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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 |
… | |
… | |
396 | |
398 | |
397 | If this flag bit is or'ed into the flag value (or the program runs setuid |
399 | If this flag bit is or'ed into the flag value (or the program runs setuid |
398 | or setgid) then libev will I<not> look at the environment variable |
400 | or setgid) then libev will I<not> look at the environment variable |
399 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
401 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
400 | override the flags completely if it is found in the environment. This is |
402 | override the flags completely if it is found in the environment. This is |
401 | useful to try out specific backends to test their performance, or to work |
403 | useful to try out specific backends to test their performance, to work |
402 | around bugs. |
404 | around bugs, or to make libev threadsafe (accessing environment variables |
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405 | cannot be done in a threadsafe way, but usually it works if no other |
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406 | thread modifies them). |
403 | |
407 | |
404 | =item C<EVFLAG_FORKCHECK> |
408 | =item C<EVFLAG_FORKCHECK> |
405 | |
409 | |
406 | Instead of calling C<ev_loop_fork> manually after a fork, you can also |
410 | Instead of calling C<ev_loop_fork> manually after a fork, you can also |
407 | 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. |
408 | |
412 | |
409 | 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, |
410 | 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 |
411 | 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 |
412 | 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 |
413 | 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 |
414 | C<pthread_atfork> which is even faster). |
418 | system also has C<pthread_atfork> which is even faster). (Update: glibc |
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419 | versions 2.25 apparently removed the C<getpid> optimisation again). |
415 | |
420 | |
416 | 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 |
417 | forget about forgetting to tell libev about forking) when you use this |
422 | forget about forgetting to tell libev about forking, although you still |
418 | flag. |
423 | have to ignore C<SIGPIPE>) when you use this flag. |
419 | |
424 | |
420 | 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> |
421 | environment variable. |
426 | environment variable. |
422 | |
427 | |
423 | =item C<EVFLAG_NOINOTIFY> |
428 | =item C<EVFLAG_NOINOTIFY> |
… | |
… | |
569 | kernel is more efficient (which says nothing about its actual speed, of |
574 | kernel is more efficient (which says nothing about its actual speed, of |
570 | course). While stopping, setting and starting an I/O watcher does never |
575 | course). While stopping, setting and starting an I/O watcher does never |
571 | cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to |
576 | cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to |
572 | two event changes per incident. Support for C<fork ()> is very bad (you |
577 | two event changes per incident. Support for C<fork ()> is very bad (you |
573 | might have to leak fd's on fork, but it's more sane than epoll) and it |
578 | might have to leak fd's on fork, but it's more sane than epoll) and it |
574 | drops fds silently in similarly hard-to-detect cases |
579 | drops fds silently in similarly hard-to-detect cases. |
575 | |
580 | |
576 | This backend usually performs well under most conditions. |
581 | This backend usually performs well under most conditions. |
577 | |
582 | |
578 | While nominally embeddable in other event loops, this doesn't work |
583 | While nominally embeddable in other event loops, this doesn't work |
579 | everywhere, so you might need to test for this. And since it is broken |
584 | everywhere, so you might need to test for this. And since it is broken |
… | |
… | |
678 | If you need dynamically allocated loops it is better to use C<ev_loop_new> |
683 | If you need dynamically allocated loops it is better to use C<ev_loop_new> |
679 | and C<ev_loop_destroy>. |
684 | and C<ev_loop_destroy>. |
680 | |
685 | |
681 | =item ev_loop_fork (loop) |
686 | =item ev_loop_fork (loop) |
682 | |
687 | |
683 | This function sets a flag that causes subsequent C<ev_run> iterations to |
688 | This function sets a flag that causes subsequent C<ev_run> iterations |
684 | reinitialise the kernel state for backends that have one. Despite the |
689 | to reinitialise the kernel state for backends that have one. Despite |
685 | name, you can call it anytime, but it makes most sense after forking, in |
690 | the name, you can call it anytime you are allowed to start or stop |
