org.hbasene.index.HBaseTermPositions.java Source code

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Here is the source code for org.hbasene.index.HBaseTermPositions.java

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/**
 * Copyright 2010 Karthik Kumar
 * 
 * 
 * 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.hbasene.index;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.NavigableMap;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hbase.client.Get;
import org.apache.hadoop.hbase.client.HTableInterface;
import org.apache.hadoop.hbase.client.HTablePool;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.lucene.index.Term;
import org.apache.lucene.index.TermEnum;
import org.apache.lucene.index.TermPositions;

import com.google.common.base.Function;

/**
 * Term Docs implementation for HBase.
 */
public class HBaseTermPositions implements TermPositions {

    @SuppressWarnings("unused")
    private static final Log LOG = LogFactory.getLog(HBaseTermPositions.class);

    /**
     * Functor to convert bytes to DocId
     */
    public static final Function<byte[], Long> BYTES_TO_DOCID = new Function<byte[], Long>() {

        @Override
        public Long apply(byte[] from) {
            return Bytes.toLong(from);
        }

    };

    private final HTableInterface table;

    private final HTablePool pool;

    /**
     * List of documents corresponding to the term docs under consideration.
     */
    private List<byte[]> documents;
    // TODO:WeakRef this and load on demand, if taken away, to save memory.

    /**
     * Current index into the documents array.
     */
    private int currentIndex;

    /**
     * Current row (field/text) of the term under consideration.
     */
    private byte[] currentRow;

    private int[] currentTermPositions;

    private int currentTermPositionIndex;

    /**
     * Encoder of the term positions in the underlying store.
     */
    private AbstractTermPositionsEncoder termPositionsEncoder;

    public HBaseTermPositions(final HBaseIndexReader reader,
            final AbstractTermPositionsEncoder termPositionsEncoder) throws IOException {
        this.pool = reader.getTablePool();
        this.table = this.pool.getTable(reader.getIndexName());
        this.termPositionsEncoder = termPositionsEncoder;
    }

    @Override
    public void close() throws IOException {
        this.documents.clear();
        this.currentIndex = 0;
        this.pool.putTable(table);
    }

    @Override
    public int doc() {
        return (int) Bytes.toLong(this.documents.get(this.currentIndex));
    }

    @Override
    public int freq() {
        return this.currentTermPositions.length;
    }

    @Override
    public boolean next() throws IOException {
        if (currentIndex < (this.documents.size() - 1)) {
            this.currentIndex++;
            resetTermPositions();
            return true;
        } else {
            return false;
        }
    }

    void resetTermPositions() throws IOException {
        Get get = new Get(this.currentRow);
        get.addColumn(HBaseneConstants.FAMILY_TERMVECTOR, this.documents.get(this.currentIndex));
        Result result = table.get(get);
        byte[] tfArray = result.getValue(HBaseneConstants.FAMILY_TERMVECTOR, this.documents.get(this.currentIndex));
        this.currentTermPositionIndex = 0;
        this.currentTermPositions = this.termPositionsEncoder.decode(tfArray);

    }

    @Override
    public int read(int[] docs, int[] freqs) throws IOException {
        int count = 0;
        for (int i = 0; i < docs.length; ++i) {
            if (next()) {
                docs[i] = this.doc();
                freqs[i] = this.freq();
                ++count;
            } else {
                break;
            }
        }
        return count;
    }

    @Override
    public void seek(Term term) throws IOException {
        final String rowKey = term.field() + "/" + term.text();
        this.currentRow = Bytes.toBytes(rowKey);
        Result result = this.getRowWithTermVectors();
        NavigableMap<byte[], byte[]> map = result.getFamilyMap(HBaseneConstants.FAMILY_TERMVECTOR);

        this.documents = new ArrayList<byte[]>(map.keySet());
        this.currentIndex = -1;
    }

    Result getRowWithTermVectors() throws IOException {
        Get get = new Get(this.currentRow);
        get.addFamily(HBaseneConstants.FAMILY_TERMVECTOR);
        return this.table.get(get);
    }

    @Override
    public void seek(TermEnum termEnum) throws IOException {
        seek(termEnum.term());
    }

    @Override
    public boolean skipTo(int target) throws IOException {
        // TODO: Should the starting Index of the loop be 0 or currentIndex ?
        for (int i = 0; i < this.documents.size(); ++i) {
            if (Bytes.toLong(this.documents.get(i)) >= target) {
                currentIndex = i;
                return true;
            }
        }
        return false;
    }

    @Override
    public byte[] getPayload(byte[] data, int offset) throws IOException {
        return null;
    }

    @Override
    public int getPayloadLength() {
        return 0;
    }

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

    @Override
    public int nextPosition() throws IOException {
        return this.currentTermPositions[this.currentTermPositionIndex++];
    }
}