com.hazelcast.core.MembershipEvent Maven / Gradle / Ivy
/*
* Copyright (c) 2008-2016, 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.core;
import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
import java.util.EventObject;
import java.util.Set;
import static java.lang.String.format;
/**
* Membership event fired when a new member is added to the cluster and/or when a member leaves the cluster
* or when there is a member attribute change via {@link Member#setBooleanAttribute(String, boolean)}
* and similar methods.
*
* Warning: If the event is triggered by a member attribute change then {@link #members} is null!
*
* @see MembershipListener
*/
@SuppressFBWarnings("SE_BAD_FIELD")
public class MembershipEvent extends EventObject {
/**
* This event type is fired when a new member joins the cluster.
*/
public static final int MEMBER_ADDED = 1;
/**
* This event type is fired if a member left the cluster or was decided to be
* unresponsive by other members for a extended time.
*/
public static final int MEMBER_REMOVED = 2;
/**
* This event type is fired if a member attribute has been changed or removed.
*
* @since 3.2
*/
public static final int MEMBER_ATTRIBUTE_CHANGED = 5;
private static final long serialVersionUID = -2010865371829087371L;
private final Member member;
private final int eventType;
private final Set members;
public MembershipEvent(Cluster cluster, Member member, int eventType, Set members) {
super(cluster);
this.member = member;
this.eventType = eventType;
this.members = members;
}
/**
* Returns a consistent view of the the members immediately after this MembershipEvent has been processed. If a
* member is removed, the returned set will not include this member. If a member is added, it will include
* this member.
*
* The problem with calling the {@link com.hazelcast.core.Cluster#getMembers()} method is that the content could already
* have changed while processing this event, so it becomes very difficult to write a deterministic algorithm since
* you cannot get a deterministic view of the members. This method solves that problem.
*
* The set is immutable and ordered. For more information see {@link com.hazelcast.core.Cluster#getMembers()}.
*
* @return the members at the moment after this event.
*/
public Set getMembers() {
return members;
}
/**
* Returns the cluster of the event.
*
* @return the current cluster instance
*/
public Cluster getCluster() {
return (Cluster) getSource();
}
/**
* Returns the membership event type;
* #MEMBER_ADDED
* #MEMBER_REMOVED
* #MEMBER_ATTRIBUTE_CHANGED
*
* @return the membership event type
*/
public int getEventType() {
return eventType;
}
/**
* Returns the removed or added member.
*
* @return member which is removed or added
*/
public Member getMember() {
return member;
}
@Override
public String toString() {
String type;
switch (eventType) {
case MEMBER_ADDED:
type = "added";
break;
case MEMBER_REMOVED:
type = "removed";
break;
case MEMBER_ATTRIBUTE_CHANGED:
type = "attributed_changes";
break;
default:
throw new IllegalStateException();
}
return format("MembershipEvent {member=%s,type=%s}", member, type);
}
}