… | |
… | |
47 | |
47 | |
48 | return 0; |
48 | return 0; |
49 | } |
49 | } |
50 | |
50 | |
51 | =head1 DESCRIPTION |
51 | =head1 DESCRIPTION |
|
|
52 | |
|
|
53 | The newest version of this document is also available as a html-formatted |
|
|
54 | web page you might find easier to navigate when reading it for the first |
|
|
55 | time: L<http://cvs.schmorp.de/libev/ev.html>. |
52 | |
56 | |
53 | Libev is an event loop: you register interest in certain events (such as a |
57 | Libev is an event loop: you register interest in certain events (such as a |
54 | file descriptor being readable or a timeout occuring), and it will manage |
58 | file descriptor being readable or a timeout occuring), and it will manage |
55 | these event sources and provide your program with events. |
59 | these event sources and provide your program with events. |
56 | |
60 | |
… | |
… | |
113 | |
117 | |
114 | =item int ev_version_major () |
118 | =item int ev_version_major () |
115 | |
119 | |
116 | =item int ev_version_minor () |
120 | =item int ev_version_minor () |
117 | |
121 | |
118 | You can find out the major and minor version numbers of the library |
122 | You can find out the major and minor ABI version numbers of the library |
119 | you linked against by calling the functions C<ev_version_major> and |
123 | you linked against by calling the functions C<ev_version_major> and |
120 | C<ev_version_minor>. If you want, you can compare against the global |
124 | C<ev_version_minor>. If you want, you can compare against the global |
121 | symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the |
125 | symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the |
122 | version of the library your program was compiled against. |
126 | version of the library your program was compiled against. |
123 | |
127 | |
|
|
128 | These version numbers refer to the ABI version of the library, not the |
|
|
129 | release version. |
|
|
130 | |
124 | Usually, it's a good idea to terminate if the major versions mismatch, |
131 | Usually, it's a good idea to terminate if the major versions mismatch, |
125 | as this indicates an incompatible change. Minor versions are usually |
132 | as this indicates an incompatible change. Minor versions are usually |
126 | compatible to older versions, so a larger minor version alone is usually |
133 | compatible to older versions, so a larger minor version alone is usually |
127 | not a problem. |
134 | not a problem. |
128 | |
135 | |
129 | Example: Make sure we haven't accidentally been linked against the wrong |
136 | Example: Make sure we haven't accidentally been linked against the wrong |
130 | version. |
137 | version. |
… | |
… | |
482 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
489 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
483 | usually a better approach for this kind of thing. |
490 | usually a better approach for this kind of thing. |
484 | |
491 | |
485 | Here are the gory details of what C<ev_loop> does: |
492 | Here are the gory details of what C<ev_loop> does: |
486 | |
493 | |
|
|
494 | - Before the first iteration, call any pending watchers. |
487 | * If there are no active watchers (reference count is zero), return. |
495 | * If there are no active watchers (reference count is zero), return. |
488 | - Queue prepare watchers and then call all outstanding watchers. |
496 | - Queue all prepare watchers and then call all outstanding watchers. |
489 | - If we have been forked, recreate the kernel state. |
497 | - If we have been forked, recreate the kernel state. |
490 | - Update the kernel state with all outstanding changes. |
498 | - Update the kernel state with all outstanding changes. |
491 | - Update the "event loop time". |
499 | - Update the "event loop time". |
492 | - Calculate for how long to block. |
500 | - Calculate for how long to block. |
493 | - Block the process, waiting for any events. |
501 | - Block the process, waiting for any events. |
… | |
… | |
732 | =item bool ev_is_pending (ev_TYPE *watcher) |
740 | =item bool ev_is_pending (ev_TYPE *watcher) |
733 | |
741 | |
734 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
742 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
735 | events but its callback has not yet been invoked). As long as a watcher |
743 | events but its callback has not yet been invoked). As long as a watcher |
736 | is pending (but not active) you must not call an init function on it (but |
744 | is pending (but not active) you must not call an init function on it (but |
737 | C<ev_TYPE_set> is safe) and you must make sure the watcher is available to |
745 | C<ev_TYPE_set> is safe), you must not change its priority, and you must |
738 | libev (e.g. you cnanot C<free ()> it). |
746 | make sure the watcher is available to libev (e.g. you cannot C<free ()> |
