… | |
… | |
127 | .\} |
127 | .\} |
128 | .rm #[ #] #H #V #F C |
128 | .rm #[ #] #H #V #F C |
129 | .\" ======================================================================== |
129 | .\" ======================================================================== |
130 | .\" |
130 | .\" |
131 | .IX Title ""<STANDARD INPUT>" 1" |
131 | .IX Title ""<STANDARD INPUT>" 1" |
132 | .TH "<STANDARD INPUT>" 1 "2007-12-08" "perl v5.8.8" "User Contributed Perl Documentation" |
132 | .TH "<STANDARD INPUT>" 1 "2007-12-12" "perl v5.8.8" "User Contributed Perl Documentation" |
133 | .SH "NAME" |
133 | .SH "NAME" |
134 | libev \- a high performance full\-featured event loop written in C |
134 | libev \- a high performance full\-featured event loop written in C |
135 | .SH "SYNOPSIS" |
135 | .SH "SYNOPSIS" |
136 | .IX Header "SYNOPSIS" |
136 | .IX Header "SYNOPSIS" |
137 | .Vb 1 |
137 | .Vb 1 |
… | |
… | |
259 | .IX Item "int ev_version_major ()" |
259 | .IX Item "int ev_version_major ()" |
260 | .PD 0 |
260 | .PD 0 |
261 | .IP "int ev_version_minor ()" 4 |
261 | .IP "int ev_version_minor ()" 4 |
262 | .IX Item "int ev_version_minor ()" |
262 | .IX Item "int ev_version_minor ()" |
263 | .PD |
263 | .PD |
264 | You can find out the major and minor version numbers of the library |
264 | You can find out the major and minor \s-1ABI\s0 version numbers of the library |
265 | you linked against by calling the functions \f(CW\*(C`ev_version_major\*(C'\fR and |
265 | you linked against by calling the functions \f(CW\*(C`ev_version_major\*(C'\fR and |
266 | \&\f(CW\*(C`ev_version_minor\*(C'\fR. If you want, you can compare against the global |
266 | \&\f(CW\*(C`ev_version_minor\*(C'\fR. If you want, you can compare against the global |
267 | symbols \f(CW\*(C`EV_VERSION_MAJOR\*(C'\fR and \f(CW\*(C`EV_VERSION_MINOR\*(C'\fR, which specify the |
267 | symbols \f(CW\*(C`EV_VERSION_MAJOR\*(C'\fR and \f(CW\*(C`EV_VERSION_MINOR\*(C'\fR, which specify the |
268 | version of the library your program was compiled against. |
268 | version of the library your program was compiled against. |
269 | .Sp |
269 | .Sp |
|
|
270 | These version numbers refer to the \s-1ABI\s0 version of the library, not the |
|
|
271 | release version. |
|
|
272 | .Sp |
270 | Usually, it's a good idea to terminate if the major versions mismatch, |
273 | Usually, it's a good idea to terminate if the major versions mismatch, |
271 | as this indicates an incompatible change. Minor versions are usually |
274 | as this indicates an incompatible change. Minor versions are usually |
272 | compatible to older versions, so a larger minor version alone is usually |
275 | compatible to older versions, so a larger minor version alone is usually |
273 | not a problem. |
276 | not a problem. |
274 | .Sp |
277 | .Sp |
275 | Example: Make sure we haven't accidentally been linked against the wrong |
278 | Example: Make sure we haven't accidentally been linked against the wrong |
276 | version. |
279 | version. |
… | |
… | |
1062 | If you cannot run the fd in non-blocking mode (for example you should not |
1065 | If you cannot run the fd in non-blocking mode (for example you should not |
1063 | play around with an Xlib connection), then you have to seperately re-test |
1066 | play around with an Xlib connection), then you have to seperately re-test |
1064 | whether a file descriptor is really ready with a known-to-be good interface |
1067 | whether a file descriptor is really ready with a known-to-be good interface |
1065 | such as poll (fortunately in our Xlib example, Xlib already does this on |
1068 | such as poll (fortunately in our Xlib example, Xlib already does this on |
1066 | its own, so its quite safe to use). |
1069 | its own, so its quite safe to use). |
|
|
1070 | .PP |
|
|
1071 | \fIThe special problem of disappearing file descriptors\fR |
|
|
1072 | .IX Subsection "The special problem of disappearing file descriptors" |
|
|
1073 | .PP |
|
|
1074 | Some backends (e.g kqueue, epoll) need to be told about closing a file |
|
|
1075 | descriptor (either by calling \f(CW\*(C`close\*(C'\fR explicitly or by any other means, |
|
|
1076 | such as \f(CW\*(C`dup\*(C'\fR). The reason is that you register interest in some file |
|
|
1077 | descriptor, but when it goes away, the operating system will silently drop |
|
|
1078 | this interest. If another file descriptor with the same number then is |
|
|
1079 | registered with libev, there is no efficient way to see that this is, in |
|
|
1080 | fact, a different file descriptor. |
|
|
1081 | .PP |
|
|
1082 | To avoid having to explicitly tell libev about such cases, libev follows |
|
|
1083 | the following policy: Each time \f(CW\*(C`ev_io_set\*(C'\fR is being called, libev |
|
|
