… | |
… | |
56 | This module provides an interface to libev |
56 | This module provides an interface to libev |
57 | (<http://software.schmorp.de/pkg/libev.html>). While the documentation |
57 | (<http://software.schmorp.de/pkg/libev.html>). While the documentation |
58 | below is comprehensive, one might also consult the documentation of |
58 | below is comprehensive, one might also consult the documentation of |
59 | libev itself (<http://cvs.schmorp.de/libev/ev.html>) for more subtle |
59 | libev itself (<http://cvs.schmorp.de/libev/ev.html>) for more subtle |
60 | details on watcher semantics or some discussion on the available |
60 | details on watcher semantics or some discussion on the available |
61 | backends, or how to force a specific backend with "LIBEV_FLAGS". |
61 | backends, or how to force a specific backend with "LIBEV_FLAGS", or just |
|
|
62 | about in any case because it has much more detailed information. |
62 | |
63 | |
63 | BASIC INTERFACE |
64 | BASIC INTERFACE |
64 | $EV::DIED |
65 | $EV::DIED |
65 | Must contain a reference to a function that is called when a |
66 | Must contain a reference to a function that is called when a |
66 | callback throws an exception (with $@ containing thr error). The |
67 | callback throws an exception (with $@ containing thr error). The |
… | |
… | |
139 | received events. |
140 | received events. |
140 | |
141 | |
141 | Each watcher type has its associated bit in revents, so you can use the |
142 | Each watcher type has its associated bit in revents, so you can use the |
142 | same callback for multiple watchers. The event mask is named after the |
143 | same callback for multiple watchers. The event mask is named after the |
143 | type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, |
144 | type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, |
144 | EV::periodic sets EV::PERIODIC and so on, with the exception of IO |
145 | EV::periodic sets EV::PERIODIC and so on, with the exception of I/O |
145 | events (which can set both EV::READ and EV::WRITE bits), and EV::timer |
146 | events (which can set both EV::READ and EV::WRITE bits), and EV::timer |
146 | (which uses EV::TIMEOUT). |
147 | (which uses EV::TIMEOUT). |
147 | |
148 | |
148 | In the rare case where one wants to create a watcher but not start it at |
149 | In the rare case where one wants to create a watcher but not start it at |
149 | the same time, each constructor has a variant with a trailing "_ns" in |
150 | the same time, each constructor has a variant with a trailing "_ns" in |
… | |
… | |
167 | stopped watchers). |
168 | stopped watchers). |
168 | |
169 | |
169 | $w->stop |
170 | $w->stop |
170 | Stop a watcher if it is active. Also clear any pending events |
171 | Stop a watcher if it is active. Also clear any pending events |
171 | (events that have been received but that didn't yet result in a |
172 | (events that have been received but that didn't yet result in a |
172 | callback invocation), regardless of wether the watcher was active or |
173 | callback invocation), regardless of whether the watcher was active |
173 | not. |
174 | or not. |
174 | |
175 | |
175 | $bool = $w->is_active |
176 | $bool = $w->is_active |
176 | Returns true if the watcher is active, false otherwise. |
177 | Returns true if the watcher is active, false otherwise. |
177 | |
178 | |
178 | $current_data = $w->data |
179 | $current_data = $w->data |
… | |
… | |
227 | returning. |
228 | returning. |
228 | |
229 | |
229 | The initial value for keepalive is true (enabled), and you cna |
230 | The initial value for keepalive is true (enabled), and you cna |
230 | change it any time. |
231 | change it any time. |
231 | |
232 | |
232 | Example: Register an IO watcher for some UDP socket but do not keep |
233 | Example: Register an I/O watcher for some UDP socket but do not keep |
233 | the event loop from running just because of that watcher. |
234 | the event loop from running just because of that watcher. |
234 | |
235 | |
235 | my $udp_socket = ... |
236 | my $udp_socket = ... |
236 | my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; |
237 | my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; |
237 | $udp_watcher->keepalive (0); |
238 | $udp_watcher->keepalive (0); |
238 | |
239 | |
239 | WATCHER TYPES |
240 | WATCHER TYPES |
240 | Each of the following subsections describes a single watcher type. |
241 | Each of the following subsections describes a single watcher type. |
241 | |
242 | |
242 | IO WATCHERS - is this file descriptor readable or writable? |
243 | I/O WATCHERS - is this file descriptor readable or writable? |
243 | $w = EV::io $fileno_or_fh, $eventmask, $callback |
244 | $w = EV::io $fileno_or_fh, $eventmask, $callback |
244 | $w = EV::io_ns $fileno_or_fh, $eventmask, $callback |
245 | $w = EV::io_ns $fileno_or_fh, $eventmask, $callback |
245 | As long as the returned watcher object is alive, call the $callback |
246 | As long as the returned watcher object is alive, call the $callback |
246 | when at least one of events specified in $eventmask occurs. |
247 | when at least one of events specified in $eventmask occurs. |
247 | |
248 | |
… | |
… | |
524 | Can be used to query the actual interval used. |
525 | Can be used to query the actual interval used. |
525 | |
526 | |
526 | IDLE WATCHERS - when you've got nothing better to do... |
527 | IDLE WATCHERS - when you've got nothing better to do... |
527 | $w = EV::idle $callback |
528 | $w = EV::idle $callback |
528 | $w = EV::idle_ns $callback |
529 | $w = EV::idle_ns $callback |
529 | Call the callback when there are no pending io, timer/periodic, |
530 | Call the callback when there are no other pending watchers of the |
530 | signal or child events, i.e. when the process is idle. |
531 | same or higher priority (excluding check, prepare and other idle |
|
|
532 | watchers of the same or lower priority, of course). They are called |
|
|
533 | idle watchers because when the watcher is the highest priority |
|
|
534 | pending event in the process, the process is considered to be idle |
|
|
535 | at that priority. |
|
|
536 | |
|
|
537 | If you want a watcher that is only ever called when *no* other |
|
|
538 | events are outstanding you have to set the priority to "EV::MINPRI". |
531 | |
539 | |
532 | The process will not block as long as any idle watchers are active, |
540 | The process will not block as long as any idle watchers are active, |
533 | and they will be called repeatedly until stopped. |
541 | and they will be called repeatedly until stopped. |
|
|
542 | |
|
|
543 | For example, if you have idle watchers at priority 0 and 1, and an |
|
|
544 | I/O watcher at priority 0, then the idle watcher at priority 1 and |
|
|
545 | the I/O watcher will always run when ready. Only when the idle |
|
|
546 | watcher at priority 1 is stopped and the I/O watcher at priority 0 |
|
|
547 | is not pending with the 0-priority idle watcher be invoked. |
534 | |
548 | |
535 | The "idle_ns" variant doesn't start (activate) the newly created |
549 | The "idle_ns" variant doesn't start (activate) the newly created |
536 | watcher. |
550 | watcher. |
537 | |
551 | |
538 | PREPARE WATCHERS - customise your event loop! |
552 | PREPARE WATCHERS - customise your event loop! |
… | |
… | |
567 | or return; |
581 | or return; |
568 | |
582 | |
569 | # make the dispatcher handle any outstanding stuff |
583 | # make the dispatcher handle any outstanding stuff |
570 | ... not shown |
584 | ... not shown |
571 | |
585 | |
572 | # create an IO watcher for each and every socket |
586 | # create an I/O watcher for each and every socket |
573 | @snmp_watcher = ( |
587 | @snmp_watcher = ( |
574 | (map { EV::io $_, EV::READ, sub { } } |
588 | (map { EV::io $_, EV::READ, sub { } } |
575 | keys %{ $dispatcher->{_descriptors} }), |
589 | keys %{ $dispatcher->{_descriptors} }), |
576 | |
590 | |
577 | EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE] |
591 | EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE] |
… | |
… | |
610 | Call the callback before the event loop is resumed in the child |
624 | Call the callback before the event loop is resumed in the child |
611 | process after a fork. |
625 | process after a fork. |
612 | |
626 | |
613 | The "fork_ns" variant doesn't start (activate) the newly created |
627 | The "fork_ns" variant doesn't start (activate) the newly created |
614 | watcher. |
628 | watcher. |
|
|
629 | |
|
|
630 | PERL SIGNALS |
|
|
631 | While Perl signal handling (%SIG) is not affected by EV, the behaviour |
|
|
632 | with EV is as the same as any other C library: Perl-signals will only be |
|
|
633 | handled when Perl runs, which means your signal handler might be invoked |
|
|
634 | only the next time an event callback is invoked. |
|
|
635 | |
|
|
636 | The solution is to use EV signal watchers (see "EV::signal"), which will |
|
|
637 | ensure proper operations with regards to other event watchers. |
|
|
638 | |
|
|
639 | If you cannot do this for whatever reason, you can also force a watcher |
|
|
640 | to be called on every event loop iteration by installing a "EV::check" |
|
|
641 | watcher: |
|
|
642 | |
|
|
643 | my $async_check = EV::check sub { }; |
|
|
644 | |
|
|
645 | This ensures that perl shortly gets into control for a short time, and |
|
|
646 | also ensures slower overall operation. |
615 | |
647 | |
616 | THREADS |
648 | THREADS |
617 | Threads are not supported by this module in any way. Perl pseudo-threads |
649 | Threads are not supported by this module in any way. Perl pseudo-threads |
618 | is evil stuff and must die. As soon as Perl gains real threads I will |
650 | is evil stuff and must die. As soon as Perl gains real threads I will |
619 | work on thread support for it. |
651 | work on thread support for it. |