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130.\} 130.\}
131.rm #[ #] #H #V #F C 131.rm #[ #] #H #V #F C
132.\" ======================================================================== 132.\" ========================================================================
133.\" 133.\"
134.IX Title "LIBEV 3" 134.IX Title "LIBEV 3"
135.TH LIBEV 3 "2008-05-11" "libev-3.33" "libev - high perfromance full featured event loop" 135.TH LIBEV 3 "2008-06-09" "libev-3.42" "libev - high performance full featured event loop"
136.\" For nroff, turn off justification. Always turn off hyphenation; it makes 136.\" For nroff, turn off justification. Always turn off hyphenation; it makes
137.\" way too many mistakes in technical documents. 137.\" way too many mistakes in technical documents.
138.if n .ad l 138.if n .ad l
139.nh 139.nh
140.SH "NAME" 140.SH "NAME"
141libev \- a high performance full\-featured event loop written in C 141libev \- a high performance full\-featured event loop written in C
142.SH "SYNOPSIS" 142.SH "SYNOPSIS"
143.IX Header "SYNOPSIS" 143.IX Header "SYNOPSIS"
144.Vb 1 144.Vb 1
145\& #include <ev.h> 145\& #include <ev.h>
146.Ve 146.Ve
147.Sh "\s-1EXAMPLE\s0 \s-1PROGRAM\s0" 147.Sh "\s-1EXAMPLE\s0 \s-1PROGRAM\s0"
148.IX Subsection "EXAMPLE PROGRAM" 148.IX Subsection "EXAMPLE PROGRAM"
149.Vb 2 149.Vb 2
150\& // a single header file is required 150\& // a single header file is required
151\& #include <ev.h> 151\& #include <ev.h>
152\& 152\&
153\& // every watcher type has its own typedef\*(Aqd struct 153\& // every watcher type has its own typedef\*(Aqd struct
154\& // with the name ev_<type> 154\& // with the name ev_<type>
155\& ev_io stdin_watcher; 155\& ev_io stdin_watcher;
156\& ev_timer timeout_watcher; 156\& ev_timer timeout_watcher;
157\& 157\&
158\& // all watcher callbacks have a similar signature 158\& // all watcher callbacks have a similar signature
159\& // this callback is called when data is readable on stdin 159\& // this callback is called when data is readable on stdin
160\& static void 160\& static void
161\& stdin_cb (EV_P_ struct ev_io *w, int revents) 161\& stdin_cb (EV_P_ struct ev_io *w, int revents)
162\& { 162\& {
163\& puts ("stdin ready"); 163\& puts ("stdin ready");
164\& // for one\-shot events, one must manually stop the watcher 164\& // for one\-shot events, one must manually stop the watcher
165\& // with its corresponding stop function. 165\& // with its corresponding stop function.
166\& ev_io_stop (EV_A_ w); 166\& ev_io_stop (EV_A_ w);
167\& 167\&
168\& // this causes all nested ev_loop\*(Aqs to stop iterating 168\& // this causes all nested ev_loop\*(Aqs to stop iterating
169\& ev_unloop (EV_A_ EVUNLOOP_ALL); 169\& ev_unloop (EV_A_ EVUNLOOP_ALL);
170\& } 170\& }
171\& 171\&
172\& // another callback, this time for a time\-out 172\& // another callback, this time for a time\-out
173\& static void 173\& static void
174\& timeout_cb (EV_P_ struct ev_timer *w, int revents) 174\& timeout_cb (EV_P_ struct ev_timer *w, int revents)
175\& { 175\& {
176\& puts ("timeout"); 176\& puts ("timeout");
177\& // this causes the innermost ev_loop to stop iterating 177\& // this causes the innermost ev_loop to stop iterating
178\& ev_unloop (EV_A_ EVUNLOOP_ONE); 178\& ev_unloop (EV_A_ EVUNLOOP_ONE);
179\& } 179\& }
180\& 180\&
181\& int 181\& int
182\& main (void) 182\& main (void)
183\& { 183\& {
184\& // use the default event loop unless you have special needs 184\& // use the default event loop unless you have special needs
185\& struct ev_loop *loop = ev_default_loop (0); 185\& struct ev_loop *loop = ev_default_loop (0);
186\& 186\&
187\& // initialise an io watcher, then start it 187\& // initialise an io watcher, then start it
188\& // this one will watch for stdin to become readable 188\& // this one will watch for stdin to become readable
189\& ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); 189\& ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
190\& ev_io_start (loop, &stdin_watcher); 190\& ev_io_start (loop, &stdin_watcher);
191\& 191\&
192\& // initialise a timer watcher, then start it 192\& // initialise a timer watcher, then start it
193\& // simple non\-repeating 5.5 second timeout 193\& // simple non\-repeating 5.5 second timeout
194\& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); 194\& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
195\& ev_timer_start (loop, &timeout_watcher); 195\& ev_timer_start (loop, &timeout_watcher);
196\& 196\&
197\& // now wait for events to arrive 197\& // now wait for events to arrive
198\& ev_loop (loop, 0); 198\& ev_loop (loop, 0);
199\& 199\&
200\& // unloop was called, so exit 200\& // unloop was called, so exit
201\& return 0; 201\& return 0;
202\& } 202\& }
203.Ve 203.Ve
204.SH "DESCRIPTION" 204.SH "DESCRIPTION"
205.IX Header "DESCRIPTION" 205.IX Header "DESCRIPTION"
206The newest version of this document is also available as an html-formatted 206The newest version of this document is also available as an html-formatted
207web page you might find easier to navigate when reading it for the first 207web page you might find easier to navigate when reading it for the first
249Libev represents time as a single floating point number, representing the 249Libev represents time as a single floating point number, representing the
250(fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near 250(fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near
251the beginning of 1970, details are complicated, don't ask). This type is 251the beginning of 1970, details are complicated, don't ask). This type is
252called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually aliases 252called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually aliases
253to the \f(CW\*(C`double\*(C'\fR type in C, and when you need to do any calculations on 253to the \f(CW\*(C`double\*(C'\fR type in C, and when you need to do any calculations on
254it, you should treat it as some floatingpoint value. Unlike the name 254it, you should treat it as some floating point value. Unlike the name
255component \f(CW\*(C`stamp\*(C'\fR might indicate, it is also used for time differences 255component \f(CW\*(C`stamp\*(C'\fR might indicate, it is also used for time differences
256throughout libev. 256throughout libev.
257.SH "ERROR HANDLING"
258.IX Header "ERROR HANDLING"
259Libev knows three classes of errors: operating system errors, usage errors
260and internal errors (bugs).
261.PP
262When libev catches an operating system error it cannot handle (for example
263a system call indicating a condition libev cannot fix), it calls the callback
264set via \f(CW\*(C`ev_set_syserr_cb\*(C'\fR, which is supposed to fix the problem or
265abort. The default is to print a diagnostic message and to call \f(CW\*(C`abort
266()\*(C'\fR.
267.PP
268When libev detects a usage error such as a negative timer interval, then
269it will print a diagnostic message and abort (via the \f(CW\*(C`assert\*(C'\fR mechanism,
270so \f(CW\*(C`NDEBUG\*(C'\fR will disable this checking): these are programming errors in
271the libev caller and need to be fixed there.
272.PP
273Libev also has a few internal error-checking \f(CW\*(C`assert\*(C'\fRions, and also has
274extensive consistency checking code. These do not trigger under normal
275circumstances, as they indicate either a bug in libev or worse.
257.SH "GLOBAL FUNCTIONS" 276.SH "GLOBAL FUNCTIONS"
258.IX Header "GLOBAL FUNCTIONS" 277.IX Header "GLOBAL FUNCTIONS"
259These functions can be called anytime, even before initialising the 278These functions can be called anytime, even before initialising the
260library in any way. 279library in any way.
261.IP "ev_tstamp ev_time ()" 4 280.IP "ev_tstamp ev_time ()" 4
265you actually want to know. 284you actually want to know.
266.IP "ev_sleep (ev_tstamp interval)" 4 285.IP "ev_sleep (ev_tstamp interval)" 4
267.IX Item "ev_sleep (ev_tstamp interval)" 286.IX Item "ev_sleep (ev_tstamp interval)"
268Sleep for the given interval: The current thread will be blocked until 287Sleep for the given interval: The current thread will be blocked until
269either it is interrupted or the given time interval has passed. Basically 288either it is interrupted or the given time interval has passed. Basically
270this is a subsecond-resolution \f(CW\*(C`sleep ()\*(C'\fR. 289this is a sub-second-resolution \f(CW\*(C`sleep ()\*(C'\fR.
271.IP "int ev_version_major ()" 4 290.IP "int ev_version_major ()" 4
272.IX Item "int ev_version_major ()" 291.IX Item "int ev_version_major ()"
273.PD 0 292.PD 0
274.IP "int ev_version_minor ()" 4 293.IP "int ev_version_minor ()" 4
275.IX Item "int ev_version_minor ()" 294.IX Item "int ev_version_minor ()"
290.Sp 309.Sp
291Example: Make sure we haven't accidentally been linked against the wrong 310Example: Make sure we haven't accidentally been linked against the wrong
292version. 311version.
293.Sp 312.Sp
294.Vb 3 313.Vb 3
295\& assert (("libev version mismatch", 314\& assert (("libev version mismatch",
296\& ev_version_major () == EV_VERSION_MAJOR 315\& ev_version_major () == EV_VERSION_MAJOR
297\& && ev_version_minor () >= EV_VERSION_MINOR)); 316\& && ev_version_minor () >= EV_VERSION_MINOR));
298.Ve 317.Ve
299.IP "unsigned int ev_supported_backends ()" 4 318.IP "unsigned int ev_supported_backends ()" 4
300.IX Item "unsigned int ev_supported_backends ()" 319.IX Item "unsigned int ev_supported_backends ()"
301Return the set of all backends (i.e. their corresponding \f(CW\*(C`EV_BACKEND_*\*(C'\fR 320Return the set of all backends (i.e. their corresponding \f(CW\*(C`EV_BACKEND_*\*(C'\fR
302value) compiled into this binary of libev (independent of their 321value) compiled into this binary of libev (independent of their
305.Sp 324.Sp
306Example: make sure we have the epoll method, because yeah this is cool and 325Example: make sure we have the epoll method, because yeah this is cool and
307a must have and can we have a torrent of it please!!!11 326a must have and can we have a torrent of it please!!!11
308.Sp 327.Sp
309.Vb 2 328.Vb 2
310\& assert (("sorry, no epoll, no sex", 329\& assert (("sorry, no epoll, no sex",
311\& ev_supported_backends () & EVBACKEND_EPOLL)); 330\& ev_supported_backends () & EVBACKEND_EPOLL));
312.Ve 331.Ve
313.IP "unsigned int ev_recommended_backends ()" 4 332.IP "unsigned int ev_recommended_backends ()" 4
314.IX Item "unsigned int ev_recommended_backends ()" 333.IX Item "unsigned int ev_recommended_backends ()"
315Return the set of all backends compiled into this binary of libev and also 334Return the set of all backends compiled into this binary of libev and also
316recommended for this platform. This set is often smaller than the one 335recommended for this platform. This set is often smaller than the one
317returned by \f(CW\*(C`ev_supported_backends\*(C'\fR, as for example kqueue is broken on 336returned by \f(CW\*(C`ev_supported_backends\*(C'\fR, as for example kqueue is broken on
318most BSDs and will not be autodetected unless you explicitly request it 337most BSDs and will not be auto-detected unless you explicitly request it
319(assuming you know what you are doing). This is the set of backends that 338(assuming you know what you are doing). This is the set of backends that
320libev will probe for if you specify no backends explicitly. 339libev will probe for if you specify no backends explicitly.
321.IP "unsigned int ev_embeddable_backends ()" 4 340.IP "unsigned int ev_embeddable_backends ()" 4
322.IX Item "unsigned int ev_embeddable_backends ()" 341.IX Item "unsigned int ev_embeddable_backends ()"
323Returns the set of backends that are embeddable in other event loops. This 342Returns the set of backends that are embeddable in other event loops. This
364\& ... 383\& ...
365\& ev_set_allocator (persistent_realloc); 384\& ev_set_allocator (persistent_realloc);
366.Ve 385.Ve
367.IP "ev_set_syserr_cb (void (*cb)(const char *msg));" 4 386.IP "ev_set_syserr_cb (void (*cb)(const char *msg));" 4
368.IX Item "ev_set_syserr_cb (void (*cb)(const char *msg));" 387.IX Item "ev_set_syserr_cb (void (*cb)(const char *msg));"
369Set the callback function to call on a retryable syscall error (such 388Set the callback function to call on a retryable system call error (such
370as failed select, poll, epoll_wait). The message is a printable string 389as failed select, poll, epoll_wait). The message is a printable string
371indicating the system call or subsystem causing the problem. If this 390indicating the system call or subsystem causing the problem. If this
372callback is set, then libev will expect it to remedy the sitution, no 391callback is set, then libev will expect it to remedy the situation, no
373matter what, when it returns. That is, libev will generally retry the 392matter what, when it returns. That is, libev will generally retry the
374requested operation, or, if the condition doesn't go away, do bad stuff 393requested operation, or, if the condition doesn't go away, do bad stuff
375(such as abort). 394(such as abort).
376.Sp 395.Sp
377Example: This is basically the same thing that libev does internally, too. 396Example: This is basically the same thing that libev does internally, too.
406from multiple threads, you have to lock (note also that this is unlikely, 425from multiple threads, you have to lock (note also that this is unlikely,
407as loops cannot bes hared easily between threads anyway). 426as loops cannot bes hared easily between threads anyway).
408.Sp 427.Sp
409The default loop is the only loop that can handle \f(CW\*(C`ev_signal\*(C'\fR and 428The default loop is the only loop that can handle \f(CW\*(C`ev_signal\*(C'\fR and
410\&\f(CW\*(C`ev_child\*(C'\fR watchers, and to do this, it always registers a handler 429\&\f(CW\*(C`ev_child\*(C'\fR watchers, and to do this, it always registers a handler
411for \f(CW\*(C`SIGCHLD\*(C'\fR. If this is a problem for your app you can either 430for \f(CW\*(C`SIGCHLD\*(C'\fR. If this is a problem for your application you can either
412create a dynamic loop with \f(CW\*(C`ev_loop_new\*(C'\fR that doesn't do that, or you 431create a dynamic loop with \f(CW\*(C`ev_loop_new\*(C'\fR that doesn't do that, or you
413can simply overwrite the \f(CW\*(C`SIGCHLD\*(C'\fR signal handler \fIafter\fR calling 432can simply overwrite the \f(CW\*(C`SIGCHLD\*(C'\fR signal handler \fIafter\fR calling
414\&\f(CW\*(C`ev_default_init\*(C'\fR. 433\&\f(CW\*(C`ev_default_init\*(C'\fR.
415.Sp 434.Sp
416The flags argument can be used to specify special behaviour or specific 435The flags argument can be used to specify special behaviour or specific
424The default flags value. Use this if you have no clue (it's the right 443The default flags value. Use this if you have no clue (it's the right
425thing, believe me). 444thing, believe me).
426.ie n .IP """EVFLAG_NOENV""" 4 445.ie n .IP """EVFLAG_NOENV""" 4
427.el .IP "\f(CWEVFLAG_NOENV\fR" 4 446.el .IP "\f(CWEVFLAG_NOENV\fR" 4
428.IX Item "EVFLAG_NOENV" 447.IX Item "EVFLAG_NOENV"
429If this flag bit is ored into the flag value (or the program runs setuid 448If this flag bit is or'ed into the flag value (or the program runs setuid
430or setgid) then libev will \fInot\fR look at the environment variable 449or setgid) then libev will \fInot\fR look at the environment variable
431\&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will 450\&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will
432override the flags completely if it is found in the environment. This is 451override the flags completely if it is found in the environment. This is
433useful to try out specific backends to test their performance, or to work 452useful to try out specific backends to test their performance, or to work
434around bugs. 453around bugs.
441.Sp 460.Sp
442This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, 461This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop,
443and thus this might slow down your event loop if you do a lot of loop 462and thus this might slow down your event loop if you do a lot of loop
444iterations and little real work, but is usually not noticeable (on my 463iterations and little real work, but is usually not noticeable (on my
445GNU/Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence 464GNU/Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence
446without a syscall and thus \fIvery\fR fast, but my GNU/Linux system also has 465without a system call and thus \fIvery\fR fast, but my GNU/Linux system also has
447\&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster). 466\&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster).
448.Sp 467.Sp
449The big advantage of this flag is that you can forget about fork (and 468The big advantage of this flag is that you can forget about fork (and
450forget about forgetting to tell libev about forking) when you use this 469forget about forgetting to tell libev about forking) when you use this
451flag. 470flag.
452.Sp 471.Sp
453This flag setting cannot be overriden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR 472This flag setting cannot be overridden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR
454environment variable. 473environment variable.
455.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 474.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4
456.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 475.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4
457.IX Item "EVBACKEND_SELECT (value 1, portable select backend)" 476.IX Item "EVBACKEND_SELECT (value 1, portable select backend)"
458This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as 477This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as
460but if that fails, expect a fairly low limit on the number of fds when 479but if that fails, expect a fairly low limit on the number of fds when
461using this backend. It doesn't scale too well (O(highest_fd)), but its 480using this backend. It doesn't scale too well (O(highest_fd)), but its
462usually the fastest backend for a low number of (low-numbered :) fds. 481usually the fastest backend for a low number of (low-numbered :) fds.
463.Sp 482.Sp
464To get good performance out of this backend you need a high amount of 483To get good performance out of this backend you need a high amount of
465parallelity (most of the file descriptors should be busy). If you are 484parallelism (most of the file descriptors should be busy). If you are
466writing a server, you should \f(CW\*(C`accept ()\*(C'\fR in a loop to accept as many 485writing a server, you should \f(CW\*(C`accept ()\*(C'\fR in a loop to accept as many
467connections as possible during one iteration. You might also want to have 486connections as possible during one iteration. You might also want to have
468a look at \f(CW\*(C`ev_set_io_collect_interval ()\*(C'\fR to increase the amount of 487a look at \f(CW\*(C`ev_set_io_collect_interval ()\*(C'\fR to increase the amount of
469readyness notifications you get per iteration. 488readiness notifications you get per iteration.
470.ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 489.ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4
471.el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4 490.el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4
472.IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)" 491.IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)"
473And this is your standard \fIpoll\fR\|(2) backend. It's more complicated 492And this is your standard \fIpoll\fR\|(2) backend. It's more complicated
474than select, but handles sparse fds better and has no artificial 493than select, but handles sparse fds better and has no artificial
482For few fds, this backend is a bit little slower than poll and select, 501For few fds, this backend is a bit little slower than poll and select,
483but it scales phenomenally better. While poll and select usually scale 502but it scales phenomenally better. While poll and select usually scale
484like O(total_fds) where n is the total number of fds (or the highest fd), 503like O(total_fds) where n is the total number of fds (or the highest fd),
485epoll scales either O(1) or O(active_fds). The epoll design has a number 504epoll scales either O(1) or O(active_fds). The epoll design has a number
486of shortcomings, such as silently dropping events in some hard-to-detect 505of shortcomings, such as silently dropping events in some hard-to-detect
487cases and requiring a syscall per fd change, no fork support and bad 506cases and requiring a system call per fd change, no fork support and bad
488support for dup. 507support for dup.
489.Sp 508.Sp
490While stopping, setting and starting an I/O watcher in the same iteration 509While stopping, setting and starting an I/O watcher in the same iteration
491will result in some caching, there is still a syscall per such incident 510will result in some caching, there is still a system call per such incident
492(because the fd could point to a different file description now), so its 511(because the fd could point to a different file description now), so its
493best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors might not work 512best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors might not work
494very well if you register events for both fds. 513very well if you register events for both fds.
495.Sp 514.Sp
496Please note that epoll sometimes generates spurious notifications, so you 515Please note that epoll sometimes generates spurious notifications, so you
499.Sp 518.Sp
500Best performance from this backend is achieved by not unregistering all 519Best performance from this backend is achieved by not unregistering all
501watchers for a file descriptor until it has been closed, if possible, i.e. 520watchers for a file descriptor until it has been closed, if possible, i.e.
502keep at least one watcher active per fd at all times. 521keep at least one watcher active per fd at all times.
503.Sp 522.Sp
504While nominally embeddeble in other event loops, this feature is broken in 523While nominally embeddable in other event loops, this feature is broken in
505all kernel versions tested so far. 524all kernel versions tested so far.