1084 | will assume that this is potentially a new file descriptor, otherwise |
|
|
1085 | it is assumed that the file descriptor stays the same. That means that |
|
|
1086 | you \fIhave\fR to call \f(CW\*(C`ev_io_set\*(C'\fR (or \f(CW\*(C`ev_io_init\*(C'\fR) when you change the |
|
|
1087 | descriptor even if the file descriptor number itself did not change. |
|
|
1088 | .PP |
|
|
1089 | This is how one would do it normally anyway, the important point is that |
|
|
1090 | the libev application should not optimise around libev but should leave |
|
|
1091 | optimisations to libev. |
1067 | .IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 |
1092 | .IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 |
1068 | .IX Item "ev_io_init (ev_io *, callback, int fd, int events)" |
1093 | .IX Item "ev_io_init (ev_io *, callback, int fd, int events)" |
1069 | .PD 0 |
1094 | .PD 0 |
1070 | .IP "ev_io_set (ev_io *, int fd, int events)" 4 |
1095 | .IP "ev_io_set (ev_io *, int fd, int events)" 4 |
1071 | .IX Item "ev_io_set (ev_io *, int fd, int events)" |
1096 | .IX Item "ev_io_set (ev_io *, int fd, int events)" |
… | |
… | |
1235 | but on wallclock time (absolute time). You can tell a periodic watcher |
1260 | but on wallclock time (absolute time). You can tell a periodic watcher |
1236 | to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a |
1261 | to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a |
1237 | periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now () |
1262 | periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now () |
1238 | + 10.\*(C'\fR) and then reset your system clock to the last year, then it will |
1263 | + 10.\*(C'\fR) and then reset your system clock to the last year, then it will |
1239 | take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger |
1264 | take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger |
1240 | roughly 10 seconds later and of course not if you reset your system time |
1265 | roughly 10 seconds later). |
1241 | again). |
|
|
1242 | .PP |
1266 | .PP |
1243 | They can also be used to implement vastly more complex timers, such as |
1267 | They can also be used to implement vastly more complex timers, such as |
1244 | triggering an event on eahc midnight, local time. |
1268 | triggering an event on each midnight, local time or other, complicated, |
|
|
1269 | rules. |
1245 | .PP |
1270 | .PP |
1246 | As with timers, the callback is guarenteed to be invoked only when the |
1271 | As with timers, the callback is guarenteed to be invoked only when the |
1247 | time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready |
1272 | time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready |
1248 | during the same loop iteration then order of execution is undefined. |
1273 | during the same loop iteration then order of execution is undefined. |
1249 | .IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4 |
1274 | .IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4 |
… | |
… | |
1253 | .IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" |
1278 | .IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" |
1254 | .PD |
1279 | .PD |
1255 | Lots of arguments, lets sort it out... There are basically three modes of |
1280 | Lots of arguments, lets sort it out... There are basically three modes of |
1256 | operation, and we will explain them from simplest to complex: |
1281 | operation, and we will explain them from simplest to complex: |
1257 | .RS 4 |
1282 | .RS 4 |
1258 | .IP "* absolute timer (interval = reschedule_cb = 0)" 4 |
1283 | .IP "* absolute timer (at = time, interval = reschedule_cb = 0)" 4 |
1259 | .IX Item "absolute timer (interval = reschedule_cb = 0)" |
1284 | .IX Item "absolute timer (at = time, interval = reschedule_cb = 0)" |
1260 | In this configuration the watcher triggers an event at the wallclock time |
1285 | In this configuration the watcher triggers an event at the wallclock time |
1261 | \&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs, |
1286 | \&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs, |
1262 | that is, if it is to be run at January 1st 2011 then it will run when the |
1287 | that is, if it is to be run at January 1st 2011 then it will run when the |
1263 | system time reaches or surpasses this time. |
1288 | system time reaches or surpasses this time. |
1264 | .IP "* non-repeating interval timer (interval > 0, reschedule_cb = 0)" 4 |
1289 | .IP "* non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)" 4 |
1265 | .IX Item "non-repeating interval timer (interval > 0, reschedule_cb = 0)" |
1290 | .IX Item "non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)" |
1266 | In this mode the watcher will always be scheduled to time out at the next |
