/[fuse_dbi]/fuse-couchdb/DBI.pm
This is repository of my old source code which isn't updated any more. Go to git.rot13.org for current projects!
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revision 9 by dpavlin, Sat Aug 7 19:06:03 2004 UTC revision 54 by dpavlin, Tue Apr 26 19:57:51 2005 UTC
# Line 9  use warnings; Line 9  use warnings;
9  use POSIX qw(ENOENT EISDIR EINVAL ENOSYS O_RDWR);  use POSIX qw(ENOENT EISDIR EINVAL ENOSYS O_RDWR);
10  use Fuse;  use Fuse;
11  use DBI;  use DBI;
12    use Carp;
13    use Data::Dumper;
14    
15  our $VERSION = '0.01';  our $VERSION = '0.07';
16    
17    # block size for this filesystem
18    use constant BLOCK => 1024;
19    
20  =head1 NAME  =head1 NAME
21    
# Line 19  Fuse::DBI - mount your database as files Line 24  Fuse::DBI - mount your database as files
24  =head1 SYNOPSIS  =head1 SYNOPSIS
25    
26    use Fuse::DBI;    use Fuse::DBI;
27    Fuse::DBI->run( ... );    Fuse::DBI->mount( ... );
28    
29  See L<run> below for examples how to set parametars.  See C<run> below for examples how to set parameters.
30    
31  =head1 DESCRIPTION  =head1 DESCRIPTION
32    
33  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)>
34  available at L<http://sourceforge.net/projects/avf> to mount  available at L<http://fuse.sourceforge.net/> to mount
35  your database as file system.  your database as file system.
36    
37  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)
38  to manipulate data in database.  to manipulate data in database.
39    
40  It's actually opposite of Oracle's intention to put everything into database.  It's actually opposite of Oracle's intention to put everything into database.
# Line 39  It's actually opposite of Oracle's inten Line 44  It's actually opposite of Oracle's inten
44    
45  =cut  =cut
46    
47  =head2 run  =head2 mount
48    
49  Mount your database as filesystem.  Mount your database as filesystem.
50    
51    Fuse::DBI->run({  Let's suppose that your database have table C<files> with following structure:
52          filenames => 'select name from filenamefilenames,  
53          read => 'sql read',   id:            int
54          update => 'sql update',   filename:      text
55          dsn => 'DBI:Pg:dbname=webgui',   size:          int
56          user => 'database_user',   content:       text
57          password => 'database_password'   writable:      boolean
58    
59    Following is example how to mount table like that to C</mnt>:
60    
61      my $mnt = Fuse::DBI->mount({
62            'filenames' => 'select id,filename,size,writable from files',
63            'read' => 'select content from files where id = ?',
64            'update' => 'update files set content = ? where id = ?',
65            'dsn' => 'DBI:Pg:dbname=test_db',
66            'user' => 'database_user',
67            'password' => 'database_password',
68            'invalidate' => sub { ... },
69    });    });
70    
71    Options:
72    
73    =over 5
74    
75    =item filenames
76    
77    SQL query which returns C<id> (unique id for that row), C<filename>,
78    C<size> and C<writable> boolean flag.
79    
80    =item read
81    
82    SQL query which returns only one column with content of file and has
83    placeholder C<?> for C<id>.
84    
85    =item update
86    
87    SQL query with two pace-holders, one for new content and one for C<id>.
88    
89    =item dsn
90    
91    C<DBI> dsn to connect to (contains database driver and name of database).
92    
93    =item user
94    
95    User with which to connect to database
96    
97    =item password
98    
99    Password for connecting to database
100    
101    =item invalidate
102    
103    Optional anonymous code reference which will be executed when data is updated in
104    database. It can be used as hook to delete cache (for example on-disk-cache)
105    which is created from data edited through C<Fuse::DBI>.
106    
107    =item fork
108    
109    Optional flag which forks after mount so that executing script will continue
110    running. Implementation is experimental.
111    
112    =back
113    
114  =cut  =cut
115    
116  my $dbh;  my $dbh;
117  my $sth;  my $sth;
118  my $ctime_start;  my $ctime_start;
119    
120  sub run {  sub read_filenames;
121          my $self = shift  sub fuse_module_loaded;
122    
123    # evil, evil way to solve this. It makes this module non-reentrant. But, since
124    # fuse calls another copy of this script for each mount anyway, this shouldn't
125    # be a problem.
126    my $fuse_self;
127    
128    sub mount {
129            my $class = shift;
130            my $self = {};
131            bless($self, $class);
132    
133            my $arg = shift;
134    
135            print Dumper($arg);
136    
137            unless ($self->fuse_module_loaded) {
138                    print STDERR "no fuse module loaded. Trying sudo modprobe fuse!\n";
139                    system "sudo modprobe fuse" || die "can't modprobe fuse using sudo!\n";
140            }
141    
142          my $arg = {@_};          carp "mount needs 'dsn' to connect to (e.g. dsn => 'DBI:Pg:dbname=test')" unless ($arg->{'dsn'});
143            carp "mount needs 'mount' as mountpoint" unless ($arg->{'mount'});
144    
145          carp "run needs 'dsn' to connect to (e.g. dsn => 'DBI:Pg:dbname=test')" unless ($arg->{'dsn'});          # save (some) arguments in self
146          carp "run needs 'mount' as mountpoint" unless ($arg->{'mount'});          foreach (qw(mount invalidate)) {
147                    $self->{$_} = $arg->{$_};
148            }
149    
150          foreach (qw(filenames read update)) {          foreach (qw(filenames read update)) {
151                  carp "run needs '$_' SQL" unless ($arg->{$_});                  carp "mount needs '$_' SQL" unless ($arg->{$_});
152          }          }
153    
154          $dbh = DBI->connect($arg->{'dsn'},$arg->{'user'},$arg->{'password'}, { AutoCommit => 0 }) || die $DBI::errstr;          $ctime_start = time();
155    
156          print "start transaction\n";          my $pid;
157          #$dbh->begin_work || die $dbh->errstr;          if ($arg->{'fork'}) {
158                    $pid = fork();
159                    die "fork() failed: $!" unless defined $pid;
160                    # child will return to caller
161                    if ($pid) {
162                            my $counter = 4;
163                            while ($counter && ! $self->is_mounted) {
164                                    select(undef, undef, undef, 0.5);
165                                    $counter--;
166                            }
167                            if ($self->is_mounted) {
168                                    return $self;
169                            } else {
170                                    return undef;
171                            }
172                    }
173            }
174    
175          $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;
176    
177            $sth->{'filenames'} = $dbh->prepare($arg->{'filenames'}) || die $dbh->errstr();
178    
179          $sth->{'read'} = $dbh->prepare($arg->{'read'}) || die $dbh->errstr();          $sth->{'read'} = $dbh->prepare($arg->{'read'}) || die $dbh->errstr();
180          $sth->{'update'} = $dbh->prepare($arg->{'update'}) || die $dbh->errstr();          $sth->{'update'} = $dbh->prepare($arg->{'update'}) || die $dbh->errstr();
181    
         $ctime_start = time();  
182    
183          read_filenames;          $self->{'sth'} = $sth;
184    
185            $self->{'read_filenames'} = sub { $self->read_filenames };
186            $self->read_filenames;
187    
188            $fuse_self = \$self;
189    
190          Fuse::main(          Fuse::main(
191                  mountpoint=>$arg->{'mount'},                  mountpoint=>$arg->{'mount'},
# Line 94  sub run { Line 197  sub run {
197                  write=>\&e_write,                  write=>\&e_write,
198                  utime=>\&e_utime,                  utime=>\&e_utime,
199                  truncate=>\&e_truncate,                  truncate=>\&e_truncate,
200                    unlink=>\&e_unlink,
201                    rmdir=>\&e_unlink,
202                  debug=>0,                  debug=>0,
203          );          );
204            
205            exit(0) if ($arg->{'fork'});
206    
207            return 1;
208    
209  };  };
210    
211    =head2 is_mounted
212    
213    Check if fuse filesystem is mounted
214    
215      if ($mnt->is_mounted) { ... }
216    
217    =cut
218    
219    sub is_mounted {
220            my $self = shift;
221    
222            my $mounted = 0;
223            my $mount = $self->{'mount'} || confess "can't find mount point!";
224            if (open(MTAB, "/etc/mtab")) {
225                    while(<MTAB>) {
226                            $mounted = 1 if (/ $mount fuse /i);
227                    }
228                    close(MTAB);
229            } else {
230                    warn "can't open /etc/mtab: $!";
231            }
232    
233            return $mounted;
234    }
235    
236    
237    =head2 umount
238    
239    Unmount your database as filesystem.
240    
241      $mnt->umount;
242    
243    This will also kill background process which is translating
244    database to filesystem.
245    
246    =cut
247    
248    sub umount {
249            my $self = shift;
250    
251            if ($self->{'mount'} && $self->is_mounted) {
252                    system "( fusermount -u ".$self->{'mount'}." 2>&1 ) >/dev/null";
253                    if ($self->is_mounted) {
254                            system "sudo umount ".$self->{'mount'} ||
255                            return 0;
256                    }
257                    return 1;
258            }
259    
260            return 0;
261    }
262    
263    $SIG{'INT'} = sub {
264            if ($fuse_self && $$fuse_self->umount) {
265                    print STDERR "umount called by SIG INT\n";
266            }
267    };
268    
269    $SIG{'QUIT'} = sub {
270            if ($fuse_self && $$fuse_self->umount) {
271                    print STDERR "umount called by SIG QUIT\n";
272            }
273    };
274    
275    sub DESTROY {
276            my $self = shift;
277            if ($self->umount) {
278                    print STDERR "umount called by DESTROY\n";
279            }
280    }
281    
282    =head2 fuse_module_loaded
283    
284    Checks if C<fuse> module is loaded in kernel.
285    
286      die "no fuse module loaded in kernel"
287            unless (Fuse::DBI::fuse_module_loaded);
288    
289    This function in called by C<mount>, but might be useful alone also.
290    
291    =cut
292    
293    sub fuse_module_loaded {
294            my $lsmod = `lsmod`;
295            die "can't start lsmod: $!" unless ($lsmod);
296            if ($lsmod =~ m/fuse/s) {
297                    return 1;
298            } else {
299                    return 0;
300            }
301    }
302    
303  my %files;  my %files;
 my %dirs;  
304    
305  sub read_filenames {  sub read_filenames {
306            my $self = shift;
307    
308            my $sth = $self->{'sth'} || die "no sth argument";
309    
310          # create empty filesystem          # create empty filesystem
311          (%files) = (          (%files) = (
312                  '.' => {                  '.' => {
313                          type => 0040,                          type => 0040,
314                          mode => 0755,                          mode => 0755,
315                  },                  },
316                    '..' => {
317                            type => 0040,
318                            mode => 0755,
319                    },
320          #       a => {          #       a => {
321          #               cont => "File 'a'.\n",          #               cont => "File 'a'.\n",
322          #               type => 0100,          #               type => 0100,
# Line 131  sub read_filenames { Line 340  sub read_filenames {
340                          # first, entry is assumed to be file                          # first, entry is assumed to be file
341                          if ($d) {                          if ($d) {
342                                  $files{$d} = {                                  $files{$d} = {
                                                 size => $dirs{$d}++,  
343                                                  mode => 0755,                                                  mode => 0755,
344                                                  type => 0040                                                  type => 0040
345                                  };                                  };
# Line 149  sub read_filenames { Line 357  sub read_filenames {
357                  }                  }
358          }          }
359    
360          print "found ",scalar(keys %files)-scalar(keys %dirs)," files, ",scalar(keys %dirs), " dirs\n";          print "found ",scalar(keys %files)," files\n";
361  }  }
362    
363    
# Line 165  sub e_getattr { Line 373  sub e_getattr {
373          $file =~ s,^/,,;          $file =~ s,^/,,;
374          $file = '.' unless length($file);          $file = '.' unless length($file);
375          return -ENOENT() unless exists($files{$file});          return -ENOENT() unless exists($files{$file});
376          my ($size) = $files{$file}{size} || 1;          my ($size) = $files{$file}{size} || 0;
377          my ($dev, $ino, $rdev, $blocks, $gid, $uid, $nlink, $blksize) = (0,0,0,1,0,0,1,1024);          my ($dev, $ino, $rdev, $blocks, $gid, $uid, $nlink, $blksize) = (0,0,0,int(($size+BLOCK-1)/BLOCK),0,0,1,BLOCK);
378          my ($atime, $ctime, $mtime);          my ($atime, $ctime, $mtime);
379          $atime = $ctime = $mtime = $files{$file}{ctime} || $ctime_start;          $atime = $ctime = $mtime = $files{$file}{ctime} || $ctime_start;
380    
# Line 174  sub e_getattr { Line 382  sub e_getattr {
382    
383          # 2 possible types of return values:          # 2 possible types of return values:
384          #return -ENOENT(); # or any other error you care to          #return -ENOENT(); # or any other error you care to
385          #print(join(",",($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";
386          return ($dev,$ino,$modes,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks);          return ($dev,$ino,$modes,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks);
387  }  }
388    
# Line 184  sub e_getdir { Line 392  sub e_getdir {
392          # return as many text filenames as you like, followed by the retval.          # return as many text filenames as you like, followed by the retval.
393          print((scalar keys %files)." files total\n");          print((scalar keys %files)." files total\n");
394          my %out;          my %out;
395          foreach (keys %files) {          foreach my $f (sort keys %files) {
                 my $f = $_;  
                 $f =~ s/^\E$dirname\Q//;  
                 $f =~ s/^\///;  
396                  if ($dirname) {                  if ($dirname) {
397                          $out{$f}++ if (/^\E$dirname\Q/ && $f =~ /^[^\/]+$/);                          if ($f =~ s/^\Q$dirname\E\///) {
398                                    $out{$f}++ if ($f =~ /^[^\/]+$/);
399                            }
400                  } else {                  } else {
401                          $out{$f}++ if ($f =~ /^[^\/]+$/);                          $out{$f}++ if ($f =~ /^[^\/]+$/);
402                  }                  }
# Line 198  sub e_getdir { Line 405  sub e_getdir {
405                  $out{'no files? bug?'}++;                  $out{'no files? bug?'}++;
406          }          }
407          print scalar keys %out," files in dir '$dirname'\n";          print scalar keys %out," files in dir '$dirname'\n";
408            print "## ",join(" ",keys %out),"\n";
409          return (keys %out),0;          return (keys %out),0;
410  }  }
411    
412    sub read_content {
413            my ($file,$id) = @_;
414    
415            die "read_content needs file and id" unless ($file && $id);
416    
417            $sth->{'read'}->execute($id) || die $sth->{'read'}->errstr;
418            $files{$file}{cont} = $sth->{'read'}->fetchrow_array;
419            # I should modify ctime only if content in database changed
420            #$files{$file}{ctime} = time() unless ($files{$file}{ctime});
421            print "file '$file' content [",length($files{$file}{cont})," bytes] read in cache\n";
422    }
423    
424    
425  sub e_open {  sub e_open {
426          # VFS sanity check; it keeps all the necessary state, not much to do here.          # VFS sanity check; it keeps all the necessary state, not much to do here.
427          my $file = filename_fixup(shift);          my $file = filename_fixup(shift);
# Line 209  sub e_open { Line 430  sub e_open {
430          return -ENOENT() unless exists($files{$file});          return -ENOENT() unless exists($files{$file});
431          return -EISDIR() unless exists($files{$file}{id});          return -EISDIR() unless exists($files{$file}{id});
432    
433          if (!exists($files{$file}{cont})) {          read_content($file,$files{$file}{id}) unless exists($files{$file}{cont});
434                  $sth->{'read'}->execute($files{$file}{id}) || die $sth->{'read'}->errstr;  
435                  $files{$file}{cont} = $sth->{'read'}->fetchrow_array;          $files{$file}{cont} ||= '';
                 print "file '$file' content read in cache\n";  
         }  
436          print "open '$file' ",length($files{$file}{cont})," bytes\n";          print "open '$file' ",length($files{$file}{cont})," bytes\n";
437          return 0;          return 0;
438  }  }
# Line 234  sub e_read { Line 453  sub e_read {
453          return -EINVAL() if ($off > $len);          return -EINVAL() if ($off > $len);
454          return 0 if ($off == $len);          return 0 if ($off == $len);
455    
456          $buf_len = $buf_len-$off if ($off+$buf_len > $len);          $buf_len = $len-$off if ($len - $off < $buf_len);
457    
458          return substr($files{$file}{cont},$off,$buf_len);          return substr($files{$file}{cont},$off,$buf_len);
459  }  }
# Line 245  sub clear_cont { Line 464  sub clear_cont {
464          print "invalidate all cached content\n";          print "invalidate all cached content\n";
465          foreach my $f (keys %files) {          foreach my $f (keys %files) {
466                  delete $files{$f}{cont};                  delete $files{$f}{cont};
467                    delete $files{$f}{ctime};
468          }          }
469          print "begin new transaction\n";          print "begin new transaction\n";
470          $dbh->begin_work || die $dbh->errstr;          #$dbh->begin_work || die $dbh->errstr;
471  }  }
472    
473    
# Line 256  sub update_db { Line 476  sub update_db {
476    
477          $files{$file}{ctime} = time();          $files{$file}{ctime} = time();
478    
479          if (!$sth->{'update'}->execute($files{$file}{cont},$files{$file}{id})) {          my ($cont,$id) = (
480                    $files{$file}{cont},
481                    $files{$file}{id}
482            );
483    
484            if (!$sth->{'update'}->execute($cont,$id)) {
485                  print "update problem: ",$sth->{'update'}->errstr;                  print "update problem: ",$sth->{'update'}->errstr;
486                  clear_cont;                  clear_cont;
487                  return 0;                  return 0;
# Line 267  sub update_db { Line 492  sub update_db {
492                          return 0;                          return 0;
493                  }                  }
494                  print "updated '$file' [",$files{$file}{id},"]\n";                  print "updated '$file' [",$files{$file}{id},"]\n";
495    
496                    $$fuse_self->{'invalidate'}->() if (ref $$fuse_self->{'invalidate'});
497          }          }
498          return 1;          return 1;
499  }  }
500    
501  sub e_write {  sub e_write {
502          my $file = filename_fixup(shift);          my $file = filename_fixup(shift);
503          my ($buf_len,$off) = @_;          my ($buffer,$off) = @_;
504    
505          return -ENOENT() unless exists($files{$file});          return -ENOENT() unless exists($files{$file});
506    
507          my $len = length($files{$file}{cont});          my $cont = $files{$file}{cont};
508            my $len = length($cont);
509    
510            print "write '$file' [$len bytes] offset $off length ",length($buffer),"\n";
511    
512          print "write '$file' [$len bytes] offset $off length\n";          $files{$file}{cont} = "";
513    
514          $files{$file}{cont} =          $files{$file}{cont} .= substr($cont,0,$off) if ($off > 0);
515                  substr($files{$file}{cont},0,$off) .          $files{$file}{cont} .= $buffer;
516                  $buf_len .          $files{$file}{cont} .= substr($cont,$off+length($buffer),$len-$off-length($buffer)) if ($off+length($buffer) < $len);
517                  substr($files{$file}{cont},$off+length($buf_len));  
518            $files{$file}{size} = length($files{$file}{cont});
519    
520          if (! update_db($file)) {          if (! update_db($file)) {
521                  return -ENOSYS();                  return -ENOSYS();
522          } else {          } else {
523                  return length($buf_len);                  return length($buffer);
524          }          }
525  }  }
526    
# Line 297  sub e_truncate { Line 528  sub e_truncate {
528          my $file = filename_fixup(shift);          my $file = filename_fixup(shift);
529          my $size = shift;          my $size = shift;
530    
531            print "truncate to $size\n";
532    
533          $files{$file}{cont} = substr($files{$file}{cont},0,$size);          $files{$file}{cont} = substr($files{$file}{cont},0,$size);
534            $files{$file}{size} = $size;
535          return 0          return 0
536  };  };
537    
# Line 314  sub e_utime { Line 548  sub e_utime {
548          return 0;          return 0;
549  }  }
550    
551  sub e_statfs { return 255, 1, 1, 1, 1, 2 }  sub e_statfs {
552    
553            my $size = 0;
554            my $inodes = 0;
555    
556            foreach my $f (keys %files) {
557                    if ($f !~ /(^|\/)\.\.?$/) {
558                            $size += $files{$f}{size} || 0;
559                            $inodes++;
560                    }
561                    print "$inodes: $f [$size]\n";
562            }
563    
564            $size = int(($size+BLOCK-1)/BLOCK);
565    
566            my @ret = (255, $inodes, 1, $size, $size-1, BLOCK);
567    
568            #print "statfs: ",join(",",@ret),"\n";
569    
570            return @ret;
571    }
572    
573    sub e_unlink {
574            my $file = filename_fixup(shift);
575    
576    #       if (exists( $dirs{$file} )) {
577    #               print "unlink '$file' will re-read template names\n";
578    #               print Dumper($fuse_self);
579    #               $$fuse_self->{'read_filenames'}->();
580    #               return 0;
581            if (exists( $files{$file} )) {
582                    print "unlink '$file' will invalidate cache\n";
583                    read_content($file,$files{$file}{id});
584                    return 0;
585            }
586    
587            return -ENOENT();
588    }
589  1;  1;
590  __END__  __END__
591    
# Line 323  __END__ Line 593  __END__
593    
594  Nothing.  Nothing.
595    
596    =head1 BUGS
597    
598    Size information (C<ls -s>) is wrong. It's a problem in upstream Fuse module
599    (for which I'm to blame lately), so when it gets fixes, C<Fuse::DBI> will
600    automagically pick it up.
601    
602  =head1 SEE ALSO  =head1 SEE ALSO
603    
604  C<FUSE (Filesystem in USErspace)> website  C<FUSE (Filesystem in USErspace)> website
605  L<http://sourceforge.net/projects/avf>  L<http://fuse.sourceforge.net/>
606    
607    Example for WebGUI which comes with this distribution in
608    directory C<examples/webgui.pl>. It also contains a lot of documentation
609    about design of this module, usage and limitations.
610    
611  =head1 AUTHOR  =head1 AUTHOR
612    
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