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12 | .. |
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134 | .IX Title "LIBEV 3" |
126 | .IX Title "LIBEV 3" |
135 | .TH LIBEV 3 "2008-10-21" "libev-3.45" "libev - high performance full featured event loop" |
127 | .TH LIBEV 3 "2009-12-31" "libev-3.9" "libev - high performance full featured event loop" |
136 | .\" For nroff, turn off justification. Always turn off hyphenation; it makes |
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138 | .if n .ad l |
130 | .if n .ad l |
139 | .nh |
131 | .nh |
140 | .SH "NAME" |
132 | .SH "NAME" |
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142 | .SH "SYNOPSIS" |
134 | .SH "SYNOPSIS" |
143 | .IX Header "SYNOPSIS" |
135 | .IX Header "SYNOPSIS" |
144 | .Vb 1 |
136 | .Vb 1 |
145 | \& #include <ev.h> |
137 | \& #include <ev.h> |
146 | .Ve |
138 | .Ve |
147 | .Sh "\s-1EXAMPLE\s0 \s-1PROGRAM\s0" |
139 | .SS "\s-1EXAMPLE\s0 \s-1PROGRAM\s0" |
148 | .IX Subsection "EXAMPLE PROGRAM" |
140 | .IX Subsection "EXAMPLE PROGRAM" |
149 | .Vb 2 |
141 | .Vb 2 |
150 | \& // a single header file is required |
142 | \& // a single header file is required |
151 | \& #include <ev.h> |
143 | \& #include <ev.h> |
152 | \& |
144 | \& |
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145 | \& #include <stdio.h> // for puts |
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146 | \& |
153 | \& // every watcher type has its own typedef\*(Aqd struct |
147 | \& // every watcher type has its own typedef\*(Aqd struct |
154 | \& // with the name ev_<type> |
148 | \& // with the name ev_TYPE |
155 | \& ev_io stdin_watcher; |
149 | \& ev_io stdin_watcher; |
156 | \& ev_timer timeout_watcher; |
150 | \& ev_timer timeout_watcher; |
157 | \& |
151 | \& |
158 | \& // all watcher callbacks have a similar signature |
152 | \& // all watcher callbacks have a similar signature |
159 | \& // this callback is called when data is readable on stdin |
153 | \& // this callback is called when data is readable on stdin |
160 | \& static void |
154 | \& static void |
161 | \& stdin_cb (EV_P_ struct ev_io *w, int revents) |
155 | \& stdin_cb (EV_P_ ev_io *w, int revents) |
162 | \& { |
156 | \& { |
163 | \& puts ("stdin ready"); |
157 | \& puts ("stdin ready"); |
164 | \& // for one\-shot events, one must manually stop the watcher |
158 | \& // for one\-shot events, one must manually stop the watcher |
165 | \& // with its corresponding stop function. |
159 | \& // with its corresponding stop function. |
166 | \& ev_io_stop (EV_A_ w); |
160 | \& ev_io_stop (EV_A_ w); |
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169 | \& ev_unloop (EV_A_ EVUNLOOP_ALL); |
163 | \& ev_unloop (EV_A_ EVUNLOOP_ALL); |
170 | \& } |
164 | \& } |
171 | \& |
165 | \& |
172 | \& // another callback, this time for a time\-out |
166 | \& // another callback, this time for a time\-out |
173 | \& static void |
167 | \& static void |
174 | \& timeout_cb (EV_P_ struct ev_timer *w, int revents) |
168 | \& timeout_cb (EV_P_ ev_timer *w, int revents) |
175 | \& { |
169 | \& { |
176 | \& puts ("timeout"); |
170 | \& puts ("timeout"); |
177 | \& // this causes the innermost ev_loop to stop iterating |
171 | \& // this causes the innermost ev_loop to stop iterating |
178 | \& ev_unloop (EV_A_ EVUNLOOP_ONE); |
172 | \& ev_unloop (EV_A_ EVUNLOOP_ONE); |
179 | \& } |
173 | \& } |
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199 | \& |
193 | \& |
200 | \& // unloop was called, so exit |
194 | \& // unloop was called, so exit |
201 | \& return 0; |
195 | \& return 0; |
202 | \& } |
196 | \& } |
203 | .Ve |
197 | .Ve |
204 | .SH "DESCRIPTION" |
198 | .SH "ABOUT THIS DOCUMENT" |
205 | .IX Header "DESCRIPTION" |
199 | .IX Header "ABOUT THIS DOCUMENT" |
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200 | This document documents the libev software package. |
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201 | .PP |
206 | The newest version of this document is also available as an html-formatted |
202 | The newest version of this document is also available as an html-formatted |
207 | web page you might find easier to navigate when reading it for the first |
203 | web page you might find easier to navigate when reading it for the first |
208 | time: <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>. |
204 | time: <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>. |
209 | .PP |
205 | .PP |
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206 | While this document tries to be as complete as possible in documenting |
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207 | libev, its usage and the rationale behind its design, it is not a tutorial |
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208 | on event-based programming, nor will it introduce event-based programming |
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209 | with libev. |
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210 | .PP |
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211 | Familarity with event based programming techniques in general is assumed |
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212 | throughout this document. |
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213 | .SH "ABOUT LIBEV" |
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214 | .IX Header "ABOUT LIBEV" |
210 | Libev is an event loop: you register interest in certain events (such as a |
215 | Libev is an event loop: you register interest in certain events (such as a |
211 | file descriptor being readable or a timeout occurring), and it will manage |
216 | file descriptor being readable or a timeout occurring), and it will manage |
212 | these event sources and provide your program with events. |
217 | these event sources and provide your program with events. |
213 | .PP |
218 | .PP |
214 | To do this, it must take more or less complete control over your process |
219 | To do this, it must take more or less complete control over your process |
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217 | .PP |
222 | .PP |
218 | You register interest in certain events by registering so-called \fIevent |
223 | You register interest in certain events by registering so-called \fIevent |
219 | watchers\fR, which are relatively small C structures you initialise with the |
224 | watchers\fR, which are relatively small C structures you initialise with the |
220 | details of the event, and then hand it over to libev by \fIstarting\fR the |
225 | details of the event, and then hand it over to libev by \fIstarting\fR the |
221 | watcher. |
226 | watcher. |
222 | .Sh "\s-1FEATURES\s0" |
227 | .SS "\s-1FEATURES\s0" |
223 | .IX Subsection "FEATURES" |
228 | .IX Subsection "FEATURES" |
224 | Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific \f(CW\*(C`epoll\*(C'\fR, the |
229 | Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific \f(CW\*(C`epoll\*(C'\fR, the |
225 | BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms |
230 | BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms |
226 | for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface |
231 | for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface |
227 | (for \f(CW\*(C`ev_stat\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers |
232 | (for \f(CW\*(C`ev_stat\*(C'\fR), Linux eventfd/signalfd (for faster and cleaner |
228 | 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 |
229 | (\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 |
230 | 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 |
231 | \&\f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR watchers) as well as |
236 | change events (\f(CW\*(C`ev_child\*(C'\fR), and event watchers dealing with the event |
232 | 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 |
233 | (\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). |
234 | .PP |
240 | .PP |
235 | It also is quite fast (see this |
241 | It also is quite fast (see this |
236 | benchmark comparing it to libevent |
242 | <benchmark> comparing it to libevent |
237 | for example). |
243 | for example). |
238 | .Sh "\s-1CONVENTIONS\s0" |
244 | .SS "\s-1CONVENTIONS\s0" |
239 | .IX Subsection "CONVENTIONS" |
245 | .IX Subsection "CONVENTIONS" |
240 | 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) |
241 | configuration will be described, which supports multiple event loops. For |
247 | configuration will be described, which supports multiple event loops. For |
242 | more info about various configuration options please have a look at |
248 | more info about various configuration options please have a look at |
243 | \&\fB\s-1EMBED\s0\fR section in this manual. If libev was configured without support |
249 | \&\fB\s-1EMBED\s0\fR section in this manual. If libev was configured without support |
244 | for multiple event loops, then all functions taking an initial argument of |
250 | for multiple event loops, then all functions taking an initial argument of |
245 | name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) will not have |
251 | name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) will not have |
246 | this argument. |
252 | this argument. |
247 | .Sh "\s-1TIME\s0 \s-1REPRESENTATION\s0" |
253 | .SS "\s-1TIME\s0 \s-1REPRESENTATION\s0" |
248 | .IX Subsection "TIME REPRESENTATION" |
254 | .IX Subsection "TIME REPRESENTATION" |
249 | Libev represents time as a single floating point number, representing the |
255 | Libev represents time as a single floating point number, representing |
250 | (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 |
251 | 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 |
252 | 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 |
253 | 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 |
254 | 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 |
255 | 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 |
256 | throughout libev. |
262 | throughout libev. |
257 | .SH "ERROR HANDLING" |
263 | .SH "ERROR HANDLING" |
258 | .IX Header "ERROR HANDLING" |
264 | .IX Header "ERROR HANDLING" |
259 | 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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406 | \& ... |
412 | \& ... |
407 | \& ev_set_syserr_cb (fatal_error); |
413 | \& ev_set_syserr_cb (fatal_error); |
408 | .Ve |
414 | .Ve |
409 | .SH "FUNCTIONS CONTROLLING THE EVENT LOOP" |
415 | .SH "FUNCTIONS CONTROLLING THE EVENT LOOP" |
410 | .IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP" |
416 | .IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP" |
411 | An event loop is described by a \f(CW\*(C`struct ev_loop *\*(C'\fR. The library knows two |
417 | An event loop is described by a \f(CW\*(C`struct ev_loop *\*(C'\fR (the \f(CW\*(C`struct\*(C'\fR |
412 | types of such loops, the \fIdefault\fR loop, which supports signals and child |
418 | is \fInot\fR optional in this case, as there is also an \f(CW\*(C`ev_loop\*(C'\fR |
413 | events, and dynamically created loops which do not. |
419 | \&\fIfunction\fR). |
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420 | .PP |
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421 | The library knows two types of such loops, the \fIdefault\fR loop, which |
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422 | supports signals and child events, and dynamically created loops which do |
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423 | not. |
414 | .IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4 |
424 | .IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4 |
415 | .IX Item "struct ev_loop *ev_default_loop (unsigned int flags)" |
425 | .IX Item "struct ev_loop *ev_default_loop (unsigned int flags)" |
416 | This will initialise the default event loop if it hasn't been initialised |
426 | This will initialise the default event loop if it hasn't been initialised |
417 | yet and return it. If the default loop could not be initialised, returns |
427 | yet and return it. If the default loop could not be initialised, returns |
418 | false. If it already was initialised it simply returns it (and ignores the |
428 | false. If it already was initialised it simply returns it (and ignores the |
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421 | If you don't know what event loop to use, use the one returned from this |
431 | If you don't know what event loop to use, use the one returned from this |
422 | function. |
432 | function. |
423 | .Sp |
433 | .Sp |
424 | Note that this function is \fInot\fR thread-safe, so if you want to use it |
434 | Note that this function is \fInot\fR thread-safe, so if you want to use it |
425 | from multiple threads, you have to lock (note also that this is unlikely, |
435 | from multiple threads, you have to lock (note also that this is unlikely, |
426 | as loops cannot bes hared easily between threads anyway). |
436 | as loops cannot be shared easily between threads anyway). |
427 | .Sp |
437 | .Sp |
428 | The default loop is the only loop that can handle \f(CW\*(C`ev_signal\*(C'\fR and |
438 | The default loop is the only loop that can handle \f(CW\*(C`ev_signal\*(C'\fR and |
429 | \&\f(CW\*(C`ev_child\*(C'\fR watchers, and to do this, it always registers a handler |
439 | \&\f(CW\*(C`ev_child\*(C'\fR watchers, and to do this, it always registers a handler |
430 | for \f(CW\*(C`SIGCHLD\*(C'\fR. If this is a problem for your application you can either |
440 | for \f(CW\*(C`SIGCHLD\*(C'\fR. If this is a problem for your application you can either |
431 | create a dynamic loop with \f(CW\*(C`ev_loop_new\*(C'\fR that doesn't do that, or you |
441 | create a dynamic loop with \f(CW\*(C`ev_loop_new\*(C'\fR that doesn't do that, or you |
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469 | 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 |
470 | flag. |
480 | flag. |
471 | .Sp |
481 | .Sp |
472 | 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 |
473 | 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_SIGNALFD""" 4 |
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492 | .el .IP "\f(CWEVFLAG_SIGNALFD\fR" 4 |
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493 | .IX Item "EVFLAG_SIGNALFD" |
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494 | When this flag is specified, then libev will 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 \s-1API\s0 |
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496 | delivers signals synchronously, which makes it both faster and might make |
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497 | it possible to get the queued signal data. It can also simplify signal |
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498 | handling with threads, as long as you properly block signals in your |
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499 | threads that are not interested in handling them. |
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500 | .Sp |
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501 | Signalfd will not be used by default as this changes your signal mask, and |
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502 | there are a lot of shoddy libraries and programs (glib's threadpool for |
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503 | example) that can't properly initialise their signal masks. |
474 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
504 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
475 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
505 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
476 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
506 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
477 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
507 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
478 | libev tries to roll its own fd_set with no limits on the number of fds, |
508 | libev tries to roll its own fd_set with no limits on the number of fds, |
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503 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to \f(CW\*(C`POLLIN | POLLERR | POLLHUP\*(C'\fR, and |
533 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to \f(CW\*(C`POLLIN | POLLERR | POLLHUP\*(C'\fR, and |
504 | \&\f(CW\*(C`EV_WRITE\*(C'\fR to \f(CW\*(C`POLLOUT | POLLERR | POLLHUP\*(C'\fR. |
534 | \&\f(CW\*(C`EV_WRITE\*(C'\fR to \f(CW\*(C`POLLOUT | POLLERR | POLLHUP\*(C'\fR. |
505 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
535 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
506 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
536 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
507 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
537 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
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538 | Use the linux-specific \fIepoll\fR\|(7) interface (for both pre\- and post\-2.6.9 |
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539 | kernels). |
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540 | .Sp |
508 | For few fds, this backend is a bit little slower than poll and select, |
541 | For few fds, this backend is a bit little slower than poll and select, |
509 | but it scales phenomenally better. While poll and select usually scale |
542 | but it scales phenomenally better. While poll and select usually scale |
510 | like O(total_fds) where n is the total number of fds (or the highest fd), |
543 | like O(total_fds) where n is the total number of fds (or the highest fd), |
511 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
544 | epoll scales either O(1) or O(active_fds). |
512 | of shortcomings, such as silently dropping events in some hard-to-detect |
545 | .Sp |
513 | cases and requiring a system call per fd change, no fork support and bad |
546 | The epoll mechanism deserves honorable mention as the most misdesigned |
514 | support for dup. |
547 | of the more advanced event mechanisms: mere annoyances include silently |
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548 | dropping file descriptors, requiring a system call per change per file |
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549 | descriptor (and unnecessary guessing of parameters), problems with dup and |
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550 | so on. The biggest issue is fork races, however \- if a program forks then |
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551 | \&\fIboth\fR parent and child process have to recreate the epoll set, which can |
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552 | take considerable time (one syscall per file descriptor) and is of course |
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553 | hard to detect. |
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554 | .Sp |
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555 | Epoll is also notoriously buggy \- embedding epoll fds \fIshould\fR work, but |
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556 | of course \fIdoesn't\fR, and epoll just loves to report events for totally |
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557 | \&\fIdifferent\fR file descriptors (even already closed ones, so one cannot |
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558 | even remove them from the set) than registered in the set (especially |
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559 | on \s-1SMP\s0 systems). Libev tries to counter these spurious notifications by |
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|
560 | employing an additional generation counter and comparing that against the |
|
|
561 | events to filter out spurious ones, recreating the set when required. |
515 | .Sp |
562 | .Sp |
516 | While stopping, setting and starting an I/O watcher in the same iteration |
563 | While stopping, setting and starting an I/O watcher in the same iteration |
517 | will result in some caching, there is still a system call per such incident |
564 | will result in some caching, there is still a system call per such |
518 | (because the fd could point to a different file description now), so its |
565 | incident (because the same \fIfile descriptor\fR could point to a different |
519 | best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors might not work |
566 | \&\fIfile description\fR now), so its best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed |
520 | very well if you register events for both fds. |
567 | file descriptors might not work very well if you register events for both |
521 | .Sp |
568 | file descriptors. |
522 | Please note that epoll sometimes generates spurious notifications, so you |
|
|
523 | need to use non-blocking I/O or other means to avoid blocking when no data |
|
|
524 | (or space) is available. |
|
|
525 | .Sp |
569 | .Sp |
526 | Best performance from this backend is achieved by not unregistering all |
570 | Best performance from this backend is achieved by not unregistering all |
527 | watchers for a file descriptor until it has been closed, if possible, |
571 | watchers for a file descriptor until it has been closed, if possible, |
528 | i.e. keep at least one watcher active per fd at all times. Stopping and |
572 | i.e. keep at least one watcher active per fd at all times. Stopping and |
529 | starting a watcher (without re-setting it) also usually doesn't cause |
573 | starting a watcher (without re-setting it) also usually doesn't cause |
530 | extra overhead. |
574 | extra overhead. A fork can both result in spurious notifications as well |
|
|
575 | as in libev having to destroy and recreate the epoll object, which can |
|
|
576 | take considerable time and thus should be avoided. |
|
|
577 | .Sp |
|
|
578 | All this means that, in practice, \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR can be as fast or |
|
|
579 | faster than epoll for maybe up to a hundred file descriptors, depending on |
|
|
580 | the usage. So sad. |
531 | .Sp |
581 | .Sp |
532 | While nominally embeddable in other event loops, this feature is broken in |
582 | While nominally embeddable in other event loops, this feature is broken in |
533 | all kernel versions tested so far. |
583 | all kernel versions tested so far. |
534 | .Sp |
584 | .Sp |
535 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
585 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
536 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
586 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
537 | .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 |
587 | .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 |
538 | .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 |
588 | .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 |
539 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
589 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
540 | Kqueue deserves special mention, as at the time of this writing, it was |
590 | Kqueue deserves special mention, as at the time of this writing, it |
541 | broken on all BSDs except NetBSD (usually it doesn't work reliably with |
591 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
542 | anything but sockets and pipes, except on Darwin, where of course it's |
592 | with anything but sockets and pipes, except on Darwin, where of course |
543 | completely useless). For this reason it's not being \*(L"auto-detected\*(R" unless |
593 | it's completely useless). Unlike epoll, however, whose brokenness |
544 | you explicitly specify it in the flags (i.e. using \f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR) or |
594 | is by design, these kqueue bugs can (and eventually will) be fixed |
545 | libev was compiled on a known-to-be-good (\-enough) system like NetBSD. |
595 | without \s-1API\s0 changes to existing programs. For this reason it's not being |
|
|
596 | \&\*(L"auto-detected\*(R" unless you explicitly specify it in the flags (i.e. using |
|
|
597 | \&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR) or libev was compiled on a known-to-be-good (\-enough) |
|
|
598 | system like NetBSD. |
546 | .Sp |
599 | .Sp |
547 | You still can embed kqueue into a normal poll or select backend and use it |
600 | You still can embed kqueue into a normal poll or select backend and use it |
548 | only for sockets (after having made sure that sockets work with kqueue on |
601 | only for sockets (after having made sure that sockets work with kqueue on |
549 | the target platform). See \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
602 | the target platform). See \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
550 | .Sp |
603 | .Sp |
551 | It scales in the same way as the epoll backend, but the interface to the |
604 | It scales in the same way as the epoll backend, but the interface to the |
552 | kernel is more efficient (which says nothing about its actual speed, of |
605 | kernel is more efficient (which says nothing about its actual speed, of |
553 | course). While stopping, setting and starting an I/O watcher does never |
606 | course). While stopping, setting and starting an I/O watcher does never |
554 | cause an extra system call as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to |
607 | cause an extra system call as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to |
555 | two event changes per incident. Support for \f(CW\*(C`fork ()\*(C'\fR is very bad and it |
608 | two event changes per incident. Support for \f(CW\*(C`fork ()\*(C'\fR is very bad (but |
556 | drops fds silently in similarly hard-to-detect cases. |
609 | sane, unlike epoll) and it drops fds silently in similarly hard-to-detect |
|
|
610 | cases |
557 | .Sp |
611 | .Sp |
558 | This backend usually performs well under most conditions. |
612 | This backend usually performs well under most conditions. |
559 | .Sp |
613 | .Sp |
560 | While nominally embeddable in other event loops, this doesn't work |
614 | While nominally embeddable in other event loops, this doesn't work |
561 | everywhere, so you might need to test for this. And since it is broken |
615 | everywhere, so you might need to test for this. And since it is broken |
562 | almost everywhere, you should only use it when you have a lot of sockets |
616 | almost everywhere, you should only use it when you have a lot of sockets |
563 | (for which it usually works), by embedding it into another event loop |
617 | (for which it usually works), by embedding it into another event loop |
564 | (e.g. \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR) and, did I mention it, |
618 | (e.g. \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR (but \f(CW\*(C`poll\*(C'\fR is of course |
565 | using it only for sockets. |
619 | also broken on \s-1OS\s0 X)) and, did I mention it, using it only for sockets. |
566 | .Sp |
620 | .Sp |
567 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR into an \f(CW\*(C`EVFILT_READ\*(C'\fR kevent with |
621 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR into an \f(CW\*(C`EVFILT_READ\*(C'\fR kevent with |
568 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR, and \f(CW\*(C`EV_WRITE\*(C'\fR into an \f(CW\*(C`EVFILT_WRITE\*(C'\fR kevent with |
622 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR, and \f(CW\*(C`EV_WRITE\*(C'\fR into an \f(CW\*(C`EVFILT_WRITE\*(C'\fR kevent with |
569 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR. |
623 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR. |
570 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
624 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
… | |
… | |
590 | might perform better. |
644 | might perform better. |
591 | .Sp |
645 | .Sp |
592 | On the positive side, with the exception of the spurious readiness |
646 | On the positive side, with the exception of the spurious readiness |
593 | notifications, this backend actually performed fully to specification |
647 | notifications, this backend actually performed fully to specification |
594 | in all tests and is fully embeddable, which is a rare feat among the |
648 | in all tests and is fully embeddable, which is a rare feat among the |
595 | OS-specific backends. |
649 | OS-specific backends (I vastly prefer correctness over speed hacks). |
596 | .Sp |
650 | .Sp |
597 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
651 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
598 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
652 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
599 | .ie n .IP """EVBACKEND_ALL""" 4 |
653 | .ie n .IP """EVBACKEND_ALL""" 4 |
600 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
654 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
… | |
… | |
605 | .Sp |
659 | .Sp |
606 | It is definitely not recommended to use this flag. |
660 | It is definitely not recommended to use this flag. |
607 | .RE |
661 | .RE |
608 | .RS 4 |
662 | .RS 4 |
609 | .Sp |
663 | .Sp |
610 | If one or more of these are or'ed into the flags value, then only these |
664 | If one or more of the backend flags are or'ed into the flags value, |
611 | backends will be tried (in the reverse order as listed here). If none are |
665 | then only these backends will be tried (in the reverse order as listed |
612 | specified, all backends in \f(CW\*(C`ev_recommended_backends ()\*(C'\fR will be tried. |
666 | here). If none are specified, all backends in \f(CW\*(C`ev_recommended_backends |
|
|
667 | ()\*(C'\fR will be tried. |
613 | .Sp |
668 | .Sp |
614 | Example: This is the most typical usage. |
669 | Example: This is the most typical usage. |
615 | .Sp |
670 | .Sp |
616 | .Vb 2 |
671 | .Vb 2 |
617 | \& if (!ev_default_loop (0)) |
672 | \& if (!ev_default_loop (0)) |
… | |
… | |
660 | responsibility to either stop all watchers cleanly yourself \fIbefore\fR |
