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| -rwxr-xr-x | contrib/examples/git-rerere.perl | 284 |
1 files changed, 284 insertions, 0 deletions
diff --git a/contrib/examples/git-rerere.perl b/contrib/examples/git-rerere.perl new file mode 100755 index 000000000..4f692091e --- /dev/null +++ b/contrib/examples/git-rerere.perl @@ -0,0 +1,284 @@ +#!/usr/bin/perl +# +# REuse REcorded REsolve. This tool records a conflicted automerge +# result and its hand resolution, and helps to resolve future +# automerge that results in the same conflict. +# +# To enable this feature, create a directory 'rr-cache' under your +# .git/ directory. + +use Digest; +use File::Path; +use File::Copy; + +my $git_dir = $::ENV{GIT_DIR} || ".git"; +my $rr_dir = "$git_dir/rr-cache"; +my $merge_rr = "$git_dir/rr-cache/MERGE_RR"; + +my %merge_rr = (); + +sub read_rr { + if (!-f $merge_rr) { + %merge_rr = (); + return; + } + my $in; + local $/ = "\0"; + open $in, "<$merge_rr" or die "$!: $merge_rr"; + while (<$in>) { + chomp; + my ($name, $path) = /^([0-9a-f]{40})\t(.*)$/s; + $merge_rr{$path} = $name; + } + close $in; +} + +sub write_rr { + my $out; + open $out, ">$merge_rr" or die "$!: $merge_rr"; + for my $path (sort keys %merge_rr) { + my $name = $merge_rr{$path}; + print $out "$name\t$path\0"; + } + close $out; +} + +sub compute_conflict_name { + my ($path) = @_; + my @side = (); + my $in; + open $in, "<$path" or die "$!: $path"; + + my $sha1 = Digest->new("SHA-1"); + my $hunk = 0; + while (<$in>) { + if (/^<<<<<<< .*/) { + $hunk++; + @side = ([], undef); + } + elsif (/^=======$/) { + $side[1] = []; + } + elsif (/^>>>>>>> .*/) { + my ($one, $two); + $one = join('', @{$side[0]}); + $two = join('', @{$side[1]}); + if ($two le $one) { + ($one, $two) = ($two, $one); + } + $sha1->add($one); + $sha1->add("\0"); + $sha1->add($two); + $sha1->add("\0"); + @side = (); + } + elsif (@side == 0) { + next; + } + elsif (defined $side[1]) { + push @{$side[1]}, $_; + } + else { + push @{$side[0]}, $_; + } + } + close $in; + return ($sha1->hexdigest, $hunk); +} + +sub record_preimage { + my ($path, $name) = @_; + my @side = (); + my ($in, $out); + open $in, "<$path" or die "$!: $path"; + open $out, ">$name" or die "$!: $name"; + + while (<$in>) { + if (/^<<<<<<< .*/) { + @side = ([], undef); + } + elsif (/^=======$/) { + $side[1] = []; + } + elsif (/^>>>>>>> .*/) { + my ($one, $two); + $one = join('', @{$side[0]}); + $two = join('', @{$side[1]}); + if ($two le $one) { + ($one, $two) = ($two, $one); + } + print $out "<<<<<<<\n"; + print $out $one; + print $out "=======\n"; + print $out $two; + print $out ">>>>>>>\n"; + @side = (); + } + elsif (@side == 0) { + print $out $_; + } + elsif (defined $side[1]) { + push @{$side[1]}, $_; + } + else { + push @{$side[0]}, $_; + } + } + close $out; + close $in; +} + +sub find_conflict { + my $in; + local $/ = "\0"; + my $pid = open($in, '-|'); + die "$!" unless defined $pid; + if (!$pid) { + exec(qw(git ls-files -z -u)) or die "$!: ls-files"; + } + my %path = (); + my @path = (); + while (<$in>) { + chomp; + my ($mode, $sha1, $stage, $path) = + /^([0-7]+) ([0-9a-f]{40}) ([123])\t(.*)$/s; + $path{$path} |= (1 << $stage); + } + close $in; + while (my ($path, $status) = each %path) { + if ($status == 14) { push @path, $path; } + } + return @path; +} + +sub merge { + my ($name, $path) = @_; + record_preimage($path, "$rr_dir/$name/thisimage"); + unless (system('git', 'merge-file', map { "$rr_dir/$name/${_}image" } + qw(this pre post))) { + my $in; + open $in, "<$rr_dir/$name/thisimage" or + die "$!: $name/thisimage"; + my $out; + open $out, ">$path" or die "$!: $path"; + while (<$in>) { print $out $_; } + close $in; + close $out; + return 1; + } + 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 +# failed. Some of the conflicted paths might have been hand resolved +# in the working tree since then, but the initial run would catch all +# and register their preimages. + +for my $path (keys %conflict) { + # This path has conflict. If it is not recorded yet, + # record the pre-image. + if (!exists $merge_rr{$path}) { + my ($name, $hunk) = compute_conflict_name($path); + next unless ($hunk); + $merge_rr{$path} = $name; + if (! -d "$rr_dir/$name") { + mkpath("$rr_dir/$name", 0, 0777); + print STDERR "Recorded preimage for '$path'\n"; + record_preimage($path, "$rr_dir/$name/preimage"); + } + } +} + +# Now some of the paths that had conflicts earlier might have been +# hand resolved. Others may be similar to a conflict already that +# was resolved before. + +for my $path (keys %merge_rr) { + my $name = $merge_rr{$path}; + + # We could resolve this automatically if we have images. + if (-f "$rr_dir/$name/preimage" && + -f "$rr_dir/$name/postimage") { + if (merge($name, $path)) { + print STDERR "Resolved '$path' using previous resolution.\n"; + # Then we do not have to worry about this path + # anymore. + delete $merge_rr{$path}; + next; + } + } + + # Let's see if we have resolved it. + (undef, my $hunk) = compute_conflict_name($path); + next if ($hunk); + + print STDERR "Recorded resolution for '$path'.\n"; + copy($path, "$rr_dir/$name/postimage"); + # And we do not have to worry about this path anymore. + delete $merge_rr{$path}; +} + +# Write out the rest. +write_rr(); |