|
|
747 | it). |
739 | |
748 | |
740 | =item callback ev_cb (ev_TYPE *watcher) |
749 | =item callback ev_cb (ev_TYPE *watcher) |
741 | |
750 | |
742 | Returns the callback currently set on the watcher. |
751 | Returns the callback currently set on the watcher. |
743 | |
752 | |
… | |
… | |
762 | watchers on the same event and make sure one is called first. |
771 | watchers on the same event and make sure one is called first. |
763 | |
772 | |
764 | If you need to suppress invocation when higher priority events are pending |
773 | If you need to suppress invocation when higher priority events are pending |
765 | you need to look at C<ev_idle> watchers, which provide this functionality. |
774 | you need to look at C<ev_idle> watchers, which provide this functionality. |
766 | |
775 | |
|
|
776 | You I<must not> change the priority of a watcher as long as it is active or |
|
|
777 | pending. |
|
|
778 | |
767 | The default priority used by watchers when no priority has been set is |
779 | The default priority used by watchers when no priority has been set is |
768 | always C<0>, which is supposed to not be too high and not be too low :). |
780 | always C<0>, which is supposed to not be too high and not be too low :). |
769 | |
781 | |
770 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
782 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
771 | fine, as long as you do not mind that the priority value you query might |
783 | fine, as long as you do not mind that the priority value you query might |
772 | or might not have been adjusted to be within valid range. |
784 | or might not have been adjusted to be within valid range. |
|
|
785 | |
|
|
786 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
|
|
787 | |
|
|
788 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
|
|
789 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
|
|
790 | can deal with that fact. |
|
|
791 | |
|
|
792 | =item int ev_clear_pending (loop, ev_TYPE *watcher) |
|
|
793 | |
|
|
794 | If the watcher is pending, this function returns clears its pending status |
|
|
795 | and returns its C<revents> bitset (as if its callback was invoked). If the |
|
|
796 | watcher isn't pending it does nothing and returns C<0>. |
773 | |
797 | |
774 | =back |
798 | =back |
775 | |
799 | |
776 | |
800 | |
777 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
801 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
… | |
… | |
883 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
907 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
884 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
908 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
885 | |
909 | |
886 | If you cannot run the fd in non-blocking mode (for example you should not |
910 | If you cannot run the fd in non-blocking mode (for example you should not |
887 | play around with an Xlib connection), then you have to seperately re-test |
911 | play around with an Xlib connection), then you have to seperately re-test |
888 | wether a file descriptor is really ready with a known-to-be good interface |
912 | whether a file descriptor is really ready with a known-to-be good interface |
889 | such as poll (fortunately in our Xlib example, Xlib already does this on |
913 | such as poll (fortunately in our Xlib example, Xlib already does this on |
890 | its own, so its quite safe to use). |
914 | its own, so its quite safe to use). |
891 | |
915 | |
892 | =over 4 |
916 | =over 4 |
893 | |
917 | |
… | |
… | |
1053 | but on wallclock time (absolute time). You can tell a periodic watcher |
1077 | but on wallclock time (absolute time). You can tell a periodic watcher |
1054 | to trigger "at" some specific point in time. For example, if you tell a |
1078 | to trigger "at" some specific point in time. For example, if you tell a |
1055 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
1079 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
1056 | + 10.>) and then reset your system clock to the last year, then it will |
1080 | + 10.>) and then reset your system clock to the last year, then it will |
1057 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
1081 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
1058 | roughly 10 seconds later and of course not if you reset your system time |
1082 | roughly 10 seconds later). |
1059 | again). |
|
|
1060 | |
1083 | |
1061 | They can also be used to implement vastly more complex timers, such as |
1084 | They can also be used to implement vastly more complex timers, such as |
1062 | triggering an event on eahc midnight, local time. |
1085 | triggering an event on each midnight, local time or other, complicated, |
|
|
1086 | rules. |
1063 | |
1087 | |
1064 | As with timers, the callback is guarenteed to be invoked only when the |
