/[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 30 by dpavlin, Sat Oct 9 00:03:42 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 ($f =~ s/^\E$dirname\Q\///) {
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            $files{$file}{ctime} = time();
368            print "file '$file' content [",length($files{$file}{cont})," bytes] read in cache\n";
369    }
370    
371    
372  sub e_open {  sub e_open {
373          # 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.
374          my $file = filename_fixup(shift);          my $file = filename_fixup(shift);
# Line 209  sub e_open { Line 377  sub e_open {
377          return -ENOENT() unless exists($files{$file});          return -ENOENT() unless exists($files{$file});
378          return -EISDIR() unless exists($files{$file}{id});          return -EISDIR() unless exists($files{$file}{id});
379    
380          if (!exists($files{$file}{cont})) {          read_content($file,$files{$file}{id}) unless exists($files{$file}{cont});
381                  $sth->{'read'}->execute($files{$file}{id}) || die $sth->{'read'}->errstr;  
                 $files{$file}{cont} = $sth->{'read'}->fetchrow_array;  
                 print "file '$file' content read in cache\n";  
         }  
382          print "open '$file' ",length($files{$file}{cont})," bytes\n";          print "open '$file' ",length($files{$file}{cont})," bytes\n";
383          return 0;          return 0;
384  }  }
# Line 234  sub e_read { Line 399  sub e_read {
399          return -EINVAL() if ($off > $len);          return -EINVAL() if ($off > $len);
400          return 0 if ($off == $len);          return 0 if ($off == $len);
401    
402          $buf_len = $buf_len-$off if ($off+$buf_len > $len);          $buf_len = $len-$off if ($len - $off < $buf_len);
403    
404          return substr($files{$file}{cont},$off,$buf_len);          return substr($files{$file}{cont},$off,$buf_len);
405  }  }
# Line 247  sub clear_cont { Line 412  sub clear_cont {
412                  delete $files{$f}{cont};                  delete $files{$f}{cont};
413          }          }
414          print "begin new transaction\n";          print "begin new transaction\n";
415          $dbh->begin_work || die $dbh->errstr;          #$dbh->begin_work || die $dbh->errstr;
416  }  }
417    
418    
# Line 256  sub update_db { Line 421  sub update_db {
421    
422          $files{$file}{ctime} = time();          $files{$file}{ctime} = time();
423    
424          if (!$sth->{'update'}->execute($files{$file}{cont},$files{$file}{id})) {          my ($cont,$id) = (
425                    $files{$file}{cont},
426                    $files{$file}{id}
427            );
428    
429            if (!$sth->{'update'}->execute($cont,$id)) {
430                  print "update problem: ",$sth->{'update'}->errstr;                  print "update problem: ",$sth->{'update'}->errstr;
431                  clear_cont;                  clear_cont;
432                  return 0;                  return 0;
# Line 267  sub update_db { Line 437  sub update_db {
437                          return 0;                          return 0;
438                  }                  }
439                  print "updated '$file' [",$files{$file}{id},"]\n";                  print "updated '$file' [",$files{$file}{id},"]\n";
440    
441                    $$fuse_self->{'invalidate'}->() if (ref $$fuse_self->{'invalidate'});
442          }          }
443          return 1;          return 1;
444  }  }
445    
446  sub e_write {  sub e_write {
447          my $file = filename_fixup(shift);          my $file = filename_fixup(shift);
448          my ($buf_len,$off) = @_;          my ($buffer,$off) = @_;
449    
450          return -ENOENT() unless exists($files{$file});          return -ENOENT() unless exists($files{$file});
451    
452          my $len = length($files{$file}{cont});          my $cont = $files{$file}{cont};
453            my $len = length($cont);
454    
455          print "write '$file' [$len bytes] offset $off length\n";          print "write '$file' [$len bytes] offset $off length ",length($buffer),"\n";
456    
457          $files{$file}{cont} =          $files{$file}{cont} = "";
458                  substr($files{$file}{cont},0,$off) .  
459                  $buf_len .          $files{$file}{cont} .= substr($cont,0,$off) if ($off > 0);
460                  substr($files{$file}{cont},$off+length($buf_len));          $files{$file}{cont} .= $buffer;
461            $files{$file}{cont} .= substr($cont,$off+length($buffer),$len-$off-length($buffer)) if ($off+length($buffer) < $len);
462    
463            $files{$file}{size} = length($files{$file}{cont});
464    
465          if (! update_db($file)) {          if (! update_db($file)) {
466                  return -ENOSYS();                  return -ENOSYS();
467          } else {          } else {
468                  return length($buf_len);                  return length($buffer);
469          }          }
470  }  }
471    
# Line 297  sub e_truncate { Line 473  sub e_truncate {
473          my $file = filename_fixup(shift);          my $file = filename_fixup(shift);
474          my $size = shift;          my $size = shift;
475    
476            print "truncate to $size\n";
477    
478          $files{$file}{cont} = substr($files{$file}{cont},0,$size);          $files{$file}{cont} = substr($files{$file}{cont},0,$size);
479            $files{$file}{size} = $size;
480          return 0          return 0
481  };  };
482    
# Line 316  sub e_utime { Line 495  sub e_utime {
495    
496  sub e_statfs { return 255, 1, 1, 1, 1, 2 }  sub e_statfs { return 255, 1, 1, 1, 1, 2 }
497    
498    sub e_unlink {
499            my $file = filename_fixup(shift);
500    
501            if (exists( $dirs{$file} )) {
502                    print "unlink '$file' will re-read template names\n";
503                    print Dumper($fuse_self);
504                    $$fuse_self->{'read_filenames'}->();
505                    return 0;
506            } elsif (exists( $files{$file} )) {
507                    print "unlink '$file' will invalidate cache\n";
508                    read_content($file,$files{$file}{id});
509                    return 0;
510            }
511    
512            return -ENOENT();
513    }
514  1;  1;
515  __END__  __END__
516    
# Line 328  Nothing. Line 523  Nothing.
523  C<FUSE (Filesystem in USErspace)> website  C<FUSE (Filesystem in USErspace)> website
524  L<http://sourceforge.net/projects/avf>  L<http://sourceforge.net/projects/avf>
525    
526    Example for WebGUI which comes with this distribution in
527    directory C<examples/webgui.pl>. It also contains a lot of documentation
528    about design of this module, usage and limitations.
529    
530  =head1 AUTHOR  =head1 AUTHOR
531    
532  Dobrica Pavlinusic, E<lt>dpavlin@rot13.orgE<gt>  Dobrica Pavlinusic, E<lt>dpavlin@rot13.orgE<gt>
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