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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
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130.\} 122.\}
131.rm #[ #] #H #V #F C 123.rm #[ #] #H #V #F C
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 "2009-07-15" "libev-3.7" "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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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), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers
… …
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 236\&\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
245file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events 237file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events
246(\f(CW\*(C`ev_fork\*(C'\fR). 238(\f(CW\*(C`ev_fork\*(C'\fR).
247.PP 239.PP
248It also is quite fast (see this 240It also is quite fast (see this
249benchmark comparing it to libevent 241<benchmark> comparing it to libevent
250for example). 242for example).
251.Sh "\s-1CONVENTIONS\s0" 243.SS "\s-1CONVENTIONS\s0"
252.IX Subsection "CONVENTIONS" 244.IX Subsection "CONVENTIONS"
253Libev is very configurable. In this manual the default (and most common) 245Libev is very configurable. In this manual the default (and most common)
254configuration will be described, which supports multiple event loops. For 246configuration will be described, which supports multiple event loops. For
255more info about various configuration options please have a look at 247more 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 248\&\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 249for 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 250name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`ev_loop *\*(C'\fR) will not have
259this argument. 251this argument.
260.Sh "\s-1TIME\s0 \s-1REPRESENTATION\s0" 252.SS "\s-1TIME\s0 \s-1REPRESENTATION\s0"
261.IX Subsection "TIME REPRESENTATION" 253.IX Subsection "TIME REPRESENTATION"
262Libev represents time as a single floating point number, representing 254Libev represents time as a single floating point number, representing
263the (fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere 255the (fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere
264near the beginning of 1970, details are complicated, don't ask). This 256near 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 257type is called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually
… …
749happily wraps around with enough iterations. 741happily wraps around with enough iterations.
750.Sp 742.Sp
751This value can sometimes be useful as a generation counter of sorts (it 743This 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 744\&\*(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. 745\&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls.
746.IP "unsigned int ev_loop_depth (loop)" 4
747.IX Item "unsigned int ev_loop_depth (loop)"
748Returns the number of times \f(CW\*(C`ev_loop\*(C'\fR was entered minus the number of
749times \f(CW\*(C`ev_loop\*(C'\fR was exited, in other words, the recursion depth.
750.Sp
751Outside \f(CW\*(C`ev_loop\*(C'\fR, this number is zero. In a callback, this number is
752\&\f(CW1\fR, unless \f(CW\*(C`ev_loop\*(C'\fR was invoked recursively (or from another thread),
753in which case it is higher.
754.Sp
755Leaving \f(CW\*(C`ev_loop\*(C'\fR abnormally (setjmp/longjmp, cancelling the thread
756etc.), doesn't count as exit.
754.IP "unsigned int ev_backend (loop)" 4 757.IP "unsigned int ev_backend (loop)" 4
755.IX Item "unsigned int ev_backend (loop)" 758.IX Item "unsigned int ev_backend (loop)"
756Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in 759Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in
757use. 760use.
758.IP "ev_tstamp ev_now (loop)" 4 761.IP "ev_tstamp ev_now (loop)" 4
… …
946.Sp 949.Sp
947By setting a higher \fIio collect interval\fR you allow libev to spend more 950By 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, 951time 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 952at 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 953\&\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. 954introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. The
955sleep time ensures that libev will not poll for I/O events more often then
956once per this interval, on average.
952.Sp 957.Sp
953Likewise, by setting a higher \fItimeout collect interval\fR you allow libev 958Likewise, by setting a higher \fItimeout collect interval\fR you allow libev
954to spend more time collecting timeouts, at the expense of increased 959to spend more time collecting timeouts, at the expense of increased
955latency/jitter/inexactness (the watcher callback will be called 960latency/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 961later). \f(CW\*(C`ev_io\*(C'\fR watchers will not be affected. Setting this to a non-null
… …
958.Sp 963.Sp
959Many (busy) programs can usually benefit by setting the I/O collect 964Many (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 965interval 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 966interactive 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, 967usually 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. 968as this approaches the timing granularity of most systems. Note that if
969you do transactions with the outside world and you can't increase the
970parallelity, then this setting will limit your transaction rate (if you
971need to poll once per transaction and the I/O collect interval is 0.01,
972then you can't do more than 100 transations per second).
964.Sp 973.Sp
965Setting the \fItimeout collect interval\fR can improve the opportunity for 974Setting the \fItimeout collect interval\fR can improve the opportunity for
966saving power, as the program will \*(L"bundle\*(R" timer callback invocations that 975saving 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 976are \*(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 977times 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 978reduce 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. 979they fire on, say, one-second boundaries only.
980.Sp
981Example: we only need 0.1s timeout granularity, and we wish not to poll
982more often than 100 times per second:
983.Sp
984.Vb 2
985\& ev_set_timeout_collect_interval (EV_DEFAULT_UC_ 0.1);
986\& ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
987.Ve
988.IP "ev_invoke_pending (loop)" 4
989.IX Item "ev_invoke_pending (loop)"
990This call will simply invoke all pending watchers while resetting their
991pending state. Normally, \f(CW\*(C`ev_loop\*(C'\fR does this automatically when required,
992but when overriding the invoke callback this call comes handy.
993.IP "int ev_pending_count (loop)" 4
994.IX Item "int ev_pending_count (loop)"
995Returns the number of pending watchers \- zero indicates that no watchers
996are pending.
997.IP "ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(\s-1EV_P\s0))" 4
998.IX Item "ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))"
999This overrides the invoke pending functionality of the loop: Instead of
1000invoking all pending watchers when there are any, \f(CW\*(C`ev_loop\*(C'\fR will call
1001this callback instead. This is useful, for example, when you want to
1002invoke the actual watchers inside another context (another thread etc.).
1003.Sp
1004If you want to reset the callback, use \f(CW\*(C`ev_invoke_pending\*(C'\fR as new
1005callback.
1006.IP "ev_set_loop_release_cb (loop, void (*release)(\s-1EV_P\s0), void (*acquire)(\s-1EV_P\s0))" 4
1007.IX Item "ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P))"
1008Sometimes you want to share the same loop between multiple threads. This
1009can be done relatively simply by putting mutex_lock/unlock calls around
1010each call to a libev function.
1011.Sp
1012However, \f(CW\*(C`ev_loop\*(C'\fR can run an indefinite time, so it is not feasible to
1013wait for it to return. One way around this is to wake up the loop via
1014\&\f(CW\*(C`ev_unloop\*(C'\fR and \f(CW\*(C`av_async_send\*(C'\fR, another way is to set these \fIrelease\fR
1015and \fIacquire\fR callbacks on the loop.
