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54.\" 46.\"
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56.\" titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and index 48.\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index
57.\" entries marked with X<> in POD. Of course, you'll have to process the 49.\" entries marked with X<> in POD. Of course, you'll have to process the
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130.\} 122.\}
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132.\" ======================================================================== 124.\" ========================================================================
133.\" 125.\"
134.IX Title "LIBEV 3" 126.IX Title "LIBEV 3"
135.TH LIBEV 3 "2009-04-25" "libev-3.6" "libev - high performance full featured event loop" 127.TH LIBEV 3 "2009-07-27" "libev-3.8" "libev - high performance full featured event loop"
136.\" For nroff, turn off justification. Always turn off hyphenation; it makes 128.\" For nroff, turn off justification. Always turn off hyphenation; it makes
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138.if n .ad l 130.if n .ad l
139.nh 131.nh
140.SH "NAME" 132.SH "NAME"
… …
142.SH "SYNOPSIS" 134.SH "SYNOPSIS"
143.IX Header "SYNOPSIS" 135.IX Header "SYNOPSIS"
144.Vb 1 136.Vb 1
145\& #include <ev.h> 137\& #include <ev.h>
146.Ve 138.Ve
147.Sh "\s-1EXAMPLE\s0 \s-1PROGRAM\s0" 139.SS "\s-1EXAMPLE\s0 \s-1PROGRAM\s0"
148.IX Subsection "EXAMPLE PROGRAM" 140.IX Subsection "EXAMPLE PROGRAM"
149.Vb 2 141.Vb 2
150\& // a single header file is required 142\& // a single header file is required
151\& #include <ev.h> 143\& #include <ev.h>
152\& 144\&
… …
230.PP 222.PP
231You register interest in certain events by registering so-called \fIevent 223You register interest in certain events by registering so-called \fIevent
232watchers\fR, which are relatively small C structures you initialise with the 224watchers\fR, which are relatively small C structures you initialise with the
233details of the event, and then hand it over to libev by \fIstarting\fR the 225details of the event, and then hand it over to libev by \fIstarting\fR the
234watcher. 226watcher.
235.Sh "\s-1FEATURES\s0" 227.SS "\s-1FEATURES\s0"
236.IX Subsection "FEATURES" 228.IX Subsection "FEATURES"
237Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific \f(CW\*(C`epoll\*(C'\fR, the 229Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific \f(CW\*(C`epoll\*(C'\fR, the
238BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms 230BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms
239for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface 231for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface
240(for \f(CW\*(C`ev_stat\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers 232(for \f(CW\*(C`ev_stat\*(C'\fR), Linux eventfd/signalfd (for faster and cleaner
241with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals 233inter-thread wakeup (\f(CW\*(C`ev_async\*(C'\fR)/signal handling (\f(CW\*(C`ev_signal\*(C'\fR)) relative
242(\f(CW\*(C`ev_signal\*(C'\fR), process status change events (\f(CW\*(C`ev_child\*(C'\fR), and event 234timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers with customised rescheduling
243watchers dealing with the event loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR, 235(\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals (\f(CW\*(C`ev_signal\*(C'\fR), process status
244\&\f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR watchers) as well as 236change events (\f(CW\*(C`ev_child\*(C'\fR), and event watchers dealing with the event
245file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events 237loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR, \f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and
246(\f(CW\*(C`ev_fork\*(C'\fR). 238\&\f(CW\*(C`ev_check\*(C'\fR watchers) as well as file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even
239limited support for fork events (\f(CW\*(C`ev_fork\*(C'\fR).
247.PP 240.PP
248It also is quite fast (see this 241It also is quite fast (see this
249benchmark comparing it to libevent 242<benchmark> comparing it to libevent
250for example). 243for example).
251.Sh "\s-1CONVENTIONS\s0" 244.SS "\s-1CONVENTIONS\s0"
252.IX Subsection "CONVENTIONS" 245.IX Subsection "CONVENTIONS"
253Libev is very configurable. In this manual the default (and most common) 246Libev is very configurable. In this manual the default (and most common)
254configuration will be described, which supports multiple event loops. For 247configuration will be described, which supports multiple event loops. For
255more info about various configuration options please have a look at 248more 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 249\&\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 250for 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`ev_loop *\*(C'\fR) will not have 251name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`ev_loop *\*(C'\fR) will not have
259this argument. 252this argument.
260.Sh "\s-1TIME\s0 \s-1REPRESENTATION\s0" 253.SS "\s-1TIME\s0 \s-1REPRESENTATION\s0"
261.IX Subsection "TIME REPRESENTATION" 254.IX Subsection "TIME REPRESENTATION"
262Libev represents time as a single floating point number, representing 255Libev represents time as a single floating point number, representing
263the (fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere 256the (fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere
264near the beginning of 1970, details are complicated, don't ask). This 257near the beginning of 1970, details are complicated, don't ask). This
265type is called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually 258type is called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually
… …
486forget about forgetting to tell libev about forking) when you use this 479forget about forgetting to tell libev about forking) when you use this
487flag. 480flag.
488.Sp 481.Sp
489This flag setting cannot be overridden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR 482This flag setting cannot be overridden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR
490environment variable. 483environment variable.
484.ie n .IP """EVFLAG_NOINOTIFY""" 4
485.el .IP "\f(CWEVFLAG_NOINOTIFY\fR" 4
486.IX Item "EVFLAG_NOINOTIFY"
487When this flag is specified, then libev will not attempt to use the
488\&\fIinotify\fR \s-1API\s0 for it's \f(CW\*(C`ev_stat\*(C'\fR watchers. Apart from debugging and
489testing, this flag can be useful to conserve inotify file descriptors, as
490otherwise each loop using \f(CW\*(C`ev_stat\*(C'\fR watchers consumes one inotify handle.
491.ie n .IP """EVFLAG_NOSIGNALFD""" 4
492.el .IP "\f(CWEVFLAG_NOSIGNALFD\fR" 4
493.IX Item "EVFLAG_NOSIGNALFD"
494When this flag is specified, then libev will not attempt to use the
495\&\fIsignalfd\fR \s-1API\s0 for it's \f(CW\*(C`ev_signal\*(C'\fR (and \f(CW\*(C`ev_child\*(C'\fR) watchers. This is
496probably only useful to work around any bugs in libev. Consequently, this
497flag might go away once the signalfd functionality is considered stable,
498so it's useful mostly in environment variables and not in program code.
491.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 499.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4
492.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 500.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4
493.IX Item "EVBACKEND_SELECT (value 1, portable select backend)" 501.IX Item "EVBACKEND_SELECT (value 1, portable select backend)"
494This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as 502This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as
495libev tries to roll its own fd_set with no limits on the number of fds, 503libev tries to roll its own fd_set with no limits on the number of fds,
… …
643.Sp 651.Sp
644It is definitely not recommended to use this flag. 652It is definitely not recommended to use this flag.
645.RE 653.RE
646.RS 4 654.RS 4
647.Sp 655.Sp
648If one or more of these are or'ed into the flags value, then only these 656If one or more of the backend flags are or'ed into the flags value,
649backends will be tried (in the reverse order as listed here). If none are 657then only these backends will be tried (in the reverse order as listed
650specified, all backends in \f(CW\*(C`ev_recommended_backends ()\*(C'\fR will be tried. 658here). If none are specified, all backends in \f(CW\*(C`ev_recommended_backends
659()\*(C'\fR will be tried.
651.Sp 660.Sp
652Example: This is the most typical usage. 661Example: This is the most typical usage.
653.Sp 662.Sp
654.Vb 2 663.Vb 2
655\& if (!ev_default_loop (0)) 664\& if (!ev_default_loop (0))
… …
749happily wraps around with enough iterations. 758happily wraps around with enough iterations.
750.Sp 759.Sp
751This value can sometimes be useful as a generation counter of sorts (it 760This value can sometimes be useful as a generation counter of sorts (it
752\&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with 761\&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with
753\&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls. 762\&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls.
763.IP "unsigned int ev_loop_depth (loop)" 4
764.IX Item "unsigned int ev_loop_depth (loop)"
765Returns the number of times \f(CW\*(C`ev_loop\*(C'\fR was entered minus the number of
766times \f(CW\*(C`ev_loop\*(C'\fR was exited, in other words, the recursion depth.
767.Sp
768Outside \f(CW\*(C`ev_loop\*(C'\fR, this number is zero. In a callback, this number is
769\&\f(CW1\fR, unless \f(CW\*(C`ev_loop\*(C'\fR was invoked recursively (or from another thread),
770in which case it is higher.
771.Sp
772Leaving \f(CW\*(C`ev_loop\*(C'\fR abnormally (setjmp/longjmp, cancelling the thread
773etc.), doesn't count as exit.
754.IP "unsigned int ev_backend (loop)" 4 774.IP "unsigned int ev_backend (loop)" 4
755.IX Item "unsigned int ev_backend (loop)" 775.IX Item "unsigned int ev_backend (loop)"
756Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in 776Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in
757use. 777use.
758.IP "ev_tstamp ev_now (loop)" 4 778.IP "ev_tstamp ev_now (loop)" 4
… …
946.Sp 966.Sp
947By setting a higher \fIio collect interval\fR you allow libev to spend more 967By setting a higher \fIio collect interval\fR you allow libev to spend more
948time collecting I/O events, so you can handle more events per iteration, 968time collecting I/O events, so you can handle more events per iteration,
949at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and 969at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and
950\&\f(CW\*(C`ev_timer\*(C'\fR) will be not affected. Setting this to a non-null value will 970\&\f(CW\*(C`ev_timer\*(C'\fR) will be not affected. Setting this to a non-null value will
951introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. 971introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. The
972sleep time ensures that libev will not poll for I/O events more often then
973once per this interval, on average.
