From: Willy Tarreau <w@1wt.eu>
Date: Mon, 14 Nov 2022 16:33:02 +0000 (+0100)
Subject: CLEANUP: stick-table: remove the unused table->exp_next
X-Git-Tag: v2.7-dev9~71
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=63427140527bcd0e45fe4a7a574cc5db0b5141e6;p=thirdparty%2Fhaproxy.git

CLEANUP: stick-table: remove the unused table->exp_next

The ->exp_next field of the stick-table was probably useful in 1.5 but
it currently only carries a copy of what the future value of the table's
task's expire value will be, while it's systematically copied over there
immediately after being assigned. As such it provides exactly a local
variable. Let's remove it, as it costs atomic operations.
---

diff --git a/include/haproxy/stick_table-t.h b/include/haproxy/stick_table-t.h
index 54b27bb4f5..cc9fe93576 100644
--- a/include/haproxy/stick_table-t.h
+++ b/include/haproxy/stick_table-t.h
@@ -185,7 +185,6 @@ struct stktable {
 	unsigned int size;        /* maximum number of sticky sessions in table */
 	unsigned int current;     /* number of sticky sessions currently in table */
 	int nopurge;              /* if non-zero, don't purge sticky sessions when full */
-	int exp_next;             /* next expiration date (ticks) */
 	int expire;               /* time to live for sticky sessions (milliseconds) */
 	int data_size;            /* the size of the data that is prepended *before* stksess */
 	int data_ofs[STKTABLE_DATA_TYPES]; /* negative offsets of present data types, or 0 if absent */
diff --git a/src/stick_table.c b/src/stick_table.c
index 77a5ba5231..61e63b8ae6 100644
--- a/src/stick_table.c
+++ b/src/stick_table.c
@@ -548,19 +548,10 @@ void stktable_requeue_exp(struct stktable *t, const struct stksess *ts)
 	if (!t->expire)
 		return;
 
-	/* set both t->exp_next and the task's expire to the newest
-	 * expiration date.
-	 */
-	old_exp = HA_ATOMIC_LOAD(&t->exp_next);
-	do {
-		new_exp = tick_first(expire, old_exp);
-	} while (new_exp != old_exp &&
-		 !HA_ATOMIC_CAS(&t->exp_next, &old_exp, new_exp) &&
-		 __ha_cpu_relax());
-
+	/* set the task's expire to the newest expiration date. */
 	old_exp = HA_ATOMIC_LOAD(&t->exp_task->expire);
 	do {
-		new_exp = HA_ATOMIC_LOAD(&t->exp_next);
+		new_exp = tick_first(expire, old_exp);
 	} while (new_exp != old_exp &&
 		 !HA_ATOMIC_CAS(&t->exp_task->expire, &old_exp, new_exp) &&
 		 __ha_cpu_relax());
@@ -664,6 +655,7 @@ static int stktable_trash_expired(struct stktable *t)
 	struct stksess *ts;
 	struct eb32_node *eb;
 	int looped = 0;
+	int exp_next;
 
 	HA_RWLOCK_WRLOCK(STK_TABLE_LOCK, &t->lock);
 	eb = eb32_lookup_ge(&t->exps, now_ms - TIMER_LOOK_BACK);
@@ -685,7 +677,7 @@ static int stktable_trash_expired(struct stktable *t)
 
 		if (likely(tick_is_lt(now_ms, eb->key))) {
 			/* timer not expired yet, revisit it later */
-			t->exp_next = eb->key;
+			exp_next = eb->key;
 			goto out_unlock;
 		}
 
@@ -718,10 +710,10 @@ static int stktable_trash_expired(struct stktable *t)
 	}
 
 	/* We have found no task to expire in any tree */
-	t->exp_next = TICK_ETERNITY;
+	exp_next = TICK_ETERNITY;
 out_unlock:
 	HA_RWLOCK_WRUNLOCK(STK_TABLE_LOCK, &t->lock);
-	return t->exp_next;
+	return exp_next;
 }
 
 /*
@@ -748,7 +740,6 @@ int stktable_init(struct stktable *t)
 
 		t->pool = create_pool("sticktables", sizeof(struct stksess) + round_ptr_size(t->data_size) + t->key_size, MEM_F_SHARED);
 
-		t->exp_next = TICK_ETERNITY;
 		if ( t->expire ) {
 			t->exp_task = task_new_anywhere();
 			if (!t->exp_task)