IO::Select - OO interface to the select system call |
IO::Select - OO interface to the select system call
use IO::Select;
$s = IO::Select->new();
$s->add(\*STDIN); $s->add($some_handle);
@ready = $s->can_read($timeout);
@ready = IO::Select->new(@handles)->read(0);
The IO::Select
package implements an object approach to the system select
function call. It allows the user to see what IO handles, see the IO::Handle manpage,
are ready for reading, writing or have an error condition pending.
IO::Select
object. It is these values that
will be returned when an event occurs. IO::Select
keeps these values in a
cache which is indexed by the fileno
of the handle, so if more than one
handle with the same fileno
is specified then only the last one is cached.
Each handle can be an IO::Handle
object, an integer or an array
reference where the first element is an IO::Handle
or an integer.
fileno
of the handles. So the exact handles that were added
need not be passed, just handles that have an equivalent fileno
TIMEOUT
is
the maximum amount of time to wait before returning an empty list, in
seconds, possibly fractional. If TIMEOUT
is not given and any
handles are registered then the call will block.
can_read
except check for handles that can be written to.
can_read
except check for handles that have an exception
condition, for example pending out-of-band data.
can_
methods is called or the object is passed to
the select
static method.
bits()
select()
call.
select
is a static method, that is you call it with the package
name like new
. READ
, WRITE
and ERROR
are either undef
or IO::Select
objects. TIMEOUT
is optional and has the same
effect as for the core select call.
The result will be an array of 3 elements, each a reference to an array which will hold the handles that are ready for reading, writing and have error conditions respectively. Upon error an empty array is returned.
Here is a short example which shows how IO::Select
could be used
to write a server which communicates with several sockets while also
listening for more connections on a listen socket
use IO::Select; use IO::Socket;
$lsn = new IO::Socket::INET(Listen => 1, LocalPort => 8080); $sel = new IO::Select( $lsn );
while(@ready = $sel->can_read) { foreach $fh (@ready) { if($fh == $lsn) { # Create a new socket $new = $lsn->accept; $sel->add($new); } else { # Process socket
# Maybe we have finished with the socket $sel->remove($fh); $fh->close; } } }
Graham Barr. Currently maintained by the Perl Porters. Please report all bugs to <perl5-porters@perl.org>.
Copyright (c) 1997-8 Graham Barr <gbarr@pobox.com>. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
IO::Select - OO interface to the select system call |