… | |
… | |
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. |
|
|
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 |
… | |
… | |
2118 | Example: Call a callback every hour, or, more precisely, whenever the |
2123 | Example: Call a callback every hour, or, more precisely, whenever the |
2119 | system time is divisible by 3600. The callback invocation times have |
2124 | system time is divisible by 3600. The callback invocation times have |
2120 | potentially a lot of jitter, but good long-term stability. |
2125 | potentially a lot of jitter, but good long-term stability. |
2121 | |
2126 | |
2122 | static void |
2127 | static void |
2123 | clock_cb (struct ev_loop *loop, ev_io *w, int revents) |
2128 | clock_cb (struct ev_loop *loop, ev_periodic *w, int revents) |
2124 | { |
2129 | { |
2125 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2130 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2126 | } |
2131 | } |
2127 | |
2132 | |
2128 | ev_periodic hourly_tick; |
2133 | ev_periodic hourly_tick; |
… | |
… | |
2960 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
2965 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
2961 | handlers will be invoked, too, of course. |
2966 | handlers will be invoked, too, of course. |
2962 | |
2967 | |
2963 | =head3 The special problem of life after fork - how is it possible? |
2968 | =head3 The special problem of life after fork - how is it possible? |
2964 | |
2969 | |
2965 | Most uses of C<fork()> consist of forking, then some simple calls to ste |
2970 | Most uses of C<fork()> consist of forking, then some simple calls to set |
2966 | up/change the process environment, followed by a call to C<exec()>. This |
2971 | up/change the process environment, followed by a call to C<exec()>. This |
2967 | sequence should be handled by libev without any problems. |
2972 | sequence should be handled by libev without any problems. |
2968 | |
2973 | |
2969 | This changes when the application actually wants to do event handling |
2974 | This changes when the application actually wants to do event handling |
2970 | in the child, or both parent in child, in effect "continuing" after the |
2975 | in the child, or both parent in child, in effect "continuing" after the |
… | |
… | |
3004 | believe me. |
3009 | believe me. |
3005 | |
3010 | |
3006 | =back |
3011 | =back |
3007 | |
3012 | |
3008 | |
3013 | |
3009 | =head2 C<ev_async> - how to wake up another event loop |
3014 | =head2 C<ev_async> - how to wake up an event loop |
3010 | |
3015 | |
3011 | In general, you cannot use an C<ev_loop> from multiple threads or other |
3016 | In general, you cannot use an C<ev_loop> from multiple threads or other |
3012 | asynchronous sources such as signal handlers (as opposed to multiple event |
3017 | asynchronous sources such as signal handlers (as opposed to multiple event |
3013 | loops - those are of course safe to use in different threads). |
3018 | loops - those are of course safe to use in different threads). |
3014 | |
3019 | |
3015 | Sometimes, however, you need to wake up another event loop you do not |
3020 | Sometimes, however, you need to wake up an event loop you do not control, |
3016 | control, for example because it belongs to another thread. This is what |
3021 | for example because it belongs to another thread. This is what C<ev_async> |
3017 | C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you |
3022 | watchers do: as long as the C<ev_async> watcher is active, you can signal |
3018 | can signal it by calling C<ev_async_send>, which is thread- and signal |
3023 | it by calling C<ev_async_send>, which is thread- and signal safe. |
3019 | safe. |
|
|
3020 | |
3024 | |
3021 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3025 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3022 | too, are asynchronous in nature, and signals, too, will be compressed |
3026 | too, are asynchronous in nature, and signals, too, will be compressed |
3023 | (i.e. the number of callback invocations may be less than the number of |
3027 | (i.e. the number of callback invocations may be less than the number of |
3024 | C<ev_async_sent> calls). |
3028 | C<ev_async_sent> calls). |
… | |
… | |
3179 | |
3183 | |
3180 | If C<timeout> is less than 0, then no timeout watcher will be |
3184 | 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 |
3185 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
3182 | repeat = 0) will be started. C<0> is a valid timeout. |
3186 | repeat = 0) will be started. C<0> is a valid timeout. |
3183 | |
3187 | |
3184 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
