mirror of
https://git.FreeBSD.org/src.git
synced 2024-12-23 11:18:54 +00:00
79 lines
1.6 KiB
Perl
79 lines
1.6 KiB
Perl
package FileCache;
|
|
|
|
=head1 NAME
|
|
|
|
FileCache - keep more files open than the system permits
|
|
|
|
=head1 SYNOPSIS
|
|
|
|
cacheout $path;
|
|
print $path @data;
|
|
|
|
=head1 DESCRIPTION
|
|
|
|
The C<cacheout> function will make sure that there's a filehandle open
|
|
for writing available as the pathname you give it. It automatically
|
|
closes and re-opens files if you exceed your system file descriptor
|
|
maximum.
|
|
|
|
=head1 BUGS
|
|
|
|
F<sys/param.h> lies with its C<NOFILE> define on some systems,
|
|
so you may have to set $FileCache::cacheout_maxopen yourself.
|
|
|
|
=cut
|
|
|
|
require 5.000;
|
|
use Carp;
|
|
use Exporter;
|
|
|
|
@ISA = qw(Exporter);
|
|
@EXPORT = qw(
|
|
cacheout
|
|
);
|
|
|
|
# Open in their package.
|
|
|
|
sub cacheout_open {
|
|
my $pack = caller(1);
|
|
open(*{$pack . '::' . $_[0]}, $_[1]);
|
|
}
|
|
|
|
sub cacheout_close {
|
|
my $pack = caller(1);
|
|
close(*{$pack . '::' . $_[0]});
|
|
}
|
|
|
|
# But only this sub name is visible to them.
|
|
|
|
$cacheout_seq = 0;
|
|
$cacheout_numopen = 0;
|
|
|
|
sub cacheout {
|
|
($file) = @_;
|
|
unless (defined $cacheout_maxopen) {
|
|
if (open(PARAM,'/usr/include/sys/param.h')) {
|
|
local ($_, $.);
|
|
while (<PARAM>) {
|
|
$cacheout_maxopen = $1 - 4
|
|
if /^\s*#\s*define\s+NOFILE\s+(\d+)/;
|
|
}
|
|
close PARAM;
|
|
}
|
|
$cacheout_maxopen = 16 unless $cacheout_maxopen;
|
|
}
|
|
if (!$isopen{$file}) {
|
|
if (++$cacheout_numopen > $cacheout_maxopen) {
|
|
my @lru = sort {$isopen{$a} <=> $isopen{$b};} keys(%isopen);
|
|
splice(@lru, $cacheout_maxopen / 3);
|
|
$cacheout_numopen -= @lru;
|
|
for (@lru) { &cacheout_close($_); delete $isopen{$_}; }
|
|
}
|
|
cacheout_open($file, ($saw{$file}++ ? '>>' : '>') . $file)
|
|
or croak("Can't create $file: $!");
|
|
}
|
|
$isopen{$file} = ++$cacheout_seq;
|
|
}
|
|
|
|
1;
|