506.ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 525.ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4
507.el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 526.el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4
508.IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" 527.IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)"
509Kqueue deserves special mention, as at the time of this writing, it 528Kqueue deserves special mention, as at the time of this writing, it
510was broken on all BSDs except NetBSD (usually it doesn't work reliably 529was broken on all BSDs except NetBSD (usually it doesn't work reliably
511with anything but sockets and pipes, except on Darwin, where of course 530with anything but sockets and pipes, except on Darwin, where of course
512it's completely useless). For this reason it's not being \*(L"autodetected\*(R" 531it's completely useless). For this reason it's not being \*(L"auto-detected\*(R"
513unless you explicitly specify it explicitly in the flags (i.e. using 532unless you explicitly specify it explicitly in the flags (i.e. using
514\&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR) or libev was compiled on a known-to-be-good (\-enough) 533\&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR) or libev was compiled on a known-to-be-good (\-enough)
515system like NetBSD. 534system like NetBSD.
516.Sp 535.Sp
517You still can embed kqueue into a normal poll or select backend and use it 536You still can embed kqueue into a normal poll or select backend and use it
519the target platform). See \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. 538the target platform). See \f(CW\*(C`ev_embed\*(C'\fR watchers for more info.
520.Sp 539.Sp
521It scales in the same way as the epoll backend, but the interface to the 540It scales in the same way as the epoll backend, but the interface to the
522kernel is more efficient (which says nothing about its actual speed, of 541kernel is more efficient (which says nothing about its actual speed, of
523course). While stopping, setting and starting an I/O watcher does never 542course). While stopping, setting and starting an I/O watcher does never
524cause an extra syscall as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to 543cause an extra system call as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to
525two event changes per incident, support for \f(CW\*(C`fork ()\*(C'\fR is very bad and it 544two event changes per incident, support for \f(CW\*(C`fork ()\*(C'\fR is very bad and it
526drops fds silently in similarly hard-to-detect cases. 545drops fds silently in similarly hard-to-detect cases.
527.Sp 546.Sp
528This backend usually performs well under most conditions. 547This backend usually performs well under most conditions.
529.Sp 548.Sp
544.el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 563.el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4
545.IX Item "EVBACKEND_PORT (value 32, Solaris 10)" 564.IX Item "EVBACKEND_PORT (value 32, Solaris 10)"
546This uses the Solaris 10 event port mechanism. As with everything on Solaris, 565This uses the Solaris 10 event port mechanism. As with everything on Solaris,
547it's really slow, but it still scales very well (O(active_fds)). 566it's really slow, but it still scales very well (O(active_fds)).
548.Sp 567.Sp
549Please note that solaris event ports can deliver a lot of spurious 568Please note that Solaris event ports can deliver a lot of spurious
550notifications, so you need to use non-blocking I/O or other means to avoid 569notifications, so you need to use non-blocking I/O or other means to avoid
551blocking when no data (or space) is available. 570blocking when no data (or space) is available.
552.Sp 571.Sp
553While this backend scales well, it requires one system call per active 572While this backend scales well, it requires one system call per active
554file descriptor per loop iteration. For small and medium numbers of file 573file descriptor per loop iteration. For small and medium numbers of file
555descriptors a \*(L"slow\*(R" \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR backend 574descriptors a \*(L"slow\*(R" \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR backend
556might perform better. 575might perform better.
557.Sp 576.Sp
558On the positive side, ignoring the spurious readyness notifications, this 577On the positive side, ignoring the spurious readiness notifications, this
559backend actually performed to specification in all tests and is fully 578backend actually performed to specification in all tests and is fully
560embeddable, which is a rare feat among the OS-specific backends. 579embeddable, which is a rare feat among the OS-specific backends.
561.ie n .IP """EVBACKEND_ALL""" 4 580.ie n .IP """EVBACKEND_ALL""" 4
562.el .IP "\f(CWEVBACKEND_ALL\fR" 4 581.el .IP "\f(CWEVBACKEND_ALL\fR" 4
563.IX Item "EVBACKEND_ALL" 582.IX Item "EVBACKEND_ALL"
567.Sp 586.Sp
568It is definitely not recommended to use this flag. 587It is definitely not recommended to use this flag.
569.RE 588.RE
570.RS 4 589.RS 4
571.Sp 590.Sp
572If one or more of these are ored into the flags value, then only these 591If one or more of these are or'ed into the flags value, then only these
573backends will be tried (in the reverse order as listed here). If none are 592backends will be tried (in the reverse order as listed here). If none are
574specified, all backends in \f(CW\*(C`ev_recommended_backends ()\*(C'\fR will be tried. 593specified, all backends in \f(CW\*(C`ev_recommended_backends ()\*(C'\fR will be tried.
575.Sp 594.Sp
576The most typical usage is like this: 595The most typical usage is like this:
577.Sp 596.Sp
578.Vb 2 597.Vb 2
579\& if (!ev_default_loop (0)) 598\& if (!ev_default_loop (0))
580\& fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); 599\& fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
581.Ve 600.Ve
582.Sp 601.Sp
583Restrict libev to the select and poll backends, and do not allow 602Restrict libev to the select and poll backends, and do not allow
584environment settings to be taken into account: 603environment settings to be taken into account:
585.Sp 604.Sp
586.Vb 1 605.Vb 1
587\& ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); 606\& ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
588.Ve 607.Ve
589.Sp 608.Sp
590Use whatever libev has to offer, but make sure that kqueue is used if 609Use whatever libev has to offer, but make sure that kqueue is used if
591available (warning, breaks stuff, best use only with your own private 610available (warning, breaks stuff, best use only with your own private
592event loop and only if you know the \s-1OS\s0 supports your types of fds): 611event loop and only if you know the \s-1OS\s0 supports your types of fds):
593.Sp 612.Sp
594.Vb 1 613.Vb 1
595\& ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); 614\& ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
596.Ve 615.Ve
597.RE 616.RE
598.IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4 617.IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4
599.IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" 618.IX Item "struct ev_loop *ev_loop_new (unsigned int flags)"
600Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is 619Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is
607default loop in the \*(L"main\*(R" or \*(L"initial\*(R" thread. 626default loop in the \*(L"main\*(R" or \*(L"initial\*(R" thread.
608.Sp 627.Sp
609Example: Try to create a event loop that uses epoll and nothing else. 628Example: Try to create a event loop that uses epoll and nothing else.
610.Sp 629.Sp
611.Vb 3 630.Vb 3
612\& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); 631\& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
613\& if (!epoller) 632\& if (!epoller)
614\& fatal ("no epoll found here, maybe it hides under your chair"); 633\& fatal ("no epoll found here, maybe it hides under your chair");
615.Ve 634.Ve
616.IP "ev_default_destroy ()" 4 635.IP "ev_default_destroy ()" 4
617.IX Item "ev_default_destroy ()" 636.IX Item "ev_default_destroy ()"
618Destroys the default loop again (frees all memory and kernel state 637Destroys the default loop again (frees all memory and kernel state
619etc.). None of the active event watchers will be stopped in the normal 638etc.). None of the active event watchers will be stopped in the normal
620sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your 639sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your
621responsibility to either stop all watchers cleanly yoursef \fIbefore\fR 640responsibility to either stop all watchers cleanly yourself \fIbefore\fR
622calling this function, or cope with the fact afterwards (which is usually 641calling this function, or cope with the fact afterwards (which is usually
623the easiest thing, you can just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them 642the easiest thing, you can just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them
624for example). 643for example).
625.Sp 644.Sp
626Note that certain global state, such as signal state, will not be freed by 645Note that certain global state, such as signal state, will not be freed by
701A flags value of \f(CW\*(C`EVLOOP_NONBLOCK\*(C'\fR will look for new events, will handle 720A flags value of \f(CW\*(C`EVLOOP_NONBLOCK\*(C'\fR will look for new events, will handle
702those events and any outstanding ones, but will not block your process in 721those events and any outstanding ones, but will not block your process in
703case there are no events and will return after one iteration of the loop. 722case there are no events and will return after one iteration of the loop.
704.Sp 723.Sp
705A flags value of \f(CW\*(C`EVLOOP_ONESHOT\*(C'\fR will look for new events (waiting if 724A flags value of \f(CW\*(C`EVLOOP_ONESHOT\*(C'\fR will look for new events (waiting if
706neccessary) and will handle those and any outstanding ones. It will block 725necessary) and will handle those and any outstanding ones. It will block
707your process until at least one new event arrives, and will return after 726your process until at least one new event arrives, and will return after
708one iteration of the loop. This is useful if you are waiting for some 727one iteration of the loop. This is useful if you are waiting for some
709external event in conjunction with something not expressible using other 728external event in conjunction with something not expressible using other
710libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is 729libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is
711usually a better approach for this kind of thing. 730usually a better approach for this kind of thing.
777.Sp 796.Sp
778Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR 797Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR
779running when nothing else is active. 798running when nothing else is active.
780.Sp 799.Sp
781.Vb 4 800.Vb 4
782\& struct ev_signal exitsig; 801\& struct ev_signal exitsig;
783\& ev_signal_init (&exitsig, sig_cb, SIGINT); 802\& ev_signal_init (&exitsig, sig_cb, SIGINT);
784\& ev_signal_start (loop, &exitsig); 803\& ev_signal_start (loop, &exitsig);
785\& evf_unref (loop); 804\& evf_unref (loop);
786.Ve 805.Ve
787.Sp 806.Sp
788Example: For some weird reason, unregister the above signal handler again. 807Example: For some weird reason, unregister the above signal handler again.
789.Sp 808.Sp
790.Vb 2 809.Vb 2
791\& ev_ref (loop); 810\& ev_ref (loop);
792\& ev_signal_stop (loop, &exitsig); 811\& ev_signal_stop (loop, &exitsig);
793.Ve 812.Ve
794.IP "ev_set_io_collect_interval (loop, ev_tstamp interval)" 4 813.IP "ev_set_io_collect_interval (loop, ev_tstamp interval)" 4
795.IX Item "ev_set_io_collect_interval (loop, ev_tstamp interval)" 814.IX Item "ev_set_io_collect_interval (loop, ev_tstamp interval)"
796.PD 0 815.PD 0
797.IP "ev_set_timeout_collect_interval (loop, ev_tstamp interval)" 4 816.IP "ev_set_timeout_collect_interval (loop, ev_tstamp interval)" 4
821to spend more time collecting timeouts, at the expense of increased 840to spend more time collecting timeouts, at the expense of increased
822latency (the watcher callback will be called later). \f(CW\*(C`ev_io\*(C'\fR watchers 841latency (the watcher callback will be called later). \f(CW\*(C`ev_io\*(C'\fR watchers
823will not be affected. Setting this to a non-null value will not introduce 842will not be affected. Setting this to a non-null value will not introduce
824any overhead in libev. 843any overhead in libev.
825.Sp 844.Sp
826Many (busy) programs can usually benefit by setting the io collect 845Many (busy) programs can usually benefit by setting the I/O collect
827interval to a value near \f(CW0.1\fR or so, which is often enough for 846interval to a value near \f(CW0.1\fR or so, which is often enough for
828interactive servers (of course not for games), likewise for timeouts. It 847interactive servers (of course not for games), likewise for timeouts. It
829usually doesn't make much sense to set it to a lower value than \f(CW0.01\fR, 848usually doesn't make much sense to set it to a lower value than \f(CW0.01\fR,
830as this approsaches the timing granularity of most systems. 849as this approaches the timing granularity of most systems.
850.IP "ev_loop_verify (loop)" 4
851.IX Item "ev_loop_verify (loop)"
852This function only does something when \f(CW\*(C`EV_VERIFY\*(C'\fR support has been
853compiled in. It tries to go through all internal structures and checks
854them for validity. If anything is found to be inconsistent, it will print
855an error message to standard error and call \f(CW\*(C`abort ()\*(C'\fR.
856.Sp
857This can be used to catch bugs inside libev itself: under normal
858circumstances, this function will never abort as of course libev keeps its
859data structures consistent.
831.SH "ANATOMY OF A WATCHER" 860.SH "ANATOMY OF A WATCHER"
832.IX Header "ANATOMY OF A WATCHER" 861.IX Header "ANATOMY OF A WATCHER"
833A watcher is a structure that you create and register to record your 862A watcher is a structure that you create and register to record your
834interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to 863interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to
835become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that: 864become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that:
836.PP 865.PP
837.Vb 5 866.Vb 5
838\& static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) 867\& static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)
839\& { 868\& {
840\& ev_io_stop (w); 869\& ev_io_stop (w);
841\& ev_unloop (loop, EVUNLOOP_ALL); 870\& ev_unloop (loop, EVUNLOOP_ALL);
842\& } 871\& }
843\& 872\&
844\& struct ev_loop *loop = ev_default_loop (0); 873\& struct ev_loop *loop = ev_default_loop (0);
845\& struct ev_io stdin_watcher; 874\& struct ev_io stdin_watcher;
846\& ev_init (&stdin_watcher, my_cb); 875\& ev_init (&stdin_watcher, my_cb);
847\& ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); 876\& ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
848\& ev_io_start (loop, &stdin_watcher); 877\& ev_io_start (loop, &stdin_watcher);
849\& ev_loop (loop, 0); 878\& ev_loop (loop, 0);
850.Ve 879.Ve
851.PP 880.PP
852As you can see, you are responsible for allocating the memory for your 881As you can see, you are responsible for allocating the memory for your
853watcher structures (and it is usually a bad idea to do this on the stack, 882watcher structures (and it is usually a bad idea to do this on the stack,
854although this can sometimes be quite valid). 883although this can sometimes be quite valid).
855.PP 884.PP
856Each watcher structure must be initialised by a call to \f(CW\*(C`ev_init 885Each watcher structure must be initialised by a call to \f(CW\*(C`ev_init
857(watcher *, callback)\*(C'\fR, which expects a callback to be provided. This 886(watcher *, callback)\*(C'\fR, which expects a callback to be provided. This
858callback gets invoked each time the event occurs (or, in the case of io 887callback gets invoked each time the event occurs (or, in the case of I/O
859watchers, each time the event loop detects that the file descriptor given 888watchers, each time the event loop detects that the file descriptor given
860is readable and/or writable). 889is readable and/or writable).
861.PP 890.PP
862Each watcher type has its own \f(CW\*(C`ev_<type>_set (watcher *, ...)\*(C'\fR macro 891Each watcher type has its own \f(CW\*(C`ev_<type>_set (watcher *, ...)\*(C'\fR macro
863with arguments specific to this watcher type. There is also a macro 892with arguments specific to this watcher type. There is also a macro
943.IX Item "EV_ASYNC" 972.IX Item "EV_ASYNC"
944The given async watcher has been asynchronously notified (see \f(CW\*(C`ev_async\*(C'\fR). 973The given async watcher has been asynchronously notified (see \f(CW\*(C`ev_async\*(C'\fR).
945.ie n .IP """EV_ERROR""" 4 974.ie n .IP """EV_ERROR""" 4
946.el .IP "\f(CWEV_ERROR\fR" 4 975.el .IP "\f(CWEV_ERROR\fR" 4
947.IX Item "EV_ERROR" 976.IX Item "EV_ERROR"
948An unspecified error has occured, the watcher has been stopped. This might 977An unspecified error has occurred, the watcher has been stopped. This might
949happen because the watcher could not be properly started because libev 978happen because the watcher could not be properly started because libev
950ran out of memory, a file descriptor was found to be closed or any other 979ran out of memory, a file descriptor was found to be closed or any other
951problem. You best act on it by reporting the problem and somehow coping 980problem. You best act on it by reporting the problem and somehow coping
952with the watcher being stopped. 981with the watcher being stopped.
953.Sp 982.Sp
954Libev will usually signal a few \*(L"dummy\*(R" events together with an error, 983Libev will usually signal a few \*(L"dummy\*(R" events together with an error,
955for example it might indicate that a fd is readable or writable, and if 984for example it might indicate that a fd is readable or writable, and if
956your callbacks is well-written it can just attempt the operation and cope 985your callbacks is well-written it can just attempt the operation and cope
957with the error from \fIread()\fR or \fIwrite()\fR. This will not work in multithreaded 986with the error from \fIread()\fR or \fIwrite()\fR. This will not work in multi-threaded
958programs, though, so beware. 987programs, though, so beware.
959.Sh "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" 988.Sh "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0"
960.IX Subsection "GENERIC WATCHER FUNCTIONS" 989.IX Subsection "GENERIC WATCHER FUNCTIONS"
961In the following description, \f(CW\*(C`TYPE\*(C'\fR stands for the watcher type, 990In the following description, \f(CW\*(C`TYPE\*(C'\fR stands for the watcher type,
962e.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. 991e.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.
987Although some watcher types do not have type-specific arguments 1016Although some watcher types do not have type-specific arguments
988(e.g. \f(CW\*(C`ev_prepare\*(C'\fR) you still need to call its \f(CW\*(C`set\*(C'\fR macro. 1017(e.g. \f(CW\*(C`ev_prepare\*(C'\fR) you still need to call its \f(CW\*(C`set\*(C'\fR macro.
989.ie n .IP """ev_TYPE_init"" (ev_TYPE *watcher, callback, [args])" 4 1018.ie n .IP """ev_TYPE_init"" (ev_TYPE *watcher, callback, [args])" 4
990.el .IP "\f(CWev_TYPE_init\fR (ev_TYPE *watcher, callback, [args])" 4 1019.el .IP "\f(CWev_TYPE_init\fR (ev_TYPE *watcher, callback, [args])" 4
991.IX Item "ev_TYPE_init (ev_TYPE *watcher, callback, [args])" 1020.IX Item "ev_TYPE_init (ev_TYPE *watcher, callback, [args])"
992This convinience macro rolls both \f(CW\*(C`ev_init\*(C'\fR and \f(CW\*(C`ev_TYPE_set\*(C'\fR macro 1021This convenience macro rolls both \f(CW\*(C`ev_init\*(C'\fR and \f(CW\*(C`ev_TYPE_set\*(C'\fR macro
993calls into a single call. This is the most convinient method to initialise 1022calls into a single call. This is the most convenient method to initialise
994a watcher. The same limitations apply, of course. 1023a watcher. The same limitations apply, of course.
995.ie n .IP """ev_TYPE_start"" (loop *, ev_TYPE *watcher)" 4 1024.ie n .IP """ev_TYPE_start"" (loop *, ev_TYPE *watcher)" 4
996.el .IP "\f(CWev_TYPE_start\fR (loop *, ev_TYPE *watcher)" 4 1025.el .IP "\f(CWev_TYPE_start\fR (loop *, ev_TYPE *watcher)" 4
997.IX Item "ev_TYPE_start (loop *, ev_TYPE *watcher)" 1026.IX Item "ev_TYPE_start (loop *, ev_TYPE *watcher)"
998Starts (activates) the given watcher. Only active watchers will receive 1027Starts (activates) the given watcher. Only active watchers will receive
1073don't want to allocate memory and store a pointer to it in that data 1102don't want to allocate memory and store a pointer to it in that data
1074member, you can also \*(L"subclass\*(R" the watcher type and provide your own 1103member, you can also \*(L"subclass\*(R" the watcher type and provide your own
1075data: 1104data:
1076.PP 1105.PP
1077.Vb 7 1106.Vb 7
1078\& struct my_io 1107\& struct my_io
1079\& { 1108\& {
1080\& struct ev_io io; 1109\& struct ev_io io;
1081\& int otherfd; 1110\& int otherfd;
1082\& void *somedata; 1111\& void *somedata;
1083\& struct whatever *mostinteresting; 1112\& struct whatever *mostinteresting;
1084\& } 1113\& }
1085.Ve 1114.Ve
1086.PP 1115.PP
1087And since your callback will be called with a pointer to the watcher, you 1116And since your callback will be called with a pointer to the watcher, you
1088can cast it back to your own type: 1117can cast it back to your own type:
1089.PP 1118.PP
1090.Vb 5 1119.Vb 5
1091\& static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents) 1120\& static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents)
1092\& { 1121\& {
1093\& struct my_io *w = (struct my_io *)w_; 1122\& struct my_io *w = (struct my_io *)w_;
1094\& ... 1123\& ...
1095\& } 1124\& }
1096.Ve 1125.Ve
1097.PP 1126.PP
1098More interesting and less C\-conformant ways of casting your callback type 1127More interesting and less C\-conformant ways of casting your callback type
1099instead have been omitted. 1128instead have been omitted.