1291 | In this mode the watcher will always be scheduled to time out at the next |
1267 | \&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N) and then repeat, regardless |
1292 | \&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N, which can also be negative) |
1268 | of any time jumps. |
1293 | and then repeat, regardless of any time jumps. |
1269 | .Sp |
1294 | .Sp |
1270 | This can be used to create timers that do not drift with respect to system |
1295 | This can be used to create timers that do not drift with respect to system |
1271 | time: |
1296 | time: |
1272 | .Sp |
1297 | .Sp |
1273 | .Vb 1 |
1298 | .Vb 1 |
… | |
… | |
1280 | by 3600. |
1305 | by 3600. |
1281 | .Sp |
1306 | .Sp |
1282 | Another way to think about it (for the mathematically inclined) is that |
1307 | Another way to think about it (for the mathematically inclined) is that |
1283 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
1308 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
1284 | time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps. |
1309 | time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps. |
|
|
1310 | .Sp |
|
|
1311 | For numerical stability it is preferable that the \f(CW\*(C`at\*(C'\fR value is near |
|
|
1312 | \&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for |
|
|
1313 | this value. |
1285 | .IP "* manual reschedule mode (reschedule_cb = callback)" 4 |
1314 | .IP "* manual reschedule mode (at and interval ignored, reschedule_cb = callback)" 4 |
1286 | .IX Item "manual reschedule mode (reschedule_cb = callback)" |
1315 | .IX Item "manual reschedule mode (at and interval ignored, reschedule_cb = callback)" |
1287 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being |
1316 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being |
1288 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1317 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1289 | reschedule callback will be called with the watcher as first, and the |
1318 | reschedule callback will be called with the watcher as first, and the |
1290 | current time as second argument. |
1319 | current time as second argument. |
1291 | .Sp |
1320 | .Sp |
1292 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, |
1321 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, |
1293 | ever, or make any event loop modifications\fR. If you need to stop it, |
1322 | ever, or make any event loop modifications\fR. If you need to stop it, |
1294 | return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by |
1323 | return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by |
1295 | starting a prepare watcher). |
1324 | starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is legal). |
1296 | .Sp |
1325 | .Sp |
1297 | Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1326 | Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1298 | ev_tstamp now)\*(C'\fR, e.g.: |
1327 | ev_tstamp now)\*(C'\fR, e.g.: |
1299 | .Sp |
1328 | .Sp |
1300 | .Vb 4 |
1329 | .Vb 4 |
… | |
… | |
1324 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
1353 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
1325 | Simply stops and restarts the periodic watcher again. This is only useful |
1354 | Simply stops and restarts the periodic watcher again. This is only useful |
1326 | when you changed some parameters or the reschedule callback would return |
1355 | when you changed some parameters or the reschedule callback would return |
1327 | a different time than the last time it was called (e.g. in a crond like |
1356 | a different time than the last time it was called (e.g. in a crond like |
1328 | program when the crontabs have changed). |
1357 | program when the crontabs have changed). |
|
|
1358 | .IP "ev_tstamp offset [read\-write]" 4 |
|
|
1359 | .IX Item "ev_tstamp offset [read-write]" |
|
|
1360 | When repeating, this contains the offset value, otherwise this is the |
|
|
1361 | absolute point in time (the \f(CW\*(C`at\*(C'\fR value passed to \f(CW\*(C`ev_periodic_set\*(C'\fR). |
|
|
1362 | .Sp |
|
|
1363 | Can be modified any time, but changes only take effect when the periodic |
|
|
1364 | timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
1329 | .IP "ev_tstamp interval [read\-write]" 4 |
1365 | .IP "ev_tstamp interval [read\-write]" 4 |
1330 | .IX Item "ev_tstamp interval [read-write]" |
1366 | .IX Item "ev_tstamp interval [read-write]" |
1331 | The current interval value. Can be modified any time, but changes only |
1367 | The current interval value. Can be modified any time, but changes only |
1332 | take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being |
1368 | take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being |
1333 | called. |
1369 | called. |