test/unit/org/apache/cassandra/utils/MergeIteratorTest.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
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*/
package org.apache.cassandra.utils;

import java.util.Arrays;
import java.util.Iterator;

import org.apache.cassandra.utils.AbstractIterator;
import com.google.common.collect.Iterators;
import com.google.common.collect.Ordering;
import org.junit.Before;
import org.junit.Test;

public class MergeIteratorTest
{
    CLI<String> all = null, cat = null, a = null, b = null, c = null, d = null;

    @Before
    public void clear()
    {
        all = new CLI("1", "2", "3", "3", "4", "5", "6", "7", "8", "8", "9");
        cat = new CLI("1", "2", "33", "4", "5", "6", "7", "88", "9");
        a = new CLI("1", "3", "5", "8");
        b = new CLI("2", "4", "6");
        c = new CLI("3", "7", "8", "9");
        d = new CLI();
    }

    /** Test that duplicate values are concatted. */
    @Test
    public void testManyToOne() throws Exception
    {
        MergeIterator.Reducer<String,String> reducer = new MergeIterator.Reducer<String,String>()
        {
            String concatted = "";

            @Override
            public void reduce(int idx, String current)
            {
                concatted += current;
            }

            public String getReduced()
            {
                String tmp = concatted;
                concatted = "";
                return tmp;
            }
        };
        IMergeIterator<String,String> smi = MergeIterator.get(Arrays.asList(a, b, c, d),
                Ordering.<String>natural(),
                reducer);
        assert Iterators.elementsEqual(cat, smi);
        smi.close();
        assert a.closed && b.closed && c.closed && d.closed;
    }

    // closeable list iterator
    public static class CLI<E> extends AbstractIterator<E> implements CloseableIterator<E>
    {
        Iterator<E> iter;
        boolean closed = false;
        public CLI(E... items)
        {
            this.iter = Arrays.asList(items).iterator();
        }

        protected E computeNext()
        {
            if (!iter.hasNext()) return endOfData();
            return iter.next();
        }

        public void close()
        {
            assert !this.closed;
            this.closed = true;
        }
    }
}