1100.PP 1129.PP
1101Another common scenario is having some data structure with multiple 1130Another common scenario is having some data structure with multiple
1102watchers: 1131watchers:
1103.PP 1132.PP
1104.Vb 6 1133.Vb 6
1105\& struct my_biggy 1134\& struct my_biggy
1106\& { 1135\& {
1107\& int some_data; 1136\& int some_data;
1108\& ev_timer t1; 1137\& ev_timer t1;
1109\& ev_timer t2; 1138\& ev_timer t2;
1110\& } 1139\& }
1111.Ve 1140.Ve
1112.PP 1141.PP
1113In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more complicated, 1142In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more complicated,
1114you need to use \f(CW\*(C`offsetof\*(C'\fR: 1143you need to use \f(CW\*(C`offsetof\*(C'\fR:
1115.PP 1144.PP
1116.Vb 1 1145.Vb 1
1117\& #include <stddef.h> 1146\& #include <stddef.h>
1118\& 1147\&
1119\& static void 1148\& static void
1120\& t1_cb (EV_P_ struct ev_timer *w, int revents) 1149\& t1_cb (EV_P_ struct ev_timer *w, int revents)
1121\& { 1150\& {
1122\& struct my_biggy big = (struct my_biggy * 1151\& struct my_biggy big = (struct my_biggy *
1123\& (((char *)w) \- offsetof (struct my_biggy, t1)); 1152\& (((char *)w) \- offsetof (struct my_biggy, t1));
1124\& } 1153\& }
1125\& 1154\&
1126\& static void 1155\& static void
1127\& t2_cb (EV_P_ struct ev_timer *w, int revents) 1156\& t2_cb (EV_P_ struct ev_timer *w, int revents)
1128\& { 1157\& {
1129\& struct my_biggy big = (struct my_biggy * 1158\& struct my_biggy big = (struct my_biggy *
1130\& (((char *)w) \- offsetof (struct my_biggy, t2)); 1159\& (((char *)w) \- offsetof (struct my_biggy, t2));
1131\& } 1160\& }
1132.Ve 1161.Ve
1133.SH "WATCHER TYPES" 1162.SH "WATCHER TYPES"
1134.IX Header "WATCHER TYPES" 1163.IX Header "WATCHER TYPES"
1135This section describes each watcher in detail, but will not repeat 1164This section describes each watcher in detail, but will not repeat
1136information given in the last section. Any initialisation/set macros, 1165information given in the last section. Any initialisation/set macros,
1163If you must do this, then force the use of a known-to-be-good backend 1192If you must do this, then force the use of a known-to-be-good backend
1164(at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and 1193(at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and
1165\&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR). 1194\&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR).
1166.PP 1195.PP
1167Another thing you have to watch out for is that it is quite easy to 1196Another thing you have to watch out for is that it is quite easy to
1168receive \*(L"spurious\*(R" readyness notifications, that is your callback might 1197receive \*(L"spurious\*(R" readiness notifications, that is your callback might
1169be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block 1198be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block
1170because there is no data. Not only are some backends known to create a 1199because there is no data. Not only are some backends known to create a
1171lot of those (for example solaris ports), it is very easy to get into 1200lot of those (for example Solaris ports), it is very easy to get into
1172this situation even with a relatively standard program structure. Thus 1201this situation even with a relatively standard program structure. Thus
1173it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning 1202it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning
1174\&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives. 1203\&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives.
1175.PP 1204.PP
1176If you cannot run the fd in non-blocking mode (for example you should not 1205If you cannot run the fd in non-blocking mode (for example you should not
1177play around with an Xlib connection), then you have to seperately re-test 1206play around with an Xlib connection), then you have to separately re-test
1178whether a file descriptor is really ready with a known-to-be good interface 1207whether a file descriptor is really ready with a known-to-be good interface
1179such as poll (fortunately in our Xlib example, Xlib already does this on 1208such as poll (fortunately in our Xlib example, Xlib already does this on
1180its own, so its quite safe to use). 1209its own, so its quite safe to use).
1181.PP 1210.PP
1182\fIThe special problem of disappearing file descriptors\fR 1211\fIThe special problem of disappearing file descriptors\fR
1245.PD 0 1274.PD 0
1246.IP "ev_io_set (ev_io *, int fd, int events)" 4 1275.IP "ev_io_set (ev_io *, int fd, int events)" 4
1247.IX Item "ev_io_set (ev_io *, int fd, int events)" 1276.IX Item "ev_io_set (ev_io *, int fd, int events)"
1248.PD 1277.PD
1249Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The \f(CW\*(C`fd\*(C'\fR is the file descriptor to 1278Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The \f(CW\*(C`fd\*(C'\fR is the file descriptor to
1250rceeive events for and events is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or 1279receive events for and events is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or
1251\&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR to receive the given events. 1280\&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR to receive the given events.
1252.IP "int fd [read\-only]" 4 1281.IP "int fd [read\-only]" 4
1253.IX Item "int fd [read-only]" 1282.IX Item "int fd [read-only]"
1254The file descriptor being watched. 1283The file descriptor being watched.
1255.IP "int events [read\-only]" 4 1284.IP "int events [read\-only]" 4
1262Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well 1291Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well
1263readable, but only once. Since it is likely line-buffered, you could 1292readable, but only once. Since it is likely line-buffered, you could
1264attempt to read a whole line in the callback. 1293attempt to read a whole line in the callback.
1265.PP 1294.PP
1266.Vb 6 1295.Vb 6
1267\& static void 1296\& static void
1268\& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) 1297\& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1269\& { 1298\& {
1270\& ev_io_stop (loop, w); 1299\& ev_io_stop (loop, w);
1271\& .. read from stdin here (or from w\->fd) and haqndle any I/O errors 1300\& .. read from stdin here (or from w\->fd) and haqndle any I/O errors
1272\& } 1301\& }
1273\& 1302\&
1274\& ... 1303\& ...
1275\& struct ev_loop *loop = ev_default_init (0); 1304\& struct ev_loop *loop = ev_default_init (0);
1276\& struct ev_io stdin_readable; 1305\& struct ev_io stdin_readable;
1277\& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); 1306\& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1278\& ev_io_start (loop, &stdin_readable); 1307\& ev_io_start (loop, &stdin_readable);
1279\& ev_loop (loop, 0); 1308\& ev_loop (loop, 0);
1280.Ve 1309.Ve
1281.ie n .Sh """ev_timer"" \- relative and optionally repeating timeouts" 1310.ie n .Sh """ev_timer"" \- relative and optionally repeating timeouts"
1282.el .Sh "\f(CWev_timer\fP \- relative and optionally repeating timeouts" 1311.el .Sh "\f(CWev_timer\fP \- relative and optionally repeating timeouts"
1283.IX Subsection "ev_timer - relative and optionally repeating timeouts" 1312.IX Subsection "ev_timer - relative and optionally repeating timeouts"
1284Timer watchers are simple relative timers that generate an event after a 1313Timer watchers are simple relative timers that generate an event after a
1285given time, and optionally repeating in regular intervals after that. 1314given time, and optionally repeating in regular intervals after that.
1286.PP 1315.PP
1287The timers are based on real time, that is, if you register an event that 1316The timers are based on real time, that is, if you register an event that
1288times out after an hour and you reset your system clock to last years 1317times out after an hour and you reset your system clock to January last
1289time, it will still time out after (roughly) and hour. \*(L"Roughly\*(R" because 1318year, it will still time out after (roughly) and hour. \*(L"Roughly\*(R" because
1290detecting time jumps is hard, and some inaccuracies are unavoidable (the 1319detecting time jumps is hard, and some inaccuracies are unavoidable (the
1291monotonic clock option helps a lot here). 1320monotonic clock option helps a lot here).
1292.PP 1321.PP
1293The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR 1322The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR
1294time. This is usually the right thing as this timestamp refers to the time 1323time. This is usually the right thing as this timestamp refers to the time
1298.PP 1327.PP
1299.Vb 1 1328.Vb 1
1300\& ev_timer_set (&timer, after + ev_now () \- ev_time (), 0.); 1329\& ev_timer_set (&timer, after + ev_now () \- ev_time (), 0.);
1301.Ve 1330.Ve
1302.PP 1331.PP
1303The callback is guarenteed to be invoked only when its timeout has passed, 1332The callback is guaranteed to be invoked only after its timeout has passed,
1304but if multiple timers become ready during the same loop iteration then 1333but if multiple timers become ready during the same loop iteration then
1305order of execution is undefined. 1334order of execution is undefined.
1306.PP 1335.PP
1307\fIWatcher-Specific Functions and Data Members\fR 1336\fIWatcher-Specific Functions and Data Members\fR
1308.IX Subsection "Watcher-Specific Functions and Data Members" 1337.IX Subsection "Watcher-Specific Functions and Data Members"
1310.IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 1339.IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)"
1311.PD 0 1340.PD 0
1312.IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 1341.IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4
1313.IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 1342.IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)"
1314.PD 1343.PD
1315Configure the timer to trigger after \f(CW\*(C`after\*(C'\fR seconds. If \f(CW\*(C`repeat\*(C'\fR is 1344Configure the timer to trigger after \f(CW\*(C`after\*(C'\fR seconds. If \f(CW\*(C`repeat\*(C'\fR
1316\&\f(CW0.\fR, then it will automatically be stopped. If it is positive, then the 1345is \f(CW0.\fR, then it will automatically be stopped once the timeout is
1317timer will automatically be configured to trigger again \f(CW\*(C`repeat\*(C'\fR seconds 1346reached. If it is positive, then the timer will automatically be
1318later, again, and again, until stopped manually. 1347configured to trigger again \f(CW\*(C`repeat\*(C'\fR seconds later, again, and again,
1348until stopped manually.
1319.Sp 1349.Sp
1320The timer itself will do a best-effort at avoiding drift, that is, if you 1350The timer itself will do a best-effort at avoiding drift, that is, if
1321configure a timer to trigger every 10 seconds, then it will trigger at 1351you configure a timer to trigger every 10 seconds, then it will normally
1322exactly 10 second intervals. If, however, your program cannot keep up with 1352trigger at exactly 10 second intervals. If, however, your program cannot
1323the timer (because it takes longer than those 10 seconds to do stuff) the 1353keep up with the timer (because it takes longer than those 10 seconds to
1324timer will not fire more than once per event loop iteration. 1354do stuff) the timer will not fire more than once per event loop iteration.
1325.IP "ev_timer_again (loop, ev_timer *)" 4 1355.IP "ev_timer_again (loop, ev_timer *)" 4
1326.IX Item "ev_timer_again (loop, ev_timer *)" 1356.IX Item "ev_timer_again (loop, ev_timer *)"
1327This will act as if the timer timed out and restart it again if it is 1357This will act as if the timer timed out and restart it again if it is
1328repeating. The exact semantics are: 1358repeating. The exact semantics are:
1329.Sp 1359.Sp
1330If the timer is pending, its pending status is cleared. 1360If the timer is pending, its pending status is cleared.
1331.Sp 1361.Sp
1332If the timer is started but nonrepeating, stop it (as if it timed out). 1362If the timer is started but non-repeating, stop it (as if it timed out).
1333.Sp 1363.Sp
1334If the timer is repeating, either start it if necessary (with the 1364If the timer is repeating, either start it if necessary (with the
1335\&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value. 1365\&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value.
1336.Sp 1366.Sp
1337This sounds a bit complicated, but here is a useful and typical 1367This sounds a bit complicated, but here is a useful and typical
1338example: Imagine you have a tcp connection and you want a so-called idle 1368example: Imagine you have a \s-1TCP\s0 connection and you want a so-called idle
1339timeout, that is, you want to be called when there have been, say, 60 1369timeout, that is, you want to be called when there have been, say, 60
1340seconds of inactivity on the socket. The easiest way to do this is to 1370seconds of inactivity on the socket. The easiest way to do this is to
1341configure an \f(CW\*(C`ev_timer\*(C'\fR with a \f(CW\*(C`repeat\*(C'\fR value of \f(CW60\fR and then call 1371configure an \f(CW\*(C`ev_timer\*(C'\fR with a \f(CW\*(C`repeat\*(C'\fR value of \f(CW60\fR and then call
1342\&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If 1372\&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If
1343you go into an idle state where you do not expect data to travel on the 1373you go into an idle state where you do not expect data to travel on the
1370.IX Subsection "Examples" 1400.IX Subsection "Examples"
1371.PP 1401.PP
1372Example: Create a timer that fires after 60 seconds. 1402Example: Create a timer that fires after 60 seconds.
1373.PP 1403.PP
1374.Vb 5 1404.Vb 5
1375\& static void 1405\& static void
1376\& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) 1406\& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1377\& { 1407\& {
1378\& .. one minute over, w is actually stopped right here 1408\& .. one minute over, w is actually stopped right here
1379\& } 1409\& }
1380\& 1410\&
1381\& struct ev_timer mytimer; 1411\& struct ev_timer mytimer;
1382\& ev_timer_init (&mytimer, one_minute_cb, 60., 0.); 1412\& ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
1383\& ev_timer_start (loop, &mytimer); 1413\& ev_timer_start (loop, &mytimer);
1384.Ve 1414.Ve
1385.PP 1415.PP
1386Example: Create a timeout timer that times out after 10 seconds of 1416Example: Create a timeout timer that times out after 10 seconds of
1387inactivity. 1417inactivity.
1388.PP 1418.PP
1389.Vb 5 1419.Vb 5
1390\& static void 1420\& static void
1391\& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) 1421\& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1392\& { 1422\& {
1393\& .. ten seconds without any activity 1423\& .. ten seconds without any activity
1394\& } 1424\& }
1395\& 1425\&
1396\& struct ev_timer mytimer; 1426\& struct ev_timer mytimer;
1397\& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ 1427\& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1398\& ev_timer_again (&mytimer); /* start timer */ 1428\& ev_timer_again (&mytimer); /* start timer */
1399\& ev_loop (loop, 0); 1429\& ev_loop (loop, 0);
1400\& 1430\&
1401\& // and in some piece of code that gets executed on any "activity": 1431\& // and in some piece of code that gets executed on any "activity":
1402\& // reset the timeout to start ticking again at 10 seconds 1432\& // reset the timeout to start ticking again at 10 seconds
1403\& ev_timer_again (&mytimer); 1433\& ev_timer_again (&mytimer);
1404.Ve 1434.Ve
1405.ie n .Sh """ev_periodic"" \- to cron or not to cron?" 1435.ie n .Sh """ev_periodic"" \- to cron or not to cron?"
1406.el .Sh "\f(CWev_periodic\fP \- to cron or not to cron?" 1436.el .Sh "\f(CWev_periodic\fP \- to cron or not to cron?"
1407.IX Subsection "ev_periodic - to cron or not to cron?" 1437.IX Subsection "ev_periodic - to cron or not to cron?"
1408Periodic watchers are also timers of a kind, but they are very versatile 1438Periodic watchers are also timers of a kind, but they are very versatile
1409(and unfortunately a bit complex). 1439(and unfortunately a bit complex).
1410.PP 1440.PP
1411Unlike \f(CW\*(C`ev_timer\*(C'\fR's, they are not based on real time (or relative time) 1441Unlike \f(CW\*(C`ev_timer\*(C'\fR's, they are not based on real time (or relative time)
1412but on wallclock time (absolute time). You can tell a periodic watcher 1442but on wall clock time (absolute time). You can tell a periodic watcher
1413to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a 1443to trigger after some specific point in time. For example, if you tell a
1414periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now () 1444periodic watcher to trigger in 10 seconds (by specifying e.g. \f(CW\*(C`ev_now ()
1415+ 10.\*(C'\fR) and then reset your system clock to the last year, then it will 1445+ 10.\*(C'\fR, that is, an absolute time not a delay) and then reset your system
1446clock to January of the previous year, then it will take more than year
1416take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger 1447to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would still trigger
1417roughly 10 seconds later). 1448roughly 10 seconds later as it uses a relative timeout).
1418.PP 1449.PP
1419They can also be used to implement vastly more complex timers, such as 1450\&\f(CW\*(C`ev_periodic\*(C'\fRs can also be used to implement vastly more complex timers,
1420triggering an event on each midnight, local time or other, complicated, 1451such as triggering an event on each \*(L"midnight, local time\*(R", or other
1421rules. 1452complicated, rules.
1422.PP 1453.PP
1423As with timers, the callback is guarenteed to be invoked only when the 1454As with timers, the callback is guaranteed to be invoked only when the
1424time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready 1455time (\f(CW\*(C`at\*(C'\fR) has passed, but if multiple periodic timers become ready
1425during the same loop iteration then order of execution is undefined. 1456during the same loop iteration then order of execution is undefined.
1426.PP 1457.PP
1427\fIWatcher-Specific Functions and Data Members\fR 1458\fIWatcher-Specific Functions and Data Members\fR
1428.IX Subsection "Watcher-Specific Functions and Data Members" 1459.IX Subsection "Watcher-Specific Functions and Data Members"
1429.IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4 1460.IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4
1436operation, and we will explain them from simplest to complex: 1467operation, and we will explain them from simplest to complex:
1437.RS 4 1468.RS 4
1438.IP "\(bu" 4 1469.IP "\(bu" 4
1439absolute timer (at = time, interval = reschedule_cb = 0) 1470absolute timer (at = time, interval = reschedule_cb = 0)
1440.Sp 1471.Sp
1441In this configuration the watcher triggers an event at the wallclock time 1472In this configuration the watcher triggers an event after the wall clock
1442\&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs, 1473time \f(CW\*(C`at\*(C'\fR has passed and doesn't repeat. It will not adjust when a time
1443that is, if it is to be run at January 1st 2011 then it will run when the 1474jump occurs, that is, if it is to be run at January 1st 2011 then it will
1444system time reaches or surpasses this time. 1475run when the system time reaches or surpasses this time.
1445.IP "\(bu" 4 1476.IP "\(bu" 4
1446repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) 1477repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
1447.Sp 1478.Sp
1448In this mode the watcher will always be scheduled to time out at the next 1479In this mode the watcher will always be scheduled to time out at the next
1449\&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N, which can also be negative) 1480\&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N, which can also be negative)
1450and then repeat, regardless of any time jumps. 1481and then repeat, regardless of any time jumps.
1451.Sp 1482.Sp
1452This can be used to create timers that do not drift with respect to system 1483This can be used to create timers that do not drift with respect to system
1453time: 1484time, for example, here is a \f(CW\*(C`ev_periodic\*(C'\fR that triggers each hour, on
1485the hour:
1454.Sp 1486.Sp
1455.Vb 1 1487.Vb 1
1456\& ev_periodic_set (&periodic, 0., 3600., 0); 1488\& ev_periodic_set (&periodic, 0., 3600., 0);
1457.Ve 1489.Ve
1458.Sp 1490.Sp
1459This doesn't mean there will always be 3600 seconds in between triggers, 1491This doesn't mean there will always be 3600 seconds in between triggers,
1460but only that the the callback will be called when the system time shows a 1492but only that the callback will be called when the system time shows a
1461full hour (\s-1UTC\s0), or more correctly, when the system time is evenly divisible 1493full hour (\s-1UTC\s0), or more correctly, when the system time is evenly divisible
1462by 3600. 1494by 3600.
1463.Sp 1495.Sp
1464Another way to think about it (for the mathematically inclined) is that 1496Another way to think about it (for the mathematically inclined) is that
1465\&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible 1497\&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible
1466time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps. 1498time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps.
1467.Sp 1499.Sp
1468For numerical stability it is preferable that the \f(CW\*(C`at\*(C'\fR value is near 1500For numerical stability it is preferable that the \f(CW\*(C`at\*(C'\fR value is near
1469\&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for 1501\&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for
1470this value. 1502this value, and in fact is often specified as zero.
1503.Sp
1504Note also that there is an upper limit to how often a timer can fire (\s-1CPU\s0
1505speed for example), so if \f(CW\*(C`interval\*(C'\fR is very small then timing stability
1506will of course deteriorate. Libev itself tries to be exact to be about one
1507millisecond (if the \s-1OS\s0 supports it and the machine is fast enough).
1471.IP "\(bu" 4 1508.IP "\(bu" 4
1472manual reschedule mode (at and interval ignored, reschedule_cb = callback) 1509manual reschedule mode (at and interval ignored, reschedule_cb = callback)
1473.Sp 1510.Sp
1474In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being 1511In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being
1475ignored. Instead, each time the periodic watcher gets scheduled, the 1512ignored. Instead, each time the periodic watcher gets scheduled, the
1476reschedule callback will be called with the watcher as first, and the 1513reschedule callback will be called with the watcher as first, and the
1477current time as second argument. 1514current time as second argument.
1478.Sp 1515.Sp
1479\&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, 1516\&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher,
1480ever, or make any event loop modifications\fR. If you need to stop it, 1517ever, or make \s-1ANY\s0 event loop modifications whatsoever\fR.
1481return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by 1518.Sp
1519If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop
1482starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is legal). 1520it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the
1521only event loop modification you are allowed to do).
1483.Sp 1522.Sp
1484Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w, 1523The callback prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic
1485ev_tstamp now)\*(C'\fR, e.g.: 1524*w, ev_tstamp now)\*(C'\fR, e.g.:
1486.Sp 1525.Sp
1487.Vb 4 1526.Vb 4
1488\& static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) 1527\& static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
1489\& { 1528\& {
1490\& return now + 60.; 1529\& return now + 60.;
1494It must return the next time to trigger, based on the passed time value 1533It must return the next time to trigger, based on the passed time value
1495(that is, the lowest time value larger than to the second argument). It 1534(that is, the lowest time value larger than to the second argument). It
1496will usually be called just before the callback will be triggered, but 1535will usually be called just before the callback will be triggered, but
1497might be called at other times, too. 1536might be called at other times, too.
