… | |
… | |
75 | While this document tries to be as complete as possible in documenting |
75 | While this document tries to be as complete as possible in documenting |
76 | libev, its usage and the rationale behind its design, it is not a tutorial |
76 | libev, its usage and the rationale behind its design, it is not a tutorial |
77 | on event-based programming, nor will it introduce event-based programming |
77 | on event-based programming, nor will it introduce event-based programming |
78 | with libev. |
78 | with libev. |
79 | |
79 | |
80 | Familarity with event based programming techniques in general is assumed |
80 | Familiarity with event based programming techniques in general is assumed |
81 | throughout this document. |
81 | throughout this document. |
82 | |
82 | |
83 | =head1 ABOUT LIBEV |
83 | =head1 ABOUT LIBEV |
84 | |
84 | |
85 | Libev is an event loop: you register interest in certain events (such as a |
85 | Libev is an event loop: you register interest in certain events (such as a |
… | |
… | |
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. |
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|
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 |
… | |
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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. |
… | |
… | |
700 | C<ev_resume> directly afterwards to resume timer processing. |
705 | C<ev_resume> directly afterwards to resume timer processing. |
701 | |
706 | |
702 | Effectively, all C<ev_timer> watchers will be delayed by the time spend |
707 | Effectively, all C<ev_timer> watchers will be delayed by the time spend |
703 | between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers |
708 | between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers |
704 | will be rescheduled (that is, they will lose any events that would have |
709 | will be rescheduled (that is, they will lose any events that would have |
705 | occured while suspended). |
710 | occurred while suspended). |
706 | |
711 | |
707 | After calling C<ev_suspend> you B<must not> call I<any> function on the |
712 | After calling C<ev_suspend> you B<must not> call I<any> function on the |
708 | given loop other than C<ev_resume>, and you B<must not> call C<ev_resume> |
713 | given loop other than C<ev_resume>, and you B<must not> call C<ev_resume> |
709 | without a previous call to C<ev_suspend>. |
714 | without a previous call to C<ev_suspend>. |
710 | |
715 | |
… | |
… | |
787 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
792 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
788 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
793 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
789 | |
794 | |
790 | This "unloop state" will be cleared when entering C<ev_loop> again. |
795 | This "unloop state" will be cleared when entering C<ev_loop> again. |
791 | |
796 | |
792 | It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls. |
797 | It is safe to call C<ev_unloop> from outside any C<ev_loop> calls. |
793 | |
798 | |
794 | =item ev_ref (loop) |
799 | =item ev_ref (loop) |
795 | |
800 | |
796 | =item ev_unref (loop) |
801 | =item ev_unref (loop) |
797 | |
802 | |
… | |
… | |
867 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
872 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
868 | as this approaches the timing granularity of most systems. Note that if |
873 | as this approaches the timing granularity of most systems. Note that if |
869 | you do transactions with the outside world and you can't increase the |
874 | you do transactions with the outside world and you can't increase the |
870 | parallelity, then this setting will limit your transaction rate (if you |
875 | parallelity, then this setting will limit your transaction rate (if you |
871 | need to poll once per transaction and the I/O collect interval is 0.01, |
876 | need to poll once per transaction and the I/O collect interval is 0.01, |
872 | then you can't do more than 100 transations per second). |
877 | then you can't do more than 100 transactions per second). |
873 | |
878 | |
874 | Setting the I<timeout collect interval> can improve the opportunity for |
879 | Setting the I<timeout collect interval> can improve the opportunity for |
875 | saving power, as the program will "bundle" timer callback invocations that |
880 | saving power, as the program will "bundle" timer callback invocations that |
876 | are "near" in time together, by delaying some, thus reducing the number of |
881 | are "near" in time together, by delaying some, thus reducing the number of |
877 | times the process sleeps and wakes up again. Another useful technique to |
882 | times the process sleeps and wakes up again. Another useful technique to |
… | |
… | |
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 | |
… | |
… | |
1375 | |
1380 | |
1376 | For example, to emulate how many other event libraries handle priorities, |
1381 | For example, to emulate how many other event libraries handle priorities, |
1377 | you can associate an C<ev_idle> watcher to each such watcher, and in |
1382 | you can associate an C<ev_idle> watcher to each such watcher, and in |
