com.alibaba.nacos.common.notify.Event Maven / Gradle / Ivy
/*
* Copyright 1999-2018 Alibaba Group Holding Ltd.
*
* 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.alibaba.nacos.common.notify;
import java.io.Serializable;
import java.util.concurrent.atomic.AtomicLong;
/**
* An abstract class for event.
*
* @author liaochuntao
* @author zongtanghu
*/
@SuppressWarnings({"PMD.AbstractClassShouldStartWithAbstractNamingRule"})
public abstract class Event implements Serializable {
private static final long serialVersionUID = -3731383194964997493L;
private static final AtomicLong SEQUENCE = new AtomicLong(0);
private final long sequence = SEQUENCE.getAndIncrement();
/**
* Event sequence number, which can be used to handle the sequence of events.
*
* @return sequence num, It's best to make sure it's monotone.
*/
public long sequence() {
return sequence;
}
/**
* Event scope.
*
* @return event scope, return null if for all scope
*/
public String scope() {
return null;
}
/**
* Whether is plugin event. If so, the event can be dropped when no publish and subscriber without any hint. Default
* false
*
* @return {@code true} if is plugin event, otherwise {@code false}
*/
public boolean isPluginEvent() {
return false;
}
}