… | |
… | |
983 | In general you can register as many read and/or write event watchers per |
983 | In general you can register as many read and/or write event watchers per |
984 | fd as you want (as long as you don't confuse yourself). Setting all file |
984 | fd as you want (as long as you don't confuse yourself). Setting all file |
985 | descriptors to non-blocking mode is also usually a good idea (but not |
985 | descriptors to non-blocking mode is also usually a good idea (but not |
986 | required if you know what you are doing). |
986 | required if you know what you are doing). |
987 | |
987 | |
988 | You have to be careful with dup'ed file descriptors, though. Some backends |
|
|
989 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
|
|
990 | descriptors correctly if you register interest in two or more fds pointing |
|
|
991 | to the same underlying file/socket/etc. description (that is, they share |
|
|
992 | the same underlying "file open"). |
|
|
993 | |
|
|
994 | If you must do this, then force the use of a known-to-be-good backend |
988 | If you must do this, then force the use of a known-to-be-good backend |
995 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
989 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
996 | C<EVBACKEND_POLL>). |
990 | C<EVBACKEND_POLL>). |
997 | |
991 | |
998 | Another thing you have to watch out for is that it is quite easy to |
992 | Another thing you have to watch out for is that it is quite easy to |
… | |
… | |
1033 | |
1027 | |
1034 | =head3 The special problem of dup'ed file descriptors |
1028 | =head3 The special problem of dup'ed file descriptors |
1035 | |
1029 | |
1036 | Some backends (e.g. epoll), cannot register events for file descriptors, |
1030 | Some backends (e.g. epoll), cannot register events for file descriptors, |
1037 | but only events for the underlying file descriptions. That means when you |
1031 | but only events for the underlying file descriptions. That means when you |
1038 | have C<dup ()>'ed file descriptors and register events for them, only one |
1032 | have C<dup ()>'ed file descriptors or weirder constellations, and register |
1039 | file descriptor might actually receive events. |
1033 | events for them, only one file descriptor might actually receive events. |
1040 | |
1034 | |
1041 | There is no workaround possible except not registering events |
1035 | There is no workaround possible except not registering events |
1042 | for potentially C<dup ()>'ed file descriptors, or to resort to |
1036 | for potentially C<dup ()>'ed file descriptors, or to resort to |
1043 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1037 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1044 | |
1038 | |
… | |
… | |
1073 | =item int events [read-only] |
1067 | =item int events [read-only] |
1074 | |
1068 | |
1075 | The events being watched. |
1069 | The events being watched. |
1076 | |
1070 | |
1077 | =back |
1071 | =back |
|
|
1072 | |
|
|
1073 | =head3 Examples |
1078 | |
1074 | |
1079 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1075 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1080 | readable, but only once. Since it is likely line-buffered, you could |
1076 | readable, but only once. Since it is likely line-buffered, you could |
1081 | attempt to read a whole line in the callback. |
1077 | attempt to read a whole line in the callback. |
1082 | |
1078 | |
… | |
… | |
1180 | or C<ev_timer_again> is called and determines the next timeout (if any), |
1176 | or C<ev_timer_again> is called and determines the next timeout (if any), |
1181 | which is also when any modifications are taken into account. |
1177 | which is also when any modifications are taken into account. |
1182 | |
1178 | |
1183 | =back |
1179 | =back |
1184 | |
1180 | |
|
|
1181 | =head3 Examples |
|
|
1182 | |
1185 | Example: Create a timer that fires after 60 seconds. |
1183 | Example: Create a timer that fires after 60 seconds. |
1186 | |
1184 | |
1187 | static void |
1185 | static void |
1188 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1186 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1189 | { |
1187 | { |
… | |
… | |
1346 | When active, contains the absolute time that the watcher is supposed to |
1344 | When active, contains the absolute time that the watcher is supposed to |
1347 | trigger next. |
1345 | trigger next. |
1348 | |
1346 | |
1349 | =back |
1347 | =back |
1350 | |
1348 | |
|
|
1349 | =head3 Examples |
|
|
1350 | |
1351 | Example: Call a callback every hour, or, more precisely, whenever the |
1351 | Example: Call a callback every hour, or, more precisely, whenever the |
1352 | system clock is divisible by 3600. The callback invocation times have |
1352 | system clock is divisible by 3600. The callback invocation times have |
1353 | potentially a lot of jittering, but good long-term stability. |
1353 | potentially a lot of jittering, but good long-term stability. |
