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>

perl v5.38.2                                       2024-02-04                       IO::Async::Loop::Select(3pm)