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1 | =encoding utf-8 |
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2 | |
1 | =head1 NAME |
3 | =head1 NAME |
2 | |
4 | |
3 | libev - a high performance full-featured event loop written in C |
5 | libev - a high performance full-featured event loop written in C |
4 | |
6 | |
5 | =head1 SYNOPSIS |
7 | =head1 SYNOPSIS |
… | |
… | |
414 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
416 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
415 | without a system call and thus I<very> fast, but my GNU/Linux system also has |
417 | without a system call and thus I<very> fast, but my GNU/Linux system also has |
416 | C<pthread_atfork> which is even faster). |
418 | C<pthread_atfork> which is even faster). |
417 | |
419 | |
418 | The big advantage of this flag is that you can forget about fork (and |
420 | The big advantage of this flag is that you can forget about fork (and |
419 | forget about forgetting to tell libev about forking) when you use this |
421 | forget about forgetting to tell libev about forking, although you still |
420 | flag. |
422 | have to ignore C<SIGPIPE>) when you use this flag. |
421 | |
423 | |
422 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
424 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
423 | environment variable. |
425 | environment variable. |
424 | |
426 | |
425 | =item C<EVFLAG_NOINOTIFY> |
427 | =item C<EVFLAG_NOINOTIFY> |
… | |
… | |
680 | If you need dynamically allocated loops it is better to use C<ev_loop_new> |
682 | If you need dynamically allocated loops it is better to use C<ev_loop_new> |
681 | and C<ev_loop_destroy>. |
683 | and C<ev_loop_destroy>. |
682 | |
684 | |
683 | =item ev_loop_fork (loop) |
685 | =item ev_loop_fork (loop) |
684 | |
686 | |
685 | This function sets a flag that causes subsequent C<ev_run> iterations to |
687 | This function sets a flag that causes subsequent C<ev_run> iterations |
686 | reinitialise the kernel state for backends that have one. Despite the |
688 | to reinitialise the kernel state for backends that have one. Despite |
687 | name, you can call it anytime, but it makes most sense after forking, in |
689 | the name, you can call it anytime you are allowed to start or stop |
688 | the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the |
690 | watchers (except inside an C<ev_prepare> callback), but it makes most |
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691 | sense after forking, in the child process. You I<must> call it (or use |
689 | child before resuming or calling C<ev_run>. |
692 | C<EVFLAG_FORKCHECK>) in the child before resuming or calling C<ev_run>. |
690 | |
693 | |
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694 | In addition, if you want to reuse a loop (via this function or |
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695 | C<EVFLAG_FORKCHECK>), you I<also> have to ignore C<SIGPIPE>. |
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696 | |
691 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
697 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
692 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
698 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
693 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
699 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
694 | during fork. |
700 | during fork. |
695 | |
701 | |
696 | On the other hand, you only need to call this function in the child |
702 | On the other hand, you only need to call this function in the child |
… | |
… | |
2026 | |
2032 | |
2027 | The relative timeouts are calculated relative to the C<ev_now ()> |
2033 | The relative timeouts are calculated relative to the C<ev_now ()> |
2028 | time. This is usually the right thing as this timestamp refers to the time |
2034 | time. This is usually the right thing as this timestamp refers to the time |
2029 | of the event triggering whatever timeout you are modifying/starting. If |
2035 | of the event triggering whatever timeout you are modifying/starting. If |
2030 | you suspect event processing to be delayed and you I<need> to base the |
2036 | you suspect event processing to be delayed and you I<need> to base the |
2031 | timeout on the current time, use something like this to adjust for this: |
2037 | timeout on the current time, use something like the following to adjust |
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2038 | for it: |
2032 | |
2039 | |
2033 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
2040 | ev_timer_set (&timer, after + (ev_time () - ev_now ()), 0.); |
2034 | |
2041 | |
2035 | If the event loop is suspended for a long time, you can also force an |
2042 | If the event loop is suspended for a long time, you can also force an |
2036 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
2043 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
2037 | ()>. |
2044 | ()>, although that will push the event time of all outstanding events |
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2045 | further into the future. |
2038 | |
2046 | |
2039 | =head3 The special problem of unsynchronised clocks |
2047 | =head3 The special problem of unsynchronised clocks |
2040 | |
2048 | |
2041 | Modern systems have a variety of clocks - libev itself uses the normal |
2049 | Modern systems have a variety of clocks - libev itself uses the normal |
2042 | "wall clock" clock and, if available, the monotonic clock (to avoid time |
