… | |
… | |
411 | make libev check for a fork in each iteration by enabling this flag. |
411 | make libev check for a fork in each iteration by enabling this flag. |
412 | |
412 | |
413 | This works by calling C<getpid ()> on every iteration of the loop, |
413 | This works by calling C<getpid ()> on every iteration of the loop, |
414 | and thus this might slow down your event loop if you do a lot of loop |
414 | and thus this might slow down your event loop if you do a lot of loop |
415 | iterations and little real work, but is usually not noticeable (on my |
415 | iterations and little real work, but is usually not noticeable (on my |
416 | 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 |
417 | without a system call and thus I<very> fast, but my GNU/Linux system also has |
417 | sequence without a system call and thus I<very> fast, but my GNU/Linux |
418 | C<pthread_atfork> which is even faster). |
418 | system also has C<pthread_atfork> which is even faster). (Update: glibc |
|
|
419 | versions 2.25 apparently removed the C<getpid> optimisation again). |
419 | |
420 | |
420 | The big advantage of this flag is that you can forget about fork (and |
421 | The big advantage of this flag is that you can forget about fork (and |
421 | forget about forgetting to tell libev about forking) when you use this |
422 | forget about forgetting to tell libev about forking, although you still |
422 | flag. |
423 | have to ignore C<SIGPIPE>) when you use this flag. |
423 | |
424 | |
424 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
425 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
425 | environment variable. |
426 | environment variable. |
426 | |
427 | |
427 | =item C<EVFLAG_NOINOTIFY> |
428 | =item C<EVFLAG_NOINOTIFY> |
… | |
… | |
688 | to reinitialise the kernel state for backends that have one. Despite |
689 | to reinitialise the kernel state for backends that have one. Despite |
689 | the name, you can call it anytime you are allowed to start or stop |
690 | the name, you can call it anytime you are allowed to start or stop |
690 | watchers (except inside an C<ev_prepare> callback), but it makes most |
691 | watchers (except inside an C<ev_prepare> callback), but it makes most |
691 | sense after forking, in the child process. You I<must> call it (or use |
692 | sense after forking, in the child process. You I<must> call it (or use |
692 | C<EVFLAG_FORKCHECK>) in the child before resuming or calling C<ev_run>. |
693 | C<EVFLAG_FORKCHECK>) in the child before resuming or calling C<ev_run>. |
|
|
694 | |
|
|
695 | In addition, if you want to reuse a loop (via this function or |
|
|
696 | C<EVFLAG_FORKCHECK>), you I<also> have to ignore C<SIGPIPE>. |
693 | |
697 | |
694 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
698 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
695 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
699 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
696 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
700 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
697 | during fork. |
701 | during fork. |
… | |
… | |
2029 | |
2033 | |
2030 | The relative timeouts are calculated relative to the C<ev_now ()> |
2034 | The relative timeouts are calculated relative to the C<ev_now ()> |
2031 | time. This is usually the right thing as this timestamp refers to the time |
2035 | time. This is usually the right thing as this timestamp refers to the time |
2032 | of the event triggering whatever timeout you are modifying/starting. If |
2036 | of the event triggering whatever timeout you are modifying/starting. If |
2033 | you suspect event processing to be delayed and you I<need> to base the |
2037 | you suspect event processing to be delayed and you I<need> to base the |
2034 | timeout on the current time, use something like this to adjust for this: |
2038 | timeout on the current time, use something like the following to adjust |
|
|
2039 | for it: |
2035 | |
2040 | |
2036 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
2041 | ev_timer_set (&timer, after + (ev_time () - ev_now ()), 0.); |
2037 | |
2042 | |
2038 | If the event loop is suspended for a long time, you can also force an |
2043 | If the event loop is suspended for a long time, you can also force an |
2039 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
2044 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
