index: introduce git_index_uniq() function

It removes all entries with equal path except last added.

On large indexes git_index_append() + git_index_uniq() before writing is
*much* faster, than git_index_add().

Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>

include/git2/index.h

@@ -173,6 +173,13 @@ GIT_EXTERN(int) git_index_write(git_index *index);
 GIT_EXTERN(int) git_index_find(git_index *index, const char *path);
 
 /**
+ * Remove all entries with equal path except last added
+ *
+ * @param index an existing index object
+ */
+GIT_EXTERN(void) git_index_uniq(git_index *index);
+
+/**
  * Add or update an index entry from a file in disk
  *
  * The file `path` must be relative to the repository's

src/index.c

@@ -487,6 +487,11 @@ int git_index_find(git_index *index, const char *path)
 	return git_vector_bsearch2(&index->entries, index_srch, path);
 }
 
+void git_index_uniq(git_index *index)
+{
+	git_vector_uniq(&index->entries);
+}
+
 const git_index_entry_unmerged *git_index_get_unmerged_bypath(git_index *index, const char *path)
 {
 	int pos;