2050 | "wall clock" clock and, if available, the monotonic clock (to avoid time |
… | |
… | |
2391 | |
2399 | |
2392 | ev_periodic hourly_tick; |
2400 | ev_periodic hourly_tick; |
2393 | ev_periodic_init (&hourly_tick, clock_cb, |
2401 | ev_periodic_init (&hourly_tick, clock_cb, |
2394 | fmod (ev_now (loop), 3600.), 3600., 0); |
2402 | fmod (ev_now (loop), 3600.), 3600., 0); |
2395 | ev_periodic_start (loop, &hourly_tick); |
2403 | ev_periodic_start (loop, &hourly_tick); |
2396 | |
2404 | |
2397 | |
2405 | |
2398 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
2406 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
2399 | |
2407 | |
2400 | Signal watchers will trigger an event when the process receives a specific |
2408 | Signal watchers will trigger an event when the process receives a specific |
2401 | signal one or more times. Even though signals are very asynchronous, libev |
2409 | signal one or more times. Even though signals are very asynchronous, libev |
… | |
… | |
2411 | only within the same loop, i.e. you can watch for C<SIGINT> in your |
2419 | only within the same loop, i.e. you can watch for C<SIGINT> in your |
2412 | default loop and for C<SIGIO> in another loop, but you cannot watch for |
2420 | default loop and for C<SIGIO> in another loop, but you cannot watch for |
2413 | C<SIGINT> in both the default loop and another loop at the same time. At |
2421 | C<SIGINT> in both the default loop and another loop at the same time. At |
2414 | the moment, C<SIGCHLD> is permanently tied to the default loop. |
2422 | the moment, C<SIGCHLD> is permanently tied to the default loop. |
2415 | |
2423 | |
2416 | When the first watcher gets started will libev actually register something |
2424 | Only after the first watcher for a signal is started will libev actually |
2417 | with the kernel (thus it coexists with your own signal handlers as long as |
2425 | register something with the kernel. It thus coexists with your own signal |
2418 | you don't register any with libev for the same signal). |
2426 | handlers as long as you don't register any with libev for the same signal. |
2419 | |
2427 | |
2420 | If possible and supported, libev will install its handlers with |
2428 | If possible and supported, libev will install its handlers with |
2421 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2429 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2422 | not be unduly interrupted. If you have a problem with system calls getting |
2430 | not be unduly interrupted. If you have a problem with system calls getting |
2423 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2431 | interrupted by signals you can block all signals in an C<ev_check> watcher |
… | |
… | |
2905 | |
2913 | |
2906 | Prepare and check watchers are often (but not always) used in pairs: |
2914 | Prepare and check watchers are often (but not always) used in pairs: |
2907 | prepare watchers get invoked before the process blocks and check watchers |
2915 | prepare watchers get invoked before the process blocks and check watchers |
2908 | afterwards. |
2916 | afterwards. |
2909 | |
2917 | |
2910 | You I<must not> call C<ev_run> or similar functions that enter |
2918 | You I<must not> call C<ev_run> (or similar functions that enter the |
2911 | the current event loop from either C<ev_prepare> or C<ev_check> |
2919 | current event loop) or C<ev_loop_fork> from either C<ev_prepare> or |
2912 | watchers. Other loops than the current one are fine, however. The |
2920 | C<ev_check> watchers. Other loops than the current one are fine, |
2913 | rationale behind this is that you do not need to check for recursion in |
2921 | however. The rationale behind this is that you do not need to check |
2914 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2922 | for recursion in those watchers, i.e. the sequence will always be |
2915 | C<ev_check> so if you have one watcher of each kind they will always be |
2923 | C<ev_prepare>, blocking, C<ev_check> so if you have one watcher of each |
2916 | called in pairs bracketing the blocking call. |
2924 | kind they will always be called in pairs bracketing the blocking call. |
2917 | |
2925 | |
2918 | Their main purpose is to integrate other event mechanisms into libev and |
2926 | Their main purpose is to integrate other event mechanisms into libev and |
2919 | their use is somewhat advanced. They could be used, for example, to track |
2927 | their use is somewhat advanced. They could be used, for example, to track |
2920 | variable changes, implement your own watchers, integrate net-snmp or a |
2928 | variable changes, implement your own watchers, integrate net-snmp or a |
2921 | coroutine library and lots more. They are also occasionally useful if |
2929 | coroutine library and lots more. They are also occasionally useful if |
… | |
… | |
3211 | used). |
3219 | used). |
3212 | |
3220 | |
3213 | struct ev_loop *loop_hi = ev_default_init (0); |
3221 | struct ev_loop *loop_hi = ev_default_init (0); |
3214 | struct ev_loop *loop_lo = 0; |
3222 | struct ev_loop *loop_lo = 0; |
3215 | ev_embed embed; |
3223 | ev_embed embed; |
3216 | |
3224 | |
3217 | // see if there is a chance of getting one that works |
3225 | // see if there is a chance of getting one that works |
3218 | // (remember that a flags value of 0 means autodetection) |
3226 | // (remember that a flags value of 0 means autodetection) |
