/[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 21 by dpavlin, Sat Oct 2 15:29:02 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 L<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 L<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 85  sub mount { Line 146  sub mount {
146    
147          $ctime_start = time();          $ctime_start = time();
148    
149            my $pid;
150          if ($arg->{'fork'}) {          if ($arg->{'fork'}) {
151                  my $pid = fork();                  $pid = fork();
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                          $self ? return $self : return undef;                          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    
168          $dbh = DBI->connect($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;
169    
170          $sth->{filenames} = $dbh->prepare($arg->{'filenames'}) || die $dbh->errstr();          $sth->{'filenames'} = $dbh->prepare($arg->{'filenames'}) || die $dbh->errstr();
171    
172          $sth->{'read'} = $dbh->prepare($arg->{'read'}) || die $dbh->errstr();          $sth->{'read'} = $dbh->prepare($arg->{'read'}) || die $dbh->errstr();
173          $sth->{'update'} = $dbh->prepare($arg->{'update'}) || die $dbh->errstr();          $sth->{'update'} = $dbh->prepare($arg->{'update'}) || die $dbh->errstr();
174    
175    
176            $self->{'sth'} = $sth;
177    
178            $self->{'read_filenames'} = sub { $self->read_filenames };
179          $self->read_filenames;          $self->read_filenames;
180    
181          my $mount = Fuse::main(          $fuse_self = \$self;
182    
183            Fuse::main(
184                  mountpoint=>$arg->{'mount'},                  mountpoint=>$arg->{'mount'},
185                  getattr=>\&e_getattr,                  getattr=>\&e_getattr,
186                  getdir=>\&e_getdir,                  getdir=>\&e_getdir,
# Line 114  sub mount { Line 191  sub mount {
191                  utime=>\&e_utime,                  utime=>\&e_utime,
192                  truncate=>\&e_truncate,                  truncate=>\&e_truncate,
193                  unlink=>\&e_unlink,                  unlink=>\&e_unlink,
194                    rmdir=>\&e_unlink,
195                  debug=>0,                  debug=>0,
196          );          );
197            
198            exit(0) if ($arg->{'fork'});
199    
200            return 1;
201    
         if (! $mount) {  
                 warn "mount on ",$arg->{'mount'}," failed!\n";  
                 return undef;  
         }  
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 137  database to filesystem. Line 241  database to filesystem.
241  sub umount {  sub umount {
242          my $self = shift;          my $self = shift;
243    
244          system "fusermount -u ".$self->{'mount'} || croak "umount error: $!";          if ($self->{'mount'} && $self->is_mounted) {
245                    system "fusermount -u ".$self->{'mount'}." 2>&1 >/dev/null" || return 0;
246                    return 1;
247            }
248    
249          return 1;          return 0;
250    }
251    
252    $SIG{'INT'} = sub {
253            if ($fuse_self && $$fuse_self->umount) {
254                    print STDERR "umount called by SIG INT\n";
255            }
256    };
257    
258    $SIG{'QUIT'} = sub {
259            if ($fuse_self && $$fuse_self->umount) {
260                    print STDERR "umount called by SIG QUIT\n";
261            }
262    };
263    
264    sub DESTROY {
265            my $self = shift;
266            if ($self->umount) {
267                    print STDERR "umount called by DESTROY\n";
268            }
269  }  }
270    
271  =head2 fuse_module_loaded  =head2 fuse_module_loaded
# Line 149  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 169  my %dirs; Line 295  my %dirs;
295  sub read_filenames {  sub read_filenames {
296          my $self = shift;          my $self = shift;
297    
298            my $sth = $self->{'sth'} || die "no sth argument";
299    
300          # create empty filesystem          # create empty filesystem
301          (%files) = (          (%files) = (
302                  '.' => {                  '.' => {
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 253  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 275  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} = $sth->{'read'}->fetchrow_array;
410            # I should modify ctime only if content in database changed
411            #$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 320  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 $dbh->errstr;
# Line 347  sub update_db { Line 482  sub update_db {
482                          return 0;                          return 0;
483                  }                  }
484                  print "updated '$file' [",$files{$file}{id},"]\n";                  print "updated '$file' [",$files{$file}{id},"]\n";
485    
486                    $$fuse_self->{'invalidate'}->() if (ref $$fuse_self->{'invalidate'});
487          }          }
488          return 1;          return 1;
489  }  }
# Line 406  sub e_statfs { return 255, 1, 1, 1, 1, 2 Line 543  sub e_statfs { return 255, 1, 1, 1, 1, 2
543  sub e_unlink {  sub e_unlink {
544          my $file = filename_fixup(shift);          my $file = filename_fixup(shift);
545    
546          return -ENOENT() unless exists($files{$file});          if (exists( $dirs{$file} )) {
547                    print "unlink '$file' will re-read template names\n";
548          print "unlink '$file' will invalidate cache\n";                  print Dumper($fuse_self);
549                    $$fuse_self->{'read_filenames'}->();
550          read_content($file,$files{$file}{id});                  return 0;
551            } elsif (exists( $files{$file} )) {
552                    print "unlink '$file' will invalidate cache\n";
553                    read_content($file,$files{$file}{id});
554                    return 0;
555            }
556    
557          return 0;          return -ENOENT();
558  }  }
559  1;  1;
560  __END__  __END__
# Line 421  __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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