--- trunk/DBI.pm 2004/10/08 22:55:36 26 +++ trunk/DBI.pm 2004/11/23 23:54:58 47 @@ -13,7 +13,7 @@ use Data::Dumper; -our $VERSION = '0.03'; +our $VERSION = '0.07'; =head1 NAME @@ -24,15 +24,15 @@ use Fuse::DBI; Fuse::DBI->mount( ... ); -See C below for examples how to set parametars. +See C below for examples how to set parameters. =head1 DESCRIPTION This module will use C module, part of C -available at L to mount +available at L 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. @@ -46,15 +46,69 @@ Mount your database as filesystem. +Let's suppose that your database have table C with following structure: + + id: int + filename: text + size: int + content: text + writable: boolean + +Following is example how to mount table like that to C: + my $mnt = Fuse::DBI->mount({ - filenames => 'select name from files_table as filenames', - 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 (unique id for that row), C, +C and C boolean flag. + +=item read + +SQL query which returns only one column with content of file and has +placeholder C for C. + +=item update + +SQL query with two pace-holders, one for new content and one for C. + +=item dsn + +C 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. + +=item fork + +Optional flag which forks after mount so that executing script will continue +running. Implementation is experimental. + +=back + =cut my $dbh; @@ -98,7 +152,16 @@ die "fork() failed: $!" unless defined $pid; # child will return to caller if ($pid) { - return $self; + my $counter = 4; + while ($counter && ! $self->is_mounted) { + select(undef, undef, undef, 0.5); + $counter--; + } + if ($self->is_mounted) { + return $self; + } else { + return undef; + } } } @@ -115,8 +178,6 @@ $self->{'read_filenames'} = sub { $self->read_filenames }; $self->read_filenames; - $self->{'mounted'} = 1; - $fuse_self = \$self; Fuse::main( @@ -134,14 +195,38 @@ debug=>0, ); - $self->{'mounted'} = 0; - exit(0) if ($arg->{'fork'}); return 1; }; +=head2 is_mounted + +Check if fuse filesystem is mounted + + if ($mnt->is_mounted) { ... } + +=cut + +sub is_mounted { + my $self = shift; + + my $mounted = 0; + my $mount = $self->{'mount'} || confess "can't find mount point!"; + if (open(MTAB, "/etc/mtab")) { + while() { + $mounted = 1 if (/ $mount fuse /i); + } + close(MTAB); + } else { + warn "can't open /etc/mtab: $!"; + } + + return $mounted; +} + + =head2 umount Unmount your database as filesystem. @@ -156,23 +241,31 @@ sub umount { my $self = shift; - if ($self->{'mounted'}) { - system "fusermount -u ".$self->{'mount'} || croak "umount error: $!"; + if ($self->{'mount'} && $self->is_mounted) { + system "fusermount -u ".$self->{'mount'}." 2>&1 >/dev/null" || return 0; + return 1; } - return 1; + return 0; } $SIG{'INT'} = sub { - print STDERR "umount called by SIG INT\n"; - umount; + if ($fuse_self && $$fuse_self->umount) { + print STDERR "umount called by SIG INT\n"; + } +}; + +$SIG{'QUIT'} = sub { + if ($fuse_self && $$fuse_self->umount) { + print STDERR "umount called by SIG QUIT\n"; + } }; sub DESTROY { my $self = shift; - return if (! $self->{'mounted'}); - print STDERR "umount called by DESTROY\n"; - $self->umount; + if ($self->umount) { + print STDERR "umount called by DESTROY\n"; + } } =head2 fuse_module_loaded @@ -182,7 +275,7 @@ die "no fuse module loaded in kernel" unless (Fuse::DBI::fuse_module_loaded); -This function in called by L, but might be useful alone also. +This function in called by C, but might be useful alone also. =cut @@ -210,6 +303,10 @@ type => 0040, mode => 0755, }, + '..' => { + type => 0040, + mode => 0755, + }, # a => { # cont => "File 'a'.\n", # type => 0100, @@ -288,7 +385,7 @@ my %out; foreach my $f (sort keys %files) { if ($dirname) { - if ($f =~ s/^\E$dirname\Q\///) { + if ($f =~ s/^\Q$dirname\E\///) { $out{$f}++ if ($f =~ /^[^\/]+$/); } } else { @@ -310,7 +407,8 @@ $sth->{'read'}->execute($id) || die $sth->{'read'}->errstr; $files{$file}{cont} = $sth->{'read'}->fetchrow_array; - $files{$file}{ctime} = time(); + # 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"; } @@ -356,6 +454,7 @@ 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; @@ -464,10 +563,20 @@ Nothing. +=head1 BUGS + +Size information (C) is wrong. It's a problem in upstream Fuse module +(for which I'm to blame lately), so when it gets fixes, C will +automagically pick it up. + =head1 SEE ALSO C website -L +L + +Example for WebGUI which comes with this distribution in +directory C. It also contains a lot of documentation +about design of this module, usage and limitations. =head1 AUTHOR