/[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 55 by dpavlin, Tue Apr 26 20:12:55 2005 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 = '0.08';
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 C<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 C<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                    if ($self->is_mounted) {
254                            system "sudo umount ".$self->{'mount'} ||
255                            return 0;
256                    }
257                    return 1;
258            }
259    
260          return 1;          return 0;
261    }
262    
263    $SIG{'INT'} = sub {
264            if ($fuse_self && $$fuse_self->umount) {
265                    print STDERR "umount called by SIG INT\n";
266            }
267    };
268    
269    $SIG{'QUIT'} = sub {
270            if ($fuse_self && $$fuse_self->umount) {
271                    print STDERR "umount called by SIG QUIT\n";
272            }
273    };
274    
275    sub DESTROY {
276            my $self = shift;
277            if ($self->umount) {
278                    print STDERR "umount called by DESTROY\n";
279            }
280  }  }
281    
282  =head2 fuse_module_loaded  =head2 fuse_module_loaded
# Line 150  Checks if C<fuse> module is loaded in ke Line 286  Checks if C<fuse> module is loaded in ke
286    die "no fuse module loaded in kernel"    die "no fuse module loaded in kernel"
287          unless (Fuse::DBI::fuse_module_loaded);          unless (Fuse::DBI::fuse_module_loaded);
288    
289  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.
290    
291  =cut  =cut
292    
# Line 165  sub fuse_module_loaded { Line 301  sub fuse_module_loaded {
301  }  }
302    
303  my %files;  my %files;
 my %dirs;  
304    
305  sub read_filenames {  sub read_filenames {
306          my $self = shift;          my $self = shift;
307    
308            my $sth = $self->{'sth'} || die "no sth argument";
309    
310          # create empty filesystem          # create empty filesystem
311          (%files) = (          (%files) = (
312                  '.' => {                  '.' => {
313                          type => 0040,                          type => 0040,
314                          mode => 0755,                          mode => 0755,
315                  },                  },
316                    '..' => {
317                            type => 0040,
318                            mode => 0755,
319                    },
320          #       a => {          #       a => {
321          #               cont => "File 'a'.\n",          #               cont => "File 'a'.\n",
322          #               type => 0100,          #               type => 0100,
# Line 188  sub read_filenames { Line 329  sub read_filenames {
329    
330          # read them in with sesible defaults          # read them in with sesible defaults
331          while (my $row = $sth->{'filenames'}->fetchrow_hashref() ) {          while (my $row = $sth->{'filenames'}->fetchrow_hashref() ) {
332                    $row->{'filename'} ||= 'NULL-'.$row->{'id'};
333                  $files{$row->{'filename'}} = {                  $files{$row->{'filename'}} = {
334                          size => $row->{'size'},                          size => $row->{'size'},
335                          mode => $row->{'writable'} ? 0644 : 0444,                          mode => $row->{'writable'} ? 0644 : 0444,
336                          id => $row->{'id'} || 99,                          id => $row->{'id'} || 99,
337                  };                  };
338    
339    
340                  my $d;                  my $d;
341                  foreach (split(m!/!, $row->{'filename'})) {                  foreach (split(m!/!, $row->{'filename'})) {
342                          # first, entry is assumed to be file                          # first, entry is assumed to be file
343                          if ($d) {                          if ($d) {
344                                  $files{$d} = {                                  $files{$d} = {
                                                 size => $dirs{$d}++,  
345                                                  mode => 0755,                                                  mode => 0755,
346                                                  type => 0040                                                  type => 0040
347                                  };                                  };
# Line 217  sub read_filenames { Line 359  sub read_filenames {
359                  }                  }
360          }          }
361    
362          print "found ",scalar(keys %files)-scalar(keys %dirs)," files, ",scalar(keys %dirs), " dirs\n";          print "found ",scalar(keys %files)," files\n";
363  }  }
364    
365    
# Line 233  sub e_getattr { Line 375  sub e_getattr {
375          $file =~ s,^/,,;          $file =~ s,^/,,;
376          $file = '.' unless length($file);          $file = '.' unless length($file);
377          return -ENOENT() unless exists($files{$file});          return -ENOENT() unless exists($files{$file});
378          my ($size) = $files{$file}{size} || 1;          my ($size) = $files{$file}{size} || 0;
379          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);
380          my ($atime, $ctime, $mtime);          my ($atime, $ctime, $mtime);
381          $atime = $ctime = $mtime = $files{$file}{ctime} || $ctime_start;          $atime = $ctime = $mtime = $files{$file}{ctime} || $ctime_start;
382    
# Line 242  sub e_getattr { Line 384  sub e_getattr {
384    
385          # 2 possible types of return values:          # 2 possible types of return values:
