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Revision 1.83 by root, Wed Dec 12 17:55:31 2007 UTC vs.
Revision 1.92 by root, Fri Dec 21 01:26:04 2007 UTC

53The newest version of this document is also available as a html-formatted 53The newest version of this document is also available as a html-formatted
54web page you might find easier to navigate when reading it for the first 54web page you might find easier to navigate when reading it for the first
55time: L<http://cvs.schmorp.de/libev/ev.html>. 55time: L<http://cvs.schmorp.de/libev/ev.html>.
56 56
57Libev is an event loop: you register interest in certain events (such as a 57Libev is an event loop: you register interest in certain events (such as a
58file descriptor being readable or a timeout occuring), and it will manage 58file descriptor being readable or a timeout occurring), and it will manage
59these event sources and provide your program with events. 59these event sources and provide your program with events.
60 60
61To do this, it must take more or less complete control over your process 61To do this, it must take more or less complete control over your process
62(or thread) by executing the I<event loop> handler, and will then 62(or thread) by executing the I<event loop> handler, and will then
63communicate events via a callback mechanism. 63communicate events via a callback mechanism.
98Libev represents time as a single floating point number, representing the 98Libev represents time as a single floating point number, representing the
99(fractional) number of seconds since the (POSIX) epoch (somewhere near 99(fractional) number of seconds since the (POSIX) epoch (somewhere near
100the beginning of 1970, details are complicated, don't ask). This type is 100the beginning of 1970, details are complicated, don't ask). This type is
101called C<ev_tstamp>, which is what you should use too. It usually aliases 101called C<ev_tstamp>, which is what you should use too. It usually aliases
102to the C<double> type in C, and when you need to do any calculations on 102to the C<double> type in C, and when you need to do any calculations on
103it, you should treat it as such. 103it, you should treat it as some floatingpoint value. Unlike the name
104component C<stamp> might indicate, it is also used for time differences
105throughout libev.
104 106
105=head1 GLOBAL FUNCTIONS 107=head1 GLOBAL FUNCTIONS
106 108
107These functions can be called anytime, even before initialising the 109These functions can be called anytime, even before initialising the
108library in any way. 110library in any way.
329 331
330=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) 332=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)
331 333
332Kqueue deserves special mention, as at the time of this writing, it 334Kqueue deserves special mention, as at the time of this writing, it
333was broken on all BSDs except NetBSD (usually it doesn't work with 335was broken on all BSDs except NetBSD (usually it doesn't work with
334anything but sockets and pipes, except on Darwin, where of course its 336anything but sockets and pipes, except on Darwin, where of course it's
335completely useless). For this reason its not being "autodetected" 337completely useless). For this reason it's not being "autodetected"
336unless you explicitly specify it explicitly in the flags (i.e. using 338unless you explicitly specify it explicitly in the flags (i.e. using
337C<EVBACKEND_KQUEUE>). 339C<EVBACKEND_KQUEUE>).
338 340
339It scales in the same way as the epoll backend, but the interface to the 341It scales in the same way as the epoll backend, but the interface to the
340kernel is more efficient (which says nothing about its actual speed, of 342kernel is more efficient (which says nothing about its actual speed, of
402Destroys the default loop again (frees all memory and kernel state 404Destroys the default loop again (frees all memory and kernel state
403etc.). None of the active event watchers will be stopped in the normal 405etc.). None of the active event watchers will be stopped in the normal
404sense, so e.g. C<ev_is_active> might still return true. It is your 406sense, so e.g. C<ev_is_active> might still return true. It is your
405responsibility to either stop all watchers cleanly yoursef I<before> 407responsibility to either stop all watchers cleanly yoursef I<before>
406calling this function, or cope with the fact afterwards (which is usually 408calling this function, or cope with the fact afterwards (which is usually
407the easiest thing, youc na just ignore the watchers and/or C<free ()> them 409the easiest thing, you can just ignore the watchers and/or C<free ()> them
408for example). 410for example).
411
412Note that certain global state, such as signal state, will not be freed by
413this function, and related watchers (such as signal and child watchers)
414would need to be stopped manually.
415
416In general it is not advisable to call this function except in the
417rare occasion where you really need to free e.g. the signal handling
418pipe fds. If you need dynamically allocated loops it is better to use
419C<ev_loop_new> and C<ev_loop_destroy>).
409 420
410=item ev_loop_destroy (loop) 421=item ev_loop_destroy (loop)
411 422
412Like C<ev_default_destroy>, but destroys an event loop created by an 423Like C<ev_default_destroy>, but destroys an event loop created by an
413earlier call to C<ev_loop_new>. 424earlier call to C<ev_loop_new>.
