… | |
… | |
124 | this argument. |
124 | this argument. |
125 | |
125 | |
126 | =head2 TIME REPRESENTATION |
126 | =head2 TIME REPRESENTATION |
127 | |
127 | |
128 | Libev represents time as a single floating point number, representing |
128 | Libev represents time as a single floating point number, representing |
129 | the (fractional) number of seconds since the (POSIX) epoch (somewhere |
129 | the (fractional) number of seconds since the (POSIX) epoch (in practise |
130 | near the beginning of 1970, details are complicated, don't ask). This |
130 | somewhere near the beginning of 1970, details are complicated, don't |
131 | type is called C<ev_tstamp>, which is what you should use too. It usually |
131 | ask). This type is called C<ev_tstamp>, which is what you should use |
132 | aliases to the C<double> type in C. When you need to do any calculations |
132 | too. It usually aliases to the C<double> type in C. When you need to do |
133 | on it, you should treat it as some floating point value. Unlike the name |
133 | any calculations on it, you should treat it as some floating point value. |
|
|
134 | |
134 | component C<stamp> might indicate, it is also used for time differences |
135 | Unlike the name component C<stamp> might indicate, it is also used for |
135 | throughout libev. |
136 | time differences (e.g. delays) throughout libev. |
136 | |
137 | |
137 | =head1 ERROR HANDLING |
138 | =head1 ERROR HANDLING |
138 | |
139 | |
139 | Libev knows three classes of errors: operating system errors, usage errors |
140 | Libev knows three classes of errors: operating system errors, usage errors |
140 | and internal errors (bugs). |
141 | and internal errors (bugs). |
… | |
… | |
191 | as this indicates an incompatible change. Minor versions are usually |
192 | as this indicates an incompatible change. Minor versions are usually |
192 | compatible to older versions, so a larger minor version alone is usually |
193 | compatible to older versions, so a larger minor version alone is usually |
193 | not a problem. |
194 | not a problem. |
194 | |
195 | |
195 | Example: Make sure we haven't accidentally been linked against the wrong |
196 | Example: Make sure we haven't accidentally been linked against the wrong |
196 | version. |
197 | version (note, however, that this will not detect ABI mismatches :). |
197 | |
198 | |
198 | assert (("libev version mismatch", |
199 | assert (("libev version mismatch", |
199 | ev_version_major () == EV_VERSION_MAJOR |
200 | ev_version_major () == EV_VERSION_MAJOR |
200 | && ev_version_minor () >= EV_VERSION_MINOR)); |
201 | && ev_version_minor () >= EV_VERSION_MINOR)); |
201 | |
202 | |
… | |
… | |
345 | useful to try out specific backends to test their performance, or to work |
346 | useful to try out specific backends to test their performance, or to work |
346 | around bugs. |
347 | around bugs. |
347 | |
348 | |
348 | =item C<EVFLAG_FORKCHECK> |
349 | =item C<EVFLAG_FORKCHECK> |
349 | |
350 | |
350 | Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after |
351 | Instead of calling C<ev_loop_fork> manually after a fork, you can also |
351 | a fork, you can also make libev check for a fork in each iteration by |
352 | make libev check for a fork in each iteration by enabling this flag. |
352 | enabling this flag. |
|
|
353 | |
353 | |
354 | This works by calling C<getpid ()> on every iteration of the loop, |
354 | This works by calling C<getpid ()> on every iteration of the loop, |
355 | and thus this might slow down your event loop if you do a lot of loop |
355 | and thus this might slow down your event loop if you do a lot of loop |
356 | iterations and little real work, but is usually not noticeable (on my |
356 | iterations and little real work, but is usually not noticeable (on my |
357 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
357 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
… | |
… | |
567 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
567 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
568 | |
568 | |
569 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
569 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
570 | |
570 | |
571 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
571 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
572 | always distinct from the default loop. Unlike the default loop, it cannot |
572 | always distinct from the default loop. |
573 | handle signal and child watchers, and attempts to do so will be greeted by |
|
|
574 | undefined behaviour (or a failed assertion if assertions are enabled). |
|
|
575 | |
573 | |
576 | Note that this function I<is> thread-safe, and the recommended way to use |
574 | Note that this function I<is> thread-safe, and one common way to use |
577 | libev with threads is indeed to create one loop per thread, and using the |
575 | libev with threads is indeed to create one loop per thread, and using the |
578 | default loop in the "main" or "initial" thread. |
576 | default loop in the "main" or "initial" thread. |
579 | |
577 | |
580 | Example: Try to create a event loop that uses epoll and nothing else. |
578 | Example: Try to create a event loop that uses epoll and nothing else. |
581 | |
579 | |
… | |
… | |