2040 | ()>. |
2045 | ()>, although that will push the event time of all outstanding events |
|
|
2046 | further into the future. |
2041 | |
2047 | |
2042 | =head3 The special problem of unsynchronised clocks |
2048 | =head3 The special problem of unsynchronised clocks |
2043 | |
2049 | |
2044 | Modern systems have a variety of clocks - libev itself uses the normal |
2050 | Modern systems have a variety of clocks - libev itself uses the normal |
2045 | "wall clock" clock and, if available, the monotonic clock (to avoid time |
2051 | "wall clock" clock and, if available, the monotonic clock (to avoid time |
… | |
… | |
2108 | |
2114 | |
2109 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
2115 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
2110 | |
2116 | |
2111 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
2117 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
2112 | |
2118 | |
2113 | Configure the timer to trigger after C<after> seconds. If C<repeat> |
2119 | Configure the timer to trigger after C<after> seconds (fractional and |
2114 | is C<0.>, then it will automatically be stopped once the timeout is |
2120 | negative values are supported). If C<repeat> is C<0.>, then it will |
2115 | reached. If it is positive, then the timer will automatically be |
2121 | automatically be stopped once the timeout is reached. If it is positive, |
2116 | configured to trigger again C<repeat> seconds later, again, and again, |
2122 | then the timer will automatically be configured to trigger again C<repeat> |
2117 | until stopped manually. |
2123 | seconds later, again, and again, until stopped manually. |
2118 | |
2124 | |
2119 | The timer itself will do a best-effort at avoiding drift, that is, if |
2125 | The timer itself will do a best-effort at avoiding drift, that is, if |
2120 | you configure a timer to trigger every 10 seconds, then it will normally |
2126 | you configure a timer to trigger every 10 seconds, then it will normally |
2121 | trigger at exactly 10 second intervals. If, however, your program cannot |
2127 | trigger at exactly 10 second intervals. If, however, your program cannot |
2122 | keep up with the timer (because it takes longer than those 10 seconds to |
2128 | keep up with the timer (because it takes longer than those 10 seconds to |
… | |
… | |
2204 | Periodic watchers are also timers of a kind, but they are very versatile |
2210 | Periodic watchers are also timers of a kind, but they are very versatile |
2205 | (and unfortunately a bit complex). |
2211 | (and unfortunately a bit complex). |
2206 | |
2212 | |
2207 | Unlike C<ev_timer>, periodic watchers are not based on real time (or |
2213 | Unlike C<ev_timer>, periodic watchers are not based on real time (or |
2208 | relative time, the physical time that passes) but on wall clock time |
2214 | relative time, the physical time that passes) but on wall clock time |
2209 | (absolute time, the thing you can read on your calender or clock). The |
2215 | (absolute time, the thing you can read on your calendar or clock). The |
2210 | difference is that wall clock time can run faster or slower than real |
2216 | difference is that wall clock time can run faster or slower than real |
2211 | time, and time jumps are not uncommon (e.g. when you adjust your |
2217 | time, and time jumps are not uncommon (e.g. when you adjust your |
2212 | wrist-watch). |
2218 | wrist-watch). |
2213 | |
2219 | |
2214 | You can tell a periodic watcher to trigger after some specific point |
2220 | You can tell a periodic watcher to trigger after some specific point |
… | |
… | |
2219 | C<ev_timer>, which would still trigger roughly 10 seconds after starting |
2225 | C<ev_timer>, which would still trigger roughly 10 seconds after starting |
2220 | it, as it uses a relative timeout). |
2226 | it, as it uses a relative timeout). |
2221 | |
2227 | |
2222 | C<ev_periodic> watchers can also be used to implement vastly more complex |
2228 | C<ev_periodic> watchers can also be used to implement vastly more complex |
2223 | timers, such as triggering an event on each "midnight, local time", or |
2229 | timers, such as triggering an event on each "midnight, local time", or |
2224 | other complicated rules. This cannot be done with C<ev_timer> watchers, as |
2230 | other complicated rules. This cannot easily be done with C<ev_timer> |
