/*
* 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 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.channels.FileChannel;
import java.nio.channels.ReadableByteChannel;
import javax.annotation.concurrent.NotThreadSafe;
/**
* This class provides read access to a block data file locally stored in managed storage.
*/
@NotThreadSafe
public final class LocalFileBlockReader implements BlockReader {
private final String mFilePath;
private final RandomAccessFile mLocalFile;
private final FileChannel mLocalFileChannel;
private final Closer mCloser = Closer.create();
private final long mFileSize;
private boolean mClosed;
/**
* Constructs a Block reader given the file path of the block.
*
* @param path file path of the block
*/
public LocalFileBlockReader(String path) throws IOException {
mFilePath = Preconditions.checkNotNull(path);
mLocalFile = mCloser.register(new RandomAccessFile(mFilePath, "r"));
mFileSize = mLocalFile.length();
mLocalFileChannel = mCloser.register(mLocalFile.getChannel());
}
@Override
public ReadableByteChannel getChannel() {
return mLocalFileChannel;
}
@Override
public long getLength() {
return mFileSize;
}
/**
* @return the file path
*/
public String getFilePath() {
return mFilePath;
}
@Override
public ByteBuffer read(long offset, long length) throws IOException {
Preconditions.checkArgument(offset + length <= mFileSize,
"offset=%s, length=%s, exceeding fileSize=%s", offset, length, mFileSize);
// TODO(calvin): May need to make sure length is an int.
if (length == -1L) {
length = mFileSize - offset;
}
return mLocalFileChannel.map(FileChannel.MapMode.READ_ONLY, offset, length);
}
@Override
public int transferTo(ByteBuf buf) throws IOException {
return buf.writeBytes(mLocalFileChannel, buf.writableBytes());
}
@Override
public void close() throws IOException {
if (mClosed) {
return;
}
try {
mCloser.close();
} finally {
mClosed = true;
}
}
@Override
public boolean isClosed() {
return mClosed;
}
}