386          #return -ENOENT(); # or any other error you care to          #return -ENOENT(); # or any other error you care to
387          #print(join(",",($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";
388          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);
389  }  }
390    
# Line 254  sub e_getdir { Line 396  sub e_getdir {
396          my %out;          my %out;
397          foreach my $f (sort keys %files) {          foreach my $f (sort keys %files) {
398                  if ($dirname) {                  if ($dirname) {
399                          if ($f =~ s/^\E$dirname\Q\///) {                          if ($f =~ s/^\Q$dirname\E\///) {
400                                  $out{$f}++ if ($f =~ /^[^\/]+$/);                                  $out{$f}++ if ($f =~ /^[^\/]+$/);
401                          }                          }
402                  } else {                  } else {
# Line 276  sub read_content { Line 418  sub read_content {
418    
419          $sth->{'read'}->execute($id) || die $sth->{'read'}->errstr;          $sth->{'read'}->execute($id) || die $sth->{'read'}->errstr;
420          $files{$file}{cont} = $sth->{'read'}->fetchrow_array;          $files{$file}{cont} = $sth->{'read'}->fetchrow_array;
421            # I should modify ctime only if content in database changed
422            #$files{$file}{ctime} = time() unless ($files{$file}{ctime});
423          print "file '$file' content [",length($files{$file}{cont})," bytes] read in cache\n";          print "file '$file' content [",length($files{$file}{cont})," bytes] read in cache\n";
424  }  }
425    
# Line 290  sub e_open { Line 434  sub e_open {
434    
435          read_content($file,$files{$file}{id}) unless exists($files{$file}{cont});          read_content($file,$files{$file}{id}) unless exists($files{$file}{cont});
436    
437            $files{$file}{cont} ||= '';
438          print "open '$file' ",length($files{$file}{cont})," bytes\n";          print "open '$file' ",length($files{$file}{cont})," bytes\n";
439          return 0;          return 0;
440  }  }
# Line 321  sub clear_cont { Line 466  sub clear_cont {
466          print "invalidate all cached content\n";          print "invalidate all cached content\n";
467          foreach my $f (keys %files) {          foreach my $f (keys %files) {
468                  delete $files{$f}{cont};                  delete $files{$f}{cont};
469                    delete $files{$f}{ctime};
470          }          }
471          print "begin new transaction\n";          print "begin new transaction\n";
472          #$dbh->begin_work || die $dbh->errstr;          #$dbh->begin_work || die $dbh->errstr;
# Line 348  sub update_db { Line 494  sub update_db {
494                          return 0;                          return 0;
495                  }                  }
496                  print "updated '$file' [",$files{$file}{id},"]\n";                  print "updated '$file' [",$files{$file}{id},"]\n";
497    
498                    $$fuse_self->{'invalidate'}->() if (ref $$fuse_self->{'invalidate'});
499          }          }
500          return 1;          return 1;
501  }  }
# Line 402  sub e_utime { Line 550  sub e_utime {
550          return 0;          return 0;
551  }  }
552    
553  sub e_statfs { return 255, 1, 1, 1, 1, 2 }  sub e_statfs {
554    
555  sub e_unlink {          my $size = 0;
556          my $file = filename_fixup(shift);          my $inodes = 0;
557    
558          return -ENOENT() unless exists($files{$file});          foreach my $f (keys %files) {
559                    if ($f !~ /(^|\/)\.\.?$/) {
560                            $size += $files{$f}{size} || 0;
561                            $inodes++;
562                    }
563                    print "$inodes: $f [$size]\n";
564            }
565    
566          print "unlink '$file' will invalidate cache\n";          $size = int(($size+BLOCK-1)/BLOCK);
567    
568          read_content($file,$files{$file}{id});          my @ret = (255, $inodes, 1, $size, $size-1, BLOCK);
569    
570          return 0;          #print "statfs: ",join(",",@ret),"\n";
571    
572            return @ret;
573    }
574    
575    sub e_unlink {
576            my $file = filename_fixup(shift);
577    
578    #       if (exists( $dirs{$file} )) {
579    #               print "unlink '$file' will re-read template names\n";
580    #               print Dumper($fuse_self);
581    #               $$fuse_self->{'read_filenames'}->();
582    #               return 0;
583            if (exists( $files{$file} )) {
584                    print "unlink '$file' will invalidate cache\n";
585                    read_content($file,$files{$file}{id});
586                    return 0;
587            }
588    
589            return -ENOENT();
590  }  }
591  1;  1;
592  __END__  __END__
# Line 422  __END__ Line 595  __END__
595    
596  Nothing.  Nothing.
597    
598    =head1 BUGS
599    
600    Size information (C<ls -s>) is wrong. It's a problem in upstream Fuse module
601    (for which I'm to blame lately), so when it gets fixes, C<Fuse::DBI> will
602    automagically pick it up.
603    
604  =head1 SEE ALSO  =head1 SEE ALSO
605    
606  C<FUSE (Filesystem in USErspace)> website  C<FUSE (Filesystem in USErspace)> website
607  L<http://sourceforge.net/projects/avf>  L<http://fuse.sourceforge.net/>
608    
609    Example for WebGUI which comes with this distribution in
610    directory C<examples/webgui.pl>. It also contains a lot of documentation
611    about design of this module, usage and limitations.
612    
613  =head1 AUTHOR  =head1 AUTHOR
614    
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