org.apache.hama.bsp.message.io.SyncReadByteBufferInputStream.java Source code

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Here is the source code for org.apache.hama.bsp.message.io.SyncReadByteBufferInputStream.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.hama.bsp.message.io;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * A {@link ByteBuffer} input stream that synchronously reads from spilled data.
 * Uses {@link DuplexByteArrayChannel} within.
 */
public class SyncReadByteBufferInputStream extends ByteBufferInputStream {

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

    private boolean spilled;
    private FileChannel fileChannel;
    private long fileBytesToRead;
    private long fileBytesRead;
    private DuplexByteArrayChannel duplexChannel = new DuplexByteArrayChannel();

    public SyncReadByteBufferInputStream(boolean isSpilled, String fileName) {
        spilled = isSpilled;
        if (isSpilled) {
            RandomAccessFile f;
            try {
                f = new RandomAccessFile(fileName, "r");
                fileChannel = f.getChannel();
                fileBytesToRead = fileChannel.size();
            } catch (FileNotFoundException e) {
                LOG.error("File not found initializing Synchronous Input Byte Stream", e);
                throw new RuntimeException(e);
            } catch (IOException e) {
                LOG.error("Error initializing Synchronous Input Byte Stream", e);
                throw new RuntimeException(e);
            }

        }
    }

    private void feedDataFromFile() throws IOException {
        int toReadNow = (int) Math.min(buffer.capacity(), fileBytesToRead);
        fileChannel.transferTo(fileBytesRead, toReadNow, duplexChannel);
        fileBytesRead += toReadNow;
        fileBytesToRead -= toReadNow;
        duplexChannel.flip();
    }

    @Override
    public void setBuffer(ByteBuffer buffer, long toRead, long total) throws IOException {
        this.buffer = buffer;
        duplexChannel.setBuffer(buffer);
        if (spilled) {
            feedDataFromFile();
        }
        super.setBuffer(buffer, fileBytesToRead, fileBytesToRead);

    }

    @Override
    protected int onBufferRead(byte[] b, int off, int len, int cur) throws IOException {

        if (fileBytesToRead == 0) {
            return cur == 0 ? -1 : cur;
        }

        if (spilled) {
            buffer.clear();
            feedDataFromFile();
        }
        return cur += read(b, off, len);
    }

}