2225 | those cannot react to time jumps. |
2231 | watchers, as those cannot react to time jumps. |
2226 | |
2232 | |
2227 | As with timers, the callback is guaranteed to be invoked only when the |
2233 | As with timers, the callback is guaranteed to be invoked only when the |
2228 | point in time where it is supposed to trigger has passed. If multiple |
2234 | point in time where it is supposed to trigger has passed. If multiple |
2229 | timers become ready during the same loop iteration then the ones with |
2235 | timers become ready during the same loop iteration then the ones with |
2230 | earlier time-out values are invoked before ones with later time-out values |
2236 | earlier time-out values are invoked before ones with later time-out values |
… | |
… | |
2316 | |
2322 | |
2317 | NOTE: I<< This callback must always return a time that is higher than or |
2323 | NOTE: I<< This callback must always return a time that is higher than or |
2318 | equal to the passed C<now> value >>. |
2324 | equal to the passed C<now> value >>. |
2319 | |
2325 | |
2320 | This can be used to create very complex timers, such as a timer that |
2326 | This can be used to create very complex timers, such as a timer that |
2321 | triggers on "next midnight, local time". To do this, you would calculate the |
2327 | triggers on "next midnight, local time". To do this, you would calculate |
2322 | next midnight after C<now> and return the timestamp value for this. How |
2328 | the next midnight after C<now> and return the timestamp value for |
2323 | you do this is, again, up to you (but it is not trivial, which is the main |
2329 | this. Here is a (completely untested, no error checking) example on how to |
2324 | reason I omitted it as an example). |
2330 | do this: |
|
|
2331 | |
|
|
2332 | #include <time.h> |
|
|
2333 | |
|
|
2334 | static ev_tstamp |
|
|
2335 | my_rescheduler (ev_periodic *w, ev_tstamp now) |
|
|
2336 | { |
|
|
2337 | time_t tnow = (time_t)now; |
|
|
2338 | struct tm tm; |
|
|
2339 | localtime_r (&tnow, &tm); |
|
|
2340 | |
|
|
2341 | tm.tm_sec = tm.tm_min = tm.tm_hour = 0; // midnight current day |
|
|
2342 | ++tm.tm_mday; // midnight next day |
|
|
2343 | |
|
|
2344 | return mktime (&tm); |
|
|
2345 | } |
|
|
2346 | |
|
|
2347 | Note: this code might run into trouble on days that have more then two |
|
|
2348 | midnights (beginning and end). |
2325 | |
2349 | |
2326 | =back |
2350 | =back |
2327 | |
2351 | |
2328 | =item ev_periodic_again (loop, ev_periodic *) |
2352 | =item ev_periodic_again (loop, ev_periodic *) |
2329 | |
2353 | |
… | |
… | |
3512 | |
3536 | |
3513 | There are some other functions of possible interest. Described. Here. Now. |
3537 | There are some other functions of possible interest. Described. Here. Now. |
3514 | |
3538 | |
3515 | =over 4 |
3539 | =over 4 |
3516 | |
3540 | |
3517 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback) |
3541 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback, arg) |
3518 | |
3542 | |
3519 | This function combines a simple timer and an I/O watcher, calls your |
3543 | This function combines a simple timer and an I/O watcher, calls your |
3520 | callback on whichever event happens first and automatically stops both |
3544 | callback on whichever event happens first and automatically stops both |
3521 | watchers. This is useful if you want to wait for a single event on an fd |
3545 | watchers. This is useful if you want to wait for a single event on an fd |
3522 | or timeout without having to allocate/configure/start/stop/free one or |
3546 | or timeout without having to allocate/configure/start/stop/free one or |
… | |
… | |
3898 | To embed libev, see L</EMBEDDING>, but in short, it's easiest to create two |
3922 | To embed libev, see L</EMBEDDING>, but in short, it's easiest to create two |
3899 | files, F<my_ev.h> and F<my_ev.c> that include the respective libev files: |
3923 | files, F<my_ev.h> and F<my_ev.c> that include the respective libev files: |
3900 | |
3924 | |
3901 | // my_ev.h |
3925 | // my_ev.h |
3902 | #define EV_CB_DECLARE(type) struct my_coro *cb; |
3926 | #define EV_CB_DECLARE(type) struct my_coro *cb; |
3903 | #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb); |
3927 | #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb) |
3904 | #include "../libev/ev.h" |
3928 | #include "../libev/ev.h" |
3905 | |
3929 | |
3906 | // my_ev.c |
