src/Cache/CacheUtilities.pm

#____________________________________________________________________ 
# File: CacheUtilities.pm
#____________________________________________________________________ 
#  
# Author: Shaun Ashby <Shaun.Ashby@cern.ch>
# Update: 2003-10-30 11:51:58+0100
# Revision: $Id: CacheUtilities.pm,v 1.6.2.3 2006/09/11 11:19:58 sashby Exp $ 
#
# Copyright: 2003 (C) Shaun Ashby
#
#--------------------------------------------------------------------

=head1 NAME

Cache::CacheUtilities - Utilities for reading and writing of cache files.

=head1 SYNOPSIS

Reading:

         print "Reading cached data","\n",if ($ENV{SCRAM_DEBUG});
         $cacheobject=&Cache::CacheUtilities::read($cachename);

Writing:
   
         &Cache::CacheUtilities::write($cacheobject,$cachename);

=head1 DESCRIPTION

Functions for reading and writing of cache files. This uses Data::Dumper to
write out Perl data structures to files. For reading, the complete data structure
is read from the cache file and stored in a variable which is then evalled to
restore the original object.

=head1 METHODS

=over

=cut

package Cache::CacheUtilities;
require 5.004;

use IO::File;
use English;
use Exporter;

@ISA=qw(Exporter);

#
# Common functions for interacting with caches:
#

=item   C<read($cachefilename)>

Read the cache file $cachefilename and return a Perl object.

=cut

sub read()
   {
   my ($cachefilename) = @_;
   my $cachefh = IO::File->new($cachefilename, O_RDONLY)
      || die "Unable to read cached data file $cachefilename: ",$ERRNO,"\n";
   my @cacheitems = <$cachefh>;
   close $cachefh;

   # Copy the new cache object to self and return:
   $cache = eval "@cacheitems";
   die "Cache load error: ",$EVAL_ERROR,"\n", if ($EVAL_ERROR);
   return $cache;
   }

=item   C<write($cacheobject,$cachefilename)>

Dump the Perl object $cacheobject to a file $cachefilename.

=cut

sub write()
   {
   my ($cacheobject,$cachefilename) = @_;
   
   use Data::Dumper;
   use File::Copy;

   print "[ CacheUtilities::write() ] Writing cache ",$cachefilename,"\n", if ($ENV{SCRAM_DEBUG});
   
   # Move the cache file to make a backup:
   move($cachefilename,$cachefilename.".bak") if ( -r $cachefilename);   
   # Dump the cache to file:
   my $cachefh = IO::File->new($cachefilename, O_WRONLY|O_CREAT)
      or die "Couldn't write to $cachefilename: ",$ERRNO,"\n";

   # Name that should replace "VAR1" in the dumped
   # representation of the cache object:
   $Data::Dumper::Varname='cache';
   $Data::Dumper::Purity = 1;
   print $cachefh Dumper($cacheobject);
   close $cachefh;

   # Change the permissions to -rw-r--r--:
   my $filemode = 0644;
   chmod $filemode, $cachefilename;

   return;
   }

1;


=back

=head1 AUTHOR/MAINTAINER

Shaun Ashby

=cut
Revision:	1.7
Committed:	Mon Sep 11 13:48:33 2006 UTC (18 years, 7 months ago) by sashby
Content type:	text/plain
Branch:	MAIN
CVS Tags:	V1_0_3-p4, V1_0_3-p3, V1_0_3-p2, before110xmlBRmerge, V1_0_3-p1, V1_0_3
Branch point for:	v103_with_xml
Changes since 1.6:	+4 -4 lines
Log Message:	* empty log message *
#	User	Rev	Content
1	sashby	1.2	#____________________________________________________________________
2			# File: CacheUtilities.pm
3			#____________________________________________________________________
4			#
5			# Author: Shaun Ashby <Shaun.Ashby@cern.ch>
6			# Update: 2003-10-30 11:51:58+0100
7	sashby	1.7	# Revision: $Id: CacheUtilities.pm,v 1.6.2.3 2006/09/11 11:19:58 sashby Exp $
8	sashby	1.2	#
9			# Copyright: 2003 (C) Shaun Ashby
10			#
11			#--------------------------------------------------------------------
12	sashby	1.5
13			=head1 NAME
14
15			Cache::CacheUtilities - Utilities for reading and writing of cache files.
16
17			=head1 SYNOPSIS
18
19			Reading:
20
21			print "Reading cached data","\n",if ($ENV{SCRAM_DEBUG});
22			$cacheobject=&Cache::CacheUtilities::read($cachename);
23
24			Writing:
25
26			&Cache::CacheUtilities::write($cacheobject,$cachename);
27
28			=head1 DESCRIPTION
29
30			Functions for reading and writing of cache files. This uses Data::Dumper to
31			write out Perl data structures to files. For reading, the complete data structure
32			is read from the cache file and stored in a variable which is then evalled to
33			restore the original object.
34
35			=head1 METHODS
36
37			=over
38
39			=cut
40
41	sashby	1.2	package Cache::CacheUtilities;
42			require 5.004;
43
44			use IO::File;
45			use English;
46			use Exporter;
47
48			@ISA=qw(Exporter);
49
50			#
51			# Common functions for interacting with caches:
52			#
53
54	sashby	1.5	=item C<read($cachefilename)>
55
56			Read the cache file $cachefilename and return a Perl object.
57
58			=cut
59
60	sashby	1.2	sub read()
61			{
62			my ($cachefilename) = @_;
63			my $cachefh = IO::File->new($cachefilename, O_RDONLY)
64			\|\| die "Unable to read cached data file $cachefilename: ",$ERRNO,"\n";
65			my @cacheitems = <$cachefh>;
66			close $cachefh;
67
68			# Copy the new cache object to self and return:
69			$cache = eval "@cacheitems";
70			die "Cache load error: ",$EVAL_ERROR,"\n", if ($EVAL_ERROR);
71			return $cache;
72			}
73
74	sashby	1.6	=item C<write($cacheobject,$cachefilename)>
75	sashby	1.5
76			Dump the Perl object $cacheobject to a file $cachefilename.
77
78			=cut
79
80	sashby	1.2	sub write()
81			{
82			my ($cacheobject,$cachefilename) = @_;
83	sashby	1.7
84	sashby	1.2	use Data::Dumper;
85			use File::Copy;
86
87	sashby	1.7	print "[ CacheUtilities::write() ] Writing cache ",$cachefilename,"\n", if ($ENV{SCRAM_DEBUG});
88	sashby	1.3
89	sashby	1.7	# Move the cache file to make a backup:
90	sashby	1.2	move($cachefilename,$cachefilename.".bak") if ( -r $cachefilename);
91			# Dump the cache to file:
92			my $cachefh = IO::File->new($cachefilename, O_WRONLY\|O_CREAT)
93			or die "Couldn't write to $cachefilename: ",$ERRNO,"\n";
94
95			# Name that should replace "VAR1" in the dumped
96			# representation of the cache object:
97			$Data::Dumper::Varname='cache';
98			$Data::Dumper::Purity = 1;
99			print $cachefh Dumper($cacheobject);
100			close $cachefh;
101
102	sashby	1.3	# Change the permissions to -rw-r--r--:
103			my $filemode = 0644;
104			chmod $filemode, $cachefilename;
105
106	sashby	1.2	return;
107			}
108
109			1;
110	sashby	1.5
111
112			=back
113
114			=head1 AUTHOR/MAINTAINER
115
116			Shaun Ashby
117
118			=cut