Simplify cache API

Earlier, add_file_to_index() invalidated the path in the cache-tree
but remove_file_from_cache() did not, and the user of the latter
needed to invalidate the entry himself.  This led to a few bugs due to
missed invalidate calls already.  This patch makes the management of
cache-tree less error prone by making more invalidate calls from lower
level cache API functions.

The rules are:

 - If you are going to write the index, you should either maintain
   cache_tree correctly.

   - If you cannot, alternatively you can remove the entire cache_tree
     by calling cache_tree_free() before you call write_cache().

   - When you modify the index, cache_tree_invalidate_path() should be
     called with the path you are modifying, to discard the entry from
     the cache-tree structure.

 - The following cache API functions exported from read-cache.c (and
   the macro whose names have "cache" instead of "index")
   automatically call cache_tree_invalidate_path() for you:

   - remove_file_from_index();
   - add_file_to_index();
   - add_index_entry();

   You can modify the index bypassing the above API functions
   (e.g. find an existing cache entry from the index and modify it in
   place).  You need to call cache_tree_invalidate_path() yourself in
   such a case.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/read-cache.c b/read-cache.c
index 8b1c94e0e3..d82a99a915 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -346,6 +346,7 @@ int remove_file_from_index(struct index_state *istate, const char *path)
 	int pos = index_name_pos(istate, path, strlen(path));
 	if (pos < 0)
 		pos = -pos-1;
+	cache_tree_invalidate_path(istate->cache_tree, path);
 	while (pos < istate->cache_nr && !strcmp(istate->cache[pos]->name, path))
 		remove_index_entry_at(istate, pos);
 	return 0;
@@ -430,7 +431,6 @@ int add_file_to_index(struct index_state *istate, const char *path, int verbose)
 		die("unable to add %s to index",path);
 	if (verbose)
 		printf("add '%s'\n", path);
-	cache_tree_invalidate_path(istate->cache_tree, path);
 	return 0;
 }
 
@@ -673,6 +673,7 @@ static int add_index_entry_with_check(struct index_state *istate, struct cache_e
 	int ok_to_replace = option & ADD_CACHE_OK_TO_REPLACE;
 	int skip_df_check = option & ADD_CACHE_SKIP_DFCHECK;
 
+	cache_tree_invalidate_path(istate->cache_tree, ce->name);
 	pos = index_name_pos(istate, ce->name, ntohs(ce->ce_flags));
 
 	/* existing match? Just replace it. */