/[fuse_dbi]/fuse-couchdb/DBI.pm
This is repository of my old source code which isn't updated any more. Go to git.rot13.org for current projects!
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revision 23 by dpavlin, Sat Oct 2 16:54:42 2004 UTC revision 40 by dpavlin, Fri Nov 19 21:56:12 2004 UTC
# Line 13  use Carp; Line 13  use Carp;
13  use Data::Dumper;  use Data::Dumper;
14    
15    
16  our $VERSION = '0.03';  our $VERSION = '0.06';
17    
18  =head1 NAME  =head1 NAME
19    
# Line 24  Fuse::DBI - mount your database as files Line 24  Fuse::DBI - mount your database as files
24    use Fuse::DBI;    use Fuse::DBI;
25    Fuse::DBI->mount( ... );    Fuse::DBI->mount( ... );
26    
27  See C<run> below for examples how to set parametars.  See C<run> below for examples how to set parameters.
28    
29  =head1 DESCRIPTION  =head1 DESCRIPTION
30    
31  This module will use C<Fuse> module, part of C<FUSE (Filesystem in USErspace)>  This module will use C<Fuse> module, part of C<FUSE (Filesystem in USErspace)>
32  available at L<http://sourceforge.net/projects/avf> to mount  available at L<http://fuse.sourceforge.net/> to mount
33  your database as file system.  your database as file system.
34    
35  That will give you posibility to use normal file-system tools (cat, grep, vi)  That will give you possibility to use normal file-system tools (cat, grep, vi)
36  to manipulate data in database.  to manipulate data in database.
37    
38  It's actually opposite of Oracle's intention to put everything into database.  It's actually opposite of Oracle's intention to put everything into database.
# Line 46  It's actually opposite of Oracle's inten Line 46  It's actually opposite of Oracle's inten
46    
47  Mount your database as filesystem.  Mount your database as filesystem.
48    
49    Let's suppose that your database have table C<files> with following structure:
50    
51     id:            int
52     filename:      text
53     size:          int
54     content:       text
55     writable:      boolean
56    
57    Following is example how to mount table like that to C</mnt>:
58    
59    my $mnt = Fuse::DBI->mount({    my $mnt = Fuse::DBI->mount({
60          filenames => 'select name from files_table as filenames',          'filenames' => 'select id,filename,size,writable from files',
61          read => 'sql read',          'read' => 'select content from files where id = ?',
62          update => 'sql update',          'update' => 'update files set content = ? where id = ?',
63          dsn => 'DBI:Pg:dbname=webgui',          'dsn' => 'DBI:Pg:dbname=test_db',
64          user => 'database_user',          'user' => 'database_user',
65          password => 'database_password'          'password' => 'database_password',
66            'invalidate' => sub { ... },
67    });    });
68    
69    Options:
70    
71    =over 5
72    
73    =item filenames
74    
75    SQL query which returns C<id> (unique id for that row), C<filename>,
76    C<size> and C<writable> boolean flag.
77    
78    =item read
79    
80    SQL query which returns only one column with content of file and has
81    placeholder C<?> for C<id>.
82    
83    =item update
84    
85    SQL query with two pace-holders, one for new content and one for C<id>.
86    
87    =item dsn
88    
89    C<DBI> dsn to connect to (contains database driver and name of database).
90    
91    =item user
92    
93    User with which to connect to database
94    
95    =item password
96    
97    Password for connecting to database
98    
99    =item invalidate
100    
101    Optional anonymous code reference which will be executed when data is updated in
102    database. It can be used as hook to delete cache (for example on-disk-cache)
103    which is created from data edited through C<Fuse::DBI>.
104    
105    =item fork
106    
107    Optional flag which forks after mount so that executing script will continue
108    running. Implementation is experimental.
109    
110    =back
111    
112  =cut  =cut
113    
114  my $dbh;  my $dbh;
# Line 64  my $ctime_start; Line 118  my $ctime_start;
118  sub read_filenames;  sub read_filenames;
119  sub fuse_module_loaded;  sub fuse_module_loaded;
120    
121    # evil, evil way to solve this. It makes this module non-reentrant. But, since
122    # fuse calls another copy of this script for each mount anyway, this shouldn't
123    # be a problem.
124    my $fuse_self;
125    
126  sub mount {  sub mount {
127          my $class = shift;          my $class = shift;
128          my $self = {};          my $self = {};
# Line 77  sub mount { Line 136  sub mount {
136          carp "mount needs 'mount' as mountpoint" unless ($arg->{'mount'});          carp "mount needs 'mount' as mountpoint" unless ($arg->{'mount'});
137    
138          # save (some) arguments in self          # save (some) arguments in self
139          $self->{$_} = $arg->{$_} foreach (qw(mount));          foreach (qw(mount invalidate)) {
140                    $self->{$_} = $arg->{$_};
141            }
142    
143          foreach (qw(filenames read update)) {          foreach (qw(filenames read update)) {
144                  carp "mount needs '$_' SQL" unless ($arg->{$_});                  carp "mount needs '$_' SQL" unless ($arg->{$_});
# Line 97  sub mount { Line 158  sub mount {
158    
159          $dbh = DBI->connect($arg->{'dsn'},$arg->{'user'},$arg->{'password'}, {AutoCommit => 0, RaiseError => 1}) || die $DBI::errstr;          $dbh = DBI->connect($arg->{'dsn'},$arg->{'user'},$arg->{'password'}, {AutoCommit => 0, RaiseError => 1}) || die $DBI::errstr;
160    
161          $sth->{filenames} = $dbh->prepare($arg->{'filenames'}) || die $dbh->errstr();          $sth->{'filenames'} = $dbh->prepare($arg->{'filenames'}) || die $dbh->errstr();
162    
163          $sth->{'read'} = $dbh->prepare($arg->{'read'}) || die $dbh->errstr();          $sth->{'read'} = $dbh->prepare($arg->{'read'}) || die $dbh->errstr();
164          $sth->{'update'} = $dbh->prepare($arg->{'update'}) || die $dbh->errstr();          $sth->{'update'} = $dbh->prepare($arg->{'update'}) || die $dbh->errstr();
165    
166    
167            $self->{'sth'} = $sth;
168    
169            $self->{'read_filenames'} = sub { $self->read_filenames };
170          $self->read_filenames;          $self->read_filenames;
171    
172            $fuse_self = \$self;
173    
174          Fuse::main(          Fuse::main(
175                  mountpoint=>$arg->{'mount'},                  mountpoint=>$arg->{'mount'},
176                  getattr=>\&e_getattr,                  getattr=>\&e_getattr,
# Line 115  sub mount { Line 182  sub mount {
182                  utime=>\&e_utime,                  utime=>\&e_utime,
183                  truncate=>\&e_truncate,                  truncate=>\&e_truncate,
184                  unlink=>\&e_unlink,                  unlink=>\&e_unlink,
185                    rmdir=>\&e_unlink,
186                  debug=>0,                  debug=>0,
187          );          );
188            
189          exit(0) if ($arg->{'fork'});          exit(0) if ($arg->{'fork'});
190    
191          return 1;          return 1;
# Line 138  database to filesystem. Line 206  database to filesystem.
206  sub umount {  sub umount {
207          my $self = shift;          my $self = shift;
208    
209          system "fusermount -u ".$self->{'mount'} || croak "umount error: $!";          if ($self->{'mount'}) {
210                    if (open(MTAB, "/etc/mtab")) {
211                            my $mounted = 0;
212                            my $mount = $self->{'mount'};
213                            while(<MTAB>) {
214                                    $mounted = 1 if (/ $mount fuse /i);
215                            }
216                            close(MTAB);
217                    
218                            if ($mounted) {
219                                    system "fusermount -u ".$self->{'mount'}." 2>&1 >/dev/null" || return 0;
220                                    return 1;
221                            }
222    
223                    } else {
224                            warn "can't open /etc/mtab: $!";
225                            return 0;
226                    }
227            }
228    }
229    
230          return 1;  $SIG{'INT'} = sub {
231            if ($fuse_self && $$fuse_self->umount) {
232                    print STDERR "umount called by SIG INT\n";
233            }
234    };
235    
236    $SIG{'QUIT'} = sub {
237            if ($fuse_self && $$fuse_self->umount) {
238                    print STDERR "umount called by SIG QUIT\n";
239            }
240    };
241    
242    sub DESTROY {
243            my $self = shift;
244            if ($self->umount) {
245                    print STDERR "umount called by DESTROY\n";
246            }
247  }  }
248    
249  =head2 fuse_module_loaded  =head2 fuse_module_loaded
# Line 150  Checks if C<fuse> module is loaded in ke Line 253  Checks if C<fuse> module is loaded in ke
253    die "no fuse module loaded in kernel"    die "no fuse module loaded in kernel"
254          unless (Fuse::DBI::fuse_module_loaded);          unless (Fuse::DBI::fuse_module_loaded);
255    
256  This function in called by L<mount>, but might be useful alone also.  This function in called by C<mount>, but might be useful alone also.
257    
258  =cut  =cut
259    
# Line 170  my %dirs; Line 273  my %dirs;
273  sub read_filenames {  sub read_filenames {
274          my $self = shift;          my $self = shift;
275    
276            my $sth = $self->{'sth'} || die "no sth argument";
277    
278          # create empty filesystem          # create empty filesystem
279          (%files) = (          (%files) = (
280                  '.' => {                  '.' => {
281                          type => 0040,                          type => 0040,
282                          mode => 0755,                          mode => 0755,
283                  },                  },
284                    '..' => {
285                            type => 0040,
286                            mode => 0755,
287                    },
288          #       a => {          #       a => {
289          #               cont => "File 'a'.\n",          #               cont => "File 'a'.\n",
290          #               type => 0100,          #               type => 0100,
# Line 254  sub e_getdir { Line 363  sub e_getdir {
363          my %out;          my %out;
364          foreach my $f (sort keys %files) {          foreach my $f (sort keys %files) {
365                  if ($dirname) {                  if ($dirname) {
366                          if ($f =~ s/^\E$dirname\Q\///) {                          if ($f =~ s/^\Q$dirname\E\///) {
367                                  $out{$f}++ if ($f =~ /^[^\/]+$/);                                  $out{$f}++ if ($f =~ /^[^\/]+$/);
368                          }                          }
369                  } else {                  } else {
# Line 276  sub read_content { Line 385  sub read_content {
385    
386          $sth->{'read'}->execute($id) || die $sth->{'read'}->errstr;          $sth->{'read'}->execute($id) || die $sth->{'read'}->errstr;
387          $files{$file}{cont} = $sth->{'read'}->fetchrow_array;          $files{$file}{cont} = $sth->{'read'}->fetchrow_array;
388            # I should modify ctime only if content in database changed
389            #$files{$file}{ctime} = time() unless ($files{$file}{ctime});
390          print "file '$file' content [",length($files{$file}{cont})," bytes] read in cache\n";          print "file '$file' content [",length($files{$file}{cont})," bytes] read in cache\n";
391  }  }
392    
# Line 321  sub clear_cont { Line 432  sub clear_cont {
432          print "invalidate all cached content\n";          print "invalidate all cached content\n";
433          foreach my $f (keys %files) {          foreach my $f (keys %files) {
434                  delete $files{$f}{cont};                  delete $files{$f}{cont};
435                    delete $files{$f}{ctime};
436          }          }
437          print "begin new transaction\n";          print "begin new transaction\n";
438          #$dbh->begin_work || die $dbh->errstr;          #$dbh->begin_work || die $dbh->errstr;
# Line 348  sub update_db { Line 460  sub update_db {
460                          return 0;                          return 0;
461                  }                  }
462                  print "updated '$file' [",$files{$file}{id},"]\n";                  print "updated '$file' [",$files{$file}{id},"]\n";
463    
464                    $$fuse_self->{'invalidate'}->() if (ref $$fuse_self->{'invalidate'});
465          }          }
466          return 1;          return 1;
467  }  }
# Line 407  sub e_statfs { return 255, 1, 1, 1, 1, 2 Line 521  sub e_statfs { return 255, 1, 1, 1, 1, 2
521  sub e_unlink {  sub e_unlink {
522          my $file = filename_fixup(shift);          my $file = filename_fixup(shift);
523    
524          return -ENOENT() unless exists($files{$file});          if (exists( $dirs{$file} )) {
525                    print "unlink '$file' will re-read template names\n";
526          print "unlink '$file' will invalidate cache\n";                  print Dumper($fuse_self);
527                    $$fuse_self->{'read_filenames'}->();
528          read_content($file,$files{$file}{id});                  return 0;
529            } elsif (exists( $files{$file} )) {
530                    print "unlink '$file' will invalidate cache\n";
531                    read_content($file,$files{$file}{id});
532                    return 0;
533            }
534    
535          return 0;          return -ENOENT();
536  }  }
537  1;  1;
538  __END__  __END__
# Line 422  __END__ Line 541  __END__
541    
542  Nothing.  Nothing.
543    
544    =head1 BUGS
545    
546    Size information (C<ls -s>) is wrong. It's a problem in upstream Fuse module
547    (for which I'm to blame lately), so when it gets fixes, C<Fuse::DBI> will
548    automagically pick it up.
549    
550  =head1 SEE ALSO  =head1 SEE ALSO
551    
552  C<FUSE (Filesystem in USErspace)> website  C<FUSE (Filesystem in USErspace)> website
553  L<http://sourceforge.net/projects/avf>  L<http://fuse.sourceforge.net/>
554    
555    Example for WebGUI which comes with this distribution in
556    directory C<examples/webgui.pl>. It also contains a lot of documentation
557    about design of this module, usage and limitations.
558    
559  =head1 AUTHOR  =head1 AUTHOR
560    
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