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io::async::loop::select

IO::Async::Loop::Select(3pm)				User Contributed Perl Documentation			      IO::Async::Loop::Select(3pm)

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

   $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

   $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

   $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

   $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

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

AUTHOR

       Paul Evans <leonerd@leonerd.org.uk>

perl v5.14.2							    2012-10-24					      IO::Async::Loop::Select(3pm)

Shell Programming and Scripting