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williamc |
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#
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# ObjectStore.pm
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#
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# Originally Written by Christopher Williams
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#
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# Description
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# -----------
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# An very simple object persistency manager for small scale use.
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# Objects are saved and recovered on demand
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# Objects to be stored in this manager must implement the following interface
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# new() : No arguments to new
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# store(filehandle) : dump out to stream passed by filehandle
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# restore(filehandle) : restore from stream passed by filehandle
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#
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# Interface
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# ---------
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# new(store_directory) : A new ObjectStore object
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# store(oref,@keys) : store an object - each object must have
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# a unique key
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# find(@keys) : find and recover object(s) from the store
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# that match keys. Returned as a list of oref
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package ObjectUtilities::ObjectStore;
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require 5.004;
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use Utilities::AddDir;
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use Utilities::HashDB;
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sub new {
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my $class=shift;
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my $dir=shift;
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$self={};
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bless $self, $class;
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$self->{admindir}=$dir."/admin";
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AddDir::adddir($self->{admindir});
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if ( -d $dir ) {
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$self->{storage}=$dir."/objects";
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AddDir::adddir($self->{storage});
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$self->_init();
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}
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else {
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return undef;
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}
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return $self;
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}
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sub store {
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my $self=shift;
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my $oref=shift;
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my @keys=@_;
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my $oreftype=ref($oref);
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my $filename=$self->{storage}."/".$self->_filename(@keys);
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my $fh=$self->_openfile(">".$filename);
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$oref->store($fh);
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close $fh;
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$self->{filehash}->deletedata(@keys);
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$self->{filehash}->setdata($filename,@keys); # persistent
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$self->{typehash}->deletedata($filename);
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$self->{typehash}->setdata($oreftype,$filename); # persistent
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$self->{orefhash}->deletedata($filename);
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$self->{orefhash}->setdata($oref,$filename); # transient
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$self->_storedb();
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}
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sub find {
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my $self=shift;
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my @keys=shift;
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my @oref=();
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my $oref;
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my @types;
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my $type;
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my @validobjs=();
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my $fh;
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my @datafiles=$self->{filehash}->getdata(@keys);
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foreach $file ( @datafiles ) {
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@oref=$self->{orefhash}->getdata($file);
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if ( $#oref < 0 ) { # we need to instatniate it
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@types=$self->{typehash}->getdata($file);
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$type=$types[0];
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eval "require $type";
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$oref=$type->new();
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$fh=$self->_openfile("<".$file);
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$oref->restore($fh);
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close $fh;
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}
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else {
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$oref=$oref[0];
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}
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push @validobjs, $oref;
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}
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return @validobjs;
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}
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#
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# Private routines
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#
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sub _filename {
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my $self=shift;
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my @keys=@_;
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my $filename=join '_', @keys;
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return $filename;
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}
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sub _storedb {
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my $self=shift;
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$self->{filehash}->store($self->{admindir}."/filedb");
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$self->{typehash}->store($self->{admindir}."/typedb");
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}
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sub _restoredb {
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my $self=shift;
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if ( -f $self->{admindir}."/filedb" ) {
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$self->{filehash}->restore($self->{admindir}."/filedb");
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$self->{typehash}->restore($self->{admindir}."/typedb");
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close $fh;
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}
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}
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sub _openfile {
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my $self=shift;
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my $filename=shift;
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local $fh=FileHandle->new();
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open ( $fh, $filename) or die "Unable to open $filename\n $!\n";
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return $fh;
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}
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sub _init {
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my $self=shift;
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$self->{filehash}=Utilities::HashDB->new();
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$self->{typehash}=Utilities::HashDB->new();
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$self->{orefhash}=Utilities::HashDB->new();
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$self->_restoredb();
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}
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