458 469
459Returns the current "event loop time", which is the time the event loop 470Returns the current "event loop time", which is the time the event loop
460received events and started processing them. This timestamp does not 471received events and started processing them. This timestamp does not
461change as long as callbacks are being processed, and this is also the base 472change as long as callbacks are being processed, and this is also the base
462time used for relative timers. You can treat it as the timestamp of the 473time used for relative timers. You can treat it as the timestamp of the
463event occuring (or more correctly, libev finding out about it). 474event occurring (or more correctly, libev finding out about it).
464 475
465=item ev_loop (loop, int flags) 476=item ev_loop (loop, int flags)
466 477
467Finally, this is it, the event handler. This function usually is called 478Finally, this is it, the event handler. This function usually is called
468after you initialised all your watchers and you want to start handling 479after you initialised all your watchers and you want to start handling
1220 1231
1221The current reschedule callback, or C<0>, if this functionality is 1232The current reschedule callback, or C<0>, if this functionality is
1222switched off. Can be changed any time, but changes only take effect when 1233switched off. Can be changed any time, but changes only take effect when
1223the periodic timer fires or C<ev_periodic_again> is being called. 1234the periodic timer fires or C<ev_periodic_again> is being called.
1224 1235
1236=item ev_tstamp at [read-only]
1237
1238When active, contains the absolute time that the watcher is supposed to
1239trigger next.
1240
1225=back 1241=back
1226 1242
1227Example: Call a callback every hour, or, more precisely, whenever the 1243Example: Call a callback every hour, or, more precisely, whenever the
1228system clock is divisible by 3600. The callback invocation times have 1244system clock is divisible by 3600. The callback invocation times have
1229potentially a lot of jittering, but good long-term stability. 1245potentially a lot of jittering, but good long-term stability.
1775 1791
1776Make a single, non-blocking sweep over the embedded loop. This works 1792Make a single, non-blocking sweep over the embedded loop. This works
1777similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most 1793similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
1778apropriate way for embedded loops. 1794apropriate way for embedded loops.
1779 1795
1780=item struct ev_loop *loop [read-only] 1796=item struct ev_loop *other [read-only]
1781 1797
1782The embedded event loop. 1798The embedded event loop.
1783 1799
1784=back 1800=back
1785 1801
2019 2035
2020=item w->stop () 2036=item w->stop ()
2021 2037
2022Stops the watcher if it is active. Again, no C<loop> argument. 2038Stops the watcher if it is active. Again, no C<loop> argument.
2023 2039
2024=item w->again () C<ev::timer>, C<ev::periodic> only 2040=item w->again () (C<ev::timer>, C<ev::periodic> only)
2025 2041
2026For C<ev::timer> and C<ev::periodic>, this invokes the corresponding 2042For C<ev::timer> and C<ev::periodic>, this invokes the corresponding
2027C<ev_TYPE_again> function. 2043C<ev_TYPE_again> function.
2028 2044
2029=item w->sweep () C<ev::embed> only 2045=item w->sweep () (C<ev::embed> only)
2030 2046
2031Invokes C<ev_embed_sweep>. 2047Invokes C<ev_embed_sweep>.
2032 2048
2033=item w->update () C<ev::stat> only 2049=item w->update () (C<ev::stat> only)
2034 2050
2035Invokes C<ev_stat_stat>. 2051Invokes C<ev_stat_stat>.
2036 2052
2037=back 2053=back
2038 2054
2058 } 2074 }
2059 2075
2060 2076
2061=head1 MACRO MAGIC 2077=head1 MACRO MAGIC
2062 2078
2063Libev can be compiled with a variety of options, the most fundemantal is 2079Libev can be compiled with a variety of options, the most fundamantal
2064C<EV_MULTIPLICITY>. This option determines whether (most) functions and 2080of which is C<EV_MULTIPLICITY>. This option determines whether (most)
2065callbacks have an initial C<struct ev_loop *> argument. 2081functions and callbacks have an initial C<struct ev_loop *> argument.
2066 2082
2067To make it easier to write programs that cope with either variant, the 2083To make it easier to write programs that cope with either variant, the
2068following macros are defined: 2084following macros are defined:
2069 2085
2070=over 4 2086=over 4
2124Libev can (and often is) directly embedded into host 2140Libev can (and often is) directly embedded into host
2125applications. Examples of applications that embed it include the Deliantra 2141applications. Examples of applications that embed it include the Deliantra
2126Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) 2142Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
2127and rxvt-unicode. 2143and rxvt-unicode.
