/[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 36 by dpavlin, Tue Nov 16 15:34:25 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 = '0.05';
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    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                    $self->{'mounted'} = 1;
152                    $pid = fork();
153                    die "fork() failed: $!" unless defined $pid;
154                    # child will return to caller
155                    if ($pid) {
156                            return $self;
157                    }
158            }
159    
160          $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;
161    
162            $sth->{'filenames'} = $dbh->prepare($arg->{'filenames'}) || die $dbh->errstr();
163    
164          $sth->{'read'} = $dbh->prepare($arg->{'read'}) || die $dbh->errstr();          $sth->{'read'} = $dbh->prepare($arg->{'read'}) || die $dbh->errstr();
165          $sth->{'update'} = $dbh->prepare($arg->{'update'}) || die $dbh->errstr();          $sth->{'update'} = $dbh->prepare($arg->{'update'}) || die $dbh->errstr();
166    
         $ctime_start = time();  
167    
168          read_filenames;          $self->{'sth'} = $sth;
169    
170            $self->{'read_filenames'} = sub { $self->read_filenames };
171            $self->read_filenames;
172    
173            $self->{'mounted'} = 1 unless ($arg->{'fork'});
174    
175            $fuse_self = \$self;
176    
177          Fuse::main(          Fuse::main(
178                  mountpoint=>$arg->{'mount'},                  mountpoint=>$arg->{'mount'},
# Line 94  sub run { Line 184  sub run {
184                  write=>\&e_write,                  write=>\&e_write,
185                  utime=>\&e_utime,                  utime=>\&e_utime,
186                  truncate=>\&e_truncate,                  truncate=>\&e_truncate,
187                    unlink=>\&e_unlink,
188                    rmdir=>\&e_unlink,
189                  debug=>0,                  debug=>0,
190          );          );
191            
192            $self->{'mounted'} = 0;
193    
194            exit(0) if ($arg->{'fork'});
195    
196            return 1;
197    
198  };  };
199    
200    =head2 umount
201    
202    Unmount your database as filesystem.
203    
204      $mnt->umount;
205    
206    This will also kill background process which is translating
207    database to filesystem.
208    
209    =cut
210    
211    sub umount {
212            my $self = shift;
213    
214            if ($self->{'mounted'}) {
215                    system "fusermount -u ".$self->{'mount'} || warn "umount error: $!" && return 0;
216            }
217    
218            return 1;
219    }
220    
221    $SIG{'INT'} = sub {
222            print STDERR "umount called by SIG INT\n";
223            umount;
224    };
225    
226    sub DESTROY {
227            my $self = shift;
228            return if (! $self->{'mounted'});
229            print STDERR "umount called by DESTROY\n";
230            $self->umount;
231    }
232    
233    =head2 fuse_module_loaded
234    
235    Checks if C<fuse> module is loaded in kernel.
236    
237      die "no fuse module loaded in kernel"
238            unless (Fuse::DBI::fuse_module_loaded);
239    
240    This function in called by C<mount>, but might be useful alone also.
241    
242    =cut
243    
244    sub fuse_module_loaded {
245            my $lsmod = `lsmod`;
246            die "can't start lsmod: $!" unless ($lsmod);
247            if ($lsmod =~ m/fuse/s) {
248                    return 1;
249            } else {
250                    return 0;
251            }
252    }
253    
254  my %files;  my %files;
255  my %dirs;  my %dirs;
256    
257  sub read_filenames {  sub read_filenames {
258            my $self = shift;
259    
260            my $sth = $self->{'sth'} || die "no sth argument";
261    
262          # create empty filesystem          # create empty filesystem
263          (%files) = (          (%files) = (
264                  '.' => {                  '.' => {
# Line 184  sub e_getdir { Line 341  sub e_getdir {
341          # return as many text filenames as you like, followed by the retval.          # return as many text filenames as you like, followed by the retval.
342          print((scalar keys %files)." files total\n");          print((scalar keys %files)." files total\n");
343          my %out;          my %out;
344          foreach (keys %files) {          foreach my $f (sort keys %files) {
                 my $f = $_;  
                 $f =~ s/^\E$dirname\Q//;  
                 $f =~ s/^\///;  
345                  if ($dirname) {                  if ($dirname) {
346                          $out{$f}++ if (/^\E$dirname\Q/ && $f =~ /^[^\/]+$/);                          if ($f =~ s/^\Q$dirname\E\///) {
347                                    $out{$f}++ if ($f =~ /^[^\/]+$/);
348                            }
349                  } else {                  } else {
350                          $out{$f}++ if ($f =~ /^[^\/]+$/);                          $out{$f}++ if ($f =~ /^[^\/]+$/);
351                  }                  }
# Line 198  sub e_getdir { Line 354  sub e_getdir {
354                  $out{'no files? bug?'}++;                  $out{'no files? bug?'}++;
355          }          }
356          print scalar keys %out," files in dir '$dirname'\n";          print scalar keys %out," files in dir '$dirname'\n";
357            print "## ",join(" ",keys %out),"\n";
358          return (keys %out),0;          return (keys %out),0;
359  }  }
360    
361    sub read_content {
362            my ($file,$id) = @_;
363    
364            die "read_content needs file and id" unless ($file && $id);
365    
366            $sth->{'read'}->execute($id) || die $sth->{'read'}->errstr;
367            $files{$file}{cont} = $sth->{'read'}->fetchrow_array;
368            # I should modify ctime only if content in database changed
369            #$files{$file}{ctime} = time() unless ($files{$file}{ctime});
370            print "file '$file' content [",length($files{$file}{cont})," bytes] read in cache\n";
371    }
372    
373    
374  sub e_open {  sub e_open {
375          # 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.
376          my $file = filename_fixup(shift);          my $file = filename_fixup(shift);
# Line 209  sub e_open { Line 379  sub e_open {
379          return -ENOENT() unless exists($files{$file});          return -ENOENT() unless exists($files{$file});
380          return -EISDIR() unless exists($files{$file}{id});          return -EISDIR() unless exists($files{$file}{id});
381    
382          if (!exists($files{$file}{cont})) {          read_content($file,$files{$file}{id}) unless exists($files{$file}{cont});
383                  $sth->{'read'}->execute($files{$file}{id}) || die $sth->{'read'}->errstr;  
                 $files{$file}{cont} = $sth->{'read'}->fetchrow_array;  
                 print "file '$file' content read in cache\n";  
         }  
384          print "open '$file' ",length($files{$file}{cont})," bytes\n";          print "open '$file' ",length($files{$file}{cont})," bytes\n";
385          return 0;          return 0;
386  }  }
# Line 234  sub e_read { Line 401  sub e_read {
401          return -EINVAL() if ($off > $len);          return -EINVAL() if ($off > $len);
402          return 0 if ($off == $len);          return 0 if ($off == $len);
403    
404          $buf_len = $buf_len-$off if ($off+$buf_len > $len);          $buf_len = $len-$off if ($len - $off < $buf_len);
405    
406          return substr($files{$file}{cont},$off,$buf_len);          return substr($files{$file}{cont},$off,$buf_len);
407  }  }
# Line 245  sub clear_cont { Line 412  sub clear_cont {
412          print "invalidate all cached content\n";          print "invalidate all cached content\n";
413          foreach my $f (keys %files) {          foreach my $f (keys %files) {
414                  delete $files{$f}{cont};                  delete $files{$f}{cont};
415                    delete $files{$f}{ctime};
416          }          }
417          print "begin new transaction\n";          print "begin new transaction\n";
418          $dbh->begin_work || die $dbh->errstr;          #$dbh->begin_work || die $dbh->errstr;
419  }  }
420    
421    
# Line 256  sub update_db { Line 424  sub update_db {
424    
425          $files{$file}{ctime} = time();          $files{$file}{ctime} = time();
426    
427          if (!$sth->{'update'}->execute($files{$file}{cont},$files{$file}{id})) {          my ($cont,$id) = (
428                    $files{$file}{cont},
429                    $files{$file}{id}
430            );
431    
432            if (!$sth->{'update'}->execute($cont,$id)) {
433                  print "update problem: ",$sth->{'update'}->errstr;                  print "update problem: ",$sth->{'update'}->errstr;
434                  clear_cont;                  clear_cont;
435                  return 0;                  return 0;
# Line 267  sub update_db { Line 440  sub update_db {
440                          return 0;                          return 0;
441                  }                  }
442                  print "updated '$file' [",$files{$file}{id},"]\n";                  print "updated '$file' [",$files{$file}{id},"]\n";
443    
444                    $$fuse_self->{'invalidate'}->() if (ref $$fuse_self->{'invalidate'});
445          }          }
446          return 1;          return 1;
447  }  }
448    
449  sub e_write {  sub e_write {
450          my $file = filename_fixup(shift);          my $file = filename_fixup(shift);
451          my ($buf_len,$off) = @_;          my ($buffer,$off) = @_;
452    
453          return -ENOENT() unless exists($files{$file});          return -ENOENT() unless exists($files{$file});
454    
455          my $len = length($files{$file}{cont});          my $cont = $files{$file}{cont};
456            my $len = length($cont);
457    
458          print "write '$file' [$len bytes] offset $off length\n";          print "write '$file' [$len bytes] offset $off length ",length($buffer),"\n";
459    
460          $files{$file}{cont} =          $files{$file}{cont} = "";
461                  substr($files{$file}{cont},0,$off) .  
462                  $buf_len .          $files{$file}{cont} .= substr($cont,0,$off) if ($off > 0);
463                  substr($files{$file}{cont},$off+length($buf_len));          $files{$file}{cont} .= $buffer;
464            $files{$file}{cont} .= substr($cont,$off+length($buffer),$len-$off-length($buffer)) if ($off+length($buffer) < $len);
465    
466            $files{$file}{size} = length($files{$file}{cont});
467    
468          if (! update_db($file)) {          if (! update_db($file)) {
469                  return -ENOSYS();                  return -ENOSYS();
470          } else {          } else {
471                  return length($buf_len);                  return length($buffer);
472          }          }
473  }  }
474    
# Line 297  sub e_truncate { Line 476  sub e_truncate {
476          my $file = filename_fixup(shift);          my $file = filename_fixup(shift);
477          my $size = shift;          my $size = shift;
478    
479            print "truncate to $size\n";
480    
481          $files{$file}{cont} = substr($files{$file}{cont},0,$size);          $files{$file}{cont} = substr($files{$file}{cont},0,$size);
482            $files{$file}{size} = $size;
483          return 0          return 0
484  };  };
485    
# Line 316  sub e_utime { Line 498  sub e_utime {
498    
499  sub e_statfs { return 255, 1, 1, 1, 1, 2 }  sub e_statfs { return 255, 1, 1, 1, 1, 2 }
500    
501    sub e_unlink {
502            my $file = filename_fixup(shift);
503    
504            if (exists( $dirs{$file} )) {
505                    print "unlink '$file' will re-read template names\n";
506                    print Dumper($fuse_self);
507                    $$fuse_self->{'read_filenames'}->();
508                    return 0;
509            } elsif (exists( $files{$file} )) {
510                    print "unlink '$file' will invalidate cache\n";
511                    read_content($file,$files{$file}{id});
512                    return 0;
513            }
514    
515            return -ENOENT();
516    }
517  1;  1;
518  __END__  __END__
519    
# Line 326  Nothing. Line 524  Nothing.
524  =head1 SEE ALSO  =head1 SEE ALSO
525    
526  C<FUSE (Filesystem in USErspace)> website  C<FUSE (Filesystem in USErspace)> website
527  L<http://sourceforge.net/projects/avf>  L<http://fuse.sourceforge.net/>
528    
529    Example for WebGUI which comes with this distribution in
530    directory C<examples/webgui.pl>. It also contains a lot of documentation
531    about design of this module, usage and limitations.
532    
533  =head1 AUTHOR  =head1 AUTHOR
534    
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