1016.Sp
1017When set, then \f(CW\*(C`release\*(C'\fR will be called just before the thread is
1018suspended waiting for new events, and \f(CW\*(C`acquire\*(C'\fR is called just
1019afterwards.
1020.Sp
1021Ideally, \f(CW\*(C`release\*(C'\fR will just call your mutex_unlock function, and
1022\&\f(CW\*(C`acquire\*(C'\fR will just call the mutex_lock function again.
1023.Sp
1024While event loop modifications are allowed between invocations of
1025\&\f(CW\*(C`release\*(C'\fR and \f(CW\*(C`acquire\*(C'\fR (that's their only purpose after all), no
1026modifications done will affect the event loop, i.e. adding watchers will
1027have no effect on the set of file descriptors being watched, or the time
1028waited. USe an \f(CW\*(C`ev_async\*(C'\fR watcher to wake up \f(CW\*(C`ev_loop\*(C'\fR when you want it
1029to take note of any changes you made.
1030.Sp
1031In theory, threads executing \f(CW\*(C`ev_loop\*(C'\fR will be async-cancel safe between
1032invocations of \f(CW\*(C`release\*(C'\fR and \f(CW\*(C`acquire\*(C'\fR.
1033.Sp
1034See also the locking example in the \f(CW\*(C`THREADS\*(C'\fR section later in this
1035document.
1036.IP "ev_set_userdata (loop, void *data)" 4
1037.IX Item "ev_set_userdata (loop, void *data)"
1038.PD 0
1039.IP "ev_userdata (loop)" 4
1040.IX Item "ev_userdata (loop)"
1041.PD
1042Set and retrieve a single \f(CW\*(C`void *\*(C'\fR associated with a loop. When
1043\&\f(CW\*(C`ev_set_userdata\*(C'\fR has never been called, then \f(CW\*(C`ev_userdata\*(C'\fR returns
1044\&\f(CW0.\fR
1045.Sp
1046These two functions can be used to associate arbitrary data with a loop,
1047and are intended solely for the \f(CW\*(C`invoke_pending_cb\*(C'\fR, \f(CW\*(C`release\*(C'\fR and
1048\&\f(CW\*(C`acquire\*(C'\fR callbacks described above, but of course can be (ab\-)used for
1049any other purpose as well.
971.IP "ev_loop_verify (loop)" 4 1050.IP "ev_loop_verify (loop)" 4
972.IX Item "ev_loop_verify (loop)" 1051.IX Item "ev_loop_verify (loop)"
973This function only does something when \f(CW\*(C`EV_VERIFY\*(C'\fR support has been 1052This 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 1053compiled in, which is the default for non-minimal builds. It tries to go
975through all internal structures and checks them for validity. If anything 1054through all internal structures and checks them for validity. If anything
… …
1124example it might indicate that a fd is readable or writable, and if your 1203example 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 1204callbacks 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 1205the 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 1206programs, though, as the fd could already be closed and reused for another
1128thing, so beware. 1207thing, so beware.
1129.Sh "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" 1208.SS "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0"
1130.IX Subsection "GENERIC WATCHER FUNCTIONS" 1209.IX Subsection "GENERIC WATCHER FUNCTIONS"
1131.ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 1210.ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4
1132.el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 1211.el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4
1133.IX Item "ev_init (ev_TYPE *watcher, callback)" 1212.IX Item "ev_init (ev_TYPE *watcher, callback)"
1134This macro initialises the generic portion of a watcher. The contents 1213This 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 1337returns 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. 1338watcher isn't pending it does nothing and returns \f(CW0\fR.
1260.Sp 1339.Sp
1261Sometimes it can be useful to \*(L"poll\*(R" a watcher instead of waiting for its 1340Sometimes 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. 1341callback 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" 1342.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" 1343.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 1344Each 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 1345and 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 1346to 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 1347don't want to allocate memory and store a pointer to it in that data
… …
1319\& #include <stddef.h> 1398\& #include <stddef.h>
1320\& 1399\&
1321\& static void 1400\& static void
1322\& t1_cb (EV_P_ ev_timer *w, int revents) 1401\& t1_cb (EV_P_ ev_timer *w, int revents)
1323\& { 1402\& {
1324\& struct my_biggy big = (struct my_biggy * 1403\& struct my_biggy big = (struct my_biggy *)
1325\& (((char *)w) \- offsetof (struct my_biggy, t1)); 1404\& (((char *)w) \- offsetof (struct my_biggy, t1));
1326\& } 1405\& }
1327\& 1406\&
1328\& static void 1407\& static void
1329\& t2_cb (EV_P_ ev_timer *w, int revents) 1408\& t2_cb (EV_P_ ev_timer *w, int revents)
1330\& { 1409\& {
1331\& struct my_biggy big = (struct my_biggy * 1410\& struct my_biggy big = (struct my_biggy *)
1332\& (((char *)w) \- offsetof (struct my_biggy, t2)); 1411\& (((char *)w) \- offsetof (struct my_biggy, t2));
1333\& } 1412\& }
1334.Ve 1413.Ve
1335.Sh "\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0" 1414.SS "\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0"
1336.IX Subsection "WATCHER PRIORITY MODELS" 1415.IX Subsection "WATCHER PRIORITY MODELS"
1337Many event loops support \fIwatcher priorities\fR, which are usually small 1416Many event loops support \fIwatcher priorities\fR, which are usually small
1338integers that influence the ordering of event callback invocation 1417integers that influence the ordering of event callback invocation
1339between watchers in some way, all else being equal. 1418between watchers in some way, all else being equal.
1340.PP 1419.PP
… …
1413\& // with the default priority are receiving events. 1492\& // with the default priority are receiving events.
1414\& ev_idle_start (EV_A_ &idle); 1493\& ev_idle_start (EV_A_ &idle);
1415\& } 1494\& }
1416\& 1495\&
1417\& static void 1496\& static void
1418\& idle\-cb (EV_P_ ev_idle *w, int revents) 1497\& idle_cb (EV_P_ ev_idle *w, int revents)
1419\& { 1498\& {
1420\& // actual processing 1499\& // actual processing
1421\& read (STDIN_FILENO, ...); 1500\& read (STDIN_FILENO, ...);
1422\& 1501\&
1423\& // have to start the I/O watcher again, as 1502\& // have to start the I/O watcher again, as
… …
1448watcher is stopped to your hearts content), or \fI[read\-write]\fR, which 1527watcher 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 1528means 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 1529is 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 1530sensible or take immediate effect (or do anything at all), but libev will
1452not crash or malfunction in any way. 1531not crash or malfunction in any way.
