/[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 40 by dpavlin, Fri Nov 19 21:56:12 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 = '0.06';
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://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 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          my $arg = {@_};  # 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 $fuse_self;
125    
126          carp "run needs 'dsn' to connect to (e.g. dsn => 'DBI:Pg:dbname=test')" unless ($arg->{'dsn'});  sub mount {
127          carp "run needs 'mount' as mountpoint" unless ($arg->{'mount'});          my $class = shift;
128            my $self = {};
129            bless($self, $class);
130    
131            my $arg = shift;
132    
133            print Dumper($arg);
134    
135            carp "mount needs 'dsn' to connect to (e.g. dsn => 'DBI:Pg:dbname=test')" unless ($arg->{'dsn'});
136            carp "mount needs 'mount' as mountpoint" unless ($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            $dbh = DBI->connect($arg->{'dsn'},$arg->{'user'},$arg->{'password'}, {AutoCommit => 0, RaiseError => 1}) || die $DBI::errstr;
160    
161          $sth->{filenames} = $dbh->prepare($arg->{'filenames'}) || die $dbh->errstr();          $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            $fuse_self = \$self;
173    
174          Fuse::main(          Fuse::main(
175                  mountpoint=>$arg->{'mount'},                  mountpoint=>$arg->{'mount'},
# Line 94  sub run { Line 181  sub run {
181                  write=>\&e_write,                  write=>\&e_write,
182                  utime=>\&e_utime,                  utime=>\&e_utime,
183                  truncate=>\&e_truncate,                  truncate=>\&e_truncate,
184                    unlink=>\&e_unlink,
185                    rmdir=>\&e_unlink,
186                  debug=>0,                  debug=>0,
187          );          );
188            
189            exit(0) if ($arg->{'fork'});
190    
191            return 1;
192    
193  };  };
194    
195    =head2 umount
196    
197    Unmount your database as filesystem.
198    
199      $mnt->umount;
200    
201    This will also kill background process which is translating
202    database to filesystem.
203    
204    =cut
205    
206    sub umount {
207            my $self = shift;
208    
209            if ($self->{'mount'}) {
210                    if (open(MTAB, "/etc/mtab")) {
211                            my $mounted = 0;
212                            my $mount = $self->{'mount'};
213                            while(<MTAB>) {
214                                    $mounted = 1 if (/ $mount fuse /i);
215                            }
216                            close(MTAB);
217                    
218                            if ($mounted) {
219                                    system "fusermount -u ".$self->{'mount'}." 2>&1 >/dev/null" || return 0;
220                                    return 1;
221                            }
222    
223                    } else {
224                            warn "can't open /etc/mtab: $!";
225                            return 0;
226                    }
227            }
228    }
229    
230    $SIG{'INT'} = sub {
231            if ($fuse_self && $$fuse_self->umount) {
232                    print STDERR "umount called by SIG INT\n";
233            }
234    };
235    
236    $SIG{'QUIT'} = sub {
237            if ($fuse_self && $$fuse_self->umount) {
238                    print STDERR "umount called by SIG QUIT\n";
239            }
240    };
241    
242    sub DESTROY {
243            my $self = shift;
244            if ($self->umount) {
245                    print STDERR "umount called by DESTROY\n";
246            }
247    }
248    
249    =head2 fuse_module_loaded
250    
251    Checks if C<fuse> module is loaded in kernel.
252    
253      die "no fuse module loaded in kernel"
254            unless (Fuse::DBI::fuse_module_loaded);
255    
256    This function in called by C<mount>, but might be useful alone also.
257    
258    =cut
259    
260    sub fuse_module_loaded {
261            my $lsmod = `lsmod`;
262            die "can't start lsmod: $!" unless ($lsmod);
263            if ($lsmod =~ m/fuse/s) {
264                    return 1;
265            } else {
266                    return 0;
267            }
268    }
269    
270  my %files;  my %files;
271  my %dirs;  my %dirs;
272    
273  sub read_filenames {  sub read_filenames {
274            my $self = shift;
275    
276            my $sth = $self->{'sth'} || die "no sth argument";
277    
278          # create empty filesystem          # create empty filesystem
279          (%files) = (          (%files) = (
280                  '.' => {                  '.' => {
281                          type => 0040,                          type => 0040,
282                          mode => 0755,                          mode => 0755,
283                  },                  },
284                    '..' => {
285                            type => 0040,
286                            mode => 0755,
287                    },
288          #       a => {          #       a => {
289          #               cont => "File 'a'.\n",          #               cont => "File 'a'.\n",
290          #               type => 0100,          #               type => 0100,
# Line 184  sub e_getdir { Line 361  sub e_getdir {
361          # return as many text filenames as you like, followed by the retval.          # return as many text filenames as you like, followed by the retval.
362          print((scalar keys %files)." files total\n");          print((scalar keys %files)." files total\n");
363          my %out;          my %out;
364          foreach (keys %files) {          foreach my $f (sort keys %files) {
                 my $f = $_;  
                 $f =~ s/^\E$dirname\Q//;  
                 $f =~ s/^\///;  
365                  if ($dirname) {                  if ($dirname) {
366                          $out{$f}++ if (/^\E$dirname\Q/ && $f =~ /^[^\/]+$/);                          if ($f =~ s/^\Q$dirname\E\///) {
367                                    $out{$f}++ if ($f =~ /^[^\/]+$/);
368                            }
369                  } else {                  } else {
370                          $out{$f}++ if ($f =~ /^[^\/]+$/);                          $out{$f}++ if ($f =~ /^[^\/]+$/);
371                  }                  }
# Line 198  sub e_getdir { Line 374  sub e_getdir {
374                  $out{'no files? bug?'}++;                  $out{'no files? bug?'}++;
375          }          }
376          print scalar keys %out," files in dir '$dirname'\n";          print scalar keys %out," files in dir '$dirname'\n";
377            print "## ",join(" ",keys %out),"\n";
378          return (keys %out),0;          return (keys %out),0;
379  }  }
380    
381    sub read_content {
382            my ($file,$id) = @_;
383    
384            die "read_content needs file and id" unless ($file && $id);
385    
386            $sth->{'read'}->execute($id) || die $sth->{'read'}->errstr;
387            $files{$file}{cont} = $sth->{'read'}->fetchrow_array;
388            # I should modify ctime only if content in database changed
389            #$files{$file}{ctime} = time() unless ($files{$file}{ctime});
390            print "file '$file' content [",length($files{$file}{cont})," bytes] read in cache\n";
391    }
392    
393    
394  sub e_open {  sub e_open {
395          # 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.
396          my $file = filename_fixup(shift);          my $file = filename_fixup(shift);
# Line 209  sub e_open { Line 399  sub e_open {
399          return -ENOENT() unless exists($files{$file});          return -ENOENT() unless exists($files{$file});
400          return -EISDIR() unless exists($files{$file}{id});          return -EISDIR() unless exists($files{$file}{id});
401    
402          if (!exists($files{$file}{cont})) {          read_content($file,$files{$file}{id}) unless exists($files{$file}{cont});
403                  $sth->{'read'}->execute($files{$file}{id}) || die $sth->{'read'}->errstr;  
                 $files{$file}{cont} = $sth->{'read'}->fetchrow_array;  
                 print "file '$file' content read in cache\n";  
         }  
404          print "open '$file' ",length($files{$file}{cont})," bytes\n";          print "open '$file' ",length($files{$file}{cont})," bytes\n";
405          return 0;          return 0;
406  }  }
# Line 234  sub e_read { Line 421  sub e_read {
421          return -EINVAL() if ($off > $len);          return -EINVAL() if ($off > $len);
422          return 0 if ($off == $len);          return 0 if ($off == $len);
423    
424          $buf_len = $buf_len-$off if ($off+$buf_len > $len);          $buf_len = $len-$off if ($len - $off < $buf_len);
425    
426          return substr($files{$file}{cont},$off,$buf_len);          return substr($files{$file}{cont},$off,$buf_len);
427  }  }
# Line 245  sub clear_cont { Line 432  sub clear_cont {
432          print "invalidate all cached content\n";          print "invalidate all cached content\n";
433          foreach my $f (keys %files) {          foreach my $f (keys %files) {
434                  delete $files{$f}{cont};                  delete $files{$f}{cont};
435                    delete $files{$f}{ctime};
436          }          }
437          print "begin new transaction\n";          print "begin new transaction\n";
438          $dbh->begin_work || die $dbh->errstr;          #$dbh->begin_work || die $dbh->errstr;
439  }  }
440    
441    
# Line 256  sub update_db { Line 444  sub update_db {
444    
445          $files{$file}{ctime} = time();          $files{$file}{ctime} = time();
446    
447          if (!$sth->{'update'}->execute($files{$file}{cont},$files{$file}{id})) {          my ($cont,$id) = (
448                    $files{$file}{cont},
449                    $files{$file}{id}
450            );
451    