686 | the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the |
691 | watchers (except inside an C<ev_prepare> callback), but it makes most |
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692 | sense after forking, in the child process. You I<must> call it (or use |
687 | child before resuming or calling C<ev_run>. |
693 | C<EVFLAG_FORKCHECK>) in the child before resuming or calling C<ev_run>. |
688 | |
694 | |
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695 | In addition, if you want to reuse a loop (via this function or |
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696 | C<EVFLAG_FORKCHECK>), you I<also> have to ignore C<SIGPIPE>. |
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697 | |
689 | 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 |
690 | 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 |
691 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
700 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
692 | during fork. |
701 | during fork. |
693 | |
702 | |
694 | On the other hand, you only need to call this function in the child |
703 | On the other hand, you only need to call this function in the child |
… | |
… | |
1393 | transition between them will be described in more detail - and while these |
1402 | transition between them will be described in more detail - and while these |
1394 | rules might look complicated, they usually do "the right thing". |
1403 | rules might look complicated, they usually do "the right thing". |
1395 | |
1404 | |
1396 | =over 4 |
1405 | =over 4 |
1397 | |
1406 | |
1398 | =item initialiased |
1407 | =item initialised |
1399 | |
1408 | |
1400 | Before a watcher can be registered with the event loop it has to be |
1409 | Before a watcher can be registered with the event loop it has to be |
1401 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
1410 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
1402 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
1411 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
1403 | |
1412 | |
… | |
… | |
2024 | |
2033 | |
2025 | The relative timeouts are calculated relative to the C<ev_now ()> |
2034 | The relative timeouts are calculated relative to the C<ev_now ()> |
2026 | 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 |
2027 | of the event triggering whatever timeout you are modifying/starting. If |
2036 | of the event triggering whatever timeout you are modifying/starting. If |
2028 | 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 |
2029 | 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 |
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2039 | for it: |
2030 | |
2040 | |
2031 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
2041 | ev_timer_set (&timer, after + (ev_time () - ev_now ()), 0.); |
2032 | |
2042 | |
2033 | 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 |
2034 | 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 |
2035 | ()>. |
2045 | ()>, although that will push the event time of all outstanding events |
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2046 | further into the future. |
2036 | |
2047 | |
2037 | =head3 The special problem of unsynchronised clocks |
2048 | =head3 The special problem of unsynchronised clocks |
2038 | |
2049 | |
2039 | 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 |
2040 | "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 |
… | |
… | |
2103 | |
2114 | |
2104 | =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) |
2105 | |
2116 | |
2106 | =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) |
2107 | |
2118 | |
2108 | Configure the timer to trigger after C<after> seconds. If C<repeat> |
2119 | Configure the timer to trigger after C<after> seconds (fractional and |
2109 | 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 |
2110 | reached. If it is positive, then the timer will automatically be |
2121 | automatically be stopped once the timeout is reached. If it is positive, |
2111 | configured to trigger again C<repeat> seconds later, again, and again, |
2122 | then the timer will automatically be configured to trigger again C<repeat> |
2112 | until stopped manually. |
2123 | seconds later, again, and again, until stopped manually. |
2113 | |
2124 | |
2114 | 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 |
2115 | 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 |
2116 | trigger at exactly 10 second intervals. If, however, your program cannot |
2127 | trigger at exactly 10 second intervals. If, however, your program cannot |
2117 | 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 |
… | |
… | |
2199 | 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 |
2200 | (and unfortunately a bit complex). |
2211 | (and unfortunately a bit complex). |
2201 | |
2212 | |
2202 | 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 |
