 |
1330 | 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 |
1203 | \&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback |
1331 | \&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback |
1204 | can deal with that fact, as both are simply passed through to the |
1332 | can deal with that fact, as both are simply passed through to the |
… | |
… | |
1209 | returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the |
1337 | returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the |
1210 | watcher isn't pending it does nothing and returns \f(CW0\fR. |
1338 | watcher isn't pending it does nothing and returns \f(CW0\fR. |
1211 | .Sp |
1339 | .Sp |
1212 | Sometimes it can be useful to \*(L"poll\*(R" a watcher instead of waiting for its |
1340 | Sometimes it can be useful to \*(L"poll\*(R" a watcher instead of waiting for its |
1213 | callback to be invoked, which can be accomplished with this function. |
1341 | callback to be invoked, which can be accomplished with this function. |
1214 | .Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
1342 | .SS "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
1215 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
1343 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
1216 | Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change |
1344 | Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change |
1217 | and read at any time: libev will completely ignore it. This can be used |
1345 | and read at any time: libev will completely ignore it. This can be used |
1218 | to associate arbitrary data with your watcher. If you need more data and |
1346 | to associate arbitrary data with your watcher. If you need more data and |
1219 | don't want to allocate memory and store a pointer to it in that data |
1347 | don't want to allocate memory and store a pointer to it in that data |
… | |
… | |
1270 | \& #include <stddef.h> |
1398 | \& #include <stddef.h> |
1271 | \& |
1399 | \& |
1272 | \& static void |
1400 | \& static void |
1273 | \& t1_cb (EV_P_ ev_timer *w, int revents) |
1401 | \& t1_cb (EV_P_ ev_timer *w, int revents) |
1274 | \& { |
1402 | \& { |
1275 | \& struct my_biggy big = (struct my_biggy * |
1403 | \& struct my_biggy big = (struct my_biggy *) |
1276 | \& (((char *)w) \- offsetof (struct my_biggy, t1)); |
1404 | \& (((char *)w) \- offsetof (struct my_biggy, t1)); |
1277 | \& } |
1405 | \& } |
1278 | \& |
1406 | \& |
1279 | \& static void |
1407 | \& static void |
1280 | \& t2_cb (EV_P_ ev_timer *w, int revents) |
1408 | \& t2_cb (EV_P_ ev_timer *w, int revents) |
1281 | \& { |
1409 | \& { |
1282 | \& struct my_biggy big = (struct my_biggy * |
1410 | \& struct my_biggy big = (struct my_biggy *) |
1283 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
1411 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
1284 | \& } |
1412 | \& } |
1285 | .Ve |
1413 | .Ve |
|
|
1414 | .SS "\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0" |
|
|
1415 | .IX Subsection "WATCHER PRIORITY MODELS" |
|
|
1416 | Many event loops support \fIwatcher priorities\fR, which are usually small |
|
|
1417 | integers that influence the ordering of event callback invocation |
|
|
1418 | between watchers in some way, all else being equal. |
|
|
1419 | .PP |
|
|
1420 | In libev, Watcher priorities can be set using \f(CW\*(C`ev_set_priority\*(C'\fR. See its |
|
|
1421 | description for the more technical details such as the actual priority |
|
|
1422 | range. |
|
|
1423 | .PP |
|
|
1424 | There are two common ways how these these priorities are being interpreted |
|
|
1425 | by event loops: |
|
|
1426 | .PP |
|
|
1427 | In the more common lock-out model, higher priorities \*(L"lock out\*(R" invocation |
|
|
1428 | of lower priority watchers, which means as long as higher priority |
|
|
1429 | watchers receive events, lower priority watchers are not being invoked. |
|
|
1430 | .PP |
|
|
1431 | The less common only-for-ordering model uses priorities solely to order |
|
|
1432 | callback invocation within a single event loop iteration: Higher priority |
|
|
1433 | watchers are invoked before lower priority ones, but they all get invoked |
|
|
1434 | before polling for new events. |
|
|
1435 | .PP |
|
|
1436 | Libev uses the second (only-for-ordering) model for all its watchers |
|
|
1437 | except for idle watchers (which use the lock-out model). |
|
|
1438 | .PP |
|
|
1439 | The rationale behind this is that implementing the lock-out model for |
|
|
1440 | watchers is not well supported by most kernel interfaces, and most event |
|
|
1441 | libraries will just poll for the same events again and again as long as |
|
|
1442 | their callbacks have not been executed, which is very inefficient in the |
|
|
1443 | common case of one high-priority watcher locking out a mass of lower |
|
|
1444 | priority ones. |
|
|
1445 | .PP |
|
|
1446 | Static (ordering) priorities are most useful when you have two or more |
|
|
1447 | watchers handling the same resource: a typical usage example is having an |
|
|
1448 | \&\f(CW\*(C`ev_io\*(C'\fR watcher to receive data, and an associated \f(CW\*(C`ev_timer\*(C'\fR to handle |
|
|
1449 | timeouts. Under load, data might be received while the program handles |
|
|
1450 | other jobs, but since timers normally get invoked first, the timeout |
|
|
1451 | handler will be executed before checking for data. In that case, giving |
|
|
1452 | the timer a lower priority than the I/O watcher ensures that I/O will be |
|
|
1453 | handled first even under adverse conditions (which is usually, but not |
|
|
1454 | always, what you want). |
|
|
1455 | .PP |
|
|
1456 | Since idle watchers use the \*(L"lock-out\*(R" model, meaning that idle watchers |
|
|
1457 | will only be executed when no same or higher priority watchers have |
|
|
1458 | received events, they can be used to implement the \*(L"lock-out\*(R" model when |
|
|
1459 | required. |
|
|
1460 | .PP |
|
|
1461 | For example, to emulate how many other event libraries handle priorities, |
|
|
1462 | you can associate an \f(CW\*(C`ev_idle\*(C'\fR watcher to each such watcher, and in |
|
|
1463 | the normal watcher callback, you just start the idle watcher. The real |
|
|
1464 | processing is done in the idle watcher callback. This causes libev to |
|
|
1465 | continously poll and process kernel event data for the watcher, but when |
|
|
1466 | the lock-out case is known to be rare (which in turn is rare :), this is |
|
|
1467 | workable. |
|
|
1468 | .PP |
|
|
1469 | Usually, however, the lock-out model implemented that way will perform |
|
|
1470 | miserably under the type of load it was designed to handle. In that case, |
|
|
1471 | it might be preferable to stop the real watcher before starting the |
|
|
1472 | idle watcher, so the kernel will not have to process the event in case |
|
|
1473 | the actual processing will be delayed for considerable time. |
|
|
1474 | .PP |
|
|
1475 | Here is an example of an I/O watcher that should run at a strictly lower |
|
|
1476 | priority than the default, and which should only process data when no |
|
|
1477 | other events are pending: |
|
|
1478 | .PP |
|
|
1479 | .Vb 2 |
|
|
1480 | \& ev_idle idle; // actual processing watcher |
|
|
1481 | \& ev_io io; // actual event watcher |
|
|
1482 | \& |
|
|
1483 | \& static void |
|
|
1484 | \& io_cb (EV_P_ ev_io *w, int revents) |
|
|
1485 | \& { |
|
|
1486 | \& // stop the I/O watcher, we received the event, but |
|
|
1487 | \& // are not yet ready to handle it. |
|
|
1488 | \& ev_io_stop (EV_A_ w); |
|
|
1489 | \& |
|
|
1490 | \& // start the idle watcher to ahndle the actual event. |
|
|
1491 | \& // it will not be executed as long as other watchers |
|
|
1492 | \& // with the default priority are receiving events. |
|
|
1493 | \& ev_idle_start (EV_A_ &idle); |
|
|
1494 | \& } |
|
|
1495 | \& |
|
|
1496 | \& static void |
|
|
1497 | \& idle_cb (EV_P_ ev_idle *w, int revents) |
|
|
1498 | \& { |
|
|
1499 | \& // actual processing |
|
|
1500 | \& read (STDIN_FILENO, ...); |
|
|
1501 | \& |
|
|
1502 | \& // have to start the I/O watcher again, as |
|
|
1503 | \& // we have handled the event |
|
|
1504 | \& ev_io_start (EV_P_ &io); |
|
|
1505 | \& } |
|
|
1506 | \& |
|
|
1507 | \& // initialisation |
|
|
1508 | \& ev_idle_init (&idle, idle_cb); |
|
|
1509 | \& ev_io_init (&io, io_cb, STDIN_FILENO, EV_READ); |
|
|
1510 | \& ev_io_start (EV_DEFAULT_ &io); |
|
|
1511 | .Ve |
|
|
1512 | .PP |
|
|
1513 | In the \*(L"real\*(R" world, it might also be beneficial to start a timer, so that |
|
|
1514 | low-priority connections can not be locked out forever under load. This |
|
|
1515 | enables your program to keep a lower latency for important connections |
|
|
1516 | during short periods of high load, while not completely locking out less |
|
|
1517 | important ones. |
1286 | .SH "WATCHER TYPES" |
1518 | .SH "WATCHER TYPES" |
1287 | .IX Header "WATCHER TYPES" |
1519 | .IX Header "WATCHER TYPES" |
1288 | This section describes each watcher in detail, but will not repeat |
1520 | This section describes each watcher in detail, but will not repeat |
1289 | information given in the last section. Any initialisation/set macros, |
1521 | information given in the last section. Any initialisation/set macros, |
1290 | functions and members specific to the watcher type are explained. |
1522 | functions and members specific to the watcher type are explained. |
… | |
… | |
1295 | watcher is stopped to your hearts content), or \fI[read\-write]\fR, which |
1527 | watcher is stopped to your hearts content), or \fI[read\-write]\fR, which |
1296 | means you can expect it to have some sensible content while the watcher |
1528 | means you can expect it to have some sensible content while the watcher |
1297 | is active, but you can also modify it. Modifying it may not do something |
1529 | is active, but you can also modify it. Modifying it may not do something |
1298 | sensible or take immediate effect (or do anything at all), but libev will |
1530 | sensible or take immediate effect (or do anything at all), but libev will |
1299 | not crash or malfunction in any way. |
1531 | not crash or malfunction in any way. |
1300 | .ie n .Sh """ev_io"" \- is this file descriptor readable or writable?" |
1532 | .ie n .SS """ev_io"" \- is this file descriptor readable or writable?" |
1301 | .el .Sh "\f(CWev_io\fP \- is this file descriptor readable or writable?" |
1533 | .el .SS "\f(CWev_io\fP \- is this file descriptor readable or writable?" |
1302 | .IX Subsection "ev_io - is this file descriptor readable or writable?" |
1534 | .IX Subsection "ev_io - is this file descriptor readable or writable?" |
1303 | I/O watchers check whether a file descriptor is readable or writable |
1535 | I/O watchers check whether a file descriptor is readable or writable |
1304 | in each iteration of the event loop, or, more precisely, when reading |
1536 | in each iteration of the event loop, or, more precisely, when reading |
1305 | would not block the process and writing would at least be able to write |
1537 | would not block the process and writing would at least be able to write |
1306 | some data. This behaviour is called level-triggering because you keep |
1538 | some data. This behaviour is called level-triggering because you keep |
… | |
… | |
1313 | descriptors to non-blocking mode is also usually a good idea (but not |
1545 | descriptors to non-blocking mode is also usually a good idea (but not |
1314 | required if you know what you are doing). |
1546 | required if you know what you are doing). |
1315 | .PP |
1547 | .PP |
1316 | If you cannot use non-blocking mode, then force the use of a |
1548 | If you cannot use non-blocking mode, then force the use of a |
1317 | known-to-be-good backend (at the time of this writing, this includes only |
1549 | known-to-be-good backend (at the time of this writing, this includes only |
1318 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and \f(CW\*(C`EVBACKEND_POLL\*(C'\fR). |
1550 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and \f(CW\*(C`EVBACKEND_POLL\*(C'\fR). The same applies to file |
|
|
1551 | descriptors for which non-blocking operation makes no sense (such as |
|
|
1552 | files) \- libev doesn't guarentee any specific behaviour in that case. |
1319 | .PP |
1553 | .PP |
1320 | Another thing you have to watch out for is that it is quite easy to |
1554 | Another thing you have to watch out for is that it is quite easy to |
1321 | receive \*(L"spurious\*(R" readiness notifications, that is your callback might |
1555 | receive \*(L"spurious\*(R" readiness notifications, that is your callback might |
1322 | be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block |
1556 | be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block |
1323 | because there is no data. Not only are some backends known to create a |
1557 | because there is no data. Not only are some backends known to create a |
… | |
… | |
1432 | \& ev_io stdin_readable; |
1666 | \& ev_io stdin_readable; |
1433 | \& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1667 | \& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1434 | \& ev_io_start (loop, &stdin_readable); |
1668 | \& ev_io_start (loop, &stdin_readable); |
1435 | \& ev_loop (loop, 0); |
1669 | \& ev_loop (loop, 0); |
1436 | .Ve |
1670 | .Ve |
1437 | .ie n .Sh """ev_timer"" \- relative and optionally repeating timeouts" |
1671 | .ie n .SS """ev_timer"" \- relative and optionally repeating timeouts" |
1438 | .el .Sh "\f(CWev_timer\fP \- relative and optionally repeating timeouts" |
1672 | .el .SS "\f(CWev_timer\fP \- relative and optionally repeating timeouts" |
1439 | .IX Subsection "ev_timer - relative and optionally repeating timeouts" |
1673 | .IX Subsection "ev_timer - relative and optionally repeating timeouts" |
1440 | Timer watchers are simple relative timers that generate an event after a |
1674 | Timer watchers are simple relative timers that generate an event after a |
1441 | given time, and optionally repeating in regular intervals after that. |
1675 | given time, and optionally repeating in regular intervals after that. |
1442 | .PP |
1676 | .PP |
1443 | The timers are based on real time, that is, if you register an event that |
1677 | The timers are based on real time, that is, if you register an event that |
… | |
… | |
1445 | year, it will still time out after (roughly) one hour. \*(L"Roughly\*(R" because |
1679 | year, it will still time out after (roughly) one hour. \*(L"Roughly\*(R" because |
1446 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1680 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1447 | monotonic clock option helps a lot here). |
1681 | monotonic clock option helps a lot here). |
1448 | .PP |
1682 | .PP |
1449 | The callback is guaranteed to be invoked only \fIafter\fR its timeout has |
1683 | The callback is guaranteed to be invoked only \fIafter\fR its timeout has |
1450 | passed, but if multiple timers become ready during the same loop iteration |
1684 | passed (not \fIat\fR, so on systems with very low-resolution clocks this |
1451 | then order of execution is undefined. |