452            if (!$sth->{'update'}->execute($cont,$id)) {
453                  print "update problem: ",$sth->{'update'}->errstr;                  print "update problem: ",$sth->{'update'}->errstr;
454                  clear_cont;                  clear_cont;
455                  return 0;                  return 0;
# Line 267  sub update_db { Line 460  sub update_db {
460                          return 0;                          return 0;
461                  }                  }
462                  print "updated '$file' [",$files{$file}{id},"]\n";                  print "updated '$file' [",$files{$file}{id},"]\n";
463    
464                    $$fuse_self->{'invalidate'}->() if (ref $$fuse_self->{'invalidate'});
465          }          }
466          return 1;          return 1;
467  }  }
468    
469  sub e_write {  sub e_write {
470          my $file = filename_fixup(shift);          my $file = filename_fixup(shift);
471          my ($buf_len,$off) = @_;          my ($buffer,$off) = @_;
472    
473          return -ENOENT() unless exists($files{$file});          return -ENOENT() unless exists($files{$file});
474    
475          my $len = length($files{$file}{cont});          my $cont = $files{$file}{cont};
476            my $len = length($cont);
477    
478          print "write '$file' [$len bytes] offset $off length\n";          print "write '$file' [$len bytes] offset $off length ",length($buffer),"\n";
479    
480          $files{$file}{cont} =          $files{$file}{cont} = "";
481                  substr($files{$file}{cont},0,$off) .  
482                  $buf_len .          $files{$file}{cont} .= substr($cont,0,$off) if ($off > 0);
483                  substr($files{$file}{cont},$off+length($buf_len));          $files{$file}{cont} .= $buffer;
484            $files{$file}{cont} .= substr($cont,$off+length($buffer),$len-$off-length($buffer)) if ($off+length($buffer) < $len);
485    
486            $files{$file}{size} = length($files{$file}{cont});
487    
488          if (! update_db($file)) {          if (! update_db($file)) {
489                  return -ENOSYS();                  return -ENOSYS();
490          } else {          } else {
491                  return length($buf_len);                  return length($buffer);
492          }          }
493  }  }
494    
# Line 297  sub e_truncate { Line 496  sub e_truncate {
496          my $file = filename_fixup(shift);          my $file = filename_fixup(shift);
497          my $size = shift;          my $size = shift;
498    
499            print "truncate to $size\n";
500    
501          $files{$file}{cont} = substr($files{$file}{cont},0,$size);          $files{$file}{cont} = substr($files{$file}{cont},0,$size);
502            $files{$file}{size} = $size;
503          return 0          return 0
504  };  };
505    
# Line 316  sub e_utime { Line 518  sub e_utime {
518    
519  sub e_statfs { return 255, 1, 1, 1, 1, 2 }  sub e_statfs { return 255, 1, 1, 1, 1, 2 }
520    
521    sub e_unlink {
522            my $file = filename_fixup(shift);
523    
524            if (exists( $dirs{$file} )) {
525                    print "unlink '$file' will re-read template names\n";
526                    print Dumper($fuse_self);
527                    $$fuse_self->{'read_filenames'}->();
528                    return 0;
529            } elsif (exists( $files{$file} )) {
530                    print "unlink '$file' will invalidate cache\n";
531                    read_content($file,$files{$file}{id});
532                    return 0;
533            }
534    
535            return -ENOENT();
536    }
537  1;  1;
538  __END__  __END__
539    
# Line 323  __END__ Line 541  __END__
541    
542  Nothing.  Nothing.
543    
544    =head1 BUGS
545    
546    Size information (C<ls -s>) is wrong. It's a problem in upstream Fuse module
547    (for which I'm to blame lately), so when it gets fixes, C<Fuse::DBI> will
548    automagically pick it up.
549    
550  =head1 SEE ALSO  =head1 SEE ALSO
551    
552  C<FUSE (Filesystem in USErspace)> website  C<FUSE (Filesystem in USErspace)> website
553  L<http://sourceforge.net/projects/avf>  L<http://fuse.sourceforge.net/>
554    
555    Example for WebGUI which comes with this distribution in
556    directory C<examples/webgui.pl>. It also contains a lot of documentation
557    about design of this module, usage and limitations.
558    
559  =head1 AUTHOR  =head1 AUTHOR
560    
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