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authorPerl 5 Porters <perl5-porters@africa.nicoh.com>1996-02-02 18:52:27 -0800
committerLarry Wall <lwall@sems.com>1996-02-02 18:52:27 -0800
commitc07a80fdfe3926b5eb0585b674aa5d1f57b32ade (patch)
tree6d56135571eb9ea6635748469bdaf72ad481247a /lib/FileCache.pm
parent91b7def858c29dac014df40946a128c06b3aa2ed (diff)
downloadperl-c07a80fdfe3926b5eb0585b674aa5d1f57b32ade.tar.gz
perl5.002beta3
[editor's note: no patch file was found for this release, so no fine-grained changes] I can't find the password for our ftp server, so I had to drop it into ftp://ftp.sems.com/pub/incoming/perl5.002b3.tar.gz, which is a drop directory you can't ls. The current plan is that Andy is gonna whack on this a little more, and then release a gamma in a few days when he's happy with it. So don't get carried away. This is now *late* beta. In other words, have less than the appropriate amount of fun. :-) Larry
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diff --git a/lib/FileCache.pm b/lib/FileCache.pm
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+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 $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;