read-cache: be specific what part of the index has changed

cache entry additions, removals and modifications are separated
out. The rest of changes are still in the catch-all flag
SOMETHING_CHANGED, which would be more specific later.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/update-index.c

@@ -56,7 +56,7 @@ static int mark_ce_flags(const char *path, int flag, int mark)
 		else
 			active_cache[pos]->ce_flags &= ~flag;
 		cache_tree_invalidate_path(active_cache_tree, path);
-		active_cache_changed = 1;
+		active_cache_changed = SOMETHING_CHANGED;
 		return 0;
 	}
 	return -1;
@@ -268,7 +268,7 @@ static void chmod_path(int flip, const char *path)
 		goto fail;
 	}
 	cache_tree_invalidate_path(active_cache_tree, path);
-	active_cache_changed = 1;
+	active_cache_changed = SOMETHING_CHANGED;
 	report("chmod %cx '%s'", flip, path);
 	return;
  fail:
@@ -889,7 +889,7 @@ int cmd_update_index(int argc, const char **argv, const char *prefix)
 			    INDEX_FORMAT_LB, INDEX_FORMAT_UB);
 
 		if (the_index.version != preferred_index_format)
-			active_cache_changed = 1;
+			active_cache_changed = SOMETHING_CHANGED;
 		the_index.version = preferred_index_format;
 	}
 

cache.h

@@ -268,6 +268,11 @@ static inline unsigned int canon_mode(unsigned int mode)
 
 #define cache_entry_size(len) (offsetof(struct cache_entry,name) + (len) + 1)
 
+#define SOMETHING_CHANGED	(1 << 0) /* unclassified changes go here */
+#define CE_ENTRY_CHANGED	(1 << 1)
+#define CE_ENTRY_REMOVED	(1 << 2)
+#define CE_ENTRY_ADDED		(1 << 3)
+
 struct index_state {
 	struct cache_entry **cache;
 	unsigned int version;

read-cache.c

@@ -51,7 +51,7 @@ static void replace_index_entry(struct index_state *istate, int nr, struct cache
 	remove_name_hash(istate, old);
 	free(old);
 	set_index_entry(istate, nr, ce);
-	istate->cache_changed = 1;
+	istate->cache_changed |= CE_ENTRY_CHANGED;
 }
 
 void rename_index_entry_at(struct index_state *istate, int nr, const char *new_name)
@@ -482,7 +482,7 @@ int remove_index_entry_at(struct index_state *istate, int pos)
 	record_resolve_undo(istate, ce);
 	remove_name_hash(istate, ce);
 	free(ce);
-	istate->cache_changed = 1;
+	istate->cache_changed |= CE_ENTRY_REMOVED;
 	istate->cache_nr--;
 	if (pos >= istate->cache_nr)
 		return 0;
@@ -512,7 +512,7 @@ void remove_marked_cache_entries(struct index_state *istate)
 	}
 	if (j == istate->cache_nr)
 		return;
-	istate->cache_changed = 1;
+	istate->cache_changed |= CE_ENTRY_REMOVED;
 	istate->cache_nr = j;
 }
 
@@ -1002,7 +1002,7 @@ int add_index_entry(struct index_state *istate, struct cache_entry *ce, int opti
 			istate->cache + pos,
 			(istate->cache_nr - pos - 1) * sizeof(ce));
 	set_index_entry(istate, pos, ce);
-	istate->cache_changed = 1;
+	istate->cache_changed |= CE_ENTRY_ADDED;
 	return 0;
 }
 
@@ -1101,6 +1101,7 @@ static struct cache_entry *refresh_cache_ent(struct index_state *istate,
 	    !(ce->ce_flags & CE_VALID))
 		updated->ce_flags &= ~CE_VALID;
 
+	/* istate->cache_changed is updated in the caller */
 	return updated;
 }
 
@@ -1182,7 +1183,7 @@ int refresh_index(struct index_state *istate, unsigned int flags,
 				 * means the index is not valid anymore.
 				 */
 				ce->ce_flags &= ~CE_VALID;
-				istate->cache_changed = 1;
+				istate->cache_changed |= CE_ENTRY_CHANGED;
 			}
 			if (quiet)
 				continue;

resolve-undo.c

@@ -110,7 +110,7 @@ void resolve_undo_clear_index(struct index_state *istate)
 	string_list_clear(resolve_undo, 1);
 	free(resolve_undo);
 	istate->resolve_undo = NULL;
-	istate->cache_changed = 1;
+	istate->cache_changed = SOMETHING_CHANGED;
 }
 
 int unmerge_index_entry_at(struct index_state *istate, int pos)