+/* The connection states have the following meanings:
+ *
+ * - S_VOID: No connection information is configured.
+ *
+ * - S_BACKOFF: Waiting for a period of time before reconnecting.
+ *
+ * - S_CONNECTING: A connection attempt is in progress and has not yet
+ * succeeded or failed.
+ *
+ * - S_ACTIVE: A connection has been established and appears to be healthy.
+ *
+ * - S_IDLE: A connection has been established but has been idle for some
+ * time. An echo request has been sent, but no reply has yet been
+ * received.
+ *
+ * - S_DISCONNECTED: An unreliable connection has disconnected and cannot be
+ * automatically retried.
+ */