1498.Sp 1537.Sp
1499\&\s-1NOTE:\s0 \fIThis callback must always return a time that is later than the 1538\&\s-1NOTE:\s0 \fIThis callback must always return a time that is higher than or
1500passed \f(CI\*(C`now\*(C'\fI value\fR. Not even \f(CW\*(C`now\*(C'\fR itself will do, it \fImust\fR be larger. 1539equal to the passed \f(CI\*(C`now\*(C'\fI value\fR.
1501.Sp 1540.Sp
1502This can be used to create very complex timers, such as a timer that 1541This can be used to create very complex timers, such as a timer that
1503triggers on each midnight, local time. To do this, you would calculate the 1542triggers on \*(L"next midnight, local time\*(R". To do this, you would calculate the
1504next midnight after \f(CW\*(C`now\*(C'\fR and return the timestamp value for this. How 1543next midnight after \f(CW\*(C`now\*(C'\fR and return the timestamp value for this. How
1505you do this is, again, up to you (but it is not trivial, which is the main 1544you do this is, again, up to you (but it is not trivial, which is the main
1506reason I omitted it as an example). 1545reason I omitted it as an example).
1507.RE 1546.RE
1508.RS 4 1547.RS 4
1538\fIExamples\fR 1577\fIExamples\fR
1539.IX Subsection "Examples" 1578.IX Subsection "Examples"
1540.PP 1579.PP
1541Example: Call a callback every hour, or, more precisely, whenever the 1580Example: Call a callback every hour, or, more precisely, whenever the
1542system clock is divisible by 3600. The callback invocation times have 1581system clock is divisible by 3600. The callback invocation times have
1543potentially a lot of jittering, but good long-term stability. 1582potentially a lot of jitter, but good long-term stability.
1544.PP 1583.PP
1545.Vb 5 1584.Vb 5
1546\& static void 1585\& static void
1547\& clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) 1586\& clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1548\& { 1587\& {
1549\& ... its now a full hour (UTC, or TAI or whatever your clock follows) 1588\& ... its now a full hour (UTC, or TAI or whatever your clock follows)
1550\& } 1589\& }
1551\& 1590\&
1552\& struct ev_periodic hourly_tick; 1591\& struct ev_periodic hourly_tick;
1553\& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); 1592\& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1554\& ev_periodic_start (loop, &hourly_tick); 1593\& ev_periodic_start (loop, &hourly_tick);
1555.Ve 1594.Ve
1556.PP 1595.PP
1557Example: The same as above, but use a reschedule callback to do it: 1596Example: The same as above, but use a reschedule callback to do it:
1558.PP 1597.PP
1559.Vb 1 1598.Vb 1
1560\& #include <math.h> 1599\& #include <math.h>
1561\& 1600\&
1562\& static ev_tstamp 1601\& static ev_tstamp
1563\& my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) 1602\& my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
1564\& { 1603\& {
1565\& return fmod (now, 3600.) + 3600.; 1604\& return fmod (now, 3600.) + 3600.;
1566\& } 1605\& }
1567\& 1606\&
1568\& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); 1607\& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1569.Ve 1608.Ve
1570.PP 1609.PP
1571Example: Call a callback every hour, starting now: 1610Example: Call a callback every hour, starting now:
1572.PP 1611.PP
1573.Vb 4 1612.Vb 4
1574\& struct ev_periodic hourly_tick; 1613\& struct ev_periodic hourly_tick;
1575\& ev_periodic_init (&hourly_tick, clock_cb, 1614\& ev_periodic_init (&hourly_tick, clock_cb,
1576\& fmod (ev_now (loop), 3600.), 3600., 0); 1615\& fmod (ev_now (loop), 3600.), 3600., 0);
1577\& ev_periodic_start (loop, &hourly_tick); 1616\& ev_periodic_start (loop, &hourly_tick);
1578.Ve 1617.Ve
1579.ie n .Sh """ev_signal"" \- signal me when a signal gets signalled!" 1618.ie n .Sh """ev_signal"" \- signal me when a signal gets signalled!"
1580.el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled!" 1619.el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled!"
1581.IX Subsection "ev_signal - signal me when a signal gets signalled!" 1620.IX Subsection "ev_signal - signal me when a signal gets signalled!"
1582Signal watchers will trigger an event when the process receives a specific 1621Signal watchers will trigger an event when the process receives a specific
1590as you don't register any with libev). Similarly, when the last signal 1629as you don't register any with libev). Similarly, when the last signal
1591watcher for a signal is stopped libev will reset the signal handler to 1630watcher for a signal is stopped libev will reset the signal handler to
1592\&\s-1SIG_DFL\s0 (regardless of what it was set to before). 1631\&\s-1SIG_DFL\s0 (regardless of what it was set to before).
1593.PP 1632.PP
1594If possible and supported, libev will install its handlers with 1633If possible and supported, libev will install its handlers with
1595\&\f(CW\*(C`SA_RESTART\*(C'\fR behaviour enabled, so syscalls should not be unduly 1634\&\f(CW\*(C`SA_RESTART\*(C'\fR behaviour enabled, so system calls should not be unduly
1596interrupted. If you have a problem with syscalls getting interrupted by 1635interrupted. If you have a problem with system calls getting interrupted by
1597signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher and unblock 1636signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher and unblock
1598them in an \f(CW\*(C`ev_prepare\*(C'\fR watcher. 1637them in an \f(CW\*(C`ev_prepare\*(C'\fR watcher.
1599.PP 1638.PP
1600\fIWatcher-Specific Functions and Data Members\fR 1639\fIWatcher-Specific Functions and Data Members\fR
1601.IX Subsection "Watcher-Specific Functions and Data Members" 1640.IX Subsection "Watcher-Specific Functions and Data Members"
1615.IX Subsection "Examples" 1654.IX Subsection "Examples"
1616.PP 1655.PP
1617Example: Try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0. 1656Example: Try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0.
1618.PP 1657.PP
1619.Vb 5 1658.Vb 5
1620\& static void 1659\& static void
1621\& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) 1660\& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1622\& { 1661\& {
1623\& ev_unloop (loop, EVUNLOOP_ALL); 1662\& ev_unloop (loop, EVUNLOOP_ALL);
1624\& } 1663\& }
1625\& 1664\&
1626\& struct ev_signal signal_watcher; 1665\& struct ev_signal signal_watcher;
1627\& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); 1666\& ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1628\& ev_signal_start (loop, &sigint_cb); 1667\& ev_signal_start (loop, &sigint_cb);
1629.Ve 1668.Ve
1630.ie n .Sh """ev_child"" \- watch out for process status changes" 1669.ie n .Sh """ev_child"" \- watch out for process status changes"
1631.el .Sh "\f(CWev_child\fP \- watch out for process status changes" 1670.el .Sh "\f(CWev_child\fP \- watch out for process status changes"
1632.IX Subsection "ev_child - watch out for process status changes" 1671.IX Subsection "ev_child - watch out for process status changes"
1633Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to 1672Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to
1635is permissible to install a child watcher \fIafter\fR the child has been 1674is permissible to install a child watcher \fIafter\fR the child has been
1636forked (which implies it might have already exited), as long as the event 1675forked (which implies it might have already exited), as long as the event
1637loop isn't entered (or is continued from a watcher). 1676loop isn't entered (or is continued from a watcher).
1638.PP 1677.PP
1639Only the default event loop is capable of handling signals, and therefore 1678Only the default event loop is capable of handling signals, and therefore
1640you can only rgeister child watchers in the default event loop. 1679you can only register child watchers in the default event loop.
1641.PP 1680.PP
1642\fIProcess Interaction\fR 1681\fIProcess Interaction\fR
1643.IX Subsection "Process Interaction" 1682.IX Subsection "Process Interaction"
1644.PP 1683.PP
1645Libev grabs \f(CW\*(C`SIGCHLD\*(C'\fR as soon as the default event loop is 1684Libev grabs \f(CW\*(C`SIGCHLD\*(C'\fR as soon as the default event loop is
1646initialised. This is necessary to guarantee proper behaviour even if 1685initialised. This is necessary to guarantee proper behaviour even if
1647the first child watcher is started after the child exits. The occurance 1686the first child watcher is started after the child exits. The occurrence
1648of \f(CW\*(C`SIGCHLD\*(C'\fR is recorded asynchronously, but child reaping is done 1687of \f(CW\*(C`SIGCHLD\*(C'\fR is recorded asynchronously, but child reaping is done
1649synchronously as part of the event loop processing. Libev always reaps all 1688synchronously as part of the event loop processing. Libev always reaps all
1650children, even ones not watched. 1689children, even ones not watched.
1651.PP 1690.PP
1652\fIOverriding the Built-In Processing\fR 1691\fIOverriding the Built-In Processing\fR
1692.PP 1731.PP
1693Example: \f(CW\*(C`fork()\*(C'\fR a new process and install a child handler to wait for 1732Example: \f(CW\*(C`fork()\*(C'\fR a new process and install a child handler to wait for
1694its completion. 1733its completion.
1695.PP 1734.PP
1696.Vb 1 1735.Vb 1
1697\& ev_child cw; 1736\& ev_child cw;
1698\& 1737\&
1699\& static void 1738\& static void
1700\& child_cb (EV_P_ struct ev_child *w, int revents) 1739\& child_cb (EV_P_ struct ev_child *w, int revents)
1701\& { 1740\& {
1702\& ev_child_stop (EV_A_ w); 1741\& ev_child_stop (EV_A_ w);
1703\& printf ("process %d exited with status %x\en", w\->rpid, w\->rstatus); 1742\& printf ("process %d exited with status %x\en", w\->rpid, w\->rstatus);
1704\& } 1743\& }
1705\& 1744\&
1706\& pid_t pid = fork (); 1745\& pid_t pid = fork ();
1707\& 1746\&
1708\& if (pid < 0) 1747\& if (pid < 0)
1709\& // error 1748\& // error
1710\& else if (pid == 0) 1749\& else if (pid == 0)
1711\& { 1750\& {
1712\& // the forked child executes here 1751\& // the forked child executes here
1713\& exit (1); 1752\& exit (1);
1714\& } 1753\& }
1715\& else 1754\& else
1716\& { 1755\& {
1717\& ev_child_init (&cw, child_cb, pid, 0); 1756\& ev_child_init (&cw, child_cb, pid, 0);
1718\& ev_child_start (EV_DEFAULT_ &cw); 1757\& ev_child_start (EV_DEFAULT_ &cw);
1719\& } 1758\& }
1720.Ve 1759.Ve
1721.ie n .Sh """ev_stat"" \- did the file attributes just change?" 1760.ie n .Sh """ev_stat"" \- did the file attributes just change?"
1722.el .Sh "\f(CWev_stat\fP \- did the file attributes just change?" 1761.el .Sh "\f(CWev_stat\fP \- did the file attributes just change?"
1723.IX Subsection "ev_stat - did the file attributes just change?" 1762.IX Subsection "ev_stat - did the file attributes just change?"
1724This watches a filesystem path for attribute changes. That is, it calls 1763This watches a file system path for attribute changes. That is, it calls
1725\&\f(CW\*(C`stat\*(C'\fR regularly (or when the \s-1OS\s0 says it changed) and sees if it changed 1764\&\f(CW\*(C`stat\*(C'\fR regularly (or when the \s-1OS\s0 says it changed) and sees if it changed
1726compared to the last time, invoking the callback if it did. 1765compared to the last time, invoking the callback if it did.
1727.PP 1766.PP
1728The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does 1767The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does
1729not exist\*(R" is a status change like any other. The condition \*(L"path does 1768not exist\*(R" is a status change like any other. The condition \*(L"path does
1764disabled large file support, you get the 32 bit version of the stat 1803disabled large file support, you get the 32 bit version of the stat
1765structure. When using the library from programs that change the \s-1ABI\s0 to 1804structure. When using the library from programs that change the \s-1ABI\s0 to
1766use 64 bit file offsets the programs will fail. In that case you have to 1805use 64 bit file offsets the programs will fail. In that case you have to
1767compile libev with the same flags to get binary compatibility. This is 1806compile libev with the same flags to get binary compatibility. This is
1768obviously the case with any flags that change the \s-1ABI\s0, but the problem is 1807obviously the case with any flags that change the \s-1ABI\s0, but the problem is
1769most noticably with ev_stat and largefile support. 1808most noticeably with ev_stat and large file support.
1770.PP 1809.PP
1771\fIInotify\fR 1810\fIInotify\fR
1772.IX Subsection "Inotify" 1811.IX Subsection "Inotify"
1773.PP 1812.PP
1774When \f(CW\*(C`inotify (7)\*(C'\fR support has been compiled into libev (generally only 1813When \f(CW\*(C`inotify (7)\*(C'\fR support has been compiled into libev (generally only
1786descriptor open on the object at all times). 1825descriptor open on the object at all times).
1787.PP 1826.PP
1788\fIThe special problem of stat time resolution\fR 1827\fIThe special problem of stat time resolution\fR
1789.IX Subsection "The special problem of stat time resolution" 1828.IX Subsection "The special problem of stat time resolution"
1790.PP 1829.PP
1791The \f(CW\*(C`stat ()\*(C'\fR syscall only supports full-second resolution portably, and 1830The \f(CW\*(C`stat ()\*(C'\fR system call only supports full-second resolution portably, and
1792even on systems where the resolution is higher, many filesystems still 1831even on systems where the resolution is higher, many file systems still
1793only support whole seconds. 1832only support whole seconds.
1794.PP 1833.PP
1795That means that, if the time is the only thing that changes, you can 1834That means that, if the time is the only thing that changes, you can
1796easily miss updates: on the first update, \f(CW\*(C`ev_stat\*(C'\fR detects a change and 1835easily miss updates: on the first update, \f(CW\*(C`ev_stat\*(C'\fR detects a change and
1797calls your callback, which does something. When there is another update 1836calls your callback, which does something. When there is another update
1798within the same second, \f(CW\*(C`ev_stat\*(C'\fR will be unable to detect it as the stat 1837within the same second, \f(CW\*(C`ev_stat\*(C'\fR will be unable to detect it as the stat
1799data does not change. 1838data does not change.
1800.PP 1839.PP
1801The solution to this is to delay acting on a change for slightly more 1840The solution to this is to delay acting on a change for slightly more
1802than second (or till slightly after the next full second boundary), using 1841than a second (or till slightly after the next full second boundary), using
1803a roughly one-second-delay \f(CW\*(C`ev_timer\*(C'\fR (e.g. \f(CW\*(C`ev_timer_set (w, 0., 1.02); 1842a roughly one-second-delay \f(CW\*(C`ev_timer\*(C'\fR (e.g. \f(CW\*(C`ev_timer_set (w, 0., 1.02);
1804ev_timer_again (loop, w)\*(C'\fR). 1843ev_timer_again (loop, w)\*(C'\fR).
1805.PP 1844.PP
1806The \f(CW.02\fR offset is added to work around small timing inconsistencies 1845The \f(CW.02\fR offset is added to work around small timing inconsistencies
1807of some operating systems (where the second counter of the current time 1846of some operating systems (where the second counter of the current time
1852.IP "ev_tstamp interval [read\-only]" 4 1891.IP "ev_tstamp interval [read\-only]" 4
1853.IX Item "ev_tstamp interval [read-only]" 1892.IX Item "ev_tstamp interval [read-only]"
1854The specified interval. 1893The specified interval.
1855.IP "const char *path [read\-only]" 4 1894.IP "const char *path [read\-only]" 4
1856.IX Item "const char *path [read-only]" 1895.IX Item "const char *path [read-only]"
1857The filesystem path that is being watched. 1896The file system path that is being watched.
1858.PP 1897.PP
1859\fIExamples\fR 1898\fIExamples\fR
1860.IX Subsection "Examples" 1899.IX Subsection "Examples"
1861.PP 1900.PP
1862Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes. 1901Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes.
1863.PP 1902.PP
1864.Vb 10 1903.Vb 10
1865\& static void 1904\& static void
1866\& passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) 1905\& passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
1867\& { 1906\& {
1868\& /* /etc/passwd changed in some way */ 1907\& /* /etc/passwd changed in some way */
1869\& if (w\->attr.st_nlink) 1908\& if (w\->attr.st_nlink)
1870\& { 1909\& {
1871\& printf ("passwd current size %ld\en", (long)w\->attr.st_size); 1910\& printf ("passwd current size %ld\en", (long)w\->attr.st_size);
1872\& printf ("passwd current atime %ld\en", (long)w\->attr.st_mtime); 1911\& printf ("passwd current atime %ld\en", (long)w\->attr.st_mtime);
1873\& printf ("passwd current mtime %ld\en", (long)w\->attr.st_mtime); 1912\& printf ("passwd current mtime %ld\en", (long)w\->attr.st_mtime);
1874\& } 1913\& }
1875\& else 1914\& else
1876\& /* you shalt not abuse printf for puts */ 1915\& /* you shalt not abuse printf for puts */
1877\& puts ("wow, /etc/passwd is not there, expect problems. " 1916\& puts ("wow, /etc/passwd is not there, expect problems. "
1878\& "if this is windows, they already arrived\en"); 1917\& "if this is windows, they already arrived\en");
1879\& } 1918\& }
1880\& 1919\&
1881\& ... 1920\& ...
1882\& ev_stat passwd; 1921\& ev_stat passwd;
1883\& 1922\&
1884\& ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.); 1923\& ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);
1885\& ev_stat_start (loop, &passwd); 1924\& ev_stat_start (loop, &passwd);
1886.Ve 1925.Ve
1887.PP 1926.PP
1888Example: Like above, but additionally use a one-second delay so we do not 1927Example: Like above, but additionally use a one-second delay so we do not
1889miss updates (however, frequent updates will delay processing, too, so 1928miss updates (however, frequent updates will delay processing, too, so
1890one might do the work both on \f(CW\*(C`ev_stat\*(C'\fR callback invocation \fIand\fR on 1929one might do the work both on \f(CW\*(C`ev_stat\*(C'\fR callback invocation \fIand\fR on
1891\&\f(CW\*(C`ev_timer\*(C'\fR callback invocation). 1930\&\f(CW\*(C`ev_timer\*(C'\fR callback invocation).
1892.PP 1931.PP
1893.Vb 2 1932.Vb 2
1894\& static ev_stat passwd; 1933\& static ev_stat passwd;
1895\& static ev_timer timer; 1934\& static ev_timer timer;
1896\& 1935\&
1897\& static void 1936\& static void
1898\& timer_cb (EV_P_ ev_timer *w, int revents) 1937\& timer_cb (EV_P_ ev_timer *w, int revents)
1899\& { 1938\& {
1900\& ev_timer_stop (EV_A_ w); 1939\& ev_timer_stop (EV_A_ w);
1901\& 1940\&
1902\& /* now it\*(Aqs one second after the most recent passwd change */ 1941\& /* now it\*(Aqs one second after the most recent passwd change */
1903\& } 1942\& }
1904\& 1943\&
1905\& static void 1944\& static void
1906\& stat_cb (EV_P_ ev_stat *w, int revents) 1945\& stat_cb (EV_P_ ev_stat *w, int revents)
1907\& { 1946\& {
1908\& /* reset the one\-second timer */ 1947\& /* reset the one\-second timer */
1909\& ev_timer_again (EV_A_ &timer); 1948\& ev_timer_again (EV_A_ &timer);
1910\& } 1949\& }
1911\& 1950\&
1912\& ... 1951\& ...
1913\& ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); 1952\& ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);
1914\& ev_stat_start (loop, &passwd); 1953\& ev_stat_start (loop, &passwd);
1915\& ev_timer_init (&timer, timer_cb, 0., 1.02); 1954\& ev_timer_init (&timer, timer_cb, 0., 1.02);
1916.Ve 1955.Ve
1917.ie n .Sh """ev_idle"" \- when you've got nothing better to do..." 1956.ie n .Sh """ev_idle"" \- when you've got nothing better to do..."
1918.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..." 1957.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..."
1919.IX Subsection "ev_idle - when you've got nothing better to do..." 1958.IX Subsection "ev_idle - when you've got nothing better to do..."
1920Idle watchers trigger events when no other events of the same or higher 1959Idle watchers trigger events when no other events of the same or higher
1949.PP 1988.PP
1950Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the 1989Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the
1951callback, free it. Also, use no error checking, as usual. 1990callback, free it. Also, use no error checking, as usual.
