org.apache.hadoop.mapred.nativetask.handlers.BufferPuller.java Source code

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Here is the source code for org.apache.hadoop.mapred.nativetask.handlers.BufferPuller.java

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/**
 * 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.mapred.nativetask.handlers;

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

import org.apache.commons.io.IOUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.io.DataInputBuffer;
import org.apache.hadoop.mapred.RawKeyValueIterator;
import org.apache.hadoop.mapred.nativetask.Constants;
import org.apache.hadoop.mapred.nativetask.DataReceiver;
import org.apache.hadoop.mapred.nativetask.NativeDataSource;
import org.apache.hadoop.mapred.nativetask.buffer.BufferType;
import org.apache.hadoop.mapred.nativetask.buffer.ByteBufferDataReader;
import org.apache.hadoop.mapred.nativetask.buffer.InputBuffer;
import org.apache.hadoop.util.Progress;

/**
 * actively signal a {@link BufferPullee} to load data into buffer and receive
 */
@InterfaceAudience.Private
public class BufferPuller implements RawKeyValueIterator, DataReceiver {

    private static Log LOG = LogFactory.getLog(BufferPuller.class);

    public final static int KV_HEADER_LENGTH = Constants.SIZEOF_KV_LENGTH;

    byte[] keyBytes = new byte[0];
    byte[] valueBytes = new byte[0];

    private InputBuffer inputBuffer;
    private InputBuffer asideBuffer;

    int remain = 0;

    private ByteBufferDataReader nativeReader;

    DataInputBuffer keyBuffer = new DataInputBuffer();
    DataInputBuffer valueBuffer = new DataInputBuffer();

    private boolean noMoreData = false;

    private NativeDataSource input;
    private boolean closed = false;

    public BufferPuller(NativeDataSource handler) throws IOException {
        this.input = handler;
        this.inputBuffer = handler.getInputBuffer();
        nativeReader = new ByteBufferDataReader(null);
        this.asideBuffer = new InputBuffer(BufferType.HEAP_BUFFER, inputBuffer.capacity());
    }

    @Override
    public DataInputBuffer getKey() throws IOException {
        return keyBuffer;
    }

    @Override
    public DataInputBuffer getValue() throws IOException {
        return valueBuffer;
    }

    public void reset() {
        noMoreData = false;
    }

    @Override
    public boolean next() throws IOException {
        if (closed) {
            return false;
        }

        if (noMoreData) {
            return false;
        }
        final int asideRemain = asideBuffer.remaining();
        final int inputRemain = inputBuffer.remaining();

        if (asideRemain == 0 && inputRemain == 0) {
            input.loadData();
        }

        if (asideBuffer.remaining() > 0) {
            return nextKeyValue(asideBuffer);
        } else if (inputBuffer.remaining() > 0) {
            return nextKeyValue(inputBuffer);
        } else {
            noMoreData = true;
            return false;
        }
    }

    private boolean nextKeyValue(InputBuffer buffer) throws IOException {
        if (closed) {
            return false;
        }

        nativeReader.reset(buffer);

        final int keyLength = nativeReader.readInt();
        if (keyBytes.length < keyLength) {
            keyBytes = new byte[keyLength];
        }

        final int valueLength = nativeReader.readInt();
        if (valueBytes.length < valueLength) {
            valueBytes = new byte[valueLength];
        }

        IOUtils.readFully(nativeReader, keyBytes, 0, keyLength);
        IOUtils.readFully(nativeReader, valueBytes, 0, valueLength);

        keyBuffer.reset(keyBytes, keyLength);
        valueBuffer.reset(valueBytes, valueLength);

        return true;
    }

    @Override
    public boolean receiveData() throws IOException {
        if (closed) {
            return false;
        }

        final ByteBuffer input = inputBuffer.getByteBuffer();

        if (null != asideBuffer && asideBuffer.length() > 0) {
            if (asideBuffer.remaining() > 0) {
                final byte[] output = asideBuffer.getByteBuffer().array();
                final int write = Math.min(asideBuffer.remaining(), input.remaining());
                input.get(output, asideBuffer.position(), write);
                asideBuffer.position(asideBuffer.position() + write);
            }

            if (asideBuffer.remaining() == 0) {
                asideBuffer.position(0);
            }
        }

        if (input.remaining() == 0) {
            return true;
        }

        if (input.remaining() < KV_HEADER_LENGTH) {
            throw new IOException("incomplete data, input length is: " + input.remaining());
        }
        final int position = input.position();
        final int keyLength = input.getInt();
        final int valueLength = input.getInt();
        input.position(position);
        final int kvLength = keyLength + valueLength + KV_HEADER_LENGTH;
        final int remaining = input.remaining();

        if (kvLength > remaining) {
            if (null == asideBuffer || asideBuffer.capacity() < kvLength) {
                asideBuffer = new InputBuffer(BufferType.HEAP_BUFFER, kvLength);
            }
            asideBuffer.rewind(0, kvLength);

            input.get(asideBuffer.array(), 0, remaining);
            asideBuffer.position(remaining);
        }
        return true;
    }

    @Override
    public Progress getProgress() {
        return null;
    }

    /**
     * Closes the iterator so that the underlying streams can be closed.
     */
    @Override
    public void close() throws IOException {
        if (closed) {
            return;
        }
        if (null != nativeReader) {
            nativeReader.close();
        }
        closed = true;
    }
}