/[fuse_dbi]/fuse-couchdb/DBI.pm
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trunk/fuse_dbi.pl revision 2 by dpavlin, Wed Aug 4 09:03:05 2004 UTC trunk/DBI.pm revision 31 by dpavlin, Sun Oct 10 19:33:23 2004 UTC
# Line 1  Line 1 
1  #!/usr/bin/perl  #!/usr/bin/perl
2    
3  use POSIX qw(ENOENT EISDIR EINVAL);  package Fuse::DBI;
 use Fuse;  
4    
5  use DBI;  use 5.008;
6  use strict;  use strict;
7    use warnings;
8    
9  my $sql_filenames = q{  use POSIX qw(ENOENT EISDIR EINVAL ENOSYS O_RDWR);
10          select  use Fuse;
11                  templateid as id,  use DBI;
12                  namespace||'/'||name||' ['||templateid||']' as filename,  use Carp;
13                  length(template) as size,  use Data::Dumper;
14                  iseditable as writable  
15          from template ;  
16  };  our $VERSION = '0.04';
17    
18    =head1 NAME
19    
20    Fuse::DBI - mount your database as filesystem and use it
21    
22    =head1 SYNOPSIS
23    
24      use Fuse::DBI;
25      Fuse::DBI->mount( ... );
26    
27    See C<run> below for examples how to set parameters.
28    
29    =head1 DESCRIPTION
30    
31    This module will use C<Fuse> module, part of C<FUSE (Filesystem in USErspace)>
32    available at L<http://sourceforge.net/projects/avf> to mount
33    your database as file system.
34    
35    That will give you possibility to use normal file-system tools (cat, grep, vi)
36    to manipulate data in database.
37    
38    It's actually opposite of Oracle's intention to put everything into database.
39    
40    
41    =head1 METHODS
42    
43    =cut
44    
45    =head2 mount
46    
47    Mount your database as filesystem.
48    
49    Let's suppose that your database have table C<files> with following structure:
50    
51     id:            int
52     filename:      text
53     size:          int
54     content:       text
55     writable:      boolean
56    
57    Following is example how to mount table like that to C</mnt>:
58    
59      my $mnt = Fuse::DBI->mount({
60            'filenames' => 'select id,filename,size,writable from files',
61            'read' => 'select content from files where id = ?',
62            'update' => 'update files set content = ? where id = ?',
63            'dsn' => 'DBI:Pg:dbname=test_db',
64            'user' => 'database_user',
65            'password' => 'database_password',
66            'invalidate' => sub { ... },
67      });
68    
69    Options:
70    
71    =over 5
72    
73    =item filenames
74    
75    SQL query which returns C<id> (unique id for that row), C<filename>,
76    C<size> and C<writable> boolean flag.
77    
78    =item read
79    
80    SQL query which returns only one column with content of file and has
81    placeholder C<?> for C<id>.
82    
83    =item update
84    
85    SQL query with two pace-holders, one for new content and one for C<id>.
86    
87    =item dsn
88    
89    C<DBI> dsn to connect to (contains database driver and name of database).
90    
91    =item user
92    
93    User with which to connect to database
94    
95    =item password
96    
97    Password for connecting to database
98    
99    =item invalidate
100    
101    Optional anonymous code reference which will be executed when data is updated in
102    database. It can be used as hook to delete cache (for example on-disk-cache)
103    which is created from data edited through C<Fuse::DBI>.
104    
105    =item fork
106    
107    Optional flag which forks after mount so that executing script will continue
108    running. Implementation is experimental.
109    
110    =back
111    
112    =cut
113    
114    my $dbh;
115    my $sth;
116    my $ctime_start;
117    
118    sub read_filenames;
119    sub fuse_module_loaded;
120    
121    # evil, evil way to solve this. It makes this module non-reentrant. But, since
122    # fuse calls another copy of this script for each mount anyway, this shouldn't
123    # be a problem.
124    my $fuse_self;
125    
126    sub mount {
127            my $class = shift;
128            my $self = {};
129            bless($self, $class);
130    
131            my $arg = shift;
132    
133            print Dumper($arg);
134    
135            carp "mount needs 'dsn' to connect to (e.g. dsn => 'DBI:Pg:dbname=test')" unless ($arg->{'dsn'});
136            carp "mount needs 'mount' as mountpoint" unless ($arg->{'mount'});
137    
138            # save (some) arguments in self
139            foreach (qw(mount invalidate)) {
140                    $self->{$_} = $arg->{$_};
141            }
142    
143            foreach (qw(filenames read update)) {
144                    carp "mount needs '$_' SQL" unless ($arg->{$_});
145            }
146    
147            $ctime_start = time();
148    
149            my $pid;
150            if ($arg->{'fork'}) {
151                    $pid = fork();
152                    die "fork() failed: $!" unless defined $pid;
153                    # child will return to caller
154                    if ($pid) {
155                            return $self;
156                    }
157            }
158    
159            $dbh = DBI->connect($arg->{'dsn'},$arg->{'user'},$arg->{'password'}, {AutoCommit => 0, RaiseError => 1}) || die $DBI::errstr;
160    
161            $sth->{'filenames'} = $dbh->prepare($arg->{'filenames'}) || die $dbh->errstr();
162    
163            $sth->{'read'} = $dbh->prepare($arg->{'read'}) || die $dbh->errstr();
164            $sth->{'update'} = $dbh->prepare($arg->{'update'}) || die $dbh->errstr();
165    
166    
167            $self->{'sth'} = $sth;
168    
169            $self->{'read_filenames'} = sub { $self->read_filenames };
170            $self->read_filenames;
171    
172            $self->{'mounted'} = 1;
173    
174            $fuse_self = \$self;
175    
176            Fuse::main(
177                    mountpoint=>$arg->{'mount'},
178                    getattr=>\&e_getattr,
179                    getdir=>\&e_getdir,
180                    open=>\&e_open,
181                    statfs=>\&e_statfs,
182                    read=>\&e_read,
183                    write=>\&e_write,
184                    utime=>\&e_utime,
185                    truncate=>\&e_truncate,
186                    unlink=>\&e_unlink,
187                    rmdir=>\&e_unlink,
188                    debug=>0,
189            );
190            
191            $self->{'mounted'} = 0;
192    
193            exit(0) if ($arg->{'fork'});
194    
195            return 1;
196    
 my $sql_content = q{  
         select template  
         from template  
         where templateid = ?;  
197  };  };
198    
199    =head2 umount
200    
201    Unmount your database as filesystem.
202    
203      $mnt->umount;
204    
205    This will also kill background process which is translating
206    database to filesystem.
207    
208    =cut
209    
210    sub umount {
211            my $self = shift;
212    
213  my $connect = "DBI:Pg:dbname=webgui";          if ($self->{'mounted'}) {
214                    system "fusermount -u ".$self->{'mount'} || croak "umount error: $!";
215            }
216    
217            return 1;
218    }
219    
220    $SIG{'INT'} = sub {
221            print STDERR "umount called by SIG INT\n";
222            umount;
223    };
224    
225  my $dbh = DBI->connect($connect,"","") || die $DBI::errstr;  sub DESTROY {
226            my $self = shift;
227            return if (! $self->{'mounted'});
228            print STDERR "umount called by DESTROY\n";
229            $self->umount;
230    }
231    
232  print STDERR "$sql_filenames\n";  =head2 fuse_module_loaded
233    
234  my $sth_filenames = $dbh->prepare($sql_filenames) || die $dbh->errstr();  Checks if C<fuse> module is loaded in kernel.
 $sth_filenames->execute() || die $sth_filenames->errstr();  
235    
236  my $sth_content = $dbh->prepare($sql_content) || die $dbh->errstr();    die "no fuse module loaded in kernel"
237            unless (Fuse::DBI::fuse_module_loaded);
238    
239  print "#",join(",",@{ $sth_filenames->{NAME} }),"\n";  This function in called by C<mount>, but might be useful alone also.
240    
241  my $ctime_start = time();  =cut
242    
243  my (%files) = (  sub fuse_module_loaded {
244          '.' => {          my $lsmod = `lsmod`;
245                  type => 0040,          die "can't start lsmod: $!" unless ($lsmod);
246                  mode => 0755,          if ($lsmod =~ m/fuse/s) {
247          },                  return 1;
248  #       a => {          } else {
249  #               cont => "File 'a'.\n",                  return 0;
250  #               type => 0100,          }
251  #               ctime => time()-2000  }
 #       },  
 );  
252    
253    my %files;
254  my %dirs;  my %dirs;
255    
256  while (my $row = $sth_filenames->fetchrow_hashref() ) {  sub read_filenames {
257          $files{$row->{'filename'}} = {          my $self = shift;
258                  size => $row->{'size'},  
259                  mode => $row->{'writable'} ? 0644 : 0444,          my $sth = $self->{'sth'} || die "no sth argument";
260                  id => $row->{'id'} || 99,  
261          };          # create empty filesystem
262            (%files) = (
263          my $d;                  '.' => {
264          foreach (split(m!/!, $row->{'filename'})) {                          type => 0040,
265                  # first, entry is assumed to be file                          mode => 0755,
266                  if ($d) {                  },
267                          $files{$d} = {          #       a => {
268                                          size => $dirs{$d}++,          #               cont => "File 'a'.\n",
269                                          mode => 0755,          #               type => 0100,
270                                          type => 0040          #               ctime => time()-2000
271                          };          #       },
272                          $files{$d.'/.'} = {          );
273                                          mode => 0755,  
274                                          type => 0040          # fetch new filename list from database
275                          };          $sth->{'filenames'}->execute() || die $sth->{'filenames'}->errstr();
276                          $files{$d.'/..'} = {  
277                                          mode => 0755,          # read them in with sesible defaults
278                                          type => 0040          while (my $row = $sth->{'filenames'}->fetchrow_hashref() ) {
279                          };                  $files{$row->{'filename'}} = {
280                            size => $row->{'size'},
281                            mode => $row->{'writable'} ? 0644 : 0444,
282                            id => $row->{'id'} || 99,
283                    };
284    
285                    my $d;
286                    foreach (split(m!/!, $row->{'filename'})) {
287                            # first, entry is assumed to be file
288                            if ($d) {
289                                    $files{$d} = {
290                                                    size => $dirs{$d}++,
291                                                    mode => 0755,
292                                                    type => 0040
293                                    };
294                                    $files{$d.'/.'} = {
295                                                    mode => 0755,
296                                                    type => 0040
297                                    };
298                                    $files{$d.'/..'} = {
299                                                    mode => 0755,
300                                                    type => 0040
301                                    };
302                            }
303                            $d .= "/" if ($d);
304                            $d .= "$_";
305                  }                  }
                 $d .= "/" if ($d);  
                 $d .= "$_";  
306          }          }
307    
308            print "found ",scalar(keys %files)-scalar(keys %dirs)," files, ",scalar(keys %dirs), " dirs\n";
309  }  }
310    
 print scalar (keys %dirs), " dirs:",join(" ",keys %dirs),"\n";  
311    
312  sub filename_fixup {  sub filename_fixup {
313          my ($file) = shift;          my ($file) = shift;
# Line 114  sub e_getdir { Line 340  sub e_getdir {
340          # return as many text filenames as you like, followed by the retval.          # return as many text filenames as you like, followed by the retval.
341          print((scalar keys %files)." files total\n");          print((scalar keys %files)." files total\n");
342          my %out;          my %out;
343          foreach (keys %files) {          foreach my $f (sort keys %files) {
                 my $f = $_;  
                 $f =~ s/^\E$dirname\Q//;  
                 $f =~ s/^\///;  
344                  if ($dirname) {                  if ($dirname) {
345                          $out{$f}++ if (/^\E$dirname\Q/ && $f =~ /^[^\/]+$/);                          if ($f =~ s/^\E$dirname\Q\///) {
346                                    $out{$f}++ if ($f =~ /^[^\/]+$/);
347                            }
348                  } else {                  } else {
349                          $out{$f}++ if ($f =~ /^[^\/]+$/);                          $out{$f}++ if ($f =~ /^[^\/]+$/);
350                  }                  }
                 print "f: $_ -> $f\n";  
351          }          }
352          if (! %out) {          if (! %out) {
353                  $out{'no files? bug?'}++;                  $out{'no files? bug?'}++;
354          }          }
355          print scalar keys %out," files found for '$dirname': ",keys %out,"\n";          print scalar keys %out," files in dir '$dirname'\n";
356            print "## ",join(" ",keys %out),"\n";
357          return (keys %out),0;          return (keys %out),0;
358  }  }
359    
360    sub read_content {
361            my ($file,$id) = @_;
362    
363            die "read_content needs file and id" unless ($file && $id);
364    
365            $sth->{'read'}->execute($id) || die $sth->{'read'}->errstr;
366            $files{$file}{cont} = $sth->{'read'}->fetchrow_array;
367            # I should modify ctime only if content in database changed
368            #$files{$file}{ctime} = time() unless ($files{$file}{ctime});
369            print "file '$file' content [",length($files{$file}{cont})," bytes] read in cache\n";
370    }
371    
372    
373  sub e_open {  sub e_open {
374          # 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.
375          my ($file) = filename_fixup(shift);          my $file = filename_fixup(shift);
376          print("open called\n");          my $flags = shift;
377    
378          return -ENOENT() unless exists($files{$file});          return -ENOENT() unless exists($files{$file});
379          return -EISDIR() unless exists($files{$file}{id});          return -EISDIR() unless exists($files{$file}{id});
380          if (!exists($files{$file}{cont})) {  
381                  $sth_content->execute($files{$file}{id});          read_content($file,$files{$file}{id}) unless exists($files{$file}{cont});
382                  ($files{$file}{cont}) = $sth_content->fetchrow_array;  
383          }          print "open '$file' ",length($files{$file}{cont})," bytes\n";
         print("open ok\n");  
384          return 0;          return 0;
385  }  }
386    
387  sub e_read {  sub e_read {
388          # return an error numeric, or binary/text string.  (note: 0 means EOF, "0" will          # return an error numeric, or binary/text string.
389          # give a byte (ascii "0") to the reading program)          # (note: 0 means EOF, "0" will give a byte (ascii "0")
390            # to the reading program)
391          my ($file) = filename_fixup(shift);          my ($file) = filename_fixup(shift);
392          my ($buf,$off) = @_;          my ($buf_len,$off) = @_;
393    
394            return -ENOENT() unless exists($files{$file});
395    
396            my $len = length($files{$file}{cont});
397    
398            print "read '$file' [$len bytes] offset $off length $buf_len\n";
399    
400            return -EINVAL() if ($off > $len);
401            return 0 if ($off == $len);
402    
403            $buf_len = $len-$off if ($len - $off < $buf_len);
404    
405            return substr($files{$file}{cont},$off,$buf_len);
406    }
407    
408    sub clear_cont {
409            print "transaction rollback\n";
410            $dbh->rollback || die $dbh->errstr;
411            print "invalidate all cached content\n";
412            foreach my $f (keys %files) {
413                    delete $files{$f}{cont};
414                    delete $files{$f}{ctime};
415            }
416            print "begin new transaction\n";
417            #$dbh->begin_work || die $dbh->errstr;
418    }
419    
420    
421    sub update_db {
422            my $file = shift || die;
423    
424            $files{$file}{ctime} = time();
425    
426            my ($cont,$id) = (
427                    $files{$file}{cont},
428                    $files{$file}{id}
429            );
430    
431            if (!$sth->{'update'}->execute($cont,$id)) {
432                    print "update problem: ",$sth->{'update'}->errstr;
433                    clear_cont;
434                    return 0;
435            } else {
436                    if (! $dbh->commit) {
437                            print "ERROR: commit problem: ",$sth->{'update'}->errstr;
438                            clear_cont;
439                            return 0;
440                    }
441                    print "updated '$file' [",$files{$file}{id},"]\n";
442    
443                    $$fuse_self->{'invalidate'}->() if (ref $$fuse_self->{'invalidate'});
444            }
445            return 1;
446    }
447    
448    sub e_write {
449            my $file = filename_fixup(shift);
450            my ($buffer,$off) = @_;
451    
452          return -ENOENT() unless exists($files{$file});          return -ENOENT() unless exists($files{$file});
453          return -EINVAL() if $off > length($files{$file}{cont});  
454          return 0 if $off == length($files{$file}{cont});          my $cont = $files{$file}{cont};
455          return substr($files{$file}{cont},$off,$buf);          my $len = length($cont);
456    
457            print "write '$file' [$len bytes] offset $off length ",length($buffer),"\n";
458    
459            $files{$file}{cont} = "";
460    
461            $files{$file}{cont} .= substr($cont,0,$off) if ($off > 0);
462            $files{$file}{cont} .= $buffer;
463            $files{$file}{cont} .= substr($cont,$off+length($buffer),$len-$off-length($buffer)) if ($off+length($buffer) < $len);
464    
465            $files{$file}{size} = length($files{$file}{cont});
466    
467            if (! update_db($file)) {
468                    return -ENOSYS();
469            } else {
470                    return length($buffer);
471            }
472    }
473    
474    sub e_truncate {
475            my $file = filename_fixup(shift);
476            my $size = shift;
477    
478            print "truncate to $size\n";
479    
480            $files{$file}{cont} = substr($files{$file}{cont},0,$size);
481            $files{$file}{size} = $size;
482            return 0
483    };
484    
485    
486    sub e_utime {
487            my ($atime,$mtime,$file) = @_;
488            $file = filename_fixup($file);
489    
490            return -ENOENT() unless exists($files{$file});
491    
492            print "utime '$file' $atime $mtime\n";
493    
494            $files{$file}{time} = $mtime;
495            return 0;
496  }  }
497    
498  sub e_statfs { return 255, 1, 1, 1, 1, 2 }  sub e_statfs { return 255, 1, 1, 1, 1, 2 }
499    
500  # If you run the script directly, it will run fusermount, which will in turn  sub e_unlink {
501  # re-run this script.  Hence the funky semantics.          my $file = filename_fixup(shift);
502  my ($mountpoint) = "";  
503  $mountpoint = shift(@ARGV) if @ARGV;          if (exists( $dirs{$file} )) {
504  Fuse::main(                  print "unlink '$file' will re-read template names\n";
505          mountpoint=>$mountpoint,                  print Dumper($fuse_self);
506          getattr=>\&e_getattr,                  $$fuse_self->{'read_filenames'}->();
507          getdir=>\&e_getdir,                  return 0;
508          open=>\&e_open,          } elsif (exists( $files{$file} )) {
509          statfs=>\&e_statfs,                  print "unlink '$file' will invalidate cache\n";
510          read=>\&e_read,                  read_content($file,$files{$file}{id});
511          debug=>1,                  return 0;
512  );          }
513    
514            return -ENOENT();
515    }
516    1;
517    __END__
518    
519    =head1 EXPORT
520    
521    Nothing.
522    
523    =head1 SEE ALSO
524    
525    C<FUSE (Filesystem in USErspace)> website
526    L<http://sourceforge.net/projects/avf>
527    
528    Example for WebGUI which comes with this distribution in
529    directory C<examples/webgui.pl>. It also contains a lot of documentation
530    about design of this module, usage and limitations.
531    
532    =head1 AUTHOR
533    
534    Dobrica Pavlinusic, E<lt>dpavlin@rot13.orgE<gt>
535    
536    =head1 COPYRIGHT AND LICENSE
537    
538    Copyright (C) 2004 by Dobrica Pavlinusic
539    
540    This library is free software; you can redistribute it and/or modify
541    it under the same terms as Perl itself, either Perl version 5.8.4 or,
542    at your option, any later version of Perl 5 you may have available.
543    
544    
545    =cut
546    
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