3219 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3227 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3220 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3228 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3221 | : 0; |
3229 | : 0; |
… | |
… | |
3235 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
3243 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
3236 | |
3244 | |
3237 | struct ev_loop *loop = ev_default_init (0); |
3245 | struct ev_loop *loop = ev_default_init (0); |
3238 | struct ev_loop *loop_socket = 0; |
3246 | struct ev_loop *loop_socket = 0; |
3239 | ev_embed embed; |
3247 | ev_embed embed; |
3240 | |
3248 | |
3241 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3249 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3242 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3250 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3243 | { |
3251 | { |
3244 | ev_embed_init (&embed, 0, loop_socket); |
3252 | ev_embed_init (&embed, 0, loop_socket); |
3245 | ev_embed_start (loop, &embed); |
3253 | ev_embed_start (loop, &embed); |
… | |
… | |
3261 | and calls it in the wrong process, the fork handlers will be invoked, too, |
3269 | and calls it in the wrong process, the fork handlers will be invoked, too, |
3262 | of course. |
3270 | of course. |
3263 | |
3271 | |
3264 | =head3 The special problem of life after fork - how is it possible? |
3272 | =head3 The special problem of life after fork - how is it possible? |
3265 | |
3273 | |
3266 | Most uses of C<fork()> consist of forking, then some simple calls to set |
3274 | Most uses of C<fork ()> consist of forking, then some simple calls to set |
3267 | up/change the process environment, followed by a call to C<exec()>. This |
3275 | up/change the process environment, followed by a call to C<exec()>. This |
3268 | sequence should be handled by libev without any problems. |
3276 | sequence should be handled by libev without any problems. |
3269 | |
3277 | |
3270 | This changes when the application actually wants to do event handling |
3278 | This changes when the application actually wants to do event handling |
3271 | in the child, or both parent in child, in effect "continuing" after the |
3279 | in the child, or both parent in child, in effect "continuing" after the |
… | |
… | |
3895 | To embed libev, see L</EMBEDDING>, but in short, it's easiest to create two |
3903 | To embed libev, see L</EMBEDDING>, but in short, it's easiest to create two |
3896 | files, F<my_ev.h> and F<my_ev.c> that include the respective libev files: |
3904 | files, F<my_ev.h> and F<my_ev.c> that include the respective libev files: |
3897 | |
3905 | |
3898 | // my_ev.h |
3906 | // my_ev.h |
3899 | #define EV_CB_DECLARE(type) struct my_coro *cb; |
3907 | #define EV_CB_DECLARE(type) struct my_coro *cb; |
3900 | #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb); |
3908 | #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb) |
3901 | #include "../libev/ev.h" |
3909 | #include "../libev/ev.h" |
3902 | |
3910 | |
3903 | // my_ev.c |
3911 | // my_ev.c |
3904 | #define EV_H "my_ev.h" |
3912 | #define EV_H "my_ev.h" |
3905 | #include "../libev/ev.c" |
3913 | #include "../libev/ev.c" |
… | |
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3982 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
3990 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
3983 | you to use some convenience methods to start/stop watchers and also change |
3991 | you to use some convenience methods to start/stop watchers and also change |
3984 | the callback model to a model using method callbacks on objects. |
3992 | the callback model to a model using method callbacks on objects. |
3985 | |
3993 | |
3986 | To use it, |
3994 | To use it, |
3987 | |
3995 | |
3988 | #include <ev++.h> |
3996 | #include <ev++.h> |
3989 | |
3997 | |
3990 | This automatically includes F<ev.h> and puts all of its definitions (many |
3998 | This automatically includes F<ev.h> and puts all of its definitions (many |
3991 | of them macros) into the global namespace. All C++ specific things are |
3999 | of them macros) into the global namespace. All C++ specific things are |
3992 | put into the C<ev> namespace. It should support all the same embedding |
4000 | put into the C<ev> namespace. It should support all the same embedding |
… | |
… | |
4095 | void operator() (ev::io &w, int revents) |
4103 | void operator() (ev::io &w, int revents) |
4096 | { |
4104 | { |
4097 | ... |
4105 | ... |
4098 | } |
4106 | } |
4099 | } |
4107 | } |
4100 | |
4108 | |
4101 | myfunctor f; |
4109 | myfunctor f; |
4102 | |
4110 | |
4103 | ev::io w; |
4111 | ev::io w; |
4104 | w.set (&f); |
4112 | w.set (&f); |
4105 | |
4113 | |
… | |
… | |
5429 | =over 4 |
5437 | =over 4 |
5430 | |
5438 | |
5431 | =item C<EV_COMPAT3> backwards compatibility mechanism |
5439 | =item C<EV_COMPAT3> backwards compatibility mechanism |
5432 | |
5440 | |
5433 | The backward compatibility mechanism can be controlled by |
5441 | The backward compatibility mechanism can be controlled by |
5434 | C<EV_COMPAT3>. See L</PREPROCESSOR SYMBOLS/MACROS> in the L</EMBEDDING> |
5442 | C<EV_COMPAT3>. See L</"PREPROCESSOR SYMBOLS/MACROS"> in the L</EMBEDDING> |
5435 | section. |
5443 | section. |
5436 | |
5444 | |
5437 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
5445 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
5438 | |
5446 | |
5439 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
5447 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |