+# Tie::File seems to be prone to offset errors if revisions get sparse,
+# it's not that fast, either. Tie::File is also not in Perl 5.6. So
+# one of my favorite modules is out :< Next up would be one of the DBM
+# modules, but I'm not sure which is most portable... So I'll just
+# go with something that's plain-text, but still capable of
+# being randomly accessed. So here's my ultra-simple fixed-width
+# database. All records are 40 characters + "\n", so it's easy to seek
+# to a revision: (41 * rev) is the byte offset.
+# A record of 40 0s denotes an empty revision.
+# And yes, it's still pretty fast (faster than Tie::File).
+sub revdb_set {
+ my ($file, $rev, $commit) = @_;
+ length $commit == 40 or croak "arg3 must be a full SHA1 hexsum\n";
+ open my $fh, '+<', $file or croak $!;
+ my $offset = $rev * 41;
+ # assume that append is the common case:
+ seek $fh, 0, 2 or croak $!;
+ my $pos = tell $fh;
+ if ($pos < $offset) {
+ print $fh (('0' x 40),"\n") x (($offset - $pos) / 41);
+ }
+ seek $fh, $offset, 0 or croak $!;
+ print $fh $commit,"\n";
+ close $fh or croak $!;
+}
+
+sub revdb_get {
+ my ($file, $rev) = @_;
+ my $ret;
+ my $offset = $rev * 41;
+ open my $fh, '<', $file or croak $!;
+ seek $fh, $offset, 0;
+ if (tell $fh == $offset) {
+ $ret = readline $fh;
+ if (defined $ret) {
+ chomp $ret;
+ $ret = undef if ($ret =~ /^0{40}$/);
+ }
+ }
+ close $fh or croak $!;
+ return $ret;
+}
+