2128 2144
2129The goal is to enable you to just copy the neecssary files into your 2145The goal is to enable you to just copy the necessary files into your
2130source directory without having to change even a single line in them, so 2146source directory without having to change even a single line in them, so
2131you can easily upgrade by simply copying (or having a checked-out copy of 2147you can easily upgrade by simply copying (or having a checked-out copy of
2132libev somewhere in your source tree). 2148libev somewhere in your source tree).
2133 2149
2134=head2 FILESETS 2150=head2 FILESETS
2224 2240
2225If defined to be C<1>, libev will try to detect the availability of the 2241If defined to be C<1>, libev will try to detect the availability of the
2226monotonic clock option at both compiletime and runtime. Otherwise no use 2242monotonic clock option at both compiletime and runtime. Otherwise no use
2227of the monotonic clock option will be attempted. If you enable this, you 2243of the monotonic clock option will be attempted. If you enable this, you
2228usually have to link against librt or something similar. Enabling it when 2244usually have to link against librt or something similar. Enabling it when
2229the functionality isn't available is safe, though, althoguh you have 2245the functionality isn't available is safe, though, although you have
2230to make sure you link against any libraries where the C<clock_gettime> 2246to make sure you link against any libraries where the C<clock_gettime>
2231function is hiding in (often F<-lrt>). 2247function is hiding in (often F<-lrt>).
2232 2248
2233=item EV_USE_REALTIME 2249=item EV_USE_REALTIME
2234 2250
2235If defined to be C<1>, libev will try to detect the availability of the 2251If defined to be C<1>, libev will try to detect the availability of the
2236realtime clock option at compiletime (and assume its availability at 2252realtime clock option at compiletime (and assume its availability at
2237runtime if successful). Otherwise no use of the realtime clock option will 2253runtime if successful). Otherwise no use of the realtime clock option will
2238be attempted. This effectively replaces C<gettimeofday> by C<clock_get 2254be attempted. This effectively replaces C<gettimeofday> by C<clock_get
2239(CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries 2255(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
2240in the description of C<EV_USE_MONOTONIC>, though. 2256note about libraries in the description of C<EV_USE_MONOTONIC>, though.
2241 2257
2242=item EV_USE_SELECT 2258=item EV_USE_SELECT
2243 2259
2244If undefined or defined to be C<1>, libev will compile in support for the 2260If undefined or defined to be C<1>, libev will compile in support for the
2245C<select>(2) backend. No attempt at autodetection will be done: if no 2261C<select>(2) backend. No attempt at autodetection will be done: if no
2424 2440
2425=item ev_set_cb (ev, cb) 2441=item ev_set_cb (ev, cb)
2426 2442
2427Can be used to change the callback member declaration in each watcher, 2443Can be used to change the callback member declaration in each watcher,
2428and the way callbacks are invoked and set. Must expand to a struct member 2444and the way callbacks are invoked and set. Must expand to a struct member
2429definition and a statement, respectively. See the F<ev.v> header file for 2445definition and a statement, respectively. See the F<ev.c> header file for
2430their default definitions. One possible use for overriding these is to 2446their default definitions. One possible use for overriding these is to
2431avoid the C<struct ev_loop *> as first argument in all cases, or to use 2447avoid the C<struct ev_loop *> as first argument in all cases, or to use
2432method calls instead of plain function calls in C++. 2448method calls instead of plain function calls in C++.
2449
2450=head2 EXPORTED API SYMBOLS
2451
2452If you need to re-export the API (e.g. via a dll) and you need a list of
2453exported symbols, you can use the provided F<Symbol.*> files which list
2454all public symbols, one per line:
2455
2456 Symbols.ev for libev proper
2457 Symbols.event for the libevent emulation
2458
2459This can also be used to rename all public symbols to avoid clashes with
2460multiple versions of libev linked together (which is obviously bad in
2461itself, but sometimes it is inconvinient to avoid this).
2462
2463A sed command like this will create wrapper C<#define>'s that you need to
2464include before including F<ev.h>:
2465
2466 <Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
2467
2468This would create a file F<wrap.h> which essentially looks like this:
2469
2470 #define ev_backend myprefix_ev_backend
2471 #define ev_check_start myprefix_ev_check_start
2472 #define ev_check_stop myprefix_ev_check_stop
2473 ...
2433 2474
2434=head2 EXAMPLES 2475=head2 EXAMPLES
2435 2476
2436For a real-world example of a program the includes libev 2477For a real-world example of a program the includes libev
2437verbatim, you can have a look at the EV perl module 2478verbatim, you can have a look at the EV perl module

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