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# -*- Mode: Cperl -*- |
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# Database -- |
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# ITIID : $ITI$ $Header $__Header$ |
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# Author : Ulrich Pfeifer |
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# Created On : Thu Aug 8 09:44:13 1996 |
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# Last Modified By: Ulrich Pfeifer |
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# Last Modified On: Sun May 30 18:34:08 1999 |
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# Language : CPerl |
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# Update Count : 250 |
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# Status : Unknown, Use with caution! |
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# |
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# Copyright (c) 1996-1997, Ulrich Pfeifer |
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# |
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|
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=head1 NAME |
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|
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WAIT::Database - Module fo maintaining WAIT databases |
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|
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=head1 SYNOPSIS |
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|
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require WAIT::Database; |
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|
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=head1 DESCRIPTION |
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|
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The modules handles creating, opening, and deleting of databases and |
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tables. |
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|
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=cut |
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|
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package WAIT::Database; |
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|
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use strict; |
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use FileHandle (); |
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use File::Path qw(rmtree); |
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use WAIT::Table (); |
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use Fcntl; |
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use Carp; # will use autouse later |
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# use autouse Carp => qw( croak($) ); |
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my ($HAVE_DATA_DUMPER, $HAVE_STORABLE); |
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|
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BEGIN { |
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eval { require Data::Dumper }; |
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$HAVE_DATA_DUMPER = 1 if $@ eq ''; |
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eval { require Storable }; |
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$HAVE_STORABLE = 1 if $@ eq ''; |
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$HAVE_DATA_DUMPER || $HAVE_STORABLE || |
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die "Could not find Data::Dumper nor Storable"; |
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$Storable::forgive_me = 1; |
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} |
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|
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|
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=head2 Constructor create |
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|
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$db = WAIT::Database->create( |
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name => <name>, |
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directory => <dir> |
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); |
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|
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Create a new database. |
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|
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=over 10 |
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|
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=item B<name> I<name> |
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|
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mandatory |
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|
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=item B<directory> I<directory> |
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|
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Directory which should contain the database (defaults to the current |
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directory). |
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|
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=item B<uniqueatt> I<true> |
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|
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If given, the database will require unique attributes over all tables. |
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|
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The method will croak on failure. |
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|
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=back |
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|
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=cut |
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|
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sub create { |
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my $type = shift; |
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my %parm = @_; |
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my $self = {}; |
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my $dir = $parm{directory} || '.'; |
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my $name = $parm{name}; |
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|
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unless ($name) { |
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croak("No name specified"); |
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} |
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|
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unless (-d $dir){ |
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croak("Directory '$dir' does not exits: $!"); |
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} |
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|
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if (-d "$dir/$name") { |
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warn "Warning: Directory '$dir/$name' already exists"; |
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} else { |
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unless (mkdir "$dir/$name", 0775) { |
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croak("Could not mkdir '$dir/$name': $!"); |
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} |
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} |
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|
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$self->{name} = $name; |
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$self->{file} = "$dir/$name"; |
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$self->{uniqueatt} = $parm{uniqueatt}; |
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$self->{mode} = O_CREAT; |
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bless $self => ref($type) || $type; |
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} |
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|
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|
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=head2 Constructor open |
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|
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$db = WAIT::Database->open( |
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name => "foo", |
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directory => "bar" |
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); |
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|
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Open an existing database I<foo> in directory I<bar>. |
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|
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=cut |
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|
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sub open { |
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my $type = shift; |
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my %parm = @_; |
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my $dir = $parm{directory} || '.'; |
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my $name = $parm{name} or croak "No name specified"; |
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my $catalog = "$dir/$name/catalog"; |
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my $meta = "$dir/$name/meta"; |
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my $self; |
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|
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if ($HAVE_STORABLE and -e $catalog |
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and (!-e $meta or -M $meta >= -M $catalog)) { |
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$self = Storable::retrieve($catalog); |
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} else { |
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return undef unless -f $meta; |
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|
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$self = do $meta; |
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unless (defined $self) { |
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warn "do '$meta' did not work. Mysterious! Reverting to eval `cat $meta`"; |
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sleep(4); |
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$self = eval `cat $meta`; |
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} |
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} |
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|
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return unless defined $self; |
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$self->{mode} = (exists $parm{mode})?$parm{mode}:(O_CREAT | O_RDWR); |
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$self; |
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} |
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|
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|
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=head2 C<$db-E<gt>dispose;> |
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Dispose a database. Remove all associated files. This may fail if the |
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database or one of its tables is still open. Failure will be indicated |
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by a false return value. |
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|
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=cut |
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|
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sub dispose { |
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my $dir; |
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|
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if (ref $_[0]) { # called with instance |
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croak "Database readonly" unless $_[0]->{mode} & (O_CREAT | O_RDWR); |
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$dir = $_[0]->{file}; |
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$_[0]->close; |
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} else { |
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my $type = shift; |
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my %parm = @_; |
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my $base = $parm{directory} || '.'; |
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my $name = $parm{name} || croak "No name specified"; |
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$dir = "$base/$name"; |
