… | |
… | |
551 | usually a better approach for this kind of thing. |
551 | usually a better approach for this kind of thing. |
552 | |
552 | |
553 | Here are the gory details of what C<ev_loop> does: |
553 | Here are the gory details of what C<ev_loop> does: |
554 | |
554 | |
555 | - Before the first iteration, call any pending watchers. |
555 | - Before the first iteration, call any pending watchers. |
556 | * If there are no active watchers (reference count is zero), return. |
556 | * If EVFLAG_FORKCHECK was used, check for a fork. |
557 | - Queue all prepare watchers and then call all outstanding watchers. |
557 | - If a fork was detected, queue and call all fork watchers. |
|
|
558 | - Queue and call all prepare watchers. |
558 | - If we have been forked, recreate the kernel state. |
559 | - If we have been forked, recreate the kernel state. |
559 | - Update the kernel state with all outstanding changes. |
560 | - Update the kernel state with all outstanding changes. |
560 | - Update the "event loop time". |
561 | - Update the "event loop time". |
561 | - Calculate for how long to block. |
562 | - Calculate for how long to sleep or block, if at all |
|
|
563 | (active idle watchers, EVLOOP_NONBLOCK or not having |
|
|
564 | any active watchers at all will result in not sleeping). |
|
|
565 | - Sleep if the I/O and timer collect interval say so. |
562 | - Block the process, waiting for any events. |
566 | - Block the process, waiting for any events. |
563 | - Queue all outstanding I/O (fd) events. |
567 | - Queue all outstanding I/O (fd) events. |
564 | - Update the "event loop time" and do time jump handling. |
568 | - Update the "event loop time" and do time jump handling. |
565 | - Queue all outstanding timers. |
569 | - Queue all outstanding timers. |
566 | - Queue all outstanding periodics. |
570 | - Queue all outstanding periodics. |
567 | - If no events are pending now, queue all idle watchers. |
571 | - If no events are pending now, queue all idle watchers. |
568 | - Queue all check watchers. |
572 | - Queue all check watchers. |
569 | - Call all queued watchers in reverse order (i.e. check watchers first). |
573 | - Call all queued watchers in reverse order (i.e. check watchers first). |
570 | Signals and child watchers are implemented as I/O watchers, and will |
574 | Signals and child watchers are implemented as I/O watchers, and will |
571 | be handled here by queueing them when their watcher gets executed. |
575 | be handled here by queueing them when their watcher gets executed. |
572 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
576 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
573 | were used, return, otherwise continue with step *. |
577 | were used, or there are no active watchers, return, otherwise |
|
|
578 | continue with step *. |
574 | |
579 | |
575 | Example: Queue some jobs and then loop until no events are outsanding |
580 | Example: Queue some jobs and then loop until no events are outstanding |
576 | anymore. |
581 | anymore. |
577 | |
582 | |
578 | ... queue jobs here, make sure they register event watchers as long |
583 | ... queue jobs here, make sure they register event watchers as long |
579 | ... as they still have work to do (even an idle watcher will do..) |
584 | ... as they still have work to do (even an idle watcher will do..) |
580 | ev_loop (my_loop, 0); |
585 | ev_loop (my_loop, 0); |
… | |
… | |
584 | |
589 | |
585 | Can be used to make a call to C<ev_loop> return early (but only after it |
590 | Can be used to make a call to C<ev_loop> return early (but only after it |
586 | has processed all outstanding events). The C<how> argument must be either |
591 | has processed all outstanding events). The C<how> argument must be either |
587 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
592 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
588 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
593 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
|
|
594 | |
|
|
595 | This "unloop state" will be cleared when entering C<ev_loop> again. |
589 | |
596 | |
590 | =item ev_ref (loop) |
597 | =item ev_ref (loop) |
591 | |
598 | |
592 | =item ev_unref (loop) |
599 | =item ev_unref (loop) |
593 | |
600 | |
… | |
… | |
983 | In general you can register as many read and/or write event watchers per |
990 | 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 |
991 | 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 |
992 | descriptors to non-blocking mode is also usually a good idea (but not |
986 | required if you know what you are doing). |
993 | required if you know what you are doing). |
987 | |
994 | |
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 |
995 | 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 |
996 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
996 | C<EVBACKEND_POLL>). |
997 | C<EVBACKEND_POLL>). |
997 | |
998 | |
998 | Another thing you have to watch out for is that it is quite easy to |
999 | Another thing you have to watch out for is that it is quite easy to |
… | |
… | |
1033 | |
1034 | |
1034 | =head3 The special problem of dup'ed file descriptors |