1685 | might introduce a small delay). If multiple timers become ready during the |
|
|
1686 | same loop iteration then the ones with earlier time-out values are invoked |
|
|
1687 | before ones of the same priority with later time-out values (but this is |
|
|
1688 | no longer true when a callback calls \f(CW\*(C`ev_loop\*(C'\fR recursively). |
1452 | .PP |
1689 | .PP |
1453 | \fIBe smart about timeouts\fR |
1690 | \fIBe smart about timeouts\fR |
1454 | .IX Subsection "Be smart about timeouts" |
1691 | .IX Subsection "Be smart about timeouts" |
1455 | .PP |
1692 | .PP |
1456 | Many real-world problems involve some kind of timeout, usually for error |
1693 | Many real-world problems involve some kind of timeout, usually for error |
… | |
… | |
1503 | member and \f(CW\*(C`ev_timer_again\*(C'\fR. |
1740 | member and \f(CW\*(C`ev_timer_again\*(C'\fR. |
1504 | .Sp |
1741 | .Sp |
1505 | At start: |
1742 | At start: |
1506 | .Sp |
1743 | .Sp |
1507 | .Vb 3 |
1744 | .Vb 3 |
1508 | \& ev_timer_init (timer, callback); |
1745 | \& ev_init (timer, callback); |
1509 | \& timer\->repeat = 60.; |
1746 | \& timer\->repeat = 60.; |
1510 | \& ev_timer_again (loop, timer); |
1747 | \& ev_timer_again (loop, timer); |
1511 | .Ve |
1748 | .Ve |
1512 | .Sp |
1749 | .Sp |
1513 | Each time there is some activity: |
1750 | Each time there is some activity: |
… | |
… | |
1557 | \& else |
1794 | \& else |
1558 | \& { |
1795 | \& { |
1559 | \& // callback was invoked, but there was some activity, re\-arm |
1796 | \& // callback was invoked, but there was some activity, re\-arm |
1560 | \& // the watcher to fire in last_activity + 60, which is |
1797 | \& // the watcher to fire in last_activity + 60, which is |
1561 | \& // guaranteed to be in the future, so "again" is positive: |
1798 | \& // guaranteed to be in the future, so "again" is positive: |
1562 | \& w\->again = timeout \- now; |
1799 | \& w\->repeat = timeout \- now; |
1563 | \& ev_timer_again (EV_A_ w); |
1800 | \& ev_timer_again (EV_A_ w); |
1564 | \& } |
1801 | \& } |
1565 | \& } |
1802 | \& } |
1566 | .Ve |
1803 | .Ve |
1567 | .Sp |
1804 | .Sp |
… | |
… | |
1582 | To start the timer, simply initialise the watcher and set \f(CW\*(C`last_activity\*(C'\fR |
1819 | To start the timer, simply initialise the watcher and set \f(CW\*(C`last_activity\*(C'\fR |
1583 | to the current time (meaning we just have some activity :), then call the |
1820 | to the current time (meaning we just have some activity :), then call the |
1584 | callback, which will \*(L"do the right thing\*(R" and start the timer: |
1821 | callback, which will \*(L"do the right thing\*(R" and start the timer: |
1585 | .Sp |
1822 | .Sp |
1586 | .Vb 3 |
1823 | .Vb 3 |
1587 | \& ev_timer_init (timer, callback); |
1824 | \& ev_init (timer, callback); |
1588 | \& last_activity = ev_now (loop); |
1825 | \& last_activity = ev_now (loop); |
1589 | \& callback (loop, timer, EV_TIMEOUT); |
1826 | \& callback (loop, timer, EV_TIMEOUT); |
1590 | .Ve |
1827 | .Ve |
1591 | .Sp |
1828 | .Sp |
1592 | And when there is some activity, simply store the current time in |
1829 | And when there is some activity, simply store the current time in |
… | |
… | |
1655 | .Ve |
1892 | .Ve |
1656 | .PP |
1893 | .PP |
1657 | If the event loop is suspended for a long time, you can also force an |
1894 | If the event loop is suspended for a long time, you can also force an |
1658 | update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update |
1895 | update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update |
1659 | ()\*(C'\fR. |
1896 | ()\*(C'\fR. |
|
|
1897 | .PP |
|
|
1898 | \fIThe special problems of suspended animation\fR |
|
|
1899 | .IX Subsection "The special problems of suspended animation" |
|
|
1900 | .PP |
|
|
1901 | When you leave the server world it is quite customary to hit machines that |
|
|
1902 | can suspend/hibernate \- what happens to the clocks during such a suspend? |
|
|
1903 | .PP |
|
|
1904 | Some quick tests made with a Linux 2.6.28 indicate that a suspend freezes |
|
|
1905 | all processes, while the clocks (\f(CW\*(C`times\*(C'\fR, \f(CW\*(C`CLOCK_MONOTONIC\*(C'\fR) continue |
|
|
1906 | to run until the system is suspended, but they will not advance while the |
|
|
1907 | system is suspended. That means, on resume, it will be as if the program |
|
|
1908 | was frozen for a few seconds, but the suspend time will not be counted |
|
|
1909 | towards \f(CW\*(C`ev_timer\*(C'\fR when a monotonic clock source is used. The real time |
|
|
1910 | clock advanced as expected, but if it is used as sole clocksource, then a |
|
|
1911 | long suspend would be detected as a time jump by libev, and timers would |
|
|
1912 | be adjusted accordingly. |
|
|
1913 | .PP |
|
|
1914 | I would not be surprised to see different behaviour in different between |
|
|
1915 | operating systems, \s-1OS\s0 versions or even different hardware. |
|
|
1916 | .PP |
|
|
1917 | The other form of suspend (job control, or sending a \s-1SIGSTOP\s0) will see a |
|
|
1918 | time jump in the monotonic clocks and the realtime clock. If the program |
|
|
1919 | is suspended for a very long time, and monotonic clock sources are in use, |
|
|
1920 | then you can expect \f(CW\*(C`ev_timer\*(C'\fRs to expire as the full suspension time |
|
|
1921 | will be counted towards the timers. When no monotonic clock source is in |
|
|
1922 | use, then libev will again assume a timejump and adjust accordingly. |
|
|
1923 | .PP |
|
|
1924 | It might be beneficial for this latter case to call \f(CW\*(C`ev_suspend\*(C'\fR |
|
|
1925 | and \f(CW\*(C`ev_resume\*(C'\fR in code that handles \f(CW\*(C`SIGTSTP\*(C'\fR, to at least get |
|
|
1926 | deterministic behaviour in this case (you can do nothing against |
|
|
1927 | \&\f(CW\*(C`SIGSTOP\*(C'\fR). |
1660 | .PP |
1928 | .PP |
1661 | \fIWatcher-Specific Functions and Data Members\fR |
1929 | \fIWatcher-Specific Functions and Data Members\fR |
1662 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1930 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1663 | .IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 |
1931 | .IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 |
1664 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
1932 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
… | |
… | |
1689 | If the timer is repeating, either start it if necessary (with the |
1957 | If the timer is repeating, either start it if necessary (with the |
1690 | \&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value. |
1958 | \&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value. |
1691 | .Sp |
1959 | .Sp |
1692 | This sounds a bit complicated, see \*(L"Be smart about timeouts\*(R", above, for a |
1960 | This sounds a bit complicated, see \*(L"Be smart about timeouts\*(R", above, for a |
1693 | usage example. |
1961 | usage example. |
|
|
1962 | .IP "ev_timer_remaining (loop, ev_timer *)" 4 |
|
|
1963 | .IX Item "ev_timer_remaining (loop, ev_timer *)" |
|
|
1964 | Returns the remaining time until a timer fires. If the timer is active, |
|
|
1965 | then this time is relative to the current event loop time, otherwise it's |
|
|
1966 | the timeout value currently configured. |
|
|
1967 | .Sp |
|
|
1968 | That is, after an \f(CW\*(C`ev_timer_set (w, 5, 7)\*(C'\fR, \f(CW\*(C`ev_timer_remaining\*(C'\fR returns |
|
|
1969 | \&\f(CW5\fR. When the timer is started and one second passes, \f(CW\*(C`ev_timer_remain\*(C'\fR |
|
|
1970 | will return \f(CW4\fR. When the timer expires and is restarted, it will return |
|
|
1971 | roughly \f(CW7\fR (likely slightly less as callback invocation takes some time, |
|
|
1972 | too), and so on. |
1694 | .IP "ev_tstamp repeat [read\-write]" 4 |
1973 | .IP "ev_tstamp repeat [read\-write]" 4 |
1695 | .IX Item "ev_tstamp repeat [read-write]" |
1974 | .IX Item "ev_tstamp repeat [read-write]" |
1696 | The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out |
1975 | The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out |
1697 | or \f(CW\*(C`ev_timer_again\*(C'\fR is called, and determines the next timeout (if any), |
1976 | or \f(CW\*(C`ev_timer_again\*(C'\fR is called, and determines the next timeout (if any), |
1698 | which is also when any modifications are taken into account. |
1977 | which is also when any modifications are taken into account. |
… | |
… | |
1731 | \& |
2010 | \& |
1732 | \& // and in some piece of code that gets executed on any "activity": |
2011 | \& // and in some piece of code that gets executed on any "activity": |
1733 | \& // reset the timeout to start ticking again at 10 seconds |
2012 | \& // reset the timeout to start ticking again at 10 seconds |
1734 | \& ev_timer_again (&mytimer); |
2013 | \& ev_timer_again (&mytimer); |
1735 | .Ve |
2014 | .Ve |
1736 | .ie n .Sh """ev_periodic"" \- to cron or not to cron?" |
2015 | .ie n .SS """ev_periodic"" \- to cron or not to cron?" |
1737 | .el .Sh "\f(CWev_periodic\fP \- to cron or not to cron?" |
2016 | .el .SS "\f(CWev_periodic\fP \- to cron or not to cron?" |
1738 | .IX Subsection "ev_periodic - to cron or not to cron?" |
2017 | .IX Subsection "ev_periodic - to cron or not to cron?" |
1739 | Periodic watchers are also timers of a kind, but they are very versatile |
2018 | Periodic watchers are also timers of a kind, but they are very versatile |
1740 | (and unfortunately a bit complex). |
2019 | (and unfortunately a bit complex). |
1741 | .PP |
2020 | .PP |
1742 | Unlike \f(CW\*(C`ev_timer\*(C'\fR's, they are not based on real time (or relative time) |
2021 | Unlike \f(CW\*(C`ev_timer\*(C'\fR, periodic watchers are not based on real time (or |
1743 | but on wall clock time (absolute time). You can tell a periodic watcher |
2022 | relative time, the physical time that passes) but on wall clock time |
1744 | to trigger after some specific point in time. For example, if you tell a |
2023 | (absolute time, the thing you can read on your calender or clock). The |
1745 | periodic watcher to trigger in 10 seconds (by specifying e.g. \f(CW\*(C`ev_now () |
2024 | difference is that wall clock time can run faster or slower than real |
1746 | + 10.\*(C'\fR, that is, an absolute time not a delay) and then reset your system |
2025 | time, and time jumps are not uncommon (e.g. when you adjust your |
1747 | clock to January of the previous year, then it will take more than year |
2026 | wrist-watch). |
1748 | to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would still trigger |
|
|
1749 | roughly 10 seconds later as it uses a relative timeout). |
|
|
1750 | .PP |
2027 | .PP |
|
|
2028 | You can tell a periodic watcher to trigger after some specific point |
|
|
2029 | in time: for example, if you tell a periodic watcher to trigger \*(L"in 10 |
|
|
2030 | seconds\*(R" (by specifying e.g. \f(CW\*(C`ev_now () + 10.\*(C'\fR, that is, an absolute time |
|
|
2031 | not a delay) and then reset your system clock to January of the previous |
|
|
2032 | year, then it will take a year or more to trigger the event (unlike an |
|
|
2033 | \&\f(CW\*(C`ev_timer\*(C'\fR, which would still trigger roughly 10 seconds after starting |
|
|
2034 | it, as it uses a relative timeout). |
|
|
2035 | .PP |
1751 | \&\f(CW\*(C`ev_periodic\*(C'\fRs can also be used to implement vastly more complex timers, |
2036 | \&\f(CW\*(C`ev_periodic\*(C'\fR watchers can also be used to implement vastly more complex |
1752 | such as triggering an event on each \*(L"midnight, local time\*(R", or other |
2037 | timers, such as triggering an event on each \*(L"midnight, local time\*(R", or |
1753 | complicated rules. |
2038 | other complicated rules. This cannot be done with \f(CW\*(C`ev_timer\*(C'\fR watchers, as |
|
|
2039 | those cannot react to time jumps. |
1754 | .PP |
2040 | .PP |
1755 | As with timers, the callback is guaranteed to be invoked only when the |
2041 | As with timers, the callback is guaranteed to be invoked only when the |
1756 | time (\f(CW\*(C`at\*(C'\fR) has passed, but if multiple periodic timers become ready |
2042 | point in time where it is supposed to trigger has passed. If multiple |
1757 | during the same loop iteration, then order of execution is undefined. |
2043 | timers become ready during the same loop iteration then the ones with |
|
|
2044 | earlier time-out values are invoked before ones with later time-out values |
|
|
2045 | (but this is no longer true when a callback calls \f(CW\*(C`ev_loop\*(C'\fR recursively). |
1758 | .PP |
2046 | .PP |
1759 | \fIWatcher-Specific Functions and Data Members\fR |
2047 | \fIWatcher-Specific Functions and Data Members\fR |
1760 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2048 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1761 | .IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4 |
2049 | .IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" 4 |
1762 | .IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" |
2050 | .IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" |
1763 | .PD 0 |
2051 | .PD 0 |
1764 | .IP "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 4 |
2052 | .IP "ev_periodic_set (ev_periodic *, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" 4 |
1765 | .IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" |
2053 | .IX Item "ev_periodic_set (ev_periodic *, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" |
1766 | .PD |
2054 | .PD |
1767 | Lots of arguments, lets sort it out... There are basically three modes of |
2055 | Lots of arguments, let's sort it out... There are basically three modes of |
1768 | operation, and we will explain them from simplest to most complex: |
2056 | operation, and we will explain them from simplest to most complex: |
1769 | .RS 4 |
2057 | .RS 4 |
1770 | .IP "\(bu" 4 |
2058 | .IP "\(bu" 4 |
1771 | absolute timer (at = time, interval = reschedule_cb = 0) |
2059 | absolute timer (offset = absolute time, interval = 0, reschedule_cb = 0) |
1772 | .Sp |
2060 | .Sp |
1773 | In this configuration the watcher triggers an event after the wall clock |
2061 | In this configuration the watcher triggers an event after the wall clock |
1774 | time \f(CW\*(C`at\*(C'\fR has passed. It will not repeat and will not adjust when a time |
2062 | time \f(CW\*(C`offset\*(C'\fR has passed. It will not repeat and will not adjust when a |
1775 | jump occurs, that is, if it is to be run at January 1st 2011 then it will |
2063 | time jump occurs, that is, if it is to be run at January 1st 2011 then it |
1776 | only run when the system clock reaches or surpasses this time. |
2064 | will be stopped and invoked when the system clock reaches or surpasses |
|
|
2065 | this point in time. |
1777 | .IP "\(bu" 4 |
2066 | .IP "\(bu" 4 |
1778 | repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
2067 | repeating interval timer (offset = offset within interval, interval > 0, reschedule_cb = 0) |
1779 | .Sp |
2068 | .Sp |
1780 | In this mode the watcher will always be scheduled to time out at the next |
2069 | In this mode the watcher will always be scheduled to time out at the next |
1781 | \&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N, which can also be negative) |
