read-cache: speed up add_index_entry during checkout

Teach add_index_entry_with_check() to see if the path
of the new item is greater than the last path in the
index array before attempting to search for it.

During checkout, merge_working_tree() populates the new
index in sorted order, so this change will save a binary
lookups per file.  This preserves the original behavior
but simply checks the last element before starting the
search.

This helps performance on very large repositories.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Jeff Hostetler 2017-04-19 17:06:16 +00:00 committed by Junio C Hamano
parent 350d870143
commit e5494631ed

View File

@ -1021,7 +1021,16 @@ static int add_index_entry_with_check(struct index_state *istate, struct cache_e
if (!(option & ADD_CACHE_KEEP_CACHE_TREE))
cache_tree_invalidate_path(istate, ce->name);
pos = index_name_stage_pos(istate, ce->name, ce_namelen(ce), ce_stage(ce));
/*
* If this entry's path sorts after the last entry in the index,
* we can avoid searching for it.
*/
if (istate->cache_nr > 0 &&
strcmp(ce->name, istate->cache[istate->cache_nr - 1]->name) > 0)
pos = -istate->cache_nr - 1;
else
pos = index_name_stage_pos(istate, ce->name, ce_namelen(ce), ce_stage(ce));
/* existing match? Just replace it. */
if (pos >= 0) {