Merge pull request microsoft#417 from vdye/sparse-index/git-reset

Sparse index: `git reset`

builtin/reset.c

@@ -196,6 +196,73 @@ static void update_index_from_diff(struct diff_queue_struct *q,
 	}
 }
 
+static int pathspec_needs_expanded_index(const struct pathspec *pathspec)
+{
+	unsigned int i, pos;
+	int res = 0;
+	char *skip_worktree_seen = NULL;
+
+	/*
+	 * When using a magic pathspec, assume for the sake of simplicity that
+	 * the index needs to be expanded to match all matchable files.
+	 */
+	if (pathspec->magic)
+		return 1;
+
+	for (i = 0; i < pathspec->nr; i++) {
+		struct pathspec_item item = pathspec->items[i];
+
+		/*
+		 * If the pathspec item has a wildcard, the index should be expanded
+		 * if the pathspec has the possibility of matching a subset of entries inside
+		 * of a sparse directory (but not the entire directory).
+		 *
+		 * If the pathspec item is a literal path, the index only needs to be expanded
+		 * if a) the pathspec isn't in the sparse checkout cone (to make sure we don't
+		 * expand for in-cone files) and b) it doesn't match any sparse directories
+		 * (since we can reset whole sparse directories without expanding them).
+		 */
+		if (item.nowildcard_len < item.len) {
+			for (pos = 0; pos < active_nr; pos++) {
+				struct cache_entry *ce = active_cache[pos];
+
+				if (!S_ISSPARSEDIR(ce->ce_mode))
+					continue;
+
+				/*
+				 * If the pre-wildcard length is longer than the sparse
+				 * directory name and the sparse directory is the first
+				 * component of the pathspec, need to expand the index.
+				 */
+				if (item.nowildcard_len > ce_namelen(ce) &&
+				    !strncmp(item.original, ce->name, ce_namelen(ce))) {
+					res = 1;
+					break;
+				}
+
+				/*
+				 * If the pre-wildcard length is shorter than the sparse
+				 * directory and the pathspec does not match the whole
+				 * directory, need to expand the index.
+				 */
+				if (!strncmp(item.original, ce->name, item.nowildcard_len) &&
+				    wildmatch(item.original, ce->name, 0)) {
+					res = 1;
+					break;
+				}
+			}
+		} else if (!path_in_cone_mode_sparse_checkout(item.original, &the_index) &&
+			   !matches_skip_worktree(pathspec, i, &skip_worktree_seen))
+			res = 1;
+
+		if (res > 0)
+			break;
+	}
+
+	free(skip_worktree_seen);
+	return res;
+}
+
 static int read_from_tree(const struct pathspec *pathspec,
 			  struct object_id *tree_oid,
 			  int intent_to_add)
@@ -208,7 +275,13 @@ static int read_from_tree(const struct pathspec *pathspec,
 	opt.format_callback = update_index_from_diff;
 	opt.format_callback_data = &intent_to_add;
 	opt.flags.override_submodule_config = 1;
+	opt.flags.recursive = 1;
 	opt.repo = the_repository;
+	opt.change = diff_change;
+	opt.add_remove = diff_addremove;
+
+	if (pathspec->nr && the_index.sparse_index && pathspec_needs_expanded_index(pathspec))
+		ensure_full_index(&the_index);
 
 	if (do_diff_cache(tree_oid, &opt))
 		return 1;
@@ -287,9 +360,6 @@ static void parse_args(struct pathspec *pathspec,
 	}
 	*rev_ret = rev;
 
-	if (read_cache() < 0)
-		die(_("index file corrupt"));
-
 	parse_pathspec(pathspec, 0,
 		       PATHSPEC_PREFER_FULL |
 		       (patch_mode ? PATHSPEC_PREFIX_ORIGIN : 0),
@@ -446,6 +516,12 @@ int cmd_reset(int argc, const char **argv, const char *prefix)
 	if (intent_to_add && reset_type != MIXED)
 		die(_("-N can only be used with --mixed"));
 