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} |
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croak "No such database '$dir'" unless -e "$dir/meta"; |
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|
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#warn "Running rmtree on dir[$dir]"; |
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my $ret = rmtree($dir, 0, 1); |
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#warn "rmtree returned[$ret]"; |
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$ret; |
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} |
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|
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|
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=head2 C<$db-E<gt>close;> |
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|
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Close a database saving all meta data after closing all associated tables. |
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|
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=cut |
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|
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sub close { |
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my $self = $_[0]; |
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my $file = $self->{file}; |
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my $table; |
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my $did_save; |
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|
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for $table (values %{$self->{tables}}) { |
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$table->close if ref($table); |
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} |
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return 1 unless $self->{mode} & (O_RDWR | O_CREAT); |
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|
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if ($HAVE_DATA_DUMPER) { |
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my $fh = new FileHandle "> $file/meta"; |
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if ($fh) { |
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my $dumper = new Data::Dumper [$self],['self']; |
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$fh->print('my '); |
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$fh->print($dumper->Dumpxs); |
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$fh->close; |
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$did_save = 1; |
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} else { |
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croak "Could not open '$file/meta' for writing: $!"; |
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# never reached: return unless $HAVE_STORABLE; |
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} |
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} |
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|
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if ($HAVE_STORABLE) { |
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if (!eval {Storable::store($self, "$file/catalog")}) { |
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croak "Could not open '$file/catalog' for writing: $!"; |
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# never reached: return unless $did_save; |
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} else { |
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$did_save++; |
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} |
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} |
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undef $_[0]; |
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$did_save; |
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} |
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|
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|
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=head2 C<$db-E<gt>create_table(name =E<gt>> I<tname>, ... C<);> |
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Create a new table with name I<tname>. All parameters are passed to |
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C<WAIT::Table-E<gt>new> together with a filename to use. See |
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L<WAIT::Table> for which attributes are required. The method returns a |
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table handle (C<WAIT::Table::Handle>). |
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|
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=cut |
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|
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sub create_table { |
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my $self = shift; |
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my %parm = @_; |
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my $name = $parm{name} or croak "create_table: No name specified"; |
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my $attr = $parm{attr} or croak "create_table: No attributes specified"; |
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my $file = $self->{file}; |
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|
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croak "Database readonly" unless $self->{mode} & (O_CREAT | O_RDWR); |
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|
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if (defined $self->{tables}->{$name}) { |
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die "Table '$name' already exists"; |
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} |
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if ($self->{uniqueatt}) { |
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for (@$attr) { # attribute names must be uniqe |
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if ($self->{attr}->{$_}) { |
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croak("Attribute '$_' is not unique") |
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} |
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} |
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} |
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$self->{tables}->{$name} = WAIT::Table->new(file => "$file/$name", |
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database => $self, |
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%parm); |
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unless (defined $self->{tables}->{$name}) {# fail gracefully |
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delete $self->{tables}->{$name}; |
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return undef; |
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} |
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|
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if ($self->{uniqueatt}) { |
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# remember table name for each attribute |
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map ($self->{attr}->{$_} = $name, @$attr); |
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} |
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WAIT::Table::Handle->new($self, $name); |
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} |
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|
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|
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=head2 C<$db-E<gt>table(name =E<gt>> I<tname>C<);> |
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|
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Open a new table with name I<tname>. The method |
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returns a table handle (C<WAIT::Table::Handle). |
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|
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=cut |
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|
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sub sync { |
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my $self = shift; |
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|
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for (values %{$self->{tables}}) { |
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$_->sync; |
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} |
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} |
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|
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sub table { |
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my $self = shift; |
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my %parm = @_; |
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my $name = $parm{name} or croak "No name specified"; |
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|
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if (defined $self->{tables}->{$name}) { |
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if (exists $parm{mode}) { |
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$self->{tables}->{$name}->{mode} = $parm{mode}; |
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} else { |
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$self->{tables}->{$name}->{mode} = $self->{mode}; |
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} |
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WAIT::Table::Handle->new($self,$name); |
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} else { |
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croak "No such table '$name'"; |
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} |
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} |
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|
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|
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=head2 C<$db-E<gt>drop(name =E<gt>> I<tname>C<);> |
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|
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Drop the table named I<tname>. The table should be closed before |
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calling B<drop>. |
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|
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=cut |
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|
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sub drop_table { |
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my $self = shift; |
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my %parm = @_; |
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my $name = $parm{name} or croak "No name specified"; |
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|
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croak "Database readonly" unless $self->{mode} & (O_CREAT | O_RDWR); |
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if (!defined $self->{tables}->{$name}) { |
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croak "Table '$name' does not exist"; |
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} |
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$self->{tables}->{$name}->drop; |
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|
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if ($self->{uniqueatt}) { |
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# recycle attribute names |
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for (keys %{$self->{attr}}) { |
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delete $self->{attr}->{$_} if $self->{attr}->{$_} eq $name; |
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} |
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} |
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undef $self->{tables}->{$name}; # Call WAIT::Table::DESTROY here; |
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1; |
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} |
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|
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|
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1; |
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|
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|
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=head1 AUTHOR |
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|
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Ulrich Pfeifer E<lt>F<pfeifer@ls6.informatik.uni-dortmund.de>E<gt> |
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|
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=cut |
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|
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