From 26c4f15080663a12006abf8539ebf28bb223e6d9 Mon Sep 17 00:00:00 2001

From: Phil Sutter <psutter@redhat.com>

Date: Mon, 7 Dec 2020 18:29:15 +0100

Subject: [PATCH] json: echo: Speedup seqnum_to_json()

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1900565

Upstream Status: nftables commit 389a0e1edc89a

commit 389a0e1edc89a4048a272e569d3349b1d43bc567

Author: Phil Sutter <phil@nwl.cc>

Date:   Fri Nov 20 20:01:59 2020 +0100

    json: echo: Speedup seqnum_to_json()

    Derek Dai reports:

    "If there are a lot of command in JSON node, seqnum_to_json() will slow

    down application (eg: firewalld) dramatically since it iterate whole

    command list every time."

    He sent a patch implementing a lookup table, but we can do better: Speed

    this up by introducing a hash table to store the struct json_cmd_assoc

    objects in, taking their netlink sequence number as key.

    Quickly tested restoring a ruleset containing about 19k rules:

    | # time ./before/nft -jeaf large_ruleset.json >/dev/null

    | 4.85user 0.47system 0:05.48elapsed 97%CPU (0avgtext+0avgdata 69732maxresident)k

    | 0inputs+0outputs (15major+16937minor)pagefaults 0swaps

    | # time ./after/nft -jeaf large_ruleset.json >/dev/null

    | 0.18user 0.44system 0:00.70elapsed 89%CPU (0avgtext+0avgdata 68484maxresident)k

    | 0inputs+0outputs (15major+16645minor)pagefaults 0swaps

    Bugzilla: https://bugzilla.netfilter.org/show_bug.cgi?id=1479

    Reported-by: Derek Dai <daiderek@gmail.com>

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

---

 src/parser_json.c | 28 ++++++++++++++++++----------

 1 file changed, 18 insertions(+), 10 deletions(-)

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

index ddc694f..107dc38 100644

--- a/src/parser_json.c

+++ b/src/parser_json.c

@@ -3646,42 +3646,50 @@ static int json_verify_metainfo(struct json_ctx *ctx, json_t *root)

 }

 struct json_cmd_assoc {

-	struct json_cmd_assoc *next;

+	struct hlist_node hnode;

 	const struct cmd *cmd;

 	json_t *json;

 };

-static struct json_cmd_assoc *json_cmd_list = NULL;

+#define CMD_ASSOC_HSIZE		512

+static struct hlist_head json_cmd_assoc_hash[CMD_ASSOC_HSIZE];

 static void json_cmd_assoc_free(void)

 {

 	struct json_cmd_assoc *cur;

+	struct hlist_node *pos, *n;

+	int i;

-	while (json_cmd_list) {

-		cur = json_cmd_list;

-		json_cmd_list = cur->next;

-		free(cur);

+	for (i = 0; i < CMD_ASSOC_HSIZE; i++) {

+		hlist_for_each_entry_safe(cur, pos, n,

+					  &json_cmd_assoc_hash[i], hnode)

+			free(cur);

 	}

 }

 static void json_cmd_assoc_add(json_t *json, const struct cmd *cmd)

 {

 	struct json_cmd_assoc *new = xzalloc(sizeof *new);

+	int key = cmd->seqnum % CMD_ASSOC_HSIZE;

-	new->next	= json_cmd_list;

 	new->json	= json;

 	new->cmd	= cmd;

-	json_cmd_list	= new;

+

+	hlist_add_head(&new->hnode, &json_cmd_assoc_hash[key]);

 }

 static json_t *seqnum_to_json(const uint32_t seqnum)

 {

-	const struct json_cmd_assoc *cur;

+	int key = seqnum % CMD_ASSOC_HSIZE;

+	struct json_cmd_assoc *cur;

+	struct hlist_node *n;

-	for (cur = json_cmd_list; cur; cur = cur->next) {

+

+	hlist_for_each_entry(cur, n, &json_cmd_assoc_hash[key], hnode) {

 		if (cur->cmd->seqnum == seqnum)

 			return cur->json;

 	}

+

 	return NULL;

 }

-- 

1.8.3.1