… | |
… | |
77 | on event-based programming, nor will it introduce event-based programming |
77 | on event-based programming, nor will it introduce event-based programming |
78 | with libev. |
78 | with libev. |
79 | |
79 | |
80 | Familiarity with event based programming techniques in general is assumed |
80 | Familiarity with event based programming techniques in general is assumed |
81 | throughout this document. |
81 | throughout this document. |
|
|
82 | |
|
|
83 | =head1 WHAT TO READ WHEN IN A HURRY |
|
|
84 | |
|
|
85 | This manual tries to be very detailed, but unfortunately, this also makes |
|
|
86 | it very long. If you just want to know the basics of libev, I suggest |
|
|
87 | reading L<ANATOMY OF A WATCHER>, then the L<EXAMPLE PROGRAM> above and |
|
|
88 | look up the missing functions in L<GLOBAL FUNCTIONS> and the C<ev_io> and |
|
|
89 | C<ev_timer> sections in L<WATCHER TYPES>. |
82 | |
90 | |
83 | =head1 ABOUT LIBEV |
91 | =head1 ABOUT LIBEV |
84 | |
92 | |
85 | Libev is an event loop: you register interest in certain events (such as a |
93 | Libev is an event loop: you register interest in certain events (such as a |
86 | file descriptor being readable or a timeout occurring), and it will manage |
94 | file descriptor being readable or a timeout occurring), and it will manage |
… | |
… | |
300 | An event loop is described by a C<struct ev_loop *> (the C<struct> is |
308 | An event loop is described by a C<struct ev_loop *> (the C<struct> is |
301 | I<not> optional in this case unless libev 3 compatibility is disabled, as |
309 | I<not> optional in this case unless libev 3 compatibility is disabled, as |
302 | libev 3 had an C<ev_loop> function colliding with the struct name). |
310 | libev 3 had an C<ev_loop> function colliding with the struct name). |
303 | |
311 | |
304 | The library knows two types of such loops, the I<default> loop, which |
312 | The library knows two types of such loops, the I<default> loop, which |
305 | supports signals and child events, and dynamically created event loops |
313 | supports child process events, and dynamically created event loops which |
306 | which do not. |
314 | do not. |
307 | |
315 | |
308 | =over 4 |
316 | =over 4 |
309 | |
317 | |
310 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
318 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
311 | |
319 | |
… | |
… | |
341 | |
349 | |
342 | Example: Restrict libev to the select and poll backends, and do not allow |
350 | Example: Restrict libev to the select and poll backends, and do not allow |
343 | environment settings to be taken into account: |
351 | environment settings to be taken into account: |
344 | |
352 | |
345 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
353 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
346 | |
|
|
347 | Example: Use whatever libev has to offer, but make sure that kqueue is |
|
|
348 | used if available (warning, breaks stuff, best use only with your own |
|
|
349 | private event loop and only if you know the OS supports your types of |
|
|
350 | fds): |
|
|
351 | |
|
|
352 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
353 | |
354 | |
354 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
355 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
355 | |
356 | |
356 | This will create and initialise a new event loop object. If the loop |
357 | This will create and initialise a new event loop object. If the loop |
357 | could not be initialised, returns false. |
358 | could not be initialised, returns false. |
… | |
… | |
589 | Example: Try to create a event loop that uses epoll and nothing else. |
590 | Example: Try to create a event loop that uses epoll and nothing else. |
590 | |
591 | |
591 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
592 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
592 | if (!epoller) |
593 | if (!epoller) |
593 | fatal ("no epoll found here, maybe it hides under your chair"); |
594 | fatal ("no epoll found here, maybe it hides under your chair"); |
|
|
595 | |
|
|
596 | Example: Use whatever libev has to offer, but make sure that kqueue is |
|
|
597 | used if available. |
|
|
598 | |
|
|
599 | struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
594 | |
600 | |
595 | =item ev_loop_destroy (loop) |
601 | =item ev_loop_destroy (loop) |
596 | |
602 | |
597 | Destroys an event loop object (frees all memory and kernel state |
603 | Destroys an event loop object (frees all memory and kernel state |
598 | etc.). None of the active event watchers will be stopped in the normal |
604 | etc.). None of the active event watchers will be stopped in the normal |
… | |
… | |
1114 | =item C<EV_FORK> |
1120 | =item C<EV_FORK> |
1115 | |
1121 | |
1116 | The event loop has been resumed in the child process after fork (see |
1122 | The event loop has been resumed in the child process after fork (see |
1117 | C<ev_fork>). |
1123 | C<ev_fork>). |
1118 | |
1124 | |
|
|
1125 | =item C<EV_CLEANUP> |
|
|
1126 | |
|
|
1127 | The event loop is about to be destroyed (see C<ev_cleanup>). |
|
|
1128 | |
1119 | =item C<EV_ASYNC> |
1129 | =item C<EV_ASYNC> |
1120 | |
1130 | |
1121 | The given async watcher has been asynchronously notified (see C<ev_async>). |
1131 | The given async watcher has been asynchronously notified (see C<ev_async>). |
1122 | |
1132 | |
1123 | =item C<EV_CUSTOM> |
1133 | =item C<EV_CUSTOM> |
… | |
… | |
1144 | programs, though, as the fd could already be closed and reused for another |
1154 | programs, though, as the fd could already be closed and reused for another |
1145 | thing, so beware. |
1155 | thing, so beware. |
1146 | |
1156 | |
1147 | =back |
1157 | =back |
1148 | |
1158 | |
1149 | =head2 WATCHER STATES |
|
|
1150 | |
|
|
1151 | There are various watcher states mentioned throughout this manual - |
|
|
1152 | active, pending and so on. In this section these states and the rules to |
|
|
1153 | transition between them will be described in more detail - and while these |
|
|
1154 | rules might look complicated, they usually do "the right thing". |
|
|
1155 | |
|
|
1156 | =over 4 |
|
|
1157 | |
|
|
1158 | =item initialiased |
|
|
1159 | |
|
|
1160 | Before a watcher can be registered with the event looop it has to be |
|
|
1161 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
|
|
1162 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
|
|
1163 | |
|
|
1164 | In this state it is simply some block of memory that is suitable for use |
|
|
1165 | in an event loop. It can be moved around, freed, reused etc. at will. |
|
|
1166 | |
|
|
1167 | =item started/running/active |
|
|
1168 | |
|
|
1169 | Once a watcher has been started with a call to C<ev_TYPE_start> it becomes |
|
|
1170 | property of the event loop, and is actively waiting for events. While in |
|
|
1171 | this state it cannot be accessed (except in a few documented ways), moved, |
|
|
1172 | freed or anything else - the only legal thing is to keep a pointer to it, |
|
|
1173 | and call libev functions on it that are documented to work on active watchers. |
|
|
1174 | |
|
|
1175 | =item pending |
|
|
1176 | |
|
|
1177 | If a watcher is active and libev determines that an event it is interested |
|
|
1178 | in has occurred (such as a timer expiring), it will become pending. It will |
|
|
1179 | stay in this pending state until either it is stopped or its callback is |
|
|
1180 | about to be invoked, so it is not normally pending inside the watcher |
|
|
1181 | callback. |
|
|
1182 | |
|
|
1183 | The watcher might or might not be active while it is pending (for example, |
|
|
1184 | an expired non-repeating timer can be pending but no longer active). If it |
|
|
1185 | is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>), |
|
|
1186 | but it is still property of the event loop at this time, so cannot be |
|
|
1187 | moved, freed or reused. And if it is active the rules described in the |
|
|
1188 | previous item still apply. |
|
|
1189 | |
|
|
1190 | It is also possible to feed an event on a watcher that is not active (e.g. |
|
|
1191 | via C<ev_feed_event>), in which case it becomes pending without being |
|
|
1192 | active. |
|
|
1193 | |
|
|
1194 | =item stopped |
|
|
1195 | |
|
|
1196 | A watcher can be stopped implicitly by libev (in which case it might still |
|
|
1197 | be pending), or explicitly by calling its C<ev_TYPE_stop> function. The |
|
|
1198 | latter will clear any pending state the watcher might be in, regardless |
|
|
1199 | of whether it was active or not, so stopping a watcher explicitly before |
|
|
1200 | freeing it is often a good idea. |
|
|
1201 | |
|
|
1202 | While stopped (and not pending) the watcher is essentially in the |
