On 7/29/2018 6:33 AM, Nguyễn Thái Ngọc Duy wrote:
This is a micro optimization that probably only shines on repos with
deep directory structure. Instead of allocating and freeing a new
cache_entry in every iteration, we reuse the last one and only update
the parts that are new each iteration.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@xxxxxxxxx>
---
unpack-trees.c | 29 ++++++++++++++++++++---------
1 file changed, 20 insertions(+), 9 deletions(-)
diff --git a/unpack-trees.c b/unpack-trees.c
index 39566b28fb..c33ebaf001 100644
--- a/unpack-trees.c
+++ b/unpack-trees.c
@@ -694,6 +694,8 @@ static int traverse_by_cache_tree(int pos, int nr_entries, int nr_names,
{
struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
struct unpack_trees_options *o = info->data;
+ struct cache_entry *tree_ce = NULL;
+ int ce_len = 0;
int i, d;
if (!o->merge)
@@ -708,30 +710,39 @@ static int traverse_by_cache_tree(int pos, int nr_entries, int nr_names,
* in the first place.
*/
for (i = 0; i < nr_entries; i++) {
- struct cache_entry *tree_ce;
- int len, rc;
+ int new_ce_len, len, rc;
src[0] = o->src_index->cache[pos + i];
len = ce_namelen(src[0]);
- tree_ce = xcalloc(1, cache_entry_size(len));
+ new_ce_len = cache_entry_size(len);
+
+ if (new_ce_len > ce_len) {
+ new_ce_len <<= 1;
+ tree_ce = xrealloc(tree_ce, new_ce_len);
+ memset(tree_ce, 0, new_ce_len);
+ ce_len = new_ce_len;
+
+ tree_ce->ce_flags = create_ce_flags(0);
+
+ for (d = 1; d <= nr_names; d++)
+ src[d] = tree_ce;
+ }
Nice optimization - especially when there are a lot of cache entries and
large trees.
tree_ce->ce_mode = src[0]->ce_mode;
- tree_ce->ce_flags = create_ce_flags(0);
tree_ce->ce_namelen = len;
oidcpy(&tree_ce->oid, &src[0]->oid);
memcpy(tree_ce->name, src[0]->name, len + 1);
- for (d = 1; d <= nr_names; d++)
- src[d] = tree_ce;
-
rc = call_unpack_fn((const struct cache_entry * const *)src, o);
- free(tree_ce);
- if (rc < 0)
+ if (rc < 0) {
+ free(tree_ce);
return rc;
+ }
mark_ce_used(src[0], o);
}
+ free(tree_ce);
if (o->debug_unpack)
printf("Unpacked %d entries from %s to %s using cache-tree\n",
nr_entries,