3188 | 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 |
3189 | 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> |
3190 | 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> |
3191 | 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 |
3192 | a timeout and an io event at the same time - you probably should give io |
3189 | events precedence. |
3193 | events precedence. |
3190 | |
3194 | |
3191 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
3195 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
3192 | |
3196 | |
3193 | static void stdin_ready (int revents, void *arg) |
3197 | static void stdin_ready (int revents, void *arg) |
3194 | { |
3198 | { |
3195 | if (revents & EV_READ) |
3199 | if (revents & EV_READ) |
3196 | /* stdin might have data for us, joy! */; |
3200 | /* stdin might have data for us, joy! */; |
3197 | else if (revents & EV_TIMEOUT) |
3201 | else if (revents & EV_TIMER) |
3198 | /* doh, nothing entered */; |
3202 | /* doh, nothing entered */; |
3199 | } |
3203 | } |
3200 | |
3204 | |
3201 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3205 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3202 | |
3206 | |
… | |
… | |
3336 | myclass obj; |
3340 | myclass obj; |
3337 | ev::io iow; |
3341 | ev::io iow; |
3338 | iow.set <myclass, &myclass::io_cb> (&obj); |
3342 | iow.set <myclass, &myclass::io_cb> (&obj); |
3339 | |
3343 | |
3340 | =item w->set (object *) |
3344 | =item w->set (object *) |
3341 | |
|
|
3342 | This is an B<experimental> feature that might go away in a future version. |
|
|
3343 | |
3345 | |
3344 | This is a variation of a method callback - leaving out the method to call |
3346 | 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 |
3347 | 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 |
3348 | functor objects without having to manually specify the C<operator ()> all |
3347 | the time. Incidentally, you can then also leave out the template argument |
3349 | 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 |
3662 | define before including (or compiling) any of its files. The default in |
3661 | the absence of autoconf is documented for every option. |
3663 | the absence of autoconf is documented for every option. |
3662 | |
3664 | |
3663 | Symbols marked with "(h)" do not change the ABI, and can have different |
3665 | 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 |
3666 | 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 |
3667 | 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 |
3668 | 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 |
3669 | users of libev and the libev code itself must be compiled with compatible |
3668 | settings. |
3670 | settings. |
3669 | |
3671 | |
3670 | =over 4 |
3672 | =over 4 |
… | |
… | |
3882 | EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, |
3884 | EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, |
3883 | EV_ASYNC_ENABLE, EV_CHILD_ENABLE. |
3885 | EV_ASYNC_ENABLE, EV_CHILD_ENABLE. |
3884 | |
3886 | |
3885 | If undefined or defined to be C<1> (and the platform supports it), then |
3887 | If undefined or defined to be C<1> (and the platform supports it), then |
3886 | the respective watcher type is supported. If defined to be C<0>, then it |
3888 | the respective watcher type is supported. If defined to be C<0>, then it |
3887 | is not. Disabling watcher types mainly saves codesize. |
3889 | is not. Disabling watcher types mainly saves code size. |
3888 | |
3890 | |
3889 | =item EV_FEATURES |
3891 | =item EV_FEATURES |
3890 | |
3892 | |
3891 | If you need to shave off some kilobytes of code at the expense of some |
3893 | If you need to shave off some kilobytes of code at the expense of some |
3892 | speed (but with the full API), you can define this symbol to request |
3894 | speed (but with the full API), you can define this symbol to request |
3893 | certain subsets of functionality. The default is to enable all features |
3895 | certain subsets of functionality. The default is to enable all features |
3894 | that can be enabled on the platform. |
3896 | that can be enabled on the platform. |
3895 | |
|
|
3896 | Note that using autoconf will usually override most of the features, so |
|
|
3897 | using this symbol makes sense mostly when embedding libev. |
|
|
3898 | |
3897 | |
3899 | A typical way to use this symbol is to define it to C<0> (or to a bitset |
3898 | A typical way to use this symbol is to define it to C<0> (or to a bitset |
3900 | with some broad features you want) and then selectively re-enable |
3899 | with some broad features you want) and then selectively re-enable |
