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12 | .. |
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132 | .\" ======================================================================== |
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134 | .IX Title "LIBEV 3" |
126 | .IX Title "LIBEV 3" |
135 | .TH LIBEV 3 "2009-02-06" "libev-3.53" "libev - high performance full featured event loop" |
127 | .TH LIBEV 3 "2009-07-27" "libev-3.8" "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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201 | \& |
193 | \& |
202 | \& // unloop was called, so exit |
194 | \& // unloop was called, so exit |
203 | \& return 0; |
195 | \& return 0; |
204 | \& } |
196 | \& } |
205 | .Ve |
197 | .Ve |
206 | .SH "DESCRIPTION" |
198 | .SH "ABOUT THIS DOCUMENT" |
207 | .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 |
208 | 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 |
209 | 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 |
210 | 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>. |
211 | .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" |
212 | 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 |
213 | 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 |
214 | these event sources and provide your program with events. |
217 | these event sources and provide your program with events. |
215 | .PP |
218 | .PP |
216 | 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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219 | .PP |
222 | .PP |
220 | You register interest in certain events by registering so-called \fIevent |
223 | You register interest in certain events by registering so-called \fIevent |
221 | 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 |
222 | 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 |
223 | watcher. |
226 | watcher. |
224 | .Sh "\s-1FEATURES\s0" |
227 | .SS "\s-1FEATURES\s0" |
225 | .IX Subsection "FEATURES" |
228 | .IX Subsection "FEATURES" |
226 | 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 |
227 | 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 |
228 | 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 |
229 | (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), Linux eventfd/signalfd (for faster and cleaner |
230 | with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals |
233 | inter-thread wakeup (\f(CW\*(C`ev_async\*(C'\fR)/signal handling (\f(CW\*(C`ev_signal\*(C'\fR)) relative |
231 | (\f(CW\*(C`ev_signal\*(C'\fR), process status change events (\f(CW\*(C`ev_child\*(C'\fR), and event |
234 | timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers with customised rescheduling |
232 | watchers dealing with the event loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR, |
235 | (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals (\f(CW\*(C`ev_signal\*(C'\fR), process status |
233 | \&\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 | change events (\f(CW\*(C`ev_child\*(C'\fR), and event watchers dealing with the event |
234 | file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events |
237 | loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR, \f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and |
235 | (\f(CW\*(C`ev_fork\*(C'\fR). |
238 | \&\f(CW\*(C`ev_check\*(C'\fR watchers) as well as file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even |
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239 | limited support for fork events (\f(CW\*(C`ev_fork\*(C'\fR). |
236 | .PP |
240 | .PP |
237 | It also is quite fast (see this |
241 | It also is quite fast (see this |
238 | benchmark comparing it to libevent |
242 | <benchmark> comparing it to libevent |
239 | for example). |
243 | for example). |
240 | .Sh "\s-1CONVENTIONS\s0" |
244 | .SS "\s-1CONVENTIONS\s0" |
241 | .IX Subsection "CONVENTIONS" |
245 | .IX Subsection "CONVENTIONS" |
242 | Libev is very configurable. In this manual the default (and most common) |
246 | Libev is very configurable. In this manual the default (and most common) |
243 | configuration will be described, which supports multiple event loops. For |
247 | configuration will be described, which supports multiple event loops. For |
244 | more info about various configuration options please have a look at |
248 | more info about various configuration options please have a look at |
245 | \&\fB\s-1EMBED\s0\fR section in this manual. If libev was configured without support |
249 | \&\fB\s-1EMBED\s0\fR section in this manual. If libev was configured without support |
246 | for multiple event loops, then all functions taking an initial argument of |
250 | for multiple event loops, then all functions taking an initial argument of |
247 | name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`ev_loop *\*(C'\fR) will not have |
251 | name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`ev_loop *\*(C'\fR) will not have |
248 | this argument. |
252 | this argument. |
249 | .Sh "\s-1TIME\s0 \s-1REPRESENTATION\s0" |
253 | .SS "\s-1TIME\s0 \s-1REPRESENTATION\s0" |
250 | .IX Subsection "TIME REPRESENTATION" |
254 | .IX Subsection "TIME REPRESENTATION" |
251 | Libev represents time as a single floating point number, representing the |
255 | Libev represents time as a single floating point number, representing |
252 | (fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near |
256 | the (fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere |
253 | the beginning of 1970, details are complicated, don't ask). This type is |
257 | near the beginning of 1970, details are complicated, don't ask). This |
254 | called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually aliases |
258 | type is called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually |
255 | to the \f(CW\*(C`double\*(C'\fR type in C, and when you need to do any calculations on |
259 | aliases to the \f(CW\*(C`double\*(C'\fR type in C. When you need to do any calculations |
256 | it, you should treat it as some floating point value. Unlike the name |
260 | on it, you should treat it as some floating point value. Unlike the name |
257 | component \f(CW\*(C`stamp\*(C'\fR might indicate, it is also used for time differences |
261 | component \f(CW\*(C`stamp\*(C'\fR might indicate, it is also used for time differences |
258 | throughout libev. |
262 | throughout libev. |
259 | .SH "ERROR HANDLING" |
263 | .SH "ERROR HANDLING" |
260 | .IX Header "ERROR HANDLING" |
264 | .IX Header "ERROR HANDLING" |
261 | Libev knows three classes of errors: operating system errors, usage errors |
265 | Libev knows three classes of errors: operating system errors, usage errors |
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475 | forget about forgetting to tell libev about forking) when you use this |
479 | forget about forgetting to tell libev about forking) when you use this |
476 | flag. |
480 | flag. |
477 | .Sp |
481 | .Sp |
478 | This flag setting cannot be overridden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR |
482 | This flag setting cannot be overridden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR |
479 | environment variable. |
483 | environment variable. |
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484 | .ie n .IP """EVFLAG_NOINOTIFY""" 4 |
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485 | .el .IP "\f(CWEVFLAG_NOINOTIFY\fR" 4 |
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486 | .IX Item "EVFLAG_NOINOTIFY" |
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487 | When this flag is specified, then libev will not attempt to use the |
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488 | \&\fIinotify\fR \s-1API\s0 for it's \f(CW\*(C`ev_stat\*(C'\fR watchers. Apart from debugging and |
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489 | testing, this flag can be useful to conserve inotify file descriptors, as |
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490 | otherwise each loop using \f(CW\*(C`ev_stat\*(C'\fR watchers consumes one inotify handle. |
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491 | .ie n .IP """EVFLAG_NOSIGNALFD""" 4 |
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492 | .el .IP "\f(CWEVFLAG_NOSIGNALFD\fR" 4 |
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493 | .IX Item "EVFLAG_NOSIGNALFD" |
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494 | When this flag is specified, then libev will not attempt to use the |
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495 | \&\fIsignalfd\fR \s-1API\s0 for it's \f(CW\*(C`ev_signal\*(C'\fR (and \f(CW\*(C`ev_child\*(C'\fR) watchers. This is |
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496 | probably only useful to work around any bugs in libev. Consequently, this |
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497 | flag might go away once the signalfd functionality is considered stable, |
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498 | so it's useful mostly in environment variables and not in program code. |
480 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
499 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
481 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
500 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
482 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
501 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
483 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
502 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
484 | libev tries to roll its own fd_set with no limits on the number of fds, |
503 | libev tries to roll its own fd_set with no limits on the number of fds, |
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632 | .Sp |
651 | .Sp |
633 | It is definitely not recommended to use this flag. |
652 | It is definitely not recommended to use this flag. |
634 | .RE |
653 | .RE |
635 | .RS 4 |
654 | .RS 4 |
636 | .Sp |
655 | .Sp |
637 | If one or more of these are or'ed into the flags value, then only these |
656 | If one or more of the backend flags are or'ed into the flags value, |
638 | backends will be tried (in the reverse order as listed here). If none are |
657 | then only these backends will be tried (in the reverse order as listed |
639 | specified, all backends in \f(CW\*(C`ev_recommended_backends ()\*(C'\fR will be tried. |
658 | here). If none are specified, all backends in \f(CW\*(C`ev_recommended_backends |
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659 | ()\*(C'\fR will be tried. |
640 | .Sp |
660 | .Sp |
641 | Example: This is the most typical usage. |
661 | Example: This is the most typical usage. |
642 | .Sp |
662 | .Sp |
643 | .Vb 2 |
663 | .Vb 2 |
644 | \& if (!ev_default_loop (0)) |
664 | \& if (!ev_default_loop (0)) |
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738 | happily wraps around with enough iterations. |
758 | happily wraps around with enough iterations. |
739 | .Sp |
759 | .Sp |
740 | This value can sometimes be useful as a generation counter of sorts (it |
760 | This value can sometimes be useful as a generation counter of sorts (it |
741 | \&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with |
761 | \&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with |
742 | \&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls. |
762 | \&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls. |
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763 | .IP "unsigned int ev_loop_depth (loop)" 4 |
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764 | .IX Item "unsigned int ev_loop_depth (loop)" |
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765 | Returns the number of times \f(CW\*(C`ev_loop\*(C'\fR was entered minus the number of |
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766 | times \f(CW\*(C`ev_loop\*(C'\fR was exited, in other words, the recursion depth. |
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767 | .Sp |
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768 | Outside \f(CW\*(C`ev_loop\*(C'\fR, this number is zero. In a callback, this number is |
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769 | \&\f(CW1\fR, unless \f(CW\*(C`ev_loop\*(C'\fR was invoked recursively (or from another thread), |
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770 | in which case it is higher. |
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771 | .Sp |
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772 | Leaving \f(CW\*(C`ev_loop\*(C'\fR abnormally (setjmp/longjmp, cancelling the thread |
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773 | etc.), doesn't count as exit. |
743 | .IP "unsigned int ev_backend (loop)" 4 |
774 | .IP "unsigned int ev_backend (loop)" 4 |
744 | .IX Item "unsigned int ev_backend (loop)" |
775 | .IX Item "unsigned int ev_backend (loop)" |
745 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
776 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
746 | use. |
777 | use. |
747 | .IP "ev_tstamp ev_now (loop)" 4 |
778 | .IP "ev_tstamp ev_now (loop)" 4 |
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760 | This function is rarely useful, but when some event callback runs for a |
791 | This function is rarely useful, but when some event callback runs for a |
761 | very long time without entering the event loop, updating libev's idea of |
792 | very long time without entering the event loop, updating libev's idea of |
762 | the current time is a good idea. |
793 | the current time is a good idea. |
763 | .Sp |
794 | .Sp |
764 | See also \*(L"The special problem of time updates\*(R" in the \f(CW\*(C`ev_timer\*(C'\fR section. |
795 | See also \*(L"The special problem of time updates\*(R" in the \f(CW\*(C`ev_timer\*(C'\fR section. |
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796 | .IP "ev_suspend (loop)" 4 |
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797 | .IX Item "ev_suspend (loop)" |
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798 | .PD 0 |
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799 | .IP "ev_resume (loop)" 4 |
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800 | .IX Item "ev_resume (loop)" |
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801 | .PD |
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802 | These two functions suspend and resume a loop, for use when the loop is |
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803 | not used for a while and timeouts should not be processed. |
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804 | .Sp |
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805 | A typical use case would be an interactive program such as a game: When |
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806 | the user presses \f(CW\*(C`^Z\*(C'\fR to suspend the game and resumes it an hour later it |
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807 | would be best to handle timeouts as if no time had actually passed while |
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808 | the program was suspended. This can be achieved by calling \f(CW\*(C`ev_suspend\*(C'\fR |
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809 | in your \f(CW\*(C`SIGTSTP\*(C'\fR handler, sending yourself a \f(CW\*(C`SIGSTOP\*(C'\fR and calling |
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810 | \&\f(CW\*(C`ev_resume\*(C'\fR directly afterwards to resume timer processing. |
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811 | .Sp |
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812 | Effectively, all \f(CW\*(C`ev_timer\*(C'\fR watchers will be delayed by the time spend |
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813 | 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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814 | will be rescheduled (that is, they will lose any events that would have |
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815 | occured while suspended). |
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816 | .Sp |
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817 | After calling \f(CW\*(C`ev_suspend\*(C'\fR you \fBmust not\fR call \fIany\fR function on the |
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818 | 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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819 | without a previous call to \f(CW\*(C`ev_suspend\*(C'\fR. |
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820 | .Sp |
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821 | 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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822 | event loop time (see \f(CW\*(C`ev_now_update\*(C'\fR). |
765 | .IP "ev_loop (loop, int flags)" 4 |
823 | .IP "ev_loop (loop, int flags)" 4 |
766 | .IX Item "ev_loop (loop, int flags)" |
824 | .IX Item "ev_loop (loop, int flags)" |
767 | Finally, this is it, the event handler. This function usually is called |
825 | Finally, this is it, the event handler. This function usually is called |
768 | after you initialised all your watchers and you want to start handling |
826 | after you initialised all your watchers and you want to start handling |
769 | events. |
827 | events. |
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856 | .Sp |
914 | .Sp |
857 | If you have a watcher you never unregister that should not keep \f(CW\*(C`ev_loop\*(C'\fR |
915 | If you have a watcher you never unregister that should not keep \f(CW\*(C`ev_loop\*(C'\fR |
858 | from returning, call \fIev_unref()\fR after starting, and \fIev_ref()\fR before |
916 | from returning, call \fIev_unref()\fR after starting, and \fIev_ref()\fR before |
859 | stopping it. |
917 | stopping it. |
860 | .Sp |
918 | .Sp |
861 | As an example, libev itself uses this for its internal signal pipe: It is |
919 | As an example, libev itself uses this for its internal signal pipe: It |