1952.PP 1991.PP
1953.Vb 7 1992.Vb 7
1954\& static void 1993\& static void
1955\& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) 1994\& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1956\& { 1995\& {
1957\& free (w); 1996\& free (w);
1958\& // now do something you wanted to do when the program has 1997\& // now do something you wanted to do when the program has
1959\& // no longer anything immediate to do. 1998\& // no longer anything immediate to do.
1960\& } 1999\& }
1961\& 2000\&
1962\& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); 2001\& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1963\& ev_idle_init (idle_watcher, idle_cb); 2002\& ev_idle_init (idle_watcher, idle_cb);
1964\& ev_idle_start (loop, idle_cb); 2003\& ev_idle_start (loop, idle_cb);
1965.Ve 2004.Ve
1966.ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!" 2005.ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!"
1967.el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" 2006.el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!"
1968.IX Subsection "ev_prepare and ev_check - customise your event loop!" 2007.IX Subsection "ev_prepare and ev_check - customise your event loop!"
1969Prepare and check watchers are usually (but not always) used in tandem: 2008Prepare and check watchers are usually (but not always) used in tandem:
1988.PP 2027.PP
1989This is done by examining in each prepare call which file descriptors need 2028This is done by examining in each prepare call which file descriptors need
1990to be watched by the other library, registering \f(CW\*(C`ev_io\*(C'\fR watchers for 2029to be watched by the other library, registering \f(CW\*(C`ev_io\*(C'\fR watchers for
1991them and starting an \f(CW\*(C`ev_timer\*(C'\fR watcher for any timeouts (many libraries 2030them and starting an \f(CW\*(C`ev_timer\*(C'\fR watcher for any timeouts (many libraries
1992provide just this functionality). Then, in the check watcher you check for 2031provide just this functionality). Then, in the check watcher you check for
1993any events that occured (by checking the pending status of all watchers 2032any events that occurred (by checking the pending status of all watchers
1994and stopping them) and call back into the library. The I/O and timer 2033and stopping them) and call back into the library. The I/O and timer
1995callbacks will never actually be called (but must be valid nevertheless, 2034callbacks will never actually be called (but must be valid nevertheless,
1996because you never know, you know?). 2035because you never know, you know?).
1997.PP 2036.PP
1998As another example, the Perl Coro module uses these hooks to integrate 2037As another example, the Perl Coro module uses these hooks to integrate
2041is pseudo-code only of course. This requires you to either use a low 2080is pseudo-code only of course. This requires you to either use a low
2042priority for the check watcher or use \f(CW\*(C`ev_clear_pending\*(C'\fR explicitly, as 2081priority for the check watcher or use \f(CW\*(C`ev_clear_pending\*(C'\fR explicitly, as
2043the callbacks for the IO/timeout watchers might not have been called yet. 2082the callbacks for the IO/timeout watchers might not have been called yet.
2044.PP 2083.PP
2045.Vb 2 2084.Vb 2
2046\& static ev_io iow [nfd]; 2085\& static ev_io iow [nfd];
2047\& static ev_timer tw; 2086\& static ev_timer tw;
2048\& 2087\&
2049\& static void 2088\& static void
2050\& io_cb (ev_loop *loop, ev_io *w, int revents) 2089\& io_cb (ev_loop *loop, ev_io *w, int revents)
2051\& { 2090\& {
2052\& } 2091\& }
2053\& 2092\&
2054\& // create io watchers for each fd and a timer before blocking 2093\& // create io watchers for each fd and a timer before blocking
2055\& static void 2094\& static void
2056\& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) 2095\& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
2057\& { 2096\& {
2058\& int timeout = 3600000; 2097\& int timeout = 3600000;
2059\& struct pollfd fds [nfd]; 2098\& struct pollfd fds [nfd];
2060\& // actual code will need to loop here and realloc etc. 2099\& // actual code will need to loop here and realloc etc.
2061\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); 2100\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
2062\& 2101\&
2063\& /* the callback is illegal, but won\*(Aqt be called as we stop during check */ 2102\& /* the callback is illegal, but won\*(Aqt be called as we stop during check */
2064\& ev_timer_init (&tw, 0, timeout * 1e\-3); 2103\& ev_timer_init (&tw, 0, timeout * 1e\-3);
2065\& ev_timer_start (loop, &tw); 2104\& ev_timer_start (loop, &tw);
2066\& 2105\&
2067\& // create one ev_io per pollfd 2106\& // create one ev_io per pollfd
2068\& for (int i = 0; i < nfd; ++i) 2107\& for (int i = 0; i < nfd; ++i)
2069\& { 2108\& {
2070\& ev_io_init (iow + i, io_cb, fds [i].fd, 2109\& ev_io_init (iow + i, io_cb, fds [i].fd,
2071\& ((fds [i].events & POLLIN ? EV_READ : 0) 2110\& ((fds [i].events & POLLIN ? EV_READ : 0)
2072\& | (fds [i].events & POLLOUT ? EV_WRITE : 0))); 2111\& | (fds [i].events & POLLOUT ? EV_WRITE : 0)));
2073\& 2112\&
2074\& fds [i].revents = 0; 2113\& fds [i].revents = 0;
2075\& ev_io_start (loop, iow + i); 2114\& ev_io_start (loop, iow + i);
2076\& } 2115\& }
2077\& } 2116\& }
2078\& 2117\&
2079\& // stop all watchers after blocking 2118\& // stop all watchers after blocking
2080\& static void 2119\& static void
2081\& adns_check_cb (ev_loop *loop, ev_check *w, int revents) 2120\& adns_check_cb (ev_loop *loop, ev_check *w, int revents)
2082\& { 2121\& {
2083\& ev_timer_stop (loop, &tw); 2122\& ev_timer_stop (loop, &tw);
2084\& 2123\&
2085\& for (int i = 0; i < nfd; ++i) 2124\& for (int i = 0; i < nfd; ++i)
2086\& { 2125\& {
2087\& // set the relevant poll flags 2126\& // set the relevant poll flags
2088\& // could also call adns_processreadable etc. here 2127\& // could also call adns_processreadable etc. here
2089\& struct pollfd *fd = fds + i; 2128\& struct pollfd *fd = fds + i;
2090\& int revents = ev_clear_pending (iow + i); 2129\& int revents = ev_clear_pending (iow + i);
2091\& if (revents & EV_READ ) fd\->revents |= fd\->events & POLLIN; 2130\& if (revents & EV_READ ) fd\->revents |= fd\->events & POLLIN;
2092\& if (revents & EV_WRITE) fd\->revents |= fd\->events & POLLOUT; 2131\& if (revents & EV_WRITE) fd\->revents |= fd\->events & POLLOUT;
2093\& 2132\&
2094\& // now stop the watcher 2133\& // now stop the watcher
2095\& ev_io_stop (loop, iow + i); 2134\& ev_io_stop (loop, iow + i);
2096\& } 2135\& }
2097\& 2136\&
2098\& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); 2137\& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
2099\& } 2138\& }
2100.Ve 2139.Ve
2101.PP 2140.PP
2102Method 2: This would be just like method 1, but you run \f(CW\*(C`adns_afterpoll\*(C'\fR 2141Method 2: This would be just like method 1, but you run \f(CW\*(C`adns_afterpoll\*(C'\fR
2103in the prepare watcher and would dispose of the check watcher. 2142in the prepare watcher and would dispose of the check watcher.
2104.PP 2143.PP
2105Method 3: If the module to be embedded supports explicit event 2144Method 3: If the module to be embedded supports explicit event
2106notification (adns does), you can also make use of the actual watcher 2145notification (libadns does), you can also make use of the actual watcher
2107callbacks, and only destroy/create the watchers in the prepare watcher. 2146callbacks, and only destroy/create the watchers in the prepare watcher.
2108.PP 2147.PP
2109.Vb 5 2148.Vb 5
2110\& static void 2149\& static void
2111\& timer_cb (EV_P_ ev_timer *w, int revents) 2150\& timer_cb (EV_P_ ev_timer *w, int revents)
2112\& { 2151\& {
2113\& adns_state ads = (adns_state)w\->data; 2152\& adns_state ads = (adns_state)w\->data;
2114\& update_now (EV_A); 2153\& update_now (EV_A);
2115\& 2154\&
2116\& adns_processtimeouts (ads, &tv_now); 2155\& adns_processtimeouts (ads, &tv_now);
2117\& } 2156\& }
2118\& 2157\&
2119\& static void 2158\& static void
2120\& io_cb (EV_P_ ev_io *w, int revents) 2159\& io_cb (EV_P_ ev_io *w, int revents)
2121\& { 2160\& {
2122\& adns_state ads = (adns_state)w\->data; 2161\& adns_state ads = (adns_state)w\->data;
2123\& update_now (EV_A); 2162\& update_now (EV_A);
2124\& 2163\&
2125\& if (revents & EV_READ ) adns_processreadable (ads, w\->fd, &tv_now); 2164\& if (revents & EV_READ ) adns_processreadable (ads, w\->fd, &tv_now);
2126\& if (revents & EV_WRITE) adns_processwriteable (ads, w\->fd, &tv_now); 2165\& if (revents & EV_WRITE) adns_processwriteable (ads, w\->fd, &tv_now);
2127\& } 2166\& }
2128\& 2167\&
2129\& // do not ever call adns_afterpoll 2168\& // do not ever call adns_afterpoll
2130.Ve 2169.Ve
2131.PP 2170.PP
2132Method 4: Do not use a prepare or check watcher because the module you 2171Method 4: Do not use a prepare or check watcher because the module you
2133want to embed is too inflexible to support it. Instead, youc na override 2172want to embed is too inflexible to support it. Instead, you can override
2134their poll function. The drawback with this solution is that the main 2173their poll function. The drawback with this solution is that the main
2135loop is now no longer controllable by \s-1EV\s0. The \f(CW\*(C`Glib::EV\*(C'\fR module does 2174loop is now no longer controllable by \s-1EV\s0. The \f(CW\*(C`Glib::EV\*(C'\fR module does
2136this. 2175this.
2137.PP 2176.PP
2138.Vb 4 2177.Vb 4
2139\& static gint 2178\& static gint
2140\& event_poll_func (GPollFD *fds, guint nfds, gint timeout) 2179\& event_poll_func (GPollFD *fds, guint nfds, gint timeout)
2141\& { 2180\& {
2142\& int got_events = 0; 2181\& int got_events = 0;
2143\& 2182\&
2144\& for (n = 0; n < nfds; ++n) 2183\& for (n = 0; n < nfds; ++n)
2145\& // create/start io watcher that sets the relevant bits in fds[n] and increment got_events 2184\& // create/start io watcher that sets the relevant bits in fds[n] and increment got_events
2146\& 2185\&
2147\& if (timeout >= 0) 2186\& if (timeout >= 0)
2148\& // create/start timer 2187\& // create/start timer
2149\& 2188\&
2150\& // poll 2189\& // poll
2151\& ev_loop (EV_A_ 0); 2190\& ev_loop (EV_A_ 0);
2152\& 2191\&
2153\& // stop timer again 2192\& // stop timer again
2154\& if (timeout >= 0) 2193\& if (timeout >= 0)
2155\& ev_timer_stop (EV_A_ &to); 2194\& ev_timer_stop (EV_A_ &to);
2156\& 2195\&
2157\& // stop io watchers again \- their callbacks should have set 2196\& // stop io watchers again \- their callbacks should have set
2158\& for (n = 0; n < nfds; ++n) 2197\& for (n = 0; n < nfds; ++n)
2159\& ev_io_stop (EV_A_ iow [n]); 2198\& ev_io_stop (EV_A_ iow [n]);
2160\& 2199\&
2161\& return got_events; 2200\& return got_events;
2162\& } 2201\& }
2163.Ve 2202.Ve
2164.ie n .Sh """ev_embed"" \- when one backend isn't enough..." 2203.ie n .Sh """ev_embed"" \- when one backend isn't enough..."
2165.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." 2204.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..."
2166.IX Subsection "ev_embed - when one backend isn't enough..." 2205.IX Subsection "ev_embed - when one backend isn't enough..."
2167This is a rather advanced watcher type that lets you embed one event loop 2206This is a rather advanced watcher type that lets you embed one event loop
2223.PD 2262.PD
2224Configures the watcher to embed the given loop, which must be 2263Configures the watcher to embed the given loop, which must be
2225embeddable. If the callback is \f(CW0\fR, then \f(CW\*(C`ev_embed_sweep\*(C'\fR will be 2264embeddable. If the callback is \f(CW0\fR, then \f(CW\*(C`ev_embed_sweep\*(C'\fR will be
2226invoked automatically, otherwise it is the responsibility of the callback 2265invoked automatically, otherwise it is the responsibility of the callback
2227to invoke it (it will continue to be called until the sweep has been done, 2266to invoke it (it will continue to be called until the sweep has been done,
2228if you do not want thta, you need to temporarily stop the embed watcher). 2267if you do not want that, you need to temporarily stop the embed watcher).
2229.IP "ev_embed_sweep (loop, ev_embed *)" 4 2268.IP "ev_embed_sweep (loop, ev_embed *)" 4
2230.IX Item "ev_embed_sweep (loop, ev_embed *)" 2269.IX Item "ev_embed_sweep (loop, ev_embed *)"
2231Make a single, non-blocking sweep over the embedded loop. This works 2270Make a single, non-blocking sweep over the embedded loop. This works
2232similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most 2271similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most
2233apropriate way for embedded loops. 2272appropriate way for embedded loops.
2234.IP "struct ev_loop *other [read\-only]" 4 2273.IP "struct ev_loop *other [read\-only]" 4
2235.IX Item "struct ev_loop *other [read-only]" 2274.IX Item "struct ev_loop *other [read-only]"
2236The embedded event loop. 2275The embedded event loop.
2237.PP 2276.PP
2238\fIExamples\fR 2277\fIExamples\fR
2239.IX Subsection "Examples" 2278.IX Subsection "Examples"
2240.PP 2279.PP
2241Example: Try to get an embeddable event loop and embed it into the default 2280Example: Try to get an embeddable event loop and embed it into the default
2242event loop. If that is not possible, use the default loop. The default 2281event loop. If that is not possible, use the default loop. The default
2243loop is stored in \f(CW\*(C`loop_hi\*(C'\fR, while the mebeddable loop is stored in 2282loop is stored in \f(CW\*(C`loop_hi\*(C'\fR, while the embeddable loop is stored in
2244\&\f(CW\*(C`loop_lo\*(C'\fR (which is \f(CW\*(C`loop_hi\*(C'\fR in the acse no embeddable loop can be 2283\&\f(CW\*(C`loop_lo\*(C'\fR (which is \f(CW\*(C`loop_hi\*(C'\fR in the case no embeddable loop can be
2245used). 2284used).
2246.PP 2285.PP
2247.Vb 3 2286.Vb 3
2248\& struct ev_loop *loop_hi = ev_default_init (0); 2287\& struct ev_loop *loop_hi = ev_default_init (0);
2249\& struct ev_loop *loop_lo = 0; 2288\& struct ev_loop *loop_lo = 0;
2250\& struct ev_embed embed; 2289\& struct ev_embed embed;
2251\& 2290\&
2252\& // see if there is a chance of getting one that works 2291\& // see if there is a chance of getting one that works
2253\& // (remember that a flags value of 0 means autodetection) 2292\& // (remember that a flags value of 0 means autodetection)
2254\& loop_lo = ev_embeddable_backends () & ev_recommended_backends () 2293\& loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
2255\& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) 2294\& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
2256\& : 0; 2295\& : 0;
2257\& 2296\&
2258\& // if we got one, then embed it, otherwise default to loop_hi 2297\& // if we got one, then embed it, otherwise default to loop_hi
2259\& if (loop_lo) 2298\& if (loop_lo)
2260\& { 2299\& {
2261\& ev_embed_init (&embed, 0, loop_lo); 2300\& ev_embed_init (&embed, 0, loop_lo);
2262\& ev_embed_start (loop_hi, &embed); 2301\& ev_embed_start (loop_hi, &embed);
2263\& } 2302\& }
2264\& else 2303\& else
2265\& loop_lo = loop_hi; 2304\& loop_lo = loop_hi;
2266.Ve 2305.Ve
2267.PP 2306.PP
2268Example: Check if kqueue is available but not recommended and create 2307Example: Check if kqueue is available but not recommended and create
2269a kqueue backend for use with sockets (which usually work with any 2308a kqueue backend for use with sockets (which usually work with any
2270kqueue implementation). Store the kqueue/socket\-only event loop in 2309kqueue implementation). Store the kqueue/socket\-only event loop in
2271\&\f(CW\*(C`loop_socket\*(C'\fR. (One might optionally use \f(CW\*(C`EVFLAG_NOENV\*(C'\fR, too). 2310\&\f(CW\*(C`loop_socket\*(C'\fR. (One might optionally use \f(CW\*(C`EVFLAG_NOENV\*(C'\fR, too).
2272.PP 2311.PP
2273.Vb 3 2312.Vb 3
2274\& struct ev_loop *loop = ev_default_init (0); 2313\& struct ev_loop *loop = ev_default_init (0);
2275\& struct ev_loop *loop_socket = 0; 2314\& struct ev_loop *loop_socket = 0;
2276\& struct ev_embed embed; 2315\& struct ev_embed embed;
2277\& 2316\&
2278\& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) 2317\& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)
2279\& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) 2318\& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))
2280\& { 2319\& {
2281\& ev_embed_init (&embed, 0, loop_socket); 2320\& ev_embed_init (&embed, 0, loop_socket);
2282\& ev_embed_start (loop, &embed); 2321\& ev_embed_start (loop, &embed);
2283\& } 2322\& }
2284\& 2323\&
2285\& if (!loop_socket) 2324\& if (!loop_socket)
2286\& loop_socket = loop; 2325\& loop_socket = loop;
2287\& 2326\&
2288\& // now use loop_socket for all sockets, and loop for everything else 2327\& // now use loop_socket for all sockets, and loop for everything else
2289.Ve 2328.Ve
2290.ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork" 2329.ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork"
2291.el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" 2330.el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork"
2292.IX Subsection "ev_fork - the audacity to resume the event loop after a fork" 2331.IX Subsection "ev_fork - the audacity to resume the event loop after a fork"
2293Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because 2332Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because
2339queue: 2378queue:
2340.IP "queueing from a signal handler context" 4 2379.IP "queueing from a signal handler context" 4
2341.IX Item "queueing from a signal handler context" 2380.IX Item "queueing from a signal handler context"
2342To implement race-free queueing, you simply add to the queue in the signal 2381To implement race-free queueing, you simply add to the queue in the signal
2343handler but you block the signal handler in the watcher callback. Here is an example that does that for 2382handler but you block the signal handler in the watcher callback. Here is an example that does that for
2344some fictitiuous \s-1SIGUSR1\s0 handler: 2383some fictitious \s-1SIGUSR1\s0 handler:
2345.Sp 2384.Sp
2346.Vb 1 2385.Vb 1
2347\& static ev_async mysig; 2386\& static ev_async mysig;
2348\& 2387\&
2349\& static void 2388\& static void
2420.IP "ev_async_send (loop, ev_async *)" 4 2459.IP "ev_async_send (loop, ev_async *)" 4
2421.IX Item "ev_async_send (loop, ev_async *)" 2460.IX Item "ev_async_send (loop, ev_async *)"
2422Sends/signals/activates the given \f(CW\*(C`ev_async\*(C'\fR watcher, that is, feeds 2461Sends/signals/activates the given \f(CW\*(C`ev_async\*(C'\fR watcher, that is, feeds
2423an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop. Unlike 2462an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop. Unlike
2424\&\f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do in other threads, signal or 2463\&\f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do in other threads, signal or
2425similar contexts (see the dicusssion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the embedding 2464similar contexts (see the discussion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the embedding
2426section below on what exactly this means). 2465section below on what exactly this means).
2427.Sp 2466.Sp
2428This call incurs the overhead of a syscall only once per loop iteration, 2467This call incurs the overhead of a system call only once per loop iteration,
2429so while the overhead might be noticable, it doesn't apply to repeated 2468so while the overhead might be noticeable, it doesn't apply to repeated
2430calls to \f(CW\*(C`ev_async_send\*(C'\fR. 2469calls to \f(CW\*(C`ev_async_send\*(C'\fR.
2431.IP "bool = ev_async_pending (ev_async *)" 4 2470.IP "bool = ev_async_pending (ev_async *)" 4
2432.IX Item "bool = ev_async_pending (ev_async *)" 2471.IX Item "bool = ev_async_pending (ev_async *)"
2433Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the 2472Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the
2434watcher but the event has not yet been processed (or even noted) by the 2473watcher but the event has not yet been processed (or even noted) by the
2435event loop. 2474event loop.