1088 | As with timers, the callback is guarenteed to be invoked only when the |
1065 | time (C<at>) has been passed, but if multiple periodic timers become ready |
1089 | time (C<at>) has been passed, but if multiple periodic timers become ready |
1066 | during the same loop iteration then order of execution is undefined. |
1090 | during the same loop iteration then order of execution is undefined. |
1067 | |
1091 | |
… | |
… | |
1074 | Lots of arguments, lets sort it out... There are basically three modes of |
1098 | Lots of arguments, lets sort it out... There are basically three modes of |
1075 | operation, and we will explain them from simplest to complex: |
1099 | operation, and we will explain them from simplest to complex: |
1076 | |
1100 | |
1077 | =over 4 |
1101 | =over 4 |
1078 | |
1102 | |
1079 | =item * absolute timer (interval = reschedule_cb = 0) |
1103 | =item * absolute timer (at = time, interval = reschedule_cb = 0) |
1080 | |
1104 | |
1081 | In this configuration the watcher triggers an event at the wallclock time |
1105 | In this configuration the watcher triggers an event at the wallclock time |
1082 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1106 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1083 | that is, if it is to be run at January 1st 2011 then it will run when the |
1107 | that is, if it is to be run at January 1st 2011 then it will run when the |
1084 | system time reaches or surpasses this time. |
1108 | system time reaches or surpasses this time. |
1085 | |
1109 | |
1086 | =item * non-repeating interval timer (interval > 0, reschedule_cb = 0) |
1110 | =item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1087 | |
1111 | |
1088 | In this mode the watcher will always be scheduled to time out at the next |
1112 | In this mode the watcher will always be scheduled to time out at the next |
1089 | C<at + N * interval> time (for some integer N) and then repeat, regardless |
1113 | C<at + N * interval> time (for some integer N, which can also be negative) |
1090 | of any time jumps. |
1114 | and then repeat, regardless of any time jumps. |
1091 | |
1115 | |
1092 | This can be used to create timers that do not drift with respect to system |
1116 | This can be used to create timers that do not drift with respect to system |
1093 | time: |
1117 | time: |
1094 | |
1118 | |
1095 | ev_periodic_set (&periodic, 0., 3600., 0); |
1119 | ev_periodic_set (&periodic, 0., 3600., 0); |
… | |
… | |
1101 | |
1125 | |
1102 | Another way to think about it (for the mathematically inclined) is that |
1126 | Another way to think about it (for the mathematically inclined) is that |
1103 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1127 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1104 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1128 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1105 | |
1129 | |
|
|
1130 | For numerical stability it is preferable that the C<at> value is near |
|
|
1131 | C<ev_now ()> (the current time), but there is no range requirement for |
|
|
1132 | this value. |
|
|
1133 | |
1106 | =item * manual reschedule mode (reschedule_cb = callback) |
1134 | =item * manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
1107 | |
1135 | |
1108 | In this mode the values for C<interval> and C<at> are both being |
1136 | In this mode the values for C<interval> and C<at> are both being |
1109 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1137 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1110 | reschedule callback will be called with the watcher as first, and the |
1138 | reschedule callback will be called with the watcher as first, and the |
1111 | current time as second argument. |
1139 | current time as second argument. |
1112 | |
1140 | |
1113 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1141 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1114 | ever, or make any event loop modifications>. If you need to stop it, |
1142 | ever, or make any event loop modifications>. If you need to stop it, |
1115 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
1143 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
1116 | starting a prepare watcher). |
1144 | starting an C<ev_prepare> watcher, which is legal). |
1117 | |
1145 | |
1118 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1146 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1119 | ev_tstamp now)>, e.g.: |
1147 | ev_tstamp now)>, e.g.: |
1120 | |
1148 | |
1121 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1149 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
… | |
… | |
1143 | |
1171 | |
1144 | Simply stops and restarts the periodic watcher again. This is only useful |
