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>