|
|
1203 | initialised state, that is it can be reused, moved, modified in any way |
|
|
1204 | you wish. |
|
|
1205 | |
|
|
1206 | =back |
|
|
1207 | |
|
|
1208 | =head2 GENERIC WATCHER FUNCTIONS |
1159 | =head2 GENERIC WATCHER FUNCTIONS |
1209 | |
1160 | |
1210 | =over 4 |
1161 | =over 4 |
1211 | |
1162 | |
1212 | =item C<ev_init> (ev_TYPE *watcher, callback) |
1163 | =item C<ev_init> (ev_TYPE *watcher, callback) |
… | |
… | |
1353 | |
1304 | |
1354 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
1305 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
1355 | functions that do not need a watcher. |
1306 | functions that do not need a watcher. |
1356 | |
1307 | |
1357 | =back |
1308 | =back |
1358 | |
|
|
1359 | |
1309 | |
1360 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
1310 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
1361 | |
1311 | |
1362 | Each watcher has, by default, a member C<void *data> that you can change |
1312 | Each watcher has, by default, a member C<void *data> that you can change |
1363 | and read at any time: libev will completely ignore it. This can be used |
1313 | and read at any time: libev will completely ignore it. This can be used |
… | |
… | |
1419 | t2_cb (EV_P_ ev_timer *w, int revents) |
1369 | t2_cb (EV_P_ ev_timer *w, int revents) |
1420 | { |
1370 | { |
1421 | struct my_biggy big = (struct my_biggy *) |
1371 | struct my_biggy big = (struct my_biggy *) |
1422 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1372 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1423 | } |
1373 | } |
|
|
1374 | |
|
|
1375 | =head2 WATCHER STATES |
|
|
1376 | |
|
|
1377 | There are various watcher states mentioned throughout this manual - |
|
|
1378 | active, pending and so on. In this section these states and the rules to |
|
|
1379 | transition between them will be described in more detail - and while these |
|
|
1380 | rules might look complicated, they usually do "the right thing". |
|
|
1381 | |
|
|
1382 | =over 4 |
|
|
1383 | |
|
|
1384 | =item initialiased |
|
|
1385 | |
|
|
1386 | Before a watcher can be registered with the event looop it has to be |
|
|
1387 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
|
|
1388 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
|
|
1389 | |
|
|
1390 | In this state it is simply some block of memory that is suitable for use |
|
|
1391 | in an event loop. It can be moved around, freed, reused etc. at will. |
|
|
1392 | |
|
|
1393 | =item started/running/active |
|
|
1394 | |
|
|
1395 | Once a watcher has been started with a call to C<ev_TYPE_start> it becomes |
|
|
1396 | property of the event loop, and is actively waiting for events. While in |
|
|
1397 | this state it cannot be accessed (except in a few documented ways), moved, |
|
|
1398 | freed or anything else - the only legal thing is to keep a pointer to it, |
|
|
1399 | and call libev functions on it that are documented to work on active watchers. |
|
|
1400 | |
|
|
1401 | =item pending |
|
|
1402 | |
|
|
1403 | If a watcher is active and libev determines that an event it is interested |
|
|
1404 | in has occurred (such as a timer expiring), it will become pending. It will |
|
|
1405 | stay in this pending state until either it is stopped or its callback is |
|
|
1406 | about to be invoked, so it is not normally pending inside the watcher |
|
|
1407 | callback. |
|
|
1408 | |
|
|
1409 | The watcher might or might not be active while it is pending (for example, |
|
|
1410 | an expired non-repeating timer can be pending but no longer active). If it |
|
|
1411 | is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>), |
|
|
1412 | but it is still property of the event loop at this time, so cannot be |
|
|
1413 | moved, freed or reused. And if it is active the rules described in the |
|
|
1414 | previous item still apply. |
|
|
1415 | |
|
|
1416 | It is also possible to feed an event on a watcher that is not active (e.g. |
|
|
1417 | via C<ev_feed_event>), in which case it becomes pending without being |
|
|
1418 | active. |
|
|
1419 | |
|
|
1420 | =item stopped |
|
|
1421 | |
|
|
1422 | A watcher can be stopped implicitly by libev (in which case it might still |
|
|
1423 | be pending), or explicitly by calling its C<ev_TYPE_stop> function. The |
|
|
1424 | latter will clear any pending state the watcher might be in, regardless |
|
|
1425 | of whether it was active or not, so stopping a watcher explicitly before |
|
|
1426 | freeing it is often a good idea. |
|
|
1427 | |
|
|
1428 | While stopped (and not pending) the watcher is essentially in the |
|
|
1429 | initialised state, that is it can be reused, moved, modified in any way |
|
|
1430 | you wish. |
|
|
1431 | |
|
|
1432 | =back |
1424 | |
1433 | |
1425 | =head2 WATCHER PRIORITY MODELS |
1434 | =head2 WATCHER PRIORITY MODELS |
1426 | |
1435 | |
1427 | Many event loops support I<watcher priorities>, which are usually small |
1436 | Many event loops support I<watcher priorities>, which are usually small |
1428 | integers that influence the ordering of event callback invocation |
1437 | integers that influence the ordering of event callback invocation |
… | |
… | |
3092 | |
3101 | |
3093 | =head3 Watcher-Specific Functions and Data Members |
3102 | =head3 Watcher-Specific Functions and Data Members |
3094 | |
3103 | |
3095 | =over 4 |
3104 | =over 4 |
3096 | |
3105 | |
3097 | =item ev_fork_init (ev_signal *, callback) |
3106 | =item ev_fork_init (ev_fork *, callback) |
3098 | |
3107 | |
3099 | Initialises and configures the fork watcher - it has no parameters of any |
3108 | Initialises and configures the fork watcher - it has no parameters of any |
3100 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
3109 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
3101 | believe me. |
3110 | really. |
3102 | |
3111 | |
3103 | =back |
3112 | =back |
|
|
3113 | |
|
|
3114 | |
|
|
3115 | =head2 C<ev_cleanup> - even the best things end |
|
|
3116 | |
|
|
3117 | Cleanup watchers are called just before the event loop is being destroyed |
|
|
3118 | by a call to C<ev_loop_destroy>. |
|
|
3119 | |
|
|
3120 | While there is no guarantee that the event loop gets destroyed, cleanup |
|
|
3121 | watchers provide a convenient method to install cleanup hooks for your |
|
|
3122 | program, worker threads and so on - you just to make sure to destroy the |
|
|
3123 | loop when you want them to be invoked. |
|
|
3124 | |
|
|
3125 | Cleanup watchers are invoked in the same way as any other watcher. Unlike |
|
|
3126 | all other watchers, they do not keep a reference to the event loop (which |
|
|
3127 | makes a lot of sense if you think about it). Like all other watchers, you |
|
|
3128 | can call libev functions in the callback, except C<ev_cleanup_start>. |
|
|
3129 | |
|
|
3130 | =head3 Watcher-Specific Functions and Data Members |
|
|
3131 | |
|
|
3132 | =over 4 |
|
|
3133 | |
|
|
3134 | =item ev_cleanup_init (ev_cleanup *, callback) |
|
|
3135 | |
|
|
3136 | Initialises and configures the cleanup watcher - it has no parameters of |
|
|
3137 | any kind. There is a C<ev_cleanup_set> macro, but using it is utterly |
|
|
3138 | pointless, I assure you. |
|
|
3139 | |
|
|
3140 | =back |
|
|
3141 | |
|
|
3142 | Example: Register an atexit handler to destroy the default loop, so any |
|
|
3143 | cleanup functions are called. |
|
|
3144 | |
|
|
3145 | static void |
|
|
3146 | program_exits (void) |
|
|
3147 | { |
|
|
3148 | ev_loop_destroy (EV_DEFAULT_UC); |
|
|
3149 | } |
|
|
3150 | |
|
|
3151 | ... |
|
|
3152 | atexit (program_exits); |
3104 | |
3153 | |
3105 | |
3154 | |
3106 | =head2 C<ev_async> - how to wake up an event loop |
3155 | =head2 C<ev_async> - how to wake up an event loop |
3107 | |
3156 | |
3108 | In general, you cannot use an C<ev_run> from multiple threads or other |
3157 | In general, you cannot use an C<ev_run> from multiple threads or other |
… | |
… | |
4715 | structure (guaranteed by POSIX but not by ISO C for example), but it also |
4764 | structure (guaranteed by POSIX but not by ISO C for example), but it also |
4716 | assumes that the same (machine) code can be used to call any watcher |
4765 | assumes that the same (machine) code can be used to call any watcher |
4717 | callback: The watcher callbacks have different type signatures, but libev |
4766 | callback: The watcher callbacks have different type signatures, but libev |
4718 | calls them using an C<ev_watcher *> internally. |
4767 | calls them using an C<ev_watcher *> internally. |
4719 | |
4768 | |
|
|
4769 | =item pointer accesses must be thread-atomic |
|
|
4770 | |
|
|