862 | not visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting |
920 | is not visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from |
863 | if no event watchers registered by it are active. It is also an excellent |
921 | exiting if no event watchers registered by it are active. It is also an |
864 | way to do this for generic recurring timers or from within third-party |
922 | excellent way to do this for generic recurring timers or from within |
865 | libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR |
923 | third-party libraries. Just remember to \fIunref after start\fR and \fIref |
866 | (but only if the watcher wasn't active before, or was active before, |
924 | before stop\fR (but only if the watcher wasn't active before, or was active |
867 | respectively). |
925 | before, respectively. Note also that libev might stop watchers itself |
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926 | (e.g. non-repeating timers) in which case you have to \f(CW\*(C`ev_ref\*(C'\fR |
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927 | in the callback). |
868 | .Sp |
928 | .Sp |
869 | Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR |
929 | Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR |
870 | running when nothing else is active. |
930 | running when nothing else is active. |
871 | .Sp |
931 | .Sp |
872 | .Vb 4 |
932 | .Vb 4 |
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… | |
906 | .Sp |
966 | .Sp |
907 | By setting a higher \fIio collect interval\fR you allow libev to spend more |
967 | By setting a higher \fIio collect interval\fR you allow libev to spend more |
908 | time collecting I/O events, so you can handle more events per iteration, |
968 | time collecting I/O events, so you can handle more events per iteration, |
909 | at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and |
969 | at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and |
910 | \&\f(CW\*(C`ev_timer\*(C'\fR) will be not affected. Setting this to a non-null value will |
970 | \&\f(CW\*(C`ev_timer\*(C'\fR) will be not affected. Setting this to a non-null value will |
911 | introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. |
971 | introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. The |
|
|
972 | sleep time ensures that libev will not poll for I/O events more often then |
|
|
973 | once per this interval, on average. |
912 | .Sp |
974 | .Sp |
913 | Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
975 | Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
914 | to spend more time collecting timeouts, at the expense of increased |
976 | to spend more time collecting timeouts, at the expense of increased |
915 | latency/jitter/inexactness (the watcher callback will be called |
977 | latency/jitter/inexactness (the watcher callback will be called |
916 | later). \f(CW\*(C`ev_io\*(C'\fR watchers will not be affected. Setting this to a non-null |
978 | later). \f(CW\*(C`ev_io\*(C'\fR watchers will not be affected. Setting this to a non-null |
… | |
… | |
918 | .Sp |
980 | .Sp |
919 | Many (busy) programs can usually benefit by setting the I/O collect |
981 | Many (busy) programs can usually benefit by setting the I/O collect |
920 | interval to a value near \f(CW0.1\fR or so, which is often enough for |
982 | interval to a value near \f(CW0.1\fR or so, which is often enough for |
921 | interactive servers (of course not for games), likewise for timeouts. It |
983 | interactive servers (of course not for games), likewise for timeouts. It |
922 | usually doesn't make much sense to set it to a lower value than \f(CW0.01\fR, |
984 | usually doesn't make much sense to set it to a lower value than \f(CW0.01\fR, |
923 | as this approaches the timing granularity of most systems. |
985 | as this approaches the timing granularity of most systems. Note that if |
|
|
986 | you do transactions with the outside world and you can't increase the |
|
|
987 | parallelity, then this setting will limit your transaction rate (if you |
|
|
988 | need to poll once per transaction and the I/O collect interval is 0.01, |
|
|
989 | then you can't do more than 100 transations per second). |
924 | .Sp |
990 | .Sp |
925 | Setting the \fItimeout collect interval\fR can improve the opportunity for |
991 | Setting the \fItimeout collect interval\fR can improve the opportunity for |
926 | saving power, as the program will \*(L"bundle\*(R" timer callback invocations that |
992 | saving power, as the program will \*(L"bundle\*(R" timer callback invocations that |
927 | are \*(L"near\*(R" in time together, by delaying some, thus reducing the number of |
993 | are \*(L"near\*(R" in time together, by delaying some, thus reducing the number of |
928 | times the process sleeps and wakes up again. Another useful technique to |
994 | times the process sleeps and wakes up again. Another useful technique to |
929 | reduce iterations/wake\-ups is to use \f(CW\*(C`ev_periodic\*(C'\fR watchers and make sure |
995 | reduce iterations/wake\-ups is to use \f(CW\*(C`ev_periodic\*(C'\fR watchers and make sure |
930 | they fire on, say, one-second boundaries only. |
996 | they fire on, say, one-second boundaries only. |
|
|
997 | .Sp |
|
|
998 | Example: we only need 0.1s timeout granularity, and we wish not to poll |
|
|
999 | more often than 100 times per second: |
|
|
1000 | .Sp |
|
|
1001 | .Vb 2 |
|
|
1002 | \& ev_set_timeout_collect_interval (EV_DEFAULT_UC_ 0.1); |
|
|
1003 | \& ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
|
|
1004 | .Ve |
|
|
1005 | .IP "ev_invoke_pending (loop)" 4 |
|
|
1006 | .IX Item "ev_invoke_pending (loop)" |
|
|
1007 | This call will simply invoke all pending watchers while resetting their |
|
|
1008 | pending state. Normally, \f(CW\*(C`ev_loop\*(C'\fR does this automatically when required, |
|
|
1009 | but when overriding the invoke callback this call comes handy. |
|
|
1010 | .IP "int ev_pending_count (loop)" 4 |
|
|
1011 | .IX Item "int ev_pending_count (loop)" |
|
|
1012 | Returns the number of pending watchers \- zero indicates that no watchers |
|
|
1013 | are pending. |
|
|
1014 | .IP "ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(\s-1EV_P\s0))" 4 |
|
|
1015 | .IX Item "ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))" |
|
|
1016 | This overrides the invoke pending functionality of the loop: Instead of |
|
|
1017 | invoking all pending watchers when there are any, \f(CW\*(C`ev_loop\*(C'\fR will call |
|
|
1018 | this callback instead. This is useful, for example, when you want to |
|
|
1019 | invoke the actual watchers inside another context (another thread etc.). |
|
|
1020 | .Sp |
|
|
1021 | If you want to reset the callback, use \f(CW\*(C`ev_invoke_pending\*(C'\fR as new |
|
|
1022 | callback. |
|
|
1023 | .IP "ev_set_loop_release_cb (loop, void (*release)(\s-1EV_P\s0), void (*acquire)(\s-1EV_P\s0))" 4 |
|
|
1024 | .IX Item "ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P))" |
|
|
1025 | Sometimes you want to share the same loop between multiple threads. This |
|
|
1026 | can be done relatively simply by putting mutex_lock/unlock calls around |
|
|
1027 | each call to a libev function. |
|
|
1028 | .Sp |
|
|
1029 | However, \f(CW\*(C`ev_loop\*(C'\fR can run an indefinite time, so it is not feasible to |
|
|
1030 | wait for it to return. One way around this is to wake up the loop via |
|
|
1031 | \&\f(CW\*(C`ev_unloop\*(C'\fR and \f(CW\*(C`av_async_send\*(C'\fR, another way is to set these \fIrelease\fR |
|
|
1032 | and \fIacquire\fR callbacks on the loop. |
|
|
1033 | .Sp |
|
|
1034 | When set, then \f(CW\*(C`release\*(C'\fR will be called just before the thread is |
|
|
1035 | suspended waiting for new events, and \f(CW\*(C`acquire\*(C'\fR is called just |
|
|
1036 | afterwards. |
|
|
1037 | .Sp |
|
|
1038 | Ideally, \f(CW\*(C`release\*(C'\fR will just call your mutex_unlock function, and |
|
|
1039 | \&\f(CW\*(C`acquire\*(C'\fR will just call the mutex_lock function again. |
|
|
1040 | .Sp |
|
|
1041 | While event loop modifications are allowed between invocations of |
|
|
1042 | \&\f(CW\*(C`release\*(C'\fR and \f(CW\*(C`acquire\*(C'\fR (that's their only purpose after all), no |
|
|
1043 | modifications done will affect the event loop, i.e. adding watchers will |
|
|
1044 | have no effect on the set of file descriptors being watched, or the time |
|
|
1045 | 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 |
|
|
1046 | to take note of any changes you made. |
|
|
1047 | .Sp |
|
|
1048 | In theory, threads executing \f(CW\*(C`ev_loop\*(C'\fR will be async-cancel safe between |
|
|
1049 | invocations of \f(CW\*(C`release\*(C'\fR and \f(CW\*(C`acquire\*(C'\fR. |
|
|
1050 | .Sp |
|
|
1051 | See also the locking example in the \f(CW\*(C`THREADS\*(C'\fR section later in this |
|
|
1052 | document. |
|
|
1053 | .IP "ev_set_userdata (loop, void *data)" 4 |
|
|
1054 | .IX Item "ev_set_userdata (loop, void *data)" |
|
|
1055 | .PD 0 |
|
|
1056 | .IP "ev_userdata (loop)" 4 |
|
|
1057 | .IX Item "ev_userdata (loop)" |
|
|
1058 | .PD |
|
|
1059 | Set and retrieve a single \f(CW\*(C`void *\*(C'\fR associated with a loop. When |
|
|
1060 | \&\f(CW\*(C`ev_set_userdata\*(C'\fR has never been called, then \f(CW\*(C`ev_userdata\*(C'\fR returns |
|
|
1061 | \&\f(CW0.\fR |
|
|
1062 | .Sp |
|
|
1063 | These two functions can be used to associate arbitrary data with a loop, |
|
|
1064 | and are intended solely for the \f(CW\*(C`invoke_pending_cb\*(C'\fR, \f(CW\*(C`release\*(C'\fR and |
|
|
1065 | \&\f(CW\*(C`acquire\*(C'\fR callbacks described above, but of course can be (ab\-)used for |
|
|
1066 | any other purpose as well. |
931 | .IP "ev_loop_verify (loop)" 4 |
1067 | .IP "ev_loop_verify (loop)" 4 |
932 | .IX Item "ev_loop_verify (loop)" |
1068 | .IX Item "ev_loop_verify (loop)" |
933 | This function only does something when \f(CW\*(C`EV_VERIFY\*(C'\fR support has been |
1069 | This function only does something when \f(CW\*(C`EV_VERIFY\*(C'\fR support has been |
934 | compiled in, which is the default for non-minimal builds. It tries to go |
1070 | compiled in, which is the default for non-minimal builds. It tries to go |
935 | through all internal structures and checks them for validity. If anything |
1071 | through all internal structures and checks them for validity. If anything |
… | |
… | |
1060 | \&\f(CW\*(C`ev_fork\*(C'\fR). |
1196 | \&\f(CW\*(C`ev_fork\*(C'\fR). |
1061 | .ie n .IP """EV_ASYNC""" 4 |
1197 | .ie n .IP """EV_ASYNC""" 4 |
1062 | .el .IP "\f(CWEV_ASYNC\fR" 4 |
1198 | .el .IP "\f(CWEV_ASYNC\fR" 4 |
1063 | .IX Item "EV_ASYNC" |
1199 | .IX Item "EV_ASYNC" |
1064 | The given async watcher has been asynchronously notified (see \f(CW\*(C`ev_async\*(C'\fR). |
1200 | The given async watcher has been asynchronously notified (see \f(CW\*(C`ev_async\*(C'\fR). |
|
|
1201 | .ie n .IP """EV_CUSTOM""" 4 |
|
|
1202 | .el .IP "\f(CWEV_CUSTOM\fR" 4 |
|
|
1203 | .IX Item "EV_CUSTOM" |
|
|
1204 | Not ever sent (or otherwise used) by libev itself, but can be freely used |
|
|
1205 | by libev users to signal watchers (e.g. via \f(CW\*(C`ev_feed_event\*(C'\fR). |
1065 | .ie n .IP """EV_ERROR""" 4 |
1206 | .ie n .IP """EV_ERROR""" 4 |
1066 | .el .IP "\f(CWEV_ERROR\fR" 4 |
1207 | .el .IP "\f(CWEV_ERROR\fR" 4 |
1067 | .IX Item "EV_ERROR" |
1208 | .IX Item "EV_ERROR" |
1068 | An unspecified error has occurred, the watcher has been stopped. This might |
1209 | An unspecified error has occurred, the watcher has been stopped. This might |
1069 | happen because the watcher could not be properly started because libev |
1210 | happen because the watcher could not be properly started because libev |
… | |
… | |
1079 | example it might indicate that a fd is readable or writable, and if your |
1220 | example it might indicate that a fd is readable or writable, and if your |
1080 | callbacks is well-written it can just attempt the operation and cope with |
1221 | callbacks is well-written it can just attempt the operation and cope with |
1081 | the error from \fIread()\fR or \fIwrite()\fR. This will not work in multi-threaded |
1222 | the error from \fIread()\fR or \fIwrite()\fR. This will not work in multi-threaded |
1082 | programs, though, as the fd could already be closed and reused for another |
1223 | programs, though, as the fd could already be closed and reused for another |
1083 | thing, so beware. |
1224 | thing, so beware. |
1084 | .Sh "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" |
1225 | .SS "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" |
1085 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1226 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1086 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
1227 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
1087 | .el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 |
1228 | .el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 |
1088 | .IX Item "ev_init (ev_TYPE *watcher, callback)" |
1229 | .IX Item "ev_init (ev_TYPE *watcher, callback)" |
1089 | This macro initialises the generic portion of a watcher. The contents |
1230 | This macro initialises the generic portion of a watcher. The contents |
… | |
… | |
1184 | integer between \f(CW\*(C`EV_MAXPRI\*(C'\fR (default: \f(CW2\fR) and \f(CW\*(C`EV_MINPRI\*(C'\fR |
1325 | integer between \f(CW\*(C`EV_MAXPRI\*(C'\fR (default: \f(CW2\fR) and \f(CW\*(C`EV_MINPRI\*(C'\fR |
1185 | (default: \f(CW\*(C`\-2\*(C'\fR). Pending watchers with higher priority will be invoked |
1326 | (default: \f(CW\*(C`\-2\*(C'\fR). Pending watchers with higher priority will be invoked |
1186 | before watchers with lower priority, but priority will not keep watchers |
1327 | before watchers with lower priority, but priority will not keep watchers |
1187 | from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers). |
1328 | from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers). |
1188 | .Sp |
1329 | .Sp |
1189 | This means that priorities are \fIonly\fR used for ordering callback |
|
|
1190 | invocation after new events have been received. This is useful, for |
|
|
1191 | example, to reduce latency after idling, or more often, to bind two |
|
|
1192 | watchers on the same event and make sure one is called first. |
|
|
1193 | .Sp |
|
|
1194 | If you need to suppress invocation when higher priority events are pending |
1330 | If you need to suppress invocation when higher priority events are pending |
1195 | you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality. |
1331 | you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality. |
1196 | .Sp |
1332 | .Sp |
1197 | You \fImust not\fR change the priority of a watcher as long as it is active or |
1333 | You \fImust not\fR change the priority of a watcher as long as it is active or |
1198 | pending. |
1334 | pending. |
1199 | .Sp |
|
|
1200 | The default priority used by watchers when no priority has been set is |
|
|
1201 | always \f(CW0\fR, which is supposed to not be too high and not be too low :). |
|
|
1202 | .Sp |
1335 | .Sp |
1203 | Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is |
1336 | Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is |
1204 | fine, as long as you do not mind that the priority value you query might |
1337 | fine, as long as you do not mind that the priority value you query might |
1205 | or might not have been clamped to the valid range. |
1338 | or might not have been clamped to the valid range. |
|
|
1339 | .Sp |
|
|
1340 | The default priority used by watchers when no priority has been set is |
|
|
1341 | always \f(CW0\fR, which is supposed to not be too high and not be too low :). |
|
|
1342 | .Sp |
|
|
1343 | See \*(L"\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0\*(R", below, for a more thorough treatment of |
|
|
1344 | priorities. |
1206 | .IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 |
1345 | .IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 |
1207 | .IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" |
1346 | .IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" |
1208 | 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 |
1347 | 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 |
1209 | \&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback |
1348 | \&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback |
1210 | can deal with that fact, as both are simply passed through to the |
1349 | can deal with that fact, as both are simply passed through to the |
… | |
… | |
1215 | returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the |
1354 | returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the |
1216 | watcher isn't pending it does nothing and returns \f(CW0\fR. |
1355 | watcher isn't pending it does nothing and returns \f(CW0\fR. |
1217 | .Sp |
1356 | .Sp |
1218 | Sometimes it can be useful to \*(L"poll\*(R" a watcher instead of waiting for its |
1357 | Sometimes it can be useful to \*(L"poll\*(R" a watcher instead of waiting for its |
1219 | callback to be invoked, which can be accomplished with this function. |
1358 | callback to be invoked, which can be accomplished with this function. |
1220 | .Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
1359 | .SS "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
1221 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
1360 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
1222 | Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change |
1361 | Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change |
1223 | and read at any time: libev will completely ignore it. This can be used |
1362 | and read at any time: libev will completely ignore it. This can be used |
1224 | to associate arbitrary data with your watcher. If you need more data and |
1363 | to associate arbitrary data with your watcher. If you need more data and |
1225 | don't want to allocate memory and store a pointer to it in that data |