2070 | \&\f(CW\*(C`offset + N * interval\*(C'\fR time (for some integer N, which can also be |
1782 | and then repeat, regardless of any time jumps. |
2071 | negative) and then repeat, regardless of any time jumps. The \f(CW\*(C`offset\*(C'\fR |
|
|
2072 | argument is merely an offset into the \f(CW\*(C`interval\*(C'\fR periods. |
1783 | .Sp |
2073 | .Sp |
1784 | This can be used to create timers that do not drift with respect to the |
2074 | This can be used to create timers that do not drift with respect to the |
1785 | system clock, for example, here is a \f(CW\*(C`ev_periodic\*(C'\fR that triggers each |
2075 | system clock, for example, here is an \f(CW\*(C`ev_periodic\*(C'\fR that triggers each |
1786 | hour, on the hour: |
2076 | hour, on the hour (with respect to \s-1UTC\s0): |
1787 | .Sp |
2077 | .Sp |
1788 | .Vb 1 |
2078 | .Vb 1 |
1789 | \& ev_periodic_set (&periodic, 0., 3600., 0); |
2079 | \& ev_periodic_set (&periodic, 0., 3600., 0); |
1790 | .Ve |
2080 | .Ve |
1791 | .Sp |
2081 | .Sp |
… | |
… | |
1794 | full hour (\s-1UTC\s0), or more correctly, when the system time is evenly divisible |
2084 | full hour (\s-1UTC\s0), or more correctly, when the system time is evenly divisible |
1795 | by 3600. |
2085 | by 3600. |
1796 | .Sp |
2086 | .Sp |
1797 | Another way to think about it (for the mathematically inclined) is that |
2087 | Another way to think about it (for the mathematically inclined) is that |
1798 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
2088 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
1799 | time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps. |
2089 | time where \f(CW\*(C`time = offset (mod interval)\*(C'\fR, regardless of any time jumps. |
1800 | .Sp |
2090 | .Sp |
1801 | For numerical stability it is preferable that the \f(CW\*(C`at\*(C'\fR value is near |
2091 | For numerical stability it is preferable that the \f(CW\*(C`offset\*(C'\fR value is near |
1802 | \&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for |
2092 | \&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for |
1803 | this value, and in fact is often specified as zero. |
2093 | this value, and in fact is often specified as zero. |
1804 | .Sp |
2094 | .Sp |
1805 | Note also that there is an upper limit to how often a timer can fire (\s-1CPU\s0 |
2095 | Note also that there is an upper limit to how often a timer can fire (\s-1CPU\s0 |
1806 | speed for example), so if \f(CW\*(C`interval\*(C'\fR is very small then timing stability |
2096 | speed for example), so if \f(CW\*(C`interval\*(C'\fR is very small then timing stability |
1807 | will of course deteriorate. Libev itself tries to be exact to be about one |
2097 | will of course deteriorate. Libev itself tries to be exact to be about one |
1808 | millisecond (if the \s-1OS\s0 supports it and the machine is fast enough). |
2098 | millisecond (if the \s-1OS\s0 supports it and the machine is fast enough). |
1809 | .IP "\(bu" 4 |
2099 | .IP "\(bu" 4 |
1810 | manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
2100 | manual reschedule mode (offset ignored, interval ignored, reschedule_cb = callback) |
1811 | .Sp |
2101 | .Sp |
1812 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being |
2102 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`offset\*(C'\fR are both being |
1813 | ignored. Instead, each time the periodic watcher gets scheduled, the |
2103 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1814 | reschedule callback will be called with the watcher as first, and the |
2104 | reschedule callback will be called with the watcher as first, and the |
1815 | current time as second argument. |
2105 | current time as second argument. |
1816 | .Sp |
2106 | .Sp |
1817 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, |
2107 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, ever, |
1818 | ever, or make \s-1ANY\s0 event loop modifications whatsoever\fR. |
2108 | or make \s-1ANY\s0 other event loop modifications whatsoever, unless explicitly |
|
|
2109 | allowed by documentation here\fR. |
1819 | .Sp |
2110 | .Sp |
1820 | If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop |
2111 | If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop |
1821 | it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the |
2112 | it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the |
1822 | only event loop modification you are allowed to do). |
2113 | only event loop modification you are allowed to do). |
1823 | .Sp |
2114 | .Sp |
… | |
… | |
1854 | when you changed some parameters or the reschedule callback would return |
2145 | when you changed some parameters or the reschedule callback would return |
1855 | a different time than the last time it was called (e.g. in a crond like |
2146 | a different time than the last time it was called (e.g. in a crond like |
1856 | program when the crontabs have changed). |
2147 | program when the crontabs have changed). |
1857 | .IP "ev_tstamp ev_periodic_at (ev_periodic *)" 4 |
2148 | .IP "ev_tstamp ev_periodic_at (ev_periodic *)" 4 |
1858 | .IX Item "ev_tstamp ev_periodic_at (ev_periodic *)" |
2149 | .IX Item "ev_tstamp ev_periodic_at (ev_periodic *)" |
1859 | When active, returns the absolute time that the watcher is supposed to |
2150 | When active, returns the absolute time that the watcher is supposed |
1860 | trigger next. |
2151 | to trigger next. This is not the same as the \f(CW\*(C`offset\*(C'\fR argument to |
|
|
2152 | \&\f(CW\*(C`ev_periodic_set\*(C'\fR, but indeed works even in interval and manual |
|
|
2153 | rescheduling modes. |
1861 | .IP "ev_tstamp offset [read\-write]" 4 |
2154 | .IP "ev_tstamp offset [read\-write]" 4 |
1862 | .IX Item "ev_tstamp offset [read-write]" |
2155 | .IX Item "ev_tstamp offset [read-write]" |
1863 | When repeating, this contains the offset value, otherwise this is the |
2156 | When repeating, this contains the offset value, otherwise this is the |
1864 | absolute point in time (the \f(CW\*(C`at\*(C'\fR value passed to \f(CW\*(C`ev_periodic_set\*(C'\fR). |
2157 | absolute point in time (the \f(CW\*(C`offset\*(C'\fR value passed to \f(CW\*(C`ev_periodic_set\*(C'\fR, |
|
|
2158 | although libev might modify this value for better numerical stability). |
1865 | .Sp |
2159 | .Sp |
1866 | Can be modified any time, but changes only take effect when the periodic |
2160 | Can be modified any time, but changes only take effect when the periodic |
1867 | timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
2161 | timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
1868 | .IP "ev_tstamp interval [read\-write]" 4 |
2162 | .IP "ev_tstamp interval [read\-write]" 4 |
1869 | .IX Item "ev_tstamp interval [read-write]" |
2163 | .IX Item "ev_tstamp interval [read-write]" |
… | |
… | |
1915 | \& ev_periodic hourly_tick; |
2209 | \& ev_periodic hourly_tick; |
1916 | \& ev_periodic_init (&hourly_tick, clock_cb, |
2210 | \& ev_periodic_init (&hourly_tick, clock_cb, |
1917 | \& fmod (ev_now (loop), 3600.), 3600., 0); |
2211 | \& fmod (ev_now (loop), 3600.), 3600., 0); |
1918 | \& ev_periodic_start (loop, &hourly_tick); |
2212 | \& ev_periodic_start (loop, &hourly_tick); |
1919 | .Ve |
2213 | .Ve |
1920 | .ie n .Sh """ev_signal"" \- signal me when a signal gets signalled!" |
2214 | .ie n .SS """ev_signal"" \- signal me when a signal gets signalled!" |
1921 | .el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled!" |
2215 | .el .SS "\f(CWev_signal\fP \- signal me when a signal gets signalled!" |
1922 | .IX Subsection "ev_signal - signal me when a signal gets signalled!" |
2216 | .IX Subsection "ev_signal - signal me when a signal gets signalled!" |
1923 | Signal watchers will trigger an event when the process receives a specific |
2217 | Signal watchers will trigger an event when the process receives a specific |
1924 | signal one or more times. Even though signals are very asynchronous, libev |
2218 | signal one or more times. Even though signals are very asynchronous, libev |
1925 | will try it's best to deliver signals synchronously, i.e. as part of the |
2219 | will try it's best to deliver signals synchronously, i.e. as part of the |
1926 | normal event processing, like any other event. |
2220 | normal event processing, like any other event. |
… | |
… | |
1970 | \& |
2264 | \& |
1971 | \& ev_signal signal_watcher; |
2265 | \& ev_signal signal_watcher; |
1972 | \& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2266 | \& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1973 | \& ev_signal_start (loop, &signal_watcher); |
2267 | \& ev_signal_start (loop, &signal_watcher); |
1974 | .Ve |
2268 | .Ve |
1975 | .ie n .Sh """ev_child"" \- watch out for process status changes" |
2269 | .ie n .SS """ev_child"" \- watch out for process status changes" |
1976 | .el .Sh "\f(CWev_child\fP \- watch out for process status changes" |
2270 | .el .SS "\f(CWev_child\fP \- watch out for process status changes" |
1977 | .IX Subsection "ev_child - watch out for process status changes" |
2271 | .IX Subsection "ev_child - watch out for process status changes" |
1978 | Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to |
2272 | Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to |
1979 | some child status changes (most typically when a child of yours dies or |
2273 | some child status changes (most typically when a child of yours dies or |
1980 | exits). It is permissible to install a child watcher \fIafter\fR the child |
2274 | exits). It is permissible to install a child watcher \fIafter\fR the child |
1981 | has been forked (which implies it might have already exited), as long |
2275 | has been forked (which implies it might have already exited), as long |
1982 | as the event loop isn't entered (or is continued from a watcher), i.e., |
2276 | as the event loop isn't entered (or is continued from a watcher), i.e., |
1983 | forking and then immediately registering a watcher for the child is fine, |
2277 | forking and then immediately registering a watcher for the child is fine, |
1984 | but forking and registering a watcher a few event loop iterations later is |
2278 | but forking and registering a watcher a few event loop iterations later or |
1985 | not. |
2279 | in the next callback invocation is not. |
1986 | .PP |
2280 | .PP |
1987 | Only the default event loop is capable of handling signals, and therefore |
2281 | Only the default event loop is capable of handling signals, and therefore |
1988 | you can only register child watchers in the default event loop. |
2282 | you can only register child watchers in the default event loop. |
|
|
2283 | .PP |
|
|
2284 | Due to some design glitches inside libev, child watchers will always be |
|
|
2285 | handled at maximum priority (their priority is set to \f(CW\*(C`EV_MAXPRI\*(C'\fR by |
|
|
2286 | libev) |
1989 | .PP |
2287 | .PP |
1990 | \fIProcess Interaction\fR |
2288 | \fIProcess Interaction\fR |
1991 | .IX Subsection "Process Interaction" |
2289 | .IX Subsection "Process Interaction" |
1992 | .PP |
2290 | .PP |
1993 | Libev grabs \f(CW\*(C`SIGCHLD\*(C'\fR as soon as the default event loop is |
2291 | Libev grabs \f(CW\*(C`SIGCHLD\*(C'\fR as soon as the default event loop is |
… | |
… | |
2072 | \& { |
2370 | \& { |
2073 | \& ev_child_init (&cw, child_cb, pid, 0); |
2371 | \& ev_child_init (&cw, child_cb, pid, 0); |
2074 | \& ev_child_start (EV_DEFAULT_ &cw); |
2372 | \& ev_child_start (EV_DEFAULT_ &cw); |
2075 | \& } |
2373 | \& } |
2076 | .Ve |
2374 | .Ve |
2077 | .ie n .Sh """ev_stat"" \- did the file attributes just change?" |
2375 | .ie n .SS """ev_stat"" \- did the file attributes just change?" |
2078 | .el .Sh "\f(CWev_stat\fP \- did the file attributes just change?" |
2376 | .el .SS "\f(CWev_stat\fP \- did the file attributes just change?" |
2079 | .IX Subsection "ev_stat - did the file attributes just change?" |
2377 | .IX Subsection "ev_stat - did the file attributes just change?" |
2080 | This watches a file system path for attribute changes. That is, it calls |
2378 | This watches a file system path for attribute changes. That is, it calls |
2081 | \&\f(CW\*(C`stat\*(C'\fR on that path in regular intervals (or when the \s-1OS\s0 says it changed) |
2379 | \&\f(CW\*(C`stat\*(C'\fR on that path in regular intervals (or when the \s-1OS\s0 says it changed) |
2082 | and sees if it changed compared to the last time, invoking the callback if |
2380 | and sees if it changed compared to the last time, invoking the callback if |
2083 | it did. |
2381 | it did. |
2084 | .PP |
2382 | .PP |
2085 | The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does |
2383 | The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does |
2086 | not exist\*(R" is a status change like any other. The condition \*(L"path does |
2384 | not exist\*(R" is a status change like any other. The condition \*(L"path does not |
2087 | not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is |
2385 | exist\*(R" (or more correctly \*(L"path cannot be stat'ed\*(R") is signified by the |
2088 | otherwise always forced to be at least one) and all the other fields of |
2386 | \&\f(CW\*(C`st_nlink\*(C'\fR field being zero (which is otherwise always forced to be at |
2089 | the stat buffer having unspecified contents. |
2387 | least one) and all the other fields of the stat buffer having unspecified |
|
|
2388 | contents. |
2090 | .PP |
2389 | .PP |
2091 | The path \fImust not\fR end in a slash or contain special components such as |
2390 | The path \fImust not\fR end in a slash or contain special components such as |
2092 | \&\f(CW\*(C`.\*(C'\fR or \f(CW\*(C`..\*(C'\fR. The path \fIshould\fR be absolute: If it is relative and |
2391 | \&\f(CW\*(C`.\*(C'\fR or \f(CW\*(C`..\*(C'\fR. The path \fIshould\fR be absolute: If it is relative and |
2093 | your working directory changes, then the behaviour is undefined. |
2392 | your working directory changes, then the behaviour is undefined. |
2094 | .PP |
2393 | .PP |
… | |
… | |
2104 | This watcher type is not meant for massive numbers of stat watchers, |
2403 | This watcher type is not meant for massive numbers of stat watchers, |
2105 | as even with OS-supported change notifications, this can be |
2404 | as even with OS-supported change notifications, this can be |
2106 | resource-intensive. |
2405 | resource-intensive. |
2107 | .PP |
2406 | .PP |
2108 | At the time of this writing, the only OS-specific interface implemented |
2407 | At the time of this writing, the only OS-specific interface implemented |
2109 | is the Linux inotify interface (implementing kqueue support is left as |
2408 | is the Linux inotify interface (implementing kqueue support is left as an |
2110 | an exercise for the reader. Note, however, that the author sees no way |
2409 | exercise for the reader. Note, however, that the author sees no way of |
2111 | of implementing \f(CW\*(C`ev_stat\*(C'\fR semantics with kqueue). |
2410 | implementing \f(CW\*(C`ev_stat\*(C'\fR semantics with kqueue, except as a hint). |
2112 | .PP |
2411 | .PP |
2113 | \fI\s-1ABI\s0 Issues (Largefile Support)\fR |
2412 | \fI\s-1ABI\s0 Issues (Largefile Support)\fR |
