… | |
… | |
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 | |
… | |
… | |
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 |
… | |
… | |
1922 | |
1933 | |
1923 | |
1934 | |
1924 | =head2 C<ev_stat> - did the file attributes just change? |
1935 | =head2 C<ev_stat> - did the file attributes just change? |
1925 | |
1936 | |
1926 | This watches a file system path for attribute changes. That is, it calls |
1937 | This watches a file system path for attribute changes. That is, it calls |
1927 | C<stat> regularly (or when the OS says it changed) and sees if it changed |
1938 | C<stat> on that path in regular intervals (or when the OS says it changed) |
1928 | compared to the last time, invoking the callback if it did. |
1939 | and sees if it changed compared to the last time, invoking the callback if |
|
|
1940 | it did. |
1929 | |
1941 | |
1930 | 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 |
1931 | 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 |
1932 | 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 |
1933 | 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 |
1934 | the stat buffer having unspecified contents. |
1946 | least one) and all the other fields of the stat buffer having unspecified |
|
|
1947 | contents. |
1935 | |
1948 | |
1936 | The path I<should> be absolute and I<must not> end in a slash. If it is |
1949 | The path I<must not> end in a slash or contain special components such as |
|
|
1950 | C<.> or C<..>. The path I<should> be absolute: If it is relative and |
1937 | relative and your working directory changes, the behaviour is undefined. |
1951 | your working directory changes, then the behaviour is undefined. |
1938 | |
1952 | |
1939 | Since there is no standard kernel interface to do this, the portable |
1953 | Since there is no portable change notification interface available, the |
1940 | implementation simply calls C<stat (2)> regularly on the path to see if |
1954 | portable implementation simply calls C<stat(2)> regularly on the path |
1941 | it changed somehow. You can specify a recommended polling interval for |
1955 | to see if it changed somehow. You can specify a recommended polling |
1942 | this case. If you specify a polling interval of C<0> (highly recommended!) |
1956 | interval for this case. If you specify a polling interval of C<0> (highly |
1943 | then a I<suitable, unspecified default> value will be used (which |
1957 | recommended!) then a I<suitable, unspecified default> value will be used |
1944 | you can expect to be around five seconds, although this might change |
1958 | (which you can expect to be around five seconds, although this might |
1945 | dynamically). Libev will also impose a minimum interval which is currently |
1959 | change dynamically). Libev will also impose a minimum interval which is |
1946 | around C<0.1>, but thats usually overkill. |
1960 | currently around C<0.1>, but that's usually overkill. |
1947 | |
1961 | |
1948 | 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, |
1949 | as even with OS-supported change notifications, this can be |
1963 | as even with OS-supported change notifications, this can be |
1950 | resource-intensive. |
1964 | resource-intensive. |
1951 | |
1965 | |
1952 | 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 |
1953 | is the Linux inotify interface (implementing kqueue support is left as |
1967 | is the Linux inotify interface (implementing kqueue support is left as an |
1954 | 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 |
1955 | of implementing C<ev_stat> semantics with kqueue). |
1969 | implementing C<ev_stat> semantics with kqueue, except as a hint). |
1956 | |
1970 | |
1957 | =head3 ABI Issues (Largefile Support) |
1971 | =head3 ABI Issues (Largefile Support) |
1958 | |
1972 | |
1959 | Libev by default (unless the user overrides this) uses the default |
1973 | Libev by default (unless the user overrides this) uses the default |
1960 | compilation environment, which means that on systems with large file |
1974 | compilation environment, which means that on systems with large file |
1961 | support disabled by default, you get the 32 bit version of the stat |
1975 | support disabled by default, you get the 32 bit version of the stat |
1962 | structure. When using the library from programs that change the ABI to |
1976 | structure. When using the library from programs that change the ABI to |
1963 | use 64 bit file offsets the programs will fail. In that case you have to |
1977 | use 64 bit file offsets the programs will fail. In that case you have to |
1964 | compile libev with the same flags to get binary compatibility. This is |
1978 | compile libev with the same flags to get binary compatibility. This is |
1965 | obviously the case with any flags that change the ABI, but the problem is |
