/[fuse_dbi]/trunk/DBI.pm
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revision 26 by dpavlin, Fri Oct 8 22:55:36 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 115  sub mount { Line 169  sub mount {
169          $self->{'read_filenames'} = sub { $self->read_filenames };          $self->{'read_filenames'} = sub { $self->read_filenames };
170          $self->read_filenames;          $self->read_filenames;
171    
         $self->{'mounted'} = 1;  
   
172          $fuse_self = \$self;          $fuse_self = \$self;
173    
174          Fuse::main(          Fuse::main(
# Line 134  sub mount { Line 186  sub mount {
186                  debug=>0,                  debug=>0,
187          );          );
188                    
         $self->{'mounted'} = 0;  
   
189          exit(0) if ($arg->{'fork'});          exit(0) if ($arg->{'fork'});
190    
191          return 1;          return 1;
# Line 156  database to filesystem. Line 206  database to filesystem.
206  sub umount {  sub umount {
207          my $self = shift;          my $self = shift;
208    
209          if ($self->{'mounted'}) {          if ($self->{'mount'}) {
210                  system "fusermount -u ".$self->{'mount'} || croak "umount error: $!";                  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          return 1;                  } else {
224                            warn "can't open /etc/mtab: $!";
225                            return 0;
226                    }
227            }
228  }  }
229    
230  $SIG{'INT'} = sub {  $SIG{'INT'} = sub {
231          print STDERR "umount called by SIG INT\n";          if ($fuse_self && $$fuse_self->umount) {
232          umount;                  print STDERR "umount called by SIG INT\n";
233            }
234    };
235    
236    $SIG{'QUIT'} = sub {
237            if ($fuse_self && $$fuse_self->umount) {
238                    print STDERR "umount called by SIG QUIT\n";
239            }
240  };  };
241    
242  sub DESTROY {  sub DESTROY {
243          my $self = shift;          my $self = shift;
244          return if (! $self->{'mounted'});          if ($self->umount) {
245          print STDERR "umount called by DESTROY\n";                  print STDERR "umount called by DESTROY\n";
246          $self->umount;          }
247  }  }
248    
249  =head2 fuse_module_loaded  =head2 fuse_module_loaded
# Line 182  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 210  sub read_filenames { Line 281  sub read_filenames {
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 288  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 310  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          $files{$file}{ctime} = time();          # 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 356  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 464  __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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