NAME

IO::Async::Loop::Select - use IO::Async with select(2)

SYNOPSIS

Normally an instance of this class would not be directly constructed by a program. It may however, be useful for runinng IO::Async with an existing program already using a select call.

            

              
              
use IO::Async::Loop::Select;
my $loop = IO::Async::Loop::Select->new;
$loop->add( ... );
while(1) {
   my ( $rvec, $wvec, $evec ) = ('') x 3;
   my $timeout;
   $loop->pre_select( \$rvec, \$wvec, \$evec, \$timeout );
   ...
   my $ret = select( $rvec, $wvec, $evec, $timeout );
   ...
   $loop->post_select( $rvec, $evec, $wvec );
}
            
          

DESCRIPTION

This subclass of IO::Async::Loop uses the select(2) syscall to perform read-ready and write-ready tests.

To integrate with an existing select-based event loop, a pair of methods pre_select and post_select can be called immediately before and after a select call. The relevant bits in the read-ready, write-ready and exceptional-state bitvectors are set by the pre_select method, and tested by the post_select method to pick which event callbacks to invoke.

CONSTRUCTOR

new

            

              
              
$loop = IO::Async::Loop::Select->new;
            
          

This function returns a new instance of a IO::Async::Loop::Select object. It takes no special arguments.

METHODS

pre_select

            

              
              
$loop->pre_select( \$readvec, \$writevec, \$exceptvec, \$timeout );
            
          

This method prepares the bitvectors for a select call, setting the bits that the Loop is interested in. It will also adjust the $timeout value if appropriate, reducing it if the next event timeout the Loop requires is sooner than the current value.

\$readvec

\$writevec

\$exceptvec

Scalar references to the reading, writing and exception bitvectors

\$timeout

Scalar reference to the timeout value

post_select

            

              
              
$loop->post_select( $readvec, $writevec, $exceptvec );
            
          

This method checks the returned bitvectors from a select call, and calls any of the callbacks that are appropriate.

$readvec

$writevec

$exceptvec

Scalars containing the read-ready, write-ready and exception bitvectors

loop_once

            

              
              
$count = $loop->loop_once( $timeout );
            
          

This method calls the pre_select method to prepare the bitvectors for a select syscall, performs it, then calls post_select to process the result. It returns the total number of callbacks invoked by the post_select method, or undef if the underlying select(2) syscall returned an error.

SEE ALSO

• IO::Select - OO interface to select system call

AUTHOR

Paul Evans <leonerd@leonerd.org.uk>