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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 "2008-05-22" "libev-3.41" "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" 257.SH "ERROR HANDLING"
258.IX Header "ERROR HANDLING" 258.IX Header "ERROR HANDLING"
259Libev knows three classes of errors: operating system errors, usage errors 259Libev knows three classes of errors: operating system errors, usage errors
260and internal errors (bugs). 260and internal errors (bugs).
261.PP 261.PP
262When libev catches an operating system error it cannot handle (for example 262When libev catches an operating system error it cannot handle (for example
263a syscall indicating a condition libev cannot fix), it calls the callback 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 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 265abort. The default is to print a diagnostic message and to call \f(CW\*(C`abort
266()\*(C'\fR. 266()\*(C'\fR.
267.PP 267.PP
268When libev detects a usage error such as a negative timer interval, then 268When libev detects a usage error such as a negative timer interval, then
284you actually want to know. 284you actually want to know.
285.IP "ev_sleep (ev_tstamp interval)" 4 285.IP "ev_sleep (ev_tstamp interval)" 4
286.IX Item "ev_sleep (ev_tstamp interval)" 286.IX Item "ev_sleep (ev_tstamp interval)"
287Sleep for the given interval: The current thread will be blocked until 287Sleep for the given interval: The current thread will be blocked until
288either it is interrupted or the given time interval has passed. Basically 288either it is interrupted or the given time interval has passed. Basically
289this is a subsecond-resolution \f(CW\*(C`sleep ()\*(C'\fR. 289this is a sub-second-resolution \f(CW\*(C`sleep ()\*(C'\fR.
290.IP "int ev_version_major ()" 4 290.IP "int ev_version_major ()" 4
291.IX Item "int ev_version_major ()" 291.IX Item "int ev_version_major ()"
292.PD 0 292.PD 0
293.IP "int ev_version_minor ()" 4 293.IP "int ev_version_minor ()" 4
294.IX Item "int ev_version_minor ()" 294.IX Item "int ev_version_minor ()"
309.Sp 309.Sp
310Example: Make sure we haven't accidentally been linked against the wrong 310Example: Make sure we haven't accidentally been linked against the wrong
311version. 311version.
312.Sp 312.Sp
313.Vb 3 313.Vb 3
314\& assert (("libev version mismatch", 314\& assert (("libev version mismatch",
315\& ev_version_major () == EV_VERSION_MAJOR 315\& ev_version_major () == EV_VERSION_MAJOR
316\& && ev_version_minor () >= EV_VERSION_MINOR)); 316\& && ev_version_minor () >= EV_VERSION_MINOR));
317.Ve 317.Ve
318.IP "unsigned int ev_supported_backends ()" 4 318.IP "unsigned int ev_supported_backends ()" 4
319.IX Item "unsigned int ev_supported_backends ()" 319.IX Item "unsigned int ev_supported_backends ()"
320Return 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
321value) compiled into this binary of libev (independent of their 321value) compiled into this binary of libev (independent of their
324.Sp 324.Sp
325Example: 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
326a 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
327.Sp 327.Sp
328.Vb 2 328.Vb 2
329\& assert (("sorry, no epoll, no sex", 329\& assert (("sorry, no epoll, no sex",
330\& ev_supported_backends () & EVBACKEND_EPOLL)); 330\& ev_supported_backends () & EVBACKEND_EPOLL));
331.Ve 331.Ve
332.IP "unsigned int ev_recommended_backends ()" 4 332.IP "unsigned int ev_recommended_backends ()" 4
333.IX Item "unsigned int ev_recommended_backends ()" 333.IX Item "unsigned int ev_recommended_backends ()"
334Return 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
335recommended for this platform. This set is often smaller than the one 335recommended for this platform. This set is often smaller than the one
336returned 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
337most BSDs and will not be autodetected unless you explicitly request it 337most BSDs and will not be auto-detected unless you explicitly request it
338(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
339libev will probe for if you specify no backends explicitly. 339libev will probe for if you specify no backends explicitly.
340.IP "unsigned int ev_embeddable_backends ()" 4 340.IP "unsigned int ev_embeddable_backends ()" 4
341.IX Item "unsigned int ev_embeddable_backends ()" 341.IX Item "unsigned int ev_embeddable_backends ()"
342Returns 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
383\& ... 383\& ...
384\& ev_set_allocator (persistent_realloc); 384\& ev_set_allocator (persistent_realloc);
385.Ve 385.Ve
386.IP "ev_set_syserr_cb (void (*cb)(const char *msg));" 4 386.IP "ev_set_syserr_cb (void (*cb)(const char *msg));" 4
387.IX Item "ev_set_syserr_cb (void (*cb)(const char *msg));" 387.IX Item "ev_set_syserr_cb (void (*cb)(const char *msg));"
388Set the callback function to call on a retryable syscall error (such 388Set the callback function to call on a retryable system call error (such
389as failed select, poll, epoll_wait). The message is a printable string 389as failed select, poll, epoll_wait). The message is a printable string
390indicating the system call or subsystem causing the problem. If this 390indicating the system call or subsystem causing the problem. If this
391callback 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
392matter what, when it returns. That is, libev will generally retry the 392matter what, when it returns. That is, libev will generally retry the
393requested 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
394(such as abort). 394(such as abort).
395.Sp 395.Sp
396Example: This is basically the same thing that libev does internally, too. 396Example: This is basically the same thing that libev does internally, too.
425from 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,
426as loops cannot bes hared easily between threads anyway). 426as loops cannot bes hared easily between threads anyway).
427.Sp 427.Sp
428The 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
429\&\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
430for \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
431create 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
432can 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
433\&\f(CW\*(C`ev_default_init\*(C'\fR. 433\&\f(CW\*(C`ev_default_init\*(C'\fR.
434.Sp 434.Sp
435The flags argument can be used to specify special behaviour or specific 435The flags argument can be used to specify special behaviour or specific
443The 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
444thing, believe me). 444thing, believe me).
445.ie n .IP """EVFLAG_NOENV""" 4 445.ie n .IP """EVFLAG_NOENV""" 4
446.el .IP "\f(CWEVFLAG_NOENV\fR" 4 446.el .IP "\f(CWEVFLAG_NOENV\fR" 4
447.IX Item "EVFLAG_NOENV" 447.IX Item "EVFLAG_NOENV"
448If 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
449or setgid) then libev will \fInot\fR look at the environment variable 449or setgid) then libev will \fInot\fR look at the environment variable
450\&\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
451override 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
452useful 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
453around bugs. 453around bugs.
460.Sp 460.Sp
461This 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,
462and 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
463iterations and little real work, but is usually not noticeable (on my 463iterations and little real work, but is usually not noticeable (on my
464GNU/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
465without 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
466\&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster). 466\&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster).
467.Sp 467.Sp
468The 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
469forget about forgetting to tell libev about forking) when you use this 469forget about forgetting to tell libev about forking) when you use this
470flag. 470flag.
471.Sp 471.Sp
472This 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
473environment variable. 473environment variable.
474.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 474.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4
475.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
476.IX Item "EVBACKEND_SELECT (value 1, portable select backend)" 476.IX Item "EVBACKEND_SELECT (value 1, portable select backend)"
477This 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
479but 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
480using 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
481usually the fastest backend for a low number of (low-numbered :) fds. 481usually the fastest backend for a low number of (low-numbered :) fds.
482.Sp 482.Sp
483To 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
484parallelity (most of the file descriptors should be busy). If you are 484parallelism (most of the file descriptors should be busy). If you are
485writing 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
486connections as possible during one iteration. You might also want to have 486connections as possible during one iteration. You might also want to have
487a 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
488readiness notifications you get per iteration. 488readiness notifications you get per iteration.
489.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
501For 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,
502but it scales phenomenally better. While poll and select usually scale 502but it scales phenomenally better. While poll and select usually scale
503like 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),
504epoll 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
505of shortcomings, such as silently dropping events in some hard-to-detect 505of shortcomings, such as silently dropping events in some hard-to-detect
506cases 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
507support for dup. 507support for dup.
508.Sp 508.Sp
509While 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
510will 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
511(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
512best 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
513very well if you register events for both fds. 513very well if you register events for both fds.
514.Sp 514.Sp
515Please note that epoll sometimes generates spurious notifications, so you 515Please note that epoll sometimes generates spurious notifications, so you
518.Sp 518.Sp
519Best performance from this backend is achieved by not unregistering all 519Best performance from this backend is achieved by not unregistering all
520watchers 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.
521keep at least one watcher active per fd at all times. 521keep at least one watcher active per fd at all times.
522.Sp 522.Sp
523While nominally embeddeble in other event loops, this feature is broken in 523While nominally embeddable in other event loops, this feature is broken in
524all kernel versions tested so far. 524all kernel versions tested so far.
525.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
526.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
527.IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" 527.IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)"
528Kqueue deserves special mention, as at the time of this writing, it 528Kqueue deserves special mention, as at the time of this writing, it
529was 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
530with anything but sockets and pipes, except on Darwin, where of course 530with anything but sockets and pipes, except on Darwin, where of course
531it'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"
532unless you explicitly specify it explicitly in the flags (i.e. using 532unless you explicitly specify it explicitly in the flags (i.e. using
533\&\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)
534system like NetBSD. 534system like NetBSD.
535.Sp 535.Sp
536You 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
538the 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.
539.Sp 539.Sp
540It 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
541kernel is more efficient (which says nothing about its actual speed, of 541kernel is more efficient (which says nothing about its actual speed, of
542course). While stopping, setting and starting an I/O watcher does never 542course). While stopping, setting and starting an I/O watcher does never
543cause 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
544two 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
545drops fds silently in similarly hard-to-detect cases. 545drops fds silently in similarly hard-to-detect cases.
546.Sp 546.Sp
547This backend usually performs well under most conditions. 547This backend usually performs well under most conditions.
548.Sp 548.Sp
563.el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 563.el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4
564.IX Item "EVBACKEND_PORT (value 32, Solaris 10)" 564.IX Item "EVBACKEND_PORT (value 32, Solaris 10)"
565This 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,
566it'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)).
567.Sp 567.Sp
568Please note that solaris event ports can deliver a lot of spurious 568Please note that Solaris event ports can deliver a lot of spurious
569notifications, 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
570blocking when no data (or space) is available. 570blocking when no data (or space) is available.
571.Sp 571.Sp
572While this backend scales well, it requires one system call per active 572While this backend scales well, it requires one system call per active
573file descriptor per loop iteration. For small and medium numbers of file 573file descriptor per loop iteration. For small and medium numbers of file
586.Sp 586.Sp
587It is definitely not recommended to use this flag. 587It is definitely not recommended to use this flag.
588.RE 588.RE
589.RS 4 589.RS 4
590.Sp 590.Sp
591If 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
592backends 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
593specified, 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.
594.Sp 594.Sp
595The most typical usage is like this: 595The most typical usage is like this:
596.Sp 596.Sp
597.Vb 2 597.Vb 2
598\& if (!ev_default_loop (0)) 598\& if (!ev_default_loop (0))
599\& fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); 599\& fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
600.Ve 600.Ve
601.Sp 601.Sp
602Restrict libev to the select and poll backends, and do not allow 602Restrict libev to the select and poll backends, and do not allow
603environment settings to be taken into account: 603environment settings to be taken into account:
604.Sp 604.Sp
605.Vb 1 605.Vb 1
606\& ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); 606\& ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
607.Ve 607.Ve
608.Sp 608.Sp
609Use 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
610available (warning, breaks stuff, best use only with your own private 610available (warning, breaks stuff, best use only with your own private
611event 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):
612.Sp 612.Sp
613.Vb 1 613.Vb 1
614\& ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); 614\& ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
615.Ve 615.Ve
616.RE 616.RE
617.IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4 617.IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4
618.IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" 618.IX Item "struct ev_loop *ev_loop_new (unsigned int flags)"
619Similar 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
626default loop in the \*(L"main\*(R" or \*(L"initial\*(R" thread. 626default loop in the \*(L"main\*(R" or \*(L"initial\*(R" thread.
627.Sp 627.Sp
628Example: 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.
629.Sp 629.Sp
630.Vb 3 630.Vb 3
631\& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); 631\& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
632\& if (!epoller) 632\& if (!epoller)
633\& fatal ("no epoll found here, maybe it hides under your chair"); 633\& fatal ("no epoll found here, maybe it hides under your chair");
634.Ve 634.Ve
635.IP "ev_default_destroy ()" 4 635.IP "ev_default_destroy ()" 4
636.IX Item "ev_default_destroy ()" 636.IX Item "ev_default_destroy ()"
637Destroys the default loop again (frees all memory and kernel state 637Destroys the default loop again (frees all memory and kernel state
638etc.). 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
639sense, 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
640responsibility to either stop all watchers cleanly yoursef \fIbefore\fR 640responsibility to either stop all watchers cleanly yourself \fIbefore\fR
641calling this function, or cope with the fact afterwards (which is usually 641calling this function, or cope with the fact afterwards (which is usually
642the 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
643for example). 643for example).
644.Sp 644.Sp
645Note 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
720A 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
721those 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
722case 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.