1354 | |
1354 | |
1355 | static void |
1355 | static void |
… | |
… | |
1446 | |
1446 | |
1447 | The process exit/trace status caused by C<rpid> (see your systems |
1447 | The process exit/trace status caused by C<rpid> (see your systems |
1448 | C<waitpid> and C<sys/wait.h> documentation for details). |
1448 | C<waitpid> and C<sys/wait.h> documentation for details). |
1449 | |
1449 | |
1450 | =back |
1450 | =back |
|
|
1451 | |
|
|
1452 | =head3 Examples |
1451 | |
1453 | |
1452 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
1454 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
1453 | |
1455 | |
1454 | static void |
1456 | static void |
1455 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1457 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
… | |
… | |
1664 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1666 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1665 | believe me. |
1667 | believe me. |
1666 | |
1668 | |
1667 | =back |
1669 | =back |
1668 | |
1670 | |
|
|
1671 | =head3 Examples |
|
|
1672 | |
1669 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1673 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1670 | callback, free it. Also, use no error checking, as usual. |
1674 | callback, free it. Also, use no error checking, as usual. |
1671 | |
1675 | |
1672 | static void |
1676 | static void |
1673 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1677 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
… | |
… | |
1744 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1748 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1745 | macros, but using them is utterly, utterly and completely pointless. |
1749 | macros, but using them is utterly, utterly and completely pointless. |
1746 | |
1750 | |
1747 | =back |
1751 | =back |
1748 | |
1752 | |
|
|
1753 | =head3 Examples |
|
|
1754 | |
1749 | There are a number of principal ways to embed other event loops or modules |
1755 | There are a number of principal ways to embed other event loops or modules |
1750 | into libev. Here are some ideas on how to include libadns into libev |
1756 | into libev. Here are some ideas on how to include libadns into libev |
1751 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
1757 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
1752 | use for an actually working example. Another Perl module named C<EV::Glib> |
1758 | use for an actually working example. Another Perl module named C<EV::Glib> |
1753 | embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV |
1759 | embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV |
… | |
… | |
1921 | portable one. |
1927 | portable one. |
1922 | |
1928 | |
1923 | So when you want to use this feature you will always have to be prepared |
1929 | So when you want to use this feature you will always have to be prepared |
1924 | that you cannot get an embeddable loop. The recommended way to get around |
1930 | that you cannot get an embeddable loop. The recommended way to get around |
1925 | this is to have a separate variables for your embeddable loop, try to |
1931 | this is to have a separate variables for your embeddable loop, try to |
1926 | create it, and if that fails, use the normal loop for everything: |
1932 | create it, and if that fails, use the normal loop for everything. |
|
|
1933 | |
|
|
1934 | =head3 Watcher-Specific Functions and Data Members |
|
|
1935 | |
|
|
1936 | =over 4 |
|
|
1937 | |
|
|
1938 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1939 | |
|
|
1940 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1941 | |
|
|
1942 | Configures the watcher to embed the given loop, which must be |
|
|
1943 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
1944 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1945 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1946 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
1947 | |
|
|
1948 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
1949 | |
|
|
1950 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1951 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
1952 | apropriate way for embedded loops. |
|
|
1953 | |
|
|
1954 | =item struct ev_loop *other [read-only] |
|
|
1955 | |
|
|
1956 | The embedded event loop. |
|
|
1957 | |
|
|
1958 | =back |
|
|
1959 | |
|
|
1960 | =head3 Examples |
|
|
1961 | |
|
|
1962 | Example: Try to get an embeddable event loop and embed it into the default |
|
|
1963 | event loop. If that is not possible, use the default loop. The default |
|
|
1964 | loop is stored in C<loop_hi>, while the mebeddable loop is stored in |
|
|
1965 | C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be |
|
|
1966 | used). |
1927 | |
1967 | |
1928 | struct ev_loop *loop_hi = ev_default_init (0); |
1968 | struct ev_loop *loop_hi = ev_default_init (0); |
1929 | struct ev_loop *loop_lo = 0; |
