org.apache.flink.runtime.messages.Acknowledge Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.flink.runtime.messages;
import java.io.Serializable;
/**
* A generic acknowledgement message.
*/
public class Acknowledge implements Serializable {
private static final long serialVersionUID = 7808628311617273755L;
/** The singleton instance */
private static final Acknowledge INSTANCE = new Acknowledge();
/**
* Gets the singleton instance.
* @return The singleton instance.
*/
public static Acknowledge get() {
return INSTANCE;
}
// ------------------------------------------------------------------------
/** Private constructor to prevent instantiation */
private Acknowledge() {}
// ------------------------------------------------------------------------
@Override
public boolean equals(Object obj) {
return obj != null && obj.getClass() == Acknowledge.class;
}
@Override
public int hashCode() {
return 41;
}
@Override
public String toString() {
return getClass().getSimpleName();
}
/**
* Read resolve to preserve the singleton object property.
* (per best practices, this should have visibility 'protected')
*/
protected Object readResolve() throws java.io.ObjectStreamException {
return INSTANCE;
}
}