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Revision 1.82 by root, Wed Dec 12 17:55:06 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
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
1792event loop blocks next and before C<ev_check> watchers are being called, 1808event loop blocks next and before C<ev_check> watchers are being called,
1793and only in the child after the fork. If whoever good citizen calling 1809and only in the child after the fork. If whoever good citizen calling
1794C<ev_default_fork> cheats and calls it in the wrong process, the fork 1810C<ev_default_fork> cheats and calls it in the wrong process, the fork
1795handlers will be invoked, too, of course. 1811handlers will be invoked, too, of course.
1796 1812
1813=head3 Watcher-Specific Functions and Data Members
1814
1797=over 4 1815=over 4
1798 1816
1799=item ev_fork_init (ev_signal *, callback) 1817=item ev_fork_init (ev_signal *, callback)
1800 1818
1801Initialises and configures the fork watcher - it has no parameters of any 1819Initialises and configures the fork watcher - it has no parameters of any
2017 2035
2018=item w->stop () 2036=item w->stop ()
2019 2037
2020Stops the watcher if it is active. Again, no C<loop> argument. 2038Stops the watcher if it is active. Again, no C<loop> argument.
2021 2039
2022=item w->again () C<ev::timer>, C<ev::periodic> only 2040=item w->again () (C<ev::timer>, C<ev::periodic> only)
2023 2041
2024For C<ev::timer> and C<ev::periodic>, this invokes the corresponding 2042For C<ev::timer> and C<ev::periodic>, this invokes the corresponding
2025C<ev_TYPE_again> function. 2043C<ev_TYPE_again> function.
2026 2044
2027=item w->sweep () C<ev::embed> only 2045=item w->sweep () (C<ev::embed> only)
2028 2046
2029Invokes C<ev_embed_sweep>. 2047Invokes C<ev_embed_sweep>.
2030 2048
2031=item w->update () C<ev::stat> only 2049=item w->update () (C<ev::stat> only)
2032 2050
2033Invokes C<ev_stat_stat>. 2051Invokes C<ev_stat_stat>.
2034 2052
2035=back 2053=back
2036 2054
2056 } 2074 }
2057 2075
2058 2076
2059=head1 MACRO MAGIC 2077=head1 MACRO MAGIC
2060 2078
2061Libev can be compiled with a variety of options, the most fundemantal is 2079Libev can be compiled with a variety of options, the most fundamantal
2062C<EV_MULTIPLICITY>. This option determines whether (most) functions and 2080of which is C<EV_MULTIPLICITY>. This option determines whether (most)
2063callbacks have an initial C<struct ev_loop *> argument. 2081functions and callbacks have an initial C<struct ev_loop *> argument.
2064 2082
2065To 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
2066following macros are defined: 2084following macros are defined:
2067 2085
2068=over 4 2086=over 4
2122Libev can (and often is) directly embedded into host 2140Libev can (and often is) directly embedded into host
2123applications. Examples of applications that embed it include the Deliantra 2141applications. Examples of applications that embed it include the Deliantra
2124Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) 2142Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
2125and rxvt-unicode. 2143and rxvt-unicode.
2126 2144
2127The 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
2128source 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
2129you 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
2130libev somewhere in your source tree). 2148libev somewhere in your source tree).
2131 2149
2132=head2 FILESETS 2150=head2 FILESETS
2222 2240
2223If 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
2224monotonic clock option at both compiletime and runtime. Otherwise no use 2242monotonic clock option at both compiletime and runtime. Otherwise no use
2225of 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
2226usually have to link against librt or something similar. Enabling it when 2244usually have to link against librt or something similar. Enabling it when
2227the functionality isn't available is safe, though, althoguh you have 2245the functionality isn't available is safe, though, although you have
2228to 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>
2229function is hiding in (often F<-lrt>). 2247function is hiding in (often F<-lrt>).
2230 2248
2231=item EV_USE_REALTIME 2249=item EV_USE_REALTIME
2232 2250
2233If 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
2234realtime clock option at compiletime (and assume its availability at 2252realtime clock option at compiletime (and assume its availability at
2235runtime if successful). Otherwise no use of the realtime clock option will 2253runtime if successful). Otherwise no use of the realtime clock option will
2236be attempted. This effectively replaces C<gettimeofday> by C<clock_get 2254be attempted. This effectively replaces C<gettimeofday> by C<clock_get
2237(CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries 2255(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
2238in the description of C<EV_USE_MONOTONIC>, though. 2256note about libraries in the description of C<EV_USE_MONOTONIC>, though.
2239 2257
2240=item EV_USE_SELECT 2258=item EV_USE_SELECT
2241 2259
2242If 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
2243C<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
2422 2440
2423=item ev_set_cb (ev, cb) 2441=item ev_set_cb (ev, cb)
2424 2442
2425Can be used to change the callback member declaration in each watcher, 2443Can be used to change the callback member declaration in each watcher,
2426and 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
2427definition 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
2428their default definitions. One possible use for overriding these is to 2446their default definitions. One possible use for overriding these is to
2429avoid 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
2430method 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 ...
2431 2474
2432=head2 EXAMPLES 2475=head2 EXAMPLES
2433 2476
2434For a real-world example of a program the includes libev 2477For a real-world example of a program the includes libev
2435verbatim, 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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