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

Introduction

Here is the source code for org.apache.hama.bsp.message.io.DualChannelByteBufferStream.java

Source

/**
 * 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.File;
import java.io.IOException;
import java.math.BigInteger;
import java.nio.ByteBuffer;
import java.security.SecureRandom;

import org.apache.hadoop.conf.Configuration;
import org.apache.hama.Constants;

/**
 * A synchronous i/o stream that is used to write data into and to read back the
 * written data.
 */
public class DualChannelByteBufferStream {

    private DirectByteBufferOutputStream outputBuffer;
    private SyncFlushByteBufferOutputStream outputStream;
    private DirectByteBufferInputStream inputBuffer;
    private SyncReadByteBufferInputStream inputStream;

    private String fileName;

    private ByteBuffer buffer;
    private boolean outputMode;
    private boolean inputMode;

    public void init(Configuration conf) {

        boolean directAlloc = conf.getBoolean(Constants.BYTEBUFFER_DIRECT, Constants.BYTEBUFFER_DIRECT_DEFAULT);
        int size = conf.getInt(Constants.BYTEBUFFER_SIZE, Constants.BUFFER_DEFAULT_SIZE);
        if (directAlloc) {
            buffer = ByteBuffer.allocateDirect(size);
        } else {
            buffer = ByteBuffer.allocateDirect(size);
        }
        fileName = conf.get(Constants.DATA_SPILL_PATH) + File.separatorChar
                + new BigInteger(128, new SecureRandom()).toString(32);
        outputMode = true;
        outputStream = new SyncFlushByteBufferOutputStream(fileName);
        outputBuffer = new DirectByteBufferOutputStream(outputStream);
        outputStream.setBuffer(buffer);

    }

    public DirectByteBufferOutputStream getOutputStream() {
        return outputBuffer;
    }

    public void closeOutput() throws IOException {
        if (outputMode) {
            outputBuffer.close();
        }
        outputMode = false;
    }

    public void close() throws IOException {
        closeInput();
        closeOutput();
    }

    public boolean prepareRead() throws IOException {
        outputStream.close();
        outputMode = false;
        buffer.clear();
        inputStream = new SyncReadByteBufferInputStream(outputStream.isSpilled(), fileName);
        inputBuffer = new DirectByteBufferInputStream(inputStream);
        inputBuffer.setBuffer(buffer);
        inputMode = true;
        return true;
    }

    public DirectByteBufferInputStream getInputStream() {
        return inputBuffer;
    }

    public void closeInput() throws IOException {
        if (inputMode) {
            inputBuffer.close();
        }
        inputMode = false;
    }

}