/[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 31 by dpavlin, Sun Oct 10 19:33:23 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 = '0.04';
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    
# Line 32  This module will use C<Fuse> module, par Line 32  This module will use C<Fuse> module, par
32  available at L<http://sourceforge.net/projects/avf> to mount  available at L<http://sourceforge.net/projects/avf> 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            $self->{'mounted'} = 1;
173    
174            $fuse_self = \$self;
175    
176          Fuse::main(          Fuse::main(
177                  mountpoint=>$arg->{'mount'},                  mountpoint=>$arg->{'mount'},
178                  getattr=>\&e_getattr,                  getattr=>\&e_getattr,
# Line 115  sub mount { Line 184  sub mount {
184                  utime=>\&e_utime,                  utime=>\&e_utime,
185                  truncate=>\&e_truncate,                  truncate=>\&e_truncate,
186                  unlink=>\&e_unlink,                  unlink=>\&e_unlink,
187                    rmdir=>\&e_unlink,
188                  debug=>0,                  debug=>0,
189          );          );
190            
191            $self->{'mounted'} = 0;
192    
193          exit(0) if ($arg->{'fork'});          exit(0) if ($arg->{'fork'});
194    
# Line 138  database to filesystem. Line 210  database to filesystem.
210  sub umount {  sub umount {
211          my $self = shift;          my $self = shift;
212    
213          system "fusermount -u ".$self->{'mount'} || croak "umount error: $!";          if ($self->{'mounted'}) {
214                    system "fusermount -u ".$self->{'mount'} || croak "umount error: $!";
215            }
216    
217          return 1;          return 1;
218  }  }
219    
220    $SIG{'INT'} = sub {
221            print STDERR "umount called by SIG INT\n";
222            umount;
223    };
224    
225    sub DESTROY {
226            my $self = shift;
227            return if (! $self->{'mounted'});
228            print STDERR "umount called by DESTROY\n";
229            $self->umount;
230    }
231    
232  =head2 fuse_module_loaded  =head2 fuse_module_loaded
233    
234  Checks if C<fuse> module is loaded in kernel.  Checks if C<fuse> module is loaded in kernel.
# Line 150  Checks if C<fuse> module is loaded in ke Line 236  Checks if C<fuse> module is loaded in ke
236    die "no fuse module loaded in kernel"    die "no fuse module loaded in kernel"
237          unless (Fuse::DBI::fuse_module_loaded);          unless (Fuse::DBI::fuse_module_loaded);
238    
239  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.
240    
241  =cut  =cut
242    
# Line 170  my %dirs; Line 256  my %dirs;
256  sub read_filenames {  sub read_filenames {
257          my $self = shift;          my $self = shift;
258    
259            my $sth = $self->{'sth'} || die "no sth argument";
260    
261          # create empty filesystem          # create empty filesystem
262          (%files) = (          (%files) = (
263                  '.' => {                  '.' => {
# Line 276  sub read_content { Line 364  sub read_content {
364    
365          $sth->{'read'}->execute($id) || die $sth->{'read'}->errstr;          $sth->{'read'}->execute($id) || die $sth->{'read'}->errstr;
366          $files{$file}{cont} = $sth->{'read'}->fetchrow_array;          $files{$file}{cont} = $sth->{'read'}->fetchrow_array;
367            # I should modify ctime only if content in database changed
368            #$files{$file}{ctime} = time() unless ($files{$file}{ctime});
369          print "file '$file' content [",length($files{$file}{cont})," bytes] read in cache\n";          print "file '$file' content [",length($files{$file}{cont})," bytes] read in cache\n";
370  }  }
371    
# Line 321  sub clear_cont { Line 411  sub clear_cont {
411          print "invalidate all cached content\n";          print "invalidate all cached content\n";
412          foreach my $f (keys %files) {          foreach my $f (keys %files) {
413                  delete $files{$f}{cont};                  delete $files{$f}{cont};
414                    delete $files{$f}{ctime};
415          }          }
416          print "begin new transaction\n";          print "begin new transaction\n";
417          #$dbh->begin_work || die $dbh->errstr;          #$dbh->begin_work || die $dbh->errstr;
# Line 348  sub update_db { Line 439  sub update_db {
439                          return 0;                          return 0;
440                  }                  }
441                  print "updated '$file' [",$files{$file}{id},"]\n";                  print "updated '$file' [",$files{$file}{id},"]\n";
442    
443                    $$fuse_self->{'invalidate'}->() if (ref $$fuse_self->{'invalidate'});
444          }          }
445          return 1;          return 1;
446  }  }
# Line 407  sub e_statfs { return 255, 1, 1, 1, 1, 2 Line 500  sub e_statfs { return 255, 1, 1, 1, 1, 2
500  sub e_unlink {  sub e_unlink {
501          my $file = filename_fixup(shift);          my $file = filename_fixup(shift);
502    
503          return -ENOENT() unless exists($files{$file});          if (exists( $dirs{$file} )) {
504                    print "unlink '$file' will re-read template names\n";
505          print "unlink '$file' will invalidate cache\n";                  print Dumper($fuse_self);
506                    $$fuse_self->{'read_filenames'}->();
507          read_content($file,$files{$file}{id});                  return 0;
508            } elsif (exists( $files{$file} )) {
509                    print "unlink '$file' will invalidate cache\n";
510                    read_content($file,$files{$file}{id});
511                    return 0;
512            }
513    
514          return 0;          return -ENOENT();
515  }  }
516  1;  1;
517  __END__  __END__
# Line 427  Nothing. Line 525  Nothing.
525  C<FUSE (Filesystem in USErspace)> website  C<FUSE (Filesystem in USErspace)> website
526  L<http://sourceforge.net/projects/avf>  L<http://sourceforge.net/projects/avf>
527    
528    Example for WebGUI which comes with this distribution in
529    directory C<examples/webgui.pl>. It also contains a lot of documentation
530    about design of this module, usage and limitations.
531    
532  =head1 AUTHOR  =head1 AUTHOR
533    
534  Dobrica Pavlinusic, E<lt>dpavlin@rot13.orgE<gt>  Dobrica Pavlinusic, E<lt>dpavlin@rot13.orgE<gt>
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