[ViewVC] Diff of: cvs/EV/EV.pm

Comparing EV/EV.pm (file contents):
Revision 1.44 by root, Thu Nov 22 04:52:23 2007 UTC vs.
Revision 1.53 by root, Sat Nov 24 16:57:30 2007 UTC

   EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block
 =head1 DESCRIPTION
 This module provides an interface to libev
-(L<http://software.schmorp.de/pkg/libev.html>).
+(L<http://software.schmorp.de/pkg/libev.html>). While the documentation
+below is comprehensive, one might also consult the documentation of libev
+itself (L<http://cvs.schmorp.de/libev/ev.html>) for more subtle details on
+watcher semantics or some discussion on the available backends, or how to
+force a specific backend with C<LIBEV_FLAGS>.
 =cut
 package EV;
 use strict;
 BEGIN {
-   our $VERSION = '1.2';
+   our $VERSION = '1.3';
    use XSLoader;
    XSLoader::load "EV", $VERSION;
 }
-@EV::Io::ISA       =
+@EV::IO::ISA       =
 @EV::Timer::ISA    =
 @EV::Periodic::ISA =
 @EV::Signal::ISA   =
 @EV::Idle::ISA     =
 @EV::Prepare::ISA  =
 innermost call to EV::loop return.
 When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
 fast as possible.
+=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
+This function rolls together an I/O and a timer watcher for a single
+one-shot event without the need for managing a watcher object.
+If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
+must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
+| EV::WRITE>, indicating the type of I/O event you want to wait for. If
+you do not want to wait for some I/O event, specify C<undef> for
+C<$fh_or_undef> and C<0> for C<$events>).
+If timeout is C<undef> or negative, then there will be no
+timeout. Otherwise a EV::timer with this value will be started.
+When an error occurs or either the timeout or I/O watcher triggers, then
+the callback will be called with the received event set (in general
+you can expect it to be a combination of C<EV:ERROR>, C<EV::READ>,
+C<EV::WRITE> and C<EV::TIMEOUT>).
+EV::once doesn't return anything: the watchers stay active till either
+of them triggers, then they will be stopped and freed, and the callback
+invoked.
 =back
 =head2 WATCHER
 A watcher is an object that gets created to record your interest in some
 watchers with higher priority will be invoked first. The valid range of
 priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
 -2). If the priority is outside this range it will automatically be
 normalised to the nearest valid priority.
-The default priority of any newly-created weatcher is 0.
+The default priority of any newly-created watcher is 0.
+Note that the priority semantics have not yet been fleshed out and are
+subject to almost certain change.
 =item $w->trigger ($revents)
 Call the callback *now* with the given event mask.
+=item $previous_state = $w->keepalive ($bool)
+Normally, C<EV::loop> will return when there are no active watchers
+(which is a "deadlock" because no progress can be made anymore). This is
+convinient because it allows you to start your watchers (and your jobs),
+call C<EV::loop> once and when it returns you know that all your jobs are
+finished (or they forgot to register some watchers for their task :).
+Sometimes, however, this gets in your way, for example when you the module
+that calls C<EV::loop> (usually the main program) is not the same module
+as a long-living watcher (for example a DNS client module written by
+somebody else even). Then you might want any outstanding requests to be
+handled, but you would not want to keep C<EV::loop> from returning just
+because you happen to have this long-running UDP port watcher.
+In this case you can clear the keepalive status, which means that even
+though your watcher is active, it won't keep C<EV::loop> from returning.
+The initial value for keepalive is true (enabled), and you cna change it
+any time.
+Example: Register an IO watcher for some UDP socket but do not keep the
+event loop from running just because of that watcher.
+   my $udp_socket = ...
+   my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
+   $udp_watcher->keepalive (0);
 =item $w = EV::io $fileno_or_fh, $eventmask, $callback
 =item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
 =item $w = EV::timer $after, $repeat, $callback
 =item $w = EV::timer_ns $after, $repeat, $callback
-Calls the callback after C<$after> seconds. If C<$repeat> is non-zero,
+Calls the callback after C<$after> seconds (which may be fractional). If
-the timer will be restarted (with the $repeat value as $after) after the
+C<$repeat> is non-zero, the timer will be restarted (with the $repeat
-callback returns.
+value as $after) after the callback returns.
 This means that the callback would be called roughly after C<$after>
 seconds, and then every C<$repeat> seconds. The timer does his best not
 to drift, but it will not invoke the timer more often then once per event
 loop iteration, and might drift in other cases. If that isn't acceptable,
       # do nothing unless active
       $dispatcher->{_event_queue_h}
          or return;
       # make the dispatcher handle any outstanding stuff
+      ... not shown
       # create an IO watcher for each and every socket
       @snmp_watcher = (
          (map { EV::io $_, EV::READ, sub { } }
              keys %{ $dispatcher->{_descriptors} }),
+         EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
+                     ? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
+                    0, sub { },
       );
-      # if there are any timeouts, also create a timer
-      push @snmp_watcher, EV::timer $event->[Net::SNMP::Dispatcher::_TIME] - EV::now, 0, sub { }
-         if $event->[Net::SNMP::Dispatcher::_ACTIVE];
    };
-The callbacks are irrelevant, the only purpose of those watchers is
+The callbacks are irrelevant (and are not even being called), the
-to wake up the process as soon as one of those events occurs (socket
+only purpose of those watchers is to wake up the process as soon as
-readable, or timer timed out). The corresponding EV::check watcher will then
+one of those events occurs (socket readable, or timer timed out). The
-clean up:
+corresponding EV::check watcher will then clean up:
    our $snmp_check = EV::check sub {
       # destroy all watchers
       @snmp_watcher = ();
       # make the dispatcher handle any new stuff
+      ... not shown
    };
 The callbacks of the created watchers will not be called as the watchers
 are destroyed before this cna happen (remember EV::check gets called
 first).
 =back
 =head1 THREADS
-Threads are not supported by this in any way. Perl pseudo-threads is evil
+Threads are not supported by this module in any way. Perl pseudo-threads
-stuff and must die.
+is evil stuff and must die. As soon as Perl gains real threads I will work
+on thread support for it.
+=head1 FORK
+Most of the "improved" event delivering mechanisms of modern operating
+systems have quite a few problems with fork(2) (to put it bluntly: it is
+not supported and usually destructive). Libev makes it possible to work
+around this by having a function that recreates the kernel state after
+fork in the child.
+On non-win32 platforms, this module requires the pthread_atfork
+functionality to do this automatically for you. This function is quite
+buggy on most BSDs, though, so YMMV. The overhead for this is quite
+negligible, because everything the function currently does is set a flag
+that is checked only when the event loop gets used the next time, so when
+you do fork but not use EV, the overhead is minimal.
+On win32, there is no notion of fork so all this doesn't apply, of course.
 =cut
 our $DIED = sub {
    warn "EV: error in callback (ignoring): $@";

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Comparing EV/EV.pm (file contents): Revision 1.44 by root, Thu Nov 22 04:52:23 2007 UTC vs. Revision 1.53 by root, Sat Nov 24 16:57:30 2007 UTC

Diff Legend

Comparing EV/EV.pm (file contents):
Revision 1.44 by root, Thu Nov 22 04:52:23 2007 UTC vs.
Revision 1.53 by root, Sat Nov 24 16:57:30 2007 UTC