/[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 22 by dpavlin, Sat Oct 2 16:30:16 2004 UTC revision 52 by dpavlin, Sat Nov 27 15:08:10 2004 UTC
# Line 12  use DBI; Line 12  use DBI;
12  use Carp;  use Carp;
13  use Data::Dumper;  use Data::Dumper;
14    
15    our $VERSION = '0.07';
16    
17  our $VERSION = '0.03';  # block size for this filesystem
18    use constant BLOCK => 1024;
19    
20  =head1 NAME  =head1 NAME
21    
# Line 24  Fuse::DBI - mount your database as files Line 26  Fuse::DBI - mount your database as files
26    use Fuse::DBI;    use Fuse::DBI;
27    Fuse::DBI->mount( ... );    Fuse::DBI->mount( ... );
28    
29  See L<run> below for examples how to set parametars.  See C<run> below for examples how to set parameters.
30    
31  =head1 DESCRIPTION  =head1 DESCRIPTION
32    
33  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)>
34  available at L<http://sourceforge.net/projects/avf> to mount  available at L<http://fuse.sourceforge.net/> to mount
35  your database as file system.  your database as file system.
36    
37  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)
38  to manipulate data in database.  to manipulate data in database.
39    
40  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 48  It's actually opposite of Oracle's inten
48    
49  Mount your database as filesystem.  Mount your database as filesystem.
50    
51    Let's suppose that your database have table C<files> with following structure:
52    
53     id:            int
54     filename:      text
55     size:          int
56     content:       text
57     writable:      boolean
58    
59    Following is example how to mount table like that to C</mnt>:
60    
61    my $mnt = Fuse::DBI->mount({    my $mnt = Fuse::DBI->mount({
62          filenames => 'select name from files_table as filenames',          'filenames' => 'select id,filename,size,writable from files',
63          read => 'sql read',          'read' => 'select content from files where id = ?',
64          update => 'sql update',          'update' => 'update files set content = ? where id = ?',
65          dsn => 'DBI:Pg:dbname=webgui',          'dsn' => 'DBI:Pg:dbname=test_db',
66          user => 'database_user',          'user' => 'database_user',
67          password => 'database_password'          'password' => 'database_password',
68            'invalidate' => sub { ... },
69    });    });
70    
71    Options:
72    
73    =over 5
74    
75    =item filenames
76    
77    SQL query which returns C<id> (unique id for that row), C<filename>,
78    C<size> and C<writable> boolean flag.
79    
80    =item read
81    
82    SQL query which returns only one column with content of file and has
83    placeholder C<?> for C<id>.
84    
85    =item update
86    
87    SQL query with two pace-holders, one for new content and one for C<id>.
88    
89    =item dsn
90    
91    C<DBI> dsn to connect to (contains database driver and name of database).
92    
93    =item user
94    
95    User with which to connect to database
96    
97    =item password
98    
99    Password for connecting to database
100    
101    =item invalidate
102    
103    Optional anonymous code reference which will be executed when data is updated in
104    database. It can be used as hook to delete cache (for example on-disk-cache)
105    which is created from data edited through C<Fuse::DBI>.
106    
107    =item fork
108    
109    Optional flag which forks after mount so that executing script will continue
110    running. Implementation is experimental.
111    
112    =back
113    
114  =cut  =cut
115    
116  my $dbh;  my $dbh;
# Line 64  my $ctime_start; Line 120  my $ctime_start;
120  sub read_filenames;  sub read_filenames;
121  sub fuse_module_loaded;  sub fuse_module_loaded;
122    
123    # evil, evil way to solve this. It makes this module non-reentrant. But, since
124    # fuse calls another copy of this script for each mount anyway, this shouldn't
125    # be a problem.
126    my $fuse_self;
127    
128  sub mount {  sub mount {
129          my $class = shift;          my $class = shift;
130          my $self = {};          my $self = {};
# Line 73  sub mount { Line 134  sub mount {
134    
135          print Dumper($arg);          print Dumper($arg);
136    
137            unless ($self->fuse_module_loaded) {
138                    print STDERR "no fuse module loaded. Trying sudo modprobe fuse!\n";
139                    system "sudo modprobe fuse" || die "can't modprobe fuse using sudo!\n";
140            }
141    
142          carp "mount needs 'dsn' to connect to (e.g. dsn => 'DBI:Pg:dbname=test')" unless ($arg->{'dsn'});          carp "mount needs 'dsn' to connect to (e.g. dsn => 'DBI:Pg:dbname=test')" unless ($arg->{'dsn'});
143          carp "mount needs 'mount' as mountpoint" unless ($arg->{'mount'});          carp "mount needs 'mount' as mountpoint" unless ($arg->{'mount'});
144    
145          # save (some) arguments in self          # save (some) arguments in self
146          $self->{$_} = $arg->{$_} foreach (qw(mount));          foreach (qw(mount invalidate)) {
147                    $self->{$_} = $arg->{$_};
148            }
149    
150          foreach (qw(filenames read update)) {          foreach (qw(filenames read update)) {
151                  carp "mount needs '$_' SQL" unless ($arg->{$_});                  carp "mount needs '$_' SQL" unless ($arg->{$_});
# Line 91  sub mount { Line 159  sub mount {
159                  die "fork() failed: $!" unless defined $pid;                  die "fork() failed: $!" unless defined $pid;
160                  # child will return to caller                  # child will return to caller
161                  if ($pid) {                  if ($pid) {
162                          return $self;                          my $counter = 4;
163                            while ($counter && ! $self->is_mounted) {
164                                    select(undef, undef, undef, 0.5);
165                                    $counter--;
166                            }
167                            if ($self->is_mounted) {
168                                    return $self;
169                            } else {
170                                    return undef;
171                            }
172                  }                  }
173          }          }
174    
175          $dbh = DBI->connect($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;
176    
177          $sth->{filenames} = $dbh->prepare($arg->{'filenames'}) || die $dbh->errstr();          $sth->{'filenames'} = $dbh->prepare($arg->{'filenames'}) || die $dbh->errstr();
178    
179          $sth->{'read'} = $dbh->prepare($arg->{'read'}) || die $dbh->errstr();          $sth->{'read'} = $dbh->prepare($arg->{'read'}) || die $dbh->errstr();
180          $sth->{'update'} = $dbh->prepare($arg->{'update'}) || die $dbh->errstr();          $sth->{'update'} = $dbh->prepare($arg->{'update'}) || die $dbh->errstr();
181    
182    
183            $self->{'sth'} = $sth;
184    
185            $self->{'read_filenames'} = sub { $self->read_filenames };
186          $self->read_filenames;          $self->read_filenames;
187    
188            $fuse_self = \$self;
189    
190          Fuse::main(          Fuse::main(
191                  mountpoint=>$arg->{'mount'},                  mountpoint=>$arg->{'mount'},
192                  getattr=>\&e_getattr,                  getattr=>\&e_getattr,
# Line 115  sub mount { Line 198  sub mount {
198                  utime=>\&e_utime,                  utime=>\&e_utime,
199                  truncate=>\&e_truncate,                  truncate=>\&e_truncate,
200                  unlink=>\&e_unlink,                  unlink=>\&e_unlink,
201                    rmdir=>\&e_unlink,
202                  debug=>0,                  debug=>0,
203          );          );
204            
205          exit(0) if ($arg->{'fork'});          exit(0) if ($arg->{'fork'});
206    
207          return 1;          return 1;
208    
209  };  };
210    
211    =head2 is_mounted
212    
213    Check if fuse filesystem is mounted
214    
215      if ($mnt->is_mounted) { ... }
216    
217    =cut
218    
219    sub is_mounted {
220            my $self = shift;
221    
222            my $mounted = 0;
223            my $mount = $self->{'mount'} || confess "can't find mount point!";
224            if (open(MTAB, "/etc/mtab")) {
225                    while(<MTAB>) {
226                            $mounted = 1 if (/ $mount fuse /i);
227                    }
228                    close(MTAB);
229            } else {
230                    warn "can't open /etc/mtab: $!";
231            }
232    
233            return $mounted;
234    }
235    
236    
237  =head2 umount  =head2 umount
238    
239  Unmount your database as filesystem.  Unmount your database as filesystem.
# Line 138  database to filesystem. Line 248  database to filesystem.
248  sub umount {  sub umount {
249          my $self = shift;          my $self = shift;
250    
251          system "fusermount -u ".$self->{'mount'} || croak "umount error: $!";          if ($self->{'mount'} && $self->is_mounted) {
252                    system "( fusermount -u ".$self->{'mount'}." 2>&1 ) >/dev/null" ||
253                            system "sudo umount ".$self->{'mount'} ||
254                            return 0;
255                    return 1;
256            }
257    
258          return 1;          return 0;
259    }
260    
261    $SIG{'INT'} = sub {
262            if ($fuse_self && $$fuse_self->umount) {
263                    print STDERR "umount called by SIG INT\n";
264            }
265    };
266    
267    $SIG{'QUIT'} = sub {
268            if ($fuse_self && $$fuse_self->umount) {
269                    print STDERR "umount called by SIG QUIT\n";
270            }
271    };
272    
273    sub DESTROY {
274            my $self = shift;
275            if ($self->umount) {
276                    print STDERR "umount called by DESTROY\n";
277            }
278  }  }
279    
280  =head2 fuse_module_loaded  =head2 fuse_module_loaded
# Line 150  Checks if C<fuse> module is loaded in ke Line 284  Checks if C<fuse> module is loaded in ke
284    die "no fuse module loaded in kernel"    die "no fuse module loaded in kernel"
285          unless (Fuse::DBI::fuse_module_loaded);          unless (Fuse::DBI::fuse_module_loaded);
286    
287  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.
288    
289  =cut  =cut
290    
# Line 165  sub fuse_module_loaded { Line 299  sub fuse_module_loaded {
299  }  }
300    
301  my %files;  my %files;
 my %dirs;  
302    
303  sub read_filenames {  sub read_filenames {
304          my $self = shift;          my $self = shift;
305    
306            my $sth = $self->{'sth'} || die "no sth argument";
307    
308          # create empty filesystem          # create empty filesystem
309          (%files) = (          (%files) = (
310                  '.' => {                  '.' => {
311                          type => 0040,                          type => 0040,
312                          mode => 0755,                          mode => 0755,
313                  },                  },
314                    '..' => {
315                            type => 0040,
316                            mode => 0755,
317                    },
318          #       a => {          #       a => {
319          #               cont => "File 'a'.\n",          #               cont => "File 'a'.\n",
320          #               type => 0100,          #               type => 0100,
# Line 199  sub read_filenames { Line 338  sub read_filenames {
338                          # first, entry is assumed to be file                          # first, entry is assumed to be file
339                          if ($d) {                          if ($d) {
340                                  $files{$d} = {                                  $files{$d} = {
                                                 size => $dirs{$d}++,  
341                                                  mode => 0755,                                                  mode => 0755,
342                                                  type => 0040                                                  type => 0040
343                                  };                                  };
# Line 217  sub read_filenames { Line 355  sub read_filenames {
355                  }                  }
356          }          }
357    
358          print "found ",scalar(keys %files)-scalar(keys %dirs)," files, ",scalar(keys %dirs), " dirs\n";          print "found ",scalar(keys %files)," files\n";
359  }  }
360    
361    
# Line 233  sub e_getattr { Line 371  sub e_getattr {
371          $file =~ s,^/,,;          $file =~ s,^/,,;
372          $file = '.' unless length($file);          $file = '.' unless length($file);
373          return -ENOENT() unless exists($files{$file});          return -ENOENT() unless exists($files{$file});
374          my ($size) = $files{$file}{size} || 1;          my ($size) = $files{$file}{size} || BLOCK;
375          my ($dev, $ino, $rdev, $blocks, $gid, $uid, $nlink, $blksize) = (0,0,0,1,0,0,1,1024);          my ($dev, $ino, $rdev, $blocks, $gid, $uid, $nlink, $blksize) = (0,0,0,int(($size+BLOCK-1)/BLOCK),0,0,1,BLOCK);
376          my ($atime, $ctime, $mtime);          my ($atime, $ctime, $mtime);
377          $atime = $ctime = $mtime = $files{$file}{ctime} || $ctime_start;          $atime = $ctime = $mtime = $files{$file}{ctime} || $ctime_start;
378    
# Line 242  sub e_getattr { Line 380  sub e_getattr {
380    
381          # 2 possible types of return values:          # 2 possible types of return values:
382          #return -ENOENT(); # or any other error you care to          #return -ENOENT(); # or any other error you care to
383          #print(join(",",($dev,$ino,$modes,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks)),"\n");          print "getattr($file) ",join(",",($dev,$ino,$modes,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks)),"\n";
384          return ($dev,$ino,$modes,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks);          return ($dev,$ino,$modes,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks);
385  }  }
386    
# Line 254  sub e_getdir { Line 392  sub e_getdir {
392          my %out;          my %out;
393          foreach my $f (sort keys %files) {          foreach my $f (sort keys %files) {
394                  if ($dirname) {                  if ($dirname) {
395                          if ($f =~ s/^\E$dirname\Q\///) {                          if ($f =~ s/^\Q$dirname\E\///) {
396                                  $out{$f}++ if ($f =~ /^[^\/]+$/);                                  $out{$f}++ if ($f =~ /^[^\/]+$/);
397                          }                          }
398                  } else {                  } else {
# Line 276  sub read_content { Line 414  sub read_content {
414    
415          $sth->{'read'}->execute($id) || die $sth->{'read'}->errstr;          $sth->{'read'}->execute($id) || die $sth->{'read'}->errstr;
416          $files{$file}{cont} = $sth->{'read'}->fetchrow_array;          $files{$file}{cont} = $sth->{'read'}->fetchrow_array;
417            # I should modify ctime only if content in database changed
418            #$files{$file}{ctime} = time() unless ($files{$file}{ctime});
419          print "file '$file' content [",length($files{$file}{cont})," bytes] read in cache\n";          print "file '$file' content [",length($files{$file}{cont})," bytes] read in cache\n";
420  }  }
421    
# Line 321  sub clear_cont { Line 461  sub clear_cont {
461          print "invalidate all cached content\n";          print "invalidate all cached content\n";
462          foreach my $f (keys %files) {          foreach my $f (keys %files) {
463                  delete $files{$f}{cont};                  delete $files{$f}{cont};
464                    delete $files{$f}{ctime};
465          }          }
466          print "begin new transaction\n";          print "begin new transaction\n";
467          #$dbh->begin_work || die $dbh->errstr;          #$dbh->begin_work || die $dbh->errstr;
# Line 348  sub update_db { Line 489  sub update_db {
489                          return 0;                          return 0;
490                  }                  }
491                  print "updated '$file' [",$files{$file}{id},"]\n";                  print "updated '$file' [",$files{$file}{id},"]\n";
492    
493                    $$fuse_self->{'invalidate'}->() if (ref $$fuse_self->{'invalidate'});
494          }          }
495          return 1;          return 1;
496  }  }
# Line 402  sub e_utime { Line 545  sub e_utime {
545          return 0;          return 0;
546  }  }
547    
548  sub e_statfs { return 255, 1, 1, 1, 1, 2 }  sub e_statfs {
549    
550  sub e_unlink {          my $size = 0;
551          my $file = filename_fixup(shift);          my $inodes = 0;
552    
553          return -ENOENT() unless exists($files{$file});          foreach my $f (keys %files) {
554                    if ($f !~ /(^|\/)\.\.?$/) {
555                            $size += $files{$f}{size} || 0;
556                            $inodes++;
557                    }
558                    print "$inodes: $f [$size]\n";
559            }
560    
561          print "unlink '$file' will invalidate cache\n";          $size = int(($size+BLOCK-1)/BLOCK);
562    
563          read_content($file,$files{$file}{id});          my @ret = (255, $inodes, 1, $size, $size-1, BLOCK);
564    
565          return 0;          print "statfs: ",join(",",@ret),"\n";
566    
567            return @ret;
568    }
569    
570    sub e_unlink {
571            my $file = filename_fixup(shift);
572    
573    #       if (exists( $dirs{$file} )) {
574    #               print "unlink '$file' will re-read template names\n";
575    #               print Dumper($fuse_self);
576    #               $$fuse_self->{'read_filenames'}->();
577    #               return 0;
578            if (exists( $files{$file} )) {
579                    print "unlink '$file' will invalidate cache\n";
580                    read_content($file,$files{$file}{id});
581                    return 0;
582            }
583    
584            return -ENOENT();
585  }  }
586  1;  1;
587  __END__  __END__
# Line 422  __END__ Line 590  __END__
590    
591  Nothing.  Nothing.
592    
593    =head1 BUGS
594    
595    Size information (C<ls -s>) is wrong. It's a problem in upstream Fuse module
596    (for which I'm to blame lately), so when it gets fixes, C<Fuse::DBI> will
597    automagically pick it up.
598    
599  =head1 SEE ALSO  =head1 SEE ALSO
600    
601  C<FUSE (Filesystem in USErspace)> website  C<FUSE (Filesystem in USErspace)> website
602  L<http://sourceforge.net/projects/avf>  L<http://fuse.sourceforge.net/>
603    
604    Example for WebGUI which comes with this distribution in
605    directory C<examples/webgui.pl>. It also contains a lot of documentation
606    about design of this module, usage and limitations.
607    
608  =head1 AUTHOR  =head1 AUTHOR
609    
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