1453.ie n .Sh """ev_io"" \- is this file descriptor readable or writable?" 1532.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?" 1533.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?" 1534.IX Subsection "ev_io - is this file descriptor readable or writable?"
1456I/O watchers check whether a file descriptor is readable or writable 1535I/O watchers check whether a file descriptor is readable or writable
1457in each iteration of the event loop, or, more precisely, when reading 1536in 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 1537would not block the process and writing would at least be able to write
1459some data. This behaviour is called level-triggering because you keep 1538some data. This behaviour is called level-triggering because you keep
… …
1587\& ev_io stdin_readable; 1666\& ev_io stdin_readable;
1588\& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); 1667\& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1589\& ev_io_start (loop, &stdin_readable); 1668\& ev_io_start (loop, &stdin_readable);
1590\& ev_loop (loop, 0); 1669\& ev_loop (loop, 0);
1591.Ve 1670.Ve
1592.ie n .Sh """ev_timer"" \- relative and optionally repeating timeouts" 1671.ie n .SS """ev_timer"" \- relative and optionally repeating timeouts"
1593.el .Sh "\f(CWev_timer\fP \- relative and optionally repeating timeouts" 1672.el .SS "\f(CWev_timer\fP \- relative and optionally repeating timeouts"
1594.IX Subsection "ev_timer - relative and optionally repeating timeouts" 1673.IX Subsection "ev_timer - relative and optionally repeating timeouts"
1595Timer watchers are simple relative timers that generate an event after a 1674Timer watchers are simple relative timers that generate an event after a
1596given time, and optionally repeating in regular intervals after that. 1675given time, and optionally repeating in regular intervals after that.
1597.PP 1676.PP
1598The timers are based on real time, that is, if you register an event that 1677The timers are based on real time, that is, if you register an event that
… …
1603.PP 1682.PP
1604The callback is guaranteed to be invoked only \fIafter\fR its timeout has 1683The 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 1684passed (not \fIat\fR, so on systems with very low-resolution clocks this
1606might introduce a small delay). If multiple timers become ready during the 1685might introduce a small delay). If multiple timers become ready during the
1607same loop iteration then the ones with earlier time-out values are invoked 1686same 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 1687before ones of the same priority with later time-out values (but this is
1609callback calls \f(CW\*(C`ev_loop\*(C'\fR recursively). 1688no longer true when a callback calls \f(CW\*(C`ev_loop\*(C'\fR recursively).
1610.PP 1689.PP
1611\fIBe smart about timeouts\fR 1690\fIBe smart about timeouts\fR
1612.IX Subsection "Be smart about timeouts" 1691.IX Subsection "Be smart about timeouts"
1613.PP 1692.PP
1614Many real-world problems involve some kind of timeout, usually for error 1693Many real-world problems involve some kind of timeout, usually for error
… …
1661member and \f(CW\*(C`ev_timer_again\*(C'\fR. 1740member and \f(CW\*(C`ev_timer_again\*(C'\fR.
1662.Sp 1741.Sp
1663At start: 1742At start:
1664.Sp 1743.Sp
1665.Vb 3 1744.Vb 3
1666\& ev_timer_init (timer, callback); 1745\& ev_init (timer, callback);
1667\& timer\->repeat = 60.; 1746\& timer\->repeat = 60.;
1668\& ev_timer_again (loop, timer); 1747\& ev_timer_again (loop, timer);
1669.Ve 1748.Ve
1670.Sp 1749.Sp
1671Each time there is some activity: 1750Each time there is some activity:
… …
1740To start the timer, simply initialise the watcher and set \f(CW\*(C`last_activity\*(C'\fR 1819To 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 1820to 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: 1821callback, which will \*(L"do the right thing\*(R" and start the timer:
1743.Sp 1822.Sp
1744.Vb 3 1823.Vb 3
1745\& ev_timer_init (timer, callback); 1824\& ev_init (timer, callback);
1746\& last_activity = ev_now (loop); 1825\& last_activity = ev_now (loop);
1747\& callback (loop, timer, EV_TIMEOUT); 1826\& callback (loop, timer, EV_TIMEOUT);
1748.Ve 1827.Ve
1749.Sp 1828.Sp
1750And when there is some activity, simply store the current time in 1829And when there is some activity, simply store the current time in
… …
1813.Ve 1892.Ve
1814.PP 1893.PP
1815If the event loop is suspended for a long time, you can also force an 1894If 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 1895update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update
1817()\*(C'\fR. 1896()\*(C'\fR.
1897.PP
1898\fIThe special problems of suspended animation\fR
1899.IX Subsection "The special problems of suspended animation"
1900.PP
1901When you leave the server world it is quite customary to hit machines that
1902can suspend/hibernate \- what happens to the clocks during such a suspend?
1903.PP
1904Some quick tests made with a Linux 2.6.28 indicate that a suspend freezes
1905all processes, while the clocks (\f(CW\*(C`times\*(C'\fR, \f(CW\*(C`CLOCK_MONOTONIC\*(C'\fR) continue
1906to run until the system is suspended, but they will not advance while the
1907system is suspended. That means, on resume, it will be as if the program
1908was frozen for a few seconds, but the suspend time will not be counted
1909towards \f(CW\*(C`ev_timer\*(C'\fR when a monotonic clock source is used. The real time
1910clock advanced as expected, but if it is used as sole clocksource, then a
1911long suspend would be detected as a time jump by libev, and timers would
1912be adjusted accordingly.
1913.PP
1914I would not be surprised to see different behaviour in different between
1915operating systems, \s-1OS\s0 versions or even different hardware.
1916.PP
1917The other form of suspend (job control, or sending a \s-1SIGSTOP\s0) will see a
1918time jump in the monotonic clocks and the realtime clock. If the program
1919is suspended for a very long time, and monotonic clock sources are in use,
1920then you can expect \f(CW\*(C`ev_timer\*(C'\fRs to expire as the full suspension time
1921will be counted towards the timers. When no monotonic clock source is in
1922use, then libev will again assume a timejump and adjust accordingly.
1923.PP
1924It might be beneficial for this latter case to call \f(CW\*(C`ev_suspend\*(C'\fR
1925and \f(CW\*(C`ev_resume\*(C'\fR in code that handles \f(CW\*(C`SIGTSTP\*(C'\fR, to at least get
1926deterministic behaviour in this case (you can do nothing against
1927\&\f(CW\*(C`SIGSTOP\*(C'\fR).
1818.PP 1928.PP
1819\fIWatcher-Specific Functions and Data Members\fR 1929\fIWatcher-Specific Functions and Data Members\fR
1820.IX Subsection "Watcher-Specific Functions and Data Members" 1930.IX Subsection "Watcher-Specific Functions and Data Members"
1821.IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 1931.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)" 1932.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 1957If 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. 1958\&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value.
