/[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 54 by dpavlin, Tue Apr 26 19:57:51 2005 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          print "start transaction\n";          my $pid;
157          $dbh->begin_work || die $dbh->errstr;          if ($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            $dbh = DBI->connect($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    
         $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                    if ($self->is_mounted) {
254                            system "sudo umount ".$self->{'mount'} ||
255                            return 0;
256                    }
257                    return 1;
258            }
259    
260          system "fusermount -u ".$self->{'mount'} || croak "umount error: $!";          return 0;
261    }
262    
263          if ($self->{'proc'}->poll) {  $SIG{'INT'} = sub {
264                  $self->{'proc'}->kill;          if ($fuse_self && $$fuse_self->umount) {
265                  return 1 if (! $self->{'proc'}->poll);                  print STDERR "umount called by SIG INT\n";
266          } else {          }
267                  return 1;  };
268    
269    $SIG{'QUIT'} = sub {
270            if ($fuse_self && $$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
283    
284    Checks if C<fuse> module is loaded in kernel.
285    
286      die "no fuse module loaded in kernel"
287            unless (Fuse::DBI::fuse_module_loaded);
288    
289    This function in called by C<mount>, but might be useful alone also.
290    
291    =cut
292    
293    sub fuse_module_loaded {
294            my $lsmod = `lsmod`;
295            die "can't start lsmod: $!" unless ($lsmod);
296            if ($lsmod =~ m/fuse/s) {
297                    return 1;
298            } else {
299                    return 0;
300            }
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 = $self->{'sth'} || die "no sth argument";
309    
310          # create empty filesystem          # create empty filesystem
311          (%files) = (          (%files) = (
312                  '.' => {                  '.' => {
313                          type => 0040,                          type => 0040,
314                          mode => 0755,                          mode => 0755,
315                  },                  },
316                    '..' => {
317                            type => 0040,
318                            mode => 0755,
319                    },
320          #       a => {          #       a => {
321          #               cont => "File 'a'.\n",          #               cont => "File 'a'.\n",
322          #               type => 0100,          #               type => 0100,
# Line 182  sub read_filenames { Line 340  sub read_filenames {
340                          # first, entry is assumed to be file                          # first, entry is assumed to be file
341                          if ($d) {                          if ($d) {
342                                  $files{$d} = {                                  $files{$d} = {
                                                 size => $dirs{$d}++,  
343                                                  mode => 0755,                                                  mode => 0755,
344                                                  type => 0040                                                  type => 0040
345                                  };                                  };
# Line 200  sub read_filenames { Line 357  sub read_filenames {
357                  }                  }
358          }          }
359    
360          print "found ",scalar(keys %files)-scalar(keys %dirs)," files, ",scalar(keys %dirs), " dirs\n";          print "found ",scalar(keys %files)," files\n";
361  }  }
362    
363    
# Line 216  sub e_getattr { Line 373  sub e_getattr {
373          $file =~ s,^/,,;          $file =~ s,^/,,;
374          $file = '.' unless length($file);          $file = '.' unless length($file);
375          return -ENOENT() unless exists($files{$file});          return -ENOENT() unless exists($files{$file});
376          my ($size) = $files{$file}{size} || 1;          my ($size) = $files{$file}{size} || 0;
377          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);
378          my ($atime, $ctime, $mtime);          my ($atime, $ctime, $mtime);
379          $atime = $ctime = $mtime = $files{$file}{ctime} || $ctime_start;          $atime = $ctime = $mtime = $files{$file}{ctime} || $ctime_start;
380    
# Line 225  sub e_getattr { Line 382  sub e_getattr {
382    
383          # 2 possible types of return values:          # 2 possible types of return values:
384          #return -ENOENT(); # or any other error you care to          #return -ENOENT(); # or any other error you care to
385          #print(join(",",($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";
386          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);
387  }  }
388    
# Line 237  sub e_getdir { Line 394  sub e_getdir {
394          my %out;          my %out;
395          foreach my $f (sort keys %files) {          foreach my $f (sort keys %files) {
396                  if ($dirname) {                  if ($dirname) {
397                          if ($f =~ s/^\E$dirname\Q\///) {                          if ($f =~ s/^\Q$dirname\E\///) {
398                                  $out{$f}++ if ($f =~ /^[^\/]+$/);                                  $out{$f}++ if ($f =~ /^[^\/]+$/);
399                          }                          }
400                  } else {                  } else {
# Line 252  sub e_getdir { Line 409  sub e_getdir {
409          return (keys %out),0;          return (keys %out),0;
410  }  }
411    
412    sub read_content {
413            my ($file,$id) = @_;
414    
415            die "read_content needs file and id" unless ($file && $id);
416    
417            $sth->{'read'}->execute($id) || die $sth->{'read'}->errstr;
418            $files{$file}{cont} = $sth->{'read'}->fetchrow_array;
419            # I should modify ctime only if content in database changed
420            #$files{$file}{ctime} = time() unless ($files{$file}{ctime});
421            print "file '$file' content [",length($files{$file}{cont})," bytes] read in cache\n";
422    }
423    
424    
425  sub e_open {  sub e_open {
426          # 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.
427          my $file = filename_fixup(shift);          my $file = filename_fixup(shift);
# Line 260  sub e_open { Line 430  sub e_open {
430          return -ENOENT() unless exists($files{$file});          return -ENOENT() unless exists($files{$file});
431          return -EISDIR() unless exists($files{$file}{id});          return -EISDIR() unless exists($files{$file}{id});
432    
433          if (!exists($files{$file}{cont})) {          read_content($file,$files{$file}{id}) unless exists($files{$file}{cont});
434                  $sth->{'read'}->execute($files{$file}{id}) || die $sth->{'read'}->errstr;  
435                  $files{$file}{cont} = $sth->{'read'}->fetchrow_array;          $files{$file}{cont} ||= '';
                 print "file '$file' content read in cache\n";  
         }  
436          print "open '$file' ",length($files{$file}{cont})," bytes\n";          print "open '$file' ",length($files{$file}{cont})," bytes\n";
437          return 0;          return 0;
438  }  }
# Line 285  sub e_read { Line 453  sub e_read {
453          return -EINVAL() if ($off > $len);          return -EINVAL() if ($off > $len);
454          return 0 if ($off == $len);          return 0 if ($off == $len);
455    
456          $buf_len = $buf_len-$off if ($off+$buf_len > $len);          $buf_len = $len-$off if ($len - $off < $buf_len);
457    
458          return substr($files{$file}{cont},$off,$buf_len);          return substr($files{$file}{cont},$off,$buf_len);
459  }  }
# Line 296  sub clear_cont { Line 464  sub clear_cont {
464          print "invalidate all cached content\n";          print "invalidate all cached content\n";
465          foreach my $f (keys %files) {          foreach my $f (keys %files) {
466                  delete $files{$f}{cont};                  delete $files{$f}{cont};
467                    delete $files{$f}{ctime};
468          }          }
469          print "begin new transaction\n";          print "begin new transaction\n";
470          $dbh->begin_work || die $dbh->errstr;          #$dbh->begin_work || die $dbh->errstr;
471  }  }
472    
473    
# Line 307  sub update_db { Line 476  sub update_db {
476    
477          $files{$file}{ctime} = time();          $files{$file}{ctime} = time();
478    
479          if (!$sth->{'update'}->execute($files{$file}{cont},$files{$file}{id})) {          my ($cont,$id) = (
480                    $files{$file}{cont},
481                    $files{$file}{id}
482            );
483    
484            if (!$sth->{'update'}->execute($cont,$id)) {
485                  print "update problem: ",$sth->{'update'}->errstr;                  print "update problem: ",$sth->{'update'}->errstr;
486                  clear_cont;                  clear_cont;
487                  return 0;                  return 0;
# Line 318  sub update_db { Line 492  sub update_db {
492                          return 0;                          return 0;
493                  }                  }
494                  print "updated '$file' [",$files{$file}{id},"]\n";                  print "updated '$file' [",$files{$file}{id},"]\n";
495    
496                    $$fuse_self->{'invalidate'}->() if (ref $$fuse_self->{'invalidate'});
497          }          }
498          return 1;          return 1;
499  }  }
# Line 337  sub e_write { Line 513  sub e_write {
513    
514          $files{$file}{cont} .= substr($cont,0,$off) if ($off > 0);          $files{$file}{cont} .= substr($cont,0,$off) if ($off > 0);
515          $files{$file}{cont} .= $buffer;          $files{$file}{cont} .= $buffer;
516          $files{$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);
517    
518          $files{$file}{size} = length($files{$file}{cont});          $files{$file}{size} = length($files{$file}{cont});
519    
# Line 372  sub e_utime { Line 548  sub e_utime {
548          return 0;          return 0;
549  }  }
550    
551  sub e_statfs { return 255, 1, 1, 1, 1, 2 }  sub e_statfs {
552    
553            my $size = 0;
554            my $inodes = 0;
555    
556            foreach my $f (keys %files) {
557                    if ($f !~ /(^|\/)\.\.?$/) {
558                            $size += $files{$f}{size} || 0;
559                            $inodes++;
560                    }
561                    print "$inodes: $f [$size]\n";
562            }
563    
564            $size = int(($size+BLOCK-1)/BLOCK);
565    
566            my @ret = (255, $inodes, 1, $size, $size-1, BLOCK);
567    
568            #print "statfs: ",join(",",@ret),"\n";
569    
570            return @ret;
571    }
572    
573    sub e_unlink {
574            my $file = filename_fixup(shift);
575    
576    #       if (exists( $dirs{$file} )) {
577    #               print "unlink '$file' will re-read template names\n";
578    #               print Dumper($fuse_self);
579    #               $$fuse_self->{'read_filenames'}->();
580    #               return 0;
581            if (exists( $files{$file} )) {
582                    print "unlink '$file' will invalidate cache\n";
583                    read_content($file,$files{$file}{id});
584                    return 0;
585            }
586    
587            return -ENOENT();
588    }
589  1;  1;
590  __END__  __END__
591    
# Line 381  __END__ Line 593  __END__
593    
594  Nothing.  Nothing.
595    
596    =head1 BUGS
597    
598    Size information (C<ls -s>) is wrong. It's a problem in upstream Fuse module
599    (for which I'm to blame lately), so when it gets fixes, C<Fuse::DBI> will
600    automagically pick it up.
601    
602  =head1 SEE ALSO  =head1 SEE ALSO
603    
604  C<FUSE (Filesystem in USErspace)> website  C<FUSE (Filesystem in USErspace)> website
605  L<http://sourceforge.net/projects/avf>  L<http://fuse.sourceforge.net/>
606    
607    Example for WebGUI which comes with this distribution in
608    directory C<examples/webgui.pl>. It also contains a lot of documentation
609    about design of this module, usage and limitations.
610    
611  =head1 AUTHOR  =head1 AUTHOR
612    
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