/[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 18 by dpavlin, Sun Sep 5 16:59:41 2004 UTC revision 52 by dpavlin, Sat Nov 27 15:08:10 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    our $VERSION = '0.07';
16    
17  our $VERSION = '0.02';  # block size for this filesystem
18    use constant BLOCK => 1024;
19    
20  =head1 NAME  =head1 NAME
21    
# Line 25  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 47  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 filenamefilenames,          '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 63  my $sth; Line 118  my $sth;
118  my $ctime_start;  my $ctime_start;
119    
120  sub read_filenames;  sub read_filenames;
121    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 $class = shift;
# Line 73  sub mount { Line 134  sub mount {
134    
135          print Dumper($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 ($arg->{$_});
152          }          }
153    
154          $dbh = DBI->connect($arg->{'dsn'},$arg->{'user'},$arg->{'password'}, { AutoCommit => 0 }) || die $DBI::errstr;          $ctime_start = time();
155    
156            my $pid;
157            if ($arg->{'fork'}) {
158                    $pid = fork();
159                    die "fork() failed: $!" unless defined $pid;
160                    # child will return to caller
161                    if ($pid) {
162                            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          print "start transaction\n";          $dbh = DBI->connect($arg->{'dsn'},$arg->{'user'},$arg->{'password'}, {AutoCommit => 0, RaiseError => 1}) || die $DBI::errstr;
         $dbh->begin_work || die $dbh->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    
         $ctime_start = time();  
182    
183          read_filenames;          $self->{'sth'} = $sth;
184    
185            $self->{'read_filenames'} = sub { $self->read_filenames };
186            $self->read_filenames;
187    
188          $self->{'proc'} = Proc::Simple->new();          $fuse_self = \$self;
         $self->{'proc'}->kill_on_destroy(1);  
189    
190          $self->{'proc'}->start( sub {          Fuse::main(
191                  Fuse::main(                  mountpoint=>$arg->{'mount'},
192                          mountpoint=>$arg->{'mount'},                  getattr=>\&e_getattr,
193                          getattr=>\&e_getattr,                  getdir=>\&e_getdir,
194                          getdir=>\&e_getdir,                  open=>\&e_open,
195                          open=>\&e_open,                  statfs=>\&e_statfs,
196                          statfs=>\&e_statfs,                  read=>\&e_read,
197                          read=>\&e_read,                  write=>\&e_write,
198                          write=>\&e_write,                  utime=>\&e_utime,
199                          utime=>\&e_utime,                  truncate=>\&e_truncate,
200                          truncate=>\&e_truncate,                  unlink=>\&e_unlink,
201                          debug=>0,                  rmdir=>\&e_unlink,
202                  );                  debug=>0,
203          } );          );
204            
205            exit(0) if ($arg->{'fork'});
206    
207          confess "Fuse::main failed" if (! $self->{'proc'}->poll);          return 1;
208    
         $self ? return $self : return undef;  
209  };  };
210    
211    =head2 is_mounted
212    
213    Check if fuse filesystem is mounted
214    
215      if ($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 134  database to filesystem. Line 248  database to filesystem.
248  sub umount {  sub umount {
249          my $self = shift;          my $self = shift;
250    
251          confess "no process running?" unless ($self->{'proc'});          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 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
281    
282          system "fusermount -u ".$self->{'mount'} || croak "umount error: $!";  Checks if C<fuse> module is loaded in kernel.
283    
284          if ($self->{'proc'}->poll) {    die "no fuse module loaded in kernel"
285                  $self->{'proc'}->kill;          unless (Fuse::DBI::fuse_module_loaded);
286                  return 1 if (! $self->{'proc'}->poll);  
287          } else {  This function in called by C<mount>, but might be useful alone also.
288    
289    =cut
290    
291    sub fuse_module_loaded {
292            my $lsmod = `lsmod`;
293            die "can't start lsmod: $!" unless ($lsmod);
294            if ($lsmod =~ m/fuse/s) {
295                  return 1;                  return 1;
296            } else {
297                    return 0;
298          }          }
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 = $self->{'sth'} || die "no sth argument";
307    
308          # create empty filesystem          # create empty filesystem
309          (%files) = (          (%files) = (
310                  '.' => {                  '.' => {
311                          type => 0040,                          type => 0040,
312                          mode => 0755,                          mode => 0755,
313                  },                  },
314                    '..' => {
315                            type => 0040,
316                            mode => 0755,
317                    },
318          #       a => {          #       a => {
319          #               cont => "File 'a'.\n",          #               cont => "File 'a'.\n",
320          #               type => 0100,          #               type => 0100,
# Line 182  sub read_filenames { Line 338  sub read_filenames {
338                          # first, entry is assumed to be file                          # first, entry is assumed to be file
339                          if ($d) {                          if ($d) {
340                                  $files{$d} = {                                  $files{$d} = {
                                                 size => $dirs{$d}++,  
341                                                  mode => 0755,                                                  mode => 0755,
342                                                  type => 0040                                                  type => 0040
343                                  };                                  };
# Line 200  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 216  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} || $ctime_start;
378    
# Line 225  sub e_getattr { Line 380  sub e_getattr {
380    
381          # 2 possible types of return values:          # 2 possible types of return values:
382          #return -ENOENT(); # or any other error you care to          #return -ENOENT(); # or any other error you care to
383          #print(join(",",($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 237  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 252  sub e_getdir { Line 407  sub e_getdir {
407          return (keys %out),0;          return (keys %out),0;
408  }  }
409    
410    sub read_content {
411            my ($file,$id) = @_;
412    
413            die "read_content needs file and id" unless ($file && $id);
414    
415            $sth->{'read'}->execute($id) || die $sth->{'read'}->errstr;
416            $files{$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";
420    }
421    
422    
423  sub e_open {  sub e_open {
424          # 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.
425          my $file = filename_fixup(shift);          my $file = filename_fixup(shift);
# Line 260  sub e_open { Line 428  sub e_open {
428          return -ENOENT() unless exists($files{$file});          return -ENOENT() unless exists($files{$file});
429          return -EISDIR() unless exists($files{$file}{id});          return -EISDIR() unless exists($files{$file}{id});
430    
431          if (!exists($files{$file}{cont})) {          read_content($file,$files{$file}{id}) unless exists($files{$file}{cont});
432                  $sth->{'read'}->execute($files{$file}{id}) || die $sth->{'read'}->errstr;  
                 $files{$file}{cont} = $sth->{'read'}->fetchrow_array;  
                 print "file '$file' content read in cache\n";  
         }  
433          print "open '$file' ",length($files{$file}{cont})," bytes\n";          print "open '$file' ",length($files{$file}{cont})," bytes\n";
434          return 0;          return 0;
435  }  }
# Line 285  sub e_read { Line 450  sub e_read {
450          return -EINVAL() if ($off > $len);          return -EINVAL() if ($off > $len);
451          return 0 if ($off == $len);          return 0 if ($off == $len);
452    
453          $buf_len = $buf_len-$off if ($off+$buf_len > $len);          $buf_len = $len-$off if ($len - $off < $buf_len);
454    
455          return substr($files{$file}{cont},$off,$buf_len);          return substr($files{$file}{cont},$off,$buf_len);
456  }  }
# Line 296  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;
468  }  }
469    
470    
# Line 307  sub update_db { Line 473  sub update_db {
473    
474          $files{$file}{ctime} = time();          $files{$file}{ctime} = time();
475    
476          if (!$sth->{'update'}->execute($files{$file}{cont},$files{$file}{id})) {          my ($cont,$id) = (
477                    $files{$file}{cont},
478                    $files{$file}{id}
479            );
480    
481            if (!$sth->{'update'}->execute($cont,$id)) {
482                  print "update problem: ",$sth->{'update'}->errstr;                  print "update problem: ",$sth->{'update'}->errstr;
483                  clear_cont;                  clear_cont;
484                  return 0;                  return 0;
# Line 318  sub update_db { Line 489  sub update_db {
489                          return 0;                          return 0;
490                  }                  }
491                  print "updated '$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 337  sub e_write { Line 510  sub e_write {
510    
511          $files{$file}{cont} .= substr($cont,0,$off) if ($off > 0);          $files{$file}{cont} .= substr($cont,0,$off) if ($off > 0);
512          $files{$file}{cont} .= $buffer;          $files{$file}{cont} .= $buffer;
513          $files{$file}{cont} .= substr($cont,-($off+length($buffer))) if ($off+length($buffer) > $len);          $files{$file}{cont} .= substr($cont,$off+length($buffer),$len-$off-length($buffer)) if ($off+length($buffer) < $len);
514    
515          $files{$file}{size} = length($files{$file}{cont});          $files{$file}{size} = length($files{$file}{cont});
516    
# Line 372  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            my $size = 0;
551            my $inodes = 0;
552    
553            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            $size = int(($size+BLOCK-1)/BLOCK);
562    
563            my @ret = (255, $inodes, 1, $size, $size-1, BLOCK);
564    
565            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__
588    
# Line 381  __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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