1172 | Simply stops and restarts the periodic watcher again. This is only useful |
1145 | when you changed some parameters or the reschedule callback would return |
1173 | when you changed some parameters or the reschedule callback would return |
1146 | a different time than the last time it was called (e.g. in a crond like |
1174 | a different time than the last time it was called (e.g. in a crond like |
1147 | program when the crontabs have changed). |
1175 | program when the crontabs have changed). |
|
|
1176 | |
|
|
1177 | =item ev_tstamp offset [read-write] |
|
|
1178 | |
|
|
1179 | When repeating, this contains the offset value, otherwise this is the |
|
|
1180 | absolute point in time (the C<at> value passed to C<ev_periodic_set>). |
|
|
1181 | |
|
|
1182 | Can be modified any time, but changes only take effect when the periodic |
|
|
1183 | timer fires or C<ev_periodic_again> is being called. |
1148 | |
1184 | |
1149 | =item ev_tstamp interval [read-write] |
1185 | =item ev_tstamp interval [read-write] |
1150 | |
1186 | |
1151 | The current interval value. Can be modified any time, but changes only |
1187 | The current interval value. Can be modified any time, but changes only |
1152 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
1188 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
… | |
… | |
1461 | with priority higher than or equal to the event loop and one coroutine |
1497 | with priority higher than or equal to the event loop and one coroutine |
1462 | of lower priority, but only once, using idle watchers to keep the event |
1498 | of lower priority, but only once, using idle watchers to keep the event |
1463 | loop from blocking if lower-priority coroutines are active, thus mapping |
1499 | loop from blocking if lower-priority coroutines are active, thus mapping |
1464 | low-priority coroutines to idle/background tasks). |
1500 | low-priority coroutines to idle/background tasks). |
1465 | |
1501 | |
|
|
1502 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
|
|
1503 | priority, to ensure that they are being run before any other watchers |
|
|
1504 | after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers, |
|
|
1505 | too) should not activate ("feed") events into libev. While libev fully |
|
|
1506 | supports this, they will be called before other C<ev_check> watchers did |
|
|
1507 | their job. As C<ev_check> watchers are often used to embed other event |
|
|
1508 | loops those other event loops might be in an unusable state until their |
|
|
1509 | C<ev_check> watcher ran (always remind yourself to coexist peacefully with |
|
|
1510 | others). |
|
|
1511 | |
1466 | =over 4 |
1512 | =over 4 |
1467 | |
1513 | |
1468 | =item ev_prepare_init (ev_prepare *, callback) |
1514 | =item ev_prepare_init (ev_prepare *, callback) |
1469 | |
1515 | |
1470 | =item ev_check_init (ev_check *, callback) |
1516 | =item ev_check_init (ev_check *, callback) |
… | |
… | |
1473 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1519 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1474 | macros, but using them is utterly, utterly and completely pointless. |
1520 | macros, but using them is utterly, utterly and completely pointless. |
1475 | |
1521 | |
1476 | =back |
1522 | =back |
1477 | |
1523 | |
1478 | Example: To include a library such as adns, you would add IO watchers |
1524 | There are a number of principal ways to embed other event loops or modules |
1479 | and a timeout watcher in a prepare handler, as required by libadns, and |
1525 | into libev. Here are some ideas on how to include libadns into libev |
|
|
1526 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
|
|
1527 | use for an actually working example. Another Perl module named C<EV::Glib> |
|
|
1528 | embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV |
|
|
1529 | into the Glib event loop). |
|
|
1530 | |
|
|
1531 | Method 1: Add IO watchers and a timeout watcher in a prepare handler, |
1480 | in a check watcher, destroy them and call into libadns. What follows is |
1532 | and in a check watcher, destroy them and call into libadns. What follows |
1481 | pseudo-code only of course: |
1533 | is pseudo-code only of course. This requires you to either use a low |
|
|
1534 | priority for the check watcher or use C<ev_clear_pending> explicitly, as |
|
|
1535 | the callbacks for the IO/timeout watchers might not have been called yet. |
1482 | |
1536 | |
1483 | static ev_io iow [nfd]; |
1537 | static ev_io iow [nfd]; |
1484 | static ev_timer tw; |
1538 | static ev_timer tw; |
1485 | |
1539 | |
1486 | static void |
1540 | static void |
1487 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1541 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1488 | { |
1542 | { |
1489 | // set the relevant poll flags |
|
|
1490 | // could also call adns_processreadable etc. here |
