package FileCache;
+our $VERSION = '1.08';
+
=head1 NAME
FileCache - keep more files open than the system permits
=head1 SYNOPSIS
+ no strict 'refs';
+
+ use FileCache;
+ # or
+ use FileCache maxopen => 16;
+
+ cacheout $mode, $path;
+ # or
cacheout $path;
print $path @data;
+ $fh = cacheout $mode, $path;
+ # or
+ $fh = cacheout $path;
+ print $fh @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.
+for reading or writing available as the pathname you give it. It
+automatically closes and re-opens files if you exceed your system's
+maximum number of file descriptors, or the suggested maximum I<maxopen>.
+
+=over
+
+=item cacheout EXPR
+
+The 1-argument form of cacheout will open a file for writing (C<< '>' >>)
+on it's first use, and appending (C<<< '>>' >>>) thereafter.
+
+Returns EXPR on success for convenience. You may neglect the
+return value and manipulate EXPR as the filehandle directly if you prefer.
+
+=item cacheout MODE, EXPR
+
+The 2-argument form of cacheout will use the supplied mode for the initial
+and subsequent openings. Most valid modes for 3-argument C<open> are supported
+namely; C<< '>' >>, C<< '+>' >>, C<< '<' >>, C<< '<+' >>, C<<< '>>' >>>,
+C< '|-' > and C< '-|' >
+
+To pass supplemental arguments to a program opened with C< '|-' > or C< '-|' >
+append them to the command string as you would system EXPR.
+
+Returns EXPR on success for convenience. You may neglect the
+return value and manipulate EXPR as the filehandle directly if you prefer.
+
+=back
+
+=head1 CAVEATS
+
+While it is permissible to C<close> a FileCache managed file,
+do not do so if you are calling C<FileCache::cacheout> from a package other
+than which it was imported, or with another module which overrides C<close>.
+If you must, use C<FileCache::cacheout_close>.
+
+Although FileCache can be used with piped opens ('-|' or '|-') doing so is
+strongly discouraged. If FileCache finds it necessary to close and then reopen
+a pipe, the command at the far end of the pipe will be reexecuted - the results
+of performing IO on FileCache'd pipes is unlikely to be what you expect. The
+ability to use FileCache on pipes may be removed in a future release.
+
+FileCache does not store the current file offset if it finds it necessary to
+close a file. When the file is reopened, the offset will be as specified by the
+original C<open> file mode. This could be construed to be a bug.
+
+The module functionality relies on symbolic references, so things will break
+under 'use strict' unless 'no strict "refs"' is also specified.
=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.
+so you may have to set I<maxopen> yourself.
=cut
-require 5.000;
+require 5.006;
use Carp;
-use Exporter;
-
-@ISA = qw(Exporter);
-@EXPORT = qw(
- cacheout
-);
+use strict;
+no strict 'refs';
+
+# These are not C<my> for legacy reasons.
+# Previous versions requested the user set $cacheout_maxopen by hand.
+# Some authors fiddled with %saw to overcome the clobber on initial open.
+use vars qw(%saw $cacheout_maxopen);
+$cacheout_maxopen = 16;
+
+use base 'Exporter';
+our @EXPORT = qw[cacheout cacheout_close];
+
+
+my %isopen;
+my $cacheout_seq = 0;
+
+sub import {
+ my ($pkg,%args) = @_;
+
+ # Use Exporter. %args are for us, not Exporter.
+ # Make sure to up export_to_level, or we will import into ourselves,
+ # rather than our calling package;
+
+ __PACKAGE__->export_to_level(1);
+ Exporter::import( $pkg );
+
+ # Truth is okay here because setting maxopen to 0 would be bad
+ return $cacheout_maxopen = $args{maxopen} if $args{maxopen};
+
+ # XXX This code is crazy. Why is it a one element foreach loop?
+ # Why is it using $param both as a filename and filehandle?
+ foreach my $param ( '/usr/include/sys/param.h' ){
+ if (open($param, '<', $param)) {
+ local ($_, $.);
+ while (<$param>) {
+ if( /^\s*#\s*define\s+NOFILE\s+(\d+)/ ){
+ $cacheout_maxopen = $1 - 4;
+ close($param);
+ last;
+ }
+ }
+ close $param;
+ }
+ }
+ $cacheout_maxopen ||= 16;
+}
# Open in their package.
-
sub cacheout_open {
- my $pack = caller(1);
- open(*{$pack . '::' . $_[0]}, $_[1]);
+ return open(*{caller(1) . '::' . $_[1]}, $_[0], $_[1]) && $_[1];
}
+# Close in their package.
sub cacheout_close {
- my $pack = caller(1);
- close(*{$pack . '::' . $_[0]});
+ # Short-circuit in case the filehandle disappeared
+ my $pkg = caller($_[1]||0);
+ defined fileno(*{$pkg . '::' . $_[0]}) &&
+ CORE::close(*{$pkg . '::' . $_[0]});
+ delete $isopen{$_[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 $cacheout_maxopen;
+ my($mode, $file, $class, $ret, $ref, $narg);
+ croak "Not enough arguments for cacheout" unless $narg = scalar @_;
+ croak "Too many arguments for cacheout" if $narg > 2;
+
+ ($mode, $file) = @_;
+ ($file, $mode) = ($mode, $file) if $narg == 1;
+ croak "Invalid mode for cacheout" if $mode &&
+ ( $mode !~ /^\s*(?:>>|\+?>|\+?<|\|\-|)|\-\|\s*$/ );
+
+ # Mode changed?
+ if( $isopen{$file} && ($mode||'>') ne $isopen{$file}->[1] ){
+ &cacheout_close($file, 1);
}
- if (!$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: $!");
+
+ if( $isopen{$file}) {
+ $ret = $file;
+ $isopen{$file}->[0]++;
+ }
+ else{
+ if( scalar keys(%isopen) > $cacheout_maxopen -1 ) {
+ my @lru = sort{ $isopen{$a}->[0] <=> $isopen{$b}->[0] } keys(%isopen);
+ $cacheout_seq = 0;
+ $isopen{$_}->[0] = $cacheout_seq++ for
+ splice(@lru, int($cacheout_maxopen / 3)||$cacheout_maxopen);
+ &cacheout_close($_, 1) for @lru;
+ }
+
+ unless( $ref ){
+ $mode ||= $saw{$file} ? '>>' : ($saw{$file}=1, '>');
+ }
+ #XXX should we just return the value from cacheout_open, no croak?
+ $ret = cacheout_open($mode, $file) or croak("Can't create $file: $!");
+
+ $isopen{$file} = [++$cacheout_seq, $mode];
}
- $isopen{$file} = ++$cacheout_seq;
+ return $ret;
}
-
1;
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