1979 | obviously the case with any flags that change the ABI, but the problem is |
1966 | most noticeably disabled with ev_stat and large file support. |
1980 | most noticeably displayed with ev_stat and large file support. |
1967 | |
1981 | |
1968 | The solution for this is to lobby your distribution maker to make large |
1982 | The solution for this is to lobby your distribution maker to make large |
1969 | file interfaces available by default (as e.g. FreeBSD does) and not |
1983 | file interfaces available by default (as e.g. FreeBSD does) and not |
1970 | optional. Libev cannot simply switch on large file support because it has |
1984 | optional. Libev cannot simply switch on large file support because it has |
1971 | to exchange stat structures with application programs compiled using the |
1985 | to exchange stat structures with application programs compiled using the |
1972 | default compilation environment. |
1986 | default compilation environment. |
1973 | |
1987 | |
1974 | =head3 Inotify and Kqueue |
1988 | =head3 Inotify and Kqueue |
1975 | |
1989 | |
1976 | 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 |
1977 | 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 |
1978 | 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> |
1979 | change detection where possible. The inotify descriptor will be created |
1993 | watcher is being started. |
1980 | lazily when the first C<ev_stat> watcher is being started. |
|
|
1981 | |
1994 | |
1982 | 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 |
1983 | 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 |
1984 | 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 |
1985 | 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, |
1986 | 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. |
1987 | |
2003 | |
1988 | 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 |
1989 | implement this functionality, due to the requirement of having a file |
2005 | implement this functionality, due to the requirement of having a file |
1990 | 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 |
1991 | etc. is difficult. |
2007 | etc. is difficult. |
1992 | |
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 suually 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. |
|
|
2026 | |
1993 | =head3 The special problem of stat time resolution |
2027 | =head3 The special problem of stat time resolution |
1994 | |
2028 | |
1995 | The C<stat ()> system call only supports full-second resolution portably, and |
2029 | The C<stat ()> system call only supports full-second resolution portably, |
1996 | even on systems where the resolution is higher, most file systems still |
2030 | and even on systems where the resolution is higher, most file systems |
1997 | only support whole seconds. |
2031 | still only support whole seconds. |
1998 | |
2032 | |
1999 | That means that, if the time is the only thing that changes, you can |
2033 | That means that, if the time is the only thing that changes, you can |
2000 | easily miss updates: on the first update, C<ev_stat> detects a change and |
2034 | easily miss updates: on the first update, C<ev_stat> detects a change and |
2001 | calls your callback, which does something. When there is another update |
2035 | calls your callback, which does something. When there is another update |
2002 | within the same second, C<ev_stat> will be unable to detect unless the |
2036 | within the same second, C<ev_stat> will be unable to detect unless the |
… | |
… | |
2641 | =over 4 |
2675 | =over 4 |
2642 | |
2676 | |
2643 | =item ev_async_init (ev_async *, callback) |
2677 | =item ev_async_init (ev_async *, callback) |
2644 | |
2678 | |
2645 | Initialises and configures the async watcher - it has no parameters of any |
2679 | Initialises and configures the async watcher - it has no parameters of any |
2646 | kind. There is a C<ev_asynd_set> macro, but using it is utterly pointless, |
2680 | kind. There is a C<ev_async_set> macro, but using it is utterly pointless, |
2647 | trust me. |
2681 | trust me. |
2648 | |
2682 | |
2649 | =item ev_async_send (loop, ev_async *) |
2683 | =item ev_async_send (loop, ev_async *) |
2650 | |
2684 | |
2651 | Sends/signals/activates the given C<ev_async> watcher, that is, feeds |
2685 | Sends/signals/activates the given C<ev_async> watcher, that is, feeds |
… | |
… | |
2965 | Tony Arcieri has written a ruby extension that offers access to a subset |
2999 | Tony Arcieri has written a ruby extension that offers access to a subset |
2966 | of the libev API and adds file handle abstractions, asynchronous DNS and |
3000 | of the libev API and adds file handle abstractions, asynchronous DNS and |
2967 | more on top of it. It can be found via gem servers. Its homepage is at |
3001 | more on top of it. It can be found via gem servers. Its homepage is at |