1969 | struct ev_loop *loop_lo = 0; |
1930 | struct ev_embed embed; |
1970 | struct ev_embed embed; |
1931 | |
1971 | |
… | |
… | |
1942 | ev_embed_start (loop_hi, &embed); |
1982 | ev_embed_start (loop_hi, &embed); |
1943 | } |
1983 | } |
1944 | else |
1984 | else |
1945 | loop_lo = loop_hi; |
1985 | loop_lo = loop_hi; |
1946 | |
1986 | |
1947 | =head3 Watcher-Specific Functions and Data Members |
1987 | Example: Check if kqueue is available but not recommended and create |
|
|
1988 | a kqueue backend for use with sockets (which usually work with any |
|
|
1989 | kqueue implementation). Store the kqueue/socket-only event loop in |
|
|
1990 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
1948 | |
1991 | |
1949 | =over 4 |
1992 | struct ev_loop *loop = ev_default_init (0); |
|
|
1993 | struct ev_loop *loop_socket = 0; |
|
|
1994 | struct ev_embed embed; |
|
|
1995 | |
|
|
1996 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
|
|
1997 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
|
|
1998 | { |
|
|
1999 | ev_embed_init (&embed, 0, loop_socket); |
|
|
2000 | ev_embed_start (loop, &embed); |
|
|
2001 | } |
1950 | |
2002 | |
1951 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
2003 | if (!loop_socket) |
|
|
2004 | loop_socket = loop; |
1952 | |
2005 | |
1953 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
2006 | // now use loop_socket for all sockets, and loop for everything else |
1954 | |
|
|
1955 | Configures the watcher to embed the given loop, which must be |
|
|
1956 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
1957 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1958 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1959 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
1960 | |
|
|
1961 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
1962 | |
|
|
1963 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1964 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
1965 | apropriate way for embedded loops. |
|
|
1966 | |
|
|
1967 | =item struct ev_loop *other [read-only] |
|
|
1968 | |
|
|
1969 | The embedded event loop. |
|
|
1970 | |
|
|
1971 | =back |
|
|
1972 | |
2007 | |
1973 | |
2008 | |
1974 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
2009 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
1975 | |
2010 | |
1976 | Fork watchers are called when a C<fork ()> was detected (usually because |
2011 | Fork watchers are called when a C<fork ()> was detected (usually because |
… | |
… | |
2455 | wants osf handles on win32 (this is the case when the select to |
2490 | wants osf handles on win32 (this is the case when the select to |
2456 | be used is the winsock select). This means that it will call |
2491 | be used is the winsock select). This means that it will call |
2457 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
2492 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
2458 | it is assumed that all these functions actually work on fds, even |
2493 | it is assumed that all these functions actually work on fds, even |
2459 | on win32. Should not be defined on non-win32 platforms. |
2494 | on win32. Should not be defined on non-win32 platforms. |
|
|
2495 | |
|
|
2496 | =item EV_FD_TO_WIN32_HANDLE |
|
|
2497 | |
|
|
2498 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
|
|
2499 | file descriptors to socket handles. When not defining this symbol (the |
|
|
2500 | default), then libev will call C<_get_osfhandle>, which is usually |
|
|
2501 | correct. In some cases, programs use their own file descriptor management, |
|
|
2502 | in which case they can provide this function to map fds to socket handles. |
2460 | |
2503 | |
2461 | =item EV_USE_POLL |
2504 | =item EV_USE_POLL |
2462 | |
2505 | |
2463 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
2506 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
2464 | backend. Otherwise it will be enabled on non-win32 platforms. It |
2507 | backend. Otherwise it will be enabled on non-win32 platforms. It |
… | |
… | |
2501 | be detected at runtime. |
2544 | be detected at runtime. |
2502 | |
2545 | |
2503 | =item EV_H |
2546 | =item EV_H |
2504 | |
2547 | |
2505 | The name of the F<ev.h> header file used to include it. The default if |
2548 | The name of the F<ev.h> header file used to include it. The default if |
2506 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
2549 | undefined is C<"ev.h"> in F<event.h> and F<ev.c>. This can be used to |
2507 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
2550 | virtually rename the F<ev.h> header file in case of conflicts. |
2508 | |
2551 | |
2509 | =item EV_CONFIG_H |
2552 | =item EV_CONFIG_H |
2510 | |
2553 | |
2511 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2554 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2512 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2555 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2513 | C<EV_H>, above. |
2556 | C<EV_H>, above. |
2514 | |
2557 | |
2515 | =item EV_EVENT_H |
2558 | =item EV_EVENT_H |
2516 | |
2559 | |
2517 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2560 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2518 | of how the F<event.h> header can be found. |
2561 | of how the F<event.h> header can be found, the dfeault is C<"event.h">. |
2519 | |
2562 | |
2520 | =item EV_PROTOTYPES |
2563 | =item EV_PROTOTYPES |
2521 | |
2564 | |
2522 | If defined to be C<0>, then F<ev.h> will not define any function |
2565 | If defined to be C<0>, then F<ev.h> will not define any function |
2523 | prototypes, but still define all the structs and other symbols. This is |
2566 | prototypes, but still define all the structs and other symbols. This is |
… | |
… | |
2737 | watchers becomes O(1) w.r.t. prioritiy handling. |
2780 | watchers becomes O(1) w.r.t. prioritiy handling. |
2738 | |
2781 | |
2739 | =back |
2782 | =back |
2740 | |
2783 | |
2741 | |
2784 | |
|
|
2785 | =head1 Win32 platform limitations and workarounds |
|
|
2786 | |
|
|
2787 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
|
|
2788 | requires, and its I/O model is fundamentally incompatible with the POSIX |
|
|
2789 | model. Libev still offers limited functionality on this platform in |
|
|
2790 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
|
|
2791 | descriptors. This only applies when using Win32 natively, not when using |
|
|
2792 | e.g. cygwin. |
|
|
2793 | |
|
|
2794 | There is no supported compilation method available on windows except |
|
|
2795 | embedding it into other applications. |
|
|
2796 | |
|
|
2797 | Due to the many, low, and arbitrary limits on the win32 platform and the |
|
|
2798 | abysmal performance of winsockets, using a large number of sockets is not |
|
|
2799 | recommended (and not reasonable). If your program needs to use more than |
|
|
2800 | a hundred or so sockets, then likely it needs to use a totally different |
|
|
2801 | implementation for windows, as libev offers the POSIX model, which cannot |
|
|
2802 | be implemented efficiently on windows (microsoft monopoly games). |
|
|
2803 | |
|
|
2804 | =over 4 |
|
|
2805 | |
|
|
2806 | =item The winsocket select function |
|
|
2807 | |
|
|
2808 | The winsocket C<select> function doesn't follow POSIX in that it requires |
|
|
2809 | socket I<handles> and not socket I<file descriptors>. This makes select |
|
|
2810 | very inefficient, and also requires a mapping from file descriptors |
|
|
2811 | to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>, |
|
|
2812 | C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor |
|
|
2813 | symbols for more info. |
|
|
2814 | |
|
|
2815 | The configuration for a "naked" win32 using the microsoft runtime |
|
|
2816 | libraries and raw winsocket select is: |
|
|
2817 | |
|
|
2818 | #define EV_USE_SELECT 1 |
|
|
2819 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
|
|
2820 | |
|
|
2821 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
|
|
2822 | complexity in the O(n²) range when using win32. |
|
|
2823 | |
|
|
2824 | =item Limited number of file descriptors |
|
|
2825 | |
|
|
2826 | Windows has numerous arbitrary (and low) limits on things. Early versions |
|
|
2827 | of winsocket's select only supported waiting for a max. of C<64> handles |
|
|
2828 | (probably owning to the fact that all windows kernels can only wait for |
|
|
2829 | C<64> things at the same time internally; microsoft recommends spawning a |
|
|
2830 | chain of threads and wait for 63 handles and the previous thread in each). |
|
|
2831 | |
|
|
2832 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
|
|
2833 | to some high number (e.g. C<2048>) before compiling the winsocket select |
|
|
2834 | call (which might be in libev or elsewhere, for example, perl does its own |
|
|
2835 | select emulation on windows). |
|
|
2836 | |
|
|
2837 | Another limit is the number of file descriptors in the microsoft runtime |
|
|
2838 | libraries, which by default is C<64> (there must be a hidden I<64> fetish |
|
|
2839 | or something like this inside microsoft). You can increase this by calling |
|
|
2840 | C<_setmaxstdio>, which can increase this limit to C<2048> (another |
|
|
2841 | arbitrary limit), but is broken in many versions of the microsoft runtime |
|
|
2842 | libraries. |
|
|
2843 | |
|
|
2844 | This might get you to about C<512> or C<2048> sockets (depending on |
|
|
2845 | windows version and/or the phase of the moon). To get more, you need to |
|
|
2846 | wrap all I/O functions and provide your own fd management, but the cost of |
|
|
2847 | calling select (O(n²)) will likely make this unworkable. |
|
|
2848 | |
|
|
2849 | =back |
|
|
2850 | |
|
|
2851 | |
2742 | =head1 AUTHOR |
2852 | =head1 AUTHOR |
2743 | |
2853 | |
2744 | Marc Lehmann <libev@schmorp.de>. |
2854 | Marc Lehmann <libev@schmorp.de>. |
2745 | |
2855 | |