X-Git-Url: http://git.rot13.org/?p=Fuse-DBI;a=blobdiff_plain;f=DBI.pm;h=3537bf070cad63466a64fc3743b2a7c8e4002089;hp=df80edc44847363f2d2c66b7f6098512784db77e;hb=8b53b090ace163fc02e100998eda16f4a0c0435b;hpb=9652c581b0fe3216545e52cb5a728392fffd3d66

diff --git a/DBI.pm b/DBI.pm
index df80edc..3537bf0 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 = '0.01';
+our $VERSION = '0.05';
 
 =head1 NAME
 
@@ -25,15 +24,15 @@ Fuse::DBI - mount your database as filesystem and use it
   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.
@@ -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<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;
@@ -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 $class = shift;
@@ -77,47 +136,65 @@ sub mount {
 	carp "mount needs 'mount' as mountpoint" unless ($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'}) {
+		$self->{'mounted'} = 1;
+		$pid = fork();
+		die "fork() failed: $!" unless defined $pid;
+		# child will return to caller
+		if ($pid) {
+			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();
 
-	$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;
+
+	$self->{'mounted'} = 1 unless ($arg->{'fork'});
+
+	$fuse_self = \$self;
+
+	Fuse::main(
+		mountpoint=>$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 +211,54 @@ database to filesystem.
 sub umount {
 	my $self = shift;
 
-	confess "no process running?" unless ($self->{'proc'});
+	if ($self->{'mounted'}) {
+		system "fusermount -u ".$self->{'mount'} || warn "umount error: $!" && return 0;
+	}
+
+	return 1;
+}
+
+$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
 
-	system "fusermount -u ".$self->{'mount'} || croak "umount error: $!";
+Checks if C<fuse> module is loaded in kernel.
 
-	if ($self->{'proc'}->poll) {
-		$self->{'proc'}->kill;
-		return 1 if (! $self->{'proc'}->poll);
-	} else {
+  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) = (
 		'.' => {
@@ -237,7 +343,7 @@ 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 +358,19 @@ 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 $file = filename_fixup(shift);
@@ -260,11 +379,8 @@ sub e_open {
 	return -ENOENT() unless exists($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 +401,7 @@ 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 +412,10 @@ 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 +424,12 @@ 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;
@@ -318,29 +440,35 @@ sub update_db {
 			return 0;
 		}
 		print "updated '$file' [",$files{$file}{id},"]\n";
+
+		$$fuse_self->{'invalidate'}->() if (ref $$fuse_self->{'invalidate'});
 	}
 	return 1;
 }
 
 sub e_write {
 	my $file = filename_fixup(shift);
-	my ($buf_len,$off) = @_;
+	my ($buffer,$off) = @_;
 
 	return -ENOENT() unless exists($files{$file});
 
-	my $len = length($files{$file}{cont});
+	my $cont = $files{$file}{cont};
+	my $len = length($cont);
+
+	print "write '$file' [$len bytes] offset $off length ",length($buffer),"\n";
 
-	print "write '$file' [$len bytes] offset $off length\n";
+	$files{$file}{cont} = "";
 
-	$files{$file}{cont} =
-		substr($files{$file}{cont},0,$off) .
-		$buf_len .
-		substr($files{$file}{cont},$off+length($buf_len));
+	$files{$file}{cont} .= substr($cont,0,$off) if ($off > 0);
+	$files{$file}{cont} .= $buffer;
+	$files{$file}{cont} .= substr($cont,$off+length($buffer),$len-$off-length($buffer)) if ($off+length($buffer) < $len);
+
+	$files{$file}{size} = length($files{$file}{cont});
 
 	if (! update_db($file)) {
 		return -ENOSYS();
 	} else {
-		return length($buf_len);
+		return length($buffer);
 	}
 }
 
@@ -348,7 +476,10 @@ sub e_truncate {
 	my $file = filename_fixup(shift);
 	my $size = shift;
 
+	print "truncate to $size\n";
+
 	$files{$file}{cont} = substr($files{$file}{cont},0,$size);
+	$files{$file}{size} = $size;
 	return 0
 };
 
@@ -367,6 +498,22 @@ 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__
 
@@ -379,6 +526,10 @@ Nothing.
 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>