use Fuse;
use DBI;
use Carp;
-use Proc::Simple;
use Data::Dumper;
-our $VERSION = '0.02';
+our $VERSION = '0.04';
=head1 NAME
use Fuse::DBI;
Fuse::DBI->mount( ... );
-See L<run> below for examples how to set parametars.
+See C<run> below for examples how to set parameters.
=head1 DESCRIPTION
-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)>
available at L<http://sourceforge.net/projects/avf> to mount
your database as file system.
-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)
to manipulate data in database.
It's actually opposite of Oracle's intention to put everything into database.
Mount your database as filesystem.
+Let's suppose that your database have table C<files> with following structure:
+
+ id: int
+ filename: text
+ size: int
+ content: text
+ writable: boolean
+
+Following is example how to mount table like that to C</mnt>:
+
my $mnt = Fuse::DBI->mount({
- filenames => 'select name from filenamefilenames,
- read => 'sql read',
- update => 'sql update',
- dsn => 'DBI:Pg:dbname=webgui',
- user => 'database_user',
- password => 'database_password'
+ 'filenames' => 'select id,filename,size,writable from files',
+ 'read' => 'select content from files where id = ?',
+ 'update' => 'update files set content = ? where id = ?',
+ 'dsn' => 'DBI:Pg:dbname=test_db',
+ 'user' => 'database_user',
+ 'password' => 'database_password',
+ 'invalidate' => sub { ... },
});
+Options:
+
+=over 5
+
+=item filenames
+
+SQL query which returns C<id> (unique id for that row), C<filename>,
+C<size> and C<writable> boolean flag.
+
+=item read
+
+SQL query which returns only one column with content of file and has
+placeholder C<?> for C<id>.
+
+=item update
+
+SQL query with two pace-holders, one for new content and one for C<id>.
+
+=item dsn
+
+C<DBI> dsn to connect to (contains database driver and name of database).
+
+=item user
+
+User with which to connect to database
+
+=item password
+
+Password for connecting to database
+
+=item invalidate
+
+Optional anonymous code reference which will be executed when data is updated in
+database. It can be used as hook to delete cache (for example on-disk-cache)
+which is created from data edited through C<Fuse::DBI>.
+
+=item fork
+
+Optional flag which forks after mount so that executing script will continue
+running. Implementation is experimental.
+
+=back
+
=cut
my $dbh;
my $ctime_start;
sub read_filenames;
+sub fuse_module_loaded;
+
+# evil, evil way to solve this. It makes this module non-reentrant. But, since
+# fuse calls another copy of this script for each mount anyway, this shouldn't
+# be a problem.
+my $fuse_self;
sub mount {
my $class = shift;
carp "mount needs 'mount' as mountpoint" unless ($arg->{'mount'});
# save (some) arguments in self
- $self->{$_} = $arg->{$_} foreach (qw(mount));
+ foreach (qw(mount invalidate)) {
+ $self->{$_} = $arg->{$_};
+ }
foreach (qw(filenames read update)) {
carp "mount needs '$_' SQL" unless ($arg->{$_});
}
- $dbh = DBI->connect($arg->{'dsn'},$arg->{'user'},$arg->{'password'}, { AutoCommit => 0 }) || die $DBI::errstr;
+ $ctime_start = time();
- print "start transaction\n";
- $dbh->begin_work || die $dbh->errstr;
+ my $pid;
+ if ($arg->{'fork'}) {
+ $pid = fork();
+ die "fork() failed: $!" unless defined $pid;
+ # child will return to caller
+ if ($pid) {
+ return $self;
+ }
+ }
- $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;
+
+ $sth->{'filenames'} = $dbh->prepare($arg->{'filenames'}) || die $dbh->errstr();
$sth->{'read'} = $dbh->prepare($arg->{'read'}) || die $dbh->errstr();
$sth->{'update'} = $dbh->prepare($arg->{'update'}) || die $dbh->errstr();
- $ctime_start = time();
- read_filenames;
-
- $self->{'proc'} = Proc::Simple->new();
- $self->{'proc'}->kill_on_destroy(1);
-
- $self->{'proc'}->start( sub {
- Fuse::main(
- mountpoint=>$arg->{'mount'},
- getattr=>\&e_getattr,
- getdir=>\&e_getdir,
- open=>\&e_open,
- statfs=>\&e_statfs,
- read=>\&e_read,
- write=>\&e_write,
- utime=>\&e_utime,
- truncate=>\&e_truncate,
- debug=>0,
- );
- } );
-
- confess "Fuse::main failed" if (! $self->{'proc'}->poll);
-
- $self ? return $self : return undef;
+ $self->{'sth'} = $sth;
+
+ $self->{'read_filenames'} = sub { $self->read_filenames };
+ $self->read_filenames;
+
+ $self->{'mounted'} = 1;
+
+ $fuse_self = \$self;
+
+ Fuse::main(
+ mountpoint=>$arg->{'mount'},
+ getattr=>\&e_getattr,
+ getdir=>\&e_getdir,
+ open=>\&e_open,
+ statfs=>\&e_statfs,
+ read=>\&e_read,
+ write=>\&e_write,
+ utime=>\&e_utime,
+ truncate=>\&e_truncate,
+ unlink=>\&e_unlink,
+ rmdir=>\&e_unlink,
+ debug=>0,
+ );
+
+ $self->{'mounted'} = 0;
+
+ exit(0) if ($arg->{'fork'});
+
+ return 1;
+
};
=head2 umount
sub umount {
my $self = shift;
- confess "no process running?" unless ($self->{'proc'});
+ if ($self->{'mounted'}) {
+ system "fusermount -u ".$self->{'mount'} || croak "umount error: $!";
+ }
- system "fusermount -u ".$self->{'mount'} || croak "umount error: $!";
+ return 1;
+}
- if ($self->{'proc'}->poll) {
- $self->{'proc'}->kill;
- return 1 if (! $self->{'proc'}->poll);
- } else {
+$SIG{'INT'} = sub {
+ print STDERR "umount called by SIG INT\n";
+ umount;
+};
+
+sub DESTROY {
+ my $self = shift;
+ return if (! $self->{'mounted'});
+ print STDERR "umount called by DESTROY\n";
+ $self->umount;
+}
+
+=head2 fuse_module_loaded
+
+Checks if C<fuse> module is loaded in kernel.
+
+ die "no fuse module loaded in kernel"
+ unless (Fuse::DBI::fuse_module_loaded);
+
+This function in called by C<mount>, but might be useful alone also.
+
+=cut
+
+sub fuse_module_loaded {
+ my $lsmod = `lsmod`;
+ die "can't start lsmod: $!" unless ($lsmod);
+ if ($lsmod =~ m/fuse/s) {
return 1;
+ } else {
+ return 0;
}
}
-
my %files;
my %dirs;
sub read_filenames {
my $self = shift;
+ my $sth = $self->{'sth'} || die "no sth argument";
+
# create empty filesystem
(%files) = (
'.' => {
return (keys %out),0;
}
+sub read_content {
+ my ($file,$id) = @_;
+
+ die "read_content needs file and id" unless ($file && $id);
+
+ $sth->{'read'}->execute($id) || die $sth->{'read'}->errstr;
+ $files{$file}{cont} = $sth->{'read'}->fetchrow_array;
+ # I should modify ctime only if content in database changed
+ #$files{$file}{ctime} = time() unless ($files{$file}{ctime});
+ print "file '$file' content [",length($files{$file}{cont})," bytes] read in cache\n";
+}
+
+
sub e_open {
# VFS sanity check; it keeps all the necessary state, not much to do here.
my $file = filename_fixup(shift);
return -ENOENT() unless exists($files{$file});
return -EISDIR() unless exists($files{$file}{id});
- if (!exists($files{$file}{cont})) {
- $sth->{'read'}->execute($files{$file}{id}) || die $sth->{'read'}->errstr;
- $files{$file}{cont} = $sth->{'read'}->fetchrow_array;
- print "file '$file' content read in cache\n";
- }
+ read_content($file,$files{$file}{id}) unless exists($files{$file}{cont});
+
print "open '$file' ",length($files{$file}{cont})," bytes\n";
return 0;
}
return -EINVAL() if ($off > $len);
return 0 if ($off == $len);
- $buf_len = $buf_len-$off if ($off+$buf_len > $len);
+ $buf_len = $len-$off if ($len - $off < $buf_len);
return substr($files{$file}{cont},$off,$buf_len);
}
print "invalidate all cached content\n";
foreach my $f (keys %files) {
delete $files{$f}{cont};
+ delete $files{$f}{ctime};
}
print "begin new transaction\n";
- $dbh->begin_work || die $dbh->errstr;
+ #$dbh->begin_work || die $dbh->errstr;
}
$files{$file}{ctime} = time();
- if (!$sth->{'update'}->execute($files{$file}{cont},$files{$file}{id})) {
+ my ($cont,$id) = (
+ $files{$file}{cont},
+ $files{$file}{id}
+ );
+
+ if (!$sth->{'update'}->execute($cont,$id)) {
print "update problem: ",$sth->{'update'}->errstr;
clear_cont;
return 0;
return 0;
}
print "updated '$file' [",$files{$file}{id},"]\n";
+
+ $$fuse_self->{'invalidate'}->() if (ref $$fuse_self->{'invalidate'});
}
return 1;
}
$files{$file}{cont} .= substr($cont,0,$off) if ($off > 0);
$files{$file}{cont} .= $buffer;
- $files{$file}{cont} .= substr($cont,-($off+length($buffer))) if ($off+length($buffer) > $len);
+ $files{$file}{cont} .= substr($cont,$off+length($buffer),$len-$off-length($buffer)) if ($off+length($buffer) < $len);
$files{$file}{size} = length($files{$file}{cont});
sub e_statfs { return 255, 1, 1, 1, 1, 2 }
+sub e_unlink {
+ my $file = filename_fixup(shift);
+
+ if (exists( $dirs{$file} )) {
+ print "unlink '$file' will re-read template names\n";
+ print Dumper($fuse_self);
+ $$fuse_self->{'read_filenames'}->();
+ return 0;
+ } elsif (exists( $files{$file} )) {
+ print "unlink '$file' will invalidate cache\n";
+ read_content($file,$files{$file}{id});
+ return 0;
+ }
+
+ return -ENOENT();
+}
1;
__END__
C<FUSE (Filesystem in USErspace)> website
L<http://sourceforge.net/projects/avf>
+Example for WebGUI which comes with this distribution in
+directory C<examples/webgui.pl>. It also contains a lot of documentation
+about design of this module, usage and limitations.
+
=head1 AUTHOR
Dobrica Pavlinusic, E<lt>dpavlin@rot13.orgE<gt>
projects / Fuse-DBI / blobdiff