unpack-trees: reduce malloc in cache-tree walk
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@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Nguyễn Thái Ngọc Duy committed
Aug 18, 2018 at 16:41 UTC
f1e11c6510846321574e0ad9443843d7ba3eb758
1 file changed
+20
-9
unpack-trees.c
+20
-9
@@ -685,6 +685,8 @@ static int traverse_by_cache_tree(int pos, int nr_entries, int nr_names,
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{
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struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
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struct unpack_trees_options *o = info->data;
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+ struct cache_entry *tree_ce = NULL;
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+ int ce_len = 0;
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int i, d;
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if (!o->merge)
@@ -699,30 +701,39 @@ static int traverse_by_cache_tree(int pos, int nr_entries, int nr_names,
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* get here in the first place.
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*/
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for (i = 0; i < nr_entries; i++) {
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- struct cache_entry *tree_ce;
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- int len, rc;
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+ int new_ce_len, len, rc;
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src[0] = o->src_index->cache[pos + i];
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len = ce_namelen(src[0]);
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- tree_ce = xcalloc(1, cache_entry_size(len));
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+ new_ce_len = cache_entry_size(len);
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+
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+ if (new_ce_len > ce_len) {
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+ new_ce_len <<= 1;
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+ tree_ce = xrealloc(tree_ce, new_ce_len);
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+ memset(tree_ce, 0, new_ce_len);
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+ ce_len = new_ce_len;
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+
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+ tree_ce->ce_flags = create_ce_flags(0);
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+
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+ for (d = 1; d <= nr_names; d++)
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+ src[d] = tree_ce;
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+ }
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tree_ce->ce_mode = src[0]->ce_mode;
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- tree_ce->ce_flags = create_ce_flags(0);
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tree_ce->ce_namelen = len;
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oidcpy(&tree_ce->oid, &src[0]->oid);
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memcpy(tree_ce->name, src[0]->name, len + 1);
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- for (d = 1; d <= nr_names; d++)
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- src[d] = tree_ce;
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-
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rc = call_unpack_fn((const struct cache_entry * const *)src, o);
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- free(tree_ce);
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- if (rc < 0)
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+ if (rc < 0) {
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+ free(tree_ce);
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return rc;
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+ }
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mark_ce_used(src[0], o);
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}
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+ free(tree_ce);
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if (o->debug_unpack)
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printf("Unpacked %d entries from %s to %s using cache-tree\n",
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nr_entries,