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Diffstat (limited to 'Master/tlpkg/tlperl/lib/FileCache.pm')
| -rwxr-xr-x | Master/tlpkg/tlperl/lib/FileCache.pm | 188 |
1 files changed, 188 insertions, 0 deletions
diff --git a/Master/tlpkg/tlperl/lib/FileCache.pm b/Master/tlpkg/tlperl/lib/FileCache.pm new file mode 100755 index 00000000000..09583b04afa --- /dev/null +++ b/Master/tlpkg/tlperl/lib/FileCache.pm @@ -0,0 +1,188 @@ +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 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 I<maxopen> yourself. + +=cut + +require 5.006; +use Carp; +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 { + return open(*{caller(1) . '::' . $_[1]}, $_[0], $_[1]) && $_[1]; +} + +# Close in their package. +sub cacheout_close { + # 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. +sub cacheout { + 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}) { + $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]; + } + return $ret; +} +1; |