2114 | .IX Subsection "ABI Issues (Largefile Support)" |
2413 | .IX Subsection "ABI Issues (Largefile Support)" |
2115 | .PP |
2414 | .PP |
2116 | Libev by default (unless the user overrides this) uses the default |
2415 | Libev by default (unless the user overrides this) uses the default |
… | |
… | |
2129 | default compilation environment. |
2428 | default compilation environment. |
2130 | .PP |
2429 | .PP |
2131 | \fIInotify and Kqueue\fR |
2430 | \fIInotify and Kqueue\fR |
2132 | .IX Subsection "Inotify and Kqueue" |
2431 | .IX Subsection "Inotify and Kqueue" |
2133 | .PP |
2432 | .PP |
2134 | When \f(CW\*(C`inotify (7)\*(C'\fR support has been compiled into libev (generally |
2433 | When \f(CW\*(C`inotify (7)\*(C'\fR support has been compiled into libev and present at |
2135 | only available with Linux 2.6.25 or above due to bugs in earlier |
2434 | runtime, it will be used to speed up change detection where possible. The |
2136 | implementations) and present at runtime, it will be used to speed up |
2435 | inotify descriptor will be created lazily when the first \f(CW\*(C`ev_stat\*(C'\fR |
2137 | change detection where possible. The inotify descriptor will be created |
2436 | watcher is being started. |
2138 | lazily when the first \f(CW\*(C`ev_stat\*(C'\fR watcher is being started. |
|
|
2139 | .PP |
2437 | .PP |
2140 | Inotify presence does not change the semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers |
2438 | Inotify presence does not change the semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers |
2141 | except that changes might be detected earlier, and in some cases, to avoid |
2439 | except that changes might be detected earlier, and in some cases, to avoid |
2142 | making regular \f(CW\*(C`stat\*(C'\fR calls. Even in the presence of inotify support |
2440 | making regular \f(CW\*(C`stat\*(C'\fR calls. Even in the presence of inotify support |
2143 | there are many cases where libev has to resort to regular \f(CW\*(C`stat\*(C'\fR polling, |
2441 | there are many cases where libev has to resort to regular \f(CW\*(C`stat\*(C'\fR polling, |
2144 | but as long as the path exists, libev usually gets away without polling. |
2442 | but as long as kernel 2.6.25 or newer is used (2.6.24 and older have too |
|
|
2443 | many bugs), the path exists (i.e. stat succeeds), and the path resides on |
|
|
2444 | a local filesystem (libev currently assumes only ext2/3, jfs, reiserfs and |
|
|
2445 | xfs are fully working) libev usually gets away without polling. |
2145 | .PP |
2446 | .PP |
2146 | There is no support for kqueue, as apparently it cannot be used to |
2447 | There is no support for kqueue, as apparently it cannot be used to |
2147 | implement this functionality, due to the requirement of having a file |
2448 | implement this functionality, due to the requirement of having a file |
2148 | descriptor open on the object at all times, and detecting renames, unlinks |
2449 | descriptor open on the object at all times, and detecting renames, unlinks |
2149 | etc. is difficult. |
2450 | etc. is difficult. |
|
|
2451 | .PP |
|
|
2452 | \fI\f(CI\*(C`stat ()\*(C'\fI is a synchronous operation\fR |
|
|
2453 | .IX Subsection "stat () is a synchronous operation" |
|
|
2454 | .PP |
|
|
2455 | Libev doesn't normally do any kind of I/O itself, and so is not blocking |
|
|
2456 | the process. The exception are \f(CW\*(C`ev_stat\*(C'\fR watchers \- those call \f(CW\*(C`stat |
|
|
2457 | ()\*(C'\fR, which is a synchronous operation. |
|
|
2458 | .PP |
|
|
2459 | For local paths, this usually doesn't matter: unless the system is very |
|
|
2460 | busy or the intervals between stat's are large, a stat call will be fast, |
|
|
2461 | as the path data is usually in memory already (except when starting the |
|
|
2462 | watcher). |
|
|
2463 | .PP |
|
|
2464 | For networked file systems, calling \f(CW\*(C`stat ()\*(C'\fR can block an indefinite |
|
|
2465 | time due to network issues, and even under good conditions, a stat call |
|
|
2466 | often takes multiple milliseconds. |
|
|
2467 | .PP |
|
|
2468 | Therefore, it is best to avoid using \f(CW\*(C`ev_stat\*(C'\fR watchers on networked |
|
|
2469 | paths, although this is fully supported by libev. |
2150 | .PP |
2470 | .PP |
2151 | \fIThe special problem of stat time resolution\fR |
2471 | \fIThe special problem of stat time resolution\fR |
2152 | .IX Subsection "The special problem of stat time resolution" |
2472 | .IX Subsection "The special problem of stat time resolution" |
2153 | .PP |
2473 | .PP |
2154 | The \f(CW\*(C`stat ()\*(C'\fR system call only supports full-second resolution portably, |
2474 | The \f(CW\*(C`stat ()\*(C'\fR system call only supports full-second resolution portably, |
… | |
… | |
2275 | \& ... |
2595 | \& ... |
2276 | \& ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
2596 | \& ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
2277 | \& ev_stat_start (loop, &passwd); |
2597 | \& ev_stat_start (loop, &passwd); |
2278 | \& ev_timer_init (&timer, timer_cb, 0., 1.02); |
2598 | \& ev_timer_init (&timer, timer_cb, 0., 1.02); |
2279 | .Ve |
2599 | .Ve |
2280 | .ie n .Sh """ev_idle"" \- when you've got nothing better to do..." |
2600 | .ie n .SS """ev_idle"" \- when you've got nothing better to do..." |
2281 | .el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..." |
2601 | .el .SS "\f(CWev_idle\fP \- when you've got nothing better to do..." |
2282 | .IX Subsection "ev_idle - when you've got nothing better to do..." |
2602 | .IX Subsection "ev_idle - when you've got nothing better to do..." |
2283 | Idle watchers trigger events when no other events of the same or higher |
2603 | Idle watchers trigger events when no other events of the same or higher |
2284 | priority are pending (prepare, check and other idle watchers do not count |
2604 | priority are pending (prepare, check and other idle watchers do not count |
2285 | as receiving \*(L"events\*(R"). |
2605 | as receiving \*(L"events\*(R"). |
2286 | .PP |
2606 | .PP |
… | |
… | |
2299 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
2619 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
2300 | event loop has handled all outstanding events. |
2620 | event loop has handled all outstanding events. |
2301 | .PP |
2621 | .PP |
2302 | \fIWatcher-Specific Functions and Data Members\fR |
2622 | \fIWatcher-Specific Functions and Data Members\fR |
2303 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2623 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2304 | .IP "ev_idle_init (ev_signal *, callback)" 4 |
2624 | .IP "ev_idle_init (ev_idle *, callback)" 4 |
2305 | .IX Item "ev_idle_init (ev_signal *, callback)" |
2625 | .IX Item "ev_idle_init (ev_idle *, callback)" |
2306 | Initialises and configures the idle watcher \- it has no parameters of any |
2626 | Initialises and configures the idle watcher \- it has no parameters of any |
2307 | kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, |
2627 | kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, |
2308 | believe me. |
2628 | believe me. |
2309 | .PP |
2629 | .PP |
2310 | \fIExamples\fR |
2630 | \fIExamples\fR |
… | |
… | |
2322 | \& // no longer anything immediate to do. |
2642 | \& // no longer anything immediate to do. |
2323 | \& } |
2643 | \& } |
2324 | \& |
2644 | \& |
2325 | \& ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
2645 | \& ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
2326 | \& ev_idle_init (idle_watcher, idle_cb); |
2646 | \& ev_idle_init (idle_watcher, idle_cb); |
2327 | \& ev_idle_start (loop, idle_cb); |
2647 | \& ev_idle_start (loop, idle_watcher); |
2328 | .Ve |
2648 | .Ve |
2329 | .ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!" |
2649 | .ie n .SS """ev_prepare"" and ""ev_check"" \- customise your event loop!" |
2330 | .el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" |
2650 | .el .SS "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" |
2331 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
2651 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
2332 | Prepare and check watchers are usually (but not always) used in pairs: |
2652 | Prepare and check watchers are usually (but not always) used in pairs: |
2333 | prepare watchers get invoked before the process blocks and check watchers |
2653 | prepare watchers get invoked before the process blocks and check watchers |
2334 | afterwards. |
2654 | afterwards. |
2335 | .PP |
2655 | .PP |
… | |
… | |
2425 | \& struct pollfd fds [nfd]; |
2745 | \& struct pollfd fds [nfd]; |
2426 | \& // actual code will need to loop here and realloc etc. |
2746 | \& // actual code will need to loop here and realloc etc. |
2427 | \& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2747 | \& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2428 | \& |
2748 | \& |
2429 | \& /* the callback is illegal, but won\*(Aqt be called as we stop during check */ |
2749 | \& /* the callback is illegal, but won\*(Aqt be called as we stop during check */ |
2430 | \& ev_timer_init (&tw, 0, timeout * 1e\-3); |
2750 | \& ev_timer_init (&tw, 0, timeout * 1e\-3, 0.); |
2431 | \& ev_timer_start (loop, &tw); |
2751 | \& ev_timer_start (loop, &tw); |
2432 | \& |
2752 | \& |
2433 | \& // create one ev_io per pollfd |
2753 | \& // create one ev_io per pollfd |
2434 | \& for (int i = 0; i < nfd; ++i) |
2754 | \& for (int i = 0; i < nfd; ++i) |
2435 | \& { |
2755 | \& { |
… | |
… | |
2526 | \& ev_io_stop (EV_A_ iow [n]); |
2846 | \& ev_io_stop (EV_A_ iow [n]); |
2527 | \& |
2847 | \& |
2528 | \& return got_events; |
2848 | \& return got_events; |
2529 | \& } |
2849 | \& } |
2530 | .Ve |
2850 | .Ve |
2531 | .ie n .Sh """ev_embed"" \- when one backend isn't enough..." |
2851 | .ie n .SS """ev_embed"" \- when one backend isn't enough..." |
2532 | .el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." |
2852 | .el .SS "\f(CWev_embed\fP \- when one backend isn't enough..." |
2533 | .IX Subsection "ev_embed - when one backend isn't enough..." |
2853 | .IX Subsection "ev_embed - when one backend isn't enough..." |
2534 | This is a rather advanced watcher type that lets you embed one event loop |
2854 | This is a rather advanced watcher type that lets you embed one event loop |
2535 | into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded |
2855 | into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded |
2536 | loop, other types of watchers might be handled in a delayed or incorrect |
2856 | loop, other types of watchers might be handled in a delayed or incorrect |
2537 | fashion and must not be used). |
2857 | fashion and must not be used). |
… | |
… | |
2552 | some fds have to be watched and handled very quickly (with low latency), |
2872 | some fds have to be watched and handled very quickly (with low latency), |
2553 | and even priorities and idle watchers might have too much overhead. In |
2873 | and even priorities and idle watchers might have too much overhead. In |
2554 | this case you would put all the high priority stuff in one loop and all |
2874 | this case you would put all the high priority stuff in one loop and all |
2555 | the rest in a second one, and embed the second one in the first. |
2875 | the rest in a second one, and embed the second one in the first. |
2556 | .PP |
2876 | .PP |
2557 | As long as the watcher is active, the callback will be invoked every time |
2877 | As long as the watcher is active, the callback will be invoked every |
2558 | there might be events pending in the embedded loop. The callback must then |
2878 | time there might be events pending in the embedded loop. The callback |
2559 | call \f(CW\*(C`ev_embed_sweep (mainloop, watcher)\*(C'\fR to make a single sweep and invoke |
2879 | must then call \f(CW\*(C`ev_embed_sweep (mainloop, watcher)\*(C'\fR to make a single |
2560 | their callbacks (you could also start an idle watcher to give the embedded |
2880 | sweep and invoke their callbacks (the callback doesn't need to invoke the |
2561 | loop strictly lower priority for example). You can also set the callback |
2881 | \&\f(CW\*(C`ev_embed_sweep\*(C'\fR function directly, it could also start an idle watcher |
2562 | to \f(CW0\fR, in which case the embed watcher will automatically execute the |
2882 | to give the embedded loop strictly lower priority for example). |
2563 | embedded loop sweep. |
|
|
2564 | .PP |
2883 | .PP |
2565 | As long as the watcher is started it will automatically handle events. The |
2884 | You can also set the callback to \f(CW0\fR, in which case the embed watcher |
2566 | callback will be invoked whenever some events have been handled. You can |
2885 | will automatically execute the embedded loop sweep whenever necessary. |
2567 | set the callback to \f(CW0\fR to avoid having to specify one if you are not |
|
|
2568 | interested in that. |
|
|
2569 | .PP |
2886 | .PP |
2570 | Also, there have not currently been made special provisions for forking: |
2887 | Fork detection will be handled transparently while the \f(CW\*(C`ev_embed\*(C'\fR watcher |
2571 | when you fork, you not only have to call \f(CW\*(C`ev_loop_fork\*(C'\fR on both loops, |
2888 | is active, i.e., the embedded loop will automatically be forked when the |
2572 | but you will also have to stop and restart any \f(CW\*(C`ev_embed\*(C'\fR watchers |
2889 | embedding loop forks. In other cases, the user is responsible for calling |
2573 | yourself \- but you can use a fork watcher to handle this automatically, |
2890 | \&\f(CW\*(C`ev_loop_fork\*(C'\fR on the embedded loop. |
2574 | and future versions of libev might do just that. |
|
|
2575 | .PP |
2891 | .PP |
2576 | Unfortunately, not all backends are embeddable: only the ones returned by |
2892 | Unfortunately, not all backends are embeddable: only the ones returned by |
2577 | \&\f(CW\*(C`ev_embeddable_backends\*(C'\fR are, which, unfortunately, does not include any |
2893 | \&\f(CW\*(C`ev_embeddable_backends\*(C'\fR are, which, unfortunately, does not include any |
2578 | portable one. |
2894 | portable one. |
2579 | .PP |
2895 | .PP |
… | |
… | |
2663 | \& if (!loop_socket) |
2979 | \& if (!loop_socket) |
2664 | \& loop_socket = loop; |
2980 | \& loop_socket = loop; |
2665 | \& |
2981 | \& |
2666 | \& // now use loop_socket for all sockets, and loop for everything else |
2982 | \& // now use loop_socket for all sockets, and loop for everything else |
2667 | .Ve |
2983 | .Ve |
2668 | .ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork" |
2984 | .ie n .SS """ev_fork"" \- the audacity to resume the event loop after a fork" |
2669 | .el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
2985 | .el .SS "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
2670 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
2986 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
2671 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
2987 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
2672 | whoever is a good citizen cared to tell libev about it by calling |
2988 | whoever is a good citizen cared to tell libev about it by calling |