1364 | don't want to allocate memory and store a pointer to it in that data |
… | |
… | |
1276 | \& #include <stddef.h> |
1415 | \& #include <stddef.h> |
1277 | \& |
1416 | \& |
1278 | \& static void |
1417 | \& static void |
1279 | \& t1_cb (EV_P_ ev_timer *w, int revents) |
1418 | \& t1_cb (EV_P_ ev_timer *w, int revents) |
1280 | \& { |
1419 | \& { |
1281 | \& struct my_biggy big = (struct my_biggy * |
1420 | \& struct my_biggy big = (struct my_biggy *) |
1282 | \& (((char *)w) \- offsetof (struct my_biggy, t1)); |
1421 | \& (((char *)w) \- offsetof (struct my_biggy, t1)); |
1283 | \& } |
1422 | \& } |
1284 | \& |
1423 | \& |
1285 | \& static void |
1424 | \& static void |
1286 | \& t2_cb (EV_P_ ev_timer *w, int revents) |
1425 | \& t2_cb (EV_P_ ev_timer *w, int revents) |
1287 | \& { |
1426 | \& { |
1288 | \& struct my_biggy big = (struct my_biggy * |
1427 | \& struct my_biggy big = (struct my_biggy *) |
1289 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
1428 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
1290 | \& } |
1429 | \& } |
1291 | .Ve |
1430 | .Ve |
|
|
1431 | .SS "\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0" |
|
|
1432 | .IX Subsection "WATCHER PRIORITY MODELS" |
|
|
1433 | Many event loops support \fIwatcher priorities\fR, which are usually small |
|
|
1434 | integers that influence the ordering of event callback invocation |
|
|
1435 | between watchers in some way, all else being equal. |
|
|
1436 | .PP |
|
|
1437 | In libev, Watcher priorities can be set using \f(CW\*(C`ev_set_priority\*(C'\fR. See its |
|
|
1438 | description for the more technical details such as the actual priority |
|
|
1439 | range. |
|
|
1440 | .PP |
|
|
1441 | There are two common ways how these these priorities are being interpreted |
|
|
1442 | by event loops: |
|
|
1443 | .PP |
|
|
1444 | In the more common lock-out model, higher priorities \*(L"lock out\*(R" invocation |
|
|
1445 | of lower priority watchers, which means as long as higher priority |
|
|
1446 | watchers receive events, lower priority watchers are not being invoked. |
|
|
1447 | .PP |
|
|
1448 | The less common only-for-ordering model uses priorities solely to order |
|
|
1449 | callback invocation within a single event loop iteration: Higher priority |
|
|
1450 | watchers are invoked before lower priority ones, but they all get invoked |
|
|
1451 | before polling for new events. |
|
|
1452 | .PP |
|
|
1453 | Libev uses the second (only-for-ordering) model for all its watchers |
|
|
1454 | except for idle watchers (which use the lock-out model). |
|
|
1455 | .PP |
|
|
1456 | The rationale behind this is that implementing the lock-out model for |
|
|
1457 | watchers is not well supported by most kernel interfaces, and most event |
|
|
1458 | libraries will just poll for the same events again and again as long as |
|
|
1459 | their callbacks have not been executed, which is very inefficient in the |
|
|
1460 | common case of one high-priority watcher locking out a mass of lower |
|
|
1461 | priority ones. |
|
|
1462 | .PP |
|
|
1463 | Static (ordering) priorities are most useful when you have two or more |
|
|
1464 | watchers handling the same resource: a typical usage example is having an |
|
|
1465 | \&\f(CW\*(C`ev_io\*(C'\fR watcher to receive data, and an associated \f(CW\*(C`ev_timer\*(C'\fR to handle |
|
|
1466 | timeouts. Under load, data might be received while the program handles |
|
|
1467 | other jobs, but since timers normally get invoked first, the timeout |
|
|
1468 | handler will be executed before checking for data. In that case, giving |
|
|
1469 | the timer a lower priority than the I/O watcher ensures that I/O will be |
|
|
1470 | handled first even under adverse conditions (which is usually, but not |
|
|
1471 | always, what you want). |
|
|
1472 | .PP |
|
|
1473 | Since idle watchers use the \*(L"lock-out\*(R" model, meaning that idle watchers |
|
|
1474 | will only be executed when no same or higher priority watchers have |
|
|
1475 | received events, they can be used to implement the \*(L"lock-out\*(R" model when |
|
|
1476 | required. |
|
|
1477 | .PP |
|
|
1478 | For example, to emulate how many other event libraries handle priorities, |
|
|
1479 | you can associate an \f(CW\*(C`ev_idle\*(C'\fR watcher to each such watcher, and in |
|
|
1480 | the normal watcher callback, you just start the idle watcher. The real |
|
|
1481 | processing is done in the idle watcher callback. This causes libev to |
|
|
1482 | continously poll and process kernel event data for the watcher, but when |
|
|
1483 | the lock-out case is known to be rare (which in turn is rare :), this is |
|
|
1484 | workable. |
|
|
1485 | .PP |
|
|
1486 | Usually, however, the lock-out model implemented that way will perform |
|
|
1487 | miserably under the type of load it was designed to handle. In that case, |
|
|
1488 | it might be preferable to stop the real watcher before starting the |
|
|
1489 | idle watcher, so the kernel will not have to process the event in case |
|
|
1490 | the actual processing will be delayed for considerable time. |
|
|
1491 | .PP |
|
|
1492 | Here is an example of an I/O watcher that should run at a strictly lower |
|
|
1493 | priority than the default, and which should only process data when no |
|
|
1494 | other events are pending: |
|
|
1495 | .PP |
|
|
1496 | .Vb 2 |
|
|
1497 | \& ev_idle idle; // actual processing watcher |
|
|
1498 | \& ev_io io; // actual event watcher |
|
|
1499 | \& |
|
|
1500 | \& static void |
|
|
1501 | \& io_cb (EV_P_ ev_io *w, int revents) |
|
|
1502 | \& { |
|
|
1503 | \& // stop the I/O watcher, we received the event, but |
|
|
1504 | \& // are not yet ready to handle it. |
|
|
1505 | \& ev_io_stop (EV_A_ w); |
|
|
1506 | \& |
|
|
1507 | \& // start the idle watcher to ahndle the actual event. |
|
|
1508 | \& // it will not be executed as long as other watchers |
|
|
1509 | \& // with the default priority are receiving events. |
|
|
1510 | \& ev_idle_start (EV_A_ &idle); |
|
|
1511 | \& } |
|
|
1512 | \& |
|
|
1513 | \& static void |
|
|
1514 | \& idle_cb (EV_P_ ev_idle *w, int revents) |
|
|
1515 | \& { |
|
|
1516 | \& // actual processing |
|
|
1517 | \& read (STDIN_FILENO, ...); |
|
|
1518 | \& |
|
|
1519 | \& // have to start the I/O watcher again, as |
|
|
1520 | \& // we have handled the event |
|
|
1521 | \& ev_io_start (EV_P_ &io); |
|
|
1522 | \& } |
|
|
1523 | \& |
|
|
1524 | \& // initialisation |
|
|
1525 | \& ev_idle_init (&idle, idle_cb); |
|
|
1526 | \& ev_io_init (&io, io_cb, STDIN_FILENO, EV_READ); |
|
|
1527 | \& ev_io_start (EV_DEFAULT_ &io); |
|
|
1528 | .Ve |
|
|
1529 | .PP |
|
|
1530 | In the \*(L"real\*(R" world, it might also be beneficial to start a timer, so that |
|
|
1531 | low-priority connections can not be locked out forever under load. This |
|
|
1532 | enables your program to keep a lower latency for important connections |
|
|
1533 | during short periods of high load, while not completely locking out less |
|
|
1534 | important ones. |
1292 | .SH "WATCHER TYPES" |
1535 | .SH "WATCHER TYPES" |
1293 | .IX Header "WATCHER TYPES" |
1536 | .IX Header "WATCHER TYPES" |
1294 | This section describes each watcher in detail, but will not repeat |
1537 | This section describes each watcher in detail, but will not repeat |
1295 | information given in the last section. Any initialisation/set macros, |
1538 | information given in the last section. Any initialisation/set macros, |
1296 | functions and members specific to the watcher type are explained. |
1539 | functions and members specific to the watcher type are explained. |
… | |
… | |
1301 | watcher is stopped to your hearts content), or \fI[read\-write]\fR, which |
1544 | watcher is stopped to your hearts content), or \fI[read\-write]\fR, which |
1302 | means you can expect it to have some sensible content while the watcher |
1545 | means you can expect it to have some sensible content while the watcher |
1303 | is active, but you can also modify it. Modifying it may not do something |
1546 | is active, but you can also modify it. Modifying it may not do something |
1304 | sensible or take immediate effect (or do anything at all), but libev will |
1547 | sensible or take immediate effect (or do anything at all), but libev will |
1305 | not crash or malfunction in any way. |
1548 | not crash or malfunction in any way. |
1306 | .ie n .Sh """ev_io"" \- is this file descriptor readable or writable?" |
1549 | .ie n .SS """ev_io"" \- is this file descriptor readable or writable?" |
1307 | .el .Sh "\f(CWev_io\fP \- is this file descriptor readable or writable?" |
1550 | .el .SS "\f(CWev_io\fP \- is this file descriptor readable or writable?" |
1308 | .IX Subsection "ev_io - is this file descriptor readable or writable?" |
1551 | .IX Subsection "ev_io - is this file descriptor readable or writable?" |
1309 | I/O watchers check whether a file descriptor is readable or writable |
1552 | I/O watchers check whether a file descriptor is readable or writable |
1310 | in each iteration of the event loop, or, more precisely, when reading |
1553 | in each iteration of the event loop, or, more precisely, when reading |
1311 | would not block the process and writing would at least be able to write |
1554 | would not block the process and writing would at least be able to write |
1312 | some data. This behaviour is called level-triggering because you keep |
1555 | some data. This behaviour is called level-triggering because you keep |
… | |
… | |
1319 | descriptors to non-blocking mode is also usually a good idea (but not |
1562 | descriptors to non-blocking mode is also usually a good idea (but not |
1320 | required if you know what you are doing). |
1563 | required if you know what you are doing). |
1321 | .PP |
1564 | .PP |
1322 | If you cannot use non-blocking mode, then force the use of a |
1565 | If you cannot use non-blocking mode, then force the use of a |
1323 | known-to-be-good backend (at the time of this writing, this includes only |
1566 | known-to-be-good backend (at the time of this writing, this includes only |
1324 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and \f(CW\*(C`EVBACKEND_POLL\*(C'\fR). |
1567 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and \f(CW\*(C`EVBACKEND_POLL\*(C'\fR). The same applies to file |
|
|
1568 | descriptors for which non-blocking operation makes no sense (such as |
|
|
1569 | files) \- libev doesn't guarentee any specific behaviour in that case. |
1325 | .PP |
1570 | .PP |
1326 | Another thing you have to watch out for is that it is quite easy to |
1571 | Another thing you have to watch out for is that it is quite easy to |
1327 | receive \*(L"spurious\*(R" readiness notifications, that is your callback might |
1572 | receive \*(L"spurious\*(R" readiness notifications, that is your callback might |
1328 | be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block |
1573 | be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block |
1329 | because there is no data. Not only are some backends known to create a |
1574 | because there is no data. Not only are some backends known to create a |
… | |
… | |
1438 | \& ev_io stdin_readable; |
1683 | \& ev_io stdin_readable; |
1439 | \& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1684 | \& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1440 | \& ev_io_start (loop, &stdin_readable); |
1685 | \& ev_io_start (loop, &stdin_readable); |
1441 | \& ev_loop (loop, 0); |
1686 | \& ev_loop (loop, 0); |
1442 | .Ve |
1687 | .Ve |
1443 | .ie n .Sh """ev_timer"" \- relative and optionally repeating timeouts" |
1688 | .ie n .SS """ev_timer"" \- relative and optionally repeating timeouts" |
1444 | .el .Sh "\f(CWev_timer\fP \- relative and optionally repeating timeouts" |
1689 | .el .SS "\f(CWev_timer\fP \- relative and optionally repeating timeouts" |
1445 | .IX Subsection "ev_timer - relative and optionally repeating timeouts" |
1690 | .IX Subsection "ev_timer - relative and optionally repeating timeouts" |
1446 | Timer watchers are simple relative timers that generate an event after a |
1691 | Timer watchers are simple relative timers that generate an event after a |
1447 | given time, and optionally repeating in regular intervals after that. |
1692 | given time, and optionally repeating in regular intervals after that. |
1448 | .PP |
1693 | .PP |
1449 | The timers are based on real time, that is, if you register an event that |
1694 | The timers are based on real time, that is, if you register an event that |
… | |
… | |
1451 | year, it will still time out after (roughly) one hour. \*(L"Roughly\*(R" because |
1696 | year, it will still time out after (roughly) one hour. \*(L"Roughly\*(R" because |
1452 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1697 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1453 | monotonic clock option helps a lot here). |
1698 | monotonic clock option helps a lot here). |
1454 | .PP |
1699 | .PP |
1455 | The callback is guaranteed to be invoked only \fIafter\fR its timeout has |
1700 | The callback is guaranteed to be invoked only \fIafter\fR its timeout has |
1456 | passed, but if multiple timers become ready during the same loop iteration |
1701 | passed (not \fIat\fR, so on systems with very low-resolution clocks this |
1457 | then order of execution is undefined. |
1702 | might introduce a small delay). If multiple timers become ready during the |
|
|
1703 | same loop iteration then the ones with earlier time-out values are invoked |
|
|
1704 | before ones of the same priority with later time-out values (but this is |
|
|
1705 | no longer true when a callback calls \f(CW\*(C`ev_loop\*(C'\fR recursively). |
1458 | .PP |
1706 | .PP |
1459 | \fIBe smart about timeouts\fR |
1707 | \fIBe smart about timeouts\fR |
1460 | .IX Subsection "Be smart about timeouts" |
1708 | .IX Subsection "Be smart about timeouts" |
1461 | .PP |
1709 | .PP |
1462 | Many real-world problems involve some kind of timeout, usually for error |
1710 | Many real-world problems involve some kind of timeout, usually for error |
… | |
… | |
1509 | member and \f(CW\*(C`ev_timer_again\*(C'\fR. |
1757 | member and \f(CW\*(C`ev_timer_again\*(C'\fR. |
1510 | .Sp |
1758 | .Sp |
1511 | At start: |
1759 | At start: |
1512 | .Sp |
1760 | .Sp |
1513 | .Vb 3 |
1761 | .Vb 3 |
1514 | \& ev_timer_init (timer, callback); |
1762 | \& ev_init (timer, callback); |
1515 | \& timer\->repeat = 60.; |
1763 | \& timer\->repeat = 60.; |
1516 | \& ev_timer_again (loop, timer); |
1764 | \& ev_timer_again (loop, timer); |
1517 | .Ve |
1765 | .Ve |
1518 | .Sp |
1766 | .Sp |
1519 | Each time there is some activity: |
1767 | Each time there is some activity: |
… | |
… | |
1588 | To start the timer, simply initialise the watcher and set \f(CW\*(C`last_activity\*(C'\fR |
1836 | To start the timer, simply initialise the watcher and set \f(CW\*(C`last_activity\*(C'\fR |
1589 | to the current time (meaning we just have some activity :), then call the |
1837 | to the current time (meaning we just have some activity :), then call the |
1590 | callback, which will \*(L"do the right thing\*(R" and start the timer: |
1838 | callback, which will \*(L"do the right thing\*(R" and start the timer: |
1591 | .Sp |
1839 | .Sp |
1592 | .Vb 3 |
1840 | .Vb 3 |
1593 | \& ev_timer_init (timer, callback); |
1841 | \& ev_init (timer, callback); |
1594 | \& last_activity = ev_now (loop); |
1842 | \& last_activity = ev_now (loop); |
1595 | \& callback (loop, timer, EV_TIMEOUT); |
1843 | \& callback (loop, timer, EV_TIMEOUT); |
1596 | .Ve |
1844 | .Ve |
1597 | .Sp |
1845 | .Sp |
1598 | And when there is some activity, simply store the current time in |
1846 | And when there is some activity, simply store the current time in |
… | |
… | |
1661 | .Ve |
1909 | .Ve |
1662 | .PP |
1910 | .PP |
1663 | If the event loop is suspended for a long time, you can also force an |
1911 | If the event loop is suspended for a long time, you can also force an |
1664 | update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update |
1912 | update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update |
1665 | ()\*(C'\fR. |
1913 | ()\*(C'\fR. |
|
|
1914 | .PP |
|
|
1915 | \fIThe special problems of suspended animation\fR |
|
|
1916 | .IX Subsection "The special problems of suspended animation" |
|
|
1917 | .PP |
|
|
1918 | When you leave the server world it is quite customary to hit machines that |
|
|
1919 | can suspend/hibernate \- what happens to the clocks during such a suspend? |
|
|
1920 | .PP |
|
|
1921 | Some quick tests made with a Linux 2.6.28 indicate that a suspend freezes |
|
|
1922 | all processes, while the clocks (\f(CW\*(C`times\*(C'\fR, \f(CW\*(C`CLOCK_MONOTONIC\*(C'\fR) continue |
|
|
1923 | to run until the system is suspended, but they will not advance while the |
|
|
1924 | system is suspended. That means, on resume, it will be as if the program |
|
|
1925 | was frozen for a few seconds, but the suspend time will not be counted |
|
|
1926 | towards \f(CW\*(C`ev_timer\*(C'\fR when a monotonic clock source is used. The real time |
|
|
1927 | clock advanced as expected, but if it is used as sole clocksource, then a |
|
|
1928 | long suspend would be detected as a time jump by libev, and timers would |
|
|
1929 | be adjusted accordingly. |
|
|
1930 | .PP |
|
|
1931 | I would not be surprised to see different behaviour in different between |
|
|
1932 | operating systems, \s-1OS\s0 versions or even different hardware. |
|
|
1933 | .PP |
|
|
1934 | The other form of suspend (job control, or sending a \s-1SIGSTOP\s0) will see a |
|
|
1935 | time jump in the monotonic clocks and the realtime clock. If the program |
|
|
1936 | is suspended for a very long time, and monotonic clock sources are in use, |
|
|
1937 | then you can expect \f(CW\*(C`ev_timer\*(C'\fRs to expire as the full suspension time |