3901 | additional parts you want, for example if you want everything minimal, |
3900 | additional parts you want, for example if you want everything minimal, |
3902 | but multiple event loop support, async and child watchers and the poll |
3901 | but multiple event loop support, async and child watchers and the poll |
… | |
… | |
3915 | |
3914 | |
3916 | =item C<1> - faster/larger code |
3915 | =item C<1> - faster/larger code |
3917 | |
3916 | |
3918 | Use larger code to speed up some operations. |
3917 | Use larger code to speed up some operations. |
3919 | |
3918 | |
3920 | Currently this is used to override some inlining decisions (enlarging the roughly |
3919 | Currently this is used to override some inlining decisions (enlarging the |
3921 | 30% code size on amd64. |
3920 | code size by roughly 30% on amd64). |
3922 | |
3921 | |
3923 | When optimising for size, use of compiler flags such as C<-Os> with |
3922 | When optimising for size, use of compiler flags such as C<-Os> with |
3924 | gcc recommended, as well as C<-DNDEBUG>, as libev contains a number of |
3923 | gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of |
3925 | assertions. |
3924 | assertions. |
3926 | |
3925 | |
3927 | =item C<2> - faster/larger data structures |
3926 | =item C<2> - faster/larger data structures |
3928 | |
3927 | |
3929 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
3928 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
3930 | hash table sizes and so on. This will usually further increase codesize |
3929 | hash table sizes and so on. This will usually further increase code size |
3931 | and can additionally have an effect on the size of data structures at |
3930 | and can additionally have an effect on the size of data structures at |
3932 | runtime. |
3931 | runtime. |
3933 | |
3932 | |
3934 | =item C<4> - full API configuration |
3933 | =item C<4> - full API configuration |
3935 | |
3934 | |
3936 | This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and |
3935 | This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and |
3937 | enables multiplicity (C<EV_MULTIPLICITY>=1). |
3936 | enables multiplicity (C<EV_MULTIPLICITY>=1). |
3938 | |
3937 | |
|
|
3938 | =item C<8> - full API |
|
|
3939 | |
3939 | It also enables a lot of the "lesser used" core API functions. See C<ev.h> |
3940 | This enables a lot of the "lesser used" API functions. See C<ev.h> for |
3940 | for details on which parts of the API are still available without this |
3941 | details on which parts of the API are still available without this |
3941 | feature, and do not complain if this subset changes over time. |
3942 | feature, and do not complain if this subset changes over time. |
3942 | |
3943 | |
3943 | =item C<8> - enable all optional watcher types |
3944 | =item C<16> - enable all optional watcher types |
3944 | |
3945 | |
3945 | Enables all optional watcher types. If you want to selectively enable |
3946 | Enables all optional watcher types. If you want to selectively enable |
3946 | only some watcher types other than I/O and timers (e.g. prepare, |
3947 | only some watcher types other than I/O and timers (e.g. prepare, |
3947 | embed, async, child...) you can enable them manually by defining |
3948 | embed, async, child...) you can enable them manually by defining |
3948 | C<EV_watchertype_ENABLE> to C<1> instead. |
3949 | C<EV_watchertype_ENABLE> to C<1> instead. |
3949 | |
3950 | |
3950 | =item C<16> - enable all backends |
3951 | =item C<32> - enable all backends |
3951 | |
3952 | |
3952 | This enables all backends - without this feature, you need to enable at |
3953 | This enables all backends - without this feature, you need to enable at |
3953 | least one backend manually (C<EV_USE_SELECT> is a good choice). |
3954 | least one backend manually (C<EV_USE_SELECT> is a good choice). |
3954 | |
3955 | |
3955 | =item C<32> - enable OS-specific "helper" APIs |
3956 | =item C<64> - enable OS-specific "helper" APIs |
3956 | |
3957 | |
3957 | Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by |
3958 | Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by |
3958 | default. |
3959 | default. |
3959 | |
3960 | |
3960 | =back |
3961 | =back |
3961 | |
3962 | |
3962 | Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0> |
3963 | Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0> |
3963 | reduces the compiled size of libev from 24.7Kb to 6.5Kb on my GNU/Linux |
3964 | reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb |
3964 | amd64 system, while still giving you I/O watchers, timers and monotonic |
3965 | code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O |
3965 | clock support. |
3966 | watchers, timers and monotonic clock support. |
3966 | |
3967 | |
3967 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
3968 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
3968 | when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by |
3969 | when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by |
3969 | your program might be left out as well - a binary starting a timer and an |
3970 | your program might be left out as well - a binary starting a timer and an |
3970 | I/O watcher then might come out at only 5Kb. |
3971 | I/O watcher then might come out at only 5Kb. |
3971 | |
3972 | |
3972 | =item EV_AVOID_STDIO |
3973 | =item EV_AVOID_STDIO |
3973 | |
3974 | |
3974 | If this is set to C<1> at compiletime, then libev will avoid using stdio |
3975 | If this is set to C<1> at compiletime, then libev will avoid using stdio |
3975 | functions (printf, scanf, perror etc.). This will increase the codesize |
3976 | functions (printf, scanf, perror etc.). This will increase the code size |
3976 | somewhat, but if your program doesn't otherwise depend on stdio and your |
3977 | somewhat, but if your program doesn't otherwise depend on stdio and your |
3977 | libc allows it, this avoids linking in the stdio library which is quite |
3978 | libc allows it, this avoids linking in the stdio library which is quite |
3978 | big. |
3979 | big. |
3979 | |
3980 | |
3980 | Note that error messages might become less precise when this option is |
3981 | Note that error messages might become less precise when this option is |
… | |
… | |
3984 | |
3985 | |
3985 | The highest supported signal number, +1 (or, the number of |
3986 | The highest supported signal number, +1 (or, the number of |
3986 | signals): Normally, libev tries to deduce the maximum number of signals |
3987 | signals): Normally, libev tries to deduce the maximum number of signals |
3987 | automatically, but sometimes this fails, in which case it can be |
3988 | automatically, but sometimes this fails, in which case it can be |
3988 | specified. Also, using a lower number than detected (C<32> should be |
3989 | specified. Also, using a lower number than detected (C<32> should be |
3989 | good for about any system in existance) can save some memory, as libev |
3990 | good for about any system in existence) can save some memory, as libev |
3990 | statically allocates some 12-24 bytes per signal number. |
3991 | statically allocates some 12-24 bytes per signal number. |
3991 | |
3992 | |
3992 | =item EV_PID_HASHSIZE |
3993 | =item EV_PID_HASHSIZE |
3993 | |
3994 | |
3994 | C<ev_child> watchers use a small hash table to distribute workload by |
3995 | C<ev_child> watchers use a small hash table to distribute workload by |
… | |
… | |
4040 | will be C<0>. |
4041 | will be C<0>. |
4041 | |
4042 | |
4042 | =item EV_COMMON |
4043 | =item EV_COMMON |
4043 | |
4044 | |
4044 | By default, all watchers have a C<void *data> member. By redefining |
4045 | By default, all watchers have a C<void *data> member. By redefining |
4045 | this macro to a something else you can include more and other types of |
4046 | this macro to something else you can include more and other types of |
4046 | members. You have to define it each time you include one of the files, |
4047 | members. You have to define it each time you include one of the files, |
4047 | though, and it must be identical each time. |
4048 | though, and it must be identical each time. |
4048 | |
4049 | |
4049 | For example, the perl EV module uses something like this: |
4050 | For example, the perl EV module uses something like this: |
4050 | |
4051 | |
… | |
… | |
4103 | file. |
4104 | file. |
4104 | |
4105 | |
4105 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
4106 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
4106 | that everybody includes and which overrides some configure choices: |
4107 | that everybody includes and which overrides some configure choices: |
4107 | |
4108 | |
4108 | #define EV_FEATURES 0 |
4109 | #define EV_FEATURES 8 |
4109 | #define EV_USE_SELECT 1 |
4110 | #define EV_USE_SELECT 1 |
|
|
4111 | #define EV_PREPARE_ENABLE 1 |
|
|
4112 | #define EV_IDLE_ENABLE 1 |
|
|
4113 | #define EV_SIGNAL_ENABLE 1 |
|
|
4114 | #define EV_CHILD_ENABLE 1 |
|
|
4115 | #define EV_USE_STDEXCEPT 0 |
4110 | #define EV_CONFIG_H <config.h> |
4116 | #define EV_CONFIG_H <config.h> |
4111 | |
4117 | |
4112 | #include "ev++.h" |
4118 | #include "ev++.h" |
4113 | |
4119 | |
4114 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
4120 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
… | |
… | |
4344 | maintainable. |
4350 | maintainable. |
4345 | |
4351 | |
4346 | And of course, some compiler warnings are just plain stupid, or simply |
4352 | And of course, some compiler warnings are just plain stupid, or simply |
4347 | wrong (because they don't actually warn about the condition their message |
4353 | wrong (because they don't actually warn about the condition their message |
4348 | seems to warn about). For example, certain older gcc versions had some |
4354 | seems to warn about). For example, certain older gcc versions had some |
4349 | warnings that resulted an extreme number of false positives. These have |
4355 | warnings that resulted in an extreme number of false positives. These have |
4350 | been fixed, but some people still insist on making code warn-free with |
4356 | been fixed, but some people still insist on making code warn-free with |
4351 | such buggy versions. |
4357 | such buggy versions. |
4352 | |
4358 | |
4353 | While libev is written to generate as few warnings as possible, |
4359 | While libev is written to generate as few warnings as possible, |
4354 | "warn-free" code is not a goal, and it is recommended not to build libev |
4360 | "warn-free" code is not a goal, and it is recommended not to build libev |
… | |
… | |
4389 | If you need, for some reason, empty reports from valgrind for your project |
4395 | If you need, for some reason, empty reports from valgrind for your project |
4390 | I suggest using suppression lists. |
4396 | I suggest using suppression lists. |
4391 | |
4397 | |
4392 | |
4398 | |
4393 | =head1 PORTABILITY NOTES |
4399 | =head1 PORTABILITY NOTES |
|
|
4400 | |
|
|
4401 | =head2 GNU/LINUX 32 BIT LIMITATIONS |
|
|
4402 | |
|
|
4403 | GNU/Linux is the only common platform that supports 64 bit file/large file |
|
|
4404 | interfaces but disables them by default. |
|
|
4405 | |
|
|
4406 | That means that libev compiled in the default environment doesn't support |
|
|
4407 | files larger than 2GiB, which mainly affects C<ev_stat> watchers. |
|
|
4408 | |
|
|
4409 | Unfortunately, many programs try to work around this GNU/Linux issue |
|
|
4410 | by enabling the large file API, which makes them incompatible with the |
|
|
4411 | standard libev compiled for their system. |
|
|
4412 | |
|
|
4413 | Likewise, libev cannot enable the large file API itself as this would |
|
|
4414 | suddenly make it incompatible to the default compile time environment, |
|
|
4415 | i.e. all programs not using special compile switches. |
|
|
4416 | |
|
|
4417 | =head2 OS/X AND DARWIN BUGS |
|
|
4418 | |
|
|
4419 | The whole thing is a bug if you ask me - basically any system interface |
|
|
4420 | you touch is broken, whether it is locales, poll, kqueue or even their |
|
|
4421 | OpenGL drivers. |
|
|
4422 | |
|
|
4423 | =over 4 |
|
|
4424 | |
|
|
4425 | =item KQUEUE IS BUGGY |
|
|
4426 | |
|
|
4427 | The kqueue syscall is broken in all known versions - most versions support |
|
|
4428 | only sockets, many support pipes. |
|
|
4429 | |
|
|
4430 | =item POLL IS BUGGY |
|
|
4431 | |
|
|
4432 | Instead of fixing C<kqueue>, Apple replaced their (working) C<poll> |
|
|
4433 | implementation by something calling C<kqueue> internally around the 10.5.6 |
|
|
4434 | release, so now C<kqueue> I<and> C<poll> are broken. |
|
|
4435 | |
|
|
4436 | Libev tries to work around this by neither using C<kqueue> nor C<poll> by |
|
|
4437 | default on this rotten platform, but of course you cna still ask for them |
|
|
4438 | when creating a loop. |
|
|
4439 | |
|
|
4440 | =item SELECT IS BUGGY |
|
|
4441 | |
|
|
4442 | All that's left is C<select>, and of course Apple found a way to fuck this |
|
|
4443 | one up as well: On OS/X, C<select> actively limits the number of file |
|
|
4444 | descriptors you can pass in to 1024 - your program suddenyl crashes when |
|
|
4445 | you use more. |
|
|
4446 | |
|
|
4447 | There is an undocumented "workaround" for this - defining |
|
|
4448 | C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should> |
|
|
4449 | work on OS/X. |
|
|
4450 | |
|
|
4451 | =back |
|
|
4452 | |
|
|
4453 | =head2 SOLARIS PROBLEMS AND WORKAROUNDS |
|
|
4454 | |
|
|
4455 | =over 4 |
|
|
4456 | |
|
|
4457 | =item C<errno> reentrancy |
|
|
4458 | |
|
|
4459 | The default compile environment on Solaris is unfortunately so |
|
|
4460 | thread-unsafe that you can't even use components/libraries compiled |
|
|
4461 | without C<-D_REENTRANT> (as long as they use C<errno>), which, of course, |
|
|
4462 | isn't defined by default. |
|
|
4463 | |
|
|
4464 | If you want to use libev in threaded environments you have to make sure |
|
|
4465 | it's compiled with C<_REENTRANT> defined. |
|
|
4466 | |
|
|
4467 | =item Event Port Backend |
|
|
4468 | |
|
|
4469 | The scalable event interface for Solaris is called "event ports". Unfortunately, |
|
|
4470 | this mechanism is very buggy. If you run into high CPU usage, your program |
|
|
4471 | freezes or you get a large number of spurious wakeups, make sure you have |
|
|
4472 | all the relevant and latest kernel patches applied. No, I don't know which |
|
|
4473 | ones, but there are multiple ones. |
|
|
4474 | |
|
|
4475 | If you can't get it to work, you can try running the program with |
|
|
4476 | C<LIBEV_FLAGS=3> to only allow C<poll> and C<select> backends. |
|
|
4477 | |
|
|
4478 | =back |
|
|
4479 | |
|
|
4480 | =head2 AIX POLL BUG |
|
|
4481 | |
|
|
4482 | AIX unfortunately has a broken C<poll.h> header. Libev works around |
|
|
4483 | this by trying to avoid the poll backend altogether (i.e. it's not even |
|
|
4484 | compiled in), which normally isn't a big problem as C<select> works fine |
|
|
4485 | with large bitsets, and AIX is dead anyway. |
4394 | |
4486 | |
4395 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
4487 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
4396 | |
4488 | |
4397 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
4489 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
4398 | requires, and its I/O model is fundamentally incompatible with the POSIX |
4490 | requires, and its I/O model is fundamentally incompatible with the POSIX |
… | |
… | |
4617 | involves iterating over all running async watchers or all signal numbers. |
4709 | involves iterating over all running async watchers or all signal numbers. |
4618 | |
4710 | |
4619 | =back |
4711 | =back |
4620 | |
4712 | |
4621 | |
4713 | |
|
|
4714 | =head1 PORTING FROM LIBEV 3.X TO 4.X |
|
|
4715 | |
|
|
4716 | The major version 4 introduced some minor incompatible changes to the API. |
|
|
4717 | |
|
|
4718 | At the moment, the C<ev.h> header file tries to implement superficial |
|
|
4719 | compatibility, so most programs should still compile. Those might be |
|
|
4720 | removed in later versions of libev, so better update early than late. |
|
|
4721 | |
|
|
4722 | =over 4 |
|
|
4723 | |
|
|
4724 | =item C<ev_loop_count> renamed to C<ev_iteration> |
|
|
4725 | |
|
|
4726 | =item C<ev_loop_depth> renamed to C<ev_depth> |
|
|
4727 | |
|
|
4728 | =item C<ev_loop_verify> renamed to C<ev_verify> |
|
|
4729 | |
|
|
4730 | Most functions working on C<struct ev_loop> objects don't have an |
|
|
4731 | C<ev_loop_> prefix, so it was removed. Note that C<ev_loop_fork> is |
|
|
4732 | still called C<ev_loop_fork> because it would otherwise clash with the |
|
|
4733 | C<ev_fork> typedef. |
|
|
4734 | |
|
|
4735 | =item C<EV_TIMEOUT> renamed to C<EV_TIMER> in C<revents> |
|
|
4736 | |
|
|
4737 | This is a simple rename - all other watcher types use their name |
|
|
4738 | as revents flag, and now C<ev_timer> does, too. |
|
|
4739 | |
|
|
4740 | Both C<EV_TIMER> and C<EV_TIMEOUT> symbols were present in 3.x versions |
|
|
4741 | and continue to be present for the foreseeable future, so this is mostly a |
|
|
4742 | documentation change. |
|
|
4743 | |
|
|
4744 | =item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> |
|
|
4745 | |
|
|
4746 | The preprocessor symbol C<EV_MINIMAL> has been replaced by a different |
|
|
4747 | mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile |
|
|
4748 | and work, but the library code will of course be larger. |
|
|
4749 | |
|
|
4750 | =back |
|
|
4751 | |
|
|
4752 | |
4622 | =head1 GLOSSARY |
4753 | =head1 GLOSSARY |
4623 | |
4754 | |
4624 | =over 4 |
4755 | =over 4 |
4625 | |
4756 | |
4626 | =item active |
4757 | =item active |
… | |
… | |
4647 | A change of state of some external event, such as data now being available |
4778 | A change of state of some external event, such as data now being available |
4648 | for reading on a file descriptor, time having passed or simply not having |
4779 | for reading on a file descriptor, time having passed or simply not having |
4649 | any other events happening anymore. |
4780 | any other events happening anymore. |
4650 | |
4781 | |
4651 | In libev, events are represented as single bits (such as C<EV_READ> or |
4782 | In libev, events are represented as single bits (such as C<EV_READ> or |
4652 | C<EV_TIMEOUT>). |
4783 | C<EV_TIMER>). |
4653 | |
4784 | |
4654 | =item event library |
4785 | =item event library |
4655 | |
4786 | |
4656 | A software package implementing an event model and loop. |
4787 | A software package implementing an event model and loop. |
4657 | |
4788 | |