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## $Id: Checksum.pm,v 1.4 2004/05/06 12:53:07 jonen Exp $ |
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## |
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## Copyright (c) 2002 Andreas Motl <andreas.motl@ilo.de> |
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## |
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## See COPYRIGHT section in pod text below for usage and distribution rights. |
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## |
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## ---------------------------------------------------------------------------------------- |
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## $Log: Checksum.pm,v $ |
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## Revision 1.4 2004/05/06 12:53:07 jonen |
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## + added use of File::RsycP::digest |
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## |
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## Revision 1.3 2003/05/13 08:19:00 joko |
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## switched to crc32 |
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## |
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## Revision 1.2 2003/02/11 09:53:07 joko |
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## + metadata-structure-change, fixed some code here |
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## |
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## Revision 1.1 2003/02/09 05:10:13 joko |
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## + initial commit |
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## |
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## ---------------------------------------------------------------------------------------- |
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=pod |
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=head1 Todo |
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|
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o Data::Transfer::Sync::Compare::Slot using Compare::Struct |
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o Load checksum algorithm on demand, do some negotiation |
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|
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=cut |
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package Data::Transfer::Sync::Compare::Checksum; |
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|
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use strict; |
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use warnings; |
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|
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use mixin::with qw( Data::Transfer::Sync ); |
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|
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use shortcuts qw( RUNNING_IN_HELL ); |
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use Data::Dumper; |
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# TODO: Load these appropriatly at runtime. |
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use Digest::MD5 qw( md5 md5_hex md5_base64 ); |
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use String::CRC32; |
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|
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# don't use File::RsyncP::Digest on win32 |
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# TODO: enhance here! (e.g. negotiate proper checksum-algorithm first, apply afterwards) |
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if (not RUNNING_IN_HELL()) { |
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eval "use File::RsyncP::Digest;"; |
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} |
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|
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# get logger instance |
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my $logger = Log::Dispatch::Config->instance; |
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|
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|
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# Maybe refactor to shortcuts::checksum? |
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sub _calcChecksum { |
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my $self = shift; |
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my $descent = shift; |
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my $specifier = shift; |
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# calculate checksum for current object |
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my $ident = $self->{node}->{$descent}->{ident}; |
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|
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# build dump of this node |
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my $payload = $self->{node}->{$descent}->{payload}; |
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#my $dump = $ident . "\n" . $item->quickdump(); |
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#my $dump = $ident . "\n" . Dumper($item); |
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my $dump = $ident . "\n" . $self->_dumpCompact($payload); |
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|
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# TODO: $logger->dump( ... ); |
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#$logger->debug( __PACKAGE__ . ": " . $dump ); |
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#$logger->dump( __PACKAGE__ . ": " . $dump ); |
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|
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# calculate checksum from dump |
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# 1. md5-based fingerprint, base64 encoded (from Digest::MD5) |
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#$self->{node}->{$descent}->{checksum} = md5_base64($dump) . '=='; |
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|
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# 2. 32-bit integer "hash" value (maybe faster?) (from DBI) |
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# Note: The 32-bit integer hash from DBI seems to generate duplicates |
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# with small payloads already in ranges of hundreds of items/rows!!! |
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# Try to avoid it or try to use it only for payloads greater than, hmmm, let's say 30 chars? |
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# (we had about 15 chars average per item (row)) |
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# Possible (generic) solution: Just generate checksum, if length(checksum(payload)) < length(payload) |
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#$self->{node}->{$descent}->{checksum} = DBI::hash($dump, 1); |
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|
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# 3. good old crc32??? |
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#$self->{node}->{$descent}->{checksum} = crc32($dump); |
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|
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# 4. File::RsyncP::Digest - Perl interface to rsync message digest algorithms |
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if (not RUNNING_IN_HELL()) { |
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my $rsDigest = new File::RsyncP::Digest; |
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$rsDigest->add($dump); |
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my $digest = $rsDigest->digest(); |
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$self->{node}->{$descent}->{checksum} = unpack("H*", $digest); |
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|
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} else { # fallback to Digest::MD5 on win32 |
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$self->{node}->{$descent}->{checksum} = md5_base64($dump) . '=='; |
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} |
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# 5. some more modern Digest::SHA1 or similar? |
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# signal good |
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return 1; |
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} |
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sub _readChecksum { |
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my $self = shift; |
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my $descent = shift; |
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# signal checksum bad |
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if (!$self->{node}->{$descent}) { |
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return; |
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} |
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# trace |
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#print "desc: $descent", "\n"; |
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#print Dumper($self); |
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#print Dumper($self->{meta}->{$descent}); |
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#exit; |
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|
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# get checksum for current entry |
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# TODO: don't have the checksum column/property hardcoded as "cs" here, make this configurable somehow |
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if ($self->{meta}->{$descent}->{isChecksumAuthority}) { |
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$self->_calcChecksum($descent); |
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} else { |
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$self->{node}->{$descent}->{checksum} = $self->{node}->{$descent}->{payload}->{cs}; |
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} |
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# signal checksum good |
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return 1; |
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} |
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1; |
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__END__ |
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