|
|
1938 | will be counted towards the timers. When no monotonic clock source is in |
|
|
1939 | use, then libev will again assume a timejump and adjust accordingly. |
|
|
1940 | .PP |
|
|
1941 | It might be beneficial for this latter case to call \f(CW\*(C`ev_suspend\*(C'\fR |
|
|
1942 | and \f(CW\*(C`ev_resume\*(C'\fR in code that handles \f(CW\*(C`SIGTSTP\*(C'\fR, to at least get |
|
|
1943 | deterministic behaviour in this case (you can do nothing against |
|
|
1944 | \&\f(CW\*(C`SIGSTOP\*(C'\fR). |
1666 | .PP |
1945 | .PP |
1667 | \fIWatcher-Specific Functions and Data Members\fR |
1946 | \fIWatcher-Specific Functions and Data Members\fR |
1668 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1947 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1669 | .IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 |
1948 | .IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 |
1670 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
1949 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
… | |
… | |
1695 | If the timer is repeating, either start it if necessary (with the |
1974 | If the timer is repeating, either start it if necessary (with the |
1696 | \&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value. |
1975 | \&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value. |
1697 | .Sp |
1976 | .Sp |
1698 | This sounds a bit complicated, see \*(L"Be smart about timeouts\*(R", above, for a |
1977 | This sounds a bit complicated, see \*(L"Be smart about timeouts\*(R", above, for a |
1699 | usage example. |
1978 | usage example. |
|
|
1979 | .IP "ev_timer_remaining (loop, ev_timer *)" 4 |
|
|
1980 | .IX Item "ev_timer_remaining (loop, ev_timer *)" |
|
|
1981 | Returns the remaining time until a timer fires. If the timer is active, |
|
|
1982 | then this time is relative to the current event loop time, otherwise it's |
|
|
1983 | the timeout value currently configured. |
|
|
1984 | .Sp |
|
|
1985 | That is, after an \f(CW\*(C`ev_timer_set (w, 5, 7)\*(C'\fR, \f(CW\*(C`ev_timer_remaining\*(C'\fR returns |
|
|
1986 | \&\f(CW5\fR. When the timer is started and one second passes, \f(CW\*(C`ev_timer_remain\*(C'\fR |
|
|
1987 | will return \f(CW4\fR. When the timer expires and is restarted, it will return |
|
|
1988 | roughly \f(CW7\fR (likely slightly less as callback invocation takes some time, |
|
|
1989 | too), and so on. |
1700 | .IP "ev_tstamp repeat [read\-write]" 4 |
1990 | .IP "ev_tstamp repeat [read\-write]" 4 |
1701 | .IX Item "ev_tstamp repeat [read-write]" |
1991 | .IX Item "ev_tstamp repeat [read-write]" |
1702 | The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out |
1992 | The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out |
1703 | or \f(CW\*(C`ev_timer_again\*(C'\fR is called, and determines the next timeout (if any), |
1993 | or \f(CW\*(C`ev_timer_again\*(C'\fR is called, and determines the next timeout (if any), |
1704 | which is also when any modifications are taken into account. |
1994 | which is also when any modifications are taken into account. |
… | |
… | |
1737 | \& |
2027 | \& |
1738 | \& // and in some piece of code that gets executed on any "activity": |
2028 | \& // and in some piece of code that gets executed on any "activity": |
1739 | \& // reset the timeout to start ticking again at 10 seconds |
2029 | \& // reset the timeout to start ticking again at 10 seconds |
1740 | \& ev_timer_again (&mytimer); |
2030 | \& ev_timer_again (&mytimer); |
1741 | .Ve |
2031 | .Ve |
1742 | .ie n .Sh """ev_periodic"" \- to cron or not to cron?" |
2032 | .ie n .SS """ev_periodic"" \- to cron or not to cron?" |
1743 | .el .Sh "\f(CWev_periodic\fP \- to cron or not to cron?" |
2033 | .el .SS "\f(CWev_periodic\fP \- to cron or not to cron?" |
1744 | .IX Subsection "ev_periodic - to cron or not to cron?" |
2034 | .IX Subsection "ev_periodic - to cron or not to cron?" |
1745 | Periodic watchers are also timers of a kind, but they are very versatile |
2035 | Periodic watchers are also timers of a kind, but they are very versatile |
1746 | (and unfortunately a bit complex). |
2036 | (and unfortunately a bit complex). |
1747 | .PP |
2037 | .PP |
1748 | Unlike \f(CW\*(C`ev_timer\*(C'\fR's, they are not based on real time (or relative time) |
2038 | Unlike \f(CW\*(C`ev_timer\*(C'\fR, periodic watchers are not based on real time (or |
1749 | but on wall clock time (absolute time). You can tell a periodic watcher |
2039 | relative time, the physical time that passes) but on wall clock time |
1750 | to trigger after some specific point in time. For example, if you tell a |
2040 | (absolute time, the thing you can read on your calender or clock). The |
1751 | periodic watcher to trigger in 10 seconds (by specifying e.g. \f(CW\*(C`ev_now () |
2041 | difference is that wall clock time can run faster or slower than real |
1752 | + 10.\*(C'\fR, that is, an absolute time not a delay) and then reset your system |
2042 | time, and time jumps are not uncommon (e.g. when you adjust your |
1753 | clock to January of the previous year, then it will take more than year |
2043 | wrist-watch). |
1754 | to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would still trigger |
|
|
1755 | roughly 10 seconds later as it uses a relative timeout). |
|
|
1756 | .PP |
2044 | .PP |
|
|
2045 | You can tell a periodic watcher to trigger after some specific point |
|
|
2046 | in time: for example, if you tell a periodic watcher to trigger \*(L"in 10 |
|
|
2047 | seconds\*(R" (by specifying e.g. \f(CW\*(C`ev_now () + 10.\*(C'\fR, that is, an absolute time |
|
|
2048 | not a delay) and then reset your system clock to January of the previous |
|
|
2049 | year, then it will take a year or more to trigger the event (unlike an |
|
|
2050 | \&\f(CW\*(C`ev_timer\*(C'\fR, which would still trigger roughly 10 seconds after starting |
|
|
2051 | it, as it uses a relative timeout). |
|
|
2052 | .PP |
1757 | \&\f(CW\*(C`ev_periodic\*(C'\fRs can also be used to implement vastly more complex timers, |
2053 | \&\f(CW\*(C`ev_periodic\*(C'\fR watchers can also be used to implement vastly more complex |
1758 | such as triggering an event on each \*(L"midnight, local time\*(R", or other |
2054 | timers, such as triggering an event on each \*(L"midnight, local time\*(R", or |
1759 | complicated rules. |
2055 | other complicated rules. This cannot be done with \f(CW\*(C`ev_timer\*(C'\fR watchers, as |
|
|
2056 | those cannot react to time jumps. |
1760 | .PP |
2057 | .PP |
1761 | As with timers, the callback is guaranteed to be invoked only when the |
2058 | As with timers, the callback is guaranteed to be invoked only when the |
1762 | time (\f(CW\*(C`at\*(C'\fR) has passed, but if multiple periodic timers become ready |
2059 | point in time where it is supposed to trigger has passed. If multiple |
1763 | during the same loop iteration, then order of execution is undefined. |
2060 | timers become ready during the same loop iteration then the ones with |
|
|
2061 | earlier time-out values are invoked before ones with later time-out values |
|
|
2062 | (but this is no longer true when a callback calls \f(CW\*(C`ev_loop\*(C'\fR recursively). |
1764 | .PP |
2063 | .PP |
1765 | \fIWatcher-Specific Functions and Data Members\fR |
2064 | \fIWatcher-Specific Functions and Data Members\fR |
1766 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2065 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1767 | .IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4 |
2066 | .IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" 4 |
1768 | .IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" |
2067 | .IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" |
1769 | .PD 0 |
2068 | .PD 0 |
1770 | .IP "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 4 |
2069 | .IP "ev_periodic_set (ev_periodic *, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" 4 |
1771 | .IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" |
2070 | .IX Item "ev_periodic_set (ev_periodic *, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" |
1772 | .PD |
2071 | .PD |
1773 | Lots of arguments, lets sort it out... There are basically three modes of |
2072 | Lots of arguments, let's sort it out... There are basically three modes of |
1774 | operation, and we will explain them from simplest to most complex: |
2073 | operation, and we will explain them from simplest to most complex: |
1775 | .RS 4 |
2074 | .RS 4 |
1776 | .IP "\(bu" 4 |
2075 | .IP "\(bu" 4 |
1777 | absolute timer (at = time, interval = reschedule_cb = 0) |
2076 | absolute timer (offset = absolute time, interval = 0, reschedule_cb = 0) |
1778 | .Sp |
2077 | .Sp |
1779 | In this configuration the watcher triggers an event after the wall clock |
2078 | In this configuration the watcher triggers an event after the wall clock |
1780 | time \f(CW\*(C`at\*(C'\fR has passed. It will not repeat and will not adjust when a time |
2079 | time \f(CW\*(C`offset\*(C'\fR has passed. It will not repeat and will not adjust when a |
1781 | jump occurs, that is, if it is to be run at January 1st 2011 then it will |
2080 | time jump occurs, that is, if it is to be run at January 1st 2011 then it |
1782 | only run when the system clock reaches or surpasses this time. |
2081 | will be stopped and invoked when the system clock reaches or surpasses |
|
|
2082 | this point in time. |
1783 | .IP "\(bu" 4 |
2083 | .IP "\(bu" 4 |
1784 | repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
2084 | repeating interval timer (offset = offset within interval, interval > 0, reschedule_cb = 0) |
1785 | .Sp |
2085 | .Sp |
1786 | In this mode the watcher will always be scheduled to time out at the next |
2086 | In this mode the watcher will always be scheduled to time out at the next |
1787 | \&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N, which can also be negative) |
2087 | \&\f(CW\*(C`offset + N * interval\*(C'\fR time (for some integer N, which can also be |
1788 | and then repeat, regardless of any time jumps. |
2088 | negative) and then repeat, regardless of any time jumps. The \f(CW\*(C`offset\*(C'\fR |
|
|
2089 | argument is merely an offset into the \f(CW\*(C`interval\*(C'\fR periods. |
1789 | .Sp |
2090 | .Sp |
1790 | This can be used to create timers that do not drift with respect to the |
2091 | This can be used to create timers that do not drift with respect to the |
1791 | system clock, for example, here is a \f(CW\*(C`ev_periodic\*(C'\fR that triggers each |
2092 | system clock, for example, here is an \f(CW\*(C`ev_periodic\*(C'\fR that triggers each |
1792 | hour, on the hour: |
2093 | hour, on the hour (with respect to \s-1UTC\s0): |
1793 | .Sp |
2094 | .Sp |
1794 | .Vb 1 |
2095 | .Vb 1 |
1795 | \& ev_periodic_set (&periodic, 0., 3600., 0); |
2096 | \& ev_periodic_set (&periodic, 0., 3600., 0); |
1796 | .Ve |
2097 | .Ve |
1797 | .Sp |
2098 | .Sp |
… | |
… | |
1800 | full hour (\s-1UTC\s0), or more correctly, when the system time is evenly divisible |
2101 | full hour (\s-1UTC\s0), or more correctly, when the system time is evenly divisible |
1801 | by 3600. |
2102 | by 3600. |
1802 | .Sp |
2103 | .Sp |
1803 | Another way to think about it (for the mathematically inclined) is that |
2104 | Another way to think about it (for the mathematically inclined) is that |
1804 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
2105 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
1805 | time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps. |
2106 | time where \f(CW\*(C`time = offset (mod interval)\*(C'\fR, regardless of any time jumps. |
1806 | .Sp |
2107 | .Sp |
1807 | For numerical stability it is preferable that the \f(CW\*(C`at\*(C'\fR value is near |
2108 | For numerical stability it is preferable that the \f(CW\*(C`offset\*(C'\fR value is near |
1808 | \&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for |
2109 | \&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for |
1809 | this value, and in fact is often specified as zero. |
2110 | this value, and in fact is often specified as zero. |
1810 | .Sp |
2111 | .Sp |
1811 | Note also that there is an upper limit to how often a timer can fire (\s-1CPU\s0 |
2112 | Note also that there is an upper limit to how often a timer can fire (\s-1CPU\s0 |
1812 | speed for example), so if \f(CW\*(C`interval\*(C'\fR is very small then timing stability |
2113 | speed for example), so if \f(CW\*(C`interval\*(C'\fR is very small then timing stability |
1813 | will of course deteriorate. Libev itself tries to be exact to be about one |
2114 | will of course deteriorate. Libev itself tries to be exact to be about one |
1814 | millisecond (if the \s-1OS\s0 supports it and the machine is fast enough). |
2115 | millisecond (if the \s-1OS\s0 supports it and the machine is fast enough). |
1815 | .IP "\(bu" 4 |
2116 | .IP "\(bu" 4 |
1816 | manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
2117 | manual reschedule mode (offset ignored, interval ignored, reschedule_cb = callback) |
1817 | .Sp |
2118 | .Sp |
1818 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being |
2119 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`offset\*(C'\fR are both being |
1819 | ignored. Instead, each time the periodic watcher gets scheduled, the |
2120 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1820 | reschedule callback will be called with the watcher as first, and the |
2121 | reschedule callback will be called with the watcher as first, and the |
1821 | current time as second argument. |
2122 | current time as second argument. |
1822 | .Sp |
2123 | .Sp |
1823 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, |
2124 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, ever, |
1824 | ever, or make \s-1ANY\s0 event loop modifications whatsoever\fR. |
2125 | or make \s-1ANY\s0 other event loop modifications whatsoever, unless explicitly |
|
|
2126 | allowed by documentation here\fR. |
1825 | .Sp |
2127 | .Sp |
1826 | If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop |
2128 | If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop |
1827 | it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the |
2129 | it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the |
1828 | only event loop modification you are allowed to do). |
2130 | only event loop modification you are allowed to do). |
1829 | .Sp |
2131 | .Sp |
… | |
… | |
1860 | when you changed some parameters or the reschedule callback would return |
2162 | when you changed some parameters or the reschedule callback would return |
1861 | a different time than the last time it was called (e.g. in a crond like |
2163 | a different time than the last time it was called (e.g. in a crond like |
1862 | program when the crontabs have changed). |
2164 | program when the crontabs have changed). |
1863 | .IP "ev_tstamp ev_periodic_at (ev_periodic *)" 4 |
2165 | .IP "ev_tstamp ev_periodic_at (ev_periodic *)" 4 |
1864 | .IX Item "ev_tstamp ev_periodic_at (ev_periodic *)" |
2166 | .IX Item "ev_tstamp ev_periodic_at (ev_periodic *)" |
1865 | When active, returns the absolute time that the watcher is supposed to |
2167 | When active, returns the absolute time that the watcher is supposed |
1866 | trigger next. |
2168 | to trigger next. This is not the same as the \f(CW\*(C`offset\*(C'\fR argument to |
|
|
2169 | \&\f(CW\*(C`ev_periodic_set\*(C'\fR, but indeed works even in interval and manual |
|
|
2170 | rescheduling modes. |
1867 | .IP "ev_tstamp offset [read\-write]" 4 |
2171 | .IP "ev_tstamp offset [read\-write]" 4 |
1868 | .IX Item "ev_tstamp offset [read-write]" |
2172 | .IX Item "ev_tstamp offset [read-write]" |
1869 | When repeating, this contains the offset value, otherwise this is the |
2173 | When repeating, this contains the offset value, otherwise this is the |
1870 | absolute point in time (the \f(CW\*(C`at\*(C'\fR value passed to \f(CW\*(C`ev_periodic_set\*(C'\fR). |
2174 | absolute point in time (the \f(CW\*(C`offset\*(C'\fR value passed to \f(CW\*(C`ev_periodic_set\*(C'\fR, |
|
|
2175 | although libev might modify this value for better numerical stability). |
1871 | .Sp |
2176 | .Sp |
1872 | Can be modified any time, but changes only take effect when the periodic |
2177 | Can be modified any time, but changes only take effect when the periodic |
1873 | timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
2178 | timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
1874 | .IP "ev_tstamp interval [read\-write]" 4 |
2179 | .IP "ev_tstamp interval [read\-write]" 4 |
1875 | .IX Item "ev_tstamp interval [read-write]" |
2180 | .IX Item "ev_tstamp interval [read-write]" |
… | |
… | |
1921 | \& ev_periodic hourly_tick; |
2226 | \& ev_periodic hourly_tick; |
1922 | \& ev_periodic_init (&hourly_tick, clock_cb, |
2227 | \& ev_periodic_init (&hourly_tick, clock_cb, |
1923 | \& fmod (ev_now (loop), 3600.), 3600., 0); |
2228 | \& fmod (ev_now (loop), 3600.), 3600., 0); |
1924 | \& ev_periodic_start (loop, &hourly_tick); |
2229 | \& ev_periodic_start (loop, &hourly_tick); |
1925 | .Ve |
2230 | .Ve |
1926 | .ie n .Sh """ev_signal"" \- signal me when a signal gets signalled!" |
2231 | .ie n .SS """ev_signal"" \- signal me when a signal gets signalled!" |
1927 | .el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled!" |
2232 | .el .SS "\f(CWev_signal\fP \- signal me when a signal gets signalled!" |
1928 | .IX Subsection "ev_signal - signal me when a signal gets signalled!" |
2233 | .IX Subsection "ev_signal - signal me when a signal gets signalled!" |
1929 | Signal watchers will trigger an event when the process receives a specific |
2234 | Signal watchers will trigger an event when the process receives a specific |
1930 | signal one or more times. Even though signals are very asynchronous, libev |
2235 | signal one or more times. Even though signals are very asynchronous, libev |
