table of contents
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¶
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>
2024-03-08 | perl v5.40.0 |