2203 | 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 |
2204 | (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 |
2205 | 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 |
2206 | 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 |
2207 | wrist-watch). |
2218 | wrist-watch). |
2208 | |
2219 | |
2209 | 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 |
… | |
… | |
2214 | 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 |
2215 | it, as it uses a relative timeout). |
2226 | it, as it uses a relative timeout). |
2216 | |
2227 | |
2217 | 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 |
2218 | 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 |
2219 | 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> |
2220 | those cannot react to time jumps. |
2231 | watchers, as those cannot react to time jumps. |
2221 | |
2232 | |
2222 | 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 |
2223 | 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 |
2224 | 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 |
2225 | 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 |
… | |
… | |
2311 | |
2322 | |
2312 | 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 |
2313 | equal to the passed C<now> value >>. |
2324 | equal to the passed C<now> value >>. |
2314 | |
2325 | |
2315 | 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 |
2316 | 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 |
2317 | 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 |
2318 | 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 |
2319 | reason I omitted it as an example). |
2330 | do this: |
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2331 | |
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2332 | #include <time.h> |
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2333 | |
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2334 | static ev_tstamp |
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2335 | my_rescheduler (ev_periodic *w, ev_tstamp now) |
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2336 | { |
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2337 | time_t tnow = (time_t)now; |
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2338 | struct tm tm; |
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2339 | localtime_r (&tnow, &tm); |
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2340 | |
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2341 | tm.tm_sec = tm.tm_min = tm.tm_hour = 0; // midnight current day |
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2342 | ++tm.tm_mday; // midnight next day |
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2343 | |
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2344 | return mktime (&tm); |
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2345 | } |
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2346 | |
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2347 | Note: this code might run into trouble on days that have more then two |
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2348 | midnights (beginning and end). |
2320 | |
2349 | |
2321 | =back |
2350 | =back |
2322 | |
2351 | |
2323 | =item ev_periodic_again (loop, ev_periodic *) |
2352 | =item ev_periodic_again (loop, ev_periodic *) |
2324 | |
2353 | |
… | |
… | |
2389 | |
2418 | |
2390 | ev_periodic hourly_tick; |
2419 | ev_periodic hourly_tick; |
2391 | ev_periodic_init (&hourly_tick, clock_cb, |
2420 | ev_periodic_init (&hourly_tick, clock_cb, |
2392 | fmod (ev_now (loop), 3600.), 3600., 0); |
2421 | fmod (ev_now (loop), 3600.), 3600., 0); |
2393 | ev_periodic_start (loop, &hourly_tick); |
2422 | ev_periodic_start (loop, &hourly_tick); |
2394 | |
2423 | |
2395 | |
2424 | |
2396 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
2425 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
2397 | |
2426 | |
2398 | Signal watchers will trigger an event when the process receives a specific |
2427 | Signal watchers will trigger an event when the process receives a specific |
2399 | signal one or more times. Even though signals are very asynchronous, libev |
2428 | signal one or more times. Even though signals are very asynchronous, libev |
… | |
… | |
2409 | only within the same loop, i.e. you can watch for C<SIGINT> in your |
2438 | only within the same loop, i.e. you can watch for C<SIGINT> in your |
2410 | default loop and for C<SIGIO> in another loop, but you cannot watch for |
2439 | default loop and for C<SIGIO> in another loop, but you cannot watch for |
2411 | C<SIGINT> in both the default loop and another loop at the same time. At |
2440 | C<SIGINT> in both the default loop and another loop at the same time. At |
2412 | the moment, C<SIGCHLD> is permanently tied to the default loop. |