1931 | will try it's best to deliver signals synchronously, i.e. as part of the |
2236 | will try it's best to deliver signals synchronously, i.e. as part of the |
1932 | normal event processing, like any other event. |
2237 | normal event processing, like any other event. |
1933 | .PP |
2238 | .PP |
1934 | If you want signals asynchronously, just use \f(CW\*(C`sigaction\*(C'\fR as you would |
2239 | If you want signals to be delivered truly asynchronously, just use |
1935 | do without libev and forget about sharing the signal. You can even use |
2240 | \&\f(CW\*(C`sigaction\*(C'\fR as you would do without libev and forget about sharing |
1936 | \&\f(CW\*(C`ev_async\*(C'\fR from a signal handler to synchronously wake up an event loop. |
2241 | the signal. You can even use \f(CW\*(C`ev_async\*(C'\fR from a signal handler to |
|
|
2242 | synchronously wake up an event loop. |
1937 | .PP |
2243 | .PP |
1938 | You can configure as many watchers as you like per signal. Only when the |
2244 | You can configure as many watchers as you like for the same signal, but |
|
|
2245 | only within the same loop, i.e. you can watch for \f(CW\*(C`SIGINT\*(C'\fR in your |
|
|
2246 | default loop and for \f(CW\*(C`SIGIO\*(C'\fR in another loop, but you cannot watch for |
|
|
2247 | \&\f(CW\*(C`SIGINT\*(C'\fR in both the default loop and another loop at the same time. At |
|
|
2248 | the moment, \f(CW\*(C`SIGCHLD\*(C'\fR is permanently tied to the default loop. |
|
|
2249 | .PP |
1939 | first watcher gets started will libev actually register a signal handler |
2250 | When the first watcher gets started will libev actually register something |
1940 | with the kernel (thus it coexists with your own signal handlers as long as |
2251 | with the kernel (thus it coexists with your own signal handlers as long as |
1941 | you don't register any with libev for the same signal). Similarly, when |
2252 | you don't register any with libev for the same signal). |
1942 | the last signal watcher for a signal is stopped, libev will reset the |
2253 | .PP |
1943 | signal handler to \s-1SIG_DFL\s0 (regardless of what it was set to before). |
2254 | Both the signal mask state (\f(CW\*(C`sigprocmask\*(C'\fR) and the signal handler state |
|
|
2255 | (\f(CW\*(C`sigaction\*(C'\fR) are unspecified after starting a signal watcher (and after |
|
|
2256 | sotpping it again), that is, libev might or might not block the signal, |
|
|
2257 | and might or might not set or restore the installed signal handler. |
1944 | .PP |
2258 | .PP |
1945 | If possible and supported, libev will install its handlers with |
2259 | If possible and supported, libev will install its handlers with |
1946 | \&\f(CW\*(C`SA_RESTART\*(C'\fR behaviour enabled, so system calls should not be unduly |
2260 | \&\f(CW\*(C`SA_RESTART\*(C'\fR (or equivalent) behaviour enabled, so system calls should |
1947 | interrupted. If you have a problem with system calls getting interrupted by |
2261 | not be unduly interrupted. If you have a problem with system calls getting |
1948 | signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher and unblock |
2262 | interrupted by signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher |
1949 | them in an \f(CW\*(C`ev_prepare\*(C'\fR watcher. |
2263 | and unblock them in an \f(CW\*(C`ev_prepare\*(C'\fR watcher. |
1950 | .PP |
2264 | .PP |
1951 | \fIWatcher-Specific Functions and Data Members\fR |
2265 | \fIWatcher-Specific Functions and Data Members\fR |
1952 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2266 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1953 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
2267 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
1954 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
2268 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
… | |
… | |
1976 | \& |
2290 | \& |
1977 | \& ev_signal signal_watcher; |
2291 | \& ev_signal signal_watcher; |
1978 | \& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2292 | \& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1979 | \& ev_signal_start (loop, &signal_watcher); |
2293 | \& ev_signal_start (loop, &signal_watcher); |
1980 | .Ve |
2294 | .Ve |
1981 | .ie n .Sh """ev_child"" \- watch out for process status changes" |
2295 | .ie n .SS """ev_child"" \- watch out for process status changes" |
1982 | .el .Sh "\f(CWev_child\fP \- watch out for process status changes" |
2296 | .el .SS "\f(CWev_child\fP \- watch out for process status changes" |
1983 | .IX Subsection "ev_child - watch out for process status changes" |
2297 | .IX Subsection "ev_child - watch out for process status changes" |
1984 | Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to |
2298 | Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to |
1985 | some child status changes (most typically when a child of yours dies or |
2299 | some child status changes (most typically when a child of yours dies or |
1986 | exits). It is permissible to install a child watcher \fIafter\fR the child |
2300 | exits). It is permissible to install a child watcher \fIafter\fR the child |
1987 | has been forked (which implies it might have already exited), as long |
2301 | has been forked (which implies it might have already exited), as long |
1988 | as the event loop isn't entered (or is continued from a watcher), i.e., |
2302 | as the event loop isn't entered (or is continued from a watcher), i.e., |
1989 | forking and then immediately registering a watcher for the child is fine, |
2303 | forking and then immediately registering a watcher for the child is fine, |
1990 | but forking and registering a watcher a few event loop iterations later is |
2304 | but forking and registering a watcher a few event loop iterations later or |
1991 | not. |
2305 | in the next callback invocation is not. |
1992 | .PP |
2306 | .PP |
1993 | Only the default event loop is capable of handling signals, and therefore |
2307 | Only the default event loop is capable of handling signals, and therefore |
1994 | you can only register child watchers in the default event loop. |
2308 | you can only register child watchers in the default event loop. |
1995 | .PP |
2309 | .PP |
|
|
2310 | Due to some design glitches inside libev, child watchers will always be |
|
|
2311 | handled at maximum priority (their priority is set to \f(CW\*(C`EV_MAXPRI\*(C'\fR by |
|
|
2312 | libev) |
|
|
2313 | .PP |
1996 | \fIProcess Interaction\fR |
2314 | \fIProcess Interaction\fR |
1997 | .IX Subsection "Process Interaction" |
2315 | .IX Subsection "Process Interaction" |
1998 | .PP |
2316 | .PP |
1999 | Libev grabs \f(CW\*(C`SIGCHLD\*(C'\fR as soon as the default event loop is |
2317 | Libev grabs \f(CW\*(C`SIGCHLD\*(C'\fR as soon as the default event loop is |
2000 | initialised. This is necessary to guarantee proper behaviour even if |
2318 | initialised. This is necessary to guarantee proper behaviour even if the |
2001 | the first child watcher is started after the child exits. The occurrence |
2319 | first child watcher is started after the child exits. The occurrence |
2002 | of \f(CW\*(C`SIGCHLD\*(C'\fR is recorded asynchronously, but child reaping is done |
2320 | of \f(CW\*(C`SIGCHLD\*(C'\fR is recorded asynchronously, but child reaping is done |
2003 | synchronously as part of the event loop processing. Libev always reaps all |
2321 | synchronously as part of the event loop processing. Libev always reaps all |
2004 | children, even ones not watched. |
2322 | children, even ones not watched. |
2005 | .PP |
2323 | .PP |
2006 | \fIOverriding the Built-In Processing\fR |
2324 | \fIOverriding the Built-In Processing\fR |
… | |
… | |
2018 | .IX Subsection "Stopping the Child Watcher" |
2336 | .IX Subsection "Stopping the Child Watcher" |
2019 | .PP |
2337 | .PP |
2020 | Currently, the child watcher never gets stopped, even when the |
2338 | Currently, the child watcher never gets stopped, even when the |
2021 | child terminates, so normally one needs to stop the watcher in the |
2339 | child terminates, so normally one needs to stop the watcher in the |
2022 | callback. Future versions of libev might stop the watcher automatically |
2340 | callback. Future versions of libev might stop the watcher automatically |
2023 | when a child exit is detected. |
2341 | when a child exit is detected (calling \f(CW\*(C`ev_child_stop\*(C'\fR twice is not a |
|
|
2342 | problem). |
2024 | .PP |
2343 | .PP |
2025 | \fIWatcher-Specific Functions and Data Members\fR |
2344 | \fIWatcher-Specific Functions and Data Members\fR |
2026 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2345 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2027 | .IP "ev_child_init (ev_child *, callback, int pid, int trace)" 4 |
2346 | .IP "ev_child_init (ev_child *, callback, int pid, int trace)" 4 |
2028 | .IX Item "ev_child_init (ev_child *, callback, int pid, int trace)" |
2347 | .IX Item "ev_child_init (ev_child *, callback, int pid, int trace)" |
… | |
… | |
2078 | \& { |
2397 | \& { |
2079 | \& ev_child_init (&cw, child_cb, pid, 0); |
2398 | \& ev_child_init (&cw, child_cb, pid, 0); |
2080 | \& ev_child_start (EV_DEFAULT_ &cw); |
2399 | \& ev_child_start (EV_DEFAULT_ &cw); |
2081 | \& } |
2400 | \& } |
2082 | .Ve |
2401 | .Ve |
2083 | .ie n .Sh """ev_stat"" \- did the file attributes just change?" |
2402 | .ie n .SS """ev_stat"" \- did the file attributes just change?" |
2084 | .el .Sh "\f(CWev_stat\fP \- did the file attributes just change?" |
2403 | .el .SS "\f(CWev_stat\fP \- did the file attributes just change?" |
2085 | .IX Subsection "ev_stat - did the file attributes just change?" |
2404 | .IX Subsection "ev_stat - did the file attributes just change?" |
2086 | This watches a file system path for attribute changes. That is, it calls |
2405 | This watches a file system path for attribute changes. That is, it calls |
2087 | \&\f(CW\*(C`stat\*(C'\fR on that path in regular intervals (or when the \s-1OS\s0 says it changed) |
2406 | \&\f(CW\*(C`stat\*(C'\fR on that path in regular intervals (or when the \s-1OS\s0 says it changed) |
2088 | and sees if it changed compared to the last time, invoking the callback if |
2407 | and sees if it changed compared to the last time, invoking the callback if |
2089 | it did. |
2408 | it did. |
… | |
… | |
2303 | \& ... |
2622 | \& ... |
2304 | \& ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
2623 | \& ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
2305 | \& ev_stat_start (loop, &passwd); |
2624 | \& ev_stat_start (loop, &passwd); |
2306 | \& ev_timer_init (&timer, timer_cb, 0., 1.02); |
2625 | \& ev_timer_init (&timer, timer_cb, 0., 1.02); |
2307 | .Ve |
2626 | .Ve |
2308 | .ie n .Sh """ev_idle"" \- when you've got nothing better to do..." |
2627 | .ie n .SS """ev_idle"" \- when you've got nothing better to do..." |
2309 | .el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..." |
2628 | .el .SS "\f(CWev_idle\fP \- when you've got nothing better to do..." |
2310 | .IX Subsection "ev_idle - when you've got nothing better to do..." |
2629 | .IX Subsection "ev_idle - when you've got nothing better to do..." |
2311 | Idle watchers trigger events when no other events of the same or higher |
2630 | Idle watchers trigger events when no other events of the same or higher |
2312 | priority are pending (prepare, check and other idle watchers do not count |
2631 | priority are pending (prepare, check and other idle watchers do not count |
2313 | as receiving \*(L"events\*(R"). |
2632 | as receiving \*(L"events\*(R"). |
2314 | .PP |
2633 | .PP |
… | |
… | |
2327 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
2646 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
2328 | event loop has handled all outstanding events. |
2647 | event loop has handled all outstanding events. |
2329 | .PP |
2648 | .PP |
2330 | \fIWatcher-Specific Functions and Data Members\fR |
2649 | \fIWatcher-Specific Functions and Data Members\fR |
2331 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2650 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2332 | .IP "ev_idle_init (ev_signal *, callback)" 4 |
2651 | .IP "ev_idle_init (ev_idle *, callback)" 4 |
2333 | .IX Item "ev_idle_init (ev_signal *, callback)" |
2652 | .IX Item "ev_idle_init (ev_idle *, callback)" |
2334 | Initialises and configures the idle watcher \- it has no parameters of any |
2653 | Initialises and configures the idle watcher \- it has no parameters of any |
2335 | kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, |
2654 | kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, |
2336 | believe me. |
2655 | believe me. |
2337 | .PP |
2656 | .PP |
2338 | \fIExamples\fR |
2657 | \fIExamples\fR |
… | |
… | |
2350 | \& // no longer anything immediate to do. |
2669 | \& // no longer anything immediate to do. |
2351 | \& } |
2670 | \& } |
2352 | \& |
2671 | \& |
2353 | \& ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
2672 | \& ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
2354 | \& ev_idle_init (idle_watcher, idle_cb); |
2673 | \& ev_idle_init (idle_watcher, idle_cb); |
2355 | \& ev_idle_start (loop, idle_cb); |
2674 | \& ev_idle_start (loop, idle_watcher); |
2356 | .Ve |
2675 | .Ve |
2357 | .ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!" |
2676 | .ie n .SS """ev_prepare"" and ""ev_check"" \- customise your event loop!" |
2358 | .el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" |
2677 | .el .SS "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" |
2359 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
2678 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
2360 | Prepare and check watchers are usually (but not always) used in pairs: |
2679 | Prepare and check watchers are usually (but not always) used in pairs: |
2361 | prepare watchers get invoked before the process blocks and check watchers |
2680 | prepare watchers get invoked before the process blocks and check watchers |
2362 | afterwards. |
2681 | afterwards. |
2363 | .PP |
2682 | .PP |
… | |
… | |
2453 | \& struct pollfd fds [nfd]; |
2772 | \& struct pollfd fds [nfd]; |
2454 | \& // actual code will need to loop here and realloc etc. |
2773 | \& // actual code will need to loop here and realloc etc. |
2455 | \& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2774 | \& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2456 | \& |
2775 | \& |
2457 | \& /* the callback is illegal, but won\*(Aqt be called as we stop during check */ |
2776 | \& /* the callback is illegal, but won\*(Aqt be called as we stop during check */ |
2458 | \& ev_timer_init (&tw, 0, timeout * 1e\-3); |
2777 | \& ev_timer_init (&tw, 0, timeout * 1e\-3, 0.); |
2459 | \& ev_timer_start (loop, &tw); |
2778 | \& ev_timer_start (loop, &tw); |
2460 | \& |
2779 | \& |
2461 | \& // create one ev_io per pollfd |
2780 | \& // create one ev_io per pollfd |
2462 | \& for (int i = 0; i < nfd; ++i) |
2781 | \& for (int i = 0; i < nfd; ++i) |
2463 | \& { |
2782 | \& { |
… | |
… | |
2554 | \& ev_io_stop (EV_A_ iow [n]); |
2873 | \& ev_io_stop (EV_A_ iow [n]); |
2555 | \& |
2874 | \& |
2556 | \& return got_events; |
2875 | \& return got_events; |
2557 | \& } |
2876 | \& } |
2558 | .Ve |
2877 | .Ve |
2559 | .ie n .Sh """ev_embed"" \- when one backend isn't enough..." |
2878 | .ie n .SS """ev_embed"" \- when one backend isn't enough..." |
2560 | .el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." |
2879 | .el .SS "\f(CWev_embed\fP \- when one backend isn't enough..." |
2561 | .IX Subsection "ev_embed - when one backend isn't enough..." |
2880 | .IX Subsection "ev_embed - when one backend isn't enough..." |
2562 | This is a rather advanced watcher type that lets you embed one event loop |
2881 | This is a rather advanced watcher type that lets you embed one event loop |
2563 | into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded |
2882 | into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded |
2564 | loop, other types of watchers might be handled in a delayed or incorrect |
2883 | loop, other types of watchers might be handled in a delayed or incorrect |
2565 | fashion and must not be used). |
2884 | fashion and must not be used). |
… | |
… | |
2687 | \& if (!loop_socket) |
3006 | \& if (!loop_socket) |
2688 | \& loop_socket = loop; |
3007 | \& loop_socket = loop; |
2689 | \& |
3008 | \& |
2690 | \& // now use loop_socket for all sockets, and loop for everything else |
3009 | \& // now use loop_socket for all sockets, and loop for everything else |
2691 | .Ve |
3010 | .Ve |
2692 | .ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork" |
3011 | .ie n .SS """ev_fork"" \- the audacity to resume the event loop after a fork" |
2693 | .el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
3012 | .el .SS "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
2694 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
3013 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
2695 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
3014 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
2696 | whoever is a good citizen cared to tell libev about it by calling |
3015 | whoever is a good citizen cared to tell libev about it by calling |
2697 | \&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the |
3016 | \&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the |
2698 | event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, |
3017 | event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, |
2699 | and only in the child after the fork. If whoever good citizen calling |
3018 | and only in the child after the fork. If whoever good citizen calling |
2700 | \&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork |
3019 | \&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork |
2701 | handlers will be invoked, too, of course. |
3020 | handlers will be invoked, too, of course. |
2702 | .PP |
3021 | .PP |
|
|