|
|
1491 | struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1492 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1493 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1494 | } |
1543 | } |
1495 | |
1544 | |
1496 | // create io watchers for each fd and a timer before blocking |
1545 | // create io watchers for each fd and a timer before blocking |
1497 | static void |
1546 | static void |
1498 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1547 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
… | |
… | |
1504 | |
1553 | |
1505 | /* the callback is illegal, but won't be called as we stop during check */ |
1554 | /* the callback is illegal, but won't be called as we stop during check */ |
1506 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1555 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1507 | ev_timer_start (loop, &tw); |
1556 | ev_timer_start (loop, &tw); |
1508 | |
1557 | |
1509 | // create on ev_io per pollfd |
1558 | // create one ev_io per pollfd |
1510 | for (int i = 0; i < nfd; ++i) |
1559 | for (int i = 0; i < nfd; ++i) |
1511 | { |
1560 | { |
1512 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1561 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1513 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1562 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1514 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1563 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1515 | |
1564 | |
1516 | fds [i].revents = 0; |
1565 | fds [i].revents = 0; |
1517 | iow [i].data = fds + i; |
|
|
1518 | ev_io_start (loop, iow + i); |
1566 | ev_io_start (loop, iow + i); |
1519 | } |
1567 | } |
1520 | } |
1568 | } |
1521 | |
1569 | |
1522 | // stop all watchers after blocking |
1570 | // stop all watchers after blocking |
… | |
… | |
1524 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1572 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1525 | { |
1573 | { |
1526 | ev_timer_stop (loop, &tw); |
1574 | ev_timer_stop (loop, &tw); |
1527 | |
1575 | |
1528 | for (int i = 0; i < nfd; ++i) |
1576 | for (int i = 0; i < nfd; ++i) |
|
|
1577 | { |
|
|
1578 | // set the relevant poll flags |
|
|
1579 | // could also call adns_processreadable etc. here |
|
|
1580 | struct pollfd *fd = fds + i; |
|
|
1581 | int revents = ev_clear_pending (iow + i); |
|
|
1582 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1583 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1584 | |
|
|
1585 | // now stop the watcher |
1529 | ev_io_stop (loop, iow + i); |
1586 | ev_io_stop (loop, iow + i); |
|
|
1587 | } |
1530 | |
1588 | |
1531 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
1589 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1590 | } |
|
|
1591 | |
|
|
1592 | Method 2: This would be just like method 1, but you run C<adns_afterpoll> |
|
|
1593 | in the prepare watcher and would dispose of the check watcher. |
|
|
1594 | |
|
|
1595 | Method 3: If the module to be embedded supports explicit event |
|
|
1596 | notification (adns does), you can also make use of the actual watcher |
|
|
1597 | callbacks, and only destroy/create the watchers in the prepare watcher. |
|
|
1598 | |
|
|
1599 | static void |
|
|
1600 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1601 | { |
|
|
1602 | adns_state ads = (adns_state)w->data; |
|
|
1603 | update_now (EV_A); |
|
|
1604 | |
|
|
1605 | adns_processtimeouts (ads, &tv_now); |
|
|
1606 | } |
|
|
1607 | |
|
|
1608 | static void |
|
|
1609 | io_cb (EV_P_ ev_io *w, int revents) |
|
|
1610 | { |
|
|
1611 | adns_state ads = (adns_state)w->data; |
|
|
1612 | update_now (EV_A); |
|
|
1613 | |
|
|
1614 | if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now); |
|
|
1615 | if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now); |
|
|
1616 | } |
|
|
1617 | |
|
|
1618 | // do not ever call adns_afterpoll |
|
|
1619 | |
|
|
1620 | Method 4: Do not use a prepare or check watcher because the module you |
|
|
1621 | want to embed is too inflexible to support it. Instead, youc na override |
|
|
1622 | their poll function. The drawback with this solution is that the main |
|
|
1623 | loop is now no longer controllable by EV. The C<Glib::EV> module does |
|
|
1624 | this. |
|
|
1625 | |
|
|
1626 | static gint |
|
|
1627 | event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
|
|
1628 | { |
|
|
1629 | int got_events = 0; |
|
|
1630 | |
|
|
1631 | for (n = 0; n < nfds; ++n) |
|
|
1632 | // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
|
|
1633 | |
|
|
1634 | if (timeout >= 0) |
|
|
1635 | // create/start timer |
|
|
1636 | |
|
|
1637 | // poll |
|
|
1638 | ev_loop (EV_A_ 0); |
|
|
1639 | |
|
|
1640 | // stop timer again |
|
|
1641 | if (timeout >= 0) |
|
|
1642 | ev_timer_stop (EV_A_ &to); |
|
|
1643 | |
|
|
1644 | // stop io watchers again - their callbacks should have set |
|
|
1645 | for (n = 0; n < nfds; ++n) |
|
|
1646 | ev_io_stop (EV_A_ iow [n]); |
|
|
1647 | |
|
|
1648 | return got_events; |
1532 | } |
1649 | } |
1533 | |
1650 | |
1534 | |
1651 | |
1535 | =head2 C<ev_embed> - when one backend isn't enough... |
1652 | =head2 C<ev_embed> - when one backend isn't enough... |
1536 | |
1653 | |
… | |
… | |
1740 | |
1857 | |
1741 | To use it, |
1858 | To use it, |
1742 | |
1859 | |
1743 | #include <ev++.h> |
1860 | #include <ev++.h> |
1744 | |
1861 | |
1745 | (it is not installed by default). This automatically includes F<ev.h> |
1862 | This automatically includes F<ev.h> and puts all of its definitions (many |
1746 | and puts all of its definitions (many of them macros) into the global |
1863 | of them macros) into the global namespace. All C++ specific things are |
1747 | namespace. All C++ specific things are put into the C<ev> namespace. |
1864 | put into the C<ev> namespace. It should support all the same embedding |
|
|
1865 | options as F<ev.h>, most notably C<EV_MULTIPLICITY>. |
1748 | |
1866 | |
1749 | It should support all the same embedding options as F<ev.h>, most notably |
1867 | Care has been taken to keep the overhead low. The only data member the C++ |
1750 | C<EV_MULTIPLICITY>. |
1868 | classes add (compared to plain C-style watchers) is the event loop pointer |
|
|
1869 | that the watcher is associated with (or no additional members at all if |
|
|
1870 | you disable C<EV_MULTIPLICITY> when embedding libev). |
|
|
1871 | |
|
|
1872 | Currently, functions, and static and non-static member functions can be |
|
|
1873 | used as callbacks. Other types should be easy to add as long as they only |
|
|
1874 | need one additional pointer for context. If you need support for other |
|
|
1875 | types of functors please contact the author (preferably after implementing |
|
|
1876 | it). |
1751 | |
1877 | |
1752 | Here is a list of things available in the C<ev> namespace: |
1878 | Here is a list of things available in the C<ev> namespace: |
1753 | |
1879 | |
1754 | =over 4 |
1880 | =over 4 |
1755 | |
1881 | |
… | |
… | |
1771 | |
1897 | |
1772 | All of those classes have these methods: |
1898 | All of those classes have these methods: |
1773 | |
1899 | |
1774 | =over 4 |
1900 | =over 4 |
1775 | |
1901 | |
1776 | =item ev::TYPE::TYPE (object *, object::method *) |
1902 | =item ev::TYPE::TYPE () |
1777 | |
1903 | |
1778 | =item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *) |
1904 | =item ev::TYPE::TYPE (struct ev_loop *) |
1779 | |
1905 | |
1780 | =item ev::TYPE::~TYPE |
1906 | =item ev::TYPE::~TYPE |
1781 | |
1907 | |
1782 | The constructor takes a pointer to an object and a method pointer to |
1908 | The constructor (optionally) takes an event loop to associate the watcher |
1783 | the event handler callback to call in this class. The constructor calls |
1909 | with. If it is omitted, it will use C<EV_DEFAULT>. |
1784 | C<ev_init> for you, which means you have to call the C<set> method |
1910 | |
1785 | before starting it. If you do not specify a loop then the constructor |
1911 | The constructor calls C<ev_init> for you, which means you have to call the |
1786 | automatically associates the default loop with this watcher. |
1912 | C<set> method before starting it. |
|
|
1913 | |
|
|
1914 | It will not set a callback, however: You have to call the templated C<set> |
|
|
1915 | method to set a callback before you can start the watcher. |
|
|
1916 | |
|
|
1917 | (The reason why you have to use a method is a limitation in C++ which does |
|
|
1918 | not allow explicit template arguments for constructors). |
1787 | |
1919 | |
1788 | The destructor automatically stops the watcher if it is active. |
1920 | The destructor automatically stops the watcher if it is active. |
|
|
1921 | |
|
|
1922 | =item w->set<class, &class::method> (object *) |
|
|
1923 | |
|
|
1924 | This method sets the callback method to call. The method has to have a |
|
|
1925 | signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as |
|
|
1926 | first argument and the C<revents> as second. The object must be given as |
|
|
1927 | parameter and is stored in the C<data> member of the watcher. |
|
|
1928 | |
|
|
1929 | This method synthesizes efficient thunking code to call your method from |
|
|
1930 | the C callback that libev requires. If your compiler can inline your |
|
|
1931 | callback (i.e. it is visible to it at the place of the C<set> call and |
|
|
1932 | your compiler is good :), then the method will be fully inlined into the |
|
|
1933 | thunking function, making it as fast as a direct C callback. |
|
|
1934 | |
|
|
1935 | Example: simple class declaration and watcher initialisation |
|
|
1936 | |
|
|
1937 | struct myclass |
|
|
1938 | { |
|
|
1939 | void io_cb (ev::io &w, int revents) { } |
|
|
1940 | } |
|
|
1941 | |
|
|
1942 | myclass obj; |
|
|
1943 | ev::io iow; |
|
|
1944 | iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
1945 | |
|
|
1946 | =item w->set<function> (void *data = 0) |
|
|
1947 | |
|
|
1948 | Also sets a callback, but uses a static method or plain function as |
|
|
1949 | callback. The optional C<data> argument will be stored in the watcher's |
|
|
1950 | C<data> member and is free for you to use. |
|
|
1951 | |
|
|
1952 | The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>. |
|
|
1953 | |
|
|
1954 | See the method-C<set> above for more details. |
|
|
1955 | |
|
|
1956 | Example: |
|
|
1957 | |
|
|
1958 | static void io_cb (ev::io &w, int revents) { } |
|
|
1959 | iow.set <io_cb> (); |
1789 | |
1960 | |
1790 | =item w->set (struct ev_loop *) |
1961 | =item w->set (struct ev_loop *) |
1791 | |
1962 | |
1792 | Associates a different C<struct ev_loop> with this watcher. You can only |
1963 | Associates a different C<struct ev_loop> with this watcher. You can only |
1793 | do this when the watcher is inactive (and not pending either). |
1964 | do this when the watcher is inactive (and not pending either). |
1794 | |
1965 | |
1795 | =item w->set ([args]) |
1966 | =item w->set ([args]) |
1796 | |
1967 | |
1797 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
1968 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
1798 | called at least once. Unlike the C counterpart, an active watcher gets |
1969 | called at least once. Unlike the C counterpart, an active watcher gets |
1799 | automatically stopped and restarted. |
1970 | automatically stopped and restarted when reconfiguring it with this |
|
|
1971 | method. |
1800 | |
1972 | |
1801 | =item w->start () |
1973 | =item w->start () |
1802 | |
1974 | |
1803 | Starts the watcher. Note that there is no C<loop> argument as the |
1975 | Starts the watcher. Note that there is no C<loop> argument, as the |
1804 | constructor already takes the loop. |
1976 | constructor already stores the event loop. |
1805 | |
1977 | |
1806 | =item w->stop () |
1978 | =item w->stop () |
1807 | |
1979 | |
1808 | Stops the watcher if it is active. Again, no C<loop> argument. |
1980 | Stops the watcher if it is active. Again, no C<loop> argument. |
1809 | |
1981 | |
… | |
… | |
1834 | |
2006 | |
1835 | myclass (); |
2007 | myclass (); |
1836 | } |
2008 | } |
1837 | |
2009 | |
1838 | myclass::myclass (int fd) |
2010 | myclass::myclass (int fd) |
1839 | : io (this, &myclass::io_cb), |
|
|
1840 | idle (this, &myclass::idle_cb) |
|
|
1841 | { |
2011 | { |
|
|
2012 | io .set <myclass, &myclass::io_cb > (this); |
|
|
2013 | idle.set <myclass, &myclass::idle_cb> (this); |
|
|
2014 | |
1842 | io.start (fd, ev::READ); |
2015 | io.start (fd, ev::READ); |
1843 | } |
2016 | } |
1844 | |
2017 | |
1845 | |
2018 | |
1846 | =head1 MACRO MAGIC |
2019 | =head1 MACRO MAGIC |
1847 | |
2020 | |
1848 | Libev can be compiled with a variety of options, the most fundemantal is |
2021 | Libev can be compiled with a variety of options, the most fundemantal is |
1849 | C<EV_MULTIPLICITY>. This option determines wether (most) functions and |
2022 | C<EV_MULTIPLICITY>. This option determines whether (most) functions and |
1850 | callbacks have an initial C<struct ev_loop *> argument. |
2023 | callbacks have an initial C<struct ev_loop *> argument. |
1851 | |
2024 | |
1852 | To make it easier to write programs that cope with either variant, the |
2025 | To make it easier to write programs that cope with either variant, the |
1853 | following macros are defined: |
2026 | following macros are defined: |
1854 | |
2027 | |
… | |
… | |
1888 | loop, if multiple loops are supported ("ev loop default"). |
2061 | loop, if multiple loops are supported ("ev loop default"). |
1889 | |
2062 | |
1890 | =back |
2063 | =back |
1891 | |
2064 | |
1892 | Example: Declare and initialise a check watcher, utilising the above |
2065 | Example: Declare and initialise a check watcher, utilising the above |
1893 | macros so it will work regardless of wether multiple loops are supported |
2066 | macros so it will work regardless of whether multiple loops are supported |
1894 | or not. |
2067 | or not. |
1895 | |
2068 | |
1896 | static void |
2069 | static void |
1897 | check_cb (EV_P_ ev_timer *w, int revents) |
2070 | check_cb (EV_P_ ev_timer *w, int revents) |
1898 | { |
2071 | { |
… | |
… | |
2123 | will have the C<struct ev_loop *> as first argument, and you can create |
2296 | will have the C<struct ev_loop *> as first argument, and you can create |
2124 | additional independent event loops. Otherwise there will be no support |
2297 | additional independent event loops. Otherwise there will be no support |