1849.Sp 1959.Sp
1850This sounds a bit complicated, see \*(L"Be smart about timeouts\*(R", above, for a 1960This sounds a bit complicated, see \*(L"Be smart about timeouts\*(R", above, for a
1851usage example. 1961usage example.
1962.IP "ev_timer_remaining (loop, ev_timer *)" 4
1963.IX Item "ev_timer_remaining (loop, ev_timer *)"
1964Returns the remaining time until a timer fires. If the timer is active,
1965then this time is relative to the current event loop time, otherwise it's
1966the timeout value currently configured.
1967.Sp
1968That is, after an \f(CW\*(C`ev_timer_set (w, 5, 7)\*(C'\fR, \f(CW\*(C`ev_timer_remaining\*(C'\fR returns
1969\&\f(CW5\fR. When the timer is started and one second passes, \f(CW\*(C`ev_timer_remain\*(C'\fR
1970will return \f(CW4\fR. When the timer expires and is restarted, it will return
1971roughly \f(CW7\fR (likely slightly less as callback invocation takes some time,
1972too), and so on.
1852.IP "ev_tstamp repeat [read\-write]" 4 1973.IP "ev_tstamp repeat [read\-write]" 4
1853.IX Item "ev_tstamp repeat [read-write]" 1974.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 1975The 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), 1976or \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. 1977which is also when any modifications are taken into account.
… …
1889\& 2010\&
1890\& // and in some piece of code that gets executed on any "activity": 2011\& // and in some piece of code that gets executed on any "activity":
1891\& // reset the timeout to start ticking again at 10 seconds 2012\& // reset the timeout to start ticking again at 10 seconds
1892\& ev_timer_again (&mytimer); 2013\& ev_timer_again (&mytimer);
1893.Ve 2014.Ve
1894.ie n .Sh """ev_periodic"" \- to cron or not to cron?" 2015.ie n .SS """ev_periodic"" \- to cron or not to cron?"
1895.el .Sh "\f(CWev_periodic\fP \- to cron or not to cron?" 2016.el .SS "\f(CWev_periodic\fP \- to cron or not to cron?"
1896.IX Subsection "ev_periodic - to cron or not to cron?" 2017.IX Subsection "ev_periodic - to cron or not to cron?"
1897Periodic watchers are also timers of a kind, but they are very versatile 2018Periodic watchers are also timers of a kind, but they are very versatile
1898(and unfortunately a bit complex). 2019(and unfortunately a bit complex).
1899.PP 2020.PP
1900Unlike \f(CW\*(C`ev_timer\*(C'\fR, periodic watchers are not based on real time (or 2021Unlike \f(CW\*(C`ev_timer\*(C'\fR, periodic watchers are not based on real time (or
… …
2088\& ev_periodic hourly_tick; 2209\& ev_periodic hourly_tick;
2089\& ev_periodic_init (&hourly_tick, clock_cb, 2210\& ev_periodic_init (&hourly_tick, clock_cb,
2090\& fmod (ev_now (loop), 3600.), 3600., 0); 2211\& fmod (ev_now (loop), 3600.), 3600., 0);
2091\& ev_periodic_start (loop, &hourly_tick); 2212\& ev_periodic_start (loop, &hourly_tick);
2092.Ve 2213.Ve
2093.ie n .Sh """ev_signal"" \- signal me when a signal gets signalled!" 2214.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!" 2215.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!" 2216.IX Subsection "ev_signal - signal me when a signal gets signalled!"
2096Signal watchers will trigger an event when the process receives a specific 2217Signal watchers will trigger an event when the process receives a specific
2097signal one or more times. Even though signals are very asynchronous, libev 2218signal 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 2219will try it's best to deliver signals synchronously, i.e. as part of the
2099normal event processing, like any other event. 2220normal event processing, like any other event.
… …
2143\& 2264\&
2144\& ev_signal signal_watcher; 2265\& ev_signal signal_watcher;
2145\& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); 2266\& ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
2146\& ev_signal_start (loop, &signal_watcher); 2267\& ev_signal_start (loop, &signal_watcher);
2147.Ve 2268.Ve
2148.ie n .Sh """ev_child"" \- watch out for process status changes" 2269.ie n .SS """ev_child"" \- watch out for process status changes"
2149.el .Sh "\f(CWev_child\fP \- watch out for process status changes" 2270.el .SS "\f(CWev_child\fP \- watch out for process status changes"
2150.IX Subsection "ev_child - watch out for process status changes" 2271.IX Subsection "ev_child - watch out for process status changes"
2151Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to 2272Child 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 2273some 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 2274exits). It is permissible to install a child watcher \fIafter\fR the child
2154has been forked (which implies it might have already exited), as long 2275has 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., 2276as 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, 2277forking and then immediately registering a watcher for the child is fine,
2157but forking and registering a watcher a few event loop iterations later is 2278but forking and registering a watcher a few event loop iterations later or
2158not. 2279in the next callback invocation is not.
2159.PP 2280.PP
2160Only the default event loop is capable of handling signals, and therefore 2281Only the default event loop is capable of handling signals, and therefore
2161you can only register child watchers in the default event loop. 2282you can only register child watchers in the default event loop.
2283.PP
2284Due to some design glitches inside libev, child watchers will always be
2285handled at maximum priority (their priority is set to \f(CW\*(C`EV_MAXPRI\*(C'\fR by
2286libev)
2162.PP 2287.PP
2163\fIProcess Interaction\fR 2288\fIProcess Interaction\fR
2164.IX Subsection "Process Interaction" 2289.IX Subsection "Process Interaction"
2165.PP 2290.PP
2166Libev grabs \f(CW\*(C`SIGCHLD\*(C'\fR as soon as the default event loop is 2291Libev grabs \f(CW\*(C`SIGCHLD\*(C'\fR as soon as the default event loop is
… …
2245\& { 2370\& {
2246\& ev_child_init (&cw, child_cb, pid, 0); 2371\& ev_child_init (&cw, child_cb, pid, 0);
2247\& ev_child_start (EV_DEFAULT_ &cw); 2372\& ev_child_start (EV_DEFAULT_ &cw);
2248\& } 2373\& }
2249.Ve 2374.Ve
2250.ie n .Sh """ev_stat"" \- did the file attributes just change?" 2375.ie n .SS """ev_stat"" \- did the file attributes just change?"
2251.el .Sh "\f(CWev_stat\fP \- did the file attributes just change?" 2376.el .SS "\f(CWev_stat\fP \- did the file attributes just change?"
2252.IX Subsection "ev_stat - did the file attributes just change?" 2377.IX Subsection "ev_stat - did the file attributes just change?"
