Merge branch 'nd/split-index'

An experiment to use two files (the base file and incremental
changes relative to it) to represent the index to reduce I/O cost
of rewriting a large index when only small part of the working tree
changes.

* nd/split-index: (32 commits)
  t1700: new tests for split-index mode
  t2104: make sure split index mode is off for the version test
  read-cache: force split index mode with GIT_TEST_SPLIT_INDEX
  read-tree: note about dropping split-index mode or index version
  read-tree: force split-index mode off on --index-output
  rev-parse: add --shared-index-path to get shared index path
  update-index --split-index: do not split if $GIT_DIR is read only
  update-index: new options to enable/disable split index mode
  split-index: strip pathname of on-disk replaced entries
  split-index: do not invalidate cache-tree at read time
  split-index: the reading part
  split-index: the writing part
  read-cache: mark updated entries for split index
  read-cache: save deleted entries in split index
  read-cache: mark new entries for split index
  read-cache: split-index mode
  read-cache: save index SHA-1 after reading
  entry.c: update cache_changed if refresh_cache is set in checkout_entry()
  cache-tree: mark istate->cache_changed on prime_cache_tree()
  cache-tree: mark istate->cache_changed on cache tree update
  ...

1 files changed, 4 insertions, 8 deletions

diff --git a/builtin/merge.c b/builtin/merge.c
index 86e9c61277..22491a1c2b 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -657,14 +657,12 @@ static int try_merge_strategy(const char *strategy, struct commit_list *common,
 			      struct commit_list *remoteheads,
 			      struct commit *head, const char *head_arg)
 {
-	int index_fd;
 	struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
 
-	index_fd = hold_locked_index(lock, 1);
+	hold_locked_index(lock, 1);
 	refresh_cache(REFRESH_QUIET);
 	if (active_cache_changed &&
-			(write_cache(index_fd, active_cache, active_nr) ||
-			 commit_locked_index(lock)))
+	    write_locked_index(&the_index, lock, COMMIT_LOCK))
 		return error(_("Unable to write index."));
 	rollback_lock_file(lock);
 
@@ -672,7 +670,6 @@ static int try_merge_strategy(const char *strategy, struct commit_list *common,
 		int clean, x;
 		struct commit *result;
 		struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
-		int index_fd;
 		struct commit_list *reversed = NULL;
 		struct merge_options o;
 		struct commit_list *j;
@@ -700,12 +697,11 @@ static int try_merge_strategy(const char *strategy, struct commit_list *common,
 		for (j = common; j; j = j->next)
 			commit_list_insert(j->item, &reversed);
 
-		index_fd = hold_locked_index(lock, 1);
+		hold_locked_index(lock, 1);
 		clean = merge_recursive(&o, head,
 				remoteheads->item, reversed, &result);
 		if (active_cache_changed &&
-				(write_cache(index_fd, active_cache, active_nr) ||
-				 commit_locked_index(lock)))
+		    write_locked_index(&the_index, lock, COMMIT_LOCK))
 			die (_("unable to write %s"), get_index_file());
 		rollback_lock_file(lock);
 		return clean ? 0 : 1;