From a3af0aff50cd3e899cb5205d4d5330a96aeffaa5 Mon Sep 17 00:00:00 2001

From: Phil Sutter <psutter@redhat.com>

Date: Mon, 17 Dec 2018 17:30:06 +0100

Subject: [PATCH] chain: Hash chain list by name

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1658533

Upstream Status: libnftnl commit 7170f0929ef50

commit 7170f0929ef50a1a45d9fd5d058ea6178c8e56ef

Author: Phil Sutter <phil@nwl.cc>

Date:   Tue Dec 11 18:44:00 2018 +0100

    chain: Hash chain list by name

    Introduce a hash table to speedup nftnl_chain_list_lookup_byname(). In

    theory this could replace the linked list completely but has been left

    in place so that nftnl_chain_list_add_tail() still does what it's

    supposed to and iterators return chains in original order.

    Speed was tested using a simple script which creates a dump file

    containing a number of custom chains and for each of them two rules in

    INPUT chain jumping to it. The following table compares run-time of

    iptables-legacy-restore with iptables-nft-restore before and after this

    patch:

    count      legacy       nft-old        nft-new

    ----------------------------------------------

    10000         26s           38s            31s

    50000        137s          339s           149s

    So while it is still not as quick, it now scales nicely (at least in

    this very primitive test).

    Signed-off-by: Phil Sutter <phil@nwl.cc>

    Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

---

 src/chain.c | 30 +++++++++++++++++++++++++++++-

 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/src/chain.c b/src/chain.c

index 22bb45c..ae074fd 100644

--- a/src/chain.c

+++ b/src/chain.c

@@ -32,6 +32,7 @@

 struct nftnl_chain {

 	struct list_head head;

+	struct hlist_node hnode;

 	const char	*name;

 	const char	*type;

@@ -991,20 +992,27 @@ void nftnl_rule_iter_destroy(struct nftnl_rule_iter *iter)

 	xfree(iter);

 }

+#define CHAIN_NAME_HSIZE	512

+

 struct nftnl_chain_list {

+

 	struct list_head list;

+	struct hlist_head name_hash[CHAIN_NAME_HSIZE];

 };

 EXPORT_SYMBOL(nftnl_chain_list_alloc);

 struct nftnl_chain_list *nftnl_chain_list_alloc(void)

 {

 	struct nftnl_chain_list *list;

+	int i;

 	list = calloc(1, sizeof(struct nftnl_chain_list));

 	if (list == NULL)

 		return NULL;

 	INIT_LIST_HEAD(&list->list);

+	for (i = 0; i < CHAIN_NAME_HSIZE; i++)

+		INIT_HLIST_HEAD(&list->name_hash[i]);

 	return list;

 }

@@ -1016,6 +1024,7 @@ void nftnl_chain_list_free(struct nftnl_chain_list *list)

 	list_for_each_entry_safe(r, tmp, &list->list, head) {

 		list_del(&r->head);

+		hlist_del(&r->hnode);

 		nftnl_chain_free(r);

 	}

 	xfree(list);

@@ -1027,15 +1036,31 @@ int nftnl_chain_list_is_empty(const struct nftnl_chain_list *list)

 	return list_empty(&list->list);

 }

+static uint32_t djb_hash(const char *key)

+{

+	uint32_t i, hash = 5381;

+

+	for (i = 0; i < strlen(key); i++)

+		hash = ((hash << 5) + hash) + key[i];

+

+	return hash;

+}

+

 EXPORT_SYMBOL(nftnl_chain_list_add);

 void nftnl_chain_list_add(struct nftnl_chain *r, struct nftnl_chain_list *list)

 {

+	int key = djb_hash(r->name) % CHAIN_NAME_HSIZE;

+

+	hlist_add_head(&r->hnode, &list->name_hash[key]);

 	list_add(&r->head, &list->list);

 }

 EXPORT_SYMBOL(nftnl_chain_list_add_tail);

 void nftnl_chain_list_add_tail(struct nftnl_chain *r, struct nftnl_chain_list *list)

 {

+	int key = djb_hash(r->name) % CHAIN_NAME_HSIZE;

+

+	hlist_add_head(&r->hnode, &list->name_hash[key]);

 	list_add_tail(&r->head, &list->list);

 }

@@ -1043,6 +1068,7 @@ EXPORT_SYMBOL(nftnl_chain_list_del);

 void nftnl_chain_list_del(struct nftnl_chain *r)

 {

 	list_del(&r->head);

+	hlist_del(&r->hnode);

 }

 EXPORT_SYMBOL(nftnl_chain_list_foreach);

@@ -1066,9 +1092,11 @@ struct nftnl_chain *

 nftnl_chain_list_lookup_byname(struct nftnl_chain_list *chain_list,

 			       const char *chain)

 {

+	int key = djb_hash(chain) % CHAIN_NAME_HSIZE;

 	struct nftnl_chain *c;

+	struct hlist_node *n;

-	list_for_each_entry(c, &chain_list->list, head) {

+	hlist_for_each_entry(c, n, &chain_list->name_hash[key], hnode) {

 		if (!strcmp(chain, c->name))

 			return c;

 	}

-- 

1.8.3.1