Add an option to autobalance a HA cluster automatically

src/libcharon/plugins/ha/ha_segments.c

@@ -90,6 +90,11 @@ struct private_ha_segments_t {
 	 * Timeout for heartbeats received from other node
 	 */
 	int heartbeat_timeout;
+
+	/**
+	 * Interval to check for autobalance, 0 to disable
+	 */
+	int autobalance;
 };
 
 /**
@@ -374,6 +379,54 @@ static void start_heartbeat(private_ha_segments_t *this)
 			this, NULL, (callback_job_cancel_t)return_false, JOB_PRIO_CRITICAL));
 }
 
+/**
+ * Take a segment if we are handling less than half of segments
+ */
+static job_requeue_t autobalance(private_ha_segments_t *this)
+{
+	int i, active = 0;
+
+	this->mutex->lock(this->mutex);
+
+	for (i = 1; i <= this->count; i++)
+	{
+		if (this->active & SEGMENTS_BIT(i))
+		{
+			active++;
+		}
+	}
+	if (active < this->count / 2)
+	{
+		for (i = 1; i <= this->count; i++)
+		{
+			if (!(this->active & SEGMENTS_BIT(i)))
+			{
+				DBG1(DBG_CFG, "autobalancing HA (%d/%d active), taking %d",
+					 active, this->count, i);
+				enable_disable(this, i, TRUE, TRUE);
+				/* we claim only one in each interval */
+				break;
+			}
+		}
+	}
+
+	this->mutex->unlock(this->mutex);
+
+	return JOB_RESCHEDULE(this->autobalance);
+}
+
+/**
+ * Schedule autobalancing
+ */
+static void start_autobalance(private_ha_segments_t *this)
+{
+	DBG1(DBG_CFG, "scheduling HA autobalance every %ds", this->autobalance);
+	lib->scheduler->schedule_job(lib->scheduler,
+		(job_t*)callback_job_create_with_prio((callback_job_cb_t)autobalance,
+			this, NULL, (callback_job_cancel_t)return_false, JOB_PRIO_CRITICAL),
+		this->autobalance);
+}
+
 METHOD(ha_segments_t, is_active, bool,
 	private_ha_segments_t *this, u_int segment)
 {
@@ -421,6 +474,8 @@ ha_segments_t *ha_segments_create(ha_socket_t *socket, ha_kernel_t *kernel,
 		.heartbeat_timeout = lib->settings->get_int(lib->settings,
 				"%s.plugins.ha.heartbeat_timeout", DEFAULT_HEARTBEAT_TIMEOUT,
 				charon->name),
+		.autobalance = lib->settings->get_int(lib->settings,
+				"%s.plugins.ha.autobalance", 0, charon->name),
 	);
 
 	if (monitor)
@@ -430,6 +485,10 @@ ha_segments_t *ha_segments_create(ha_socket_t *socket, ha_kernel_t *kernel,
 		start_heartbeat(this);
 		start_watchdog(this);
 	}
+	if (this->autobalance)
+	{
+		start_autobalance(this);
+	}
 
 	return &this->public;
 }