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/*
 * 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.streaming.runtime.partitioner;

import org.apache.flink.annotation.Internal;
import org.apache.flink.runtime.io.network.api.writer.SubtaskStateMapper;
import org.apache.flink.runtime.plugable.SerializationDelegate;
import org.apache.flink.streaming.runtime.streamrecord.StreamRecord;

import java.util.Random;

/**
 * Partitioner that distributes the data equally by selecting one output channel randomly.
 *
 * @param  Type of the Tuple
 */
@Internal
public class ShufflePartitioner extends StreamPartitioner {
    private static final long serialVersionUID = 1L;

    private Random random = new Random();

    @Override
    public int selectChannel(SerializationDelegate> record) {
        return random.nextInt(numberOfChannels);
    }

    @Override
    public SubtaskStateMapper getDownstreamSubtaskStateMapper() {
        return SubtaskStateMapper.ROUND_ROBIN;
    }

    @Override
    public StreamPartitioner copy() {
        return new ShufflePartitioner();
    }

    @Override
    public boolean isPointwise() {
        return false;
    }

    @Override
    public String toString() {
        return "SHUFFLE";
    }
}