/[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 13 by dpavlin, Sun Aug 29 20:12:37 2004 UTC revision 51 by dpavlin, Sat Nov 27 14:02:18 2004 UTC
# Line 10  use POSIX qw(ENOENT EISDIR EINVAL ENOSYS Line 10  use POSIX qw(ENOENT EISDIR EINVAL ENOSYS
10  use Fuse;  use Fuse;
11  use DBI;  use DBI;
12  use Carp;  use Carp;
 use Proc::Simple;  
13  use Data::Dumper;  use Data::Dumper;
14    
15    
16  our $VERSION = '0.01';  our $VERSION = '0.07';
17    
18  =head1 NAME  =head1 NAME
19    
# Line 25  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 47  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 filenamefilenames,          '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 63  my $sth; Line 116  my $sth;
116  my $ctime_start;  my $ctime_start;
117    
118  sub read_filenames;  sub read_filenames;
119    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 $class = shift;
# Line 73  sub mount { Line 132  sub mount {
132    
133          print Dumper($arg);          print Dumper($arg);
134    
135            unless ($self->fuse_module_loaded) {
136                    print STDERR "no fuse module loaded. Trying sudo modprobe fuse!\n";
137                    system "sudo modprobe fuse" || die "can't modprobe fuse using sudo!\n";
138            }
139    
140          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'});
141          carp "mount needs 'mount' as mountpoint" unless ($arg->{'mount'});          carp "mount needs 'mount' as mountpoint" unless ($arg->{'mount'});
142    
143          # save (some) arguments in self          # save (some) arguments in self
144          $self->{$_} = $arg->{$_} foreach (qw(mount));          foreach (qw(mount invalidate)) {
145                    $self->{$_} = $arg->{$_};
146            }
147    
148          foreach (qw(filenames read update)) {          foreach (qw(filenames read update)) {
149                  carp "mount needs '$_' SQL" unless ($arg->{$_});                  carp "mount needs '$_' SQL" unless ($arg->{$_});
150          }          }
151    
152          $dbh = DBI->connect($arg->{'dsn'},$arg->{'user'},$arg->{'password'}, { AutoCommit => 0 }) || die $DBI::errstr;          $ctime_start = time();
153    
154          print "start transaction\n";          my $pid;
155          #$dbh->begin_work || die $dbh->errstr;          if ($arg->{'fork'}) {
156                    $pid = fork();
157                    die "fork() failed: $!" unless defined $pid;
158                    # child will return to caller
159                    if ($pid) {
160                            my $counter = 4;
161                            while ($counter && ! $self->is_mounted) {
162                                    select(undef, undef, undef, 0.5);
163                                    $counter--;
164                            }
165                            if ($self->is_mounted) {
166                                    return $self;
167                            } else {
168                                    return undef;
169                            }
170                    }
171            }
172    
173            $dbh = DBI->connect($arg->{'dsn'},$arg->{'user'},$arg->{'password'}, {AutoCommit => 0, RaiseError => 1}) || die $DBI::errstr;
174    
175          $sth->{filenames} = $dbh->prepare($arg->{'filenames'}) || die $dbh->errstr();          $sth->{'filenames'} = $dbh->prepare($arg->{'filenames'}) || die $dbh->errstr();
176    
177          $sth->{'read'} = $dbh->prepare($arg->{'read'}) || die $dbh->errstr();          $sth->{'read'} = $dbh->prepare($arg->{'read'}) || die $dbh->errstr();
178          $sth->{'update'} = $dbh->prepare($arg->{'update'}) || die $dbh->errstr();          $sth->{'update'} = $dbh->prepare($arg->{'update'}) || die $dbh->errstr();
179    
         $ctime_start = time();  
180    
181          read_filenames;          $self->{'sth'} = $sth;
182    
183            $self->{'read_filenames'} = sub { $self->read_filenames };
184            $self->read_filenames;
185    
186          $self->{'proc'} = Proc::Simple->new();          $fuse_self = \$self;
         $self->{'proc'}->kill_on_destroy(1);  
187    
188          $self->{'proc'}->start( sub {          Fuse::main(
189                  Fuse::main(                  mountpoint=>$arg->{'mount'},
190                          mountpoint=>$arg->{'mount'},                  getattr=>\&e_getattr,
191                          getattr=>\&e_getattr,                  getdir=>\&e_getdir,
192                          getdir=>\&e_getdir,                  open=>\&e_open,
193                          open=>\&e_open,                  statfs=>\&e_statfs,
194                          statfs=>\&e_statfs,                  read=>\&e_read,
195                          read=>\&e_read,                  write=>\&e_write,
196                          write=>\&e_write,                  utime=>\&e_utime,
197                          utime=>\&e_utime,                  truncate=>\&e_truncate,
198                          truncate=>\&e_truncate,                  unlink=>\&e_unlink,
199                          debug=>0,                  rmdir=>\&e_unlink,
200                  );                  debug=>0,
201          } );          );
202            
203            exit(0) if ($arg->{'fork'});
204    
205          confess "Fuse::main failed" if (! $self->{'proc'}->poll);          return 1;
206    
         $self ? return $self : return undef;  
207  };  };
208    
209    =head2 is_mounted
210    
211    Check if fuse filesystem is mounted
212    
213      if ($mnt->is_mounted) { ... }
214    
215    =cut
216    
217    sub is_mounted {
218            my $self = shift;
219    
220            my $mounted = 0;
221            my $mount = $self->{'mount'} || confess "can't find mount point!";
222            if (open(MTAB, "/etc/mtab")) {
223                    while(<MTAB>) {
224                            $mounted = 1 if (/ $mount fuse /i);
225                    }
226                    close(MTAB);
227            } else {
228                    warn "can't open /etc/mtab: $!";
229            }
230    
231            return $mounted;
232    }
233    
234    
235  =head2 umount  =head2 umount
236    
237  Unmount your database as filesystem.  Unmount your database as filesystem.
# Line 134  database to filesystem. Line 246  database to filesystem.
246  sub umount {  sub umount {
247          my $self = shift;          my $self = shift;
248    
249          confess "no process running?" unless ($self->{'proc'});          if ($self->{'mount'} && $self->is_mounted) {
250                    system "fusermount -u ".$self->{'mount'}." 2>&1 >/dev/null" ||
251                            system "sudo umount ".$self->{'mount'} ||
252                            return 0;
253                    return 1;
254            }
255    
256          system "fusermount -u ".$self->{'mount'} || croak "umount error: $!";          return 0;
257    }
258    
259          if ($self->{'proc'}->poll) {  $SIG{'INT'} = sub {
260                  $self->{'proc'}->kill;          if ($fuse_self && $$fuse_self->umount) {
261                  return 1 if (! $self->{'proc'}->poll);                  print STDERR "umount called by SIG INT\n";
262          } else {          }
263                  return 1;  };
264    
265    $SIG{'QUIT'} = sub {
266            if ($fuse_self && $$fuse_self->umount) {
267                    print STDERR "umount called by SIG QUIT\n";
268            }
269    };
270    
271    sub DESTROY {
272            my $self = shift;
273            if ($self->umount) {
274                    print STDERR "umount called by DESTROY\n";
275          }          }
276  }  }
277    
278    =head2 fuse_module_loaded
279    
280    Checks if C<fuse> module is loaded in kernel.
281    
282      die "no fuse module loaded in kernel"
283            unless (Fuse::DBI::fuse_module_loaded);
284    
285    This function in called by C<mount>, but might be useful alone also.
286    
287    =cut
288    
289    sub fuse_module_loaded {
290            my $lsmod = `lsmod`;
291            die "can't start lsmod: $!" unless ($lsmod);
292            if ($lsmod =~ m/fuse/s) {
293                    return 1;
294            } else {
295                    return 0;
296            }
297    }
298    
299  my %files;  my %files;
 my %dirs;  
300    
301  sub read_filenames {  sub read_filenames {
302          my $self = shift;          my $self = shift;
303    
304            my $sth = $self->{'sth'} || die "no sth argument";
305    
306          # create empty filesystem          # create empty filesystem
307          (%files) = (          (%files) = (
308                  '.' => {                  '.' => {
309                          type => 0040,                          type => 0040,
310                          mode => 0755,                          mode => 0755,
311                  },                  },
312                    '..' => {
313                            type => 0040,
314                            mode => 0755,
315                    },
316          #       a => {          #       a => {
317          #               cont => "File 'a'.\n",          #               cont => "File 'a'.\n",
318          #               type => 0100,          #               type => 0100,
# Line 182  sub read_filenames { Line 336  sub read_filenames {
336                          # first, entry is assumed to be file                          # first, entry is assumed to be file
337                          if ($d) {                          if ($d) {
338                                  $files{$d} = {                                  $files{$d} = {
                                                 size => $dirs{$d}++,  
339                                                  mode => 0755,                                                  mode => 0755,
340                                                  type => 0040                                                  type => 0040
341                                  };                                  };
# Line 200  sub read_filenames { Line 353  sub read_filenames {
353                  }                  }
354          }          }
355    
356          print "found ",scalar(keys %files)-scalar(keys %dirs)," files, ",scalar(keys %dirs), " dirs\n";          print "found ",scalar(keys %files)," files\n";
357  }  }
358    
359    
# Line 216  sub e_getattr { Line 369  sub e_getattr {
369          $file =~ s,^/,,;          $file =~ s,^/,,;
370          $file = '.' unless length($file);          $file = '.' unless length($file);
371          return -ENOENT() unless exists($files{$file});          return -ENOENT() unless exists($files{$file});
372          my ($size) = $files{$file}{size} || 1;          my ($size) = $files{$file}{size} || 1024;
373          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+1023)/1024),0,0,1,1024);
374          my ($atime, $ctime, $mtime);          my ($atime, $ctime, $mtime);
375          $atime = $ctime = $mtime = $files{$file}{ctime} || $ctime_start;          $atime = $ctime = $mtime = $files{$file}{ctime} || $ctime_start;
376    
# Line 225  sub e_getattr { Line 378  sub e_getattr {
378    
379          # 2 possible types of return values:          # 2 possible types of return values:
380          #return -ENOENT(); # or any other error you care to          #return -ENOENT(); # or any other error you care to
381          #print(join(",",($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";
382          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);
383  }  }
384    
# Line 237  sub e_getdir { Line 390  sub e_getdir {
390          my %out;          my %out;
391          foreach my $f (sort keys %files) {          foreach my $f (sort keys %files) {
392                  if ($dirname) {                  if ($dirname) {
393                          if ($f =~ s/^\E$dirname\Q\///) {                          if ($f =~ s/^\Q$dirname\E\///) {
394                                  $out{$f}++ if ($f =~ /^[^\/]+$/);                                  $out{$f}++ if ($f =~ /^[^\/]+$/);
395                          }                          }
396                  } else {                  } else {
# Line 252  sub e_getdir { Line 405  sub e_getdir {
405          return (keys %out),0;          return (keys %out),0;
406  }  }
407    
408    sub read_content {
409            my ($file,$id) = @_;
410    
411            die "read_content needs file and id" unless ($file && $id);
412    
413            $sth->{'read'}->execute($id) || die $sth->{'read'}->errstr;
414            $files{$file}{cont} = $sth->{'read'}->fetchrow_array;
415            # I should modify ctime only if content in database changed
416            #$files{$file}{ctime} = time() unless ($files{$file}{ctime});
417            print "file '$file' content [",length($files{$file}{cont})," bytes] read in cache\n";
418    }
419    
420    
421  sub e_open {  sub e_open {
422          # VFS sanity check; it keeps all the necessary state, not much to do here.          # VFS sanity check; it keeps all the necessary state, not much to do here.
423          my $file = filename_fixup(shift);          my $file = filename_fixup(shift);
# Line 260  sub e_open { Line 426  sub e_open {
426          return -ENOENT() unless exists($files{$file});          return -ENOENT() unless exists($files{$file});
427          return -EISDIR() unless exists($files{$file}{id});          return -EISDIR() unless exists($files{$file}{id});
428    
429          if (!exists($files{$file}{cont})) {          read_content($file,$files{$file}{id}) unless exists($files{$file}{cont});
430                  $sth->{'read'}->execute($files{$file}{id}) || die $sth->{'read'}->errstr;  
                 $files{$file}{cont} = $sth->{'read'}->fetchrow_array;  
                 print "file '$file' content read in cache\n";  
         }  
431          print "open '$file' ",length($files{$file}{cont})," bytes\n";          print "open '$file' ",length($files{$file}{cont})," bytes\n";
432          return 0;          return 0;
433  }  }
# Line 285  sub e_read { Line 448  sub e_read {
448          return -EINVAL() if ($off > $len);          return -EINVAL() if ($off > $len);
449          return 0 if ($off == $len);          return 0 if ($off == $len);
450    
451          $buf_len = $buf_len-$off if ($off+$buf_len > $len);          $buf_len = $len-$off if ($len - $off < $buf_len);
452    
453          return substr($files{$file}{cont},$off,$buf_len);          return substr($files{$file}{cont},$off,$buf_len);
454  }  }
# Line 296  sub clear_cont { Line 459  sub clear_cont {
459          print "invalidate all cached content\n";          print "invalidate all cached content\n";
460          foreach my $f (keys %files) {          foreach my $f (keys %files) {
461                  delete $files{$f}{cont};                  delete $files{$f}{cont};
462                    delete $files{$f}{ctime};
463          }          }
464          print "begin new transaction\n";          print "begin new transaction\n";
465          $dbh->begin_work || die $dbh->errstr;          #$dbh->begin_work || die $dbh->errstr;
466  }  }
467    
468    
# Line 307  sub update_db { Line 471  sub update_db {
471    
472          $files{$file}{ctime} = time();          $files{$file}{ctime} = time();
473    
474          if (!$sth->{'update'}->execute($files{$file}{cont},$files{$file}{id})) {          my ($cont,$id) = (
475                    $files{$file}{cont},
476                    $files{$file}{id}
477            );
478    
479            if (!$sth->{'update'}->execute($cont,$id)) {
480                  print "update problem: ",$sth->{'update'}->errstr;                  print "update problem: ",$sth->{'update'}->errstr;
481                  clear_cont;                  clear_cont;
482                  return 0;                  return 0;
# Line 318  sub update_db { Line 487  sub update_db {
487                          return 0;                          return 0;
488                  }                  }
489                  print "updated '$file' [",$files{$file}{id},"]\n";                  print "updated '$file' [",$files{$file}{id},"]\n";
490    
491                    $$fuse_self->{'invalidate'}->() if (ref $$fuse_self->{'invalidate'});
492          }          }
493          return 1;          return 1;
494  }  }
495    
496  sub e_write {  sub e_write {
497          my $file = filename_fixup(shift);          my $file = filename_fixup(shift);
498          my ($buf_len,$off) = @_;          my ($buffer,$off) = @_;
499    
500          return -ENOENT() unless exists($files{$file});          return -ENOENT() unless exists($files{$file});
501    
502          my $len = length($files{$file}{cont});          my $cont = $files{$file}{cont};
503            my $len = length($cont);
504    
505            print "write '$file' [$len bytes] offset $off length ",length($buffer),"\n";
506    
507          print "write '$file' [$len bytes] offset $off length\n";          $files{$file}{cont} = "";
508    
509          $files{$file}{cont} =          $files{$file}{cont} .= substr($cont,0,$off) if ($off > 0);
510                  substr($files{$file}{cont},0,$off) .          $files{$file}{cont} .= $buffer;
511                  $buf_len .          $files{$file}{cont} .= substr($cont,$off+length($buffer),$len-$off-length($buffer)) if ($off+length($buffer) < $len);
512                  substr($files{$file}{cont},$off+length($buf_len));  
513            $files{$file}{size} = length($files{$file}{cont});
514    
515          if (! update_db($file)) {          if (! update_db($file)) {
516                  return -ENOSYS();                  return -ENOSYS();
517          } else {          } else {
518                  return length($buf_len);                  return length($buffer);
519          }          }
520  }  }
521    
# Line 348  sub e_truncate { Line 523  sub e_truncate {
523          my $file = filename_fixup(shift);          my $file = filename_fixup(shift);
524          my $size = shift;          my $size = shift;
525    
526            print "truncate to $size\n";
527    
528          $files{$file}{cont} = substr($files{$file}{cont},0,$size);          $files{$file}{cont} = substr($files{$file}{cont},0,$size);
529            $files{$file}{size} = $size;
530          return 0          return 0
531  };  };
532    
# Line 365  sub e_utime { Line 543  sub e_utime {
543          return 0;          return 0;
544  }  }
545    
546  sub e_statfs { return 255, 1, 1, 1, 1, 2 }  sub e_statfs {
547    
548            my $size = 0;
549            my $inodes = 0;
550    
551            foreach my $f (keys %files) {
552                    if ($f !~ /(^|\/)\.\.?$/) {
553                            $size += $files{$f}{size} || 0;
554                            $inodes++;
555                    }
556                    print "$inodes: $f [$size]\n";
557            }
558    
559            $size = int(($size+1023)/1024);
560    
561            my @ret = (255, $inodes+1000, $inodes, $size, $size-10, 1024);
562    
563            print "statfs: ",join(",",@ret),"\n";
564    
565            return @ret;
566    }
567    
568    sub e_unlink {
569            my $file = filename_fixup(shift);
570    
571    #       if (exists( $dirs{$file} )) {
572    #               print "unlink '$file' will re-read template names\n";
573    #               print Dumper($fuse_self);
574    #               $$fuse_self->{'read_filenames'}->();
575    #               return 0;
576            if (exists( $files{$file} )) {
577                    print "unlink '$file' will invalidate cache\n";
578                    read_content($file,$files{$file}{id});
579                    return 0;
580            }
581    
582            return -ENOENT();
583    }
584  1;  1;
585  __END__  __END__
586    
# Line 374  __END__ Line 588  __END__
588    
589  Nothing.  Nothing.
590    
591    =head1 BUGS
592    
593    Size information (C<ls -s>) is wrong. It's a problem in upstream Fuse module
594    (for which I'm to blame lately), so when it gets fixes, C<Fuse::DBI> will
595    automagically pick it up.
596    
597  =head1 SEE ALSO  =head1 SEE ALSO
598    
599  C<FUSE (Filesystem in USErspace)> website  C<FUSE (Filesystem in USErspace)> website
600  L<http://sourceforge.net/projects/avf>  L<http://fuse.sourceforge.net/>
601    
602    Example for WebGUI which comes with this distribution in
603    directory C<examples/webgui.pl>. It also contains a lot of documentation
604    about design of this module, usage and limitations.
605    
606  =head1 AUTHOR  =head1 AUTHOR
607    
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