org.apache.flink.runtime.state.PriorityComparator 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.state;
/**
* This interface works similar to {@link Comparable} and is used to prioritize between two objects. The main difference
* between this interface and {@link Comparable} is it is not require to follow the usual contract between that
* {@link Comparable#compareTo(Object)} and {@link Object#equals(Object)}. The contract of this interface is:
* When two objects are equal, they indicate the same priority, but indicating the same priority does not require that
* both objects are equal.
*
* @param type of the compared objects.
*/
@FunctionalInterface
public interface PriorityComparator {
PriorityComparator> FOR_PRIORITY_COMPARABLE_OBJECTS = PriorityComparable::comparePriorityTo;
/**
* Compares two objects for priority. Returns a negative integer, zero, or a positive integer as the first
* argument has lower, equal to, or higher priority than the second.
* @param left left operand in the comparison by priority.
* @param right left operand in the comparison by priority.
* @return a negative integer, zero, or a positive integer as the first argument has lower, equal to, or higher
* priority than the second.
*/
int comparePriority(T left, T right);
@SuppressWarnings("unchecked")
static > PriorityComparator forPriorityComparableObjects() {
return (PriorityComparator) FOR_PRIORITY_COMPARABLE_OBJECTS;
}
}