2673 | \&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the |
2989 | \&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the |
2674 | event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, |
2990 | event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, |
2675 | and only in the child after the fork. If whoever good citizen calling |
2991 | and only in the child after the fork. If whoever good citizen calling |
2676 | \&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork |
2992 | \&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork |
2677 | handlers will be invoked, too, of course. |
2993 | handlers will be invoked, too, of course. |
2678 | .PP |
2994 | .PP |
|
|
2995 | \fIThe special problem of life after fork \- how is it possible?\fR |
|
|
2996 | .IX Subsection "The special problem of life after fork - how is it possible?" |
|
|
2997 | .PP |
|
|
2998 | Most uses of \f(CW\*(C`fork()\*(C'\fR consist of forking, then some simple calls to ste |
|
|
2999 | up/change the process environment, followed by a call to \f(CW\*(C`exec()\*(C'\fR. This |
|
|
3000 | sequence should be handled by libev without any problems. |
|
|
3001 | .PP |
|
|
3002 | This changes when the application actually wants to do event handling |
|
|
3003 | in the child, or both parent in child, in effect \*(L"continuing\*(R" after the |
|
|
3004 | fork. |
|
|
3005 | .PP |
|
|
3006 | The default mode of operation (for libev, with application help to detect |
|
|
3007 | forks) is to duplicate all the state in the child, as would be expected |
|
|
3008 | when \fIeither\fR the parent \fIor\fR the child process continues. |
|
|
3009 | .PP |
|
|
3010 | When both processes want to continue using libev, then this is usually the |
|
|
3011 | wrong result. In that case, usually one process (typically the parent) is |
|
|
3012 | supposed to continue with all watchers in place as before, while the other |
|
|
3013 | process typically wants to start fresh, i.e. without any active watchers. |
|
|
3014 | .PP |
|
|
3015 | The cleanest and most efficient way to achieve that with libev is to |
|
|
3016 | simply create a new event loop, which of course will be \*(L"empty\*(R", and |
|
|
3017 | use that for new watchers. This has the advantage of not touching more |
|
|
3018 | memory than necessary, and thus avoiding the copy-on-write, and the |
|
|
3019 | disadvantage of having to use multiple event loops (which do not support |
|
|
3020 | signal watchers). |
|
|
3021 | .PP |
|
|
3022 | When this is not possible, or you want to use the default loop for |
|
|
3023 | other reasons, then in the process that wants to start \*(L"fresh\*(R", call |
|
|
3024 | \&\f(CW\*(C`ev_default_destroy ()\*(C'\fR followed by \f(CW\*(C`ev_default_loop (...)\*(C'\fR. Destroying |
|
|
3025 | the default loop will \*(L"orphan\*(R" (not stop) all registered watchers, so you |
|
|
3026 | have to be careful not to execute code that modifies those watchers. Note |
|
|
3027 | also that in that case, you have to re-register any signal watchers. |
|
|
3028 | .PP |
2679 | \fIWatcher-Specific Functions and Data Members\fR |
3029 | \fIWatcher-Specific Functions and Data Members\fR |
2680 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3030 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2681 | .IP "ev_fork_init (ev_signal *, callback)" 4 |
3031 | .IP "ev_fork_init (ev_signal *, callback)" 4 |
2682 | .IX Item "ev_fork_init (ev_signal *, callback)" |
3032 | .IX Item "ev_fork_init (ev_signal *, callback)" |
2683 | Initialises and configures the fork watcher \- it has no parameters of any |
3033 | Initialises and configures the fork watcher \- it has no parameters of any |
2684 | kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, |
3034 | kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, |
2685 | believe me. |
3035 | believe me. |
2686 | .ie n .Sh """ev_async"" \- how to wake up another event loop" |
3036 | .ie n .SS """ev_async"" \- how to wake up another event loop" |
2687 | .el .Sh "\f(CWev_async\fP \- how to wake up another event loop" |
3037 | .el .SS "\f(CWev_async\fP \- how to wake up another event loop" |
2688 | .IX Subsection "ev_async - how to wake up another event loop" |
3038 | .IX Subsection "ev_async - how to wake up another event loop" |
2689 | In general, you cannot use an \f(CW\*(C`ev_loop\*(C'\fR from multiple threads or other |
3039 | In general, you cannot use an \f(CW\*(C`ev_loop\*(C'\fR from multiple threads or other |
2690 | asynchronous sources such as signal handlers (as opposed to multiple event |
3040 | asynchronous sources such as signal handlers (as opposed to multiple event |
2691 | loops \- those are of course safe to use in different threads). |
3041 | loops \- those are of course safe to use in different threads). |
2692 | .PP |
3042 | .PP |
… | |
… | |
2801 | an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop. Unlike |
3151 | an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop. Unlike |
2802 | \&\f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do from other threads, signal or |
3152 | \&\f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do from other threads, signal or |
2803 | similar contexts (see the discussion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the embedding |
3153 | similar contexts (see the discussion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the embedding |
2804 | section below on what exactly this means). |
3154 | section below on what exactly this means). |
2805 | .Sp |
3155 | .Sp |
|
|
3156 | Note that, as with other watchers in libev, multiple events might get |
|
|
3157 | compressed into a single callback invocation (another way to look at this |
|
|
3158 | is that \f(CW\*(C`ev_async\*(C'\fR watchers are level-triggered, set on \f(CW\*(C`ev_async_send\*(C'\fR, |
|
|
3159 | reset when the event loop detects that). |
|
|
3160 | .Sp |
2806 | This call incurs the overhead of a system call only once per loop iteration, |
3161 | This call incurs the overhead of a system call only once per event loop |
2807 | so while the overhead might be noticeable, it doesn't apply to repeated |
3162 | iteration, so while the overhead might be noticeable, it doesn't apply to |
2808 | calls to \f(CW\*(C`ev_async_send\*(C'\fR. |
3163 | repeated calls to \f(CW\*(C`ev_async_send\*(C'\fR for the same event loop. |
2809 | .IP "bool = ev_async_pending (ev_async *)" 4 |
3164 | .IP "bool = ev_async_pending (ev_async *)" 4 |
2810 | .IX Item "bool = ev_async_pending (ev_async *)" |
3165 | .IX Item "bool = ev_async_pending (ev_async *)" |
2811 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
3166 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
2812 | watcher but the event has not yet been processed (or even noted) by the |
3167 | watcher but the event has not yet been processed (or even noted) by the |
2813 | event loop. |
3168 | event loop. |
… | |
… | |
2815 | \&\f(CW\*(C`ev_async_send\*(C'\fR sets a flag in the watcher and wakes up the loop. When |
3170 | \&\f(CW\*(C`ev_async_send\*(C'\fR sets a flag in the watcher and wakes up the loop. When |
2816 | the loop iterates next and checks for the watcher to have become active, |
3171 | the loop iterates next and checks for the watcher to have become active, |
2817 | it will reset the flag again. \f(CW\*(C`ev_async_pending\*(C'\fR can be used to very |
3172 | it will reset the flag again. \f(CW\*(C`ev_async_pending\*(C'\fR can be used to very |
2818 | quickly check whether invoking the loop might be a good idea. |
3173 | quickly check whether invoking the loop might be a good idea. |
2819 | .Sp |
3174 | .Sp |
2820 | Not that this does \fInot\fR check whether the watcher itself is pending, only |
3175 | Not that this does \fInot\fR check whether the watcher itself is pending, |
2821 | whether it has been requested to make this watcher pending. |
3176 | only whether it has been requested to make this watcher pending: there |
|
|
3177 | is a time window between the event loop checking and resetting the async |
|
|
3178 | notification, and the callback being invoked. |
2822 | .SH "OTHER FUNCTIONS" |
3179 | .SH "OTHER FUNCTIONS" |
2823 | .IX Header "OTHER FUNCTIONS" |
3180 | .IX Header "OTHER FUNCTIONS" |
2824 | There are some other functions of possible interest. Described. Here. Now. |
3181 | There are some other functions of possible interest. Described. Here. Now. |
2825 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
3182 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
2826 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
3183 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
… | |
… | |
2923 | need one additional pointer for context. If you need support for other |
3280 | need one additional pointer for context. If you need support for other |
2924 | types of functors please contact the author (preferably after implementing |
3281 | types of functors please contact the author (preferably after implementing |
2925 | it). |
3282 | it). |
2926 | .PP |
3283 | .PP |
2927 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
3284 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
2928 | .ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4 |
3285 | .ie n .IP """ev::READ"", ""ev::WRITE"" etc." 4 |
2929 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
3286 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
2930 | .IX Item "ev::READ, ev::WRITE etc." |
3287 | .IX Item "ev::READ, ev::WRITE etc." |
2931 | These are just enum values with the same values as the \f(CW\*(C`EV_READ\*(C'\fR etc. |
3288 | These are just enum values with the same values as the \f(CW\*(C`EV_READ\*(C'\fR etc. |
2932 | macros from \fIev.h\fR. |
3289 | macros from \fIev.h\fR. |
2933 | .ie n .IP """ev::tstamp""\fR, \f(CW""ev::now""" 4 |
3290 | .ie n .IP """ev::tstamp"", ""ev::now""" 4 |
2934 | .el .IP "\f(CWev::tstamp\fR, \f(CWev::now\fR" 4 |
3291 | .el .IP "\f(CWev::tstamp\fR, \f(CWev::now\fR" 4 |
2935 | .IX Item "ev::tstamp, ev::now" |
3292 | .IX Item "ev::tstamp, ev::now" |
2936 | Aliases to the same types/functions as with the \f(CW\*(C`ev_\*(C'\fR prefix. |
3293 | Aliases to the same types/functions as with the \f(CW\*(C`ev_\*(C'\fR prefix. |
2937 | .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 |
3294 | .ie n .IP """ev::io"", ""ev::timer"", ""ev::periodic"", ""ev::idle"", ""ev::sig"" etc." 4 |
2938 | .el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4 |
3295 | .el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4 |
2939 | .IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc." |
3296 | .IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc." |
2940 | For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of |
3297 | For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of |
2941 | the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR |
3298 | the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR |
2942 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
3299 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
… | |
… | |
2987 | \& } |
3344 | \& } |
2988 | \& |
3345 | \& |
2989 | \& myclass obj; |
3346 | \& myclass obj; |
2990 | \& ev::io iow; |
3347 | \& ev::io iow; |
2991 | \& iow.set <myclass, &myclass::io_cb> (&obj); |
3348 | \& iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
3349 | .Ve |
|
|
3350 | .IP "w\->set (object *)" 4 |
|
|
3351 | .IX Item "w->set (object *)" |
|
|
3352 | This is an \fBexperimental\fR feature that might go away in a future version. |
|
|
3353 | .Sp |
|
|
3354 | This is a variation of a method callback \- leaving out the method to call |
|
|
3355 | will default the method to \f(CW\*(C`operator ()\*(C'\fR, which makes it possible to use |
|
|
3356 | functor objects without having to manually specify the \f(CW\*(C`operator ()\*(C'\fR all |
|
|
3357 | the time. Incidentally, you can then also leave out the template argument |
|
|
3358 | list. |
|
|
3359 | .Sp |
|
|
3360 | The \f(CW\*(C`operator ()\*(C'\fR method prototype must be \f(CW\*(C`void operator ()(watcher &w, |
|
|
3361 | int revents)\*(C'\fR. |
|
|
3362 | .Sp |
|
|
3363 | See the method\-\f(CW\*(C`set\*(C'\fR above for more details. |
|
|
3364 | .Sp |
|
|
3365 | Example: use a functor object as callback. |
|
|
3366 | .Sp |
|
|
3367 | .Vb 7 |
|
|
3368 | \& struct myfunctor |
|
|
3369 | \& { |
|
|
3370 | \& void operator() (ev::io &w, int revents) |
|
|
3371 | \& { |
|
|
3372 | \& ... |
|
|
3373 | \& } |
|
|
3374 | \& } |
|
|
3375 | \& |
|
|
3376 | \& myfunctor f; |
|
|
3377 | \& |
|
|
3378 | \& ev::io w; |
|
|
3379 | \& w.set (&f); |
2992 | .Ve |
3380 | .Ve |
2993 | .IP "w\->set<function> (void *data = 0)" 4 |
3381 | .IP "w\->set<function> (void *data = 0)" 4 |
2994 | .IX Item "w->set<function> (void *data = 0)" |
3382 | .IX Item "w->set<function> (void *data = 0)" |
2995 | Also sets a callback, but uses a static method or plain function as |
3383 | Also sets a callback, but uses a static method or plain function as |
2996 | callback. The optional \f(CW\*(C`data\*(C'\fR argument will be stored in the watcher's |
3384 | callback. The optional \f(CW\*(C`data\*(C'\fR argument will be stored in the watcher's |
… | |
… | |
3021 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
3409 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
3022 | constructor already stores the event loop. |
3410 | constructor already stores the event loop. |
3023 | .IP "w\->stop ()" 4 |
3411 | .IP "w\->stop ()" 4 |
3024 | .IX Item "w->stop ()" |
3412 | .IX Item "w->stop ()" |
3025 | Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. |
3413 | Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. |
3026 | .ie n .IP "w\->again () (""ev::timer""\fR, \f(CW""ev::periodic"" only)" 4 |
3414 | .ie n .IP "w\->again () (""ev::timer"", ""ev::periodic"" only)" 4 |
3027 | .el .IP "w\->again () (\f(CWev::timer\fR, \f(CWev::periodic\fR only)" 4 |
3415 | .el .IP "w\->again () (\f(CWev::timer\fR, \f(CWev::periodic\fR only)" 4 |
3028 | .IX Item "w->again () (ev::timer, ev::periodic only)" |
3416 | .IX Item "w->again () (ev::timer, ev::periodic only)" |
3029 | For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding |
3417 | For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding |
3030 | \&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. |
3418 | \&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. |
3031 | .ie n .IP "w\->sweep () (""ev::embed"" only)" 4 |
3419 | .ie n .IP "w\->sweep () (""ev::embed"" only)" 4 |
… | |
… | |
3076 | It can be found and installed via \s-1CPAN\s0, its homepage is at |
3464 | It can be found and installed via \s-1CPAN\s0, its homepage is at |
3077 | <http://software.schmorp.de/pkg/EV>. |
3465 | <http://software.schmorp.de/pkg/EV>. |
3078 | .IP "Python" 4 |
3466 | .IP "Python" 4 |
3079 | .IX Item "Python" |
3467 | .IX Item "Python" |
3080 | Python bindings can be found at <http://code.google.com/p/pyev/>. It |
3468 | Python bindings can be found at <http://code.google.com/p/pyev/>. It |
3081 | seems to be quite complete and well-documented. Note, however, that the |
3469 | seems to be quite complete and well-documented. |