1378 | the normal watcher callback, you just start the idle watcher. The real |
1383 | the normal watcher callback, you just start the idle watcher. The real |
1379 | processing is done in the idle watcher callback. This causes libev to |
1384 | processing is done in the idle watcher callback. This causes libev to |
1380 | continously poll and process kernel event data for the watcher, but when |
1385 | continuously poll and process kernel event data for the watcher, but when |
1381 | the lock-out case is known to be rare (which in turn is rare :), this is |
1386 | the lock-out case is known to be rare (which in turn is rare :), this is |
1382 | workable. |
1387 | workable. |
1383 | |
1388 | |
1384 | Usually, however, the lock-out model implemented that way will perform |
1389 | Usually, however, the lock-out model implemented that way will perform |
1385 | miserably under the type of load it was designed to handle. In that case, |
1390 | miserably under the type of load it was designed to handle. In that case, |
… | |
… | |
1399 | { |
1404 | { |
1400 | // stop the I/O watcher, we received the event, but |
1405 | // stop the I/O watcher, we received the event, but |
1401 | // are not yet ready to handle it. |
1406 | // are not yet ready to handle it. |
1402 | ev_io_stop (EV_A_ w); |
1407 | ev_io_stop (EV_A_ w); |
1403 | |
1408 | |
1404 | // start the idle watcher to ahndle the actual event. |
1409 | // start the idle watcher to handle the actual event. |
1405 | // it will not be executed as long as other watchers |
1410 | // it will not be executed as long as other watchers |
1406 | // with the default priority are receiving events. |
1411 | // with the default priority are receiving events. |
1407 | ev_idle_start (EV_A_ &idle); |
1412 | ev_idle_start (EV_A_ &idle); |
1408 | } |
1413 | } |
1409 | |
1414 | |
… | |
… | |
1463 | |
1468 | |
1464 | If you cannot use non-blocking mode, then force the use of a |
1469 | If you cannot use non-blocking mode, then force the use of a |
1465 | known-to-be-good backend (at the time of this writing, this includes only |
1470 | known-to-be-good backend (at the time of this writing, this includes only |
1466 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file |
1471 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file |
1467 | descriptors for which non-blocking operation makes no sense (such as |
1472 | descriptors for which non-blocking operation makes no sense (such as |
1468 | files) - libev doesn't guarentee any specific behaviour in that case. |
1473 | files) - libev doesn't guarantee any specific behaviour in that case. |
1469 | |
1474 | |
1470 | Another thing you have to watch out for is that it is quite easy to |
1475 | Another thing you have to watch out for is that it is quite easy to |
1471 | receive "spurious" readiness notifications, that is your callback might |
1476 | receive "spurious" readiness notifications, that is your callback might |
1472 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1477 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1473 | because there is no data. Not only are some backends known to create a |
1478 | because there is no data. Not only are some backends known to create a |
… | |
… | |
1541 | somewhere, as that would have given you a big clue). |
1546 | somewhere, as that would have given you a big clue). |
1542 | |
1547 | |
1543 | =head3 The special problem of accept()ing when you can't |
1548 | =head3 The special problem of accept()ing when you can't |
1544 | |
1549 | |
1545 | Many implementations of the POSIX C<accept> function (for example, |
1550 | Many implementations of the POSIX C<accept> function (for example, |
1546 | found in port-2004 Linux) have the peculiar behaviour of not removing a |
1551 | found in post-2004 Linux) have the peculiar behaviour of not removing a |
1547 | connection from the pending queue in all error cases. |
1552 | connection from the pending queue in all error cases. |
1548 | |
1553 | |
1549 | For example, larger servers often run out of file descriptors (because |
1554 | For example, larger servers often run out of file descriptors (because |
1550 | of resource limits), causing C<accept> to fail with C<ENFILE> but not |
1555 | of resource limits), causing C<accept> to fail with C<ENFILE> but not |
1551 | rejecting the connection, leading to libev signalling readiness on |
1556 | rejecting the connection, leading to libev signalling readiness on |
… | |
… | |
1732 | ev_tstamp timeout = last_activity + 60.; |
1737 | ev_tstamp timeout = last_activity + 60.; |
1733 | |
1738 | |
1734 | // if last_activity + 60. is older than now, we did time out |
1739 | // if last_activity + 60. is older than now, we did time out |
1735 | if (timeout < now) |
1740 | if (timeout < now) |
1736 | { |
1741 | { |
1737 | // timeout occured, take action |
1742 | // timeout occurred, take action |
1738 | } |
1743 | } |
1739 | else |
1744 | else |
1740 | { |
1745 | { |
1741 | // callback was invoked, but there was some activity, re-arm |
1746 | // callback was invoked, but there was some activity, re-arm |
1742 | // the watcher to fire in last_activity + 60, which is |
1747 | // the watcher to fire in last_activity + 60, which is |
… | |
… | |
1764 | 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 |
1765 | callback, which will "do the right thing" and start the timer: |
1770 | callback, which will "do the right thing" and start the timer: |
1766 | |
1771 | |
1767 | ev_init (timer, callback); |
1772 | ev_init (timer, callback); |
1768 | last_activity = ev_now (loop); |
1773 | last_activity = ev_now (loop); |
1769 | callback (loop, timer, EV_TIMEOUT); |
1774 | callback (loop, timer, EV_TIMER); |
1770 | |
1775 | |
1771 | 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 |
1772 | C<last_activity>, no libev calls at all: |
1777 | C<last_activity>, no libev calls at all: |
1773 | |
1778 | |
1774 | last_actiivty = ev_now (loop); |
1779 | last_activity = ev_now (loop); |
1775 | |
1780 | |
1776 | This technique is slightly more complex, but in most cases where the |
1781 | This technique is slightly more complex, but in most cases where the |
1777 | time-out is unlikely to be triggered, much more efficient. |
1782 | time-out is unlikely to be triggered, much more efficient. |
1778 | |
1783 | |
1779 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
1784 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
… | |
… | |
3179 | |
3184 | |
3180 | 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 |
3181 | 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 |
3182 | repeat = 0) will be started. C<0> is a valid timeout. |
3187 | repeat = 0) will be started. C<0> is a valid timeout. |
3183 | |
3188 | |
3184 | 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 |
3185 | 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 |
3186 | 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> |
3187 | 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> |
3188 | 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 |
3189 | events precedence. |
3194 | events precedence. |
3190 | |
3195 | |
3191 | 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. |
3192 | |
3197 | |
3193 | static void stdin_ready (int revents, void *arg) |
3198 | static void stdin_ready (int revents, void *arg) |
3194 | { |
3199 | { |
3195 | if (revents & EV_READ) |
3200 | if (revents & EV_READ) |
3196 | /* stdin might have data for us, joy! */; |
3201 | /* stdin might have data for us, joy! */; |
3197 | else if (revents & EV_TIMEOUT) |
3202 | else if (revents & EV_TIMER) |
3198 | /* doh, nothing entered */; |
3203 | /* doh, nothing entered */; |
3199 | } |
3204 | } |
3200 | |
3205 | |
3201 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3206 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3202 | |
3207 | |
… | |
… | |
3336 | myclass obj; |
3341 | myclass obj; |
3337 | ev::io iow; |
3342 | ev::io iow; |
3338 | iow.set <myclass, &myclass::io_cb> (&obj); |
3343 | iow.set <myclass, &myclass::io_cb> (&obj); |
3339 | |
3344 | |
3340 | =item w->set (object *) |
3345 | =item w->set (object *) |
3341 | |
|
|
3342 | This is an B<experimental> feature that might go away in a future version. |
|
|
3343 | |
3346 | |
3344 | This is a variation of a method callback - leaving out the method to call |
3347 | This is a variation of a method callback - leaving out the method to call |
3345 | will default the method to C<operator ()>, which makes it possible to use |
3348 | will default the method to C<operator ()>, which makes it possible to use |
3346 | functor objects without having to manually specify the C<operator ()> all |
3349 | functor objects without having to manually specify the C<operator ()> all |
3347 | the time. Incidentally, you can then also leave out the template argument |
3350 | the time. Incidentally, you can then also leave out the template argument |
… | |
… | |
3660 | define before including (or compiling) any of its files. The default in |
3663 | define before including (or compiling) any of its files. The default in |
3661 | the absence of autoconf is documented for every option. |
3664 | the absence of autoconf is documented for every option. |
3662 | |
3665 | |
3663 | Symbols marked with "(h)" do not change the ABI, and can have different |
3666 | Symbols marked with "(h)" do not change the ABI, and can have different |
3664 | values when compiling libev vs. including F<ev.h>, so it is permissible |
3667 | values when compiling libev vs. including F<ev.h>, so it is permissible |
3665 | to redefine them before including F<ev.h> without breakign compatibility |
3668 | to redefine them before including F<ev.h> without breaking compatibility |
3666 | to a compiled library. All other symbols change the ABI, which means all |
3669 | to a compiled library. All other symbols change the ABI, which means all |
3667 | users of libev and the libev code itself must be compiled with compatible |
3670 | users of libev and the libev code itself must be compiled with compatible |
3668 | settings. |
3671 | settings. |
3669 | |
3672 | |
3670 | =over 4 |
3673 | =over 4 |
… | |
… | |
3957 | default. |
3960 | default. |
3958 | |
3961 | |
3959 | =back |
3962 | =back |
3960 | |
3963 | |
3961 | Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0> |
3964 | Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0> |
3962 | reduces the compiled size of libev from 24.7Kb to 6.5Kb on my GNU/Linux |
3965 | reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb |
3963 | amd64 system, while still giving you I/O watchers, timers and monotonic |
3966 | code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O |
3964 | clock support. |
3967 | watchers, timers and monotonic clock support. |
3965 | |
3968 | |
3966 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
3969 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
3967 | when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by |
3970 | when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by |
3968 | your program might be left out as well - a binary starting a timer and an |
3971 | your program might be left out as well - a binary starting a timer and an |
3969 | I/O watcher then might come out at only 5Kb. |
3972 | I/O watcher then might come out at only 5Kb. |
… | |
… | |
3983 | |
3986 | |
3984 | The highest supported signal number, +1 (or, the number of |
3987 | The highest supported signal number, +1 (or, the number of |
3985 | signals): Normally, libev tries to deduce the maximum number of signals |
3988 | signals): Normally, libev tries to deduce the maximum number of signals |
3986 | automatically, but sometimes this fails, in which case it can be |
3989 | automatically, but sometimes this fails, in which case it can be |
3987 | specified. Also, using a lower number than detected (C<32> should be |
3990 | specified. Also, using a lower number than detected (C<32> should be |
3988 | good for about any system in existance) can save some memory, as libev |
3991 | good for about any system in existence) can save some memory, as libev |
3989 | statically allocates some 12-24 bytes per signal number. |
3992 | statically allocates some 12-24 bytes per signal number. |
3990 | |
3993 | |
3991 | =item EV_PID_HASHSIZE |
3994 | =item EV_PID_HASHSIZE |
3992 | |
3995 | |
3993 | C<ev_child> watchers use a small hash table to distribute workload by |
3996 | C<ev_child> watchers use a small hash table to distribute workload by |
… | |
… | |
4621 | involves iterating over all running async watchers or all signal numbers. |
4624 | involves iterating over all running async watchers or all signal numbers. |
4622 | |
4625 | |
4623 | =back |
4626 | =back |
4624 | |
4627 | |
4625 | |
4628 | |
|
|
4629 | =head1 PORTING FROM LIBEV 3.X TO 4.X |
|
|
4630 | |
|
|
4631 | The major version 4 introduced some minor incompatible changes to the API. |
|
|
4632 | |
|
|
4633 | At the moment, the C<ev.h> header file tries to implement superficial |
|
|
4634 | compatibility, so most programs should still compile. Those might be |
|
|
4635 | removed in later versions of libev, so better update early than late. |
|
|
4636 | |
|
|
4637 | =over 4 |
|
|
4638 | |
|
|
4639 | =item C<ev_loop_count> renamed to C<ev_iteration> |
|
|
4640 | |
|
|
4641 | =item C<ev_loop_depth> renamed to C<ev_depth> |
|
|
4642 | |
|
|
4643 | =item C<ev_loop_verify> renamed to C<ev_verify> |
|
|
4644 | |
|
|
4645 | Most functions working on C<struct ev_loop> objects don't have an |
|
|
4646 | C<ev_loop_> prefix, so it was removed. Note that C<ev_loop_fork> is |
|
|
4647 | still called C<ev_loop_fork> because it would otherwise clash with the |
|
|
4648 | C<ev_fork> typedef. |
|
|
4649 | |
|
|
4650 | =item C<EV_TIMEOUT> renamed to C<EV_TIMER> in C<revents> |
|
|
4651 | |
|
|
4652 | This is a simple rename - all other watcher types use their name |
|
|
4653 | as revents flag, and now C<ev_timer> does, too. |
|
|
4654 | |
|
|
4655 | Both C<EV_TIMER> and C<EV_TIMEOUT> symbols were present in 3.x versions |
|
|
4656 | and continue to be present for the foreseeable future, so this is mostly a |
|
|
4657 | documentation change. |
|
|
4658 | |
|
|
4659 | =item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> |
|
|
4660 | |
|
|
4661 | The preprocessor symbol C<EV_MINIMAL> has been replaced by a different |
|
|
4662 | mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile |
|
|
4663 | and work, but the library code will of course be larger. |
|
|
4664 | |
|
|
4665 | =back |
|
|
4666 | |
|
|
4667 | |
4626 | =head1 GLOSSARY |
4668 | =head1 GLOSSARY |
4627 | |
4669 | |
4628 | =over 4 |
4670 | =over 4 |
4629 | |
4671 | |
4630 | =item active |
4672 | =item active |
… | |
… | |
4651 | A change of state of some external event, such as data now being available |
4693 | A change of state of some external event, such as data now being available |
4652 | for reading on a file descriptor, time having passed or simply not having |
4694 | for reading on a file descriptor, time having passed or simply not having |
4653 | any other events happening anymore. |
4695 | any other events happening anymore. |
4654 | |
4696 | |
4655 | In libev, events are represented as single bits (such as C<EV_READ> or |
4697 | In libev, events are represented as single bits (such as C<EV_READ> or |
4656 | C<EV_TIMEOUT>). |
4698 | C<EV_TIMER>). |
4657 | |
4699 | |
4658 | =item event library |
4700 | =item event library |
4659 | |
4701 | |
4660 | A software package implementing an event model and loop. |
4702 | A software package implementing an event model and loop. |
4661 | |
4703 | |