2436.Sp 2475.Sp
2437\&\f(CW\*(C`ev_async_send\*(C'\fR sets a flag in the watcher and wakes up the loop. When 2476\&\f(CW\*(C`ev_async_send\*(C'\fR sets a flag in the watcher and wakes up the loop. When
2438the loop iterates next and checks for the watcher to have become active, 2477the loop iterates next and checks for the watcher to have become active,
2439it will reset the flag again. \f(CW\*(C`ev_async_pending\*(C'\fR can be used to very 2478it will reset the flag again. \f(CW\*(C`ev_async_pending\*(C'\fR can be used to very
2440quickly check wether invoking the loop might be a good idea. 2479quickly check whether invoking the loop might be a good idea.
2441.Sp 2480.Sp
2442Not that this does \fInot\fR check wether the watcher itself is pending, only 2481Not that this does \fInot\fR check whether the watcher itself is pending, only
2443wether it has been requested to make this watcher pending. 2482whether it has been requested to make this watcher pending.
2444.SH "OTHER FUNCTIONS" 2483.SH "OTHER FUNCTIONS"
2445.IX Header "OTHER FUNCTIONS" 2484.IX Header "OTHER FUNCTIONS"
2446There are some other functions of possible interest. Described. Here. Now. 2485There are some other functions of possible interest. Described. Here. Now.
2447.IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 2486.IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4
2448.IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 2487.IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)"
2452or timeout without having to allocate/configure/start/stop/free one or 2491or timeout without having to allocate/configure/start/stop/free one or
2453more watchers yourself. 2492more watchers yourself.
2454.Sp 2493.Sp
2455If \f(CW\*(C`fd\*(C'\fR is less than 0, then no I/O watcher will be started and events 2494If \f(CW\*(C`fd\*(C'\fR is less than 0, then no I/O watcher will be started and events
2456is being ignored. Otherwise, an \f(CW\*(C`ev_io\*(C'\fR watcher for the given \f(CW\*(C`fd\*(C'\fR and 2495is being ignored. Otherwise, an \f(CW\*(C`ev_io\*(C'\fR watcher for the given \f(CW\*(C`fd\*(C'\fR and
2457\&\f(CW\*(C`events\*(C'\fR set will be craeted and started. 2496\&\f(CW\*(C`events\*(C'\fR set will be created and started.
2458.Sp 2497.Sp
2459If \f(CW\*(C`timeout\*(C'\fR is less than 0, then no timeout watcher will be 2498If \f(CW\*(C`timeout\*(C'\fR is less than 0, then no timeout watcher will be
2460started. Otherwise an \f(CW\*(C`ev_timer\*(C'\fR watcher with after = \f(CW\*(C`timeout\*(C'\fR (and 2499started. Otherwise an \f(CW\*(C`ev_timer\*(C'\fR watcher with after = \f(CW\*(C`timeout\*(C'\fR (and
2461repeat = 0) will be started. While \f(CW0\fR is a valid timeout, it is of 2500repeat = 0) will be started. While \f(CW0\fR is a valid timeout, it is of
2462dubious value. 2501dubious value.
2465passed an \f(CW\*(C`revents\*(C'\fR set like normal event callbacks (a combination of 2504passed an \f(CW\*(C`revents\*(C'\fR set like normal event callbacks (a combination of
2466\&\f(CW\*(C`EV_ERROR\*(C'\fR, \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or \f(CW\*(C`EV_TIMEOUT\*(C'\fR) and the \f(CW\*(C`arg\*(C'\fR 2505\&\f(CW\*(C`EV_ERROR\*(C'\fR, \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or \f(CW\*(C`EV_TIMEOUT\*(C'\fR) and the \f(CW\*(C`arg\*(C'\fR
2467value passed to \f(CW\*(C`ev_once\*(C'\fR: 2506value passed to \f(CW\*(C`ev_once\*(C'\fR:
2468.Sp 2507.Sp
2469.Vb 7 2508.Vb 7
2470\& static void stdin_ready (int revents, void *arg) 2509\& static void stdin_ready (int revents, void *arg)
2471\& { 2510\& {
2472\& if (revents & EV_TIMEOUT) 2511\& if (revents & EV_TIMEOUT)
2473\& /* doh, nothing entered */; 2512\& /* doh, nothing entered */;
2474\& else if (revents & EV_READ) 2513\& else if (revents & EV_READ)
2475\& /* stdin might have data for us, joy! */; 2514\& /* stdin might have data for us, joy! */;
2476\& } 2515\& }
2477\& 2516\&
2478\& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); 2517\& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
2479.Ve 2518.Ve
2480.IP "ev_feed_event (ev_loop *, watcher *, int revents)" 4 2519.IP "ev_feed_event (ev_loop *, watcher *, int revents)" 4
2481.IX Item "ev_feed_event (ev_loop *, watcher *, int revents)" 2520.IX Item "ev_feed_event (ev_loop *, watcher *, int revents)"
2482Feeds the given event set into the event loop, as if the specified event 2521Feeds the given event set into the event loop, as if the specified event
2483had happened for the specified watcher (which must be a pointer to an 2522had happened for the specified watcher (which must be a pointer to an
2486.IX Item "ev_feed_fd_event (ev_loop *, int fd, int revents)" 2525.IX Item "ev_feed_fd_event (ev_loop *, int fd, int revents)"
2487Feed an event on the given fd, as if a file descriptor backend detected 2526Feed an event on the given fd, as if a file descriptor backend detected
2488the given events it. 2527the given events it.
2489.IP "ev_feed_signal_event (ev_loop *loop, int signum)" 4 2528.IP "ev_feed_signal_event (ev_loop *loop, int signum)" 4
2490.IX Item "ev_feed_signal_event (ev_loop *loop, int signum)" 2529.IX Item "ev_feed_signal_event (ev_loop *loop, int signum)"
2491Feed an event as if the given signal occured (\f(CW\*(C`loop\*(C'\fR must be the default 2530Feed an event as if the given signal occurred (\f(CW\*(C`loop\*(C'\fR must be the default
2492loop!). 2531loop!).
2493.SH "LIBEVENT EMULATION" 2532.SH "LIBEVENT EMULATION"
2494.IX Header "LIBEVENT EMULATION" 2533.IX Header "LIBEVENT EMULATION"
2495Libev offers a compatibility emulation layer for libevent. It cannot 2534Libev offers a compatibility emulation layer for libevent. It cannot
2496emulate the internals of libevent, so here are some usage hints: 2535emulate the internals of libevent, so here are some usage hints:
2516The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need 2555The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need
2517to use the libev header file and library. 2556to use the libev header file and library.
2518.SH "\*(C+ SUPPORT" 2557.SH "\*(C+ SUPPORT"
2519.IX Header " SUPPORT" 2558.IX Header " SUPPORT"
2520Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow 2559Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow
2521you to use some convinience methods to start/stop watchers and also change 2560you to use some convenience methods to start/stop watchers and also change
2522the callback model to a model using method callbacks on objects. 2561the callback model to a model using method callbacks on objects.
2523.PP 2562.PP
2524To use it, 2563To use it,
2525.PP 2564.PP
2526.Vb 1 2565.Vb 1
2527\& #include <ev++.h> 2566\& #include <ev++.h>
2528.Ve 2567.Ve
2529.PP 2568.PP
2530This automatically includes \fIev.h\fR and puts all of its definitions (many 2569This automatically includes \fIev.h\fR and puts all of its definitions (many
2531of them macros) into the global namespace. All \*(C+ specific things are 2570of them macros) into the global namespace. All \*(C+ specific things are
2532put into the \f(CW\*(C`ev\*(C'\fR namespace. It should support all the same embedding 2571put into the \f(CW\*(C`ev\*(C'\fR namespace. It should support all the same embedding
2598thunking function, making it as fast as a direct C callback. 2637thunking function, making it as fast as a direct C callback.
2599.Sp 2638.Sp
2600Example: simple class declaration and watcher initialisation 2639Example: simple class declaration and watcher initialisation
2601.Sp 2640.Sp
2602.Vb 4 2641.Vb 4
2603\& struct myclass 2642\& struct myclass
2604\& { 2643\& {
2605\& void io_cb (ev::io &w, int revents) { } 2644\& void io_cb (ev::io &w, int revents) { }
2606\& } 2645\& }
2607\& 2646\&
2608\& myclass obj; 2647\& myclass obj;
2609\& ev::io iow; 2648\& ev::io iow;
2610\& iow.set <myclass, &myclass::io_cb> (&obj); 2649\& iow.set <myclass, &myclass::io_cb> (&obj);
2611.Ve 2650.Ve
2612.IP "w\->set<function> (void *data = 0)" 4 2651.IP "w\->set<function> (void *data = 0)" 4
2613.IX Item "w->set<function> (void *data = 0)" 2652.IX Item "w->set<function> (void *data = 0)"
2614Also sets a callback, but uses a static method or plain function as 2653Also sets a callback, but uses a static method or plain function as
2615callback. The optional \f(CW\*(C`data\*(C'\fR argument will be stored in the watcher's 2654callback. The optional \f(CW\*(C`data\*(C'\fR argument will be stored in the watcher's
2620See the method\-\f(CW\*(C`set\*(C'\fR above for more details. 2659See the method\-\f(CW\*(C`set\*(C'\fR above for more details.
2621.Sp 2660.Sp
2622Example: 2661Example:
2623.Sp 2662.Sp
2624.Vb 2 2663.Vb 2
2625\& static void io_cb (ev::io &w, int revents) { } 2664\& static void io_cb (ev::io &w, int revents) { }
2626\& iow.set <io_cb> (); 2665\& iow.set <io_cb> ();
2627.Ve 2666.Ve
2628.IP "w\->set (struct ev_loop *)" 4 2667.IP "w\->set (struct ev_loop *)" 4
2629.IX Item "w->set (struct ev_loop *)" 2668.IX Item "w->set (struct ev_loop *)"
2630Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only 2669Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only
2631do this when the watcher is inactive (and not pending either). 2670do this when the watcher is inactive (and not pending either).
2632.IP "w\->set ([args])" 4 2671.IP "w\->set ([arguments])" 4
2633.IX Item "w->set ([args])" 2672.IX Item "w->set ([arguments])"
2634Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be 2673Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same arguments. Must be
2635called at least once. Unlike the C counterpart, an active watcher gets 2674called at least once. Unlike the C counterpart, an active watcher gets
2636automatically stopped and restarted when reconfiguring it with this 2675automatically stopped and restarted when reconfiguring it with this
2637method. 2676method.
2638.IP "w\->start ()" 4 2677.IP "w\->start ()" 4
2639.IX Item "w->start ()" 2678.IX Item "w->start ()"
2661.PP 2700.PP
2662Example: Define a class with an \s-1IO\s0 and idle watcher, start one of them in 2701Example: Define a class with an \s-1IO\s0 and idle watcher, start one of them in
2663the constructor. 2702the constructor.
2664.PP 2703.PP
2665.Vb 4 2704.Vb 4
2666\& class myclass 2705\& class myclass
2667\& { 2706\& {
2668\& ev::io io; void io_cb (ev::io &w, int revents); 2707\& ev::io io; void io_cb (ev::io &w, int revents);
2669\& ev:idle idle void idle_cb (ev::idle &w, int revents); 2708\& ev:idle idle void idle_cb (ev::idle &w, int revents);
2670\& 2709\&
2671\& myclass (int fd) 2710\& myclass (int fd)
2672\& { 2711\& {
2673\& io .set <myclass, &myclass::io_cb > (this); 2712\& io .set <myclass, &myclass::io_cb > (this);
2674\& idle.set <myclass, &myclass::idle_cb> (this); 2713\& idle.set <myclass, &myclass::idle_cb> (this);
2675\& 2714\&
2676\& io.start (fd, ev::READ); 2715\& io.start (fd, ev::READ);
2677\& } 2716\& }
2678\& }; 2717\& };
2679.Ve 2718.Ve
2680.SH "OTHER LANGUAGE BINDINGS" 2719.SH "OTHER LANGUAGE BINDINGS"
2681.IX Header "OTHER LANGUAGE BINDINGS" 2720.IX Header "OTHER LANGUAGE BINDINGS"
2682Libev does not offer other language bindings itself, but bindings for a 2721Libev does not offer other language bindings itself, but bindings for a
2683numbe rof languages exist in the form of third-party packages. If you know 2722number of languages exist in the form of third-party packages. If you know
2684any interesting language binding in addition to the ones listed here, drop 2723any interesting language binding in addition to the ones listed here, drop
2685me a note. 2724me a note.
2686.IP "Perl" 4 2725.IP "Perl" 4
2687.IX Item "Perl" 2726.IX Item "Perl"
2688The \s-1EV\s0 module implements the full libev \s-1API\s0 and is actually used to test 2727The \s-1EV\s0 module implements the full libev \s-1API\s0 and is actually used to test
2689libev. \s-1EV\s0 is developed together with libev. Apart from the \s-1EV\s0 core module, 2728libev. \s-1EV\s0 is developed together with libev. Apart from the \s-1EV\s0 core module,
2690there are additional modules that implement libev-compatible interfaces 2729there are additional modules that implement libev-compatible interfaces
2691to \f(CW\*(C`libadns\*(C'\fR (\f(CW\*(C`EV::ADNS\*(C'\fR), \f(CW\*(C`Net::SNMP\*(C'\fR (\f(CW\*(C`Net::SNMP::EV\*(C'\fR) and the 2730to \f(CW\*(C`libadns\*(C'\fR (\f(CW\*(C`EV::ADNS\*(C'\fR), \f(CW\*(C`Net::SNMP\*(C'\fR (\f(CW\*(C`Net::SNMP::EV\*(C'\fR) and the
2692\&\f(CW\*(C`libglib\*(C'\fR event core (\f(CW\*(C`Glib::EV\*(C'\fR and \f(CW\*(C`EV::Glib\*(C'\fR). 2731\&\f(CW\*(C`libglib\*(C'\fR event core (\f(CW\*(C`Glib::EV\*(C'\fR and \f(CW\*(C`EV::Glib\*(C'\fR).
2693.Sp 2732.Sp
2694It can be found and installed via \s-1CPAN\s0, its homepage is found at 2733It can be found and installed via \s-1CPAN\s0, its homepage is at
2695<http://software.schmorp.de/pkg/EV>. 2734<http://software.schmorp.de/pkg/EV>.
2735.IP "Python" 4
2736.IX Item "Python"
2737Python bindings can be found at <http://code.google.com/p/pyev/>. It
2738seems to be quite complete and well-documented. Note, however, that the
2739patch they require for libev is outright dangerous as it breaks the \s-1ABI\s0
2740for everybody else, and therefore, should never be applied in an installed
2741libev (if python requires an incompatible \s-1ABI\s0 then it needs to embed
2742libev).
2696.IP "Ruby" 4 2743.IP "Ruby" 4
2697.IX Item "Ruby" 2744.IX Item "Ruby"
2698Tony Arcieri has written a ruby extension that offers access to a subset 2745Tony Arcieri has written a ruby extension that offers access to a subset
2699of the libev \s-1API\s0 and adds filehandle abstractions, asynchronous \s-1DNS\s0 and 2746of the libev \s-1API\s0 and adds file handle abstractions, asynchronous \s-1DNS\s0 and
2700more on top of it. It can be found via gem servers. Its homepage is at 2747more on top of it. It can be found via gem servers. Its homepage is at
2701<http://rev.rubyforge.org/>. 2748<http://rev.rubyforge.org/>.
2702.IP "D" 4 2749.IP "D" 4
2703.IX Item "D" 2750.IX Item "D"
2704Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to 2751Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to
2705be found at <http://git.llucax.com.ar/?p=software/ev.d.git;a=summary>. 2752be found at <http://git.llucax.com.ar/?p=software/ev.d.git;a=summary>.
2706.SH "MACRO MAGIC" 2753.SH "MACRO MAGIC"
2707.IX Header "MACRO MAGIC" 2754.IX Header "MACRO MAGIC"
2708Libev can be compiled with a variety of options, the most fundamantal 2755Libev can be compiled with a variety of options, the most fundamental
2709of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) 2756of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most)
2710functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. 2757functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument.
2711.PP 2758.PP
2712To make it easier to write programs that cope with either variant, the 2759To make it easier to write programs that cope with either variant, the
2713following macros are defined: 2760following macros are defined:
2717This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev 2764This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev
2718loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument, 2765loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument,
2719\&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example: 2766\&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example:
2720.Sp 2767.Sp
2721.Vb 3 2768.Vb 3
2722\& ev_unref (EV_A); 2769\& ev_unref (EV_A);
2723\& ev_timer_add (EV_A_ watcher); 2770\& ev_timer_add (EV_A_ watcher);
2724\& ev_loop (EV_A_ 0); 2771\& ev_loop (EV_A_ 0);
2725.Ve 2772.Ve
2726.Sp 2773.Sp
2727It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope, 2774It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope,
2728which is often provided by the following macro. 2775which is often provided by the following macro.
2729.ie n .IP """EV_P""\fR, \f(CW""EV_P_""" 4 2776.ie n .IP """EV_P""\fR, \f(CW""EV_P_""" 4
2732This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev 2779This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev
2733loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter, 2780loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter,
2734\&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example: 2781\&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example:
2735.Sp 2782.Sp
2736.Vb 2 2783.Vb 2
2737\& // this is how ev_unref is being declared 2784\& // this is how ev_unref is being declared
2738\& static void ev_unref (EV_P); 2785\& static void ev_unref (EV_P);
2739\& 2786\&
2740\& // this is how you can declare your typical callback 2787\& // this is how you can declare your typical callback
2741\& static void cb (EV_P_ ev_timer *w, int revents) 2788\& static void cb (EV_P_ ev_timer *w, int revents)
2742.Ve 2789.Ve
2743.Sp 2790.Sp
2744It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite 2791It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite
2745suitable for use with \f(CW\*(C`EV_A\*(C'\fR. 2792suitable for use with \f(CW\*(C`EV_A\*(C'\fR.
2746.ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4 2793.ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4
2762Example: Declare and initialise a check watcher, utilising the above 2809Example: Declare and initialise a check watcher, utilising the above
2763macros so it will work regardless of whether multiple loops are supported 2810macros so it will work regardless of whether multiple loops are supported
2764or not. 2811or not.
2765.PP 2812.PP
2766.Vb 5 2813.Vb 5
2767\& static void 2814\& static void
2768\& check_cb (EV_P_ ev_timer *w, int revents) 2815\& check_cb (EV_P_ ev_timer *w, int revents)
2769\& { 2816\& {
2770\& ev_check_stop (EV_A_ w); 2817\& ev_check_stop (EV_A_ w);
2771\& } 2818\& }
2772\& 2819\&
2773\& ev_check check; 2820\& ev_check check;
2774\& ev_check_init (&check, check_cb); 2821\& ev_check_init (&check, check_cb);
2775\& ev_check_start (EV_DEFAULT_ &check); 2822\& ev_check_start (EV_DEFAULT_ &check);
2776\& ev_loop (EV_DEFAULT_ 0); 2823\& ev_loop (EV_DEFAULT_ 0);
2777.Ve 2824.Ve
2778.SH "EMBEDDING" 2825.SH "EMBEDDING"
2779.IX Header "EMBEDDING" 2826.IX Header "EMBEDDING"
2780Libev can (and often is) directly embedded into host 2827Libev can (and often is) directly embedded into host
2781applications. Examples of applications that embed it include the Deliantra 2828applications. Examples of applications that embed it include the Deliantra
2787you can easily upgrade by simply copying (or having a checked-out copy of 2834you can easily upgrade by simply copying (or having a checked-out copy of
2788libev somewhere in your source tree). 2835libev somewhere in your source tree).
2789.Sh "\s-1FILESETS\s0" 2836.Sh "\s-1FILESETS\s0"
2790.IX Subsection "FILESETS" 2837.IX Subsection "FILESETS"
2791Depending on what features you need you need to include one or more sets of files 2838Depending on what features you need you need to include one or more sets of files
2792in your app. 2839in your application.
2793.PP 2840.PP
2794\fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR 2841\fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR
2795.IX Subsection "CORE EVENT LOOP" 2842.IX Subsection "CORE EVENT LOOP"
2796.PP 2843.PP
2797To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual 2844To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual
2798configuration (no autoconf): 2845configuration (no autoconf):
2799.PP 2846.PP
2800.Vb 2 2847.Vb 2
2801\& #define EV_STANDALONE 1 2848\& #define EV_STANDALONE 1
2802\& #include "ev.c" 2849\& #include "ev.c"
2803.Ve 2850.Ve
2804.PP 2851.PP
2805This will automatically include \fIev.h\fR, too, and should be done in a 2852This will automatically include \fIev.h\fR, too, and should be done in a
2806single C source file only to provide the function implementations. To use 2853single C source file only to provide the function implementations. To use
2807it, do the same for \fIev.h\fR in all files wishing to use this \s-1API\s0 (best 2854it, do the same for \fIev.h\fR in all files wishing to use this \s-1API\s0 (best
2808done by writing a wrapper around \fIev.h\fR that you can include instead and 2855done by writing a wrapper around \fIev.h\fR that you can include instead and
2809where you can put other configuration options): 2856where you can put other configuration options):
2810.PP 2857.PP
2811.Vb 2 2858.Vb 2
2812\& #define EV_STANDALONE 1 2859\& #define EV_STANDALONE 1
2813\& #include "ev.h" 2860\& #include "ev.h"
2814.Ve 2861.Ve
2815.PP 2862.PP
2816Both header files and implementation files can be compiled with a \*(C+ 2863Both header files and implementation files can be compiled with a \*(C+
2817compiler (at least, thats a stated goal, and breakage will be treated 2864compiler (at least, thats a stated goal, and breakage will be treated
2818as a bug). 2865as a bug).