3082 | patch they require for libev is outright dangerous as it breaks the \s-1ABI\s0 |
|
|
3083 | for everybody else, and therefore, should never be applied in an installed |
|
|
3084 | libev (if python requires an incompatible \s-1ABI\s0 then it needs to embed |
|
|
3085 | libev). |
|
|
3086 | .IP "Ruby" 4 |
3470 | .IP "Ruby" 4 |
3087 | .IX Item "Ruby" |
3471 | .IX Item "Ruby" |
3088 | Tony Arcieri has written a ruby extension that offers access to a subset |
3472 | Tony Arcieri has written a ruby extension that offers access to a subset |
3089 | of the libev \s-1API\s0 and adds file handle abstractions, asynchronous \s-1DNS\s0 and |
3473 | of the libev \s-1API\s0 and adds file handle abstractions, asynchronous \s-1DNS\s0 and |
3090 | more on top of it. It can be found via gem servers. Its homepage is at |
3474 | more on top of it. It can be found via gem servers. Its homepage is at |
3091 | <http://rev.rubyforge.org/>. |
3475 | <http://rev.rubyforge.org/>. |
|
|
3476 | .Sp |
|
|
3477 | Roger Pack reports that using the link order \f(CW\*(C`\-lws2_32 \-lmsvcrt\-ruby\-190\*(C'\fR |
|
|
3478 | makes rev work even on mingw. |
|
|
3479 | .IP "Haskell" 4 |
|
|
3480 | .IX Item "Haskell" |
|
|
3481 | A haskell binding to libev is available at |
|
|
3482 | <http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev>. |
3092 | .IP "D" 4 |
3483 | .IP "D" 4 |
3093 | .IX Item "D" |
3484 | .IX Item "D" |
3094 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
3485 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
3095 | be found at <http://proj.llucax.com.ar/wiki/evd>. |
3486 | be found at <http://proj.llucax.com.ar/wiki/evd>. |
3096 | .IP "Ocaml" 4 |
3487 | .IP "Ocaml" 4 |
… | |
… | |
3103 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
3494 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
3104 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
3495 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
3105 | .PP |
3496 | .PP |
3106 | To make it easier to write programs that cope with either variant, the |
3497 | To make it easier to write programs that cope with either variant, the |
3107 | following macros are defined: |
3498 | following macros are defined: |
3108 | .ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4 |
3499 | .ie n .IP """EV_A"", ""EV_A_""" 4 |
3109 | .el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4 |
3500 | .el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4 |
3110 | .IX Item "EV_A, EV_A_" |
3501 | .IX Item "EV_A, EV_A_" |
3111 | This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev |
3502 | This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev |
3112 | loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument, |
3503 | loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument, |
3113 | \&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example: |
3504 | \&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example: |
… | |
… | |
3118 | \& ev_loop (EV_A_ 0); |
3509 | \& ev_loop (EV_A_ 0); |
3119 | .Ve |
3510 | .Ve |
3120 | .Sp |
3511 | .Sp |
3121 | It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope, |
3512 | It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope, |
3122 | which is often provided by the following macro. |
3513 | which is often provided by the following macro. |
3123 | .ie n .IP """EV_P""\fR, \f(CW""EV_P_""" 4 |
3514 | .ie n .IP """EV_P"", ""EV_P_""" 4 |
3124 | .el .IP "\f(CWEV_P\fR, \f(CWEV_P_\fR" 4 |
3515 | .el .IP "\f(CWEV_P\fR, \f(CWEV_P_\fR" 4 |
3125 | .IX Item "EV_P, EV_P_" |
3516 | .IX Item "EV_P, EV_P_" |
3126 | This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev |
3517 | This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev |
3127 | loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter, |
3518 | loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter, |
3128 | \&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example: |
3519 | \&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example: |
… | |
… | |
3135 | \& static void cb (EV_P_ ev_timer *w, int revents) |
3526 | \& static void cb (EV_P_ ev_timer *w, int revents) |
3136 | .Ve |
3527 | .Ve |
3137 | .Sp |
3528 | .Sp |
3138 | It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite |
3529 | It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite |
3139 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
3530 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
3140 | .ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4 |
3531 | .ie n .IP """EV_DEFAULT"", ""EV_DEFAULT_""" 4 |
3141 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
3532 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
3142 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
3533 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
3143 | Similar to the other two macros, this gives you the value of the default |
3534 | Similar to the other two macros, this gives you the value of the default |
3144 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). |
3535 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). |
3145 | .ie n .IP """EV_DEFAULT_UC""\fR, \f(CW""EV_DEFAULT_UC_""" 4 |
3536 | .ie n .IP """EV_DEFAULT_UC"", ""EV_DEFAULT_UC_""" 4 |
3146 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
3537 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
3147 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
3538 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
3148 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
3539 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
3149 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
3540 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
3150 | is undefined when the default loop has not been initialised by a previous |
3541 | is undefined when the default loop has not been initialised by a previous |
… | |
… | |
3178 | .PP |
3569 | .PP |
3179 | The goal is to enable you to just copy the necessary files into your |
3570 | The goal is to enable you to just copy the necessary files into your |
3180 | source directory without having to change even a single line in them, so |
3571 | source directory without having to change even a single line in them, so |
3181 | you can easily upgrade by simply copying (or having a checked-out copy of |
3572 | you can easily upgrade by simply copying (or having a checked-out copy of |
3182 | libev somewhere in your source tree). |
3573 | libev somewhere in your source tree). |
3183 | .Sh "\s-1FILESETS\s0" |
3574 | .SS "\s-1FILESETS\s0" |
3184 | .IX Subsection "FILESETS" |
3575 | .IX Subsection "FILESETS" |
3185 | Depending on what features you need you need to include one or more sets of files |
3576 | Depending on what features you need you need to include one or more sets of files |
3186 | in your application. |
3577 | in your application. |
3187 | .PP |
3578 | .PP |
3188 | \fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR |
3579 | \fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR |
… | |
… | |
3267 | For this of course you need the m4 file: |
3658 | For this of course you need the m4 file: |
3268 | .PP |
3659 | .PP |
3269 | .Vb 1 |
3660 | .Vb 1 |
3270 | \& libev.m4 |
3661 | \& libev.m4 |
3271 | .Ve |
3662 | .Ve |
3272 | .Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
3663 | .SS "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
3273 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
3664 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
3274 | Libev can be configured via a variety of preprocessor symbols you have to |
3665 | Libev can be configured via a variety of preprocessor symbols you have to |
3275 | define before including any of its files. The default in the absence of |
3666 | define before including any of its files. The default in the absence of |
3276 | autoconf is documented for every option. |
3667 | autoconf is documented for every option. |
3277 | .IP "\s-1EV_STANDALONE\s0" 4 |
3668 | .IP "\s-1EV_STANDALONE\s0" 4 |
… | |
… | |
3279 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
3670 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
3280 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
3671 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
3281 | implementations for some libevent functions (such as logging, which is not |
3672 | implementations for some libevent functions (such as logging, which is not |
3282 | supported). It will also not define any of the structs usually found in |
3673 | supported). It will also not define any of the structs usually found in |
3283 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
3674 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
|
|
3675 | .Sp |
|
|
3676 | In stanbdalone mode, libev will still try to automatically deduce the |
|
|
3677 | configuration, but has to be more conservative. |
3284 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
3678 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
3285 | .IX Item "EV_USE_MONOTONIC" |
3679 | .IX Item "EV_USE_MONOTONIC" |
3286 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
3680 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
3287 | monotonic clock option at both compile time and runtime. Otherwise no use |
3681 | monotonic clock option at both compile time and runtime. Otherwise no |
3288 | of the monotonic clock option will be attempted. If you enable this, you |
3682 | use of the monotonic clock option will be attempted. If you enable this, |
3289 | usually have to link against librt or something similar. Enabling it when |
3683 | you usually have to link against librt or something similar. Enabling it |
3290 | the functionality isn't available is safe, though, although you have |
3684 | when the functionality isn't available is safe, though, although you have |
3291 | to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR |
3685 | to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR |
3292 | function is hiding in (often \fI\-lrt\fR). |
3686 | function is hiding in (often \fI\-lrt\fR). See also \f(CW\*(C`EV_USE_CLOCK_SYSCALL\*(C'\fR. |
3293 | .IP "\s-1EV_USE_REALTIME\s0" 4 |
3687 | .IP "\s-1EV_USE_REALTIME\s0" 4 |
3294 | .IX Item "EV_USE_REALTIME" |
3688 | .IX Item "EV_USE_REALTIME" |
3295 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
3689 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
3296 | real-time clock option at compile time (and assume its availability at |
3690 | real-time clock option at compile time (and assume its availability |
3297 | runtime if successful). Otherwise no use of the real-time clock option will |
3691 | at runtime if successful). Otherwise no use of the real-time clock |
3298 | be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get |
3692 | option will be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR |
3299 | (CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See the |
3693 | by \f(CW\*(C`clock_get (CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect |
3300 | note about libraries in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though. |
3694 | correctness. See the note about libraries in the description of |
|
|
3695 | \&\f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though. Defaults to the opposite value of |
|
|
3696 | \&\f(CW\*(C`EV_USE_CLOCK_SYSCALL\*(C'\fR. |
|
|
3697 | .IP "\s-1EV_USE_CLOCK_SYSCALL\s0" 4 |
|
|
3698 | .IX Item "EV_USE_CLOCK_SYSCALL" |
|
|
3699 | If defined to be \f(CW1\fR, libev will try to use a direct syscall instead |
|
|
3700 | of calling the system-provided \f(CW\*(C`clock_gettime\*(C'\fR function. This option |
|
|
3701 | exists because on GNU/Linux, \f(CW\*(C`clock_gettime\*(C'\fR is in \f(CW\*(C`librt\*(C'\fR, but \f(CW\*(C`librt\*(C'\fR |
|
|
3702 | unconditionally pulls in \f(CW\*(C`libpthread\*(C'\fR, slowing down single-threaded |
|
|
3703 | programs needlessly. Using a direct syscall is slightly slower (in |
|
|
3704 | theory), because no optimised vdso implementation can be used, but avoids |
|
|
3705 | the pthread dependency. Defaults to \f(CW1\fR on GNU/Linux with glibc 2.x or |
|
|
3706 | higher, as it simplifies linking (no need for \f(CW\*(C`\-lrt\*(C'\fR). |
3301 | .IP "\s-1EV_USE_NANOSLEEP\s0" 4 |
3707 | .IP "\s-1EV_USE_NANOSLEEP\s0" 4 |
3302 | .IX Item "EV_USE_NANOSLEEP" |
3708 | .IX Item "EV_USE_NANOSLEEP" |
3303 | If defined to be \f(CW1\fR, libev will assume that \f(CW\*(C`nanosleep ()\*(C'\fR is available |
3709 | If defined to be \f(CW1\fR, libev will assume that \f(CW\*(C`nanosleep ()\*(C'\fR is available |
3304 | and will use it for delays. Otherwise it will use \f(CW\*(C`select ()\*(C'\fR. |
3710 | and will use it for delays. Otherwise it will use \f(CW\*(C`select ()\*(C'\fR. |
3305 | .IP "\s-1EV_USE_EVENTFD\s0" 4 |
3711 | .IP "\s-1EV_USE_EVENTFD\s0" 4 |
… | |
… | |
3317 | will not be compiled in. |
3723 | will not be compiled in. |
3318 | .IP "\s-1EV_SELECT_USE_FD_SET\s0" 4 |
3724 | .IP "\s-1EV_SELECT_USE_FD_SET\s0" 4 |
3319 | .IX Item "EV_SELECT_USE_FD_SET" |
3725 | .IX Item "EV_SELECT_USE_FD_SET" |
3320 | If defined to \f(CW1\fR, then the select backend will use the system \f(CW\*(C`fd_set\*(C'\fR |
3726 | If defined to \f(CW1\fR, then the select backend will use the system \f(CW\*(C`fd_set\*(C'\fR |
3321 | structure. This is useful if libev doesn't compile due to a missing |
3727 | structure. This is useful if libev doesn't compile due to a missing |
3322 | \&\f(CW\*(C`NFDBITS\*(C'\fR or \f(CW\*(C`fd_mask\*(C'\fR definition or it mis-guesses the bitset layout on |
3728 | \&\f(CW\*(C`NFDBITS\*(C'\fR or \f(CW\*(C`fd_mask\*(C'\fR definition or it mis-guesses the bitset layout |
3323 | exotic systems. This usually limits the range of file descriptors to some |
3729 | on exotic systems. This usually limits the range of file descriptors to |
3324 | low limit such as 1024 or might have other limitations (winsocket only |
3730 | some low limit such as 1024 or might have other limitations (winsocket |
3325 | allows 64 sockets). The \f(CW\*(C`FD_SETSIZE\*(C'\fR macro, set before compilation, might |
3731 | only allows 64 sockets). The \f(CW\*(C`FD_SETSIZE\*(C'\fR macro, set before compilation, |
3326 | influence the size of the \f(CW\*(C`fd_set\*(C'\fR used. |
3732 | configures the maximum size of the \f(CW\*(C`fd_set\*(C'\fR. |
3327 | .IP "\s-1EV_SELECT_IS_WINSOCKET\s0" 4 |
3733 | .IP "\s-1EV_SELECT_IS_WINSOCKET\s0" 4 |
3328 | .IX Item "EV_SELECT_IS_WINSOCKET" |
3734 | .IX Item "EV_SELECT_IS_WINSOCKET" |
3329 | When defined to \f(CW1\fR, the select backend will assume that |
3735 | When defined to \f(CW1\fR, the select backend will assume that |
3330 | select/socket/connect etc. don't understand file descriptors but |
3736 | select/socket/connect etc. don't understand file descriptors but |
3331 | wants osf handles on win32 (this is the case when the select to |
3737 | wants osf handles on win32 (this is the case when the select to |
… | |
… | |
3461 | If undefined or defined to be \f(CW1\fR, then async watchers are supported. If |
3867 | If undefined or defined to be \f(CW1\fR, then async watchers are supported. If |
3462 | defined to be \f(CW0\fR, then they are not. |
