/[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 47 by dpavlin, Tue Nov 23 23:54:58 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 = '0.07';
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    # 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          my $arg = {@_};  sub mount {
127            my $class = shift;
128            my $self = {};
129            bless($self, $class);
130    
131          carp "run needs 'dsn' to connect to (e.g. dsn => 'DBI:Pg:dbname=test')" unless ($arg->{'dsn'});          my $arg = shift;
132          carp "run needs 'mount' as mountpoint" unless ($arg->{'mount'});  
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                            my $counter = 4;
156                            while ($counter && ! $self->is_mounted) {
157                                    select(undef, undef, undef, 0.5);
158                                    $counter--;
159                            }
160                            if ($self->is_mounted) {
161                                    return $self;
162                            } else {
163                                    return undef;
164                            }
165                    }
166            }
167    
168            $dbh = DBI->connect($arg->{'dsn'},$arg->{'user'},$arg->{'password'}, {AutoCommit => 0, RaiseError => 1}) || die $DBI::errstr;
169    
170          $sth->{filenames} = $dbh->prepare($arg->{'filenames'}) || die $dbh->errstr();          $sth->{'filenames'} = $dbh->prepare($arg->{'filenames'}) || die $dbh->errstr();
171    
172          $sth->{'read'} = $dbh->prepare($arg->{'read'}) || die $dbh->errstr();          $sth->{'read'} = $dbh->prepare($arg->{'read'}) || die $dbh->errstr();
173          $sth->{'update'} = $dbh->prepare($arg->{'update'}) || die $dbh->errstr();          $sth->{'update'} = $dbh->prepare($arg->{'update'}) || die $dbh->errstr();
174    
         $ctime_start = time();  
175    
176          read_filenames;          $self->{'sth'} = $sth;
177    
178            $self->{'read_filenames'} = sub { $self->read_filenames };
179            $self->read_filenames;
180    
181            $fuse_self = \$self;
182    
183          Fuse::main(          Fuse::main(
184                  mountpoint=>$arg->{'mount'},                  mountpoint=>$arg->{'mount'},
# Line 94  sub run { Line 190  sub run {
190                  write=>\&e_write,                  write=>\&e_write,
191                  utime=>\&e_utime,                  utime=>\&e_utime,
192                  truncate=>\&e_truncate,                  truncate=>\&e_truncate,
193                    unlink=>\&e_unlink,
194                    rmdir=>\&e_unlink,
195                  debug=>0,                  debug=>0,
196          );          );
197            
198            exit(0) if ($arg->{'fork'});
199    
200            return 1;
201    
202    };
203    
204    =head2 is_mounted
205    
206    Check if fuse filesystem is mounted
207    
208      if ($mnt->is_mounted) { ... }
209    
210    =cut
211    
212    sub is_mounted {
213            my $self = shift;
214    
215            my $mounted = 0;
216            my $mount = $self->{'mount'} || confess "can't find mount point!";
217            if (open(MTAB, "/etc/mtab")) {
218                    while(<MTAB>) {
219                            $mounted = 1 if (/ $mount fuse /i);
220                    }
221                    close(MTAB);
222            } else {
223                    warn "can't open /etc/mtab: $!";
224            }
225    
226            return $mounted;
227    }
228    
229    
230    =head2 umount
231    
232    Unmount your database as filesystem.
233    
234      $mnt->umount;
235    
236    This will also kill background process which is translating
237    database to filesystem.
238    
239    =cut
240    
241    sub umount {
242            my $self = shift;
243    
244            if ($self->{'mount'} && $self->is_mounted) {
245                    system "fusermount -u ".$self->{'mount'}." 2>&1 >/dev/null" || return 0;
246                    return 1;
247            }
248    
249            return 0;
250    }
251    
252    $SIG{'INT'} = sub {
253            if ($fuse_self && $$fuse_self->umount) {
254                    print STDERR "umount called by SIG INT\n";
255            }
256    };
257    
258    $SIG{'QUIT'} = sub {
259            if ($fuse_self && $$fuse_self->umount) {
260                    print STDERR "umount called by SIG QUIT\n";
261            }
262  };  };
263    
264    sub DESTROY {
265            my $self = shift;
266            if ($self->umount) {
267                    print STDERR "umount called by DESTROY\n";
268            }
269    }
270    
271    =head2 fuse_module_loaded
272    
273    Checks if C<fuse> module is loaded in kernel.
274    
275      die "no fuse module loaded in kernel"
276            unless (Fuse::DBI::fuse_module_loaded);
277    
278    This function in called by C<mount>, but might be useful alone also.
279    
280    =cut
281    
282    sub fuse_module_loaded {
283            my $lsmod = `lsmod`;
284            die "can't start lsmod: $!" unless ($lsmod);
285            if ($lsmod =~ m/fuse/s) {
286                    return 1;
287            } else {
288                    return 0;
289            }
290    }
291    
292  my %files;  my %files;
293  my %dirs;  my %dirs;
294    
295  sub read_filenames {  sub read_filenames {
296            my $self = shift;
297    
298            my $sth = $self->{'sth'} || die "no sth argument";
299    
300          # create empty filesystem          # create empty filesystem
301          (%files) = (          (%files) = (
302                  '.' => {                  '.' => {
303                          type => 0040,                          type => 0040,
304                          mode => 0755,                          mode => 0755,
305                  },                  },
306                    '..' => {
307                            type => 0040,
308                            mode => 0755,
309                    },
310          #       a => {          #       a => {
311          #               cont => "File 'a'.\n",          #               cont => "File 'a'.\n",
312          #               type => 0100,          #               type => 0100,
# Line 184  sub e_getdir { Line 383  sub e_getdir {
383          # return as many text filenames as you like, followed by the retval.          # return as many text filenames as you like, followed by the retval.
384          print((scalar keys %files)." files total\n");          print((scalar keys %files)." files total\n");
385          my %out;          my %out;
386          foreach (keys %files) {          foreach my $f (sort keys %files) {
                 my $f = $_;  
                 $f =~ s/^\E$dirname\Q//;  
                 $f =~ s/^\///;  
387                  if ($dirname) {                  if ($dirname) {
388                          $out{$f}++ if (/^\E$dirname\Q/ && $f =~ /^[^\/]+$/);                          if ($f =~ s/^\Q$dirname\E\///) {
389                                    $out{$f}++ if ($f =~ /^[^\/]+$/);
390                            }
391                  } else {                  } else {
392                          $out{$f}++ if ($f =~ /^[^\/]+$/);                          $out{$f}++ if ($f =~ /^[^\/]+$/);
393                  }                  }
# Line 198  sub e_getdir { Line 396  sub e_getdir {
396                  $out{'no files? bug?'}++;                  $out{'no files? bug?'}++;
397          }          }
398          print scalar keys %out," files in dir '$dirname'\n";          print scalar keys %out," files in dir '$dirname'\n";
399            print "## ",join(" ",keys %out),"\n";
400          return (keys %out),0;          return (keys %out),0;
401  }  }
402    
403    sub read_content {
404            my ($file,$id) = @_;
405    
406            die "read_content needs file and id" unless ($file && $id);
407    
408            $sth->{'read'}->execute($id) || die $sth->{'read'}->errstr;
409            $files{$file}{cont} = $sth->{'read'}->fetchrow_array;
410            # I should modify ctime only if content in database changed
411            #$files{$file}{ctime} = time() unless ($files{$file}{ctime});
412            print "file '$file' content [",length($files{$file}{cont})," bytes] read in cache\n";
413    }
414    
415    
416  sub e_open {  sub e_open {
417          # 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.
418          my $file = filename_fixup(shift);          my $file = filename_fixup(shift);
# Line 209  sub e_open { Line 421  sub e_open {
421          return -ENOENT() unless exists($files{$file});          return -ENOENT() unless exists($files{$file});
422          return -EISDIR() unless exists($files{$file}{id});          return -EISDIR() unless exists($files{$file}{id});
423    
424          if (!exists($files{$file}{cont})) {          read_content($file,$files{$file}{id}) unless exists($files{$file}{cont});
425                  $sth->{'read'}->execute($files{$file}{id}) || die $sth->{'read'}->errstr;  
                 $files{$file}{cont} = $sth->{'read'}->fetchrow_array;  
                 print "file '$file' content read in cache\n";  
         }  
426          print "open '$file' ",length($files{$file}{cont})," bytes\n";          print "open '$file' ",length($files{$file}{cont})," bytes\n";
427          return 0;          return 0;
428  }  }
# Line 234  sub e_read { Line 443  sub e_read {
443          return -EINVAL() if ($off > $len);          return -EINVAL() if ($off > $len);
444          return 0 if ($off == $len);          return 0 if ($off == $len);
445    
446          $buf_len = $buf_len-$off if ($off+$buf_len > $len);          $buf_len = $len-$off if ($len - $off < $buf_len);
447    
448          return substr($files{$file}{cont},$off,$buf_len);          return substr($files{$file}{cont},$off,$buf_len);
449  }  }
# Line 245  sub clear_cont { Line 454  sub clear_cont {
454          print "invalidate all cached content\n";          print "invalidate all cached content\n";
455          foreach my $f (keys %files) {          foreach my $f (keys %files) {
456                  delete $files{$f}{cont};                  delete $files{$f}{cont};
457                    delete $files{$f}{ctime};
458          }          }
459          print "begin new transaction\n";          print "begin new transaction\n";
460          $dbh->begin_work || die $dbh->errstr;          #$dbh->begin_work || die $dbh->errstr;
461  }  }
462    
463    
# Line 256  sub update_db { Line 466  sub update_db {
466    
467          $files{$file}{ctime} = time();          $files{$file}{ctime} = time();
468    
469          if (!$sth->{'update'}->execute($files{$file}{cont},$files{$file}{id})) {          my ($cont,$id) = (
470                    $files{$file}{cont},
471                    $files{$file}{id}
472            );
473    
474            if (!$sth->{'update'}->execute($cont,$id)) {
475                  print "update problem: ",$sth->{'update'}->errstr;                  print "update problem: ",$sth->{'update'}->errstr;
476                  clear_cont;                  clear_cont;
477                  return 0;                  return 0;
# Line 267  sub update_db { Line 482  sub update_db {
482                          return 0;                          return 0;
483                  }                  }
484                  print "updated '$file' [",$files{$file}{id},"]\n";                  print "updated '$file' [",$files{$file}{id},"]\n";
485    
486                    $$fuse_self->{'invalidate'}->() if (ref $$fuse_self->{'invalidate'});
487          }          }
488          return 1;          return 1;
489  }  }
490    
491  sub e_write {  sub e_write {
492          my $file = filename_fixup(shift);          my $file = filename_fixup(shift);
493          my ($buf_len,$off) = @_;          my ($buffer,$off) = @_;
494    
495          return -ENOENT() unless exists($files{$file});          return -ENOENT() unless exists($files{$file});
496    
497          my $len = length($files{$file}{cont});          my $cont = $files{$file}{cont};
498            my $len = length($cont);
499    
500            print "write '$file' [$len bytes] offset $off length ",length($buffer),"\n";
501    
502          print "write '$file' [$len bytes] offset $off length\n";          $files{$file}{cont} = "";
503    
504          $files{$file}{cont} =          $files{$file}{cont} .= substr($cont,0,$off) if ($off > 0);
505                  substr($files{$file}{cont},0,$off) .          $files{$file}{cont} .= $buffer;
506                  $buf_len .          $files{$file}{cont} .= substr($cont,$off+length($buffer),$len-$off-length($buffer)) if ($off+length($buffer) < $len);
507                  substr($files{$file}{cont},$off+length($buf_len));  
508            $files{$file}{size} = length($files{$file}{cont});
509    
510          if (! update_db($file)) {          if (! update_db($file)) {
511                  return -ENOSYS();                  return -ENOSYS();
512          } else {          } else {
513                  return length($buf_len);                  return length($buffer);
514          }          }
515  }  }
516    
# Line 297  sub e_truncate { Line 518  sub e_truncate {
518          my $file = filename_fixup(shift);          my $file = filename_fixup(shift);
519          my $size = shift;          my $size = shift;
520    
521            print "truncate to $size\n";
522    
523          $files{$file}{cont} = substr($files{$file}{cont},0,$size);          $files{$file}{cont} = substr($files{$file}{cont},0,$size);
524            $files{$file}{size} = $size;
525          return 0          return 0
526  };  };
527    
# Line 316  sub e_utime { Line 540  sub e_utime {
540    
541  sub e_statfs { return 255, 1, 1, 1, 1, 2 }  sub e_statfs { return 255, 1, 1, 1, 1, 2 }
542    
543    sub e_unlink {
544            my $file = filename_fixup(shift);
545    
546            if (exists( $dirs{$file} )) {
547                    print "unlink '$file' will re-read template names\n";
548                    print Dumper($fuse_self);
549                    $$fuse_self->{'read_filenames'}->();
550                    return 0;
551            } elsif (exists( $files{$file} )) {
552                    print "unlink '$file' will invalidate cache\n";
553                    read_content($file,$files{$file}{id});
554                    return 0;
555            }
556    
557            return -ENOENT();
558    }
559  1;  1;
560  __END__  __END__
561    
# Line 323  __END__ Line 563  __END__
563    
564  Nothing.  Nothing.
565    
566    =head1 BUGS
567    
568    Size information (C<ls -s>) is wrong. It's a problem in upstream Fuse module
569    (for which I'm to blame lately), so when it gets fixes, C<Fuse::DBI> will
570    automagically pick it up.
571    
572  =head1 SEE ALSO  =head1 SEE ALSO
573    
574  C<FUSE (Filesystem in USErspace)> website  C<FUSE (Filesystem in USErspace)> website
575  L<http://sourceforge.net/projects/avf>  L<http://fuse.sourceforge.net/>
576    
577    Example for WebGUI which comes with this distribution in
578    directory C<examples/webgui.pl>. It also contains a lot of documentation
579    about design of this module, usage and limitations.
580    
581  =head1 AUTHOR  =head1 AUTHOR
582    
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