# IO::Poll.pm
#
# Copyright (c) 1997-8 Graham Barr <[email protected]>. All rights reserved.
# This program is free software; you can redistribute it and/or
# modify it under the same terms as Perl itself.

package IO::Poll;

use strict;
use IO::Handle;
use Exporter ();
our(@ISA, @EXPORT_OK, @EXPORT, $VERSION);

@ISA = qw(Exporter);
$VERSION = "0.09";

@EXPORT = qw( POLLIN
POLLOUT
POLLERR
POLLHUP
POLLNVAL
);

@EXPORT_OK = qw(
POLLPRI
POLLRDNORM
POLLWRNORM
POLLRDBAND
POLLWRBAND
POLLNORM
);

# [0] maps fd's to requested masks
# [1] maps fd's to returned masks
# [2] maps fd's to handles
sub new {
my $class = shift;

my $self = bless [{},{},{}], $class;

$self;
}

sub mask {
my $self = shift;
my $io = shift;
my $fd = fileno($io);
return unless defined $fd;
if (@_) {
my $mask = shift;
if($mask) {
$self->[0]{$fd}{$io} = $mask; # the error events are always returned
$self->[1]{$fd} = 0; # output mask
$self->[2]{$io} = $io; # remember handle
} else {
delete $self->[0]{$fd}{$io};
unless(%{$self->[0]{$fd}}) {
# We no longer have any handles for this FD
delete $self->[1]{$fd};
delete $self->[0]{$fd};
}
delete $self->[2]{$io};
}
}

return unless exists $self->[0]{$fd} and exists $self->[0]{$fd}{$io};
return $self->[0]{$fd}{$io};
}


sub poll {
my($self,$timeout) = @_;

$self->[1] = {};

my($fd,$mask,$iom);
my @poll = ();

while(($fd,$iom) = each %{$self->[0]}) {
$mask = 0;
$mask |= $_ for values(%$iom);
push(@poll,$fd => $mask);
}

my $ret = @poll ? _poll(defined($timeout) ? $timeout * 1000 : -1,@poll) : 0;

return $ret
unless $ret > 0;

while(@poll) {
my($fd,$got) = splice(@poll,0,2);
$self->[1]{$fd} = $got if $got;
}

return $ret;
}

sub events {
my $self = shift;
my $io = shift;
my $fd = fileno($io);
exists $self->[1]{$fd} and exists $self->[0]{$fd}{$io}
? $self->[1]{$fd} & ($self->[0]{$fd}{$io}|POLLHUP|POLLERR|POLLNVAL)
: 0;
}

sub remove {
my $self = shift;
my $io = shift;
$self->mask($io,0);
}

sub handles {
my $self = shift;
return values %{$self->[2]} unless @_;

my $events = shift || 0;
my($fd,$ev,$io,$mask);
my @handles = ();

while(($fd,$ev) = each %{$self->[1]}) {
while (($io,$mask) = each %{$self->[0]{$fd}}) {
$mask |= POLLHUP|POLLERR|POLLNVAL; # must allow these
push @handles,$self->[2]{$io} if ($ev & $mask) & $events;
}
}
return @handles;
}

1;

__END__

=head1 NAME

IO::Poll - Object interface to system poll call

=head1 SYNOPSIS

use IO::Poll qw(POLLRDNORM POLLWRNORM POLLIN POLLHUP);

$poll = IO::Poll->new();

$poll->mask($input_handle => POLLIN);
$poll->mask($output_handle => POLLOUT);

$poll->poll($timeout);

$ev = $poll->events($input);

=head1 DESCRIPTION

C<IO::Poll> is a simple interface to the system level poll routine.

=head1 METHODS

=over 4

=item mask ( IO [, EVENT_MASK ] )

If EVENT_MASK is given, then, if EVENT_MASK is non-zero, IO is added to the
list of file descriptors and the next call to poll will check for
any event specified in EVENT_MASK. If EVENT_MASK is zero then IO will be
removed from the list of file descriptors.

If EVENT_MASK is not given then the return value will be the current
event mask value for IO.

=item poll ( [ TIMEOUT ] )

Call the system level poll routine. If TIMEOUT is not specified then the
call will block. Returns the number of handles which had events
happen, or -1 on error.

=item events ( IO )

Returns the event mask which represents the events that happened on IO
during the last call to C<poll>.

=item remove ( IO )

Remove IO from the list of file descriptors for the next poll.

=item handles( [ EVENT_MASK ] )

Returns a list of handles. If EVENT_MASK is not given then a list of all
handles known will be returned. If EVENT_MASK is given then a list
of handles will be returned which had one of the events specified by
EVENT_MASK happen during the last call ti C<poll>

=back

=head1 SEE ALSO

L<poll(2)>, L<IO::Handle>, L<IO::Select>

=head1 AUTHOR

Graham Barr. Currently maintained by the Perl Porters. Please report all
bugs to <[email protected]>.

=head1 COPYRIGHT

Copyright (c) 1997-8 Graham Barr <[email protected]>. All rights reserved.
This program is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.

=cut