/[fuse_dbi]/fuse-couchdb/DBI.pm
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revision 23 by dpavlin, Sat Oct 2 16:54:42 2004 UTC revision 36 by dpavlin, Tue Nov 16 15:34:25 2004 UTC
# Line 13  use Carp; Line 13  use Carp;
13  use Data::Dumper;  use Data::Dumper;
14    
15    
16  our $VERSION = '0.03';  our $VERSION = '0.05';
17    
18  =head1 NAME  =head1 NAME
19    
# Line 24  Fuse::DBI - mount your database as files Line 24  Fuse::DBI - mount your database as files
24    use Fuse::DBI;    use Fuse::DBI;
25    Fuse::DBI->mount( ... );    Fuse::DBI->mount( ... );
26    
27  See C<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 C<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 46  It's actually opposite of Oracle's inten Line 46  It's actually opposite of Oracle's inten
46    
47  Mount your database as filesystem.  Mount your database as filesystem.
48    
49    Let's suppose that your database have table C<files> with following structure:
50    
51     id:            int
52     filename:      text
53     size:          int
54     content:       text
55     writable:      boolean
56    
57    Following is example how to mount table like that to C</mnt>:
58    
59    my $mnt = Fuse::DBI->mount({    my $mnt = Fuse::DBI->mount({
60          filenames => 'select name from files_table as filenames',          'filenames' => 'select id,filename,size,writable from files',
61          read => 'sql read',          'read' => 'select content from files where id = ?',
62          update => 'sql update',          'update' => 'update files set content = ? where id = ?',
63          dsn => 'DBI:Pg:dbname=webgui',          'dsn' => 'DBI:Pg:dbname=test_db',
64          user => 'database_user',          'user' => 'database_user',
65          password => 'database_password'          '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;
# Line 64  my $ctime_start; Line 118  my $ctime_start;
118  sub read_filenames;  sub read_filenames;
119  sub fuse_module_loaded;  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 {  sub mount {
127          my $class = shift;          my $class = shift;
128          my $self = {};          my $self = {};
# Line 77  sub mount { Line 136  sub mount {
136          carp "mount needs 'mount' as mountpoint" unless ($arg->{'mount'});          carp "mount needs 'mount' as mountpoint" unless ($arg->{'mount'});
137    
138          # save (some) arguments in self          # save (some) arguments in self
139          $self->{$_} = $arg->{$_} foreach (qw(mount));          foreach (qw(mount invalidate)) {
140                    $self->{$_} = $arg->{$_};
141            }
142    
143          foreach (qw(filenames read update)) {          foreach (qw(filenames read update)) {
144                  carp "mount needs '$_' SQL" unless ($arg->{$_});                  carp "mount needs '$_' SQL" unless ($arg->{$_});
# Line 87  sub mount { Line 148  sub mount {
148    
149          my $pid;          my $pid;
150          if ($arg->{'fork'}) {          if ($arg->{'fork'}) {
151                    $self->{'mounted'} = 1;
152                  $pid = fork();                  $pid = fork();
153                  die "fork() failed: $!" unless defined $pid;                  die "fork() failed: $!" unless defined $pid;
154                  # child will return to caller                  # child will return to caller
# Line 97  sub mount { Line 159  sub mount {
159    
160          $dbh = DBI->connect($arg->{'dsn'},$arg->{'user'},$arg->{'password'}, {AutoCommit => 0, RaiseError => 1}) || die $DBI::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();          $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    
167    
168            $self->{'sth'} = $sth;
169    
170            $self->{'read_filenames'} = sub { $self->read_filenames };
171          $self->read_filenames;          $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'},
179                  getattr=>\&e_getattr,                  getattr=>\&e_getattr,
# Line 115  sub mount { Line 185  sub mount {
185                  utime=>\&e_utime,                  utime=>\&e_utime,
186                  truncate=>\&e_truncate,                  truncate=>\&e_truncate,
187                  unlink=>\&e_unlink,                  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'});          exit(0) if ($arg->{'fork'});
195    
# Line 138  database to filesystem. Line 211  database to filesystem.
211  sub umount {  sub umount {
212          my $self = shift;          my $self = shift;
213    
214          system "fusermount -u ".$self->{'mount'} || croak "umount error: $!";          if ($self->{'mounted'}) {
215                    system "fusermount -u ".$self->{'mount'} || warn "umount error: $!" && return 0;
216            }
217    
218          return 1;          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  =head2 fuse_module_loaded
234    
235  Checks if C<fuse> module is loaded in kernel.  Checks if C<fuse> module is loaded in kernel.
# Line 150  Checks if C<fuse> module is loaded in ke Line 237  Checks if C<fuse> module is loaded in ke
237    die "no fuse module loaded in kernel"    die "no fuse module loaded in kernel"
238          unless (Fuse::DBI::fuse_module_loaded);          unless (Fuse::DBI::fuse_module_loaded);
239    
240  This function in called by L<mount>, but might be useful alone also.  This function in called by C<mount>, but might be useful alone also.
241    
242  =cut  =cut
243    
# Line 170  my %dirs; Line 257  my %dirs;
257  sub read_filenames {  sub read_filenames {
258          my $self = shift;          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 254  sub e_getdir { Line 343  sub e_getdir {
343          my %out;          my %out;
344          foreach my $f (sort keys %files) {          foreach my $f (sort keys %files) {
345                  if ($dirname) {                  if ($dirname) {
346                          if ($f =~ s/^\E$dirname\Q\///) {                          if ($f =~ s/^\Q$dirname\E\///) {
347                                  $out{$f}++ if ($f =~ /^[^\/]+$/);                                  $out{$f}++ if ($f =~ /^[^\/]+$/);
348                          }                          }
349                  } else {                  } else {
# Line 276  sub read_content { Line 365  sub read_content {
365    
366          $sth->{'read'}->execute($id) || die $sth->{'read'}->errstr;          $sth->{'read'}->execute($id) || die $sth->{'read'}->errstr;
367          $files{$file}{cont} = $sth->{'read'}->fetchrow_array;          $files{$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";          print "file '$file' content [",length($files{$file}{cont})," bytes] read in cache\n";
371  }  }
372    
# Line 321  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 $dbh->errstr;
# Line 348  sub update_db { Line 440  sub update_db {
440                          return 0;                          return 0;
441                  }                  }
442                  print "updated '$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  }  }
# Line 407  sub e_statfs { return 255, 1, 1, 1, 1, 2 Line 501  sub e_statfs { return 255, 1, 1, 1, 1, 2
501  sub e_unlink {  sub e_unlink {
502          my $file = filename_fixup(shift);          my $file = filename_fixup(shift);
503    
504          return -ENOENT() unless exists($files{$file});          if (exists( $dirs{$file} )) {
505                    print "unlink '$file' will re-read template names\n";
506          print "unlink '$file' will invalidate cache\n";                  print Dumper($fuse_self);
507                    $$fuse_self->{'read_filenames'}->();
508          read_content($file,$files{$file}{id});                  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 0;          return -ENOENT();
516  }  }
517  1;  1;
518  __END__  __END__
# Line 425  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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