+	prepare_repo_settings(the_repository);
+	the_repository->settings.command_requires_full_index = 0;
+
+	if (read_cache() < 0)
+		die(_("index file corrupt"));
+
 	/* Soft reset does not touch the index file nor the working tree
 	 * at all, but requires them in a good order.  Other resets reset
 	 * the index file to the tree object we are switching to. */

cache-tree.c

@@ -801,15 +801,26 @@ int write_index_as_tree(struct object_id *oid, struct index_state *index_state,
 	return ret;
 }
 
+static void prime_cache_tree_sparse_dir(struct cache_tree *it,
+					struct tree *tree)
+{
+
+	oidcpy(&it->oid, &tree->object.oid);
+	it->entry_count = 1;
+}
+
 static void prime_cache_tree_rec(struct repository *r,
 				 struct cache_tree *it,
-				 struct tree *tree)
+				 struct tree *tree,
+				 struct strbuf *tree_path)
 {
 	struct tree_desc desc;
 	struct name_entry entry;
 	int cnt;
+	int base_path_len = tree_path->len;
 
 	oidcpy(&it->oid, &tree->object.oid);
+
 	init_tree_desc(&desc, tree->buffer, tree->size);
 	cnt = 0;
 	while (tree_entry(&desc, &entry)) {
@@ -818,26 +829,55 @@ static void prime_cache_tree_rec(struct repository *r,
 		else {
 			struct cache_tree_sub *sub;
 			struct tree *subtree = lookup_tree(r, &entry.oid);
+
 			if (!subtree->object.parsed)
 				parse_tree(subtree);
 			sub = cache_tree_sub(it, entry.path);
 			sub->cache_tree = cache_tree();
-			prime_cache_tree_rec(r, sub->cache_tree, subtree);
+
+			/*
+			 * Recursively-constructed subtree path is only needed when working
+			 * in a sparse index (where it's used to determine whether the
+			 * subtree is a sparse directory in the index).
+			 */
+			if (r->index->sparse_index) {
+				strbuf_setlen(tree_path, base_path_len);
+				strbuf_grow(tree_path, base_path_len + entry.pathlen + 1);
+				strbuf_add(tree_path, entry.path, entry.pathlen);
+				strbuf_addch(tree_path, '/');
+			}
+
+			/*
+			 * If a sparse index is in use, the directory being processed may be
+			 * sparse. To confirm that, we can check whether an entry with that
+			 * exact name exists in the index. If it does, the created subtree
+			 * should be sparse. Otherwise, cache tree expansion should continue
+			 * as normal.
+			 */
+			if (r->index->sparse_index &&
+			    index_entry_exists(r->index, tree_path->buf, tree_path->len))
+				prime_cache_tree_sparse_dir(sub->cache_tree, subtree);
+			else
+				prime_cache_tree_rec(r, sub->cache_tree, subtree, tree_path);
 			cnt += sub->cache_tree->entry_count;
 		}
 	}
+
 	it->entry_count = cnt;
 }
 
 void prime_cache_tree(struct repository *r,
 		      struct index_state *istate,
 		      struct tree *tree)
 {
+	struct strbuf tree_path = STRBUF_INIT;
+
 	trace2_region_enter("cache-tree", "prime_cache_tree", r);
 	cache_tree_free(&istate->cache_tree);
 	istate->cache_tree = cache_tree();
 
-	prime_cache_tree_rec(r, istate->cache_tree, tree);
+	prime_cache_tree_rec(r, istate->cache_tree, tree, &tree_path);
+	strbuf_release(&tree_path);
 	istate->cache_changed |= CACHE_TREE_CHANGED;
 	trace2_region_leave("cache-tree", "prime_cache_tree", r);
 }

cache.h

@@ -833,6 +833,16 @@ struct cache_entry *index_file_next_match(struct index_state *istate, struct cac
  */
 int index_name_pos(struct index_state *, const char *name, int namelen);
 
+/*
+ * Determines whether an entry with the given name exists within the
+ * given index. The return value is 1 if an exact match is found, otherwise
+ * it is 0. Note that, unlike index_name_pos, this function does not expand
+ * the index if it is sparse. If an item exists within the full index but it
+ * is contained within a sparse directory (and not in the sparse index), 0 is
+ * returned.
+ */
+int index_entry_exists(struct index_state *, const char *name, int namelen);
+
 /*
  * Some functions return the negative complement of an insert position when a
  * precise match was not found but a position was found where the entry would

read-cache.c

@@ -70,6 +70,11 @@
  */
 #define CACHE_ENTRY_PATH_LENGTH 80
 
+enum index_search_mode {
+	NO_EXPAND_SPARSE = 0,
+	EXPAND_SPARSE = 1
+};
+
 static inline struct cache_entry *mem_pool__ce_alloc(struct mem_pool *mem_pool, size_t len)
 {
 	struct cache_entry *ce;
@@ -564,7 +569,10 @@ int cache_name_stage_compare(const char *name1, int len1, int stage1, const char
 	return 0;
 }
 
-static int index_name_stage_pos(struct index_state *istate, const char *name, int namelen, int stage)
+static int index_name_stage_pos(struct index_state *istate,
+				const char *name, int namelen,
+				int stage,
+				enum index_search_mode search_mode)
 {
 	int first, last;
 
@@ -583,7 +591,7 @@ static int index_name_stage_pos(struct index_state *istate, const char *name, in
 		first = next+1;
 	}
 
-	if (istate->sparse_index &&
+	if (search_mode == EXPAND_SPARSE && istate->sparse_index &&
 	    first > 0) {
 		/* Note: first <= istate->cache_nr */
 		struct cache_entry *ce = istate->cache[first - 1];
@@ -599,7 +607,7 @@ static int index_name_stage_pos(struct index_state *istate, const char *name, in
 		    ce_namelen(ce) < namelen &&
 		    !strncmp(name, ce->name, ce_namelen(ce))) {
 			ensure_full_index(istate);
-			return index_name_stage_pos(istate, name, namelen, stage);
+			return index_name_stage_pos(istate, name, namelen, stage, search_mode);
 		}
 	}
 
@@ -608,7 +616,12 @@ static int index_name_stage_pos(struct index_state *istate, const char *name, in
 
 int index_name_pos(struct index_state *istate, const char *name, int namelen)
 {
-	return index_name_stage_pos(istate, name, namelen, 0);
+	return index_name_stage_pos(istate, name, namelen, 0, EXPAND_SPARSE);
+}
+
+int index_entry_exists(struct index_state *istate, const char *name, int namelen)
+{
+	return index_name_stage_pos(istate, name, namelen, 0, NO_EXPAND_SPARSE) >= 0;
 }
 
 int remove_index_entry_at(struct index_state *istate, int pos)
@@ -1250,7 +1263,7 @@ static int has_dir_name(struct index_state *istate,
 			 */
 		}
 
-		pos = index_name_stage_pos(istate, name, len, stage);
+		pos = index_name_stage_pos(istate, name, len, stage, EXPAND_SPARSE);
 		if (pos >= 0) {
 			/*
 			 * Found one, but not so fast.  This could
@@ -1350,7 +1363,7 @@ static int add_index_entry_with_check(struct index_state *istate, struct cache_e
 		strcmp(ce->name, istate->cache[istate->cache_nr - 1]->name) > 0)
 		pos = index_pos_to_insert_pos(istate->cache_nr);
 	else
-		pos = index_name_stage_pos(istate, ce->name, ce_namelen(ce), ce_stage(ce));
+		pos = index_name_stage_pos(istate, ce->name, ce_namelen(ce), ce_stage(ce), EXPAND_SPARSE);
 
 	/* existing match? Just replace it. */
 	if (pos >= 0) {
@@ -1385,7 +1398,7 @@ static int add_index_entry_with_check(struct index_state *istate, struct cache_e
 		if (!ok_to_replace)
 			return error(_("'%s' appears as both a file and as a directory"),
 				     ce->name);
-		pos = index_name_stage_pos(istate, ce->name, ce_namelen(ce), ce_stage(ce));
+		pos = index_name_stage_pos(istate, ce->name, ce_namelen(ce), ce_stage(ce), EXPAND_SPARSE);
 		pos = -pos-1;
 	}
 	return pos + 1;