715 | responsibility to either stop all watchers cleanly yourself \fIbefore\fR |
661 | calling this function, or cope with the fact afterwards (which is usually |
716 | calling this function, or cope with the fact afterwards (which is usually |
662 | the easiest thing, you can just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them |
717 | the easiest thing, you can just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them |
663 | for example). |
718 | for example). |
664 | .Sp |
719 | .Sp |
665 | Note that certain global state, such as signal state, will not be freed by |
720 | Note that certain global state, such as signal state (and installed signal |
666 | this function, and related watchers (such as signal and child watchers) |
721 | handlers), will not be freed by this function, and related watchers (such |
667 | would need to be stopped manually. |
722 | as signal and child watchers) would need to be stopped manually. |
668 | .Sp |
723 | .Sp |
669 | In general it is not advisable to call this function except in the |
724 | In general it is not advisable to call this function except in the |
670 | rare occasion where you really need to free e.g. the signal handling |
725 | rare occasion where you really need to free e.g. the signal handling |
671 | pipe fds. If you need dynamically allocated loops it is better to use |
726 | pipe fds. If you need dynamically allocated loops it is better to use |
672 | \&\f(CW\*(C`ev_loop_new\*(C'\fR and \f(CW\*(C`ev_loop_destroy\*(C'\fR). |
727 | \&\f(CW\*(C`ev_loop_new\*(C'\fR and \f(CW\*(C`ev_loop_destroy\*(C'\fR. |
673 | .IP "ev_loop_destroy (loop)" 4 |
728 | .IP "ev_loop_destroy (loop)" 4 |
674 | .IX Item "ev_loop_destroy (loop)" |
729 | .IX Item "ev_loop_destroy (loop)" |
675 | Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an |
730 | Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an |
676 | earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. |
731 | earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. |
677 | .IP "ev_default_fork ()" 4 |
732 | .IP "ev_default_fork ()" 4 |
… | |
… | |
711 | happily wraps around with enough iterations. |
766 | happily wraps around with enough iterations. |
712 | .Sp |
767 | .Sp |
713 | This value can sometimes be useful as a generation counter of sorts (it |
768 | This value can sometimes be useful as a generation counter of sorts (it |
714 | \&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with |
769 | \&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with |
715 | \&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls. |
770 | \&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls. |
|
|
771 | .IP "unsigned int ev_loop_depth (loop)" 4 |
|
|
772 | .IX Item "unsigned int ev_loop_depth (loop)" |
|
|
773 | Returns the number of times \f(CW\*(C`ev_loop\*(C'\fR was entered minus the number of |
|
|
774 | times \f(CW\*(C`ev_loop\*(C'\fR was exited, in other words, the recursion depth. |
|
|
775 | .Sp |
|
|
776 | Outside \f(CW\*(C`ev_loop\*(C'\fR, this number is zero. In a callback, this number is |
|
|
777 | \&\f(CW1\fR, unless \f(CW\*(C`ev_loop\*(C'\fR was invoked recursively (or from another thread), |
|
|
778 | in which case it is higher. |
|
|
779 | .Sp |
|
|
780 | Leaving \f(CW\*(C`ev_loop\*(C'\fR abnormally (setjmp/longjmp, cancelling the thread |
|
|
781 | etc.), doesn't count as exit. |
716 | .IP "unsigned int ev_backend (loop)" 4 |
782 | .IP "unsigned int ev_backend (loop)" 4 |
717 | .IX Item "unsigned int ev_backend (loop)" |
783 | .IX Item "unsigned int ev_backend (loop)" |
718 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
784 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
719 | use. |
785 | use. |
720 | .IP "ev_tstamp ev_now (loop)" 4 |
786 | .IP "ev_tstamp ev_now (loop)" 4 |
… | |
… | |
733 | This function is rarely useful, but when some event callback runs for a |
799 | This function is rarely useful, but when some event callback runs for a |
734 | very long time without entering the event loop, updating libev's idea of |
800 | very long time without entering the event loop, updating libev's idea of |
735 | the current time is a good idea. |
801 | the current time is a good idea. |
736 | .Sp |
802 | .Sp |
737 | See also \*(L"The special problem of time updates\*(R" in the \f(CW\*(C`ev_timer\*(C'\fR section. |
803 | See also \*(L"The special problem of time updates\*(R" in the \f(CW\*(C`ev_timer\*(C'\fR section. |
|
|
804 | .IP "ev_suspend (loop)" 4 |
|
|
805 | .IX Item "ev_suspend (loop)" |
|
|
806 | .PD 0 |
|
|
807 | .IP "ev_resume (loop)" 4 |
|
|
808 | .IX Item "ev_resume (loop)" |
|
|
809 | .PD |
|
|
810 | These two functions suspend and resume a loop, for use when the loop is |
|
|
811 | not used for a while and timeouts should not be processed. |
|
|
812 | .Sp |
|
|
813 | A typical use case would be an interactive program such as a game: When |
|
|
814 | the user presses \f(CW\*(C`^Z\*(C'\fR to suspend the game and resumes it an hour later it |
|
|
815 | would be best to handle timeouts as if no time had actually passed while |
|
|
816 | the program was suspended. This can be achieved by calling \f(CW\*(C`ev_suspend\*(C'\fR |
|
|
817 | in your \f(CW\*(C`SIGTSTP\*(C'\fR handler, sending yourself a \f(CW\*(C`SIGSTOP\*(C'\fR and calling |
|
|
818 | \&\f(CW\*(C`ev_resume\*(C'\fR directly afterwards to resume timer processing. |
|
|
819 | .Sp |
|
|
820 | Effectively, all \f(CW\*(C`ev_timer\*(C'\fR watchers will be delayed by the time spend |
|
|
821 | 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 |
|
|
822 | will be rescheduled (that is, they will lose any events that would have |
|
|
823 | occured while suspended). |
|
|
824 | .Sp |
|
|
825 | After calling \f(CW\*(C`ev_suspend\*(C'\fR you \fBmust not\fR call \fIany\fR function on the |
|
|
826 | given loop other than \f(CW\*(C`ev_resume\*(C'\fR, and you \fBmust not\fR call \f(CW\*(C`ev_resume\*(C'\fR |
|
|
827 | without a previous call to \f(CW\*(C`ev_suspend\*(C'\fR. |
|
|
828 | .Sp |
|
|
829 | Calling \f(CW\*(C`ev_suspend\*(C'\fR/\f(CW\*(C`ev_resume\*(C'\fR has the side effect of updating the |
|
|
830 | event loop time (see \f(CW\*(C`ev_now_update\*(C'\fR). |
738 | .IP "ev_loop (loop, int flags)" 4 |
831 | .IP "ev_loop (loop, int flags)" 4 |
739 | .IX Item "ev_loop (loop, int flags)" |
832 | .IX Item "ev_loop (loop, int flags)" |
740 | Finally, this is it, the event handler. This function usually is called |
833 | Finally, this is it, the event handler. This function usually is called |
741 | after you initialised all your watchers and you want to start handling |
834 | after you have initialised all your watchers and you want to start |
742 | events. |
835 | handling events. |
743 | .Sp |
836 | .Sp |
744 | If the flags argument is specified as \f(CW0\fR, it will not return until |
837 | If the flags argument is specified as \f(CW0\fR, it will not return until |
745 | either no event watchers are active anymore or \f(CW\*(C`ev_unloop\*(C'\fR was called. |
838 | either no event watchers are active anymore or \f(CW\*(C`ev_unloop\*(C'\fR was called. |
746 | .Sp |
839 | .Sp |
747 | Please note that an explicit \f(CW\*(C`ev_unloop\*(C'\fR is usually better than |
840 | Please note that an explicit \f(CW\*(C`ev_unloop\*(C'\fR is usually better than |
… | |
… | |
757 | the loop. |
850 | the loop. |
758 | .Sp |
851 | .Sp |
759 | A flags value of \f(CW\*(C`EVLOOP_ONESHOT\*(C'\fR will look for new events (waiting if |
852 | A flags value of \f(CW\*(C`EVLOOP_ONESHOT\*(C'\fR will look for new events (waiting if |
760 | necessary) and will handle those and any already outstanding ones. It |
853 | necessary) and will handle those and any already outstanding ones. It |
761 | will block your process until at least one new event arrives (which could |
854 | will block your process until at least one new event arrives (which could |
762 | be an event internal to libev itself, so there is no guarentee that a |
855 | be an event internal to libev itself, so there is no guarantee that a |
763 | user-registered callback will be called), and will return after one |
856 | user-registered callback will be called), and will return after one |
764 | iteration of the loop. |
857 | iteration of the loop. |
765 | .Sp |
858 | .Sp |
766 | This is useful if you are waiting for some external event in conjunction |
859 | This is useful if you are waiting for some external event in conjunction |
767 | with something not expressible using other libev watchers (i.e. "roll your |
860 | with something not expressible using other libev watchers (i.e. "roll your |
… | |
… | |
825 | .PD |
918 | .PD |
826 | Ref/unref can be used to add or remove a reference count on the event |
919 | Ref/unref can be used to add or remove a reference count on the event |
827 | loop: Every watcher keeps one reference, and as long as the reference |
920 | loop: Every watcher keeps one reference, and as long as the reference |
828 | count is nonzero, \f(CW\*(C`ev_loop\*(C'\fR will not return on its own. |
921 | count is nonzero, \f(CW\*(C`ev_loop\*(C'\fR will not return on its own. |
829 | .Sp |
922 | .Sp |
830 | If you have a watcher you never unregister that should not keep \f(CW\*(C`ev_loop\*(C'\fR |
923 | This is useful when you have a watcher that you never intend to |
831 | from returning, call \fIev_unref()\fR after starting, and \fIev_ref()\fR before |
924 | unregister, but that nevertheless should not keep \f(CW\*(C`ev_loop\*(C'\fR from |
|
|
925 | returning. In such a case, call \f(CW\*(C`ev_unref\*(C'\fR after starting, and \f(CW\*(C`ev_ref\*(C'\fR |
832 | stopping it. |
926 | before stopping it. |
833 | .Sp |
927 | .Sp |
834 | As an example, libev itself uses this for its internal signal pipe: It is |
928 | As an example, libev itself uses this for its internal signal pipe: It |
835 | not visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting |
929 | is not visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from |
836 | if no event watchers registered by it are active. It is also an excellent |
930 | exiting if no event watchers registered by it are active. It is also an |
837 | way to do this for generic recurring timers or from within third-party |
931 | excellent way to do this for generic recurring timers or from within |
838 | libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR |
932 | third-party libraries. Just remember to \fIunref after start\fR and \fIref |
839 | (but only if the watcher wasn't active before, or was active before, |
933 | before stop\fR (but only if the watcher wasn't active before, or was active |
840 | respectively). |
934 | before, respectively. Note also that libev might stop watchers itself |
|
|
935 | (e.g. non-repeating timers) in which case you have to \f(CW\*(C`ev_ref\*(C'\fR |
|
|
936 | in the callback). |
841 | .Sp |
937 | .Sp |
842 | Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR |
938 | Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR |
843 | running when nothing else is active. |
939 | running when nothing else is active. |
844 | .Sp |
940 | .Sp |
845 | .Vb 4 |
941 | .Vb 4 |
846 | \& struct ev_signal exitsig; |
942 | \& ev_signal exitsig; |
847 | \& ev_signal_init (&exitsig, sig_cb, SIGINT); |
943 | \& ev_signal_init (&exitsig, sig_cb, SIGINT); |
848 | \& ev_signal_start (loop, &exitsig); |
944 | \& ev_signal_start (loop, &exitsig); |
849 | \& evf_unref (loop); |
945 | \& evf_unref (loop); |
850 | .Ve |
946 | .Ve |
851 | .Sp |
947 | .Sp |
… | |
… | |
879 | .Sp |
975 | .Sp |
880 | By setting a higher \fIio collect interval\fR you allow libev to spend more |
976 | By setting a higher \fIio collect interval\fR you allow libev to spend more |
881 | time collecting I/O events, so you can handle more events per iteration, |
977 | time collecting I/O events, so you can handle more events per iteration, |
882 | at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and |
978 | at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and |
883 | \&\f(CW\*(C`ev_timer\*(C'\fR) will be not affected. Setting this to a non-null value will |
979 | \&\f(CW\*(C`ev_timer\*(C'\fR) will be not affected. Setting this to a non-null value will |
884 | introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. |
980 | introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. The |
|
|
981 | sleep time ensures that libev will not poll for I/O events more often then |
|
|
982 | once per this interval, on average. |
885 | .Sp |
983 | .Sp |
886 | Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
984 | Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
887 | to spend more time collecting timeouts, at the expense of increased |
985 | to spend more time collecting timeouts, at the expense of increased |
888 | latency/jitter/inexactness (the watcher callback will be called |
986 | latency/jitter/inexactness (the watcher callback will be called |
889 | later). \f(CW\*(C`ev_io\*(C'\fR watchers will not be affected. Setting this to a non-null |
987 | later). \f(CW\*(C`ev_io\*(C'\fR watchers will not be affected. Setting this to a non-null |
… | |
… | |
891 | .Sp |
989 | .Sp |
892 | Many (busy) programs can usually benefit by setting the I/O collect |
990 | Many (busy) programs can usually benefit by setting the I/O collect |
893 | interval to a value near \f(CW0.1\fR or so, which is often enough for |
991 | interval to a value near \f(CW0.1\fR or so, which is often enough for |
894 | interactive servers (of course not for games), likewise for timeouts. It |
992 | interactive servers (of course not for games), likewise for timeouts. It |
895 | usually doesn't make much sense to set it to a lower value than \f(CW0.01\fR, |
993 | usually doesn't make much sense to set it to a lower value than \f(CW0.01\fR, |
896 | as this approaches the timing granularity of most systems. |
994 | as this approaches the timing granularity of most systems. Note that if |
|
|
995 | you do transactions with the outside world and you can't increase the |
|
|
996 | parallelity, then this setting will limit your transaction rate (if you |
|
|
997 | need to poll once per transaction and the I/O collect interval is 0.01, |
|
|
998 | then you can't do more than 100 transations per second). |
897 | .Sp |
999 | .Sp |
898 | Setting the \fItimeout collect interval\fR can improve the opportunity for |
1000 | Setting the \fItimeout collect interval\fR can improve the opportunity for |
899 | saving power, as the program will \*(L"bundle\*(R" timer callback invocations that |
1001 | saving power, as the program will \*(L"bundle\*(R" timer callback invocations that |
900 | are \*(L"near\*(R" in time together, by delaying some, thus reducing the number of |
1002 | are \*(L"near\*(R" in time together, by delaying some, thus reducing the number of |
901 | times the process sleeps and wakes up again. Another useful technique to |
1003 | times the process sleeps and wakes up again. Another useful technique to |
902 | reduce iterations/wake\-ups is to use \f(CW\*(C`ev_periodic\*(C'\fR watchers and make sure |
1004 | reduce iterations/wake\-ups is to use \f(CW\*(C`ev_periodic\*(C'\fR watchers and make sure |
903 | they fire on, say, one-second boundaries only. |
1005 | they fire on, say, one-second boundaries only. |
|
|
1006 | .Sp |
|
|
1007 | Example: we only need 0.1s timeout granularity, and we wish not to poll |
|
|
1008 | more often than 100 times per second: |
|
|
1009 | .Sp |
|
|
1010 | .Vb 2 |
|
|
1011 | \& ev_set_timeout_collect_interval (EV_DEFAULT_UC_ 0.1); |
|
|
1012 | \& ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
|
|
1013 | .Ve |
|
|
1014 | .IP "ev_invoke_pending (loop)" 4 |
|
|
1015 | .IX Item "ev_invoke_pending (loop)" |
|
|
1016 | This call will simply invoke all pending watchers while resetting their |
|
|
1017 | pending state. Normally, \f(CW\*(C`ev_loop\*(C'\fR does this automatically when required, |
|
|
1018 | but when overriding the invoke callback this call comes handy. |
|
|
1019 | .IP "int ev_pending_count (loop)" 4 |
|
|
1020 | .IX Item "int ev_pending_count (loop)" |
|
|
1021 | Returns the number of pending watchers \- zero indicates that no watchers |
|
|
1022 | are pending. |
|
|
1023 | .IP "ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(\s-1EV_P\s0))" 4 |
|
|
1024 | .IX Item "ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))" |
|
|
1025 | This overrides the invoke pending functionality of the loop: Instead of |
|
|
1026 | invoking all pending watchers when there are any, \f(CW\*(C`ev_loop\*(C'\fR will call |
|
|
1027 | this callback instead. This is useful, for example, when you want to |
|
|
1028 | invoke the actual watchers inside another context (another thread etc.). |
|
|
1029 | .Sp |
|
|
1030 | If you want to reset the callback, use \f(CW\*(C`ev_invoke_pending\*(C'\fR as new |
|
|
1031 | callback. |
|
|
1032 | .IP "ev_set_loop_release_cb (loop, void (*release)(\s-1EV_P\s0), void (*acquire)(\s-1EV_P\s0))" 4 |
|
|
1033 | .IX Item "ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P))" |
|
|
1034 | Sometimes you want to share the same loop between multiple threads. This |
|
|
1035 | can be done relatively simply by putting mutex_lock/unlock calls around |
|
|
1036 | each call to a libev function. |
|
|
1037 | .Sp |
|
|
1038 | However, \f(CW\*(C`ev_loop\*(C'\fR can run an indefinite time, so it is not feasible to |
|
|
1039 | wait for it to return. One way around this is to wake up the loop via |
|
|
1040 | \&\f(CW\*(C`ev_unloop\*(C'\fR and \f(CW\*(C`av_async_send\*(C'\fR, another way is to set these \fIrelease\fR |
|
|
1041 | and \fIacquire\fR callbacks on the loop. |
|
|
1042 | .Sp |
|
|
1043 | When set, then \f(CW\*(C`release\*(C'\fR will be called just before the thread is |
|
|
1044 | suspended waiting for new events, and \f(CW\*(C`acquire\*(C'\fR is called just |
|
|
1045 | afterwards. |
|
|
1046 | .Sp |
|
|
1047 | Ideally, \f(CW\*(C`release\*(C'\fR will just call your mutex_unlock function, and |
|
|
1048 | \&\f(CW\*(C`acquire\*(C'\fR will just call the mutex_lock function again. |
|
|
1049 | .Sp |
|
|
1050 | While event loop modifications are allowed between invocations of |
|
|
1051 | \&\f(CW\*(C`release\*(C'\fR and \f(CW\*(C`acquire\*(C'\fR (that's their only purpose after all), no |
|
|
1052 | modifications done will affect the event loop, i.e. adding watchers will |
|
|
1053 | have no effect on the set of file descriptors being watched, or the time |
|
|
1054 | 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 |
|
|
1055 | to take note of any changes you made. |
|
|
1056 | .Sp |
|
|
1057 | In theory, threads executing \f(CW\*(C`ev_loop\*(C'\fR will be async-cancel safe between |
|
|
1058 | invocations of \f(CW\*(C`release\*(C'\fR and \f(CW\*(C`acquire\*(C'\fR. |
|
|
1059 | .Sp |
|
|
1060 | See also the locking example in the \f(CW\*(C`THREADS\*(C'\fR section later in this |
|
|
1061 | document. |
|
|
1062 | .IP "ev_set_userdata (loop, void *data)" 4 |
|
|
1063 | .IX Item "ev_set_userdata (loop, void *data)" |
|
|
1064 | .PD 0 |
|
|
1065 | .IP "ev_userdata (loop)" 4 |
|
|
1066 | .IX Item "ev_userdata (loop)" |
|
|
1067 | .PD |
|
|
1068 | Set and retrieve a single \f(CW\*(C`void *\*(C'\fR associated with a loop. When |
|
|
1069 | \&\f(CW\*(C`ev_set_userdata\*(C'\fR has never been called, then \f(CW\*(C`ev_userdata\*(C'\fR returns |
|
|
1070 | \&\f(CW0.\fR |
|
|
1071 | .Sp |
|
|
1072 | These two functions can be used to associate arbitrary data with a loop, |
|
|
1073 | and are intended solely for the \f(CW\*(C`invoke_pending_cb\*(C'\fR, \f(CW\*(C`release\*(C'\fR and |
|
|
1074 | \&\f(CW\*(C`acquire\*(C'\fR callbacks described above, but of course can be (ab\-)used for |
|
|
1075 | any other purpose as well. |
904 | .IP "ev_loop_verify (loop)" 4 |
1076 | .IP "ev_loop_verify (loop)" 4 |
905 | .IX Item "ev_loop_verify (loop)" |
1077 | .IX Item "ev_loop_verify (loop)" |
906 | This function only does something when \f(CW\*(C`EV_VERIFY\*(C'\fR support has been |
1078 | This function only does something when \f(CW\*(C`EV_VERIFY\*(C'\fR support has been |
907 | compiled in. which is the default for non-minimal builds. It tries to go |
1079 | compiled in, which is the default for non-minimal builds. It tries to go |
908 | through all internal structures and checks them for validity. If anything |
1080 | through all internal structures and checks them for validity. If anything |
909 | is found to be inconsistent, it will print an error message to standard |
1081 | is found to be inconsistent, it will print an error message to standard |
910 | error and call \f(CW\*(C`abort ()\*(C'\fR. |
1082 | error and call \f(CW\*(C`abort ()\*(C'\fR. |
911 | .Sp |
1083 | .Sp |
912 | This can be used to catch bugs inside libev itself: under normal |
1084 | This can be used to catch bugs inside libev itself: under normal |
913 | circumstances, this function will never abort as of course libev keeps its |
1085 | circumstances, this function will never abort as of course libev keeps its |
914 | data structures consistent. |
1086 | data structures consistent. |
915 | .SH "ANATOMY OF A WATCHER" |
1087 | .SH "ANATOMY OF A WATCHER" |
916 | .IX Header "ANATOMY OF A WATCHER" |
1088 | .IX Header "ANATOMY OF A WATCHER" |
|
|
1089 | In the following description, uppercase \f(CW\*(C`TYPE\*(C'\fR in names stands for the |
|
|
1090 | watcher type, e.g. \f(CW\*(C`ev_TYPE_start\*(C'\fR can mean \f(CW\*(C`ev_timer_start\*(C'\fR for timer |
|
|
1091 | watchers and \f(CW\*(C`ev_io_start\*(C'\fR for I/O watchers. |
|
|
1092 | .PP |
917 | A watcher is a structure that you create and register to record your |
1093 | A watcher is a structure that you create and register to record your |
918 | interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to |
1094 | interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to |
919 | become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that: |
1095 | become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that: |
920 | .PP |
1096 | .PP |
921 | .Vb 5 |
1097 | .Vb 5 |
922 | \& static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1098 | \& static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
923 | \& { |
1099 | \& { |
924 | \& ev_io_stop (w); |
1100 | \& ev_io_stop (w); |
925 | \& ev_unloop (loop, EVUNLOOP_ALL); |
1101 | \& ev_unloop (loop, EVUNLOOP_ALL); |
926 | \& } |
1102 | \& } |
927 | \& |
1103 | \& |
928 | \& struct ev_loop *loop = ev_default_loop (0); |
1104 | \& struct ev_loop *loop = ev_default_loop (0); |
|
|
1105 | \& |
929 | \& struct ev_io stdin_watcher; |
1106 | \& ev_io stdin_watcher; |
|
|
1107 | \& |
930 | \& ev_init (&stdin_watcher, my_cb); |
1108 | \& ev_init (&stdin_watcher, my_cb); |
931 | \& ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
1109 | \& ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
932 | \& ev_io_start (loop, &stdin_watcher); |
1110 | \& ev_io_start (loop, &stdin_watcher); |
|
|
1111 | \& |
933 | \& ev_loop (loop, 0); |
1112 | \& ev_loop (loop, 0); |
934 | .Ve |
1113 | .Ve |
935 | .PP |
1114 | .PP |
936 | As you can see, you are responsible for allocating the memory for your |
1115 | As you can see, you are responsible for allocating the memory for your |
937 | watcher structures (and it is usually a bad idea to do this on the stack, |
1116 | watcher structures (and it is \fIusually\fR a bad idea to do this on the |
938 | although this can sometimes be quite valid). |
1117 | stack). |
|
|
1118 | .PP |
|
|
1119 | Each watcher has an associated watcher structure (called \f(CW\*(C`struct ev_TYPE\*(C'\fR |
|
|
1120 | or simply \f(CW\*(C`ev_TYPE\*(C'\fR, as typedefs are provided for all watcher structs). |
939 | .PP |
1121 | .PP |
940 | Each watcher structure must be initialised by a call to \f(CW\*(C`ev_init |
1122 | Each watcher structure must be initialised by a call to \f(CW\*(C`ev_init |
941 | (watcher *, callback)\*(C'\fR, which expects a callback to be provided. This |
1123 | (watcher *, callback)\*(C'\fR, which expects a callback to be provided. This |
942 | callback gets invoked each time the event occurs (or, in the case of I/O |
1124 | callback gets invoked each time the event occurs (or, in the case of I/O |
943 | watchers, each time the event loop detects that the file descriptor given |
1125 | watchers, each time the event loop detects that the file descriptor given |
944 | is readable and/or writable). |
1126 | is readable and/or writable). |
945 | .PP |
1127 | .PP |
946 | Each watcher type has its own \f(CW\*(C`ev_<type>_set (watcher *, ...)\*(C'\fR macro |
1128 | Each watcher type further has its own \f(CW\*(C`ev_TYPE_set (watcher *, ...)\*(C'\fR |
947 | with arguments specific to this watcher type. There is also a macro |
1129 | macro to configure it, with arguments specific to the watcher type. There |
948 | to combine initialisation and setting in one call: \f(CW\*(C`ev_<type>_init |
1130 | is also a macro to combine initialisation and setting in one call: \f(CW\*(C`ev_TYPE_init (watcher *, callback, ...)\*(C'\fR. |
949 | (watcher *, callback, ...)\*(C'\fR. |
|
|
950 | .PP |
1131 | .PP |
951 | To make the watcher actually watch out for events, you have to start it |
1132 | To make the watcher actually watch out for events, you have to start it |
952 | with a watcher-specific start function (\f(CW\*(C`ev_<type>_start (loop, watcher |
1133 | with a watcher-specific start function (\f(CW\*(C`ev_TYPE_start (loop, watcher |
953 | *)\*(C'\fR), and you can stop watching for events at any time by calling the |
1134 | *)\*(C'\fR), and you can stop watching for events at any time by calling the |
954 | corresponding stop function (\f(CW\*(C`ev_<type>_stop (loop, watcher *)\*(C'\fR. |
1135 | corresponding stop function (\f(CW\*(C`ev_TYPE_stop (loop, watcher *)\*(C'\fR. |
955 | .PP |
1136 | .PP |
956 | As long as your watcher is active (has been started but not stopped) you |
1137 | As long as your watcher is active (has been started but not stopped) you |
957 | must not touch the values stored in it. Most specifically you must never |
1138 | must not touch the values stored in it. Most specifically you must never |
958 | reinitialise it or call its \f(CW\*(C`set\*(C'\fR macro. |
1139 | reinitialise it or call its \f(CW\*(C`ev_TYPE_set\*(C'\fR macro. |
959 | .PP |
1140 | .PP |
960 | Each and every callback receives the event loop pointer as first, the |
1141 | Each and every callback receives the event loop pointer as first, the |
961 | registered watcher structure as second, and a bitset of received events as |
1142 | registered watcher structure as second, and a bitset of received events as |
962 | third argument. |
1143 | third argument. |
963 | .PP |
1144 | .PP |
… | |
… | |
1024 | \&\f(CW\*(C`ev_fork\*(C'\fR). |
1205 | \&\f(CW\*(C`ev_fork\*(C'\fR). |
1025 | .ie n .IP """EV_ASYNC""" 4 |
1206 | .ie n .IP """EV_ASYNC""" 4 |
1026 | .el .IP "\f(CWEV_ASYNC\fR" 4 |
1207 | .el .IP "\f(CWEV_ASYNC\fR" 4 |
1027 | .IX Item "EV_ASYNC" |
1208 | .IX Item "EV_ASYNC" |
1028 | The given async watcher has been asynchronously notified (see \f(CW\*(C`ev_async\*(C'\fR). |
1209 | The given async watcher has been asynchronously notified (see \f(CW\*(C`ev_async\*(C'\fR). |
|
|
1210 | .ie n .IP """EV_CUSTOM""" 4 |
|
|
1211 | .el .IP "\f(CWEV_CUSTOM\fR" 4 |
|
|
1212 | .IX Item "EV_CUSTOM" |
|
|
1213 | Not ever sent (or otherwise used) by libev itself, but can be freely used |
|
|
1214 | by libev users to signal watchers (e.g. via \f(CW\*(C`ev_feed_event\*(C'\fR). |
1029 | .ie n .IP """EV_ERROR""" 4 |
1215 | .ie n .IP """EV_ERROR""" 4 |
1030 | .el .IP "\f(CWEV_ERROR\fR" 4 |
1216 | .el .IP "\f(CWEV_ERROR\fR" 4 |
1031 | .IX Item "EV_ERROR" |
1217 | .IX Item "EV_ERROR" |
1032 | An unspecified error has occurred, the watcher has been stopped. This might |
1218 | An unspecified error has occurred, the watcher has been stopped. This might |
1033 | happen because the watcher could not be properly started because libev |
1219 | happen because the watcher could not be properly started because libev |
1034 | ran out of memory, a file descriptor was found to be closed or any other |
1220 | ran out of memory, a file descriptor was found to be closed or any other |
|
|
1221 | problem. Libev considers these application bugs. |
|
|
1222 | .Sp |
1035 | problem. You best act on it by reporting the problem and somehow coping |
1223 | You best act on it by reporting the problem and somehow coping with the |
1036 | with the watcher being stopped. |
1224 | watcher being stopped. Note that well-written programs should not receive |
|
|
1225 | an error ever, so when your watcher receives it, this usually indicates a |
|
|
1226 | bug in your program. |
1037 | .Sp |
1227 | .Sp |
1038 | Libev will usually signal a few \*(L"dummy\*(R" events together with an error, for |
1228 | Libev will usually signal a few \*(L"dummy\*(R" events together with an error, for |
1039 | example it might indicate that a fd is readable or writable, and if your |
1229 | example it might indicate that a fd is readable or writable, and if your |
1040 | callbacks is well-written it can just attempt the operation and cope with |
1230 | callbacks is well-written it can just attempt the operation and cope with |
1041 | the error from \fIread()\fR or \fIwrite()\fR. This will not work in multi-threaded |
1231 | the error from \fIread()\fR or \fIwrite()\fR. This will not work in multi-threaded |
1042 | programs, though, as the fd could already be closed and reused for another |
1232 | programs, though, as the fd could already be closed and reused for another |
1043 | thing, so beware. |
1233 | thing, so beware. |
1044 | .Sh "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" |
1234 | .SS "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" |
