pulsar-functions/java-examples/src/main/java/org/apache/pulsar/functions/api/examples/AddWindowFunction.java

/**
 * 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.pulsar.functions.api.examples;

import lombok.extern.slf4j.Slf4j;

import java.util.Collection;
import java.util.function.Function;

/**
 * Example Function that acts on a window of tuples at a time rather than per tuple basis.
 */
@Slf4j
public class AddWindowFunction implements Function <Collection<Integer>, Integer> {
    @Override
    public Integer apply(Collection<Integer> integers) {
        return integers.stream().reduce(0, (x, y) -> x + y);
    }
}