2253This watches a file system path for attribute changes. That is, it calls 2378This 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) 2379\&\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 2380and sees if it changed compared to the last time, invoking the callback if
2256it did. 2381it did.
… …
2470\& ... 2595\& ...
2471\& ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); 2596\& ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);
2472\& ev_stat_start (loop, &passwd); 2597\& ev_stat_start (loop, &passwd);
2473\& ev_timer_init (&timer, timer_cb, 0., 1.02); 2598\& ev_timer_init (&timer, timer_cb, 0., 1.02);
2474.Ve 2599.Ve
2475.ie n .Sh """ev_idle"" \- when you've got nothing better to do..." 2600.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..." 2601.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..." 2602.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 2603Idle watchers trigger events when no other events of the same or higher
2479priority are pending (prepare, check and other idle watchers do not count 2604priority are pending (prepare, check and other idle watchers do not count
2480as receiving \*(L"events\*(R"). 2605as receiving \*(L"events\*(R").
2481.PP 2606.PP
… …
2517\& // no longer anything immediate to do. 2642\& // no longer anything immediate to do.
2518\& } 2643\& }
2519\& 2644\&
2520\& ev_idle *idle_watcher = malloc (sizeof (ev_idle)); 2645\& ev_idle *idle_watcher = malloc (sizeof (ev_idle));
2521\& ev_idle_init (idle_watcher, idle_cb); 2646\& ev_idle_init (idle_watcher, idle_cb);
2522\& ev_idle_start (loop, idle_cb); 2647\& ev_idle_start (loop, idle_watcher);
2523.Ve 2648.Ve
2524.ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!" 2649.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!" 2650.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!" 2651.IX Subsection "ev_prepare and ev_check - customise your event loop!"
2527Prepare and check watchers are usually (but not always) used in pairs: 2652Prepare and check watchers are usually (but not always) used in pairs:
2528prepare watchers get invoked before the process blocks and check watchers 2653prepare watchers get invoked before the process blocks and check watchers
2529afterwards. 2654afterwards.
2530.PP 2655.PP
… …
2620\& struct pollfd fds [nfd]; 2745\& struct pollfd fds [nfd];
2621\& // actual code will need to loop here and realloc etc. 2746\& // actual code will need to loop here and realloc etc.
2622\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); 2747\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
2623\& 2748\&
2624\& /* the callback is illegal, but won\*(Aqt be called as we stop during check */ 2749\& /* the callback is illegal, but won\*(Aqt be called as we stop during check */
2625\& ev_timer_init (&tw, 0, timeout * 1e\-3); 2750\& ev_timer_init (&tw, 0, timeout * 1e\-3, 0.);
2626\& ev_timer_start (loop, &tw); 2751\& ev_timer_start (loop, &tw);
2627\& 2752\&
2628\& // create one ev_io per pollfd 2753\& // create one ev_io per pollfd
2629\& for (int i = 0; i < nfd; ++i) 2754\& for (int i = 0; i < nfd; ++i)
2630\& { 2755\& {
… …
2721\& ev_io_stop (EV_A_ iow [n]); 2846\& ev_io_stop (EV_A_ iow [n]);
2722\& 2847\&
2723\& return got_events; 2848\& return got_events;
2724\& } 2849\& }
2725.Ve 2850.Ve
2726.ie n .Sh """ev_embed"" \- when one backend isn't enough..." 2851.ie n .SS """ev_embed"" \- when one backend isn't enough..."
2727.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." 2852.el .SS "\f(CWev_embed\fP \- when one backend isn't enough..."
2728.IX Subsection "ev_embed - when one backend isn't enough..." 2853.IX Subsection "ev_embed - when one backend isn't enough..."
2729This is a rather advanced watcher type that lets you embed one event loop 2854This 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 2855into 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 2856loop, other types of watchers might be handled in a delayed or incorrect
2732fashion and must not be used). 2857fashion and must not be used).
… …
2854\& if (!loop_socket) 2979\& if (!loop_socket)
2855\& loop_socket = loop; 2980\& loop_socket = loop;
2856\& 2981\&
2857\& // now use loop_socket for all sockets, and loop for everything else 2982\& // now use loop_socket for all sockets, and loop for everything else
2858.Ve 2983.Ve
2859.ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork" 2984.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" 2985.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" 2986.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 2987Fork 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 2988whoever 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 2989\&\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, 2990event 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 3031.IP "ev_fork_init (ev_signal *, callback)" 4
2907.IX Item "ev_fork_init (ev_signal *, callback)" 3032.IX Item "ev_fork_init (ev_signal *, callback)"
2908Initialises and configures the fork watcher \- it has no parameters of any 3033Initialises 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, 3034kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless,
2910believe me. 3035believe me.
2911.ie n .Sh """ev_async"" \- how to wake up another event loop" 3036.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" 3037.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" 3038.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 3039In 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 3040asynchronous sources such as signal handlers (as opposed to multiple event
2916loops \- those are of course safe to use in different threads). 3041loops \- those are of course safe to use in different threads).
2917.PP 3042.PP
… …
3155need one additional pointer for context. If you need support for other 3280need one additional pointer for context. If you need support for other
3156types of functors please contact the author (preferably after implementing 3281types of functors please contact the author (preferably after implementing
3157it). 3282it).
3158.PP 3283.PP
3159Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: 3284Here 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 3285.ie n .IP """ev::READ"", ""ev::WRITE"" etc." 4
3161.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 3286.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4
3162.IX Item "ev::READ, ev::WRITE etc." 3287.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. 3288These are just enum values with the same values as the \f(CW\*(C`EV_READ\*(C'\fR etc.
3164macros from \fIev.h\fR. 3289macros from \fIev.h\fR.
3165.ie n .IP """ev::tstamp""\fR, \f(CW""ev::now""" 4 3290.ie n .IP """ev::tstamp"", ""ev::now""" 4
3166.el .IP "\f(CWev::tstamp\fR, \f(CWev::now\fR" 4 3291.el .IP "\f(CWev::tstamp\fR, \f(CWev::now\fR" 4
3167.IX Item "ev::tstamp, ev::now" 3292.IX Item "ev::tstamp, ev::now"
3168Aliases to the same types/functions as with the \f(CW\*(C`ev_\*(C'\fR prefix. 3293Aliases 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 3294.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 3295.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." 3296.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 3297For 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 3298the 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 3299which 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 3409Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the
3285constructor already stores the event loop. 3410constructor already stores the event loop.