583 | if (!epoller) |
581 | if (!epoller) |
584 | fatal ("no epoll found here, maybe it hides under your chair"); |
582 | fatal ("no epoll found here, maybe it hides under your chair"); |
585 | |
583 | |
586 | =item ev_default_destroy () |
584 | =item ev_default_destroy () |
587 | |
585 | |
588 | Destroys the default loop again (frees all memory and kernel state |
586 | Destroys the default loop (frees all memory and kernel state etc.). None |
589 | etc.). None of the active event watchers will be stopped in the normal |
587 | of the active event watchers will be stopped in the normal sense, so |
590 | sense, so e.g. C<ev_is_active> might still return true. It is your |
588 | e.g. C<ev_is_active> might still return true. It is your responsibility to |
591 | responsibility to either stop all watchers cleanly yourself I<before> |
589 | either stop all watchers cleanly yourself I<before> calling this function, |
592 | calling this function, or cope with the fact afterwards (which is usually |
590 | or cope with the fact afterwards (which is usually the easiest thing, you |
593 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
591 | can just ignore the watchers and/or C<free ()> them for example). |
594 | for example). |
|
|
595 | |
592 | |
596 | Note that certain global state, such as signal state (and installed signal |
593 | Note that certain global state, such as signal state (and installed signal |
597 | handlers), will not be freed by this function, and related watchers (such |
594 | handlers), will not be freed by this function, and related watchers (such |
598 | as signal and child watchers) would need to be stopped manually. |
595 | as signal and child watchers) would need to be stopped manually. |
599 | |
596 | |
… | |
… | |
614 | name, you can call it anytime, but it makes most sense after forking, in |
611 | name, you can call it anytime, but it makes most sense after forking, in |
615 | the child process (or both child and parent, but that again makes little |
612 | the child process (or both child and parent, but that again makes little |
616 | sense). You I<must> call it in the child before using any of the libev |
613 | sense). You I<must> call it in the child before using any of the libev |
617 | functions, and it will only take effect at the next C<ev_loop> iteration. |
614 | functions, and it will only take effect at the next C<ev_loop> iteration. |
618 | |
615 | |
|
|
616 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
|
|
617 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
|
|
618 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
|
|
619 | during fork. |
|
|
620 | |
619 | On the other hand, you only need to call this function in the child |
621 | On the other hand, you only need to call this function in the child |
620 | process if and only if you want to use the event library in the child. If |
622 | process if and only if you want to use the event loop in the child. If you |
621 | you just fork+exec, you don't have to call it at all. |
623 | just fork+exec or create a new loop in the child, you don't have to call |
|
|
624 | it at all. |
622 | |
625 | |
623 | The function itself is quite fast and it's usually not a problem to call |
626 | The function itself is quite fast and it's usually not a problem to call |
624 | it just in case after a fork. To make this easy, the function will fit in |
627 | it just in case after a fork. To make this easy, the function will fit in |
625 | quite nicely into a call to C<pthread_atfork>: |
628 | quite nicely into a call to C<pthread_atfork>: |
626 | |
629 | |
… | |
… | |
628 | |
631 | |
629 | =item ev_loop_fork (loop) |
632 | =item ev_loop_fork (loop) |
630 | |
633 | |
631 | Like C<ev_default_fork>, but acts on an event loop created by |
634 | Like C<ev_default_fork>, but acts on an event loop created by |
632 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
635 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
633 | after fork that you want to re-use in the child, and how you do this is |
636 | after fork that you want to re-use in the child, and how you keep track of |
634 | entirely your own problem. |
637 | them is entirely your own problem. |
635 | |
638 | |
636 | =item int ev_is_default_loop (loop) |
639 | =item int ev_is_default_loop (loop) |
637 | |
640 | |
638 | Returns true when the given loop is, in fact, the default loop, and false |
641 | Returns true when the given loop is, in fact, the default loop, and false |
639 | otherwise. |
642 | otherwise. |
640 | |
643 | |
641 | =item unsigned int ev_loop_count (loop) |
644 | =item unsigned int ev_iteration (loop) |
642 | |
645 | |
643 | Returns the count of loop iterations for the loop, which is identical to |
646 | Returns the current iteration count for the loop, which is identical to |
644 | the number of times libev did poll for new events. It starts at C<0> and |
647 | the number of times libev did poll for new events. It starts at C<0> and |
645 | happily wraps around with enough iterations. |
648 | happily wraps around with enough iterations. |
646 | |
649 | |
647 | This value can sometimes be useful as a generation counter of sorts (it |
650 | This value can sometimes be useful as a generation counter of sorts (it |
