/[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 9 by dpavlin, Sat Aug 7 19:06:03 2004 UTC revision 32 by dpavlin, Mon Nov 15 20:45:03 2004 UTC
# Line 9  use warnings; Line 9  use warnings;
9  use POSIX qw(ENOENT EISDIR EINVAL ENOSYS O_RDWR);  use POSIX qw(ENOENT EISDIR EINVAL ENOSYS O_RDWR);
10  use Fuse;  use Fuse;
11  use DBI;  use DBI;
12    use Carp;
13    use Data::Dumper;
14    
15  our $VERSION = '0.01';  
16    our $VERSION = '0.04';
17    
18  =head1 NAME  =head1 NAME
19    
# Line 19  Fuse::DBI - mount your database as files Line 22  Fuse::DBI - mount your database as files
22  =head1 SYNOPSIS  =head1 SYNOPSIS
23    
24    use Fuse::DBI;    use Fuse::DBI;
25    Fuse::DBI->run( ... );    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://sourceforge.net/projects/avf> 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 39  It's actually opposite of Oracle's inten Line 42  It's actually opposite of Oracle's inten
42    
43  =cut  =cut
44    
45  =head2 run  =head2 mount
46    
47  Mount your database as filesystem.  Mount your database as filesystem.
48    
49    Fuse::DBI->run({  Let's suppose that your database have table C<files> with following structure:
50          filenames => 'select name from filenamefilenames,  
51          read => 'sql read',   id:            int
52          update => 'sql update',   filename:      text
53          dsn => 'DBI:Pg:dbname=webgui',   size:          int
54          user => 'database_user',   content:       text
55          password => 'database_password'   writable:      boolean
56    
57    Following is example how to mount table like that to C</mnt>:
58    
59      my $mnt = Fuse::DBI->mount({
60            'filenames' => 'select id,filename,size,writable from files',
61            'read' => 'select content from files where id = ?',
62            'update' => 'update files set content = ? where id = ?',
63            'dsn' => 'DBI:Pg:dbname=test_db',
64            'user' => 'database_user',
65            '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;
115  my $sth;  my $sth;
116  my $ctime_start;  my $ctime_start;
117    
118  sub run {  sub read_filenames;
119          my $self = shift  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 {
127            my $class = shift;
128            my $self = {};
129            bless($self, $class);
130    
131            my $arg = shift;
132    
133          my $arg = {@_};          print Dumper($arg);
134    
135          carp "run 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'});
136          carp "run needs 'mount' as mountpoint" unless ($arg->{'mount'});          carp "mount needs 'mount' as mountpoint" unless ($arg->{'mount'});
137    
138            # save (some) arguments in self
139            foreach (qw(mount invalidate)) {
140                    $self->{$_} = $arg->{$_};
141            }
142    
143          foreach (qw(filenames read update)) {          foreach (qw(filenames read update)) {
144                  carp "run needs '$_' SQL" unless ($arg->{$_});                  carp "mount needs '$_' SQL" unless ($arg->{$_});
145          }          }
146    
147          $dbh = DBI->connect($arg->{'dsn'},$arg->{'user'},$arg->{'password'}, { AutoCommit => 0 }) || die $DBI::errstr;          $ctime_start = time();
148    
149          print "start transaction\n";          my $pid;
150          #$dbh->begin_work || die $dbh->errstr;          if ($arg->{'fork'}) {
151                    $pid = fork();
152                    die "fork() failed: $!" unless defined $pid;
153                    # child will return to caller
154                    if ($pid) {
155                            return $self;
156                    }
157            }
158    
159          $sth->{filenames} = $dbh->prepare($arg->{'filenames'}) || die $dbh->errstr();          $dbh = DBI->connect($arg->{'dsn'},$arg->{'user'},$arg->{'password'}, {AutoCommit => 0, RaiseError => 1}) || die $DBI::errstr;
160    
161            $sth->{'filenames'} = $dbh->prepare($arg->{'filenames'}) || die $dbh->errstr();
162    
163          $sth->{'read'} = $dbh->prepare($arg->{'read'}) || die $dbh->errstr();          $sth->{'read'} = $dbh->prepare($arg->{'read'}) || die $dbh->errstr();
164          $sth->{'update'} = $dbh->prepare($arg->{'update'}) || die $dbh->errstr();          $sth->{'update'} = $dbh->prepare($arg->{'update'}) || die $dbh->errstr();
165    
         $ctime_start = time();  
166    
167          read_filenames;          $self->{'sth'} = $sth;
168    
169            $self->{'read_filenames'} = sub { $self->read_filenames };
170            $self->read_filenames;
171    
172            $self->{'mounted'} = 1;
173    
174            $fuse_self = \$self;
175    
176          Fuse::main(          Fuse::main(
177                  mountpoint=>$arg->{'mount'},                  mountpoint=>$arg->{'mount'},
# Line 94  sub run { Line 183  sub run {
183                  write=>\&e_write,                  write=>\&e_write,
184                  utime=>\&e_utime,                  utime=>\&e_utime,
185                  truncate=>\&e_truncate,                  truncate=>\&e_truncate,
186                    unlink=>\&e_unlink,
187                    rmdir=>\&e_unlink,
188                  debug=>0,                  debug=>0,
189          );          );
190            
191            $self->{'mounted'} = 0;
192    
193            exit(0) if ($arg->{'fork'});
194    
195            return 1;
196    
197  };  };
198    
199    =head2 umount
200    
201    Unmount your database as filesystem.
202    
203      $mnt->umount;
204    
205    This will also kill background process which is translating
206    database to filesystem.
207    
208    =cut
209    
210    sub umount {
211            my $self = shift;
212    
213            if ($self->{'mounted'}) {
214                    system "fusermount -u ".$self->{'mount'} || croak "umount error: $!";
215            }
216    
217            return 1;
218    }
219    
220    $SIG{'INT'} = sub {
221            print STDERR "umount called by SIG INT\n";
222            umount;
223    };
224    
225    sub DESTROY {
226            my $self = shift;
227            return if (! $self->{'mounted'});
228            print STDERR "umount called by DESTROY\n";
229            $self->umount;
230    }
231    
232    =head2 fuse_module_loaded
233    
234    Checks if C<fuse> module is loaded in kernel.
235    
236      die "no fuse module loaded in kernel"
237            unless (Fuse::DBI::fuse_module_loaded);
238    
239    This function in called by C<mount>, but might be useful alone also.
240    
241    =cut
242    
243    sub fuse_module_loaded {
244            my $lsmod = `lsmod`;
245            die "can't start lsmod: $!" unless ($lsmod);
246            if ($lsmod =~ m/fuse/s) {
247                    return 1;
248            } else {
249                    return 0;
250            }
251    }
252    
253  my %files;  my %files;
254  my %dirs;  my %dirs;
255    
256  sub read_filenames {  sub read_filenames {
257            my $self = shift;
258    
259            my $sth = $self->{'sth'} || die "no sth argument";
260    
261          # create empty filesystem          # create empty filesystem
262          (%files) = (          (%files) = (
263                  '.' => {                  '.' => {
# Line 184  sub e_getdir { Line 340  sub e_getdir {
340          # return as many text filenames as you like, followed by the retval.          # return as many text filenames as you like, followed by the retval.