3286.IP "w\->stop ()" 4 3411.IP "w\->stop ()" 4
3287.IX Item "w->stop ()" 3412.IX Item "w->stop ()"
3288Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. 3413Stops 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 3414.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 3415.el .IP "w\->again () (\f(CWev::timer\fR, \f(CWev::periodic\fR only)" 4
3291.IX Item "w->again () (ev::timer, ev::periodic only)" 3416.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 3417For \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. 3418\&\f(CW\*(C`ev_TYPE_again\*(C'\fR function.
3294.ie n .IP "w\->sweep () (""ev::embed"" only)" 4 3419.ie n .IP "w\->sweep () (""ev::embed"" only)" 4
… …
3369of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) 3494of 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. 3495functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument.
3371.PP 3496.PP
3372To make it easier to write programs that cope with either variant, the 3497To make it easier to write programs that cope with either variant, the
3373following macros are defined: 3498following macros are defined:
3374.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4 3499.ie n .IP """EV_A"", ""EV_A_""" 4
3375.el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4 3500.el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4
3376.IX Item "EV_A, EV_A_" 3501.IX Item "EV_A, EV_A_"
3377This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev 3502This 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, 3503loop 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: 3504\&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example:
… …
3384\& ev_loop (EV_A_ 0); 3509\& ev_loop (EV_A_ 0);
3385.Ve 3510.Ve
3386.Sp 3511.Sp
3387It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope, 3512It 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. 3513which is often provided by the following macro.
3389.ie n .IP """EV_P""\fR, \f(CW""EV_P_""" 4 3514.ie n .IP """EV_P"", ""EV_P_""" 4
3390.el .IP "\f(CWEV_P\fR, \f(CWEV_P_\fR" 4 3515.el .IP "\f(CWEV_P\fR, \f(CWEV_P_\fR" 4
3391.IX Item "EV_P, EV_P_" 3516.IX Item "EV_P, EV_P_"
3392This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev 3517This 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, 3518loop 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: 3519\&\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) 3526\& static void cb (EV_P_ ev_timer *w, int revents)
3402.Ve 3527.Ve
3403.Sp 3528.Sp
3404It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite 3529It 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. 3530suitable for use with \f(CW\*(C`EV_A\*(C'\fR.
3406.ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4 3531.ie n .IP """EV_DEFAULT"", ""EV_DEFAULT_""" 4
3407.el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 3532.el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4
3408.IX Item "EV_DEFAULT, EV_DEFAULT_" 3533.IX Item "EV_DEFAULT, EV_DEFAULT_"
3409Similar to the other two macros, this gives you the value of the default 3534Similar to the other two macros, this gives you the value of the default
3410loop, if multiple loops are supported (\*(L"ev loop default\*(R"). 3535loop, if multiple loops are supported (\*(L"ev loop default\*(R").
3411.ie n .IP """EV_DEFAULT_UC""\fR, \f(CW""EV_DEFAULT_UC_""" 4 3536.ie n .IP """EV_DEFAULT_UC"", ""EV_DEFAULT_UC_""" 4
3412.el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 3537.el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4
3413.IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" 3538.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 3539Usage 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 3540default 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 3541is undefined when the default loop has not been initialised by a previous
… …
3444.PP 3569.PP
3445The goal is to enable you to just copy the necessary files into your 3570The 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 3571source 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 3572you can easily upgrade by simply copying (or having a checked-out copy of
3448libev somewhere in your source tree). 3573libev somewhere in your source tree).
3449.Sh "\s-1FILESETS\s0" 3574.SS "\s-1FILESETS\s0"
3450.IX Subsection "FILESETS" 3575.IX Subsection "FILESETS"
3451Depending on what features you need you need to include one or more sets of files 3576Depending on what features you need you need to include one or more sets of files
3452in your application. 3577in your application.
3453.PP 3578.PP
3454\fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR 3579\fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR
… …
3533For this of course you need the m4 file: 3658For this of course you need the m4 file:
3534.PP 3659.PP
3535.Vb 1 3660.Vb 1
3536\& libev.m4 3661\& libev.m4
3537.Ve 3662.Ve
3538.Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" 3663.SS "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0"
3539.IX Subsection "PREPROCESSOR SYMBOLS/MACROS" 3664.IX Subsection "PREPROCESSOR SYMBOLS/MACROS"
3540Libev can be configured via a variety of preprocessor symbols you have to 3665Libev 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 3666define before including any of its files. The default in the absence of
3542autoconf is documented for every option. 3667autoconf is documented for every option.
3543.IP "\s-1EV_STANDALONE\s0" 4 3668.IP "\s-1EV_STANDALONE\s0" 4
… …
3742If undefined or defined to be \f(CW1\fR, then async watchers are supported. If 3867If undefined or defined to be \f(CW1\fR, then async watchers are supported. If
3743defined to be \f(CW0\fR, then they are not. 3868defined to be \f(CW0\fR, then they are not.
3744.IP "\s-1EV_MINIMAL\s0" 4 3869.IP "\s-1EV_MINIMAL\s0" 4
3745.IX Item "EV_MINIMAL" 3870.IX Item "EV_MINIMAL"
3746If you need to shave off some kilobytes of code at the expense of some 3871If 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 3872speed (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 3873is used to override some inlining decisions, saves roughly 30% code size
3749much smaller 2\-heap for timer management over the default 4\-heap. 3874on amd64. It also selects a much smaller 2\-heap for timer management over
3875the default 4\-heap.
3876.Sp
3877You can save even more by disabling watcher types you do not need
3878and setting \f(CW\*(C`EV_MAXPRI\*(C'\fR == \f(CW\*(C`EV_MINPRI\*(C'\fR. Also, disabling \f(CW\*(C`assert\*(C'\fR
3879(\f(CW\*(C`\-DNDEBUG\*(C'\fR) will usually reduce code size a lot.
3880.Sp
3881Defining \f(CW\*(C`EV_MINIMAL\*(C'\fR to \f(CW2\fR will additionally reduce the core \s-1API\s0 to
3882provide a bare-bones event library. See \f(CW\*(C`ev.h\*(C'\fR for details on what parts
3883of the \s-1API\s0 are still available, and do not complain if this subset changes
3884over time.
3750.IP "\s-1EV_PID_HASHSIZE\s0" 4 3885.IP "\s-1EV_PID_HASHSIZE\s0" 4
3751.IX Item "EV_PID_HASHSIZE" 3886.IX Item "EV_PID_HASHSIZE"
3752\&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by 3887\&\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 3888pid. 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 3889than 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 3953and 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 3954definition and a statement, respectively. See the \fIev.h\fR header file for
3820their default definitions. One possible use for overriding these is to 3955their 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 3956avoid 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+. 3957method calls instead of plain function calls in \*(C+.
