MINOR: rhttp: add count of active conns per thread

Add a new member <nb_rhttp_conns> in thread_ctx structure. Its purpose
is to count the current number of opened reverse HTTP connections
regarding from their listeners membership.

This patch will be useful to support multi-thread for active reverse
HTTP, in order to select the less loaded thread.

Note that despite access to <nb_rhttp_conns> are only done by the
current thread, atomic operations are used. This is because once
multi-thread support will be added, external threads will also retrieve
values from others.

include/haproxy/tinfo-t.h

@@ -141,6 +141,7 @@ struct thread_ctx {
 	struct list quic_conns;             /* list of active quic-conns attached to this thread */
 	struct list quic_conns_clo;         /* list of closing quic-conns attached to this thread */
 	struct list queued_checks;          /* checks waiting for a connection slot */
+	unsigned int nb_rhttp_conns;        /* count of current conns used for active reverse HTTP */
 
 	ALWAYS_ALIGN(2*sizeof(void*));
 	struct list tasklets[TL_CLASSES];   /* tasklets (and/or tasks) to run, by class */

src/connection.c

@@ -592,7 +592,12 @@ void conn_free(struct connection *conn)
 	if (conn_reverse_in_preconnect(conn)) {
 		struct listener *l = conn_active_reverse_listener(conn);
 		rhttp_notify_preconn_err(l);
+		HA_ATOMIC_DEC(&th_ctx->nb_rhttp_conns);
 	}
+	else if (conn->flags & CO_FL_REVERSED) {
+		HA_ATOMIC_DEC(&th_ctx->nb_rhttp_conns);
+	}
+
 
 	conn_force_unsubscribe(conn);
 	pool_free(pool_head_connection, conn);

src/proto_rhttp.c

@@ -56,6 +56,8 @@ static struct connection *new_reverse_conn(struct listener *l, struct server *sr
 	if (!conn)
 		goto err;
 
+	HA_ATOMIC_INC(&th_ctx->nb_rhttp_conns);
+
 	conn_set_reverse(conn, &l->obj_type);
 
 	if (alloc_bind_address(&bind_addr, srv, srv->proxy, NULL) != SRV_STATUS_OK)
@@ -376,3 +378,14 @@ int rhttp_accepting_conn(const struct receiver *rx)
 }
 
 INITCALL1(STG_REGISTER, protocol_register, &proto_rhttp);
+
+/* perform minimal intializations */
+static void init_rhttp()
+{
+	int i;
+
+	for (i = 0; i < MAX_THREADS; i++)
+		ha_thread_ctx[i].nb_rhttp_conns = 0;
+}
+
+INITCALL0(STG_PREPARE, init_rhttp);