4771 | Accessing a pointer value must be atomic, it must both be readable and |
|
|
4772 | writable in one piece - this is the case on all current architectures. |
|
|
4773 | |
4720 | =item C<sig_atomic_t volatile> must be thread-atomic as well |
4774 | =item C<sig_atomic_t volatile> must be thread-atomic as well |
4721 | |
4775 | |
4722 | The type C<sig_atomic_t volatile> (or whatever is defined as |
4776 | The type C<sig_atomic_t volatile> (or whatever is defined as |
4723 | C<EV_ATOMIC_T>) must be atomic with respect to accesses from different |
4777 | C<EV_ATOMIC_T>) must be atomic with respect to accesses from different |
4724 | threads. This is not part of the specification for C<sig_atomic_t>, but is |
4778 | threads. This is not part of the specification for C<sig_atomic_t>, but is |
… | |
… | |
4830 | =back |
4884 | =back |
4831 | |
4885 | |
4832 | |
4886 | |
4833 | =head1 PORTING FROM LIBEV 3.X TO 4.X |
4887 | =head1 PORTING FROM LIBEV 3.X TO 4.X |
4834 | |
4888 | |
4835 | The major version 4 introduced some minor incompatible changes to the API. |
4889 | The major version 4 introduced some incompatible changes to the API. |
4836 | |
4890 | |
4837 | At the moment, the C<ev.h> header file tries to implement superficial |
4891 | At the moment, the C<ev.h> header file provides compatibility definitions |
4838 | compatibility, so most programs should still compile. Those might be |
4892 | for all changes, so most programs should still compile. The compatibility |
4839 | removed in later versions of libev, so better update early than late. |
4893 | layer might be removed in later versions of libev, so better update to the |
|
|
4894 | new API early than late. |
4840 | |
4895 | |
4841 | =over 4 |
4896 | =over 4 |
4842 | |
4897 | |
|
|
4898 | =item C<EV_COMPAT3> backwards compatibility mechanism |
|
|
4899 | |
|
|
4900 | The backward compatibility mechanism can be controlled by |
|
|
4901 | C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING> |
|
|
4902 | section. |
|
|
4903 | |
4843 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
4904 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
4844 | |
4905 | |
4845 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
4906 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
4846 | |
4907 | |
4847 | ev_loop_destroy (EV_DEFAULT); |
4908 | ev_loop_destroy (EV_DEFAULT_UC); |
4848 | ev_loop_fork (EV_DEFAULT); |
4909 | ev_loop_fork (EV_DEFAULT); |
4849 | |
4910 | |
4850 | =item function/symbol renames |
4911 | =item function/symbol renames |
4851 | |
4912 | |
4852 | A number of functions and symbols have been renamed: |
4913 | A number of functions and symbols have been renamed: |
… | |
… | |
4872 | ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme |
4933 | ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme |
4873 | as all other watcher types. Note that C<ev_loop_fork> is still called |
4934 | as all other watcher types. Note that C<ev_loop_fork> is still called |
4874 | C<ev_loop_fork> because it would otherwise clash with the C<ev_fork> |
4935 | C<ev_loop_fork> because it would otherwise clash with the C<ev_fork> |
4875 | typedef. |
4936 | typedef. |
4876 | |
4937 | |
4877 | =item C<EV_COMPAT3> backwards compatibility mechanism |
|
|
4878 | |
|
|
4879 | The backward compatibility mechanism can be controlled by |
|
|
4880 | C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING> |
|
|
4881 | section. |
|
|
4882 | |
|
|
4883 | =item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> |
4938 | =item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> |
4884 | |
4939 | |
4885 | The preprocessor symbol C<EV_MINIMAL> has been replaced by a different |
4940 | The preprocessor symbol C<EV_MINIMAL> has been replaced by a different |
4886 | mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile |
4941 | mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile |
4887 | and work, but the library code will of course be larger. |
4942 | and work, but the library code will of course be larger. |
… | |
… | |
4961 | |
5016 | |
4962 | =back |
5017 | =back |
4963 | |
5018 | |
4964 | =head1 AUTHOR |
5019 | =head1 AUTHOR |
4965 | |
5020 | |
4966 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |
5021 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael |
|
|
5022 | Magnusson and Emanuele Giaquinta. |
4967 | |
5023 | |