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, 6 insertions, 10 deletions

diff --git a/sequencer.c b/sequencer.c
index cdd30c0737..3c060e0547 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -263,11 +263,11 @@ static int do_recursive_merge(struct commit *base, struct commit *next,
 {
 	struct merge_options o;
 	struct tree *result, *next_tree, *base_tree, *head_tree;
-	int clean, index_fd;
+	int clean;
 	const char **xopt;
 	static struct lock_file index_lock;
 
-	index_fd = hold_locked_index(&index_lock, 1);
+	hold_locked_index(&index_lock, 1);
 
 	read_cache();
 
@@ -288,8 +288,7 @@ static int do_recursive_merge(struct commit *base, struct commit *next,
 			    next_tree, base_tree, &result);
 
 	if (active_cache_changed &&
-	    (write_cache(index_fd, active_cache, active_nr) ||
-	     commit_locked_index(&index_lock)))
+	    write_locked_index(&the_index, &index_lock, COMMIT_LOCK))
 		/* TRANSLATORS: %s will be "revert" or "cherry-pick" */
 		die(_("%s: Unable to write new index file"), action_name(opts));
 	rollback_lock_file(&index_lock);
@@ -341,9 +340,7 @@ static int is_index_unchanged(void)
 		active_cache_tree = cache_tree();
 
 	if (!cache_tree_fully_valid(active_cache_tree))
-		if (cache_tree_update(active_cache_tree,
-				      (const struct cache_entry * const *)active_cache,
-				      active_nr, 0))
+		if (cache_tree_update(&the_index, 0))
 			return error(_("Unable to update cache tree\n"));
 
 	return !hashcmp(active_cache_tree->sha1, head_commit->tree->object.sha1);
@@ -643,9 +640,8 @@ static void read_and_refresh_cache(struct replay_opts *opts)
 	if (read_index_preload(&the_index, NULL) < 0)
 		die(_("git %s: failed to read the index"), action_name(opts));
 	refresh_index(&the_index, REFRESH_QUIET|REFRESH_UNMERGED, NULL, NULL, NULL);
-	if (the_index.cache_changed) {
-		if (write_index(&the_index, index_fd) ||
-		    commit_locked_index(&index_lock))
+	if (the_index.cache_changed && index_fd >= 0) {
+		if (write_locked_index(&the_index, &index_lock, COMMIT_LOCK))
 			die(_("git %s: failed to refresh the index"), action_name(opts));
 	}
 	rollback_lock_file(&index_lock);