filter-branch: stash away ref map in a branch

With "--state-branch=<branchname>" option, the mapping from old object names
and filtered ones in ./map/ directory is stashed away in the object database,
and the one from the previous run is read to populate the ./map/ directory,
allowing for incremental updates of large trees.

Signed-off-by: Ian Campbell <ijc@hellion.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/git-filter-branch.txt b/Documentation/git-filter-branch.txt
index 9e5169aa64f4ffd5ea42f85b2dbe812086e9652c..bebdcdec5ad4775588abe8814c59a269c7c1a832 100644 (file)
--- a/Documentation/git-filter-branch.txt
+++ b/Documentation/git-filter-branch.txt
@@ -14,7 +14,7 @@ SYNOPSIS
        [--commit-filter <command>] [--tag-name-filter <command>]
        [--subdirectory-filter <directory>] [--prune-empty]
        [--original <namespace>] [-d <directory>] [-f | --force]
-       [--] [<rev-list options>...]
+       [--state-branch <branch>] [--] [<rev-list options>...]
 
 DESCRIPTION
 -----------
@@ -198,6 +198,12 @@ to other tags will be rewritten to point to the underlying commit.
        directory or when there are already refs starting with
        'refs/original/', unless forced.
 
+--state-branch <branch>::
+       This option will cause the mapping from old to new objects to
+       be loaded from named branch upon startup and saved as a new
+       commit to that branch upon exit, enabling incremental of large
+       trees. If '<branch>' does not exist it will be created.
+
 <rev-list options>...::
        Arguments for 'git rev-list'.  All positive refs included by
        these options are rewritten.  You may also specify options

diff --git a/git-filter-branch.sh b/git-filter-branch.sh
index 9edb9420642af466d2cf1c05a8ce6f59a3273767..956869b8e397affd189d99ad7bf0c2debea79f10 100755 (executable)
--- a/git-filter-branch.sh
+++ b/git-filter-branch.sh
@@ -86,7 +86,7 @@ USAGE="[--setup <command>] [--env-filter <command>]
        [--parent-filter <command>] [--msg-filter <command>]
        [--commit-filter <command>] [--tag-name-filter <command>]
        [--subdirectory-filter <directory>] [--original <namespace>]
-       [-d <directory>] [-f | --force]
+       [-d <directory>] [-f | --force] [--state-branch <branch>]
        [--] [<rev-list options>...]"
 
 OPTIONS_SPEC=
@@ -106,6 +106,7 @@ filter_msg=cat
 filter_commit=
 filter_tag_name=
 filter_subdir=
+state_branch=
 orig_namespace=refs/original/
 force=
 prune_empty=
@@ -181,6 +182,9 @@ do
        --original)
                orig_namespace=$(expr "$OPTARG/" : '\(.*[^/]\)/*$')/
                ;;
+       --state-branch)
+               state_branch="$OPTARG"
+               ;;
        *)
                usage
                ;;
@@ -259,6 +263,26 @@ export GIT_INDEX_FILE
 # map old->new commit ids for rewriting parents
 mkdir ../map || die "Could not create map/ directory"
 
+if test -n "$state_branch"
+then
+       state_commit=$(git rev-parse --no-flags --revs-only "$state_branch")
+       if test -n "$state_commit"
+       then
+               echo "Populating map from $state_branch ($state_commit)" 1>&2
+               perl -e'open(MAP, "-|", "git show $ARGV[0]:filter.map") or die;
+                       while (<MAP>) {
+                               m/(.*):(.*)/ or die;
+                               open F, ">../map/$1" or die;
+                               print F "$2" or die;
+                               close(F) or die;
+                       }
+                       close(MAP) or die;' "$state_commit" \
+                               || die "Unable to load state from $state_branch:filter.map"
+       else
+               echo "Branch $state_branch does not exist. Will create" 1>&2
+       fi
+fi
+
 # we need "--" only if there are no path arguments in $@
 nonrevs=$(git rev-parse --no-revs "$@") || exit
 if test -z "$nonrevs"
@@ -590,6 +614,29 @@ test -z "$ORIG_GIT_COMMITTER_DATE" || {
        export GIT_COMMITTER_DATE
 }
 
+if test -n "$state_branch"
+then
+       echo "Saving rewrite state to $state_branch" 1>&2
+       state_blob=$(
+               perl -e'opendir D, "../map" or die;
+                       open H, "|-", "git hash-object -w --stdin" or die;
+                       foreach (sort readdir(D)) {
+                               next if m/^\.\.?$/;
+                               open F, "<../map/$_" or die;
+                               chomp($f = <F>);
+                               print H "$_:$f\n" or die;
+                       }
+                       close(H) or die;' || die "Unable to save state")
+       state_tree=$(/bin/echo -e "100644 blob $state_blob\tfilter.map" | git mktree)
+       if test -n "$state_commit"
+       then
+               state_commit=$(/bin/echo "Sync" | git commit-tree "$state_tree" -p "$state_commit")
+       else
+               state_commit=$(/bin/echo "Sync" | git commit-tree "$state_tree" )
+       fi
+       git update-ref "$state_branch" "$state_commit"
+fi
+
 cd "$orig_dir"
 rm -rf "$tempdir"