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Comparing libev/ev.pod (file contents):
Revision 1.137 by root, Sun Mar 16 16:42:56 2008 UTC vs.
Revision 1.141 by root, Wed Apr 2 19:19:33 2008 UTC

… …
275flags. If that is troubling you, check C<ev_backend ()> afterwards). 275flags. If that is troubling you, check C<ev_backend ()> afterwards).
276 276
277If you don't know what event loop to use, use the one returned from this 277If you don't know what event loop to use, use the one returned from this
278function. 278function.
279 279
280Note that this function is I<not> thread-safe, so if you want to use it
281from multiple threads, you have to lock (note also that this is unlikely,
282as loops cannot bes hared easily between threads anyway).
283
280The default loop is the only loop that can handle C<ev_signal> and 284The default loop is the only loop that can handle C<ev_signal> and
281C<ev_child> watchers, and to do this, it always registers a handler 285C<ev_child> watchers, and to do this, it always registers a handler
282for C<SIGCHLD>. If this is a problem for your app you can either 286for C<SIGCHLD>. If this is a problem for your app you can either
283create a dynamic loop with C<ev_loop_new> that doesn't do that, or you 287create a dynamic loop with C<ev_loop_new> that doesn't do that, or you
284can simply overwrite the C<SIGCHLD> signal handler I<after> calling 288can simply overwrite the C<SIGCHLD> signal handler I<after> calling
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354For few fds, this backend is a bit little slower than poll and select, 358For few fds, this backend is a bit little slower than poll and select,
355but it scales phenomenally better. While poll and select usually scale 359but it scales phenomenally better. While poll and select usually scale
356like O(total_fds) where n is the total number of fds (or the highest fd), 360like O(total_fds) where n is the total number of fds (or the highest fd),
357epoll scales either O(1) or O(active_fds). The epoll design has a number 361epoll scales either O(1) or O(active_fds). The epoll design has a number
358of shortcomings, such as silently dropping events in some hard-to-detect 362of shortcomings, such as silently dropping events in some hard-to-detect
359cases and rewiring a syscall per fd change, no fork support and bad 363cases and requiring a syscall per fd change, no fork support and bad
360support for dup. 364support for dup.
361 365
362While stopping, setting and starting an I/O watcher in the same iteration 366While stopping, setting and starting an I/O watcher in the same iteration
363will result in some caching, there is still a syscall per such incident 367will result in some caching, there is still a syscall per such incident
364(because the fd could point to a different file description now), so its 368(because the fd could point to a different file description now), so its
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465 469
466Similar to C<ev_default_loop>, but always creates a new event loop that is 470Similar to C<ev_default_loop>, but always creates a new event loop that is
467always distinct from the default loop. Unlike the default loop, it cannot 471always distinct from the default loop. Unlike the default loop, it cannot
468handle signal and child watchers, and attempts to do so will be greeted by 472handle signal and child watchers, and attempts to do so will be greeted by
469undefined behaviour (or a failed assertion if assertions are enabled). 473undefined behaviour (or a failed assertion if assertions are enabled).
474
475Note that this function I<is> thread-safe, and the recommended way to use
476libev with threads is indeed to create one loop per thread, and using the
477default loop in the "main" or "initial" thread.
470 478
471Example: Try to create a event loop that uses epoll and nothing else. 479Example: Try to create a event loop that uses epoll and nothing else.
472 480
473 struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); 481 struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
474 if (!epoller) 482 if (!epoller)
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1085To support fork in your programs, you either have to call 1093To support fork in your programs, you either have to call
1086C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child, 1094C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child,
1087enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or 1095enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or
1088C<EVBACKEND_POLL>. 1096C<EVBACKEND_POLL>.
1089 1097
1098=head3 The special problem of SIGPIPE
1099
1100While not really specific to libev, it is easy to forget about SIGPIPE:
1101when reading from a pipe whose other end has been closed, your program
1102gets send a SIGPIPE, which, by default, aborts your program. For most
1103programs this is sensible behaviour, for daemons, this is usually
1104undesirable.
1105
1106So when you encounter spurious, unexplained daemon exits, make sure you
1107ignore SIGPIPE (and maybe make sure you log the exit status of your daemon
1108somewhere, as that would have given you a big clue).
1109
1090 1110
1091=head3 Watcher-Specific Functions 1111=head3 Watcher-Specific Functions
1092 1112
1093=over 4 1113=over 4
1094 1114
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2268 2288
2269This call incurs the overhead of a syscall only once per loop iteration, 2289This call incurs the overhead of a syscall only once per loop iteration,
2270so while the overhead might be noticable, it doesn't apply to repeated 2290so while the overhead might be noticable, it doesn't apply to repeated
2271calls to C<ev_async_send>. 2291calls to C<ev_async_send>.
2272 2292
2293=item bool = ev_async_pending (ev_async *)
2294
2295Returns a non-zero value when C<ev_async_send> has been called on the
2296watcher but the event has not yet been processed (or even noted) by the
2297event loop.
2298
2299C<ev_async_send> sets a flag in the watcher and wakes up the loop. When
2300the loop iterates next and checks for the watcher to have become active,
2301it will reset the flag again. C<ev_async_pending> can be used to very
2302quickly check wether invoking the loop might be a good idea.
2303
2304Not that this does I<not> check wether the watcher itself is pending, only
2305wether it has been requested to make this watcher pending.
2306
2273=back 2307=back
2274 2308
2275 2309
2276=head1 OTHER FUNCTIONS 2310=head1 OTHER FUNCTIONS
2277 2311

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