2125 | for multiple event loops and there is no first event loop pointer |
2298 | for multiple event loops and there is no first event loop pointer |
2126 | argument. Instead, all functions act on the single default loop. |
2299 | argument. Instead, all functions act on the single default loop. |
2127 | |
2300 | |
|
|
2301 | =item EV_MINPRI |
|
|
2302 | |
|
|
2303 | =item EV_MAXPRI |
|
|
2304 | |
|
|
2305 | The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to |
|
|
2306 | C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can |
|
|
2307 | provide for more priorities by overriding those symbols (usually defined |
|
|
2308 | to be C<-2> and C<2>, respectively). |
|
|
2309 | |
|
|
2310 | When doing priority-based operations, libev usually has to linearly search |
|
|
2311 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
2312 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
|
|
2313 | fine. |
|
|
2314 | |
|
|
2315 | If your embedding app does not need any priorities, defining these both to |
|
|
2316 | C<0> will save some memory and cpu. |
|
|
2317 | |
2128 | =item EV_PERIODIC_ENABLE |
2318 | =item EV_PERIODIC_ENABLE |
2129 | |
2319 | |
2130 | If undefined or defined to be C<1>, then periodic timers are supported. If |
2320 | If undefined or defined to be C<1>, then periodic timers are supported. If |
2131 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
2321 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
2132 | code. |
2322 | code. |
… | |
… | |
2234 | |
2424 | |
2235 | In this section the complexities of (many of) the algorithms used inside |
2425 | In this section the complexities of (many of) the algorithms used inside |
2236 | libev will be explained. For complexity discussions about backends see the |
2426 | libev will be explained. For complexity discussions about backends see the |
2237 | documentation for C<ev_default_init>. |
2427 | documentation for C<ev_default_init>. |
2238 | |
2428 | |
|
|
2429 | All of the following are about amortised time: If an array needs to be |
|
|
2430 | extended, libev needs to realloc and move the whole array, but this |
|
|
2431 | happens asymptotically never with higher number of elements, so O(1) might |
|
|
2432 | mean it might do a lengthy realloc operation in rare cases, but on average |
|
|
2433 | it is much faster and asymptotically approaches constant time. |
|
|
2434 | |
2239 | =over 4 |
2435 | =over 4 |
2240 | |
2436 | |
2241 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2437 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2242 | |
2438 | |
|
|
2439 | This means that, when you have a watcher that triggers in one hour and |
|
|
2440 | there are 100 watchers that would trigger before that then inserting will |
|
|
2441 | have to skip those 100 watchers. |
|
|
2442 | |
2243 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2443 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2244 | |
2444 | |
|
|
2445 | That means that for changing a timer costs less than removing/adding them |
|
|
2446 | as only the relative motion in the event queue has to be paid for. |
|
|
2447 | |
2245 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2448 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2246 | |
2449 | |
|
|
2450 | These just add the watcher into an array or at the head of a list. |
2247 | =item Stopping check/prepare/idle watchers: O(1) |
2451 | =item Stopping check/prepare/idle watchers: O(1) |
2248 | |
2452 | |
2249 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2453 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2250 | |
2454 | |
|
|
2455 | These watchers are stored in lists then need to be walked to find the |
|
|
2456 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
2457 | have many watchers waiting for the same fd or signal). |
|
|
2458 | |
2251 | =item Finding the next timer per loop iteration: O(1) |
2459 | =item Finding the next timer per loop iteration: O(1) |
2252 | |
2460 | |
2253 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2461 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2254 | |
2462 | |
|
|
2463 | A change means an I/O watcher gets started or stopped, which requires |
|
|
2464 | libev to recalculate its status (and possibly tell the kernel). |
|
|
2465 | |
2255 | =item Activating one watcher: O(1) |
2466 | =item Activating one watcher: O(1) |
2256 | |
2467 | |
|
|
2468 | =item Priority handling: O(number_of_priorities) |
|
|
2469 | |
|
|
2470 | Priorities are implemented by allocating some space for each |
|
|
2471 | priority. When doing priority-based operations, libev usually has to |
|
|
2472 | linearly search all the priorities. |
|
|
2473 | |
2257 | =back |
2474 | =back |
2258 | |
2475 | |
2259 | |
2476 | |
2260 | =head1 AUTHOR |
2477 | =head1 AUTHOR |
2261 | |
2478 | |