3823.Sh "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" 3958.SS "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0"
3824.IX Subsection "EXPORTED API SYMBOLS" 3959.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 3960If 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 3961exported symbols, you can use the provided \fISymbol.*\fR files which list
3827all public symbols, one per line: 3962all public symbols, one per line:
3828.PP 3963.PP
… …
3848\& #define ev_backend myprefix_ev_backend 3983\& #define ev_backend myprefix_ev_backend
3849\& #define ev_check_start myprefix_ev_check_start 3984\& #define ev_check_start myprefix_ev_check_start
3850\& #define ev_check_stop myprefix_ev_check_stop 3985\& #define ev_check_stop myprefix_ev_check_stop
3851\& ... 3986\& ...
3852.Ve 3987.Ve
3853.Sh "\s-1EXAMPLES\s0" 3988.SS "\s-1EXAMPLES\s0"
3854.IX Subsection "EXAMPLES" 3989.IX Subsection "EXAMPLES"
3855For a real-world example of a program the includes libev 3990For a real-world example of a program the includes libev
3856verbatim, you can have a look at the \s-1EV\s0 perl module 3991verbatim, 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 3992(<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 3993the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public
… …
3883\& #include "ev_cpp.h" 4018\& #include "ev_cpp.h"
3884\& #include "ev.c" 4019\& #include "ev.c"
3885.Ve 4020.Ve
3886.SH "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" 4021.SH "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES"
3887.IX Header "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" 4022.IX Header "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES"
3888.Sh "\s-1THREADS\s0 \s-1AND\s0 \s-1COROUTINES\s0" 4023.SS "\s-1THREADS\s0 \s-1AND\s0 \s-1COROUTINES\s0"
3889.IX Subsection "THREADS AND COROUTINES" 4024.IX Subsection "THREADS AND COROUTINES"
3890\fI\s-1THREADS\s0\fR 4025\fI\s-1THREADS\s0\fR
3891.IX Subsection "THREADS" 4026.IX Subsection "THREADS"
3892.PP 4027.PP
3893All libev functions are reentrant and thread-safe unless explicitly 4028All libev functions are reentrant and thread-safe unless explicitly
… …
3939An example use would be to communicate signals or other events that only 4074An example use would be to communicate signals or other events that only
3940work in the default loop by registering the signal watcher with the 4075work 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 4076default 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. 4077watcher callback into the event loop interested in the signal.
3943.PP 4078.PP
4079\s-1THREAD\s0 \s-1LOCKING\s0 \s-1EXAMPLE\s0
4080.IX Subsection "THREAD LOCKING EXAMPLE"
4081.PP
4082Here is a fictitious example of how to run an event loop in a different
4083thread than where callbacks are being invoked and watchers are
4084created/added/removed.
4085.PP
4086For a real-world example, see the \f(CW\*(C`EV::Loop::Async\*(C'\fR perl module,
4087which uses exactly this technique (which is suited for many high-level
4088languages).
4089.PP
4090The example uses a pthread mutex to protect the loop data, a condition
4091variable to wait for callback invocations, an async watcher to notify the
4092event loop thread and an unspecified mechanism to wake up the main thread.
4093.PP
4094First, you need to associate some data with the event loop:
4095.PP
4096.Vb 6
4097\& typedef struct {
4098\& mutex_t lock; /* global loop lock */
4099\& ev_async async_w;
4100\& thread_t tid;
4101\& cond_t invoke_cv;
4102\& } userdata;
4103\&
4104\& void prepare_loop (EV_P)
4105\& {
4106\& // for simplicity, we use a static userdata struct.
4107\& static userdata u;
4108\&
4109\& ev_async_init (&u\->async_w, async_cb);
4110\& ev_async_start (EV_A_ &u\->async_w);
4111\&
4112\& pthread_mutex_init (&u\->lock, 0);
4113\& pthread_cond_init (&u\->invoke_cv, 0);
4114\&
4115\& // now associate this with the loop
4116\& ev_set_userdata (EV_A_ u);
4117\& ev_set_invoke_pending_cb (EV_A_ l_invoke);
4118\& ev_set_loop_release_cb (EV_A_ l_release, l_acquire);
4119\&
4120\& // then create the thread running ev_loop
4121\& pthread_create (&u\->tid, 0, l_run, EV_A);
4122\& }
4123.Ve
4124.PP
4125The callback for the \f(CW\*(C`ev_async\*(C'\fR watcher does nothing: the watcher is used
4126solely to wake up the event loop so it takes notice of any new watchers
4127that might have been added:
4128.PP
4129.Vb 5
4130\& static void
4131\& async_cb (EV_P_ ev_async *w, int revents)
4132\& {
4133\& // just used for the side effects
4134\& }
4135.Ve
4136.PP
4137The \f(CW\*(C`l_release\*(C'\fR and \f(CW\*(C`l_acquire\*(C'\fR callbacks simply unlock/lock the mutex
4138protecting the loop data, respectively.
4139.PP
4140.Vb 6
4141\& static void
4142\& l_release (EV_P)
4143\& {
4144\& userdata *u = ev_userdata (EV_A);
4145\& pthread_mutex_unlock (&u\->lock);
4146\& }
4147\&
4148\& static void
4149\& l_acquire (EV_P)
4150\& {
4151\& userdata *u = ev_userdata (EV_A);
4152\& pthread_mutex_lock (&u\->lock);
4153\& }
4154.Ve
4155.PP
4156The event loop thread first acquires the mutex, and then jumps straight
4157into \f(CW\*(C`ev_loop\*(C'\fR:
4158.PP
4159.Vb 4
4160\& void *
4161\& l_run (void *thr_arg)
4162\& {
4163\& struct ev_loop *loop = (struct ev_loop *)thr_arg;
4164\&
4165\& l_acquire (EV_A);
4166\& pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
4167\& ev_loop (EV_A_ 0);
4168\& l_release (EV_A);
4169\&
4170\& return 0;
4171\& }
4172.Ve
4173.PP
4174Instead of invoking all pending watchers, the \f(CW\*(C`l_invoke\*(C'\fR callback will
4175signal the main thread via some unspecified mechanism (signals? pipe
4176writes? \f(CW\*(C`Async::Interrupt\*(C'\fR?) and then waits until all pending watchers
4177have been called (in a while loop because a) spurious wakeups are possible
4178and b) skipping inter-thread-communication when there are no pending
4179watchers is very beneficial):
4180.PP
4181.Vb 4
4182\& static void
4183\& l_invoke (EV_P)
4184\& {
4185\& userdata *u = ev_userdata (EV_A);
4186\&
4187\& while (ev_pending_count (EV_A))
4188\& {
4189\& wake_up_other_thread_in_some_magic_or_not_so_magic_way ();
4190\& pthread_cond_wait (&u\->invoke_cv, &u\->lock);
4191\& }
4192\& }
4193.Ve
4194.PP
4195Now, whenever the main thread gets told to invoke pending watchers, it
4196will grab the lock, call \f(CW\*(C`ev_invoke_pending\*(C'\fR and then signal the loop
4197thread to continue:
4198.PP
4199.Vb 4
4200\& static void
4201\& real_invoke_pending (EV_P)
4202\& {
4203\& userdata *u = ev_userdata (EV_A);
4204\&
4205\& pthread_mutex_lock (&u\->lock);
4206\& ev_invoke_pending (EV_A);
4207\& pthread_cond_signal (&u\->invoke_cv);
4208\& pthread_mutex_unlock (&u\->lock);
4209\& }
4210.Ve
4211.PP
4212Whenever you want to start/stop a watcher or do other modifications to an
4213event loop, you will now have to lock:
4214.PP
4215.Vb 2
4216\& ev_timer timeout_watcher;
4217\& userdata *u = ev_userdata (EV_A);
4218\&
4219\& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
4220\&
4221\& pthread_mutex_lock (&u\->lock);
4222\& ev_timer_start (EV_A_ &timeout_watcher);
4223\& ev_async_send (EV_A_ &u\->async_w);
4224\& pthread_mutex_unlock (&u\->lock);
4225.Ve
4226.PP
4227Note that sending the \f(CW\*(C`ev_async\*(C'\fR watcher is required because otherwise
4228an event loop currently blocking in the kernel will have no knowledge
4229about the newly added timer. By waking up the loop it will pick up any new
4230watchers in the next event loop iteration.