1045 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1235 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1046 | In the following description, \f(CW\*(C`TYPE\*(C'\fR stands for the watcher type, |
|
|
1047 | e.g. \f(CW\*(C`timer\*(C'\fR for \f(CW\*(C`ev_timer\*(C'\fR watchers and \f(CW\*(C`io\*(C'\fR for \f(CW\*(C`ev_io\*(C'\fR watchers. |
|
|
1048 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
1236 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
1049 | .el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 |
1237 | .el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 |
1050 | .IX Item "ev_init (ev_TYPE *watcher, callback)" |
1238 | .IX Item "ev_init (ev_TYPE *watcher, callback)" |
1051 | This macro initialises the generic portion of a watcher. The contents |
1239 | This macro initialises the generic portion of a watcher. The contents |
1052 | of the watcher object can be arbitrary (so \f(CW\*(C`malloc\*(C'\fR will do). Only |
1240 | of the watcher object can be arbitrary (so \f(CW\*(C`malloc\*(C'\fR will do). Only |
… | |
… | |
1056 | which rolls both calls into one. |
1244 | which rolls both calls into one. |
1057 | .Sp |
1245 | .Sp |
1058 | You can reinitialise a watcher at any time as long as it has been stopped |
1246 | You can reinitialise a watcher at any time as long as it has been stopped |
1059 | (or never started) and there are no pending events outstanding. |
1247 | (or never started) and there are no pending events outstanding. |
1060 | .Sp |
1248 | .Sp |
1061 | The callback is always of type \f(CW\*(C`void (*)(ev_loop *loop, ev_TYPE *watcher, |
1249 | The callback is always of type \f(CW\*(C`void (*)(struct ev_loop *loop, ev_TYPE *watcher, |
1062 | int revents)\*(C'\fR. |
1250 | int revents)\*(C'\fR. |
1063 | .Sp |
1251 | .Sp |
1064 | Example: Initialise an \f(CW\*(C`ev_io\*(C'\fR watcher in two steps. |
1252 | Example: Initialise an \f(CW\*(C`ev_io\*(C'\fR watcher in two steps. |
1065 | .Sp |
1253 | .Sp |
1066 | .Vb 3 |
1254 | .Vb 3 |
1067 | \& ev_io w; |
1255 | \& ev_io w; |
1068 | \& ev_init (&w, my_cb); |
1256 | \& ev_init (&w, my_cb); |
1069 | \& ev_io_set (&w, STDIN_FILENO, EV_READ); |
1257 | \& ev_io_set (&w, STDIN_FILENO, EV_READ); |
1070 | .Ve |
1258 | .Ve |
1071 | .ie n .IP """ev_TYPE_set"" (ev_TYPE *, [args])" 4 |
1259 | .ie n .IP """ev_TYPE_set"" (ev_TYPE *watcher, [args])" 4 |
1072 | .el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *, [args])" 4 |
1260 | .el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *watcher, [args])" 4 |
1073 | .IX Item "ev_TYPE_set (ev_TYPE *, [args])" |
1261 | .IX Item "ev_TYPE_set (ev_TYPE *watcher, [args])" |
1074 | This macro initialises the type-specific parts of a watcher. You need to |
1262 | This macro initialises the type-specific parts of a watcher. You need to |
1075 | call \f(CW\*(C`ev_init\*(C'\fR at least once before you call this macro, but you can |
1263 | call \f(CW\*(C`ev_init\*(C'\fR at least once before you call this macro, but you can |
1076 | call \f(CW\*(C`ev_TYPE_set\*(C'\fR any number of times. You must not, however, call this |
1264 | call \f(CW\*(C`ev_TYPE_set\*(C'\fR any number of times. You must not, however, call this |
1077 | macro on a watcher that is active (it can be pending, however, which is a |
1265 | macro on a watcher that is active (it can be pending, however, which is a |
1078 | difference to the \f(CW\*(C`ev_init\*(C'\fR macro). |
1266 | difference to the \f(CW\*(C`ev_init\*(C'\fR macro). |
… | |
… | |
1091 | Example: Initialise and set an \f(CW\*(C`ev_io\*(C'\fR watcher in one step. |
1279 | Example: Initialise and set an \f(CW\*(C`ev_io\*(C'\fR watcher in one step. |
1092 | .Sp |
1280 | .Sp |
1093 | .Vb 1 |
1281 | .Vb 1 |
1094 | \& ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1282 | \& ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1095 | .Ve |
1283 | .Ve |
1096 | .ie n .IP """ev_TYPE_start"" (loop *, ev_TYPE *watcher)" 4 |
1284 | .ie n .IP """ev_TYPE_start"" (loop, ev_TYPE *watcher)" 4 |
1097 | .el .IP "\f(CWev_TYPE_start\fR (loop *, ev_TYPE *watcher)" 4 |
1285 | .el .IP "\f(CWev_TYPE_start\fR (loop, ev_TYPE *watcher)" 4 |
1098 | .IX Item "ev_TYPE_start (loop *, ev_TYPE *watcher)" |
1286 | .IX Item "ev_TYPE_start (loop, ev_TYPE *watcher)" |
1099 | Starts (activates) the given watcher. Only active watchers will receive |
1287 | Starts (activates) the given watcher. Only active watchers will receive |
1100 | events. If the watcher is already active nothing will happen. |
1288 | events. If the watcher is already active nothing will happen. |
1101 | .Sp |
1289 | .Sp |
1102 | Example: Start the \f(CW\*(C`ev_io\*(C'\fR watcher that is being abused as example in this |
1290 | Example: Start the \f(CW\*(C`ev_io\*(C'\fR watcher that is being abused as example in this |
1103 | whole section. |
1291 | whole section. |
1104 | .Sp |
1292 | .Sp |
1105 | .Vb 1 |
1293 | .Vb 1 |
1106 | \& ev_io_start (EV_DEFAULT_UC, &w); |
1294 | \& ev_io_start (EV_DEFAULT_UC, &w); |
1107 | .Ve |
1295 | .Ve |
1108 | .ie n .IP """ev_TYPE_stop"" (loop *, ev_TYPE *watcher)" 4 |
1296 | .ie n .IP """ev_TYPE_stop"" (loop, ev_TYPE *watcher)" 4 |
1109 | .el .IP "\f(CWev_TYPE_stop\fR (loop *, ev_TYPE *watcher)" 4 |
1297 | .el .IP "\f(CWev_TYPE_stop\fR (loop, ev_TYPE *watcher)" 4 |
1110 | .IX Item "ev_TYPE_stop (loop *, ev_TYPE *watcher)" |
1298 | .IX Item "ev_TYPE_stop (loop, ev_TYPE *watcher)" |
1111 | Stops the given watcher if active, and clears the pending status (whether |
1299 | Stops the given watcher if active, and clears the pending status (whether |
1112 | the watcher was active or not). |
1300 | the watcher was active or not). |
1113 | .Sp |
1301 | .Sp |
1114 | It is possible that stopped watchers are pending \- for example, |
1302 | It is possible that stopped watchers are pending \- for example, |
1115 | non-repeating timers are being stopped when they become pending \- but |
1303 | non-repeating timers are being stopped when they become pending \- but |
… | |
… | |
1134 | Returns the callback currently set on the watcher. |
1322 | Returns the callback currently set on the watcher. |
1135 | .IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 |
1323 | .IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 |
1136 | .IX Item "ev_cb_set (ev_TYPE *watcher, callback)" |
1324 | .IX Item "ev_cb_set (ev_TYPE *watcher, callback)" |
1137 | Change the callback. You can change the callback at virtually any time |
1325 | Change the callback. You can change the callback at virtually any time |
1138 | (modulo threads). |
1326 | (modulo threads). |
1139 | .IP "ev_set_priority (ev_TYPE *watcher, priority)" 4 |
1327 | .IP "ev_set_priority (ev_TYPE *watcher, int priority)" 4 |
1140 | .IX Item "ev_set_priority (ev_TYPE *watcher, priority)" |
1328 | .IX Item "ev_set_priority (ev_TYPE *watcher, int priority)" |
1141 | .PD 0 |
1329 | .PD 0 |
1142 | .IP "int ev_priority (ev_TYPE *watcher)" 4 |
1330 | .IP "int ev_priority (ev_TYPE *watcher)" 4 |
1143 | .IX Item "int ev_priority (ev_TYPE *watcher)" |
1331 | .IX Item "int ev_priority (ev_TYPE *watcher)" |
1144 | .PD |
1332 | .PD |
1145 | Set and query the priority of the watcher. The priority is a small |
1333 | Set and query the priority of the watcher. The priority is a small |
1146 | integer between \f(CW\*(C`EV_MAXPRI\*(C'\fR (default: \f(CW2\fR) and \f(CW\*(C`EV_MINPRI\*(C'\fR |
1334 | integer between \f(CW\*(C`EV_MAXPRI\*(C'\fR (default: \f(CW2\fR) and \f(CW\*(C`EV_MINPRI\*(C'\fR |
1147 | (default: \f(CW\*(C`\-2\*(C'\fR). Pending watchers with higher priority will be invoked |
1335 | (default: \f(CW\*(C`\-2\*(C'\fR). Pending watchers with higher priority will be invoked |
1148 | before watchers with lower priority, but priority will not keep watchers |
1336 | before watchers with lower priority, but priority will not keep watchers |
1149 | from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers). |
1337 | from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers). |
1150 | .Sp |
1338 | .Sp |
1151 | This means that priorities are \fIonly\fR used for ordering callback |
|
|
1152 | invocation after new events have been received. This is useful, for |
|
|
1153 | example, to reduce latency after idling, or more often, to bind two |
|
|
1154 | watchers on the same event and make sure one is called first. |
|
|
1155 | .Sp |
|
|
1156 | If you need to suppress invocation when higher priority events are pending |
1339 | If you need to suppress invocation when higher priority events are pending |
1157 | you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality. |
1340 | you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality. |
1158 | .Sp |
1341 | .Sp |
1159 | You \fImust not\fR change the priority of a watcher as long as it is active or |
1342 | You \fImust not\fR change the priority of a watcher as long as it is active or |
1160 | pending. |
1343 | pending. |
1161 | .Sp |
1344 | .Sp |
|
|
1345 | Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is |
|
|
1346 | fine, as long as you do not mind that the priority value you query might |
|
|
1347 | or might not have been clamped to the valid range. |
|
|
1348 | .Sp |
1162 | The default priority used by watchers when no priority has been set is |
1349 | The default priority used by watchers when no priority has been set is |
1163 | always \f(CW0\fR, which is supposed to not be too high and not be too low :). |
1350 | always \f(CW0\fR, which is supposed to not be too high and not be too low :). |
1164 | .Sp |
1351 | .Sp |
1165 | Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is |
1352 | See \*(L"\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0\*(R", below, for a more thorough treatment of |
1166 | fine, as long as you do not mind that the priority value you query might |
1353 | priorities. |
1167 | or might not have been adjusted to be within valid range. |
|
|
1168 | .IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 |
1354 | .IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 |
1169 | .IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" |
1355 | .IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" |
1170 | 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 |
1356 | 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 |
1171 | \&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback |
1357 | \&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback |
1172 | can deal with that fact, as both are simply passed through to the |
1358 | can deal with that fact, as both are simply passed through to the |
… | |
… | |
1177 | returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the |
1363 | returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the |
1178 | watcher isn't pending it does nothing and returns \f(CW0\fR. |
1364 | watcher isn't pending it does nothing and returns \f(CW0\fR. |
1179 | .Sp |
1365 | .Sp |
1180 | Sometimes it can be useful to \*(L"poll\*(R" a watcher instead of waiting for its |
1366 | Sometimes it can be useful to \*(L"poll\*(R" a watcher instead of waiting for its |
1181 | callback to be invoked, which can be accomplished with this function. |
1367 | callback to be invoked, which can be accomplished with this function. |
|
|
1368 | .IP "ev_feed_event (loop, ev_TYPE *watcher, int revents)" 4 |
|
|
1369 | .IX Item "ev_feed_event (loop, ev_TYPE *watcher, int revents)" |
|
|
1370 | Feeds the given event set into the event loop, as if the specified event |
|
|
1371 | had happened for the specified watcher (which must be a pointer to an |
|
|
1372 | initialised but not necessarily started event watcher). Obviously you must |
|
|
1373 | not free the watcher as long as it has pending events. |
|
|
1374 | .Sp |
|
|
1375 | Stopping the watcher, letting libev invoke it, or calling |
|
|
1376 | \&\f(CW\*(C`ev_clear_pending\*(C'\fR will clear the pending event, even if the watcher was |
|
|
1377 | not started in the first place. |
|
|
1378 | .Sp |
|
|
1379 | See also \f(CW\*(C`ev_feed_fd_event\*(C'\fR and \f(CW\*(C`ev_feed_signal_event\*(C'\fR for related |
|
|
1380 | functions that do not need a watcher. |
1182 | .Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
1381 | .SS "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
1183 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
1382 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
1184 | Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change |
1383 | Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change |
1185 | and read at any time: libev will completely ignore it. This can be used |
1384 | and read at any time: libev will completely ignore it. This can be used |
1186 | to associate arbitrary data with your watcher. If you need more data and |
1385 | to associate arbitrary data with your watcher. If you need more data and |
1187 | don't want to allocate memory and store a pointer to it in that data |
1386 | don't want to allocate memory and store a pointer to it in that data |
… | |
… | |
1189 | data: |
1388 | data: |
1190 | .PP |
1389 | .PP |
1191 | .Vb 7 |
1390 | .Vb 7 |
1192 | \& struct my_io |
1391 | \& struct my_io |
1193 | \& { |
1392 | \& { |
1194 | \& struct ev_io io; |
1393 | \& ev_io io; |
1195 | \& int otherfd; |
1394 | \& int otherfd; |
1196 | \& void *somedata; |
1395 | \& void *somedata; |
1197 | \& struct whatever *mostinteresting; |
1396 | \& struct whatever *mostinteresting; |
1198 | \& }; |
1397 | \& }; |
1199 | \& |
1398 | \& |
… | |
… | |
1204 | .PP |
1403 | .PP |
1205 | And since your callback will be called with a pointer to the watcher, you |
1404 | And since your callback will be called with a pointer to the watcher, you |
1206 | can cast it back to your own type: |
1405 | can cast it back to your own type: |
1207 | .PP |
1406 | .PP |
1208 | .Vb 5 |
1407 | .Vb 5 |
1209 | \& static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents) |
1408 | \& static void my_cb (struct ev_loop *loop, ev_io *w_, int revents) |
1210 | \& { |
1409 | \& { |
1211 | \& struct my_io *w = (struct my_io *)w_; |
1410 | \& struct my_io *w = (struct my_io *)w_; |
1212 | \& ... |
1411 | \& ... |
1213 | \& } |
1412 | \& } |
1214 | .Ve |
1413 | .Ve |
… | |
… | |
1236 | .PP |
1435 | .PP |
1237 | .Vb 1 |
1436 | .Vb 1 |
1238 | \& #include <stddef.h> |
1437 | \& #include <stddef.h> |
1239 | \& |
1438 | \& |
1240 | \& static void |
1439 | \& static void |
1241 | \& t1_cb (EV_P_ struct ev_timer *w, int revents) |
1440 | \& t1_cb (EV_P_ ev_timer *w, int revents) |
1242 | \& { |
1441 | \& { |
1243 | \& struct my_biggy big = (struct my_biggy * |
1442 | \& struct my_biggy big = (struct my_biggy *) |
1244 | \& (((char *)w) \- offsetof (struct my_biggy, t1)); |
1443 | \& (((char *)w) \- offsetof (struct my_biggy, t1)); |
1245 | \& } |
1444 | \& } |
1246 | \& |
1445 | \& |
1247 | \& static void |
1446 | \& static void |
1248 | \& t2_cb (EV_P_ struct ev_timer *w, int revents) |
1447 | \& t2_cb (EV_P_ ev_timer *w, int revents) |
1249 | \& { |
1448 | \& { |
1250 | \& struct my_biggy big = (struct my_biggy * |
1449 | \& struct my_biggy big = (struct my_biggy *) |
1251 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
1450 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
1252 | \& } |
1451 | \& } |
1253 | .Ve |
1452 | .Ve |
|
|
1453 | .SS "\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0" |
|
|
1454 | .IX Subsection "WATCHER PRIORITY MODELS" |
|
|
1455 | Many event loops support \fIwatcher priorities\fR, which are usually small |
|
|
1456 | integers that influence the ordering of event callback invocation |
|
|
1457 | between watchers in some way, all else being equal. |
|
|
1458 | .PP |
|
|
1459 | In libev, Watcher priorities can be set using \f(CW\*(C`ev_set_priority\*(C'\fR. See its |
|
|
1460 | description for the more technical details such as the actual priority |
|
|
1461 | range. |
|
|
1462 | .PP |
|
|
1463 | There are two common ways how these these priorities are being interpreted |
|
|
1464 | by event loops: |
|
|
1465 | .PP |
|
|
1466 | In the more common lock-out model, higher priorities \*(L"lock out\*(R" invocation |
|
|
1467 | of lower priority watchers, which means as long as higher priority |
|
|
1468 | watchers receive events, lower priority watchers are not being invoked. |
|
|
1469 | .PP |
|
|
1470 | The less common only-for-ordering model uses priorities solely to order |
|
|
1471 | callback invocation within a single event loop iteration: Higher priority |
|
|
1472 | watchers are invoked before lower priority ones, but they all get invoked |
|
|
1473 | before polling for new events. |
|
|
1474 | .PP |
|
|
1475 | Libev uses the second (only-for-ordering) model for all its watchers |
|
|
1476 | except for idle watchers (which use the lock-out model). |
|
|
1477 | .PP |
|
|
1478 | The rationale behind this is that implementing the lock-out model for |
|
|
1479 | watchers is not well supported by most kernel interfaces, and most event |
|
|
1480 | libraries will just poll for the same events again and again as long as |
|
|
1481 | their callbacks have not been executed, which is very inefficient in the |
|
|
1482 | common case of one high-priority watcher locking out a mass of lower |
|
|
1483 | priority ones. |
|
|
1484 | .PP |
|
|
1485 | Static (ordering) priorities are most useful when you have two or more |
|
|
1486 | watchers handling the same resource: a typical usage example is having an |
|
|
1487 | \&\f(CW\*(C`ev_io\*(C'\fR watcher to receive data, and an associated \f(CW\*(C`ev_timer\*(C'\fR to handle |
|
|
1488 | timeouts. Under load, data might be received while the program handles |
|
|
1489 | other jobs, but since timers normally get invoked first, the timeout |
|
|
1490 | handler will be executed before checking for data. In that case, giving |
|
|
1491 | the timer a lower priority than the I/O watcher ensures that I/O will be |
|
|
1492 | handled first even under adverse conditions (which is usually, but not |
|
|
1493 | always, what you want). |
|
|
1494 | .PP |
|
|
1495 | Since idle watchers use the \*(L"lock-out\*(R" model, meaning that idle watchers |
|
|
1496 | will only be executed when no same or higher priority watchers have |
|
|
1497 | received events, they can be used to implement the \*(L"lock-out\*(R" model when |
|
|
1498 | required. |
|
|
1499 | .PP |
|
|
1500 | For example, to emulate how many other event libraries handle priorities, |
|
|
1501 | you can associate an \f(CW\*(C`ev_idle\*(C'\fR watcher to each such watcher, and in |
|
|
1502 | the normal watcher callback, you just start the idle watcher. The real |
|
|
1503 | processing is done in the idle watcher callback. This causes libev to |
|
|
1504 | continously poll and process kernel event data for the watcher, but when |
|
|
1505 | the lock-out case is known to be rare (which in turn is rare :), this is |
|
|
1506 | workable. |
|
|
1507 | .PP |
|
|
1508 | Usually, however, the lock-out model implemented that way will perform |
|
|
1509 | miserably under the type of load it was designed to handle. In that case, |
|
|
1510 | it might be preferable to stop the real watcher before starting the |
|
|
1511 | idle watcher, so the kernel will not have to process the event in case |
|
|
1512 | the actual processing will be delayed for considerable time. |
|
|
1513 | .PP |
|
|
1514 | Here is an example of an I/O watcher that should run at a strictly lower |
|
|
1515 | priority than the default, and which should only process data when no |
|
|
1516 | other events are pending: |
|
|
1517 | .PP |
|
|
1518 | .Vb 2 |
|
|
1519 | \& ev_idle idle; // actual processing watcher |
|
|
1520 | \& ev_io io; // actual event watcher |
|
|
1521 | \& |
|
|
1522 | \& static void |
|
|
1523 | \& io_cb (EV_P_ ev_io *w, int revents) |
|
|
1524 | \& { |
|
|
1525 | \& // stop the I/O watcher, we received the event, but |
|
|
1526 | \& // are not yet ready to handle it. |
|
|
1527 | \& ev_io_stop (EV_A_ w); |
|
|
1528 | \& |
|
|
1529 | \& // start the idle watcher to ahndle the actual event. |
|
|
1530 | \& // it will not be executed as long as other watchers |
|
|
1531 | \& // with the default priority are receiving events. |
|
|
1532 | \& ev_idle_start (EV_A_ &idle); |
|
|
1533 | \& } |
|
|
1534 | \& |
|
|
1535 | \& static void |
|
|
1536 | \& idle_cb (EV_P_ ev_idle *w, int revents) |
|
|
1537 | \& { |
|
|
1538 | \& // actual processing |
|
|
1539 | \& read (STDIN_FILENO, ...); |
|
|
1540 | \& |
|
|
1541 | \& // have to start the I/O watcher again, as |
|
|
1542 | \& // we have handled the event |
|
|
1543 | \& ev_io_start (EV_P_ &io); |
|
|
1544 | \& } |
|
|
1545 | \& |
|
|
1546 | \& // initialisation |
|
|
1547 | \& ev_idle_init (&idle, idle_cb); |
|
|
1548 | \& ev_io_init (&io, io_cb, STDIN_FILENO, EV_READ); |
|
|
1549 | \& ev_io_start (EV_DEFAULT_ &io); |
|
|
1550 | .Ve |
|
|
1551 | .PP |
|
|
1552 | In the \*(L"real\*(R" world, it might also be beneficial to start a timer, so that |
|
|
1553 | low-priority connections can not be locked out forever under load. This |
|
|
1554 | enables your program to keep a lower latency for important connections |
|
|
1555 | during short periods of high load, while not completely locking out less |
|
|
1556 | important ones. |
1254 | .SH "WATCHER TYPES" |
1557 | .SH "WATCHER TYPES" |
1255 | .IX Header "WATCHER TYPES" |
1558 | .IX Header "WATCHER TYPES" |
1256 | This section describes each watcher in detail, but will not repeat |
1559 | This section describes each watcher in detail, but will not repeat |
1257 | information given in the last section. Any initialisation/set macros, |
1560 | information given in the last section. Any initialisation/set macros, |
1258 | functions and members specific to the watcher type are explained. |
1561 | functions and members specific to the watcher type are explained. |
… | |
… | |
1263 | watcher is stopped to your hearts content), or \fI[read\-write]\fR, which |
1566 | watcher is stopped to your hearts content), or \fI[read\-write]\fR, which |
1264 | means you can expect it to have some sensible content while the watcher |
1567 | means you can expect it to have some sensible content while the watcher |
1265 | is active, but you can also modify it. Modifying it may not do something |
1568 | is active, but you can also modify it. Modifying it may not do something |
1266 | sensible or take immediate effect (or do anything at all), but libev will |
1569 | sensible or take immediate effect (or do anything at all), but libev will |
1267 | not crash or malfunction in any way. |
1570 | not crash or malfunction in any way. |
1268 | .ie n .Sh """ev_io"" \- is this file descriptor readable or writable?" |
1571 | .ie n .SS """ev_io"" \- is this file descriptor readable or writable?" |
1269 | .el .Sh "\f(CWev_io\fP \- is this file descriptor readable or writable?" |
1572 | .el .SS "\f(CWev_io\fP \- is this file descriptor readable or writable?" |
1270 | .IX Subsection "ev_io - is this file descriptor readable or writable?" |
1573 | .IX Subsection "ev_io - is this file descriptor readable or writable?" |
1271 | I/O watchers check whether a file descriptor is readable or writable |
1574 | I/O watchers check whether a file descriptor is readable or writable |
1272 | in each iteration of the event loop, or, more precisely, when reading |
1575 | in each iteration of the event loop, or, more precisely, when reading |
1273 | would not block the process and writing would at least be able to write |
1576 | would not block the process and writing would at least be able to write |
1274 | some data. This behaviour is called level-triggering because you keep |
1577 | some data. This behaviour is called level-triggering because you keep |
… | |
… | |
1281 | descriptors to non-blocking mode is also usually a good idea (but not |
1584 | descriptors to non-blocking mode is also usually a good idea (but not |
1282 | required if you know what you are doing). |
1585 | required if you know what you are doing). |
1283 | .PP |
1586 | .PP |
1284 | If you cannot use non-blocking mode, then force the use of a |
1587 | If you cannot use non-blocking mode, then force the use of a |
1285 | known-to-be-good backend (at the time of this writing, this includes only |
1588 | known-to-be-good backend (at the time of this writing, this includes only |
1286 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and \f(CW\*(C`EVBACKEND_POLL\*(C'\fR). |
1589 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and \f(CW\*(C`EVBACKEND_POLL\*(C'\fR). The same applies to file |
|
|
1590 | descriptors for which non-blocking operation makes no sense (such as |
|
|
1591 | files) \- libev doesn't guarentee any specific behaviour in that case. |
1287 | .PP |
1592 | .PP |
1288 | Another thing you have to watch out for is that it is quite easy to |
1593 | Another thing you have to watch out for is that it is quite easy to |
1289 | receive \*(L"spurious\*(R" readiness notifications, that is your callback might |
1594 | receive \*(L"spurious\*(R" readiness notifications, that is your callback might |
1290 | be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block |
1595 | be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block |
1291 | because there is no data. Not only are some backends known to create a |
1596 | because there is no data. Not only are some backends known to create a |
… | |
… | |
1387 | readable, but only once. Since it is likely line-buffered, you could |
1692 | readable, but only once. Since it is likely line-buffered, you could |
1388 | attempt to read a whole line in the callback. |
1693 | attempt to read a whole line in the callback. |
1389 | .PP |
1694 | .PP |
1390 | .Vb 6 |
1695 | .Vb 6 |
1391 | \& static void |
1696 | \& static void |
1392 | \& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1697 | \& stdin_readable_cb (struct ev_loop *loop, ev_io *w, int revents) |
1393 | \& { |
1698 | \& { |
1394 | \& ev_io_stop (loop, w); |
1699 | \& ev_io_stop (loop, w); |
1395 | \& .. read from stdin here (or from w\->fd) and handle any I/O errors |
1700 | \& .. read from stdin here (or from w\->fd) and handle any I/O errors |
1396 | \& } |
1701 | \& } |
1397 | \& |
1702 | \& |
1398 | \& ... |
1703 | \& ... |
1399 | \& struct ev_loop *loop = ev_default_init (0); |
1704 | \& struct ev_loop *loop = ev_default_init (0); |
1400 | \& struct ev_io stdin_readable; |
1705 | \& ev_io stdin_readable; |
1401 | \& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1706 | \& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1402 | \& ev_io_start (loop, &stdin_readable); |
1707 | \& ev_io_start (loop, &stdin_readable); |
1403 | \& ev_loop (loop, 0); |
1708 | \& ev_loop (loop, 0); |
1404 | .Ve |
1709 | .Ve |
1405 | .ie n .Sh """ev_timer"" \- relative and optionally repeating timeouts" |
1710 | .ie n .SS """ev_timer"" \- relative and optionally repeating timeouts" |
1406 | .el .Sh "\f(CWev_timer\fP \- relative and optionally repeating timeouts" |
1711 | .el .SS "\f(CWev_timer\fP \- relative and optionally repeating timeouts" |
1407 | .IX Subsection "ev_timer - relative and optionally repeating timeouts" |
1712 | .IX Subsection "ev_timer - relative and optionally repeating timeouts" |
1408 | Timer watchers are simple relative timers that generate an event after a |
1713 | Timer watchers are simple relative timers that generate an event after a |
1409 | given time, and optionally repeating in regular intervals after that. |
1714 | given time, and optionally repeating in regular intervals after that. |
1410 | .PP |
1715 | .PP |
1411 | The timers are based on real time, that is, if you register an event that |
1716 | The timers are based on real time, that is, if you register an event that |
… | |
… | |
1413 | year, it will still time out after (roughly) one hour. \*(L"Roughly\*(R" because |
1718 | year, it will still time out after (roughly) one hour. \*(L"Roughly\*(R" because |
1414 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1719 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1415 | monotonic clock option helps a lot here). |
1720 | monotonic clock option helps a lot here). |
1416 | .PP |
1721 | .PP |
1417 | The callback is guaranteed to be invoked only \fIafter\fR its timeout has |
1722 | The callback is guaranteed to be invoked only \fIafter\fR its timeout has |
1418 | passed, but if multiple timers become ready during the same loop iteration |
1723 | passed (not \fIat\fR, so on systems with very low-resolution clocks this |
1419 | then order of execution is undefined. |
1724 | might introduce a small delay). If multiple timers become ready during the |
|
|
1725 | same loop iteration then the ones with earlier time-out values are invoked |
|
|
1726 | before ones of the same priority with later time-out values (but this is |
|
|
1727 | no longer true when a callback calls \f(CW\*(C`ev_loop\*(C'\fR recursively). |
|
|
1728 | .PP |
|
|
1729 | \fIBe smart about timeouts\fR |
|
|
1730 | .IX Subsection "Be smart about timeouts" |
|
|
1731 | .PP |
|
|
1732 | Many real-world problems involve some kind of timeout, usually for error |
|
|
1733 | recovery. A typical example is an \s-1HTTP\s0 request \- if the other side hangs, |
|
|
1734 | you want to raise some error after a while. |
|
|
1735 | .PP |
|
|
1736 | What follows are some ways to handle this problem, from obvious and |
|
|
1737 | inefficient to smart and efficient. |
|
|
1738 | .PP |
|
|
1739 | In the following, a 60 second activity timeout is assumed \- a timeout that |
|
|
1740 | gets reset to 60 seconds each time there is activity (e.g. each time some |
|
|
1741 | data or other life sign was received). |
|
|
1742 | .IP "1. Use a timer and stop, reinitialise and start it on activity." 4 |
|
|
1743 | .IX Item "1. Use a timer and stop, reinitialise and start it on activity." |
|
|
1744 | This is the most obvious, but not the most simple way: In the beginning, |
|
|
1745 | start the watcher: |
|
|
1746 | .Sp |
|
|
1747 | .Vb 2 |
|
|