341          print((scalar keys %files)." files total\n");          print((scalar keys %files)." files total\n");
342          my %out;          my %out;
343          foreach (keys %files) {          foreach my $f (sort keys %files) {
                 my $f = $_;  
                 $f =~ s/^\E$dirname\Q//;  
                 $f =~ s/^\///;  
344                  if ($dirname) {                  if ($dirname) {
345                          $out{$f}++ if (/^\E$dirname\Q/ && $f =~ /^[^\/]+$/);                          if ($f =~ s/^\Q$dirname\E\///) {
346                                    $out{$f}++ if ($f =~ /^[^\/]+$/);
347                            }
348                  } else {                  } else {
349                          $out{$f}++ if ($f =~ /^[^\/]+$/);                          $out{$f}++ if ($f =~ /^[^\/]+$/);
350                  }                  }
# Line 198  sub e_getdir { Line 353  sub e_getdir {
353                  $out{'no files? bug?'}++;                  $out{'no files? bug?'}++;
354          }          }
355          print scalar keys %out," files in dir '$dirname'\n";          print scalar keys %out," files in dir '$dirname'\n";
356            print "## ",join(" ",keys %out),"\n";
357          return (keys %out),0;          return (keys %out),0;
358  }  }
359    
360    sub read_content {
361            my ($file,$id) = @_;
362    
363            die "read_content needs file and id" unless ($file && $id);
364    
365            $sth->{'read'}->execute($id) || die $sth->{'read'}->errstr;
366            $files{$file}{cont} = $sth->{'read'}->fetchrow_array;
367            # I should modify ctime only if content in database changed
368            #$files{$file}{ctime} = time() unless ($files{$file}{ctime});
369            print "file '$file' content [",length($files{$file}{cont})," bytes] read in cache\n";
370    }
371    
372    
373  sub e_open {  sub e_open {
374          # 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.
375          my $file = filename_fixup(shift);          my $file = filename_fixup(shift);
# Line 209  sub e_open { Line 378  sub e_open {
378          return -ENOENT() unless exists($files{$file});          return -ENOENT() unless exists($files{$file});
379          return -EISDIR() unless exists($files{$file}{id});          return -EISDIR() unless exists($files{$file}{id});
380    
381          if (!exists($files{$file}{cont})) {          read_content($file,$files{$file}{id}) unless exists($files{$file}{cont});
382                  $sth->{'read'}->execute($files{$file}{id}) || die $sth->{'read'}->errstr;  
                 $files{$file}{cont} = $sth->{'read'}->fetchrow_array;  
                 print "file '$file' content read in cache\n";  
         }  
383          print "open '$file' ",length($files{$file}{cont})," bytes\n";          print "open '$file' ",length($files{$file}{cont})," bytes\n";
384          return 0;          return 0;
385  }  }
# Line 234  sub e_read { Line 400  sub e_read {
400          return -EINVAL() if ($off > $len);          return -EINVAL() if ($off > $len);
401          return 0 if ($off == $len);          return 0 if ($off == $len);
402    
403          $buf_len = $buf_len-$off if ($off+$buf_len > $len);          $buf_len = $len-$off if ($len - $off < $buf_len);
404    
405          return substr($files{$file}{cont},$off,$buf_len);          return substr($files{$file}{cont},$off,$buf_len);
406  }  }
# Line 245  sub clear_cont { Line 411  sub clear_cont {
411          print "invalidate all cached content\n";          print "invalidate all cached content\n";
412          foreach my $f (keys %files) {          foreach my $f (keys %files) {
413                  delete $files{$f}{cont};                  delete $files{$f}{cont};
414                    delete $files{$f}{ctime};
415          }          }
416          print "begin new transaction\n";          print "begin new transaction\n";
417          $dbh->begin_work || die $dbh->errstr;          #$dbh->begin_work || die $dbh->errstr;
418  }  }
419    
420    
# Line 256  sub update_db { Line 423  sub update_db {
423    
424          $files{$file}{ctime} = time();          $files{$file}{ctime} = time();
425    
426          if (!$sth->{'update'}->execute($files{$file}{cont},$files{$file}{id})) {          my ($cont,$id) = (
427                    $files{$file}{cont},
428                    $files{$file}{id}
429            );
430    
431            if (!$sth->{'update'}->execute($cont,$id)) {
432                  print "update problem: ",$sth->{'update'}->errstr;                  print "update problem: ",$sth->{'update'}->errstr;
433                  clear_cont;                  clear_cont;
434                  return 0;                  return 0;
# Line 267  sub update_db { Line 439  sub update_db {
439                          return 0;                          return 0;
440                  }                  }
441                  print "updated '$file' [",$files{$file}{id},"]\n";                  print "updated '$file' [",$files{$file}{id},"]\n";
442    
443                    $$fuse_self->{'invalidate'}->() if (ref $$fuse_self->{'invalidate'});
444          }          }
445          return 1;          return 1;
446  }  }
447    
448  sub e_write {  sub e_write {
449          my $file = filename_fixup(shift);          my $file = filename_fixup(shift);
450          my ($buf_len,$off) = @_;          my ($buffer,$off) = @_;
451    
452          return -ENOENT() unless exists($files{$file});          return -ENOENT() unless exists($files{$file});
453    
454          my $len = length($files{$file}{cont});          my $cont = $files{$file}{cont};
455            my $len = length($cont);
456    
457          print "write '$file' [$len bytes] offset $off length\n";          print "write '$file' [$len bytes] offset $off length ",length($buffer),"\n";
458    
459          $files{$file}{cont} =          $files{$file}{cont} = "";
460                  substr($files{$file}{cont},0,$off) .  
461                  $buf_len .          $files{$file}{cont} .= substr($cont,0,$off) if ($off > 0);
462                  substr($files{$file}{cont},$off+length($buf_len));          $files{$file}{cont} .= $buffer;
463            $files{$file}{cont} .= substr($cont,$off+length($buffer),$len-$off-length($buffer)) if ($off+length($buffer) < $len);
464    
465            $files{$file}{size} = length($files{$file}{cont});
466    
467          if (! update_db($file)) {          if (! update_db($file)) {
468                  return -ENOSYS();                  return -ENOSYS();
469          } else {          } else {
470                  return length($buf_len);                  return length($buffer);
471          }          }
472  }  }
473    
# Line 297  sub e_truncate { Line 475  sub e_truncate {
475          my $file = filename_fixup(shift);          my $file = filename_fixup(shift);
476          my $size = shift;          my $size = shift;
477    
478            print "truncate to $size\n";
479    
480          $files{$file}{cont} = substr($files{$file}{cont},0,$size);          $files{$file}{cont} = substr($files{$file}{cont},0,$size);
481            $files{$file}{size} = $size;
482          return 0          return 0
483  };  };
484    
# Line 316  sub e_utime { Line 497  sub e_utime {
497    
498  sub e_statfs { return 255, 1, 1, 1, 1, 2 }  sub e_statfs { return 255, 1, 1, 1, 1, 2 }
499    
500    sub e_unlink {
501            my $file = filename_fixup(shift);
502    
503            if (exists( $dirs{$file} )) {
504                    print "unlink '$file' will re-read template names\n";
505                    print Dumper($fuse_self);
506                    $$fuse_self->{'read_filenames'}->();
507                    return 0;
508            } elsif (exists( $files{$file} )) {
509                    print "unlink '$file' will invalidate cache\n";
510                    read_content($file,$files{$file}{id});
511                    return 0;
512            }
513    
514            return -ENOENT();
515    }
516  1;  1;
517  __END__  __END__
518    
# Line 328  Nothing. Line 525  Nothing.
525  C<FUSE (Filesystem in USErspace)> website  C<FUSE (Filesystem in USErspace)> website
526  L<http://sourceforge.net/projects/avf>  L<http://sourceforge.net/projects/avf>
527    
528    Example for WebGUI which comes with this distribution in
529    directory C<examples/webgui.pl>. It also contains a lot of documentation
530    about design of this module, usage and limitations.
531    
532  =head1 AUTHOR  =head1 AUTHOR
533    
534  Dobrica Pavlinusic, E<lt>dpavlin@rot13.orgE<gt>  Dobrica Pavlinusic, E<lt>dpavlin@rot13.orgE<gt>
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