+/*
+ * Copyright (c) 2020 PANTHEON.tech, s.r.o. and others. All rights reserved.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v1.0 which accompanies this distribution,
+ * and is available at http://www.eclipse.org/legal/epl-v10.html
+ */
+package org.opendaylight.controller.cluster.raft.messages;
+
+/**
+ * An instance of a {@link Payload} class is meant to be used as the Payload for {@link AppendEntries}.
+ *
+ * <p>
+ * When an actor which is derived from RaftActor attempts to persistData it must pass an instance of the Payload class.
+ * Similarly when state needs to be applied to the derived RaftActor it will be passed an instance of the Payload class.
+ */
+public abstract class Payload {
+ /**
+ * Return the estimate of in-memory size of this payload.
+ *
+ * @return An estimate of the in-memory size of this payload.
+ */
+ public abstract int size();
+}