X-Git-Url: http://git.rot13.org/?p=Fuse-DBI;a=blobdiff_plain;f=DBI.pm;h=ddc083fb0b9d6791e8a22d64c908d3a2ec12cd50;hp=96b3ea36f3cb697f2473efa6075629d891553130;hb=3e6d7539cc1290bed4cfb99e89c64dc0472ab4b3;hpb=414d242c9ec3d06490ed022c99e3d01e80bf82db diff --git a/DBI.pm b/DBI.pm index 96b3ea3..ddc083f 100755 --- a/DBI.pm +++ b/DBI.pm @@ -10,11 +10,10 @@ use POSIX qw(ENOENT EISDIR EINVAL ENOSYS O_RDWR); use Fuse; use DBI; use Carp; -use Proc::Simple; use Data::Dumper; -our $VERSION = '0.02'; +our $VERSION = '0.04'; =head1 NAME @@ -25,15 +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. @@ -47,15 +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 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 (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; @@ -63,6 +116,12 @@ my $sth; 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 $class = shift; @@ -77,47 +136,64 @@ sub mount { carp "mount needs 'mount' as mountpoint" unless ($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->{$_}); } - $dbh = DBI->connect($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 @@ -134,25 +210,54 @@ database to filesystem. 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 module is loaded in kernel. + + die "no fuse module loaded in kernel" + unless (Fuse::DBI::fuse_module_loaded); + +This function in called by C, 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) = ( '.' => { @@ -237,7 +342,7 @@ sub e_getdir { 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 { @@ -252,6 +357,19 @@ sub e_getdir { 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 $file = filename_fixup(shift); @@ -260,11 +378,8 @@ sub e_open { return -ENOENT() unless exists($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; } @@ -285,7 +400,7 @@ sub e_read { 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); } @@ -296,9 +411,10 @@ 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 $dbh->errstr; + #$dbh->begin_work || die $dbh->errstr; } @@ -307,7 +423,12 @@ sub update_db { $files{$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; @@ -318,6 +439,8 @@ sub update_db { return 0; } print "updated '$file' [",$files{$file}{id},"]\n"; + + $$fuse_self->{'invalidate'}->() if (ref $$fuse_self->{'invalidate'}); } return 1; } @@ -337,7 +460,7 @@ sub e_write { $files{$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}); @@ -374,6 +497,22 @@ sub e_utime { 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__ @@ -386,6 +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