3930 | // my_ev.c |
3907 | #define EV_H "my_ev.h" |
3931 | #define EV_H "my_ev.h" |
3908 | #include "../libev/ev.c" |
3932 | #include "../libev/ev.c" |
… | |
… | |
3954 | The normal C API should work fine when used from C++: both ev.h and the |
3978 | The normal C API should work fine when used from C++: both ev.h and the |
3955 | libev sources can be compiled as C++. Therefore, code that uses the C API |
3979 | libev sources can be compiled as C++. Therefore, code that uses the C API |
3956 | will work fine. |
3980 | will work fine. |
3957 | |
3981 | |
3958 | Proper exception specifications might have to be added to callbacks passed |
3982 | Proper exception specifications might have to be added to callbacks passed |
3959 | to libev: exceptions may be thrown only from watcher callbacks, all |
3983 | to libev: exceptions may be thrown only from watcher callbacks, all other |
3960 | other callbacks (allocator, syserr, loop acquire/release and periodic |
3984 | callbacks (allocator, syserr, loop acquire/release and periodic reschedule |
3961 | reschedule callbacks) must not throw exceptions, and might need a C<throw |
3985 | callbacks) must not throw exceptions, and might need a C<noexcept> |
3962 | ()> specification. If you have code that needs to be compiled as both C |
3986 | specification. If you have code that needs to be compiled as both C and |
3963 | and C++ you can use the C<EV_THROW> macro for this: |
3987 | C++ you can use the C<EV_NOEXCEPT> macro for this: |
3964 | |
3988 | |
3965 | static void |
3989 | static void |
3966 | fatal_error (const char *msg) EV_THROW |
3990 | fatal_error (const char *msg) EV_NOEXCEPT |
3967 | { |
3991 | { |
3968 | perror (msg); |
3992 | perror (msg); |
3969 | abort (); |
3993 | abort (); |
3970 | } |
3994 | } |
3971 | |
3995 | |
… | |
… | |
4381 | ev_vars.h |
4405 | ev_vars.h |
4382 | ev_wrap.h |
4406 | ev_wrap.h |
4383 | |
4407 | |
4384 | ev_win32.c required on win32 platforms only |
4408 | ev_win32.c required on win32 platforms only |
4385 | |
4409 | |
4386 | ev_select.c only when select backend is enabled (which is enabled by default) |
4410 | ev_select.c only when select backend is enabled |
4387 | ev_poll.c only when poll backend is enabled (disabled by default) |
4411 | ev_poll.c only when poll backend is enabled |
4388 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
4412 | ev_epoll.c only when the epoll backend is enabled |
4389 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
4413 | ev_kqueue.c only when the kqueue backend is enabled |
4390 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
4414 | ev_port.c only when the solaris port backend is enabled |
4391 | |
4415 | |
4392 | F<ev.c> includes the backend files directly when enabled, so you only need |
4416 | F<ev.c> includes the backend files directly when enabled, so you only need |
4393 | to compile this single file. |
4417 | to compile this single file. |
4394 | |
4418 | |
4395 | =head3 LIBEVENT COMPATIBILITY API |
4419 | =head3 LIBEVENT COMPATIBILITY API |
… | |
… | |
5295 | structure (guaranteed by POSIX but not by ISO C for example), but it also |
5319 | structure (guaranteed by POSIX but not by ISO C for example), but it also |
5296 | assumes that the same (machine) code can be used to call any watcher |
5320 | assumes that the same (machine) code can be used to call any watcher |
5297 | callback: The watcher callbacks have different type signatures, but libev |
5321 | callback: The watcher callbacks have different type signatures, but libev |
5298 | calls them using an C<ev_watcher *> internally. |
5322 | calls them using an C<ev_watcher *> internally. |
5299 | |
5323 | |
|
|
5324 | =item null pointers and integer zero are represented by 0 bytes |
|
|
5325 | |
|
|
5326 | Libev uses C<memset> to initialise structs and arrays to C<0> bytes, and |
|
|
5327 | relies on this setting pointers and integers to null. |
|
|
5328 | |
5300 | =item pointer accesses must be thread-atomic |
5329 | =item pointer accesses must be thread-atomic |
5301 | |
5330 | |
5302 | Accessing a pointer value must be atomic, it must both be readable and |
5331 | Accessing a pointer value must be atomic, it must both be readable and |
5303 | writable in one piece - this is the case on all current architectures. |
5332 | writable in one piece - this is the case on all current architectures. |
5304 | |
5333 | |