2968 | L<http://rev.rubyforge.org/>. |
3002 | L<http://rev.rubyforge.org/>. |
2969 | |
3003 | |
|
|
3004 | Roger Pack reports that using the link order C<-lws2_32 -lmsvcrt-ruby-190> |
|
|
3005 | makes rev work even on mingw. |
|
|
3006 | |
2970 | =item D |
3007 | =item D |
2971 | |
3008 | |
2972 | Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to |
3009 | Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to |
2973 | be found at L<http://proj.llucax.com.ar/wiki/evd>. |
3010 | be found at L<http://proj.llucax.com.ar/wiki/evd>. |
2974 | |
3011 | |
… | |
… | |
3084 | |
3121 | |
3085 | #define EV_STANDALONE 1 |
3122 | #define EV_STANDALONE 1 |
3086 | #include "ev.h" |
3123 | #include "ev.h" |
3087 | |
3124 | |
3088 | Both header files and implementation files can be compiled with a C++ |
3125 | Both header files and implementation files can be compiled with a C++ |
3089 | compiler (at least, thats a stated goal, and breakage will be treated |
3126 | compiler (at least, that's a stated goal, and breakage will be treated |
3090 | as a bug). |
3127 | as a bug). |
3091 | |
3128 | |
3092 | You need the following files in your source tree, or in a directory |
3129 | You need the following files in your source tree, or in a directory |
3093 | in your include path (e.g. in libev/ when using -Ilibev): |
3130 | in your include path (e.g. in libev/ when using -Ilibev): |
3094 | |
3131 | |
… | |
… | |
3150 | keeps libev from including F<config.h>, and it also defines dummy |
3187 | keeps libev from including F<config.h>, and it also defines dummy |
3151 | implementations for some libevent functions (such as logging, which is not |
3188 | implementations for some libevent functions (such as logging, which is not |
3152 | supported). It will also not define any of the structs usually found in |
3189 | supported). It will also not define any of the structs usually found in |
3153 | F<event.h> that are not directly supported by the libev core alone. |
3190 | F<event.h> that are not directly supported by the libev core alone. |
3154 | |
3191 | |
|
|
3192 | In stanbdalone mode, libev will still try to automatically deduce the |
|
|
3193 | configuration, but has to be more conservative. |
|
|
3194 | |
3155 | =item EV_USE_MONOTONIC |
3195 | =item EV_USE_MONOTONIC |
3156 | |
3196 | |
3157 | If defined to be C<1>, libev will try to detect the availability of the |
3197 | If defined to be C<1>, libev will try to detect the availability of the |
3158 | monotonic clock option at both compile time and runtime. Otherwise no use |
3198 | monotonic clock option at both compile time and runtime. Otherwise no |
3159 | of the monotonic clock option will be attempted. If you enable this, you |
3199 | use of the monotonic clock option will be attempted. If you enable this, |
3160 | usually have to link against librt or something similar. Enabling it when |
3200 | you usually have to link against librt or something similar. Enabling it |
3161 | the functionality isn't available is safe, though, although you have |
3201 | when the functionality isn't available is safe, though, although you have |
3162 | to make sure you link against any libraries where the C<clock_gettime> |
3202 | to make sure you link against any libraries where the C<clock_gettime> |
3163 | function is hiding in (often F<-lrt>). |
3203 | function is hiding in (often F<-lrt>). See also C<EV_USE_CLOCK_SYSCALL>. |
3164 | |
3204 | |
3165 | =item EV_USE_REALTIME |
3205 | =item EV_USE_REALTIME |
3166 | |
3206 | |
3167 | If defined to be C<1>, libev will try to detect the availability of the |
3207 | If defined to be C<1>, libev will try to detect the availability of the |
3168 | real-time clock option at compile time (and assume its availability at |
3208 | real-time clock option at compile time (and assume its availability at |
3169 | runtime if successful). Otherwise no use of the real-time clock option will |
3209 | runtime if successful). Otherwise no use of the real-time clock option will |
3170 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
3210 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
3171 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
3211 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
3172 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
3212 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
3173 | |
3213 | |
|
|
3214 | =item EV_USE_CLOCK_SYSCALL |
|
|
3215 | |
|
|
3216 | If defined to be C<1>, libev will try to use a direct syscall instead |
|
|
3217 | of calling the system-provided C<clock_gettime> function. This option |
|
|
3218 | exists because on GNU/Linux, C<clock_gettime> is in C<librt>, but C<librt> |
|
|
3219 | unconditionally pulls in C<libpthread>, slowing down single-threaded |
|
|
3220 | programs needlessly. Using a direct syscall is slightly slower (in |
|
|
3221 | theory), because no optimised vdso implementation can be used, but avoids |
|
|
3222 | the pthread dependency. Defaults to C<1> on GNU/Linux with glibc 2.x or |
|
|
3223 | higher, as it simplifies linking (no need for C<-lrt>). |
|
|
3224 | |
3174 | =item EV_USE_NANOSLEEP |
3225 | =item EV_USE_NANOSLEEP |
3175 | |
3226 | |
3176 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
3227 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
3177 | and will use it for delays. Otherwise it will use C<select ()>. |
3228 | and will use it for delays. Otherwise it will use C<select ()>. |
3178 | |
3229 | |
… | |
… | |
3193 | |
3244 | |
3194 | =item EV_SELECT_USE_FD_SET |
3245 | =item EV_SELECT_USE_FD_SET |
3195 | |
3246 | |
3196 | If defined to C<1>, then the select backend will use the system C<fd_set> |
3247 | If defined to C<1>, then the select backend will use the system C<fd_set> |
3197 | structure. This is useful if libev doesn't compile due to a missing |
3248 | structure. This is useful if libev doesn't compile due to a missing |
3198 | C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout on |
3249 | C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout |
3199 | exotic systems. This usually limits the range of file descriptors to some |
3250 | on exotic systems. This usually limits the range of file descriptors to |
3200 | low limit such as 1024 or might have other limitations (winsocket only |
3251 | some low limit such as 1024 or might have other limitations (winsocket |
3201 | allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might |
3252 | only allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, |
3202 | influence the size of the C<fd_set> used. |
3253 | configures the maximum size of the C<fd_set>. |
3203 | |
3254 | |
3204 | =item EV_SELECT_IS_WINSOCKET |
3255 | =item EV_SELECT_IS_WINSOCKET |
3205 | |
3256 | |
3206 | When defined to C<1>, the select backend will assume that |
3257 | When defined to C<1>, the select backend will assume that |
3207 | select/socket/connect etc. don't understand file descriptors but |
3258 | select/socket/connect etc. don't understand file descriptors but |
… | |
… | |
3566 | loop, as long as you don't confuse yourself). The only exception is that |
3617 | loop, as long as you don't confuse yourself). The only exception is that |
3567 | you must not do this from C<ev_periodic> reschedule callbacks. |
3618 | you must not do this from C<ev_periodic> reschedule callbacks. |
3568 | |
3619 | |
3569 | Care has been taken to ensure that libev does not keep local state inside |
3620 | Care has been taken to ensure that libev does not keep local state inside |
3570 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
3621 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
3571 | they do not clal any callbacks. |
3622 | they do not call any callbacks. |
3572 | |
3623 | |
3573 | =head2 COMPILER WARNINGS |
3624 | =head2 COMPILER WARNINGS |
3574 | |
3625 | |
3575 | Depending on your compiler and compiler settings, you might get no or a |
3626 | Depending on your compiler and compiler settings, you might get no or a |
3576 | lot of warnings when compiling libev code. Some people are apparently |
3627 | lot of warnings when compiling libev code. Some people are apparently |
… | |
… | |
3610 | ==2274== definitely lost: 0 bytes in 0 blocks. |
3661 | ==2274== definitely lost: 0 bytes in 0 blocks. |
3611 | ==2274== possibly lost: 0 bytes in 0 blocks. |
3662 | ==2274== possibly lost: 0 bytes in 0 blocks. |
3612 | ==2274== still reachable: 256 bytes in 1 blocks. |
3663 | ==2274== still reachable: 256 bytes in 1 blocks. |
3613 | |
3664 | |
3614 | Then there is no memory leak, just as memory accounted to global variables |
3665 | Then there is no memory leak, just as memory accounted to global variables |
3615 | is not a memleak - the memory is still being refernced, and didn't leak. |
3666 | is not a memleak - the memory is still being referenced, and didn't leak. |
3616 | |
3667 | |
3617 | Similarly, under some circumstances, valgrind might report kernel bugs |
3668 | Similarly, under some circumstances, valgrind might report kernel bugs |
3618 | as if it were a bug in libev (e.g. in realloc or in the poll backend, |
3669 | as if it were a bug in libev (e.g. in realloc or in the poll backend, |
3619 | although an acceptable workaround has been found here), or it might be |
3670 | although an acceptable workaround has been found here), or it might be |
3620 | confused. |
3671 | confused. |
… | |
… | |
3858 | =back |
3909 | =back |
3859 | |
3910 | |
3860 | |
3911 | |
3861 | =head1 AUTHOR |
3912 | =head1 AUTHOR |
3862 | |
3913 | |
3863 | Marc Lehmann <libev@schmorp.de>. |
3914 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |
3864 | |
3915 | |