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#____________________________________________________________________
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# File: CacheUtilities.pm
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#____________________________________________________________________
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#
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# Author: Shaun Ashby <Shaun.Ashby@cern.ch>
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# Update: 2003-10-30 11:51:58+0100
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# Revision: $Id: CacheUtilities.pm,v 1.6.2.3 2006/09/11 11:19:58 sashby Exp $
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#
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# Copyright: 2003 (C) Shaun Ashby
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#
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#--------------------------------------------------------------------
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=head1 NAME
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Cache::CacheUtilities - Utilities for reading and writing of cache files.
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=head1 SYNOPSIS
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Reading:
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print "Reading cached data","\n",if ($ENV{SCRAM_DEBUG});
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$cacheobject=&Cache::CacheUtilities::read($cachename);
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Writing:
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&Cache::CacheUtilities::write($cacheobject,$cachename);
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=head1 DESCRIPTION
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Functions for reading and writing of cache files. This uses Data::Dumper to
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write out Perl data structures to files. For reading, the complete data structure
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is read from the cache file and stored in a variable which is then evalled to
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restore the original object.
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=head1 METHODS
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=over
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=cut
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package Cache::CacheUtilities;
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require 5.004;
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use IO::File;
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use English;
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use Exporter;
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@ISA=qw(Exporter);
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#
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# Common functions for interacting with caches:
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#
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=item C<read($cachefilename)>
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Read the cache file $cachefilename and return a Perl object.
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=cut
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sub read()
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{
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my ($cachefilename) = @_;
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my $cachefh = IO::File->new($cachefilename, O_RDONLY)
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|| die "Unable to read cached data file $cachefilename: ",$ERRNO,"\n";
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my @cacheitems = <$cachefh>;
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close $cachefh;
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# Copy the new cache object to self and return:
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$cache = eval "@cacheitems";
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die "Cache load error: ",$EVAL_ERROR,"\n", if ($EVAL_ERROR);
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return $cache;
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}
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=item C<write($cacheobject,$cachefilename)>
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Dump the Perl object $cacheobject to a file $cachefilename.
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=cut
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sub write()
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{
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my ($cacheobject,$cachefilename) = @_;
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use Data::Dumper;
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use File::Copy;
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print "[ CacheUtilities::write() ] Writing cache ",$cachefilename,"\n", if ($ENV{SCRAM_DEBUG});
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# Move the cache file to make a backup:
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move($cachefilename,$cachefilename.".bak") if ( -r $cachefilename);
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# Dump the cache to file:
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my $cachefh = IO::File->new($cachefilename, O_WRONLY|O_CREAT)
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or die "Couldn't write to $cachefilename: ",$ERRNO,"\n";
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# Name that should replace "VAR1" in the dumped
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# representation of the cache object:
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$Data::Dumper::Varname='cache';
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$Data::Dumper::Purity = 1;
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print $cachefh Dumper($cacheobject);
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close $cachefh;
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# Change the permissions to -rw-r--r--:
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my $filemode = 0644;
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chmod $filemode, $cachefilename;
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return;
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}
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1;
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=back
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=head1 AUTHOR/MAINTAINER
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Shaun Ashby
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=cut
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