| 1 |
# -*- Mode: Perl -*- |
| 2 |
# $Basename: Database.pm $ |
| 3 |
# $Revision: 1.14 $ |
| 4 |
# Author : Ulrich Pfeifer |
| 5 |
# Created On : Thu Aug 8 09:44:13 1996 |
| 6 |
# Last Modified By: Ulrich Pfeifer |
| 7 |
# Last Modified On: Sat Apr 15 16:15:29 2000 |
| 8 |
# Language : CPerl |
| 9 |
# |
| 10 |
# (C) Copyright 1996-2000, Ulrich Pfeifer |
| 11 |
# |
| 12 |
|
| 13 |
=head1 NAME |
| 14 |
|
| 15 |
WAIT::Database - Module fo maintaining WAIT databases |
| 16 |
|
| 17 |
=head1 SYNOPSIS |
| 18 |
|
| 19 |
require WAIT::Database; |
| 20 |
|
| 21 |
=head1 DESCRIPTION |
| 22 |
|
| 23 |
The modules handles creating, opening, and deleting of databases and |
| 24 |
tables. |
| 25 |
|
| 26 |
=cut |
| 27 |
|
| 28 |
package WAIT::Database; |
| 29 |
|
| 30 |
use strict; |
| 31 |
use FileHandle (); |
| 32 |
use File::Path qw(rmtree); |
| 33 |
use WAIT::Table (); |
| 34 |
use Fcntl; |
| 35 |
use Carp; # will use autouse later |
| 36 |
use LockFile::Simple (); |
| 37 |
|
| 38 |
# use autouse Carp => qw( croak($) ); |
| 39 |
my ($HAVE_DATA_DUMPER, $HAVE_STORABLE); |
| 40 |
|
| 41 |
BEGIN { |
| 42 |
eval { require Data::Dumper }; |
| 43 |
$HAVE_DATA_DUMPER = 1 if $@ eq ''; |
| 44 |
eval { require Storable }; |
| 45 |
$HAVE_STORABLE = 1 if $@ eq ''; |
| 46 |
$HAVE_DATA_DUMPER || $HAVE_STORABLE || |
| 47 |
die "Could not find Data::Dumper nor Storable"; |
| 48 |
$Storable::forgive_me = 1; |
| 49 |
} |
| 50 |
|
| 51 |
|
| 52 |
=head2 Constructor create |
| 53 |
|
| 54 |
$db = WAIT::Database->create( |
| 55 |
name => <name>, |
| 56 |
directory => <dir> |
| 57 |
); |
| 58 |
|
| 59 |
Create a new database. |
| 60 |
|
| 61 |
=over 10 |
| 62 |
|
| 63 |
=item B<name> I<name> |
| 64 |
|
| 65 |
mandatory |
| 66 |
|
| 67 |
=item B<directory> I<directory> |
| 68 |
|
| 69 |
Directory which should contain the database (defaults to the current |
| 70 |
directory). |
| 71 |
|
| 72 |
=item B<uniqueatt> I<true> |
| 73 |
|
| 74 |
If given, the database will require unique attributes over all tables. |
| 75 |
|
| 76 |
The method will croak on failure. |
| 77 |
|
| 78 |
=back |
| 79 |
|
| 80 |
=cut |
| 81 |
|
| 82 |
sub create { |
| 83 |
my $type = shift; |
| 84 |
my %parm = @_; |
| 85 |
my $self = {}; |
| 86 |
my $dir = $parm{directory} || '.'; |
| 87 |
my $name = $parm{name}; |
| 88 |
|
| 89 |
unless ($name) { |
| 90 |
croak("No name specified"); |
| 91 |
} |
| 92 |
|
| 93 |
unless (-d $dir){ |
| 94 |
croak("Directory '$dir' does not exits: $!"); |
| 95 |
} |
| 96 |
|
| 97 |
if (-d "$dir/$name") { |
| 98 |
warn "Warning: Directory '$dir/$name' already exists"; |
| 99 |
} else { |
| 100 |
unless (mkdir "$dir/$name", 0775) { |
| 101 |
croak("Could not mkdir '$dir/$name': $!"); |
| 102 |
} |
| 103 |
} |
| 104 |
|
| 105 |
$self->{name} = $name; |
| 106 |
$self->{file} = "$dir/$name"; |
| 107 |
$self->{uniqueatt} = $parm{uniqueatt}; |
| 108 |
$self->{mode} = O_CREAT; |
| 109 |
my $lockmgr = LockFile::Simple->make(-autoclean => 1); |
| 110 |
# aquire a write lock |
| 111 |
$self->{write_lock} = $lockmgr->lock("$dir/$name/write") |
| 112 |
or die "Can't lock '$dir/$name/write'"; |
| 113 |
bless $self => ref($type) || $type; |
| 114 |
} |
| 115 |
|
| 116 |
|
| 117 |
=head2 Constructor open |
| 118 |
|
| 119 |
$db = WAIT::Database->open( |
| 120 |
name => "foo", |
| 121 |
directory => "bar" |
| 122 |
); |
| 123 |
|
| 124 |
Open an existing database I<foo> in directory I<bar>. |
| 125 |
|
| 126 |
=cut |
| 127 |
|
| 128 |
sub open { |
| 129 |
my $type = shift; |
| 130 |
my %parm = @_; |
| 131 |
my $dir = $parm{directory} || '.'; |
| 132 |
my $name = $parm{name} or croak "No name specified"; |
| 133 |
my $catalog = "$dir/$name/catalog"; |
| 134 |
my $meta = "$dir/$name/meta"; |
| 135 |
my $self; |
| 136 |
|
| 137 |
if ($HAVE_STORABLE and -e $catalog |
| 138 |
and (!-e $meta or -M $meta >= -M $catalog)) { |
| 139 |
$self = Storable::retrieve($catalog); |
| 140 |
} else { |
| 141 |
return undef unless -f $meta; |
| 142 |
|
| 143 |
$self = do $meta; |
| 144 |
unless (defined $self) { |
| 145 |
warn "do '$meta' did not work. Mysterious! Reverting to eval `cat $meta`"; |
| 146 |
sleep(4); |
| 147 |
$self = eval `cat $meta`; |
| 148 |
} |
| 149 |
} |
| 150 |
|
| 151 |
return unless defined $self; |
| 152 |
$self->{mode} = (exists $parm{mode})?$parm{mode}:(O_CREAT | O_RDWR); |
| 153 |
|
| 154 |
if ($self->{mode} & O_RDWR) { |
| 155 |
# Locking: We do not care about read access since write is atomic. |
| 156 |
my $lockmgr = LockFile::Simple->make(-autoclean => 1); |
| 157 |
|
| 158 |
# aquire a write lock |
| 159 |
$self->{write_lock} = $lockmgr->lock("$dir/$name/write") |
| 160 |
or die "Can't lock '$dir/$name/write'"; |
| 161 |
} |
| 162 |
|
| 163 |
$self; |
| 164 |
} |
| 165 |
|
| 166 |
|
| 167 |
=head2 C<$db-E<gt>dispose;> |
| 168 |
|
| 169 |
Dispose a database. Remove all associated files. This may fail if the |
| 170 |
database or one of its tables is still open. Failure will be indicated |
| 171 |
by a false return value. |
| 172 |
|
| 173 |
=cut |
| 174 |
|
| 175 |
sub dispose { |
| 176 |
my $dir; |
| 177 |
|
| 178 |
if (ref $_[0]) { # called with instance |
| 179 |
croak "Database readonly" unless $_[0]->{mode} & (O_CREAT | O_RDWR); |
| 180 |
$dir = $_[0]->{file}; |
| 181 |
$_[0]->close; |
| 182 |
} else { |
| 183 |
my $type = shift; |
| 184 |
my %parm = @_; |
| 185 |
my $base = $parm{directory} || '.'; |
| 186 |
my $name = $parm{name} || croak "No name specified"; |
| 187 |
$dir = "$base/$name"; |
| 188 |
} |
| 189 |
croak "No such database '$dir'" unless -e "$dir/meta"; |
| 190 |
|
| 191 |
#warn "Running rmtree on dir[$dir]"; |
| 192 |
my $ret = rmtree($dir, 0, 1); |
| 193 |
#warn "rmtree returned[$ret]"; |
| 194 |
$ret; |
| 195 |
} |
| 196 |
|
| 197 |
|
| 198 |
=head2 C<$db-E<gt>close;> |
| 199 |
|
| 200 |
Close a database saving all meta data after closing all associated tables. |
| 201 |
|
| 202 |
=cut |
| 203 |
|
| 204 |
sub close { |
| 205 |
my $self = $_[0]; |
| 206 |
my $file = $self->{file}; |
| 207 |
my $table; |
| 208 |
my $did_save; |
| 209 |
|
| 210 |
for $table (values %{$self->{tables}}) { |
| 211 |
$table->close if ref($table); |
| 212 |
} |
| 213 |
return 1 unless $self->{mode} & (O_RDWR | O_CREAT); |
| 214 |
|
| 215 |
my $lock = delete $self->{write_lock}; # Do not store lock objects |
| 216 |
|
| 217 |
if ($HAVE_DATA_DUMPER) { |
| 218 |
my $fh = new FileHandle "> $file/meta.$$"; |
| 219 |
if ($fh) { |
| 220 |
my $dumper = new Data::Dumper [$self],['self']; |
| 221 |
$fh->print('my '); |
| 222 |
$fh->print($dumper->Dumpxs); |
| 223 |
$fh->close; |
| 224 |
$did_save = rename "$file/meta.$$", "$file/meta"; |
| 225 |
} else { |
| 226 |
croak "Could not open '$file/meta' for writing: $!"; |
| 227 |
# never reached: return unless $HAVE_STORABLE; |
| 228 |
} |
| 229 |
} |
| 230 |
|
| 231 |
if ($HAVE_STORABLE) { |
| 232 |
if (!eval {Storable::store($self, "$file/catalog.$$")}) { |
| 233 |
unlink "$file/catalog.$$"; |
| 234 |
croak "Could not open '$file/catalog.$$' for writing: $!"; |
| 235 |
# never reached: return unless $did_save; |
| 236 |
} else { |
| 237 |
$did_save = rename "$file/catalog.$$", "$file/catalog"; |
| 238 |
} |
| 239 |
} |
| 240 |
|
| 241 |
$lock->release; |
| 242 |
|
| 243 |
undef $_[0]; |
| 244 |
$did_save; |
| 245 |
} |
| 246 |
|
| 247 |
|
| 248 |
=head2 C<$db-E<gt>create_table(name =E<gt>> I<tname>, ... C<);> |
| 249 |
|
| 250 |
Create a new table with name I<tname>. All parameters are passed to |
| 251 |
C<WAIT::Table-E<gt>new> together with a filename to use. See |
| 252 |
L<WAIT::Table> for which attributes are required. The method returns a |
| 253 |
table handle (C<WAIT::Table::Handle>). |
| 254 |
|
| 255 |
=cut |
| 256 |
|
| 257 |
sub create_table { |
| 258 |
my $self = shift; |
| 259 |
my %parm = @_; |
| 260 |
my $name = $parm{name} or croak "create_table: No name specified"; |
| 261 |
my $attr = $parm{attr} or croak "create_table: No attributes specified"; |
| 262 |
my $file = $self->{file}; |
| 263 |
|
| 264 |
croak "Database readonly" unless $self->{mode} & (O_CREAT | O_RDWR); |
| 265 |
|
| 266 |
if (defined $self->{tables}->{$name}) { |
| 267 |
die "Table '$name' already exists"; |
| 268 |
} |
| 269 |
|
| 270 |
if ($self->{uniqueatt}) { |
| 271 |
for (@$attr) { # attribute names must be uniqe |
