APR:PerlIO -- An APR Perl IO layer
# under mod_perl use APR::PerlIO (); sub handler { my $r = shift; die "This Perl build doesn't support PerlIO layers" unless APR::PerlIO::PERLIO_LAYERS_ARE_ENABLED; open my $fh, ">:APR", $filename, $r->pool or die $!; # work with $fh as normal $fh close $fh; return Apache::OK; } # outside mod_perl % perl -MApache2 -MAPR -MAPR::PerlIO -MAPR::Pool -le \ 'open my $fh, ">:APR", "/tmp/apr", APR::Pool->new or die "$!"; \ print $fh "whoah!"; \ close $fh;'
APR::PerlIO implements a Perl IO layer using APR's file manipulation as its internals.
APR::PerlIO
Why do you want to use this? Normally you shouldn't, probably it won't be faster than Perl's default layer. It's only useful when you need to manipulate a filehandle opened at the APR side, while using Perl.
Normally you won't call open() with APR layer attribute, but some mod_perl functions will return a filehandle which is internally hooked to APR. But you can use APR Perl IO directly if you want.
Before using the Perl IO APR layer one has to check whether it's supported by the used perl build.
die "This Perl build doesn't support PerlIO layers" unless APR::PerlIO::PERLIO_LAYERS_ARE_ENABLED;
Notice that loading APR::PerlIO won't fail when Perl IO layers aren't available since APR::PerlIO provides functionality for Perl builds not supporting Perl IO layers.
Perl Interface:
To use APR Perl IO to open a file the four arguments open() should be used. For example:
open my $fh, ">:APR", $filename, $r->pool or die $!;
where:
the second argument is the mode to open the file, constructed from two sections separated by the : character: the first section is the mode to open the file under (>, <, etc) and the second section must be a string APR.
:
the fourth argument must be an APR::Pool object.
APR::Pool
the rest of the arguments are the same as described by the open() manpage.
seek($fh, $offset, $whence);
If $offset is zero, seek() works normally.
$offset
seek()
However if $offset is non-zero and Perl has been compiled with with large files support (-Duselargefiles), whereas APR wasn't, this function will croak. This is because largefile size Off_t simply cannot fit into a non-largefile size apr_off_t.
-Duselargefiles
Off_t
apr_off_t
To solve the problem, rebuild Perl with -Uuselargefiles. Currently there is no way to force APR to build with large files support.
-Uuselargefiles
The C API provides functions to convert between Perl IO and APR Perl IO filehandles.
META: document these
The perliol(1), perlapio(1) and perl(1) manpages.
To install mod_perl, copy and paste the appropriate command in to your terminal.
cpanm
cpanm mod_perl
CPAN shell
perl -MCPAN -e shell install mod_perl
For more information on module installation, please visit the detailed CPAN module installation guide.