952.Sp 974.Sp
953Likewise, by setting a higher \fItimeout collect interval\fR you allow libev 975Likewise, by setting a higher \fItimeout collect interval\fR you allow libev
954to spend more time collecting timeouts, at the expense of increased 976to spend more time collecting timeouts, at the expense of increased
955latency/jitter/inexactness (the watcher callback will be called 977latency/jitter/inexactness (the watcher callback will be called
956later). \f(CW\*(C`ev_io\*(C'\fR watchers will not be affected. Setting this to a non-null 978later). \f(CW\*(C`ev_io\*(C'\fR watchers will not be affected. Setting this to a non-null
… …
958.Sp 980.Sp
959Many (busy) programs can usually benefit by setting the I/O collect 981Many (busy) programs can usually benefit by setting the I/O collect
960interval to a value near \f(CW0.1\fR or so, which is often enough for 982interval to a value near \f(CW0.1\fR or so, which is often enough for
961interactive servers (of course not for games), likewise for timeouts. It 983interactive servers (of course not for games), likewise for timeouts. It
962usually doesn't make much sense to set it to a lower value than \f(CW0.01\fR, 984usually doesn't make much sense to set it to a lower value than \f(CW0.01\fR,
963as this approaches the timing granularity of most systems. 985as this approaches the timing granularity of most systems. Note that if
986you do transactions with the outside world and you can't increase the
987parallelity, then this setting will limit your transaction rate (if you
988need to poll once per transaction and the I/O collect interval is 0.01,
989then you can't do more than 100 transations per second).
964.Sp 990.Sp
965Setting the \fItimeout collect interval\fR can improve the opportunity for 991Setting the \fItimeout collect interval\fR can improve the opportunity for
966saving power, as the program will \*(L"bundle\*(R" timer callback invocations that 992saving power, as the program will \*(L"bundle\*(R" timer callback invocations that
967are \*(L"near\*(R" in time together, by delaying some, thus reducing the number of 993are \*(L"near\*(R" in time together, by delaying some, thus reducing the number of
968times the process sleeps and wakes up again. Another useful technique to 994times the process sleeps and wakes up again. Another useful technique to
969reduce iterations/wake\-ups is to use \f(CW\*(C`ev_periodic\*(C'\fR watchers and make sure 995reduce iterations/wake\-ups is to use \f(CW\*(C`ev_periodic\*(C'\fR watchers and make sure
970they fire on, say, one-second boundaries only. 996they fire on, say, one-second boundaries only.
997.Sp
998Example: we only need 0.1s timeout granularity, and we wish not to poll
999more often than 100 times per second:
1000.Sp
1001.Vb 2
1002\& ev_set_timeout_collect_interval (EV_DEFAULT_UC_ 0.1);
1003\& ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
1004.Ve
1005.IP "ev_invoke_pending (loop)" 4
1006.IX Item "ev_invoke_pending (loop)"
1007This call will simply invoke all pending watchers while resetting their
1008pending state. Normally, \f(CW\*(C`ev_loop\*(C'\fR does this automatically when required,
1009but when overriding the invoke callback this call comes handy.
1010.IP "int ev_pending_count (loop)" 4
1011.IX Item "int ev_pending_count (loop)"
1012Returns the number of pending watchers \- zero indicates that no watchers
1013are pending.
1014.IP "ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(\s-1EV_P\s0))" 4
1015.IX Item "ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))"
1016This overrides the invoke pending functionality of the loop: Instead of
1017invoking all pending watchers when there are any, \f(CW\*(C`ev_loop\*(C'\fR will call
1018this callback instead. This is useful, for example, when you want to
1019invoke the actual watchers inside another context (another thread etc.).
1020.Sp
1021If you want to reset the callback, use \f(CW\*(C`ev_invoke_pending\*(C'\fR as new
1022callback.
1023.IP "ev_set_loop_release_cb (loop, void (*release)(\s-1EV_P\s0), void (*acquire)(\s-1EV_P\s0))" 4
1024.IX Item "ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P))"
1025Sometimes you want to share the same loop between multiple threads. This
1026can be done relatively simply by putting mutex_lock/unlock calls around
1027each call to a libev function.
1028.Sp
1029However, \f(CW\*(C`ev_loop\*(C'\fR can run an indefinite time, so it is not feasible to
1030wait for it to return. One way around this is to wake up the loop via
1031\&\f(CW\*(C`ev_unloop\*(C'\fR and \f(CW\*(C`av_async_send\*(C'\fR, another way is to set these \fIrelease\fR
1032and \fIacquire\fR callbacks on the loop.
1033.Sp
1034When set, then \f(CW\*(C`release\*(C'\fR will be called just before the thread is
1035suspended waiting for new events, and \f(CW\*(C`acquire\*(C'\fR is called just
1036afterwards.
1037.Sp
1038Ideally, \f(CW\*(C`release\*(C'\fR will just call your mutex_unlock function, and
1039\&\f(CW\*(C`acquire\*(C'\fR will just call the mutex_lock function again.
1040.Sp
1041While event loop modifications are allowed between invocations of
1042\&\f(CW\*(C`release\*(C'\fR and \f(CW\*(C`acquire\*(C'\fR (that's their only purpose after all), no
1043modifications done will affect the event loop, i.e. adding watchers will
1044have no effect on the set of file descriptors being watched, or the time
1045waited. USe an \f(CW\*(C`ev_async\*(C'\fR watcher to wake up \f(CW\*(C`ev_loop\*(C'\fR when you want it
1046to take note of any changes you made.
1047.Sp
1048In theory, threads executing \f(CW\*(C`ev_loop\*(C'\fR will be async-cancel safe between
1049invocations of \f(CW\*(C`release\*(C'\fR and \f(CW\*(C`acquire\*(C'\fR.
1050.Sp
1051See also the locking example in the \f(CW\*(C`THREADS\*(C'\fR section later in this
1052document.
1053.IP "ev_set_userdata (loop, void *data)" 4
1054.IX Item "ev_set_userdata (loop, void *data)"
1055.PD 0
1056.IP "ev_userdata (loop)" 4
1057.IX Item "ev_userdata (loop)"
1058.PD
1059Set and retrieve a single \f(CW\*(C`void *\*(C'\fR associated with a loop. When
1060\&\f(CW\*(C`ev_set_userdata\*(C'\fR has never been called, then \f(CW\*(C`ev_userdata\*(C'\fR returns
1061\&\f(CW0.\fR
1062.Sp
1063These two functions can be used to associate arbitrary data with a loop,
1064and are intended solely for the \f(CW\*(C`invoke_pending_cb\*(C'\fR, \f(CW\*(C`release\*(C'\fR and
1065\&\f(CW\*(C`acquire\*(C'\fR callbacks described above, but of course can be (ab\-)used for
1066any other purpose as well.
971.IP "ev_loop_verify (loop)" 4 1067.IP "ev_loop_verify (loop)" 4
972.IX Item "ev_loop_verify (loop)" 1068.IX Item "ev_loop_verify (loop)"
973This function only does something when \f(CW\*(C`EV_VERIFY\*(C'\fR support has been 1069This function only does something when \f(CW\*(C`EV_VERIFY\*(C'\fR support has been
974compiled in, which is the default for non-minimal builds. It tries to go 1070compiled in, which is the default for non-minimal builds. It tries to go
975through all internal structures and checks them for validity. If anything 1071through all internal structures and checks them for validity. If anything
… …
1124example it might indicate that a fd is readable or writable, and if your 1220example it might indicate that a fd is readable or writable, and if your
1125callbacks is well-written it can just attempt the operation and cope with 1221callbacks is well-written it can just attempt the operation and cope with
1126the error from \fIread()\fR or \fIwrite()\fR. This will not work in multi-threaded 1222the error from \fIread()\fR or \fIwrite()\fR. This will not work in multi-threaded
1127programs, though, as the fd could already be closed and reused for another 1223programs, though, as the fd could already be closed and reused for another
1128thing, so beware. 1224thing, so beware.
1129.Sh "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" 1225.SS "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0"
1130.IX Subsection "GENERIC WATCHER FUNCTIONS" 1226.IX Subsection "GENERIC WATCHER FUNCTIONS"
1131.ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 1227.ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4
1132.el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 1228.el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4
1133.IX Item "ev_init (ev_TYPE *watcher, callback)" 1229.IX Item "ev_init (ev_TYPE *watcher, callback)"
1134This macro initialises the generic portion of a watcher. The contents 1230This macro initialises the generic portion of a watcher. The contents
… …
1258returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the 1354returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the
1259watcher isn't pending it does nothing and returns \f(CW0\fR. 1355watcher isn't pending it does nothing and returns \f(CW0\fR.
1260.Sp 1356.Sp
1261Sometimes it can be useful to \*(L"poll\*(R" a watcher instead of waiting for its 1357Sometimes it can be useful to \*(L"poll\*(R" a watcher instead of waiting for its
1262callback to be invoked, which can be accomplished with this function. 1358callback to be invoked, which can be accomplished with this function.
1263.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" 1359.SS "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0"
1264.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" 1360.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER"
1265Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change 1361Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change
1266and read at any time: libev will completely ignore it. This can be used 1362and read at any time: libev will completely ignore it. This can be used
1267to associate arbitrary data with your watcher. If you need more data and 1363to associate arbitrary data with your watcher. If you need more data and
1268don't want to allocate memory and store a pointer to it in that data 1364don't want to allocate memory and store a pointer to it in that data
… …
1319\& #include <stddef.h> 1415\& #include <stddef.h>
1320\& 1416\&
1321\& static void 1417\& static void
1322\& t1_cb (EV_P_ ev_timer *w, int revents) 1418\& t1_cb (EV_P_ ev_timer *w, int revents)
1323\& { 1419\& {
1324\& struct my_biggy big = (struct my_biggy * 1420\& struct my_biggy big = (struct my_biggy *)
1325\& (((char *)w) \- offsetof (struct my_biggy, t1)); 1421\& (((char *)w) \- offsetof (struct my_biggy, t1));
1326\& } 1422\& }
1327\& 1423\&
1328\& static void 1424\& static void
1329\& t2_cb (EV_P_ ev_timer *w, int revents) 1425\& t2_cb (EV_P_ ev_timer *w, int revents)
1330\& { 1426\& {
1331\& struct my_biggy big = (struct my_biggy * 1427\& struct my_biggy big = (struct my_biggy *)
1332\& (((char *)w) \- offsetof (struct my_biggy, t2)); 1428\& (((char *)w) \- offsetof (struct my_biggy, t2));
1333\& } 1429\& }
1334.Ve 1430.Ve
1335.Sh "\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0" 1431.SS "\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0"
1336.IX Subsection "WATCHER PRIORITY MODELS" 1432.IX Subsection "WATCHER PRIORITY MODELS"
1337Many event loops support \fIwatcher priorities\fR, which are usually small 1433Many event loops support \fIwatcher priorities\fR, which are usually small
1338integers that influence the ordering of event callback invocation 1434integers that influence the ordering of event callback invocation
1339between watchers in some way, all else being equal. 1435between watchers in some way, all else being equal.
