Merge branch 'ew/rerere'

* ew/rerere:
  rerere: record (or avoid misrecording) resolved, skipped or aborted rebase/am
  git-rerere: add 'gc' command.
  rerere: add clear, diff, and status commands

Documentation/git-rerere.txt

@@ -7,8 +7,7 @@ git-rerere - Reuse recorded resolve
 
 SYNOPSIS
 --------
-'git-rerere'
-
+'git-rerere' [clear|diff|status]
 
 DESCRIPTION
 -----------
@@ -27,6 +26,38 @@ results and applying the previously recorded hand resolution.
 You need to create `$GIT_DIR/rr-cache` directory to enable this
 command.
 
+
+COMMANDS
+--------
+
+Normally, git-rerere is run without arguments or user-intervention.
+However, it has several commands that allow it to interact with
+its working state.
+
+'clear'::
+
+This resets the metadata used by rerere if a merge resolution is to be
+is aborted.  Calling gitlink:git-am[1] --skip or gitlink:git-rebase[1]
+[--skip|--abort] will automatcally invoke this command.
+
+'diff'::
+
+This displays diffs for the current state of the resolution.  It is
+useful for tracking what has changed while the user is resolving
+conflicts.  Additional arguments are passed directly to the system
+diff(1) command installed in PATH.
+
+'status'::
+
+Like diff, but this only prints the filenames that will be tracked
+for resolutions.
+
+'gc'::
+
+This command is used to prune records of conflicted merge that
+occurred long time ago.
+
+
 DISCUSSION
 ----------
 

git-am.sh

@@ -246,6 +246,10 @@ last=`cat "$dotest/last"`
 this=`cat "$dotest/next"`
 if test "$skip" = t
 then
+	if test -d "$GIT_DIR/rr-cache"
+	then
+		git-rerere clear
+	fi
 	this=`expr "$this" + 1`
 	resume=
 fi
@@ -408,6 +412,10 @@ do
 			stop_here_user_resolve $this
 		fi
 		apply_status=0
+		if test -d "$GIT_DIR/rr-cache"
+		then
+			git rerere
+		fi
 		;;
 	esac
 

git-rebase.sh

@@ -139,6 +139,10 @@ do
 	--skip)
 		if test -d "$dotest"
 		then
+			if test -d "$GIT_DIR/rr-cache"
+			then
+				git-rerere clear
+			fi
 			prev_head="`cat $dotest/prev_head`"
 			end="`cat $dotest/end`"
 			msgnum="`cat $dotest/msgnum`"
@@ -157,6 +161,10 @@ do
 		exit
 		;;
 	--abort)
+		if test -d "$GIT_DIR/rr-cache"
+		then
+			git-rerere clear
+		fi
 		if test -d "$dotest"
 		then
 			rm -r "$dotest"

git-rerere.perl

@@ -169,9 +169,66 @@ 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();
+
+if (@ARGV) {
+	my $arg = shift @ARGV;
+	if ($arg eq 'clear') {
+		for my $path (keys %merge_rr) {
+			my $name = $merge_rr{$path};
+			if (-d "$rr_dir/$name" &&
+			    ! -f "$rr_dir/$name/postimage") {
+				rmtree(["$rr_dir/$name"]);
+			}
+		}
+		unlink $merge_rr;
+	}
+	elsif ($arg eq 'status') {
+		for my $path (keys %merge_rr) {
+			print $path, "\n";
+		}
+	}
+	elsif ($arg eq 'diff') {
+		for my $path (keys %merge_rr) {
+			my $name = $merge_rr{$path};
+			system('diff', ((@ARGV == 0) ? ('-u') : @ARGV),
+				'-L', "a/$path", '-L', "b/$path",
+				"$rr_dir/$name/preimage", $path);
+		}
+	}
+	elsif ($arg eq 'gc') {
+		garbage_collect_rerere(@ARGV);
+	}
+	else {
+		die "$0 unknown command: $arg\n";
+	}
+	exit 0;
+}
+
 my %conflict = map { $_ => 1 } find_conflict();
 
 # MERGE_RR records paths with conflicts immediately after merge