git-rerere: add 'gc' command.

Over time, unresolved rr-cache entries are accumulated and they
tend to get less and less likely to be useful as the tips of
branches advance.

Reorder documentation page to show the subcommand section earlier
than the discussion section.

Signed-off-by: Junio C Hamano <junkio@cox.net>

1 files changed, 25 insertions, 0 deletions

diff --git a/git-rerere.perl b/git-rerere.perl
index b2550bb2e..61eef575d 100755
--- a/git-rerere.perl
+++ b/git-rerere.perl
@@ -169,6 +169,28 @@ sub merge {
 	return 0;
 }
 
+sub garbage_collect_rerere {
+	# We should allow specifying these from the command line and
+	# that is why the caller gives @ARGV to us, but I am lazy.
+
+	my $cutoff_noresolve = 15; # two weeks
+	my $cutoff_resolve = 60; # two months
+	my @to_remove;
+	while (<$rr_dir/*/preimage>) {
+		my ($dir) = /^(.*)\/preimage$/;
+		my $cutoff = ((-f "$dir/postimage")
+			      ? $cutoff_resolve
+			      : $cutoff_noresolve);
+		my $age = -M "$_";
+		if ($cutoff <= $age) {
+			push @to_remove, $dir;
+		}
+	}
+	if (@to_remove) {
+		rmtree(\@to_remove);
+	}
+}
+
 -d "$rr_dir" || exit(0);
 
 read_rr();
@@ -198,6 +220,9 @@ if (@ARGV) {
 				"$rr_dir/$name/preimage", $path);
 		}
 	}
+	elsif ($arg eq 'gc') {
+		garbage_collect_rerere(@ARGV);
+	}
 	else {
 		die "$0 unknown command: $arg\n";
 	}