/*
* Copyright (c) 2008-2017, Hazelcast, Inc. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.hazelcast.internal.cluster;
import com.hazelcast.core.Cluster;
import com.hazelcast.version.Version;
/**
* Listeners interested in acting upon cluster version update should implement this interface.
* Services registered with the Hazelcast {@link com.hazelcast.spi.impl.servicemanager.ServiceManager} which implement this
* interface do not have have to register themselves, as their {@link #onClusterVersionChange(Version)} method will be
* invoked automatically.
*
* Other listeners have to register themselves with {@link com.hazelcast.instance.NodeExtension#registerListener(Object)}.
* Upon registration, the listener's {@link #onClusterVersionChange(Version)} method will be invoked once with the current
* value of the cluster version.
*
* @see Cluster#getClusterVersion()
* @see ClusterService#changeClusterVersion(Version)
* @since 3.8
*/
public interface ClusterVersionListener {
/**
* Invoked on registered listeners after the new cluster version has been applied. Listeners are executed synchronously
* immediately after {@code ClusterStateManager#version} has been updated and while the cluster service lock
* {@code ClusterServiceImpl#lock} is still locked, as part of the commit phase of the transaction changing
* the cluster version. Unhandled exceptions from listeners implementation will break the new version commit and a slow
* implementation will stall the system and may cause a transaction timeout.
* If new cluster version is {@code null} and property
* {@link com.hazelcast.spi.properties.GroupProperty#INIT_CLUSTER_VERSION} is set, the version set by this property
* will be provided as argument to the listener. If neither are set, running node's codebase version will be used.
*
* @param newVersion the new version
*/
void onClusterVersionChange(Version newVersion);
}