3868 | defined to be \f(CW0\fR, then they are not. |
3463 | .IP "\s-1EV_MINIMAL\s0" 4 |
3869 | .IP "\s-1EV_MINIMAL\s0" 4 |
3464 | .IX Item "EV_MINIMAL" |
3870 | .IX Item "EV_MINIMAL" |
3465 | If you need to shave off some kilobytes of code at the expense of some |
3871 | If you need to shave off some kilobytes of code at the expense of some |
3466 | speed, define this symbol to \f(CW1\fR. Currently this is used to override some |
3872 | speed (but with the full \s-1API\s0), define this symbol to \f(CW1\fR. Currently this |
3467 | inlining decisions, saves roughly 30% code size on amd64. It also selects a |
3873 | is used to override some inlining decisions, saves roughly 30% code size |
3468 | much smaller 2\-heap for timer management over the default 4\-heap. |
3874 | on amd64. It also selects a much smaller 2\-heap for timer management over |
|
|
3875 | the default 4\-heap. |
|
|
3876 | .Sp |
|
|
3877 | You can save even more by disabling watcher types you do not need |
|
|
3878 | and setting \f(CW\*(C`EV_MAXPRI\*(C'\fR == \f(CW\*(C`EV_MINPRI\*(C'\fR. Also, disabling \f(CW\*(C`assert\*(C'\fR |
|
|
3879 | (\f(CW\*(C`\-DNDEBUG\*(C'\fR) will usually reduce code size a lot. |
|
|
3880 | .Sp |
|
|
3881 | Defining \f(CW\*(C`EV_MINIMAL\*(C'\fR to \f(CW2\fR will additionally reduce the core \s-1API\s0 to |
|
|
3882 | provide a bare-bones event library. See \f(CW\*(C`ev.h\*(C'\fR for details on what parts |
|
|
3883 | of the \s-1API\s0 are still available, and do not complain if this subset changes |
|
|
3884 | over time. |
3469 | .IP "\s-1EV_PID_HASHSIZE\s0" 4 |
3885 | .IP "\s-1EV_PID_HASHSIZE\s0" 4 |
3470 | .IX Item "EV_PID_HASHSIZE" |
3886 | .IX Item "EV_PID_HASHSIZE" |
3471 | \&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by |
3887 | \&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by |
3472 | pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more |
3888 | pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more |
3473 | than enough. If you need to manage thousands of children you might want to |
3889 | than enough. If you need to manage thousands of children you might want to |
… | |
… | |
3537 | and the way callbacks are invoked and set. Must expand to a struct member |
3953 | and the way callbacks are invoked and set. Must expand to a struct member |
3538 | definition and a statement, respectively. See the \fIev.h\fR header file for |
3954 | definition and a statement, respectively. See the \fIev.h\fR header file for |
3539 | their default definitions. One possible use for overriding these is to |
3955 | their default definitions. One possible use for overriding these is to |
3540 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
3956 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
3541 | method calls instead of plain function calls in \*(C+. |
3957 | method calls instead of plain function calls in \*(C+. |
3542 | .Sh "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" |
3958 | .SS "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" |
3543 | .IX Subsection "EXPORTED API SYMBOLS" |
3959 | .IX Subsection "EXPORTED API SYMBOLS" |
3544 | If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of |
3960 | If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of |
3545 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
3961 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
3546 | all public symbols, one per line: |
3962 | all public symbols, one per line: |
3547 | .PP |
3963 | .PP |
… | |
… | |
3567 | \& #define ev_backend myprefix_ev_backend |
3983 | \& #define ev_backend myprefix_ev_backend |
3568 | \& #define ev_check_start myprefix_ev_check_start |
3984 | \& #define ev_check_start myprefix_ev_check_start |
3569 | \& #define ev_check_stop myprefix_ev_check_stop |
3985 | \& #define ev_check_stop myprefix_ev_check_stop |
3570 | \& ... |
3986 | \& ... |
3571 | .Ve |
3987 | .Ve |
3572 | .Sh "\s-1EXAMPLES\s0" |
3988 | .SS "\s-1EXAMPLES\s0" |
3573 | .IX Subsection "EXAMPLES" |
3989 | .IX Subsection "EXAMPLES" |
3574 | For a real-world example of a program the includes libev |
3990 | For a real-world example of a program the includes libev |
3575 | verbatim, you can have a look at the \s-1EV\s0 perl module |
3991 | verbatim, you can have a look at the \s-1EV\s0 perl module |
3576 | (<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
3992 | (<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
3577 | the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public |
3993 | the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public |
… | |
… | |
3602 | \& #include "ev_cpp.h" |
4018 | \& #include "ev_cpp.h" |
3603 | \& #include "ev.c" |
4019 | \& #include "ev.c" |
3604 | .Ve |
4020 | .Ve |
3605 | .SH "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" |
4021 | .SH "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" |
3606 | .IX Header "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" |
4022 | .IX Header "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" |
3607 | .Sh "\s-1THREADS\s0 \s-1AND\s0 \s-1COROUTINES\s0" |
4023 | .SS "\s-1THREADS\s0 \s-1AND\s0 \s-1COROUTINES\s0" |
3608 | .IX Subsection "THREADS AND COROUTINES" |
4024 | .IX Subsection "THREADS AND COROUTINES" |
3609 | \fI\s-1THREADS\s0\fR |
4025 | \fI\s-1THREADS\s0\fR |
3610 | .IX Subsection "THREADS" |
4026 | .IX Subsection "THREADS" |
3611 | .PP |
4027 | .PP |
3612 | All libev functions are reentrant and thread-safe unless explicitly |
4028 | All libev functions are reentrant and thread-safe unless explicitly |
… | |
… | |
3658 | An example use would be to communicate signals or other events that only |
4074 | An example use would be to communicate signals or other events that only |
3659 | work in the default loop by registering the signal watcher with the |
4075 | work in the default loop by registering the signal watcher with the |
3660 | default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop |
4076 | default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop |
3661 | watcher callback into the event loop interested in the signal. |
4077 | watcher callback into the event loop interested in the signal. |
3662 | .PP |
4078 | .PP |
|
|
4079 | \s-1THREAD\s0 \s-1LOCKING\s0 \s-1EXAMPLE\s0 |
|
|
4080 | .IX Subsection "THREAD LOCKING EXAMPLE" |
|
|
4081 | .PP |
|
|
4082 | Here is a fictitious example of how to run an event loop in a different |
|
|
4083 | thread than where callbacks are being invoked and watchers are |
|
|
4084 | created/added/removed. |
|
|
4085 | .PP |
|
|
4086 | For a real-world example, see the \f(CW\*(C`EV::Loop::Async\*(C'\fR perl module, |
|
|
4087 | which uses exactly this technique (which is suited for many high-level |
|
|
4088 | languages). |
|
|
4089 | .PP |
|
|
4090 | The example uses a pthread mutex to protect the loop data, a condition |
|
|
4091 | variable to wait for callback invocations, an async watcher to notify the |
|
|
4092 | event loop thread and an unspecified mechanism to wake up the main thread. |
|
|
4093 | .PP |
|
|
4094 | First, you need to associate some data with the event loop: |
|
|
4095 | .PP |
|
|
4096 | .Vb 6 |
|
|
4097 | \& typedef struct { |
|
|
4098 | \& mutex_t lock; /* global loop lock */ |
|
|
4099 | \& ev_async async_w; |
|
|
4100 | \& thread_t tid; |
|
|
4101 | \& cond_t invoke_cv; |
|
|
4102 | \& } userdata; |
|
|
4103 | \& |
|
|
4104 | \& void prepare_loop (EV_P) |
|
|
4105 | \& { |
|
|
4106 | \& // for simplicity, we use a static userdata struct. |
|
|
4107 | \& static userdata u; |
|
|
4108 | \& |
|
|
4109 | \& ev_async_init (&u\->async_w, async_cb); |
|
|
4110 | \& ev_async_start (EV_A_ &u\->async_w); |
|
|
4111 | \& |
|
|
4112 | \& pthread_mutex_init (&u\->lock, 0); |
|
|
4113 | \& pthread_cond_init (&u\->invoke_cv, 0); |
|
|
4114 | \& |
|
|
4115 | \& // now associate this with the loop |
|
|
4116 | \& ev_set_userdata (EV_A_ u); |
|
|
4117 | \& ev_set_invoke_pending_cb (EV_A_ l_invoke); |
|
|
4118 | \& ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
|
|
4119 | \& |
|
|
4120 | \& // then create the thread running ev_loop |
|
|
4121 | \& pthread_create (&u\->tid, 0, l_run, EV_A); |
|
|
4122 | \& } |
|
|
4123 | .Ve |
|
|
4124 | .PP |
|
|
4125 | The callback for the \f(CW\*(C`ev_async\*(C'\fR watcher does nothing: the watcher is used |
|
|
4126 | solely to wake up the event loop so it takes notice of any new watchers |
|
|
4127 | that might have been added: |
|
|
4128 | .PP |
|
|
4129 | .Vb 5 |
|
|
4130 | \& static void |
|
|
4131 | \& async_cb (EV_P_ ev_async *w, int revents) |
|
|
4132 | \& { |
|
|
4133 | \& // just used for the side effects |
|
|
4134 | \& } |
|
|
4135 | .Ve |
|
|
4136 | .PP |
|
|
4137 | The \f(CW\*(C`l_release\*(C'\fR and \f(CW\*(C`l_acquire\*(C'\fR callbacks simply unlock/lock the mutex |
|
|
4138 | protecting the loop data, respectively. |
|
|
4139 | .PP |
|
|
4140 | .Vb 6 |
|
|
4141 | \& static void |
|
|
4142 | \& l_release (EV_P) |
|
|
4143 | \& { |
|
|
4144 | \& userdata *u = ev_userdata (EV_A); |
|
|
4145 | \& pthread_mutex_unlock (&u\->lock); |
|
|
4146 | \& } |
|
|
4147 | \& |
|
|
4148 | \& static void |
|
|
4149 | \& l_acquire (EV_P) |
|
|
4150 | \& { |
|
|
4151 | \& userdata *u = ev_userdata (EV_A); |
|
|
4152 | \& pthread_mutex_lock (&u\->lock); |
|
|
4153 | \& } |
|
|
4154 | .Ve |
|
|
4155 | .PP |
|
|
4156 | The event loop thread first acquires the mutex, and then jumps straight |
|
|
4157 | into \f(CW\*(C`ev_loop\*(C'\fR: |
|
|
4158 | .PP |
|
|
4159 | .Vb 4 |
|
|
4160 | \& void * |
|
|
4161 | \& l_run (void *thr_arg) |
|
|
4162 | \& { |
|
|
4163 | \& struct ev_loop *loop = (struct ev_loop *)thr_arg; |
|
|
4164 | \& |
|
|
4165 | \& l_acquire (EV_A); |
|
|
4166 | \& pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
|
|
4167 | \& ev_loop (EV_A_ 0); |
|
|
4168 | \& l_release (EV_A); |
|
|
4169 | \& |
|
|
4170 | \& return 0; |
|
|
4171 | \& } |
|
|
4172 | .Ve |
|
|
4173 | .PP |
|
|
4174 | Instead of invoking all pending watchers, the \f(CW\*(C`l_invoke\*(C'\fR callback will |
|
|
4175 | signal the main thread via some unspecified mechanism (signals? pipe |
|
|
4176 | writes? \f(CW\*(C`Async::Interrupt\*(C'\fR?) and then waits until all pending watchers |
|
|
4177 | have been called (in a while loop because a) spurious wakeups are possible |
|
|
4178 | and b) skipping inter-thread-communication when there are no pending |
|
|
4179 | watchers is very beneficial): |
|
|
4180 | .PP |
|
|
4181 | .Vb 4 |
|
|
4182 | \& static void |
|
|
4183 | \& l_invoke (EV_P) |
|
|
4184 | \& { |
|
|
4185 | \& userdata *u = ev_userdata (EV_A); |
|
|
4186 | \& |
|
|
4187 | \& while (ev_pending_count (EV_A)) |
|
|
4188 | \& { |
|
|
4189 | \& wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
|
|
4190 | \& pthread_cond_wait (&u\->invoke_cv, &u\->lock); |
|
|
4191 | \& } |
|
|
4192 | \& } |
|
|
4193 | .Ve |
|
|
4194 | .PP |
|
|
4195 | Now, whenever the main thread gets told to invoke pending watchers, it |
|
|
4196 | will grab the lock, call \f(CW\*(C`ev_invoke_pending\*(C'\fR and then signal the loop |
|
|
4197 | thread to continue: |
|
|
4198 | .PP |
|
|
4199 | .Vb 4 |
|
|
4200 | \& static void |
|
|
4201 | \& real_invoke_pending (EV_P) |
|
|
4202 | \& { |
|
|
4203 | \& userdata *u = ev_userdata (EV_A); |
|
|
4204 | \& |
|
|
4205 | \& pthread_mutex_lock (&u\->lock); |
|
|
4206 | \& ev_invoke_pending (EV_A); |
|
|
4207 | \& pthread_cond_signal (&u\->invoke_cv); |
|
|
4208 | \& pthread_mutex_unlock (&u\->lock); |
|
|
4209 | \& } |
|
|
4210 | .Ve |
|
|
4211 | .PP |
|
|
4212 | Whenever you want to start/stop a watcher or do other modifications to an |
|
|
4213 | event loop, you will now have to lock: |
|
|
4214 | .PP |
|
|
4215 | .Vb 2 |
|
|
4216 | \& ev_timer timeout_watcher; |
|
|
4217 | \& userdata *u = ev_userdata (EV_A); |
|
|
4218 | \& |
|
|
4219 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
|
|
4220 | \& |
|
|
4221 | \& pthread_mutex_lock (&u\->lock); |
|
|
4222 | \& ev_timer_start (EV_A_ &timeout_watcher); |
|
|
4223 | \& ev_async_send (EV_A_ &u\->async_w); |
|
|
4224 | \& pthread_mutex_unlock (&u\->lock); |
|
|
4225 | .Ve |
|
|
4226 | .PP |
|
|
4227 | Note that sending the \f(CW\*(C`ev_async\*(C'\fR watcher is required because otherwise |
|
|
4228 | an event loop currently blocking in the kernel will have no knowledge |
|
|
4229 | about the newly added timer. By waking up the loop it will pick up any new |
|
|
4230 | watchers in the next event loop iteration. |
|
|
4231 | .PP |
3663 | \fI\s-1COROUTINES\s0\fR |
4232 | \fI\s-1COROUTINES\s0\fR |
3664 | .IX Subsection "COROUTINES" |
4233 | .IX Subsection "COROUTINES" |
3665 | .PP |
4234 | .PP |
3666 | Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): |
4235 | Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): |
3667 | libev fully supports nesting calls to its functions from different |
4236 | libev fully supports nesting calls to its functions from different |
3668 | coroutines (e.g. you can call \f(CW\*(C`ev_loop\*(C'\fR on the same loop from two |
4237 | coroutines (e.g. you can call \f(CW\*(C`ev_loop\*(C'\fR on the same loop from two |
3669 | different coroutines, and switch freely between both coroutines running the |
4238 | different coroutines, and switch freely between both coroutines running |
3670 | loop, as long as you don't confuse yourself). The only exception is that |
4239 | the loop, as long as you don't confuse yourself). The only exception is |
3671 | you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
4240 | that you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
3672 | .PP |
4241 | .PP |
3673 | Care has been taken to ensure that libev does not keep local state inside |
4242 | Care has been taken to ensure that libev does not keep local state inside |
3674 | \&\f(CW\*(C`ev_loop\*(C'\fR, and other calls do not usually allow for coroutine switches as |
4243 | \&\f(CW\*(C`ev_loop\*(C'\fR, and other calls do not usually allow for coroutine switches as |
3675 | they do not call any callbacks. |
4244 | they do not call any callbacks. |
3676 | .Sh "\s-1COMPILER\s0 \s-1WARNINGS\s0" |
4245 | .SS "\s-1COMPILER\s0 \s-1WARNINGS\s0" |
3677 | .IX Subsection "COMPILER WARNINGS" |
4246 | .IX Subsection "COMPILER WARNINGS" |
3678 | Depending on your compiler and compiler settings, you might get no or a |
4247 | Depending on your compiler and compiler settings, you might get no or a |
3679 | lot of warnings when compiling libev code. Some people are apparently |
4248 | lot of warnings when compiling libev code. Some people are apparently |
3680 | scared by this. |
4249 | scared by this. |
3681 | .PP |
4250 | .PP |
… | |
… | |
3698 | While libev is written to generate as few warnings as possible, |
4267 | While libev is written to generate as few warnings as possible, |
3699 | \&\*(L"warn-free\*(R" code is not a goal, and it is recommended not to build libev |
4268 | \&\*(L"warn-free\*(R" code is not a goal, and it is recommended not to build libev |
3700 | with any compiler warnings enabled unless you are prepared to cope with |
4269 | with any compiler warnings enabled unless you are prepared to cope with |
3701 | them (e.g. by ignoring them). Remember that warnings are just that: |
