[BUG] Another bad garbage collection bug

Gavin Carr gavin at openfusion.com.au
Mon Nov 17 10:57:00 UTC 2008

I've found another bad bug with garbage collection: any target
that has the 'nocolons' setting turned on (and it's on by default 
for both the Ftp and Sftp targets) have their chunks incorrectly 
compared during garbage collection, with the result that ALL 
chunks get deleted when you do a gc.

The problem is that chunks in the brackup file are recorded with
colons, while the chunks on disk are escaped, and then the 
comparison during garbage collection is just done directly, when
one or other of the operands should be converted.

The simplest fix is probably to unescape to colons again e.g.

=== modified file 'lib/Brackup/Target.pm'
--- lib/Brackup/Target.pm       2008-11-17 06:05:36 +0000
+++ lib/Brackup/Target.pm       2008-11-17 10:30:05 +0000
@@ -136,7 +136,7 @@
     # get all chunks and then loop through metafiles to detect
     # referenced ones
-    my %chunks = map {$_ => 1} $self->chunks;
+    my %chunks = map {s/\./:/ if $self->nocolons; $_ => 1} $self->chunks;
     my $tempfile = +(tempfile())[1];
     my @backups = $self->backups;
     BACKUP: foreach my $i (0 .. $#backups) {

A stylistic wrinkle is that the whole 'nocolons' thing is target-
specific at the moment, so because garbage collection is 
implemented in the parent Brackup::Target class we probably need
to either implement a default nocolons() method there, or leave it
target-optional and make the test more complex e.g.

  my %chunks = map {s/\./:/ if $self->can('nocolons') && $self->nocolons; $_ => 1} $self->chunks;

Thoughts on that? I'm probably inclined towards the former at the 
moment, but not too strongly. If we do the latter, then we should
maybe redo the map as a for, as it's getting pretty long?

Although the real fix is probably to try and get rid of this 
whole colons thing altogether and convert to the dotted version
everywhere - if we can figure out how do it in a way that's 
backward compatible.


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