datamine.storage.recordbuffers.RecordBuffer.java Source code

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Here is the source code for datamine.storage.recordbuffers.RecordBuffer.java

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/**
 * Copyright (C) 2016 Turn Inc. (yan.qi@turn.com)
 *
 * 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 datamine.storage.recordbuffers;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.nio.ByteBuffer;

import org.apache.hadoop.io.Writable;

import com.google.common.base.Preconditions;

/**
 * The implementation of storage for a record. 
 * 
 * @author yqi
 * @date Jul 31, 2014
 */
public class RecordBuffer implements Writable {

    /**
     * Size of buffer   
     */
    private int recordByteBufferSize = 0;

    /**
     * The buffer holding all records
     */
    private ByteBuffer recordByteBuffer = null;

    /**
     * This is a dummy constructor for Hadoop MR job
     */
    public RecordBuffer() {

    }

    public RecordBuffer(RecordBuffer record) {
        this(record.getByteBuffer().array(), 0, record.getRecordBufferSize());
    }

    public RecordBuffer(byte[] recordBytes, int offset, int length) {
        Preconditions.checkArgument(length > 0);
        this.recordByteBufferSize = length;
        this.recordByteBuffer = ByteBuffer.allocate(length);
        this.recordByteBuffer.put(recordBytes, offset, length);
    }

    public void wrap(byte[] recordBytes, int offset, int length) {
        Preconditions.checkArgument(length > 0);
        this.recordByteBufferSize = length;
        this.recordByteBuffer = ByteBuffer.wrap(recordBytes, offset, length);
    }

    /**
     * FIXME is it right, always?
     * @return the recordBufferSize
     */
    public int getRecordBufferSize() {
        return this.recordByteBufferSize;
    }

    /**
     * @return the recordBuffer
     */
    public ByteBuffer getByteBuffer() {
        return recordByteBuffer;
    }

    public void clear() {
        this.recordByteBuffer = null;
        this.recordByteBufferSize = 0;
    }

    @Override
    public void readFields(DataInput in) throws IOException {
        this.recordByteBufferSize = in.readInt();
        if (this.recordByteBuffer == null || this.recordByteBufferSize > this.recordByteBuffer.capacity()) {
            this.recordByteBuffer = ByteBuffer.allocate(this.recordByteBufferSize);
        } else {
            this.recordByteBuffer.clear();
        }

        in.readFully(this.recordByteBuffer.array(), 0, this.recordByteBufferSize);
    }

    @Override
    public void write(DataOutput out) throws IOException {
        out.writeInt(this.recordByteBufferSize);
        out.write(this.recordByteBuffer.array(), 0, this.recordByteBufferSize);
    }

}