/*
 * Copyright 2017 HugeGraph Authors
 *
 * 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 com.baidu.hugegraph.computer.core.sort.flusher;

import java.io.IOException;
import java.util.Iterator;

import org.apache.commons.lang.NotImplementedException;

import com.baidu.hugegraph.computer.core.combiner.PointerCombiner;
import com.baidu.hugegraph.computer.core.io.RandomAccessOutput;
import com.baidu.hugegraph.computer.core.store.entry.KvEntry;

public interface InnerSortFlusher {

    /**
     * Flush result to this output.
     */
    default RandomAccessOutput output() {
        throw new NotImplementedException();
    }

    /**
     * Combine entries with the same key.
     */
    default PointerCombiner combiner() {
        throw new NotImplementedException();
    }

    /**
     * Combine the list of inputValues, and write the combined result length and
     * results to output.
     */
    void flush(Iterator<KvEntry> entries) throws IOException;
}