2441 | the moment, C<SIGCHLD> is permanently tied to the default loop. |
2413 | |
2442 | |
2414 | When the first watcher gets started will libev actually register something |
2443 | Only after the first watcher for a signal is started will libev actually |
2415 | with the kernel (thus it coexists with your own signal handlers as long as |
2444 | register something with the kernel. It thus coexists with your own signal |
2416 | you don't register any with libev for the same signal). |
2445 | handlers as long as you don't register any with libev for the same signal. |
2417 | |
2446 | |
2418 | If possible and supported, libev will install its handlers with |
2447 | If possible and supported, libev will install its handlers with |
2419 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2448 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2420 | not be unduly interrupted. If you have a problem with system calls getting |
2449 | not be unduly interrupted. If you have a problem with system calls getting |
2421 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2450 | interrupted by signals you can block all signals in an C<ev_check> watcher |
… | |
… | |
2606 | |
2635 | |
2607 | =head2 C<ev_stat> - did the file attributes just change? |
2636 | =head2 C<ev_stat> - did the file attributes just change? |
2608 | |
2637 | |
2609 | This watches a file system path for attribute changes. That is, it calls |
2638 | This watches a file system path for attribute changes. That is, it calls |
2610 | C<stat> on that path in regular intervals (or when the OS says it changed) |
2639 | C<stat> on that path in regular intervals (or when the OS says it changed) |
2611 | and sees if it changed compared to the last time, invoking the callback if |
2640 | and sees if it changed compared to the last time, invoking the callback |
2612 | it did. |
2641 | if it did. Starting the watcher C<stat>'s the file, so only changes that |
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|
2642 | happen after the watcher has been started will be reported. |
2613 | |
2643 | |
2614 | The path does not need to exist: changing from "path exists" to "path does |
2644 | The path does not need to exist: changing from "path exists" to "path does |
2615 | not exist" is a status change like any other. The condition "path does not |
2645 | not exist" is a status change like any other. The condition "path does not |
2616 | exist" (or more correctly "path cannot be stat'ed") is signified by the |
2646 | exist" (or more correctly "path cannot be stat'ed") is signified by the |
2617 | C<st_nlink> field being zero (which is otherwise always forced to be at |
2647 | C<st_nlink> field being zero (which is otherwise always forced to be at |
… | |
… | |
2902 | |
2932 | |
2903 | Prepare and check watchers are often (but not always) used in pairs: |
2933 | Prepare and check watchers are often (but not always) used in pairs: |
2904 | prepare watchers get invoked before the process blocks and check watchers |
2934 | prepare watchers get invoked before the process blocks and check watchers |
2905 | afterwards. |
2935 | afterwards. |
2906 | |
2936 | |
2907 | You I<must not> call C<ev_run> or similar functions that enter |
2937 | You I<must not> call C<ev_run> (or similar functions that enter the |
2908 | the current event loop from either C<ev_prepare> or C<ev_check> |
2938 | current event loop) or C<ev_loop_fork> from either C<ev_prepare> or |
2909 | watchers. Other loops than the current one are fine, however. The |
2939 | C<ev_check> watchers. Other loops than the current one are fine, |
2910 | rationale behind this is that you do not need to check for recursion in |
2940 | however. The rationale behind this is that you do not need to check |
2911 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2941 | for recursion in those watchers, i.e. the sequence will always be |
2912 | C<ev_check> so if you have one watcher of each kind they will always be |
2942 | C<ev_prepare>, blocking, C<ev_check> so if you have one watcher of each |
2913 | called in pairs bracketing the blocking call. |
2943 | kind they will always be called in pairs bracketing the blocking call. |
2914 | |
2944 | |
2915 | Their main purpose is to integrate other event mechanisms into libev and |
2945 | Their main purpose is to integrate other event mechanisms into libev and |
2916 | their use is somewhat advanced. They could be used, for example, to track |
2946 | their use is somewhat advanced. They could be used, for example, to track |
2917 | variable changes, implement your own watchers, integrate net-snmp or a |
2947 | variable changes, implement your own watchers, integrate net-snmp or a |
2918 | coroutine library and lots more. They are also occasionally useful if |
2948 | coroutine library and lots more. They are also occasionally useful if |
… | |
