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Comparing libev/ev.pod (file contents):
Revision 1.220 by root, Thu Nov 20 11:25:15 2008 UTC vs.
Revision 1.223 by root, Sun Dec 14 21:58:08 2008 UTC

460 460
461While nominally embeddable in other event loops, this doesn't work 461While nominally embeddable in other event loops, this doesn't work
462everywhere, so you might need to test for this. And since it is broken 462everywhere, so you might need to test for this. And since it is broken
463almost everywhere, you should only use it when you have a lot of sockets 463almost everywhere, you should only use it when you have a lot of sockets
464(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
465(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
466using it only for sockets. 466also broken on OS X)) and, did I mention it, using it only for sockets.
467 467
468This backend maps C<EV_READ> into an C<EVFILT_READ> kevent with 468This backend maps C<EV_READ> into an C<EVFILT_READ> kevent with
469C<NOTE_EOF>, and C<EV_WRITE> into an C<EVFILT_WRITE> kevent with 469C<NOTE_EOF>, and C<EV_WRITE> into an C<EVFILT_WRITE> kevent with
470C<NOTE_EOF>. 470C<NOTE_EOF>.
471 471
2012the process. The exception are C<ev_stat> watchers - those call C<stat 2012the process. The exception are C<ev_stat> watchers - those call C<stat
2013()>, which is a synchronous operation. 2013()>, which is a synchronous operation.
2014 2014
2015For local paths, this usually doesn't matter: unless the system is very 2015For local paths, this usually doesn't matter: unless the system is very
2016busy or the intervals between stat's are large, a stat call will be fast, 2016busy or the intervals between stat's are large, a stat call will be fast,
2017as the path data is suually in memory already (except when starting the 2017as the path data is usually in memory already (except when starting the
2018watcher). 2018watcher).
2019 2019
2020For networked file systems, calling C<stat ()> can block an indefinite 2020For networked file systems, calling C<stat ()> can block an indefinite
2021time due to network issues, and even under good conditions, a stat call 2021time due to network issues, and even under good conditions, a stat call
2022often takes multiple milliseconds. 2022often takes multiple milliseconds.
2428some fds have to be watched and handled very quickly (with low latency), 2428some fds have to be watched and handled very quickly (with low latency),
2429and even priorities and idle watchers might have too much overhead. In 2429and even priorities and idle watchers might have too much overhead. In
2430this case you would put all the high priority stuff in one loop and all 2430this case you would put all the high priority stuff in one loop and all
2431the rest in a second one, and embed the second one in the first. 2431the rest in a second one, and embed the second one in the first.
2432 2432
2433As long as the watcher is active, the callback will be invoked every time 2433As long as the watcher is active, the callback will be invoked every
2434there might be events pending in the embedded loop. The callback must then 2434time there might be events pending in the embedded loop. The callback
2435call C<ev_embed_sweep (mainloop, watcher)> to make a single sweep and invoke 2435must then call C<ev_embed_sweep (mainloop, watcher)> to make a single
2436their callbacks (you could also start an idle watcher to give the embedded 2436sweep and invoke their callbacks (the callback doesn't need to invoke the
2437loop strictly lower priority for example). You can also set the callback 2437C<ev_embed_sweep> function directly, it could also start an idle watcher
2438to C<0>, in which case the embed watcher will automatically execute the 2438to give the embedded loop strictly lower priority for example).
2439embedded loop sweep.
2440 2439
2441As long as the watcher is started it will automatically handle events. The 2440You can also set the callback to C<0>, in which case the embed watcher
2442callback will be invoked whenever some events have been handled. You can 2441will automatically execute the embedded loop sweep whenever necessary.
2443set the callback to C<0> to avoid having to specify one if you are not
2444interested in that.
2445 2442
2446Also, there have not currently been made special provisions for forking: 2443Fork detection will be handled transparently while the C<ev_embed> watcher
2447when you fork, you not only have to call C<ev_loop_fork> on both loops, 2444is active, i.e., the embedded loop will automatically be forked when the
2448but you will also have to stop and restart any C<ev_embed> watchers 2445embedding loop forks. In other cases, the user is responsible for calling
2449yourself - but you can use a fork watcher to handle this automatically, 2446C<ev_loop_fork> on the embedded loop.
2450and future versions of libev might do just that.
2451 2447
2452Unfortunately, not all backends are embeddable: only the ones returned by 2448Unfortunately, not all backends are embeddable: only the ones returned by
2453C<ev_embeddable_backends> are, which, unfortunately, does not include any 2449C<ev_embeddable_backends> are, which, unfortunately, does not include any
2454portable one. 2450portable one.
2455 2451
2891 2887
2892 myclass obj; 2888 myclass obj;
2893 ev::io iow; 2889 ev::io iow;
2894 iow.set <myclass, &myclass::io_cb> (&obj); 2890 iow.set <myclass, &myclass::io_cb> (&obj);
2895 2891
2892=item w->set (object *)
2893
2894This is an B<experimental> feature that might go away in a future version.
2895
2896This is a variation of a method callback - leaving out the method to call
2897will default the method to C<operator ()>, which makes it possible to use
2898functor objects without having to manually specify the C<operator ()> all
2899the time. Incidentally, you can then also leave out the template argument
2900list.
2901
2902The C<operator ()> method prototype must be C<void operator ()(watcher &w,
2903int revents)>.
2904
2905See the method-C<set> above for more details.
2906
2907Example: 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
2896=item w->set<function> (void *data = 0) 2922=item w->set<function> (void *data = 0)
2897 2923
2898Also sets a callback, but uses a static method or plain function as 2924Also sets a callback, but uses a static method or plain function as
2899callback. The optional C<data> argument will be stored in the watcher's 2925callback. The optional C<data> argument will be stored in the watcher's
2900C<data> member and is free for you to use. 2926C<data> member and is free for you to use.

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