| 272 |
if ($self->{attr}->{$_}) { |
| 273 |
croak("Attribute '$_' is not unique") |
| 274 |
} |
| 275 |
} |
| 276 |
} |
| 277 |
$self->{tables}->{$name} = WAIT::Table->new(file => "$file/$name", |
| 278 |
database => $self, |
| 279 |
%parm); |
| 280 |
unless (defined $self->{tables}->{$name}) {# fail gracefully |
| 281 |
delete $self->{tables}->{$name}; |
| 282 |
return undef; |
| 283 |
} |
| 284 |
|
| 285 |
if ($self->{uniqueatt}) { |
| 286 |
# remember table name for each attribute |
| 287 |
map ($self->{attr}->{$_} = $name, @$attr); |
| 288 |
} |
| 289 |
WAIT::Table::Handle->new($self, $name); |
| 290 |
} |
| 291 |
|
| 292 |
|
| 293 |
=head2 C<$db-E<gt>table(name =E<gt>> I<tname>C<);> |
| 294 |
|
| 295 |
Open a new table with name I<tname>. The method |
| 296 |
returns a table handle (C<WAIT::Table::Handle>). |
| 297 |
|
| 298 |
=cut |
| 299 |
|
| 300 |
sub sync { |
| 301 |
my $self = shift; |
| 302 |
|
| 303 |
for (values %{$self->{tables}}) { |
| 304 |
$_->sync; |
| 305 |
} |
| 306 |
} |
| 307 |
|
| 308 |
sub table { |
| 309 |
my $self = shift; |
| 310 |
my %parm = @_; |
| 311 |
my $name = $parm{name} or croak "No name specified"; |
| 312 |
|
| 313 |
if (defined $self->{tables}->{$name}) { |
| 314 |
if (exists $parm{mode}) { |
| 315 |
$self->{tables}->{$name}->{mode} = $parm{mode}; |
| 316 |
} else { |
| 317 |
$self->{tables}->{$name}->{mode} = $self->{mode}; |
| 318 |
} |
| 319 |
WAIT::Table::Handle->new($self,$name); |
| 320 |
} else { |
| 321 |
# croak "No such table '$name'"; |
| 322 |
return; |
| 323 |
} |
| 324 |
} |
| 325 |
|
| 326 |
|
| 327 |
=head2 C<$db-E<gt>drop(name =E<gt>> I<tname>C<);> |
| 328 |
|
| 329 |
Drop the table named I<tname>. The table should be closed before |
| 330 |
calling B<drop>. |
| 331 |
|
| 332 |
=cut |
| 333 |
|
| 334 |
sub drop_table { |
| 335 |
my $self = shift; |
| 336 |
my %parm = @_; |
| 337 |
my $name = $parm{name} or croak "No name specified"; |
| 338 |
|
| 339 |
croak "Database readonly" unless $self->{mode} & (O_CREAT | O_RDWR); |
| 340 |
if (!defined $self->{tables}->{$name}) { |
| 341 |
croak "Table '$name' does not exist"; |
| 342 |
} |
| 343 |
$self->{tables}->{$name}->drop; |
| 344 |
|
| 345 |
if ($self->{uniqueatt}) { |
| 346 |
# recycle attribute names |
| 347 |
for (keys %{$self->{attr}}) { |
| 348 |
delete $self->{attr}->{$_} if $self->{attr}->{$_} eq $name; |
| 349 |
} |
| 350 |
} |
| 351 |
undef $self->{tables}->{$name}; # Call WAIT::Table::DESTROY here; |
| 352 |
1; |
| 353 |
} |
| 354 |
|
| 355 |
|
| 356 |
1; |
| 357 |
|
| 358 |
|
| 359 |
=head1 AUTHOR |
| 360 |
|
| 361 |
Ulrich Pfeifer E<lt>F<pfeifer@ls6.informatik.uni-dortmund.de>E<gt> |
| 362 |
|
| 363 |
=cut |
| 364 |
|
| 365 |
|
Parent Directory
| 
Revision Log