2819.PP 2866.PP
2820You need the following files in your source tree, or in a directory 2867You need the following files in your source tree, or in a directory
2821in your include path (e.g. in libev/ when using \-Ilibev): 2868in your include path (e.g. in libev/ when using \-Ilibev):
2822.PP 2869.PP
2823.Vb 4 2870.Vb 4
2824\& ev.h 2871\& ev.h
2825\& ev.c 2872\& ev.c
2826\& ev_vars.h 2873\& ev_vars.h
2827\& ev_wrap.h 2874\& ev_wrap.h
2828\& 2875\&
2829\& ev_win32.c required on win32 platforms only 2876\& ev_win32.c required on win32 platforms only
2830\& 2877\&
2831\& ev_select.c only when select backend is enabled (which is enabled by default) 2878\& ev_select.c only when select backend is enabled (which is enabled by default)
2832\& ev_poll.c only when poll backend is enabled (disabled by default) 2879\& ev_poll.c only when poll backend is enabled (disabled by default)
2833\& ev_epoll.c only when the epoll backend is enabled (disabled by default) 2880\& ev_epoll.c only when the epoll backend is enabled (disabled by default)
2834\& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) 2881\& ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
2835\& ev_port.c only when the solaris port backend is enabled (disabled by default) 2882\& ev_port.c only when the solaris port backend is enabled (disabled by default)
2836.Ve 2883.Ve
2837.PP 2884.PP
2838\&\fIev.c\fR includes the backend files directly when enabled, so you only need 2885\&\fIev.c\fR includes the backend files directly when enabled, so you only need
2839to compile this single file. 2886to compile this single file.
2840.PP 2887.PP
2842.IX Subsection "LIBEVENT COMPATIBILITY API" 2889.IX Subsection "LIBEVENT COMPATIBILITY API"
2843.PP 2890.PP
2844To include the libevent compatibility \s-1API\s0, also include: 2891To include the libevent compatibility \s-1API\s0, also include:
2845.PP 2892.PP
2846.Vb 1 2893.Vb 1
2847\& #include "event.c" 2894\& #include "event.c"
2848.Ve 2895.Ve
2849.PP 2896.PP
2850in the file including \fIev.c\fR, and: 2897in the file including \fIev.c\fR, and:
2851.PP 2898.PP
2852.Vb 1 2899.Vb 1
2853\& #include "event.h" 2900\& #include "event.h"
2854.Ve 2901.Ve
2855.PP 2902.PP
2856in the files that want to use the libevent \s-1API\s0. This also includes \fIev.h\fR. 2903in the files that want to use the libevent \s-1API\s0. This also includes \fIev.h\fR.
2857.PP 2904.PP
2858You need the following additional files for this: 2905You need the following additional files for this:
2859.PP 2906.PP
2860.Vb 2 2907.Vb 2
2861\& event.h 2908\& event.h
2862\& event.c 2909\& event.c
2863.Ve 2910.Ve
2864.PP 2911.PP
2865\fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR 2912\fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR
2866.IX Subsection "AUTOCONF SUPPORT" 2913.IX Subsection "AUTOCONF SUPPORT"
2867.PP 2914.PP
2868Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your config in 2915Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your configuration in
2869whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your 2916whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your
2870\&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then 2917\&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then
2871include \fIconfig.h\fR and configure itself accordingly. 2918include \fIconfig.h\fR and configure itself accordingly.
2872.PP 2919.PP
2873For this of course you need the m4 file: 2920For this of course you need the m4 file:
2874.PP 2921.PP
2875.Vb 1 2922.Vb 1
2876\& libev.m4 2923\& libev.m4
2877.Ve 2924.Ve
2878.Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" 2925.Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0"
2879.IX Subsection "PREPROCESSOR SYMBOLS/MACROS" 2926.IX Subsection "PREPROCESSOR SYMBOLS/MACROS"
2880Libev can be configured via a variety of preprocessor symbols you have to 2927Libev can be configured via a variety of preprocessor symbols you have to
2881define before including any of its files. The default in the absense of 2928define before including any of its files. The default in the absence of
2882autoconf is noted for every option. 2929autoconf is noted for every option.
2883.IP "\s-1EV_STANDALONE\s0" 4 2930.IP "\s-1EV_STANDALONE\s0" 4
2884.IX Item "EV_STANDALONE" 2931.IX Item "EV_STANDALONE"
2885Must always be \f(CW1\fR if you do not use autoconf configuration, which 2932Must always be \f(CW1\fR if you do not use autoconf configuration, which
2886keeps libev from including \fIconfig.h\fR, and it also defines dummy 2933keeps libev from including \fIconfig.h\fR, and it also defines dummy
2888supported). It will also not define any of the structs usually found in 2935supported). It will also not define any of the structs usually found in
2889\&\fIevent.h\fR that are not directly supported by the libev core alone. 2936\&\fIevent.h\fR that are not directly supported by the libev core alone.
2890.IP "\s-1EV_USE_MONOTONIC\s0" 4 2937.IP "\s-1EV_USE_MONOTONIC\s0" 4
2891.IX Item "EV_USE_MONOTONIC" 2938.IX Item "EV_USE_MONOTONIC"
2892If defined to be \f(CW1\fR, libev will try to detect the availability of the 2939If defined to be \f(CW1\fR, libev will try to detect the availability of the
2893monotonic clock option at both compiletime and runtime. Otherwise no use 2940monotonic clock option at both compile time and runtime. Otherwise no use
2894of the monotonic clock option will be attempted. If you enable this, you 2941of the monotonic clock option will be attempted. If you enable this, you
2895usually have to link against librt or something similar. Enabling it when 2942usually have to link against librt or something similar. Enabling it when
2896the functionality isn't available is safe, though, although you have 2943the functionality isn't available is safe, though, although you have
2897to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR 2944to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR
2898function is hiding in (often \fI\-lrt\fR). 2945function is hiding in (often \fI\-lrt\fR).
2899.IP "\s-1EV_USE_REALTIME\s0" 4 2946.IP "\s-1EV_USE_REALTIME\s0" 4
2900.IX Item "EV_USE_REALTIME" 2947.IX Item "EV_USE_REALTIME"
2901If defined to be \f(CW1\fR, libev will try to detect the availability of the 2948If defined to be \f(CW1\fR, libev will try to detect the availability of the
2902realtime clock option at compiletime (and assume its availability at 2949real-time clock option at compile time (and assume its availability at
2903runtime if successful). Otherwise no use of the realtime clock option will 2950runtime if successful). Otherwise no use of the real-time clock option will
2904be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get 2951be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get
2905(CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See the 2952(CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See the
2906note about libraries in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though. 2953note about libraries in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though.
2907.IP "\s-1EV_USE_NANOSLEEP\s0" 4 2954.IP "\s-1EV_USE_NANOSLEEP\s0" 4
2908.IX Item "EV_USE_NANOSLEEP" 2955.IX Item "EV_USE_NANOSLEEP"
2916If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc 2963If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc
29172.7 or newer, otherwise disabled. 29642.7 or newer, otherwise disabled.
2918.IP "\s-1EV_USE_SELECT\s0" 4 2965.IP "\s-1EV_USE_SELECT\s0" 4
2919.IX Item "EV_USE_SELECT" 2966.IX Item "EV_USE_SELECT"
2920If undefined or defined to be \f(CW1\fR, libev will compile in support for the 2967If undefined or defined to be \f(CW1\fR, libev will compile in support for the
2921\&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at autodetection will be done: if no 2968\&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at auto-detection will be done: if no
2922other method takes over, select will be it. Otherwise the select backend 2969other method takes over, select will be it. Otherwise the select backend
2923will not be compiled in. 2970will not be compiled in.
2924.IP "\s-1EV_SELECT_USE_FD_SET\s0" 4 2971.IP "\s-1EV_SELECT_USE_FD_SET\s0" 4
2925.IX Item "EV_SELECT_USE_FD_SET" 2972.IX Item "EV_SELECT_USE_FD_SET"
2926If defined to \f(CW1\fR, then the select backend will use the system \f(CW\*(C`fd_set\*(C'\fR 2973If defined to \f(CW1\fR, then the select backend will use the system \f(CW\*(C`fd_set\*(C'\fR
2927structure. This is useful if libev doesn't compile due to a missing 2974structure. This is useful if libev doesn't compile due to a missing
2928\&\f(CW\*(C`NFDBITS\*(C'\fR or \f(CW\*(C`fd_mask\*(C'\fR definition or it misguesses the bitset layout on 2975\&\f(CW\*(C`NFDBITS\*(C'\fR or \f(CW\*(C`fd_mask\*(C'\fR definition or it mis-guesses the bitset layout on
2929exotic systems. This usually limits the range of file descriptors to some 2976exotic systems. This usually limits the range of file descriptors to some
2930low limit such as 1024 or might have other limitations (winsocket only 2977low limit such as 1024 or might have other limitations (winsocket only
2931allows 64 sockets). The \f(CW\*(C`FD_SETSIZE\*(C'\fR macro, set before compilation, might 2978allows 64 sockets). The \f(CW\*(C`FD_SETSIZE\*(C'\fR macro, set before compilation, might
2932influence the size of the \f(CW\*(C`fd_set\*(C'\fR used. 2979influence the size of the \f(CW\*(C`fd_set\*(C'\fR used.
2933.IP "\s-1EV_SELECT_IS_WINSOCKET\s0" 4 2980.IP "\s-1EV_SELECT_IS_WINSOCKET\s0" 4
297510 port style backend. Its availability will be detected at runtime, 302210 port style backend. Its availability will be detected at runtime,
2976otherwise another method will be used as fallback. This is the preferred 3023otherwise another method will be used as fallback. This is the preferred
2977backend for Solaris 10 systems. 3024backend for Solaris 10 systems.
2978.IP "\s-1EV_USE_DEVPOLL\s0" 4 3025.IP "\s-1EV_USE_DEVPOLL\s0" 4
2979.IX Item "EV_USE_DEVPOLL" 3026.IX Item "EV_USE_DEVPOLL"
2980reserved for future expansion, works like the \s-1USE\s0 symbols above. 3027Reserved for future expansion, works like the \s-1USE\s0 symbols above.
2981.IP "\s-1EV_USE_INOTIFY\s0" 4 3028.IP "\s-1EV_USE_INOTIFY\s0" 4
2982.IX Item "EV_USE_INOTIFY" 3029.IX Item "EV_USE_INOTIFY"
2983If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify 3030If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify
2984interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will 3031interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will
2985be detected at runtime. If undefined, it will be enabled if the headers 3032be detected at runtime. If undefined, it will be enabled if the headers
2990access is atomic with respect to other threads or signal contexts. No such 3037access is atomic with respect to other threads or signal contexts. No such
2991type is easily found in the C language, so you can provide your own type 3038type is easily found in the C language, so you can provide your own type
2992that you know is safe for your purposes. It is used both for signal handler \*(L"locking\*(R" 3039that you know is safe for your purposes. It is used both for signal handler \*(L"locking\*(R"
2993as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR watchers. 3040as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR watchers.
2994.Sp 3041.Sp
2995In the absense of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR 3042In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR
2996(from \fIsignal.h\fR), which is usually good enough on most platforms. 3043(from \fIsignal.h\fR), which is usually good enough on most platforms.
2997.IP "\s-1EV_H\s0" 4 3044.IP "\s-1EV_H\s0" 4
2998.IX Item "EV_H" 3045.IX Item "EV_H"
2999The name of the \fIev.h\fR header file used to include it. The default if 3046The name of the \fIev.h\fR header file used to include it. The default if
3000undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be 3047undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be
3035When doing priority-based operations, libev usually has to linearly search 3082When doing priority-based operations, libev usually has to linearly search
3036all the priorities, so having many of them (hundreds) uses a lot of space 3083all the priorities, so having many of them (hundreds) uses a lot of space
3037and time, so using the defaults of five priorities (\-2 .. +2) is usually 3084and time, so using the defaults of five priorities (\-2 .. +2) is usually
3038fine. 3085fine.
3039.Sp 3086.Sp
3040If your embedding app does not need any priorities, defining these both to 3087If your embedding application does not need any priorities, defining these both to
3041\&\f(CW0\fR will save some memory and cpu. 3088\&\f(CW0\fR will save some memory and \s-1CPU\s0.
3042.IP "\s-1EV_PERIODIC_ENABLE\s0" 4 3089.IP "\s-1EV_PERIODIC_ENABLE\s0" 4
3043.IX Item "EV_PERIODIC_ENABLE" 3090.IX Item "EV_PERIODIC_ENABLE"
3044If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If 3091If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If
3045defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of 3092defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of
3046code. 3093code.
3067defined to be \f(CW0\fR, then they are not. 3114defined to be \f(CW0\fR, then they are not.
3068.IP "\s-1EV_MINIMAL\s0" 4 3115.IP "\s-1EV_MINIMAL\s0" 4
3069.IX Item "EV_MINIMAL" 3116.IX Item "EV_MINIMAL"
3070If you need to shave off some kilobytes of code at the expense of some 3117If you need to shave off some kilobytes of code at the expense of some
3071speed, define this symbol to \f(CW1\fR. Currently this is used to override some 3118speed, define this symbol to \f(CW1\fR. Currently this is used to override some
3072inlining decisions, saves roughly 30% codesize of amd64. It also selects a 3119inlining decisions, saves roughly 30% code size on amd64. It also selects a
3073much smaller 2\-heap for timer management over the default 4\-heap. 3120much smaller 2\-heap for timer management over the default 4\-heap.
3074.IP "\s-1EV_PID_HASHSIZE\s0" 4 3121.IP "\s-1EV_PID_HASHSIZE\s0" 4
3075.IX Item "EV_PID_HASHSIZE" 3122.IX Item "EV_PID_HASHSIZE"
3076\&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by 3123\&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by
3077pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more 3124pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more
3086two). 3133two).
3087.IP "\s-1EV_USE_4HEAP\s0" 4 3134.IP "\s-1EV_USE_4HEAP\s0" 4
3088.IX Item "EV_USE_4HEAP" 3135.IX Item "EV_USE_4HEAP"
3089Heaps are not very cache-efficient. To improve the cache-efficiency of the 3136Heaps are not very cache-efficient. To improve the cache-efficiency of the
3090timer and periodics heap, libev uses a 4\-heap when this symbol is defined 3137timer and periodics heap, libev uses a 4\-heap when this symbol is defined
3091to \f(CW1\fR. The 4\-heap uses more complicated (longer) code but has a 3138to \f(CW1\fR. The 4\-heap uses more complicated (longer) code but has
3092noticable after performance with many (thousands) of watchers. 3139noticeably faster performance with many (thousands) of watchers.
3093.Sp 3140.Sp
3094The default is \f(CW1\fR unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set in which case it is \f(CW0\fR 3141The default is \f(CW1\fR unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set in which case it is \f(CW0\fR
3095(disabled). 3142(disabled).
3096.IP "\s-1EV_HEAP_CACHE_AT\s0" 4 3143.IP "\s-1EV_HEAP_CACHE_AT\s0" 4
3097.IX Item "EV_HEAP_CACHE_AT" 3144.IX Item "EV_HEAP_CACHE_AT"
3098Heaps are not very cache-efficient. To improve the cache-efficiency of the 3145Heaps are not very cache-efficient. To improve the cache-efficiency of the
3099timer and periodics heap, libev can cache the timestamp (\fIat\fR) within 3146timer and periodics heap, libev can cache the timestamp (\fIat\fR) within
3100the heap structure (selected by defining \f(CW\*(C`EV_HEAP_CACHE_AT\*(C'\fR to \f(CW1\fR), 3147the heap structure (selected by defining \f(CW\*(C`EV_HEAP_CACHE_AT\*(C'\fR to \f(CW1\fR),
3101which uses 8\-12 bytes more per watcher and a few hundred bytes more code, 3148which uses 8\-12 bytes more per watcher and a few hundred bytes more code,
3102but avoids random read accesses on heap changes. This noticably improves 3149but avoids random read accesses on heap changes. This improves performance
3103performance noticably with with many (hundreds) of watchers. 3150noticeably with with many (hundreds) of watchers.
3104.Sp 3151.Sp
3105The default is \f(CW1\fR unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set in which case it is \f(CW0\fR 3152The default is \f(CW1\fR unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set in which case it is \f(CW0\fR
3106(disabled). 3153(disabled).
3154.IP "\s-1EV_VERIFY\s0" 4
3155.IX Item "EV_VERIFY"
3156Controls how much internal verification (see \f(CW\*(C`ev_loop_verify ()\*(C'\fR) will
3157be done: If set to \f(CW0\fR, no internal verification code will be compiled
3158in. If set to \f(CW1\fR, then verification code will be compiled in, but not
3159called. If set to \f(CW2\fR, then the internal verification code will be
3160called once per loop, which can slow down libev. If set to \f(CW3\fR, then the
3161verification code will be called very frequently, which will slow down
3162libev considerably.
3163.Sp
3164The default is \f(CW1\fR, unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set, in which case it will be
3165\&\f(CW0.\fR
3107.IP "\s-1EV_COMMON\s0" 4 3166.IP "\s-1EV_COMMON\s0" 4
3108.IX Item "EV_COMMON" 3167.IX Item "EV_COMMON"
3109By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining 3168By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining
3110this macro to a something else you can include more and other types of 3169this macro to a something else you can include more and other types of
3111members. You have to define it each time you include one of the files, 3170members. You have to define it each time you include one of the files,
3112though, and it must be identical each time. 3171though, and it must be identical each time.
3113.Sp 3172.Sp
3114For example, the perl \s-1EV\s0 module uses something like this: 3173For example, the perl \s-1EV\s0 module uses something like this:
3115.Sp 3174.Sp
3116.Vb 3 3175.Vb 3
3117\& #define EV_COMMON \e 3176\& #define EV_COMMON \e
3118\& SV *self; /* contains this struct */ \e 3177\& SV *self; /* contains this struct */ \e
3119\& SV *cb_sv, *fh /* note no trailing ";" */ 3178\& SV *cb_sv, *fh /* note no trailing ";" */
3120.Ve 3179.Ve
3121.IP "\s-1EV_CB_DECLARE\s0 (type)" 4 3180.IP "\s-1EV_CB_DECLARE\s0 (type)" 4
3122.IX Item "EV_CB_DECLARE (type)" 3181.IX Item "EV_CB_DECLARE (type)"
3123.PD 0 3182.PD 0
3124.IP "\s-1EV_CB_INVOKE\s0 (watcher, revents)" 4 3183.IP "\s-1EV_CB_INVOKE\s0 (watcher, revents)" 4
3132their default definitions. One possible use for overriding these is to 3191their default definitions. One possible use for overriding these is to
3133avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use 3192avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use
3134method calls instead of plain function calls in \*(C+. 3193method calls instead of plain function calls in \*(C+.
3135.Sh "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" 3194.Sh "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0"
3136.IX Subsection "EXPORTED API SYMBOLS" 3195.IX Subsection "EXPORTED API SYMBOLS"
3137If you need to re-export the \s-1API\s0 (e.g. via a dll) and you need a list of 3196If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of
3138exported symbols, you can use the provided \fISymbol.*\fR files which list 3197exported symbols, you can use the provided \fISymbol.*\fR files which list
3139all public symbols, one per line: 3198all public symbols, one per line:
3140.PP 3199.PP
3141.Vb 2 3200.Vb 2
3142\& Symbols.ev for libev proper 3201\& Symbols.ev for libev proper
3143\& Symbols.event for the libevent emulation 3202\& Symbols.event for the libevent emulation
3144.Ve 3203.Ve
3145.PP 3204.PP
3146This can also be used to rename all public symbols to avoid clashes with 3205This can also be used to rename all public symbols to avoid clashes with
3147multiple versions of libev linked together (which is obviously bad in 3206multiple versions of libev linked together (which is obviously bad in
3148itself, but sometimes it is inconvinient to avoid this). 3207itself, but sometimes it is inconvenient to avoid this).
3149.PP 3208.PP
3150A sed command like this will create wrapper \f(CW\*(C`#define\*(C'\fR's that you need to 3209A sed command like this will create wrapper \f(CW\*(C`#define\*(C'\fR's that you need to
3151include before including \fIev.h\fR: 3210include before including \fIev.h\fR:
3152.PP 3211.PP
3153.Vb 1 3212.Vb 1
3174.PP 3233.PP
3175The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file 3234The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file
3176that everybody includes and which overrides some configure choices: 3235that everybody includes and which overrides some configure choices:
3177.PP 3236.PP
3178.Vb 9 3237.Vb 9
3179\& #define EV_MINIMAL 1 3238\& #define EV_MINIMAL 1
3180\& #define EV_USE_POLL 0 3239\& #define EV_USE_POLL 0
3181\& #define EV_MULTIPLICITY 0 3240\& #define EV_MULTIPLICITY 0
3182\& #define EV_PERIODIC_ENABLE 0 3241\& #define EV_PERIODIC_ENABLE 0
3183\& #define EV_STAT_ENABLE 0 3242\& #define EV_STAT_ENABLE 0
3184\& #define EV_FORK_ENABLE 0 3243\& #define EV_FORK_ENABLE 0
3185\& #define EV_CONFIG_H <config.h> 3244\& #define EV_CONFIG_H <config.h>
3186\& #define EV_MINPRI 0 3245\& #define EV_MINPRI 0
3187\& #define EV_MAXPRI 0 3246\& #define EV_MAXPRI 0
3188\& 3247\&
3189\& #include "ev++.h" 3248\& #include "ev++.h"
3190.Ve 3249.Ve
3191.PP 3250.PP
3192And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled: 3251And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled:
3193.PP 3252.PP
3194.Vb 2 3253.Vb 2
3195\& #include "ev_cpp.h" 3254\& #include "ev_cpp.h"
3196\& #include "ev.c" 3255\& #include "ev.c"
3197.Ve 3256.Ve
3198.SH "THREADS AND COROUTINES" 3257.SH "THREADS AND COROUTINES"
3199.IX Header "THREADS AND COROUTINES" 3258.IX Header "THREADS AND COROUTINES"
3200.Sh "\s-1THREADS\s0" 3259.Sh "\s-1THREADS\s0"
3201.IX Subsection "THREADS" 3260.IX Subsection "THREADS"
3202Libev itself is completely threadsafe, but it uses no locking. This 3261Libev itself is completely thread-safe, but it uses no locking. This
3203means that you can use as many loops as you want in parallel, as long as 3262means that you can use as many loops as you want in parallel, as long as
3204only one thread ever calls into one libev function with the same loop 3263only one thread ever calls into one libev function with the same loop
3205parameter. 3264parameter.
3206.PP 3265.PP
3207Or put differently: calls with different loop parameters can be done in 3266Or put differently: calls with different loop parameters can be done in
3212.PP 3271.PP
3213If you want to know which design is best for your problem, then I cannot 3272If you want to know which design is best for your problem, then I cannot
3214help you but by giving some generic advice: 3273help you but by giving some generic advice:
3215.IP "\(bu" 4 3274.IP "\(bu" 4
3216most applications have a main thread: use the default libev loop 3275most applications have a main thread: use the default libev loop
3217in that thread, or create a seperate thread running only the default loop. 3276in that thread, or create a separate thread running only the default loop.
3218.Sp 3277.Sp
3219This helps integrating other libraries or software modules that use libev 3278This helps integrating other libraries or software modules that use libev
3220themselves and don't care/know about threading. 3279themselves and don't care/know about threading.
3221.IP "\(bu" 4 3280.IP "\(bu" 4
3222one loop per thread is usually a good model. 3281one loop per thread is usually a good model.
3223.Sp 3282.Sp
3224Doing this is almost never wrong, sometimes a better-performance model 3283Doing this is almost never wrong, sometimes a better-performance model
3225exists, but it is always a good start. 3284exists, but it is always a good start.
3226.IP "\(bu" 4 3285.IP "\(bu" 4
3227other models exist, such as the leader/follower pattern, where one 3286other models exist, such as the leader/follower pattern, where one
3228loop is handed through multiple threads in a kind of round-robbin fashion. 3287loop is handed through multiple threads in a kind of round-robin fashion.
3229.Sp 3288.Sp
3230Chosing a model is hard \- look around, learn, know that usually you cna do 3289Choosing a model is hard \- look around, learn, know that usually you can do
3231better than you currently do :\-) 3290better than you currently do :\-)
3232.IP "\(bu" 4 3291.IP "\(bu" 4
3233often you need to talk to some other thread which blocks in the 3292often you need to talk to some other thread which blocks in the
3234event loop \- \f(CW\*(C`ev_async\*(C'\fR watchers can be used to wake them up from other 3293event loop \- \f(CW\*(C`ev_async\*(C'\fR watchers can be used to wake them up from other
3235threads safely (or from signal contexts...). 3294threads safely (or from signal contexts...).
3236.Sh "\s-1COROUTINES\s0" 3295.Sh "\s-1COROUTINES\s0"
3237.IX Subsection "COROUTINES" 3296.IX Subsection "COROUTINES"
3238Libev is much more accomodating to coroutines (\*(L"cooperative threads\*(R"): 3297Libev is much more accommodating to coroutines (\*(L"cooperative threads\*(R"):
3239libev fully supports nesting calls to it's functions from different 3298libev fully supports nesting calls to it's functions from different
3240coroutines (e.g. you can call \f(CW\*(C`ev_loop\*(C'\fR on the same loop from two 3299coroutines (e.g. you can call \f(CW\*(C`ev_loop\*(C'\fR on the same loop from two
3241different coroutines and switch freely between both coroutines running the 3300different coroutines and switch freely between both coroutines running the
3242loop, as long as you don't confuse yourself). The only exception is that 3301loop, as long as you don't confuse yourself). The only exception is that
3243you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. 3302you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks.
3283fixed position in the storage array. 3342fixed position in the storage array.
3284.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4 3343.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4
3285.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 3344.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)"
3286A change means an I/O watcher gets started or stopped, which requires 3345A change means an I/O watcher gets started or stopped, which requires
3287libev to recalculate its status (and possibly tell the kernel, depending 3346libev to recalculate its status (and possibly tell the kernel, depending
3288on backend and wether \f(CW\*(C`ev_io_set\*(C'\fR was used). 3347on backend and whether \f(CW\*(C`ev_io_set\*(C'\fR was used).
3289.IP "Activating one watcher (putting it into the pending state): O(1)" 4 3348.IP "Activating one watcher (putting it into the pending state): O(1)" 4
3290.IX Item "Activating one watcher (putting it into the pending state): O(1)" 3349.IX Item "Activating one watcher (putting it into the pending state): O(1)"
3291.PD 0 3350.PD 0
3292.IP "Priority handling: O(number_of_priorities)" 4 3351.IP "Priority handling: O(number_of_priorities)" 4
3293.IX Item "Priority handling: O(number_of_priorities)" 3352.IX Item "Priority handling: O(number_of_priorities)"
3302.IP "Processing ev_async_send: O(number_of_async_watchers)" 4 3361.IP "Processing ev_async_send: O(number_of_async_watchers)" 4
3303.IX Item "Processing ev_async_send: O(number_of_async_watchers)" 3362.IX Item "Processing ev_async_send: O(number_of_async_watchers)"
3304.IP "Processing signals: O(max_signal_number)" 4 3363.IP "Processing signals: O(max_signal_number)" 4
3305.IX Item "Processing signals: O(max_signal_number)" 3364.IX Item "Processing signals: O(max_signal_number)"
3306.PD 3365.PD
3307Sending involves a syscall \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR 3366Sending involves a system call \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR
3308calls in the current loop iteration. Checking for async and signal events 3367calls in the current loop iteration. Checking for async and signal events
3309involves iterating over all running async watchers or all signal numbers. 3368involves iterating over all running async watchers or all signal numbers.
3310.SH "Win32 platform limitations and workarounds" 3369.SH "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS"
3311.IX Header "Win32 platform limitations and workarounds" 3370.IX Header "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS"
3312Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev 3371Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev
3313requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 3372requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0
3314model. Libev still offers limited functionality on this platform in 3373model. Libev still offers limited functionality on this platform in
3315the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket 3374the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket
3316descriptors. This only applies when using Win32 natively, not when using 3375descriptors. This only applies when using Win32 natively, not when using
3322way (note also that glib is the slowest event library known to man). 3381way (note also that glib is the slowest event library known to man).
3323.PP 3382.PP
3324There is no supported compilation method available on windows except 3383There is no supported compilation method available on windows except
3325embedding it into other applications. 3384embedding it into other applications.
3326.PP 3385.PP
3386Not a libev limitation but worth mentioning: windows apparently doesn't
3387accept large writes: instead of resulting in a partial write, windows will
3388either accept everything or return \f(CW\*(C`ENOBUFS\*(C'\fR if the buffer is too large,
3389so make sure you only write small amounts into your sockets (less than a
3390megabyte seems safe, but thsi apparently depends on the amount of memory
3391available).
3392.PP
3327Due to the many, low, and arbitrary limits on the win32 platform and 3393Due to the many, low, and arbitrary limits on the win32 platform and
3328the abysmal performance of winsockets, using a large number of sockets 3394the abysmal performance of winsockets, using a large number of sockets
3329is not recommended (and not reasonable). If your program needs to use 3395is not recommended (and not reasonable). If your program needs to use
3330more than a hundred or so sockets, then likely it needs to use a totally 3396more than a hundred or so sockets, then likely it needs to use a totally
3331different implementation for windows, as libev offers the \s-1POSIX\s0 readyness 3397different implementation for windows, as libev offers the \s-1POSIX\s0 readiness
3332notification model, which cannot be implemented efficiently on windows 3398notification model, which cannot be implemented efficiently on windows
3333(microsoft monopoly games). 3399(Microsoft monopoly games).
3400.PP
3401A typical way to use libev under windows is to embed it (see the embedding
3402section for details) and use the following \fIevwrap.h\fR header file instead
3403of \fIev.h\fR:
3404.PP
3405.Vb 2
3406\& #define EV_STANDALONE /* keeps ev from requiring config.h */
3407\& #define EV_SELECT_IS_WINSOCKET 1 /* configure libev for windows select */
3408\&
3409\& #include "ev.h"
3410.Ve
3411.PP
3412And compile the following \fIevwrap.c\fR file into your project (make sure
3413you do \fInot\fR compile the \fIev.c\fR or any other embedded soruce files!):
3414.PP
3415.Vb 2
3416\& #include "evwrap.h"
3417\& #include "ev.c"
3418.Ve
3334.IP "The winsocket select function" 4 3419.IP "The winsocket select function" 4
3335.IX Item "The winsocket select function" 3420.IX Item "The winsocket select function"
3336The winsocket \f(CW\*(C`select\*(C'\fR function doesn't follow \s-1POSIX\s0 in that it requires 3421The winsocket \f(CW\*(C`select\*(C'\fR function doesn't follow \s-1POSIX\s0 in that it
3337socket \fIhandles\fR and not socket \fIfile descriptors\fR. This makes select 3422requires socket \fIhandles\fR and not socket \fIfile descriptors\fR (it is
3338very inefficient, and also requires a mapping from file descriptors 3423also extremely buggy). This makes select very inefficient, and also
3339to socket handles. See the discussion of the \f(CW\*(C`EV_SELECT_USE_FD_SET\*(C'\fR, 3424requires a mapping from file descriptors to socket handles (the Microsoft
3340\&\f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR and \f(CW\*(C`EV_FD_TO_WIN32_HANDLE\*(C'\fR preprocessor 3425C runtime provides the function \f(CW\*(C`_open_osfhandle\*(C'\fR for this). See the
3341symbols for more info. 3426discussion of the \f(CW\*(C`EV_SELECT_USE_FD_SET\*(C'\fR, \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR and
3427\&\f(CW\*(C`EV_FD_TO_WIN32_HANDLE\*(C'\fR preprocessor symbols for more info.
3342.Sp 3428.Sp
3343The configuration for a \*(L"naked\*(R" win32 using the microsoft runtime 3429The configuration for a \*(L"naked\*(R" win32 using the Microsoft runtime
3344libraries and raw winsocket select is: 3430libraries and raw winsocket select is:
3345.Sp 3431.Sp
3346.Vb 2 3432.Vb 2
3347\& #define EV_USE_SELECT 1 3433\& #define EV_USE_SELECT 1
3348\& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ 3434\& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
3349.Ve 3435.Ve
3350.Sp 3436.Sp
3351Note that winsockets handling of fd sets is O(n), so you can easily get a 3437Note that winsockets handling of fd sets is O(n), so you can easily get a
3352complexity in the O(nA\*^X) range when using win32. 3438complexity in the O(nA\*^X) range when using win32.
3353.IP "Limited number of file descriptors" 4 3439.IP "Limited number of file descriptors" 4
3354.IX Item "Limited number of file descriptors" 3440.IX Item "Limited number of file descriptors"
3355Windows has numerous arbitrary (and low) limits on things. 3441Windows has numerous arbitrary (and low) limits on things.
3356.Sp 3442.Sp
3357Early versions of winsocket's select only supported waiting for a maximum 3443Early versions of winsocket's select only supported waiting for a maximum
3358of \f(CW64\fR handles (probably owning to the fact that all windows kernels 3444of \f(CW64\fR handles (probably owning to the fact that all windows kernels
3359can only wait for \f(CW64\fR things at the same time internally; microsoft 3445can only wait for \f(CW64\fR things at the same time internally; Microsoft
3360recommends spawning a chain of threads and wait for 63 handles and the 3446recommends spawning a chain of threads and wait for 63 handles and the
3361previous thread in each. Great). 3447previous thread in each. Great).
3362.Sp 3448.Sp
3363Newer versions support more handles, but you need to define \f(CW\*(C`FD_SETSIZE\*(C'\fR 3449Newer versions support more handles, but you need to define \f(CW\*(C`FD_SETSIZE\*(C'\fR
3364to some high number (e.g. \f(CW2048\fR) before compiling the winsocket select 3450to some high number (e.g. \f(CW2048\fR) before compiling the winsocket select
3365call (which might be in libev or elsewhere, for example, perl does its own 3451call (which might be in libev or elsewhere, for example, perl does its own
3366select emulation on windows). 3452select emulation on windows).
3367.Sp 3453.Sp
3368Another limit is the number of file descriptors in the microsoft runtime 3454Another limit is the number of file descriptors in the Microsoft runtime
3369libraries, which by default is \f(CW64\fR (there must be a hidden \fI64\fR fetish 3455libraries, which by default is \f(CW64\fR (there must be a hidden \fI64\fR fetish
3370or something like this inside microsoft). You can increase this by calling 3456or something like this inside Microsoft). You can increase this by calling
3371\&\f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR (another 3457\&\f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR (another
3372arbitrary limit), but is broken in many versions of the microsoft runtime 3458arbitrary limit), but is broken in many versions of the Microsoft runtime
3373libraries. 3459libraries.
3374.Sp 3460.Sp
3375This might get you to about \f(CW512\fR or \f(CW2048\fR sockets (depending on 3461This might get you to about \f(CW512\fR or \f(CW2048\fR sockets (depending on
3376windows version and/or the phase of the moon). To get more, you need to 3462windows version and/or the phase of the moon). To get more, you need to
3377wrap all I/O functions and provide your own fd management, but the cost of 3463wrap all I/O functions and provide your own fd management, but the cost of
3378calling select (O(nA\*^X)) will likely make this unworkable. 3464calling select (O(nA\*^X)) will likely make this unworkable.
3379.SH "PORTABILITY REQUIREMENTS" 3465.SH "PORTABILITY REQUIREMENTS"
3380.IX Header "PORTABILITY REQUIREMENTS" 3466.IX Header "PORTABILITY REQUIREMENTS"
3381In addition to a working ISO-C implementation, libev relies on a few 3467In addition to a working ISO-C implementation, libev relies on a few
3382additional extensions: 3468additional extensions:
3469.ie n .IP """void (*)(ev_watcher_type *, int revents)""\fR must have compatible calling conventions regardless of \f(CW""ev_watcher_type *""." 4
3470.el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4
3471.IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *."
3472Libev assumes not only that all watcher pointers have the same internal
3473structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO\s0 C for example), but it also
3474assumes that the same (machine) code can be used to call any watcher
3475callback: The watcher callbacks have different type signatures, but libev
3476calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally.
3383.ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4 3477.ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4
3384.el .IP "\f(CWsig_atomic_t volatile\fR must be thread-atomic as well" 4 3478.el .IP "\f(CWsig_atomic_t volatile\fR must be thread-atomic as well" 4
3385.IX Item "sig_atomic_t volatile must be thread-atomic as well" 3479.IX Item "sig_atomic_t volatile must be thread-atomic as well"
3386The type \f(CW\*(C`sig_atomic_t volatile\*(C'\fR (or whatever is defined as 3480The type \f(CW\*(C`sig_atomic_t volatile\*(C'\fR (or whatever is defined as
3387\&\f(CW\*(C`EV_ATOMIC_T\*(C'\fR) must be atomic w.r.t. accesses from different 3481\&\f(CW\*(C`EV_ATOMIC_T\*(C'\fR) must be atomic w.r.t. accesses from different
3415have at least 51 bits of mantissa (and 9 bits of exponent), which is good 3509have at least 51 bits of mantissa (and 9 bits of exponent), which is good
3416enough for at least into the year 4000. This requirement is fulfilled by 3510enough for at least into the year 4000. This requirement is fulfilled by
3417implementations implementing \s-1IEEE\s0 754 (basically all existing ones). 3511implementations implementing \s-1IEEE\s0 754 (basically all existing ones).
3418.PP 3512.PP
3419If you know of other additional requirements drop me a note. 3513If you know of other additional requirements drop me a note.
3514.SH "COMPILER WARNINGS"
3515.IX Header "COMPILER WARNINGS"
3516Depending on your compiler and compiler settings, you might get no or a
3517lot of warnings when compiling libev code. Some people are apparently
3518scared by this.
3519.PP
3520However, these are unavoidable for many reasons. For one, each compiler
3521has different warnings, and each user has different tastes regarding
3522warning options. \*(L"Warn-free\*(R" code therefore cannot be a goal except when
3523targeting a specific compiler and compiler-version.
3524.PP
3525Another reason is that some compiler warnings require elaborate
3526workarounds, or other changes to the code that make it less clear and less
3527maintainable.
3528.PP
3529And of course, some compiler warnings are just plain stupid, or simply
3530wrong (because they don't actually warn about the condition their message
3531seems to warn about).
3532.PP
3533While libev is written to generate as few warnings as possible,
3534\&\*(L"warn-free\*(R" code is not a goal, and it is recommended not to build libev
3535with any compiler warnings enabled unless you are prepared to cope with
3536them (e.g. by ignoring them). Remember that warnings are just that:
3537warnings, not errors, or proof of bugs.
3538.SH "VALGRIND"
3539.IX Header "VALGRIND"
3540Valgrind has a special section here because it is a popular tool that is
3541highly useful, but valgrind reports are very hard to interpret.
3542.PP
3543If you think you found a bug (memory leak, uninitialised data access etc.)
3544in libev, then check twice: If valgrind reports something like:
3545.PP
3546.Vb 3
3547\& ==2274== definitely lost: 0 bytes in 0 blocks.
3548\& ==2274== possibly lost: 0 bytes in 0 blocks.
3549\& ==2274== still reachable: 256 bytes in 1 blocks.
3550.Ve
3551.PP
3552Then there is no memory leak. Similarly, under some circumstances,
3553valgrind might report kernel bugs as if it were a bug in libev, or it
3554might be confused (it is a very good tool, but only a tool).
3555.PP
3556If you are unsure about something, feel free to contact the mailing list
3557with the full valgrind report and an explanation on why you think this is
3558a bug in libev. However, don't be annoyed when you get a brisk \*(L"this is
3559no bug\*(R" answer and take the chance of learning how to interpret valgrind
3560properly.
3561.PP
3562If you need, for some reason, empty reports from valgrind for your project
3563I suggest using suppression lists.
3420.SH "AUTHOR" 3564.SH "AUTHOR"
3421.IX Header "AUTHOR" 3565.IX Header "AUTHOR"
3422Marc Lehmann <libev@schmorp.de>. 3566Marc Lehmann <libev@schmorp.de>.
3423.SH "POD ERRORS" 3567.SH "POD ERRORS"
3424.IX Header "POD ERRORS" 3568.IX Header "POD ERRORS"
3425Hey! \fBThe above document had some coding errors, which are explained below:\fR 3569Hey! \fBThe above document had some coding errors, which are explained below:\fR
3426.IP "Around line 3052:" 4 3570.IP "Around line 3116:" 4
3427.IX Item "Around line 3052:" 3571.IX Item "Around line 3116:"
3428You forgot a '=back' before '=head2' 3572You forgot a '=back' before '=head2'

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