1340.PP 1436.PP
… …
1413\& // with the default priority are receiving events. 1509\& // with the default priority are receiving events.
1414\& ev_idle_start (EV_A_ &idle); 1510\& ev_idle_start (EV_A_ &idle);
1415\& } 1511\& }
1416\& 1512\&
1417\& static void 1513\& static void
1418\& idle\-cb (EV_P_ ev_idle *w, int revents) 1514\& idle_cb (EV_P_ ev_idle *w, int revents)
1419\& { 1515\& {
1420\& // actual processing 1516\& // actual processing
1421\& read (STDIN_FILENO, ...); 1517\& read (STDIN_FILENO, ...);
1422\& 1518\&
1423\& // have to start the I/O watcher again, as 1519\& // have to start the I/O watcher again, as
… …
1448watcher is stopped to your hearts content), or \fI[read\-write]\fR, which 1544watcher is stopped to your hearts content), or \fI[read\-write]\fR, which
1449means you can expect it to have some sensible content while the watcher 1545means you can expect it to have some sensible content while the watcher
1450is active, but you can also modify it. Modifying it may not do something 1546is active, but you can also modify it. Modifying it may not do something
1451sensible or take immediate effect (or do anything at all), but libev will 1547sensible or take immediate effect (or do anything at all), but libev will
1452not crash or malfunction in any way. 1548not crash or malfunction in any way.
1453.ie n .Sh """ev_io"" \- is this file descriptor readable or writable?" 1549.ie n .SS """ev_io"" \- is this file descriptor readable or writable?"
1454.el .Sh "\f(CWev_io\fP \- is this file descriptor readable or writable?" 1550.el .SS "\f(CWev_io\fP \- is this file descriptor readable or writable?"
1455.IX Subsection "ev_io - is this file descriptor readable or writable?" 1551.IX Subsection "ev_io - is this file descriptor readable or writable?"
1456I/O watchers check whether a file descriptor is readable or writable 1552I/O watchers check whether a file descriptor is readable or writable
1457in each iteration of the event loop, or, more precisely, when reading 1553in each iteration of the event loop, or, more precisely, when reading
1458would not block the process and writing would at least be able to write 1554would not block the process and writing would at least be able to write
1459some data. This behaviour is called level-triggering because you keep 1555some data. This behaviour is called level-triggering because you keep
… …
1587\& ev_io stdin_readable; 1683\& ev_io stdin_readable;
1588\& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); 1684\& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1589\& ev_io_start (loop, &stdin_readable); 1685\& ev_io_start (loop, &stdin_readable);
1590\& ev_loop (loop, 0); 1686\& ev_loop (loop, 0);
1591.Ve 1687.Ve
1592.ie n .Sh """ev_timer"" \- relative and optionally repeating timeouts" 1688.ie n .SS """ev_timer"" \- relative and optionally repeating timeouts"
1593.el .Sh "\f(CWev_timer\fP \- relative and optionally repeating timeouts" 1689.el .SS "\f(CWev_timer\fP \- relative and optionally repeating timeouts"
1594.IX Subsection "ev_timer - relative and optionally repeating timeouts" 1690.IX Subsection "ev_timer - relative and optionally repeating timeouts"
1595Timer watchers are simple relative timers that generate an event after a 1691Timer watchers are simple relative timers that generate an event after a
1596given time, and optionally repeating in regular intervals after that. 1692given time, and optionally repeating in regular intervals after that.
1597.PP 1693.PP
1598The timers are based on real time, that is, if you register an event that 1694The timers are based on real time, that is, if you register an event that
… …
1603.PP 1699.PP
1604The callback is guaranteed to be invoked only \fIafter\fR its timeout has 1700The callback is guaranteed to be invoked only \fIafter\fR its timeout has
1605passed (not \fIat\fR, so on systems with very low-resolution clocks this 1701passed (not \fIat\fR, so on systems with very low-resolution clocks this
1606might introduce a small delay). If multiple timers become ready during the 1702might introduce a small delay). If multiple timers become ready during the
1607same loop iteration then the ones with earlier time-out values are invoked 1703same loop iteration then the ones with earlier time-out values are invoked
1608before ones with later time-out values (but this is no longer true when a 1704before ones of the same priority with later time-out values (but this is
1609callback calls \f(CW\*(C`ev_loop\*(C'\fR recursively). 1705no longer true when a callback calls \f(CW\*(C`ev_loop\*(C'\fR recursively).
1610.PP 1706.PP
1611\fIBe smart about timeouts\fR 1707\fIBe smart about timeouts\fR
1612.IX Subsection "Be smart about timeouts" 1708.IX Subsection "Be smart about timeouts"
1613.PP 1709.PP
1614Many real-world problems involve some kind of timeout, usually for error 1710Many real-world problems involve some kind of timeout, usually for error
… …
1661member and \f(CW\*(C`ev_timer_again\*(C'\fR. 1757member and \f(CW\*(C`ev_timer_again\*(C'\fR.
1662.Sp 1758.Sp
1663At start: 1759At start:
1664.Sp 1760.Sp
1665.Vb 3 1761.Vb 3
1666\& ev_timer_init (timer, callback); 1762\& ev_init (timer, callback);
1667\& timer\->repeat = 60.; 1763\& timer\->repeat = 60.;
1668\& ev_timer_again (loop, timer); 1764\& ev_timer_again (loop, timer);
1669.Ve 1765.Ve
1670.Sp 1766.Sp
1671Each time there is some activity: 1767Each time there is some activity:
… …
1740To start the timer, simply initialise the watcher and set \f(CW\*(C`last_activity\*(C'\fR 1836To start the timer, simply initialise the watcher and set \f(CW\*(C`last_activity\*(C'\fR
1741to the current time (meaning we just have some activity :), then call the 1837to the current time (meaning we just have some activity :), then call the
1742callback, which will \*(L"do the right thing\*(R" and start the timer: 1838callback, which will \*(L"do the right thing\*(R" and start the timer:
1743.Sp 1839.Sp
1744.Vb 3 1840.Vb 3
1745\& ev_timer_init (timer, callback); 1841\& ev_init (timer, callback);
1746\& last_activity = ev_now (loop); 1842\& last_activity = ev_now (loop);
1747\& callback (loop, timer, EV_TIMEOUT); 1843\& callback (loop, timer, EV_TIMEOUT);
1748.Ve 1844.Ve
1749.Sp 1845.Sp
1750And when there is some activity, simply store the current time in 1846And when there is some activity, simply store the current time in
… …
1813.Ve 1909.Ve
1814.PP 1910.PP
1815If the event loop is suspended for a long time, you can also force an 1911If the event loop is suspended for a long time, you can also force an
1816update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update 1912update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update
1817()\*(C'\fR. 1913()\*(C'\fR.
1914.PP
1915\fIThe special problems of suspended animation\fR
1916.IX Subsection "The special problems of suspended animation"
1917.PP
1918When you leave the server world it is quite customary to hit machines that
1919can suspend/hibernate \- what happens to the clocks during such a suspend?
1920.PP
1921Some quick tests made with a Linux 2.6.28 indicate that a suspend freezes
1922all processes, while the clocks (\f(CW\*(C`times\*(C'\fR, \f(CW\*(C`CLOCK_MONOTONIC\*(C'\fR) continue
1923to run until the system is suspended, but they will not advance while the
1924system is suspended. That means, on resume, it will be as if the program
1925was frozen for a few seconds, but the suspend time will not be counted
1926towards \f(CW\*(C`ev_timer\*(C'\fR when a monotonic clock source is used. The real time
1927clock advanced as expected, but if it is used as sole clocksource, then a
1928long suspend would be detected as a time jump by libev, and timers would
1929be adjusted accordingly.
1930.PP
1931I would not be surprised to see different behaviour in different between
1932operating systems, \s-1OS\s0 versions or even different hardware.
1933.PP
1934The other form of suspend (job control, or sending a \s-1SIGSTOP\s0) will see a
1935time jump in the monotonic clocks and the realtime clock. If the program
1936is suspended for a very long time, and monotonic clock sources are in use,
1937then you can expect \f(CW\*(C`ev_timer\*(C'\fRs to expire as the full suspension time
1938will be counted towards the timers. When no monotonic clock source is in
1939use, then libev will again assume a timejump and adjust accordingly.
1940.PP
1941It might be beneficial for this latter case to call \f(CW\*(C`ev_suspend\*(C'\fR
1942and \f(CW\*(C`ev_resume\*(C'\fR in code that handles \f(CW\*(C`SIGTSTP\*(C'\fR, to at least get
1943deterministic behaviour in this case (you can do nothing against
1944\&\f(CW\*(C`SIGSTOP\*(C'\fR).
1818.PP 1945.PP
1819\fIWatcher-Specific Functions and Data Members\fR 1946\fIWatcher-Specific Functions and Data Members\fR
1820.IX Subsection "Watcher-Specific Functions and Data Members" 1947.IX Subsection "Watcher-Specific Functions and Data Members"
1821.IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 1948.IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4
1822.IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 1949.IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)"
… …
1847If the timer is repeating, either start it if necessary (with the 1974If the timer is repeating, either start it if necessary (with the
1848\&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value. 1975\&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value.
