| 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 |