… | |
… | |
569 | kernel is more efficient (which says nothing about its actual speed, of |
569 | kernel is more efficient (which says nothing about its actual speed, of |
570 | course). While stopping, setting and starting an I/O watcher does never |
570 | course). While stopping, setting and starting an I/O watcher does never |
571 | cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to |
571 | cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to |
572 | two event changes per incident. Support for C<fork ()> is very bad (you |
572 | two event changes per incident. Support for C<fork ()> is very bad (you |
573 | might have to leak fd's on fork, but it's more sane than epoll) and it |
573 | might have to leak fd's on fork, but it's more sane than epoll) and it |
574 | drops fds silently in similarly hard-to-detect cases |
574 | drops fds silently in similarly hard-to-detect cases. |
575 | |
575 | |
576 | This backend usually performs well under most conditions. |
576 | This backend usually performs well under most conditions. |
577 | |
577 | |
578 | While nominally embeddable in other event loops, this doesn't work |
578 | While nominally embeddable in other event loops, this doesn't work |
579 | everywhere, so you might need to test for this. And since it is broken |
579 | everywhere, so you might need to test for this. And since it is broken |
… | |
… | |
1393 | transition between them will be described in more detail - and while these |
1393 | transition between them will be described in more detail - and while these |
1394 | rules might look complicated, they usually do "the right thing". |
1394 | rules might look complicated, they usually do "the right thing". |
1395 | |
1395 | |
1396 | =over 4 |
1396 | =over 4 |
1397 | |
1397 | |
1398 | =item initialiased |
1398 | =item initialised |
1399 | |
1399 | |
1400 | Before a watcher can be registered with the event loop it has to be |
1400 | Before a watcher can be registered with the event loop it has to be |
1401 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
1401 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
1402 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
1402 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
1403 | |
1403 | |
… | |
… | |
2962 | |
2962 | |
2963 | Using an C<ev_check> watcher is almost enough: it will be called on the |
2963 | Using an C<ev_check> watcher is almost enough: it will be called on the |
2964 | next event loop iteration. However, that isn't as soon as possible - |
2964 | next event loop iteration. However, that isn't as soon as possible - |
2965 | without external events, your C<ev_check> watcher will not be invoked. |
2965 | without external events, your C<ev_check> watcher will not be invoked. |
2966 | |
2966 | |
2967 | |
|
|
2968 | This is where C<ev_idle> watchers come in handy - all you need is a |
2967 | This is where C<ev_idle> watchers come in handy - all you need is a |
2969 | single global idle watcher that is active as long as you have one active |
2968 | single global idle watcher that is active as long as you have one active |
2970 | C<ev_check> watcher. The C<ev_idle> watcher makes sure the event loop |
2969 | C<ev_check> watcher. The C<ev_idle> watcher makes sure the event loop |
2971 | will not sleep, and the C<ev_check> watcher makes sure a callback gets |
2970 | will not sleep, and the C<ev_check> watcher makes sure a callback gets |
2972 | invoked. Neither watcher alone can do that. |
2971 | invoked. Neither watcher alone can do that. |
… | |
… | |
3251 | |
3250 | |
3252 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
3251 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
3253 | |
3252 | |
3254 | Fork watchers are called when a C<fork ()> was detected (usually because |
3253 | Fork watchers are called when a C<fork ()> was detected (usually because |
3255 | whoever is a good citizen cared to tell libev about it by calling |
3254 | whoever is a good citizen cared to tell libev about it by calling |
3256 | C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the |
3255 | C<ev_loop_fork>). The invocation is done before the event loop blocks next |
3257 | event loop blocks next and before C<ev_check> watchers are being called, |
3256 | and before C<ev_check> watchers are being called, and only in the child |
3258 | and only in the child after the fork. If whoever good citizen calling |
3257 | after the fork. If whoever good citizen calling C<ev_default_fork> cheats |
3259 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
3258 | and calls it in the wrong process, the fork handlers will be invoked, too, |
3260 | handlers will be invoked, too, of course. |
3259 | of course. |
3261 | |
3260 | |
3262 | =head3 The special problem of life after fork - how is it possible? |
3261 | =head3 The special problem of life after fork - how is it possible? |
3263 | |
3262 | |
3264 | Most uses of C<fork()> consist of forking, then some simple calls to set |
3263 | Most uses of C<fork()> consist of forking, then some simple calls to set |
3265 | up/change the process environment, followed by a call to C<exec()>. This |
3264 | up/change the process environment, followed by a call to C<exec()>. This |
… | |
… | |
4625 | above. This reduces dependencies and makes libev faster. |
4624 | above. This reduces dependencies and makes libev faster. |
4626 | |
4625 | |
4627 | =item EV_ATOMIC_T |
4626 | =item EV_ATOMIC_T |
4628 | |
4627 | |
4629 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
4628 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
4630 | access is atomic and serialised with respect to other threads or signal |
4629 | access is atomic with respect to other threads or signal contexts. No |
4631 | contexts. No such type is easily found in the C language, so you can |
4630 | such type is easily found in the C language, so you can provide your own |
4632 | provide your own type that you know is safe for your purposes. It is used |
4631 | type that you know is safe for your purposes. It is used both for signal |
4633 | both for signal handler "locking" as well as for signal and thread safety |
4632 | handler "locking" as well as for signal and thread safety in C<ev_async> |
4634 | in C<ev_async> watchers. |
4633 | watchers. |
4635 | |
4634 | |
4636 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
4635 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
4637 | (from F<signal.h>), which is usually good enough on most platforms, |
4636 | (from F<signal.h>), which is usually good enough on most platforms. |
4638 | although strictly speaking using a type that also implies a memory fence |
|
|
4639 | is required. |
|
|
4640 | |
4637 | |
4641 | =item EV_H (h) |
4638 | =item EV_H (h) |
4642 | |
4639 | |
4643 | The name of the F<ev.h> header file used to include it. The default if |
4640 | The name of the F<ev.h> header file used to include it. The default if |
4644 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
4641 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
… | |
… | |
5313 | thread" or will block signals process-wide, both behaviours would |
5310 | thread" or will block signals process-wide, both behaviours would |
5314 | be compatible with libev. Interaction between C<sigprocmask> and |
5311 | be compatible with libev. Interaction between C<sigprocmask> and |
5315 | C<pthread_sigmask> could complicate things, however. |
5312 | C<pthread_sigmask> could complicate things, however. |
5316 | |
5313 | |
5317 | The most portable way to handle signals is to block signals in all threads |
5314 | The most portable way to handle signals is to block signals in all threads |
5318 | except the initial one, and run the default loop in the initial thread as |
5315 | except the initial one, and run the signal handling loop in the initial |
5319 | well. |
5316 | thread as well. |
5320 | |
5317 | |
5321 | =item C<long> must be large enough for common memory allocation sizes |
5318 | =item C<long> must be large enough for common memory allocation sizes |
5322 | |
5319 | |
5323 | To improve portability and simplify its API, libev uses C<long> internally |
5320 | To improve portability and simplify its API, libev uses C<long> internally |
5324 | instead of C<size_t> when allocating its data structures. On non-POSIX |
5321 | instead of C<size_t> when allocating its data structures. On non-POSIX |