648 | "ticks" the number of loop iterations), as it roughly corresponds with |
651 | "ticks" the number of loop iterations), as it roughly corresponds with |
649 | C<ev_prepare> and C<ev_check> calls. |
652 | C<ev_prepare> and C<ev_check> calls - and is incremented between the |
|
|
653 | prepare and check phases. |
650 | |
654 | |
651 | =item unsigned int ev_loop_depth (loop) |
655 | =item unsigned int ev_depth (loop) |
652 | |
656 | |
653 | Returns the number of times C<ev_loop> was entered minus the number of |
657 | Returns the number of times C<ev_loop> was entered minus the number of |
654 | times C<ev_loop> was exited, in other words, the recursion depth. |
658 | times C<ev_loop> was exited, in other words, the recursion depth. |
655 | |
659 | |
656 | Outside C<ev_loop>, this number is zero. In a callback, this number is |
660 | Outside C<ev_loop>, this number is zero. In a callback, this number is |
657 | C<1>, unless C<ev_loop> was invoked recursively (or from another thread), |
661 | C<1>, unless C<ev_loop> was invoked recursively (or from another thread), |
658 | in which case it is higher. |
662 | in which case it is higher. |
659 | |
663 | |
660 | Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread |
664 | Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread |
661 | etc.), doesn't count as exit. |
665 | etc.), doesn't count as "exit" - consider this as a hint to avoid such |
|
|
666 | ungentleman behaviour unless it's really convenient. |
662 | |
667 | |
663 | =item unsigned int ev_backend (loop) |
668 | =item unsigned int ev_backend (loop) |
664 | |
669 | |
665 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
670 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
666 | use. |
671 | use. |
… | |
… | |
1032 | =item C<EV_WRITE> |
1037 | =item C<EV_WRITE> |
1033 | |
1038 | |
1034 | The file descriptor in the C<ev_io> watcher has become readable and/or |
1039 | The file descriptor in the C<ev_io> watcher has become readable and/or |
1035 | writable. |
1040 | writable. |
1036 | |
1041 | |
1037 | =item C<EV_TIMEOUT> |
1042 | =item C<EV_TIMER> |
1038 | |
1043 | |
1039 | The C<ev_timer> watcher has timed out. |
1044 | The C<ev_timer> watcher has timed out. |
1040 | |
1045 | |
1041 | =item C<EV_PERIODIC> |
1046 | =item C<EV_PERIODIC> |
1042 | |
1047 | |
… | |
… | |
1538 | |
1543 | |
1539 | So when you encounter spurious, unexplained daemon exits, make sure you |
1544 | So when you encounter spurious, unexplained daemon exits, make sure you |
1540 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
1545 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
1541 | somewhere, as that would have given you a big clue). |
1546 | somewhere, as that would have given you a big clue). |
1542 | |
1547 | |
|
|
1548 | =head3 The special problem of accept()ing when you can't |
|
|
1549 | |
|
|
1550 | Many implementations of the POSIX C<accept> function (for example, |
|
|
1551 | found in post-2004 Linux) have the peculiar behaviour of not removing a |
|
|
1552 | connection from the pending queue in all error cases. |
|
|
1553 | |
|
|
1554 | For example, larger servers often run out of file descriptors (because |
|
|
1555 | of resource limits), causing C<accept> to fail with C<ENFILE> but not |
|
|
1556 | rejecting the connection, leading to libev signalling readiness on |
|
|
1557 | the next iteration again (the connection still exists after all), and |
|
|
1558 | typically causing the program to loop at 100% CPU usage. |
|
|
1559 | |
|
|
1560 | Unfortunately, the set of errors that cause this issue differs between |
|
|
1561 | operating systems, there is usually little the app can do to remedy the |
|
|
1562 | situation, and no known thread-safe method of removing the connection to |
|
|
1563 | cope with overload is known (to me). |
|
|
1564 | |
|
|
1565 | One of the easiest ways to handle this situation is to just ignore it |
|
|
1566 | - when the program encounters an overload, it will just loop until the |
|
|
1567 | situation is over. While this is a form of busy waiting, no OS offers an |
|
|
1568 | event-based way to handle this situation, so it's the best one can do. |
|
|
1569 | |
|
|
1570 | A better way to handle the situation is to log any errors other than |
|
|
1571 | C<EAGAIN> and C<EWOULDBLOCK>, making sure not to flood the log with such |
|
|
1572 | messages, and continue as usual, which at least gives the user an idea of |
|
|
1573 | what could be wrong ("raise the ulimit!"). For extra points one could stop |
|
|
1574 | the C<ev_io> watcher on the listening fd "for a while", which reduces CPU |
|
|
1575 | usage. |
|
|
1576 | |
|
|
1577 | If your program is single-threaded, then you could also keep a dummy file |
|
|
1578 | descriptor for overload situations (e.g. by opening F</dev/null>), and |
|
|
1579 | when you run into C<ENFILE> or C<EMFILE>, close it, run C<accept>, |
|
|
1580 | close that fd, and create a new dummy fd. This will gracefully refuse |
|
|
1581 | clients under typical overload conditions. |
|
|
1582 | |
|
|
1583 | The last way to handle it is to simply log the error and C<exit>, as |
|
|
1584 | is often done with C<malloc> failures, but this results in an easy |
|
|