1748 | \& ev_timer_init (timer, callback, 60., 0.); |
|
|
1749 | \& ev_timer_start (loop, timer); |
|
|
1750 | .Ve |
|
|
1751 | .Sp |
|
|
1752 | Then, each time there is some activity, \f(CW\*(C`ev_timer_stop\*(C'\fR it, initialise it |
|
|
1753 | and start it again: |
|
|
1754 | .Sp |
|
|
1755 | .Vb 3 |
|
|
1756 | \& ev_timer_stop (loop, timer); |
|
|
1757 | \& ev_timer_set (timer, 60., 0.); |
|
|
1758 | \& ev_timer_start (loop, timer); |
|
|
1759 | .Ve |
|
|
1760 | .Sp |
|
|
1761 | This is relatively simple to implement, but means that each time there is |
|
|
1762 | some activity, libev will first have to remove the timer from its internal |
|
|
1763 | data structure and then add it again. Libev tries to be fast, but it's |
|
|
1764 | still not a constant-time operation. |
|
|
1765 | .ie n .IP "2. Use a timer and re-start it with ""ev_timer_again"" inactivity." 4 |
|
|
1766 | .el .IP "2. Use a timer and re-start it with \f(CWev_timer_again\fR inactivity." 4 |
|
|
1767 | .IX Item "2. Use a timer and re-start it with ev_timer_again inactivity." |
|
|
1768 | This is the easiest way, and involves using \f(CW\*(C`ev_timer_again\*(C'\fR instead of |
|
|
1769 | \&\f(CW\*(C`ev_timer_start\*(C'\fR. |
|
|
1770 | .Sp |
|
|
1771 | To implement this, configure an \f(CW\*(C`ev_timer\*(C'\fR with a \f(CW\*(C`repeat\*(C'\fR value |
|
|
1772 | of \f(CW60\fR and then call \f(CW\*(C`ev_timer_again\*(C'\fR at start and each time you |
|
|
1773 | successfully read or write some data. If you go into an idle state where |
|
|
1774 | you do not expect data to travel on the socket, you can \f(CW\*(C`ev_timer_stop\*(C'\fR |
|
|
1775 | the timer, and \f(CW\*(C`ev_timer_again\*(C'\fR will automatically restart it if need be. |
|
|
1776 | .Sp |
|
|
1777 | That means you can ignore both the \f(CW\*(C`ev_timer_start\*(C'\fR function and the |
|
|
1778 | \&\f(CW\*(C`after\*(C'\fR argument to \f(CW\*(C`ev_timer_set\*(C'\fR, and only ever use the \f(CW\*(C`repeat\*(C'\fR |
|
|
1779 | member and \f(CW\*(C`ev_timer_again\*(C'\fR. |
|
|
1780 | .Sp |
|
|
1781 | At start: |
|
|
1782 | .Sp |
|
|
1783 | .Vb 3 |
|
|
1784 | \& ev_init (timer, callback); |
|
|
1785 | \& timer\->repeat = 60.; |
|
|
1786 | \& ev_timer_again (loop, timer); |
|
|
1787 | .Ve |
|
|
1788 | .Sp |
|
|
1789 | Each time there is some activity: |
|
|
1790 | .Sp |
|
|
1791 | .Vb 1 |
|
|
1792 | \& ev_timer_again (loop, timer); |
|
|
1793 | .Ve |
|
|
1794 | .Sp |
|
|
1795 | It is even possible to change the time-out on the fly, regardless of |
|
|
1796 | whether the watcher is active or not: |
|
|
1797 | .Sp |
|
|
1798 | .Vb 2 |
|
|
1799 | \& timer\->repeat = 30.; |
|
|
1800 | \& ev_timer_again (loop, timer); |
|
|
1801 | .Ve |
|
|
1802 | .Sp |
|
|
1803 | This is slightly more efficient then stopping/starting the timer each time |
|
|
1804 | you want to modify its timeout value, as libev does not have to completely |
|
|
1805 | remove and re-insert the timer from/into its internal data structure. |
|
|
1806 | .Sp |
|
|
1807 | It is, however, even simpler than the \*(L"obvious\*(R" way to do it. |
|
|
1808 | .IP "3. Let the timer time out, but then re-arm it as required." 4 |
|
|
1809 | .IX Item "3. Let the timer time out, but then re-arm it as required." |
|
|
1810 | This method is more tricky, but usually most efficient: Most timeouts are |
|
|
1811 | relatively long compared to the intervals between other activity \- in |
|
|
1812 | our example, within 60 seconds, there are usually many I/O events with |
|
|
1813 | associated activity resets. |
|
|
1814 | .Sp |
|
|
1815 | In this case, it would be more efficient to leave the \f(CW\*(C`ev_timer\*(C'\fR alone, |
|
|
1816 | but remember the time of last activity, and check for a real timeout only |
|
|
1817 | within the callback: |
|
|
1818 | .Sp |
|
|
1819 | .Vb 1 |
|
|
1820 | \& ev_tstamp last_activity; // time of last activity |
|
|
1821 | \& |
|
|
1822 | \& static void |
|
|
1823 | \& callback (EV_P_ ev_timer *w, int revents) |
|
|
1824 | \& { |
|
|
1825 | \& ev_tstamp now = ev_now (EV_A); |
|
|
1826 | \& ev_tstamp timeout = last_activity + 60.; |
|
|
1827 | \& |
|
|
1828 | \& // if last_activity + 60. is older than now, we did time out |
|
|
1829 | \& if (timeout < now) |
|
|
1830 | \& { |
|
|
1831 | \& // timeout occured, take action |
|
|
1832 | \& } |
|
|
1833 | \& else |
|
|
1834 | \& { |
|
|
1835 | \& // callback was invoked, but there was some activity, re\-arm |
|
|
1836 | \& // the watcher to fire in last_activity + 60, which is |
|
|
1837 | \& // guaranteed to be in the future, so "again" is positive: |
|
|
1838 | \& w\->repeat = timeout \- now; |
|
|
1839 | \& ev_timer_again (EV_A_ w); |
|
|
1840 | \& } |
|
|
1841 | \& } |
|
|
1842 | .Ve |
|
|
1843 | .Sp |
|
|
1844 | To summarise the callback: first calculate the real timeout (defined |
|
|
1845 | as \*(L"60 seconds after the last activity\*(R"), then check if that time has |
|
|
1846 | been reached, which means something \fIdid\fR, in fact, time out. Otherwise |
|
|
1847 | the callback was invoked too early (\f(CW\*(C`timeout\*(C'\fR is in the future), so |
|
|
1848 | re-schedule the timer to fire at that future time, to see if maybe we have |
|
|
1849 | a timeout then. |
|
|
1850 | .Sp |
|
|
1851 | Note how \f(CW\*(C`ev_timer_again\*(C'\fR is used, taking advantage of the |
|
|
1852 | \&\f(CW\*(C`ev_timer_again\*(C'\fR optimisation when the timer is already running. |
|
|
1853 | .Sp |
|
|
1854 | This scheme causes more callback invocations (about one every 60 seconds |
|
|
1855 | minus half the average time between activity), but virtually no calls to |
|
|
1856 | libev to change the timeout. |
|
|
1857 | .Sp |
|
|
1858 | To start the timer, simply initialise the watcher and set \f(CW\*(C`last_activity\*(C'\fR |
|
|
1859 | to the current time (meaning we just have some activity :), then call the |
|
|
1860 | callback, which will \*(L"do the right thing\*(R" and start the timer: |
|
|
1861 | .Sp |
|
|
1862 | .Vb 3 |
|
|
1863 | \& ev_init (timer, callback); |
|
|
1864 | \& last_activity = ev_now (loop); |
|
|
1865 | \& callback (loop, timer, EV_TIMEOUT); |
|
|
1866 | .Ve |
|
|
1867 | .Sp |
|
|
1868 | And when there is some activity, simply store the current time in |
|
|
1869 | \&\f(CW\*(C`last_activity\*(C'\fR, no libev calls at all: |
|
|
1870 | .Sp |
|
|
1871 | .Vb 1 |
|
|
1872 | \& last_actiivty = ev_now (loop); |
|
|
1873 | .Ve |
|
|
1874 | .Sp |
|
|
1875 | This technique is slightly more complex, but in most cases where the |
|
|
1876 | time-out is unlikely to be triggered, much more efficient. |
|
|
1877 | .Sp |
|
|
1878 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
|
|
1879 | callback :) \- just change the timeout and invoke the callback, which will |
|
|
1880 | fix things for you. |
|
|
1881 | .IP "4. Wee, just use a double-linked list for your timeouts." 4 |
|
|
1882 | .IX Item "4. Wee, just use a double-linked list for your timeouts." |
|
|
1883 | If there is not one request, but many thousands (millions...), all |
|
|
1884 | employing some kind of timeout with the same timeout value, then one can |
|
|
1885 | do even better: |
|
|
1886 | .Sp |
|
|
1887 | When starting the timeout, calculate the timeout value and put the timeout |
|
|
1888 | at the \fIend\fR of the list. |
|
|
1889 | .Sp |
|
|
1890 | Then use an \f(CW\*(C`ev_timer\*(C'\fR to fire when the timeout at the \fIbeginning\fR of |
|
|
1891 | the list is expected to fire (for example, using the technique #3). |
|
|
1892 | .Sp |
|
|
1893 | When there is some activity, remove the timer from the list, recalculate |
|
|
1894 | the timeout, append it to the end of the list again, and make sure to |
|
|
1895 | update the \f(CW\*(C`ev_timer\*(C'\fR if it was taken from the beginning of the list. |
|
|
1896 | .Sp |
|
|
1897 | This way, one can manage an unlimited number of timeouts in O(1) time for |
|
|
1898 | starting, stopping and updating the timers, at the expense of a major |
|
|
1899 | complication, and having to use a constant timeout. The constant timeout |
|
|
1900 | ensures that the list stays sorted. |
|
|
1901 | .PP |
|
|
1902 | So which method the best? |
|
|
1903 | .PP |
|
|
1904 | Method #2 is a simple no-brain-required solution that is adequate in most |
|
|
1905 | situations. Method #3 requires a bit more thinking, but handles many cases |
|
|
1906 | better, and isn't very complicated either. In most case, choosing either |
|
|
1907 | one is fine, with #3 being better in typical situations. |
|
|
1908 | .PP |
|
|
1909 | Method #1 is almost always a bad idea, and buys you nothing. Method #4 is |
|
|
1910 | rather complicated, but extremely efficient, something that really pays |
|
|
1911 | off after the first million or so of active timers, i.e. it's usually |
|
|
1912 | overkill :) |
1420 | .PP |
1913 | .PP |
1421 | \fIThe special problem of time updates\fR |
1914 | \fIThe special problem of time updates\fR |
1422 | .IX Subsection "The special problem of time updates" |
1915 | .IX Subsection "The special problem of time updates" |
1423 | .PP |
1916 | .PP |
1424 | Establishing the current time is a costly operation (it usually takes at |
1917 | Establishing the current time is a costly operation (it usually takes at |
… | |
… | |
1438 | .Ve |
1931 | .Ve |
1439 | .PP |
1932 | .PP |
1440 | If the event loop is suspended for a long time, you can also force an |
1933 | If the event loop is suspended for a long time, you can also force an |
1441 | update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update |
1934 | update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update |
1442 | ()\*(C'\fR. |
1935 | ()\*(C'\fR. |
|
|
1936 | .PP |
|
|
1937 | \fIThe special problems of suspended animation\fR |
|
|
1938 | .IX Subsection "The special problems of suspended animation" |
|
|
1939 | .PP |
|
|
1940 | When you leave the server world it is quite customary to hit machines that |
|
|
1941 | can suspend/hibernate \- what happens to the clocks during such a suspend? |
|
|
1942 | .PP |
|
|
1943 | Some quick tests made with a Linux 2.6.28 indicate that a suspend freezes |
|
|
1944 | all processes, while the clocks (\f(CW\*(C`times\*(C'\fR, \f(CW\*(C`CLOCK_MONOTONIC\*(C'\fR) continue |
|
|
1945 | to run until the system is suspended, but they will not advance while the |
|
|
1946 | system is suspended. That means, on resume, it will be as if the program |
|
|
1947 | was frozen for a few seconds, but the suspend time will not be counted |
|
|
1948 | towards \f(CW\*(C`ev_timer\*(C'\fR when a monotonic clock source is used. The real time |
|
|
1949 | clock advanced as expected, but if it is used as sole clocksource, then a |
|
|
1950 | long suspend would be detected as a time jump by libev, and timers would |
|
|
1951 | be adjusted accordingly. |
|
|
1952 | .PP |
|
|
1953 | I would not be surprised to see different behaviour in different between |
|
|
1954 | operating systems, \s-1OS\s0 versions or even different hardware. |
|
|
1955 | .PP |
|
|
1956 | The other form of suspend (job control, or sending a \s-1SIGSTOP\s0) will see a |
|
|
1957 | time jump in the monotonic clocks and the realtime clock. If the program |
|
|
1958 | is suspended for a very long time, and monotonic clock sources are in use, |
|
|
1959 | then you can expect \f(CW\*(C`ev_timer\*(C'\fRs to expire as the full suspension time |
|
|
1960 | will be counted towards the timers. When no monotonic clock source is in |
|
|
1961 | use, then libev will again assume a timejump and adjust accordingly. |
|
|
1962 | .PP |
|
|
1963 | It might be beneficial for this latter case to call \f(CW\*(C`ev_suspend\*(C'\fR |
|
|
1964 | and \f(CW\*(C`ev_resume\*(C'\fR in code that handles \f(CW\*(C`SIGTSTP\*(C'\fR, to at least get |
|
|
1965 | deterministic behaviour in this case (you can do nothing against |
|
|
1966 | \&\f(CW\*(C`SIGSTOP\*(C'\fR). |
1443 | .PP |
1967 | .PP |
1444 | \fIWatcher-Specific Functions and Data Members\fR |
1968 | \fIWatcher-Specific Functions and Data Members\fR |
1445 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1969 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1446 | .IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 |
1970 | .IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 |
1447 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
1971 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
… | |
… | |
1470 | If the timer is started but non-repeating, stop it (as if it timed out). |
1994 | If the timer is started but non-repeating, stop it (as if it timed out). |
1471 | .Sp |
1995 | .Sp |
1472 | If the timer is repeating, either start it if necessary (with the |
1996 | If the timer is repeating, either start it if necessary (with the |
1473 | \&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value. |
1997 | \&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value. |
1474 | .Sp |
1998 | .Sp |
1475 | This sounds a bit complicated, but here is a useful and typical |
1999 | This sounds a bit complicated, see \*(L"Be smart about timeouts\*(R", above, for a |
1476 | example: Imagine you have a \s-1TCP\s0 connection and you want a so-called idle |
2000 | usage example. |
1477 | timeout, that is, you want to be called when there have been, say, 60 |
2001 | .IP "ev_tstamp ev_timer_remaining (loop, ev_timer *)" 4 |
1478 | seconds of inactivity on the socket. The easiest way to do this is to |
2002 | .IX Item "ev_tstamp ev_timer_remaining (loop, ev_timer *)" |
1479 | configure an \f(CW\*(C`ev_timer\*(C'\fR with a \f(CW\*(C`repeat\*(C'\fR value of \f(CW60\fR and then call |
2003 | Returns the remaining time until a timer fires. If the timer is active, |
1480 | \&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If |
2004 | then this time is relative to the current event loop time, otherwise it's |
1481 | you go into an idle state where you do not expect data to travel on the |
2005 | the timeout value currently configured. |
1482 | socket, you can \f(CW\*(C`ev_timer_stop\*(C'\fR the timer, and \f(CW\*(C`ev_timer_again\*(C'\fR will |
|
|
1483 | automatically restart it if need be. |
|
|
1484 | .Sp |
2006 | .Sp |
1485 | That means you can ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR |
2007 | That is, after an \f(CW\*(C`ev_timer_set (w, 5, 7)\*(C'\fR, \f(CW\*(C`ev_timer_remaining\*(C'\fR returns |
1486 | altogether and only ever use the \f(CW\*(C`repeat\*(C'\fR value and \f(CW\*(C`ev_timer_again\*(C'\fR: |
2008 | \&\f(CW5\fR. When the timer is started and one second passes, \f(CW\*(C`ev_timer_remain\*(C'\fR |
1487 | .Sp |
2009 | will return \f(CW4\fR. When the timer expires and is restarted, it will return |
1488 | .Vb 8 |
2010 | roughly \f(CW7\fR (likely slightly less as callback invocation takes some time, |
1489 | \& ev_timer_init (timer, callback, 0., 5.); |
2011 | too), and so on. |
1490 | \& ev_timer_again (loop, timer); |
|
|
1491 | \& ... |
|
|
1492 | \& timer\->again = 17.; |
|
|
1493 | \& ev_timer_again (loop, timer); |
|
|
1494 | \& ... |
|
|
1495 | \& timer\->again = 10.; |
|
|
1496 | \& ev_timer_again (loop, timer); |
|
|
1497 | .Ve |
|
|
1498 | .Sp |
|
|
1499 | This is more slightly efficient then stopping/starting the timer each time |
|
|
1500 | you want to modify its timeout value. |
|
|
1501 | .Sp |
|
|
1502 | Note, however, that it is often even more efficient to remember the |
|
|
1503 | time of the last activity and let the timer time-out naturally. In the |
|
|
1504 | callback, you then check whether the time-out is real, or, if there was |
|
|
1505 | some activity, you reschedule the watcher to time-out in \*(L"last_activity + |
|
|
1506 | timeout \- ev_now ()\*(R" seconds. |
|
|
1507 | .IP "ev_tstamp repeat [read\-write]" 4 |
2012 | .IP "ev_tstamp repeat [read\-write]" 4 |
1508 | .IX Item "ev_tstamp repeat [read-write]" |
2013 | .IX Item "ev_tstamp repeat [read-write]" |
1509 | The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out |
2014 | The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out |
1510 | or \f(CW\*(C`ev_timer_again\*(C'\fR is called, and determines the next timeout (if any), |
2015 | or \f(CW\*(C`ev_timer_again\*(C'\fR is called, and determines the next timeout (if any), |
1511 | which is also when any modifications are taken into account. |
2016 | which is also when any modifications are taken into account. |
… | |
… | |
1515 | .PP |
2020 | .PP |
1516 | Example: Create a timer that fires after 60 seconds. |
2021 | Example: Create a timer that fires after 60 seconds. |
1517 | .PP |
2022 | .PP |
1518 | .Vb 5 |
2023 | .Vb 5 |
1519 | \& static void |
2024 | \& static void |
1520 | \& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
2025 | \& one_minute_cb (struct ev_loop *loop, ev_timer *w, int revents) |
1521 | \& { |
2026 | \& { |
1522 | \& .. one minute over, w is actually stopped right here |
2027 | \& .. one minute over, w is actually stopped right here |
1523 | \& } |
2028 | \& } |
1524 | \& |
2029 | \& |
1525 | \& struct ev_timer mytimer; |
2030 | \& ev_timer mytimer; |
1526 | \& ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
2031 | \& ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1527 | \& ev_timer_start (loop, &mytimer); |
2032 | \& ev_timer_start (loop, &mytimer); |
1528 | .Ve |
2033 | .Ve |
1529 | .PP |
2034 | .PP |
1530 | Example: Create a timeout timer that times out after 10 seconds of |
2035 | Example: Create a timeout timer that times out after 10 seconds of |
1531 | inactivity. |
2036 | inactivity. |
1532 | .PP |
2037 | .PP |
1533 | .Vb 5 |
2038 | .Vb 5 |
1534 | \& static void |
2039 | \& static void |
1535 | \& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
2040 | \& timeout_cb (struct ev_loop *loop, ev_timer *w, int revents) |
1536 | \& { |
2041 | \& { |
1537 | \& .. ten seconds without any activity |
2042 | \& .. ten seconds without any activity |
1538 | \& } |
2043 | \& } |
1539 | \& |
2044 | \& |
1540 | \& struct ev_timer mytimer; |
2045 | \& ev_timer mytimer; |
1541 | \& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
2046 | \& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1542 | \& ev_timer_again (&mytimer); /* start timer */ |
2047 | \& ev_timer_again (&mytimer); /* start timer */ |
1543 | \& ev_loop (loop, 0); |
2048 | \& ev_loop (loop, 0); |
1544 | \& |
2049 | \& |
1545 | \& // and in some piece of code that gets executed on any "activity": |
2050 | \& // and in some piece of code that gets executed on any "activity": |
1546 | \& // reset the timeout to start ticking again at 10 seconds |
2051 | \& // reset the timeout to start ticking again at 10 seconds |
1547 | \& ev_timer_again (&mytimer); |
2052 | \& ev_timer_again (&mytimer); |
1548 | .Ve |
2053 | .Ve |
1549 | .ie n .Sh """ev_periodic"" \- to cron or not to cron?" |
2054 | .ie n .SS """ev_periodic"" \- to cron or not to cron?" |
1550 | .el .Sh "\f(CWev_periodic\fP \- to cron or not to cron?" |
2055 | .el .SS "\f(CWev_periodic\fP \- to cron or not to cron?" |
1551 | .IX Subsection "ev_periodic - to cron or not to cron?" |
2056 | .IX Subsection "ev_periodic - to cron or not to cron?" |
1552 | Periodic watchers are also timers of a kind, but they are very versatile |
2057 | Periodic watchers are also timers of a kind, but they are very versatile |
1553 | (and unfortunately a bit complex). |
2058 | (and unfortunately a bit complex). |
1554 | .PP |
2059 | .PP |
1555 | Unlike \f(CW\*(C`ev_timer\*(C'\fR's, they are not based on real time (or relative time) |
2060 | Unlike \f(CW\*(C`ev_timer\*(C'\fR, periodic watchers are not based on real time (or |
1556 | but on wall clock time (absolute time). You can tell a periodic watcher |
2061 | relative time, the physical time that passes) but on wall clock time |
1557 | to trigger after some specific point in time. For example, if you tell a |
2062 | (absolute time, the thing you can read on your calender or clock). The |
1558 | periodic watcher to trigger in 10 seconds (by specifying e.g. \f(CW\*(C`ev_now () |
2063 | difference is that wall clock time can run faster or slower than real |
1559 | + 10.\*(C'\fR, that is, an absolute time not a delay) and then reset your system |
2064 | time, and time jumps are not uncommon (e.g. when you adjust your |
1560 | clock to January of the previous year, then it will take more than year |
2065 | wrist-watch). |
1561 | to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would still trigger |
|
|
1562 | roughly 10 seconds later as it uses a relative timeout). |
|
|
1563 | .PP |
2066 | .PP |
|
|
2067 | You can tell a periodic watcher to trigger after some specific point |
|
|
2068 | in time: for example, if you tell a periodic watcher to trigger \*(L"in 10 |
|
|
2069 | seconds\*(R" (by specifying e.g. \f(CW\*(C`ev_now () + 10.\*(C'\fR, that is, an absolute time |
|
|
2070 | not a delay) and then reset your system clock to January of the previous |
|
|
2071 | year, then it will take a year or more to trigger the event (unlike an |
|
|
2072 | \&\f(CW\*(C`ev_timer\*(C'\fR, which would still trigger roughly 10 seconds after starting |
|
|
2073 | it, as it uses a relative timeout). |
|
|
2074 | .PP |
1564 | \&\f(CW\*(C`ev_periodic\*(C'\fRs can also be used to implement vastly more complex timers, |
2075 | \&\f(CW\*(C`ev_periodic\*(C'\fR watchers can also be used to implement vastly more complex |
1565 | such as triggering an event on each \*(L"midnight, local time\*(R", or other |
2076 | timers, such as triggering an event on each \*(L"midnight, local time\*(R", or |
1566 | complicated rules. |
2077 | other complicated rules. This cannot be done with \f(CW\*(C`ev_timer\*(C'\fR watchers, as |
|
|
2078 | those cannot react to time jumps. |
1567 | .PP |
2079 | .PP |
1568 | As with timers, the callback is guaranteed to be invoked only when the |
2080 | As with timers, the callback is guaranteed to be invoked only when the |
1569 | time (\f(CW\*(C`at\*(C'\fR) has passed, but if multiple periodic timers become ready |
2081 | point in time where it is supposed to trigger has passed. If multiple |
1570 | during the same loop iteration, then order of execution is undefined. |
2082 | timers become ready during the same loop iteration then the ones with |
|
|
2083 | earlier time-out values are invoked before ones with later time-out values |
|
|
2084 | (but this is no longer true when a callback calls \f(CW\*(C`ev_loop\*(C'\fR recursively). |
1571 | .PP |
2085 | .PP |
1572 | \fIWatcher-Specific Functions and Data Members\fR |
2086 | \fIWatcher-Specific Functions and Data Members\fR |
1573 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2087 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1574 | .IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4 |
2088 | .IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" 4 |
1575 | .IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" |
2089 | .IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" |
1576 | .PD 0 |
2090 | .PD 0 |
1577 | .IP "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 4 |
2091 | .IP "ev_periodic_set (ev_periodic *, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" 4 |
1578 | .IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" |
2092 | .IX Item "ev_periodic_set (ev_periodic *, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" |
1579 | .PD |
2093 | .PD |
1580 | Lots of arguments, lets sort it out... There are basically three modes of |
2094 | Lots of arguments, let's sort it out... There are basically three modes of |
1581 | operation, and we will explain them from simplest to most complex: |
2095 | operation, and we will explain them from simplest to most complex: |
1582 | .RS 4 |
2096 | .RS 4 |
1583 | .IP "\(bu" 4 |
2097 | .IP "\(bu" 4 |
1584 | absolute timer (at = time, interval = reschedule_cb = 0) |
2098 | absolute timer (offset = absolute time, interval = 0, reschedule_cb = 0) |
1585 | .Sp |
2099 | .Sp |
1586 | In this configuration the watcher triggers an event after the wall clock |
2100 | In this configuration the watcher triggers an event after the wall clock |
1587 | time \f(CW\*(C`at\*(C'\fR has passed. It will not repeat and will not adjust when a time |
2101 | time \f(CW\*(C`offset\*(C'\fR has passed. It will not repeat and will not adjust when a |
1588 | jump occurs, that is, if it is to be run at January 1st 2011 then it will |
2102 | time jump occurs, that is, if it is to be run at January 1st 2011 then it |
1589 | only run when the system clock reaches or surpasses this time. |
2103 | will be stopped and invoked when the system clock reaches or surpasses |
|
|
2104 | this point in time. |
1590 | .IP "\(bu" 4 |
2105 | .IP "\(bu" 4 |
1591 | repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
2106 | repeating interval timer (offset = offset within interval, interval > 0, reschedule_cb = 0) |
1592 | .Sp |
2107 | .Sp |
1593 | In this mode the watcher will always be scheduled to time out at the next |
2108 | In this mode the watcher will always be scheduled to time out at the next |
1594 | \&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N, which can also be negative) |
2109 | \&\f(CW\*(C`offset + N * interval\*(C'\fR time (for some integer N, which can also be |
1595 | and then repeat, regardless of any time jumps. |
2110 | negative) and then repeat, regardless of any time jumps. The \f(CW\*(C`offset\*(C'\fR |
|
|
2111 | argument is merely an offset into the \f(CW\*(C`interval\*(C'\fR periods. |
1596 | .Sp |
2112 | .Sp |
1597 | This can be used to create timers that do not drift with respect to the |
2113 | This can be used to create timers that do not drift with respect to the |
1598 | system clock, for example, here is a \f(CW\*(C`ev_periodic\*(C'\fR that triggers each |
2114 | system clock, for example, here is an \f(CW\*(C`ev_periodic\*(C'\fR that triggers each |
1599 | hour, on the hour: |
2115 | hour, on the hour (with respect to \s-1UTC\s0): |
1600 | .Sp |
2116 | .Sp |
1601 | .Vb 1 |
2117 | .Vb 1 |
1602 | \& ev_periodic_set (&periodic, 0., 3600., 0); |
2118 | \& ev_periodic_set (&periodic, 0., 3600., 0); |
1603 | .Ve |
2119 | .Ve |
1604 | .Sp |
2120 | .Sp |
… | |
… | |
1607 | full hour (\s-1UTC\s0), or more correctly, when the system time is evenly divisible |
2123 | full hour (\s-1UTC\s0), or more correctly, when the system time is evenly divisible |
1608 | by 3600. |
2124 | by 3600. |
1609 | .Sp |
2125 | .Sp |
1610 | Another way to think about it (for the mathematically inclined) is that |
2126 | Another way to think about it (for the mathematically inclined) is that |
1611 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
2127 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
1612 | time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps. |
2128 | time where \f(CW\*(C`time = offset (mod interval)\*(C'\fR, regardless of any time jumps. |
1613 | .Sp |
2129 | .Sp |
1614 | For numerical stability it is preferable that the \f(CW\*(C`at\*(C'\fR value is near |
2130 | For numerical stability it is preferable that the \f(CW\*(C`offset\*(C'\fR value is near |
1615 | \&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for |
2131 | \&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for |
1616 | this value, and in fact is often specified as zero. |
2132 | this value, and in fact is often specified as zero. |
1617 | .Sp |
2133 | .Sp |
1618 | Note also that there is an upper limit to how often a timer can fire (\s-1CPU\s0 |
2134 | Note also that there is an upper limit to how often a timer can fire (\s-1CPU\s0 |
1619 | speed for example), so if \f(CW\*(C`interval\*(C'\fR is very small then timing stability |
2135 | speed for example), so if \f(CW\*(C`interval\*(C'\fR is very small then timing stability |
1620 | will of course deteriorate. Libev itself tries to be exact to be about one |
2136 | will of course deteriorate. Libev itself tries to be exact to be about one |
1621 | millisecond (if the \s-1OS\s0 supports it and the machine is fast enough). |
2137 | millisecond (if the \s-1OS\s0 supports it and the machine is fast enough). |
1622 | .IP "\(bu" 4 |
2138 | .IP "\(bu" 4 |
1623 | manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
2139 | manual reschedule mode (offset ignored, interval ignored, reschedule_cb = callback) |
1624 | .Sp |
2140 | .Sp |
1625 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being |
2141 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`offset\*(C'\fR are both being |
1626 | ignored. Instead, each time the periodic watcher gets scheduled, the |
2142 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1627 | reschedule callback will be called with the watcher as first, and the |
2143 | reschedule callback will be called with the watcher as first, and the |
1628 | current time as second argument. |
2144 | current time as second argument. |
1629 | .Sp |
2145 | .Sp |
1630 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, |
2146 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, ever, |
1631 | ever, or make \s-1ANY\s0 event loop modifications whatsoever\fR. |
2147 | or make \s-1ANY\s0 other event loop modifications whatsoever, unless explicitly |
|
|
2148 | allowed by documentation here\fR. |
1632 | .Sp |
2149 | .Sp |
1633 | If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop |
2150 | If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop |
1634 | it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the |
2151 | it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the |
1635 | only event loop modification you are allowed to do). |
2152 | only event loop modification you are allowed to do). |
1636 | .Sp |
2153 | .Sp |
1637 | The callback prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic |
2154 | The callback prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(ev_periodic |
1638 | *w, ev_tstamp now)\*(C'\fR, e.g.: |
2155 | *w, ev_tstamp now)\*(C'\fR, e.g.: |
1639 | .Sp |
2156 | .Sp |
1640 | .Vb 4 |
2157 | .Vb 5 |
|
|
2158 | \& static ev_tstamp |
1641 | \& static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
2159 | \& my_rescheduler (ev_periodic *w, ev_tstamp now) |
1642 | \& { |
2160 | \& { |
1643 | \& return now + 60.; |
2161 | \& return now + 60.; |
1644 | \& } |
2162 | \& } |
1645 | .Ve |
2163 | .Ve |
1646 | .Sp |
2164 | .Sp |
… | |
… | |
1666 | when you changed some parameters or the reschedule callback would return |
2184 | when you changed some parameters or the reschedule callback would return |
1667 | a different time than the last time it was called (e.g. in a crond like |
2185 | a different time than the last time it was called (e.g. in a crond like |
1668 | program when the crontabs have changed). |
2186 | program when the crontabs have changed). |
1669 | .IP "ev_tstamp ev_periodic_at (ev_periodic *)" 4 |
2187 | .IP "ev_tstamp ev_periodic_at (ev_periodic *)" 4 |
1670 | .IX Item "ev_tstamp ev_periodic_at (ev_periodic *)" |
2188 | .IX Item "ev_tstamp ev_periodic_at (ev_periodic *)" |
1671 | When active, returns the absolute time that the watcher is supposed to |
2189 | When active, returns the absolute time that the watcher is supposed |
1672 | trigger next. |
2190 | to trigger next. This is not the same as the \f(CW\*(C`offset\*(C'\fR argument to |
|
|
2191 | \&\f(CW\*(C`ev_periodic_set\*(C'\fR, but indeed works even in interval and manual |
|
|
2192 | rescheduling modes. |
1673 | .IP "ev_tstamp offset [read\-write]" 4 |
2193 | .IP "ev_tstamp offset [read\-write]" 4 |
1674 | .IX Item "ev_tstamp offset [read-write]" |
2194 | .IX Item "ev_tstamp offset [read-write]" |
1675 | When repeating, this contains the offset value, otherwise this is the |
2195 | When repeating, this contains the offset value, otherwise this is the |
1676 | absolute point in time (the \f(CW\*(C`at\*(C'\fR value passed to \f(CW\*(C`ev_periodic_set\*(C'\fR). |
2196 | absolute point in time (the \f(CW\*(C`offset\*(C'\fR value passed to \f(CW\*(C`ev_periodic_set\*(C'\fR, |
|
|
2197 | although libev might modify this value for better numerical stability). |
1677 | .Sp |
2198 | .Sp |
1678 | Can be modified any time, but changes only take effect when the periodic |
2199 | Can be modified any time, but changes only take effect when the periodic |
1679 | timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
2200 | timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
1680 | .IP "ev_tstamp interval [read\-write]" 4 |
2201 | .IP "ev_tstamp interval [read\-write]" 4 |
1681 | .IX Item "ev_tstamp interval [read-write]" |
2202 | .IX Item "ev_tstamp interval [read-write]" |
1682 | The current interval value. Can be modified any time, but changes only |
2203 | The current interval value. Can be modified any time, but changes only |
1683 | take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being |
2204 | take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being |
1684 | called. |
2205 | called. |
1685 | .IP "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read\-write]" 4 |
2206 | .IP "ev_tstamp (*reschedule_cb)(ev_periodic *w, ev_tstamp now) [read\-write]" 4 |
1686 | .IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]" |
2207 | .IX Item "ev_tstamp (*reschedule_cb)(ev_periodic *w, ev_tstamp now) [read-write]" |
1687 | The current reschedule callback, or \f(CW0\fR, if this functionality is |
2208 | The current reschedule callback, or \f(CW0\fR, if this functionality is |
1688 | switched off. Can be changed any time, but changes only take effect when |
2209 | switched off. Can be changed any time, but changes only take effect when |
1689 | the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
2210 | the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
1690 | .PP |
2211 | .PP |
1691 | \fIExamples\fR |
2212 | \fIExamples\fR |
… | |
… | |
1695 | system time is divisible by 3600. The callback invocation times have |
2216 | system time is divisible by 3600. The callback invocation times have |
1696 | potentially a lot of jitter, but good long-term stability. |
2217 | potentially a lot of jitter, but good long-term stability. |
1697 | .PP |
2218 | .PP |
1698 | .Vb 5 |
2219 | .Vb 5 |
1699 | \& static void |
2220 | \& static void |
1700 | \& clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
2221 | \& clock_cb (struct ev_loop *loop, ev_io *w, int revents) |
1701 | \& { |
2222 | \& { |
1702 | \& ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2223 | \& ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1703 | \& } |
2224 | \& } |
1704 | \& |
2225 | \& |
1705 | \& struct ev_periodic hourly_tick; |
2226 | \& ev_periodic hourly_tick; |
1706 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
2227 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1707 | \& ev_periodic_start (loop, &hourly_tick); |
2228 | \& ev_periodic_start (loop, &hourly_tick); |
1708 | .Ve |
2229 | .Ve |
1709 | .PP |
2230 | .PP |
1710 | Example: The same as above, but use a reschedule callback to do it: |
2231 | Example: The same as above, but use a reschedule callback to do it: |
1711 | .PP |
2232 | .PP |
1712 | .Vb 1 |
2233 | .Vb 1 |
1713 | \& #include <math.h> |
2234 | \& #include <math.h> |
1714 | \& |
2235 | \& |
1715 | \& static ev_tstamp |
2236 | \& static ev_tstamp |
1716 | \& my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
2237 | \& my_scheduler_cb (ev_periodic *w, ev_tstamp now) |
1717 | \& { |
2238 | \& { |
1718 | \& return now + (3600. \- fmod (now, 3600.)); |
2239 | \& return now + (3600. \- fmod (now, 3600.)); |
1719 | \& } |
2240 | \& } |
1720 | \& |
2241 | \& |
1721 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
2242 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1722 | .Ve |
2243 | .Ve |
1723 | .PP |
2244 | .PP |
1724 | Example: Call a callback every hour, starting now: |
2245 | Example: Call a callback every hour, starting now: |
1725 | .PP |
2246 | .PP |
1726 | .Vb 4 |
2247 | .Vb 4 |
1727 | \& struct ev_periodic hourly_tick; |
2248 | \& ev_periodic hourly_tick; |
1728 | \& ev_periodic_init (&hourly_tick, clock_cb, |
2249 | \& ev_periodic_init (&hourly_tick, clock_cb, |
1729 | \& fmod (ev_now (loop), 3600.), 3600., 0); |
2250 | \& fmod (ev_now (loop), 3600.), 3600., 0); |
1730 | \& ev_periodic_start (loop, &hourly_tick); |
2251 | \& ev_periodic_start (loop, &hourly_tick); |
1731 | .Ve |
2252 | .Ve |
1732 | .ie n .Sh """ev_signal"" \- signal me when a signal gets signalled!" |
2253 | .ie n .SS """ev_signal"" \- signal me when a signal gets signalled!" |
1733 | .el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled!" |
2254 | .el .SS "\f(CWev_signal\fP \- signal me when a signal gets signalled!" |
1734 | .IX Subsection "ev_signal - signal me when a signal gets signalled!" |
2255 | .IX Subsection "ev_signal - signal me when a signal gets signalled!" |
1735 | Signal watchers will trigger an event when the process receives a specific |
2256 | Signal watchers will trigger an event when the process receives a specific |
1736 | signal one or more times. Even though signals are very asynchronous, libev |
2257 | signal one or more times. Even though signals are very asynchronous, libev |
1737 | will try it's best to deliver signals synchronously, i.e. as part of the |
2258 | will try it's best to deliver signals synchronously, i.e. as part of the |
1738 | normal event processing, like any other event. |
2259 | normal event processing, like any other event. |
1739 | .PP |
2260 | .PP |
1740 | If you want signals asynchronously, just use \f(CW\*(C`sigaction\*(C'\fR as you would |
2261 | If you want signals to be delivered truly asynchronously, just use |
1741 | do without libev and forget about sharing the signal. You can even use |
2262 | \&\f(CW\*(C`sigaction\*(C'\fR as you would do without libev and forget about sharing |
1742 | \&\f(CW\*(C`ev_async\*(C'\fR from a signal handler to synchronously wake up an event loop. |
2263 | the signal. You can even use \f(CW\*(C`ev_async\*(C'\fR from a signal handler to |
|
|
2264 | synchronously wake up an event loop. |
1743 | .PP |
2265 | .PP |
1744 | You can configure as many watchers as you like per signal. Only when the |
2266 | You can configure as many watchers as you like for the same signal, but |
|
|
2267 | only within the same loop, i.e. you can watch for \f(CW\*(C`SIGINT\*(C'\fR in your |
|
|
2268 | default loop and for \f(CW\*(C`SIGIO\*(C'\fR in another loop, but you cannot watch for |
|
|
2269 | \&\f(CW\*(C`SIGINT\*(C'\fR in both the default loop and another loop at the same time. At |
|
|
2270 | the moment, \f(CW\*(C`SIGCHLD\*(C'\fR is permanently tied to the default loop. |
|
|
2271 | .PP |
1745 | first watcher gets started will libev actually register a signal handler |
2272 | When the first watcher gets started will libev actually register something |
1746 | with the kernel (thus it coexists with your own signal handlers as long as |
2273 | with the kernel (thus it coexists with your own signal handlers as long as |
1747 | you don't register any with libev for the same signal). Similarly, when |
2274 | you don't register any with libev for the same signal). |
1748 | the last signal watcher for a signal is stopped, libev will reset the |
|
|
1749 | signal handler to \s-1SIG_DFL\s0 (regardless of what it was set to before). |
|
|
1750 | .PP |
2275 | .PP |
1751 | If possible and supported, libev will install its handlers with |
2276 | If possible and supported, libev will install its handlers with |
1752 | \&\f(CW\*(C`SA_RESTART\*(C'\fR behaviour enabled, so system calls should not be unduly |
2277 | \&\f(CW\*(C`SA_RESTART\*(C'\fR (or equivalent) behaviour enabled, so system calls should |
1753 | interrupted. If you have a problem with system calls getting interrupted by |
2278 | not be unduly interrupted. If you have a problem with system calls getting |
1754 | signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher and unblock |
2279 | interrupted by signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher |
1755 | them in an \f(CW\*(C`ev_prepare\*(C'\fR watcher. |
2280 | and unblock them in an \f(CW\*(C`ev_prepare\*(C'\fR watcher. |
|
|
2281 | .PP |
|
|
2282 | \fIThe special problem of inheritance over fork/execve/pthread_create\fR |
|
|
2283 | .IX Subsection "The special problem of inheritance over fork/execve/pthread_create" |
|
|
2284 | .PP |
|
|
2285 | Both the signal mask (\f(CW\*(C`sigprocmask\*(C'\fR) and the signal disposition |
|
|
2286 | (\f(CW\*(C`sigaction\*(C'\fR) are unspecified after starting a signal watcher (and after |
|
|
2287 | stopping it again), that is, libev might or might not block the signal, |
|
|
2288 | and might or might not set or restore the installed signal handler. |
|
|
2289 | .PP |
|
|
2290 | While this does not matter for the signal disposition (libev never |
|
|
2291 | sets signals to \f(CW\*(C`SIG_IGN\*(C'\fR, so handlers will be reset to \f(CW\*(C`SIG_DFL\*(C'\fR on |
|
|
2292 | \&\f(CW\*(C`execve\*(C'\fR), this matters for the signal mask: many programs do not expect |
|
|
2293 | certain signals to be blocked. |
|
|
2294 | .PP |
|
|
2295 | This means that before calling \f(CW\*(C`exec\*(C'\fR (from the child) you should reset |
|
|
2296 | the signal mask to whatever \*(L"default\*(R" you expect (all clear is a good |
|
|
2297 | choice usually). |
|
|
2298 | .PP |
|
|
2299 | The simplest way to ensure that the signal mask is reset in the child is |
|
|
2300 | to install a fork handler with \f(CW\*(C`pthread_atfork\*(C'\fR that resets it. That will |
|
|
2301 | catch fork calls done by libraries (such as the libc) as well. |
|
|
2302 | .PP |
|
|
2303 | In current versions of libev, the signal will not be blocked indefinitely |
|
|
2304 | unless you use the \f(CW\*(C`signalfd\*(C'\fR \s-1API\s0 (\f(CW\*(C`EV_SIGNALFD\*(C'\fR). While this reduces |
|
|
2305 | the window of opportunity for problems, it will not go away, as libev |
|
|
2306 | \&\fIhas\fR to modify the signal mask, at least temporarily. |
|
|
2307 | .PP |
|
|
2308 | So I can't stress this enough: \fIIf you do not reset your signal mask when |
|
|
2309 | you expect it to be empty, you have a race condition in your code\fR. This |
|
|
2310 | is not a libev-specific thing, this is true for most event libraries. |
1756 | .PP |
2311 | .PP |
1757 | \fIWatcher-Specific Functions and Data Members\fR |
2312 | \fIWatcher-Specific Functions and Data Members\fR |
1758 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2313 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1759 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
2314 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
1760 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
2315 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
… | |
… | |
1773 | .PP |
2328 | .PP |
1774 | Example: Try to exit cleanly on \s-1SIGINT\s0. |
2329 | Example: Try to exit cleanly on \s-1SIGINT\s0. |
1775 | .PP |
2330 | .PP |
1776 | .Vb 5 |
2331 | .Vb 5 |
1777 | \& static void |
2332 | \& static void |
1778 | \& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
2333 | \& sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
1779 | \& { |
2334 | \& { |
1780 | \& ev_unloop (loop, EVUNLOOP_ALL); |
2335 | \& ev_unloop (loop, EVUNLOOP_ALL); |
1781 | \& } |
2336 | \& } |
1782 | \& |
2337 | \& |
1783 | \& struct ev_signal signal_watcher; |
2338 | \& ev_signal signal_watcher; |
1784 | \& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2339 | \& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1785 | \& ev_signal_start (loop, &signal_watcher); |
2340 | \& ev_signal_start (loop, &signal_watcher); |
1786 | .Ve |
2341 | .Ve |
1787 | .ie n .Sh """ev_child"" \- watch out for process status changes" |
2342 | .ie n .SS """ev_child"" \- watch out for process status changes" |
1788 | .el .Sh "\f(CWev_child\fP \- watch out for process status changes" |
2343 | .el .SS "\f(CWev_child\fP \- watch out for process status changes" |
1789 | .IX Subsection "ev_child - watch out for process status changes" |
2344 | .IX Subsection "ev_child - watch out for process status changes" |
1790 | Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to |
2345 | Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to |
1791 | some child status changes (most typically when a child of yours dies or |
2346 | some child status changes (most typically when a child of yours dies or |
1792 | exits). It is permissible to install a child watcher \fIafter\fR the child |
2347 | exits). It is permissible to install a child watcher \fIafter\fR the child |
1793 | has been forked (which implies it might have already exited), as long |
2348 | has been forked (which implies it might have already exited), as long |
1794 | as the event loop isn't entered (or is continued from a watcher), i.e., |
2349 | as the event loop isn't entered (or is continued from a watcher), i.e., |
1795 | forking and then immediately registering a watcher for the child is fine, |
2350 | forking and then immediately registering a watcher for the child is fine, |
1796 | but forking and registering a watcher a few event loop iterations later is |
2351 | but forking and registering a watcher a few event loop iterations later or |
1797 | not. |
2352 | in the next callback invocation is not. |
1798 | .PP |
2353 | .PP |
1799 | Only the default event loop is capable of handling signals, and therefore |
2354 | Only the default event loop is capable of handling signals, and therefore |
1800 | you can only register child watchers in the default event loop. |
2355 | you can only register child watchers in the default event loop. |
1801 | .PP |
2356 | .PP |
|
|
2357 | Due to some design glitches inside libev, child watchers will always be |
|
|
2358 | handled at maximum priority (their priority is set to \f(CW\*(C`EV_MAXPRI\*(C'\fR by |
|
|
2359 | libev) |
|
|
2360 | .PP |
1802 | \fIProcess Interaction\fR |
2361 | \fIProcess Interaction\fR |
1803 | .IX Subsection "Process Interaction" |
2362 | .IX Subsection "Process Interaction" |
1804 | .PP |
2363 | .PP |
1805 | Libev grabs \f(CW\*(C`SIGCHLD\*(C'\fR as soon as the default event loop is |
2364 | Libev grabs \f(CW\*(C`SIGCHLD\*(C'\fR as soon as the default event loop is |
1806 | initialised. This is necessary to guarantee proper behaviour even if |
2365 | initialised. This is necessary to guarantee proper behaviour even if the |
1807 | the first child watcher is started after the child exits. The occurrence |
2366 | first child watcher is started after the child exits. The occurrence |
1808 | of \f(CW\*(C`SIGCHLD\*(C'\fR is recorded asynchronously, but child reaping is done |
2367 | of \f(CW\*(C`SIGCHLD\*(C'\fR is recorded asynchronously, but child reaping is done |
1809 | synchronously as part of the event loop processing. Libev always reaps all |
2368 | synchronously as part of the event loop processing. Libev always reaps all |
1810 | children, even ones not watched. |
2369 | children, even ones not watched. |
1811 | .PP |
2370 | .PP |
1812 | \fIOverriding the Built-In Processing\fR |
2371 | \fIOverriding the Built-In Processing\fR |
… | |
… | |
1824 | .IX Subsection "Stopping the Child Watcher" |
2383 | .IX Subsection "Stopping the Child Watcher" |
1825 | .PP |
2384 | .PP |
1826 | Currently, the child watcher never gets stopped, even when the |
2385 | Currently, the child watcher never gets stopped, even when the |
1827 | child terminates, so normally one needs to stop the watcher in the |
2386 | child terminates, so normally one needs to stop the watcher in the |
1828 | callback. Future versions of libev might stop the watcher automatically |
2387 | callback. Future versions of libev might stop the watcher automatically |
1829 | when a child exit is detected. |
2388 | when a child exit is detected (calling \f(CW\*(C`ev_child_stop\*(C'\fR twice is not a |
|
|
2389 | problem). |
1830 | .PP |
2390 | .PP |
1831 | \fIWatcher-Specific Functions and Data Members\fR |
2391 | \fIWatcher-Specific Functions and Data Members\fR |
1832 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2392 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1833 | .IP "ev_child_init (ev_child *, callback, int pid, int trace)" 4 |
2393 | .IP "ev_child_init (ev_child *, callback, int pid, int trace)" 4 |
1834 | .IX Item "ev_child_init (ev_child *, callback, int pid, int trace)" |
2394 | .IX Item "ev_child_init (ev_child *, callback, int pid, int trace)" |
… | |
… | |
1863 | .PP |
2423 | .PP |
1864 | .Vb 1 |
2424 | .Vb 1 |
1865 | \& ev_child cw; |
2425 | \& ev_child cw; |
1866 | \& |
2426 | \& |
1867 | \& static void |
2427 | \& static void |
1868 | \& child_cb (EV_P_ struct ev_child *w, int revents) |
2428 | \& child_cb (EV_P_ ev_child *w, int revents) |
1869 | \& { |
2429 | \& { |
1870 | \& ev_child_stop (EV_A_ w); |
2430 | \& ev_child_stop (EV_A_ w); |
1871 | \& printf ("process %d exited with status %x\en", w\->rpid, w\->rstatus); |
2431 | \& printf ("process %d exited with status %x\en", w\->rpid, w\->rstatus); |
1872 | \& } |
2432 | \& } |
1873 | \& |
2433 | \& |
… | |
… | |
1884 | \& { |
2444 | \& { |
1885 | \& ev_child_init (&cw, child_cb, pid, 0); |
2445 | \& ev_child_init (&cw, child_cb, pid, 0); |
1886 | \& ev_child_start (EV_DEFAULT_ &cw); |
2446 | \& ev_child_start (EV_DEFAULT_ &cw); |
1887 | \& } |
2447 | \& } |
1888 | .Ve |
2448 | .Ve |
1889 | .ie n .Sh """ev_stat"" \- did the file attributes just change?" |
2449 | .ie n .SS """ev_stat"" \- did the file attributes just change?" |
1890 | .el .Sh "\f(CWev_stat\fP \- did the file attributes just change?" |
2450 | .el .SS "\f(CWev_stat\fP \- did the file attributes just change?" |
1891 | .IX Subsection "ev_stat - did the file attributes just change?" |
2451 | .IX Subsection "ev_stat - did the file attributes just change?" |
1892 | This watches a file system path for attribute changes. That is, it calls |
2452 | This watches a file system path for attribute changes. That is, it calls |
1893 | \&\f(CW\*(C`stat\*(C'\fR regularly (or when the \s-1OS\s0 says it changed) and sees if it changed |
2453 | \&\f(CW\*(C`stat\*(C'\fR on that path in regular intervals (or when the \s-1OS\s0 says it changed) |
1894 | compared to the last time, invoking the callback if it did. |
2454 | and sees if it changed compared to the last time, invoking the callback if |
|
|
2455 | it did. |
1895 | .PP |
2456 | .PP |
1896 | The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does |
2457 | The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does |
1897 | not exist\*(R" is a status change like any other. The condition \*(L"path does |
2458 | not exist\*(R" is a status change like any other. The condition \*(L"path does not |
1898 | not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is |
2459 | exist\*(R" (or more correctly \*(L"path cannot be stat'ed\*(R") is signified by the |
1899 | otherwise always forced to be at least one) and all the other fields of |
2460 | \&\f(CW\*(C`st_nlink\*(C'\fR field being zero (which is otherwise always forced to be at |
1900 | the stat buffer having unspecified contents. |
2461 | least one) and all the other fields of the stat buffer having unspecified |
|
|
2462 | contents. |
1901 | .PP |
2463 | .PP |
1902 | The path \fIshould\fR be absolute and \fImust not\fR end in a slash. If it is |
2464 | The path \fImust not\fR end in a slash or contain special components such as |
|
|
2465 | \&\f(CW\*(C`.\*(C'\fR or \f(CW\*(C`..\*(C'\fR. The path \fIshould\fR be absolute: If it is relative and |
1903 | relative and your working directory changes, the behaviour is undefined. |
2466 | your working directory changes, then the behaviour is undefined. |
1904 | .PP |
2467 | .PP |
1905 | Since there is no standard kernel interface to do this, the portable |
2468 | Since there is no portable change notification interface available, the |
1906 | implementation simply calls \f(CW\*(C`stat (2)\*(C'\fR regularly on the path to see if |
2469 | portable implementation simply calls \f(CWstat(2)\fR regularly on the path |
1907 | it changed somehow. You can specify a recommended polling interval for |
2470 | to see if it changed somehow. You can specify a recommended polling |
1908 | this case. If you specify a polling interval of \f(CW0\fR (highly recommended!) |
2471 | interval for this case. If you specify a polling interval of \f(CW0\fR (highly |
1909 | then a \fIsuitable, unspecified default\fR value will be used (which |
2472 | recommended!) then a \fIsuitable, unspecified default\fR value will be used |
1910 | you can expect to be around five seconds, although this might change |
2473 | (which you can expect to be around five seconds, although this might |
1911 | dynamically). Libev will also impose a minimum interval which is currently |
2474 | change dynamically). Libev will also impose a minimum interval which is |
1912 | around \f(CW0.1\fR, but thats usually overkill. |
2475 | currently around \f(CW0.1\fR, but that's usually overkill. |
1913 | .PP |
2476 | .PP |
1914 | This watcher type is not meant for massive numbers of stat watchers, |
2477 | This watcher type is not meant for massive numbers of stat watchers, |
1915 | as even with OS-supported change notifications, this can be |
2478 | as even with OS-supported change notifications, this can be |
1916 | resource-intensive. |
2479 | resource-intensive. |
1917 | .PP |
2480 | .PP |
1918 | At the time of this writing, the only OS-specific interface implemented |
2481 | At the time of this writing, the only OS-specific interface implemented |
1919 | is the Linux inotify interface (implementing kqueue support is left as |
2482 | is the Linux inotify interface (implementing kqueue support is left as an |
1920 | an exercise for the reader. Note, however, that the author sees no way |
2483 | exercise for the reader. Note, however, that the author sees no way of |
1921 | of implementing \f(CW\*(C`ev_stat\*(C'\fR semantics with kqueue). |
2484 | implementing \f(CW\*(C`ev_stat\*(C'\fR semantics with kqueue, except as a hint). |
1922 | .PP |
2485 | .PP |
1923 | \fI\s-1ABI\s0 Issues (Largefile Support)\fR |
2486 | \fI\s-1ABI\s0 Issues (Largefile Support)\fR |
1924 | .IX Subsection "ABI Issues (Largefile Support)" |
2487 | .IX Subsection "ABI Issues (Largefile Support)" |
1925 | .PP |
2488 | .PP |
1926 | Libev by default (unless the user overrides this) uses the default |
2489 | Libev by default (unless the user overrides this) uses the default |
… | |
… | |
1928 | support disabled by default, you get the 32 bit version of the stat |
2491 | support disabled by default, you get the 32 bit version of the stat |
1929 | structure. When using the library from programs that change the \s-1ABI\s0 to |
2492 | structure. When using the library from programs that change the \s-1ABI\s0 to |
1930 | use 64 bit file offsets the programs will fail. In that case you have to |
2493 | use 64 bit file offsets the programs will fail. In that case you have to |
1931 | compile libev with the same flags to get binary compatibility. This is |
2494 | compile libev with the same flags to get binary compatibility. This is |
1932 | obviously the case with any flags that change the \s-1ABI\s0, but the problem is |
2495 | obviously the case with any flags that change the \s-1ABI\s0, but the problem is |
1933 | most noticeably disabled with ev_stat and large file support. |
2496 | most noticeably displayed with ev_stat and large file support. |
1934 | .PP |
2497 | .PP |
1935 | The solution for this is to lobby your distribution maker to make large |
2498 | The solution for this is to lobby your distribution maker to make large |
1936 | file interfaces available by default (as e.g. FreeBSD does) and not |
2499 | file interfaces available by default (as e.g. FreeBSD does) and not |
1937 | optional. Libev cannot simply switch on large file support because it has |
2500 | optional. Libev cannot simply switch on large file support because it has |
1938 | to exchange stat structures with application programs compiled using the |
2501 | to exchange stat structures with application programs compiled using the |
1939 | default compilation environment. |
2502 | default compilation environment. |
1940 | .PP |
2503 | .PP |
1941 | \fIInotify and Kqueue\fR |
2504 | \fIInotify and Kqueue\fR |
1942 | .IX Subsection "Inotify and Kqueue" |
2505 | .IX Subsection "Inotify and Kqueue" |
1943 | .PP |
2506 | .PP |
1944 | When \f(CW\*(C`inotify (7)\*(C'\fR support has been compiled into libev (generally |
2507 | When \f(CW\*(C`inotify (7)\*(C'\fR support has been compiled into libev and present at |
1945 | only available with Linux 2.6.25 or above due to bugs in earlier |
2508 | runtime, it will be used to speed up change detection where possible. The |
1946 | implementations) and present at runtime, it will be used to speed up |
2509 | inotify descriptor will be created lazily when the first \f(CW\*(C`ev_stat\*(C'\fR |
1947 | change detection where possible. The inotify descriptor will be created |
2510 | watcher is being started. |
1948 | lazily when the first \f(CW\*(C`ev_stat\*(C'\fR watcher is being started. |
|
|
1949 | .PP |
2511 | .PP |
1950 | Inotify presence does not change the semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers |
2512 | Inotify presence does not change the semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers |
1951 | except that changes might be detected earlier, and in some cases, to avoid |
2513 | except that changes might be detected earlier, and in some cases, to avoid |
1952 | making regular \f(CW\*(C`stat\*(C'\fR calls. Even in the presence of inotify support |
2514 | making regular \f(CW\*(C`stat\*(C'\fR calls. Even in the presence of inotify support |
1953 | there are many cases where libev has to resort to regular \f(CW\*(C`stat\*(C'\fR polling, |
2515 | there are many cases where libev has to resort to regular \f(CW\*(C`stat\*(C'\fR polling, |
1954 | but as long as the path exists, libev usually gets away without polling. |
2516 | but as long as kernel 2.6.25 or newer is used (2.6.24 and older have too |
|
|
2517 | many bugs), the path exists (i.e. stat succeeds), and the path resides on |
|
|
2518 | a local filesystem (libev currently assumes only ext2/3, jfs, reiserfs and |
|
|
2519 | xfs are fully working) libev usually gets away without polling. |
1955 | .PP |
2520 | .PP |
1956 | There is no support for kqueue, as apparently it cannot be used to |
2521 | There is no support for kqueue, as apparently it cannot be used to |
1957 | implement this functionality, due to the requirement of having a file |
2522 | implement this functionality, due to the requirement of having a file |
1958 | descriptor open on the object at all times, and detecting renames, unlinks |
2523 | descriptor open on the object at all times, and detecting renames, unlinks |
1959 | etc. is difficult. |
2524 | etc. is difficult. |
1960 | .PP |
2525 | .PP |
|
|
2526 | \fI\f(CI\*(C`stat ()\*(C'\fI is a synchronous operation\fR |
|
|
2527 | .IX Subsection "stat () is a synchronous operation" |
|
|
2528 | .PP |
|
|
2529 | Libev doesn't normally do any kind of I/O itself, and so is not blocking |
|
|
2530 | the process. The exception are \f(CW\*(C`ev_stat\*(C'\fR watchers \- those call \f(CW\*(C`stat |
|
|
2531 | ()\*(C'\fR, which is a synchronous operation. |
|
|
2532 | .PP |
|
|
2533 | For local paths, this usually doesn't matter: unless the system is very |
|
|
2534 | busy or the intervals between stat's are large, a stat call will be fast, |
|
|
2535 | as the path data is usually in memory already (except when starting the |
|
|
2536 | watcher). |
|
|
2537 | .PP |
|
|
2538 | For networked file systems, calling \f(CW\*(C`stat ()\*(C'\fR can block an indefinite |
|
|
2539 | time due to network issues, and even under good conditions, a stat call |
|
|
2540 | often takes multiple milliseconds. |
|