… | |
2962 | |
2992 | |
2963 | Using an C<ev_check> watcher is almost enough: it will be called on the |
2993 | Using an C<ev_check> watcher is almost enough: it will be called on the |
2964 | next event loop iteration. However, that isn't as soon as possible - |
2994 | next event loop iteration. However, that isn't as soon as possible - |
2965 | without external events, your C<ev_check> watcher will not be invoked. |
2995 | without external events, your C<ev_check> watcher will not be invoked. |
2966 | |
2996 | |
2967 | |
|
|
2968 | This is where C<ev_idle> watchers come in handy - all you need is a |
2997 | This is where C<ev_idle> watchers come in handy - all you need is a |
2969 | single global idle watcher that is active as long as you have one active |
2998 | single global idle watcher that is active as long as you have one active |
2970 | C<ev_check> watcher. The C<ev_idle> watcher makes sure the event loop |
2999 | C<ev_check> watcher. The C<ev_idle> watcher makes sure the event loop |
2971 | will not sleep, and the C<ev_check> watcher makes sure a callback gets |
3000 | will not sleep, and the C<ev_check> watcher makes sure a callback gets |
2972 | invoked. Neither watcher alone can do that. |
3001 | invoked. Neither watcher alone can do that. |
… | |
… | |
3178 | |
3207 | |
3179 | =over 4 |
3208 | =over 4 |
3180 | |
3209 | |
3181 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
3210 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
3182 | |
3211 | |
3183 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
3212 | =item ev_embed_set (ev_embed *, struct ev_loop *embedded_loop) |
3184 | |
3213 | |
3185 | Configures the watcher to embed the given loop, which must be |
3214 | Configures the watcher to embed the given loop, which must be |
3186 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
3215 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
3187 | invoked automatically, otherwise it is the responsibility of the callback |
3216 | invoked automatically, otherwise it is the responsibility of the callback |
3188 | to invoke it (it will continue to be called until the sweep has been done, |
3217 | to invoke it (it will continue to be called until the sweep has been done, |
… | |
… | |
3209 | used). |
3238 | used). |
3210 | |
3239 | |
3211 | struct ev_loop *loop_hi = ev_default_init (0); |
3240 | struct ev_loop *loop_hi = ev_default_init (0); |
3212 | struct ev_loop *loop_lo = 0; |
3241 | struct ev_loop *loop_lo = 0; |
3213 | ev_embed embed; |
3242 | ev_embed embed; |
3214 | |
3243 | |
3215 | // see if there is a chance of getting one that works |
3244 | // see if there is a chance of getting one that works |
3216 | // (remember that a flags value of 0 means autodetection) |
3245 | // (remember that a flags value of 0 means autodetection) |
3217 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3246 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3218 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3247 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3219 | : 0; |
3248 | : 0; |
… | |
… | |
3233 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
3262 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
3234 | |
3263 | |
3235 | struct ev_loop *loop = ev_default_init (0); |
3264 | struct ev_loop *loop = ev_default_init (0); |
3236 | struct ev_loop *loop_socket = 0; |
3265 | struct ev_loop *loop_socket = 0; |
3237 | ev_embed embed; |
3266 | ev_embed embed; |
3238 | |
3267 | |
3239 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3268 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3240 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3269 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3241 | { |
3270 | { |
3242 | ev_embed_init (&embed, 0, loop_socket); |
3271 | ev_embed_init (&embed, 0, loop_socket); |
3243 | ev_embed_start (loop, &embed); |
3272 | ev_embed_start (loop, &embed); |
… | |
… | |
3251 | |
3280 | |
3252 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
3281 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
3253 | |
3282 | |
3254 | Fork watchers are called when a C<fork ()> was detected (usually because |
3283 | Fork watchers are called when a C<fork ()> was detected (usually because |
3255 | whoever is a good citizen cared to tell libev about it by calling |
3284 | whoever is a good citizen cared to tell libev about it by calling |
3256 | C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the |
3285 | C<ev_loop_fork>). The invocation is done before the event loop blocks next |
3257 | event loop blocks next and before C<ev_check> watchers are being called, |
3286 | and before C<ev_check> watchers are being called, and only in the child |
3258 | and only in the child after the fork. If whoever good citizen calling |
3287 | after the fork. If whoever good citizen calling C<ev_default_fork> cheats |
