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|
=pod
=head1 NAME
Time::Out - Easily timeout long running operations
=head1 SYNOPSIS
use Time::Out qw( timeout );
timeout $timeout => sub {
# your operation is implemented here and will be interrupted
# if it runs for more than $timeout seconds
};
if ( $@ ) {
# operation timed-out
}
=head1 DESCRIPTION
The C<Time::Out> module provides an easy interface to L<alarm(2)> based
timeouts. Nested timeouts are supported. The module exports the C<timeout()>
function by default. The function returns whatever the code placed inside the
subroutine reference returns:
use Time::Out qw( timeout );
my $result = timeout 5 => sub {
return 7;
};
# $result == 7
If C<Time::Out> sees that L<Time::HiRes> has been loaded, it will use that
C<alarm()> function (if available) instead of the default one, allowing float
timeout values to be used effectively:
use Time::HiRes qw();
use Time::Out qw( timeout );
timeout 3.1416 => sub {
# ...
};
=head1 CAVEATS
=over 2
=item Blocking I/O on MSWin32
L<alarm(2)> doesn't interrupt blocking I/O on MSWin32, so C<timeout()> won't do
that either.
=item @_
One drawback to using C<timeout()> is that it masks C<@_> in the affected
code. This happens because the affected code is actually wrapped inside
another subroutine that provides it's own C<@_>. You can get around this by
specifically passing your C<@_> (or whatever you want for that matter) to
C<timeout()> as such:
use Time::Out qw( timeout );
sub foo {
timeout 5, @_ => sub {
@_;
};
}
my @result = foo( 42, "Hello, World!" );
# @result == ( 42, "Hello, World!" );
=item Eval inside timeout
If the affected code has its own exception handling using L<Try::Tiny> for
example, the catch block has to be amended in a way so that it will rethrow an
exception, if it refers to a timeout:
use Scalar::Util qw( blessed );
use Time::Out qw( timeout );
use Try::Tiny qw( catch try );
timeout 5, sub {
try {
select( undef, undef, undef, 7 );
die "bad\n";
} catch {
# rethrow exception, if it refers to a timeout
die $_ if defined blessed $_ and $_->isa( 'Time::Out::Exception' );
# handle all other exceptions
}
};
=back
=head1 SEE ALSO
L<alarm(2)>, L<Sys::AlarmCall>
=head1 AUTHORS
Sven Willenbuecher, E<lt>sven.willenbuecher@gmx.deE<gt>
Patrick LeBoutillier, E<lt>patl@cpan.orgE<gt>
=head1 COPYRIGHT AND LICENSE
This software is copyright (c) 2005-2008 Patrick LeBoutillier, 2023 by Sven
Willenbuecher.
This is free software; you can redistribute it and/or modify it under the same
terms as the Perl 5 programming language system itself.
=cut
|
