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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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|
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Reading: |
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|
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print "Reading cached data","\n",if ($ENV{SCRAM_DEBUG}); |
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$cacheobject=&Cache::CacheUtilities::read($cachename); |
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|
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Writing: |
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|
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&Cache::CacheUtilities::write($cacheobject,$cachename); |
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|
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=head1 DESCRIPTION |
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|
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Functions for reading and writing of cache files. This uses Storable::store() to |
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write out Perl data structures to files. For reading, the complete data structure |
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is read from the cache file using Storable::retrieve() which returns a variable |
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containing the original object. |
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=head1 METHODS |
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|
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=over |
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|
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=cut |
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|
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package Cache::CacheUtilities; |
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require 5.004; |
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use English; |
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use Exporter; |
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use Storable; |
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@ISA=qw(Exporter); |
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# |
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# Common functions for interacting with caches: |
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# |
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=item C<read($cachefilename)> |
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Read the cache file $cachefilename and return a Perl object. |
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|
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=cut |
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|
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sub read() |
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{ |
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my ($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 $cachefh; |
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|
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# Copy the new cache object to self and return: |
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$cache = eval "@cacheitems"; |
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# Retrieve the cached object from the file: |
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$cache = eval "retrieve(\"$cachefilename\")"; |
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die "Cache load error: ",$EVAL_ERROR,"\n", if ($EVAL_ERROR); |
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return $cache; |
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} |
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|
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=item C<write($cacheobject,$cachefilename)> |
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|
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Dump the Perl object $cacheobject to a file $cachefilename. |
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|
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=cut |
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|
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sub write() |
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{ |
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my ($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"; |
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# Rename the cache file to make a backup 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 $cachefh; |
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|
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# Use the store method of the Storable package to write out the object to a file: |
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eval { |
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store($cacheobject,$cachefilename); |
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}; |
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die "Cache write error: ",$EVAL_ERROR,"\n", if ($EVAL_ERROR); |
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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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} |
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1; |
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|
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=back |
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|
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=head1 AUTHOR/MAINTAINER |
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|
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Shaun Ashby |
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|
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=cut |