4270 | them (e.g. by ignoring them). Remember that warnings are just that: |
3702 | warnings, not errors, or proof of bugs. |
4271 | warnings, not errors, or proof of bugs. |
3703 | .Sh "\s-1VALGRIND\s0" |
4272 | .SS "\s-1VALGRIND\s0" |
3704 | .IX Subsection "VALGRIND" |
4273 | .IX Subsection "VALGRIND" |
3705 | Valgrind has a special section here because it is a popular tool that is |
4274 | Valgrind has a special section here because it is a popular tool that is |
3706 | highly useful. Unfortunately, valgrind reports are very hard to interpret. |
4275 | highly useful. Unfortunately, valgrind reports are very hard to interpret. |
3707 | .PP |
4276 | .PP |
3708 | If you think you found a bug (memory leak, uninitialised data access etc.) |
4277 | If you think you found a bug (memory leak, uninitialised data access etc.) |
… | |
… | |
3733 | .PP |
4302 | .PP |
3734 | If you need, for some reason, empty reports from valgrind for your project |
4303 | If you need, for some reason, empty reports from valgrind for your project |
3735 | I suggest using suppression lists. |
4304 | I suggest using suppression lists. |
3736 | .SH "PORTABILITY NOTES" |
4305 | .SH "PORTABILITY NOTES" |
3737 | .IX Header "PORTABILITY NOTES" |
4306 | .IX Header "PORTABILITY NOTES" |
3738 | .Sh "\s-1WIN32\s0 \s-1PLATFORM\s0 \s-1LIMITATIONS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" |
4307 | .SS "\s-1WIN32\s0 \s-1PLATFORM\s0 \s-1LIMITATIONS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" |
3739 | .IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" |
4308 | .IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" |
3740 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
4309 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
3741 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
4310 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
3742 | model. Libev still offers limited functionality on this platform in |
4311 | model. Libev still offers limited functionality on this platform in |
3743 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
4312 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
… | |
… | |
3750 | way (note also that glib is the slowest event library known to man). |
4319 | way (note also that glib is the slowest event library known to man). |
3751 | .PP |
4320 | .PP |
3752 | There is no supported compilation method available on windows except |
4321 | There is no supported compilation method available on windows except |
3753 | embedding it into other applications. |
4322 | embedding it into other applications. |
3754 | .PP |
4323 | .PP |
|
|
4324 | Sensible signal handling is officially unsupported by Microsoft \- libev |
|
|
4325 | tries its best, but under most conditions, signals will simply not work. |
|
|
4326 | .PP |
3755 | Not a libev limitation but worth mentioning: windows apparently doesn't |
4327 | Not a libev limitation but worth mentioning: windows apparently doesn't |
3756 | accept large writes: instead of resulting in a partial write, windows will |
4328 | accept large writes: instead of resulting in a partial write, windows will |
3757 | either accept everything or return \f(CW\*(C`ENOBUFS\*(C'\fR if the buffer is too large, |
4329 | either accept everything or return \f(CW\*(C`ENOBUFS\*(C'\fR if the buffer is too large, |
3758 | so make sure you only write small amounts into your sockets (less than a |
4330 | so make sure you only write small amounts into your sockets (less than a |
3759 | megabyte seems safe, but this apparently depends on the amount of memory |
4331 | megabyte seems safe, but this apparently depends on the amount of memory |
… | |
… | |
3763 | the abysmal performance of winsockets, using a large number of sockets |
4335 | the abysmal performance of winsockets, using a large number of sockets |
3764 | is not recommended (and not reasonable). If your program needs to use |
4336 | is not recommended (and not reasonable). If your program needs to use |
3765 | more than a hundred or so sockets, then likely it needs to use a totally |
4337 | more than a hundred or so sockets, then likely it needs to use a totally |
3766 | different implementation for windows, as libev offers the \s-1POSIX\s0 readiness |
4338 | different implementation for windows, as libev offers the \s-1POSIX\s0 readiness |
3767 | notification model, which cannot be implemented efficiently on windows |
4339 | notification model, which cannot be implemented efficiently on windows |
3768 | (Microsoft monopoly games). |
4340 | (due to Microsoft monopoly games). |
3769 | .PP |
4341 | .PP |
3770 | A typical way to use libev under windows is to embed it (see the embedding |
4342 | A typical way to use libev under windows is to embed it (see the embedding |
3771 | section for details) and use the following \fIevwrap.h\fR header file instead |
4343 | section for details) and use the following \fIevwrap.h\fR header file instead |
3772 | of \fIev.h\fR: |
4344 | of \fIev.h\fR: |
3773 | .PP |
4345 | .PP |
… | |
… | |
3811 | .Sp |
4383 | .Sp |
3812 | Early versions of winsocket's select only supported waiting for a maximum |
4384 | Early versions of winsocket's select only supported waiting for a maximum |
3813 | of \f(CW64\fR handles (probably owning to the fact that all windows kernels |
4385 | of \f(CW64\fR handles (probably owning to the fact that all windows kernels |
3814 | can only wait for \f(CW64\fR things at the same time internally; Microsoft |
4386 | can only wait for \f(CW64\fR things at the same time internally; Microsoft |
3815 | recommends spawning a chain of threads and wait for 63 handles and the |
4387 | recommends spawning a chain of threads and wait for 63 handles and the |
3816 | previous thread in each. Great). |
4388 | previous thread in each. Sounds great!). |
3817 | .Sp |
4389 | .Sp |
3818 | Newer versions support more handles, but you need to define \f(CW\*(C`FD_SETSIZE\*(C'\fR |
4390 | Newer versions support more handles, but you need to define \f(CW\*(C`FD_SETSIZE\*(C'\fR |
3819 | to some high number (e.g. \f(CW2048\fR) before compiling the winsocket select |
4391 | to some high number (e.g. \f(CW2048\fR) before compiling the winsocket select |
3820 | call (which might be in libev or elsewhere, for example, perl does its own |
4392 | call (which might be in libev or elsewhere, for example, perl and many |
3821 | select emulation on windows). |
4393 | other interpreters do their own select emulation on windows). |
3822 | .Sp |
4394 | .Sp |
3823 | Another limit is the number of file descriptors in the Microsoft runtime |
4395 | Another limit is the number of file descriptors in the Microsoft runtime |
3824 | libraries, which by default is \f(CW64\fR (there must be a hidden \fI64\fR fetish |
4396 | libraries, which by default is \f(CW64\fR (there must be a hidden \fI64\fR |
3825 | or something like this inside Microsoft). You can increase this by calling |
4397 | fetish or something like this inside Microsoft). You can increase this |
3826 | \&\f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR (another |
4398 | by calling \f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR |
3827 | arbitrary limit), but is broken in many versions of the Microsoft runtime |
4399 | (another arbitrary limit), but is broken in many versions of the Microsoft |
3828 | libraries. |
|
|
3829 | .Sp |
|
|
3830 | This might get you to about \f(CW512\fR or \f(CW2048\fR sockets (depending on |
4400 | runtime libraries. This might get you to about \f(CW512\fR or \f(CW2048\fR sockets |
3831 | windows version and/or the phase of the moon). To get more, you need to |
4401 | (depending on windows version and/or the phase of the moon). To get more, |
3832 | wrap all I/O functions and provide your own fd management, but the cost of |
4402 | you need to wrap all I/O functions and provide your own fd management, but |
3833 | calling select (O(nA\*^X)) will likely make this unworkable. |
4403 | the cost of calling select (O(nA\*^X)) will likely make this unworkable. |
3834 | .Sh "\s-1PORTABILITY\s0 \s-1REQUIREMENTS\s0" |
4404 | .SS "\s-1PORTABILITY\s0 \s-1REQUIREMENTS\s0" |
3835 | .IX Subsection "PORTABILITY REQUIREMENTS" |
4405 | .IX Subsection "PORTABILITY REQUIREMENTS" |
3836 | In addition to a working ISO-C implementation and of course the |
4406 | In addition to a working ISO-C implementation and of course the |
3837 | backend-specific APIs, libev relies on a few additional extensions: |
4407 | backend-specific APIs, libev relies on a few additional extensions: |
3838 | .ie n .IP """void (*)(ev_watcher_type *, int revents)""\fR must have compatible calling conventions regardless of \f(CW""ev_watcher_type *""." 4 |
4408 | .ie n .IP """void (*)(ev_watcher_type *, int revents)"" must have compatible calling conventions regardless of ""ev_watcher_type *""." 4 |
3839 | .el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4 |
4409 | .el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4 |
3840 | .IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *." |
4410 | .IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *." |
3841 | Libev assumes not only that all watcher pointers have the same internal |
4411 | Libev assumes not only that all watcher pointers have the same internal |
3842 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO\s0 C for example), but it also |
4412 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO\s0 C for example), but it also |
3843 | assumes that the same (machine) code can be used to call any watcher |
4413 | assumes that the same (machine) code can be used to call any watcher |
… | |
… | |
3875 | .el .IP "\f(CWdouble\fR must hold a time value in seconds with enough accuracy" 4 |
4445 | .el .IP "\f(CWdouble\fR must hold a time value in seconds with enough accuracy" 4 |
3876 | .IX Item "double must hold a time value in seconds with enough accuracy" |
4446 | .IX Item "double must hold a time value in seconds with enough accuracy" |
3877 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
4447 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
3878 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
4448 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
3879 | enough for at least into the year 4000. This requirement is fulfilled by |
4449 | enough for at least into the year 4000. This requirement is fulfilled by |
3880 | implementations implementing \s-1IEEE\s0 754 (basically all existing ones). |
4450 | implementations implementing \s-1IEEE\s0 754, which is basically all existing |
|
|
4451 | ones. With \s-1IEEE\s0 754 doubles, you get microsecond accuracy until at least |
|
|
4452 | 2200. |
3881 | .PP |
4453 | .PP |
3882 | If you know of other additional requirements drop me a note. |
4454 | If you know of other additional requirements drop me a note. |
3883 | .SH "ALGORITHMIC COMPLEXITIES" |
4455 | .SH "ALGORITHMIC COMPLEXITIES" |
3884 | .IX Header "ALGORITHMIC COMPLEXITIES" |
4456 | .IX Header "ALGORITHMIC COMPLEXITIES" |
3885 | In this section the complexities of (many of) the algorithms used inside |
4457 | In this section the complexities of (many of) the algorithms used inside |
… | |
… | |
3941 | .IX Item "Processing signals: O(max_signal_number)" |
4513 | .IX Item "Processing signals: O(max_signal_number)" |
3942 | .PD |
4514 | .PD |
3943 | Sending involves a system call \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
4515 | Sending involves a system call \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
3944 | calls in the current loop iteration. Checking for async and signal events |
4516 | calls in the current loop iteration. Checking for async and signal events |
3945 | involves iterating over all running async watchers or all signal numbers. |
4517 | involves iterating over all running async watchers or all signal numbers. |
|
|
4518 | .SH "GLOSSARY" |
|
|
4519 | .IX Header "GLOSSARY" |
|
|
4520 | .IP "active" 4 |
|
|
4521 | .IX Item "active" |
|
|
4522 | A watcher is active as long as it has been started (has been attached to |
|
|
4523 | an event loop) but not yet stopped (disassociated from the event loop). |
|
|
4524 | .IP "application" 4 |
|
|
4525 | .IX Item "application" |
|
|
4526 | In this document, an application is whatever is using libev. |
|
|
4527 | .IP "callback" 4 |
|
|
4528 | .IX Item "callback" |
|
|
4529 | The address of a function that is called when some event has been |
|
|
4530 | detected. Callbacks are being passed the event loop, the watcher that |
|
|
4531 | received the event, and the actual event bitset. |
|
|
4532 | .IP "callback invocation" 4 |
|
|
4533 | .IX Item "callback invocation" |
|
|
4534 | The act of calling the callback associated with a watcher. |
|
|
4535 | .IP "event" 4 |
|
|
4536 | .IX Item "event" |
|
|
4537 | A change of state of some external event, such as data now being available |
|
|
4538 | for reading on a file descriptor, time having passed or simply not having |
|
|
4539 | any other events happening anymore. |
|
|
4540 | .Sp |
|
|
4541 | In libev, events are represented as single bits (such as \f(CW\*(C`EV_READ\*(C'\fR or |
|
|
4542 | \&\f(CW\*(C`EV_TIMEOUT\*(C'\fR). |
|
|
4543 | .IP "event library" 4 |
|
|
4544 | .IX Item "event library" |
|
|
4545 | A software package implementing an event model and loop. |
|
|
4546 | .IP "event loop" 4 |
|
|
4547 | .IX Item "event loop" |
|
|
4548 | An entity that handles and processes external events and converts them |
|
|
4549 | into callback invocations. |
|
|
4550 | .IP "event model" 4 |
|
|
4551 | .IX Item "event model" |
|
|
4552 | The model used to describe how an event loop handles and processes |
|
|
4553 | watchers and events. |
|
|
4554 | .IP "pending" 4 |
|
|
4555 | .IX Item "pending" |
|
|
4556 | A watcher is pending as soon as the corresponding event has been detected, |
|
|
4557 | and stops being pending as soon as the watcher will be invoked or its |
|
|
4558 | pending status is explicitly cleared by the application. |
|
|
4559 | .Sp |
|
|
4560 | A watcher can be pending, but not active. Stopping a watcher also clears |
|
|
4561 | its pending status. |
|
|
4562 | .IP "real time" 4 |
|
|
4563 | .IX Item "real time" |
|
|
4564 | The physical time that is observed. It is apparently strictly monotonic :) |
|
|
4565 | .IP "wall-clock time" 4 |
|
|
4566 | .IX Item "wall-clock time" |
|
|
4567 | The time and date as shown on clocks. Unlike real time, it can actually |
|
|
4568 | be wrong and jump forwards and backwards, e.g. when the you adjust your |
|
|
4569 | clock. |
|
|
4570 | .IP "watcher" 4 |
|
|
4571 | .IX Item "watcher" |
|
|
4572 | A data structure that describes interest in certain events. Watchers need |
|
|
4573 | to be started (attached to an event loop) before they can receive events. |
|
|
4574 | .IP "watcher invocation" 4 |
|
|
4575 | .IX Item "watcher invocation" |
|
|
4576 | The act of calling the callback associated with a watcher. |
3946 | .SH "AUTHOR" |
4577 | .SH "AUTHOR" |
3947 | .IX Header "AUTHOR" |
4578 | .IX Header "AUTHOR" |
3948 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |
4579 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |