--- trunk/DBI.pm 2004/10/02 16:30:16 22 +++ trunk/DBI.pm 2004/11/27 15:08:10 52 @@ -12,8 +12,10 @@ use Carp; use Data::Dumper; +our $VERSION = '0.07'; -our $VERSION = '0.03'; +# block size for this filesystem +use constant BLOCK => 1024; =head1 NAME @@ -24,15 +26,15 @@ use Fuse::DBI; Fuse::DBI->mount( ... ); -See L below for examples how to set parametars. +See C below for examples how to set parameters. =head1 DESCRIPTION -This module will use L module, part of C -available at L to mount +This module will use C module, part of C +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 +48,69 @@ 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; @@ -64,6 +120,11 @@ 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; my $self = {}; @@ -73,11 +134,18 @@ print Dumper($arg); + unless ($self->fuse_module_loaded) { + print STDERR "no fuse module loaded. Trying sudo modprobe fuse!\n"; + system "sudo modprobe fuse" || die "can't modprobe fuse using sudo!\n"; + } + carp "mount needs 'dsn' to connect to (e.g. dsn => 'DBI:Pg:dbname=test')" unless ($arg->{'dsn'}); 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->{$_}); @@ -91,19 +159,34 @@ 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; + } } } $dbh = DBI->connect($arg->{'dsn'},$arg->{'user'},$arg->{'password'}, {AutoCommit => 0, RaiseError => 1}) || die $DBI::errstr; - $sth->{filenames} = $dbh->prepare($arg->{'filenames'}) || die $dbh->errstr(); + $sth->{'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(); + + $self->{'sth'} = $sth; + + $self->{'read_filenames'} = sub { $self->read_filenames }; $self->read_filenames; + $fuse_self = \$self; + Fuse::main( mountpoint=>$arg->{'mount'}, getattr=>\&e_getattr, @@ -115,15 +198,42 @@ utime=>\&e_utime, truncate=>\&e_truncate, unlink=>\&e_unlink, + rmdir=>\&e_unlink, debug=>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. @@ -138,9 +248,33 @@ sub umount { my $self = shift; - system "fusermount -u ".$self->{'mount'} || croak "umount error: $!"; + if ($self->{'mount'} && $self->is_mounted) { + system "( fusermount -u ".$self->{'mount'}." 2>&1 ) >/dev/null" || + system "sudo umount ".$self->{'mount'} || + return 0; + return 1; + } - return 1; + return 0; +} + +$SIG{'INT'} = sub { + 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 $self = shift; + if ($self->umount) { + print STDERR "umount called by DESTROY\n"; + } } =head2 fuse_module_loaded @@ -150,7 +284,7 @@ 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 @@ -165,17 +299,22 @@ } my %files; -my %dirs; sub read_filenames { my $self = shift; + my $sth = $self->{'sth'} || die "no sth argument"; + # create empty filesystem (%files) = ( '.' => { type => 0040, mode => 0755, }, + '..' => { + type => 0040, + mode => 0755, + }, # a => { # cont => "File 'a'.\n", # type => 0100, @@ -199,7 +338,6 @@ # first, entry is assumed to be file if ($d) { $files{$d} = { - size => $dirs{$d}++, mode => 0755, type => 0040 }; @@ -217,7 +355,7 @@ } } - print "found ",scalar(keys %files)-scalar(keys %dirs)," files, ",scalar(keys %dirs), " dirs\n"; + print "found ",scalar(keys %files)," files\n"; } @@ -233,8 +371,8 @@ $file =~ s,^/,,; $file = '.' unless length($file); return -ENOENT() unless exists($files{$file}); - my ($size) = $files{$file}{size} || 1; - my ($dev, $ino, $rdev, $blocks, $gid, $uid, $nlink, $blksize) = (0,0,0,1,0,0,1,1024); + my ($size) = $files{$file}{size} || BLOCK; + my ($dev, $ino, $rdev, $blocks, $gid, $uid, $nlink, $blksize) = (0,0,0,int(($size+BLOCK-1)/BLOCK),0,0,1,BLOCK); my ($atime, $ctime, $mtime); $atime = $ctime = $mtime = $files{$file}{ctime} || $ctime_start; @@ -242,7 +380,7 @@ # 2 possible types of return values: #return -ENOENT(); # or any other error you care to - #print(join(",",($dev,$ino,$modes,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks)),"\n"); + print "getattr($file) ",join(",",($dev,$ino,$modes,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks)),"\n"; return ($dev,$ino,$modes,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks); } @@ -254,7 +392,7 @@ 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 { @@ -276,6 +414,8 @@ $sth->{'read'}->execute($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"; } @@ -321,6 +461,7 @@ 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 $dbh->errstr; @@ -348,6 +489,8 @@ return 0; } print "updated '$file' [",$files{$file}{id},"]\n"; + + $$fuse_self->{'invalidate'}->() if (ref $$fuse_self->{'invalidate'}); } return 1; } @@ -402,18 +545,43 @@ return 0; } -sub e_statfs { return 255, 1, 1, 1, 1, 2 } +sub e_statfs { -sub e_unlink { - my $file = filename_fixup(shift); + my $size = 0; + my $inodes = 0; - return -ENOENT() unless exists($files{$file}); + foreach my $f (keys %files) { + if ($f !~ /(^|\/)\.\.?$/) { + $size += $files{$f}{size} || 0; + $inodes++; + } + print "$inodes: $f [$size]\n"; + } - print "unlink '$file' will invalidate cache\n"; + $size = int(($size+BLOCK-1)/BLOCK); - read_content($file,$files{$file}{id}); + my @ret = (255, $inodes, 1, $size, $size-1, BLOCK); - return 0; + print "statfs: ",join(",",@ret),"\n"; + + return @ret; +} + +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; + if (exists( $files{$file} )) { + print "unlink '$file' will invalidate cache\n"; + read_content($file,$files{$file}{id}); + return 0; + } + + return -ENOENT(); } 1; __END__ @@ -422,10 +590,20 @@ 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