723.Sp 723.Sp
724A 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
725neccessary) and will handle those and any outstanding ones. It will block 725necessary) and will handle those and any outstanding ones. It will block
726your 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
727one 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
728external event in conjunction with something not expressible using other 728external event in conjunction with something not expressible using other
729libev 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
730usually a better approach for this kind of thing. 730usually a better approach for this kind of thing.
796.Sp 796.Sp
797Example: 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
798running when nothing else is active. 798running when nothing else is active.
799.Sp 799.Sp
800.Vb 4 800.Vb 4
801\& struct ev_signal exitsig; 801\& struct ev_signal exitsig;
802\& ev_signal_init (&exitsig, sig_cb, SIGINT); 802\& ev_signal_init (&exitsig, sig_cb, SIGINT);
803\& ev_signal_start (loop, &exitsig); 803\& ev_signal_start (loop, &exitsig);
804\& evf_unref (loop); 804\& evf_unref (loop);
805.Ve 805.Ve
806.Sp 806.Sp
807Example: For some weird reason, unregister the above signal handler again. 807Example: For some weird reason, unregister the above signal handler again.
808.Sp 808.Sp
809.Vb 2 809.Vb 2
810\& ev_ref (loop); 810\& ev_ref (loop);
811\& ev_signal_stop (loop, &exitsig); 811\& ev_signal_stop (loop, &exitsig);
812.Ve 812.Ve
813.IP "ev_set_io_collect_interval (loop, ev_tstamp interval)" 4 813.IP "ev_set_io_collect_interval (loop, ev_tstamp interval)" 4
814.IX Item "ev_set_io_collect_interval (loop, ev_tstamp interval)" 814.IX Item "ev_set_io_collect_interval (loop, ev_tstamp interval)"
815.PD 0 815.PD 0
816.IP "ev_set_timeout_collect_interval (loop, ev_tstamp interval)" 4 816.IP "ev_set_timeout_collect_interval (loop, ev_tstamp interval)" 4
840to spend more time collecting timeouts, at the expense of increased 840to spend more time collecting timeouts, at the expense of increased
841latency (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
842will 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
843any overhead in libev. 843any overhead in libev.
844.Sp 844.Sp
845Many (busy) programs can usually benefit by setting the io collect 845Many (busy) programs can usually benefit by setting the I/O collect
846interval 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
847interactive servers (of course not for games), likewise for timeouts. It 847interactive servers (of course not for games), likewise for timeouts. It
848usually 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,
849as this approsaches the timing granularity of most systems. 849as this approaches the timing granularity of most systems.
850.IP "ev_loop_verify (loop)" 4 850.IP "ev_loop_verify (loop)" 4
851.IX Item "ev_loop_verify (loop)" 851.IX Item "ev_loop_verify (loop)"
852This function only does something when \f(CW\*(C`EV_VERIFY\*(C'\fR support has been 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 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 854them for validity. If anything is found to be inconsistent, it will print
862A 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
863interest 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
864become 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:
865.PP 865.PP
866.Vb 5 866.Vb 5
867\& 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)
868\& { 868\& {
869\& ev_io_stop (w); 869\& ev_io_stop (w);
870\& ev_unloop (loop, EVUNLOOP_ALL); 870\& ev_unloop (loop, EVUNLOOP_ALL);
871\& } 871\& }
872\& 872\&
873\& struct ev_loop *loop = ev_default_loop (0); 873\& struct ev_loop *loop = ev_default_loop (0);
874\& struct ev_io stdin_watcher; 874\& struct ev_io stdin_watcher;
875\& ev_init (&stdin_watcher, my_cb); 875\& ev_init (&stdin_watcher, my_cb);
876\& ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); 876\& ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
877\& ev_io_start (loop, &stdin_watcher); 877\& ev_io_start (loop, &stdin_watcher);
878\& ev_loop (loop, 0); 878\& ev_loop (loop, 0);
879.Ve 879.Ve
880.PP 880.PP
881As 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
882watcher 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,
883although this can sometimes be quite valid). 883although this can sometimes be quite valid).
884.PP 884.PP
885Each 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
886(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
887callback 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
888watchers, each time the event loop detects that the file descriptor given 888watchers, each time the event loop detects that the file descriptor given
889is readable and/or writable). 889is readable and/or writable).
890.PP 890.PP
891Each 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
892with arguments specific to this watcher type. There is also a macro 892with arguments specific to this watcher type. There is also a macro
972.IX Item "EV_ASYNC" 972.IX Item "EV_ASYNC"
973The 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).
974.ie n .IP """EV_ERROR""" 4 974.ie n .IP """EV_ERROR""" 4
975.el .IP "\f(CWEV_ERROR\fR" 4 975.el .IP "\f(CWEV_ERROR\fR" 4
976.IX Item "EV_ERROR" 976.IX Item "EV_ERROR"
977An unspecified error has occured, the watcher has been stopped. This might 977An unspecified error has occurred, the watcher has been stopped. This might
978happen because the watcher could not be properly started because libev 978happen because the watcher could not be properly started because libev
979ran 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
980problem. 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
981with the watcher being stopped. 981with the watcher being stopped.
982.Sp 982.Sp
983Libev 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,
984for 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
985your 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
986with 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
987programs, though, so beware. 987programs, though, so beware.
988.Sh "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" 988.Sh "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0"
989.IX Subsection "GENERIC WATCHER FUNCTIONS" 989.IX Subsection "GENERIC WATCHER FUNCTIONS"
990In 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,
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. 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.
1016Although some watcher types do not have type-specific arguments 1016Although some watcher types do not have type-specific arguments
1017(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.
1018.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
1019.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
1020.IX Item "ev_TYPE_init (ev_TYPE *watcher, callback, [args])" 1020.IX Item "ev_TYPE_init (ev_TYPE *watcher, callback, [args])"
1021This 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
1022calls 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
1023a watcher. The same limitations apply, of course. 1023a watcher. The same limitations apply, of course.
1024.ie n .IP """ev_TYPE_start"" (loop *, ev_TYPE *watcher)" 4 1024.ie n .IP """ev_TYPE_start"" (loop *, ev_TYPE *watcher)" 4
1025.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
1026.IX Item "ev_TYPE_start (loop *, ev_TYPE *watcher)" 1026.IX Item "ev_TYPE_start (loop *, ev_TYPE *watcher)"
1027Starts (activates) the given watcher. Only active watchers will receive 1027Starts (activates) the given watcher. Only active watchers will receive
1102don'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
1103member, 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
1104data: 1104data:
1105.PP 1105.PP
1106.Vb 7 1106.Vb 7
1107\& struct my_io 1107\& struct my_io
1108\& { 1108\& {
1109\& struct ev_io io; 1109\& struct ev_io io;
1110\& int otherfd; 1110\& int otherfd;
1111\& void *somedata; 1111\& void *somedata;
1112\& struct whatever *mostinteresting; 1112\& struct whatever *mostinteresting;
1113\& } 1113\& }
1114.Ve 1114.Ve
1115.PP 1115.PP
1116And 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
1117can cast it back to your own type: 1117can cast it back to your own type:
1118.PP 1118.PP
1119.Vb 5 1119.Vb 5
1120\& 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)
1121\& { 1121\& {
1122\& struct my_io *w = (struct my_io *)w_; 1122\& struct my_io *w = (struct my_io *)w_;
1123\& ... 1123\& ...
1124\& } 1124\& }
1125.Ve 1125.Ve
1126.PP 1126.PP
1127More interesting and less C\-conformant ways of casting your callback type 1127More interesting and less C\-conformant ways of casting your callback type
1128instead have been omitted. 1128instead have been omitted.
1129.PP 1129.PP
1130Another common scenario is having some data structure with multiple 1130Another common scenario is having some data structure with multiple
1131watchers: 1131watchers:
1132.PP 1132.PP
1133.Vb 6 1133.Vb 6
1134\& struct my_biggy 1134\& struct my_biggy
1135\& { 1135\& {
1136\& int some_data; 1136\& int some_data;
1137\& ev_timer t1; 1137\& ev_timer t1;
1138\& ev_timer t2; 1138\& ev_timer t2;
1139\& } 1139\& }
1140.Ve 1140.Ve
1141.PP 1141.PP
1142In 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,
1143you need to use \f(CW\*(C`offsetof\*(C'\fR: 1143you need to use \f(CW\*(C`offsetof\*(C'\fR:
1144.PP 1144.PP
1145.Vb 1 1145.Vb 1
1146\& #include <stddef.h> 1146\& #include <stddef.h>
1147\& 1147\&
1148\& static void 1148\& static void
1149\& t1_cb (EV_P_ struct ev_timer *w, int revents) 1149\& t1_cb (EV_P_ struct ev_timer *w, int revents)
1150\& { 1150\& {
1151\& struct my_biggy big = (struct my_biggy * 1151\& struct my_biggy big = (struct my_biggy *
1152\& (((char *)w) \- offsetof (struct my_biggy, t1)); 1152\& (((char *)w) \- offsetof (struct my_biggy, t1));
1153\& } 1153\& }
1154\& 1154\&
1155\& static void 1155\& static void
1156\& t2_cb (EV_P_ struct ev_timer *w, int revents) 1156\& t2_cb (EV_P_ struct ev_timer *w, int revents)
1157\& { 1157\& {
1158\& struct my_biggy big = (struct my_biggy * 1158\& struct my_biggy big = (struct my_biggy *
1159\& (((char *)w) \- offsetof (struct my_biggy, t2)); 1159\& (((char *)w) \- offsetof (struct my_biggy, t2));
1160\& } 1160\& }
1161.Ve 1161.Ve
1162.SH "WATCHER TYPES" 1162.SH "WATCHER TYPES"
1163.IX Header "WATCHER TYPES" 1163.IX Header "WATCHER TYPES"
1164This section describes each watcher in detail, but will not repeat 1164This section describes each watcher in detail, but will not repeat
1165information given in the last section. Any initialisation/set macros, 1165information given in the last section. Any initialisation/set macros,
1195.PP 1195.PP
1196Another 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
1197receive \*(L"spurious\*(R" readiness notifications, that is your callback might 1197receive \*(L"spurious\*(R" readiness notifications, that is your callback might
1198be 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
1199because 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
1200lot 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
1201this situation even with a relatively standard program structure. Thus 1201this situation even with a relatively standard program structure. Thus
1202it 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
1203\&\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.
1204.PP 1204.PP
1205If 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
1206play 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
1207whether 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
1208such 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
1209its own, so its quite safe to use). 1209its own, so its quite safe to use).
1210.PP 1210.PP
1211\fIThe special problem of disappearing file descriptors\fR 1211\fIThe special problem of disappearing file descriptors\fR
1274.PD 0 1274.PD 0
1275.IP "ev_io_set (ev_io *, int fd, int events)" 4 1275.IP "ev_io_set (ev_io *, int fd, int events)" 4
1276.IX Item "ev_io_set (ev_io *, int fd, int events)" 1276.IX Item "ev_io_set (ev_io *, int fd, int events)"
1277.PD 1277.PD
1278Configures 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
1279rceeive 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
1280\&\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.
1281.IP "int fd [read\-only]" 4 1281.IP "int fd [read\-only]" 4
1282.IX Item "int fd [read-only]" 1282.IX Item "int fd [read-only]"
1283The file descriptor being watched. 1283The file descriptor being watched.
1284.IP "int events [read\-only]" 4 1284.IP "int events [read\-only]" 4
1291Example: 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
1292readable, but only once. Since it is likely line-buffered, you could 1292readable, but only once. Since it is likely line-buffered, you could
1293attempt to read a whole line in the callback. 1293attempt to read a whole line in the callback.
1294.PP 1294.PP
1295.Vb 6 1295.Vb 6
1296\& static void 1296\& static void
1297\& 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)
1298\& { 1298\& {
1299\& ev_io_stop (loop, w); 1299\& ev_io_stop (loop, w);
1300\& .. 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
1301\& } 1301\& }
1302\& 1302\&
1303\& ... 1303\& ...
1304\& struct ev_loop *loop = ev_default_init (0); 1304\& struct ev_loop *loop = ev_default_init (0);
1305\& struct ev_io stdin_readable; 1305\& struct ev_io stdin_readable;
1306\& 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);
1307\& ev_io_start (loop, &stdin_readable); 1307\& ev_io_start (loop, &stdin_readable);
1308\& ev_loop (loop, 0); 1308\& ev_loop (loop, 0);
1309.Ve 1309.Ve
1310.ie n .Sh """ev_timer"" \- relative and optionally repeating timeouts" 1310.ie n .Sh """ev_timer"" \- relative and optionally repeating timeouts"
1311.el .Sh "\f(CWev_timer\fP \- relative and optionally repeating timeouts" 1311.el .Sh "\f(CWev_timer\fP \- relative and optionally repeating timeouts"
1312.IX Subsection "ev_timer - relative and optionally repeating timeouts" 1312.IX Subsection "ev_timer - relative and optionally repeating timeouts"
1313Timer watchers are simple relative timers that generate an event after a 1313Timer watchers are simple relative timers that generate an event after a
1314given time, and optionally repeating in regular intervals after that. 1314given time, and optionally repeating in regular intervals after that.
