/[fuse_dbi]/trunk/DBI.pm
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revision 26 by dpavlin, Fri Oct 8 22:55:36 2004 UTC revision 47 by dpavlin, Tue Nov 23 23:54:58 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 = '0.07';
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 98  sub mount { Line 152  sub mount {
152                  die "fork() failed: $!" unless defined $pid;                  die "fork() failed: $!" unless defined $pid;
153                  # child will return to caller                  # child will return to caller
154                  if ($pid) {                  if ($pid) {
155                          return $self;                          my $counter = 4;
156                            while ($counter && ! $self->is_mounted) {
157                                    select(undef, undef, undef, 0.5);
158                                    $counter--;
159                            }
160                            if ($self->is_mounted) {
161                                    return $self;
162                            } else {
163                                    return undef;
164                            }
165                  }                  }
166          }          }
167    
# Line 115  sub mount { Line 178  sub mount {
178          $self->{'read_filenames'} = sub { $self->read_filenames };          $self->{'read_filenames'} = sub { $self->read_filenames };
179          $self->read_filenames;          $self->read_filenames;
180    
         $self->{'mounted'} = 1;  
   
181          $fuse_self = \$self;          $fuse_self = \$self;
182    
183          Fuse::main(          Fuse::main(
# Line 134  sub mount { Line 195  sub mount {
195                  debug=>0,                  debug=>0,
196          );          );
197                    
         $self->{'mounted'} = 0;  
   
198          exit(0) if ($arg->{'fork'});          exit(0) if ($arg->{'fork'});
199    
200          return 1;          return 1;
201    
202  };  };
203    
204    =head2 is_mounted
205    
206    Check if fuse filesystem is mounted
207    
208      if ($mnt->is_mounted) { ... }
209    
210    =cut
211    
212    sub is_mounted {
213            my $self = shift;
214    
215            my $mounted = 0;
216            my $mount = $self->{'mount'} || confess "can't find mount point!";
217            if (open(MTAB, "/etc/mtab")) {
218                    while(<MTAB>) {
219                            $mounted = 1 if (/ $mount fuse /i);
220                    }
221                    close(MTAB);
222            } else {
223                    warn "can't open /etc/mtab: $!";
224            }
225    
226            return $mounted;
227    }
228    
229    
230  =head2 umount  =head2 umount
231    
232  Unmount your database as filesystem.  Unmount your database as filesystem.
# Line 156  database to filesystem. Line 241  database to filesystem.
241  sub umount {  sub umount {
242          my $self = shift;          my $self = shift;
243    
244          if ($self->{'mounted'}) {          if ($self->{'mount'} && $self->is_mounted) {
245                  system "fusermount -u ".$self->{'mount'} || croak "umount error: $!";                  system "fusermount -u ".$self->{'mount'}." 2>&1 >/dev/null" || return 0;
246                    return 1;
247          }          }
248    
249          return 1;          return 0;
250  }  }
251    
252  $SIG{'INT'} = sub {  $SIG{'INT'} = sub {
253          print STDERR "umount called by SIG INT\n";          if ($fuse_self && $$fuse_self->umount) {
254          umount;                  print STDERR "umount called by SIG INT\n";
255            }
256    };
257    
258    $SIG{'QUIT'} = sub {
259            if ($fuse_self && $$fuse_self->umount) {
260                    print STDERR "umount called by SIG QUIT\n";
261            }
262  };  };
263    
264  sub DESTROY {  sub DESTROY {
265          my $self = shift;          my $self = shift;
266          return if (! $self->{'mounted'});          if ($self->umount) {
267          print STDERR "umount called by DESTROY\n";                  print STDERR "umount called by DESTROY\n";
268          $self->umount;          }
269  }  }
270    
271  =head2 fuse_module_loaded  =head2 fuse_module_loaded
# Line 182  Checks if C<fuse> module is loaded in ke Line 275  Checks if C<fuse> module is loaded in ke
275    die "no fuse module loaded in kernel"    die "no fuse module loaded in kernel"
276          unless (Fuse::DBI::fuse_module_loaded);          unless (Fuse::DBI::fuse_module_loaded);
277    
278  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.
279    
280  =cut  =cut
281    
# Line 210  sub read_filenames { Line 303  sub read_filenames {
303                          type => 0040,                          type => 0040,
304                          mode => 0755,                          mode => 0755,
305                  },                  },
306                    '..' => {
307                            type => 0040,
308                            mode => 0755,
309                    },
310          #       a => {          #       a => {
311          #               cont => "File 'a'.\n",          #               cont => "File 'a'.\n",
312          #               type => 0100,          #               type => 0100,
# Line 288  sub e_getdir { Line 385  sub e_getdir {
385          my %out;          my %out;
386          foreach my $f (sort keys %files) {          foreach my $f (sort keys %files) {
387                  if ($dirname) {                  if ($dirname) {
388                          if ($f =~ s/^\E$dirname\Q\///) {                          if ($f =~ s/^\Q$dirname\E\///) {
389                                  $out{$f}++ if ($f =~ /^[^\/]+$/);                                  $out{$f}++ if ($f =~ /^[^\/]+$/);
390                          }                          }
391                  } else {                  } else {
# Line 310  sub read_content { Line 407  sub read_content {
407    
408          $sth->{'read'}->execute($id) || die $sth->{'read'}->errstr;          $sth->{'read'}->execute($id) || die $sth->{'read'}->errstr;
409          $files{$file}{cont} = $sth->{'read'}->fetchrow_array;          $files{$file}{cont} = $sth->{'read'}->fetchrow_array;
410          $files{$file}{ctime} = time();          # I should modify ctime only if content in database changed
411            #$files{$file}{ctime} = time() unless ($files{$file}{ctime});
412          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";
413  }  }
414    
# Line 356  sub clear_cont { Line 454  sub clear_cont {
454          print "invalidate all cached content\n";          print "invalidate all cached content\n";
455          foreach my $f (keys %files) {          foreach my $f (keys %files) {
456                  delete $files{$f}{cont};                  delete $files{$f}{cont};
457                    delete $files{$f}{ctime};
458          }          }
459          print "begin new transaction\n";          print "begin new transaction\n";
460          #$dbh->begin_work || die $dbh->errstr;          #$dbh->begin_work || die $dbh->errstr;
# Line 464  __END__ Line 563  __END__
563    
564  Nothing.  Nothing.
565    
566    =head1 BUGS
567    
568    Size information (C<ls -s>) is wrong. It's a problem in upstream Fuse module
569    (for which I'm to blame lately), so when it gets fixes, C<Fuse::DBI> will
570    automagically pick it up.
571    
572  =head1 SEE ALSO  =head1 SEE ALSO
573    
574  C<FUSE (Filesystem in USErspace)> website  C<FUSE (Filesystem in USErspace)> website
575  L<http://sourceforge.net/projects/avf>  L<http://fuse.sourceforge.net/>
576    
577    Example for WebGUI which comes with this distribution in
578    directory C<examples/webgui.pl>. It also contains a lot of documentation
579    about design of this module, usage and limitations.
580    
581  =head1 AUTHOR  =head1 AUTHOR
582    
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