cache: filter out tables that are not requested

Do not fetch table content for list commands that specify a
table name, e.g.

 # nft list table filter

This speeds up listing of a given table by not populating the
cache with tables that are not needed.

 - Full ruleset (huge with ~100k lines).

 # sudo nft list ruleset &> /dev/null
 real    0m3,049s
 user    0m2,080s
 sys     0m0,968s

- Listing per table is now faster:

 # nft list table nat &> /dev/null
 real    0m1,969s
 user    0m1,412s
 sys     0m0,556s

 # nft list table filter &> /dev/null
 real    0m0,697s
 user    0m0,478s
 sys     0m0,220s

Closes: https://bugzilla.netfilter.org/show_bug.cgi?id=1326
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 8 insertions, 2 deletions

diff --git a/include/cache.h b/include/cache.h
index 70aaf735..3130b2c0 100644
--- a/include/cache.h
+++ b/include/cache.h
@@ -38,12 +38,18 @@ enum cache_level_flags {
 	NFT_CACHE_FLUSHED	= (1 << 31),
 };
 
+struct nft_cache_filter {
+	const char		*table;
+};
+
 struct nft_cache;
 enum cmd_ops;
 
-unsigned int nft_cache_evaluate(struct nft_ctx *nft, struct list_head *cmds);
+unsigned int nft_cache_evaluate(struct nft_ctx *nft, struct list_head *cmds,
+				struct nft_cache_filter *filter);
 int nft_cache_update(struct nft_ctx *ctx, enum cmd_ops cmd,
-		     struct list_head *msgs);
+		     struct list_head *msgs,
+		     const struct nft_cache_filter *filter);
 bool nft_cache_needs_update(struct nft_cache *cache);
 void nft_cache_release(struct nft_cache *cache);