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124.\" ======================================================================== 133.\" ========================================================================
125.\" 134.\"
126.IX Title "LIBEV 3" 135.IX Title "LIBEV 3"
127.TH LIBEV 3 "2012-02-04" "libev-4.11" "libev - high performance full featured event loop" 136.TH LIBEV 3 "2013-12-27" "libev-4.15" "libev - high performance full featured event loop"
128.\" For nroff, turn off justification. Always turn off hyphenation; it makes 137.\" For nroff, turn off justification. Always turn off hyphenation; it makes
129.\" way too many mistakes in technical documents. 138.\" way too many mistakes in technical documents.
130.if n .ad l 139.if n .ad l
131.nh 140.nh
132.SH "NAME" 141.SH "NAME"
134.SH "SYNOPSIS" 143.SH "SYNOPSIS"
135.IX Header "SYNOPSIS" 144.IX Header "SYNOPSIS"
136.Vb 1 145.Vb 1
137\& #include <ev.h> 146\& #include <ev.h>
138.Ve 147.Ve
139.SS "\s-1EXAMPLE\s0 \s-1PROGRAM\s0" 148.SS "\s-1EXAMPLE PROGRAM\s0"
140.IX Subsection "EXAMPLE PROGRAM" 149.IX Subsection "EXAMPLE PROGRAM"
141.Vb 2 150.Vb 2
142\& // a single header file is required 151\& // a single header file is required
143\& #include <ev.h> 152\& #include <ev.h>
144\& 153\&
212throughout this document. 221throughout this document.
213.SH "WHAT TO READ WHEN IN A HURRY" 222.SH "WHAT TO READ WHEN IN A HURRY"
214.IX Header "WHAT TO READ WHEN IN A HURRY" 223.IX Header "WHAT TO READ WHEN IN A HURRY"
215This manual tries to be very detailed, but unfortunately, this also makes 224This manual tries to be very detailed, but unfortunately, this also makes
216it very long. If you just want to know the basics of libev, I suggest 225it very long. If you just want to know the basics of libev, I suggest
217reading \*(L"\s-1ANATOMY\s0 \s-1OF\s0 A \s-1WATCHER\s0\*(R", then the \*(L"\s-1EXAMPLE\s0 \s-1PROGRAM\s0\*(R" above and 226reading \*(L"\s-1ANATOMY OF A WATCHER\*(R"\s0, then the \*(L"\s-1EXAMPLE PROGRAM\*(R"\s0 above and
218look up the missing functions in \*(L"\s-1GLOBAL\s0 \s-1FUNCTIONS\s0\*(R" and the \f(CW\*(C`ev_io\*(C'\fR and 227look up the missing functions in \*(L"\s-1GLOBAL FUNCTIONS\*(R"\s0 and the \f(CW\*(C`ev_io\*(C'\fR and
219\&\f(CW\*(C`ev_timer\*(C'\fR sections in \*(L"\s-1WATCHER\s0 \s-1TYPES\s0\*(R". 228\&\f(CW\*(C`ev_timer\*(C'\fR sections in \*(L"\s-1WATCHER TYPES\*(R"\s0.
220.SH "ABOUT LIBEV" 229.SH "ABOUT LIBEV"
221.IX Header "ABOUT LIBEV" 230.IX Header "ABOUT LIBEV"
222Libev is an event loop: you register interest in certain events (such as a 231Libev is an event loop: you register interest in certain events (such as a
223file descriptor being readable or a timeout occurring), and it will manage 232file descriptor being readable or a timeout occurring), and it will manage
224these event sources and provide your program with events. 233these event sources and provide your program with events.
255more info about various configuration options please have a look at 264more info about various configuration options please have a look at
256\&\fB\s-1EMBED\s0\fR section in this manual. If libev was configured without support 265\&\fB\s-1EMBED\s0\fR section in this manual. If libev was configured without support
257for multiple event loops, then all functions taking an initial argument of 266for multiple event loops, then all functions taking an initial argument of
258name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) will not have 267name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) will not have
259this argument. 268this argument.
260.SS "\s-1TIME\s0 \s-1REPRESENTATION\s0" 269.SS "\s-1TIME REPRESENTATION\s0"
261.IX Subsection "TIME REPRESENTATION" 270.IX Subsection "TIME REPRESENTATION"
262Libev represents time as a single floating point number, representing 271Libev represents time as a single floating point number, representing
263the (fractional) number of seconds since the (\s-1POSIX\s0) epoch (in practice 272the (fractional) number of seconds since the (\s-1POSIX\s0) epoch (in practice
264somewhere near the beginning of 1970, details are complicated, don't 273somewhere near the beginning of 1970, details are complicated, don't
265ask). This type is called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use 274ask). This type is called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use
367current system. To find which embeddable backends might be supported on 376current system. To find which embeddable backends might be supported on
368the current system, you would need to look at \f(CW\*(C`ev_embeddable_backends () 377the current system, you would need to look at \f(CW\*(C`ev_embeddable_backends ()
369& ev_supported_backends ()\*(C'\fR, likewise for recommended ones. 378& ev_supported_backends ()\*(C'\fR, likewise for recommended ones.
370.Sp 379.Sp
371See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. 380See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info.
372.IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4 381.IP "ev_set_allocator (void *(*cb)(void *ptr, long size) throw ())" 4
373.IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))" 382.IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size) throw ())"
374Sets the allocation function to use (the prototype is similar \- the 383Sets the allocation function to use (the prototype is similar \- the
375semantics are identical to the \f(CW\*(C`realloc\*(C'\fR C89/SuS/POSIX function). It is 384semantics are identical to the \f(CW\*(C`realloc\*(C'\fR C89/SuS/POSIX function). It is
376used to allocate and free memory (no surprises here). If it returns zero 385used to allocate and free memory (no surprises here). If it returns zero
377when memory needs to be allocated (\f(CW\*(C`size != 0\*(C'\fR), the library might abort 386when memory needs to be allocated (\f(CW\*(C`size != 0\*(C'\fR), the library might abort
378or take some potentially destructive action. 387or take some potentially destructive action.
404\& } 413\& }
405\& 414\&
406\& ... 415\& ...
407\& ev_set_allocator (persistent_realloc); 416\& ev_set_allocator (persistent_realloc);
408.Ve 417.Ve
409.IP "ev_set_syserr_cb (void (*cb)(const char *msg))" 4 418.IP "ev_set_syserr_cb (void (*cb)(const char *msg) throw ())" 4
410.IX Item "ev_set_syserr_cb (void (*cb)(const char *msg))" 419.IX Item "ev_set_syserr_cb (void (*cb)(const char *msg) throw ())"
411Set the callback function to call on a retryable system call error (such 420Set the callback function to call on a retryable system call error (such
412as failed select, poll, epoll_wait). The message is a printable string 421as failed select, poll, epoll_wait). The message is a printable string
413indicating the system call or subsystem causing the problem. If this 422indicating the system call or subsystem causing the problem. If this
414callback is set, then libev will expect it to remedy the situation, no 423callback is set, then libev will expect it to remedy the situation, no
415matter what, when it returns. That is, libev will generally retry the 424matter what, when it returns. That is, libev will generally retry the
514.IX Item "EVFLAG_NOENV" 523.IX Item "EVFLAG_NOENV"
515If this flag bit is or'ed into the flag value (or the program runs setuid 524If this flag bit is or'ed into the flag value (or the program runs setuid
516or setgid) then libev will \fInot\fR look at the environment variable 525or setgid) then libev will \fInot\fR look at the environment variable
517\&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will 526\&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will
518override the flags completely if it is found in the environment. This is 527override the flags completely if it is found in the environment. This is
519useful to try out specific backends to test their performance, or to work 528useful to try out specific backends to test their performance, to work
520around bugs. 529around bugs, or to make libev threadsafe (accessing environment variables
530cannot be done in a threadsafe way, but usually it works if no other
531thread modifies them).
521.ie n .IP """EVFLAG_FORKCHECK""" 4 532.ie n .IP """EVFLAG_FORKCHECK""" 4
522.el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4 533.el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4
523.IX Item "EVFLAG_FORKCHECK" 534.IX Item "EVFLAG_FORKCHECK"
524Instead of calling \f(CW\*(C`ev_loop_fork\*(C'\fR manually after a fork, you can also 535Instead of calling \f(CW\*(C`ev_loop_fork\*(C'\fR manually after a fork, you can also
525make libev check for a fork in each iteration by enabling this flag. 536make libev check for a fork in each iteration by enabling this flag.
572\&\f(CW\*(C`sigprocmask\*(C'\fR, whose behaviour is officially unspecified. 583\&\f(CW\*(C`sigprocmask\*(C'\fR, whose behaviour is officially unspecified.
573.Sp 584.Sp
574This flag's behaviour will become the default in future versions of libev. 585This flag's behaviour will become the default in future versions of libev.
575.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 586.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4
576.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 587.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4
577.IX Item "EVBACKEND_SELECT (value 1, portable select backend)" 588.IX Item "EVBACKEND_SELECT (value 1, portable select backend)"
578This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as 589This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as
579libev tries to roll its own fd_set with no limits on the number of fds, 590libev tries to roll its own fd_set with no limits on the number of fds,
580but if that fails, expect a fairly low limit on the number of fds when 591but if that fails, expect a fairly low limit on the number of fds when
581using this backend. It doesn't scale too well (O(highest_fd)), but its 592using this backend. It doesn't scale too well (O(highest_fd)), but its
582usually the fastest backend for a low number of (low-numbered :) fds. 593usually the fastest backend for a low number of (low-numbered :) fds.
591This backend maps \f(CW\*(C`EV_READ\*(C'\fR to the \f(CW\*(C`readfds\*(C'\fR set and \f(CW\*(C`EV_WRITE\*(C'\fR to the 602This backend maps \f(CW\*(C`EV_READ\*(C'\fR to the \f(CW\*(C`readfds\*(C'\fR set and \f(CW\*(C`EV_WRITE\*(C'\fR to the
592\&\f(CW\*(C`writefds\*(C'\fR set (and to work around Microsoft Windows bugs, also onto the 603\&\f(CW\*(C`writefds\*(C'\fR set (and to work around Microsoft Windows bugs, also onto the
593\&\f(CW\*(C`exceptfds\*(C'\fR set on that platform). 604\&\f(CW\*(C`exceptfds\*(C'\fR set on that platform).
594.ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 605.ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4
595.el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4 606.el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4
596.IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)" 607.IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)"
597And this is your standard \fIpoll\fR\|(2) backend. It's more complicated 608And this is your standard \fIpoll\fR\|(2) backend. It's more complicated
598than select, but handles sparse fds better and has no artificial 609than select, but handles sparse fds better and has no artificial
599limit on the number of fds you can use (except it will slow down 610limit on the number of fds you can use (except it will slow down
600considerably with a lot of inactive fds). It scales similarly to select, 611considerably with a lot of inactive fds). It scales similarly to select,
601i.e. O(total_fds). See the entry for \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR, above, for 612i.e. O(total_fds). See the entry for \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR, above, for
603.Sp 614.Sp
604This backend maps \f(CW\*(C`EV_READ\*(C'\fR to \f(CW\*(C`POLLIN | POLLERR | POLLHUP\*(C'\fR, and 615This backend maps \f(CW\*(C`EV_READ\*(C'\fR to \f(CW\*(C`POLLIN | POLLERR | POLLHUP\*(C'\fR, and
605\&\f(CW\*(C`EV_WRITE\*(C'\fR to \f(CW\*(C`POLLOUT | POLLERR | POLLHUP\*(C'\fR. 616\&\f(CW\*(C`EV_WRITE\*(C'\fR to \f(CW\*(C`POLLOUT | POLLERR | POLLHUP\*(C'\fR.
606.ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 617.ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4
607.el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 618.el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4
608.IX Item "EVBACKEND_EPOLL (value 4, Linux)" 619.IX Item "EVBACKEND_EPOLL (value 4, Linux)"
609Use the linux-specific \fIepoll\fR\|(7) interface (for both pre\- and post\-2.6.9 620Use the linux-specific \fIepoll\fR\|(7) interface (for both pre\- and post\-2.6.9
610kernels). 621kernels).
611.Sp 622.Sp
612For few fds, this backend is a bit little slower than poll and select, but 623For few fds, this backend is a bit little slower than poll and select, but
613it scales phenomenally better. While poll and select usually scale like 624it scales phenomenally better. While poll and select usually scale like
666.Sp 677.Sp
667This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as 678This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as
668\&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. 679\&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR.
669.ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 680.ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4
670.el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 681.el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4
671.IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" 682.IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)"
672Kqueue deserves special mention, as at the time of this writing, it 683Kqueue deserves special mention, as at the time of this writing, it
673was broken on all BSDs except NetBSD (usually it doesn't work reliably 684was broken on all BSDs except NetBSD (usually it doesn't work reliably
674with anything but sockets and pipes, except on Darwin, where of course 685with anything but sockets and pipes, except on Darwin, where of course
675it's completely useless). Unlike epoll, however, whose brokenness 686it's completely useless). Unlike epoll, however, whose brokenness
676is by design, these kqueue bugs can (and eventually will) be fixed 687is by design, these kqueue bugs can (and eventually will) be fixed
685.Sp 696.Sp
686It scales in the same way as the epoll backend, but the interface to the 697It scales in the same way as the epoll backend, but the interface to the
687kernel is more efficient (which says nothing about its actual speed, of 698kernel is more efficient (which says nothing about its actual speed, of
688course). While stopping, setting and starting an I/O watcher does never 699course). While stopping, setting and starting an I/O watcher does never
689cause an extra system call as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to 700cause an extra system call as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to
690two event changes per incident. Support for \f(CW\*(C`fork ()\*(C'\fR is very bad (but 701two event changes per incident. Support for \f(CW\*(C`fork ()\*(C'\fR is very bad (you
691sane, unlike epoll) and it drops fds silently in similarly hard-to-detect 702might have to leak fd's on fork, but it's more sane than epoll) and it
692cases 703drops fds silently in similarly hard-to-detect cases.
693.Sp 704.Sp
694This backend usually performs well under most conditions. 705This backend usually performs well under most conditions.
695.Sp 706.Sp
696While nominally embeddable in other event loops, this doesn't work 707While nominally embeddable in other event loops, this doesn't work
697everywhere, so you might need to test for this. And since it is broken 708everywhere, so you might need to test for this. And since it is broken
698almost everywhere, you should only use it when you have a lot of sockets 709almost everywhere, you should only use it when you have a lot of sockets
699(for which it usually works), by embedding it into another event loop 710(for which it usually works), by embedding it into another event loop
700(e.g. \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR (but \f(CW\*(C`poll\*(C'\fR is of course 711(e.g. \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR (but \f(CW\*(C`poll\*(C'\fR is of course
701also broken on \s-1OS\s0 X)) and, did I mention it, using it only for sockets. 712also broken on \s-1OS X\s0)) and, did I mention it, using it only for sockets.
702.Sp 713.Sp
703This backend maps \f(CW\*(C`EV_READ\*(C'\fR into an \f(CW\*(C`EVFILT_READ\*(C'\fR kevent with 714This backend maps \f(CW\*(C`EV_READ\*(C'\fR into an \f(CW\*(C`EVFILT_READ\*(C'\fR kevent with
704\&\f(CW\*(C`NOTE_EOF\*(C'\fR, and \f(CW\*(C`EV_WRITE\*(C'\fR into an \f(CW\*(C`EVFILT_WRITE\*(C'\fR kevent with 715\&\f(CW\*(C`NOTE_EOF\*(C'\fR, and \f(CW\*(C`EV_WRITE\*(C'\fR into an \f(CW\*(C`EVFILT_WRITE\*(C'\fR kevent with
705\&\f(CW\*(C`NOTE_EOF\*(C'\fR. 716\&\f(CW\*(C`NOTE_EOF\*(C'\fR.