3259 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
3288 | and calls it in the wrong process, the fork handlers will be invoked, too, |
3260 | handlers will be invoked, too, of course. |
3289 | of course. |
3261 | |
3290 | |
3262 | =head3 The special problem of life after fork - how is it possible? |
3291 | =head3 The special problem of life after fork - how is it possible? |
3263 | |
3292 | |
3264 | Most uses of C<fork()> consist of forking, then some simple calls to set |
3293 | Most uses of C<fork ()> consist of forking, then some simple calls to set |
3265 | up/change the process environment, followed by a call to C<exec()>. This |
3294 | up/change the process environment, followed by a call to C<exec()>. This |
3266 | sequence should be handled by libev without any problems. |
3295 | sequence should be handled by libev without any problems. |
3267 | |
3296 | |
3268 | This changes when the application actually wants to do event handling |
3297 | This changes when the application actually wants to do event handling |
3269 | in the child, or both parent in child, in effect "continuing" after the |
3298 | in the child, or both parent in child, in effect "continuing" after the |
… | |
… | |
3507 | |
3536 | |
3508 | There are some other functions of possible interest. Described. Here. Now. |
3537 | There are some other functions of possible interest. Described. Here. Now. |
3509 | |
3538 | |
3510 | =over 4 |
3539 | =over 4 |
3511 | |
3540 | |
3512 | =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) |
3513 | |
3542 | |
3514 | 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 |
3515 | callback on whichever event happens first and automatically stops both |
3544 | callback on whichever event happens first and automatically stops both |
3516 | 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 |
3517 | 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 |
… | |
… | |
3659 | already been invoked. |
3688 | already been invoked. |
3660 | |
3689 | |
3661 | A common way around all these issues is to make sure that |
3690 | A common way around all these issues is to make sure that |
3662 | C<start_new_request> I<always> returns before the callback is invoked. If |
3691 | C<start_new_request> I<always> returns before the callback is invoked. If |
3663 | C<start_new_request> immediately knows the result, it can artificially |
3692 | C<start_new_request> immediately knows the result, it can artificially |
3664 | delay invoking the callback by e.g. using a C<prepare> or C<idle> watcher |
3693 | delay invoking the callback by using a C<prepare> or C<idle> watcher for |
3665 | for example, or more sneakily, by reusing an existing (stopped) watcher |
3694 | example, or more sneakily, by reusing an existing (stopped) watcher and |
3666 | and pushing it into the pending queue: |
3695 | pushing it into the pending queue: |
3667 | |
3696 | |
3668 | ev_set_cb (watcher, callback); |
3697 | ev_set_cb (watcher, callback); |
3669 | ev_feed_event (EV_A_ watcher, 0); |
3698 | ev_feed_event (EV_A_ watcher, 0); |
3670 | |
3699 | |
3671 | This way, C<start_new_request> can safely return before the callback is |
3700 | This way, C<start_new_request> can safely return before the callback is |
… | |
… | |
3679 | |
3708 | |
3680 | This brings the problem of exiting - a callback might want to finish the |
3709 | This brings the problem of exiting - a callback might want to finish the |
3681 | main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but |
3710 | main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but |
3682 | a modal "Are you sure?" dialog is still waiting), or just the nested one |
3711 | a modal "Are you sure?" dialog is still waiting), or just the nested one |
3683 | and not the main one (e.g. user clocked "Ok" in a modal dialog), or some |
3712 | and not the main one (e.g. user clocked "Ok" in a modal dialog), or some |
3684 | other combination: In these cases, C<ev_break> will not work alone. |
3713 | other combination: In these cases, a simple C<ev_break> will not work. |
3685 | |
3714 | |
3686 | The solution is to maintain "break this loop" variable for each C<ev_run> |
3715 | The solution is to maintain "break this loop" variable for each C<ev_run> |
3687 | invocation, and use a loop around C<ev_run> until the condition is |
3716 | invocation, and use a loop around C<ev_run> until the condition is |
3688 | triggered, using C<EVRUN_ONCE>: |
3717 | triggered, using C<EVRUN_ONCE>: |
3689 | |
3718 | |
… | |
… | |
3893 | 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 |
3894 | 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: |
3895 | |
3924 | |
3896 | // my_ev.h |
3925 | // my_ev.h |
3897 | #define EV_CB_DECLARE(type) struct my_coro *cb; |
3926 | #define EV_CB_DECLARE(type) struct my_coro *cb; |
3898 | #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb); |
3927 | #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb) |
3899 | #include "../libev/ev.h" |
3928 | #include "../libev/ev.h" |
3900 | |
3929 | |
3901 | // my_ev.c |
3930 | // my_ev.c |
3902 | #define EV_H "my_ev.h" |
3931 | #define EV_H "my_ev.h" |
3903 | #include "../libev/ev.c" |
3932 | #include "../libev/ev.c" |
… | |
… | |
3949 | 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 |
3950 | 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 |
3951 | will work fine. |
3980 | will work fine. |
3952 | |
3981 | |
3953 | Proper exception specifications might have to be added to callbacks passed |
3982 | Proper exception specifications might have to be added to callbacks passed |
3954 | to libev: exceptions may be thrown only from watcher callbacks, all |
3983 | to libev: exceptions may be thrown only from watcher callbacks, all other |
3955 | other callbacks (allocator, syserr, loop acquire/release and periodic |
3984 | callbacks (allocator, syserr, loop acquire/release and periodic reschedule |
3956 | reschedule callbacks) must not throw exceptions, and might need a C<throw |
3985 | callbacks) must not throw exceptions, and might need a C<noexcept> |
3957 | ()> 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 |
3958 | and C++ you can use the C<EV_THROW> macro for this: |
3987 | C++ you can use the C<EV_NOEXCEPT> macro for this: |
3959 | |
3988 | |
3960 | static void |
3989 | static void |
3961 | fatal_error (const char *msg) EV_THROW |
3990 | fatal_error (const char *msg) EV_NOEXCEPT |
3962 | { |
3991 | { |
3963 | perror (msg); |
3992 | perror (msg); |
3964 | abort (); |
3993 | abort (); |
3965 | } |
3994 | } |
3966 | |
3995 | |
… | |
… | |
3980 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
4009 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
3981 | you to use some convenience methods to start/stop watchers and also change |
4010 | you to use some convenience methods to start/stop watchers and also change |
3982 | the callback model to a model using method callbacks on objects. |
4011 | the callback model to a model using method callbacks on objects. |
3983 | |
4012 | |
3984 | To use it, |
4013 | To use it, |
3985 | |
4014 | |
3986 | #include <ev++.h> |
4015 | #include <ev++.h> |
3987 | |
4016 | |
3988 | This automatically includes F<ev.h> and puts all of its definitions (many |
4017 | This automatically includes F<ev.h> and puts all of its definitions (many |
3989 | of them macros) into the global namespace. All C++ specific things are |
4018 | of them macros) into the global namespace. All C++ specific things are |
3990 | put into the C<ev> namespace. It should support all the same embedding |
4019 | put into the C<ev> namespace. It should support all the same embedding |
… | |
… | |
4093 | void operator() (ev::io &w, int revents) |
4122 | void operator() (ev::io &w, int revents) |
4094 | { |
4123 | { |
4095 | ... |
4124 | ... |
4096 | } |
4125 | } |
4097 | } |
4126 | } |
4098 | |
4127 | |
4099 | myfunctor f; |
4128 | myfunctor f; |
4100 | |
4129 | |
4101 | ev::io w; |
4130 | ev::io w; |
4102 | w.set (&f); |
4131 | w.set (&f); |
4103 | |
4132 | |
… | |
… | |
4376 | ev_vars.h |
4405 | ev_vars.h |
4377 | ev_wrap.h |
4406 | ev_wrap.h |
4378 | |
4407 | |
4379 | ev_win32.c required on win32 platforms only |
4408 | ev_win32.c required on win32 platforms only |
4380 | |
4409 | |
4381 | ev_select.c only when select backend is enabled (which is enabled by default) |
4410 | ev_select.c only when select backend is enabled |
4382 | ev_poll.c only when poll backend is enabled (disabled by default) |
4411 | ev_poll.c only when poll backend is enabled |
4383 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
4412 | ev_epoll.c only when the epoll backend is enabled |
4384 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
4413 | ev_kqueue.c only when the kqueue backend is enabled |
4385 | 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 |
4386 | |
4415 | |
4387 | 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 |
4388 | to compile this single file. |
4417 | to compile this single file. |
4389 | |
4418 | |
4390 | =head3 LIBEVENT COMPATIBILITY API |
4419 | =head3 LIBEVENT COMPATIBILITY API |
… | |
… | |
4618 | different cpus (or different cpu cores). This reduces dependencies |
4647 | different cpus (or different cpu cores). This reduces dependencies |
4619 | and makes libev faster. |
4648 | and makes libev faster. |
4620 | |
4649 | |
4621 | =item EV_NO_THREADS |
4650 | =item EV_NO_THREADS |
4622 | |
4651 | |
4623 | If defined to be C<1>, libev will assume that it will never be called |
4652 | If defined to be C<1>, libev will assume that it will never be called from |
4624 | from different threads, which is a stronger assumption than C<EV_NO_SMP>, |
4653 | different threads (that includes signal handlers), which is a stronger |
4625 | above. This reduces dependencies and makes libev faster. |
4654 | assumption than C<EV_NO_SMP>, above. This reduces dependencies and makes |
|
|
4655 | libev faster. |
4626 | |
4656 | |
4627 | =item EV_ATOMIC_T |
4657 | =item EV_ATOMIC_T |
4628 | |
4658 | |
4629 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
4659 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
4630 | access is atomic and serialised with respect to other threads or signal |
4660 | access is atomic with respect to other threads or signal contexts. No |
4631 | contexts. No such type is easily found in the C language, so you can |
4661 | such type is easily found in the C language, so you can provide your own |
4632 | provide your own type that you know is safe for your purposes. It is used |
4662 | type that you know is safe for your purposes. It is used both for signal |
4633 | both for signal handler "locking" as well as for signal and thread safety |
4663 | handler "locking" as well as for signal and thread safety in C<ev_async> |
4634 | in C<ev_async> watchers. |
4664 | watchers. |
4635 | |
4665 | |
4636 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
4666 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
4637 | (from F<signal.h>), which is usually good enough on most platforms, |
4667 | (from F<signal.h>), which is usually good enough on most platforms. |
4638 | although strictly speaking using a type that also implies a memory fence |
|
|
4639 | is required. |
|
|
4640 | |
4668 | |
4641 | =item EV_H (h) |
4669 | =item EV_H (h) |
4642 | |
4670 | |
4643 | The name of the F<ev.h> header file used to include it. The default if |
4671 | The name of the F<ev.h> header file used to include it. The default if |
4644 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
4672 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
… | |
… | |
5291 | 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 |
5292 | 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 |
5293 | callback: The watcher callbacks have different type signatures, but libev |
5321 | callback: The watcher callbacks have different type signatures, but libev |
5294 | calls them using an C<ev_watcher *> internally. |
5322 | calls them using an C<ev_watcher *> internally. |
5295 | |
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 | |
5296 | =item pointer accesses must be thread-atomic |
5329 | =item pointer accesses must be thread-atomic |
5297 | |
5330 | |
5298 | 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 |
5299 | 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. |
5300 | |
5333 | |
… | |
… | |
5313 | thread" or will block signals process-wide, both behaviours would |
5346 | thread" or will block signals process-wide, both behaviours would |
5314 | be compatible with libev. Interaction between C<sigprocmask> and |
5347 | be compatible with libev. Interaction between C<sigprocmask> and |
5315 | C<pthread_sigmask> could complicate things, however. |
5348 | C<pthread_sigmask> could complicate things, however. |
5316 | |
5349 | |
5317 | The most portable way to handle signals is to block signals in all threads |
5350 | The most portable way to handle signals is to block signals in all threads |
5318 | except the initial one, and run the default loop in the initial thread as |
5351 | except the initial one, and run the signal handling loop in the initial |
5319 | well. |
5352 | thread as well. |
5320 | |
5353 | |
5321 | =item C<long> must be large enough for common memory allocation sizes |
5354 | =item C<long> must be large enough for common memory allocation sizes |
5322 | |
5355 | |
5323 | To improve portability and simplify its API, libev uses C<long> internally |
5356 | To improve portability and simplify its API, libev uses C<long> internally |
5324 | instead of C<size_t> when allocating its data structures. On non-POSIX |
5357 | instead of C<size_t> when allocating its data structures. On non-POSIX |
… | |
… | |
5428 | =over 4 |
5461 | =over 4 |
5429 | |
5462 | |
5430 | =item C<EV_COMPAT3> backwards compatibility mechanism |
5463 | =item C<EV_COMPAT3> backwards compatibility mechanism |
5431 | |
5464 | |
5432 | The backward compatibility mechanism can be controlled by |
5465 | The backward compatibility mechanism can be controlled by |
5433 | C<EV_COMPAT3>. See L</PREPROCESSOR SYMBOLS/MACROS> in the L</EMBEDDING> |
5466 | C<EV_COMPAT3>. See L</"PREPROCESSOR SYMBOLS/MACROS"> in the L</EMBEDDING> |
5434 | section. |
5467 | section. |
5435 | |
5468 | |
5436 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
5469 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
5437 | |
5470 | |
5438 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
5471 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |