/[fuse_dbi]/fuse-couchdb/DBI.pm
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Annotation of /fuse-couchdb/DBI.pm

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Revision 11 - (hide annotations)
Sun Aug 29 18:51:29 2004 UTC (19 years, 7 months ago) by dpavlin
Original Path: trunk/DBI.pm
File size: 8248 byte(s)
first try at making this module (late commit)

1 dpavlin 1 #!/usr/bin/perl
2    
3 dpavlin 9 package Fuse::DBI;
4    
5     use 5.008;
6     use strict;
7     use warnings;
8    
9 dpavlin 7 use POSIX qw(ENOENT EISDIR EINVAL ENOSYS O_RDWR);
10 dpavlin 1 use Fuse;
11     use DBI;
12 dpavlin 11 use Carp;
13     use Proc::Simple;
14     use Data::Dumper;
15 dpavlin 1
16 dpavlin 11
17 dpavlin 9 our $VERSION = '0.01';
18 dpavlin 1
19 dpavlin 9 =head1 NAME
20 dpavlin 1
21 dpavlin 9 Fuse::DBI - mount your database as filesystem and use it
22 dpavlin 1
23 dpavlin 9 =head1 SYNOPSIS
24 dpavlin 6
25 dpavlin 9 use Fuse::DBI;
26 dpavlin 11 Fuse::DBI->mount( ... );
27 dpavlin 1
28 dpavlin 9 See L<run> below for examples how to set parametars.
29 dpavlin 1
30 dpavlin 9 =head1 DESCRIPTION
31 dpavlin 1
32 dpavlin 9 This module will use L<Fuse> module, part of C<FUSE (Filesystem in USErspace)>
33     available at L<http://sourceforge.net/projects/avf> to mount
34     your database as file system.
35 dpavlin 1
36 dpavlin 9 That will give you posibility to use normal file-system tools (cat, grep, vi)
37     to manipulate data in database.
38 dpavlin 1
39 dpavlin 9 It's actually opposite of Oracle's intention to put everything into database.
40 dpavlin 1
41    
42 dpavlin 9 =head1 METHODS
43    
44     =cut
45    
46 dpavlin 11 =head2 mount
47 dpavlin 9
48     Mount your database as filesystem.
49    
50 dpavlin 11 my $mnt = Fuse::DBI->mount({
51 dpavlin 9 filenames => 'select name from filenamefilenames,
52     read => 'sql read',
53     update => 'sql update',
54     dsn => 'DBI:Pg:dbname=webgui',
55     user => 'database_user',
56     password => 'database_password'
57     });
58    
59     =cut
60    
61     my $dbh;
62     my $sth;
63     my $ctime_start;
64    
65 dpavlin 11 sub read_filenames;
66 dpavlin 9
67 dpavlin 11 sub mount {
68     my $class = shift;
69     my $self = {};
70     bless($self, $class);
71 dpavlin 9
72 dpavlin 11 my $arg = shift;
73 dpavlin 9
74 dpavlin 11 print Dumper($arg);
75    
76     carp "mount needs 'dsn' to connect to (e.g. dsn => 'DBI:Pg:dbname=test')" unless ($arg->{'dsn'});
77     carp "mount needs 'mount' as mountpoint" unless ($arg->{'mount'});
78    
79 dpavlin 9 foreach (qw(filenames read update)) {
80 dpavlin 11 carp "mount needs '$_' SQL" unless ($arg->{$_});
81 dpavlin 9 }
82    
83     $dbh = DBI->connect($arg->{'dsn'},$arg->{'user'},$arg->{'password'}, { AutoCommit => 0 }) || die $DBI::errstr;
84    
85     print "start transaction\n";
86     #$dbh->begin_work || die $dbh->errstr;
87    
88     $sth->{filenames} = $dbh->prepare($arg->{'filenames'}) || die $dbh->errstr();
89    
90     $sth->{'read'} = $dbh->prepare($arg->{'read'}) || die $dbh->errstr();
91     $sth->{'update'} = $dbh->prepare($arg->{'update'}) || die $dbh->errstr();
92    
93     $ctime_start = time();
94    
95     read_filenames;
96    
97 dpavlin 11 $self->{'proc'} = Proc::Simple->new();
98     $self->{'proc'}->kill_on_destroy(1);
99    
100     $self->{'proc'}->start( sub {
101     Fuse::main(
102     mountpoint=>$arg->{'mount'},
103     getattr=>\&e_getattr,
104     getdir=>\&e_getdir,
105     open=>\&e_open,
106     statfs=>\&e_statfs,
107     read=>\&e_read,
108     write=>\&e_write,
109     utime=>\&e_utime,
110     truncate=>\&e_truncate,
111     debug=>0,
112     );
113     } );
114    
115     $self ? return $self : return undef;
116 dpavlin 9 };
117    
118 dpavlin 11 =head2 umount
119    
120     Unmount your database as filesystem.
121    
122     $mnt->umount;
123    
124     This will also kill background process which is translating
125     database to filesystem.
126    
127     =cut
128    
129     sub umount {
130     my $self = shift;
131    
132     confess "no process running?" unless ($self->{'proc'});
133     $self->{'proc'}->kill;
134     }
135    
136    
137 dpavlin 9 my %files;
138 dpavlin 1 my %dirs;
139    
140 dpavlin 9 sub read_filenames {
141 dpavlin 11 my $self = shift;
142    
143 dpavlin 9 # create empty filesystem
144     (%files) = (
145     '.' => {
146     type => 0040,
147     mode => 0755,
148     },
149     # a => {
150     # cont => "File 'a'.\n",
151     # type => 0100,
152     # ctime => time()-2000
153     # },
154     );
155 dpavlin 1
156 dpavlin 9 # fetch new filename list from database
157     $sth->{'filenames'}->execute() || die $sth->{'filenames'}->errstr();
158    
159     # read them in with sesible defaults
160     while (my $row = $sth->{'filenames'}->fetchrow_hashref() ) {
161     $files{$row->{'filename'}} = {
162     size => $row->{'size'},
163     mode => $row->{'writable'} ? 0644 : 0444,
164     id => $row->{'id'} || 99,
165     };
166    
167     my $d;
168     foreach (split(m!/!, $row->{'filename'})) {
169     # first, entry is assumed to be file
170     if ($d) {
171     $files{$d} = {
172     size => $dirs{$d}++,
173     mode => 0755,
174     type => 0040
175     };
176     $files{$d.'/.'} = {
177     mode => 0755,
178     type => 0040
179     };
180     $files{$d.'/..'} = {
181     mode => 0755,
182     type => 0040
183     };
184     }
185     $d .= "/" if ($d);
186     $d .= "$_";
187 dpavlin 1 }
188     }
189 dpavlin 9
190     print "found ",scalar(keys %files)-scalar(keys %dirs)," files, ",scalar(keys %dirs), " dirs\n";
191 dpavlin 1 }
192    
193    
194     sub filename_fixup {
195     my ($file) = shift;
196     $file =~ s,^/,,;
197     $file = '.' unless length($file);
198     return $file;
199     }
200    
201     sub e_getattr {
202     my ($file) = filename_fixup(shift);
203     $file =~ s,^/,,;
204     $file = '.' unless length($file);
205     return -ENOENT() unless exists($files{$file});
206     my ($size) = $files{$file}{size} || 1;
207     my ($dev, $ino, $rdev, $blocks, $gid, $uid, $nlink, $blksize) = (0,0,0,1,0,0,1,1024);
208     my ($atime, $ctime, $mtime);
209     $atime = $ctime = $mtime = $files{$file}{ctime} || $ctime_start;
210    
211     my ($modes) = (($files{$file}{type} || 0100)<<9) + $files{$file}{mode};
212    
213     # 2 possible types of return values:
214     #return -ENOENT(); # or any other error you care to
215     #print(join(",",($dev,$ino,$modes,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks)),"\n");
216     return ($dev,$ino,$modes,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks);
217     }
218    
219     sub e_getdir {
220     my ($dirname) = shift;
221     $dirname =~ s!^/!!;
222     # return as many text filenames as you like, followed by the retval.
223     print((scalar keys %files)." files total\n");
224     my %out;
225     foreach (keys %files) {
226     my $f = $_;
227     $f =~ s/^\E$dirname\Q//;
228     $f =~ s/^\///;
229     if ($dirname) {
230 dpavlin 2 $out{$f}++ if (/^\E$dirname\Q/ && $f =~ /^[^\/]+$/);
231 dpavlin 1 } else {
232     $out{$f}++ if ($f =~ /^[^\/]+$/);
233     }
234     }
235     if (! %out) {
236     $out{'no files? bug?'}++;
237     }
238 dpavlin 8 print scalar keys %out," files in dir '$dirname'\n";
239 dpavlin 1 return (keys %out),0;
240     }
241    
242     sub e_open {
243     # VFS sanity check; it keeps all the necessary state, not much to do here.
244 dpavlin 6 my $file = filename_fixup(shift);
245     my $flags = shift;
246    
247 dpavlin 1 return -ENOENT() unless exists($files{$file});
248     return -EISDIR() unless exists($files{$file}{id});
249 dpavlin 6
250 dpavlin 1 if (!exists($files{$file}{cont})) {
251 dpavlin 9 $sth->{'read'}->execute($files{$file}{id}) || die $sth->{'read'}->errstr;
252     $files{$file}{cont} = $sth->{'read'}->fetchrow_array;
253 dpavlin 7 print "file '$file' content read in cache\n";
254 dpavlin 1 }
255 dpavlin 3 print "open '$file' ",length($files{$file}{cont})," bytes\n";
256 dpavlin 1 return 0;
257     }
258    
259     sub e_read {
260 dpavlin 3 # return an error numeric, or binary/text string.
261     # (note: 0 means EOF, "0" will give a byte (ascii "0")
262     # to the reading program)
263 dpavlin 1 my ($file) = filename_fixup(shift);
264 dpavlin 8 my ($buf_len,$off) = @_;
265 dpavlin 3
266 dpavlin 1 return -ENOENT() unless exists($files{$file});
267 dpavlin 3
268     my $len = length($files{$file}{cont});
269    
270 dpavlin 8 print "read '$file' [$len bytes] offset $off length $buf_len\n";
271 dpavlin 3
272     return -EINVAL() if ($off > $len);
273     return 0 if ($off == $len);
274    
275 dpavlin 8 $buf_len = $buf_len-$off if ($off+$buf_len > $len);
276 dpavlin 3
277 dpavlin 8 return substr($files{$file}{cont},$off,$buf_len);
278 dpavlin 1 }
279    
280 dpavlin 6 sub clear_cont {
281 dpavlin 7 print "transaction rollback\n";
282     $dbh->rollback || die $dbh->errstr;
283 dpavlin 6 print "invalidate all cached content\n";
284     foreach my $f (keys %files) {
285     delete $files{$f}{cont};
286     }
287 dpavlin 7 print "begin new transaction\n";
288     $dbh->begin_work || die $dbh->errstr;
289 dpavlin 6 }
290    
291    
292     sub update_db {
293     my $file = shift || die;
294    
295 dpavlin 8 $files{$file}{ctime} = time();
296    
297 dpavlin 9 if (!$sth->{'update'}->execute($files{$file}{cont},$files{$file}{id})) {
298     print "update problem: ",$sth->{'update'}->errstr;
299 dpavlin 6 clear_cont;
300     return 0;
301     } else {
302 dpavlin 7 if (! $dbh->commit) {
303 dpavlin 9 print "ERROR: commit problem: ",$sth->{'update'}->errstr;
304 dpavlin 6 clear_cont;
305     return 0;
306     }
307     print "updated '$file' [",$files{$file}{id},"]\n";
308     }
309     return 1;
310     }
311    
312     sub e_write {
313     my $file = filename_fixup(shift);
314 dpavlin 8 my ($buf_len,$off) = @_;
315 dpavlin 6
316     return -ENOENT() unless exists($files{$file});
317    
318     my $len = length($files{$file}{cont});
319    
320 dpavlin 8 print "write '$file' [$len bytes] offset $off length\n";
321 dpavlin 6
322     $files{$file}{cont} =
323     substr($files{$file}{cont},0,$off) .
324 dpavlin 8 $buf_len .
325     substr($files{$file}{cont},$off+length($buf_len));
326 dpavlin 6
327     if (! update_db($file)) {
328     return -ENOSYS();
329     } else {
330 dpavlin 8 return length($buf_len);
331 dpavlin 6 }
332     }
333    
334     sub e_truncate {
335     my $file = filename_fixup(shift);
336     my $size = shift;
337    
338     $files{$file}{cont} = substr($files{$file}{cont},0,$size);
339     return 0
340     };
341    
342    
343     sub e_utime {
344     my ($atime,$mtime,$file) = @_;
345     $file = filename_fixup($file);
346    
347     return -ENOENT() unless exists($files{$file});
348    
349 dpavlin 8 print "utime '$file' $atime $mtime\n";
350    
351 dpavlin 6 $files{$file}{time} = $mtime;
352     return 0;
353     }
354    
355 dpavlin 1 sub e_statfs { return 255, 1, 1, 1, 1, 2 }
356    
357 dpavlin 9 1;
358     __END__
359    
360     =head1 EXPORT
361    
362     Nothing.
363    
364     =head1 SEE ALSO
365    
366     C<FUSE (Filesystem in USErspace)> website
367     L<http://sourceforge.net/projects/avf>
368    
369     =head1 AUTHOR
370    
371     Dobrica Pavlinusic, E<lt>dpavlin@rot13.orgE<gt>
372    
373     =head1 COPYRIGHT AND LICENSE
374    
375     Copyright (C) 2004 by Dobrica Pavlinusic
376    
377     This library is free software; you can redistribute it and/or modify
378     it under the same terms as Perl itself, either Perl version 5.8.4 or,
379     at your option, any later version of Perl 5 you may have available.
380    
381    
382     =cut
383    

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