1315.PP 1315.PP
1316The 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
1317times out after an hour and you reset your system clock to january last 1317times out after an hour and you reset your system clock to January last
1318year, 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
1319detecting time jumps is hard, and some inaccuracies are unavoidable (the 1319detecting time jumps is hard, and some inaccuracies are unavoidable (the
1320monotonic clock option helps a lot here). 1320monotonic clock option helps a lot here).
1321.PP 1321.PP
1322The 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
1327.PP 1327.PP
1328.Vb 1 1328.Vb 1
1329\& ev_timer_set (&timer, after + ev_now () \- ev_time (), 0.); 1329\& ev_timer_set (&timer, after + ev_now () \- ev_time (), 0.);
1330.Ve 1330.Ve
1331.PP 1331.PP
1332The callback is guarenteed to be invoked only after its timeout has passed, 1332The callback is guaranteed to be invoked only after its timeout has passed,
1333but if multiple timers become ready during the same loop iteration then 1333but if multiple timers become ready during the same loop iteration then
1334order of execution is undefined. 1334order of execution is undefined.
1335.PP 1335.PP
1336\fIWatcher-Specific Functions and Data Members\fR 1336\fIWatcher-Specific Functions and Data Members\fR
1337.IX Subsection "Watcher-Specific Functions and Data Members" 1337.IX Subsection "Watcher-Specific Functions and Data Members"
1357This 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
1358repeating. The exact semantics are: 1358repeating. The exact semantics are:
1359.Sp 1359.Sp
1360If the timer is pending, its pending status is cleared. 1360If the timer is pending, its pending status is cleared.
1361.Sp 1361.Sp
1362If 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).
1363.Sp 1363.Sp
1364If the timer is repeating, either start it if necessary (with the 1364If the timer is repeating, either start it if necessary (with the
1365\&\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.
1366.Sp 1366.Sp
1367This sounds a bit complicated, but here is a useful and typical 1367This sounds a bit complicated, but here is a useful and typical
1368example: 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
1369timeout, 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
1370seconds 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
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 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
1372\&\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
1373you 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
1400.IX Subsection "Examples" 1400.IX Subsection "Examples"
1401.PP 1401.PP
1402Example: Create a timer that fires after 60 seconds. 1402Example: Create a timer that fires after 60 seconds.
1403.PP 1403.PP
1404.Vb 5 1404.Vb 5
1405\& static void 1405\& static void
1406\& 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)
1407\& { 1407\& {
1408\& .. one minute over, w is actually stopped right here 1408\& .. one minute over, w is actually stopped right here
1409\& } 1409\& }
1410\& 1410\&
1411\& struct ev_timer mytimer; 1411\& struct ev_timer mytimer;
1412\& ev_timer_init (&mytimer, one_minute_cb, 60., 0.); 1412\& ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
1413\& ev_timer_start (loop, &mytimer); 1413\& ev_timer_start (loop, &mytimer);
1414.Ve 1414.Ve
1415.PP 1415.PP
1416Example: Create a timeout timer that times out after 10 seconds of 1416Example: Create a timeout timer that times out after 10 seconds of
1417inactivity. 1417inactivity.
1418.PP 1418.PP
1419.Vb 5 1419.Vb 5
1420\& static void 1420\& static void
1421\& 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)
1422\& { 1422\& {
1423\& .. ten seconds without any activity 1423\& .. ten seconds without any activity
1424\& } 1424\& }
1425\& 1425\&
1426\& struct ev_timer mytimer; 1426\& struct ev_timer mytimer;
1427\& 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 */
1428\& ev_timer_again (&mytimer); /* start timer */ 1428\& ev_timer_again (&mytimer); /* start timer */
1429\& ev_loop (loop, 0); 1429\& ev_loop (loop, 0);
1430\& 1430\&
1431\& // 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":
1432\& // reset the timeout to start ticking again at 10 seconds 1432\& // reset the timeout to start ticking again at 10 seconds
1433\& ev_timer_again (&mytimer); 1433\& ev_timer_again (&mytimer);
1434.Ve 1434.Ve
1435.ie n .Sh """ev_periodic"" \- to cron or not to cron?" 1435.ie n .Sh """ev_periodic"" \- to cron or not to cron?"
1436.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?"
1437.IX Subsection "ev_periodic - to cron or not to cron?" 1437.IX Subsection "ev_periodic - to cron or not to cron?"
1438Periodic 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
1439(and unfortunately a bit complex). 1439(and unfortunately a bit complex).
1440.PP 1440.PP
1441Unlike \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)
1442but on wallclock time (absolute time). You can tell a periodic watcher 1442but on wall clock time (absolute time). You can tell a periodic watcher
1443to trigger after 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
1444periodic 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 ()
1445+ 10.\*(C'\fR, that is, an absolute time not a delay) and then reset your system 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 1446clock to January of the previous year, then it will take more than year
1447to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would still trigger 1447to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would still trigger
1448roughly 10 seconds later as it uses a relative timeout). 1448roughly 10 seconds later as it uses a relative timeout).
1449.PP 1449.PP
1450\&\f(CW\*(C`ev_periodic\*(C'\fRs can also be used to implement vastly more complex timers, 1450\&\f(CW\*(C`ev_periodic\*(C'\fRs can also be used to implement vastly more complex timers,
1451such as triggering an event on each \*(L"midnight, local time\*(R", or other 1451such as triggering an event on each \*(L"midnight, local time\*(R", or other
1452complicated, rules. 1452complicated, rules.
1453.PP 1453.PP
1454As 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
1455time (\f(CW\*(C`at\*(C'\fR) has passed, but if multiple periodic timers become ready 1455time (\f(CW\*(C`at\*(C'\fR) has passed, but if multiple periodic timers become ready
1456during the same loop iteration then order of execution is undefined. 1456during the same loop iteration then order of execution is undefined.
1457.PP 1457.PP
1458\fIWatcher-Specific Functions and Data Members\fR 1458\fIWatcher-Specific Functions and Data Members\fR
1459.IX Subsection "Watcher-Specific Functions and Data Members" 1459.IX Subsection "Watcher-Specific Functions and Data Members"
1467operation, and we will explain them from simplest to complex: 1467operation, and we will explain them from simplest to complex:
1468.RS 4 1468.RS 4
1469.IP "\(bu" 4 1469.IP "\(bu" 4
1470absolute timer (at = time, interval = reschedule_cb = 0) 1470absolute timer (at = time, interval = reschedule_cb = 0)
1471.Sp 1471.Sp
1472In this configuration the watcher triggers an event after the wallclock 1472In this configuration the watcher triggers an event after the wall clock
1473time \f(CW\*(C`at\*(C'\fR has passed and doesn't repeat. It will not adjust when a time 1473time \f(CW\*(C`at\*(C'\fR has passed and doesn't repeat. It will not adjust when a time
1474jump occurs, that is, if it is to be run at January 1st 2011 then it will 1474jump occurs, that is, if it is to be run at January 1st 2011 then it will
1475run when the system time reaches or surpasses this time. 1475run when the system time reaches or surpasses this time.
1476.IP "\(bu" 4 1476.IP "\(bu" 4
1477repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) 1477repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
1487.Vb 1 1487.Vb 1
1488\& ev_periodic_set (&periodic, 0., 3600., 0); 1488\& ev_periodic_set (&periodic, 0., 3600., 0);
1489.Ve 1489.Ve
1490.Sp 1490.Sp
1491This 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,
1492but 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
1493full 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
1494by 3600. 1494by 3600.
1495.Sp 1495.Sp
1496Another way to think about it (for the mathematically inclined) is that 1496Another way to think about it (for the mathematically inclined) is that
1497\&\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
1499.Sp 1499.Sp
1500For 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
1501\&\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
1502this value, and in fact is often specified as zero. 1502this value, and in fact is often specified as zero.
1503.Sp 1503.Sp
1504Note also that there is an upper limit to how often a timer can fire (cpu 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 1505speed for example), so if \f(CW\*(C`interval\*(C'\fR is very small then timing stability
1506will of course detoriate. Libev itself tries to be exact to be about one 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). 1507millisecond (if the \s-1OS\s0 supports it and the machine is fast enough).
1508.IP "\(bu" 4 1508.IP "\(bu" 4
1509manual reschedule mode (at and interval ignored, reschedule_cb = callback) 1509manual reschedule mode (at and interval ignored, reschedule_cb = callback)
1510.Sp 1510.Sp
1511In 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
1577\fIExamples\fR 1577\fIExamples\fR
1578.IX Subsection "Examples" 1578.IX Subsection "Examples"
1579.PP 1579.PP
1580Example: Call a callback every hour, or, more precisely, whenever the 1580Example: Call a callback every hour, or, more precisely, whenever the
1581system clock is divisible by 3600. The callback invocation times have 1581system clock is divisible by 3600. The callback invocation times have
1582potentially a lot of jittering, but good long-term stability. 1582potentially a lot of jitter, but good long-term stability.
1583.PP 1583.PP
1584.Vb 5 1584.Vb 5
1585\& static void 1585\& static void
1586\& 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)
1587\& { 1587\& {
1588\& ... 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)
1589\& } 1589\& }
1590\& 1590\&
1591\& struct ev_periodic hourly_tick; 1591\& struct ev_periodic hourly_tick;
1592\& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); 1592\& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1593\& ev_periodic_start (loop, &hourly_tick); 1593\& ev_periodic_start (loop, &hourly_tick);
1594.Ve 1594.Ve
1595.PP 1595.PP
1596Example: 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:
1597.PP 1597.PP
1598.Vb 1 1598.Vb 1
1599\& #include <math.h> 1599\& #include <math.h>
1600\& 1600\&
1601\& static ev_tstamp 1601\& static ev_tstamp
1602\& my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) 1602\& my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
1603\& { 1603\& {
1604\& return fmod (now, 3600.) + 3600.; 1604\& return fmod (now, 3600.) + 3600.;
1605\& } 1605\& }
1606\& 1606\&
1607\& 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);
1608.Ve 1608.Ve
1609.PP 1609.PP
1610Example: Call a callback every hour, starting now: 1610Example: Call a callback every hour, starting now:
1611.PP 1611.PP
1612.Vb 4 1612.Vb 4
1613\& struct ev_periodic hourly_tick; 1613\& struct ev_periodic hourly_tick;
1614\& ev_periodic_init (&hourly_tick, clock_cb, 1614\& ev_periodic_init (&hourly_tick, clock_cb,
1615\& fmod (ev_now (loop), 3600.), 3600., 0); 1615\& fmod (ev_now (loop), 3600.), 3600., 0);
1616\& ev_periodic_start (loop, &hourly_tick); 1616\& ev_periodic_start (loop, &hourly_tick);
1617.Ve 1617.Ve
1618.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!"
1619.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!"
1620.IX Subsection "ev_signal - signal me when a signal gets signalled!" 1620.IX Subsection "ev_signal - signal me when a signal gets signalled!"
1621Signal watchers will trigger an event when the process receives a specific 1621Signal watchers will trigger an event when the process receives a specific
1629as 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
1630watcher 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
1631\&\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).
1632.PP 1632.PP
1633If possible and supported, libev will install its handlers with 1633If possible and supported, libev will install its handlers with
1634\&\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
1635interrupted. If you have a problem with syscalls getting interrupted by 1635interrupted. If you have a problem with system calls getting interrupted by
1636signals 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
1637them in an \f(CW\*(C`ev_prepare\*(C'\fR watcher. 1637them in an \f(CW\*(C`ev_prepare\*(C'\fR watcher.
1638.PP 1638.PP
1639\fIWatcher-Specific Functions and Data Members\fR 1639\fIWatcher-Specific Functions and Data Members\fR
1640.IX Subsection "Watcher-Specific Functions and Data Members" 1640.IX Subsection "Watcher-Specific Functions and Data Members"
1654.IX Subsection "Examples" 1654.IX Subsection "Examples"
1655.PP 1655.PP
1656Example: 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.
1657.PP 1657.PP
1658.Vb 5 1658.Vb 5
1659\& static void 1659\& static void
1660\& 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)
1661\& { 1661\& {
1662\& ev_unloop (loop, EVUNLOOP_ALL); 1662\& ev_unloop (loop, EVUNLOOP_ALL);
1663\& } 1663\& }
1664\& 1664\&
1665\& struct ev_signal signal_watcher; 1665\& struct ev_signal signal_watcher;
1666\& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); 1666\& ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1667\& ev_signal_start (loop, &sigint_cb); 1667\& ev_signal_start (loop, &sigint_cb);
1668.Ve 1668.Ve
1669.ie n .Sh """ev_child"" \- watch out for process status changes" 1669.ie n .Sh """ev_child"" \- watch out for process status changes"
1670.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"
1671.IX Subsection "ev_child - watch out for process status changes" 1671.IX Subsection "ev_child - watch out for process status changes"
1672Child 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
1674is 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
1675forked (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
1676loop isn't entered (or is continued from a watcher). 1676loop isn't entered (or is continued from a watcher).
1677.PP 1677.PP
1678Only the default event loop is capable of handling signals, and therefore 1678Only the default event loop is capable of handling signals, and therefore
1679you can only rgeister child watchers in the default event loop. 1679you can only register child watchers in the default event loop.
1680.PP 1680.PP
1681\fIProcess Interaction\fR 1681\fIProcess Interaction\fR
1682.IX Subsection "Process Interaction" 1682.IX Subsection "Process Interaction"
1683.PP 1683.PP
1684Libev 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
1685initialised. This is necessary to guarantee proper behaviour even if 1685initialised. This is necessary to guarantee proper behaviour even if
1686the first child watcher is started after the child exits. The occurance 1686the first child watcher is started after the child exits. The occurrence
1687of \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
1688synchronously as part of the event loop processing. Libev always reaps all 1688synchronously as part of the event loop processing. Libev always reaps all
1689children, even ones not watched. 1689children, even ones not watched.
1690.PP 1690.PP
1691\fIOverriding the Built-In Processing\fR 1691\fIOverriding the Built-In Processing\fR
1731.PP 1731.PP
1732Example: \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
1733its completion. 1733its completion.
1734.PP 1734.PP
1735.Vb 1 1735.Vb 1
1736\& ev_child cw; 1736\& ev_child cw;
1737\& 1737\&
1738\& static void 1738\& static void
1739\& child_cb (EV_P_ struct ev_child *w, int revents) 1739\& child_cb (EV_P_ struct ev_child *w, int revents)
1740\& { 1740\& {
1741\& ev_child_stop (EV_A_ w); 1741\& ev_child_stop (EV_A_ w);
1742\& 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);
1743\& } 1743\& }
1744\& 1744\&
1745\& pid_t pid = fork (); 1745\& pid_t pid = fork ();
1746\& 1746\&
1747\& if (pid < 0) 1747\& if (pid < 0)
1748\& // error 1748\& // error
1749\& else if (pid == 0) 1749\& else if (pid == 0)
1750\& { 1750\& {
1751\& // the forked child executes here 1751\& // the forked child executes here
1752\& exit (1); 1752\& exit (1);
1753\& } 1753\& }
1754\& else 1754\& else
1755\& { 1755\& {
1756\& ev_child_init (&cw, child_cb, pid, 0); 1756\& ev_child_init (&cw, child_cb, pid, 0);
1757\& ev_child_start (EV_DEFAULT_ &cw); 1757\& ev_child_start (EV_DEFAULT_ &cw);
1758\& } 1758\& }
1759.Ve 1759.Ve
1760.ie n .Sh """ev_stat"" \- did the file attributes just change?" 1760.ie n .Sh """ev_stat"" \- did the file attributes just change?"
1761.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?"
1762.IX Subsection "ev_stat - did the file attributes just change?" 1762.IX Subsection "ev_stat - did the file attributes just change?"
1763This watches a filesystem path for attribute changes. That is, it calls 1763This watches a file system path for attribute changes. That is, it calls
1764\&\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
1765compared to the last time, invoking the callback if it did. 1765compared to the last time, invoking the callback if it did.
1766.PP 1766.PP
1767The 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
1768not 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
1803disabled 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
1804structure. 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
1805use 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
1806compile libev with the same flags to get binary compatibility. This is 1806compile libev with the same flags to get binary compatibility. This is
1807obviously 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
1808most noticably with ev_stat and largefile support. 1808most noticeably with ev_stat and large file support.
1809.PP 1809.PP
1810\fIInotify\fR 1810\fIInotify\fR
1811.IX Subsection "Inotify" 1811.IX Subsection "Inotify"
1812.PP 1812.PP
1813When \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
1825descriptor open on the object at all times). 1825descriptor open on the object at all times).
1826.PP 1826.PP
1827\fIThe special problem of stat time resolution\fR 1827\fIThe special problem of stat time resolution\fR
1828.IX Subsection "The special problem of stat time resolution" 1828.IX Subsection "The special problem of stat time resolution"
1829.PP 1829.PP
1830The \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
1831even on systems where the resolution is higher, many filesystems still 1831even on systems where the resolution is higher, many file systems still
1832only support whole seconds. 1832only support whole seconds.
1833.PP 1833.PP
1834That 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
1835easily 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
1836calls your callback, which does something. When there is another update 1836calls your callback, which does something. When there is another update
1891.IP "ev_tstamp interval [read\-only]" 4 1891.IP "ev_tstamp interval [read\-only]" 4
1892.IX Item "ev_tstamp interval [read-only]" 1892.IX Item "ev_tstamp interval [read-only]"
1893The specified interval. 1893The specified interval.
1894.IP "const char *path [read\-only]" 4 1894.IP "const char *path [read\-only]" 4
1895.IX Item "const char *path [read-only]" 1895.IX Item "const char *path [read-only]"
1896The filesystem path that is being watched. 1896The file system path that is being watched.
1897.PP 1897.PP
1898\fIExamples\fR 1898\fIExamples\fR
1899.IX Subsection "Examples" 1899.IX Subsection "Examples"
1900.PP 1900.PP
1901Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes. 1901Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes.
1902.PP 1902.PP
1903.Vb 10 1903.Vb 10
1904\& static void 1904\& static void
1905\& passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) 1905\& passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
1906\& { 1906\& {
1907\& /* /etc/passwd changed in some way */ 1907\& /* /etc/passwd changed in some way */
1908\& if (w\->attr.st_nlink) 1908\& if (w\->attr.st_nlink)
1909\& { 1909\& {
1910\& printf ("passwd current size %ld\en", (long)w\->attr.st_size); 1910\& printf ("passwd current size %ld\en", (long)w\->attr.st_size);
1911\& printf ("passwd current atime %ld\en", (long)w\->attr.st_mtime); 1911\& printf ("passwd current atime %ld\en", (long)w\->attr.st_mtime);
1912\& printf ("passwd current mtime %ld\en", (long)w\->attr.st_mtime); 1912\& printf ("passwd current mtime %ld\en", (long)w\->attr.st_mtime);
1913\& } 1913\& }
1914\& else 1914\& else
1915\& /* you shalt not abuse printf for puts */ 1915\& /* you shalt not abuse printf for puts */
1916\& puts ("wow, /etc/passwd is not there, expect problems. " 1916\& puts ("wow, /etc/passwd is not there, expect problems. "
1917\& "if this is windows, they already arrived\en"); 1917\& "if this is windows, they already arrived\en");
1918\& } 1918\& }
1919\& 1919\&
1920\& ... 1920\& ...
1921\& ev_stat passwd; 1921\& ev_stat passwd;
1922\& 1922\&
1923\& ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.); 1923\& ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);
1924\& ev_stat_start (loop, &passwd); 1924\& ev_stat_start (loop, &passwd);
1925.Ve 1925.Ve
1926.PP 1926.PP
1927Example: 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
1928miss updates (however, frequent updates will delay processing, too, so 1928miss updates (however, frequent updates will delay processing, too, so
1929one 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
1930\&\f(CW\*(C`ev_timer\*(C'\fR callback invocation). 1930\&\f(CW\*(C`ev_timer\*(C'\fR callback invocation).
1931.PP 1931.PP
1932.Vb 2 1932.Vb 2
1933\& static ev_stat passwd; 1933\& static ev_stat passwd;
1934\& static ev_timer timer; 1934\& static ev_timer timer;
1935\& 1935\&
1936\& static void 1936\& static void
1937\& timer_cb (EV_P_ ev_timer *w, int revents) 1937\& timer_cb (EV_P_ ev_timer *w, int revents)
1938\& { 1938\& {
1939\& ev_timer_stop (EV_A_ w); 1939\& ev_timer_stop (EV_A_ w);
1940\& 1940\&
1941\& /* now it\*(Aqs one second after the most recent passwd change */ 1941\& /* now it\*(Aqs one second after the most recent passwd change */
1942\& } 1942\& }
1943\& 1943\&
1944\& static void 1944\& static void
1945\& stat_cb (EV_P_ ev_stat *w, int revents) 1945\& stat_cb (EV_P_ ev_stat *w, int revents)
1946\& { 1946\& {
1947\& /* reset the one\-second timer */ 1947\& /* reset the one\-second timer */
1948\& ev_timer_again (EV_A_ &timer); 1948\& ev_timer_again (EV_A_ &timer);
1949\& } 1949\& }
1950\& 1950\&
1951\& ... 1951\& ...
1952\& ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); 1952\& ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);
1953\& ev_stat_start (loop, &passwd); 1953\& ev_stat_start (loop, &passwd);
1954\& ev_timer_init (&timer, timer_cb, 0., 1.02); 1954\& ev_timer_init (&timer, timer_cb, 0., 1.02);
1955.Ve 1955.Ve
1956.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..."
1957.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..."
1958.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..."
1959Idle 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
1988.PP 1988.PP
1989Example: 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
1990callback, free it. Also, use no error checking, as usual. 1990callback, free it. Also, use no error checking, as usual.
1991.PP 1991.PP
1992.Vb 7 1992.Vb 7
1993\& static void 1993\& static void
1994\& 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)
1995\& { 1995\& {
1996\& free (w); 1996\& free (w);
1997\& // now do something you wanted to do when the program has 1997\& // now do something you wanted to do when the program has
1998\& // no longer anything immediate to do. 1998\& // no longer anything immediate to do.
1999\& } 1999\& }
2000\& 2000\&
2001\& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); 2001\& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
2002\& ev_idle_init (idle_watcher, idle_cb); 2002\& ev_idle_init (idle_watcher, idle_cb);
2003\& ev_idle_start (loop, idle_cb); 2003\& ev_idle_start (loop, idle_cb);
2004.Ve 2004.Ve
2005.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!"
2006.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!"
2007.IX Subsection "ev_prepare and ev_check - customise your event loop!" 2007.IX Subsection "ev_prepare and ev_check - customise your event loop!"
2008Prepare and check watchers are usually (but not always) used in tandem: 2008Prepare and check watchers are usually (but not always) used in tandem:
2027.PP 2027.PP
2028This 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
2029to 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
2030them 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
2031provide just this functionality). Then, in the check watcher you check for 2031provide just this functionality). Then, in the check watcher you check for
2032any events that occured (by checking the pending status of all watchers 2032any events that occurred (by checking the pending status of all watchers
2033and 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
2034callbacks will never actually be called (but must be valid nevertheless, 2034callbacks will never actually be called (but must be valid nevertheless,
2035because you never know, you know?). 2035because you never know, you know?).
2036.PP 2036.PP
2037As another example, the Perl Coro module uses these hooks to integrate 2037As another example, the Perl Coro module uses these hooks to integrate
2080is 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
2081priority 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
2082the 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.
2083.PP 2083.PP
2084.Vb 2 2084.Vb 2
2085\& static ev_io iow [nfd]; 2085\& static ev_io iow [nfd];
2086\& static ev_timer tw; 2086\& static ev_timer tw;
2087\& 2087\&
2088\& static void 2088\& static void
2089\& io_cb (ev_loop *loop, ev_io *w, int revents) 2089\& io_cb (ev_loop *loop, ev_io *w, int revents)
2090\& { 2090\& {
2091\& } 2091\& }
2092\& 2092\&
2093\& // create io watchers for each fd and a timer before blocking 2093\& // create io watchers for each fd and a timer before blocking
2094\& static void 2094\& static void
2095\& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) 2095\& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
2096\& { 2096\& {
2097\& int timeout = 3600000; 2097\& int timeout = 3600000;
2098\& struct pollfd fds [nfd]; 2098\& struct pollfd fds [nfd];
2099\& // actual code will need to loop here and realloc etc. 2099\& // actual code will need to loop here and realloc etc.
2100\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); 2100\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
2101\& 2101\&
2102\& /* 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 */
2103\& ev_timer_init (&tw, 0, timeout * 1e\-3); 2103\& ev_timer_init (&tw, 0, timeout * 1e\-3);
2104\& ev_timer_start (loop, &tw); 2104\& ev_timer_start (loop, &tw);
2105\& 2105\&
2106\& // create one ev_io per pollfd 2106\& // create one ev_io per pollfd
2107\& for (int i = 0; i < nfd; ++i) 2107\& for (int i = 0; i < nfd; ++i)
2108\& { 2108\& {
2109\& ev_io_init (iow + i, io_cb, fds [i].fd, 2109\& ev_io_init (iow + i, io_cb, fds [i].fd,
2110\& ((fds [i].events & POLLIN ? EV_READ : 0) 2110\& ((fds [i].events & POLLIN ? EV_READ : 0)
2111\& | (fds [i].events & POLLOUT ? EV_WRITE : 0))); 2111\& | (fds [i].events & POLLOUT ? EV_WRITE : 0)));
2112\& 2112\&
2113\& fds [i].revents = 0; 2113\& fds [i].revents = 0;
2114\& ev_io_start (loop, iow + i); 2114\& ev_io_start (loop, iow + i);
2115\& } 2115\& }
2116\& } 2116\& }
2117\& 2117\&
2118\& // stop all watchers after blocking 2118\& // stop all watchers after blocking
2119\& static void 2119\& static void
2120\& adns_check_cb (ev_loop *loop, ev_check *w, int revents) 2120\& adns_check_cb (ev_loop *loop, ev_check *w, int revents)
2121\& { 2121\& {
2122\& ev_timer_stop (loop, &tw); 2122\& ev_timer_stop (loop, &tw);
2123\& 2123\&
2124\& for (int i = 0; i < nfd; ++i) 2124\& for (int i = 0; i < nfd; ++i)
2125\& { 2125\& {
2126\& // set the relevant poll flags 2126\& // set the relevant poll flags
2127\& // could also call adns_processreadable etc. here 2127\& // could also call adns_processreadable etc. here
2128\& struct pollfd *fd = fds + i; 2128\& struct pollfd *fd = fds + i;
2129\& int revents = ev_clear_pending (iow + i); 2129\& int revents = ev_clear_pending (iow + i);
2130\& if (revents & EV_READ ) fd\->revents |= fd\->events & POLLIN; 2130\& if (revents & EV_READ ) fd\->revents |= fd\->events & POLLIN;
2131\& if (revents & EV_WRITE) fd\->revents |= fd\->events & POLLOUT; 2131\& if (revents & EV_WRITE) fd\->revents |= fd\->events & POLLOUT;
2132\& 2132\&
2133\& // now stop the watcher 2133\& // now stop the watcher
2134\& ev_io_stop (loop, iow + i); 2134\& ev_io_stop (loop, iow + i);
2135\& } 2135\& }
2136\& 2136\&
2137\& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); 2137\& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
2138\& } 2138\& }
2139.Ve 2139.Ve
2140.PP 2140.PP
2141Method 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
2142in the prepare watcher and would dispose of the check watcher. 2142in the prepare watcher and would dispose of the check watcher.
2143.PP 2143.PP
2144Method 3: If the module to be embedded supports explicit event 2144Method 3: If the module to be embedded supports explicit event
2145notification (adns does), you can also make use of the actual watcher 2145notification (libadns does), you can also make use of the actual watcher
2146callbacks, and only destroy/create the watchers in the prepare watcher. 2146callbacks, and only destroy/create the watchers in the prepare watcher.
2147.PP 2147.PP
2148.Vb 5 2148.Vb 5
2149\& static void 2149\& static void
2150\& timer_cb (EV_P_ ev_timer *w, int revents) 2150\& timer_cb (EV_P_ ev_timer *w, int revents)
2151\& { 2151\& {
2152\& adns_state ads = (adns_state)w\->data; 2152\& adns_state ads = (adns_state)w\->data;
2153\& update_now (EV_A); 2153\& update_now (EV_A);
2154\& 2154\&
2155\& adns_processtimeouts (ads, &tv_now); 2155\& adns_processtimeouts (ads, &tv_now);
2156\& } 2156\& }
2157\& 2157\&
2158\& static void 2158\& static void
2159\& io_cb (EV_P_ ev_io *w, int revents) 2159\& io_cb (EV_P_ ev_io *w, int revents)
2160\& { 2160\& {
2161\& adns_state ads = (adns_state)w\->data; 2161\& adns_state ads = (adns_state)w\->data;
2162\& update_now (EV_A); 2162\& update_now (EV_A);
2163\& 2163\&
2164\& if (revents & EV_READ ) adns_processreadable (ads, w\->fd, &tv_now); 2164\& if (revents & EV_READ ) adns_processreadable (ads, w\->fd, &tv_now);
2165\& if (revents & EV_WRITE) adns_processwriteable (ads, w\->fd, &tv_now); 2165\& if (revents & EV_WRITE) adns_processwriteable (ads, w\->fd, &tv_now);
2166\& } 2166\& }
2167\& 2167\&
2168\& // do not ever call adns_afterpoll 2168\& // do not ever call adns_afterpoll
2169.Ve 2169.Ve
2170.PP 2170.PP
2171Method 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
2172want 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
2173their poll function. The drawback with this solution is that the main 2173their poll function. The drawback with this solution is that the main
2174loop 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
2175this. 2175this.
2176.PP 2176.PP
2177.Vb 4 2177.Vb 4
2178\& static gint 2178\& static gint
2179\& event_poll_func (GPollFD *fds, guint nfds, gint timeout) 2179\& event_poll_func (GPollFD *fds, guint nfds, gint timeout)
2180\& { 2180\& {
2181\& int got_events = 0; 2181\& int got_events = 0;
2182\& 2182\&
2183\& for (n = 0; n < nfds; ++n) 2183\& for (n = 0; n < nfds; ++n)
2184\& // 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
2185\& 2185\&
2186\& if (timeout >= 0) 2186\& if (timeout >= 0)
2187\& // create/start timer 2187\& // create/start timer
2188\& 2188\&
2189\& // poll 2189\& // poll
2190\& ev_loop (EV_A_ 0); 2190\& ev_loop (EV_A_ 0);
2191\& 2191\&
2192\& // stop timer again 2192\& // stop timer again
2193\& if (timeout >= 0) 2193\& if (timeout >= 0)
2194\& ev_timer_stop (EV_A_ &to); 2194\& ev_timer_stop (EV_A_ &to);
2195\& 2195\&
2196\& // stop io watchers again \- their callbacks should have set 2196\& // stop io watchers again \- their callbacks should have set
2197\& for (n = 0; n < nfds; ++n) 2197\& for (n = 0; n < nfds; ++n)
2198\& ev_io_stop (EV_A_ iow [n]); 2198\& ev_io_stop (EV_A_ iow [n]);
2199\& 2199\&
2200\& return got_events; 2200\& return got_events;
2201\& } 2201\& }
2202.Ve 2202.Ve
2203.ie n .Sh """ev_embed"" \- when one backend isn't enough..." 2203.ie n .Sh """ev_embed"" \- when one backend isn't enough..."
2204.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..."
2205.IX Subsection "ev_embed - when one backend isn't enough..." 2205.IX Subsection "ev_embed - when one backend isn't enough..."
2206This 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
2262.PD 2262.PD
2263Configures the watcher to embed the given loop, which must be 2263Configures the watcher to embed the given loop, which must be
2264embeddable. 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
2265invoked automatically, otherwise it is the responsibility of the callback 2265invoked automatically, otherwise it is the responsibility of the callback
2266to 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,
2267if 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).
2268.IP "ev_embed_sweep (loop, ev_embed *)" 4 2268.IP "ev_embed_sweep (loop, ev_embed *)" 4
2269.IX Item "ev_embed_sweep (loop, ev_embed *)" 2269.IX Item "ev_embed_sweep (loop, ev_embed *)"
2270Make a single, non-blocking sweep over the embedded loop. This works 2270Make a single, non-blocking sweep over the embedded loop. This works
2271similarly 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
2272apropriate way for embedded loops. 2272appropriate way for embedded loops.
2273.IP "struct ev_loop *other [read\-only]" 4 2273.IP "struct ev_loop *other [read\-only]" 4
2274.IX Item "struct ev_loop *other [read-only]" 2274.IX Item "struct ev_loop *other [read-only]"
2275The embedded event loop. 2275The embedded event loop.
2276.PP 2276.PP
2277\fIExamples\fR 2277\fIExamples\fR
2278.IX Subsection "Examples" 2278.IX Subsection "Examples"
2279.PP 2279.PP
2280Example: 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
2281event 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
2282loop 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
2283\&\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
2284used). 2284used).
2285.PP 2285.PP
2286.Vb 3 2286.Vb 3
2287\& struct ev_loop *loop_hi = ev_default_init (0); 2287\& struct ev_loop *loop_hi = ev_default_init (0);
2288\& struct ev_loop *loop_lo = 0; 2288\& struct ev_loop *loop_lo = 0;
2289\& struct ev_embed embed; 2289\& struct ev_embed embed;
2290\& 2290\&
2291\& // see if there is a chance of getting one that works 2291\& // see if there is a chance of getting one that works
2292\& // (remember that a flags value of 0 means autodetection) 2292\& // (remember that a flags value of 0 means autodetection)
2293\& loop_lo = ev_embeddable_backends () & ev_recommended_backends () 2293\& loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
2294\& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) 2294\& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
2295\& : 0; 2295\& : 0;
2296\& 2296\&
2297\& // 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
2298\& if (loop_lo) 2298\& if (loop_lo)
2299\& { 2299\& {
2300\& ev_embed_init (&embed, 0, loop_lo); 2300\& ev_embed_init (&embed, 0, loop_lo);
2301\& ev_embed_start (loop_hi, &embed); 2301\& ev_embed_start (loop_hi, &embed);
2302\& } 2302\& }
2303\& else 2303\& else
2304\& loop_lo = loop_hi; 2304\& loop_lo = loop_hi;
2305.Ve 2305.Ve
2306.PP 2306.PP
2307Example: Check if kqueue is available but not recommended and create 2307Example: Check if kqueue is available but not recommended and create
2308a kqueue backend for use with sockets (which usually work with any 2308a kqueue backend for use with sockets (which usually work with any
2309kqueue implementation). Store the kqueue/socket\-only event loop in 2309kqueue implementation). Store the kqueue/socket\-only event loop in
2310\&\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).
2311.PP 2311.PP
2312.Vb 3 2312.Vb 3
2313\& struct ev_loop *loop = ev_default_init (0); 2313\& struct ev_loop *loop = ev_default_init (0);
2314\& struct ev_loop *loop_socket = 0; 2314\& struct ev_loop *loop_socket = 0;
2315\& struct ev_embed embed; 2315\& struct ev_embed embed;
2316\& 2316\&
2317\& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) 2317\& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)
2318\& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) 2318\& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))
2319\& { 2319\& {
2320\& ev_embed_init (&embed, 0, loop_socket); 2320\& ev_embed_init (&embed, 0, loop_socket);
2321\& ev_embed_start (loop, &embed); 2321\& ev_embed_start (loop, &embed);
2322\& } 2322\& }
2323\& 2323\&
2324\& if (!loop_socket) 2324\& if (!loop_socket)
2325\& loop_socket = loop; 2325\& loop_socket = loop;
2326\& 2326\&
2327\& // 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
2328.Ve 2328.Ve
2329.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"
2330.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"
2331.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"
2332Fork 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
2378queue: 2378queue:
2379.IP "queueing from a signal handler context" 4 2379.IP "queueing from a signal handler context" 4
2380.IX Item "queueing from a signal handler context" 2380.IX Item "queueing from a signal handler context"
2381To 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
2382handler 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
2383some fictitiuous \s-1SIGUSR1\s0 handler: 2383some fictitious \s-1SIGUSR1\s0 handler:
2384.Sp 2384.Sp
2385.Vb 1 2385.Vb 1
2386\& static ev_async mysig; 2386\& static ev_async mysig;
2387\& 2387\&
2388\& static void 2388\& static void
2459.IP "ev_async_send (loop, ev_async *)" 4 2459.IP "ev_async_send (loop, ev_async *)" 4
2460.IX Item "ev_async_send (loop, ev_async *)" 2460.IX Item "ev_async_send (loop, ev_async *)"
2461Sends/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
2462an \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
2463\&\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
2464similar 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
2465section below on what exactly this means). 2465section below on what exactly this means).
2466.Sp 2466.Sp
2467This 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,
2468so 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
2469calls to \f(CW\*(C`ev_async_send\*(C'\fR. 2469calls to \f(CW\*(C`ev_async_send\*(C'\fR.
2470.IP "bool = ev_async_pending (ev_async *)" 4 2470.IP "bool = ev_async_pending (ev_async *)" 4
2471.IX Item "bool = ev_async_pending (ev_async *)" 2471.IX Item "bool = ev_async_pending (ev_async *)"
2472Returns 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
2473watcher 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
2474event loop. 2474event loop.
2475.Sp 2475.Sp
2476\&\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
2477the 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,
2478it 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
2479quickly check wether invoking the loop might be a good idea. 2479quickly check whether invoking the loop might be a good idea.
2480.Sp 2480.Sp
2481Not 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
2482wether it has been requested to make this watcher pending. 2482whether it has been requested to make this watcher pending.
2483.SH "OTHER FUNCTIONS" 2483.SH "OTHER FUNCTIONS"
2484.IX Header "OTHER FUNCTIONS" 2484.IX Header "OTHER FUNCTIONS"
2485There are some other functions of possible interest. Described. Here. Now. 2485There are some other functions of possible interest. Described. Here. Now.
2486.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
2487.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)"
2491or timeout without having to allocate/configure/start/stop/free one or 2491or timeout without having to allocate/configure/start/stop/free one or
2492more watchers yourself. 2492more watchers yourself.
2493.Sp 2493.Sp
2494If \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
2495is 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
2496\&\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.
2497.Sp 2497.Sp
2498If \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
2499started. 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
2500repeat = 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
2501dubious value. 2501dubious value.
2504passed 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
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 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
2506value passed to \f(CW\*(C`ev_once\*(C'\fR: 2506value passed to \f(CW\*(C`ev_once\*(C'\fR:
2507.Sp 2507.Sp
2508.Vb 7 2508.Vb 7
2509\& static void stdin_ready (int revents, void *arg) 2509\& static void stdin_ready (int revents, void *arg)
2510\& { 2510\& {
2511\& if (revents & EV_TIMEOUT) 2511\& if (revents & EV_TIMEOUT)
2512\& /* doh, nothing entered */; 2512\& /* doh, nothing entered */;
2513\& else if (revents & EV_READ) 2513\& else if (revents & EV_READ)
2514\& /* stdin might have data for us, joy! */; 2514\& /* stdin might have data for us, joy! */;
2515\& } 2515\& }
2516\& 2516\&
2517\& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); 2517\& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
2518.Ve 2518.Ve
2519.IP "ev_feed_event (ev_loop *, watcher *, int revents)" 4 2519.IP "ev_feed_event (ev_loop *, watcher *, int revents)" 4
2520.IX Item "ev_feed_event (ev_loop *, watcher *, int revents)" 2520.IX Item "ev_feed_event (ev_loop *, watcher *, int revents)"
2521Feeds 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
2522had 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
2525.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)"
2526Feed 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
2527the given events it. 2527the given events it.
2528.IP "ev_feed_signal_event (ev_loop *loop, int signum)" 4 2528.IP "ev_feed_signal_event (ev_loop *loop, int signum)" 4
2529.IX Item "ev_feed_signal_event (ev_loop *loop, int signum)" 2529.IX Item "ev_feed_signal_event (ev_loop *loop, int signum)"
2530Feed 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
2531loop!). 2531loop!).
2532.SH "LIBEVENT EMULATION" 2532.SH "LIBEVENT EMULATION"
2533.IX Header "LIBEVENT EMULATION" 2533.IX Header "LIBEVENT EMULATION"
2534Libev offers a compatibility emulation layer for libevent. It cannot 2534Libev offers a compatibility emulation layer for libevent. It cannot
2535emulate the internals of libevent, so here are some usage hints: 2535emulate the internals of libevent, so here are some usage hints:
2555The 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
2556to use the libev header file and library. 2556to use the libev header file and library.
2557.SH "\*(C+ SUPPORT" 2557.SH "\*(C+ SUPPORT"
2558.IX Header " SUPPORT" 2558.IX Header " SUPPORT"
2559Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow 2559Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow
2560you 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
2561the callback model to a model using method callbacks on objects. 2561the callback model to a model using method callbacks on objects.
2562.PP 2562.PP
2563To use it, 2563To use it,
2564.PP 2564.PP
2565.Vb 1 2565.Vb 1
2566\& #include <ev++.h> 2566\& #include <ev++.h>
2567.Ve 2567.Ve
2568.PP 2568.PP
2569This 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
2570of them macros) into the global namespace. All \*(C+ specific things are 2570of them macros) into the global namespace. All \*(C+ specific things are
2571put 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
2637thunking function, making it as fast as a direct C callback. 2637thunking function, making it as fast as a direct C callback.
2638.Sp 2638.Sp
2639Example: simple class declaration and watcher initialisation 2639Example: simple class declaration and watcher initialisation
2640.Sp 2640.Sp
2641.Vb 4 2641.Vb 4
2642\& struct myclass 2642\& struct myclass
2643\& { 2643\& {
2644\& void io_cb (ev::io &w, int revents) { } 2644\& void io_cb (ev::io &w, int revents) { }
2645\& } 2645\& }
2646\& 2646\&
2647\& myclass obj; 2647\& myclass obj;
2648\& ev::io iow; 2648\& ev::io iow;
2649\& iow.set <myclass, &myclass::io_cb> (&obj); 2649\& iow.set <myclass, &myclass::io_cb> (&obj);
2650.Ve 2650.Ve
2651.IP "w\->set<function> (void *data = 0)" 4 2651.IP "w\->set<function> (void *data = 0)" 4
2652.IX Item "w->set<function> (void *data = 0)" 2652.IX Item "w->set<function> (void *data = 0)"
2653Also 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
2654callback. 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
2659See 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.
2660.Sp 2660.Sp
2661Example: 2661Example:
2662.Sp 2662.Sp
2663.Vb 2 2663.Vb 2
2664\& static void io_cb (ev::io &w, int revents) { } 2664\& static void io_cb (ev::io &w, int revents) { }
2665\& iow.set <io_cb> (); 2665\& iow.set <io_cb> ();
2666.Ve 2666.Ve
2667.IP "w\->set (struct ev_loop *)" 4 2667.IP "w\->set (struct ev_loop *)" 4
2668.IX Item "w->set (struct ev_loop *)" 2668.IX Item "w->set (struct ev_loop *)"
2669Associates 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
2670do this when the watcher is inactive (and not pending either). 2670do this when the watcher is inactive (and not pending either).
2671.IP "w\->set ([args])" 4 2671.IP "w\->set ([arguments])" 4
2672.IX Item "w->set ([args])" 2672.IX Item "w->set ([arguments])"
2673Basically 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
2674called at least once. Unlike the C counterpart, an active watcher gets 2674called at least once. Unlike the C counterpart, an active watcher gets
2675automatically stopped and restarted when reconfiguring it with this 2675automatically stopped and restarted when reconfiguring it with this
2676method. 2676method.
2677.IP "w\->start ()" 4 2677.IP "w\->start ()" 4
2678.IX Item "w->start ()" 2678.IX Item "w->start ()"
2700.PP 2700.PP
2701Example: 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
2702the constructor. 2702the constructor.
2703.PP 2703.PP
2704.Vb 4 2704.Vb 4
2705\& class myclass 2705\& class myclass
2706\& { 2706\& {
2707\& ev::io io; void io_cb (ev::io &w, int revents); 2707\& ev::io io; void io_cb (ev::io &w, int revents);
2708\& ev:idle idle void idle_cb (ev::idle &w, int revents); 2708\& ev:idle idle void idle_cb (ev::idle &w, int revents);
2709\& 2709\&
2710\& myclass (int fd) 2710\& myclass (int fd)
2711\& { 2711\& {
2712\& io .set <myclass, &myclass::io_cb > (this); 2712\& io .set <myclass, &myclass::io_cb > (this);
2713\& idle.set <myclass, &myclass::idle_cb> (this); 2713\& idle.set <myclass, &myclass::idle_cb> (this);
2714\& 2714\&
2715\& io.start (fd, ev::READ); 2715\& io.start (fd, ev::READ);
2716\& } 2716\& }
2717\& }; 2717\& };
2718.Ve 2718.Ve
2719.SH "OTHER LANGUAGE BINDINGS" 2719.SH "OTHER LANGUAGE BINDINGS"
2720.IX Header "OTHER LANGUAGE BINDINGS" 2720.IX Header "OTHER LANGUAGE BINDINGS"
2721Libev does not offer other language bindings itself, but bindings for a 2721Libev does not offer other language bindings itself, but bindings for a
2722numbe 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
2723any interesting language binding in addition to the ones listed here, drop 2723any interesting language binding in addition to the ones listed here, drop
2724me a note. 2724me a note.
2725.IP "Perl" 4 2725.IP "Perl" 4
2726.IX Item "Perl" 2726.IX Item "Perl"
2727The \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
2728libev. \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,
2729there are additional modules that implement libev-compatible interfaces 2729there are additional modules that implement libev-compatible interfaces
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 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
2731\&\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).
2732.Sp 2732.Sp
2733It 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
2734<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).
2735.IP "Ruby" 4 2743.IP "Ruby" 4
2736.IX Item "Ruby" 2744.IX Item "Ruby"
2737Tony 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
2738of 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
2739more 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
2740<http://rev.rubyforge.org/>. 2748<http://rev.rubyforge.org/>.
2741.IP "D" 4 2749.IP "D" 4
2742.IX Item "D" 2750.IX Item "D"
2743Leandro 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
2744be 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>.
2745.SH "MACRO MAGIC" 2753.SH "MACRO MAGIC"
2746.IX Header "MACRO MAGIC" 2754.IX Header "MACRO MAGIC"
2747Libev can be compiled with a variety of options, the most fundamantal 2755Libev can be compiled with a variety of options, the most fundamental
2748of 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)
2749functions 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.
2750.PP 2758.PP
2751To 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
2752following macros are defined: 2760following macros are defined:
2756This 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
2757loop 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,
2758\&\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:
2759.Sp 2767.Sp
2760.Vb 3 2768.Vb 3
2761\& ev_unref (EV_A); 2769\& ev_unref (EV_A);
2762\& ev_timer_add (EV_A_ watcher); 2770\& ev_timer_add (EV_A_ watcher);
2763\& ev_loop (EV_A_ 0); 2771\& ev_loop (EV_A_ 0);
2764.Ve 2772.Ve
2765.Sp 2773.Sp
2766It 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,
2767which is often provided by the following macro. 2775which is often provided by the following macro.
2768.ie n .IP """EV_P""\fR, \f(CW""EV_P_""" 4 2776.ie n .IP """EV_P""\fR, \f(CW""EV_P_""" 4
2771This 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
2772loop 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,
2773\&\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:
2774.Sp 2782.Sp
2775.Vb 2 2783.Vb 2
2776\& // this is how ev_unref is being declared 2784\& // this is how ev_unref is being declared
2777\& static void ev_unref (EV_P); 2785\& static void ev_unref (EV_P);
2778\& 2786\&
2779\& // this is how you can declare your typical callback 2787\& // this is how you can declare your typical callback
2780\& static void cb (EV_P_ ev_timer *w, int revents) 2788\& static void cb (EV_P_ ev_timer *w, int revents)
2781.Ve 2789.Ve
2782.Sp 2790.Sp
2783It 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
2784suitable for use with \f(CW\*(C`EV_A\*(C'\fR. 2792suitable for use with \f(CW\*(C`EV_A\*(C'\fR.
2785.ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4 2793.ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4
2801Example: Declare and initialise a check watcher, utilising the above 2809Example: Declare and initialise a check watcher, utilising the above
2802macros so it will work regardless of whether multiple loops are supported 2810macros so it will work regardless of whether multiple loops are supported
2803or not. 2811or not.
2804.PP 2812.PP
2805.Vb 5 2813.Vb 5
2806\& static void 2814\& static void
2807\& check_cb (EV_P_ ev_timer *w, int revents) 2815\& check_cb (EV_P_ ev_timer *w, int revents)
2808\& { 2816\& {
2809\& ev_check_stop (EV_A_ w); 2817\& ev_check_stop (EV_A_ w);
2810\& } 2818\& }
2811\& 2819\&
2812\& ev_check check; 2820\& ev_check check;
2813\& ev_check_init (&check, check_cb); 2821\& ev_check_init (&check, check_cb);
2814\& ev_check_start (EV_DEFAULT_ &check); 2822\& ev_check_start (EV_DEFAULT_ &check);
2815\& ev_loop (EV_DEFAULT_ 0); 2823\& ev_loop (EV_DEFAULT_ 0);
2816.Ve 2824.Ve
2817.SH "EMBEDDING" 2825.SH "EMBEDDING"
2818.IX Header "EMBEDDING" 2826.IX Header "EMBEDDING"
2819Libev can (and often is) directly embedded into host 2827Libev can (and often is) directly embedded into host
2820applications. Examples of applications that embed it include the Deliantra 2828applications. Examples of applications that embed it include the Deliantra
2826you 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
2827libev somewhere in your source tree). 2835libev somewhere in your source tree).
2828.Sh "\s-1FILESETS\s0" 2836.Sh "\s-1FILESETS\s0"
2829.IX Subsection "FILESETS" 2837.IX Subsection "FILESETS"
2830Depending 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
2831in your app. 2839in your application.
2832.PP 2840.PP
2833\fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR 2841\fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR
2834.IX Subsection "CORE EVENT LOOP" 2842.IX Subsection "CORE EVENT LOOP"
2835.PP 2843.PP
2836To 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
2837configuration (no autoconf): 2845configuration (no autoconf):
2838.PP 2846.PP
2839.Vb 2 2847.Vb 2
2840\& #define EV_STANDALONE 1 2848\& #define EV_STANDALONE 1
2841\& #include "ev.c" 2849\& #include "ev.c"
2842.Ve 2850.Ve
2843.PP 2851.PP
2844This 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
2845single C source file only to provide the function implementations. To use 2853single C source file only to provide the function implementations. To use
2846it, 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
2847done 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
2848where you can put other configuration options): 2856where you can put other configuration options):
2849.PP 2857.PP
2850.Vb 2 2858.Vb 2
2851\& #define EV_STANDALONE 1 2859\& #define EV_STANDALONE 1
2852\& #include "ev.h" 2860\& #include "ev.h"
2853.Ve 2861.Ve
2854.PP 2862.PP
2855Both header files and implementation files can be compiled with a \*(C+ 2863Both header files and implementation files can be compiled with a \*(C+
2856compiler (at least, thats a stated goal, and breakage will be treated 2864compiler (at least, thats a stated goal, and breakage will be treated
2857as a bug). 2865as a bug).
2858.PP 2866.PP
2859You 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
2860in your include path (e.g. in libev/ when using \-Ilibev): 2868in your include path (e.g. in libev/ when using \-Ilibev):
2861.PP 2869.PP
2862.Vb 4 2870.Vb 4
2863\& ev.h 2871\& ev.h
2864\& ev.c 2872\& ev.c
2865\& ev_vars.h 2873\& ev_vars.h
2866\& ev_wrap.h 2874\& ev_wrap.h
2867\& 2875\&
2868\& ev_win32.c required on win32 platforms only 2876\& ev_win32.c required on win32 platforms only
2869\& 2877\&
2870\& 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)
2871\& 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)
2872\& 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)
2873\& 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)
2874\& 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)
2875.Ve 2883.Ve
2876.PP 2884.PP
2877\&\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
2878to compile this single file. 2886to compile this single file.
2879.PP 2887.PP
2881.IX Subsection "LIBEVENT COMPATIBILITY API" 2889.IX Subsection "LIBEVENT COMPATIBILITY API"
2882.PP 2890.PP
2883To include the libevent compatibility \s-1API\s0, also include: 2891To include the libevent compatibility \s-1API\s0, also include:
2884.PP 2892.PP
2885.Vb 1 2893.Vb 1
2886\& #include "event.c" 2894\& #include "event.c"
2887.Ve 2895.Ve
2888.PP 2896.PP
2889in the file including \fIev.c\fR, and: 2897in the file including \fIev.c\fR, and:
2890.PP 2898.PP
2891.Vb 1 2899.Vb 1
2892\& #include "event.h" 2900\& #include "event.h"
2893.Ve 2901.Ve
2894.PP 2902.PP
2895in 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.
2896.PP 2904.PP
2897You need the following additional files for this: 2905You need the following additional files for this:
2898.PP 2906.PP
2899.Vb 2 2907.Vb 2
2900\& event.h 2908\& event.h
2901\& event.c 2909\& event.c
2902.Ve 2910.Ve
2903.PP 2911.PP
2904\fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR 2912\fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR
2905.IX Subsection "AUTOCONF SUPPORT" 2913.IX Subsection "AUTOCONF SUPPORT"
2906.PP 2914.PP
2907Instead 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
2908whatever 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
2909\&\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
2910include \fIconfig.h\fR and configure itself accordingly. 2918include \fIconfig.h\fR and configure itself accordingly.
2911.PP 2919.PP
2912For this of course you need the m4 file: 2920For this of course you need the m4 file:
2913.PP 2921.PP
2914.Vb 1 2922.Vb 1
2915\& libev.m4 2923\& libev.m4
2916.Ve 2924.Ve
2917.Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" 2925.Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0"
2918.IX Subsection "PREPROCESSOR SYMBOLS/MACROS" 2926.IX Subsection "PREPROCESSOR SYMBOLS/MACROS"
2919Libev 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
2920define 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
2921autoconf is noted for every option. 2929autoconf is noted for every option.
2922.IP "\s-1EV_STANDALONE\s0" 4 2930.IP "\s-1EV_STANDALONE\s0" 4
2923.IX Item "EV_STANDALONE" 2931.IX Item "EV_STANDALONE"
2924Must 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
2925keeps libev from including \fIconfig.h\fR, and it also defines dummy 2933keeps libev from including \fIconfig.h\fR, and it also defines dummy
2927supported). 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
2928\&\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.
2929.IP "\s-1EV_USE_MONOTONIC\s0" 4 2937.IP "\s-1EV_USE_MONOTONIC\s0" 4
2930.IX Item "EV_USE_MONOTONIC" 2938.IX Item "EV_USE_MONOTONIC"
2931If 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
2932monotonic clock option at both compiletime and runtime. Otherwise no use 2940monotonic clock option at both compile time and runtime. Otherwise no use
2933of 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
2934usually have to link against librt or something similar. Enabling it when 2942usually have to link against librt or something similar. Enabling it when
2935the functionality isn't available is safe, though, although you have 2943the functionality isn't available is safe, though, although you have
2936to 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
2937function is hiding in (often \fI\-lrt\fR). 2945function is hiding in (often \fI\-lrt\fR).
2938.IP "\s-1EV_USE_REALTIME\s0" 4 2946.IP "\s-1EV_USE_REALTIME\s0" 4
2939.IX Item "EV_USE_REALTIME" 2947.IX Item "EV_USE_REALTIME"
2940If 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
2941realtime clock option at compiletime (and assume its availability at 2949real-time clock option at compile time (and assume its availability at
2942runtime if successful). Otherwise no use of the realtime clock option will 2950runtime if successful). Otherwise no use of the real-time clock option will
2943be 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
2944(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
2945note 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.
2946.IP "\s-1EV_USE_NANOSLEEP\s0" 4 2954.IP "\s-1EV_USE_NANOSLEEP\s0" 4
2947.IX Item "EV_USE_NANOSLEEP" 2955.IX Item "EV_USE_NANOSLEEP"
2955If 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
29562.7 or newer, otherwise disabled. 29642.7 or newer, otherwise disabled.
2957.IP "\s-1EV_USE_SELECT\s0" 4 2965.IP "\s-1EV_USE_SELECT\s0" 4
2958.IX Item "EV_USE_SELECT" 2966.IX Item "EV_USE_SELECT"
2959If 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
2960\&\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
2961other method takes over, select will be it. Otherwise the select backend 2969other method takes over, select will be it. Otherwise the select backend
2962will not be compiled in. 2970will not be compiled in.
2963.IP "\s-1EV_SELECT_USE_FD_SET\s0" 4 2971.IP "\s-1EV_SELECT_USE_FD_SET\s0" 4
2964.IX Item "EV_SELECT_USE_FD_SET" 2972.IX Item "EV_SELECT_USE_FD_SET"
2965If 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
2966structure. 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
2967\&\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
2968exotic systems. This usually limits the range of file descriptors to some 2976exotic systems. This usually limits the range of file descriptors to some
2969low limit such as 1024 or might have other limitations (winsocket only 2977low limit such as 1024 or might have other limitations (winsocket only
2970allows 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
2971influence 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.
2972.IP "\s-1EV_SELECT_IS_WINSOCKET\s0" 4 2980.IP "\s-1EV_SELECT_IS_WINSOCKET\s0" 4
301410 port style backend. Its availability will be detected at runtime, 302210 port style backend. Its availability will be detected at runtime,
3015otherwise another method will be used as fallback. This is the preferred 3023otherwise another method will be used as fallback. This is the preferred
3016backend for Solaris 10 systems. 3024backend for Solaris 10 systems.
3017.IP "\s-1EV_USE_DEVPOLL\s0" 4 3025.IP "\s-1EV_USE_DEVPOLL\s0" 4
3018.IX Item "EV_USE_DEVPOLL" 3026.IX Item "EV_USE_DEVPOLL"
3019reserved for future expansion, works like the \s-1USE\s0 symbols above. 3027Reserved for future expansion, works like the \s-1USE\s0 symbols above.
3020.IP "\s-1EV_USE_INOTIFY\s0" 4 3028.IP "\s-1EV_USE_INOTIFY\s0" 4
3021.IX Item "EV_USE_INOTIFY" 3029.IX Item "EV_USE_INOTIFY"
3022If 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
3023interface 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
3024be 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
3029access 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
3030type 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
3031that 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"
3032as 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.
3033.Sp 3041.Sp
3034In 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
3035(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.
3036.IP "\s-1EV_H\s0" 4 3044.IP "\s-1EV_H\s0" 4
3037.IX Item "EV_H" 3045.IX Item "EV_H"
3038The 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
3039undefined 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
3074When doing priority-based operations, libev usually has to linearly search 3082When doing priority-based operations, libev usually has to linearly search
3075all 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
3076and 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
3077fine. 3085fine.
3078.Sp 3086.Sp
3079If 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
3080\&\f(CW0\fR will save some memory and cpu. 3088\&\f(CW0\fR will save some memory and \s-1CPU\s0.
3081.IP "\s-1EV_PERIODIC_ENABLE\s0" 4 3089.IP "\s-1EV_PERIODIC_ENABLE\s0" 4
3082.IX Item "EV_PERIODIC_ENABLE" 3090.IX Item "EV_PERIODIC_ENABLE"
3083If 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
3084defined 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
3085code. 3093code.
3106defined to be \f(CW0\fR, then they are not. 3114defined to be \f(CW0\fR, then they are not.
3107.IP "\s-1EV_MINIMAL\s0" 4 3115.IP "\s-1EV_MINIMAL\s0" 4
3108.IX Item "EV_MINIMAL" 3116.IX Item "EV_MINIMAL"
3109If 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
3110speed, 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
3111inlining decisions, saves roughly 30% codesize of amd64. It also selects a 3119inlining decisions, saves roughly 30% code size on amd64. It also selects a
3112much smaller 2\-heap for timer management over the default 4\-heap. 3120much smaller 2\-heap for timer management over the default 4\-heap.
3113.IP "\s-1EV_PID_HASHSIZE\s0" 4 3121.IP "\s-1EV_PID_HASHSIZE\s0" 4
3114.IX Item "EV_PID_HASHSIZE" 3122.IX Item "EV_PID_HASHSIZE"
3115\&\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
3116pid. 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
3126.IP "\s-1EV_USE_4HEAP\s0" 4 3134.IP "\s-1EV_USE_4HEAP\s0" 4
3127.IX Item "EV_USE_4HEAP" 3135.IX Item "EV_USE_4HEAP"
3128Heaps 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
3129timer 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
3130to \f(CW1\fR. The 4\-heap uses more complicated (longer) code but has 3138to \f(CW1\fR. The 4\-heap uses more complicated (longer) code but has
3131noticably faster performance with many (thousands) of watchers. 3139noticeably faster performance with many (thousands) of watchers.
3132.Sp 3140.Sp
3133The 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
3134(disabled). 3142(disabled).
3135.IP "\s-1EV_HEAP_CACHE_AT\s0" 4 3143.IP "\s-1EV_HEAP_CACHE_AT\s0" 4
3136.IX Item "EV_HEAP_CACHE_AT" 3144.IX Item "EV_HEAP_CACHE_AT"
3137Heaps 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
3138timer and periodics heap, libev can cache the timestamp (\fIat\fR) within 3146timer and periodics heap, libev can cache the timestamp (\fIat\fR) within
3139the 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),
3140which 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,
3141but avoids random read accesses on heap changes. This improves performance 3149but avoids random read accesses on heap changes. This improves performance
3142noticably with with many (hundreds) of watchers. 3150noticeably with with many (hundreds) of watchers.
3143.Sp 3151.Sp
3144The 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
3145(disabled). 3153(disabled).
3146.IP "\s-1EV_VERIFY\s0" 4 3154.IP "\s-1EV_VERIFY\s0" 4
3147.IX Item "EV_VERIFY" 3155.IX Item "EV_VERIFY"
3163though, and it must be identical each time. 3171though, and it must be identical each time.
3164.Sp 3172.Sp
3165For example, the perl \s-1EV\s0 module uses something like this: 3173For example, the perl \s-1EV\s0 module uses something like this:
3166.Sp 3174.Sp
3167.Vb 3 3175.Vb 3
3168\& #define EV_COMMON \e 3176\& #define EV_COMMON \e
3169\& SV *self; /* contains this struct */ \e 3177\& SV *self; /* contains this struct */ \e
3170\& SV *cb_sv, *fh /* note no trailing ";" */ 3178\& SV *cb_sv, *fh /* note no trailing ";" */
3171.Ve 3179.Ve
3172.IP "\s-1EV_CB_DECLARE\s0 (type)" 4 3180.IP "\s-1EV_CB_DECLARE\s0 (type)" 4
3173.IX Item "EV_CB_DECLARE (type)" 3181.IX Item "EV_CB_DECLARE (type)"
3174.PD 0 3182.PD 0
3175.IP "\s-1EV_CB_INVOKE\s0 (watcher, revents)" 4 3183.IP "\s-1EV_CB_INVOKE\s0 (watcher, revents)" 4
3183their default definitions. One possible use for overriding these is to 3191their default definitions. One possible use for overriding these is to
3184avoid 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
3185method calls instead of plain function calls in \*(C+. 3193method calls instead of plain function calls in \*(C+.
3186.Sh "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" 3194.Sh "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0"
3187.IX Subsection "EXPORTED API SYMBOLS" 3195.IX Subsection "EXPORTED API SYMBOLS"
3188If 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
3189exported symbols, you can use the provided \fISymbol.*\fR files which list 3197exported symbols, you can use the provided \fISymbol.*\fR files which list
3190all public symbols, one per line: 3198all public symbols, one per line:
3191.PP 3199.PP
3192.Vb 2 3200.Vb 2
3193\& Symbols.ev for libev proper 3201\& Symbols.ev for libev proper
3194\& Symbols.event for the libevent emulation 3202\& Symbols.event for the libevent emulation
3195.Ve 3203.Ve
3196.PP 3204.PP
3197This 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
3198multiple versions of libev linked together (which is obviously bad in 3206multiple versions of libev linked together (which is obviously bad in
3199itself, but sometimes it is inconvinient to avoid this). 3207itself, but sometimes it is inconvenient to avoid this).
3200.PP 3208.PP
3201A 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
3202include before including \fIev.h\fR: 3210include before including \fIev.h\fR:
3203.PP 3211.PP
3204.Vb 1 3212.Vb 1
3225.PP 3233.PP
3226The 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
3227that everybody includes and which overrides some configure choices: 3235that everybody includes and which overrides some configure choices:
3228.PP 3236.PP
3229.Vb 9 3237.Vb 9
3230\& #define EV_MINIMAL 1 3238\& #define EV_MINIMAL 1
3231\& #define EV_USE_POLL 0 3239\& #define EV_USE_POLL 0
3232\& #define EV_MULTIPLICITY 0 3240\& #define EV_MULTIPLICITY 0
3233\& #define EV_PERIODIC_ENABLE 0 3241\& #define EV_PERIODIC_ENABLE 0
3234\& #define EV_STAT_ENABLE 0 3242\& #define EV_STAT_ENABLE 0
3235\& #define EV_FORK_ENABLE 0 3243\& #define EV_FORK_ENABLE 0
3236\& #define EV_CONFIG_H <config.h> 3244\& #define EV_CONFIG_H <config.h>
3237\& #define EV_MINPRI 0 3245\& #define EV_MINPRI 0
3238\& #define EV_MAXPRI 0 3246\& #define EV_MAXPRI 0
3239\& 3247\&
3240\& #include "ev++.h" 3248\& #include "ev++.h"
3241.Ve 3249.Ve
3242.PP 3250.PP
3243And 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:
3244.PP 3252.PP
3245.Vb 2 3253.Vb 2
3246\& #include "ev_cpp.h" 3254\& #include "ev_cpp.h"
3247\& #include "ev.c" 3255\& #include "ev.c"
3248.Ve 3256.Ve
3249.SH "THREADS AND COROUTINES" 3257.SH "THREADS AND COROUTINES"
3250.IX Header "THREADS AND COROUTINES" 3258.IX Header "THREADS AND COROUTINES"
3251.Sh "\s-1THREADS\s0" 3259.Sh "\s-1THREADS\s0"
3252.IX Subsection "THREADS" 3260.IX Subsection "THREADS"
3253Libev itself is completely threadsafe, but it uses no locking. This 3261Libev itself is completely thread-safe, but it uses no locking. This
3254means 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
3255only 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
3256parameter. 3264parameter.
3257.PP 3265.PP
3258Or put differently: calls with different loop parameters can be done in 3266Or put differently: calls with different loop parameters can be done in
3263.PP 3271.PP
3264If 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
3265help you but by giving some generic advice: 3273help you but by giving some generic advice:
3266.IP "\(bu" 4 3274.IP "\(bu" 4
3267most applications have a main thread: use the default libev loop 3275most applications have a main thread: use the default libev loop
3268in 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.
3269.Sp 3277.Sp
3270This helps integrating other libraries or software modules that use libev 3278This helps integrating other libraries or software modules that use libev
3271themselves and don't care/know about threading. 3279themselves and don't care/know about threading.
3272.IP "\(bu" 4 3280.IP "\(bu" 4
3273one loop per thread is usually a good model. 3281one loop per thread is usually a good model.
3274.Sp 3282.Sp
3275Doing this is almost never wrong, sometimes a better-performance model 3283Doing this is almost never wrong, sometimes a better-performance model
3276exists, but it is always a good start. 3284exists, but it is always a good start.
3277.IP "\(bu" 4 3285.IP "\(bu" 4
3278other models exist, such as the leader/follower pattern, where one 3286other models exist, such as the leader/follower pattern, where one
3279loop 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.
3280.Sp 3288.Sp
3281Chosing 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
3282better than you currently do :\-) 3290better than you currently do :\-)
3283.IP "\(bu" 4 3291.IP "\(bu" 4
3284often 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
3285event 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
3286threads safely (or from signal contexts...). 3294threads safely (or from signal contexts...).
3287.Sh "\s-1COROUTINES\s0" 3295.Sh "\s-1COROUTINES\s0"
3288.IX Subsection "COROUTINES" 3296.IX Subsection "COROUTINES"
3289Libev is much more accomodating to coroutines (\*(L"cooperative threads\*(R"): 3297Libev is much more accommodating to coroutines (\*(L"cooperative threads\*(R"):
3290libev fully supports nesting calls to it's functions from different 3298libev fully supports nesting calls to it's functions from different
3291coroutines (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
3292different coroutines and switch freely between both coroutines running the 3300different coroutines and switch freely between both coroutines running the
3293loop, 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
3294you 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.
3334fixed position in the storage array. 3342fixed position in the storage array.
3335.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
3336.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)"
3337A 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
3338libev to recalculate its status (and possibly tell the kernel, depending 3346libev to recalculate its status (and possibly tell the kernel, depending
3339on 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).
3340.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
3341.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)"
3342.PD 0 3350.PD 0
3343.IP "Priority handling: O(number_of_priorities)" 4 3351.IP "Priority handling: O(number_of_priorities)" 4
3344.IX Item "Priority handling: O(number_of_priorities)" 3352.IX Item "Priority handling: O(number_of_priorities)"
3353.IP "Processing ev_async_send: O(number_of_async_watchers)" 4 3361.IP "Processing ev_async_send: O(number_of_async_watchers)" 4
3354.IX Item "Processing ev_async_send: O(number_of_async_watchers)" 3362.IX Item "Processing ev_async_send: O(number_of_async_watchers)"
3355.IP "Processing signals: O(max_signal_number)" 4 3363.IP "Processing signals: O(max_signal_number)" 4
3356.IX Item "Processing signals: O(max_signal_number)" 3364.IX Item "Processing signals: O(max_signal_number)"
3357.PD 3365.PD
3358Sending 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
3359calls in the current loop iteration. Checking for async and signal events 3367calls in the current loop iteration. Checking for async and signal events
3360involves iterating over all running async watchers or all signal numbers. 3368involves iterating over all running async watchers or all signal numbers.
3361.SH "Win32 platform limitations and workarounds" 3369.SH "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS"
3362.IX Header "Win32 platform limitations and workarounds" 3370.IX Header "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS"
3363Win32 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
3364requires, 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
3365model. Libev still offers limited functionality on this platform in 3373model. Libev still offers limited functionality on this platform in
3366the 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
3367descriptors. This only applies when using Win32 natively, not when using 3375descriptors. This only applies when using Win32 natively, not when using
3373way (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).
3374.PP 3382.PP
3375There is no supported compilation method available on windows except 3383There is no supported compilation method available on windows except
3376embedding it into other applications. 3384embedding it into other applications.
3377.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
3378Due 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
3379the abysmal performance of winsockets, using a large number of sockets 3394the abysmal performance of winsockets, using a large number of sockets
3380is not recommended (and not reasonable). If your program needs to use 3395is not recommended (and not reasonable). If your program needs to use
3381more 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
3382different implementation for windows, as libev offers the \s-1POSIX\s0 readiness 3397different implementation for windows, as libev offers the \s-1POSIX\s0 readiness
3383notification model, which cannot be implemented efficiently on windows 3398notification model, which cannot be implemented efficiently on windows
3384(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
3385.IP "The winsocket select function" 4 3419.IP "The winsocket select function" 4
3386.IX Item "The winsocket select function" 3420.IX Item "The winsocket select function"
3387The winsocket \f(CW\*(C`select\*(C'\fR function doesn't follow \s-1POSIX\s0 in that it 3421The winsocket \f(CW\*(C`select\*(C'\fR function doesn't follow \s-1POSIX\s0 in that it
3388requires socket \fIhandles\fR and not socket \fIfile descriptors\fR (it is 3422requires socket \fIhandles\fR and not socket \fIfile descriptors\fR (it is
3389also extremely buggy). This makes select very inefficient, and also 3423also extremely buggy). This makes select very inefficient, and also
3390requires a mapping from file descriptors to socket handles. See the 3424requires a mapping from file descriptors to socket handles (the Microsoft
3425C runtime provides the function \f(CW\*(C`_open_osfhandle\*(C'\fR for this). See the
3391discussion of the \f(CW\*(C`EV_SELECT_USE_FD_SET\*(C'\fR, \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR and 3426discussion of the \f(CW\*(C`EV_SELECT_USE_FD_SET\*(C'\fR, \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR and
3392\&\f(CW\*(C`EV_FD_TO_WIN32_HANDLE\*(C'\fR preprocessor symbols for more info. 3427\&\f(CW\*(C`EV_FD_TO_WIN32_HANDLE\*(C'\fR preprocessor symbols for more info.
3393.Sp 3428.Sp
3394The configuration for a \*(L"naked\*(R" win32 using the microsoft runtime 3429The configuration for a \*(L"naked\*(R" win32 using the Microsoft runtime
3395libraries and raw winsocket select is: 3430libraries and raw winsocket select is:
3396.Sp 3431.Sp
3397.Vb 2 3432.Vb 2
3398\& #define EV_USE_SELECT 1 3433\& #define EV_USE_SELECT 1
3399\& #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 */
3400.Ve 3435.Ve
3401.Sp 3436.Sp
3402Note 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
3403complexity in the O(nA\*^X) range when using win32. 3438complexity in the O(nA\*^X) range when using win32.
3404.IP "Limited number of file descriptors" 4 3439.IP "Limited number of file descriptors" 4
3405.IX Item "Limited number of file descriptors" 3440.IX Item "Limited number of file descriptors"
3406Windows has numerous arbitrary (and low) limits on things. 3441Windows has numerous arbitrary (and low) limits on things.
3407.Sp 3442.Sp
3408Early versions of winsocket's select only supported waiting for a maximum 3443Early versions of winsocket's select only supported waiting for a maximum
3409of \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
3410can 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
3411recommends 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
3412previous thread in each. Great). 3447previous thread in each. Great).
3413.Sp 3448.Sp
3414Newer 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
3415to 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
3416call (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
3417select emulation on windows). 3452select emulation on windows).
3418.Sp 3453.Sp
3419Another limit is the number of file descriptors in the microsoft runtime 3454Another limit is the number of file descriptors in the Microsoft runtime
3420libraries, 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
3421or something like this inside microsoft). You can increase this by calling 3456or something like this inside Microsoft). You can increase this by calling
3422\&\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
3423arbitrary limit), but is broken in many versions of the microsoft runtime 3458arbitrary limit), but is broken in many versions of the Microsoft runtime
3424libraries. 3459libraries.
3425.Sp 3460.Sp
3426This 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
3427windows 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
3428wrap 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
3429calling select (O(nA\*^X)) will likely make this unworkable. 3464calling select (O(nA\*^X)) will likely make this unworkable.
3430.SH "PORTABILITY REQUIREMENTS" 3465.SH "PORTABILITY REQUIREMENTS"
3431.IX Header "PORTABILITY REQUIREMENTS" 3466.IX Header "PORTABILITY REQUIREMENTS"
3432In 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
3433additional 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.
3434.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
3435.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
3436.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"
3437The 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
3438\&\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
3475scared by this. 3518scared by this.
3476.PP 3519.PP
3477However, these are unavoidable for many reasons. For one, each compiler 3520However, these are unavoidable for many reasons. For one, each compiler
3478has different warnings, and each user has different tastes regarding 3521has different warnings, and each user has different tastes regarding
3479warning options. \*(L"Warn-free\*(R" code therefore cannot be a goal except when 3522warning options. \*(L"Warn-free\*(R" code therefore cannot be a goal except when
3480targetting a specific compiler and compiler-version. 3523targeting a specific compiler and compiler-version.
3481.PP 3524.PP
3482Another reason is that some compiler warnings require elaborate 3525Another reason is that some compiler warnings require elaborate
3483workarounds, or other changes to the code that make it less clear and less 3526workarounds, or other changes to the code that make it less clear and less
3484maintainable. 3527maintainable.
3485.PP 3528.PP
3486And of course, some compiler warnings are just plain stupid, or simply 3529And of course, some compiler warnings are just plain stupid, or simply
3487wrong (because they don't actually warn about the cindition their message 3530wrong (because they don't actually warn about the condition their message
3488seems to warn about). 3531seems to warn about).
3489.PP 3532.PP
3490While libev is written to generate as few warnings as possible, 3533While libev is written to generate as few warnings as possible,
3491\&\*(L"warn-free\*(R" code is not a goal, and it is recommended not to build libev 3534\&\*(L"warn-free\*(R" code is not a goal, and it is recommended not to build libev
3492with any compiler warnings enabled unless you are prepared to cope with 3535with any compiler warnings enabled unless you are prepared to cope with
3504\& ==2274== definitely lost: 0 bytes in 0 blocks. 3547\& ==2274== definitely lost: 0 bytes in 0 blocks.
3505\& ==2274== possibly lost: 0 bytes in 0 blocks. 3548\& ==2274== possibly lost: 0 bytes in 0 blocks.
3506\& ==2274== still reachable: 256 bytes in 1 blocks. 3549\& ==2274== still reachable: 256 bytes in 1 blocks.
3507.Ve 3550.Ve
3508.PP 3551.PP
3509then there is no memory leak. Similarly, under some circumstances, 3552Then there is no memory leak. Similarly, under some circumstances,
3510valgrind might report kernel bugs as if it were a bug in libev, or it 3553valgrind might report kernel bugs as if it were a bug in libev, or it
3511might be confused (it is a very good tool, but only a tool). 3554might be confused (it is a very good tool, but only a tool).
3512.PP 3555.PP
3513If you are unsure about something, feel free to contact the mailing list 3556If you are unsure about something, feel free to contact the mailing list
3514with the full valgrind report and an explanation on why you think this is 3557with the full valgrind report and an explanation on why you think this is
3522.IX Header "AUTHOR" 3565.IX Header "AUTHOR"
3523Marc Lehmann <libev@schmorp.de>. 3566Marc Lehmann <libev@schmorp.de>.
3524.SH "POD ERRORS" 3567.SH "POD ERRORS"
3525.IX Header "POD ERRORS" 3568.IX Header "POD ERRORS"
3526Hey! \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
3527.IP "Around line 3107:" 4 3570.IP "Around line 3116:" 4
3528.IX Item "Around line 3107:" 3571.IX Item "Around line 3116:"
3529You forgot a '=back' before '=head2' 3572You forgot a '=back' before '=head2'

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