3022 | \fIThe special problem of life after fork \- how is it possible?\fR |
|
|
3023 | .IX Subsection "The special problem of life after fork - how is it possible?" |
|
|
3024 | .PP |
|
|
3025 | Most uses of \f(CW\*(C`fork()\*(C'\fR consist of forking, then some simple calls to ste |
|
|
3026 | up/change the process environment, followed by a call to \f(CW\*(C`exec()\*(C'\fR. This |
|
|
3027 | sequence should be handled by libev without any problems. |
|
|
3028 | .PP |
|
|
3029 | This changes when the application actually wants to do event handling |
|
|
3030 | in the child, or both parent in child, in effect \*(L"continuing\*(R" after the |
|
|
3031 | fork. |
|
|
3032 | .PP |
|
|
3033 | The default mode of operation (for libev, with application help to detect |
|
|
3034 | forks) is to duplicate all the state in the child, as would be expected |
|
|
3035 | when \fIeither\fR the parent \fIor\fR the child process continues. |
|
|
3036 | .PP |
|
|
3037 | When both processes want to continue using libev, then this is usually the |
|
|
3038 | wrong result. In that case, usually one process (typically the parent) is |
|
|
3039 | supposed to continue with all watchers in place as before, while the other |
|
|
3040 | process typically wants to start fresh, i.e. without any active watchers. |
|
|
3041 | .PP |
|
|
3042 | The cleanest and most efficient way to achieve that with libev is to |
|
|
3043 | simply create a new event loop, which of course will be \*(L"empty\*(R", and |
|
|
3044 | use that for new watchers. This has the advantage of not touching more |
|
|
3045 | memory than necessary, and thus avoiding the copy-on-write, and the |
|
|
3046 | disadvantage of having to use multiple event loops (which do not support |
|
|
3047 | signal watchers). |
|
|
3048 | .PP |
|
|
3049 | When this is not possible, or you want to use the default loop for |
|
|
3050 | other reasons, then in the process that wants to start \*(L"fresh\*(R", call |
|
|
3051 | \&\f(CW\*(C`ev_default_destroy ()\*(C'\fR followed by \f(CW\*(C`ev_default_loop (...)\*(C'\fR. Destroying |
|
|
3052 | the default loop will \*(L"orphan\*(R" (not stop) all registered watchers, so you |
|
|
3053 | have to be careful not to execute code that modifies those watchers. Note |
|
|
3054 | also that in that case, you have to re-register any signal watchers. |
|
|
3055 | .PP |
2703 | \fIWatcher-Specific Functions and Data Members\fR |
3056 | \fIWatcher-Specific Functions and Data Members\fR |
2704 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3057 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2705 | .IP "ev_fork_init (ev_signal *, callback)" 4 |
3058 | .IP "ev_fork_init (ev_signal *, callback)" 4 |
2706 | .IX Item "ev_fork_init (ev_signal *, callback)" |
3059 | .IX Item "ev_fork_init (ev_signal *, callback)" |
2707 | Initialises and configures the fork watcher \- it has no parameters of any |
3060 | Initialises and configures the fork watcher \- it has no parameters of any |
2708 | kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, |
3061 | kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, |
2709 | believe me. |
3062 | believe me. |
2710 | .ie n .Sh """ev_async"" \- how to wake up another event loop" |
3063 | .ie n .SS """ev_async"" \- how to wake up another event loop" |
2711 | .el .Sh "\f(CWev_async\fP \- how to wake up another event loop" |
3064 | .el .SS "\f(CWev_async\fP \- how to wake up another event loop" |
2712 | .IX Subsection "ev_async - how to wake up another event loop" |
3065 | .IX Subsection "ev_async - how to wake up another event loop" |
2713 | In general, you cannot use an \f(CW\*(C`ev_loop\*(C'\fR from multiple threads or other |
3066 | In general, you cannot use an \f(CW\*(C`ev_loop\*(C'\fR from multiple threads or other |
2714 | asynchronous sources such as signal handlers (as opposed to multiple event |
3067 | asynchronous sources such as signal handlers (as opposed to multiple event |
2715 | loops \- those are of course safe to use in different threads). |
3068 | loops \- those are of course safe to use in different threads). |
2716 | .PP |
3069 | .PP |
… | |
… | |
2825 | an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop. Unlike |
3178 | an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop. Unlike |
2826 | \&\f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do from other threads, signal or |
3179 | \&\f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do from other threads, signal or |
2827 | similar contexts (see the discussion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the embedding |
3180 | similar contexts (see the discussion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the embedding |
2828 | section below on what exactly this means). |
3181 | section below on what exactly this means). |
2829 | .Sp |
3182 | .Sp |
|
|
3183 | Note that, as with other watchers in libev, multiple events might get |
|
|
3184 | compressed into a single callback invocation (another way to look at this |
|
|
3185 | is that \f(CW\*(C`ev_async\*(C'\fR watchers are level-triggered, set on \f(CW\*(C`ev_async_send\*(C'\fR, |
|
|
3186 | reset when the event loop detects that). |
|
|
3187 | .Sp |
2830 | This call incurs the overhead of a system call only once per loop iteration, |
3188 | This call incurs the overhead of a system call only once per event loop |
2831 | so while the overhead might be noticeable, it doesn't apply to repeated |
3189 | iteration, so while the overhead might be noticeable, it doesn't apply to |
2832 | calls to \f(CW\*(C`ev_async_send\*(C'\fR. |
3190 | repeated calls to \f(CW\*(C`ev_async_send\*(C'\fR for the same event loop. |
2833 | .IP "bool = ev_async_pending (ev_async *)" 4 |
3191 | .IP "bool = ev_async_pending (ev_async *)" 4 |
2834 | .IX Item "bool = ev_async_pending (ev_async *)" |
3192 | .IX Item "bool = ev_async_pending (ev_async *)" |
2835 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
3193 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
2836 | watcher but the event has not yet been processed (or even noted) by the |
3194 | watcher but the event has not yet been processed (or even noted) by the |
2837 | event loop. |
3195 | event loop. |
… | |
… | |
2839 | \&\f(CW\*(C`ev_async_send\*(C'\fR sets a flag in the watcher and wakes up the loop. When |
3197 | \&\f(CW\*(C`ev_async_send\*(C'\fR sets a flag in the watcher and wakes up the loop. When |
2840 | the loop iterates next and checks for the watcher to have become active, |
3198 | the loop iterates next and checks for the watcher to have become active, |
2841 | it will reset the flag again. \f(CW\*(C`ev_async_pending\*(C'\fR can be used to very |
3199 | it will reset the flag again. \f(CW\*(C`ev_async_pending\*(C'\fR can be used to very |
2842 | quickly check whether invoking the loop might be a good idea. |
3200 | quickly check whether invoking the loop might be a good idea. |
2843 | .Sp |
3201 | .Sp |
2844 | Not that this does \fInot\fR check whether the watcher itself is pending, only |
3202 | Not that this does \fInot\fR check whether the watcher itself is pending, |
2845 | whether it has been requested to make this watcher pending. |
3203 | only whether it has been requested to make this watcher pending: there |
|
|
3204 | is a time window between the event loop checking and resetting the async |
|
|
3205 | notification, and the callback being invoked. |
2846 | .SH "OTHER FUNCTIONS" |
3206 | .SH "OTHER FUNCTIONS" |
2847 | .IX Header "OTHER FUNCTIONS" |
3207 | .IX Header "OTHER FUNCTIONS" |
2848 | There are some other functions of possible interest. Described. Here. Now. |
3208 | There are some other functions of possible interest. Described. Here. Now. |
2849 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
3209 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
2850 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
3210 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
… | |
… | |
2947 | need one additional pointer for context. If you need support for other |
3307 | need one additional pointer for context. If you need support for other |
2948 | types of functors please contact the author (preferably after implementing |
3308 | types of functors please contact the author (preferably after implementing |
2949 | it). |
3309 | it). |
2950 | .PP |
3310 | .PP |
2951 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
3311 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
2952 | .ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4 |
3312 | .ie n .IP """ev::READ"", ""ev::WRITE"" etc." 4 |
2953 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
3313 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
2954 | .IX Item "ev::READ, ev::WRITE etc." |
3314 | .IX Item "ev::READ, ev::WRITE etc." |
2955 | These are just enum values with the same values as the \f(CW\*(C`EV_READ\*(C'\fR etc. |
3315 | These are just enum values with the same values as the \f(CW\*(C`EV_READ\*(C'\fR etc. |
2956 | macros from \fIev.h\fR. |
3316 | macros from \fIev.h\fR. |
2957 | .ie n .IP """ev::tstamp""\fR, \f(CW""ev::now""" 4 |
3317 | .ie n .IP """ev::tstamp"", ""ev::now""" 4 |
2958 | .el .IP "\f(CWev::tstamp\fR, \f(CWev::now\fR" 4 |
3318 | .el .IP "\f(CWev::tstamp\fR, \f(CWev::now\fR" 4 |
2959 | .IX Item "ev::tstamp, ev::now" |
3319 | .IX Item "ev::tstamp, ev::now" |
2960 | Aliases to the same types/functions as with the \f(CW\*(C`ev_\*(C'\fR prefix. |
3320 | Aliases to the same types/functions as with the \f(CW\*(C`ev_\*(C'\fR prefix. |
2961 | .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 |
3321 | .ie n .IP """ev::io"", ""ev::timer"", ""ev::periodic"", ""ev::idle"", ""ev::sig"" etc." 4 |
2962 | .el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4 |
3322 | .el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4 |
2963 | .IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc." |
3323 | .IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc." |
2964 | For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of |
3324 | For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of |
2965 | the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR |
3325 | the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR |
2966 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
3326 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
… | |
… | |
3076 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
3436 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
3077 | constructor already stores the event loop. |
3437 | constructor already stores the event loop. |
3078 | .IP "w\->stop ()" 4 |
3438 | .IP "w\->stop ()" 4 |
3079 | .IX Item "w->stop ()" |
3439 | .IX Item "w->stop ()" |
3080 | Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. |
3440 | Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. |
3081 | .ie n .IP "w\->again () (""ev::timer""\fR, \f(CW""ev::periodic"" only)" 4 |
3441 | .ie n .IP "w\->again () (""ev::timer"", ""ev::periodic"" only)" 4 |
3082 | .el .IP "w\->again () (\f(CWev::timer\fR, \f(CWev::periodic\fR only)" 4 |
3442 | .el .IP "w\->again () (\f(CWev::timer\fR, \f(CWev::periodic\fR only)" 4 |
3083 | .IX Item "w->again () (ev::timer, ev::periodic only)" |
3443 | .IX Item "w->again () (ev::timer, ev::periodic only)" |
3084 | For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding |
3444 | For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding |
3085 | \&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. |
3445 | \&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. |
3086 | .ie n .IP "w\->sweep () (""ev::embed"" only)" 4 |
3446 | .ie n .IP "w\->sweep () (""ev::embed"" only)" 4 |
… | |
… | |
3131 | It can be found and installed via \s-1CPAN\s0, its homepage is at |
3491 | It can be found and installed via \s-1CPAN\s0, its homepage is at |
3132 | <http://software.schmorp.de/pkg/EV>. |
3492 | <http://software.schmorp.de/pkg/EV>. |
3133 | .IP "Python" 4 |
3493 | .IP "Python" 4 |
3134 | .IX Item "Python" |
3494 | .IX Item "Python" |
3135 | Python bindings can be found at <http://code.google.com/p/pyev/>. It |
3495 | Python bindings can be found at <http://code.google.com/p/pyev/>. It |
3136 | seems to be quite complete and well-documented. Note, however, that the |
3496 | seems to be quite complete and well-documented. |
3137 | patch they require for libev is outright dangerous as it breaks the \s-1ABI\s0 |
|
|
3138 | for everybody else, and therefore, should never be applied in an installed |
|
|
3139 | libev (if python requires an incompatible \s-1ABI\s0 then it needs to embed |
|
|
3140 | libev). |
|
|
3141 | .IP "Ruby" 4 |
3497 | .IP "Ruby" 4 |
3142 | .IX Item "Ruby" |
3498 | .IX Item "Ruby" |
3143 | Tony Arcieri has written a ruby extension that offers access to a subset |
3499 | Tony Arcieri has written a ruby extension that offers access to a subset |
3144 | of the libev \s-1API\s0 and adds file handle abstractions, asynchronous \s-1DNS\s0 and |
3500 | of the libev \s-1API\s0 and adds file handle abstractions, asynchronous \s-1DNS\s0 and |
3145 | more on top of it. It can be found via gem servers. Its homepage is at |
3501 | more on top of it. It can be found via gem servers. Its homepage is at |
3146 | <http://rev.rubyforge.org/>. |
3502 | <http://rev.rubyforge.org/>. |
3147 | .Sp |
3503 | .Sp |
3148 | Roger Pack reports that using the link order \f(CW\*(C`\-lws2_32 \-lmsvcrt\-ruby\-190\*(C'\fR |
3504 | Roger Pack reports that using the link order \f(CW\*(C`\-lws2_32 \-lmsvcrt\-ruby\-190\*(C'\fR |
3149 | makes rev work even on mingw. |
3505 | makes rev work even on mingw. |
|
|
3506 | .IP "Haskell" 4 |
|
|
3507 | .IX Item "Haskell" |
|
|
3508 | A haskell binding to libev is available at |
|
|
3509 | <http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev>. |
3150 | .IP "D" 4 |
3510 | .IP "D" 4 |
3151 | .IX Item "D" |
3511 | .IX Item "D" |
3152 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
3512 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
3153 | be found at <http://proj.llucax.com.ar/wiki/evd>. |
3513 | be found at <http://proj.llucax.com.ar/wiki/evd>. |
3154 | .IP "Ocaml" 4 |
3514 | .IP "Ocaml" 4 |
3155 | .IX Item "Ocaml" |
3515 | .IX Item "Ocaml" |
3156 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3516 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3157 | <http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/>. |
3517 | <http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/>. |
|
|
3518 | .IP "Lua" 4 |
|
|
3519 | .IX Item "Lua" |
|
|
3520 | Brian Maher has written a partial interface to libev |
|
|
3521 | for lua (only \f(CW\*(C`ev_io\*(C'\fR and \f(CW\*(C`ev_timer\*(C'\fR), to be found at |
|
|
3522 | <http://github.com/brimworks/lua\-ev>. |
3158 | .SH "MACRO MAGIC" |
3523 | .SH "MACRO MAGIC" |
3159 | .IX Header "MACRO MAGIC" |
3524 | .IX Header "MACRO MAGIC" |
3160 | Libev can be compiled with a variety of options, the most fundamental |
3525 | Libev can be compiled with a variety of options, the most fundamental |
3161 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
3526 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
3162 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
3527 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
3163 | .PP |
3528 | .PP |
3164 | To make it easier to write programs that cope with either variant, the |
3529 | To make it easier to write programs that cope with either variant, the |
3165 | following macros are defined: |
3530 | following macros are defined: |
3166 | .ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4 |
3531 | .ie n .IP """EV_A"", ""EV_A_""" 4 |
3167 | .el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4 |
3532 | .el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4 |
3168 | .IX Item "EV_A, EV_A_" |
3533 | .IX Item "EV_A, EV_A_" |
3169 | This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev |
3534 | This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev |
3170 | loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument, |
3535 | loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument, |
3171 | \&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example: |
3536 | \&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example: |
… | |
… | |
3176 | \& ev_loop (EV_A_ 0); |
3541 | \& ev_loop (EV_A_ 0); |
3177 | .Ve |
3542 | .Ve |
3178 | .Sp |
3543 | .Sp |
3179 | It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope, |
3544 | It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope, |
3180 | which is often provided by the following macro. |
3545 | which is often provided by the following macro. |
3181 | .ie n .IP """EV_P""\fR, \f(CW""EV_P_""" 4 |
3546 | .ie n .IP """EV_P"", ""EV_P_""" 4 |
3182 | .el .IP "\f(CWEV_P\fR, \f(CWEV_P_\fR" 4 |
3547 | .el .IP "\f(CWEV_P\fR, \f(CWEV_P_\fR" 4 |
3183 | .IX Item "EV_P, EV_P_" |
3548 | .IX Item "EV_P, EV_P_" |
3184 | This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev |
3549 | This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev |
3185 | loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter, |
3550 | loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter, |
3186 | \&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example: |
3551 | \&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example: |
… | |
… | |
3193 | \& static void cb (EV_P_ ev_timer *w, int revents) |
3558 | \& static void cb (EV_P_ ev_timer *w, int revents) |
3194 | .Ve |
3559 | .Ve |
3195 | .Sp |
3560 | .Sp |
3196 | It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite |
3561 | It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite |
3197 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
3562 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
3198 | .ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4 |
3563 | .ie n .IP """EV_DEFAULT"", ""EV_DEFAULT_""" 4 |
3199 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
