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 <pclo...@gmail.com> --- 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,
