alluxio.worker.block.io.LocalFileBlockWriter.java Source code

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Here is the source code for alluxio.worker.block.io.LocalFileBlockWriter.java

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/*
 * The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
 * (the "License"). You may not use this work except in compliance with the License, which is
 * available at www.apache.org/licenses/LICENSE-2.0
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied, as more fully set forth in the License.
 *
 * See the NOTICE file distributed with this work for information regarding copyright ownership.
 */

package alluxio.worker.block.io;

import alluxio.util.io.BufferUtils;

import com.google.common.base.Preconditions;
import com.google.common.io.Closer;
import io.netty.buffer.ByteBuf;

import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.GatheringByteChannel;

import javax.annotation.concurrent.NotThreadSafe;

/**
 * This class provides write access to a temp block data file locally stored in managed storage.
 */
@NotThreadSafe
public final class LocalFileBlockWriter implements BlockWriter {
    private final String mFilePath;
    private final RandomAccessFile mLocalFile;
    private final FileChannel mLocalFileChannel;
    private final Closer mCloser = Closer.create();
    private long mPosition;
    private boolean mClosed;

    /**
     * Constructs a Block writer given the file path of the block.
     *
     * @param path file path of the block
     * @throws IOException if its file can not be open with "rw" mode
     */
    public LocalFileBlockWriter(String path) throws IOException {
        mFilePath = Preconditions.checkNotNull(path);
        mLocalFile = mCloser.register(new RandomAccessFile(mFilePath, "rw"));
        mLocalFileChannel = mCloser.register(mLocalFile.getChannel());
    }

    @Override
    public GatheringByteChannel getChannel() {
        return mLocalFileChannel;
    }

    @Override
    public long append(ByteBuffer inputBuf) throws IOException {
        long bytesWritten = write(mLocalFileChannel.size(), inputBuf.duplicate());
        mPosition += bytesWritten;
        return bytesWritten;
    }

    @Override
    public void transferFrom(ByteBuf buf) throws IOException {
        mPosition += buf.readBytes(mLocalFileChannel, buf.readableBytes());
    }

    @Override
    public long getPosition() {
        return mPosition;
    }

    @Override
    public void close() throws IOException {
        if (mClosed) {
            return;
        }
        mClosed = true;

        mCloser.close();
        mPosition = -1;
    }

    /**
     * Writes data to the block from an input {@link ByteBuffer}.
     *
     * @param offset starting offset of the block file to write
     * @param inputBuf {@link ByteBuffer} that input data is stored in
     * @return the size of data that was written
     * @throws IOException if an I/O error occurs
     */
    private long write(long offset, ByteBuffer inputBuf) throws IOException {
        int inputBufLength = inputBuf.limit() - inputBuf.position();
        MappedByteBuffer outputBuf = mLocalFileChannel.map(FileChannel.MapMode.READ_WRITE, offset, inputBufLength);
        outputBuf.put(inputBuf);
        int bytesWritten = outputBuf.limit();
        BufferUtils.cleanDirectBuffer(outputBuf);
        return bytesWritten;
    }
}