|
2541 | .PP |
|
|
2542 | Therefore, it is best to avoid using \f(CW\*(C`ev_stat\*(C'\fR watchers on networked |
|
|
2543 | paths, although this is fully supported by libev. |
|
|
2544 | .PP |
1961 | \fIThe special problem of stat time resolution\fR |
2545 | \fIThe special problem of stat time resolution\fR |
1962 | .IX Subsection "The special problem of stat time resolution" |
2546 | .IX Subsection "The special problem of stat time resolution" |
1963 | .PP |
2547 | .PP |
1964 | The \f(CW\*(C`stat ()\*(C'\fR system call only supports full-second resolution portably, and |
2548 | The \f(CW\*(C`stat ()\*(C'\fR system call only supports full-second resolution portably, |
1965 | even on systems where the resolution is higher, most file systems still |
2549 | and even on systems where the resolution is higher, most file systems |
1966 | only support whole seconds. |
2550 | still only support whole seconds. |
1967 | .PP |
2551 | .PP |
1968 | That means that, if the time is the only thing that changes, you can |
2552 | That means that, if the time is the only thing that changes, you can |
1969 | easily miss updates: on the first update, \f(CW\*(C`ev_stat\*(C'\fR detects a change and |
2553 | easily miss updates: on the first update, \f(CW\*(C`ev_stat\*(C'\fR detects a change and |
1970 | calls your callback, which does something. When there is another update |
2554 | calls your callback, which does something. When there is another update |
1971 | within the same second, \f(CW\*(C`ev_stat\*(C'\fR will be unable to detect unless the |
2555 | within the same second, \f(CW\*(C`ev_stat\*(C'\fR will be unable to detect unless the |
… | |
… | |
2085 | \& ... |
2669 | \& ... |
2086 | \& ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
2670 | \& ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
2087 | \& ev_stat_start (loop, &passwd); |
2671 | \& ev_stat_start (loop, &passwd); |
2088 | \& ev_timer_init (&timer, timer_cb, 0., 1.02); |
2672 | \& ev_timer_init (&timer, timer_cb, 0., 1.02); |
2089 | .Ve |
2673 | .Ve |
2090 | .ie n .Sh """ev_idle"" \- when you've got nothing better to do..." |
2674 | .ie n .SS """ev_idle"" \- when you've got nothing better to do..." |
2091 | .el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..." |
2675 | .el .SS "\f(CWev_idle\fP \- when you've got nothing better to do..." |
2092 | .IX Subsection "ev_idle - when you've got nothing better to do..." |
2676 | .IX Subsection "ev_idle - when you've got nothing better to do..." |
2093 | Idle watchers trigger events when no other events of the same or higher |
2677 | Idle watchers trigger events when no other events of the same or higher |
2094 | priority are pending (prepare, check and other idle watchers do not count |
2678 | priority are pending (prepare, check and other idle watchers do not count |
2095 | as receiving \*(L"events\*(R"). |
2679 | as receiving \*(L"events\*(R"). |
2096 | .PP |
2680 | .PP |
… | |
… | |
2109 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
2693 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
2110 | event loop has handled all outstanding events. |
2694 | event loop has handled all outstanding events. |
2111 | .PP |
2695 | .PP |
2112 | \fIWatcher-Specific Functions and Data Members\fR |
2696 | \fIWatcher-Specific Functions and Data Members\fR |
2113 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2697 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2114 | .IP "ev_idle_init (ev_signal *, callback)" 4 |
2698 | .IP "ev_idle_init (ev_idle *, callback)" 4 |
2115 | .IX Item "ev_idle_init (ev_signal *, callback)" |
2699 | .IX Item "ev_idle_init (ev_idle *, callback)" |
2116 | Initialises and configures the idle watcher \- it has no parameters of any |
2700 | Initialises and configures the idle watcher \- it has no parameters of any |
2117 | kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, |
2701 | kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, |
2118 | believe me. |
2702 | believe me. |
2119 | .PP |
2703 | .PP |
2120 | \fIExamples\fR |
2704 | \fIExamples\fR |
… | |
… | |
2123 | Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the |
2707 | Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the |
2124 | callback, free it. Also, use no error checking, as usual. |
2708 | callback, free it. Also, use no error checking, as usual. |
2125 | .PP |
2709 | .PP |
2126 | .Vb 7 |
2710 | .Vb 7 |
2127 | \& static void |
2711 | \& static void |
2128 | \& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
2712 | \& idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
2129 | \& { |
2713 | \& { |
2130 | \& free (w); |
2714 | \& free (w); |
2131 | \& // now do something you wanted to do when the program has |
2715 | \& // now do something you wanted to do when the program has |
2132 | \& // no longer anything immediate to do. |
2716 | \& // no longer anything immediate to do. |
2133 | \& } |
2717 | \& } |
2134 | \& |
2718 | \& |
2135 | \& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
2719 | \& ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
2136 | \& ev_idle_init (idle_watcher, idle_cb); |
2720 | \& ev_idle_init (idle_watcher, idle_cb); |
2137 | \& ev_idle_start (loop, idle_cb); |
2721 | \& ev_idle_start (loop, idle_watcher); |
2138 | .Ve |
2722 | .Ve |
2139 | .ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!" |
2723 | .ie n .SS """ev_prepare"" and ""ev_check"" \- customise your event loop!" |
2140 | .el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" |
2724 | .el .SS "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" |
2141 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
2725 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
2142 | Prepare and check watchers are usually (but not always) used in pairs: |
2726 | Prepare and check watchers are usually (but not always) used in pairs: |
2143 | prepare watchers get invoked before the process blocks and check watchers |
2727 | prepare watchers get invoked before the process blocks and check watchers |
2144 | afterwards. |
2728 | afterwards. |
2145 | .PP |
2729 | .PP |
… | |
… | |
2221 | .Vb 2 |
2805 | .Vb 2 |
2222 | \& static ev_io iow [nfd]; |
2806 | \& static ev_io iow [nfd]; |
2223 | \& static ev_timer tw; |
2807 | \& static ev_timer tw; |
2224 | \& |
2808 | \& |
2225 | \& static void |
2809 | \& static void |
2226 | \& io_cb (ev_loop *loop, ev_io *w, int revents) |
2810 | \& io_cb (struct ev_loop *loop, ev_io *w, int revents) |
2227 | \& { |
2811 | \& { |
2228 | \& } |
2812 | \& } |
2229 | \& |
2813 | \& |
2230 | \& // create io watchers for each fd and a timer before blocking |
2814 | \& // create io watchers for each fd and a timer before blocking |
2231 | \& static void |
2815 | \& static void |
2232 | \& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
2816 | \& adns_prepare_cb (struct ev_loop *loop, ev_prepare *w, int revents) |
2233 | \& { |
2817 | \& { |
2234 | \& int timeout = 3600000; |
2818 | \& int timeout = 3600000; |
2235 | \& struct pollfd fds [nfd]; |
2819 | \& struct pollfd fds [nfd]; |
2236 | \& // actual code will need to loop here and realloc etc. |
2820 | \& // actual code will need to loop here and realloc etc. |
2237 | \& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2821 | \& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2238 | \& |
2822 | \& |
2239 | \& /* the callback is illegal, but won\*(Aqt be called as we stop during check */ |
2823 | \& /* the callback is illegal, but won\*(Aqt be called as we stop during check */ |
2240 | \& ev_timer_init (&tw, 0, timeout * 1e\-3); |
2824 | \& ev_timer_init (&tw, 0, timeout * 1e\-3, 0.); |
2241 | \& ev_timer_start (loop, &tw); |
2825 | \& ev_timer_start (loop, &tw); |
2242 | \& |
2826 | \& |
2243 | \& // create one ev_io per pollfd |
2827 | \& // create one ev_io per pollfd |
2244 | \& for (int i = 0; i < nfd; ++i) |
2828 | \& for (int i = 0; i < nfd; ++i) |
2245 | \& { |
2829 | \& { |
… | |
… | |
2252 | \& } |
2836 | \& } |
2253 | \& } |
2837 | \& } |
2254 | \& |
2838 | \& |
2255 | \& // stop all watchers after blocking |
2839 | \& // stop all watchers after blocking |
2256 | \& static void |
2840 | \& static void |
2257 | \& adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
2841 | \& adns_check_cb (struct ev_loop *loop, ev_check *w, int revents) |
2258 | \& { |
2842 | \& { |
2259 | \& ev_timer_stop (loop, &tw); |
2843 | \& ev_timer_stop (loop, &tw); |
2260 | \& |
2844 | \& |
2261 | \& for (int i = 0; i < nfd; ++i) |
2845 | \& for (int i = 0; i < nfd; ++i) |
2262 | \& { |
2846 | \& { |
… | |
… | |
2336 | \& ev_io_stop (EV_A_ iow [n]); |
2920 | \& ev_io_stop (EV_A_ iow [n]); |
2337 | \& |
2921 | \& |
2338 | \& return got_events; |
2922 | \& return got_events; |
2339 | \& } |
2923 | \& } |
2340 | .Ve |
2924 | .Ve |
2341 | .ie n .Sh """ev_embed"" \- when one backend isn't enough..." |
2925 | .ie n .SS """ev_embed"" \- when one backend isn't enough..." |
2342 | .el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." |
2926 | .el .SS "\f(CWev_embed\fP \- when one backend isn't enough..." |
2343 | .IX Subsection "ev_embed - when one backend isn't enough..." |
2927 | .IX Subsection "ev_embed - when one backend isn't enough..." |
2344 | This is a rather advanced watcher type that lets you embed one event loop |
2928 | This is a rather advanced watcher type that lets you embed one event loop |
2345 | into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded |
2929 | into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded |
2346 | loop, other types of watchers might be handled in a delayed or incorrect |
2930 | loop, other types of watchers might be handled in a delayed or incorrect |
2347 | fashion and must not be used). |
2931 | fashion and must not be used). |
… | |
… | |
2362 | some fds have to be watched and handled very quickly (with low latency), |
2946 | some fds have to be watched and handled very quickly (with low latency), |
2363 | and even priorities and idle watchers might have too much overhead. In |
2947 | and even priorities and idle watchers might have too much overhead. In |
2364 | this case you would put all the high priority stuff in one loop and all |
2948 | this case you would put all the high priority stuff in one loop and all |
2365 | the rest in a second one, and embed the second one in the first. |
2949 | the rest in a second one, and embed the second one in the first. |
2366 | .PP |
2950 | .PP |
2367 | As long as the watcher is active, the callback will be invoked every time |
2951 | As long as the watcher is active, the callback will be invoked every |
2368 | there might be events pending in the embedded loop. The callback must then |
2952 | time there might be events pending in the embedded loop. The callback |
2369 | call \f(CW\*(C`ev_embed_sweep (mainloop, watcher)\*(C'\fR to make a single sweep and invoke |
2953 | must then call \f(CW\*(C`ev_embed_sweep (mainloop, watcher)\*(C'\fR to make a single |
2370 | their callbacks (you could also start an idle watcher to give the embedded |
2954 | sweep and invoke their callbacks (the callback doesn't need to invoke the |
2371 | loop strictly lower priority for example). You can also set the callback |
2955 | \&\f(CW\*(C`ev_embed_sweep\*(C'\fR function directly, it could also start an idle watcher |
2372 | to \f(CW0\fR, in which case the embed watcher will automatically execute the |
2956 | to give the embedded loop strictly lower priority for example). |
2373 | embedded loop sweep. |
|
|
2374 | .PP |
2957 | .PP |
2375 | As long as the watcher is started it will automatically handle events. The |
2958 | You can also set the callback to \f(CW0\fR, in which case the embed watcher |
2376 | callback will be invoked whenever some events have been handled. You can |
2959 | will automatically execute the embedded loop sweep whenever necessary. |
2377 | set the callback to \f(CW0\fR to avoid having to specify one if you are not |
|
|
2378 | interested in that. |
|
|
2379 | .PP |
2960 | .PP |
2380 | Also, there have not currently been made special provisions for forking: |
2961 | Fork detection will be handled transparently while the \f(CW\*(C`ev_embed\*(C'\fR watcher |
2381 | when you fork, you not only have to call \f(CW\*(C`ev_loop_fork\*(C'\fR on both loops, |
2962 | is active, i.e., the embedded loop will automatically be forked when the |
2382 | but you will also have to stop and restart any \f(CW\*(C`ev_embed\*(C'\fR watchers |
2963 | embedding loop forks. In other cases, the user is responsible for calling |
2383 | yourself \- but you can use a fork watcher to handle this automatically, |
2964 | \&\f(CW\*(C`ev_loop_fork\*(C'\fR on the embedded loop. |
2384 | and future versions of libev might do just that. |
|
|
2385 | .PP |
2965 | .PP |
2386 | Unfortunately, not all backends are embeddable: only the ones returned by |
2966 | Unfortunately, not all backends are embeddable: only the ones returned by |
2387 | \&\f(CW\*(C`ev_embeddable_backends\*(C'\fR are, which, unfortunately, does not include any |
2967 | \&\f(CW\*(C`ev_embeddable_backends\*(C'\fR are, which, unfortunately, does not include any |
2388 | portable one. |
2968 | portable one. |
2389 | .PP |
2969 | .PP |
… | |
… | |
2433 | used). |
3013 | used). |
2434 | .PP |
3014 | .PP |
2435 | .Vb 3 |
3015 | .Vb 3 |
2436 | \& struct ev_loop *loop_hi = ev_default_init (0); |
3016 | \& struct ev_loop *loop_hi = ev_default_init (0); |
2437 | \& struct ev_loop *loop_lo = 0; |
3017 | \& struct ev_loop *loop_lo = 0; |
2438 | \& struct ev_embed embed; |
3018 | \& ev_embed embed; |
2439 | \& |
3019 | \& |
2440 | \& // see if there is a chance of getting one that works |
3020 | \& // see if there is a chance of getting one that works |
2441 | \& // (remember that a flags value of 0 means autodetection) |
3021 | \& // (remember that a flags value of 0 means autodetection) |
2442 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3022 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
2443 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3023 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
… | |
… | |
2459 | \&\f(CW\*(C`loop_socket\*(C'\fR. (One might optionally use \f(CW\*(C`EVFLAG_NOENV\*(C'\fR, too). |
3039 | \&\f(CW\*(C`loop_socket\*(C'\fR. (One might optionally use \f(CW\*(C`EVFLAG_NOENV\*(C'\fR, too). |
2460 | .PP |
3040 | .PP |
2461 | .Vb 3 |
3041 | .Vb 3 |
2462 | \& struct ev_loop *loop = ev_default_init (0); |
3042 | \& struct ev_loop *loop = ev_default_init (0); |
2463 | \& struct ev_loop *loop_socket = 0; |
3043 | \& struct ev_loop *loop_socket = 0; |
2464 | \& struct ev_embed embed; |
3044 | \& ev_embed embed; |
2465 | \& |
3045 | \& |
2466 | \& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3046 | \& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
2467 | \& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3047 | \& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
2468 | \& { |
3048 | \& { |
2469 | \& ev_embed_init (&embed, 0, loop_socket); |
3049 | \& ev_embed_init (&embed, 0, loop_socket); |
… | |
… | |
2473 | \& if (!loop_socket) |
3053 | \& if (!loop_socket) |
2474 | \& loop_socket = loop; |
3054 | \& loop_socket = loop; |
2475 | \& |
3055 | \& |
2476 | \& // now use loop_socket for all sockets, and loop for everything else |
3056 | \& // now use loop_socket for all sockets, and loop for everything else |
2477 | .Ve |
3057 | .Ve |
2478 | .ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork" |
3058 | .ie n .SS """ev_fork"" \- the audacity to resume the event loop after a fork" |
2479 | .el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
3059 | .el .SS "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
2480 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
3060 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
2481 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
3061 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
2482 | whoever is a good citizen cared to tell libev about it by calling |
3062 | whoever is a good citizen cared to tell libev about it by calling |
2483 | \&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the |
3063 | \&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the |
2484 | event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, |
3064 | event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, |
2485 | and only in the child after the fork. If whoever good citizen calling |
3065 | and only in the child after the fork. If whoever good citizen calling |
2486 | \&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork |
3066 | \&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork |
2487 | handlers will be invoked, too, of course. |
3067 | handlers will be invoked, too, of course. |
2488 | .PP |
3068 | .PP |
|
|
3069 | \fIThe special problem of life after fork \- how is it possible?\fR |
|
|
3070 | .IX Subsection "The special problem of life after fork - how is it possible?" |
|
|
3071 | .PP |
|
|
3072 | Most uses of \f(CW\*(C`fork()\*(C'\fR consist of forking, then some simple calls to ste |
|
|
3073 | up/change the process environment, followed by a call to \f(CW\*(C`exec()\*(C'\fR. This |
|
|
3074 | sequence should be handled by libev without any problems. |
|
|
3075 | .PP |
|
|
3076 | This changes when the application actually wants to do event handling |
|
|
3077 | in the child, or both parent in child, in effect \*(L"continuing\*(R" after the |
|
|
3078 | fork. |
|
|
3079 | .PP |
|
|
3080 | The default mode of operation (for libev, with application help to detect |
|
|
3081 | forks) is to duplicate all the state in the child, as would be expected |
|
|
3082 | when \fIeither\fR the parent \fIor\fR the child process continues. |
|
|
3083 | .PP |
|
|
3084 | When both processes want to continue using libev, then this is usually the |
|
|
3085 | wrong result. In that case, usually one process (typically the parent) is |
|
|
3086 | supposed to continue with all watchers in place as before, while the other |
|
|
3087 | process typically wants to start fresh, i.e. without any active watchers. |
|
|
3088 | .PP |
|
|
3089 | The cleanest and most efficient way to achieve that with libev is to |
|
|
3090 | simply create a new event loop, which of course will be \*(L"empty\*(R", and |
|
|
3091 | use that for new watchers. This has the advantage of not touching more |
|
|
3092 | memory than necessary, and thus avoiding the copy-on-write, and the |
|
|
3093 | disadvantage of having to use multiple event loops (which do not support |
|
|
3094 | signal watchers). |
|
|
3095 | .PP |
|
|
3096 | When this is not possible, or you want to use the default loop for |
|
|
3097 | other reasons, then in the process that wants to start \*(L"fresh\*(R", call |
|
|
3098 | \&\f(CW\*(C`ev_default_destroy ()\*(C'\fR followed by \f(CW\*(C`ev_default_loop (...)\*(C'\fR. Destroying |
|
|
3099 | the default loop will \*(L"orphan\*(R" (not stop) all registered watchers, so you |
|
|
3100 | have to be careful not to execute code that modifies those watchers. Note |
|
|
3101 | also that in that case, you have to re-register any signal watchers. |
|
|
3102 | .PP |
2489 | \fIWatcher-Specific Functions and Data Members\fR |
3103 | \fIWatcher-Specific Functions and Data Members\fR |
2490 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3104 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2491 | .IP "ev_fork_init (ev_signal *, callback)" 4 |
3105 | .IP "ev_fork_init (ev_signal *, callback)" 4 |
2492 | .IX Item "ev_fork_init (ev_signal *, callback)" |
3106 | .IX Item "ev_fork_init (ev_signal *, callback)" |
2493 | Initialises and configures the fork watcher \- it has no parameters of any |
3107 | Initialises and configures the fork watcher \- it has no parameters of any |
2494 | kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, |
3108 | kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, |
2495 | believe me. |
3109 | believe me. |
2496 | .ie n .Sh """ev_async"" \- how to wake up another event loop" |
3110 | .ie n .SS """ev_async"" \- how to wake up another event loop" |
2497 | .el .Sh "\f(CWev_async\fP \- how to wake up another event loop" |
3111 | .el .SS "\f(CWev_async\fP \- how to wake up another event loop" |
2498 | .IX Subsection "ev_async - how to wake up another event loop" |
3112 | .IX Subsection "ev_async - how to wake up another event loop" |
2499 | In general, you cannot use an \f(CW\*(C`ev_loop\*(C'\fR from multiple threads or other |
3113 | In general, you cannot use an \f(CW\*(C`ev_loop\*(C'\fR from multiple threads or other |
2500 | asynchronous sources such as signal handlers (as opposed to multiple event |
3114 | asynchronous sources such as signal handlers (as opposed to multiple event |
2501 | loops \- those are of course safe to use in different threads). |
3115 | loops \- those are of course safe to use in different threads). |
2502 | .PP |
3116 | .PP |
… | |
… | |
2518 | .IX Subsection "Queueing" |
3132 | .IX Subsection "Queueing" |
2519 | .PP |
3133 | .PP |
2520 | \&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason |
3134 | \&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason |
2521 | is that the author does not know of a simple (or any) algorithm for a |
3135 | is that the author does not know of a simple (or any) algorithm for a |
2522 | multiple-writer-single-reader queue that works in all cases and doesn't |
3136 | multiple-writer-single-reader queue that works in all cases and doesn't |
2523 | need elaborate support such as pthreads. |
3137 | need elaborate support such as pthreads or unportable memory access |
|
|
3138 | semantics. |
2524 | .PP |
3139 | .PP |
2525 | That means that if you want to queue data, you have to provide your own |
3140 | That means that if you want to queue data, you have to provide your own |
2526 | queue. But at least I can tell you how to implement locking around your |
3141 | queue. But at least I can tell you how to implement locking around your |
2527 | queue: |
3142 | queue: |
2528 | .IP "queueing from a signal handler context" 4 |
3143 | .IP "queueing from a signal handler context" 4 |
… | |
… | |
2601 | \fIWatcher-Specific Functions and Data Members\fR |
3216 | \fIWatcher-Specific Functions and Data Members\fR |
2602 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3217 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2603 | .IP "ev_async_init (ev_async *, callback)" 4 |
3218 | .IP "ev_async_init (ev_async *, callback)" 4 |
2604 | .IX Item "ev_async_init (ev_async *, callback)" |
3219 | .IX Item "ev_async_init (ev_async *, callback)" |
2605 | Initialises and configures the async watcher \- it has no parameters of any |
3220 | Initialises and configures the async watcher \- it has no parameters of any |
2606 | kind. There is a \f(CW\*(C`ev_asynd_set\*(C'\fR macro, but using it is utterly pointless, |
3221 | kind. There is a \f(CW\*(C`ev_async_set\*(C'\fR macro, but using it is utterly pointless, |
2607 | trust me. |
3222 | trust me. |
2608 | .IP "ev_async_send (loop, ev_async *)" 4 |
3223 | .IP "ev_async_send (loop, ev_async *)" 4 |
2609 | .IX Item "ev_async_send (loop, ev_async *)" |
3224 | .IX Item "ev_async_send (loop, ev_async *)" |
2610 | Sends/signals/activates the given \f(CW\*(C`ev_async\*(C'\fR watcher, that is, feeds |
3225 | Sends/signals/activates the given \f(CW\*(C`ev_async\*(C'\fR watcher, that is, feeds |
2611 | an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop. Unlike |
3226 | an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop. Unlike |
2612 | \&\f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do from other threads, signal or |
3227 | \&\f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do from other threads, signal or |
2613 | similar contexts (see the discussion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the embedding |
3228 | similar contexts (see the discussion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the embedding |
2614 | section below on what exactly this means). |
3229 | section below on what exactly this means). |
2615 | .Sp |
3230 | .Sp |
|
|
3231 | Note that, as with other watchers in libev, multiple events might get |
|
|
3232 | compressed into a single callback invocation (another way to look at this |
|
|
3233 | is that \f(CW\*(C`ev_async\*(C'\fR watchers are level-triggered, set on \f(CW\*(C`ev_async_send\*(C'\fR, |
|
|
3234 | reset when the event loop detects that). |
|
|
3235 | .Sp |
2616 | This call incurs the overhead of a system call only once per loop iteration, |
3236 | This call incurs the overhead of a system call only once per event loop |
2617 | so while the overhead might be noticeable, it doesn't apply to repeated |
3237 | iteration, so while the overhead might be noticeable, it doesn't apply to |
2618 | calls to \f(CW\*(C`ev_async_send\*(C'\fR. |
3238 | repeated calls to \f(CW\*(C`ev_async_send\*(C'\fR for the same event loop. |
2619 | .IP "bool = ev_async_pending (ev_async *)" 4 |
3239 | .IP "bool = ev_async_pending (ev_async *)" 4 |
2620 | .IX Item "bool = ev_async_pending (ev_async *)" |
3240 | .IX Item "bool = ev_async_pending (ev_async *)" |
2621 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
3241 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
2622 | watcher but the event has not yet been processed (or even noted) by the |
3242 | watcher but the event has not yet been processed (or even noted) by the |
2623 | event loop. |
3243 | event loop. |
… | |
… | |
2625 | \&\f(CW\*(C`ev_async_send\*(C'\fR sets a flag in the watcher and wakes up the loop. When |
3245 | \&\f(CW\*(C`ev_async_send\*(C'\fR sets a flag in the watcher and wakes up the loop. When |
2626 | the loop iterates next and checks for the watcher to have become active, |
3246 | the loop iterates next and checks for the watcher to have become active, |
2627 | it will reset the flag again. \f(CW\*(C`ev_async_pending\*(C'\fR can be used to very |
3247 | it will reset the flag again. \f(CW\*(C`ev_async_pending\*(C'\fR can be used to very |
2628 | quickly check whether invoking the loop might be a good idea. |
3248 | quickly check whether invoking the loop might be a good idea. |
2629 | .Sp |
3249 | .Sp |
2630 | Not that this does \fInot\fR check whether the watcher itself is pending, only |
3250 | Not that this does \fInot\fR check whether the watcher itself is pending, |
2631 | whether it has been requested to make this watcher pending. |
3251 | only whether it has been requested to make this watcher pending: there |
|
|
3252 | is a time window between the event loop checking and resetting the async |
|
|
3253 | notification, and the callback being invoked. |
2632 | .SH "OTHER FUNCTIONS" |
3254 | .SH "OTHER FUNCTIONS" |
2633 | .IX Header "OTHER FUNCTIONS" |
3255 | .IX Header "OTHER FUNCTIONS" |
2634 | There are some other functions of possible interest. Described. Here. Now. |
3256 | There are some other functions of possible interest. Described. Here. Now. |
2635 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
3257 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
2636 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
3258 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
… | |
… | |
2666 | \& /* doh, nothing entered */; |
3288 | \& /* doh, nothing entered */; |
2667 | \& } |
3289 | \& } |
2668 | \& |
3290 | \& |
2669 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3291 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
2670 | .Ve |
3292 | .Ve |
2671 | .IP "ev_feed_event (ev_loop *, watcher *, int revents)" 4 |
|
|
2672 | .IX Item "ev_feed_event (ev_loop *, watcher *, int revents)" |
|
|
2673 | Feeds the given event set into the event loop, as if the specified event |
|
|
2674 | had happened for the specified watcher (which must be a pointer to an |
|
|
2675 | initialised but not necessarily started event watcher). |
|
|
2676 | .IP "ev_feed_fd_event (ev_loop *, int fd, int revents)" 4 |
3293 | .IP "ev_feed_fd_event (loop, int fd, int revents)" 4 |
2677 | .IX Item "ev_feed_fd_event (ev_loop *, int fd, int revents)" |
3294 | .IX Item "ev_feed_fd_event (loop, int fd, int revents)" |
2678 | Feed an event on the given fd, as if a file descriptor backend detected |
3295 | Feed an event on the given fd, as if a file descriptor backend detected |
2679 | the given events it. |
3296 | the given events it. |
2680 | .IP "ev_feed_signal_event (ev_loop *loop, int signum)" 4 |
3297 | .IP "ev_feed_signal_event (loop, int signum)" 4 |
2681 | .IX Item "ev_feed_signal_event (ev_loop *loop, int signum)" |
3298 | .IX Item "ev_feed_signal_event (loop, int signum)" |
2682 | Feed an event as if the given signal occurred (\f(CW\*(C`loop\*(C'\fR must be the default |
3299 | Feed an event as if the given signal occurred (\f(CW\*(C`loop\*(C'\fR must be the default |
2683 | loop!). |
3300 | loop!). |
2684 | .SH "LIBEVENT EMULATION" |
3301 | .SH "LIBEVENT EMULATION" |
2685 | .IX Header "LIBEVENT EMULATION" |
3302 | .IX Header "LIBEVENT EMULATION" |
2686 | Libev offers a compatibility emulation layer for libevent. It cannot |
3303 | Libev offers a compatibility emulation layer for libevent. It cannot |
… | |
… | |
2733 | need one additional pointer for context. If you need support for other |
3350 | need one additional pointer for context. If you need support for other |
2734 | types of functors please contact the author (preferably after implementing |
3351 | types of functors please contact the author (preferably after implementing |
2735 | it). |
3352 | it). |
2736 | .PP |
3353 | .PP |
2737 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
3354 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
2738 | .ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4 |
3355 | .ie n .IP """ev::READ"", ""ev::WRITE"" etc." 4 |
2739 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
3356 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
2740 | .IX Item "ev::READ, ev::WRITE etc." |
3357 | .IX Item "ev::READ, ev::WRITE etc." |
2741 | These are just enum values with the same values as the \f(CW\*(C`EV_READ\*(C'\fR etc. |
3358 | These are just enum values with the same values as the \f(CW\*(C`EV_READ\*(C'\fR etc. |
2742 | macros from \fIev.h\fR. |
3359 | macros from \fIev.h\fR. |
2743 | .ie n .IP """ev::tstamp""\fR, \f(CW""ev::now""" 4 |
3360 | .ie n .IP """ev::tstamp"", ""ev::now""" 4 |
2744 | .el .IP "\f(CWev::tstamp\fR, \f(CWev::now\fR" 4 |
3361 | .el .IP "\f(CWev::tstamp\fR, \f(CWev::now\fR" 4 |
2745 | .IX Item "ev::tstamp, ev::now" |
3362 | .IX Item "ev::tstamp, ev::now" |
2746 | Aliases to the same types/functions as with the \f(CW\*(C`ev_\*(C'\fR prefix. |
3363 | Aliases to the same types/functions as with the \f(CW\*(C`ev_\*(C'\fR prefix. |
2747 | .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 |
3364 | .ie n .IP """ev::io"", ""ev::timer"", ""ev::periodic"", ""ev::idle"", ""ev::sig"" etc." 4 |
2748 | .el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4 |
3365 | .el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4 |
2749 | .IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc." |
3366 | .IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc." |
2750 | For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of |
3367 | For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of |
2751 | the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR |
3368 | the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR |
2752 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
3369 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
… | |
… | |
2755 | All of those classes have these methods: |
3372 | All of those classes have these methods: |
2756 | .RS 4 |
3373 | .RS 4 |
2757 | .IP "ev::TYPE::TYPE ()" 4 |
3374 | .IP "ev::TYPE::TYPE ()" 4 |
2758 | .IX Item "ev::TYPE::TYPE ()" |
3375 | .IX Item "ev::TYPE::TYPE ()" |
2759 | .PD 0 |
3376 | .PD 0 |
2760 | .IP "ev::TYPE::TYPE (struct ev_loop *)" 4 |
3377 | .IP "ev::TYPE::TYPE (loop)" 4 |
2761 | .IX Item "ev::TYPE::TYPE (struct ev_loop *)" |
3378 | .IX Item "ev::TYPE::TYPE (loop)" |
2762 | .IP "ev::TYPE::~TYPE" 4 |
3379 | .IP "ev::TYPE::~TYPE" 4 |
2763 | .IX Item "ev::TYPE::~TYPE" |
3380 | .IX Item "ev::TYPE::~TYPE" |
2764 | .PD |
3381 | .PD |
2765 | The constructor (optionally) takes an event loop to associate the watcher |
3382 | The constructor (optionally) takes an event loop to associate the watcher |
2766 | with. If it is omitted, it will use \f(CW\*(C`EV_DEFAULT\*(C'\fR. |
3383 | with. If it is omitted, it will use \f(CW\*(C`EV_DEFAULT\*(C'\fR. |
… | |
… | |
2798 | \& |
3415 | \& |
2799 | \& myclass obj; |
3416 | \& myclass obj; |
2800 | \& ev::io iow; |
3417 | \& ev::io iow; |
2801 | \& iow.set <myclass, &myclass::io_cb> (&obj); |
3418 | \& iow.set <myclass, &myclass::io_cb> (&obj); |
2802 | .Ve |
3419 | .Ve |
|
|
3420 | .IP "w\->set (object *)" 4 |
|
|
3421 | .IX Item "w->set (object *)" |
|
|
3422 | This is an \fBexperimental\fR feature that might go away in a future version. |
|
|
3423 | .Sp |
|
|
3424 | This is a variation of a method callback \- leaving out the method to call |
|
|
3425 | will default the method to \f(CW\*(C`operator ()\*(C'\fR, which makes it possible to use |
|
|
3426 | functor objects without having to manually specify the \f(CW\*(C`operator ()\*(C'\fR all |
|
|
3427 | the time. Incidentally, you can then also leave out the template argument |
|
|
3428 | list. |
|
|
3429 | .Sp |
|
|
3430 | The \f(CW\*(C`operator ()\*(C'\fR method prototype must be \f(CW\*(C`void operator ()(watcher &w, |
|
|
3431 | int revents)\*(C'\fR. |
|
|
3432 | .Sp |
|
|
3433 | See the method\-\f(CW\*(C`set\*(C'\fR above for more details. |
|
|
3434 | .Sp |
|
|
3435 | Example: use a functor object as callback. |
|
|
3436 | .Sp |
|
|
3437 | .Vb 7 |
|
|
3438 | \& struct myfunctor |
|
|
3439 | \& { |
|
|
3440 | \& void operator() (ev::io &w, int revents) |
|
|
3441 | \& { |
|
|
3442 | \& ... |
|
|
3443 | \& } |
|
|
3444 | \& } |
|
|
3445 | \& |
|
|
3446 | \& myfunctor f; |
|
|
3447 | \& |
|
|
3448 | \& ev::io w; |
|
|
3449 | \& w.set (&f); |
|
|
3450 | .Ve |
2803 | .IP "w\->set<function> (void *data = 0)" 4 |
3451 | .IP "w\->set<function> (void *data = 0)" 4 |
2804 | .IX Item "w->set<function> (void *data = 0)" |
3452 | .IX Item "w->set<function> (void *data = 0)" |
2805 | Also sets a callback, but uses a static method or plain function as |
3453 | Also sets a callback, but uses a static method or plain function as |
2806 | callback. The optional \f(CW\*(C`data\*(C'\fR argument will be stored in the watcher's |
3454 | callback. The optional \f(CW\*(C`data\*(C'\fR argument will be stored in the watcher's |
2807 | \&\f(CW\*(C`data\*(C'\fR member and is free for you to use. |
3455 | \&\f(CW\*(C`data\*(C'\fR member and is free for you to use. |
… | |
… | |
2814 | .Sp |
3462 | .Sp |
2815 | .Vb 2 |
3463 | .Vb 2 |
2816 | \& static void io_cb (ev::io &w, int revents) { } |
3464 | \& static void io_cb (ev::io &w, int revents) { } |
2817 | \& iow.set <io_cb> (); |
3465 | \& iow.set <io_cb> (); |
2818 | .Ve |
3466 | .Ve |
2819 | .IP "w\->set (struct ev_loop *)" 4 |
3467 | .IP "w\->set (loop)" 4 |
2820 | .IX Item "w->set (struct ev_loop *)" |
3468 | .IX Item "w->set (loop)" |
2821 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
3469 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
2822 | do this when the watcher is inactive (and not pending either). |
3470 | do this when the watcher is inactive (and not pending either). |
2823 | .IP "w\->set ([arguments])" 4 |
3471 | .IP "w\->set ([arguments])" 4 |
2824 | .IX Item "w->set ([arguments])" |
3472 | .IX Item "w->set ([arguments])" |
2825 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same arguments. Must be |
3473 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same arguments. Must be |
… | |
… | |
2831 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
3479 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
2832 | constructor already stores the event loop. |
3480 | constructor already stores the event loop. |
2833 | .IP "w\->stop ()" 4 |
3481 | .IP "w\->stop ()" 4 |
2834 | .IX Item "w->stop ()" |
3482 | .IX Item "w->stop ()" |
2835 | Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. |
3483 | Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. |
2836 | .ie n .IP "w\->again () (""ev::timer""\fR, \f(CW""ev::periodic"" only)" 4 |
3484 | .ie n .IP "w\->again () (""ev::timer"", ""ev::periodic"" only)" 4 |
2837 | .el .IP "w\->again () (\f(CWev::timer\fR, \f(CWev::periodic\fR only)" 4 |
3485 | .el .IP "w\->again () (\f(CWev::timer\fR, \f(CWev::periodic\fR only)" 4 |
2838 | .IX Item "w->again () (ev::timer, ev::periodic only)" |
3486 | .IX Item "w->again () (ev::timer, ev::periodic only)" |
2839 | For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding |
3487 | For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding |
2840 | \&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. |
3488 | \&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. |
2841 | .ie n .IP "w\->sweep () (""ev::embed"" only)" 4 |
3489 | .ie n .IP "w\->sweep () (""ev::embed"" only)" 4 |
… | |
… | |
2886 | It can be found and installed via \s-1CPAN\s0, its homepage is at |
3534 | It can be found and installed via \s-1CPAN\s0, its homepage is at |
2887 | <http://software.schmorp.de/pkg/EV>. |
3535 | <http://software.schmorp.de/pkg/EV>. |
2888 | .IP "Python" 4 |
3536 | .IP "Python" 4 |
2889 | .IX Item "Python" |
3537 | .IX Item "Python" |
2890 | Python bindings can be found at <http://code.google.com/p/pyev/>. It |
3538 | Python bindings can be found at <http://code.google.com/p/pyev/>. It |
2891 | seems to be quite complete and well-documented. Note, however, that the |
3539 | seems to be quite complete and well-documented. |
2892 | patch they require for libev is outright dangerous as it breaks the \s-1ABI\s0 |
|
|
2893 | for everybody else, and therefore, should never be applied in an installed |
|
|
2894 | libev (if python requires an incompatible \s-1ABI\s0 then it needs to embed |
|
|
2895 | libev). |
|
|
2896 | .IP "Ruby" 4 |
3540 | .IP "Ruby" 4 |
2897 | .IX Item "Ruby" |
3541 | .IX Item "Ruby" |
2898 | Tony Arcieri has written a ruby extension that offers access to a subset |
3542 | Tony Arcieri has written a ruby extension that offers access to a subset |
2899 | of the libev \s-1API\s0 and adds file handle abstractions, asynchronous \s-1DNS\s0 and |
3543 | of the libev \s-1API\s0 and adds file handle abstractions, asynchronous \s-1DNS\s0 and |
2900 | more on top of it. It can be found via gem servers. Its homepage is at |
3544 | more on top of it. It can be found via gem servers. Its homepage is at |
2901 | <http://rev.rubyforge.org/>. |
3545 | <http://rev.rubyforge.org/>. |
|
|
3546 | .Sp |
|
|
3547 | Roger Pack reports that using the link order \f(CW\*(C`\-lws2_32 \-lmsvcrt\-ruby\-190\*(C'\fR |
|
|
3548 | makes rev work even on mingw. |
|
|
3549 | .IP "Haskell" 4 |
|
|
3550 | .IX Item "Haskell" |
|
|
3551 | A haskell binding to libev is available at |
|
|
3552 | <http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev>. |
2902 | .IP "D" 4 |
3553 | .IP "D" 4 |
2903 | .IX Item "D" |
3554 | .IX Item "D" |
2904 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
3555 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
2905 | be found at <http://proj.llucax.com.ar/wiki/evd>. |
3556 | be found at <http://proj.llucax.com.ar/wiki/evd>. |
|
|
3557 | .IP "Ocaml" 4 |
|
|
3558 | .IX Item "Ocaml" |
|
|
3559 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
|
|
3560 | <http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/>. |
|
|
3561 | .IP "Lua" 4 |
|
|
3562 | .IX Item "Lua" |
|
|
3563 | Brian Maher has written a partial interface to libev |
|
|
3564 | for lua (only \f(CW\*(C`ev_io\*(C'\fR and \f(CW\*(C`ev_timer\*(C'\fR), to be found at |
|
|
3565 | <http://github.com/brimworks/lua\-ev>. |
2906 | .SH "MACRO MAGIC" |
3566 | .SH "MACRO MAGIC" |
2907 | .IX Header "MACRO MAGIC" |
3567 | .IX Header "MACRO MAGIC" |
2908 | Libev can be compiled with a variety of options, the most fundamental |
3568 | Libev can be compiled with a variety of options, the most fundamental |
2909 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
3569 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
2910 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
3570 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
2911 | .PP |
3571 | .PP |
2912 | To make it easier to write programs that cope with either variant, the |
3572 | To make it easier to write programs that cope with either variant, the |
2913 | following macros are defined: |
3573 | following macros are defined: |
2914 | .ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4 |
3574 | .ie n .IP """EV_A"", ""EV_A_""" 4 |
2915 | .el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4 |
3575 | .el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4 |
2916 | .IX Item "EV_A, EV_A_" |
3576 | .IX Item "EV_A, EV_A_" |
2917 | This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev |
3577 | This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev |
2918 | loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument, |
3578 | loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument, |
2919 | \&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example: |
3579 | \&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example: |
… | |
… | |
2924 | \& ev_loop (EV_A_ 0); |
3584 | \& ev_loop (EV_A_ 0); |
2925 | .Ve |
3585 | .Ve |
2926 | .Sp |
3586 | .Sp |
2927 | It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope, |
3587 | It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope, |
2928 | which is often provided by the following macro. |
3588 | which is often provided by the following macro. |
2929 | .ie n .IP """EV_P""\fR, \f(CW""EV_P_""" 4 |
3589 | .ie n .IP """EV_P"", ""EV_P_""" 4 |
2930 | .el .IP "\f(CWEV_P\fR, \f(CWEV_P_\fR" 4 |
3590 | .el .IP "\f(CWEV_P\fR, \f(CWEV_P_\fR" 4 |
2931 | .IX Item "EV_P, EV_P_" |
3591 | .IX Item "EV_P, EV_P_" |
2932 | This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev |
3592 | This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev |
2933 | loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter, |
3593 | loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter, |
2934 | \&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example: |
3594 | \&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example: |
… | |
… | |
2941 | \& static void cb (EV_P_ ev_timer *w, int revents) |
3601 | \& static void cb (EV_P_ ev_timer *w, int revents) |
2942 | .Ve |
3602 | .Ve |
2943 | .Sp |
3603 | .Sp |
2944 | It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite |
3604 | It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite |
2945 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
3605 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
2946 | .ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4 |
3606 | .ie n .IP """EV_DEFAULT"", ""EV_DEFAULT_""" 4 |
2947 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
3607 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
2948 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
3608 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
2949 | Similar to the other two macros, this gives you the value of the default |
3609 | Similar to the other two macros, this gives you the value of the default |
2950 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). |
3610 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). |
2951 | .ie n .IP """EV_DEFAULT_UC""\fR, \f(CW""EV_DEFAULT_UC_""" 4 |
3611 | .ie n .IP """EV_DEFAULT_UC"", ""EV_DEFAULT_UC_""" 4 |
2952 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
3612 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
2953 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
3613 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
2954 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
3614 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
2955 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
3615 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
2956 | is undefined when the default loop has not been initialised by a previous |
3616 | is undefined when the default loop has not been initialised by a previous |
… | |
… | |
2984 | .PP |
3644 | .PP |
2985 | The goal is to enable you to just copy the necessary files into your |
3645 | The goal is to enable you to just copy the necessary files into your |
2986 | source directory without having to change even a single line in them, so |
3646 | source directory without having to change even a single line in them, so |
2987 | you can easily upgrade by simply copying (or having a checked-out copy of |
3647 | you can easily upgrade by simply copying (or having a checked-out copy of |
2988 | libev somewhere in your source tree). |
3648 | libev somewhere in your source tree). |
2989 | .Sh "\s-1FILESETS\s0" |
3649 | .SS "\s-1FILESETS\s0" |
2990 | .IX Subsection "FILESETS" |
3650 | .IX Subsection "FILESETS" |
2991 | Depending on what features you need you need to include one or more sets of files |
3651 | Depending on what features you need you need to include one or more sets of files |
2992 | in your application. |
3652 | in your application. |
2993 | .PP |
3653 | .PP |
2994 | \fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR |
3654 | \fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR |
… | |
… | |
3012 | \& #define EV_STANDALONE 1 |
3672 | \& #define EV_STANDALONE 1 |
3013 | \& #include "ev.h" |
3673 | \& #include "ev.h" |
3014 | .Ve |
3674 | .Ve |
3015 | .PP |
3675 | .PP |
3016 | Both header files and implementation files can be compiled with a \*(C+ |
3676 | Both header files and implementation files can be compiled with a \*(C+ |
3017 | compiler (at least, thats a stated goal, and breakage will be treated |
3677 | compiler (at least, that's a stated goal, and breakage will be treated |
3018 | as a bug). |
3678 | as a bug). |
3019 | .PP |
3679 | .PP |
3020 | You need the following files in your source tree, or in a directory |
3680 | You need the following files in your source tree, or in a directory |
3021 | in your include path (e.g. in libev/ when using \-Ilibev): |
3681 | in your include path (e.g. in libev/ when using \-Ilibev): |
3022 | .PP |
3682 | .PP |
… | |
… | |
3073 | For this of course you need the m4 file: |
3733 | For this of course you need the m4 file: |
3074 | .PP |
3734 | .PP |
3075 | .Vb 1 |
3735 | .Vb 1 |
3076 | \& libev.m4 |
3736 | \& libev.m4 |
3077 | .Ve |
3737 | .Ve |
3078 | .Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
3738 | .SS "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
3079 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
3739 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
3080 | Libev can be configured via a variety of preprocessor symbols you have to |
3740 | Libev can be configured via a variety of preprocessor symbols you have to |
3081 | define before including any of its files. The default in the absence of |
3741 | define before including any of its files. The default in the absence of |
3082 | autoconf is documented for every option. |
3742 | autoconf is documented for every option. |
3083 | .IP "\s-1EV_STANDALONE\s0" 4 |
3743 | .IP "\s-1EV_STANDALONE\s0" 4 |
… | |
… | |
3085 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
3745 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
3086 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
3746 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
3087 | implementations for some libevent functions (such as logging, which is not |
3747 | implementations for some libevent functions (such as logging, which is not |
3088 | supported). It will also not define any of the structs usually found in |
3748 | supported). It will also not define any of the structs usually found in |
3089 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
3749 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
|
|
3750 | .Sp |
|
|
3751 | In standalone mode, libev will still try to automatically deduce the |
|
|
3752 | configuration, but has to be more conservative. |
3090 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
3753 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
3091 | .IX Item "EV_USE_MONOTONIC" |
3754 | .IX Item "EV_USE_MONOTONIC" |
3092 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
3755 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
3093 | monotonic clock option at both compile time and runtime. Otherwise no use |
3756 | monotonic clock option at both compile time and runtime. Otherwise no |
3094 | of the monotonic clock option will be attempted. If you enable this, you |
3757 | use of the monotonic clock option will be attempted. If you enable this, |
3095 | usually have to link against librt or something similar. Enabling it when |
3758 | you usually have to link against librt or something similar. Enabling it |
3096 | the functionality isn't available is safe, though, although you have |
3759 | when the functionality isn't available is safe, though, although you have |
3097 | to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR |
3760 | to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR |
3098 | function is hiding in (often \fI\-lrt\fR). |
3761 | function is hiding in (often \fI\-lrt\fR). See also \f(CW\*(C`EV_USE_CLOCK_SYSCALL\*(C'\fR. |
3099 | .IP "\s-1EV_USE_REALTIME\s0" 4 |
3762 | .IP "\s-1EV_USE_REALTIME\s0" 4 |
3100 | .IX Item "EV_USE_REALTIME" |
3763 | .IX Item "EV_USE_REALTIME" |
3101 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
3764 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
3102 | real-time clock option at compile time (and assume its availability at |
3765 | real-time clock option at compile time (and assume its availability |
3103 | runtime if successful). Otherwise no use of the real-time clock option will |
3766 | at runtime if successful). Otherwise no use of the real-time clock |
3104 | be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get |
3767 | option will be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR |
3105 | (CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See the |
3768 | by \f(CW\*(C`clock_get (CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect |
3106 | note about libraries in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though. |
3769 | correctness. See the note about libraries in the description of |
|
|
3770 | \&\f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though. Defaults to the opposite value of |
|
|
3771 | \&\f(CW\*(C`EV_USE_CLOCK_SYSCALL\*(C'\fR. |
|
|
3772 | .IP "\s-1EV_USE_CLOCK_SYSCALL\s0" 4 |
|
|
3773 | .IX Item "EV_USE_CLOCK_SYSCALL" |
|
|
3774 | If defined to be \f(CW1\fR, libev will try to use a direct syscall instead |
|
|
3775 | of calling the system-provided \f(CW\*(C`clock_gettime\*(C'\fR function. This option |
|
|
3776 | exists because on GNU/Linux, \f(CW\*(C`clock_gettime\*(C'\fR is in \f(CW\*(C`librt\*(C'\fR, but \f(CW\*(C`librt\*(C'\fR |
|
|
3777 | unconditionally pulls in \f(CW\*(C`libpthread\*(C'\fR, slowing down single-threaded |
|
|
3778 | programs needlessly. Using a direct syscall is slightly slower (in |
|
|
3779 | theory), because no optimised vdso implementation can be used, but avoids |
|
|
3780 | the pthread dependency. Defaults to \f(CW1\fR on GNU/Linux with glibc 2.x or |
|
|
3781 | higher, as it simplifies linking (no need for \f(CW\*(C`\-lrt\*(C'\fR). |
3107 | .IP "\s-1EV_USE_NANOSLEEP\s0" 4 |
3782 | .IP "\s-1EV_USE_NANOSLEEP\s0" 4 |
3108 | .IX Item "EV_USE_NANOSLEEP" |
3783 | .IX Item "EV_USE_NANOSLEEP" |
3109 | If defined to be \f(CW1\fR, libev will assume that \f(CW\*(C`nanosleep ()\*(C'\fR is available |
3784 | If defined to be \f(CW1\fR, libev will assume that \f(CW\*(C`nanosleep ()\*(C'\fR is available |
3110 | and will use it for delays. Otherwise it will use \f(CW\*(C`select ()\*(C'\fR. |
3785 | and will use it for delays. Otherwise it will use \f(CW\*(C`select ()\*(C'\fR. |
3111 | .IP "\s-1EV_USE_EVENTFD\s0" 4 |
3786 | .IP "\s-1EV_USE_EVENTFD\s0" 4 |
… | |
… | |
3123 | will not be compiled in. |
3798 | will not be compiled in. |
3124 | .IP "\s-1EV_SELECT_USE_FD_SET\s0" 4 |
3799 | .IP "\s-1EV_SELECT_USE_FD_SET\s0" 4 |
3125 | .IX Item "EV_SELECT_USE_FD_SET" |
3800 | .IX Item "EV_SELECT_USE_FD_SET" |
3126 | If defined to \f(CW1\fR, then the select backend will use the system \f(CW\*(C`fd_set\*(C'\fR |
3801 | If defined to \f(CW1\fR, then the select backend will use the system \f(CW\*(C`fd_set\*(C'\fR |
3127 | structure. This is useful if libev doesn't compile due to a missing |
3802 | structure. This is useful if libev doesn't compile due to a missing |
3128 | \&\f(CW\*(C`NFDBITS\*(C'\fR or \f(CW\*(C`fd_mask\*(C'\fR definition or it mis-guesses the bitset layout on |
3803 | \&\f(CW\*(C`NFDBITS\*(C'\fR or \f(CW\*(C`fd_mask\*(C'\fR definition or it mis-guesses the bitset layout |
3129 | exotic systems. This usually limits the range of file descriptors to some |
3804 | on exotic systems. This usually limits the range of file descriptors to |
3130 | low limit such as 1024 or might have other limitations (winsocket only |
3805 | some low limit such as 1024 or might have other limitations (winsocket |
3131 | allows 64 sockets). The \f(CW\*(C`FD_SETSIZE\*(C'\fR macro, set before compilation, might |
3806 | only allows 64 sockets). The \f(CW\*(C`FD_SETSIZE\*(C'\fR macro, set before compilation, |
3132 | influence the size of the \f(CW\*(C`fd_set\*(C'\fR used. |
3807 | configures the maximum size of the \f(CW\*(C`fd_set\*(C'\fR. |
3133 | .IP "\s-1EV_SELECT_IS_WINSOCKET\s0" 4 |
3808 | .IP "\s-1EV_SELECT_IS_WINSOCKET\s0" 4 |
3134 | .IX Item "EV_SELECT_IS_WINSOCKET" |
3809 | .IX Item "EV_SELECT_IS_WINSOCKET" |
3135 | When defined to \f(CW1\fR, the select backend will assume that |
3810 | When defined to \f(CW1\fR, the select backend will assume that |
3136 | select/socket/connect etc. don't understand file descriptors but |
3811 | select/socket/connect etc. don't understand file descriptors but |
3137 | wants osf handles on win32 (this is the case when the select to |
3812 | wants osf handles on win32 (this is the case when the select to |
3138 | be used is the winsock select). This means that it will call |
3813 | be used is the winsock select). This means that it will call |
3139 | \&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise, |
3814 | \&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise, |
3140 | it is assumed that all these functions actually work on fds, even |
3815 | it is assumed that all these functions actually work on fds, even |
3141 | on win32. Should not be defined on non\-win32 platforms. |
3816 | on win32. Should not be defined on non\-win32 platforms. |
3142 | .IP "\s-1EV_FD_TO_WIN32_HANDLE\s0" 4 |
3817 | .IP "\s-1EV_FD_TO_WIN32_HANDLE\s0(fd)" 4 |
3143 | .IX Item "EV_FD_TO_WIN32_HANDLE" |
3818 | .IX Item "EV_FD_TO_WIN32_HANDLE(fd)" |
3144 | If \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR is enabled, then libev needs a way to map |
3819 | If \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR is enabled, then libev needs a way to map |
3145 | file descriptors to socket handles. When not defining this symbol (the |
3820 | file descriptors to socket handles. When not defining this symbol (the |
3146 | default), then libev will call \f(CW\*(C`_get_osfhandle\*(C'\fR, which is usually |
3821 | default), then libev will call \f(CW\*(C`_get_osfhandle\*(C'\fR, which is usually |
3147 | correct. In some cases, programs use their own file descriptor management, |
3822 | correct. In some cases, programs use their own file descriptor management, |
3148 | in which case they can provide this function to map fds to socket handles. |
3823 | in which case they can provide this function to map fds to socket handles. |
|
|
3824 | .IP "\s-1EV_WIN32_HANDLE_TO_FD\s0(handle)" 4 |
|
|
3825 | .IX Item "EV_WIN32_HANDLE_TO_FD(handle)" |
|
|
3826 | If \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR then libev maps handles to file descriptors |
|
|
3827 | using the standard \f(CW\*(C`_open_osfhandle\*(C'\fR function. For programs implementing |
|
|
3828 | their own fd to handle mapping, overwriting this function makes it easier |
|
|
3829 | to do so. This can be done by defining this macro to an appropriate value. |
|
|
3830 | .IP "\s-1EV_WIN32_CLOSE_FD\s0(fd)" 4 |
|
|
3831 | .IX Item "EV_WIN32_CLOSE_FD(fd)" |
|
|
3832 | If programs implement their own fd to handle mapping on win32, then this |
|
|
3833 | macro can be used to override the \f(CW\*(C`close\*(C'\fR function, useful to unregister |
|
|
3834 | file descriptors again. Note that the replacement function has to close |
|
|
3835 | the underlying \s-1OS\s0 handle. |
3149 | .IP "\s-1EV_USE_POLL\s0" 4 |
3836 | .IP "\s-1EV_USE_POLL\s0" 4 |
3150 | .IX Item "EV_USE_POLL" |
3837 | .IX Item "EV_USE_POLL" |
3151 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
3838 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
3152 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
3839 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
3153 | takes precedence over select. |
3840 | takes precedence over select. |
… | |
… | |
3267 | If undefined or defined to be \f(CW1\fR, then async watchers are supported. If |
3954 | If undefined or defined to be \f(CW1\fR, then async watchers are supported. If |
3268 | defined to be \f(CW0\fR, then they are not. |
3955 | defined to be \f(CW0\fR, then they are not. |
3269 | .IP "\s-1EV_MINIMAL\s0" 4 |
3956 | .IP "\s-1EV_MINIMAL\s0" 4 |
3270 | .IX Item "EV_MINIMAL" |
3957 | .IX Item "EV_MINIMAL" |
3271 | If you need to shave off some kilobytes of code at the expense of some |
3958 | If you need to shave off some kilobytes of code at the expense of some |
3272 | speed, define this symbol to \f(CW1\fR. Currently this is used to override some |
3959 | speed (but with the full \s-1API\s0), define this symbol to \f(CW1\fR. Currently this |
3273 | inlining decisions, saves roughly 30% code size on amd64. It also selects a |
3960 | is used to override some inlining decisions, saves roughly 30% code size |
3274 | much smaller 2\-heap for timer management over the default 4\-heap. |
3961 | on amd64. It also selects a much smaller 2\-heap for timer management over |
|
|
3962 | the default 4\-heap. |
|
|
3963 | .Sp |
|
|
3964 | You can save even more by disabling watcher types you do not need |
|
|
3965 | and setting \f(CW\*(C`EV_MAXPRI\*(C'\fR == \f(CW\*(C`EV_MINPRI\*(C'\fR. Also, disabling \f(CW\*(C`assert\*(C'\fR |
|
|
3966 | (\f(CW\*(C`\-DNDEBUG\*(C'\fR) will usually reduce code size a lot. |
|
|
3967 | .Sp |
|
|
3968 | Defining \f(CW\*(C`EV_MINIMAL\*(C'\fR to \f(CW2\fR will additionally reduce the core \s-1API\s0 to |
|
|
3969 | provide a bare-bones event library. See \f(CW\*(C`ev.h\*(C'\fR for details on what parts |
|
|
3970 | of the \s-1API\s0 are still available, and do not complain if this subset changes |
|
|
3971 | over time. |
|
|
3972 | .IP "\s-1EV_NSIG\s0" 4 |
|
|
3973 | .IX Item "EV_NSIG" |
|
|
3974 | The highest supported signal number, +1 (or, the number of |
|
|
3975 | signals): Normally, libev tries to deduce the maximum number of signals |
|
|
3976 | automatically, but sometimes this fails, in which case it can be |
|
|
3977 | specified. Also, using a lower number than detected (\f(CW32\fR should be |
|
|
3978 | good for about any system in existance) can save some memory, as libev |
|
|
3979 | statically allocates some 12\-24 bytes per signal number. |
3275 | .IP "\s-1EV_PID_HASHSIZE\s0" 4 |
3980 | .IP "\s-1EV_PID_HASHSIZE\s0" 4 |
3276 | .IX Item "EV_PID_HASHSIZE" |
