[RFC PATCH 4/5] repack: add delta-islands support

[Christian Couder <christian.couder@gmail.com>]

From: Jeff King <peff@peff.net>

Implement simple support for --delta-islands option and
repack.useDeltaIslands config variable in git repack.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
---
 Documentation/config.txt     | 4 ++++
 Documentation/git-repack.txt | 5 +++++
 builtin/repack.c             | 9 +++++++++
 3 files changed, 18 insertions(+)

diff --git a/Documentation/config.txt b/Documentation/config.txt
index f682e92a1a..1da39da2a6 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -3091,6 +3091,10 @@ repack.packKeptObjects::
 	index is being written (either via `--write-bitmap-index` or
 	`repack.writeBitmaps`).
 
+repack.useDeltaIslands::
+	If set to true, makes `git repack` act as if `--delta-islands`
+	was passed. Defaults to `false`.
+
 repack.writeBitmaps::
 	When true, git will write a bitmap index when packing all
 	objects to disk (e.g., when `git repack -a` is run).  This
diff --git a/Documentation/git-repack.txt b/Documentation/git-repack.txt
index d90e7907f4..a8b2d4722f 100644
--- a/Documentation/git-repack.txt
+++ b/Documentation/git-repack.txt
@@ -155,6 +155,11 @@ depth is 4095.
 	being removed. In addition, any unreachable loose objects will
 	be packed (and their loose counterparts removed).
 
+-i::
+--delta-islands::
+	Pass the `--delta-islands` option to `git-pack-objects`, see
+	linkgit:git-pack-objects[1].
+
 Configuration
 -------------
 
diff --git a/builtin/repack.c b/builtin/repack.c
index 6c636e159e..5ab9ee69e4 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -12,6 +12,7 @@
 static int delta_base_offset = 1;
 static int pack_kept_objects = -1;
 static int write_bitmaps;
+static int use_delta_islands;
 static char *packdir, *packtmp;
 
 static const char *const git_repack_usage[] = {
@@ -40,6 +41,10 @@ static int repack_config(const char *var, const char *value, void *cb)
 		write_bitmaps = git_config_bool(var, value);
 		return 0;
 	}
+	if (!strcmp(var, "repack.usedeltaislands")) {
+		use_delta_islands = git_config_bool(var, value);
+		return 0;
+	}
 	return git_default_config(var, value, cb);
 }
 
@@ -194,6 +199,8 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 				N_("pass --local to git-pack-objects")),
 		OPT_BOOL('b', "write-bitmap-index", &write_bitmaps,
 				N_("write bitmap index")),
+		OPT_BOOL('i', "delta-islands", &use_delta_islands,
+				N_("pass --delta-islands to git-pack-objects")),
 		OPT_STRING(0, "unpack-unreachable", &unpack_unreachable, N_("approxidate"),
 				N_("with -A, do not loosen objects older than this")),
 		OPT_BOOL('k', "keep-unreachable", &keep_unreachable,
@@ -267,6 +274,8 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 		argv_array_pushf(&cmd.args, "--no-reuse-object");
 	if (write_bitmaps)
 		argv_array_push(&cmd.args, "--write-bitmap-index");
+	if (use_delta_islands)
+		argv_array_push(&cmd.args, "--delta-islands");
 
 	if (pack_everything & ALL_INTO_ONE) {
 		get_non_kept_pack_filenames(&existing_packs, &keep_pack_list);
-- 
2.18.0.237.gffdb1dbdaa