4231.PP
3944\fI\s-1COROUTINES\s0\fR 4232\fI\s-1COROUTINES\s0\fR
3945.IX Subsection "COROUTINES" 4233.IX Subsection "COROUTINES"
3946.PP 4234.PP
3947Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): 4235Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"):
3948libev fully supports nesting calls to its functions from different 4236libev 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 4237coroutines (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 4238different coroutines, and switch freely between both coroutines running
3951loop, as long as you don't confuse yourself). The only exception is that 4239the 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. 4240that you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks.
3953.PP 4241.PP
3954Care has been taken to ensure that libev does not keep local state inside 4242Care 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 4243\&\f(CW\*(C`ev_loop\*(C'\fR, and other calls do not usually allow for coroutine switches as
3956they do not call any callbacks. 4244they do not call any callbacks.
3957.Sh "\s-1COMPILER\s0 \s-1WARNINGS\s0" 4245.SS "\s-1COMPILER\s0 \s-1WARNINGS\s0"
3958.IX Subsection "COMPILER WARNINGS" 4246.IX Subsection "COMPILER WARNINGS"
3959Depending on your compiler and compiler settings, you might get no or a 4247Depending on your compiler and compiler settings, you might get no or a
3960lot of warnings when compiling libev code. Some people are apparently 4248lot of warnings when compiling libev code. Some people are apparently
3961scared by this. 4249scared by this.
3962.PP 4250.PP
… …
3979While libev is written to generate as few warnings as possible, 4267While 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 4268\&\*(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 4269with any compiler warnings enabled unless you are prepared to cope with
3982them (e.g. by ignoring them). Remember that warnings are just that: 4270them (e.g. by ignoring them). Remember that warnings are just that:
3983warnings, not errors, or proof of bugs. 4271warnings, not errors, or proof of bugs.
3984.Sh "\s-1VALGRIND\s0" 4272.SS "\s-1VALGRIND\s0"
3985.IX Subsection "VALGRIND" 4273.IX Subsection "VALGRIND"
3986Valgrind has a special section here because it is a popular tool that is 4274Valgrind has a special section here because it is a popular tool that is
3987highly useful. Unfortunately, valgrind reports are very hard to interpret. 4275highly useful. Unfortunately, valgrind reports are very hard to interpret.
3988.PP 4276.PP
3989If you think you found a bug (memory leak, uninitialised data access etc.) 4277If you think you found a bug (memory leak, uninitialised data access etc.)
… …
4014.PP 4302.PP
4015If you need, for some reason, empty reports from valgrind for your project 4303If you need, for some reason, empty reports from valgrind for your project
4016I suggest using suppression lists. 4304I suggest using suppression lists.
4017.SH "PORTABILITY NOTES" 4305.SH "PORTABILITY NOTES"
4018.IX Header "PORTABILITY NOTES" 4306.IX Header "PORTABILITY NOTES"
4019.Sh "\s-1WIN32\s0 \s-1PLATFORM\s0 \s-1LIMITATIONS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" 4307.SS "\s-1WIN32\s0 \s-1PLATFORM\s0 \s-1LIMITATIONS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0"
4020.IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" 4308.IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS"
4021Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev 4309Win32 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 4310requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0
4023model. Libev still offers limited functionality on this platform in 4311model. 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 4312the 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 4399(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 4400runtime 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, 4401(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 4402you 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. 4403the cost of calling select (O(nA\*^X)) will likely make this unworkable.
4116.Sh "\s-1PORTABILITY\s0 \s-1REQUIREMENTS\s0" 4404.SS "\s-1PORTABILITY\s0 \s-1REQUIREMENTS\s0"
4117.IX Subsection "PORTABILITY REQUIREMENTS" 4405.IX Subsection "PORTABILITY REQUIREMENTS"
4118In addition to a working ISO-C implementation and of course the 4406In addition to a working ISO-C implementation and of course the
4119backend-specific APIs, libev relies on a few additional extensions: 4407backend-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 4408.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 4409.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 *." 4410.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 4411Libev 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 4412structure (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 4413assumes 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 4445.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" 4446.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 4447The 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 4448have 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 4449enough for at least into the year 4000. This requirement is fulfilled by
4162implementations implementing \s-1IEEE\s0 754 (basically all existing ones). 4450implementations implementing \s-1IEEE\s0 754, which is basically all existing
4451ones. With \s-1IEEE\s0 754 doubles, you get microsecond accuracy until at least
44522200.
4163.PP 4453.PP
4164If you know of other additional requirements drop me a note. 4454If you know of other additional requirements drop me a note.
4165.SH "ALGORITHMIC COMPLEXITIES" 4455.SH "ALGORITHMIC COMPLEXITIES"
4166.IX Header "ALGORITHMIC COMPLEXITIES" 4456.IX Header "ALGORITHMIC COMPLEXITIES"
4167In this section the complexities of (many of) the algorithms used inside 4457In this section the complexities of (many of) the algorithms used inside

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