1849.Sp 1976.Sp
1850This sounds a bit complicated, see \*(L"Be smart about timeouts\*(R", above, for a 1977This sounds a bit complicated, see \*(L"Be smart about timeouts\*(R", above, for a
1851usage example. 1978usage example.
1979.IP "ev_timer_remaining (loop, ev_timer *)" 4
1980.IX Item "ev_timer_remaining (loop, ev_timer *)"
1981Returns the remaining time until a timer fires. If the timer is active,
1982then this time is relative to the current event loop time, otherwise it's
1983the timeout value currently configured.
1984.Sp
1985That is, after an \f(CW\*(C`ev_timer_set (w, 5, 7)\*(C'\fR, \f(CW\*(C`ev_timer_remaining\*(C'\fR returns
1986\&\f(CW5\fR. When the timer is started and one second passes, \f(CW\*(C`ev_timer_remain\*(C'\fR
1987will return \f(CW4\fR. When the timer expires and is restarted, it will return
1988roughly \f(CW7\fR (likely slightly less as callback invocation takes some time,
1989too), and so on.
1852.IP "ev_tstamp repeat [read\-write]" 4 1990.IP "ev_tstamp repeat [read\-write]" 4
1853.IX Item "ev_tstamp repeat [read-write]" 1991.IX Item "ev_tstamp repeat [read-write]"
1854The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out 1992The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out
1855or \f(CW\*(C`ev_timer_again\*(C'\fR is called, and determines the next timeout (if any), 1993or \f(CW\*(C`ev_timer_again\*(C'\fR is called, and determines the next timeout (if any),
1856which is also when any modifications are taken into account. 1994which is also when any modifications are taken into account.
… …
1889\& 2027\&
1890\& // and in some piece of code that gets executed on any "activity": 2028\& // and in some piece of code that gets executed on any "activity":
1891\& // reset the timeout to start ticking again at 10 seconds 2029\& // reset the timeout to start ticking again at 10 seconds
1892\& ev_timer_again (&mytimer); 2030\& ev_timer_again (&mytimer);
1893.Ve 2031.Ve
1894.ie n .Sh """ev_periodic"" \- to cron or not to cron?" 2032.ie n .SS """ev_periodic"" \- to cron or not to cron?"
1895.el .Sh "\f(CWev_periodic\fP \- to cron or not to cron?" 2033.el .SS "\f(CWev_periodic\fP \- to cron or not to cron?"
1896.IX Subsection "ev_periodic - to cron or not to cron?" 2034.IX Subsection "ev_periodic - to cron or not to cron?"
1897Periodic watchers are also timers of a kind, but they are very versatile 2035Periodic watchers are also timers of a kind, but they are very versatile
1898(and unfortunately a bit complex). 2036(and unfortunately a bit complex).
1899.PP 2037.PP
1900Unlike \f(CW\*(C`ev_timer\*(C'\fR, periodic watchers are not based on real time (or 2038Unlike \f(CW\*(C`ev_timer\*(C'\fR, periodic watchers are not based on real time (or
… …
2088\& ev_periodic hourly_tick; 2226\& ev_periodic hourly_tick;
2089\& ev_periodic_init (&hourly_tick, clock_cb, 2227\& ev_periodic_init (&hourly_tick, clock_cb,
2090\& fmod (ev_now (loop), 3600.), 3600., 0); 2228\& fmod (ev_now (loop), 3600.), 3600., 0);
2091\& ev_periodic_start (loop, &hourly_tick); 2229\& ev_periodic_start (loop, &hourly_tick);
2092.Ve 2230.Ve
2093.ie n .Sh """ev_signal"" \- signal me when a signal gets signalled!" 2231.ie n .SS """ev_signal"" \- signal me when a signal gets signalled!"
2094.el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled!" 2232.el .SS "\f(CWev_signal\fP \- signal me when a signal gets signalled!"
2095.IX Subsection "ev_signal - signal me when a signal gets signalled!" 2233.IX Subsection "ev_signal - signal me when a signal gets signalled!"
2096Signal watchers will trigger an event when the process receives a specific 2234Signal watchers will trigger an event when the process receives a specific
2097signal one or more times. Even though signals are very asynchronous, libev 2235signal one or more times. Even though signals are very asynchronous, libev
2098will try it's best to deliver signals synchronously, i.e. as part of the 2236will try it's best to deliver signals synchronously, i.e. as part of the
2099normal event processing, like any other event. 2237normal event processing, like any other event.
2100.PP 2238.PP
2101If you want signals asynchronously, just use \f(CW\*(C`sigaction\*(C'\fR as you would 2239If you want signals to be delivered truly asynchronously, just use
2102do without libev and forget about sharing the signal. You can even use 2240\&\f(CW\*(C`sigaction\*(C'\fR as you would do without libev and forget about sharing
2103\&\f(CW\*(C`ev_async\*(C'\fR from a signal handler to synchronously wake up an event loop. 2241the signal. You can even use \f(CW\*(C`ev_async\*(C'\fR from a signal handler to
2242synchronously wake up an event loop.
2104.PP 2243.PP
2105You can configure as many watchers as you like per signal. Only when the 2244You can configure as many watchers as you like for the same signal, but
2245only within the same loop, i.e. you can watch for \f(CW\*(C`SIGINT\*(C'\fR in your
2246default loop and for \f(CW\*(C`SIGIO\*(C'\fR in another loop, but you cannot watch for
2247\&\f(CW\*(C`SIGINT\*(C'\fR in both the default loop and another loop at the same time. At
2248the moment, \f(CW\*(C`SIGCHLD\*(C'\fR is permanently tied to the default loop.
2249.PP
2106first watcher gets started will libev actually register a signal handler 2250When the first watcher gets started will libev actually register something
2107with the kernel (thus it coexists with your own signal handlers as long as 2251with the kernel (thus it coexists with your own signal handlers as long as
2108you don't register any with libev for the same signal). Similarly, when 2252you don't register any with libev for the same signal).
2109the last signal watcher for a signal is stopped, libev will reset the 2253.PP
2110signal handler to \s-1SIG_DFL\s0 (regardless of what it was set to before). 2254Both the signal mask state (\f(CW\*(C`sigprocmask\*(C'\fR) and the signal handler state
2255(\f(CW\*(C`sigaction\*(C'\fR) are unspecified after starting a signal watcher (and after
2256sotpping it again), that is, libev might or might not block the signal,
2257and might or might not set or restore the installed signal handler.
2111.PP 2258.PP
2112If possible and supported, libev will install its handlers with 2259If possible and supported, libev will install its handlers with
2113\&\f(CW\*(C`SA_RESTART\*(C'\fR behaviour enabled, so system calls should not be unduly 2260\&\f(CW\*(C`SA_RESTART\*(C'\fR (or equivalent) behaviour enabled, so system calls should
2114interrupted. If you have a problem with system calls getting interrupted by 2261not be unduly interrupted. If you have a problem with system calls getting
2115signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher and unblock 2262interrupted by signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher
2116them in an \f(CW\*(C`ev_prepare\*(C'\fR watcher. 2263and unblock them in an \f(CW\*(C`ev_prepare\*(C'\fR watcher.
2117.PP 2264.PP
2118\fIWatcher-Specific Functions and Data Members\fR 2265\fIWatcher-Specific Functions and Data Members\fR
2119.IX Subsection "Watcher-Specific Functions and Data Members" 2266.IX Subsection "Watcher-Specific Functions and Data Members"
2120.IP "ev_signal_init (ev_signal *, callback, int signum)" 4 2267.IP "ev_signal_init (ev_signal *, callback, int signum)" 4
2121.IX Item "ev_signal_init (ev_signal *, callback, int signum)" 2268.IX Item "ev_signal_init (ev_signal *, callback, int signum)"
… …
2143\& 2290\&
2144\& ev_signal signal_watcher; 2291\& ev_signal signal_watcher;
2145\& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); 2292\& ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
2146\& ev_signal_start (loop, &signal_watcher); 2293\& ev_signal_start (loop, &signal_watcher);
2147.Ve 2294.Ve
2148.ie n .Sh """ev_child"" \- watch out for process status changes" 2295.ie n .SS """ev_child"" \- watch out for process status changes"
2149.el .Sh "\f(CWev_child\fP \- watch out for process status changes" 2296.el .SS "\f(CWev_child\fP \- watch out for process status changes"
2150.IX Subsection "ev_child - watch out for process status changes" 2297.IX Subsection "ev_child - watch out for process status changes"
2151Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to 2298Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to
2152some child status changes (most typically when a child of yours dies or 2299some child status changes (most typically when a child of yours dies or
2153exits). It is permissible to install a child watcher \fIafter\fR the child 2300exits). It is permissible to install a child watcher \fIafter\fR the child
2154has been forked (which implies it might have already exited), as long 2301has been forked (which implies it might have already exited), as long
2155as the event loop isn't entered (or is continued from a watcher), i.e., 2302as the event loop isn't entered (or is continued from a watcher), i.e.,
2156forking and then immediately registering a watcher for the child is fine, 2303forking and then immediately registering a watcher for the child is fine,
2157but forking and registering a watcher a few event loop iterations later is 2304but forking and registering a watcher a few event loop iterations later or
2158not. 2305in the next callback invocation is not.
2159.PP 2306.PP
2160Only the default event loop is capable of handling signals, and therefore 2307Only the default event loop is capable of handling signals, and therefore
2161you can only register child watchers in the default event loop. 2308you can only register child watchers in the default event loop.
2162.PP 2309.PP
2310Due to some design glitches inside libev, child watchers will always be
2311handled at maximum priority (their priority is set to \f(CW\*(C`EV_MAXPRI\*(C'\fR by
2312libev)
2313.PP
2163\fIProcess Interaction\fR 2314\fIProcess Interaction\fR
2164.IX Subsection "Process Interaction" 2315.IX Subsection "Process Interaction"
2165.PP 2316.PP
2166Libev grabs \f(CW\*(C`SIGCHLD\*(C'\fR as soon as the default event loop is 2317Libev grabs \f(CW\*(C`SIGCHLD\*(C'\fR as soon as the default event loop is
2167initialised. This is necessary to guarantee proper behaviour even if 2318initialised. This is necessary to guarantee proper behaviour even if the
2168the first child watcher is started after the child exits. The occurrence 2319first child watcher is started after the child exits. The occurrence
2169of \f(CW\*(C`SIGCHLD\*(C'\fR is recorded asynchronously, but child reaping is done 2320of \f(CW\*(C`SIGCHLD\*(C'\fR is recorded asynchronously, but child reaping is done
2170synchronously as part of the event loop processing. Libev always reaps all 2321synchronously as part of the event loop processing. Libev always reaps all
2171children, even ones not watched. 2322children, even ones not watched.
2172.PP 2323.PP
2173\fIOverriding the Built-In Processing\fR 2324\fIOverriding the Built-In Processing\fR
… …
2185.IX Subsection "Stopping the Child Watcher" 2336.IX Subsection "Stopping the Child Watcher"
2186.PP 2337.PP
2187Currently, the child watcher never gets stopped, even when the 2338Currently, the child watcher never gets stopped, even when the
2188child terminates, so normally one needs to stop the watcher in the 2339child terminates, so normally one needs to stop the watcher in the
2189callback. Future versions of libev might stop the watcher automatically 2340callback. Future versions of libev might stop the watcher automatically
2190when a child exit is detected. 2341when a child exit is detected (calling \f(CW\*(C`ev_child_stop\*(C'\fR twice is not a
2342problem).
2191.PP 2343.PP
2192\fIWatcher-Specific Functions and Data Members\fR 2344\fIWatcher-Specific Functions and Data Members\fR
2193.IX Subsection "Watcher-Specific Functions and Data Members" 2345.IX Subsection "Watcher-Specific Functions and Data Members"
2194.IP "ev_child_init (ev_child *, callback, int pid, int trace)" 4 2346.IP "ev_child_init (ev_child *, callback, int pid, int trace)" 4
2195.IX Item "ev_child_init (ev_child *, callback, int pid, int trace)" 2347.IX Item "ev_child_init (ev_child *, callback, int pid, int trace)"
… …
2245\& { 2397\& {
2246\& ev_child_init (&cw, child_cb, pid, 0); 2398\& ev_child_init (&cw, child_cb, pid, 0);
2247\& ev_child_start (EV_DEFAULT_ &cw); 2399\& ev_child_start (EV_DEFAULT_ &cw);
2248\& } 2400\& }
2249.Ve 2401.Ve
2250.ie n .Sh """ev_stat"" \- did the file attributes just change?" 2402.ie n .SS """ev_stat"" \- did the file attributes just change?"
2251.el .Sh "\f(CWev_stat\fP \- did the file attributes just change?" 2403.el .SS "\f(CWev_stat\fP \- did the file attributes just change?"
2252.IX Subsection "ev_stat - did the file attributes just change?" 2404.IX Subsection "ev_stat - did the file attributes just change?"
2253This watches a file system path for attribute changes. That is, it calls 2405This watches a file system path for attribute changes. That is, it calls
2254\&\f(CW\*(C`stat\*(C'\fR on that path in regular intervals (or when the \s-1OS\s0 says it changed) 2406\&\f(CW\*(C`stat\*(C'\fR on that path in regular intervals (or when the \s-1OS\s0 says it changed)
2255and sees if it changed compared to the last time, invoking the callback if 2407and sees if it changed compared to the last time, invoking the callback if
2256it did. 2408it did.
… …
2470\& ... 2622\& ...
2471\& ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); 2623\& ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);
2472\& ev_stat_start (loop, &passwd); 2624\& ev_stat_start (loop, &passwd);
2473\& ev_timer_init (&timer, timer_cb, 0., 1.02); 2625\& ev_timer_init (&timer, timer_cb, 0., 1.02);
2474.Ve 2626.Ve
2475.ie n .Sh """ev_idle"" \- when you've got nothing better to do..." 2627.ie n .SS """ev_idle"" \- when you've got nothing better to do..."
2476.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..." 2628.el .SS "\f(CWev_idle\fP \- when you've got nothing better to do..."
2477.IX Subsection "ev_idle - when you've got nothing better to do..." 2629.IX Subsection "ev_idle - when you've got nothing better to do..."
2478Idle watchers trigger events when no other events of the same or higher 2630Idle watchers trigger events when no other events of the same or higher
2479priority are pending (prepare, check and other idle watchers do not count 2631priority are pending (prepare, check and other idle watchers do not count
2480as receiving \*(L"events\*(R"). 2632as receiving \*(L"events\*(R").
2481.PP 2633.PP
… …
2517\& // no longer anything immediate to do. 2669\& // no longer anything immediate to do.
2518\& } 2670\& }
2519\& 2671\&
2520\& ev_idle *idle_watcher = malloc (sizeof (ev_idle)); 2672\& ev_idle *idle_watcher = malloc (sizeof (ev_idle));
2521\& ev_idle_init (idle_watcher, idle_cb); 2673\& ev_idle_init (idle_watcher, idle_cb);
2522\& ev_idle_start (loop, idle_cb); 2674\& ev_idle_start (loop, idle_watcher);
2523.Ve 2675.Ve
2524.ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!" 2676.ie n .SS """ev_prepare"" and ""ev_check"" \- customise your event loop!"
2525.el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" 2677.el .SS "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!"
2526.IX Subsection "ev_prepare and ev_check - customise your event loop!" 2678.IX Subsection "ev_prepare and ev_check - customise your event loop!"
2527Prepare and check watchers are usually (but not always) used in pairs: 2679Prepare and check watchers are usually (but not always) used in pairs:
2528prepare watchers get invoked before the process blocks and check watchers 2680prepare watchers get invoked before the process blocks and check watchers
2529afterwards. 2681afterwards.
2530.PP 2682.PP
… …
2620\& struct pollfd fds [nfd]; 2772\& struct pollfd fds [nfd];
2621\& // actual code will need to loop here and realloc etc. 2773\& // actual code will need to loop here and realloc etc.
2622\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); 2774\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
2623\& 2775\&
2624\& /* the callback is illegal, but won\*(Aqt be called as we stop during check */ 2776\& /* the callback is illegal, but won\*(Aqt be called as we stop during check */
2625\& ev_timer_init (&tw, 0, timeout * 1e\-3); 2777\& ev_timer_init (&tw, 0, timeout * 1e\-3, 0.);
2626\& ev_timer_start (loop, &tw); 2778\& ev_timer_start (loop, &tw);
2627\& 2779\&
2628\& // create one ev_io per pollfd 2780\& // create one ev_io per pollfd
2629\& for (int i = 0; i < nfd; ++i) 2781\& for (int i = 0; i < nfd; ++i)
2630\& { 2782\& {
… …
2721\& ev_io_stop (EV_A_ iow [n]); 2873\& ev_io_stop (EV_A_ iow [n]);
2722\& 2874\&
2723\& return got_events; 2875\& return got_events;
2724\& } 2876\& }
2725.Ve 2877.Ve
2726.ie n .Sh """ev_embed"" \- when one backend isn't enough..." 2878.ie n .SS """ev_embed"" \- when one backend isn't enough..."
2727.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." 2879.el .SS "\f(CWev_embed\fP \- when one backend isn't enough..."
2728.IX Subsection "ev_embed - when one backend isn't enough..." 2880.IX Subsection "ev_embed - when one backend isn't enough..."
2729This is a rather advanced watcher type that lets you embed one event loop 2881This is a rather advanced watcher type that lets you embed one event loop
2730into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded 2882into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded
2731loop, other types of watchers might be handled in a delayed or incorrect 2883loop, other types of watchers might be handled in a delayed or incorrect
2732fashion and must not be used). 2884fashion and must not be used).
… …
2854\& if (!loop_socket) 3006\& if (!loop_socket)
2855\& loop_socket = loop; 3007\& loop_socket = loop;
2856\& 3008\&
2857\& // now use loop_socket for all sockets, and loop for everything else 3009\& // now use loop_socket for all sockets, and loop for everything else
2858.Ve 3010.Ve
2859.ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork" 3011.ie n .SS """ev_fork"" \- the audacity to resume the event loop after a fork"
2860.el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" 3012.el .SS "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork"
2861.IX Subsection "ev_fork - the audacity to resume the event loop after a fork" 3013.IX Subsection "ev_fork - the audacity to resume the event loop after a fork"
2862Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because 3014Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because
2863whoever is a good citizen cared to tell libev about it by calling 3015whoever is a good citizen cared to tell libev about it by calling
2864\&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the 3016\&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the
2865event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, 3017event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called,
… …
2906.IP "ev_fork_init (ev_signal *, callback)" 4 3058.IP "ev_fork_init (ev_signal *, callback)" 4
2907.IX Item "ev_fork_init (ev_signal *, callback)" 3059.IX Item "ev_fork_init (ev_signal *, callback)"
2908Initialises and configures the fork watcher \- it has no parameters of any 3060Initialises and configures the fork watcher \- it has no parameters of any
2909kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, 3061kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless,
2910believe me. 3062believe me.
2911.ie n .Sh """ev_async"" \- how to wake up another event loop" 3063.ie n .SS """ev_async"" \- how to wake up another event loop"
2912.el .Sh "\f(CWev_async\fP \- how to wake up another event loop" 3064.el .SS "\f(CWev_async\fP \- how to wake up another event loop"
2913.IX Subsection "ev_async - how to wake up another event loop" 3065.IX Subsection "ev_async - how to wake up another event loop"
2914In general, you cannot use an \f(CW\*(C`ev_loop\*(C'\fR from multiple threads or other 3066In general, you cannot use an \f(CW\*(C`ev_loop\*(C'\fR from multiple threads or other
2915asynchronous sources such as signal handlers (as opposed to multiple event 3067asynchronous sources such as signal handlers (as opposed to multiple event
2916loops \- those are of course safe to use in different threads). 3068loops \- those are of course safe to use in different threads).
2917.PP 3069.PP
… …
3155need one additional pointer for context. If you need support for other 3307need one additional pointer for context. If you need support for other
3156types of functors please contact the author (preferably after implementing 3308types of functors please contact the author (preferably after implementing
3157it). 3309it).
3158.PP 3310.PP
3159Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: 3311Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace:
3160.ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4 3312.ie n .IP """ev::READ"", ""ev::WRITE"" etc." 4
3161.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 3313.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4
3162.IX Item "ev::READ, ev::WRITE etc." 3314.IX Item "ev::READ, ev::WRITE etc."
3163These are just enum values with the same values as the \f(CW\*(C`EV_READ\*(C'\fR etc. 3315These are just enum values with the same values as the \f(CW\*(C`EV_READ\*(C'\fR etc.
3164macros from \fIev.h\fR. 3316macros from \fIev.h\fR.
3165.ie n .IP """ev::tstamp""\fR, \f(CW""ev::now""" 4 3317.ie n .IP """ev::tstamp"", ""ev::now""" 4
3166.el .IP "\f(CWev::tstamp\fR, \f(CWev::now\fR" 4 3318.el .IP "\f(CWev::tstamp\fR, \f(CWev::now\fR" 4
3167.IX Item "ev::tstamp, ev::now" 3319.IX Item "ev::tstamp, ev::now"
3168Aliases to the same types/functions as with the \f(CW\*(C`ev_\*(C'\fR prefix. 3320Aliases to the same types/functions as with the \f(CW\*(C`ev_\*(C'\fR prefix.
3169.ie n .IP """ev::io""\fR, \f(CW""ev::timer""\fR, \f(CW""ev::periodic""\fR, \f(CW""ev::idle""\fR, \f(CW""ev::sig"" etc." 4 3321.ie n .IP """ev::io"", ""ev::timer"", ""ev::periodic"", ""ev::idle"", ""ev::sig"" etc." 4
3170.el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4 3322.el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4
3171.IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc." 3323.IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc."
3172For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of 3324For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of
3173the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR 3325the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR
3174which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro 3326which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro
… …
3284Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the 3436Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the
3285constructor already stores the event loop. 3437constructor already stores the event loop.
3286.IP "w\->stop ()" 4 3438.IP "w\->stop ()" 4
3287.IX Item "w->stop ()" 3439.IX Item "w->stop ()"
3288Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. 3440Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument.
3289.ie n .IP "w\->again () (""ev::timer""\fR, \f(CW""ev::periodic"" only)" 4 3441.ie n .IP "w\->again () (""ev::timer"", ""ev::periodic"" only)" 4
3290.el .IP "w\->again () (\f(CWev::timer\fR, \f(CWev::periodic\fR only)" 4 3442.el .IP "w\->again () (\f(CWev::timer\fR, \f(CWev::periodic\fR only)" 4
3291.IX Item "w->again () (ev::timer, ev::periodic only)" 3443.IX Item "w->again () (ev::timer, ev::periodic only)"
3292For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding 3444For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding
3293\&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. 3445\&\f(CW\*(C`ev_TYPE_again\*(C'\fR function.
3294.ie n .IP "w\->sweep () (""ev::embed"" only)" 4 3446.ie n .IP "w\->sweep () (""ev::embed"" only)" 4
… …
3361be found at <http://proj.llucax.com.ar/wiki/evd>. 3513be found at <http://proj.llucax.com.ar/wiki/evd>.
3362.IP "Ocaml" 4 3514.IP "Ocaml" 4
3363.IX Item "Ocaml" 3515.IX Item "Ocaml"
3364Erkki Seppala has written Ocaml bindings for libev, to be found at 3516Erkki Seppala has written Ocaml bindings for libev, to be found at
3365<http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/>. 3517<http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/>.
3518.IP "Lua" 4
3519.IX Item "Lua"
3520Brian Maher has written a partial interface to libev
3521for lua (only \f(CW\*(C`ev_io\*(C'\fR and \f(CW\*(C`ev_timer\*(C'\fR), to be found at
3522<http://github.com/brimworks/lua\-ev>.
3366.SH "MACRO MAGIC" 3523.SH "MACRO MAGIC"
3367.IX Header "MACRO MAGIC" 3524.IX Header "MACRO MAGIC"
3368Libev can be compiled with a variety of options, the most fundamental 3525Libev can be compiled with a variety of options, the most fundamental
3369of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) 3526of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most)
3370functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. 3527functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument.
3371.PP 3528.PP
3372To make it easier to write programs that cope with either variant, the 3529To make it easier to write programs that cope with either variant, the
3373following macros are defined: 3530following macros are defined:
3374.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4 3531.ie n .IP """EV_A"", ""EV_A_""" 4
3375.el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4 3532.el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4
3376.IX Item "EV_A, EV_A_" 3533.IX Item "EV_A, EV_A_"
3377This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev 3534This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev
3378loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument, 3535loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument,
3379\&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example: 3536\&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example:
… …
3384\& ev_loop (EV_A_ 0); 3541\& ev_loop (EV_A_ 0);
3385.Ve 3542.Ve
3386.Sp 3543.Sp
3387It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope, 3544It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope,
3388which is often provided by the following macro. 3545which is often provided by the following macro.
3389.ie n .IP """EV_P""\fR, \f(CW""EV_P_""" 4 3546.ie n .IP """EV_P"", ""EV_P_""" 4
3390.el .IP "\f(CWEV_P\fR, \f(CWEV_P_\fR" 4 3547.el .IP "\f(CWEV_P\fR, \f(CWEV_P_\fR" 4
3391.IX Item "EV_P, EV_P_" 3548.IX Item "EV_P, EV_P_"
3392This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev 3549This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev
3393loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter, 3550loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter,
3394\&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example: 3551\&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example:
… …
3401\& static void cb (EV_P_ ev_timer *w, int revents) 3558\& static void cb (EV_P_ ev_timer *w, int revents)
3402.Ve 3559.Ve
3403.Sp 3560.Sp
3404It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite 3561It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite
3405suitable for use with \f(CW\*(C`EV_A\*(C'\fR. 3562suitable for use with \f(CW\*(C`EV_A\*(C'\fR.
3406.ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4 3563.ie n .IP """EV_DEFAULT"", ""EV_DEFAULT_""" 4
3407.el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 3564.el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4
3408.IX Item "EV_DEFAULT, EV_DEFAULT_" 3565.IX Item "EV_DEFAULT, EV_DEFAULT_"
3409Similar to the other two macros, this gives you the value of the default 3566Similar to the other two macros, this gives you the value of the default
3410loop, if multiple loops are supported (\*(L"ev loop default\*(R"). 3567loop, if multiple loops are supported (\*(L"ev loop default\*(R").
3411.ie n .IP """EV_DEFAULT_UC""\fR, \f(CW""EV_DEFAULT_UC_""" 4 3568.ie n .IP """EV_DEFAULT_UC"", ""EV_DEFAULT_UC_""" 4
3412.el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 3569.el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4
3413.IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" 3570.IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_"
3414Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the 3571Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the
3415default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour 3572default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour
3416is undefined when the default loop has not been initialised by a previous 3573is undefined when the default loop has not been initialised by a previous
… …
3444.PP 3601.PP
3445The goal is to enable you to just copy the necessary files into your 3602The goal is to enable you to just copy the necessary files into your
3446source directory without having to change even a single line in them, so 3603source directory without having to change even a single line in them, so
3447you can easily upgrade by simply copying (or having a checked-out copy of 3604you can easily upgrade by simply copying (or having a checked-out copy of
3448libev somewhere in your source tree). 3605libev somewhere in your source tree).
3449.Sh "\s-1FILESETS\s0" 3606.SS "\s-1FILESETS\s0"
3450.IX Subsection "FILESETS" 3607.IX Subsection "FILESETS"
3451Depending on what features you need you need to include one or more sets of files 3608Depending on what features you need you need to include one or more sets of files
3452in your application. 3609in your application.
3453.PP 3610.PP
3454\fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR 3611\fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR
… …
3533For this of course you need the m4 file: 3690For this of course you need the m4 file:
3534.PP 3691.PP
3535.Vb 1 3692.Vb 1
3536\& libev.m4 3693\& libev.m4
3537.Ve 3694.Ve
3538.Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" 3695.SS "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0"
3539.IX Subsection "PREPROCESSOR SYMBOLS/MACROS" 3696.IX Subsection "PREPROCESSOR SYMBOLS/MACROS"
3540Libev can be configured via a variety of preprocessor symbols you have to 3697Libev can be configured via a variety of preprocessor symbols you have to
3541define before including any of its files. The default in the absence of 3698define before including any of its files. The default in the absence of
3542autoconf is documented for every option. 3699autoconf is documented for every option.
3543.IP "\s-1EV_STANDALONE\s0" 4 3700.IP "\s-1EV_STANDALONE\s0" 4
… …
3546keeps libev from including \fIconfig.h\fR, and it also defines dummy 3703keeps libev from including \fIconfig.h\fR, and it also defines dummy
3547implementations for some libevent functions (such as logging, which is not 3704implementations for some libevent functions (such as logging, which is not
3548supported). It will also not define any of the structs usually found in 3705supported). It will also not define any of the structs usually found in
3549\&\fIevent.h\fR that are not directly supported by the libev core alone. 3706\&\fIevent.h\fR that are not directly supported by the libev core alone.
3550.Sp 3707.Sp
3551In stanbdalone mode, libev will still try to automatically deduce the 3708In standalone mode, libev will still try to automatically deduce the
3552configuration, but has to be more conservative. 3709configuration, but has to be more conservative.