1035 | =head3 The special problem of dup'ed file descriptors |
1035 | |
1036 | |
1036 | Some backends (e.g. epoll), cannot register events for file descriptors, |
1037 | Some backends (e.g. epoll), cannot register events for file descriptors, |
1037 | but only events for the underlying file descriptions. That means when you |
1038 | 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 |
1039 | have C<dup ()>'ed file descriptors or weirder constellations, and register |
1039 | file descriptor might actually receive events. |
1040 | events for them, only one file descriptor might actually receive events. |
1040 | |
1041 | |
1041 | There is no workaround possible except not registering events |
1042 | There is no workaround possible except not registering events |
1042 | for potentially C<dup ()>'ed file descriptors, or to resort to |
1043 | for potentially C<dup ()>'ed file descriptors, or to resort to |
1043 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1044 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1044 | |
1045 | |
… | |
… | |
1073 | =item int events [read-only] |
1074 | =item int events [read-only] |
1074 | |
1075 | |
1075 | The events being watched. |
1076 | The events being watched. |
1076 | |
1077 | |
1077 | =back |
1078 | =back |
|
|
1079 | |
|
|
1080 | =head3 Examples |
1078 | |
1081 | |
1079 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1082 | 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 |
1083 | readable, but only once. Since it is likely line-buffered, you could |
1081 | attempt to read a whole line in the callback. |
1084 | attempt to read a whole line in the callback. |
1082 | |
1085 | |
… | |
… | |
1180 | or C<ev_timer_again> is called and determines the next timeout (if any), |
1183 | 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. |
1184 | which is also when any modifications are taken into account. |
1182 | |
1185 | |
1183 | =back |
1186 | =back |
1184 | |
1187 | |
|
|
1188 | =head3 Examples |
|
|
1189 | |
1185 | Example: Create a timer that fires after 60 seconds. |
1190 | Example: Create a timer that fires after 60 seconds. |
1186 | |
1191 | |
1187 | static void |
1192 | static void |
1188 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1193 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1189 | { |
1194 | { |
… | |
… | |
1346 | When active, contains the absolute time that the watcher is supposed to |
1351 | When active, contains the absolute time that the watcher is supposed to |
1347 | trigger next. |
1352 | trigger next. |
1348 | |
1353 | |
1349 | =back |
1354 | =back |
1350 | |
1355 | |
|
|
1356 | =head3 Examples |
|
|
1357 | |
1351 | Example: Call a callback every hour, or, more precisely, whenever the |
1358 | Example: Call a callback every hour, or, more precisely, whenever the |
1352 | system clock is divisible by 3600. The callback invocation times have |
1359 | system clock is divisible by 3600. The callback invocation times have |
1353 | potentially a lot of jittering, but good long-term stability. |
1360 | potentially a lot of jittering, but good long-term stability. |
1354 | |
1361 | |
1355 | static void |
1362 | static void |
… | |
… | |
1446 | |
1453 | |
1447 | The process exit/trace status caused by C<rpid> (see your systems |
1454 | The process exit/trace status caused by C<rpid> (see your systems |
1448 | C<waitpid> and C<sys/wait.h> documentation for details). |
1455 | C<waitpid> and C<sys/wait.h> documentation for details). |
1449 | |
1456 | |
1450 | =back |
1457 | =back |
|
|
1458 | |
|
|
1459 | =head3 Examples |
1451 | |
1460 | |
1452 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
1461 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
1453 | |
1462 | |
1454 | static void |
1463 | static void |
1455 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1464 | 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, |
1673 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1665 | believe me. |
1674 | believe me. |
1666 | |
1675 | |
1667 | =back |
1676 | =back |
1668 | |
1677 | |
|
|
1678 | =head3 Examples |
|
|
1679 | |
1669 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1680 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1670 | callback, free it. Also, use no error checking, as usual. |
1681 | callback, free it. Also, use no error checking, as usual. |
1671 | |
1682 | |
1672 | static void |
1683 | static void |
1673 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1684 | 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> |
1755 | 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. |
1756 | macros, but using them is utterly, utterly and completely pointless. |
1746 | |
1757 | |
1747 | =back |
1758 | =back |
1748 | |
1759 | |
|
|
1760 | =head3 Examples |
|
|
1761 | |
1749 | There are a number of principal ways to embed other event loops or modules |
1762 | 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 |
1763 | 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 |
1764 | (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> |
1765 | 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 |
1766 | embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV |
… | |
… | |
1921 | portable one. |
1934 | portable one. |
1922 | |
1935 | |
1923 | So when you want to use this feature you will always have to be prepared |
1936 | 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 |
1937 | 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 |
1938 | 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: |
1939 | create it, and if that fails, use the normal loop for everything. |
|
|
1940 | |
|
|
1941 | =head3 Watcher-Specific Functions and Data Members |
|
|
1942 | |
|
|
1943 | =over 4 |
|
|
1944 | |
|
|
1945 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1946 | |
|
|
1947 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1948 | |
|
|
1949 | Configures the watcher to embed the given loop, which must be |
|
|
1950 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
1951 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1952 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1953 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
1954 | |
|
|
1955 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
1956 | |
|
|
1957 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1958 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
1959 | apropriate way for embedded loops. |
|
|
1960 | |
|
|
1961 | =item struct ev_loop *other [read-only] |
|
|
1962 | |
|
|
1963 | The embedded event loop. |
|
|
1964 | |
|
|
1965 | =back |
|
|
1966 | |
|
|
1967 | =head3 Examples |
|
|
1968 | |
|
|
1969 | Example: Try to get an embeddable event loop and embed it into the default |
|
|
1970 | event loop. If that is not possible, use the default loop. The default |
|
|
1971 | loop is stored in C<loop_hi>, while the mebeddable loop is stored in |
|
|
1972 | C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be |
|
|
1973 | used). |
1927 | |
1974 | |
1928 | struct ev_loop *loop_hi = ev_default_init (0); |
1975 | struct ev_loop *loop_hi = ev_default_init (0); |
1929 | struct ev_loop *loop_lo = 0; |
1976 | struct ev_loop *loop_lo = 0; |
1930 | struct ev_embed embed; |
1977 | struct ev_embed embed; |
1931 | |
1978 | |
… | |
… | |
1942 | ev_embed_start (loop_hi, &embed); |
1989 | ev_embed_start (loop_hi, &embed); |
1943 | } |
1990 | } |
1944 | else |
1991 | else |
1945 | loop_lo = loop_hi; |
1992 | loop_lo = loop_hi; |
1946 | |
1993 | |
1947 | =head3 Watcher-Specific Functions and Data Members |
1994 | Example: Check if kqueue is available but not recommended and create |
|
|
1995 | a kqueue backend for use with sockets (which usually work with any |
|
|
1996 | kqueue implementation). Store the kqueue/socket-only event loop in |
|
|
1997 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
1948 | |
1998 | |
1949 | =over 4 |
1999 | struct ev_loop *loop = ev_default_init (0); |
|
|
2000 | struct ev_loop *loop_socket = 0; |
|
|
2001 | struct ev_embed embed; |
|
|
2002 | |
|
|
2003 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
|
|
2004 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
|
|
2005 | { |
|
|
2006 | ev_embed_init (&embed, 0, loop_socket); |
|
|
2007 | ev_embed_start (loop, &embed); |
|
|
2008 | } |
1950 | |
2009 | |
1951 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
2010 | if (!loop_socket) |
|
|
2011 | loop_socket = loop; |
1952 | |
2012 | |
1953 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
2013 | // 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 | |
2014 | |
1973 | |
2015 | |
1974 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
2016 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
1975 | |
2017 | |
1976 | Fork watchers are called when a C<fork ()> was detected (usually because |
2018 | 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 |
2497 | 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 |
2498 | 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, |
2499 | 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 |
2500 | it is assumed that all these functions actually work on fds, even |
2459 | on win32. Should not be defined on non-win32 platforms. |
2501 | on win32. Should not be defined on non-win32 platforms. |
|
|
2502 | |
|
|
2503 | =item EV_FD_TO_WIN32_HANDLE |
|
|
2504 | |
|
|
2505 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
|
|
2506 | file descriptors to socket handles. When not defining this symbol (the |
|
|
2507 | default), then libev will call C<_get_osfhandle>, which is usually |
|
|
2508 | correct. In some cases, programs use their own file descriptor management, |
|
|
2509 | in which case they can provide this function to map fds to socket handles. |
2460 | |
2510 | |
2461 | =item EV_USE_POLL |
2511 | =item EV_USE_POLL |
2462 | |
2512 | |
2463 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
2513 | 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 |
2514 | backend. Otherwise it will be enabled on non-win32 platforms. It |
… | |
… | |
2501 | be detected at runtime. |
2551 | be detected at runtime. |
2502 | |
2552 | |
2503 | =item EV_H |
2553 | =item EV_H |
2504 | |
2554 | |
2505 | The name of the F<ev.h> header file used to include it. The default if |
2555 | 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 |
2556 | 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. |
2557 | virtually rename the F<ev.h> header file in case of conflicts. |
2508 | |
2558 | |
2509 | =item EV_CONFIG_H |
2559 | =item EV_CONFIG_H |
2510 | |
2560 | |
2511 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2561 | 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 |
2562 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2513 | C<EV_H>, above. |
2563 | C<EV_H>, above. |
2514 | |
2564 | |
2515 | =item EV_EVENT_H |
2565 | =item EV_EVENT_H |
2516 | |
2566 | |
2517 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2567 | 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. |
2568 | of how the F<event.h> header can be found, the dfeault is C<"event.h">. |
2519 | |
2569 | |
2520 | =item EV_PROTOTYPES |
2570 | =item EV_PROTOTYPES |
2521 | |
2571 | |
2522 | If defined to be C<0>, then F<ev.h> will not define any function |
2572 | 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 |
2573 | prototypes, but still define all the structs and other symbols. This is |
… | |
… | |
2737 | watchers becomes O(1) w.r.t. prioritiy handling. |
2787 | watchers becomes O(1) w.r.t. prioritiy handling. |
2738 | |
2788 | |
2739 | =back |
2789 | =back |
2740 | |
2790 | |
2741 | |
2791 | |
|
|
2792 | =head1 Win32 platform limitations and workarounds |
|
|
2793 | |
|
|
2794 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
|
|
2795 | requires, and its I/O model is fundamentally incompatible with the POSIX |
|
|
2796 | model. Libev still offers limited functionality on this platform in |
|
|
2797 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
|
|
2798 | descriptors. This only applies when using Win32 natively, not when using |
|
|
2799 | e.g. cygwin. |
|
|
2800 | |
|
|
2801 | There is no supported compilation method available on windows except |
|
|
2802 | embedding it into other applications. |
|
|
2803 | |
|
|
2804 | Due to the many, low, and arbitrary limits on the win32 platform and the |
|
|
2805 | abysmal performance of winsockets, using a large number of sockets is not |
|
|
2806 | recommended (and not reasonable). If your program needs to use more than |
|
|
2807 | a hundred or so sockets, then likely it needs to use a totally different |
|
|
2808 | implementation for windows, as libev offers the POSIX model, which cannot |
|
|
2809 | be implemented efficiently on windows (microsoft monopoly games). |
|
|
2810 | |
|
|
2811 | =over 4 |
|
|
2812 | |
|
|
2813 | =item The winsocket select function |
|
|
2814 | |
|
|
2815 | The winsocket C<select> function doesn't follow POSIX in that it requires |
|
|
2816 | socket I<handles> and not socket I<file descriptors>. This makes select |
|
|
2817 | very inefficient, and also requires a mapping from file descriptors |
|
|
2818 | to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>, |
|
|
2819 | C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor |
|
|
2820 | symbols for more info. |
|
|
2821 | |
|
|
2822 | The configuration for a "naked" win32 using the microsoft runtime |
|
|
2823 | libraries and raw winsocket select is: |
|
|
2824 | |
|
|
2825 | #define EV_USE_SELECT 1 |
|
|
2826 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
|
|
2827 | |
|
|
2828 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
|
|
2829 | complexity in the O(n²) range when using win32. |
|
|
2830 | |
|
|
2831 | =item Limited number of file descriptors |
|
|
2832 | |
|
|
2833 | Windows has numerous arbitrary (and low) limits on things. Early versions |
|
|
2834 | of winsocket's select only supported waiting for a max. of C<64> handles |
|
|
2835 | (probably owning to the fact that all windows kernels can only wait for |
|
|
2836 | C<64> things at the same time internally; microsoft recommends spawning a |
|
|
2837 | chain of threads and wait for 63 handles and the previous thread in each). |
|
|
2838 | |
|
|
2839 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
|
|
2840 | to some high number (e.g. C<2048>) before compiling the winsocket select |
|
|
2841 | call (which might be in libev or elsewhere, for example, perl does its own |
|
|
2842 | select emulation on windows). |
|
|
2843 | |
|
|
2844 | Another limit is the number of file descriptors in the microsoft runtime |
|
|
2845 | libraries, which by default is C<64> (there must be a hidden I<64> fetish |
|
|
2846 | or something like this inside microsoft). You can increase this by calling |
|
|
2847 | C<_setmaxstdio>, which can increase this limit to C<2048> (another |
|
|
2848 | arbitrary limit), but is broken in many versions of the microsoft runtime |
|
|
2849 | libraries. |
|
|
2850 | |
|
|
2851 | This might get you to about C<512> or C<2048> sockets (depending on |
|
|
2852 | windows version and/or the phase of the moon). To get more, you need to |
|
|
2853 | wrap all I/O functions and provide your own fd management, but the cost of |
|
|
2854 | calling select (O(n²)) will likely make this unworkable. |
|
|
2855 | |
|
|
2856 | =back |
|
|
2857 | |
|
|
2858 | |
2742 | =head1 AUTHOR |
2859 | =head1 AUTHOR |
2743 | |
2860 | |
2744 | Marc Lehmann <libev@schmorp.de>. |
2861 | Marc Lehmann <libev@schmorp.de>. |
2745 | |
2862 | |