3564 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
3200 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
3565 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
3201 | Similar to the other two macros, this gives you the value of the default |
3566 | Similar to the other two macros, this gives you the value of the default |
3202 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). |
3567 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). |
3203 | .ie n .IP """EV_DEFAULT_UC""\fR, \f(CW""EV_DEFAULT_UC_""" 4 |
3568 | .ie n .IP """EV_DEFAULT_UC"", ""EV_DEFAULT_UC_""" 4 |
3204 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
3569 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
3205 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
3570 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
3206 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
3571 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
3207 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
3572 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
3208 | is undefined when the default loop has not been initialised by a previous |
3573 | is undefined when the default loop has not been initialised by a previous |
… | |
… | |
3236 | .PP |
3601 | .PP |
3237 | The goal is to enable you to just copy the necessary files into your |
3602 | The goal is to enable you to just copy the necessary files into your |
3238 | source directory without having to change even a single line in them, so |
3603 | source directory without having to change even a single line in them, so |
3239 | you can easily upgrade by simply copying (or having a checked-out copy of |
3604 | you can easily upgrade by simply copying (or having a checked-out copy of |
3240 | libev somewhere in your source tree). |
3605 | libev somewhere in your source tree). |
3241 | .Sh "\s-1FILESETS\s0" |
3606 | .SS "\s-1FILESETS\s0" |
3242 | .IX Subsection "FILESETS" |
3607 | .IX Subsection "FILESETS" |
3243 | Depending on what features you need you need to include one or more sets of files |
3608 | Depending on what features you need you need to include one or more sets of files |
3244 | in your application. |
3609 | in your application. |
3245 | .PP |
3610 | .PP |
3246 | \fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR |
3611 | \fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR |
… | |
… | |
3325 | For this of course you need the m4 file: |
3690 | For this of course you need the m4 file: |
3326 | .PP |
3691 | .PP |
3327 | .Vb 1 |
3692 | .Vb 1 |
3328 | \& libev.m4 |
3693 | \& libev.m4 |
3329 | .Ve |
3694 | .Ve |
3330 | .Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
3695 | .SS "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
3331 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
3696 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
3332 | Libev can be configured via a variety of preprocessor symbols you have to |
3697 | Libev can be configured via a variety of preprocessor symbols you have to |
3333 | define before including any of its files. The default in the absence of |
3698 | define before including any of its files. The default in the absence of |
3334 | autoconf is documented for every option. |
3699 | autoconf is documented for every option. |
3335 | .IP "\s-1EV_STANDALONE\s0" 4 |
3700 | .IP "\s-1EV_STANDALONE\s0" 4 |
… | |
… | |
3338 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
3703 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
3339 | implementations for some libevent functions (such as logging, which is not |
3704 | implementations for some libevent functions (such as logging, which is not |
3340 | supported). It will also not define any of the structs usually found in |
3705 | supported). It will also not define any of the structs usually found in |
3341 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
3706 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
3342 | .Sp |
3707 | .Sp |
3343 | In stanbdalone mode, libev will still try to automatically deduce the |
3708 | In standalone mode, libev will still try to automatically deduce the |
3344 | configuration, but has to be more conservative. |
3709 | configuration, but has to be more conservative. |
3345 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
3710 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
3346 | .IX Item "EV_USE_MONOTONIC" |
3711 | .IX Item "EV_USE_MONOTONIC" |
3347 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
3712 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
3348 | monotonic clock option at both compile time and runtime. Otherwise no |
3713 | monotonic clock option at both compile time and runtime. Otherwise no |
… | |
… | |
3534 | If undefined or defined to be \f(CW1\fR, then async watchers are supported. If |
3899 | If undefined or defined to be \f(CW1\fR, then async watchers are supported. If |
3535 | defined to be \f(CW0\fR, then they are not. |
3900 | defined to be \f(CW0\fR, then they are not. |
3536 | .IP "\s-1EV_MINIMAL\s0" 4 |
3901 | .IP "\s-1EV_MINIMAL\s0" 4 |
3537 | .IX Item "EV_MINIMAL" |
3902 | .IX Item "EV_MINIMAL" |
3538 | If you need to shave off some kilobytes of code at the expense of some |
3903 | If you need to shave off some kilobytes of code at the expense of some |
3539 | speed, define this symbol to \f(CW1\fR. Currently this is used to override some |
3904 | speed (but with the full \s-1API\s0), define this symbol to \f(CW1\fR. Currently this |
3540 | inlining decisions, saves roughly 30% code size on amd64. It also selects a |
3905 | is used to override some inlining decisions, saves roughly 30% code size |
3541 | much smaller 2\-heap for timer management over the default 4\-heap. |
3906 | on amd64. It also selects a much smaller 2\-heap for timer management over |
|
|
3907 | the default 4\-heap. |
|
|
3908 | .Sp |
|
|
3909 | You can save even more by disabling watcher types you do not need |
|
|
3910 | and setting \f(CW\*(C`EV_MAXPRI\*(C'\fR == \f(CW\*(C`EV_MINPRI\*(C'\fR. Also, disabling \f(CW\*(C`assert\*(C'\fR |
|
|
3911 | (\f(CW\*(C`\-DNDEBUG\*(C'\fR) will usually reduce code size a lot. |
|
|
3912 | .Sp |
|
|
3913 | Defining \f(CW\*(C`EV_MINIMAL\*(C'\fR to \f(CW2\fR will additionally reduce the core \s-1API\s0 to |
|
|
3914 | provide a bare-bones event library. See \f(CW\*(C`ev.h\*(C'\fR for details on what parts |
|
|
3915 | of the \s-1API\s0 are still available, and do not complain if this subset changes |
|
|
3916 | over time. |
|
|
3917 | .IP "\s-1EV_NSIG\s0" 4 |
|
|
3918 | .IX Item "EV_NSIG" |
|
|
3919 | The highest supported signal number, +1 (or, the number of |
|
|
3920 | signals): Normally, libev tries to deduce the maximum number of signals |
|
|
3921 | automatically, but sometimes this fails, in which case it can be |
|
|
3922 | specified. Also, using a lower number than detected (\f(CW32\fR should be |
|
|
3923 | good for about any system in existance) can save some memory, as libev |
|
|
3924 | statically allocates some 12\-24 bytes per signal number. |
3542 | .IP "\s-1EV_PID_HASHSIZE\s0" 4 |
3925 | .IP "\s-1EV_PID_HASHSIZE\s0" 4 |
3543 | .IX Item "EV_PID_HASHSIZE" |
3926 | .IX Item "EV_PID_HASHSIZE" |
3544 | \&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by |
3927 | \&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by |
3545 | pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more |
3928 | pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more |
3546 | than enough. If you need to manage thousands of children you might want to |
3929 | than enough. If you need to manage thousands of children you might want to |
… | |
… | |
3610 | and the way callbacks are invoked and set. Must expand to a struct member |
3993 | and the way callbacks are invoked and set. Must expand to a struct member |
3611 | definition and a statement, respectively. See the \fIev.h\fR header file for |
3994 | definition and a statement, respectively. See the \fIev.h\fR header file for |
3612 | their default definitions. One possible use for overriding these is to |
3995 | their default definitions. One possible use for overriding these is to |
3613 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
3996 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
3614 | method calls instead of plain function calls in \*(C+. |
3997 | method calls instead of plain function calls in \*(C+. |
3615 | .Sh "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" |
3998 | .SS "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" |
3616 | .IX Subsection "EXPORTED API SYMBOLS" |
3999 | .IX Subsection "EXPORTED API SYMBOLS" |
3617 | If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of |
4000 | If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of |
3618 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
4001 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
3619 | all public symbols, one per line: |
4002 | all public symbols, one per line: |
3620 | .PP |
4003 | .PP |
… | |
… | |
3640 | \& #define ev_backend myprefix_ev_backend |
4023 | \& #define ev_backend myprefix_ev_backend |
3641 | \& #define ev_check_start myprefix_ev_check_start |
4024 | \& #define ev_check_start myprefix_ev_check_start |
3642 | \& #define ev_check_stop myprefix_ev_check_stop |
4025 | \& #define ev_check_stop myprefix_ev_check_stop |
3643 | \& ... |
4026 | \& ... |
3644 | .Ve |
4027 | .Ve |
3645 | .Sh "\s-1EXAMPLES\s0" |
4028 | .SS "\s-1EXAMPLES\s0" |
3646 | .IX Subsection "EXAMPLES" |
4029 | .IX Subsection "EXAMPLES" |
3647 | For a real-world example of a program the includes libev |
4030 | For a real-world example of a program the includes libev |
3648 | verbatim, you can have a look at the \s-1EV\s0 perl module |
4031 | verbatim, you can have a look at the \s-1EV\s0 perl module |
3649 | (<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
4032 | (<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
3650 | the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public |
4033 | the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public |
… | |
… | |
3675 | \& #include "ev_cpp.h" |
4058 | \& #include "ev_cpp.h" |
3676 | \& #include "ev.c" |
4059 | \& #include "ev.c" |
3677 | .Ve |
4060 | .Ve |
3678 | .SH "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" |
4061 | .SH "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" |
3679 | .IX Header "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" |
4062 | .IX Header "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" |
3680 | .Sh "\s-1THREADS\s0 \s-1AND\s0 \s-1COROUTINES\s0" |
4063 | .SS "\s-1THREADS\s0 \s-1AND\s0 \s-1COROUTINES\s0" |
3681 | .IX Subsection "THREADS AND COROUTINES" |
4064 | .IX Subsection "THREADS AND COROUTINES" |
3682 | \fI\s-1THREADS\s0\fR |
4065 | \fI\s-1THREADS\s0\fR |
3683 | .IX Subsection "THREADS" |
4066 | .IX Subsection "THREADS" |
3684 | .PP |
4067 | .PP |
3685 | All libev functions are reentrant and thread-safe unless explicitly |
4068 | All libev functions are reentrant and thread-safe unless explicitly |
… | |
… | |
3731 | An example use would be to communicate signals or other events that only |
4114 | An example use would be to communicate signals or other events that only |
3732 | work in the default loop by registering the signal watcher with the |
4115 | work in the default loop by registering the signal watcher with the |
3733 | default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop |
4116 | default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop |
3734 | watcher callback into the event loop interested in the signal. |
4117 | watcher callback into the event loop interested in the signal. |
3735 | .PP |
4118 | .PP |
|
|
4119 | \s-1THREAD\s0 \s-1LOCKING\s0 \s-1EXAMPLE\s0 |
|
|
4120 | .IX Subsection "THREAD LOCKING EXAMPLE" |
|
|
4121 | .PP |
|
|
4122 | Here is a fictitious example of how to run an event loop in a different |
|
|
4123 | thread than where callbacks are being invoked and watchers are |
|
|
4124 | created/added/removed. |
|
|
4125 | .PP |
|
|
4126 | For a real-world example, see the \f(CW\*(C`EV::Loop::Async\*(C'\fR perl module, |
|
|
4127 | which uses exactly this technique (which is suited for many high-level |
|
|
4128 | languages). |
|
|
4129 | .PP |
|
|
4130 | The example uses a pthread mutex to protect the loop data, a condition |
|
|
4131 | variable to wait for callback invocations, an async watcher to notify the |
|
|
4132 | event loop thread and an unspecified mechanism to wake up the main thread. |
|
|
4133 | .PP |
|
|
4134 | First, you need to associate some data with the event loop: |
|
|
4135 | .PP |
|
|
4136 | .Vb 6 |
|
|
4137 | \& typedef struct { |
|
|
4138 | \& mutex_t lock; /* global loop lock */ |
|
|
4139 | \& ev_async async_w; |
|
|
4140 | \& thread_t tid; |
|
|
4141 | \& cond_t invoke_cv; |
|
|
4142 | \& } userdata; |
|
|
4143 | \& |
|
|
4144 | \& void prepare_loop (EV_P) |
|
|
4145 | \& { |
|
|
4146 | \& // for simplicity, we use a static userdata struct. |
|
|
4147 | \& static userdata u; |
|
|
4148 | \& |
|
|
4149 | \& ev_async_init (&u\->async_w, async_cb); |
|
|
4150 | \& ev_async_start (EV_A_ &u\->async_w); |
|
|
4151 | \& |
|
|
4152 | \& pthread_mutex_init (&u\->lock, 0); |
|
|
4153 | \& pthread_cond_init (&u\->invoke_cv, 0); |
|
|
4154 | \& |
|
|
4155 | \& // now associate this with the loop |
|
|
4156 | \& ev_set_userdata (EV_A_ u); |
|
|
4157 | \& ev_set_invoke_pending_cb (EV_A_ l_invoke); |
|
|
4158 | \& ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
|
|
4159 | \& |
|
|
4160 | \& // then create the thread running ev_loop |
|
|
4161 | \& pthread_create (&u\->tid, 0, l_run, EV_A); |
|
|
4162 | \& } |
|
|
4163 | .Ve |
|
|
4164 | .PP |
|
|
4165 | The callback for the \f(CW\*(C`ev_async\*(C'\fR watcher does nothing: the watcher is used |
|
|
4166 | solely to wake up the event loop so it takes notice of any new watchers |
|
|
4167 | that might have been added: |
|
|
4168 | .PP |
|
|
4169 | .Vb 5 |
|
|
4170 | \& static void |
|
|
4171 | \& async_cb (EV_P_ ev_async *w, int revents) |
|
|
4172 | \& { |
|
|
4173 | \& // just used for the side effects |
|
|
4174 | \& } |
|
|
4175 | .Ve |
|
|
4176 | .PP |
|
|
4177 | The \f(CW\*(C`l_release\*(C'\fR and \f(CW\*(C`l_acquire\*(C'\fR callbacks simply unlock/lock the mutex |
|
|
4178 | protecting the loop data, respectively. |
|
|
4179 | .PP |
|
|
4180 | .Vb 6 |
|
|
4181 | \& static void |
|
|
4182 | \& l_release (EV_P) |
|
|
4183 | \& { |
|
|
4184 | \& userdata *u = ev_userdata (EV_A); |
|
|
4185 | \& pthread_mutex_unlock (&u\->lock); |
|
|
4186 | \& } |
|
|
4187 | \& |
|
|
4188 | \& static void |
|
|
4189 | \& l_acquire (EV_P) |
|
|
4190 | \& { |
|
|
4191 | \& userdata *u = ev_userdata (EV_A); |
|
|
4192 | \& pthread_mutex_lock (&u\->lock); |
|
|
4193 | \& } |
|
|
4194 | .Ve |
|
|
4195 | .PP |
|
|
4196 | The event loop thread first acquires the mutex, and then jumps straight |
|
|
4197 | into \f(CW\*(C`ev_loop\*(C'\fR: |
|
|
4198 | .PP |
|
|
4199 | .Vb 4 |
|
|
4200 | \& void * |
|
|
4201 | \& l_run (void *thr_arg) |
|
|
4202 | \& { |
|
|
4203 | \& struct ev_loop *loop = (struct ev_loop *)thr_arg; |
|
|
4204 | \& |
|
|
4205 | \& l_acquire (EV_A); |
|
|
4206 | \& pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
|
|
4207 | \& ev_loop (EV_A_ 0); |
|
|
4208 | \& l_release (EV_A); |
|
|
4209 | \& |
|
|
4210 | \& return 0; |
|
|
4211 | \& } |
|
|
4212 | .Ve |
|
|
4213 | .PP |
|
|
4214 | Instead of invoking all pending watchers, the \f(CW\*(C`l_invoke\*(C'\fR callback will |
|
|
4215 | signal the main thread via some unspecified mechanism (signals? pipe |
|
|
4216 | writes? \f(CW\*(C`Async::Interrupt\*(C'\fR?) and then waits until all pending watchers |
|
|
4217 | have been called (in a while loop because a) spurious wakeups are possible |
|
|
4218 | and b) skipping inter-thread-communication when there are no pending |
|
|
4219 | watchers is very beneficial): |
|
|
4220 | .PP |
|
|
4221 | .Vb 4 |
|
|
4222 | \& static void |
|
|
4223 | \& l_invoke (EV_P) |
|
|
4224 | \& { |
|
|
4225 | \& userdata *u = ev_userdata (EV_A); |
|
|
4226 | \& |
|
|
4227 | \& while (ev_pending_count (EV_A)) |
|
|
4228 | \& { |
|
|
4229 | \& wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
|
|
4230 | \& pthread_cond_wait (&u\->invoke_cv, &u\->lock); |
|
|
4231 | \& } |
|
|
4232 | \& } |
|
|
4233 | .Ve |
|
|
4234 | .PP |
|
|
4235 | Now, whenever the main thread gets told to invoke pending watchers, it |
|
|
4236 | will grab the lock, call \f(CW\*(C`ev_invoke_pending\*(C'\fR and then signal the loop |
|
|
4237 | thread to continue: |
|
|
4238 | .PP |
|
|
4239 | .Vb 4 |
|
|
4240 | \& static void |
|
|
4241 | \& real_invoke_pending (EV_P) |
|
|
4242 | \& { |
|
|
4243 | \& userdata *u = ev_userdata (EV_A); |
|
|
4244 | \& |
|
|
4245 | \& pthread_mutex_lock (&u\->lock); |
|
|
4246 | \& ev_invoke_pending (EV_A); |
|
|
4247 | \& pthread_cond_signal (&u\->invoke_cv); |
|
|
4248 | \& pthread_mutex_unlock (&u\->lock); |
|
|
4249 | \& } |
|
|
4250 | .Ve |
|
|
4251 | .PP |
|
|
4252 | Whenever you want to start/stop a watcher or do other modifications to an |
|
|
4253 | event loop, you will now have to lock: |
|
|
4254 | .PP |
|
|
4255 | .Vb 2 |
|
|
4256 | \& ev_timer timeout_watcher; |
|
|
4257 | \& userdata *u = ev_userdata (EV_A); |
|
|
4258 | \& |
|
|
4259 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
|
|
4260 | \& |
|
|
4261 | \& pthread_mutex_lock (&u\->lock); |
|
|
4262 | \& ev_timer_start (EV_A_ &timeout_watcher); |
|
|
4263 | \& ev_async_send (EV_A_ &u\->async_w); |
|
|
4264 | \& pthread_mutex_unlock (&u\->lock); |
|
|
4265 | .Ve |
|
|
4266 | .PP |
|
|
4267 | Note that sending the \f(CW\*(C`ev_async\*(C'\fR watcher is required because otherwise |
|
|
4268 | an event loop currently blocking in the kernel will have no knowledge |
|
|
4269 | about the newly added timer. By waking up the loop it will pick up any new |
|
|
4270 | watchers in the next event loop iteration. |
|
|
4271 | .PP |
3736 | \fI\s-1COROUTINES\s0\fR |
4272 | \fI\s-1COROUTINES\s0\fR |
3737 | .IX Subsection "COROUTINES" |
4273 | .IX Subsection "COROUTINES" |
3738 | .PP |
4274 | .PP |
3739 | Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): |
4275 | Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): |
3740 | libev fully supports nesting calls to its functions from different |
4276 | libev fully supports nesting calls to its functions from different |
3741 | coroutines (e.g. you can call \f(CW\*(C`ev_loop\*(C'\fR on the same loop from two |
4277 | coroutines (e.g. you can call \f(CW\*(C`ev_loop\*(C'\fR on the same loop from two |
3742 | different coroutines, and switch freely between both coroutines running the |
4278 | different coroutines, and switch freely between both coroutines running |
3743 | loop, as long as you don't confuse yourself). The only exception is that |
4279 | the loop, as long as you don't confuse yourself). The only exception is |
3744 | you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
4280 | that you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
3745 | .PP |
4281 | .PP |
3746 | Care has been taken to ensure that libev does not keep local state inside |
4282 | Care has been taken to ensure that libev does not keep local state inside |
3747 | \&\f(CW\*(C`ev_loop\*(C'\fR, and other calls do not usually allow for coroutine switches as |
4283 | \&\f(CW\*(C`ev_loop\*(C'\fR, and other calls do not usually allow for coroutine switches as |
3748 | they do not call any callbacks. |
4284 | they do not call any callbacks. |
3749 | .Sh "\s-1COMPILER\s0 \s-1WARNINGS\s0" |
4285 | .SS "\s-1COMPILER\s0 \s-1WARNINGS\s0" |
3750 | .IX Subsection "COMPILER WARNINGS" |
4286 | .IX Subsection "COMPILER WARNINGS" |
3751 | Depending on your compiler and compiler settings, you might get no or a |
4287 | Depending on your compiler and compiler settings, you might get no or a |
3752 | lot of warnings when compiling libev code. Some people are apparently |
4288 | lot of warnings when compiling libev code. Some people are apparently |
3753 | scared by this. |
4289 | scared by this. |
3754 | .PP |
4290 | .PP |
… | |
… | |
3771 | While libev is written to generate as few warnings as possible, |
4307 | While libev is written to generate as few warnings as possible, |
3772 | \&\*(L"warn-free\*(R" code is not a goal, and it is recommended not to build libev |
4308 | \&\*(L"warn-free\*(R" code is not a goal, and it is recommended not to build libev |
3773 | with any compiler warnings enabled unless you are prepared to cope with |
4309 | with any compiler warnings enabled unless you are prepared to cope with |
3774 | them (e.g. by ignoring them). Remember that warnings are just that: |
4310 | them (e.g. by ignoring them). Remember that warnings are just that: |
3775 | warnings, not errors, or proof of bugs. |
4311 | warnings, not errors, or proof of bugs. |
3776 | .Sh "\s-1VALGRIND\s0" |
4312 | .SS "\s-1VALGRIND\s0" |
3777 | .IX Subsection "VALGRIND" |
4313 | .IX Subsection "VALGRIND" |
3778 | Valgrind has a special section here because it is a popular tool that is |
4314 | Valgrind has a special section here because it is a popular tool that is |
3779 | highly useful. Unfortunately, valgrind reports are very hard to interpret. |
4315 | highly useful. Unfortunately, valgrind reports are very hard to interpret. |
3780 | .PP |
4316 | .PP |
3781 | If you think you found a bug (memory leak, uninitialised data access etc.) |
4317 | If you think you found a bug (memory leak, uninitialised data access etc.) |
… | |
… | |
3806 | .PP |
4342 | .PP |
3807 | If you need, for some reason, empty reports from valgrind for your project |
4343 | If you need, for some reason, empty reports from valgrind for your project |
3808 | I suggest using suppression lists. |
4344 | I suggest using suppression lists. |
3809 | .SH "PORTABILITY NOTES" |
4345 | .SH "PORTABILITY NOTES" |
3810 | .IX Header "PORTABILITY NOTES" |
4346 | .IX Header "PORTABILITY NOTES" |
3811 | .Sh "\s-1WIN32\s0 \s-1PLATFORM\s0 \s-1LIMITATIONS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" |
4347 | .SS "\s-1WIN32\s0 \s-1PLATFORM\s0 \s-1LIMITATIONS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" |
3812 | .IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" |
4348 | .IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" |
3813 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
4349 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
3814 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
4350 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
3815 | model. Libev still offers limited functionality on this platform in |
4351 | model. Libev still offers limited functionality on this platform in |
3816 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
4352 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
… | |
… | |
3823 | way (note also that glib is the slowest event library known to man). |
4359 | way (note also that glib is the slowest event library known to man). |
3824 | .PP |
4360 | .PP |
3825 | There is no supported compilation method available on windows except |
4361 | There is no supported compilation method available on windows except |
3826 | embedding it into other applications. |
4362 | embedding it into other applications. |
3827 | .PP |
4363 | .PP |
|
|
4364 | Sensible signal handling is officially unsupported by Microsoft \- libev |
|
|
4365 | tries its best, but under most conditions, signals will simply not work. |
|
|
4366 | .PP |
3828 | Not a libev limitation but worth mentioning: windows apparently doesn't |
4367 | Not a libev limitation but worth mentioning: windows apparently doesn't |
3829 | accept large writes: instead of resulting in a partial write, windows will |
4368 | accept large writes: instead of resulting in a partial write, windows will |
3830 | either accept everything or return \f(CW\*(C`ENOBUFS\*(C'\fR if the buffer is too large, |
4369 | either accept everything or return \f(CW\*(C`ENOBUFS\*(C'\fR if the buffer is too large, |
3831 | so make sure you only write small amounts into your sockets (less than a |
4370 | so make sure you only write small amounts into your sockets (less than a |
3832 | megabyte seems safe, but this apparently depends on the amount of memory |
4371 | megabyte seems safe, but this apparently depends on the amount of memory |
… | |
… | |
3836 | the abysmal performance of winsockets, using a large number of sockets |
4375 | the abysmal performance of winsockets, using a large number of sockets |
3837 | is not recommended (and not reasonable). If your program needs to use |
4376 | is not recommended (and not reasonable). If your program needs to use |
3838 | more than a hundred or so sockets, then likely it needs to use a totally |
4377 | more than a hundred or so sockets, then likely it needs to use a totally |
3839 | different implementation for windows, as libev offers the \s-1POSIX\s0 readiness |
4378 | different implementation for windows, as libev offers the \s-1POSIX\s0 readiness |
3840 | notification model, which cannot be implemented efficiently on windows |
4379 | notification model, which cannot be implemented efficiently on windows |
3841 | (Microsoft monopoly games). |
4380 | (due to Microsoft monopoly games). |
3842 | .PP |
4381 | .PP |
3843 | A typical way to use libev under windows is to embed it (see the embedding |
4382 | A typical way to use libev under windows is to embed it (see the embedding |
3844 | section for details) and use the following \fIevwrap.h\fR header file instead |
4383 | section for details) and use the following \fIevwrap.h\fR header file instead |
3845 | of \fIev.h\fR: |
4384 | of \fIev.h\fR: |
3846 | .PP |
4385 | .PP |
… | |
… | |
3884 | .Sp |
4423 | .Sp |
3885 | Early versions of winsocket's select only supported waiting for a maximum |
4424 | Early versions of winsocket's select only supported waiting for a maximum |
3886 | of \f(CW64\fR handles (probably owning to the fact that all windows kernels |
4425 | of \f(CW64\fR handles (probably owning to the fact that all windows kernels |
3887 | can only wait for \f(CW64\fR things at the same time internally; Microsoft |
4426 | can only wait for \f(CW64\fR things at the same time internally; Microsoft |
3888 | recommends spawning a chain of threads and wait for 63 handles and the |
4427 | recommends spawning a chain of threads and wait for 63 handles and the |
3889 | previous thread in each. Great). |
4428 | previous thread in each. Sounds great!). |
3890 | .Sp |
4429 | .Sp |
3891 | Newer versions support more handles, but you need to define \f(CW\*(C`FD_SETSIZE\*(C'\fR |
4430 | Newer versions support more handles, but you need to define \f(CW\*(C`FD_SETSIZE\*(C'\fR |
3892 | to some high number (e.g. \f(CW2048\fR) before compiling the winsocket select |
4431 | to some high number (e.g. \f(CW2048\fR) before compiling the winsocket select |
3893 | call (which might be in libev or elsewhere, for example, perl does its own |
4432 | call (which might be in libev or elsewhere, for example, perl and many |
3894 | select emulation on windows). |
4433 | other interpreters do their own select emulation on windows). |
3895 | .Sp |
4434 | .Sp |
3896 | Another limit is the number of file descriptors in the Microsoft runtime |
4435 | Another limit is the number of file descriptors in the Microsoft runtime |
3897 | libraries, which by default is \f(CW64\fR (there must be a hidden \fI64\fR fetish |
4436 | libraries, which by default is \f(CW64\fR (there must be a hidden \fI64\fR |
3898 | or something like this inside Microsoft). You can increase this by calling |
4437 | fetish or something like this inside Microsoft). You can increase this |
3899 | \&\f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR (another |
4438 | by calling \f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR |
3900 | arbitrary limit), but is broken in many versions of the Microsoft runtime |
4439 | (another arbitrary limit), but is broken in many versions of the Microsoft |
3901 | libraries. |
|
|
3902 | .Sp |
|
|
3903 | This might get you to about \f(CW512\fR or \f(CW2048\fR sockets (depending on |
4440 | runtime libraries. This might get you to about \f(CW512\fR or \f(CW2048\fR sockets |
3904 | windows version and/or the phase of the moon). To get more, you need to |
4441 | (depending on windows version and/or the phase of the moon). To get more, |
3905 | wrap all I/O functions and provide your own fd management, but the cost of |
4442 | you need to wrap all I/O functions and provide your own fd management, but |
3906 | calling select (O(nA\*^X)) will likely make this unworkable. |
4443 | the cost of calling select (O(nA\*^X)) will likely make this unworkable. |
3907 | .Sh "\s-1PORTABILITY\s0 \s-1REQUIREMENTS\s0" |
4444 | .SS "\s-1PORTABILITY\s0 \s-1REQUIREMENTS\s0" |
3908 | .IX Subsection "PORTABILITY REQUIREMENTS" |
4445 | .IX Subsection "PORTABILITY REQUIREMENTS" |
3909 | In addition to a working ISO-C implementation and of course the |
4446 | In addition to a working ISO-C implementation and of course the |
3910 | backend-specific APIs, libev relies on a few additional extensions: |
4447 | backend-specific APIs, libev relies on a few additional extensions: |
3911 | .ie n .IP """void (*)(ev_watcher_type *, int revents)""\fR must have compatible calling conventions regardless of \f(CW""ev_watcher_type *""." 4 |
4448 | .ie n .IP """void (*)(ev_watcher_type *, int revents)"" must have compatible calling conventions regardless of ""ev_watcher_type *""." 4 |
3912 | .el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4 |
4449 | .el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4 |
3913 | .IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *." |
4450 | .IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *." |
3914 | Libev assumes not only that all watcher pointers have the same internal |
4451 | Libev assumes not only that all watcher pointers have the same internal |
3915 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO\s0 C for example), but it also |
4452 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO\s0 C for example), but it also |
3916 | assumes that the same (machine) code can be used to call any watcher |
4453 | assumes that the same (machine) code can be used to call any watcher |
… | |
… | |
3948 | .el .IP "\f(CWdouble\fR must hold a time value in seconds with enough accuracy" 4 |
4485 | .el .IP "\f(CWdouble\fR must hold a time value in seconds with enough accuracy" 4 |
3949 | .IX Item "double must hold a time value in seconds with enough accuracy" |
4486 | .IX Item "double must hold a time value in seconds with enough accuracy" |
3950 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
4487 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
3951 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
4488 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
3952 | enough for at least into the year 4000. This requirement is fulfilled by |
4489 | enough for at least into the year 4000. This requirement is fulfilled by |
3953 | implementations implementing \s-1IEEE\s0 754 (basically all existing ones). |
4490 | implementations implementing \s-1IEEE\s0 754, which is basically all existing |
|
|
4491 | ones. With \s-1IEEE\s0 754 doubles, you get microsecond accuracy until at least |
|
|
4492 | 2200. |
3954 | .PP |
4493 | .PP |
3955 | If you know of other additional requirements drop me a note. |
4494 | If you know of other additional requirements drop me a note. |
3956 | .SH "ALGORITHMIC COMPLEXITIES" |
4495 | .SH "ALGORITHMIC COMPLEXITIES" |
3957 | .IX Header "ALGORITHMIC COMPLEXITIES" |
4496 | .IX Header "ALGORITHMIC COMPLEXITIES" |
3958 | In this section the complexities of (many of) the algorithms used inside |
4497 | In this section the complexities of (many of) the algorithms used inside |
… | |
… | |
4014 | .IX Item "Processing signals: O(max_signal_number)" |
4553 | .IX Item "Processing signals: O(max_signal_number)" |
4015 | .PD |
4554 | .PD |
4016 | Sending involves a system call \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
4555 | Sending involves a system call \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
4017 | calls in the current loop iteration. Checking for async and signal events |
4556 | calls in the current loop iteration. Checking for async and signal events |
4018 | involves iterating over all running async watchers or all signal numbers. |
4557 | involves iterating over all running async watchers or all signal numbers. |
|
|
4558 | .SH "GLOSSARY" |
|
|
4559 | .IX Header "GLOSSARY" |
|
|
4560 | .IP "active" 4 |
|
|
4561 | .IX Item "active" |
|
|
4562 | A watcher is active as long as it has been started (has been attached to |
|
|
4563 | an event loop) but not yet stopped (disassociated from the event loop). |
|
|
4564 | .IP "application" 4 |
|
|
4565 | .IX Item "application" |
|
|
4566 | In this document, an application is whatever is using libev. |
|
|
4567 | .IP "callback" 4 |
|
|
4568 | .IX Item "callback" |
|
|
4569 | The address of a function that is called when some event has been |
|
|
4570 | detected. Callbacks are being passed the event loop, the watcher that |
|
|
4571 | received the event, and the actual event bitset. |
|
|
4572 | .IP "callback invocation" 4 |
|
|
4573 | .IX Item "callback invocation" |
|
|
4574 | The act of calling the callback associated with a watcher. |
|
|
4575 | .IP "event" 4 |
|
|
4576 | .IX Item "event" |
|
|
4577 | A change of state of some external event, such as data now being available |
|
|
4578 | for reading on a file descriptor, time having passed or simply not having |
|
|
4579 | any other events happening anymore. |
|
|
4580 | .Sp |
|
|
4581 | In libev, events are represented as single bits (such as \f(CW\*(C`EV_READ\*(C'\fR or |
|
|
4582 | \&\f(CW\*(C`EV_TIMEOUT\*(C'\fR). |
|
|
4583 | .IP "event library" 4 |
|
|
4584 | .IX Item "event library" |
|
|
4585 | A software package implementing an event model and loop. |
|
|
4586 | .IP "event loop" 4 |
|
|
4587 | .IX Item "event loop" |
|
|
4588 | An entity that handles and processes external events and converts them |
|
|
4589 | into callback invocations. |
|
|
4590 | .IP "event model" 4 |
|
|
4591 | .IX Item "event model" |
|
|
4592 | The model used to describe how an event loop handles and processes |
|
|
4593 | watchers and events. |
|
|
4594 | .IP "pending" 4 |
|
|
4595 | .IX Item "pending" |
|
|
4596 | A watcher is pending as soon as the corresponding event has been detected, |
|
|
4597 | and stops being pending as soon as the watcher will be invoked or its |
|
|
4598 | pending status is explicitly cleared by the application. |
|
|
4599 | .Sp |
|
|
4600 | A watcher can be pending, but not active. Stopping a watcher also clears |
|
|
4601 | its pending status. |
|
|
4602 | .IP "real time" 4 |
|
|
4603 | .IX Item "real time" |
|
|
4604 | The physical time that is observed. It is apparently strictly monotonic :) |
|
|
4605 | .IP "wall-clock time" 4 |
|
|
4606 | .IX Item "wall-clock time" |
|
|
4607 | The time and date as shown on clocks. Unlike real time, it can actually |
|
|
4608 | be wrong and jump forwards and backwards, e.g. when the you adjust your |
|
|
4609 | clock. |
|
|
4610 | .IP "watcher" 4 |
|
|
4611 | .IX Item "watcher" |
|
|
4612 | A data structure that describes interest in certain events. Watchers need |
|
|
4613 | to be started (attached to an event loop) before they can receive events. |
|
|
4614 | .IP "watcher invocation" 4 |
|
|
4615 | .IX Item "watcher invocation" |
|
|
4616 | The act of calling the callback associated with a watcher. |
4019 | .SH "AUTHOR" |
4617 | .SH "AUTHOR" |
4020 | .IX Header "AUTHOR" |
4618 | .IX Header "AUTHOR" |
4021 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |
4619 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |