… | |
… | |
8 | |
8 | |
9 | =head2 EXAMPLE PROGRAM |
9 | =head2 EXAMPLE PROGRAM |
10 | |
10 | |
11 | // a single header file is required |
11 | // a single header file is required |
12 | #include <ev.h> |
12 | #include <ev.h> |
|
|
13 | |
|
|
14 | #include <stdio.h> // for puts |
13 | |
15 | |
14 | // every watcher type has its own typedef'd struct |
16 | // every watcher type has its own typedef'd struct |
15 | // with the name ev_TYPE |
17 | // with the name ev_TYPE |
16 | ev_io stdin_watcher; |
18 | ev_io stdin_watcher; |
17 | ev_timer timeout_watcher; |
19 | ev_timer timeout_watcher; |
… | |
… | |
41 | |
43 | |
42 | int |
44 | int |
43 | main (void) |
45 | main (void) |
44 | { |
46 | { |
45 | // use the default event loop unless you have special needs |
47 | // use the default event loop unless you have special needs |
46 | ev_loop *loop = ev_default_loop (0); |
48 | struct ev_loop *loop = ev_default_loop (0); |
47 | |
49 | |
48 | // initialise an io watcher, then start it |
50 | // initialise an io watcher, then start it |
49 | // this one will watch for stdin to become readable |
51 | // this one will watch for stdin to become readable |
50 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
52 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
51 | ev_io_start (loop, &stdin_watcher); |
53 | ev_io_start (loop, &stdin_watcher); |
… | |
… | |
298 | If you don't know what event loop to use, use the one returned from this |
300 | If you don't know what event loop to use, use the one returned from this |
299 | function. |
301 | function. |
300 | |
302 | |
301 | Note that this function is I<not> thread-safe, so if you want to use it |
303 | Note that this function is I<not> thread-safe, so if you want to use it |
302 | from multiple threads, you have to lock (note also that this is unlikely, |
304 | from multiple threads, you have to lock (note also that this is unlikely, |
303 | as loops cannot bes hared easily between threads anyway). |
305 | as loops cannot be shared easily between threads anyway). |
304 | |
306 | |
305 | The default loop is the only loop that can handle C<ev_signal> and |
307 | The default loop is the only loop that can handle C<ev_signal> and |
306 | C<ev_child> watchers, and to do this, it always registers a handler |
308 | C<ev_child> watchers, and to do this, it always registers a handler |
307 | for C<SIGCHLD>. If this is a problem for your application you can either |
309 | for C<SIGCHLD>. If this is a problem for your application you can either |
308 | create a dynamic loop with C<ev_loop_new> that doesn't do that, or you |
310 | create a dynamic loop with C<ev_loop_new> that doesn't do that, or you |
… | |
… | |
386 | For few fds, this backend is a bit little slower than poll and select, |
388 | For few fds, this backend is a bit little slower than poll and select, |
387 | but it scales phenomenally better. While poll and select usually scale |
389 | but it scales phenomenally better. While poll and select usually scale |
388 | like O(total_fds) where n is the total number of fds (or the highest fd), |
390 | like O(total_fds) where n is the total number of fds (or the highest fd), |
389 | epoll scales either O(1) or O(active_fds). |
391 | epoll scales either O(1) or O(active_fds). |
390 | |
392 | |
391 | The epoll syscalls are the most misdesigned of the more advanced event |
393 | The epoll mechanism deserves honorable mention as the most misdesigned |
392 | mechanisms: problems include silently dropping fds, requiring a system |
394 | of the more advanced event mechanisms: mere annoyances include silently |
393 | call per change per fd (and unnecessary guessing of parameters), problems |
395 | dropping file descriptors, requiring a system call per change per file |
|
|
396 | descriptor (and unnecessary guessing of parameters), problems with dup and |
394 | with dup and so on. The biggest issue is fork races, however - if a |
397 | so on. The biggest issue is fork races, however - if a program forks then |
395 | program forks then I<both> parent and child process have to recreate the |
398 | I<both> parent and child process have to recreate the epoll set, which can |
396 | epoll set, which can take considerable time (one syscall per fd) and is of |
399 | take considerable time (one syscall per file descriptor) and is of course |
397 | course hard to detect. |
400 | hard to detect. |
398 | |
401 | |
399 | Epoll is also notoriously buggy - embedding epoll fds should work, but |
402 | Epoll is also notoriously buggy - embedding epoll fds I<should> work, but |
400 | of course doesn't, and epoll just loves to report events for totally |
403 | of course I<doesn't>, and epoll just loves to report events for totally |
401 | I<different> file descriptors (even already closed ones, so one cannot |
404 | I<different> file descriptors (even already closed ones, so one cannot |
402 | even remove them from the set) than registered in the set (especially |
405 | even remove them from the set) than registered in the set (especially |
403 | on SMP systems). Libev tries to counter these spurious notifications by |
406 | on SMP systems). Libev tries to counter these spurious notifications by |
404 | employing an additional generation counter and comparing that against the |
407 | employing an additional generation counter and comparing that against the |
405 | events to filter out spurious ones. |
408 | events to filter out spurious ones, recreating the set when required. |
406 | |
409 | |
407 | While stopping, setting and starting an I/O watcher in the same iteration |
410 | While stopping, setting and starting an I/O watcher in the same iteration |
408 | will result in some caching, there is still a system call per such incident |
411 | will result in some caching, there is still a system call per such |
409 | (because the fd could point to a different file description now), so its |
412 | incident (because the same I<file descriptor> could point to a different |
410 | best to avoid that. Also, C<dup ()>'ed file descriptors might not work |
413 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
411 | very well if you register events for both fds. |
414 | file descriptors might not work very well if you register events for both |
|
|
415 | file descriptors. |
412 | |
416 | |
413 | Best performance from this backend is achieved by not unregistering all |
417 | Best performance from this backend is achieved by not unregistering all |
414 | watchers for a file descriptor until it has been closed, if possible, |
418 | watchers for a file descriptor until it has been closed, if possible, |
415 | i.e. keep at least one watcher active per fd at all times. Stopping and |
419 | i.e. keep at least one watcher active per fd at all times. Stopping and |
416 | starting a watcher (without re-setting it) also usually doesn't cause |
420 | starting a watcher (without re-setting it) also usually doesn't cause |
417 | extra overhead. A fork can both result in spurious notifications as well |
421 | extra overhead. A fork can both result in spurious notifications as well |
418 | as in libev having to destroy and recreate the epoll object, which can |
422 | as in libev having to destroy and recreate the epoll object, which can |
419 | take considerable time and thus should be avoided. |
423 | take considerable time and thus should be avoided. |
420 | |
424 | |
|
|
425 | All this means that, in practice, C<EVBACKEND_SELECT> can be as fast or |
|
|
426 | faster than epoll for maybe up to a hundred file descriptors, depending on |
|
|
427 | the usage. So sad. |
|
|
428 | |
421 | While nominally embeddable in other event loops, this feature is broken in |
429 | While nominally embeddable in other event loops, this feature is broken in |
422 | all kernel versions tested so far. |
430 | all kernel versions tested so far. |
423 | |
431 | |
424 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
432 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
425 | C<EVBACKEND_POLL>. |
433 | C<EVBACKEND_POLL>. |
426 | |
434 | |
427 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
435 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
428 | |
436 | |
429 | Kqueue deserves special mention, as at the time of this writing, it was |
437 | Kqueue deserves special mention, as at the time of this writing, it |
430 | broken on all BSDs except NetBSD (usually it doesn't work reliably with |
438 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
431 | anything but sockets and pipes, except on Darwin, where of course it's |
439 | with anything but sockets and pipes, except on Darwin, where of course |
432 | completely useless). For this reason it's not being "auto-detected" unless |
440 | it's completely useless). Unlike epoll, however, whose brokenness |
433 | you explicitly specify it in the flags (i.e. using C<EVBACKEND_KQUEUE>) or |
441 | is by design, these kqueue bugs can (and eventually will) be fixed |
434 | libev was compiled on a known-to-be-good (-enough) system like NetBSD. |
442 | without API changes to existing programs. For this reason it's not being |
|
|
443 | "auto-detected" unless you explicitly specify it in the flags (i.e. using |
|
|
444 | C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough) |
|
|
445 | system like NetBSD. |
435 | |
446 | |
436 | You still can embed kqueue into a normal poll or select backend and use it |
447 | You still can embed kqueue into a normal poll or select backend and use it |
437 | only for sockets (after having made sure that sockets work with kqueue on |
448 | only for sockets (after having made sure that sockets work with kqueue on |
438 | the target platform). See C<ev_embed> watchers for more info. |
449 | the target platform). See C<ev_embed> watchers for more info. |
439 | |
450 | |
… | |
… | |
449 | |
460 | |
450 | While nominally embeddable in other event loops, this doesn't work |
461 | While nominally embeddable in other event loops, this doesn't work |
451 | everywhere, so you might need to test for this. And since it is broken |
462 | everywhere, so you might need to test for this. And since it is broken |
452 | almost everywhere, you should only use it when you have a lot of sockets |
463 | almost everywhere, you should only use it when you have a lot of sockets |
453 | (for which it usually works), by embedding it into another event loop |
464 | (for which it usually works), by embedding it into another event loop |
454 | (e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and, did I mention it, |
465 | (e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> (but C<poll> is of course |
455 | using it only for sockets. |
466 | also broken on OS X)) and, did I mention it, using it only for sockets. |
456 | |
467 | |
457 | This backend maps C<EV_READ> into an C<EVFILT_READ> kevent with |
468 | This backend maps C<EV_READ> into an C<EVFILT_READ> kevent with |
458 | C<NOTE_EOF>, and C<EV_WRITE> into an C<EVFILT_WRITE> kevent with |
469 | C<NOTE_EOF>, and C<EV_WRITE> into an C<EVFILT_WRITE> kevent with |
459 | C<NOTE_EOF>. |
470 | C<NOTE_EOF>. |
460 | |
471 | |
… | |
… | |
647 | the loop. |
658 | the loop. |
648 | |
659 | |
649 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
660 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
650 | necessary) and will handle those and any already outstanding ones. It |
661 | necessary) and will handle those and any already outstanding ones. It |
651 | will block your process until at least one new event arrives (which could |
662 | will block your process until at least one new event arrives (which could |
652 | be an event internal to libev itself, so there is no guarentee that a |
663 | be an event internal to libev itself, so there is no guarantee that a |
653 | user-registered callback will be called), and will return after one |
664 | user-registered callback will be called), and will return after one |
654 | iteration of the loop. |
665 | iteration of the loop. |
655 | |
666 | |
656 | This is useful if you are waiting for some external event in conjunction |
667 | This is useful if you are waiting for some external event in conjunction |
657 | with something not expressible using other libev watchers (i.e. "roll your |
668 | with something not expressible using other libev watchers (i.e. "roll your |
… | |
… | |
1410 | else |
1421 | else |
1411 | { |
1422 | { |
1412 | // callback was invoked, but there was some activity, re-arm |
1423 | // callback was invoked, but there was some activity, re-arm |
1413 | // the watcher to fire in last_activity + 60, which is |
1424 | // the watcher to fire in last_activity + 60, which is |
1414 | // guaranteed to be in the future, so "again" is positive: |
1425 | // guaranteed to be in the future, so "again" is positive: |
1415 | w->again = timeout - now; |
1426 | w->repeat = timeout - now; |
1416 | ev_timer_again (EV_A_ w); |
1427 | ev_timer_again (EV_A_ w); |
1417 | } |
1428 | } |
1418 | } |
1429 | } |
1419 | |
1430 | |
1420 | To summarise the callback: first calculate the real timeout (defined |
1431 | To summarise the callback: first calculate the real timeout (defined |
… | |
… | |
1608 | |
1619 | |
1609 | =over 4 |
1620 | =over 4 |
1610 | |
1621 | |
1611 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1622 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1612 | |
1623 | |
1613 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
1624 | =item ev_periodic_set (ev_periodic *, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1614 | |
1625 | |
1615 | Lots of arguments, lets sort it out... There are basically three modes of |
1626 | Lots of arguments, lets sort it out... There are basically three modes of |
1616 | operation, and we will explain them from simplest to most complex: |
1627 | operation, and we will explain them from simplest to most complex: |
1617 | |
1628 | |
1618 | =over 4 |
1629 | =over 4 |
… | |
… | |
1660 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1671 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1661 | reschedule callback will be called with the watcher as first, and the |
1672 | reschedule callback will be called with the watcher as first, and the |
1662 | current time as second argument. |
1673 | current time as second argument. |
1663 | |
1674 | |
1664 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1675 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1665 | ever, or make ANY event loop modifications whatsoever>. |
1676 | ever, or make ANY other event loop modifications whatsoever>. |
1666 | |
1677 | |
1667 | If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop |
1678 | If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop |
1668 | it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the |
1679 | it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the |
1669 | only event loop modification you are allowed to do). |
1680 | only event loop modification you are allowed to do). |
1670 | |
1681 | |
… | |
… | |
1927 | C<stat> on that path in regular intervals (or when the OS says it changed) |
1938 | C<stat> on that path in regular intervals (or when the OS says it changed) |
1928 | and sees if it changed compared to the last time, invoking the callback if |
1939 | and sees if it changed compared to the last time, invoking the callback if |
1929 | it did. |
1940 | it did. |
1930 | |
1941 | |
1931 | The path does not need to exist: changing from "path exists" to "path does |
1942 | The path does not need to exist: changing from "path exists" to "path does |
1932 | not exist" is a status change like any other. The condition "path does |
1943 | not exist" is a status change like any other. The condition "path does not |
1933 | not exist" is signified by the C<st_nlink> field being zero (which is |
1944 | exist" (or more correctly "path cannot be stat'ed") is signified by the |
1934 | otherwise always forced to be at least one) and all the other fields of |
1945 | C<st_nlink> field being zero (which is otherwise always forced to be at |
1935 | the stat buffer having unspecified contents. |
1946 | least one) and all the other fields of the stat buffer having unspecified |
|
|
1947 | contents. |
1936 | |
1948 | |
1937 | The path I<must not> end in a slash or contain special components such as |
1949 | The path I<must not> end in a slash or contain special components such as |
1938 | C<.> or C<..>. The path I<should> be absolute: If it is relative and |
1950 | C<.> or C<..>. The path I<should> be absolute: If it is relative and |
1939 | your working directory changes, then the behaviour is undefined. |
1951 | your working directory changes, then the behaviour is undefined. |
1940 | |
1952 | |
… | |
… | |
1943 | to see if it changed somehow. You can specify a recommended polling |
1955 | to see if it changed somehow. You can specify a recommended polling |
1944 | interval for this case. If you specify a polling interval of C<0> (highly |
1956 | interval for this case. If you specify a polling interval of C<0> (highly |
1945 | recommended!) then a I<suitable, unspecified default> value will be used |
1957 | recommended!) then a I<suitable, unspecified default> value will be used |
1946 | (which you can expect to be around five seconds, although this might |
1958 | (which you can expect to be around five seconds, although this might |
1947 | change dynamically). Libev will also impose a minimum interval which is |
1959 | change dynamically). Libev will also impose a minimum interval which is |
1948 | currently around C<0.1>, but thats usually overkill. |
1960 | currently around C<0.1>, but that's usually overkill. |
1949 | |
1961 | |
1950 | This watcher type is not meant for massive numbers of stat watchers, |
1962 | This watcher type is not meant for massive numbers of stat watchers, |
1951 | as even with OS-supported change notifications, this can be |
1963 | as even with OS-supported change notifications, this can be |
1952 | resource-intensive. |
1964 | resource-intensive. |
1953 | |
1965 | |
1954 | At the time of this writing, the only OS-specific interface implemented |
1966 | At the time of this writing, the only OS-specific interface implemented |
1955 | is the Linux inotify interface (implementing kqueue support is left as |
1967 | is the Linux inotify interface (implementing kqueue support is left as an |
1956 | an exercise for the reader. Note, however, that the author sees no way |
1968 | exercise for the reader. Note, however, that the author sees no way of |
1957 | of implementing C<ev_stat> semantics with kqueue). |
1969 | implementing C<ev_stat> semantics with kqueue, except as a hint). |
1958 | |
1970 | |
1959 | =head3 ABI Issues (Largefile Support) |
1971 | =head3 ABI Issues (Largefile Support) |
1960 | |
1972 | |
1961 | Libev by default (unless the user overrides this) uses the default |
1973 | Libev by default (unless the user overrides this) uses the default |
1962 | compilation environment, which means that on systems with large file |
1974 | compilation environment, which means that on systems with large file |
… | |
… | |
1973 | to exchange stat structures with application programs compiled using the |
1985 | to exchange stat structures with application programs compiled using the |
1974 | default compilation environment. |
1986 | default compilation environment. |
1975 | |
1987 | |
1976 | =head3 Inotify and Kqueue |
1988 | =head3 Inotify and Kqueue |
1977 | |
1989 | |
1978 | When C<inotify (7)> support has been compiled into libev (generally |
1990 | When C<inotify (7)> support has been compiled into libev and present at |
1979 | only available with Linux 2.6.25 or above due to bugs in earlier |
1991 | runtime, it will be used to speed up change detection where possible. The |
1980 | implementations) and present at runtime, it will be used to speed up |
1992 | inotify descriptor will be created lazily when the first C<ev_stat> |
1981 | change detection where possible. The inotify descriptor will be created |
1993 | watcher is being started. |
1982 | lazily when the first C<ev_stat> watcher is being started. |
|
|
1983 | |
1994 | |
1984 | Inotify presence does not change the semantics of C<ev_stat> watchers |
1995 | Inotify presence does not change the semantics of C<ev_stat> watchers |
1985 | except that changes might be detected earlier, and in some cases, to avoid |
1996 | except that changes might be detected earlier, and in some cases, to avoid |
1986 | making regular C<stat> calls. Even in the presence of inotify support |
1997 | making regular C<stat> calls. Even in the presence of inotify support |
1987 | there are many cases where libev has to resort to regular C<stat> polling, |
1998 | there are many cases where libev has to resort to regular C<stat> polling, |
1988 | but as long as the path exists, libev usually gets away without polling. |
1999 | but as long as kernel 2.6.25 or newer is used (2.6.24 and older have too |
|
|
2000 | many bugs), the path exists (i.e. stat succeeds), and the path resides on |
|
|
2001 | a local filesystem (libev currently assumes only ext2/3, jfs, reiserfs and |
|
|
2002 | xfs are fully working) libev usually gets away without polling. |
1989 | |
2003 | |
1990 | There is no support for kqueue, as apparently it cannot be used to |
2004 | There is no support for kqueue, as apparently it cannot be used to |
1991 | implement this functionality, due to the requirement of having a file |
2005 | implement this functionality, due to the requirement of having a file |
1992 | descriptor open on the object at all times, and detecting renames, unlinks |
2006 | descriptor open on the object at all times, and detecting renames, unlinks |
1993 | etc. is difficult. |
2007 | etc. is difficult. |
|
|
2008 | |
|
|
2009 | =head3 C<stat ()> is a synchronous operation |
|
|
2010 | |
|
|
2011 | Libev doesn't normally do any kind of I/O itself, and so is not blocking |
|
|
2012 | the process. The exception are C<ev_stat> watchers - those call C<stat |
|
|
2013 | ()>, which is a synchronous operation. |
|
|
2014 | |
|
|
2015 | For local paths, this usually doesn't matter: unless the system is very |
|
|
2016 | busy or the intervals between stat's are large, a stat call will be fast, |
|
|
2017 | as the path data is usually in memory already (except when starting the |
|
|
2018 | watcher). |
|
|
2019 | |
|
|
2020 | For networked file systems, calling C<stat ()> can block an indefinite |
|
|
2021 | time due to network issues, and even under good conditions, a stat call |
|
|
2022 | often takes multiple milliseconds. |
|
|
2023 | |
|
|
2024 | Therefore, it is best to avoid using C<ev_stat> watchers on networked |
|
|
2025 | paths, although this is fully supported by libev. |
1994 | |
2026 | |
1995 | =head3 The special problem of stat time resolution |
2027 | =head3 The special problem of stat time resolution |
1996 | |
2028 | |
1997 | The C<stat ()> system call only supports full-second resolution portably, |
2029 | The C<stat ()> system call only supports full-second resolution portably, |
1998 | and even on systems where the resolution is higher, most file systems |
2030 | and even on systems where the resolution is higher, most file systems |
… | |
… | |
2147 | |
2179 | |
2148 | =head3 Watcher-Specific Functions and Data Members |
2180 | =head3 Watcher-Specific Functions and Data Members |
2149 | |
2181 | |
2150 | =over 4 |
2182 | =over 4 |
2151 | |
2183 | |
2152 | =item ev_idle_init (ev_signal *, callback) |
2184 | =item ev_idle_init (ev_idle *, callback) |
2153 | |
2185 | |
2154 | Initialises and configures the idle watcher - it has no parameters of any |
2186 | Initialises and configures the idle watcher - it has no parameters of any |
2155 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
2187 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
2156 | believe me. |
2188 | believe me. |
2157 | |
2189 | |
… | |
… | |
2396 | some fds have to be watched and handled very quickly (with low latency), |
2428 | some fds have to be watched and handled very quickly (with low latency), |
2397 | and even priorities and idle watchers might have too much overhead. In |
2429 | and even priorities and idle watchers might have too much overhead. In |
2398 | this case you would put all the high priority stuff in one loop and all |
2430 | this case you would put all the high priority stuff in one loop and all |
2399 | the rest in a second one, and embed the second one in the first. |
2431 | the rest in a second one, and embed the second one in the first. |
2400 | |
2432 | |
2401 | As long as the watcher is active, the callback will be invoked every time |
2433 | As long as the watcher is active, the callback will be invoked every |
2402 | there might be events pending in the embedded loop. The callback must then |
2434 | time there might be events pending in the embedded loop. The callback |
2403 | call C<ev_embed_sweep (mainloop, watcher)> to make a single sweep and invoke |
2435 | must then call C<ev_embed_sweep (mainloop, watcher)> to make a single |
2404 | their callbacks (you could also start an idle watcher to give the embedded |
2436 | sweep and invoke their callbacks (the callback doesn't need to invoke the |
2405 | loop strictly lower priority for example). You can also set the callback |
2437 | C<ev_embed_sweep> function directly, it could also start an idle watcher |
2406 | to C<0>, in which case the embed watcher will automatically execute the |
2438 | to give the embedded loop strictly lower priority for example). |
2407 | embedded loop sweep. |
|
|
2408 | |
2439 | |
2409 | As long as the watcher is started it will automatically handle events. The |
2440 | You can also set the callback to C<0>, in which case the embed watcher |
2410 | callback will be invoked whenever some events have been handled. You can |
2441 | will automatically execute the embedded loop sweep whenever necessary. |
2411 | set the callback to C<0> to avoid having to specify one if you are not |
|
|
2412 | interested in that. |
|
|
2413 | |
2442 | |
2414 | Also, there have not currently been made special provisions for forking: |
2443 | Fork detection will be handled transparently while the C<ev_embed> watcher |
2415 | when you fork, you not only have to call C<ev_loop_fork> on both loops, |
2444 | is active, i.e., the embedded loop will automatically be forked when the |
2416 | but you will also have to stop and restart any C<ev_embed> watchers |
2445 | embedding loop forks. In other cases, the user is responsible for calling |
2417 | yourself - but you can use a fork watcher to handle this automatically, |
2446 | C<ev_loop_fork> on the embedded loop. |
2418 | and future versions of libev might do just that. |
|
|
2419 | |
2447 | |
2420 | Unfortunately, not all backends are embeddable: only the ones returned by |
2448 | Unfortunately, not all backends are embeddable: only the ones returned by |
2421 | C<ev_embeddable_backends> are, which, unfortunately, does not include any |
2449 | C<ev_embeddable_backends> are, which, unfortunately, does not include any |
2422 | portable one. |
2450 | portable one. |
2423 | |
2451 | |
… | |
… | |
2643 | =over 4 |
2671 | =over 4 |
2644 | |
2672 | |
2645 | =item ev_async_init (ev_async *, callback) |
2673 | =item ev_async_init (ev_async *, callback) |
2646 | |
2674 | |
2647 | Initialises and configures the async watcher - it has no parameters of any |
2675 | Initialises and configures the async watcher - it has no parameters of any |
2648 | kind. There is a C<ev_asynd_set> macro, but using it is utterly pointless, |
2676 | kind. There is a C<ev_async_set> macro, but using it is utterly pointless, |
2649 | trust me. |
2677 | trust me. |
2650 | |
2678 | |
2651 | =item ev_async_send (loop, ev_async *) |
2679 | =item ev_async_send (loop, ev_async *) |
2652 | |
2680 | |
2653 | Sends/signals/activates the given C<ev_async> watcher, that is, feeds |
2681 | Sends/signals/activates the given C<ev_async> watcher, that is, feeds |
… | |
… | |
2859 | |
2887 | |
2860 | myclass obj; |
2888 | myclass obj; |
2861 | ev::io iow; |
2889 | ev::io iow; |
2862 | iow.set <myclass, &myclass::io_cb> (&obj); |
2890 | iow.set <myclass, &myclass::io_cb> (&obj); |
2863 | |
2891 | |
|
|
2892 | =item w->set (object *) |
|
|
2893 | |
|
|
2894 | This is an B<experimental> feature that might go away in a future version. |
|
|
2895 | |
|
|
2896 | This is a variation of a method callback - leaving out the method to call |
|
|
2897 | will default the method to C<operator ()>, which makes it possible to use |
|
|
2898 | functor objects without having to manually specify the C<operator ()> all |
|
|
2899 | the time. Incidentally, you can then also leave out the template argument |
|
|
2900 | list. |
|
|
2901 | |
|
|
2902 | The C<operator ()> method prototype must be C<void operator ()(watcher &w, |
|
|
2903 | int revents)>. |
|
|
2904 | |
|
|
2905 | See the method-C<set> above for more details. |
|
|
2906 | |
|
|
2907 | Example: use a functor object as callback. |
|
|
2908 | |
|
|
2909 | struct myfunctor |
|
|
2910 | { |
|
|
2911 | void operator() (ev::io &w, int revents) |
|
|
2912 | { |
|
|
2913 | ... |
|
|
2914 | } |
|
|
2915 | } |
|
|
2916 | |
|
|
2917 | myfunctor f; |
|
|
2918 | |
|
|
2919 | ev::io w; |
|
|
2920 | w.set (&f); |
|
|
2921 | |
2864 | =item w->set<function> (void *data = 0) |
2922 | =item w->set<function> (void *data = 0) |
2865 | |
2923 | |
2866 | Also sets a callback, but uses a static method or plain function as |
2924 | Also sets a callback, but uses a static method or plain function as |
2867 | callback. The optional C<data> argument will be stored in the watcher's |
2925 | callback. The optional C<data> argument will be stored in the watcher's |
2868 | C<data> member and is free for you to use. |
2926 | C<data> member and is free for you to use. |
… | |
… | |
2967 | Tony Arcieri has written a ruby extension that offers access to a subset |
3025 | Tony Arcieri has written a ruby extension that offers access to a subset |
2968 | of the libev API and adds file handle abstractions, asynchronous DNS and |
3026 | of the libev API and adds file handle abstractions, asynchronous DNS and |
2969 | more on top of it. It can be found via gem servers. Its homepage is at |
3027 | more on top of it. It can be found via gem servers. Its homepage is at |
2970 | L<http://rev.rubyforge.org/>. |
3028 | L<http://rev.rubyforge.org/>. |
2971 | |
3029 | |
|
|
3030 | Roger Pack reports that using the link order C<-lws2_32 -lmsvcrt-ruby-190> |
|
|
3031 | makes rev work even on mingw. |
|
|
3032 | |
2972 | =item D |
3033 | =item D |
2973 | |
3034 | |
2974 | Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to |
3035 | Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to |
2975 | be found at L<http://proj.llucax.com.ar/wiki/evd>. |
3036 | be found at L<http://proj.llucax.com.ar/wiki/evd>. |
2976 | |
3037 | |
… | |
… | |
3086 | |
3147 | |
3087 | #define EV_STANDALONE 1 |
3148 | #define EV_STANDALONE 1 |
3088 | #include "ev.h" |
3149 | #include "ev.h" |
3089 | |
3150 | |
3090 | Both header files and implementation files can be compiled with a C++ |
3151 | Both header files and implementation files can be compiled with a C++ |
3091 | compiler (at least, thats a stated goal, and breakage will be treated |
3152 | compiler (at least, that's a stated goal, and breakage will be treated |
3092 | as a bug). |
3153 | as a bug). |
3093 | |
3154 | |
3094 | You need the following files in your source tree, or in a directory |
3155 | You need the following files in your source tree, or in a directory |
3095 | in your include path (e.g. in libev/ when using -Ilibev): |
3156 | in your include path (e.g. in libev/ when using -Ilibev): |
3096 | |
3157 | |
… | |
… | |
3152 | keeps libev from including F<config.h>, and it also defines dummy |
3213 | keeps libev from including F<config.h>, and it also defines dummy |
3153 | implementations for some libevent functions (such as logging, which is not |
3214 | implementations for some libevent functions (such as logging, which is not |
3154 | supported). It will also not define any of the structs usually found in |
3215 | supported). It will also not define any of the structs usually found in |
3155 | F<event.h> that are not directly supported by the libev core alone. |
3216 | F<event.h> that are not directly supported by the libev core alone. |
3156 | |
3217 | |
|
|
3218 | In stanbdalone mode, libev will still try to automatically deduce the |
|
|
3219 | configuration, but has to be more conservative. |
|
|
3220 | |
3157 | =item EV_USE_MONOTONIC |
3221 | =item EV_USE_MONOTONIC |
3158 | |
3222 | |
3159 | If defined to be C<1>, libev will try to detect the availability of the |
3223 | If defined to be C<1>, libev will try to detect the availability of the |
3160 | monotonic clock option at both compile time and runtime. Otherwise no use |
3224 | monotonic clock option at both compile time and runtime. Otherwise no |
3161 | of the monotonic clock option will be attempted. If you enable this, you |
3225 | use of the monotonic clock option will be attempted. If you enable this, |
3162 | usually have to link against librt or something similar. Enabling it when |
3226 | you usually have to link against librt or something similar. Enabling it |
3163 | the functionality isn't available is safe, though, although you have |
3227 | when the functionality isn't available is safe, though, although you have |
3164 | to make sure you link against any libraries where the C<clock_gettime> |
3228 | to make sure you link against any libraries where the C<clock_gettime> |
3165 | function is hiding in (often F<-lrt>). |
3229 | function is hiding in (often F<-lrt>). See also C<EV_USE_CLOCK_SYSCALL>. |
3166 | |
3230 | |
3167 | =item EV_USE_REALTIME |
3231 | =item EV_USE_REALTIME |
3168 | |
3232 | |
3169 | If defined to be C<1>, libev will try to detect the availability of the |
3233 | If defined to be C<1>, libev will try to detect the availability of the |
3170 | real-time clock option at compile time (and assume its availability at |
3234 | real-time clock option at compile time (and assume its availability |
3171 | runtime if successful). Otherwise no use of the real-time clock option will |
3235 | at runtime if successful). Otherwise no use of the real-time clock |
3172 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
3236 | option will be attempted. This effectively replaces C<gettimeofday> |
3173 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
3237 | by C<clock_get (CLOCK_REALTIME, ...)> and will not normally affect |
3174 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
3238 | correctness. See the note about libraries in the description of |
|
|
3239 | C<EV_USE_MONOTONIC>, though. Defaults to the opposite value of |
|
|
3240 | C<EV_USE_CLOCK_SYSCALL>. |
|
|
3241 | |
|
|
3242 | =item EV_USE_CLOCK_SYSCALL |
|
|
3243 | |
|
|
3244 | If defined to be C<1>, libev will try to use a direct syscall instead |
|
|
3245 | of calling the system-provided C<clock_gettime> function. This option |
|
|
3246 | exists because on GNU/Linux, C<clock_gettime> is in C<librt>, but C<librt> |
|
|
3247 | unconditionally pulls in C<libpthread>, slowing down single-threaded |
|
|
3248 | programs needlessly. Using a direct syscall is slightly slower (in |
|
|
3249 | theory), because no optimised vdso implementation can be used, but avoids |
|
|
3250 | the pthread dependency. Defaults to C<1> on GNU/Linux with glibc 2.x or |
|
|
3251 | higher, as it simplifies linking (no need for C<-lrt>). |
3175 | |
3252 | |
3176 | =item EV_USE_NANOSLEEP |
3253 | =item EV_USE_NANOSLEEP |
3177 | |
3254 | |
3178 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
3255 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
3179 | and will use it for delays. Otherwise it will use C<select ()>. |
3256 | and will use it for delays. Otherwise it will use C<select ()>. |
… | |
… | |
3195 | |
3272 | |
3196 | =item EV_SELECT_USE_FD_SET |
3273 | =item EV_SELECT_USE_FD_SET |
3197 | |
3274 | |
3198 | If defined to C<1>, then the select backend will use the system C<fd_set> |
3275 | If defined to C<1>, then the select backend will use the system C<fd_set> |
3199 | structure. This is useful if libev doesn't compile due to a missing |
3276 | structure. This is useful if libev doesn't compile due to a missing |
3200 | C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout on |
3277 | C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout |
3201 | exotic systems. This usually limits the range of file descriptors to some |
3278 | on exotic systems. This usually limits the range of file descriptors to |
3202 | low limit such as 1024 or might have other limitations (winsocket only |
3279 | some low limit such as 1024 or might have other limitations (winsocket |
3203 | allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might |
3280 | only allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, |
3204 | influence the size of the C<fd_set> used. |
3281 | configures the maximum size of the C<fd_set>. |
3205 | |
3282 | |
3206 | =item EV_SELECT_IS_WINSOCKET |
3283 | =item EV_SELECT_IS_WINSOCKET |
3207 | |
3284 | |
3208 | When defined to C<1>, the select backend will assume that |
3285 | When defined to C<1>, the select backend will assume that |
3209 | select/socket/connect etc. don't understand file descriptors but |
3286 | select/socket/connect etc. don't understand file descriptors but |
… | |
… | |
3568 | loop, as long as you don't confuse yourself). The only exception is that |
3645 | loop, as long as you don't confuse yourself). The only exception is that |
3569 | you must not do this from C<ev_periodic> reschedule callbacks. |
3646 | you must not do this from C<ev_periodic> reschedule callbacks. |
3570 | |
3647 | |
3571 | Care has been taken to ensure that libev does not keep local state inside |
3648 | Care has been taken to ensure that libev does not keep local state inside |
3572 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
3649 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
3573 | they do not clal any callbacks. |
3650 | they do not call any callbacks. |
3574 | |
3651 | |
3575 | =head2 COMPILER WARNINGS |
3652 | =head2 COMPILER WARNINGS |
3576 | |
3653 | |
3577 | Depending on your compiler and compiler settings, you might get no or a |
3654 | Depending on your compiler and compiler settings, you might get no or a |
3578 | lot of warnings when compiling libev code. Some people are apparently |
3655 | lot of warnings when compiling libev code. Some people are apparently |
… | |
… | |
3612 | ==2274== definitely lost: 0 bytes in 0 blocks. |
3689 | ==2274== definitely lost: 0 bytes in 0 blocks. |
3613 | ==2274== possibly lost: 0 bytes in 0 blocks. |
3690 | ==2274== possibly lost: 0 bytes in 0 blocks. |
3614 | ==2274== still reachable: 256 bytes in 1 blocks. |
3691 | ==2274== still reachable: 256 bytes in 1 blocks. |
3615 | |
3692 | |
3616 | Then there is no memory leak, just as memory accounted to global variables |
3693 | Then there is no memory leak, just as memory accounted to global variables |
3617 | is not a memleak - the memory is still being refernced, and didn't leak. |
3694 | is not a memleak - the memory is still being referenced, and didn't leak. |
3618 | |
3695 | |
3619 | Similarly, under some circumstances, valgrind might report kernel bugs |
3696 | Similarly, under some circumstances, valgrind might report kernel bugs |
3620 | as if it were a bug in libev (e.g. in realloc or in the poll backend, |
3697 | as if it were a bug in libev (e.g. in realloc or in the poll backend, |
3621 | although an acceptable workaround has been found here), or it might be |
3698 | although an acceptable workaround has been found here), or it might be |
3622 | confused. |
3699 | confused. |
… | |
… | |
3860 | =back |
3937 | =back |
3861 | |
3938 | |
3862 | |
3939 | |
3863 | =head1 AUTHOR |
3940 | =head1 AUTHOR |
3864 | |
3941 | |
3865 | Marc Lehmann <libev@schmorp.de>. |
3942 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |
3866 | |
3943 | |