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Revision 1.85 by root, Mon Dec 17 07:24:12 2007 UTC vs.
Revision 1.93 by root, Fri Dec 21 01:29:34 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
1780 1791
1781Make a single, non-blocking sweep over the embedded loop. This works 1792Make a single, non-blocking sweep over the embedded loop. This works
1782similarly 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
1783apropriate way for embedded loops. 1794apropriate way for embedded loops.
1784 1795
1785=item struct ev_loop *loop [read-only] 1796=item struct ev_loop *other [read-only]
1786 1797
1787The embedded event loop. 1798The embedded event loop.
1788 1799
1789=back 1800=back
1790 1801
2129Libev can (and often is) directly embedded into host 2140Libev can (and often is) directly embedded into host
2130applications. Examples of applications that embed it include the Deliantra 2141applications. Examples of applications that embed it include the Deliantra
2131Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) 2142Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
2132and rxvt-unicode. 2143and rxvt-unicode.
2133 2144
2134The 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
2135source 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
2136you 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
2137libev somewhere in your source tree). 2148libev somewhere in your source tree).
2138 2149
2139=head2 FILESETS 2150=head2 FILESETS
2229 2240
2230If 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
2231monotonic clock option at both compiletime and runtime. Otherwise no use 2242monotonic clock option at both compiletime and runtime. Otherwise no use
2232of 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
2233usually have to link against librt or something similar. Enabling it when 2244usually have to link against librt or something similar. Enabling it when
2234the functionality isn't available is safe, though, althoguh you have 2245the functionality isn't available is safe, though, although you have
2235to 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>
2236function is hiding in (often F<-lrt>). 2247function is hiding in (often F<-lrt>).
2237 2248
2238=item EV_USE_REALTIME 2249=item EV_USE_REALTIME
2239 2250
2240If 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
2241realtime clock option at compiletime (and assume its availability at 2252realtime clock option at compiletime (and assume its availability at
2242runtime if successful). Otherwise no use of the realtime clock option will 2253runtime if successful). Otherwise no use of the realtime clock option will
2243be attempted. This effectively replaces C<gettimeofday> by C<clock_get 2254be attempted. This effectively replaces C<gettimeofday> by C<clock_get
2244(CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries 2255(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
2245in the description of C<EV_USE_MONOTONIC>, though. 2256note about libraries in the description of C<EV_USE_MONOTONIC>, though.
2246 2257
2247=item EV_USE_SELECT 2258=item EV_USE_SELECT
2248 2259
2249If 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
2250C<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
2429 2440
2430=item ev_set_cb (ev, cb) 2441=item ev_set_cb (ev, cb)
2431 2442
2432Can be used to change the callback member declaration in each watcher, 2443Can be used to change the callback member declaration in each watcher,
2433and 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
2434definition and a statement, respectively. See the F<ev.v> header file for 2445definition and a statement, respectively. See the F<ev.h> header file for
2435their default definitions. One possible use for overriding these is to 2446their default definitions. One possible use for overriding these is to
2436avoid 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
2437method 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 ...
2438 2474
2439=head2 EXAMPLES 2475=head2 EXAMPLES
2440 2476
2441For a real-world example of a program the includes libev 2477For a real-world example of a program the includes libev
2442verbatim, 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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