com.mongodb.hadoop.mapred.input.MongoInputSplit.java Source code

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Here is the source code for com.mongodb.hadoop.mapred.input.MongoInputSplit.java

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// MongoInputSplit.java
/*
 * Copyright 2010 10gen Inc.
 * 
 * Licensed 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.mongodb.hadoop.mapred.input;

import com.mongodb.*;
import com.mongodb.hadoop.util.*;
import com.mongodb.util.*;
import org.apache.commons.logging.*;
import org.apache.hadoop.io.*;
import org.apache.hadoop.mapred.*;

import java.io.*;
import java.util.*;

@SuppressWarnings("deprecation")
public class MongoInputSplit implements Writable, InputSplit {

    public MongoInputSplit(MongoURI inputURI, DBObject query, DBObject fields, DBObject sort, int limit, int skip) {
        log.info("Creating a new MongoInputSplit for MongoURI '" + inputURI + "', query: '" + query
                + "', fieldSpec: '" + fields + "', sort: '" + sort + "', limit: " + limit + ", skip: " + skip
                + " .");
        _mongoURI = inputURI;
        _querySpec = query;
        _fieldSpec = fields;
        _sortSpec = sort;
        _limit = limit;
        _skip = skip;
        getCursor();
    }

    public MongoInputSplit(com.mongodb.hadoop.input.MongoInputSplit split) {
        this(split.getMongoURI(), split.getQuerySpec(), split.getFieldSpec(), split.getSortSpec(), split.getLimit(),
                split.getSkip());
    }

    /**
     * This is supposed to return the size of the split in bytes, but for now, for sanity sake we return the # of docs
     * in the split instead.
     *
     * @return
     */
    @Override
    public long getLength() {
        return Long.MAX_VALUE;
    }

    @Override
    public String[] getLocations() {
        return _mongoURI.getHosts().toArray(new String[_mongoURI.getHosts().size()]);
    }

    /**
     * Serialize the Split instance
     */

    public void write(DataOutput out) throws IOException {
        out.writeUTF(_mongoURI.toString());
        out.writeUTF(JSON.serialize(_querySpec));
        out.writeUTF(JSON.serialize(_fieldSpec));
        out.writeUTF(JSON.serialize(_sortSpec));
        out.writeInt(_limit);
        out.writeInt(_skip);
    }

    @Override
    public void readFields(DataInput in) throws IOException {
        _mongoURI = new MongoURI(in.readUTF());
        _querySpec = (DBObject) JSON.parse(in.readUTF());
        _fieldSpec = (DBObject) JSON.parse(in.readUTF());
        _sortSpec = (DBObject) JSON.parse(in.readUTF());
        _limit = in.readInt();
        _skip = in.readInt();
        getCursor();

        if (log.isDebugEnabled()) {
            log.debug("Deserialized MongoInputSplit ... { length = " + getLength() + ", locations = "
                    + Arrays.toString(getLocations()) + ", query = " + _querySpec + ", fields = " + _fieldSpec
                    + ", sort = " + _sortSpec + ", limit = " + _limit + ", skip = " + _skip + "}");
        }
    }

    public DBCursor getCursor() {
        // Return the cursor with the split's query, etc. already slotted in for
        // them.
        // todo - support limit/skip
        if (_cursor == null) {
            _cursor = MongoConfigUtil.getCollection(_mongoURI).find(_querySpec, _fieldSpec).sort(_sortSpec);
            _cursor.slaveOk();
        }

        return _cursor;
    }

    @Override
    public String toString() {
        return "MongoInputSplit{URI=" + _mongoURI + ", query=" + _querySpec + '}';
    }

    public MongoInputSplit() {
    }

    private MongoURI _mongoURI;
    private DBObject _querySpec;
    private DBObject _fieldSpec;
    private DBObject _sortSpec;
    private int _limit = 0;
    private int _skip = 0;
    private long _length = -1;
    private transient DBCursor _cursor;

    private static final Log log = LogFactory.getLog(MongoInputSplit.class);

}