1585 | opportunity for a DoS attack. |
1543 | |
1586 | |
1544 | =head3 Watcher-Specific Functions |
1587 | =head3 Watcher-Specific Functions |
1545 | |
1588 | |
1546 | =over 4 |
1589 | =over 4 |
1547 | |
1590 | |
… | |
… | |
1726 | to the current time (meaning we just have some activity :), then call the |
1769 | to the current time (meaning we just have some activity :), then call the |
1727 | callback, which will "do the right thing" and start the timer: |
1770 | callback, which will "do the right thing" and start the timer: |
1728 | |
1771 | |
1729 | ev_init (timer, callback); |
1772 | ev_init (timer, callback); |
1730 | last_activity = ev_now (loop); |
1773 | last_activity = ev_now (loop); |
1731 | callback (loop, timer, EV_TIMEOUT); |
1774 | callback (loop, timer, EV_TIMER); |
1732 | |
1775 | |
1733 | And when there is some activity, simply store the current time in |
1776 | And when there is some activity, simply store the current time in |
1734 | C<last_activity>, no libev calls at all: |
1777 | C<last_activity>, no libev calls at all: |
1735 | |
1778 | |
1736 | last_actiivty = ev_now (loop); |
1779 | last_actiivty = ev_now (loop); |
… | |
… | |
1867 | Returns the remaining time until a timer fires. If the timer is active, |
1910 | Returns the remaining time until a timer fires. If the timer is active, |
1868 | then this time is relative to the current event loop time, otherwise it's |
1911 | then this time is relative to the current event loop time, otherwise it's |
1869 | the timeout value currently configured. |
1912 | the timeout value currently configured. |
1870 | |
1913 | |
1871 | That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns |
1914 | That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns |
1872 | C<5>. When the timer is started and one second passes, C<ev_timer_remain> |
1915 | C<5>. When the timer is started and one second passes, C<ev_timer_remaining> |
1873 | will return C<4>. When the timer expires and is restarted, it will return |
1916 | will return C<4>. When the timer expires and is restarted, it will return |
1874 | roughly C<7> (likely slightly less as callback invocation takes some time, |
1917 | roughly C<7> (likely slightly less as callback invocation takes some time, |
1875 | too), and so on. |
1918 | too), and so on. |
1876 | |
1919 | |
1877 | =item ev_tstamp repeat [read-write] |
1920 | =item ev_tstamp repeat [read-write] |
… | |
… | |
3141 | |
3184 | |
3142 | If C<timeout> is less than 0, then no timeout watcher will be |
3185 | If C<timeout> is less than 0, then no timeout watcher will be |
3143 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
3186 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
3144 | repeat = 0) will be started. C<0> is a valid timeout. |
3187 | repeat = 0) will be started. C<0> is a valid timeout. |
3145 | |
3188 | |
3146 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
3189 | The callback has the type C<void (*cb)(int revents, void *arg)> and is |
3147 | passed an C<revents> set like normal event callbacks (a combination of |
3190 | passed an C<revents> set like normal event callbacks (a combination of |
3148 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
3191 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMER>) and the C<arg> |
3149 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
3192 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
3150 | a timeout and an io event at the same time - you probably should give io |
3193 | a timeout and an io event at the same time - you probably should give io |
3151 | events precedence. |
3194 | events precedence. |
3152 | |
3195 | |
3153 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
3196 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
3154 | |
3197 | |
3155 | static void stdin_ready (int revents, void *arg) |
3198 | static void stdin_ready (int revents, void *arg) |
3156 | { |
3199 | { |
3157 | if (revents & EV_READ) |
3200 | if (revents & EV_READ) |
3158 | /* stdin might have data for us, joy! */; |
3201 | /* stdin might have data for us, joy! */; |
3159 | else if (revents & EV_TIMEOUT) |
3202 | else if (revents & EV_TIMER) |
3160 | /* doh, nothing entered */; |
3203 | /* doh, nothing entered */; |
3161 | } |
3204 | } |
3162 | |
3205 | |
3163 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3206 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3164 | |
3207 | |
… | |
… | |
3451 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3494 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3452 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3495 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3453 | |
3496 | |
3454 | =item Lua |
3497 | =item Lua |
3455 | |
3498 | |
3456 | Brian Maher has written a partial interface to libev |
3499 | Brian Maher has written a partial interface to libev for lua (at the |
3457 | for lua (only C<ev_io> and C<ev_timer>), to be found at |
3500 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
3458 | L<http://github.com/brimworks/lua-ev>. |
3501 | L<http://github.com/brimworks/lua-ev>. |
3459 | |
3502 | |
3460 | =back |
3503 | =back |
3461 | |
3504 | |
3462 | |
3505 | |
… | |
… | |
3617 | libev.m4 |
3660 | libev.m4 |
3618 | |
3661 | |
3619 | =head2 PREPROCESSOR SYMBOLS/MACROS |
3662 | =head2 PREPROCESSOR SYMBOLS/MACROS |
3620 | |
3663 | |
3621 | Libev can be configured via a variety of preprocessor symbols you have to |
3664 | Libev can be configured via a variety of preprocessor symbols you have to |
3622 | define before including any of its files. The default in the absence of |
3665 | define before including (or compiling) any of its files. The default in |
3623 | autoconf is documented for every option. |
3666 | the absence of autoconf is documented for every option. |
|
|
3667 | |
|
|
3668 | Symbols marked with "(h)" do not change the ABI, and can have different |
|
|
3669 | values when compiling libev vs. including F<ev.h>, so it is permissible |
|
|
3670 | to redefine them before including F<ev.h> without breaking compatibility |
|
|
3671 | to a compiled library. All other symbols change the ABI, which means all |
|
|
3672 | users of libev and the libev code itself must be compiled with compatible |
|
|
3673 | settings. |
3624 | |
3674 | |
3625 | =over 4 |
3675 | =over 4 |
3626 | |
3676 | |
3627 | =item EV_STANDALONE |
3677 | =item EV_STANDALONE (h) |
3628 | |
3678 | |
3629 | Must always be C<1> if you do not use autoconf configuration, which |
3679 | Must always be C<1> if you do not use autoconf configuration, which |
3630 | keeps libev from including F<config.h>, and it also defines dummy |
3680 | keeps libev from including F<config.h>, and it also defines dummy |
3631 | implementations for some libevent functions (such as logging, which is not |
3681 | implementations for some libevent functions (such as logging, which is not |
3632 | supported). It will also not define any of the structs usually found in |
3682 | supported). It will also not define any of the structs usually found in |
… | |
… | |
3782 | as well as for signal and thread safety in C<ev_async> watchers. |
3832 | as well as for signal and thread safety in C<ev_async> watchers. |
3783 | |
3833 | |
3784 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
3834 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
3785 | (from F<signal.h>), which is usually good enough on most platforms. |
3835 | (from F<signal.h>), which is usually good enough on most platforms. |
3786 | |
3836 | |
3787 | =item EV_H |
3837 | =item EV_H (h) |
3788 | |
3838 | |
3789 | The name of the F<ev.h> header file used to include it. The default if |
3839 | The name of the F<ev.h> header file used to include it. The default if |
3790 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
3840 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
3791 | used to virtually rename the F<ev.h> header file in case of conflicts. |
3841 | used to virtually rename the F<ev.h> header file in case of conflicts. |
3792 | |
3842 | |
3793 | =item EV_CONFIG_H |
3843 | =item EV_CONFIG_H (h) |
3794 | |
3844 | |
3795 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
3845 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
3796 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
3846 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
3797 | C<EV_H>, above. |
3847 | C<EV_H>, above. |
3798 | |
3848 | |
3799 | =item EV_EVENT_H |
3849 | =item EV_EVENT_H (h) |
3800 | |
3850 | |
3801 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
3851 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
3802 | of how the F<event.h> header can be found, the default is C<"event.h">. |
3852 | of how the F<event.h> header can be found, the default is C<"event.h">. |
3803 | |
3853 | |
3804 | =item EV_PROTOTYPES |
3854 | =item EV_PROTOTYPES (h) |
3805 | |
3855 | |
3806 | If defined to be C<0>, then F<ev.h> will not define any function |
3856 | If defined to be C<0>, then F<ev.h> will not define any function |
3807 | prototypes, but still define all the structs and other symbols. This is |
3857 | prototypes, but still define all the structs and other symbols. This is |
3808 | occasionally useful if you want to provide your own wrapper functions |
3858 | occasionally useful if you want to provide your own wrapper functions |
3809 | around libev functions. |
3859 | around libev functions. |
… | |
… | |
3831 | fine. |
3881 | fine. |
3832 | |
3882 | |
3833 | If your embedding application does not need any priorities, defining these |
3883 | If your embedding application does not need any priorities, defining these |
3834 | both to C<0> will save some memory and CPU. |
3884 | both to C<0> will save some memory and CPU. |
3835 | |
3885 | |
3836 | =item EV_PERIODIC_ENABLE |
3886 | =item EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE, |
|
|
3887 | EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, |
|
|
3888 | EV_ASYNC_ENABLE, EV_CHILD_ENABLE. |
3837 | |
3889 | |
3838 | If undefined or defined to be C<1>, then periodic timers are supported. If |
3890 | If undefined or defined to be C<1> (and the platform supports it), then |
3839 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
3891 | the respective watcher type is supported. If defined to be C<0>, then it |
3840 | code. |
3892 | is not. Disabling watcher types mainly saves codesize. |
3841 | |
3893 | |
3842 | =item EV_IDLE_ENABLE |
3894 | =item EV_FEATURES |
3843 | |
|
|
3844 | If undefined or defined to be C<1>, then idle watchers are supported. If |
|
|
3845 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
3846 | code. |
|
|
3847 | |
|
|
3848 | =item EV_EMBED_ENABLE |
|
|
3849 | |
|
|
3850 | If undefined or defined to be C<1>, then embed watchers are supported. If |
|
|
3851 | defined to be C<0>, then they are not. Embed watchers rely on most other |
|
|
3852 | watcher types, which therefore must not be disabled. |
|
|
3853 | |
|
|
3854 | =item EV_STAT_ENABLE |
|
|
3855 | |
|
|
3856 | If undefined or defined to be C<1>, then stat watchers are supported. If |
|
|
3857 | defined to be C<0>, then they are not. |
|
|
3858 | |
|
|
3859 | =item EV_FORK_ENABLE |
|
|
3860 | |
|
|
3861 | If undefined or defined to be C<1>, then fork watchers are supported. If |
|
|
3862 | defined to be C<0>, then they are not. |
|
|
3863 | |
|
|
3864 | =item EV_ASYNC_ENABLE |
|
|
3865 | |
|
|
3866 | If undefined or defined to be C<1>, then async watchers are supported. If |
|
|
3867 | defined to be C<0>, then they are not. |
|
|
3868 | |
|
|
3869 | =item EV_MINIMAL |
|
|
3870 | |
3895 | |
3871 | If you need to shave off some kilobytes of code at the expense of some |
3896 | If you need to shave off some kilobytes of code at the expense of some |
3872 | speed (but with the full API), define this symbol to C<1>. Currently this |
3897 | speed (but with the full API), you can define this symbol to request |
3873 | is used to override some inlining decisions, saves roughly 30% code size |
3898 | certain subsets of functionality. The default is to enable all features |
3874 | on amd64. It also selects a much smaller 2-heap for timer management over |
3899 | that can be enabled on the platform. |
3875 | the default 4-heap. |
|
|
3876 | |
3900 | |
3877 | You can save even more by disabling watcher types you do not need |
3901 | A typical way to use this symbol is to define it to C<0> (or to a bitset |
3878 | and setting C<EV_MAXPRI> == C<EV_MINPRI>. Also, disabling C<assert> |
3902 | with some broad features you want) and then selectively re-enable |
3879 | (C<-DNDEBUG>) will usually reduce code size a lot. |
3903 | additional parts you want, for example if you want everything minimal, |
|
|
3904 | but multiple event loop support, async and child watchers and the poll |
|
|
3905 | backend, use this: |
3880 | |
3906 | |
3881 | Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to |
3907 | #define EV_FEATURES 0 |
3882 | provide a bare-bones event library. See C<ev.h> for details on what parts |
3908 | #define EV_MULTIPLICITY 1 |
3883 | of the API are still available, and do not complain if this subset changes |
3909 | #define EV_USE_POLL 1 |
3884 | over time. |
3910 | #define EV_CHILD_ENABLE 1 |
|
|
3911 | #define EV_ASYNC_ENABLE 1 |
|
|
3912 | |
|
|
3913 | The actual value is a bitset, it can be a combination of the following |
|
|
3914 | values: |
|
|
3915 | |
|
|
3916 | =over 4 |
|
|
3917 | |
|
|
3918 | =item C<1> - faster/larger code |
|
|
3919 | |
|
|
3920 | Use larger code to speed up some operations. |
|
|
3921 | |
|
|
3922 | Currently this is used to override some inlining decisions (enlarging the roughly |
|
|
3923 | 30% code size on amd64. |
|
|
3924 | |
|
|
3925 | When optimising for size, use of compiler flags such as C<-Os> with |
|
|
3926 | gcc recommended, as well as C<-DNDEBUG>, as libev contains a number of |
|
|
3927 | assertions. |
|
|
3928 | |
|
|
3929 | =item C<2> - faster/larger data structures |
|
|
3930 | |
|
|
3931 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
|
|
3932 | hash table sizes and so on. This will usually further increase codesize |
|
|
3933 | and can additionally have an effect on the size of data structures at |
|
|
3934 | runtime. |
|
|
3935 | |
|
|
3936 | =item C<4> - full API configuration |
|
|
3937 | |
|
|
3938 | This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and |
|
|
3939 | enables multiplicity (C<EV_MULTIPLICITY>=1). |
|
|
3940 | |
|
|
3941 | =item C<8> - full API |
|
|
3942 | |
|
|
3943 | This enables a lot of the "lesser used" API functions. See C<ev.h> for |
|
|
3944 | details on which parts of the API are still available without this |
|
|
3945 | feature, and do not complain if this subset changes over time. |
|
|
3946 | |
|
|
3947 | =item C<16> - enable all optional watcher types |
|
|
3948 | |
|
|
3949 | Enables all optional watcher types. If you want to selectively enable |
|
|
3950 | only some watcher types other than I/O and timers (e.g. prepare, |
|
|
3951 | embed, async, child...) you can enable them manually by defining |
|
|
3952 | C<EV_watchertype_ENABLE> to C<1> instead. |
|
|
3953 | |
|
|
3954 | =item C<32> - enable all backends |
|
|
3955 | |
|
|
3956 | This enables all backends - without this feature, you need to enable at |
|
|
3957 | least one backend manually (C<EV_USE_SELECT> is a good choice). |
|
|
3958 | |
|
|
3959 | =item C<64> - enable OS-specific "helper" APIs |
|
|
3960 | |
|
|
3961 | Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by |
|
|
3962 | default. |
|
|
3963 | |
|
|
3964 | =back |
|
|
3965 | |
|
|
3966 | Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0> |
|
|
3967 | reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb |
|
|
3968 | code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O |
|
|
3969 | watchers, timers and monotonic clock support. |
|
|
3970 | |
|
|
3971 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
|
|
3972 | when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by |
|
|
3973 | your program might be left out as well - a binary starting a timer and an |
|
|
3974 | I/O watcher then might come out at only 5Kb. |
|
|
3975 | |
|
|
3976 | =item EV_AVOID_STDIO |
|
|
3977 | |
|
|
3978 | If this is set to C<1> at compiletime, then libev will avoid using stdio |
|
|
3979 | functions (printf, scanf, perror etc.). This will increase the codesize |
|
|
3980 | somewhat, but if your program doesn't otherwise depend on stdio and your |
|
|
3981 | libc allows it, this avoids linking in the stdio library which is quite |
|
|
3982 | big. |
|
|
3983 | |
|
|
3984 | Note that error messages might become less precise when this option is |
|
|
3985 | enabled. |
3885 | |
3986 | |
3886 | =item EV_NSIG |
3987 | =item EV_NSIG |
3887 | |
3988 | |
3888 | The highest supported signal number, +1 (or, the number of |
3989 | The highest supported signal number, +1 (or, the number of |
3889 | signals): Normally, libev tries to deduce the maximum number of signals |
3990 | signals): Normally, libev tries to deduce the maximum number of signals |
… | |
… | |
3893 | statically allocates some 12-24 bytes per signal number. |
3994 | statically allocates some 12-24 bytes per signal number. |
3894 | |
3995 | |
3895 | =item EV_PID_HASHSIZE |
3996 | =item EV_PID_HASHSIZE |
3896 | |
3997 | |
3897 | C<ev_child> watchers use a small hash table to distribute workload by |
3998 | C<ev_child> watchers use a small hash table to distribute workload by |
3898 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
3999 | pid. The default size is C<16> (or C<1> with C<EV_FEATURES> disabled), |
3899 | than enough. If you need to manage thousands of children you might want to |
4000 | usually more than enough. If you need to manage thousands of children you |
3900 | increase this value (I<must> be a power of two). |
4001 | might want to increase this value (I<must> be a power of two). |
3901 | |
4002 | |
3902 | =item EV_INOTIFY_HASHSIZE |
4003 | =item EV_INOTIFY_HASHSIZE |
3903 | |
4004 | |
3904 | C<ev_stat> watchers use a small hash table to distribute workload by |
4005 | C<ev_stat> watchers use a small hash table to distribute workload by |
3905 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
4006 | inotify watch id. The default size is C<16> (or C<1> with C<EV_FEATURES> |
3906 | usually more than enough. If you need to manage thousands of C<ev_stat> |
4007 | disabled), usually more than enough. If you need to manage thousands of |
3907 | watchers you might want to increase this value (I<must> be a power of |
4008 | C<ev_stat> watchers you might want to increase this value (I<must> be a |
3908 | two). |
4009 | power of two). |
3909 | |
4010 | |
3910 | =item EV_USE_4HEAP |
4011 | =item EV_USE_4HEAP |
3911 | |
4012 | |
3912 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4013 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3913 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
4014 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
3914 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
4015 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
3915 | faster performance with many (thousands) of watchers. |
4016 | faster performance with many (thousands) of watchers. |
3916 | |
4017 | |
3917 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
4018 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3918 | (disabled). |
4019 | will be C<0>. |
3919 | |
4020 | |
3920 | =item EV_HEAP_CACHE_AT |
4021 | =item EV_HEAP_CACHE_AT |
3921 | |
4022 | |
3922 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4023 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3923 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
4024 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
3924 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
4025 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
3925 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
4026 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
3926 | but avoids random read accesses on heap changes. This improves performance |
4027 | but avoids random read accesses on heap changes. This improves performance |
3927 | noticeably with many (hundreds) of watchers. |
4028 | noticeably with many (hundreds) of watchers. |
3928 | |
4029 | |
3929 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
4030 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3930 | (disabled). |
4031 | will be C<0>. |
3931 | |
4032 | |
3932 | =item EV_VERIFY |
4033 | =item EV_VERIFY |
3933 | |
4034 | |
3934 | Controls how much internal verification (see C<ev_loop_verify ()>) will |
4035 | Controls how much internal verification (see C<ev_loop_verify ()>) will |
3935 | be done: If set to C<0>, no internal verification code will be compiled |
4036 | be done: If set to C<0>, no internal verification code will be compiled |
… | |
… | |
3937 | called. If set to C<2>, then the internal verification code will be |
4038 | called. If set to C<2>, then the internal verification code will be |
3938 | called once per loop, which can slow down libev. If set to C<3>, then the |
4039 | called once per loop, which can slow down libev. If set to C<3>, then the |
3939 | verification code will be called very frequently, which will slow down |
4040 | verification code will be called very frequently, which will slow down |
3940 | libev considerably. |
4041 | libev considerably. |
3941 | |
4042 | |
3942 | The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be |
4043 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3943 | C<0>. |
4044 | will be C<0>. |
3944 | |
4045 | |
3945 | =item EV_COMMON |
4046 | =item EV_COMMON |
3946 | |
4047 | |
3947 | By default, all watchers have a C<void *data> member. By redefining |
4048 | By default, all watchers have a C<void *data> member. By redefining |
3948 | this macro to a something else you can include more and other types of |
4049 | this macro to a something else you can include more and other types of |
… | |
… | |
4006 | file. |
4107 | file. |
4007 | |
4108 | |
4008 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
4109 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
4009 | that everybody includes and which overrides some configure choices: |
4110 | that everybody includes and which overrides some configure choices: |
4010 | |
4111 | |
4011 | #define EV_MINIMAL 1 |
4112 | #define EV_FEATURES 8 |
4012 | #define EV_USE_POLL 0 |
4113 | #define EV_USE_SELECT 1 |
4013 | #define EV_MULTIPLICITY 0 |
|
|
4014 | #define EV_PERIODIC_ENABLE 0 |
4114 | #define EV_PREPARE_ENABLE 1 |
|
|
4115 | #define EV_IDLE_ENABLE 1 |
4015 | #define EV_STAT_ENABLE 0 |
4116 | #define EV_SIGNAL_ENABLE 1 |
4016 | #define EV_FORK_ENABLE 0 |
4117 | #define EV_CHILD_ENABLE 1 |
|
|
4118 | #define EV_USE_STDEXCEPT 0 |
4017 | #define EV_CONFIG_H <config.h> |
4119 | #define EV_CONFIG_H <config.h> |
4018 | #define EV_MINPRI 0 |
|
|
4019 | #define EV_MAXPRI 0 |
|
|
4020 | |
4120 | |
4021 | #include "ev++.h" |
4121 | #include "ev++.h" |
4022 | |
4122 | |
4023 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
4123 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
4024 | |
4124 | |
… | |
… | |
4526 | involves iterating over all running async watchers or all signal numbers. |
4626 | involves iterating over all running async watchers or all signal numbers. |
4527 | |
4627 | |
4528 | =back |
4628 | =back |
4529 | |
4629 | |
4530 | |
4630 | |
|
|
4631 | =head1 PORTING FROM LIBEV 3.X TO 4.X |
|
|
4632 | |
|
|
4633 | The major version 4 introduced some minor incompatible changes to the API. |
|
|
4634 | |
|
|
4635 | At the moment, the C<ev.h> header file tries to implement superficial |
|
|
4636 | compatibility, so most programs should still compile. Those might be |
|
|
4637 | removed in later versions of libev, so better update early than late. |
|
|
4638 | |
|
|
4639 | =over 4 |
|
|
4640 | |
|
|
4641 | =item C<ev_loop_count> renamed to C<ev_iteration> |
|
|
4642 | |
|
|
4643 | =item C<ev_loop_depth> renamed to C<ev_depth> |
|
|
4644 | |
|
|
4645 | =item C<ev_loop_verify> renamed to C<ev_verify> |
|
|
4646 | |
|
|
4647 | Most functions working on C<struct ev_loop> objects don't have an |
|
|
4648 | C<ev_loop_> prefix, so it was removed. Note that C<ev_loop_fork> is |
|
|
4649 | still called C<ev_loop_fork> because it would otherwise clash with the |
|
|
4650 | C<ev_fork> typedef. |
|
|
4651 | |
|
|
4652 | =item C<EV_TIMEOUT> renamed to C<EV_TIMER> in C<revents> |
|
|
4653 | |
|
|
4654 | This is a simple rename - all other watcher types use their name |
|
|
4655 | as revents flag, and now C<ev_timer> does, too. |
|
|
4656 | |
|
|
4657 | Both C<EV_TIMER> and C<EV_TIMEOUT> symbols were present in 3.x versions |
|
|
4658 | and continue to be present for the forseeable future, so this is mostly a |
|
|
4659 | documentation change. |
|
|
4660 | |
|
|
4661 | =item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> |
|
|
4662 | |
|
|
4663 | The preprocessor symbol C<EV_MINIMAL> has been replaced by a different |
|
|
4664 | mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile |
|
|
4665 | and work, but the library code will of course be larger. |
|
|
4666 | |
|
|
4667 | =back |
|
|
4668 | |
|
|
4669 | |
4531 | =head1 GLOSSARY |
4670 | =head1 GLOSSARY |
4532 | |
4671 | |
4533 | =over 4 |
4672 | =over 4 |
4534 | |
4673 | |
4535 | =item active |
4674 | =item active |
… | |
… | |
4556 | A change of state of some external event, such as data now being available |
4695 | A change of state of some external event, such as data now being available |
4557 | for reading on a file descriptor, time having passed or simply not having |
4696 | for reading on a file descriptor, time having passed or simply not having |
4558 | any other events happening anymore. |
4697 | any other events happening anymore. |
4559 | |
4698 | |
4560 | In libev, events are represented as single bits (such as C<EV_READ> or |
4699 | In libev, events are represented as single bits (such as C<EV_READ> or |
4561 | C<EV_TIMEOUT>). |
4700 | C<EV_TIMER>). |
4562 | |
4701 | |
4563 | =item event library |
4702 | =item event library |
4564 | |
4703 | |
4565 | A software package implementing an event model and loop. |
4704 | A software package implementing an event model and loop. |
4566 | |
4705 | |