706.ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 717.ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4
710implementation). According to reports, \f(CW\*(C`/dev/poll\*(C'\fR only supports sockets 721implementation). According to reports, \f(CW\*(C`/dev/poll\*(C'\fR only supports sockets
711and is not embeddable, which would limit the usefulness of this backend 722and is not embeddable, which would limit the usefulness of this backend
712immensely. 723immensely.
713.ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 724.ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4
714.el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 725.el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4
715.IX Item "EVBACKEND_PORT (value 32, Solaris 10)" 726.IX Item "EVBACKEND_PORT (value 32, Solaris 10)"
716This uses the Solaris 10 event port mechanism. As with everything on Solaris, 727This uses the Solaris 10 event port mechanism. As with everything on Solaris,
717it's really slow, but it still scales very well (O(active_fds)). 728it's really slow, but it still scales very well (O(active_fds)).
718.Sp 729.Sp
719While this backend scales well, it requires one system call per active 730While this backend scales well, it requires one system call per active
720file descriptor per loop iteration. For small and medium numbers of file 731file descriptor per loop iteration. For small and medium numbers of file
805reinitialise the kernel state for backends that have one. Despite the 816reinitialise the kernel state for backends that have one. Despite the
806name, you can call it anytime, but it makes most sense after forking, in 817name, you can call it anytime, but it makes most sense after forking, in
807the child process. You \fImust\fR call it (or use \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR) in the 818the child process. You \fImust\fR call it (or use \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR) in the
808child before resuming or calling \f(CW\*(C`ev_run\*(C'\fR. 819child before resuming or calling \f(CW\*(C`ev_run\*(C'\fR.
809.Sp 820.Sp
810Again, you \fIhave\fR to call it on \fIany\fR loop that you want to re-use after 821Again, you \fIhave\fR to call it on \fIany\fR loop that you want to re-use after
811a fork, \fIeven if you do not plan to use the loop in the parent\fR. This is 822a fork, \fIeven if you do not plan to use the loop in the parent\fR. This is
812because some kernel interfaces *cough* \fIkqueue\fR *cough* do funny things 823because some kernel interfaces *cough* \fIkqueue\fR *cough* do funny things
813during fork. 824during fork.
814.Sp 825.Sp
815On the other hand, you only need to call this function in the child 826On the other hand, you only need to call this function in the child
909given loop other than \f(CW\*(C`ev_resume\*(C'\fR, and you \fBmust not\fR call \f(CW\*(C`ev_resume\*(C'\fR 920given loop other than \f(CW\*(C`ev_resume\*(C'\fR, and you \fBmust not\fR call \f(CW\*(C`ev_resume\*(C'\fR
910without a previous call to \f(CW\*(C`ev_suspend\*(C'\fR. 921without a previous call to \f(CW\*(C`ev_suspend\*(C'\fR.
911.Sp 922.Sp
912Calling \f(CW\*(C`ev_suspend\*(C'\fR/\f(CW\*(C`ev_resume\*(C'\fR has the side effect of updating the 923Calling \f(CW\*(C`ev_suspend\*(C'\fR/\f(CW\*(C`ev_resume\*(C'\fR has the side effect of updating the
913event loop time (see \f(CW\*(C`ev_now_update\*(C'\fR). 924event loop time (see \f(CW\*(C`ev_now_update\*(C'\fR).
914.IP "ev_run (loop, int flags)" 4 925.IP "bool ev_run (loop, int flags)" 4
915.IX Item "ev_run (loop, int flags)" 926.IX Item "bool ev_run (loop, int flags)"
916Finally, this is it, the event handler. This function usually is called 927Finally, this is it, the event handler. This function usually is called
917after you have initialised all your watchers and you want to start 928after you have initialised all your watchers and you want to start
918handling events. It will ask the operating system for any new events, call 929handling events. It will ask the operating system for any new events, call
919the watcher callbacks, an then repeat the whole process indefinitely: This 930the watcher callbacks, and then repeat the whole process indefinitely: This
920is why event loops are called \fIloops\fR. 931is why event loops are called \fIloops\fR.
921.Sp 932.Sp
922If the flags argument is specified as \f(CW0\fR, it will keep handling events 933If the flags argument is specified as \f(CW0\fR, it will keep handling events
923until either no event watchers are active anymore or \f(CW\*(C`ev_break\*(C'\fR was 934until either no event watchers are active anymore or \f(CW\*(C`ev_break\*(C'\fR was
924called. 935called.
936.Sp
937The return value is false if there are no more active watchers (which
938usually means \*(L"all jobs done\*(R" or \*(L"deadlock\*(R"), and true in all other cases
939(which usually means " you should call \f(CW\*(C`ev_run\*(C'\fR again").
925.Sp 940.Sp
926Please note that an explicit \f(CW\*(C`ev_break\*(C'\fR is usually better than 941Please note that an explicit \f(CW\*(C`ev_break\*(C'\fR is usually better than
927relying on all watchers to be stopped when deciding when a program has 942relying on all watchers to be stopped when deciding when a program has
928finished (especially in interactive programs), but having a program 943finished (especially in interactive programs), but having a program
929that automatically loops as long as it has to and no longer by virtue 944that automatically loops as long as it has to and no longer by virtue
930of relying on its watchers stopping correctly, that is truly a thing of 945of relying on its watchers stopping correctly, that is truly a thing of
931beauty. 946beauty.
932.Sp 947.Sp
933This function is also \fImostly\fR exception-safe \- you can break out of 948This function is \fImostly\fR exception-safe \- you can break out of a
934a \f(CW\*(C`ev_run\*(C'\fR call by calling \f(CW\*(C`longjmp\*(C'\fR in a callback, throwing a \*(C+ 949\&\f(CW\*(C`ev_run\*(C'\fR call by calling \f(CW\*(C`longjmp\*(C'\fR in a callback, throwing a \*(C+
935exception and so on. This does not decrement the \f(CW\*(C`ev_depth\*(C'\fR value, nor 950exception and so on. This does not decrement the \f(CW\*(C`ev_depth\*(C'\fR value, nor
936will it clear any outstanding \f(CW\*(C`EVBREAK_ONE\*(C'\fR breaks. 951will it clear any outstanding \f(CW\*(C`EVBREAK_ONE\*(C'\fR breaks.
937.Sp 952.Sp
938A flags value of \f(CW\*(C`EVRUN_NOWAIT\*(C'\fR will look for new events, will handle 953A flags value of \f(CW\*(C`EVRUN_NOWAIT\*(C'\fR will look for new events, will handle
939those events and any already outstanding ones, but will not wait and 954those events and any already outstanding ones, but will not wait and
1136this callback instead. This is useful, for example, when you want to 1151this callback instead. This is useful, for example, when you want to
1137invoke the actual watchers inside another context (another thread etc.). 1152invoke the actual watchers inside another context (another thread etc.).
1138.Sp 1153.Sp
1139If you want to reset the callback, use \f(CW\*(C`ev_invoke_pending\*(C'\fR as new 1154If you want to reset the callback, use \f(CW\*(C`ev_invoke_pending\*(C'\fR as new
1140callback. 1155callback.
1141.IP "ev_set_loop_release_cb (loop, void (*release)(\s-1EV_P\s0), void (*acquire)(\s-1EV_P\s0))" 4 1156.IP "ev_set_loop_release_cb (loop, void (*release)(\s-1EV_P\s0) throw (), void (*acquire)(\s-1EV_P\s0) throw ())" 4
1142.IX Item "ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P))" 1157.IX Item "ev_set_loop_release_cb (loop, void (*release)(EV_P) throw (), void (*acquire)(EV_P) throw ())"
1143Sometimes you want to share the same loop between multiple threads. This 1158Sometimes you want to share the same loop between multiple threads. This
1144can be done relatively simply by putting mutex_lock/unlock calls around 1159can be done relatively simply by putting mutex_lock/unlock calls around
1145each call to a libev function. 1160each call to a libev function.
1146.Sp 1161.Sp
1147However, \f(CW\*(C`ev_run\*(C'\fR can run an indefinite time, so it is not feasible 1162However, \f(CW\*(C`ev_run\*(C'\fR can run an indefinite time, so it is not feasible
1295.PD 0 1310.PD 0
1296.ie n .IP """EV_CHECK""" 4 1311.ie n .IP """EV_CHECK""" 4
1297.el .IP "\f(CWEV_CHECK\fR" 4 1312.el .IP "\f(CWEV_CHECK\fR" 4
1298.IX Item "EV_CHECK" 1313.IX Item "EV_CHECK"
1299.PD 1314.PD
1300All \f(CW\*(C`ev_prepare\*(C'\fR watchers are invoked just \fIbefore\fR \f(CW\*(C`ev_run\*(C'\fR starts 1315All \f(CW\*(C`ev_prepare\*(C'\fR watchers are invoked just \fIbefore\fR \f(CW\*(C`ev_run\*(C'\fR starts to
1301to gather new events, and all \f(CW\*(C`ev_check\*(C'\fR watchers are invoked just after 1316gather new events, and all \f(CW\*(C`ev_check\*(C'\fR watchers are queued (not invoked)
1302\&\f(CW\*(C`ev_run\*(C'\fR has gathered them, but before it invokes any callbacks for any 1317just after \f(CW\*(C`ev_run\*(C'\fR has gathered them, but before it queues any callbacks
1318for any received events. That means \f(CW\*(C`ev_prepare\*(C'\fR watchers are the last
1319watchers invoked before the event loop sleeps or polls for new events, and
1320\&\f(CW\*(C`ev_check\*(C'\fR watchers will be invoked before any other watchers of the same
1321or lower priority within an event loop iteration.
1322.Sp
1303received events. Callbacks of both watcher types can start and stop as 1323Callbacks of both watcher types can start and stop as many watchers as
1304many watchers as they want, and all of them will be taken into account 1324they want, and all of them will be taken into account (for example, a
1305(for example, a \f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep 1325\&\f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep \f(CW\*(C`ev_run\*(C'\fR from
1306\&\f(CW\*(C`ev_run\*(C'\fR from blocking). 1326blocking).
1307.ie n .IP """EV_EMBED""" 4 1327.ie n .IP """EV_EMBED""" 4
1308.el .IP "\f(CWEV_EMBED\fR" 4 1328.el .IP "\f(CWEV_EMBED\fR" 4
1309.IX Item "EV_EMBED" 1329.IX Item "EV_EMBED"
1310The embedded event loop specified in the \f(CW\*(C`ev_embed\*(C'\fR watcher needs attention. 1330The embedded event loop specified in the \f(CW\*(C`ev_embed\*(C'\fR watcher needs attention.
1311.ie n .IP """EV_FORK""" 4 1331.ie n .IP """EV_FORK""" 4
1343example it might indicate that a fd is readable or writable, and if your 1363example it might indicate that a fd is readable or writable, and if your
1344callbacks is well-written it can just attempt the operation and cope with 1364callbacks is well-written it can just attempt the operation and cope with
1345the error from \fIread()\fR or \fIwrite()\fR. This will not work in multi-threaded 1365the error from \fIread()\fR or \fIwrite()\fR. This will not work in multi-threaded
1346programs, though, as the fd could already be closed and reused for another 1366programs, though, as the fd could already be closed and reused for another
1347thing, so beware. 1367thing, so beware.
1348.SS "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" 1368.SS "\s-1GENERIC WATCHER FUNCTIONS\s0"
1349.IX Subsection "GENERIC WATCHER FUNCTIONS" 1369.IX Subsection "GENERIC WATCHER FUNCTIONS"
1350.ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 1370.ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4
1351.el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 1371.el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4
1352.IX Item "ev_init (ev_TYPE *watcher, callback)" 1372.IX Item "ev_init (ev_TYPE *watcher, callback)"
1353This macro initialises the generic portion of a watcher. The contents 1373This macro initialises the generic portion of a watcher. The contents
1432make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR 1452make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR
1433it). 1453it).
1434.IP "callback ev_cb (ev_TYPE *watcher)" 4 1454.IP "callback ev_cb (ev_TYPE *watcher)" 4
1435.IX Item "callback ev_cb (ev_TYPE *watcher)" 1455.IX Item "callback ev_cb (ev_TYPE *watcher)"
1436Returns the callback currently set on the watcher. 1456Returns the callback currently set on the watcher.
1437.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 1457.IP "ev_set_cb (ev_TYPE *watcher, callback)" 4
1438.IX Item "ev_cb_set (ev_TYPE *watcher, callback)" 1458.IX Item "ev_set_cb (ev_TYPE *watcher, callback)"
1439Change the callback. You can change the callback at virtually any time 1459Change the callback. You can change the callback at virtually any time
1440(modulo threads). 1460(modulo threads).
1441.IP "ev_set_priority (ev_TYPE *watcher, int priority)" 4 1461.IP "ev_set_priority (ev_TYPE *watcher, int priority)" 4
1442.IX Item "ev_set_priority (ev_TYPE *watcher, int priority)" 1462.IX Item "ev_set_priority (ev_TYPE *watcher, int priority)"
1443.PD 0 1463.PD 0
1461or might not have been clamped to the valid range. 1481or might not have been clamped to the valid range.
1462.Sp 1482.Sp
1463The default priority used by watchers when no priority has been set is 1483The default priority used by watchers when no priority has been set is
1464always \f(CW0\fR, which is supposed to not be too high and not be too low :). 1484always \f(CW0\fR, which is supposed to not be too high and not be too low :).
1465.Sp 1485.Sp
1466See \*(L"\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0\*(R", below, for a more thorough treatment of 1486See \*(L"\s-1WATCHER PRIORITY MODELS\*(R"\s0, below, for a more thorough treatment of
1467priorities. 1487priorities.
1468.IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 1488.IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4
1469.IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" 1489.IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)"
1470Invoke the \f(CW\*(C`watcher\*(C'\fR with the given \f(CW\*(C`loop\*(C'\fR and \f(CW\*(C`revents\*(C'\fR. Neither 1490Invoke the \f(CW\*(C`watcher\*(C'\fR with the given \f(CW\*(C`loop\*(C'\fR and \f(CW\*(C`revents\*(C'\fR. Neither
1471\&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback 1491\&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback
1491not started in the first place. 1511not started in the first place.
1492.Sp 1512.Sp
1493See also \f(CW\*(C`ev_feed_fd_event\*(C'\fR and \f(CW\*(C`ev_feed_signal_event\*(C'\fR for related 1513See also \f(CW\*(C`ev_feed_fd_event\*(C'\fR and \f(CW\*(C`ev_feed_signal_event\*(C'\fR for related
1494functions that do not need a watcher. 1514functions that do not need a watcher.
1495.PP 1515.PP
1496See also the \*(L"\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0\*(R" and \*(L"\s-1BUILDING\s0 \s-1YOUR\s0 1516See also the \*(L"\s-1ASSOCIATING CUSTOM DATA WITH A WATCHER\*(R"\s0 and \*(L"\s-1BUILDING YOUR
1497\&\s-1OWN\s0 \s-1COMPOSITE\s0 \s-1WATCHERS\s0\*(R" idioms. 1517OWN COMPOSITE WATCHERS\*(R"\s0 idioms.
1498.SS "\s-1WATCHER\s0 \s-1STATES\s0" 1518.SS "\s-1WATCHER STATES\s0"
1499.IX Subsection "WATCHER STATES" 1519.IX Subsection "WATCHER STATES"
1500There are various watcher states mentioned throughout this manual \- 1520There are various watcher states mentioned throughout this manual \-
1501active, pending and so on. In this section these states and the rules to 1521active, pending and so on. In this section these states and the rules to
1502transition between them will be described in more detail \- and while these 1522transition between them will be described in more detail \- and while these
1503rules might look complicated, they usually do \*(L"the right thing\*(R". 1523rules might look complicated, they usually do \*(L"the right thing\*(R".
1504.IP "initialiased" 4 1524.IP "initialised" 4
1505.IX Item "initialiased" 1525.IX Item "initialised"
1506Before a watcher can be registered with the event loop it has to be 1526Before a watcher can be registered with the event loop it has to be
1507initialised. This can be done with a call to \f(CW\*(C`ev_TYPE_init\*(C'\fR, or calls to 1527initialised. This can be done with a call to \f(CW\*(C`ev_TYPE_init\*(C'\fR, or calls to
1508\&\f(CW\*(C`ev_init\*(C'\fR followed by the watcher-specific \f(CW\*(C`ev_TYPE_set\*(C'\fR function. 1528\&\f(CW\*(C`ev_init\*(C'\fR followed by the watcher-specific \f(CW\*(C`ev_TYPE_set\*(C'\fR function.
1509.Sp 1529.Sp
1510In this state it is simply some block of memory that is suitable for 1530In this state it is simply some block of memory that is suitable for
1546.Sp 1566.Sp
1547While stopped (and not pending) the watcher is essentially in the 1567While stopped (and not pending) the watcher is essentially in the
1548initialised state, that is, it can be reused, moved, modified in any way 1568initialised state, that is, it can be reused, moved, modified in any way
1549you wish (but when you trash the memory block, you need to \f(CW\*(C`ev_TYPE_init\*(C'\fR 1569you wish (but when you trash the memory block, you need to \f(CW\*(C`ev_TYPE_init\*(C'\fR
1550it again). 1570it again).
1551.SS "\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0" 1571.SS "\s-1WATCHER PRIORITY MODELS\s0"
1552.IX Subsection "WATCHER PRIORITY MODELS" 1572.IX Subsection "WATCHER PRIORITY MODELS"
1553Many event loops support \fIwatcher priorities\fR, which are usually small 1573Many event loops support \fIwatcher priorities\fR, which are usually small
1554integers that influence the ordering of event callback invocation 1574integers that influence the ordering of event callback invocation
1555between watchers in some way, all else being equal. 1575between watchers in some way, all else being equal.
1556.PP 1576.PP
1754wish to read \- you would first have to request some data. 1774wish to read \- you would first have to request some data.
1755.PP 1775.PP
1756Since files are typically not-so-well supported by advanced notification 1776Since files are typically not-so-well supported by advanced notification
1757mechanism, libev tries hard to emulate \s-1POSIX\s0 behaviour with respect 1777mechanism, libev tries hard to emulate \s-1POSIX\s0 behaviour with respect
1758to files, even though you should not use it. The reason for this is 1778to files, even though you should not use it. The reason for this is
1759convenience: sometimes you want to watch \s-1STDIN\s0 or \s-1STDOUT\s0, which is 1779convenience: sometimes you want to watch \s-1STDIN\s0 or \s-1STDOUT,\s0 which is
1760usually a tty, often a pipe, but also sometimes files or special devices 1780usually a tty, often a pipe, but also sometimes files or special devices
1761(for example, \f(CW\*(C`epoll\*(C'\fR on Linux works with \fI/dev/random\fR but not with 1781(for example, \f(CW\*(C`epoll\*(C'\fR on Linux works with \fI/dev/random\fR but not with
1762\&\fI/dev/urandom\fR), and even though the file might better be served with 1782\&\fI/dev/urandom\fR), and even though the file might better be served with
1763asynchronous I/O instead of with non-blocking I/O, it is still useful when 1783asynchronous I/O instead of with non-blocking I/O, it is still useful when
1764it \*(L"just works\*(R" instead of freezing. 1784it \*(L"just works\*(R" instead of freezing.
1765.PP 1785.PP
1766So avoid file descriptors pointing to files when you know it (e.g. use 1786So avoid file descriptors pointing to files when you know it (e.g. use
1767libeio), but use them when it is convenient, e.g. for \s-1STDIN/STDOUT\s0, or 1787libeio), but use them when it is convenient, e.g. for \s-1STDIN/STDOUT,\s0 or
1768when you rarely read from a file instead of from a socket, and want to 1788when you rarely read from a file instead of from a socket, and want to
1769reuse the same code path. 1789reuse the same code path.
1770.PP 1790.PP
1771\fIThe special problem of fork\fR 1791\fIThe special problem of fork\fR
1772.IX Subsection "The special problem of fork" 1792.IX Subsection "The special problem of fork"
1782\fIThe special problem of \s-1SIGPIPE\s0\fR 1802\fIThe special problem of \s-1SIGPIPE\s0\fR
1783.IX Subsection "The special problem of SIGPIPE" 1803.IX Subsection "The special problem of SIGPIPE"
1784.PP 1804.PP
1785While not really specific to libev, it is easy to forget about \f(CW\*(C`SIGPIPE\*(C'\fR: 1805While not really specific to libev, it is easy to forget about \f(CW\*(C`SIGPIPE\*(C'\fR:
1786when writing to a pipe whose other end has been closed, your program gets 1806when writing to a pipe whose other end has been closed, your program gets
1787sent a \s-1SIGPIPE\s0, which, by default, aborts your program. For most programs 1807sent a \s-1SIGPIPE,\s0 which, by default, aborts your program. For most programs
1788this is sensible behaviour, for daemons, this is usually undesirable. 1808this is sensible behaviour, for daemons, this is usually undesirable.
1789.PP 1809.PP
1790So when you encounter spurious, unexplained daemon exits, make sure you 1810So when you encounter spurious, unexplained daemon exits, make sure you
1791ignore \s-1SIGPIPE\s0 (and maybe make sure you log the exit status of your daemon 1811ignore \s-1SIGPIPE \s0(and maybe make sure you log the exit status of your daemon
1792somewhere, as that would have given you a big clue). 1812somewhere, as that would have given you a big clue).
1793.PP 1813.PP
1794\fIThe special problem of \fIaccept()\fIing when you can't\fR 1814\fIThe special problem of \fIaccept()\fIing when you can't\fR
1795.IX Subsection "The special problem of accept()ing when you can't" 1815.IX Subsection "The special problem of accept()ing when you can't"
1796.PP 1816.PP
1797Many implementations of the \s-1POSIX\s0 \f(CW\*(C`accept\*(C'\fR function (for example, 1817Many implementations of the \s-1POSIX \s0\f(CW\*(C`accept\*(C'\fR function (for example,
1798found in post\-2004 Linux) have the peculiar behaviour of not removing a 1818found in post\-2004 Linux) have the peculiar behaviour of not removing a
1799connection from the pending queue in all error cases. 1819connection from the pending queue in all error cases.
1800.PP 1820.PP
1801For example, larger servers often run out of file descriptors (because 1821For example, larger servers often run out of file descriptors (because
1802of resource limits), causing \f(CW\*(C`accept\*(C'\fR to fail with \f(CW\*(C`ENFILE\*(C'\fR but not 1822of resource limits), causing \f(CW\*(C`accept\*(C'\fR to fail with \f(CW\*(C`ENFILE\*(C'\fR but not
1990\& callback (EV_P_ ev_timer *w, int revents) 2010\& callback (EV_P_ ev_timer *w, int revents)
1991\& { 2011\& {
1992\& // calculate when the timeout would happen 2012\& // calculate when the timeout would happen
1993\& ev_tstamp after = last_activity \- ev_now (EV_A) + timeout; 2013\& ev_tstamp after = last_activity \- ev_now (EV_A) + timeout;
1994\& 2014\&
1995\& // if negative, it means we the timeout already occured 2015\& // if negative, it means we the timeout already occurred
1996\& if (after < 0.) 2016\& if (after < 0.)
1997\& { 2017\& {
1998\& // timeout occurred, take action 2018\& // timeout occurred, take action
1999\& } 2019\& }
2000\& else 2020\& else
2019.Sp 2039.Sp
2020Otherwise, we now the earliest time at which the timeout would trigger, 2040Otherwise, we now the earliest time at which the timeout would trigger,
2021and simply start the timer with this timeout value. 2041and simply start the timer with this timeout value.
2022.Sp 2042.Sp
2023In other words, each time the callback is invoked it will check whether 2043In other words, each time the callback is invoked it will check whether
2024the timeout cocured. If not, it will simply reschedule itself to check 2044the timeout occurred. If not, it will simply reschedule itself to check
2025again at the earliest time it could time out. Rinse. Repeat. 2045again at the earliest time it could time out. Rinse. Repeat.
2026.Sp 2046.Sp
2027This scheme causes more callback invocations (about one every 60 seconds 2047This scheme causes more callback invocations (about one every 60 seconds
2028minus half the average time between activity), but virtually no calls to 2048minus half the average time between activity), but virtually no calls to
2029libev to change the timeout. 2049libev to change the timeout.
2047\& last_activity = ev_now (EV_A); 2067\& last_activity = ev_now (EV_A);
2048.Ve 2068.Ve
2049.Sp 2069.Sp
2050When your timeout value changes, then the timeout can be changed by simply 2070When your timeout value changes, then the timeout can be changed by simply
2051providing a new value, stopping the timer and calling the callback, which 2071providing a new value, stopping the timer and calling the callback, which
2052will agaion do the right thing (for example, time out immediately :). 2072will again do the right thing (for example, time out immediately :).
2053.Sp 2073.Sp
2054.Vb 3 2074.Vb 3
2055\& timeout = new_value; 2075\& timeout = new_value;
2056\& ev_timer_stop (EV_A_ &timer); 2076\& ev_timer_stop (EV_A_ &timer);
2057\& callback (EV_A_ &timer, 0); 2077\& callback (EV_A_ &timer, 0);
2407In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`offset\*(C'\fR are both being 2427In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`offset\*(C'\fR are both being
2408ignored. Instead, each time the periodic watcher gets scheduled, the 2428ignored. Instead, each time the periodic watcher gets scheduled, the
2409reschedule callback will be called with the watcher as first, and the 2429reschedule callback will be called with the watcher as first, and the
2410current time as second argument. 2430current time as second argument.
2411.Sp 2431.Sp
2412\&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, ever, 2432\&\s-1NOTE: \s0\fIThis callback \s-1MUST NOT\s0 stop or destroy any periodic watcher, ever,
2413or make \s-1ANY\s0 other event loop modifications whatsoever, unless explicitly 2433or make \s-1ANY\s0 other event loop modifications whatsoever, unless explicitly
2414allowed by documentation here\fR. 2434allowed by documentation here\fR.
2415.Sp 2435.Sp
2416If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop 2436If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop
2417it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the 2437it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the
2431It must return the next time to trigger, based on the passed time value 2451It must return the next time to trigger, based on the passed time value
2432(that is, the lowest time value larger than to the second argument). It 2452(that is, the lowest time value larger than to the second argument). It
2433will usually be called just before the callback will be triggered, but 2453will usually be called just before the callback will be triggered, but
2434might be called at other times, too. 2454might be called at other times, too.
2435.Sp 2455.Sp
2436\&\s-1NOTE:\s0 \fIThis callback must always return a time that is higher than or 2456\&\s-1NOTE: \s0\fIThis callback must always return a time that is higher than or
2437equal to the passed \f(CI\*(C`now\*(C'\fI value\fR. 2457equal to the passed \f(CI\*(C`now\*(C'\fI value\fR.
2438.Sp 2458.Sp
2439This can be used to create very complex timers, such as a timer that 2459This can be used to create very complex timers, such as a timer that
2440triggers on \*(L"next midnight, local time\*(R". To do this, you would calculate the 2460triggers on \*(L"next midnight, local time\*(R". To do this, you would calculate the
2441next midnight after \f(CW\*(C`now\*(C'\fR and return the timestamp value for this. How 2461next midnight after \f(CW\*(C`now\*(C'\fR and return the timestamp value for this. How
2533only within the same loop, i.e. you can watch for \f(CW\*(C`SIGINT\*(C'\fR in your 2553only within the same loop, i.e. you can watch for \f(CW\*(C`SIGINT\*(C'\fR in your
2534default loop and for \f(CW\*(C`SIGIO\*(C'\fR in another loop, but you cannot watch for 2554default loop and for \f(CW\*(C`SIGIO\*(C'\fR in another loop, but you cannot watch for
2535\&\f(CW\*(C`SIGINT\*(C'\fR in both the default loop and another loop at the same time. At 2555\&\f(CW\*(C`SIGINT\*(C'\fR in both the default loop and another loop at the same time. At
2536the moment, \f(CW\*(C`SIGCHLD\*(C'\fR is permanently tied to the default loop. 2556the moment, \f(CW\*(C`SIGCHLD\*(C'\fR is permanently tied to the default loop.
2537.PP 2557.PP
2538When the first watcher gets started will libev actually register something 2558Only after the first watcher for a signal is started will libev actually
2539with the kernel (thus it coexists with your own signal handlers as long as 2559register something with the kernel. It thus coexists with your own signal
2540you don't register any with libev for the same signal). 2560handlers as long as you don't register any with libev for the same signal.
2541.PP 2561.PP
2542If possible and supported, libev will install its handlers with 2562If possible and supported, libev will install its handlers with
2543\&\f(CW\*(C`SA_RESTART\*(C'\fR (or equivalent) behaviour enabled, so system calls should 2563\&\f(CW\*(C`SA_RESTART\*(C'\fR (or equivalent) behaviour enabled, so system calls should
2544not be unduly interrupted. If you have a problem with system calls getting 2564not be unduly interrupted. If you have a problem with system calls getting
2545interrupted by signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher 2565interrupted by signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher
2566The simplest way to ensure that the signal mask is reset in the child is 2586The simplest way to ensure that the signal mask is reset in the child is
2567to install a fork handler with \f(CW\*(C`pthread_atfork\*(C'\fR that resets it. That will 2587to install a fork handler with \f(CW\*(C`pthread_atfork\*(C'\fR that resets it. That will
2568catch fork calls done by libraries (such as the libc) as well. 2588catch fork calls done by libraries (such as the libc) as well.
2569.PP 2589.PP
2570In current versions of libev, the signal will not be blocked indefinitely 2590In current versions of libev, the signal will not be blocked indefinitely
2571unless you use the \f(CW\*(C`signalfd\*(C'\fR \s-1API\s0 (\f(CW\*(C`EV_SIGNALFD\*(C'\fR). While this reduces 2591unless you use the \f(CW\*(C`signalfd\*(C'\fR \s-1API \s0(\f(CW\*(C`EV_SIGNALFD\*(C'\fR). While this reduces
2572the window of opportunity for problems, it will not go away, as libev 2592the window of opportunity for problems, it will not go away, as libev
2573\&\fIhas\fR to modify the signal mask, at least temporarily. 2593\&\fIhas\fR to modify the signal mask, at least temporarily.
2574.PP 2594.PP
2575So I can't stress this enough: \fIIf you do not reset your signal mask when 2595So I can't stress this enough: \fIIf you do not reset your signal mask when
2576you expect it to be empty, you have a race condition in your code\fR. This 2596you expect it to be empty, you have a race condition in your code\fR. This
2606The signal the watcher watches out for. 2626The signal the watcher watches out for.
2607.PP 2627.PP
2608\fIExamples\fR 2628\fIExamples\fR
2609.IX Subsection "Examples" 2629.IX Subsection "Examples"
2610.PP 2630.PP
2611Example: Try to exit cleanly on \s-1SIGINT\s0. 2631Example: Try to exit cleanly on \s-1SIGINT.\s0
2612.PP 2632.PP
2613.Vb 5 2633.Vb 5
2614\& static void 2634\& static void
2615\& sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) 2635\& sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)
2616\& { 2636\& {
2731.ie n .SS """ev_stat"" \- did the file attributes just change?" 2751.ie n .SS """ev_stat"" \- did the file attributes just change?"
2732.el .SS "\f(CWev_stat\fP \- did the file attributes just change?" 2752.el .SS "\f(CWev_stat\fP \- did the file attributes just change?"
2733.IX Subsection "ev_stat - did the file attributes just change?" 2753.IX Subsection "ev_stat - did the file attributes just change?"
2734This watches a file system path for attribute changes. That is, it calls 2754This watches a file system path for attribute changes. That is, it calls
2735\&\f(CW\*(C`stat\*(C'\fR on that path in regular intervals (or when the \s-1OS\s0 says it changed) 2755\&\f(CW\*(C`stat\*(C'\fR on that path in regular intervals (or when the \s-1OS\s0 says it changed)
2736and sees if it changed compared to the last time, invoking the callback if 2756and sees if it changed compared to the last time, invoking the callback
2737it did. 2757if it did. Starting the watcher \f(CW\*(C`stat\*(C'\fR's the file, so only changes that
2758happen after the watcher has been started will be reported.
2738.PP 2759.PP
2739The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does 2760The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does
2740not exist\*(R" is a status change like any other. The condition \*(L"path does not 2761not exist\*(R" is a status change like any other. The condition \*(L"path does not
2741exist\*(R" (or more correctly \*(L"path cannot be stat'ed\*(R") is signified by the 2762exist\*(R" (or more correctly \*(L"path cannot be stat'ed\*(R") is signified by the
2742\&\f(CW\*(C`st_nlink\*(C'\fR field being zero (which is otherwise always forced to be at 2763\&\f(CW\*(C`st_nlink\*(C'\fR field being zero (which is otherwise always forced to be at
2772compilation environment, which means that on systems with large file 2793compilation environment, which means that on systems with large file
2773support disabled by default, you get the 32 bit version of the stat 2794support disabled by default, you get the 32 bit version of the stat
2774structure. When using the library from programs that change the \s-1ABI\s0 to 2795structure. When using the library from programs that change the \s-1ABI\s0 to
2775use 64 bit file offsets the programs will fail. In that case you have to 2796use 64 bit file offsets the programs will fail. In that case you have to
2776compile libev with the same flags to get binary compatibility. This is 2797compile libev with the same flags to get binary compatibility. This is
2777obviously the case with any flags that change the \s-1ABI\s0, but the problem is 2798obviously the case with any flags that change the \s-1ABI,\s0 but the problem is
2778most noticeably displayed with ev_stat and large file support. 2799most noticeably displayed with ev_stat and large file support.
2779.PP 2800.PP
2780The solution for this is to lobby your distribution maker to make large 2801The solution for this is to lobby your distribution maker to make large
2781file interfaces available by default (as e.g. FreeBSD does) and not 2802file interfaces available by default (as e.g. FreeBSD does) and not
2782optional. Libev cannot simply switch on large file support because it has 2803optional. Libev cannot simply switch on large file support because it has
2973Apart from keeping your process non-blocking (which is a useful 2994Apart from keeping your process non-blocking (which is a useful
2974effect on its own sometimes), idle watchers are a good place to do 2995effect on its own sometimes), idle watchers are a good place to do
2975\&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the 2996\&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the
2976event loop has handled all outstanding events. 2997event loop has handled all outstanding events.
2977.PP 2998.PP
2999\fIAbusing an \f(CI\*(C`ev_idle\*(C'\fI watcher for its side-effect\fR
3000.IX Subsection "Abusing an ev_idle watcher for its side-effect"
3001.PP
3002As long as there is at least one active idle watcher, libev will never
3003sleep unnecessarily. Or in other words, it will loop as fast as possible.
3004For this to work, the idle watcher doesn't need to be invoked at all \- the
3005lowest priority will do.
3006.PP
3007This mode of operation can be useful together with an \f(CW\*(C`ev_check\*(C'\fR watcher,
3008to do something on each event loop iteration \- for example to balance load
3009between different connections.
3010.PP
3011See \*(L"Abusing an ev_check watcher for its side-effect\*(R" for a longer
3012example.
3013.PP
2978\fIWatcher-Specific Functions and Data Members\fR 3014\fIWatcher-Specific Functions and Data Members\fR
2979.IX Subsection "Watcher-Specific Functions and Data Members" 3015.IX Subsection "Watcher-Specific Functions and Data Members"
2980.IP "ev_idle_init (ev_idle *, callback)" 4 3016.IP "ev_idle_init (ev_idle *, callback)" 4
2981.IX Item "ev_idle_init (ev_idle *, callback)" 3017.IX Item "ev_idle_init (ev_idle *, callback)"
2982Initialises and configures the idle watcher \- it has no parameters of any 3018Initialises and configures the idle watcher \- it has no parameters of any
2987.IX Subsection "Examples" 3023.IX Subsection "Examples"
2988.PP 3024.PP
2989Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the 3025Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the
2990callback, free it. Also, use no error checking, as usual. 3026callback, free it. Also, use no error checking, as usual.
2991.PP 3027.PP
2992.Vb 7 3028.Vb 5
2993\& static void 3029\& static void
2994\& idle_cb (struct ev_loop *loop, ev_idle *w, int revents) 3030\& idle_cb (struct ev_loop *loop, ev_idle *w, int revents)
2995\& { 3031\& {
3032\& // stop the watcher
3033\& ev_idle_stop (loop, w);
3034\&
3035\& // now we can free it
2996\& free (w); 3036\& free (w);
3037\&
2997\& // now do something you wanted to do when the program has 3038\& // now do something you wanted to do when the program has
2998\& // no longer anything immediate to do. 3039\& // no longer anything immediate to do.
2999\& } 3040\& }
3000\& 3041\&
3001\& ev_idle *idle_watcher = malloc (sizeof (ev_idle)); 3042\& ev_idle *idle_watcher = malloc (sizeof (ev_idle));
3003\& ev_idle_start (loop, idle_watcher); 3044\& ev_idle_start (loop, idle_watcher);
3004.Ve 3045.Ve
3005.ie n .SS """ev_prepare"" and ""ev_check"" \- customise your event loop!" 3046.ie n .SS """ev_prepare"" and ""ev_check"" \- customise your event loop!"
3006.el .SS "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" 3047.el .SS "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!"
3007.IX Subsection "ev_prepare and ev_check - customise your event loop!" 3048.IX Subsection "ev_prepare and ev_check - customise your event loop!"
3008Prepare and check watchers are usually (but not always) used in pairs: 3049Prepare and check watchers are often (but not always) used in pairs:
3009prepare watchers get invoked before the process blocks and check watchers 3050prepare watchers get invoked before the process blocks and check watchers
3010afterwards. 3051afterwards.
3011.PP 3052.PP
3012You \fImust not\fR call \f(CW\*(C`ev_run\*(C'\fR or similar functions that enter 3053You \fImust not\fR call \f(CW\*(C`ev_run\*(C'\fR or similar functions that enter
3013the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR 3054the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR
3041with priority higher than or equal to the event loop and one coroutine 3082with priority higher than or equal to the event loop and one coroutine
3042of lower priority, but only once, using idle watchers to keep the event 3083of lower priority, but only once, using idle watchers to keep the event
3043loop from blocking if lower-priority coroutines are active, thus mapping 3084loop from blocking if lower-priority coroutines are active, thus mapping
3044low-priority coroutines to idle/background tasks). 3085low-priority coroutines to idle/background tasks).
3045.PP 3086.PP
3046It is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR) 3087When used for this purpose, it is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers
3047priority, to ensure that they are being run before any other watchers 3088highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR) priority, to ensure that they are being run before
3048after the poll (this doesn't matter for \f(CW\*(C`ev_prepare\*(C'\fR watchers). 3089any other watchers after the poll (this doesn't matter for \f(CW\*(C`ev_prepare\*(C'\fR
3090watchers).
3049.PP 3091.PP
3050Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers, too) should not 3092Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers, too) should not
3051activate (\*(L"feed\*(R") events into libev. While libev fully supports this, they 3093activate (\*(L"feed\*(R") events into libev. While libev fully supports this, they
3052might get executed before other \f(CW\*(C`ev_check\*(C'\fR watchers did their job. As 3094might get executed before other \f(CW\*(C`ev_check\*(C'\fR watchers did their job. As
3053\&\f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other (non-libev) event 3095\&\f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other (non-libev) event
3054loops those other event loops might be in an unusable state until their 3096loops those other event loops might be in an unusable state until their
3055\&\f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to coexist peacefully with 3097\&\f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to coexist peacefully with
3056others). 3098others).
3099.PP
3100\fIAbusing an \f(CI\*(C`ev_check\*(C'\fI watcher for its side-effect\fR
3101.IX Subsection "Abusing an ev_check watcher for its side-effect"
3102.PP
3103\&\f(CW\*(C`ev_check\*(C'\fR (and less often also \f(CW\*(C`ev_prepare\*(C'\fR) watchers can also be
3104useful because they are called once per event loop iteration. For
3105example, if you want to handle a large number of connections fairly, you
3106normally only do a bit of work for each active connection, and if there
3107is more work to do, you wait for the next event loop iteration, so other
3108connections have a chance of making progress.
3109.PP
3110Using an \f(CW\*(C`ev_check\*(C'\fR watcher is almost enough: it will be called on the
3111next event loop iteration. However, that isn't as soon as possible \-
3112without external events, your \f(CW\*(C`ev_check\*(C'\fR watcher will not be invoked.
3113.PP
3114This is where \f(CW\*(C`ev_idle\*(C'\fR watchers come in handy \- all you need is a
3115single global idle watcher that is active as long as you have one active
3116\&\f(CW\*(C`ev_check\*(C'\fR watcher. The \f(CW\*(C`ev_idle\*(C'\fR watcher makes sure the event loop
3117will not sleep, and the \f(CW\*(C`ev_check\*(C'\fR watcher makes sure a callback gets
3118invoked. Neither watcher alone can do that.
3057.PP 3119.PP
3058\fIWatcher-Specific Functions and Data Members\fR 3120\fIWatcher-Specific Functions and Data Members\fR
3059.IX Subsection "Watcher-Specific Functions and Data Members" 3121.IX Subsection "Watcher-Specific Functions and Data Members"
3060.IP "ev_prepare_init (ev_prepare *, callback)" 4 3122.IP "ev_prepare_init (ev_prepare *, callback)" 4
3061.IX Item "ev_prepare_init (ev_prepare *, callback)" 3123.IX Item "ev_prepare_init (ev_prepare *, callback)"
3172.Ve 3234.Ve
3173.PP 3235.PP
3174Method 4: Do not use a prepare or check watcher because the module you 3236Method 4: Do not use a prepare or check watcher because the module you
3175want to embed is not flexible enough to support it. Instead, you can 3237want to embed is not flexible enough to support it. Instead, you can
3176override their poll function. The drawback with this solution is that the 3238override their poll function. The drawback with this solution is that the
3177main loop is now no longer controllable by \s-1EV\s0. The \f(CW\*(C`Glib::EV\*(C'\fR module uses 3239main loop is now no longer controllable by \s-1EV.\s0 The \f(CW\*(C`Glib::EV\*(C'\fR module uses
3178this approach, effectively embedding \s-1EV\s0 as a client into the horrible 3240this approach, effectively embedding \s-1EV\s0 as a client into the horrible
3179libglib event loop. 3241libglib event loop.
3180.PP 3242.PP
3181.Vb 4 3243.Vb 4
3182\& static gint 3244\& static gint
3266\fIWatcher-Specific Functions and Data Members\fR 3328\fIWatcher-Specific Functions and Data Members\fR
3267.IX Subsection "Watcher-Specific Functions and Data Members" 3329.IX Subsection "Watcher-Specific Functions and Data Members"
3268.IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 3330.IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4
3269.IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 3331.IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)"
3270.PD 0 3332.PD 0
3271.IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 3333.IP "ev_embed_set (ev_embed *, struct ev_loop *embedded_loop)" 4
3272.IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 3334.IX Item "ev_embed_set (ev_embed *, struct ev_loop *embedded_loop)"
3273.PD 3335.PD
3274Configures the watcher to embed the given loop, which must be 3336Configures the watcher to embed the given loop, which must be
3275embeddable. If the callback is \f(CW0\fR, then \f(CW\*(C`ev_embed_sweep\*(C'\fR will be 3337embeddable. If the callback is \f(CW0\fR, then \f(CW\*(C`ev_embed_sweep\*(C'\fR will be
3276invoked automatically, otherwise it is the responsibility of the callback 3338invoked automatically, otherwise it is the responsibility of the callback
3277to invoke it (it will continue to be called until the sweep has been done, 3339to invoke it (it will continue to be called until the sweep has been done,
3340.ie n .SS """ev_fork"" \- the audacity to resume the event loop after a fork" 3402.ie n .SS """ev_fork"" \- the audacity to resume the event loop after a fork"
3341.el .SS "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" 3403.el .SS "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork"
3342.IX Subsection "ev_fork - the audacity to resume the event loop after a fork" 3404.IX Subsection "ev_fork - the audacity to resume the event loop after a fork"
3343Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because 3405Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because
3344whoever is a good citizen cared to tell libev about it by calling 3406whoever is a good citizen cared to tell libev about it by calling
3345\&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the 3407\&\f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the event loop blocks next
3346event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, 3408and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, and only in the child
3347and only in the child after the fork. If whoever good citizen calling 3409after the fork. If whoever good citizen calling \f(CW\*(C`ev_default_fork\*(C'\fR cheats
3348\&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork 3410and calls it in the wrong process, the fork handlers will be invoked, too,
3349handlers will be invoked, too, of course. 3411of course.
3350.PP 3412.PP
3351\fIThe special problem of life after fork \- how is it possible?\fR 3413\fIThe special problem of life after fork \- how is it possible?\fR
3352.IX Subsection "The special problem of life after fork - how is it possible?" 3414.IX Subsection "The special problem of life after fork - how is it possible?"
3353.PP 3415.PP
3354Most uses of \f(CW\*(C`fork()\*(C'\fR consist of forking, then some simple calls to set 3416Most uses of \f(CW\*(C`fork()\*(C'\fR consist of forking, then some simple calls to set
3440it by calling \f(CW\*(C`ev_async_send\*(C'\fR, which is thread\- and signal safe. 3502it by calling \f(CW\*(C`ev_async_send\*(C'\fR, which is thread\- and signal safe.
3441.PP 3503.PP
3442This functionality is very similar to \f(CW\*(C`ev_signal\*(C'\fR watchers, as signals, 3504This functionality is very similar to \f(CW\*(C`ev_signal\*(C'\fR watchers, as signals,
3443too, are asynchronous in nature, and signals, too, will be compressed 3505too, are asynchronous in nature, and signals, too, will be compressed
3444(i.e. the number of callback invocations may be less than the number of 3506(i.e. the number of callback invocations may be less than the number of
3445\&\f(CW\*(C`ev_async_sent\*(C'\fR calls). In fact, you could use signal watchers as a kind 3507\&\f(CW\*(C`ev_async_send\*(C'\fR calls). In fact, you could use signal watchers as a kind
3446of \*(L"global async watchers\*(R" by using a watcher on an otherwise unused 3508of \*(L"global async watchers\*(R" by using a watcher on an otherwise unused
3447signal, and \f(CW\*(C`ev_feed_signal\*(C'\fR to signal this watcher from another thread, 3509signal, and \f(CW\*(C`ev_feed_signal\*(C'\fR to signal this watcher from another thread,
3448even without knowing which loop owns the signal. 3510even without knowing which loop owns the signal.
3449.PP 3511.PP
3450\fIQueueing\fR 3512\fIQueueing\fR
3599\&\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_TIMER\*(C'\fR) and the \f(CW\*(C`arg\*(C'\fR 3661\&\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_TIMER\*(C'\fR) and the \f(CW\*(C`arg\*(C'\fR
3600value passed to \f(CW\*(C`ev_once\*(C'\fR. Note that it is possible to receive \fIboth\fR 3662value passed to \f(CW\*(C`ev_once\*(C'\fR. Note that it is possible to receive \fIboth\fR
3601a timeout and an io event at the same time \- you probably should give io 3663a timeout and an io event at the same time \- you probably should give io
3602events precedence. 3664events precedence.
3603.Sp 3665.Sp
3604Example: wait up to ten seconds for data to appear on \s-1STDIN_FILENO\s0. 3666Example: wait up to ten seconds for data to appear on \s-1STDIN_FILENO.\s0
3605.Sp 3667.Sp
3606.Vb 7 3668.Vb 7
3607\& static void stdin_ready (int revents, void *arg) 3669\& static void stdin_ready (int revents, void *arg)
3608\& { 3670\& {
3609\& if (revents & EV_READ) 3671\& if (revents & EV_READ)
3625.SH "COMMON OR USEFUL IDIOMS (OR BOTH)" 3687.SH "COMMON OR USEFUL IDIOMS (OR BOTH)"
3626.IX Header "COMMON OR USEFUL IDIOMS (OR BOTH)" 3688.IX Header "COMMON OR USEFUL IDIOMS (OR BOTH)"
3627This section explains some common idioms that are not immediately 3689This section explains some common idioms that are not immediately
3628obvious. Note that examples are sprinkled over the whole manual, and this 3690obvious. Note that examples are sprinkled over the whole manual, and this
3629section only contains stuff that wouldn't fit anywhere else. 3691section only contains stuff that wouldn't fit anywhere else.
3630.SS "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" 3692.SS "\s-1ASSOCIATING CUSTOM DATA WITH A WATCHER\s0"
3631.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" 3693.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER"
3632Each watcher has, by default, a \f(CW\*(C`void *data\*(C'\fR member that you can read 3694Each watcher has, by default, a \f(CW\*(C`void *data\*(C'\fR member that you can read
3633or modify at any time: libev will completely ignore it. This can be used 3695or modify at any time: libev will completely ignore it. This can be used
3634to associate arbitrary data with your watcher. If you need more data and 3696to associate arbitrary data with your watcher. If you need more data and
3635don't want to allocate memory separately and store a pointer to it in that 3697don't want to allocate memory separately and store a pointer to it in that
3661\& } 3723\& }
3662.Ve 3724.Ve
3663.PP 3725.PP
3664More interesting and less C\-conformant ways of casting your callback 3726More interesting and less C\-conformant ways of casting your callback
3665function type instead have been omitted. 3727function type instead have been omitted.
3666.SS "\s-1BUILDING\s0 \s-1YOUR\s0 \s-1OWN\s0 \s-1COMPOSITE\s0 \s-1WATCHERS\s0" 3728.SS "\s-1BUILDING YOUR OWN COMPOSITE WATCHERS\s0"
3667.IX Subsection "BUILDING YOUR OWN COMPOSITE WATCHERS" 3729.IX Subsection "BUILDING YOUR OWN COMPOSITE WATCHERS"
3668Another common scenario is to use some data structure with multiple 3730Another common scenario is to use some data structure with multiple
3669embedded watchers, in effect creating your own watcher that combines 3731embedded watchers, in effect creating your own watcher that combines
3670multiple libev event sources into one \*(L"super-watcher\*(R": 3732multiple libev event sources into one \*(L"super-watcher\*(R":
3671.PP 3733.PP
3699\& { 3761\& {
3700\& struct my_biggy big = (struct my_biggy *) 3762\& struct my_biggy big = (struct my_biggy *)
3701\& (((char *)w) \- offsetof (struct my_biggy, t2)); 3763\& (((char *)w) \- offsetof (struct my_biggy, t2));
3702\& } 3764\& }
3703.Ve 3765.Ve
3704.SS "\s-1AVOIDING\s0 \s-1FINISHING\s0 \s-1BEFORE\s0 \s-1RETURNING\s0" 3766.SS "\s-1AVOIDING FINISHING BEFORE RETURNING\s0"
3705.IX Subsection "AVOIDING FINISHING BEFORE RETURNING" 3767.IX Subsection "AVOIDING FINISHING BEFORE RETURNING"
3706Often you have structures like this in event-based programs: 3768Often you have structures like this in event-based programs:
3707.PP 3769.PP
3708.Vb 4 3770.Vb 4
3709\& callback () 3771\& callback ()
3731already been invoked. 3793already been invoked.
3732.PP 3794.PP
3733A common way around all these issues is to make sure that 3795A common way around all these issues is to make sure that
3734\&\f(CW\*(C`start_new_request\*(C'\fR \fIalways\fR returns before the callback is invoked. If 3796\&\f(CW\*(C`start_new_request\*(C'\fR \fIalways\fR returns before the callback is invoked. If
3735\&\f(CW\*(C`start_new_request\*(C'\fR immediately knows the result, it can artificially 3797\&\f(CW\*(C`start_new_request\*(C'\fR immediately knows the result, it can artificially
3736delay invoking the callback by e.g. using a \f(CW\*(C`prepare\*(C'\fR or \f(CW\*(C`idle\*(C'\fR watcher 3798delay invoking the callback by using a \f(CW\*(C`prepare\*(C'\fR or \f(CW\*(C`idle\*(C'\fR watcher for
3737for example, or more sneakily, by reusing an existing (stopped) watcher 3799example, or more sneakily, by reusing an existing (stopped) watcher and
3738and pushing it into the pending queue: 3800pushing it into the pending queue:
3739.PP 3801.PP
3740.Vb 2 3802.Vb 2
3741\& ev_set_cb (watcher, callback); 3803\& ev_set_cb (watcher, callback);
3742\& ev_feed_event (EV_A_ watcher, 0); 3804\& ev_feed_event (EV_A_ watcher, 0);
3743.Ve 3805.Ve
3744.PP 3806.PP
3745This way, \f(CW\*(C`start_new_request\*(C'\fR can safely return before the callback is 3807This way, \f(CW\*(C`start_new_request\*(C'\fR can safely return before the callback is
3746invoked, while not delaying callback invocation too much. 3808invoked, while not delaying callback invocation too much.
3747.SS "\s-1MODEL/NESTED\s0 \s-1EVENT\s0 \s-1LOOP\s0 \s-1INVOCATIONS\s0 \s-1AND\s0 \s-1EXIT\s0 \s-1CONDITIONS\s0" 3809.SS "\s-1MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS\s0"
3748.IX Subsection "MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS" 3810.IX Subsection "MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS"
3749Often (especially in \s-1GUI\s0 toolkits) there are places where you have 3811Often (especially in \s-1GUI\s0 toolkits) there are places where you have
3750\&\fImodal\fR interaction, which is most easily implemented by recursively 3812\&\fImodal\fR interaction, which is most easily implemented by recursively
3751invoking \f(CW\*(C`ev_run\*(C'\fR. 3813invoking \f(CW\*(C`ev_run\*(C'\fR.
3752.PP 3814.PP
3753This brings the problem of exiting \- a callback might want to finish the 3815This brings the problem of exiting \- a callback might want to finish the
3754main \f(CW\*(C`ev_run\*(C'\fR call, but not the nested one (e.g. user clicked \*(L"Quit\*(R", but 3816main \f(CW\*(C`ev_run\*(C'\fR call, but not the nested one (e.g. user clicked \*(L"Quit\*(R", but
3755a modal \*(L"Are you sure?\*(R" dialog is still waiting), or just the nested one 3817a modal \*(L"Are you sure?\*(R" dialog is still waiting), or just the nested one
3756and not the main one (e.g. user clocked \*(L"Ok\*(R" in a modal dialog), or some 3818and not the main one (e.g. user clocked \*(L"Ok\*(R" in a modal dialog), or some
3757other combination: In these cases, \f(CW\*(C`ev_break\*(C'\fR will not work alone. 3819other combination: In these cases, a simple \f(CW\*(C`ev_break\*(C'\fR will not work.
3758.PP 3820.PP
3759The solution is to maintain \*(L"break this loop\*(R" variable for each \f(CW\*(C`ev_run\*(C'\fR 3821The solution is to maintain \*(L"break this loop\*(R" variable for each \f(CW\*(C`ev_run\*(C'\fR
3760invocation, and use a loop around \f(CW\*(C`ev_run\*(C'\fR until the condition is 3822invocation, and use a loop around \f(CW\*(C`ev_run\*(C'\fR until the condition is
3761triggered, using \f(CW\*(C`EVRUN_ONCE\*(C'\fR: 3823triggered, using \f(CW\*(C`EVRUN_ONCE\*(C'\fR:
3762.PP 3824.PP
3784\& exit_main_loop = 1; 3846\& exit_main_loop = 1;
3785\& 3847\&
3786\& // exit both 3848\& // exit both
3787\& exit_main_loop = exit_nested_loop = 1; 3849\& exit_main_loop = exit_nested_loop = 1;
3788.Ve 3850.Ve
3789.SS "\s-1THREAD\s0 \s-1LOCKING\s0 \s-1EXAMPLE\s0" 3851.SS "\s-1THREAD LOCKING EXAMPLE\s0"
3790.IX Subsection "THREAD LOCKING EXAMPLE" 3852.IX Subsection "THREAD LOCKING EXAMPLE"
3791Here is a fictitious example of how to run an event loop in a different 3853Here is a fictitious example of how to run an event loop in a different
3792thread from where callbacks are being invoked and watchers are 3854thread from where callbacks are being invoked and watchers are
3793created/added/removed. 3855created/added/removed.
3794.PP 3856.PP
3935.PP 3997.PP
3936Note that sending the \f(CW\*(C`ev_async\*(C'\fR watcher is required because otherwise 3998Note that sending the \f(CW\*(C`ev_async\*(C'\fR watcher is required because otherwise
3937an event loop currently blocking in the kernel will have no knowledge 3999an event loop currently blocking in the kernel will have no knowledge
3938about the newly added timer. By waking up the loop it will pick up any new 4000about the newly added timer. By waking up the loop it will pick up any new
3939watchers in the next event loop iteration. 4001watchers in the next event loop iteration.
3940.SS "\s-1THREADS\s0, \s-1COROUTINES\s0, \s-1CONTINUATIONS\s0, \s-1QUEUES\s0... \s-1INSTEAD\s0 \s-1OF\s0 \s-1CALLBACKS\s0" 4002.SS "\s-1THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS\s0"
3941.IX Subsection "THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS" 4003.IX Subsection "THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS"
3942While the overhead of a callback that e.g. schedules a thread is small, it 4004While the overhead of a callback that e.g. schedules a thread is small, it
3943is still an overhead. If you embed libev, and your main usage is with some 4005is still an overhead. If you embed libev, and your main usage is with some
3944kind of threads or coroutines, you might want to customise libev so that 4006kind of threads or coroutines, you might want to customise libev so that
3945doesn't need callbacks anymore. 4007doesn't need callbacks anymore.
3967.PP 4029.PP
3968.Vb 6 4030.Vb 6
3969\& void 4031\& void
3970\& wait_for_event (ev_watcher *w) 4032\& wait_for_event (ev_watcher *w)
3971\& { 4033\& {
3972\& ev_cb_set (w) = current_coro; 4034\& ev_set_cb (w, current_coro);
3973\& switch_to (libev_coro); 4035\& switch_to (libev_coro);
3974\& } 4036\& }
3975.Ve 4037.Ve
3976.PP 4038.PP
3977That basically suspends the coroutine inside \f(CW\*(C`wait_for_event\*(C'\fR and 4039That basically suspends the coroutine inside \f(CW\*(C`wait_for_event\*(C'\fR and
3981You can do similar tricks if you have, say, threads with an event queue \- 4043You can do similar tricks if you have, say, threads with an event queue \-
3982instead of storing a coroutine, you store the queue object and instead of 4044instead of storing a coroutine, you store the queue object and instead of
3983switching to a coroutine, you push the watcher onto the queue and notify 4045switching to a coroutine, you push the watcher onto the queue and notify
3984any waiters. 4046any waiters.
3985.PP 4047.PP
3986To embed libev, see \s-1EMBEDDING\s0, but in short, it's easiest to create two 4048To embed libev, see \*(L"\s-1EMBEDDING\*(R"\s0, but in short, it's easiest to create two
3987files, \fImy_ev.h\fR and \fImy_ev.c\fR that include the respective libev files: 4049files, \fImy_ev.h\fR and \fImy_ev.c\fR that include the respective libev files:
3988.PP 4050.PP
3989.Vb 4 4051.Vb 4
3990\& // my_ev.h 4052\& // my_ev.h
3991\& #define EV_CB_DECLARE(type) struct my_coro *cb; 4053\& #define EV_CB_DECLARE(type) struct my_coro *cb;
4030.IP "\(bu" 4 4092.IP "\(bu" 4
4031The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need 4093The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need
4032to use the libev header file and library. 4094to use the libev header file and library.
4033.SH "\*(C+ SUPPORT" 4095.SH "\*(C+ SUPPORT"
4034.IX Header " SUPPORT" 4096.IX Header " SUPPORT"
4097.SS "C \s-1API\s0"
4098.IX Subsection "C API"
4099The normal C \s-1API\s0 should work fine when used from \*(C+: both ev.h and the
4100libev sources can be compiled as \*(C+. Therefore, code that uses the C \s-1API\s0
4101will work fine.
4102.PP
4103Proper exception specifications might have to be added to callbacks passed
4104to libev: exceptions may be thrown only from watcher callbacks, all
4105other callbacks (allocator, syserr, loop acquire/release and periodic
4106reschedule callbacks) must not throw exceptions, and might need a \f(CW\*(C`throw
4107()\*(C'\fR specification. If you have code that needs to be compiled as both C
4108and \*(C+ you can use the \f(CW\*(C`EV_THROW\*(C'\fR macro for this:
4109.PP
4110.Vb 6
4111\& static void
4112\& fatal_error (const char *msg) EV_THROW
4113\& {
4114\& perror (msg);
4115\& abort ();
4116\& }
4117\&
4118\& ...
4119\& ev_set_syserr_cb (fatal_error);
4120.Ve
4121.PP
4122The only \s-1API\s0 functions that can currently throw exceptions are \f(CW\*(C`ev_run\*(C'\fR,
4123\&\f(CW\*(C`ev_invoke\*(C'\fR, \f(CW\*(C`ev_invoke_pending\*(C'\fR and \f(CW\*(C`ev_loop_destroy\*(C'\fR (the latter
4124because it runs cleanup watchers).
4125.PP
4126Throwing exceptions in watcher callbacks is only supported if libev itself
4127is compiled with a \*(C+ compiler or your C and \*(C+ environments allow
4128throwing exceptions through C libraries (most do).
4129.SS "\*(C+ \s-1API\s0"
4130.IX Subsection " API"
4035Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow 4131Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow
4036you to use some convenience methods to start/stop watchers and also change 4132you to use some convenience methods to start/stop watchers and also change
4037the callback model to a model using method callbacks on objects. 4133the callback model to a model using method callbacks on objects.
4038.PP 4134.PP
4039To use it, 4135To use it,
4055Currently, functions, static and non-static member functions and classes 4151Currently, functions, static and non-static member functions and classes
4056with \f(CW\*(C`operator ()\*(C'\fR can be used as callbacks. Other types should be easy 4152with \f(CW\*(C`operator ()\*(C'\fR can be used as callbacks. Other types should be easy
4057to add as long as they only need one additional pointer for context. If 4153to add as long as they only need one additional pointer for context. If
4058you need support for other types of functors please contact the author 4154you need support for other types of functors please contact the author
4059(preferably after implementing it). 4155(preferably after implementing it).
4156.PP
4157For all this to work, your \*(C+ compiler either has to use the same calling
4158conventions as your C compiler (for static member functions), or you have
4159to embed libev and compile libev itself as \*(C+.
4060.PP 4160.PP
4061Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: 4161Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace:
4062.ie n .IP """ev::READ"", ""ev::WRITE"" etc." 4 4162.ie n .IP """ev::READ"", ""ev::WRITE"" etc." 4
4063.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 4163.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4
4064.IX Item "ev::READ, ev::WRITE etc." 4164.IX Item "ev::READ, ev::WRITE etc."
4173.IX Item "w->set (loop)" 4273.IX Item "w->set (loop)"
4174Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only 4274Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only
4175do this when the watcher is inactive (and not pending either). 4275do this when the watcher is inactive (and not pending either).
4176.IP "w\->set ([arguments])" 4 4276.IP "w\->set ([arguments])" 4
4177.IX Item "w->set ([arguments])" 4277.IX Item "w->set ([arguments])"
4178Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same arguments. Either this 4278Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR (except for \f(CW\*(C`ev::embed\*(C'\fR watchers>),
4179method or a suitable start method must be called at least once. Unlike the 4279with the same arguments. Either this method or a suitable start method
4180C counterpart, an active watcher gets automatically stopped and restarted 4280must be called at least once. Unlike the C counterpart, an active watcher
4181when reconfiguring it with this method. 4281gets automatically stopped and restarted when reconfiguring it with this
4282method.
4283.Sp
4284For \f(CW\*(C`ev::embed\*(C'\fR watchers this method is called \f(CW\*(C`set_embed\*(C'\fR, to avoid
4285clashing with the \f(CW\*(C`set (loop)\*(C'\fR method.
4182.IP "w\->start ()" 4 4286.IP "w\->start ()" 4
4183.IX Item "w->start ()" 4287.IX Item "w->start ()"
4184Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the 4288Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the
4185constructor already stores the event loop. 4289constructor already stores the event loop.
4186.IP "w\->start ([arguments])" 4 4290.IP "w\->start ([arguments])" 4
4244there are additional modules that implement libev-compatible interfaces 4348there are additional modules that implement libev-compatible interfaces
4245to \f(CW\*(C`libadns\*(C'\fR (\f(CW\*(C`EV::ADNS\*(C'\fR, but \f(CW\*(C`AnyEvent::DNS\*(C'\fR is preferred nowadays), 4349to \f(CW\*(C`libadns\*(C'\fR (\f(CW\*(C`EV::ADNS\*(C'\fR, but \f(CW\*(C`AnyEvent::DNS\*(C'\fR is preferred nowadays),
4246\&\f(CW\*(C`Net::SNMP\*(C'\fR (\f(CW\*(C`Net::SNMP::EV\*(C'\fR) and the \f(CW\*(C`libglib\*(C'\fR event core (\f(CW\*(C`Glib::EV\*(C'\fR 4350\&\f(CW\*(C`Net::SNMP\*(C'\fR (\f(CW\*(C`Net::SNMP::EV\*(C'\fR) and the \f(CW\*(C`libglib\*(C'\fR event core (\f(CW\*(C`Glib::EV\*(C'\fR
4247and \f(CW\*(C`EV::Glib\*(C'\fR). 4351and \f(CW\*(C`EV::Glib\*(C'\fR).
4248.Sp 4352.Sp
4249It can be found and installed via \s-1CPAN\s0, its homepage is at 4353It can be found and installed via \s-1CPAN,\s0 its homepage is at
4250<http://software.schmorp.de/pkg/EV>. 4354<http://software.schmorp.de/pkg/EV>.
4251.IP "Python" 4 4355.IP "Python" 4
4252.IX Item "Python" 4356.IX Item "Python"
4253Python bindings can be found at <http://code.google.com/p/pyev/>. It 4357Python bindings can be found at <http://code.google.com/p/pyev/>. It
4254seems to be quite complete and well-documented. 4358seems to be quite complete and well-documented.
4262Roger Pack reports that using the link order \f(CW\*(C`\-lws2_32 \-lmsvcrt\-ruby\-190\*(C'\fR 4366Roger Pack reports that using the link order \f(CW\*(C`\-lws2_32 \-lmsvcrt\-ruby\-190\*(C'\fR
4263makes rev work even on mingw. 4367makes rev work even on mingw.
4264.IP "Haskell" 4 4368.IP "Haskell" 4
4265.IX Item "Haskell" 4369.IX Item "Haskell"
4266A haskell binding to libev is available at 4370A haskell binding to libev is available at
4267http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev <http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hlibev>. 4371<http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev>.
4268.IP "D" 4 4372.IP "D" 4
4269.IX Item "D" 4373.IX Item "D"
4270Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to 4374Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to
4271be found at <http://www.llucax.com.ar/proj/ev.d/index.html>. 4375be found at <http://www.llucax.com.ar/proj/ev.d/index.html>.
4272.IP "Ocaml" 4 4376.IP "Ocaml" 4
4273.IX Item "Ocaml" 4377.IX Item "Ocaml"
4274Erkki Seppala has written Ocaml bindings for libev, to be found at 4378Erkki Seppala has written Ocaml bindings for libev, to be found at
4275http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/ <http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. 4379<http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/>.
4276.IP "Lua" 4 4380.IP "Lua" 4
4277.IX Item "Lua" 4381.IX Item "Lua"
4278Brian Maher has written a partial interface to libev for lua (at the 4382Brian Maher has written a partial interface to libev for lua (at the
4279time of this writing, only \f(CW\*(C`ev_io\*(C'\fR and \f(CW\*(C`ev_timer\*(C'\fR), to be found at 4383time of this writing, only \f(CW\*(C`ev_io\*(C'\fR and \f(CW\*(C`ev_timer\*(C'\fR), to be found at
4280http://github.com/brimworks/lua\-ev <http://github.com/brimworks/lua-ev>. 4384<http://github.com/brimworks/lua\-ev>.
4385.IP "Javascript" 4
4386.IX Item "Javascript"
4387Node.js (<http://nodejs.org>) uses libev as the underlying event library.
4388.IP "Others" 4
4389.IX Item "Others"
4390There are others, and I stopped counting.
4281.SH "MACRO MAGIC" 4391.SH "MACRO MAGIC"
4282.IX Header "MACRO MAGIC" 4392.IX Header "MACRO MAGIC"
4283Libev can be compiled with a variety of options, the most fundamental 4393Libev can be compiled with a variety of options, the most fundamental
4284of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) 4394of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most)
4285functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. 4395functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument.
4368.SS "\s-1FILESETS\s0" 4478.SS "\s-1FILESETS\s0"
4369.IX Subsection "FILESETS" 4479.IX Subsection "FILESETS"
4370Depending on what features you need you need to include one or more sets of files 4480Depending on what features you need you need to include one or more sets of files
4371in your application. 4481in your application.
4372.PP 4482.PP
4373\fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR 4483\fI\s-1CORE EVENT LOOP\s0\fR
4374.IX Subsection "CORE EVENT LOOP" 4484.IX Subsection "CORE EVENT LOOP"
4375.PP 4485.PP
4376To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual 4486To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual
4377configuration (no autoconf): 4487configuration (no autoconf):
4378.PP 4488.PP
4381\& #include "ev.c" 4491\& #include "ev.c"
4382.Ve 4492.Ve
4383.PP 4493.PP
4384This will automatically include \fIev.h\fR, too, and should be done in a 4494This will automatically include \fIev.h\fR, too, and should be done in a
4385single C source file only to provide the function implementations. To use 4495single C source file only to provide the function implementations. To use
4386it, do the same for \fIev.h\fR in all files wishing to use this \s-1API\s0 (best 4496it, do the same for \fIev.h\fR in all files wishing to use this \s-1API \s0(best
4387done by writing a wrapper around \fIev.h\fR that you can include instead and 4497done by writing a wrapper around \fIev.h\fR that you can include instead and
4388where you can put other configuration options): 4498where you can put other configuration options):
4389.PP 4499.PP
4390.Vb 2 4500.Vb 2
4391\& #define EV_STANDALONE 1 4501\& #define EV_STANDALONE 1
4415.Ve 4525.Ve
4416.PP 4526.PP
4417\&\fIev.c\fR includes the backend files directly when enabled, so you only need 4527\&\fIev.c\fR includes the backend files directly when enabled, so you only need
4418to compile this single file. 4528to compile this single file.
4419.PP 4529.PP
4420\fI\s-1LIBEVENT\s0 \s-1COMPATIBILITY\s0 \s-1API\s0\fR 4530\fI\s-1LIBEVENT COMPATIBILITY API\s0\fR
4421.IX Subsection "LIBEVENT COMPATIBILITY API" 4531.IX Subsection "LIBEVENT COMPATIBILITY API"
4422.PP 4532.PP
4423To include the libevent compatibility \s-1API\s0, also include: 4533To include the libevent compatibility \s-1API,\s0 also include:
4424.PP 4534.PP
4425.Vb 1 4535.Vb 1
4426\& #include "event.c" 4536\& #include "event.c"
4427.Ve 4537.Ve
4428.PP 4538.PP
4430.PP 4540.PP
4431.Vb 1 4541.Vb 1
4432\& #include "event.h" 4542\& #include "event.h"
4433.Ve 4543.Ve
4434.PP 4544.PP
4435in the files that want to use the libevent \s-1API\s0. This also includes \fIev.h\fR. 4545in the files that want to use the libevent \s-1API.\s0 This also includes \fIev.h\fR.
4436.PP 4546.PP
4437You need the following additional files for this: 4547You need the following additional files for this:
4438.PP 4548.PP
4439.Vb 2 4549.Vb 2
4440\& event.h 4550\& event.h
4441\& event.c 4551\& event.c
4442.Ve 4552.Ve
4443.PP 4553.PP
4444\fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR 4554\fI\s-1AUTOCONF SUPPORT\s0\fR
4445.IX Subsection "AUTOCONF SUPPORT" 4555.IX Subsection "AUTOCONF SUPPORT"
4446.PP 4556.PP
4447Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your configuration in 4557Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your configuration in
4448whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your 4558whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your
4449\&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then 4559\&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then
4452For this of course you need the m4 file: 4562For this of course you need the m4 file:
4453.PP 4563.PP
4454.Vb 1 4564.Vb 1
4455\& libev.m4 4565\& libev.m4
4456.Ve 4566.Ve
4457.SS "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" 4567.SS "\s-1PREPROCESSOR SYMBOLS/MACROS\s0"
4458.IX Subsection "PREPROCESSOR SYMBOLS/MACROS" 4568.IX Subsection "PREPROCESSOR SYMBOLS/MACROS"
4459Libev can be configured via a variety of preprocessor symbols you have to 4569Libev can be configured via a variety of preprocessor symbols you have to
4460define before including (or compiling) any of its files. The default in 4570define before including (or compiling) any of its files. The default in
4461the absence of autoconf is documented for every option. 4571the absence of autoconf is documented for every option.
4462.PP 4572.PP
4463Symbols marked with \*(L"(h)\*(R" do not change the \s-1ABI\s0, and can have different 4573Symbols marked with \*(L"(h)\*(R" do not change the \s-1ABI,\s0 and can have different
4464values when compiling libev vs. including \fIev.h\fR, so it is permissible 4574values when compiling libev vs. including \fIev.h\fR, so it is permissible
4465to redefine them before including \fIev.h\fR without breaking compatibility 4575to redefine them before including \fIev.h\fR without breaking compatibility
4466to a compiled library. All other symbols change the \s-1ABI\s0, which means all 4576to a compiled library. All other symbols change the \s-1ABI,\s0 which means all
4467users of libev and the libev code itself must be compiled with compatible 4577users of libev and the libev code itself must be compiled with compatible
4468settings. 4578settings.
4469.IP "\s-1EV_COMPAT3\s0 (h)" 4 4579.IP "\s-1EV_COMPAT3 \s0(h)" 4
4470.IX Item "EV_COMPAT3 (h)" 4580.IX Item "EV_COMPAT3 (h)"
4471Backwards compatibility is a major concern for libev. This is why this 4581Backwards compatibility is a major concern for libev. This is why this
4472release of libev comes with wrappers for the functions and symbols that 4582release of libev comes with wrappers for the functions and symbols that
4473have been renamed between libev version 3 and 4. 4583have been renamed between libev version 3 and 4.
4474.Sp 4584.Sp
4479typedef in that case. 4589typedef in that case.
4480.Sp 4590.Sp
4481In some future version, the default for \f(CW\*(C`EV_COMPAT3\*(C'\fR will become \f(CW0\fR, 4591In some future version, the default for \f(CW\*(C`EV_COMPAT3\*(C'\fR will become \f(CW0\fR,
4482and in some even more future version the compatibility code will be 4592and in some even more future version the compatibility code will be
4483removed completely. 4593removed completely.
4484.IP "\s-1EV_STANDALONE\s0 (h)" 4 4594.IP "\s-1EV_STANDALONE \s0(h)" 4
4485.IX Item "EV_STANDALONE (h)" 4595.IX Item "EV_STANDALONE (h)"
4486Must always be \f(CW1\fR if you do not use autoconf configuration, which 4596Must always be \f(CW1\fR if you do not use autoconf configuration, which
4487keeps libev from including \fIconfig.h\fR, and it also defines dummy 4597keeps libev from including \fIconfig.h\fR, and it also defines dummy
4488implementations for some libevent functions (such as logging, which is not 4598implementations for some libevent functions (such as logging, which is not
4489supported). It will also not define any of the structs usually found in 4599supported). It will also not define any of the structs usually found in
4580.IX Item "EV_WIN32_CLOSE_FD(fd)" 4690.IX Item "EV_WIN32_CLOSE_FD(fd)"
4581If programs implement their own fd to handle mapping on win32, then this 4691If programs implement their own fd to handle mapping on win32, then this
4582macro can be used to override the \f(CW\*(C`close\*(C'\fR function, useful to unregister 4692macro can be used to override the \f(CW\*(C`close\*(C'\fR function, useful to unregister
4583file descriptors again. Note that the replacement function has to close 4693file descriptors again. Note that the replacement function has to close
4584the underlying \s-1OS\s0 handle. 4694the underlying \s-1OS\s0 handle.
4695.IP "\s-1EV_USE_WSASOCKET\s0" 4
4696.IX Item "EV_USE_WSASOCKET"
4697If defined to be \f(CW1\fR, libev will use \f(CW\*(C`WSASocket\*(C'\fR to create its internal
4698communication socket, which works better in some environments. Otherwise,
4699the normal \f(CW\*(C`socket\*(C'\fR function will be used, which works better in other
4700environments.
4585.IP "\s-1EV_USE_POLL\s0" 4 4701.IP "\s-1EV_USE_POLL\s0" 4
4586.IX Item "EV_USE_POLL" 4702.IX Item "EV_USE_POLL"
4587If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) 4703If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2)
4588backend. Otherwise it will be enabled on non\-win32 platforms. It 4704backend. Otherwise it will be enabled on non\-win32 platforms. It
4589takes precedence over select. 4705takes precedence over select.
4626between threads, that is, threads can be used, but threads never run on 4742between threads, that is, threads can be used, but threads never run on
4627different cpus (or different cpu cores). This reduces dependencies 4743different cpus (or different cpu cores). This reduces dependencies
4628and makes libev faster. 4744and makes libev faster.
4629.IP "\s-1EV_NO_THREADS\s0" 4 4745.IP "\s-1EV_NO_THREADS\s0" 4
4630.IX Item "EV_NO_THREADS" 4746.IX Item "EV_NO_THREADS"
4631If defined to be \f(CW1\fR, libev will assume that it will never be called 4747If defined to be \f(CW1\fR, libev will assume that it will never be called from
4632from different threads, which is a stronger assumption than \f(CW\*(C`EV_NO_SMP\*(C'\fR, 4748different threads (that includes signal handlers), which is a stronger
4633above. This reduces dependencies and makes libev faster. 4749assumption than \f(CW\*(C`EV_NO_SMP\*(C'\fR, above. This reduces dependencies and makes
4750libev faster.
4634.IP "\s-1EV_ATOMIC_T\s0" 4 4751.IP "\s-1EV_ATOMIC_T\s0" 4
4635.IX Item "EV_ATOMIC_T" 4752.IX Item "EV_ATOMIC_T"
4636Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose 4753Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose
4637access is atomic and serialised with respect to other threads or signal 4754access is atomic with respect to other threads or signal contexts. No
4638contexts. No such type is easily found in the C language, so you can 4755such type is easily found in the C language, so you can provide your own
4639provide your own type that you know is safe for your purposes. It is used 4756type that you know is safe for your purposes. It is used both for signal
4640both for signal handler \*(L"locking\*(R" as well as for signal and thread safety 4757handler \*(L"locking\*(R" as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR
4641in \f(CW\*(C`ev_async\*(C'\fR watchers. 4758watchers.
4642.Sp 4759.Sp
4643In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR 4760In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR
4644(from \fIsignal.h\fR), which is usually good enough on most platforms, 4761(from \fIsignal.h\fR), which is usually good enough on most platforms.
4645although strictly speaking using a type that also implies a memory fence
4646is required.
4647.IP "\s-1EV_H\s0 (h)" 4 4762.IP "\s-1EV_H \s0(h)" 4
4648.IX Item "EV_H (h)" 4763.IX Item "EV_H (h)"
4649The name of the \fIev.h\fR header file used to include it. The default if 4764The name of the \fIev.h\fR header file used to include it. The default if
4650undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be 4765undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be
4651used to virtually rename the \fIev.h\fR header file in case of conflicts. 4766used to virtually rename the \fIev.h\fR header file in case of conflicts.
4652.IP "\s-1EV_CONFIG_H\s0 (h)" 4 4767.IP "\s-1EV_CONFIG_H \s0(h)" 4
4653.IX Item "EV_CONFIG_H (h)" 4768.IX Item "EV_CONFIG_H (h)"
4654If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override 4769If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override
4655\&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to 4770\&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to
4656\&\f(CW\*(C`EV_H\*(C'\fR, above. 4771\&\f(CW\*(C`EV_H\*(C'\fR, above.
4657.IP "\s-1EV_EVENT_H\s0 (h)" 4 4772.IP "\s-1EV_EVENT_H \s0(h)" 4
4658.IX Item "EV_EVENT_H (h)" 4773.IX Item "EV_EVENT_H (h)"
4659Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea 4774Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea
4660of how the \fIevent.h\fR header can be found, the default is \f(CW"event.h"\fR. 4775of how the \fIevent.h\fR header can be found, the default is \f(CW"event.h"\fR.
4661.IP "\s-1EV_PROTOTYPES\s0 (h)" 4 4776.IP "\s-1EV_PROTOTYPES \s0(h)" 4
4662.IX Item "EV_PROTOTYPES (h)" 4777.IX Item "EV_PROTOTYPES (h)"
4663If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function 4778If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function
4664prototypes, but still define all the structs and other symbols. This is 4779prototypes, but still define all the structs and other symbols. This is
4665occasionally useful if you want to provide your own wrapper functions 4780occasionally useful if you want to provide your own wrapper functions
4666around libev functions. 4781around libev functions.
4690all the priorities, so having many of them (hundreds) uses a lot of space 4805all the priorities, so having many of them (hundreds) uses a lot of space
4691and time, so using the defaults of five priorities (\-2 .. +2) is usually 4806and time, so using the defaults of five priorities (\-2 .. +2) is usually
4692fine. 4807fine.
4693.Sp 4808.Sp
4694If your embedding application does not need any priorities, defining these 4809If your embedding application does not need any priorities, defining these
4695both to \f(CW0\fR will save some memory and \s-1CPU\s0. 4810both to \f(CW0\fR will save some memory and \s-1CPU.\s0
4696.IP "\s-1EV_PERIODIC_ENABLE\s0, \s-1EV_IDLE_ENABLE\s0, \s-1EV_EMBED_ENABLE\s0, \s-1EV_STAT_ENABLE\s0, \s-1EV_PREPARE_ENABLE\s0, \s-1EV_CHECK_ENABLE\s0, \s-1EV_FORK_ENABLE\s0, \s-1EV_SIGNAL_ENABLE\s0, \s-1EV_ASYNC_ENABLE\s0, \s-1EV_CHILD_ENABLE\s0." 4 4811.IP "\s-1EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE, EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, EV_ASYNC_ENABLE, EV_CHILD_ENABLE.\s0" 4
4697.IX Item "EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE, EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, EV_ASYNC_ENABLE, EV_CHILD_ENABLE." 4812.IX Item "EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE, EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, EV_ASYNC_ENABLE, EV_CHILD_ENABLE."
4698If undefined or defined to be \f(CW1\fR (and the platform supports it), then 4813If undefined or defined to be \f(CW1\fR (and the platform supports it), then
4699the respective watcher type is supported. If defined to be \f(CW0\fR, then it 4814the respective watcher type is supported. If defined to be \f(CW0\fR, then it
4700is not. Disabling watcher types mainly saves code size. 4815is not. Disabling watcher types mainly saves code size.
4701.IP "\s-1EV_FEATURES\s0" 4 4816.IP "\s-1EV_FEATURES\s0" 4
4718\& #define EV_CHILD_ENABLE 1 4833\& #define EV_CHILD_ENABLE 1
4719\& #define EV_ASYNC_ENABLE 1 4834\& #define EV_ASYNC_ENABLE 1
4720.Ve 4835.Ve
4721.Sp 4836.Sp
4722The actual value is a bitset, it can be a combination of the following 4837The actual value is a bitset, it can be a combination of the following
4723values: 4838values (by default, all of these are enabled):
4724.RS 4 4839.RS 4
4725.ie n .IP "1 \- faster/larger code" 4 4840.ie n .IP "1 \- faster/larger code" 4
4726.el .IP "\f(CW1\fR \- faster/larger code" 4 4841.el .IP "\f(CW1\fR \- faster/larger code" 4
4727.IX Item "1 - faster/larger code" 4842.IX Item "1 - faster/larger code"
4728Use larger code to speed up some operations. 4843Use larger code to speed up some operations.
4731code size by roughly 30% on amd64). 4846code size by roughly 30% on amd64).
4732.Sp 4847.Sp
4733When optimising for size, use of compiler flags such as \f(CW\*(C`\-Os\*(C'\fR with 4848When optimising for size, use of compiler flags such as \f(CW\*(C`\-Os\*(C'\fR with
4734gcc is recommended, as well as \f(CW\*(C`\-DNDEBUG\*(C'\fR, as libev contains a number of 4849gcc is recommended, as well as \f(CW\*(C`\-DNDEBUG\*(C'\fR, as libev contains a number of
4735assertions. 4850assertions.
4851.Sp
4852The default is off when \f(CW\*(C`_\|_OPTIMIZE_SIZE_\|_\*(C'\fR is defined by your compiler
4853(e.g. gcc with \f(CW\*(C`\-Os\*(C'\fR).
4736.ie n .IP "2 \- faster/larger data structures" 4 4854.ie n .IP "2 \- faster/larger data structures" 4
4737.el .IP "\f(CW2\fR \- faster/larger data structures" 4 4855.el .IP "\f(CW2\fR \- faster/larger data structures" 4
4738.IX Item "2 - faster/larger data structures" 4856.IX Item "2 - faster/larger data structures"
4739Replaces the small 2\-heap for timer management by a faster 4\-heap, larger 4857Replaces the small 2\-heap for timer management by a faster 4\-heap, larger
4740hash table sizes and so on. This will usually further increase code size 4858hash table sizes and so on. This will usually further increase code size
4741and can additionally have an effect on the size of data structures at 4859and can additionally have an effect on the size of data structures at
4742runtime. 4860runtime.
4861.Sp
4862The default is off when \f(CW\*(C`_\|_OPTIMIZE_SIZE_\|_\*(C'\fR is defined by your compiler
4863(e.g. gcc with \f(CW\*(C`\-Os\*(C'\fR).
4743.ie n .IP "4 \- full \s-1API\s0 configuration" 4 4864.ie n .IP "4 \- full \s-1API\s0 configuration" 4
4744.el .IP "\f(CW4\fR \- full \s-1API\s0 configuration" 4 4865.el .IP "\f(CW4\fR \- full \s-1API\s0 configuration" 4
4745.IX Item "4 - full API configuration" 4866.IX Item "4 - full API configuration"
4746This enables priorities (sets \f(CW\*(C`EV_MAXPRI\*(C'\fR=2 and \f(CW\*(C`EV_MINPRI\*(C'\fR=\-2), and 4867This enables priorities (sets \f(CW\*(C`EV_MAXPRI\*(C'\fR=2 and \f(CW\*(C`EV_MINPRI\*(C'\fR=\-2), and
4747enables multiplicity (\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR=1). 4868enables multiplicity (\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR=1).
4869.Vb 3 4990.Vb 3
4870\& #define EV_COMMON \e 4991\& #define EV_COMMON \e
4871\& SV *self; /* contains this struct */ \e 4992\& SV *self; /* contains this struct */ \e
4872\& SV *cb_sv, *fh /* note no trailing ";" */ 4993\& SV *cb_sv, *fh /* note no trailing ";" */
4873.Ve 4994.Ve
4874.IP "\s-1EV_CB_DECLARE\s0 (type)" 4 4995.IP "\s-1EV_CB_DECLARE \s0(type)" 4
4875.IX Item "EV_CB_DECLARE (type)" 4996.IX Item "EV_CB_DECLARE (type)"
4876.PD 0 4997.PD 0
4877.IP "\s-1EV_CB_INVOKE\s0 (watcher, revents)" 4 4998.IP "\s-1EV_CB_INVOKE \s0(watcher, revents)" 4
4878.IX Item "EV_CB_INVOKE (watcher, revents)" 4999.IX Item "EV_CB_INVOKE (watcher, revents)"
4879.IP "ev_set_cb (ev, cb)" 4 5000.IP "ev_set_cb (ev, cb)" 4
4880.IX Item "ev_set_cb (ev, cb)" 5001.IX Item "ev_set_cb (ev, cb)"
4881.PD 5002.PD
4882Can be used to change the callback member declaration in each watcher, 5003Can be used to change the callback member declaration in each watcher,
4883and the way callbacks are invoked and set. Must expand to a struct member 5004and the way callbacks are invoked and set. Must expand to a struct member
4884definition and a statement, respectively. See the \fIev.h\fR header file for 5005definition and a statement, respectively. See the \fIev.h\fR header file for
4885their default definitions. One possible use for overriding these is to 5006their default definitions. One possible use for overriding these is to
4886avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use 5007avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use
4887method calls instead of plain function calls in \*(C+. 5008method calls instead of plain function calls in \*(C+.
4888.SS "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" 5009.SS "\s-1EXPORTED API SYMBOLS\s0"
4889.IX Subsection "EXPORTED API SYMBOLS" 5010.IX Subsection "EXPORTED API SYMBOLS"
4890If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of 5011If you need to re-export the \s-1API \s0(e.g. via a \s-1DLL\s0) and you need a list of
4891exported symbols, you can use the provided \fISymbol.*\fR files which list 5012exported symbols, you can use the provided \fISymbol.*\fR files which list
4892all public symbols, one per line: 5013all public symbols, one per line:
4893.PP 5014.PP
4894.Vb 2 5015.Vb 2
4895\& Symbols.ev for libev proper 5016\& Symbols.ev for libev proper
4947\& #include "ev_cpp.h" 5068\& #include "ev_cpp.h"
4948\& #include "ev.c" 5069\& #include "ev.c"
4949.Ve 5070.Ve
4950.SH "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" 5071.SH "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT"
4951.IX Header "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" 5072.IX Header "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT"
4952.SS "\s-1THREADS\s0 \s-1AND\s0 \s-1COROUTINES\s0" 5073.SS "\s-1THREADS AND COROUTINES\s0"
4953.IX Subsection "THREADS AND COROUTINES" 5074.IX Subsection "THREADS AND COROUTINES"
4954\fI\s-1THREADS\s0\fR 5075\fI\s-1THREADS\s0\fR
4955.IX Subsection "THREADS" 5076.IX Subsection "THREADS"
4956.PP 5077.PP
4957All libev functions are reentrant and thread-safe unless explicitly 5078All libev functions are reentrant and thread-safe unless explicitly
5003An example use would be to communicate signals or other events that only 5124An example use would be to communicate signals or other events that only
5004work in the default loop by registering the signal watcher with the 5125work in the default loop by registering the signal watcher with the
5005default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop 5126default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop
5006watcher callback into the event loop interested in the signal. 5127watcher callback into the event loop interested in the signal.
5007.PP 5128.PP
5008See also \*(L"\s-1THREAD\s0 \s-1LOCKING\s0 \s-1EXAMPLE\s0\*(R". 5129See also \*(L"\s-1THREAD LOCKING EXAMPLE\*(R"\s0.
5009.PP 5130.PP
5010\fI\s-1COROUTINES\s0\fR 5131\fI\s-1COROUTINES\s0\fR
5011.IX Subsection "COROUTINES" 5132.IX Subsection "COROUTINES"
5012.PP 5133.PP
5013Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): 5134Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"):
5018that you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. 5139that you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks.
5019.PP 5140.PP
5020Care has been taken to ensure that libev does not keep local state inside 5141Care has been taken to ensure that libev does not keep local state inside
5021\&\f(CW\*(C`ev_run\*(C'\fR, and other calls do not usually allow for coroutine switches as 5142\&\f(CW\*(C`ev_run\*(C'\fR, and other calls do not usually allow for coroutine switches as
5022they do not call any callbacks. 5143they do not call any callbacks.
5023.SS "\s-1COMPILER\s0 \s-1WARNINGS\s0" 5144.SS "\s-1COMPILER WARNINGS\s0"
5024.IX Subsection "COMPILER WARNINGS" 5145.IX Subsection "COMPILER WARNINGS"
5025Depending on your compiler and compiler settings, you might get no or a 5146Depending on your compiler and compiler settings, you might get no or a
5026lot of warnings when compiling libev code. Some people are apparently 5147lot of warnings when compiling libev code. Some people are apparently
5027scared by this. 5148scared by this.
5028.PP 5149.PP
5080.PP 5201.PP
5081If you need, for some reason, empty reports from valgrind for your project 5202If you need, for some reason, empty reports from valgrind for your project
5082I suggest using suppression lists. 5203I suggest using suppression lists.
5083.SH "PORTABILITY NOTES" 5204.SH "PORTABILITY NOTES"
5084.IX Header "PORTABILITY NOTES" 5205.IX Header "PORTABILITY NOTES"
5085.SS "\s-1GNU/LINUX\s0 32 \s-1BIT\s0 \s-1LIMITATIONS\s0" 5206.SS "\s-1GNU/LINUX 32 BIT LIMITATIONS\s0"
5086.IX Subsection "GNU/LINUX 32 BIT LIMITATIONS" 5207.IX Subsection "GNU/LINUX 32 BIT LIMITATIONS"
5087GNU/Linux is the only common platform that supports 64 bit file/large file 5208GNU/Linux is the only common platform that supports 64 bit file/large file
5088interfaces but \fIdisables\fR them by default. 5209interfaces but \fIdisables\fR them by default.
5089.PP 5210.PP
5090That means that libev compiled in the default environment doesn't support 5211That means that libev compiled in the default environment doesn't support
5091files larger than 2GiB or so, which mainly affects \f(CW\*(C`ev_stat\*(C'\fR watchers. 5212files larger than 2GiB or so, which mainly affects \f(CW\*(C`ev_stat\*(C'\fR watchers.
5092.PP 5213.PP
5093Unfortunately, many programs try to work around this GNU/Linux issue 5214Unfortunately, many programs try to work around this GNU/Linux issue
5094by enabling the large file \s-1API\s0, which makes them incompatible with the 5215by enabling the large file \s-1API,\s0 which makes them incompatible with the
5095standard libev compiled for their system. 5216standard libev compiled for their system.
5096.PP 5217.PP
5097Likewise, libev cannot enable the large file \s-1API\s0 itself as this would 5218Likewise, libev cannot enable the large file \s-1API\s0 itself as this would
5098suddenly make it incompatible to the default compile time environment, 5219suddenly make it incompatible to the default compile time environment,
5099i.e. all programs not using special compile switches. 5220i.e. all programs not using special compile switches.
5100.SS "\s-1OS/X\s0 \s-1AND\s0 \s-1DARWIN\s0 \s-1BUGS\s0" 5221.SS "\s-1OS/X AND DARWIN BUGS\s0"
5101.IX Subsection "OS/X AND DARWIN BUGS" 5222.IX Subsection "OS/X AND DARWIN BUGS"
5102The whole thing is a bug if you ask me \- basically any system interface 5223The whole thing is a bug if you ask me \- basically any system interface
5103you touch is broken, whether it is locales, poll, kqueue or even the 5224you touch is broken, whether it is locales, poll, kqueue or even the
5104OpenGL drivers. 5225OpenGL drivers.
5105.PP 5226.PP
5127.PP 5248.PP
5128\fI\f(CI\*(C`select\*(C'\fI is buggy\fR 5249\fI\f(CI\*(C`select\*(C'\fI is buggy\fR
5129.IX Subsection "select is buggy" 5250.IX Subsection "select is buggy"
5130.PP 5251.PP
5131All that's left is \f(CW\*(C`select\*(C'\fR, and of course Apple found a way to fuck this 5252All that's left is \f(CW\*(C`select\*(C'\fR, and of course Apple found a way to fuck this
5132one up as well: On \s-1OS/X\s0, \f(CW\*(C`select\*(C'\fR actively limits the number of file 5253one up as well: On \s-1OS/X, \s0\f(CW\*(C`select\*(C'\fR actively limits the number of file
5133descriptors you can pass in to 1024 \- your program suddenly crashes when 5254descriptors you can pass in to 1024 \- your program suddenly crashes when
5134you use more. 5255you use more.
5135.PP 5256.PP
5136There is an undocumented \*(L"workaround\*(R" for this \- defining 5257There is an undocumented \*(L"workaround\*(R" for this \- defining
5137\&\f(CW\*(C`_DARWIN_UNLIMITED_SELECT\*(C'\fR, which libev tries to use, so select \fIshould\fR 5258\&\f(CW\*(C`_DARWIN_UNLIMITED_SELECT\*(C'\fR, which libev tries to use, so select \fIshould\fR
5138work on \s-1OS/X\s0. 5259work on \s-1OS/X.\s0
5139.SS "\s-1SOLARIS\s0 \s-1PROBLEMS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" 5260.SS "\s-1SOLARIS PROBLEMS AND WORKAROUNDS\s0"
5140.IX Subsection "SOLARIS PROBLEMS AND WORKAROUNDS" 5261.IX Subsection "SOLARIS PROBLEMS AND WORKAROUNDS"
5141\fI\f(CI\*(C`errno\*(C'\fI reentrancy\fR 5262\fI\f(CI\*(C`errno\*(C'\fI reentrancy\fR
5142.IX Subsection "errno reentrancy" 5263.IX Subsection "errno reentrancy"
5143.PP 5264.PP
5144The default compile environment on Solaris is unfortunately so 5265The default compile environment on Solaris is unfortunately so
5161great. 5282great.
5162.PP 5283.PP
5163If you can't get it to work, you can try running the program by setting 5284If you can't get it to work, you can try running the program by setting
5164the environment variable \f(CW\*(C`LIBEV_FLAGS=3\*(C'\fR to only allow \f(CW\*(C`poll\*(C'\fR and 5285the environment variable \f(CW\*(C`LIBEV_FLAGS=3\*(C'\fR to only allow \f(CW\*(C`poll\*(C'\fR and
5165\&\f(CW\*(C`select\*(C'\fR backends. 5286\&\f(CW\*(C`select\*(C'\fR backends.
5166.SS "\s-1AIX\s0 \s-1POLL\s0 \s-1BUG\s0" 5287.SS "\s-1AIX POLL BUG\s0"
5167.IX Subsection "AIX POLL BUG" 5288.IX Subsection "AIX POLL BUG"
5168\&\s-1AIX\s0 unfortunately has a broken \f(CW\*(C`poll.h\*(C'\fR header. Libev works around 5289\&\s-1AIX\s0 unfortunately has a broken \f(CW\*(C`poll.h\*(C'\fR header. Libev works around
5169this by trying to avoid the poll backend altogether (i.e. it's not even 5290this by trying to avoid the poll backend altogether (i.e. it's not even
5170compiled in), which normally isn't a big problem as \f(CW\*(C`select\*(C'\fR works fine 5291compiled in), which normally isn't a big problem as \f(CW\*(C`select\*(C'\fR works fine
5171with large bitsets on \s-1AIX\s0, and \s-1AIX\s0 is dead anyway. 5292with large bitsets on \s-1AIX,\s0 and \s-1AIX\s0 is dead anyway.
5172.SS "\s-1WIN32\s0 \s-1PLATFORM\s0 \s-1LIMITATIONS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" 5293.SS "\s-1WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS\s0"
5173.IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" 5294.IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS"
5174\fIGeneral issues\fR 5295\fIGeneral issues\fR
5175.IX Subsection "General issues" 5296.IX Subsection "General issues"
5176.PP 5297.PP
5177Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev 5298Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev
5246\& #define EV_USE_SELECT 1 5367\& #define EV_USE_SELECT 1
5247\& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ 5368\& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
5248.Ve 5369.Ve
5249.PP 5370.PP
5250Note that winsockets handling of fd sets is O(n), so you can easily get a 5371Note that winsockets handling of fd sets is O(n), so you can easily get a
5251complexity in the O(nA\*^X) range when using win32. 5372complexity in the O(nX) range when using win32.
5252.PP 5373.PP
5253\fILimited number of file descriptors\fR 5374\fILimited number of file descriptors\fR
5254.IX Subsection "Limited number of file descriptors" 5375.IX Subsection "Limited number of file descriptors"
5255.PP 5376.PP
5256Windows has numerous arbitrary (and low) limits on things. 5377Windows has numerous arbitrary (and low) limits on things.
5272by calling \f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR 5393by calling \f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR
5273(another arbitrary limit), but is broken in many versions of the Microsoft 5394(another arbitrary limit), but is broken in many versions of the Microsoft
5274runtime libraries. This might get you to about \f(CW512\fR or \f(CW2048\fR sockets 5395runtime libraries. This might get you to about \f(CW512\fR or \f(CW2048\fR sockets
5275(depending on windows version and/or the phase of the moon). To get more, 5396(depending on windows version and/or the phase of the moon). To get more,
5276you need to wrap all I/O functions and provide your own fd management, but 5397you need to wrap all I/O functions and provide your own fd management, but
5277the cost of calling select (O(nA\*^X)) will likely make this unworkable. 5398the cost of calling select (O(nX)) will likely make this unworkable.
5278.SS "\s-1PORTABILITY\s0 \s-1REQUIREMENTS\s0" 5399.SS "\s-1PORTABILITY REQUIREMENTS\s0"
5279.IX Subsection "PORTABILITY REQUIREMENTS" 5400.IX Subsection "PORTABILITY REQUIREMENTS"
5280In addition to a working ISO-C implementation and of course the 5401In addition to a working ISO-C implementation and of course the
5281backend-specific APIs, libev relies on a few additional extensions: 5402backend-specific APIs, libev relies on a few additional extensions:
5282.ie n .IP """void (*)(ev_watcher_type *, int revents)"" must have compatible calling conventions regardless of ""ev_watcher_type *""." 4 5403.ie n .IP """void (*)(ev_watcher_type *, int revents)"" must have compatible calling conventions regardless of ""ev_watcher_type *""." 4
5283.el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4 5404.el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4
5284.IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *." 5405.IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *."
5285Libev assumes not only that all watcher pointers have the same internal 5406Libev assumes not only that all watcher pointers have the same internal
5286structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO\s0 C for example), but it also 5407structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO C\s0 for example), but it also
5287assumes that the same (machine) code can be used to call any watcher 5408assumes that the same (machine) code can be used to call any watcher
5288callback: The watcher callbacks have different type signatures, but libev 5409callback: The watcher callbacks have different type signatures, but libev
5289calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally. 5410calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally.
5290.IP "pointer accesses must be thread-atomic" 4 5411.IP "pointer accesses must be thread-atomic" 4
5291.IX Item "pointer accesses must be thread-atomic" 5412.IX Item "pointer accesses must be thread-atomic"
5307thread\*(R" or will block signals process-wide, both behaviours would 5428thread\*(R" or will block signals process-wide, both behaviours would
5308be compatible with libev. Interaction between \f(CW\*(C`sigprocmask\*(C'\fR and 5429be compatible with libev. Interaction between \f(CW\*(C`sigprocmask\*(C'\fR and
5309\&\f(CW\*(C`pthread_sigmask\*(C'\fR could complicate things, however. 5430\&\f(CW\*(C`pthread_sigmask\*(C'\fR could complicate things, however.
5310.Sp 5431.Sp
5311The most portable way to handle signals is to block signals in all threads 5432The most portable way to handle signals is to block signals in all threads
5312except the initial one, and run the default loop in the initial thread as 5433except the initial one, and run the signal handling loop in the initial
5313well. 5434thread as well.
5314.ie n .IP """long"" must be large enough for common memory allocation sizes" 4 5435.ie n .IP """long"" must be large enough for common memory allocation sizes" 4
5315.el .IP "\f(CWlong\fR must be large enough for common memory allocation sizes" 4 5436.el .IP "\f(CWlong\fR must be large enough for common memory allocation sizes" 4
5316.IX Item "long must be large enough for common memory allocation sizes" 5437.IX Item "long must be large enough for common memory allocation sizes"
5317To improve portability and simplify its \s-1API\s0, libev uses \f(CW\*(C`long\*(C'\fR internally 5438To improve portability and simplify its \s-1API,\s0 libev uses \f(CW\*(C`long\*(C'\fR internally
5318instead of \f(CW\*(C`size_t\*(C'\fR when allocating its data structures. On non-POSIX 5439instead of \f(CW\*(C`size_t\*(C'\fR when allocating its data structures. On non-POSIX
5319systems (Microsoft...) this might be unexpectedly low, but is still at 5440systems (Microsoft...) this might be unexpectedly low, but is still at
5320least 31 bits everywhere, which is enough for hundreds of millions of 5441least 31 bits everywhere, which is enough for hundreds of millions of
5321watchers. 5442watchers.
5322.ie n .IP """double"" must hold a time value in seconds with enough accuracy" 4 5443.ie n .IP """double"" must hold a time value in seconds with enough accuracy" 4
5324.IX Item "double must hold a time value in seconds with enough accuracy" 5445.IX Item "double must hold a time value in seconds with enough accuracy"
5325The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to 5446The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to
5326have at least 51 bits of mantissa (and 9 bits of exponent), which is 5447have at least 51 bits of mantissa (and 9 bits of exponent), which is
5327good enough for at least into the year 4000 with millisecond accuracy 5448good enough for at least into the year 4000 with millisecond accuracy
5328(the design goal for libev). This requirement is overfulfilled by 5449(the design goal for libev). This requirement is overfulfilled by
5329implementations using \s-1IEEE\s0 754, which is basically all existing ones. 5450implementations using \s-1IEEE 754,\s0 which is basically all existing ones.
5330.Sp 5451.Sp
5331With \s-1IEEE\s0 754 doubles, you get microsecond accuracy until at least the 5452With \s-1IEEE 754\s0 doubles, you get microsecond accuracy until at least the
5332year 2255 (and millisecond accuracy till the year 287396 \- by then, libev 5453year 2255 (and millisecond accuracy till the year 287396 \- by then, libev
5333is either obsolete or somebody patched it to use \f(CW\*(C`long double\*(C'\fR or 5454is either obsolete or somebody patched it to use \f(CW\*(C`long double\*(C'\fR or
5334something like that, just kidding). 5455something like that, just kidding).
5335.PP 5456.PP
5336If you know of other additional requirements drop me a note. 5457If you know of other additional requirements drop me a note.
5398calls in the current loop iteration and the loop is currently 5519calls in the current loop iteration and the loop is currently
5399blocked. Checking for async and signal events involves iterating over all 5520blocked. Checking for async and signal events involves iterating over all
5400running async watchers or all signal numbers. 5521running async watchers or all signal numbers.
5401.SH "PORTING FROM LIBEV 3.X TO 4.X" 5522.SH "PORTING FROM LIBEV 3.X TO 4.X"
5402.IX Header "PORTING FROM LIBEV 3.X TO 4.X" 5523.IX Header "PORTING FROM LIBEV 3.X TO 4.X"
5403The major version 4 introduced some incompatible changes to the \s-1API\s0. 5524The major version 4 introduced some incompatible changes to the \s-1API.\s0
5404.PP 5525.PP
5405At the moment, the \f(CW\*(C`ev.h\*(C'\fR header file provides compatibility definitions 5526At the moment, the \f(CW\*(C`ev.h\*(C'\fR header file provides compatibility definitions
5406for all changes, so most programs should still compile. The compatibility 5527for all changes, so most programs should still compile. The compatibility
5407layer might be removed in later versions of libev, so better update to the 5528layer might be removed in later versions of libev, so better update to the
5408new \s-1API\s0 early than late. 5529new \s-1API\s0 early than late.
5409.ie n .IP """EV_COMPAT3"" backwards compatibility mechanism" 4 5530.ie n .IP """EV_COMPAT3"" backwards compatibility mechanism" 4
5410.el .IP "\f(CWEV_COMPAT3\fR backwards compatibility mechanism" 4 5531.el .IP "\f(CWEV_COMPAT3\fR backwards compatibility mechanism" 4
5411.IX Item "EV_COMPAT3 backwards compatibility mechanism" 5532.IX Item "EV_COMPAT3 backwards compatibility mechanism"
5412The backward compatibility mechanism can be controlled by 5533The backward compatibility mechanism can be controlled by
5413\&\f(CW\*(C`EV_COMPAT3\*(C'\fR. See \*(L"\s-1MACROS\s0\*(R" in \s-1PREPROCESSOR\s0 \s-1SYMBOLS\s0 in the \s-1EMBEDDING\s0 5534\&\f(CW\*(C`EV_COMPAT3\*(C'\fR. See \*(L"\s-1PREPROCESSOR SYMBOLS/MACROS\*(R"\s0 in the \*(L"\s-1EMBEDDING\*(R"\s0
5414section. 5535section.
5415.ie n .IP """ev_default_destroy"" and ""ev_default_fork"" have been removed" 4 5536.ie n .IP """ev_default_destroy"" and ""ev_default_fork"" have been removed" 4
5416.el .IP "\f(CWev_default_destroy\fR and \f(CWev_default_fork\fR have been removed" 4 5537.el .IP "\f(CWev_default_destroy\fR and \f(CWev_default_fork\fR have been removed" 4
5417.IX Item "ev_default_destroy and ev_default_fork have been removed" 5538.IX Item "ev_default_destroy and ev_default_fork have been removed"
5418These calls can be replaced easily by their \f(CW\*(C`ev_loop_xxx\*(C'\fR counterparts: 5539These calls can be replaced easily by their \f(CW\*(C`ev_loop_xxx\*(C'\fR counterparts:
5458.SH "GLOSSARY" 5579.SH "GLOSSARY"
5459.IX Header "GLOSSARY" 5580.IX Header "GLOSSARY"
5460.IP "active" 4 5581.IP "active" 4
5461.IX Item "active" 5582.IX Item "active"
5462A watcher is active as long as it has been started and not yet stopped. 5583A watcher is active as long as it has been started and not yet stopped.
5463See \*(L"\s-1WATCHER\s0 \s-1STATES\s0\*(R" for details. 5584See \*(L"\s-1WATCHER STATES\*(R"\s0 for details.
5464.IP "application" 4 5585.IP "application" 4
5465.IX Item "application" 5586.IX Item "application"
5466In this document, an application is whatever is using libev. 5587In this document, an application is whatever is using libev.
5467.IP "backend" 4 5588.IP "backend" 4
5468.IX Item "backend" 5589.IX Item "backend"
5495The model used to describe how an event loop handles and processes 5616The model used to describe how an event loop handles and processes
5496watchers and events. 5617watchers and events.
5497.IP "pending" 4 5618.IP "pending" 4
5498.IX Item "pending" 5619.IX Item "pending"
5499A watcher is pending as soon as the corresponding event has been 5620A watcher is pending as soon as the corresponding event has been
5500detected. See \*(L"\s-1WATCHER\s0 \s-1STATES\s0\*(R" for details. 5621detected. See \*(L"\s-1WATCHER STATES\*(R"\s0 for details.
5501.IP "real time" 4 5622.IP "real time" 4
5502.IX Item "real time" 5623.IX Item "real time"
5503The physical time that is observed. It is apparently strictly monotonic :) 5624The physical time that is observed. It is apparently strictly monotonic :)
5504.IP "wall-clock time" 4 5625.IP "wall-clock time" 4
5505.IX Item "wall-clock time" 5626.IX Item "wall-clock time"

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