From 013a3b226a0fa5f7a8469bae736150cbf2d092c4 Mon Sep 17 00:00:00 2001

From: Phil Sutter <psutter@redhat.com>

Date: Fri, 24 Jun 2022 16:02:59 +0200

Subject: [PATCH] intervals: Do not sort cached set elements over and over

 again

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1917398

Upstream Status: nftables commit 59e3a59221fb8

commit 59e3a59221fb81c289a0868a85140dd452fb1c30

Author: Phil Sutter <phil@nwl.cc>

Date:   Thu Jun 16 10:56:12 2022 +0200

    intervals: Do not sort cached set elements over and over again

    When adding element(s) to a non-empty set, code merged the two lists and

    sorted the result. With many individual 'add element' commands this

    causes substantial overhead. Make use of the fact that

    existing_set->init is sorted already, sort only the list of new elements

    and use list_splice_sorted() to merge the two sorted lists.

    Add set_sort_splice() and use it for set element overlap detection and

    automerge.

    A test case adding ~25k elements in individual commands completes in

    about 1/4th of the time with this patch applied.

    Joint work with Pablo.

    Fixes: 3da9643fb9ff9 ("intervals: add support to automerge with kernel elements")

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

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

Signed-off-by: Phil Sutter <psutter@redhat.com>

---

 include/expression.h |  1 +

 src/intervals.c      | 46 +++++++++++++++++++++-----------------------

 src/mergesort.c      |  2 +-

 3 files changed, 24 insertions(+), 25 deletions(-)

diff --git a/include/expression.h b/include/expression.h

index 53194c9..cf7319b 100644

--- a/include/expression.h

+++ b/include/expression.h

@@ -481,6 +481,7 @@ extern struct expr *compound_expr_alloc(const struct location *loc,

 extern void compound_expr_add(struct expr *compound, struct expr *expr);

 extern void compound_expr_remove(struct expr *compound, struct expr *expr);

 extern void list_expr_sort(struct list_head *head);

+extern void list_splice_sorted(struct list_head *list, struct list_head *head);

 extern struct expr *concat_expr_alloc(const struct location *loc);

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

index e203413..dcc06d1 100644

--- a/src/intervals.c

+++ b/src/intervals.c

@@ -118,6 +118,26 @@ static bool merge_ranges(struct set_automerge_ctx *ctx,

 	return false;

 }

+static void set_sort_splice(struct expr *init, struct set *set)

+{

+	struct set *existing_set = set->existing_set;

+

+	set_to_range(init);

+	list_expr_sort(&init->expressions);

+

+	if (!existing_set)

+		return;

+

+	if (existing_set->init) {

+		set_to_range(existing_set->init);

+		list_splice_sorted(&existing_set->init->expressions,

+				   &init->expressions);

+		init_list_head(&existing_set->init->expressions);

+	} else {

+		existing_set->init = set_expr_alloc(&internal_location, set);

+	}

+}

+

 static void setelem_automerge(struct set_automerge_ctx *ctx)

 {

 	struct expr *i, *next, *prev = NULL;

@@ -222,18 +242,7 @@ int set_automerge(struct list_head *msgs, struct cmd *cmd, struct set *set,

 		return 0;

 	}

-	if (existing_set) {

-		if (existing_set->init) {

-			list_splice_init(&existing_set->init->expressions,

-					 &init->expressions);

-		} else {

-			existing_set->init = set_expr_alloc(&internal_location,

-							    set);

-		}

-	}

-

-	set_to_range(init);

-	list_expr_sort(&init->expressions);

+	set_sort_splice(init, set);

 	ctx.purge = set_expr_alloc(&internal_location, set);

@@ -591,18 +600,7 @@ int set_overlap(struct list_head *msgs, struct set *set, struct expr *init)

 	struct expr *i, *n, *clone;

 	int err;

-	if (existing_set) {

-		if (existing_set->init) {

-			list_splice_init(&existing_set->init->expressions,

-					 &init->expressions);

-		} else {

-			existing_set->init = set_expr_alloc(&internal_location,

-							    set);

-		}

-	}

-

-	set_to_range(init);

-	list_expr_sort(&init->expressions);

+	set_sort_splice(init, set);

 	err = setelem_overlap(msgs, set, init);

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

index 8e6aac5..dca7142 100644

--- a/src/mergesort.c

+++ b/src/mergesort.c

@@ -70,7 +70,7 @@ static int expr_msort_cmp(const struct expr *e1, const struct expr *e2)

 	return ret;

 }

-static void list_splice_sorted(struct list_head *list, struct list_head *head)

+void list_splice_sorted(struct list_head *list, struct list_head *head)

 {

 	struct list_head *h = head->next;

 	struct list_head *l = list->next;

-- 

2.36.1