3981 | .IX Item "EV_PID_HASHSIZE" |
3277 | \&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by |
3982 | \&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by |
3278 | pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more |
3983 | pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more |
3279 | than enough. If you need to manage thousands of children you might want to |
3984 | than enough. If you need to manage thousands of children you might want to |
… | |
… | |
3343 | and the way callbacks are invoked and set. Must expand to a struct member |
4048 | and the way callbacks are invoked and set. Must expand to a struct member |
3344 | definition and a statement, respectively. See the \fIev.h\fR header file for |
4049 | definition and a statement, respectively. See the \fIev.h\fR header file for |
3345 | their default definitions. One possible use for overriding these is to |
4050 | their default definitions. One possible use for overriding these is to |
3346 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
4051 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
3347 | method calls instead of plain function calls in \*(C+. |
4052 | method calls instead of plain function calls in \*(C+. |
3348 | .Sh "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" |
4053 | .SS "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" |
3349 | .IX Subsection "EXPORTED API SYMBOLS" |
4054 | .IX Subsection "EXPORTED API SYMBOLS" |
3350 | If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of |
4055 | If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of |
3351 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
4056 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
3352 | all public symbols, one per line: |
4057 | all public symbols, one per line: |
3353 | .PP |
4058 | .PP |
… | |
… | |
3373 | \& #define ev_backend myprefix_ev_backend |
4078 | \& #define ev_backend myprefix_ev_backend |
3374 | \& #define ev_check_start myprefix_ev_check_start |
4079 | \& #define ev_check_start myprefix_ev_check_start |
3375 | \& #define ev_check_stop myprefix_ev_check_stop |
4080 | \& #define ev_check_stop myprefix_ev_check_stop |
3376 | \& ... |
4081 | \& ... |
3377 | .Ve |
4082 | .Ve |
3378 | .Sh "\s-1EXAMPLES\s0" |
4083 | .SS "\s-1EXAMPLES\s0" |
3379 | .IX Subsection "EXAMPLES" |
4084 | .IX Subsection "EXAMPLES" |
3380 | For a real-world example of a program the includes libev |
4085 | For a real-world example of a program the includes libev |
3381 | verbatim, you can have a look at the \s-1EV\s0 perl module |
4086 | verbatim, you can have a look at the \s-1EV\s0 perl module |
3382 | (<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
4087 | (<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
3383 | the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public |
4088 | the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public |
… | |
… | |
3408 | \& #include "ev_cpp.h" |
4113 | \& #include "ev_cpp.h" |
3409 | \& #include "ev.c" |
4114 | \& #include "ev.c" |
3410 | .Ve |
4115 | .Ve |
3411 | .SH "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" |
4116 | .SH "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" |
3412 | .IX Header "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" |
4117 | .IX Header "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" |
3413 | .Sh "\s-1THREADS\s0 \s-1AND\s0 \s-1COROUTINES\s0" |
4118 | .SS "\s-1THREADS\s0 \s-1AND\s0 \s-1COROUTINES\s0" |
3414 | .IX Subsection "THREADS AND COROUTINES" |
4119 | .IX Subsection "THREADS AND COROUTINES" |
3415 | \fI\s-1THREADS\s0\fR |
4120 | \fI\s-1THREADS\s0\fR |
3416 | .IX Subsection "THREADS" |
4121 | .IX Subsection "THREADS" |
3417 | .PP |
4122 | .PP |
3418 | All libev functions are reentrant and thread-safe unless explicitly |
4123 | All libev functions are reentrant and thread-safe unless explicitly |
… | |
… | |
3464 | An example use would be to communicate signals or other events that only |
4169 | An example use would be to communicate signals or other events that only |
3465 | work in the default loop by registering the signal watcher with the |
4170 | work in the default loop by registering the signal watcher with the |
3466 | default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop |
4171 | default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop |
3467 | watcher callback into the event loop interested in the signal. |
4172 | watcher callback into the event loop interested in the signal. |
3468 | .PP |
4173 | .PP |
|
|
4174 | \s-1THREAD\s0 \s-1LOCKING\s0 \s-1EXAMPLE\s0 |
|
|
4175 | .IX Subsection "THREAD LOCKING EXAMPLE" |
|
|
4176 | .PP |
|
|
4177 | Here is a fictitious example of how to run an event loop in a different |
|
|
4178 | thread than where callbacks are being invoked and watchers are |
|
|
4179 | created/added/removed. |
|
|
4180 | .PP |
|
|
4181 | For a real-world example, see the \f(CW\*(C`EV::Loop::Async\*(C'\fR perl module, |
|
|
4182 | which uses exactly this technique (which is suited for many high-level |
|
|
4183 | languages). |
|
|
4184 | .PP |
|
|
4185 | The example uses a pthread mutex to protect the loop data, a condition |
|
|
4186 | variable to wait for callback invocations, an async watcher to notify the |
|
|
4187 | event loop thread and an unspecified mechanism to wake up the main thread. |
|
|
4188 | .PP |
|
|
4189 | First, you need to associate some data with the event loop: |
|
|
4190 | .PP |
|
|
4191 | .Vb 6 |
|
|
4192 | \& typedef struct { |
|
|
4193 | \& mutex_t lock; /* global loop lock */ |
|
|
4194 | \& ev_async async_w; |
|
|
4195 | \& thread_t tid; |
|
|
4196 | \& cond_t invoke_cv; |
|
|
4197 | \& } userdata; |
|
|
4198 | \& |
|
|
4199 | \& void prepare_loop (EV_P) |
|
|
4200 | \& { |
|
|
4201 | \& // for simplicity, we use a static userdata struct. |
|
|
4202 | \& static userdata u; |
|
|
4203 | \& |
|
|
4204 | \& ev_async_init (&u\->async_w, async_cb); |
|
|
4205 | \& ev_async_start (EV_A_ &u\->async_w); |
|
|
4206 | \& |
|
|
4207 | \& pthread_mutex_init (&u\->lock, 0); |
|
|
4208 | \& pthread_cond_init (&u\->invoke_cv, 0); |
|
|
4209 | \& |
|
|
4210 | \& // now associate this with the loop |
|
|
4211 | \& ev_set_userdata (EV_A_ u); |
|
|
4212 | \& ev_set_invoke_pending_cb (EV_A_ l_invoke); |
|
|
4213 | \& ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
|
|
4214 | \& |
|
|
4215 | \& // then create the thread running ev_loop |
|
|
4216 | \& pthread_create (&u\->tid, 0, l_run, EV_A); |
|
|
4217 | \& } |
|
|
4218 | .Ve |
|
|
4219 | .PP |
|
|
4220 | The callback for the \f(CW\*(C`ev_async\*(C'\fR watcher does nothing: the watcher is used |
|
|
4221 | solely to wake up the event loop so it takes notice of any new watchers |
|
|
4222 | that might have been added: |
|
|
4223 | .PP |
|
|
4224 | .Vb 5 |
|
|
4225 | \& static void |
|
|
4226 | \& async_cb (EV_P_ ev_async *w, int revents) |
|
|
4227 | \& { |
|
|
4228 | \& // just used for the side effects |
|
|
4229 | \& } |
|
|
4230 | .Ve |
|
|
4231 | .PP |
|
|
4232 | The \f(CW\*(C`l_release\*(C'\fR and \f(CW\*(C`l_acquire\*(C'\fR callbacks simply unlock/lock the mutex |
|
|
4233 | protecting the loop data, respectively. |
|
|
4234 | .PP |
|
|
4235 | .Vb 6 |
|
|
4236 | \& static void |
|
|
4237 | \& l_release (EV_P) |
|
|
4238 | \& { |
|
|
4239 | \& userdata *u = ev_userdata (EV_A); |
|
|
4240 | \& pthread_mutex_unlock (&u\->lock); |
|
|
4241 | \& } |
|
|
4242 | \& |
|
|
4243 | \& static void |
|
|
4244 | \& l_acquire (EV_P) |
|
|
4245 | \& { |
|
|
4246 | \& userdata *u = ev_userdata (EV_A); |
|
|
4247 | \& pthread_mutex_lock (&u\->lock); |
|
|
4248 | \& } |
|
|
4249 | .Ve |
|
|
4250 | .PP |
|
|
4251 | The event loop thread first acquires the mutex, and then jumps straight |
|
|
4252 | into \f(CW\*(C`ev_loop\*(C'\fR: |
|
|
4253 | .PP |
|
|
4254 | .Vb 4 |
|
|
4255 | \& void * |
|
|
4256 | \& l_run (void *thr_arg) |
|
|
4257 | \& { |
|
|
4258 | \& struct ev_loop *loop = (struct ev_loop *)thr_arg; |
|
|
4259 | \& |
|
|
4260 | \& l_acquire (EV_A); |
|
|
4261 | \& pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
|
|
4262 | \& ev_loop (EV_A_ 0); |
|
|
4263 | \& l_release (EV_A); |
|
|
4264 | \& |
|
|
4265 | \& return 0; |
|
|
4266 | \& } |
|
|
4267 | .Ve |
|
|
4268 | .PP |
|
|
4269 | Instead of invoking all pending watchers, the \f(CW\*(C`l_invoke\*(C'\fR callback will |
|
|
4270 | signal the main thread via some unspecified mechanism (signals? pipe |
|
|
4271 | writes? \f(CW\*(C`Async::Interrupt\*(C'\fR?) and then waits until all pending watchers |
|
|
4272 | have been called (in a while loop because a) spurious wakeups are possible |
|
|
4273 | and b) skipping inter-thread-communication when there are no pending |
|
|
4274 | watchers is very beneficial): |
|
|
4275 | .PP |
|
|
4276 | .Vb 4 |
|
|
4277 | \& static void |
|
|
4278 | \& l_invoke (EV_P) |
|
|
4279 | \& { |
|
|
4280 | \& userdata *u = ev_userdata (EV_A); |
|
|
4281 | \& |
|
|
4282 | \& while (ev_pending_count (EV_A)) |
|
|
4283 | \& { |
|
|
4284 | \& wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
|
|
4285 | \& pthread_cond_wait (&u\->invoke_cv, &u\->lock); |
|
|
4286 | \& } |
|
|
4287 | \& } |
|
|
4288 | .Ve |
|
|
4289 | .PP |
|
|
4290 | Now, whenever the main thread gets told to invoke pending watchers, it |
|
|
4291 | will grab the lock, call \f(CW\*(C`ev_invoke_pending\*(C'\fR and then signal the loop |
|
|
4292 | thread to continue: |
|
|
4293 | .PP |
|
|
4294 | .Vb 4 |
|
|
4295 | \& static void |
|
|
4296 | \& real_invoke_pending (EV_P) |
|
|
4297 | \& { |
|
|
4298 | \& userdata *u = ev_userdata (EV_A); |
|
|
4299 | \& |
|
|
4300 | \& pthread_mutex_lock (&u\->lock); |
|
|
4301 | \& ev_invoke_pending (EV_A); |
|
|
4302 | \& pthread_cond_signal (&u\->invoke_cv); |
|
|
4303 | \& pthread_mutex_unlock (&u\->lock); |
|
|
4304 | \& } |
|
|
4305 | .Ve |
|
|
4306 | .PP |
|
|
4307 | Whenever you want to start/stop a watcher or do other modifications to an |
|
|
4308 | event loop, you will now have to lock: |
|
|
4309 | .PP |
|
|
4310 | .Vb 2 |
|
|
4311 | \& ev_timer timeout_watcher; |
|
|
4312 | \& userdata *u = ev_userdata (EV_A); |
|
|
4313 | \& |
|
|
4314 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
|
|
4315 | \& |
|
|
4316 | \& pthread_mutex_lock (&u\->lock); |
|
|
4317 | \& ev_timer_start (EV_A_ &timeout_watcher); |
|
|
4318 | \& ev_async_send (EV_A_ &u\->async_w); |
|
|
4319 | \& pthread_mutex_unlock (&u\->lock); |
|
|
4320 | .Ve |
|
|
4321 | .PP |
|
|
4322 | Note that sending the \f(CW\*(C`ev_async\*(C'\fR watcher is required because otherwise |
|
|
4323 | an event loop currently blocking in the kernel will have no knowledge |
|
|
4324 | about the newly added timer. By waking up the loop it will pick up any new |
|
|
4325 | watchers in the next event loop iteration. |
|
|
4326 | .PP |
3469 | \fI\s-1COROUTINES\s0\fR |
4327 | \fI\s-1COROUTINES\s0\fR |
3470 | .IX Subsection "COROUTINES" |
4328 | .IX Subsection "COROUTINES" |
3471 | .PP |
4329 | .PP |
3472 | Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): |
4330 | Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): |
3473 | libev fully supports nesting calls to its functions from different |
4331 | libev fully supports nesting calls to its functions from different |
3474 | coroutines (e.g. you can call \f(CW\*(C`ev_loop\*(C'\fR on the same loop from two |
4332 | coroutines (e.g. you can call \f(CW\*(C`ev_loop\*(C'\fR on the same loop from two |
3475 | different coroutines, and switch freely between both coroutines running the |
4333 | different coroutines, and switch freely between both coroutines running |
3476 | loop, as long as you don't confuse yourself). The only exception is that |
4334 | the loop, as long as you don't confuse yourself). The only exception is |
3477 | you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
4335 | that you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
3478 | .PP |
4336 | .PP |
3479 | Care has been taken to ensure that libev does not keep local state inside |
4337 | Care has been taken to ensure that libev does not keep local state inside |
3480 | \&\f(CW\*(C`ev_loop\*(C'\fR, and other calls do not usually allow for coroutine switches as |
4338 | \&\f(CW\*(C`ev_loop\*(C'\fR, and other calls do not usually allow for coroutine switches as |
3481 | they do not clal any callbacks. |
4339 | they do not call any callbacks. |
3482 | .Sh "\s-1COMPILER\s0 \s-1WARNINGS\s0" |
4340 | .SS "\s-1COMPILER\s0 \s-1WARNINGS\s0" |
3483 | .IX Subsection "COMPILER WARNINGS" |
4341 | .IX Subsection "COMPILER WARNINGS" |
3484 | Depending on your compiler and compiler settings, you might get no or a |
4342 | Depending on your compiler and compiler settings, you might get no or a |
3485 | lot of warnings when compiling libev code. Some people are apparently |
4343 | lot of warnings when compiling libev code. Some people are apparently |
3486 | scared by this. |
4344 | scared by this. |
3487 | .PP |
4345 | .PP |
… | |
… | |
3504 | While libev is written to generate as few warnings as possible, |
4362 | While libev is written to generate as few warnings as possible, |
3505 | \&\*(L"warn-free\*(R" code is not a goal, and it is recommended not to build libev |
4363 | \&\*(L"warn-free\*(R" code is not a goal, and it is recommended not to build libev |
3506 | with any compiler warnings enabled unless you are prepared to cope with |
4364 | with any compiler warnings enabled unless you are prepared to cope with |
3507 | them (e.g. by ignoring them). Remember that warnings are just that: |
4365 | them (e.g. by ignoring them). Remember that warnings are just that: |
3508 | warnings, not errors, or proof of bugs. |
4366 | warnings, not errors, or proof of bugs. |
3509 | .Sh "\s-1VALGRIND\s0" |
4367 | .SS "\s-1VALGRIND\s0" |
3510 | .IX Subsection "VALGRIND" |
4368 | .IX Subsection "VALGRIND" |
3511 | Valgrind has a special section here because it is a popular tool that is |
4369 | Valgrind has a special section here because it is a popular tool that is |
3512 | highly useful. Unfortunately, valgrind reports are very hard to interpret. |
4370 | highly useful. Unfortunately, valgrind reports are very hard to interpret. |
3513 | .PP |
4371 | .PP |
3514 | If you think you found a bug (memory leak, uninitialised data access etc.) |
4372 | If you think you found a bug (memory leak, uninitialised data access etc.) |
… | |
… | |
3519 | \& ==2274== possibly lost: 0 bytes in 0 blocks. |
4377 | \& ==2274== possibly lost: 0 bytes in 0 blocks. |
3520 | \& ==2274== still reachable: 256 bytes in 1 blocks. |
4378 | \& ==2274== still reachable: 256 bytes in 1 blocks. |
3521 | .Ve |
4379 | .Ve |
3522 | .PP |
4380 | .PP |
3523 | Then there is no memory leak, just as memory accounted to global variables |
4381 | Then there is no memory leak, just as memory accounted to global variables |
3524 | is not a memleak \- the memory is still being refernced, and didn't leak. |
4382 | is not a memleak \- the memory is still being referenced, and didn't leak. |
3525 | .PP |
4383 | .PP |
3526 | Similarly, under some circumstances, valgrind might report kernel bugs |
4384 | Similarly, under some circumstances, valgrind might report kernel bugs |
3527 | as if it were a bug in libev (e.g. in realloc or in the poll backend, |
4385 | as if it were a bug in libev (e.g. in realloc or in the poll backend, |
3528 | although an acceptable workaround has been found here), or it might be |
4386 | although an acceptable workaround has been found here), or it might be |
3529 | confused. |
4387 | confused. |
… | |
… | |
3539 | .PP |
4397 | .PP |
3540 | If you need, for some reason, empty reports from valgrind for your project |
4398 | If you need, for some reason, empty reports from valgrind for your project |
3541 | I suggest using suppression lists. |
4399 | I suggest using suppression lists. |
3542 | .SH "PORTABILITY NOTES" |
4400 | .SH "PORTABILITY NOTES" |
3543 | .IX Header "PORTABILITY NOTES" |
4401 | .IX Header "PORTABILITY NOTES" |
3544 | .Sh "\s-1WIN32\s0 \s-1PLATFORM\s0 \s-1LIMITATIONS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" |
4402 | .SS "\s-1WIN32\s0 \s-1PLATFORM\s0 \s-1LIMITATIONS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" |
3545 | .IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" |
4403 | .IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" |
3546 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
4404 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
3547 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
4405 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
3548 | model. Libev still offers limited functionality on this platform in |
4406 | model. Libev still offers limited functionality on this platform in |
3549 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
4407 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
… | |
… | |
3556 | way (note also that glib is the slowest event library known to man). |
4414 | way (note also that glib is the slowest event library known to man). |
3557 | .PP |
4415 | .PP |
3558 | There is no supported compilation method available on windows except |
4416 | There is no supported compilation method available on windows except |
3559 | embedding it into other applications. |
4417 | embedding it into other applications. |
3560 | .PP |
4418 | .PP |
|
|
4419 | Sensible signal handling is officially unsupported by Microsoft \- libev |
|
|
4420 | tries its best, but under most conditions, signals will simply not work. |
|
|
4421 | .PP |
3561 | Not a libev limitation but worth mentioning: windows apparently doesn't |
4422 | Not a libev limitation but worth mentioning: windows apparently doesn't |
3562 | accept large writes: instead of resulting in a partial write, windows will |
4423 | accept large writes: instead of resulting in a partial write, windows will |
3563 | either accept everything or return \f(CW\*(C`ENOBUFS\*(C'\fR if the buffer is too large, |
4424 | either accept everything or return \f(CW\*(C`ENOBUFS\*(C'\fR if the buffer is too large, |
3564 | so make sure you only write small amounts into your sockets (less than a |
4425 | so make sure you only write small amounts into your sockets (less than a |
3565 | megabyte seems safe, but this apparently depends on the amount of memory |
4426 | megabyte seems safe, but this apparently depends on the amount of memory |
… | |
… | |
3569 | the abysmal performance of winsockets, using a large number of sockets |
4430 | the abysmal performance of winsockets, using a large number of sockets |
3570 | is not recommended (and not reasonable). If your program needs to use |
4431 | is not recommended (and not reasonable). If your program needs to use |
3571 | more than a hundred or so sockets, then likely it needs to use a totally |
4432 | more than a hundred or so sockets, then likely it needs to use a totally |
3572 | different implementation for windows, as libev offers the \s-1POSIX\s0 readiness |
4433 | different implementation for windows, as libev offers the \s-1POSIX\s0 readiness |
3573 | notification model, which cannot be implemented efficiently on windows |
4434 | notification model, which cannot be implemented efficiently on windows |
3574 | (Microsoft monopoly games). |
4435 | (due to Microsoft monopoly games). |
3575 | .PP |
4436 | .PP |
3576 | A typical way to use libev under windows is to embed it (see the embedding |
4437 | A typical way to use libev under windows is to embed it (see the embedding |
3577 | section for details) and use the following \fIevwrap.h\fR header file instead |
4438 | section for details) and use the following \fIevwrap.h\fR header file instead |
3578 | of \fIev.h\fR: |
4439 | of \fIev.h\fR: |
3579 | .PP |
4440 | .PP |
… | |
… | |
3617 | .Sp |
4478 | .Sp |
3618 | Early versions of winsocket's select only supported waiting for a maximum |
4479 | Early versions of winsocket's select only supported waiting for a maximum |
3619 | of \f(CW64\fR handles (probably owning to the fact that all windows kernels |
4480 | of \f(CW64\fR handles (probably owning to the fact that all windows kernels |
3620 | can only wait for \f(CW64\fR things at the same time internally; Microsoft |
4481 | can only wait for \f(CW64\fR things at the same time internally; Microsoft |
3621 | recommends spawning a chain of threads and wait for 63 handles and the |
4482 | recommends spawning a chain of threads and wait for 63 handles and the |
3622 | previous thread in each. Great). |
4483 | previous thread in each. Sounds great!). |
3623 | .Sp |
4484 | .Sp |
3624 | Newer versions support more handles, but you need to define \f(CW\*(C`FD_SETSIZE\*(C'\fR |
4485 | Newer versions support more handles, but you need to define \f(CW\*(C`FD_SETSIZE\*(C'\fR |
3625 | to some high number (e.g. \f(CW2048\fR) before compiling the winsocket select |
4486 | to some high number (e.g. \f(CW2048\fR) before compiling the winsocket select |
3626 | call (which might be in libev or elsewhere, for example, perl does its own |
4487 | call (which might be in libev or elsewhere, for example, perl and many |
3627 | select emulation on windows). |
4488 | other interpreters do their own select emulation on windows). |
3628 | .Sp |
4489 | .Sp |
3629 | Another limit is the number of file descriptors in the Microsoft runtime |
4490 | Another limit is the number of file descriptors in the Microsoft runtime |
3630 | libraries, which by default is \f(CW64\fR (there must be a hidden \fI64\fR fetish |
4491 | libraries, which by default is \f(CW64\fR (there must be a hidden \fI64\fR |
3631 | or something like this inside Microsoft). You can increase this by calling |
4492 | fetish or something like this inside Microsoft). You can increase this |
3632 | \&\f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR (another |
4493 | by calling \f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR |
3633 | arbitrary limit), but is broken in many versions of the Microsoft runtime |
4494 | (another arbitrary limit), but is broken in many versions of the Microsoft |
3634 | libraries. |
|
|
3635 | .Sp |
|
|
3636 | This might get you to about \f(CW512\fR or \f(CW2048\fR sockets (depending on |
4495 | runtime libraries. This might get you to about \f(CW512\fR or \f(CW2048\fR sockets |
3637 | windows version and/or the phase of the moon). To get more, you need to |
4496 | (depending on windows version and/or the phase of the moon). To get more, |
3638 | wrap all I/O functions and provide your own fd management, but the cost of |
4497 | you need to wrap all I/O functions and provide your own fd management, but |
3639 | calling select (O(nA\*^X)) will likely make this unworkable. |
4498 | the cost of calling select (O(nA\*^X)) will likely make this unworkable. |
3640 | .Sh "\s-1PORTABILITY\s0 \s-1REQUIREMENTS\s0" |
4499 | .SS "\s-1PORTABILITY\s0 \s-1REQUIREMENTS\s0" |
3641 | .IX Subsection "PORTABILITY REQUIREMENTS" |
4500 | .IX Subsection "PORTABILITY REQUIREMENTS" |
3642 | In addition to a working ISO-C implementation and of course the |
4501 | In addition to a working ISO-C implementation and of course the |
3643 | backend-specific APIs, libev relies on a few additional extensions: |
4502 | backend-specific APIs, libev relies on a few additional extensions: |
3644 | .ie n .IP """void (*)(ev_watcher_type *, int revents)""\fR must have compatible calling conventions regardless of \f(CW""ev_watcher_type *""." 4 |
4503 | .ie n .IP """void (*)(ev_watcher_type *, int revents)"" must have compatible calling conventions regardless of ""ev_watcher_type *""." 4 |
3645 | .el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4 |
4504 | .el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4 |
3646 | .IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *." |
4505 | .IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *." |
3647 | Libev assumes not only that all watcher pointers have the same internal |
4506 | Libev assumes not only that all watcher pointers have the same internal |
3648 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO\s0 C for example), but it also |
4507 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO\s0 C for example), but it also |
3649 | assumes that the same (machine) code can be used to call any watcher |
4508 | assumes that the same (machine) code can be used to call any watcher |
… | |
… | |
3681 | .el .IP "\f(CWdouble\fR must hold a time value in seconds with enough accuracy" 4 |
4540 | .el .IP "\f(CWdouble\fR must hold a time value in seconds with enough accuracy" 4 |
3682 | .IX Item "double must hold a time value in seconds with enough accuracy" |
4541 | .IX Item "double must hold a time value in seconds with enough accuracy" |
3683 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
4542 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
3684 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
4543 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
3685 | enough for at least into the year 4000. This requirement is fulfilled by |
4544 | enough for at least into the year 4000. This requirement is fulfilled by |
3686 | implementations implementing \s-1IEEE\s0 754 (basically all existing ones). |
4545 | implementations implementing \s-1IEEE\s0 754, which is basically all existing |
|
|
4546 | ones. With \s-1IEEE\s0 754 doubles, you get microsecond accuracy until at least |
|
|
4547 | 2200. |
3687 | .PP |
4548 | .PP |
3688 | If you know of other additional requirements drop me a note. |
4549 | If you know of other additional requirements drop me a note. |
3689 | .SH "ALGORITHMIC COMPLEXITIES" |
4550 | .SH "ALGORITHMIC COMPLEXITIES" |
3690 | .IX Header "ALGORITHMIC COMPLEXITIES" |
4551 | .IX Header "ALGORITHMIC COMPLEXITIES" |
3691 | In this section the complexities of (many of) the algorithms used inside |
4552 | In this section the complexities of (many of) the algorithms used inside |
… | |
… | |
3747 | .IX Item "Processing signals: O(max_signal_number)" |
4608 | .IX Item "Processing signals: O(max_signal_number)" |
3748 | .PD |
4609 | .PD |
3749 | Sending involves a system call \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
4610 | Sending involves a system call \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
3750 | calls in the current loop iteration. Checking for async and signal events |
4611 | calls in the current loop iteration. Checking for async and signal events |
3751 | involves iterating over all running async watchers or all signal numbers. |
4612 | involves iterating over all running async watchers or all signal numbers. |
|
|
4613 | .SH "GLOSSARY" |
|
|
4614 | .IX Header "GLOSSARY" |
|
|
4615 | .IP "active" 4 |
|
|
4616 | .IX Item "active" |
|
|
4617 | A watcher is active as long as it has been started (has been attached to |
|
|
4618 | an event loop) but not yet stopped (disassociated from the event loop). |
|
|
4619 | .IP "application" 4 |
|
|
4620 | .IX Item "application" |
|
|
4621 | In this document, an application is whatever is using libev. |
|
|
4622 | .IP "callback" 4 |
|
|
4623 | .IX Item "callback" |
|
|
4624 | The address of a function that is called when some event has been |
|
|
4625 | detected. Callbacks are being passed the event loop, the watcher that |
|
|
4626 | received the event, and the actual event bitset. |
|
|
4627 | .IP "callback invocation" 4 |
|
|
4628 | .IX Item "callback invocation" |
|
|
4629 | The act of calling the callback associated with a watcher. |
|
|
4630 | .IP "event" 4 |
|
|
4631 | .IX Item "event" |
|
|
4632 | A change of state of some external event, such as data now being available |
|
|
4633 | for reading on a file descriptor, time having passed or simply not having |
|
|
4634 | any other events happening anymore. |
|
|
4635 | .Sp |
|
|
4636 | In libev, events are represented as single bits (such as \f(CW\*(C`EV_READ\*(C'\fR or |
|
|
4637 | \&\f(CW\*(C`EV_TIMEOUT\*(C'\fR). |
|
|
4638 | .IP "event library" 4 |
|
|
4639 | .IX Item "event library" |
|
|
4640 | A software package implementing an event model and loop. |
|
|
4641 | .IP "event loop" 4 |
|
|
4642 | .IX Item "event loop" |
|
|
4643 | An entity that handles and processes external events and converts them |
|
|
4644 | into callback invocations. |
|
|
4645 | .IP "event model" 4 |
|
|
4646 | .IX Item "event model" |
|
|
4647 | The model used to describe how an event loop handles and processes |
|
|
4648 | watchers and events. |
|
|
4649 | .IP "pending" 4 |
|
|
4650 | .IX Item "pending" |
|
|
4651 | A watcher is pending as soon as the corresponding event has been detected, |
|
|
4652 | and stops being pending as soon as the watcher will be invoked or its |
|
|
4653 | pending status is explicitly cleared by the application. |
|
|
4654 | .Sp |
|
|
4655 | A watcher can be pending, but not active. Stopping a watcher also clears |
|
|
4656 | its pending status. |
|
|
4657 | .IP "real time" 4 |
|
|
4658 | .IX Item "real time" |
|
|
4659 | The physical time that is observed. It is apparently strictly monotonic :) |
|
|
4660 | .IP "wall-clock time" 4 |
|
|
4661 | .IX Item "wall-clock time" |
|
|
4662 | The time and date as shown on clocks. Unlike real time, it can actually |
|
|
4663 | be wrong and jump forwards and backwards, e.g. when the you adjust your |
|
|
4664 | clock. |
|
|
4665 | .IP "watcher" 4 |
|
|
4666 | .IX Item "watcher" |
|
|
4667 | A data structure that describes interest in certain events. Watchers need |
|
|
4668 | to be started (attached to an event loop) before they can receive events. |
|
|
4669 | .IP "watcher invocation" 4 |
|
|
4670 | .IX Item "watcher invocation" |
|
|
4671 | The act of calling the callback associated with a watcher. |
3752 | .SH "AUTHOR" |
4672 | .SH "AUTHOR" |
3753 | .IX Header "AUTHOR" |
4673 | .IX Header "AUTHOR" |
3754 | Marc Lehmann <libev@schmorp.de>. |
4674 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |