Paul Evans > IO-Async > IO::Async::Loop::Select

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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 ^

AUTHOR ^

Paul Evans <leonerd@leonerd.org.uk>

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