X-Git-Url: http://git.rot13.org/?p=Fuse-DBI;a=blobdiff_plain;f=DBI.pm;h=c94a5e3e84d40f1fd346d3894fb3d8086df72fab;hp=8caecd3918101286f349fc57ac68ade3d710d39a;hb=258e57966734da73223b72d0048e613ad0b38703;hpb=423879e95093f0dc5a34dbd712555377a3b6aa38 diff --git a/DBI.pm b/DBI.pm index 8caecd3..c94a5e3 100755 --- a/DBI.pm +++ b/DBI.pm @@ -13,7 +13,7 @@ use Carp; use Data::Dumper; -our $VERSION = '0.03'; +our $VERSION = '0.04'; =head1 NAME @@ -24,15 +24,15 @@ Fuse::DBI - mount your database as filesystem and use it 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 +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 +46,69 @@ 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 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 +118,11 @@ 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; my $self = {}; @@ -77,7 +136,9 @@ sub mount { carp "mount needs 'mount' as mountpoint" unless ($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->{$_}); @@ -85,25 +146,34 @@ sub mount { $ctime_start = time(); + my $pid; if ($arg->{'fork'}) { - my $pid = fork(); + $pid = fork(); die "fork() failed: $!" unless defined $pid; # child will return to caller if ($pid) { - $self ? return $self : return undef; + return $self; } } $dbh = DBI->connect($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; - my $mount = Fuse::main( + $self->{'mounted'} = 1; + + $fuse_self = \$self; + + Fuse::main( mountpoint=>$arg->{'mount'}, getattr=>\&e_getattr, getdir=>\&e_getdir, @@ -114,13 +184,16 @@ sub mount { utime=>\&e_utime, truncate=>\&e_truncate, unlink=>\&e_unlink, + rmdir=>\&e_unlink, debug=>0, ); + + $self->{'mounted'} = 0; + + exit(0) if ($arg->{'fork'}); + + return 1; - if (! $mount) { - warn "mount on ",$arg->{'mount'}," failed!\n"; - return undef; - } }; =head2 umount @@ -137,11 +210,25 @@ database to filesystem. sub umount { my $self = shift; - system "fusermount -u ".$self->{'mount'} || croak "umount error: $!"; + if ($self->{'mounted'}) { + system "fusermount -u ".$self->{'mount'} || croak "umount error: $!"; + } return 1; } +$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 module is loaded in kernel. @@ -149,7 +236,7 @@ Checks if C module is loaded in kernel. 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 @@ -169,6 +256,8 @@ my %dirs; sub read_filenames { my $self = shift; + my $sth = $self->{'sth'} || die "no sth argument"; + # create empty filesystem (%files) = ( '.' => { @@ -275,6 +364,8 @@ sub read_content { $sth->{'read'}->execute($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"; } @@ -320,6 +411,7 @@ sub clear_cont { 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 $dbh->errstr; @@ -347,6 +439,8 @@ sub update_db { return 0; } print "updated '$file' [",$files{$file}{id},"]\n"; + + $$fuse_self->{'invalidate'}->() if (ref $$fuse_self->{'invalidate'}); } return 1; } @@ -406,13 +500,18 @@ sub e_statfs { return 255, 1, 1, 1, 1, 2 } sub e_unlink { my $file = filename_fixup(shift); - return -ENOENT() unless exists($files{$file}); - - print "unlink '$file' will invalidate cache\n"; - - read_content($file,$files{$file}{id}); + 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 0; + return -ENOENT(); } 1; __END__ @@ -426,6 +525,10 @@ Nothing. C website 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 Dobrica Pavlinusic, Edpavlin@rot13.orgE