3553.IP "\s-1EV_USE_MONOTONIC\s0" 4 3710.IP "\s-1EV_USE_MONOTONIC\s0" 4
3554.IX Item "EV_USE_MONOTONIC" 3711.IX Item "EV_USE_MONOTONIC"
3555If defined to be \f(CW1\fR, libev will try to detect the availability of the 3712If defined to be \f(CW1\fR, libev will try to detect the availability of the
3556monotonic clock option at both compile time and runtime. Otherwise no 3713monotonic clock option at both compile time and runtime. Otherwise no
… …
3742If undefined or defined to be \f(CW1\fR, then async watchers are supported. If 3899If undefined or defined to be \f(CW1\fR, then async watchers are supported. If
3743defined to be \f(CW0\fR, then they are not. 3900defined to be \f(CW0\fR, then they are not.
3744.IP "\s-1EV_MINIMAL\s0" 4 3901.IP "\s-1EV_MINIMAL\s0" 4
3745.IX Item "EV_MINIMAL" 3902.IX Item "EV_MINIMAL"
3746If you need to shave off some kilobytes of code at the expense of some 3903If you need to shave off some kilobytes of code at the expense of some
3747speed, define this symbol to \f(CW1\fR. Currently this is used to override some 3904speed (but with the full \s-1API\s0), define this symbol to \f(CW1\fR. Currently this
3748inlining decisions, saves roughly 30% code size on amd64. It also selects a 3905is used to override some inlining decisions, saves roughly 30% code size
3749much smaller 2\-heap for timer management over the default 4\-heap. 3906on amd64. It also selects a much smaller 2\-heap for timer management over
3907the default 4\-heap.
3908.Sp
3909You can save even more by disabling watcher types you do not need
3910and setting \f(CW\*(C`EV_MAXPRI\*(C'\fR == \f(CW\*(C`EV_MINPRI\*(C'\fR. Also, disabling \f(CW\*(C`assert\*(C'\fR
3911(\f(CW\*(C`\-DNDEBUG\*(C'\fR) will usually reduce code size a lot.
3912.Sp
3913Defining \f(CW\*(C`EV_MINIMAL\*(C'\fR to \f(CW2\fR will additionally reduce the core \s-1API\s0 to
3914provide a bare-bones event library. See \f(CW\*(C`ev.h\*(C'\fR for details on what parts
3915of the \s-1API\s0 are still available, and do not complain if this subset changes
3916over time.
3917.IP "\s-1EV_NSIG\s0" 4
3918.IX Item "EV_NSIG"
3919The highest supported signal number, +1 (or, the number of
3920signals): Normally, libev tries to deduce the maximum number of signals
3921automatically, but sometimes this fails, in which case it can be
3922specified. Also, using a lower number than detected (\f(CW32\fR should be
3923good for about any system in existance) can save some memory, as libev
3924statically allocates some 12\-24 bytes per signal number.
3750.IP "\s-1EV_PID_HASHSIZE\s0" 4 3925.IP "\s-1EV_PID_HASHSIZE\s0" 4
3751.IX Item "EV_PID_HASHSIZE" 3926.IX Item "EV_PID_HASHSIZE"
3752\&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by 3927\&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by
3753pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more 3928pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more
3754than enough. If you need to manage thousands of children you might want to 3929than enough. If you need to manage thousands of children you might want to
… …
3818and the way callbacks are invoked and set. Must expand to a struct member 3993and the way callbacks are invoked and set. Must expand to a struct member
3819definition and a statement, respectively. See the \fIev.h\fR header file for 3994definition and a statement, respectively. See the \fIev.h\fR header file for
3820their default definitions. One possible use for overriding these is to 3995their default definitions. One possible use for overriding these is to
3821avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use 3996avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use
3822method calls instead of plain function calls in \*(C+. 3997method calls instead of plain function calls in \*(C+.
3823.Sh "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" 3998.SS "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0"
3824.IX Subsection "EXPORTED API SYMBOLS" 3999.IX Subsection "EXPORTED API SYMBOLS"
3825If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of 4000If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of
3826exported symbols, you can use the provided \fISymbol.*\fR files which list 4001exported symbols, you can use the provided \fISymbol.*\fR files which list
3827all public symbols, one per line: 4002all public symbols, one per line:
3828.PP 4003.PP
… …
3848\& #define ev_backend myprefix_ev_backend 4023\& #define ev_backend myprefix_ev_backend
3849\& #define ev_check_start myprefix_ev_check_start 4024\& #define ev_check_start myprefix_ev_check_start
3850\& #define ev_check_stop myprefix_ev_check_stop 4025\& #define ev_check_stop myprefix_ev_check_stop
3851\& ... 4026\& ...
3852.Ve 4027.Ve
3853.Sh "\s-1EXAMPLES\s0" 4028.SS "\s-1EXAMPLES\s0"
3854.IX Subsection "EXAMPLES" 4029.IX Subsection "EXAMPLES"
3855For a real-world example of a program the includes libev 4030For a real-world example of a program the includes libev
3856verbatim, you can have a look at the \s-1EV\s0 perl module 4031verbatim, you can have a look at the \s-1EV\s0 perl module
3857(<http://software.schmorp.de/pkg/EV.html>). It has the libev files in 4032(<http://software.schmorp.de/pkg/EV.html>). It has the libev files in
3858the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public 4033the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public
… …
3883\& #include "ev_cpp.h" 4058\& #include "ev_cpp.h"
3884\& #include "ev.c" 4059\& #include "ev.c"
3885.Ve 4060.Ve
3886.SH "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" 4061.SH "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES"
3887.IX Header "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" 4062.IX Header "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES"
3888.Sh "\s-1THREADS\s0 \s-1AND\s0 \s-1COROUTINES\s0" 4063.SS "\s-1THREADS\s0 \s-1AND\s0 \s-1COROUTINES\s0"
3889.IX Subsection "THREADS AND COROUTINES" 4064.IX Subsection "THREADS AND COROUTINES"
3890\fI\s-1THREADS\s0\fR 4065\fI\s-1THREADS\s0\fR
3891.IX Subsection "THREADS" 4066.IX Subsection "THREADS"
3892.PP 4067.PP
3893All libev functions are reentrant and thread-safe unless explicitly 4068All libev functions are reentrant and thread-safe unless explicitly
… …
3939An example use would be to communicate signals or other events that only 4114An example use would be to communicate signals or other events that only
3940work in the default loop by registering the signal watcher with the 4115work in the default loop by registering the signal watcher with the
3941default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop 4116default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop
3942watcher callback into the event loop interested in the signal. 4117watcher callback into the event loop interested in the signal.
3943.PP 4118.PP
4119\s-1THREAD\s0 \s-1LOCKING\s0 \s-1EXAMPLE\s0
4120.IX Subsection "THREAD LOCKING EXAMPLE"
4121.PP
4122Here is a fictitious example of how to run an event loop in a different
4123thread than where callbacks are being invoked and watchers are
4124created/added/removed.
4125.PP
4126For a real-world example, see the \f(CW\*(C`EV::Loop::Async\*(C'\fR perl module,
4127which uses exactly this technique (which is suited for many high-level
4128languages).
4129.PP
4130The example uses a pthread mutex to protect the loop data, a condition
4131variable to wait for callback invocations, an async watcher to notify the
4132event loop thread and an unspecified mechanism to wake up the main thread.
4133.PP
4134First, you need to associate some data with the event loop:
4135.PP
4136.Vb 6
4137\& typedef struct {
4138\& mutex_t lock; /* global loop lock */
4139\& ev_async async_w;
4140\& thread_t tid;
4141\& cond_t invoke_cv;
4142\& } userdata;
4143\&
4144\& void prepare_loop (EV_P)
4145\& {
4146\& // for simplicity, we use a static userdata struct.
4147\& static userdata u;
4148\&
4149\& ev_async_init (&u\->async_w, async_cb);
4150\& ev_async_start (EV_A_ &u\->async_w);
4151\&
4152\& pthread_mutex_init (&u\->lock, 0);
4153\& pthread_cond_init (&u\->invoke_cv, 0);
4154\&
4155\& // now associate this with the loop
4156\& ev_set_userdata (EV_A_ u);
4157\& ev_set_invoke_pending_cb (EV_A_ l_invoke);
4158\& ev_set_loop_release_cb (EV_A_ l_release, l_acquire);
4159\&
4160\& // then create the thread running ev_loop
4161\& pthread_create (&u\->tid, 0, l_run, EV_A);
4162\& }
4163.Ve
4164.PP
4165The callback for the \f(CW\*(C`ev_async\*(C'\fR watcher does nothing: the watcher is used
4166solely to wake up the event loop so it takes notice of any new watchers
4167that might have been added:
4168.PP
4169.Vb 5
4170\& static void
4171\& async_cb (EV_P_ ev_async *w, int revents)
4172\& {
4173\& // just used for the side effects
4174\& }
4175.Ve
4176.PP
4177The \f(CW\*(C`l_release\*(C'\fR and \f(CW\*(C`l_acquire\*(C'\fR callbacks simply unlock/lock the mutex
4178protecting the loop data, respectively.
4179.PP
4180.Vb 6
4181\& static void
4182\& l_release (EV_P)
4183\& {
4184\& userdata *u = ev_userdata (EV_A);
4185\& pthread_mutex_unlock (&u\->lock);
4186\& }
4187\&
4188\& static void
4189\& l_acquire (EV_P)
4190\& {
4191\& userdata *u = ev_userdata (EV_A);
4192\& pthread_mutex_lock (&u\->lock);
4193\& }
4194.Ve
4195.PP
4196The event loop thread first acquires the mutex, and then jumps straight
4197into \f(CW\*(C`ev_loop\*(C'\fR:
4198.PP
4199.Vb 4
4200\& void *
4201\& l_run (void *thr_arg)
4202\& {
4203\& struct ev_loop *loop = (struct ev_loop *)thr_arg;
4204\&
4205\& l_acquire (EV_A);
4206\& pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
4207\& ev_loop (EV_A_ 0);
4208\& l_release (EV_A);
4209\&
4210\& return 0;
4211\& }
4212.Ve
4213.PP
4214Instead of invoking all pending watchers, the \f(CW\*(C`l_invoke\*(C'\fR callback will
4215signal the main thread via some unspecified mechanism (signals? pipe
4216writes? \f(CW\*(C`Async::Interrupt\*(C'\fR?) and then waits until all pending watchers
4217have been called (in a while loop because a) spurious wakeups are possible
4218and b) skipping inter-thread-communication when there are no pending
4219watchers is very beneficial):
4220.PP
4221.Vb 4
4222\& static void
4223\& l_invoke (EV_P)
4224\& {
4225\& userdata *u = ev_userdata (EV_A);
4226\&
4227\& while (ev_pending_count (EV_A))
4228\& {
4229\& wake_up_other_thread_in_some_magic_or_not_so_magic_way ();
4230\& pthread_cond_wait (&u\->invoke_cv, &u\->lock);
4231\& }
4232\& }
4233.Ve
4234.PP
4235Now, whenever the main thread gets told to invoke pending watchers, it
4236will grab the lock, call \f(CW\*(C`ev_invoke_pending\*(C'\fR and then signal the loop
4237thread to continue:
4238.PP
4239.Vb 4
4240\& static void
4241\& real_invoke_pending (EV_P)
4242\& {
4243\& userdata *u = ev_userdata (EV_A);
4244\&
4245\& pthread_mutex_lock (&u\->lock);
4246\& ev_invoke_pending (EV_A);
4247\& pthread_cond_signal (&u\->invoke_cv);
4248\& pthread_mutex_unlock (&u\->lock);
4249\& }
4250.Ve
4251.PP
4252Whenever you want to start/stop a watcher or do other modifications to an
4253event loop, you will now have to lock:
4254.PP
4255.Vb 2
4256\& ev_timer timeout_watcher;
4257\& userdata *u = ev_userdata (EV_A);
4258\&
4259\& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
4260\&
4261\& pthread_mutex_lock (&u\->lock);
4262\& ev_timer_start (EV_A_ &timeout_watcher);
4263\& ev_async_send (EV_A_ &u\->async_w);
4264\& pthread_mutex_unlock (&u\->lock);
4265.Ve
4266.PP
4267Note that sending the \f(CW\*(C`ev_async\*(C'\fR watcher is required because otherwise
4268an event loop currently blocking in the kernel will have no knowledge
4269about the newly added timer. By waking up the loop it will pick up any new
4270watchers in the next event loop iteration.
4271.PP
3944\fI\s-1COROUTINES\s0\fR 4272\fI\s-1COROUTINES\s0\fR
3945.IX Subsection "COROUTINES" 4273.IX Subsection "COROUTINES"
3946.PP 4274.PP
3947Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): 4275Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"):
3948libev fully supports nesting calls to its functions from different 4276libev fully supports nesting calls to its functions from different
3949coroutines (e.g. you can call \f(CW\*(C`ev_loop\*(C'\fR on the same loop from two 4277coroutines (e.g. you can call \f(CW\*(C`ev_loop\*(C'\fR on the same loop from two
3950different coroutines, and switch freely between both coroutines running the 4278different coroutines, and switch freely between both coroutines running
3951loop, as long as you don't confuse yourself). The only exception is that 4279the loop, as long as you don't confuse yourself). The only exception is
3952you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. 4280that you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks.
3953.PP 4281.PP
3954Care has been taken to ensure that libev does not keep local state inside 4282Care has been taken to ensure that libev does not keep local state inside
3955\&\f(CW\*(C`ev_loop\*(C'\fR, and other calls do not usually allow for coroutine switches as 4283\&\f(CW\*(C`ev_loop\*(C'\fR, and other calls do not usually allow for coroutine switches as
3956they do not call any callbacks. 4284they do not call any callbacks.
3957.Sh "\s-1COMPILER\s0 \s-1WARNINGS\s0" 4285.SS "\s-1COMPILER\s0 \s-1WARNINGS\s0"
3958.IX Subsection "COMPILER WARNINGS" 4286.IX Subsection "COMPILER WARNINGS"
3959Depending on your compiler and compiler settings, you might get no or a 4287Depending on your compiler and compiler settings, you might get no or a
3960lot of warnings when compiling libev code. Some people are apparently 4288lot of warnings when compiling libev code. Some people are apparently
3961scared by this. 4289scared by this.
3962.PP 4290.PP
… …
3979While libev is written to generate as few warnings as possible, 4307While libev is written to generate as few warnings as possible,
3980\&\*(L"warn-free\*(R" code is not a goal, and it is recommended not to build libev 4308\&\*(L"warn-free\*(R" code is not a goal, and it is recommended not to build libev
3981with any compiler warnings enabled unless you are prepared to cope with 4309with any compiler warnings enabled unless you are prepared to cope with
3982them (e.g. by ignoring them). Remember that warnings are just that: 4310them (e.g. by ignoring them). Remember that warnings are just that:
3983warnings, not errors, or proof of bugs. 4311warnings, not errors, or proof of bugs.
3984.Sh "\s-1VALGRIND\s0" 4312.SS "\s-1VALGRIND\s0"
3985.IX Subsection "VALGRIND" 4313.IX Subsection "VALGRIND"
3986Valgrind has a special section here because it is a popular tool that is 4314Valgrind has a special section here because it is a popular tool that is
3987highly useful. Unfortunately, valgrind reports are very hard to interpret. 4315highly useful. Unfortunately, valgrind reports are very hard to interpret.
3988.PP 4316.PP
3989If you think you found a bug (memory leak, uninitialised data access etc.) 4317If you think you found a bug (memory leak, uninitialised data access etc.)
… …
4014.PP 4342.PP
4015If you need, for some reason, empty reports from valgrind for your project 4343If you need, for some reason, empty reports from valgrind for your project
4016I suggest using suppression lists. 4344I suggest using suppression lists.
4017.SH "PORTABILITY NOTES" 4345.SH "PORTABILITY NOTES"
4018.IX Header "PORTABILITY NOTES" 4346.IX Header "PORTABILITY NOTES"
4019.Sh "\s-1WIN32\s0 \s-1PLATFORM\s0 \s-1LIMITATIONS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" 4347.SS "\s-1WIN32\s0 \s-1PLATFORM\s0 \s-1LIMITATIONS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0"
4020.IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" 4348.IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS"
4021Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev 4349Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev
4022requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 4350requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0
4023model. Libev still offers limited functionality on this platform in 4351model. Libev still offers limited functionality on this platform in
4024the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket 4352the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket
… …
4111(another arbitrary limit), but is broken in many versions of the Microsoft 4439(another arbitrary limit), but is broken in many versions of the Microsoft
4112runtime libraries. This might get you to about \f(CW512\fR or \f(CW2048\fR sockets 4440runtime libraries. This might get you to about \f(CW512\fR or \f(CW2048\fR sockets
4113(depending on windows version and/or the phase of the moon). To get more, 4441(depending on windows version and/or the phase of the moon). To get more,
4114you need to wrap all I/O functions and provide your own fd management, but 4442you need to wrap all I/O functions and provide your own fd management, but
4115the cost of calling select (O(nA\*^X)) will likely make this unworkable. 4443the cost of calling select (O(nA\*^X)) will likely make this unworkable.
4116.Sh "\s-1PORTABILITY\s0 \s-1REQUIREMENTS\s0" 4444.SS "\s-1PORTABILITY\s0 \s-1REQUIREMENTS\s0"
4117.IX Subsection "PORTABILITY REQUIREMENTS" 4445.IX Subsection "PORTABILITY REQUIREMENTS"
4118In addition to a working ISO-C implementation and of course the 4446In addition to a working ISO-C implementation and of course the
4119backend-specific APIs, libev relies on a few additional extensions: 4447backend-specific APIs, libev relies on a few additional extensions:
4120.ie n .IP """void (*)(ev_watcher_type *, int revents)""\fR must have compatible calling conventions regardless of \f(CW""ev_watcher_type *""." 4 4448.ie n .IP """void (*)(ev_watcher_type *, int revents)"" must have compatible calling conventions regardless of ""ev_watcher_type *""." 4
4121.el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4 4449.el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4
4122.IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *." 4450.IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *."
4123Libev assumes not only that all watcher pointers have the same internal 4451Libev assumes not only that all watcher pointers have the same internal
4124structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO\s0 C for example), but it also 4452structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO\s0 C for example), but it also
4125assumes that the same (machine) code can be used to call any watcher 4453assumes that the same (machine) code can be used to call any watcher
… …
4157.el .IP "\f(CWdouble\fR must hold a time value in seconds with enough accuracy" 4 4485.el .IP "\f(CWdouble\fR must hold a time value in seconds with enough accuracy" 4
4158.IX Item "double must hold a time value in seconds with enough accuracy" 4486.IX Item "double must hold a time value in seconds with enough accuracy"
4159The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to 4487The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to
4160have at least 51 bits of mantissa (and 9 bits of exponent), which is good 4488have at least 51 bits of mantissa (and 9 bits of exponent), which is good
4161enough for at least into the year 4000. This requirement is fulfilled by 4489enough for at least into the year 4000. This requirement is fulfilled by
4162implementations implementing \s-1IEEE\s0 754 (basically all existing ones). 4490implementations implementing \s-1IEEE\s0 754, which is basically all existing
4491ones. With \s-1IEEE\s0 754 doubles, you get microsecond accuracy until at least
44922200.
4163.PP 4493.PP
4164If you know of other additional requirements drop me a note. 4494If you know of other additional requirements drop me a note.
4165.SH "ALGORITHMIC COMPLEXITIES" 4495.SH "ALGORITHMIC COMPLEXITIES"
4166.IX Header "ALGORITHMIC COMPLEXITIES" 4496.IX Header "ALGORITHMIC COMPLEXITIES"
4167In this section the complexities of (many of) the algorithms used inside 4497In this section the complexities of (many of) the algorithms used inside

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