org.apache.hadoop.hbase.regionserver.EmptyIndex.java Source code

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Here is the source code for org.apache.hadoop.hbase.regionserver.EmptyIndex.java

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/**
 * Copyright 2010 The Apache Software Foundation
 *
 * 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.hadoop.hbase.regionserver;

import org.apache.commons.lang.ArrayUtils;
import org.apache.hadoop.hbase.regionserver.idx.support.arrays.List;
import org.apache.hadoop.hbase.regionserver.idx.support.sets.IntSet;
import org.apache.hadoop.hbase.regionserver.idx.support.sets.IntSetBuilder;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.hbase.util.ClassSize;

/**
 * An empty index.
 */
public class EmptyIndex implements IdxIndex {

    private static final int HEAP_SIZE = ClassSize.align(ClassSize.OBJECT + ClassSize.REFERENCE + Bytes.SIZEOF_INT);

    private List<?> keyStore;
    private int numKeyValues;

    /**
     * Construct a new empty index with a given capacity. All sets genreated by
     * this empty index will be initiazlized using the provided capacity.
     *
     * @param keyStore the key store
     * @param capacity the capacity
     */
    EmptyIndex(List<?> keyStore, int capacity) {
        this.keyStore = keyStore;
        this.numKeyValues = capacity;
    }

    /**
     * {@inheritDoc}
     * <p/>
     * Returns an empty set.
     */
    @Override
    public IntSet lookup(byte[] probe) {
        return IntSetBuilder.newEmptyIntSet(numKeyValues);
    }

    /**
     * {@inheritDoc}
     * <p/>
     * Returns an empty set.
     */
    @Override
    public IntSet tail(byte[] probe, boolean inclusive) {
        return IntSetBuilder.newEmptyIntSet(numKeyValues);
    }

    /**
     * {@inheritDoc}
     * <p/>
     * Returns an empty set.
     */
    @Override
    public IntSet head(byte[] probe, boolean inclusive) {
        return IntSetBuilder.newEmptyIntSet(numKeyValues);
    }

    /**
     * {@inheritDoc}
     * <p/>
     * Returns an empty set.
     */
    @Override
    public IntSet all() {
        return IntSetBuilder.newEmptyIntSet(numKeyValues);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public String probeToString(byte[] bytes) {
        return ArrayUtils.toString(keyStore.fromBytes(bytes));
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public int size() {
        return 0;
    }

    @Override
    public long heapSize() {
        return HEAP_SIZE;
    }
}