alluxio.worker.dora

Class PagedFileReader

java.lang.Object

alluxio.worker.block.io.BlockClient

alluxio.worker.block.io.BlockReader

alluxio.worker.dora.PagedFileReader

All Implemented Interfaces:

PositionReader, Closeable, AutoCloseable

public class PagedFileReader
extends BlockReader
implements PositionReader

Paged file reader.

Nested Class Summary

Nested classes/interfaces inherited from class alluxio.worker.block.io.BlockClient

BlockClient.Type

Constructor Summary

Constructors

Constructor and Description
PagedFileReader(LocalCachePositionReader localCachePositionReader, long fileSize, long startPosition) Constructor.

Method Summary

Modifier and Type	Method and Description
void	close() Closes the positon reader and do cleanup job if any.
static PagedFileReader	create(AlluxioConfiguration conf, CacheManager cacheManager, UnderFileSystem ufs, String fileId, String ufsPath, long fileSize, long startPosition) Creates a new PagedFileReader.
ReadableByteChannel	getChannel() Returns a readable byte channel of the block.
long	getLength() Gets the length of the block in bytes.
String	getLocation()
CompositeDataBuffer	getMultipleDataFileChannel(io.netty.channel.Channel channel, long length) Get a CompositeDataBuffer which has a list of DataFileChannel.
boolean	isClosed()
ByteBuffer	read(long offset, long length) Reads data from the block.
int	readInternal(long position, ReadTargetBuffer buffer, int length)
int	transferTo(io.netty.buffer.ByteBuf buf) Transfers data (up to buf.writableBytes()) from this reader to the buffer.

Methods inherited from class alluxio.worker.block.io.BlockClient

toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface alluxio.PositionReader

read, read, read, read, read

Constructor Detail

PagedFileReader

public PagedFileReader(LocalCachePositionReader localCachePositionReader,
                       long fileSize,
                       long startPosition)

Constructor.

Parameters:

localCachePositionReader -

fileSize -

startPosition -

Method Detail

create

public static PagedFileReader create(AlluxioConfiguration conf,
                                     CacheManager cacheManager,
                                     UnderFileSystem ufs,
                                     String fileId,
                                     String ufsPath,
                                     long fileSize,
                                     long startPosition)

Creates a new PagedFileReader.

Parameters:

conf -

cacheManager -

ufs -

fileId -

ufsPath -

fileSize -

startPosition -

Returns:

a new PagedFileReader

getMultipleDataFileChannel

public CompositeDataBuffer getMultipleDataFileChannel(io.netty.channel.Channel channel,
                                                      long length)
                                               throws IOException

Get a CompositeDataBuffer which has a list of DataFileChannel.

Parameters:

channel - the Channel object which is used for allocating ByteBuf

length - the bytes to read

Returns:

CompositeDataBuffer

Throws:

IOException

read

public ByteBuffer read(long offset,
                       long length)
                throws IOException

Description copied from class: BlockReader

Reads data from the block.

Implementation Note

Since this method needs to allocate a buffer inside its implementation, it must not choose a ByteBuffer that needs any kind of explicit de-allocation, e.g. a pooled buffer, because the caller has no means of knowing how and when to properly deallocate the returned buffer.
If explicit de-allocation is desired, use an externally allocated ByteBuf and call BlockReader.transferTo(ByteBuf) instead. It is then the caller's responsibility to de-allocate the buffer.

Specified by:

read in class BlockReader

Parameters:

offset - the offset from starting of the block file in bytes

length - the length of data to read in bytes. If offset + length exceeds the block size, the part of data from offset to the end of block is returned.

Returns:

ByteBuffer the data that was read, empty buffer if offset is at the end of block

Throws:

IOException

getLength

public long getLength()

Description copied from class: BlockReader

Gets the length of the block in bytes.

Specified by:

getLength in class BlockReader

Returns:

the length of the block in bytes

getChannel

public ReadableByteChannel getChannel()

Description copied from class: BlockReader

Returns a readable byte channel of the block.

Specified by:

getChannel in class BlockReader

Returns:

channel

transferTo

public int transferTo(io.netty.buffer.ByteBuf buf)
               throws IOException

Description copied from class: BlockReader

Transfers data (up to buf.writableBytes()) from this reader to the buffer.

Specified by:

transferTo in class BlockReader

Parameters:

buf - the byte buffer

Returns:

the number of bytes transferred, -1 if the end of the block is reached

Throws:

IOException

readInternal

public int readInternal(long position,
                        ReadTargetBuffer buffer,
                        int length)
                 throws IOException

Specified by:

readInternal in interface PositionReader

Parameters:

position - position of the file to start reading data

buffer - target byte buffer

length - bytes to read

Returns:

bytes read, or -1 none of data is read

Throws:

IOException

close

public void close()
           throws IOException

Description copied from interface: PositionReader

Closes the positon reader and do cleanup job if any.

Specified by:

close in interface PositionReader

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Overrides:

close in class BlockClient

Throws:

IOException

isClosed

public boolean isClosed()

Specified by:

isClosed in class BlockReader

Returns:

true if this reader is closed

getLocation

public String getLocation()

Specified by:

getLocation in class BlockReader

Returns:

an informational string of the location the reader is reading from